TasWater - EPA Websiteepa.tas.gov.au/Documents/TasWater, Blackmans Bay Sewage... · 2016-11-16 · The Project Proponent is Taswater, the State’s water authority. Approvals Process

TasWater

Blackmans Bay STP

DPEMP

August 2016

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | i

Executive Summary

The proposed Project is an upgrade of the existing Blackmans Bay Sewage Treatment Plant

(STP), located on the western shore of the lower Derwent Estuary off Tinderbox Road, at the

end of Treatment Plant Road (south of the main suburban area of Blackmans Bay).

The upgrade will involve both an increase in capacity of the plant as well as improved overall

effluent treatment to improve the quality of water discharged to the Derwent Estuary and meet

EPA compliance requirements. It will also improve odour and noise for local residents.

The upgrade will benefit the Kingborough area, both now and for future generations, by allowing

TasWater to improve performance and capacity of the Blackmans Bay STP and facilitate the

consolidation of the Kingborough sewerage system to accommodate growth in the area and

centralise waste from local catchments. This will allow TasWater to close underperforming STPs

at Electrona, Margate and Howden in the future. A key driving factor for the amalgamation of

STPs at Electrona, Margate and Howden is the long term benefits to North West Bay by

removing wastewater discharges from these STPs.

Project Overview

At its core the upgrade will address deficiencies with the current STP to meet emission limits

and manage odour impacts to the surrounding environment as well as catering for projected

increases in sewage flow to the to the Blackmans Bay STP from the immediate catchment. The

Blackmans Bay STP is part of Tasmania’s wastewater infrastructure and maintaining its ability

to cater for current and projected loads without prejudicing emission limits or public amenity is a

core requirement for ongoing public infrastructure in the region. In addition to immediate

catchment pressures; the upgrade has been planned in the context of a strategic rationalisation

of STPs in the broader area and will be designed to cater for current and projected future loads

from the ageing Margate, Electrona and Howden STPs, which are planned to be

decommissioned. The decommissioning of these plants and the subsequent new influent

pipework transferring the loads from these catchments to the Project are excluded from this

application.

The Project aims to significantly improve plant performance to the Tasmanian EPA’s Accepted

Modern Technology (AMT) performance criteria (with some alteration to phosphorus and

nitrogen treatment criteria) and to meet the capacity requirements of projected sewage volumes

based on a 2040 population growth horizon for the aforementioned catchments.

The upgrade includes the conversion of the existing Blackmans Bay activated sludge system

STP with a current design capacity of 4.125 ML/day to an Intermittently Decanted Extended

Aeration - Sequential Batch Reactor (IDEA-SBR) system with an Average Dry Weather Flow

(ADWF) design capacity of 8.53 ML/day.

The Project Proponent is Taswater, the State’s water authority.

Approvals Process

Schedule 2 of the Environmental Management and Pollution Control Act 1994 (EMPCA), states

that Level 2 approval is required for wastewater treatment and disposal of more than 100 kL/day

(average dry weather flow) of effluent. As the Project aims to treat a maximum ADWF of 8.53

ML/day, it is above the Scheduled Level 2 limit and therefore the Project needs to obtain

approval to operate under the Land Use Planning and Approvals Act 1993 and EMPCA as a

Level 2 activity.

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | ii

A Notice of Intent (NOI) was submitted to the Tasmanian EPA in 2014, seeking confirmation of

the level of approval and seeking Project Specific Guidelines. The EPA determined the project

to be a Level 2B assessment and Project Specific Guidelines were issued.

The resulting approval pathway for the Project is the submission of a Development Proposal

and Environmental Management Plan (DPEMP – this document) and associated development

application (DA) to Kingborough Council, which is subsequently referred to the EPA Board for

joint assessment and approval.

The DA and associated DPEMP are then advertised for public comment and representation.

Any comments received are taken into consideration during the Council and EPA assessment

process. Once a determination has been made by the EPA Board and the Council a permit may

be issued (if approved) with conditions (if required) and an appeals period applies before the

approval comes into effect.

In the approvals process this DPEMP forms the key document by which agencies and the public

can obtain an understanding of the Project and its potential impacts, benefits and commitments

to management actions.

Community consultation prior to submission of the DPEMP to Kingborough Council will also

provide the public with an understanding of the Project’s impacts and benefits, along with

TasWater’s commitment to manage both construction and operation.

No significant impacts are expected to occur to Matters of National Environmental Significance

as a result of the Project, as has been determined through relevant studies. Therefore, the

project has not been referred to the Commonwealth under the Environment Protection

Biodiversity Conservation Act 1999 (EPBC Act).

Project Site

The Site is within a relatively large parcel of land (surrounding the existing STP site) which is

currently owed by Kingborough Council and used as a buffer for the existing STP and for

recreational walking by the local community. TasWater has entered into an agreement with

Kingborough Council to purchase that parcel of land which will continue to be used for its

current purpose and to accommodate the expansion of the Project. The combined parcels of

land (existing STP site and surrounding Council owned parcel to be acquired by TasWater) form

the combined ‘Project Site’ for this application (i.e. ‘The Land’).

The Project Site is bounded to the north by medium density residential development, to the west

by low density residential development, to the south by a Council owned land parcel

(predominantly bushland used for walking and dog exercise) and to the east by the Derwent

Estuary. The Project Site slopes from west to east, towards the estuary, and contains two small

drainage lines immediately to the north and south of the existing STP.

The development footprint (Project Footprint) is within and adjacent to the existing STP and

therefore contains partially disturbed land, as well as undisturbed land. The Project Footprint

contains a small number of mature eucalypt trees and other small native species but is

otherwise dominated by exotic grasses and already disturbed areas.

Key Impacts and Mitigation

The proposed Project involves upgrades and expansion to an existing site (for the majority of

the Project Footprint), therefore many of the impacts normally associated with a new STP are

lessened in this case as the site is already utilised for that purpose. The expansion does,

however, pose a number of key changes to onsite and offsite impacts, summarised as follows

(details provided in the body of this DPEMP):

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | iii

The Project design will result in significant improvements to treated effluent quality across

almost all parameters. Nitrogen and ammonia in particular will be treated to a much lower

level under the new arrangements than is achieved by the existing STP. The Project design

will also provide greater reliability of treatment and capacity to cater for upset and storm

conditions, providing a significant treatment improvement over the current plant. The

proposal does however also involve a gradual increase in discharge flows as a result of

growth in the area as well as catering for existing Margate, Electrona and Howden sewage

flows in the event these plants are decommissioned and redirected to Blackmans Bay.

An assessment has been made of the increased effluent flows from the Project into the

Derwent Estuary. This assessment found that the existing mixing zone (for the current

plant) is sufficient for complete mixing of toxicants to ambient concentrations at the Project

design capacity, therefore no expansion of the existing STP effluent mixing zone is needed.

The assessment also found residual risks of eutrophication, algal blooms and impacts to

human health and marine ecosystems are limited as a result of the relatively high treated

effluent quality, the nature of the outfall site (no threatened species) and the exposed

nature of the discharge environment (i.e. large estuary mouth, rather than a confined river

or bay). The Project does have potential to impact on a local giant kelp forest by reducing

current effluent nutrient loads. This is considered further in the body of the DPEMP.

An associated benefit of the upgraded plant to the marine environment is the potential

facilitation of the removal of treated effluent from the constrained environment of North

West Bay through the provision of sufficient treatment capacity to cater for future loads from

Margate, Electrona and Howden plants (currently discharging into North West Bay) which

can be decommissioned.

The proposal involves some clearance of mature eucalypt species and a very small area of

a threatened vegetation community but is predominantly focused on already disturbed land.

TasWater has commitment to a landscaping program replacing all mature eucalypts

removed with new trees at a ratio of 3 to 1. Residual impacts to native flora and fauna are

considered low.

An assessment of odour impact from the new plant illustrated compliance with the relevant

legislation and shows the 2 odour unit contained within the Project Site on al l occasions bar

a simulated “worst-case scenario”. Odour impacts from the Project are expected to be

greatly reduced in comparison to the current plant.

An assessment of noise impacts from the Project showed compliance with the adopted

criteria under all normal operating conditions. Noise during emergency power generation

scenarios and the construction period were assessed against different criteria (due to the

short-term nature of these impacts and the lack of night time work in the case of

construction) and found to be compliant.

The Project will involve some additional visual intrusion for nearby residents, but is cut into

the existing bank considerably, will be painted to blend into the existing environment, is

similar in nature to the existing STP and will be screened by proposed landscaping from

most angles. With these measures in place overall visual intrusion is expected to be limited.

Conclusion

Overall the Project offers a significant improvement in wastewater treatment capacity, quality

and reliability and poses a relatively small number of environmental and social impacts .

Treatment plant upgrades and expansions are an essential part of maintaining the State’s

wastewater assets for current and projected population growth and the Blackmans Bay sit e has

been carefully selected and designed to minimise impacts as far as practical whilst allowing the

provision of long term wastewater treatment in the Kingborough Local Government Area.

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | iv

Acronyms

AADT Annual average daily traffic Kl Kilolitre

ABS Australian Bureau of Statistics kWh Kilowatt hour

ADCP Acoustic doppler current profiler LAeq Equivalent sound level (weighted)

ADWF Average dry weather flow LAmax Maximum sound level (weighted)

ADWG Australian Drinking Water Guidelines

LGA Local government area

AER Annual Environmental Report LUPAA Land Use Planning and Approvals Act 1993

AHD Australian Height Datum L/S Litres per second

AHT Aboriginal Heritage Tasmania M Million

AMT Accepted modern technology MBR Membrane bioreactor

ANZECC Australian and New Zealand Environment Conservation Council

MCC Motor Control Cabinet

AS Australian Standard ML Megalitre

AS/NZS Australian New Zealand Standard ML/d Megalitre per day

BOD Biological oxygen demand MNES Matters of National Environmental Significance

BTF Bio-trickling filter NEPM National Environmental Protection Measures

C Celsius NGERS National Greenhouse

and Energy Reporting Scheme

CEMP Construction Environmental Management Plan

NMPM Noise Measurement Procedures Manual

CFEV Conservation of Freshwater Ecosystem Values

NO. Number

CFU Colony forming unit NOI Notice of Intent

CMM Contingency Management Manual NTU Nephelometric turbidity unit

COD Chemical oxygen demand NHMRC National Health and

Medical Research Council

DA Development Application NRMMC National Resource

Management Ministerial Council

DB Decibel NWP National Waste Policy 2009

DBA Decibel (weighted) OEMP Operational Environmental Management Plan

DBH Diameter at breast height O&M Operation and maintenance

DEP Derwent Estuary Program OMP Operational Management Plan

DFCS Design for Construction Safety OU Odour unit

DOTF Department of Treasury and Finance

PEV Protected Environmental Value

DPEMP Development Proposal and Environmental Management Plan

PLC Programmable logic controller

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | v

DPIPWE Department of Primary Industries, Parks, Water and the Environment

PSU Practical salinity unit

DTA Direct toxicity assessment RAS Return activated sludge

ELG Emission Limit Guidelines for Sewage Treatment Plants that Discharge Pollutants in Fresh and Marine Waters 2001

SBR Sequential batch reactor

EMP Environmental Management Plan SOER Specific Odour Emission Rates

EMPCA Environmental Management and Pollution Control Act 1994

SPS Sewage pump station

EMPCR Environmental Management and Pollution Control Regulations 2014

SSMP Sewage Sludge Management Plan

EMZ Environmental Management Zone STP Sewage treatment plant

EPA Environment Protection Authority SWL Sound power level

EPBC Act Environment Protection and Biodiversity Conservation Act 1999

SWMP Soil and Water Management Plan

EPN Environmental Protection Notice RMPS Resource Management and Planning System

EPP Environmental Protection Policy 2004

t Tonnes

GFA Gross floor area tCO2-e/annum

Tonnes of equivalent CO2 per annum

ha Hectare TDS Total dissolved solids

hr Hour THC Tasmanian Heritage Council

HSMP Health and Safety Management Plan

TJ/annum Terajoules per annum

H2S Hydrogen sulphide TSPA Tasmanian Threatened Species Protection Act 1995

Hz Hertz TSS Total suspended solids

IBC Intermediate bulk container TW TasWater

IDEA-SBR Intermittently decanted extended aeration – sequential batch reactor

µg Microgram

ITP Inspection and test plans UV Ultraviolet

Kg Kilogram VOCs Volatile organic compounds

KHz Kilohertz WAS Waste activated sludge

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | vi

Table of contents

1. Introduction..................................................................................................................................... 1

1.1 Title of Proposal ................................................................................................................... 1

1.2 Proponent ............................................................................................................................ 1

1.3 Proposal Background........................................................................................................... 1

1.4 Legislative Framework ......................................................................................................... 2

2. Proposal Description ...................................................................................................................... 3

2.1 Project Overview .................................................................................................................. 3

2.2 Location and Site Context .................................................................................................... 4

2.3 Project Rationale and Context ............................................................................................. 8

2.4 Project Design Parameters ................................................................................................ 13

2.5 Sewage Treatment Plant Design ....................................................................................... 18

2.6 Operational Parameters ..................................................................................................... 25

2.7 Pre-Construction and Construction .................................................................................... 28

2.8 Commissioning .................................................................................................................. 32

2.9 Off-Site Infrastructure......................................................................................................... 34

2.10 Land Tenure and Public Site Access ................................................................................. 35

3. Project Alternatives ...................................................................................................................... 37

3.1 Project Rationale ................................................................................................................ 37

3.2 Alternative STP Sites ......................................................................................................... 37

3.3 Reuse Investigations.......................................................................................................... 38

3.4 Layout at the Blackmans Bay STP Site ............................................................................. 40

3.5 Alternative Treatment Plant Technology............................................................................ 41

4. Public Consultation ...................................................................................................................... 43

4.1 Stakeholder and Community Engagement Plan ................................................................ 43

4.2 Key Stakeholders Engaged ............................................................................................... 43

4.3 Key Engagement Tools...................................................................................................... 44

4.4 Summary of Feedback Received ....................................................................................... 44

4.5 Future Consultation ............................................................................................................ 44

5. Existing Environment ................................................................................................................... 45

5.1 Planning Aspects and Land Tenure ................................................................................... 45

5.2 Environmental Aspects ...................................................................................................... 51

5.3 Socio-economic Aspects ................................................................................................... 54

6. Existing Conditions, Potential Effects and Management ............................................................. 56

6.1 Air Quality .......................................................................................................................... 56

6.2 Surface Water Quality ........................................................................................................ 67

6.3 Groundwater ...................................................................................................................... 70

6.4 Noise Emissions ................................................................................................................ 73

6.5 Waste Management ........................................................................................................... 82

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | vii

6.6 Dangerous Goods and Environmentally Hazardous Materials .......................................... 85

6.7 Biodiversity and Natural Values ......................................................................................... 90

6.8 Marine and Coastal ............................................................................................................ 99

6.9 Greenhouse Gases and Ozone Depleting Substances ................................................... 118

6.10 Heritage ........................................................................................................................... 120

6.11 Land Use and Development ............................................................................................ 122

6.12 Visual Impacts .................................................................................................................. 143

6.13 Socio-economic Issues .................................................................................................... 145

6.14 Health and Safety Issues ................................................................................................. 147

6.15 Hazard Analysis and Risk Assessment ........................................................................... 149

6.16 Fire Risk ........................................................................................................................... 155

6.17 Infrastructure and off-site Ancillary Facilities ................................................................... 157

6.18 Environmental Management Systems ............................................................................. 158

6.19 Cumulative and Interactive Impacts ................................................................................. 160

6.20 Traffic Impacts ................................................................................................................. 161

7. EPBC Act Assessment ............................................................................................................... 163

7.1 Background ...................................................................................................................... 163

7.2 Matters of National Environmental Significance .............................................................. 163

7.3 Listed Ecological Communities ........................................................................................ 163

7.4 Listed Threatened Species and Migratory Species ......................................................... 164

8. Monitoring and Review ............................................................................................................... 165

9. Decommissioning and Rehabilitation ......................................................................................... 170

10. Commitments ............................................................................................................................. 171

11. Conclusion.................................................................................................................................. 175

12. Limitations .................................................................................................................................. 176

13. References ................................................................................................................................. 177

Table index

Table 2-1 Flow Characteristics at Existing STPs for 1 July 2014 – 30 June 2015 .............................. 9

Table 2-2 Effluent Quality Data for the 1 July 2014 – 30 June 2015 Reporting Period (from

Submitted 2014-15 AERs) ................................................................................................. 11

Table 2-3 Existing Mass Loads .......................................................................................................... 12

Table 2-4 Trade Waste Volumes accepted from 1 July - 30 June 2015 at Blackmans Bay,

Margate and Electrona STPs ............................................................................................. 13

Table 2-5 Required Treatment Capacities ......................................................................................... 14

Table 2-6 Design Effluent Performance of Upgraded STP ................................................................ 16

Table 3-1 STP Process Selection Criteria ......................................................................................... 41

Table 5-1 Land Title Details - Development Site ............................................................................... 46

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | viii

Table 5-2 Land Use Zoning – Location & Description ....................................................................... 49

Table 6-1 Odour Modelling Scenarios ............................................................................................... 60

Table 6-2 Relevant Groundwater PEVs and Water Quality Indicators .............................................. 70

Table 6-3 Noise Criteria for Sensitive Receptors During Operations ................................................ 74

Table 6-4 Noise Criteria for Construction and Emergency Diesel Generation .................................. 75

Table 6-5 Modelled Sound Pressure Levels during Operation .......................................................... 77

Table 6-6 Modelled Sound Pressure Levels during Construction ...................................................... 78

Table 6-7 Vegetation Communities Impacted by the Development................................................... 94

Table 6-8 Upgraded Blackmans Bay Treatment Plant Mass Loads into Derwent Estuary

(median effluent quality)................................................................................................... 107

Table 6-9 Approximate Mass Load Contributions to the Derwent Estuary (median effluent

quality) ............................................................................................................................. 109

Table 6-10 Nitrogenous Compounds Concentration Comparison between Ambient Lower

Derwent Estuary and Outfall Monitoring Sites ................................................................. 112

Table 6-11 Water Quality Monitoring Sites, Parameter Groups and Monitoring Frequency ............. 114

Table 6-12 Water Monitoring Parameters .......................................................................................... 114

Table 6-13 Benthic Infauna Site and Frequency ................................................................................ 115

Table 6-14 Giant Kelp Forest Monitoring Sites .................................................................................. 115

Table 6-15 NGERS Calculations for the Project ................................................................................ 119

Table 6-16 Regulation 11 of the Water and Sewerage (General) Industry Regulations 2009 .......... 123

Table 6-17 Likelihood Ranking with Design Control .......................................................................... 149

Table 6-18 Environmental Consequence Ranking ............................................................................ 150

Table 6-19 Risk Matrix ....................................................................................................................... 150

Table 6-20 Risk Rating Key for Proponent Action and Ultimate Acceptability ................................... 150

Table 6-21 Environmental Hazard Identification and Risk Assessment Outcomes ........................... 151

Table 8-1 Treated Effluent Sampling ............................................................................................... 165

Table 8-2 Receiving Environment Monitoring .................................................................................. 167

Table 10-1 Commitments ................................................................................................................... 171

Figure index

Figure 2-1 Location Map ....................................................................................................................... 5

Figure 2-2 Site Plan ............................................................................................................................... 6

Figure 2-3 Land Tenure and Surrounding Land Use ............................................................................ 7

Figure 2-4 Projected Medium & High Population Growth for Kingborough LGA ................................ 15

Figure 2-5 Process Flow Diagram ....................................................................................................... 19

Figure 2-6 Public Access ..................................................................................................................... 36

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | ix

Figure 5-1 Title Plans .......................................................................................................................... 47

Figure 5-2 Land Use Zoning - Development Site & Surrounds ........................................................... 50

Figure 5-3 Reserves and Geomorphological Features ....................................................................... 53

Figure 5-4 Age and Sex Pyramid for Kingborough (ABS Census, 2006) ........................................... 55

Figure 6-1 Sensitive Receptors considered in Odour Assessment (Source: MWH 2016).................. 58

Figure 6-2 Major odour emission sources modelled (Source: MWH 2016) ........................................ 59

Figure 6-3 Odour Modelling Scenario 1: Normal Operating Conditions (Source: MWH

2016) .................................................................................................................................. 61

Figure 6-4 Odour Modelling Scenario 2: Inlet Works Maintenance (Source: MWH 2016) ................. 62

Figure 6-5 Odour Modelling Scenario 3: Upset in Treatment Process (Source: MWH 2016) ............ 63

Figure 6-6 Odour Modelling Scenario 4: Upset in Sludge Process (Source: MWH 2016).................. 64

Figure 6-7 Noise Sources from Upgraded STP (Source, Vipac 2016) ............................................... 76

Figure 6-8 Residential Locations used for Baseline Noise Assessment (Source, Vipac

2016) .................................................................................................................................. 76

Figure 6-9 Predicted Noise Emission Contours for Normal Operations in Neutral Weather

(Source: Vipac, 2016) ........................................................................................................ 80

Figure 6-10 Predicted Noise Emission Contours for Normal Operations with Temporary

Power Generation in Neutral Weather (Source: Vipac, 2016) ........................................... 81

Figure 6-11 Flora and Ecological Values within STP Footprint ............................................................. 98

Figure 6-12 Modelled 50th and 95th percentile (left and right respectively) tracer

concentrations from the pre-extension Blackmans Bay STP marine outfall over

a 3-month period from December 2003 - March 2004 (from Herzfeld et al, 2005) ......... 110

Figure 6-13 Marine Monitoring Sites ................................................................................................... 117

Figure 6-14 Landslide Hazard Area Overlay & Development Site (Low Landslide Hazard

Area on the Left and Medium Hazard Landslide Area on the Right) ............................... 137

Figure 6-15 Coastal Erosion Hazard Overlay & Development Site .................................................... 141

Appendices

Appendix A - Design Drawings

Appendix B - Ecological Appendices

Appendix C - Sewage Treatment Plant Contingency Management Manual

Appendix D - Near-field Modelling of Effluent

Appendix E - Odour Modelling Report

Appendix F - Noise Modelling Report

Appendix G - Marine Monitoring Reports

Appendix H – EPA Project Specific Guidelines

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107 | 1

1. Introduction

1.1 Title of Proposal

The proposal is referred to as “Blackmans Bay Sewage Treatment Plant Upgrade”.

1.2 Proponent

The proposal proponent is Tasmanian Water and Sewerage Corporation Pty Ltd (TasWater):

TasWater

ACN: 133 654 976

ABN: 47 162 220 653

Australian Private Company

169 Main Road, Moonah, TAS 7009

The contact person for the proponent is:

Lance Stapleton, Department Manager Product Quality

Phone: 0408 175 522 and Email: [email protected]

TasWater is a State Agency responsible for the provision of water, wastewater and recycled

water services throughout Tasmania. TasWater was formed in 2013 from the previous regional

water authorities (Southern Water, Cradle Mountain Water and Ben Lomond Water) and has

over 700 staff. The annual revenue for TasWater is approximately $246 million and annual

capital expenditure of approximately $105 million. Drawing on the combined experience of the

previous water authorities, TasWater owns and operates 113 sewage treatment plants (STPs)

and has the necessary experience in the design and operation of STPs to deliver this Project.

1.3 Proposal Background

1.3.1 Background and Rationale

The existing Blackmans Bay STP has been operating for approximately 30 years, treating

wastewater from the Kingston, Huntingfield, Blackmans Bay and southern Bonnet Hill areas.

Accepted wastewater sources comprise residential, commercial, and to a lesser degree,

industrial.

The current STP operates under the following licence arrangements:

Licence to Operate Scheduled Premises No. 3326 (18/11/1987)

Permit Conditions – Environmental No. 7551 (10/12/2008)

The existing STP treats an average flow of ~4 ML/day, which is approaching the currently

licenced limit (and design capacity) of 4.125 ML/day for average dry weather flow (ADWF).

Effluent quality results in recent years have shown plant performance to be sub-optimal and

odour has been an ongoing issue; this, together with the growing sewage treatment demands

from the current catchment, has highlighted the necessity to upgrade the plant at some point in

the near future.

With the Blackmans Bay STP requiring an upgrade in the near future and TasWater’s parallel

plans to close several underperforming STPs in the Kingborough local government area (LGA),

it was proposed that the sewage catchments from three existing STPs, namely the Margate,

Electrona, and Howden plants could potentially be redirected and amalgamated with the current

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Blackman Bay catchment and directed into the larger upgraded Blackmans Bay STP. A key

driving factor for the amalgamation of STPs at Electrona, Margate and Howden is the long term

benefits to North West Bay by removing wastewater discharges from these underperforming

STPs. The Blackmans Bay STP upgrade has been sized to facilitate this eventuality but is not

contingent upon it and the amalgamation is excluded from this application.

1.3.2 Overview

The proposal is an upgrade of the existing Blackmans Bay Sewage Treatment Plant (the

Project), located on the western shore of the lower Derwent Estuary off Tinderbox Road, at the

end of Treatment Plant Road (south of the main suburban area of Blackmans Bay). The

upgrade will involve both an increase in capacity of the plant as well as improved overall effluent

treatment.

The proposed Project will be designed to cater for current and projected future flows (up to a

~2040 design horizon) for the current Blackmans Bay STP catchment as well as potentially the

wastewater catchments currently serviced by the Electrona, Margate and Howden STPs (which

will eventually be decommissioned under a separate approval process). The transfer of

wastewater from the other three STPs to the Project is outside of the scope of this application.

The Project is anticipated to cost in the vicinity of $30-40 million, with a 24-month construction

period followed by a six-month commissioning period. The project is currently in the design

phase, with construction work aimed to commence as soon as all necessary approvals have

been sought and obtained.

1.4 Legislative Framework

Schedule 2 of the Environmental Management and Pollution Control Act 1994 (EMPCA), states

that Level 2 approval is required for wastewater treatment and disposal of more than 100 kL/day

(ADWF) of effluent. As the Project aims to treat a maximum ADWF of 8.53 ML/day, it is above

the Scheduled Level 2 limit and therefore the Project needs to obtain approval to operate under

the Land Use Planning and Approvals Act 1993 (LUPAA) and EMPCA as a Level 2 activity.

To this effect a Notice of Intent (NOI) was submitted to the Tasmanian EPA in 2014, seeking

confirmation of the level of approval and seeking Project Specific Guidelines. The EPA

determined the project to be a Level 2B assessment and Project Specific Guidelines were

issued in mid-2014. In March 2015 a revised NOI was submitted to the EPA to address some

changes to the proposal and in the same month a response was provided by the EPA

confirming there would be no change to the level of assessment or the Guidelines as a result of

the updated NOI; the Project Specific Guidelines are provided in Appendix H.

The project has not been referred to the Commonwealth under the Environment Protection

Biodiversity Conservation Act 1999 (EPBC Act) as it has been determined by the proponent that

the Project will not significantly impact on any Matters of National Environmental Significance

(MNES) and as such does not trigger the criteria for referral under the EPBC Act. As such there

will be no commonwealth involvement in the planning and environmental approvals for the

Project.

The resulting approval pathway for the Project is the submission of a Development Proposal

and Environmental Management Plan (DPEMP) and associated development application (DA)

to Kingborough Council, which is subsequently referred to the EPA Board for joint assessment

and approval.

In addition to the standard approval process the proposed Project will also have to comply with

a broad range of environmental and planning legislation, guidelines, standards and policies as

described in the relevant sections of this DPEMP.


2. Proposal Description

2.1 Project Overview

The proposed Project is an upgrade of the existing Blackmans Bay STP, located on the western

shore of the lower Derwent Estuary off Tinderbox Road, at the end of Treatment Plant Road

(south of the main suburban area of Blackmans Bay).

The upgrade will involve both an increase in capacity of the plant as well as improved overall

effluent treatment. This will improve odour and noise for residents, as well as improving the

quality of water discharged to the Derwent Estuary and meet EPA compliance requirements.

The Project will be located at the brownfield Blackmans Bay STP site and will consist of both

repurposed existing infrastructure and new infrastructure.

An overview of the Project location is shown in Figure 2-1.

The upgrade includes the conversion of the existing activated sludge system STP with a current

capacity of 4.125 ML/day to an Intermittently Decanted Extended Aeration (IDEA) -sequential

batch reactor (SBR) system with an ADWF capacity of 8.53 ML/day and the ability to treat up to

4 x ADWF for contingency. The upgraded plant will result in a significant improvement in treated

effluent quality, and provide mitigation for odour and noise.

At its core the upgrade will address deficiencies with the current plant to meet emission limits

and manage odour impacts as well as catering for projected increase in sewage flow from the

immediate catchment. In addition, the upgrade has been planned as part of a strategic

rationalisation of STPs in the broader area and will be designed to cater for current and

projected future loads from the ageing Margate, Electrona and Howden STPs, which are

planned for decommissioning (the decommissioning of these plants and influent pipework

transferring these loads to the Blackmans Bay STP is excluded from this application). The

amalgamation of STPs at Electrona, Margate and Howden will provide long term benefits to

North West Bay by removing wastewater discharges from these underperforming STPs.

The Project aims to significantly improve plant performance to the Tasmanian EPA’s Accepted

Modern Technology (AMT) performance criteria (with some seasonal alteration to nitrogen and

phosphorus treatment criteria, explained further below) and to meet the capacity requirements

of projected sewage volumes based on an estimated 2040 population growth horizon for the

aforementioned catchments.

The upgraded plant will contain the following key components:

Inlet works including screens, a vortex grit chamber, grit classifier and collection bins;

Two IDEA-SBR tanks for nutrient removal;

Gravity thickener for waste activated sludge (utilising existing primary sedimentation tank);

Four cell aerobic digester with dewatering centrifuge (utilising existing aeration tank);

Balance tank (utilising existing secondary clarifier infrastructure);

Ultraviolet disinfection system;

New odour control facility including odour treatment via a bio-trickling filter and activated

carbon system, with an associated 12 m emission stack;

Use of the existing 600 m effluent discharge pipeline with 80 m diffuser at the Blackmans

Bay STP (no change to the outfall pipe or diffuser); and


Landscaping consisting of native grasses, shrubs and trees to reinstate the site values post

construction.

The Project is designed to produce effluent to the water quality limits outlined in Section 2.4.3.

The connection of the additional sewage from the decommissioned plants to the Project is

planned to occur via an overland rising main several kilometres in length, with a final pipeline

route yet to be selected. It is important to note that the construction of the rising main pipeline

for the planned amalgamation scheme and the decommissioning of the Margate, Electrona and

Howden STPs do not form part of the proposal; nor is this proposal contingent upon the

amalgamation proceeding.

The upgrade of the STP is anticipated to cost in the vicinity of $30-40 million, with a 24-month

construction period followed by a six-month commissioning period.

A detailed site plan is presented in Figure 2-2. The existing house shown on the western

boundary of the site is to be used as a site office during the construction phase and demolished

at the completion of construction and native vegetation reinstated in its place.

2.2 Location and Site Context

The proposed Project is located in southern Tasmania on the margins of the township of

Blackmans Bay (refer Figure 2-1).

The Project site itself includes two land titles, one currently owned by TasWater and containing

the existing Blackmans Bay STP, and another currently owned by Kingborough Council which

contains the former caretaker’s cottage (which is currently vacant) and areas for public walking

and recreation. TasWater have entered into discussions with Kingborough Council to purchase

the parcel of land (as marked on Figure 2-3) to facilitate construction of the Project. There is no

requirement for subdivision of this land as TasWater proposes to acquire the entire parcel from

Kingborough Council. TasWater will maintain public access and walking tracks on the land

surrounding the Project as outlined in Section 2.10.

The combined area of both land titles is referred to in this DPEMP as the Project Site (i.e. ‘the

Land’) (refer Figure 2-3).

The Project Site contains the existing Blackmans Bay STP, two waterways/drainage lines, an

existing (vacant) house owned by Council, the Suncoast Headlands Track, an access road

(Treatment Plant Road) and incoming wastewater pipelines, water pipelines and electricity.

The Project Site is a mosaic of exotic grassland and native vegetation including a number of

juvenile and mature eucalypts. The land slopes generally from the west to the east and includes

a geoconservation site along the eastern coastal boundary.

The Project Site is bounded by residential properties to the north and west, by adjoining council

land (used for recreation) to the south and the Derwent Estuary to the east.

The Project Site is accessed via Tinderbox Road and then Treatment Plant Road to the west.

Maps of the Project Site and surrounds are provided in Figure 2-1 to Figure 2-3.

Const

ruction

Acces

s Roa

d

Treatment Plant Road

CURRENT SITE BOUNDARY

40 m

50 m

60 m

70 m

30 m

20 m

10 m

80 m

90 m

100 m

Suncoast Drive

Tinderbox Road

Liberty Court

Wells Parade

Tahun

e Cres

cent

Ephesus Place

Jodie Court

Syracuse Place

Tahune Crescent

526,400

526,400

526,600

526,600

526,800

526,800

5,237,

200

5,237,

200

5,237,

400

5,237,

400

5,237,

600

5,237,

600

G:\32\18107\GIS\Maps\MXD\3218107_001_Figure2-1_Location_RevC.mxd

0 50 10025

MetresMap Projection: Transverse Mercator

Horizontal Datum: GDA 1994Grid: GDA 1994 MGA Zone 55

© 2016. Whilst every care has been taken to prepare this map, GHD (and DATA CUSTODIAN) make no representations or warranties about its accuracy, reliability, completeness or suitability for any particular purpose and cannot accept liability and responsibility of any kind (whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred by any party as a result of the map being inaccurate, incomplete or unsuitable in any way and for any reason.

Tasmanian Water CorporationBlackmans Bay STP DPEMP

Figure 2-1

Job NumberRevision C

32-18107

05 Aug 2016

Location MapDate

Data source: DPIPWE (cadastre, imagery, land tenure, land zoning, waterways, contours), TasWater (proposed infrastructure). Created by: jtoregan

2 Salamanca Square Hobart TAS 7000 Australia T 61 3 6210 0600 F 61 3 6210 0601 E [email protected] W www.ghd.com.au

Paper Size A3

LEGENDContours (10 m)WaterwayElectrical to site (OH)Cadastral ParcelDog excersise area

ProposedThe project siteConstruction compound *Existing fenceNew fenceSTP infrastructure

CutFillProposed screening vegetation

* site office, parking, machinery, laydown, stockpiles and bunded fuel and chemical storage.

LOADING / UNLOADINGAREA

CHEMICALSTORAGE

NEW

ACCE

SS R

OAD

TO EXISTINGOUTFALLIDEA-SBR 4-CELL

AEROBICDIGESTER

EFFLUENTATTENUATION

TANK

GRAVITYTHICKENER

AMENI

TIES B

UILDIN

GINLET WORKS

ODOURCONTROL

PLANT

DE-WATERING BUILDING(CENTRIFUGE / WORKSHOP / STORAGE)

IDEA-SBRBLOWERS

UV DISINFECTIONFACILITY

MOTOR CONTROLCENTER

PUMPSTATION

SUBSTATIONSTANDBY GENERATOR

FUTURECLOTHMEDIA

FILTRATION

WATER PUMPSTATION

THICKENED SLUDGEPUMP STATION

40 m

30 m

20 m

50 m

10 m

526,650

526,650

526,700

526,700

526,750

526,750

526,800

526,800

5,237,

300

5,237,

300

5,237,

350

5,237,

350

5,237,

400

5,237,

400

5,237,

450

5,237,

450

5,237,

500

5,237,

500

G:\32\18107\GIS\Maps\MXD\3218107_002_Figure2-2_SitePlan_RevB.mxd

0 10 205





Figure 2-2

Job NumberRevision B

32-18107

05 Aug 2016

Site PlanDate



Paper Size A3

LEGENDContours (10 m)WaterwayElectrical to site (OH)Cadastral parcel

ProposedThe project siteConstruction compound

Existing fenceNew fenceSecurity gateMajor process pipeSTP infrastructure

CutFill

(site office, parking, machinery, laydown, stockpilesand bunded fuel and chemical storage)

Const

ruction

Acces

s Roa

dTreatment Plant Road

The project area is delineated as 'The Site'and TasWater have entered into an agreementwith Kingborough Council to purchase the land

title within 'The Site'.

172 m

170 m

167 m

170 mSuncoast Headlands Track

Suncoast Headlands Track

Suncoast Headlands Track

Suncoast Drive

Tinderbox Road

Liberty Court

Wells Parade

Tahun

e Cres

cent

Ephesus Place

Jodie Court

Syracuse Place

Suncoast Drive

Tinde

rbox R

oad

Liberty Court

Tahune Crescent

Wells Parade

Tahun

e Cres

cent

Tahune Crescent

Ephesus Place

Jodie Court

Syracuse Place

526,400

526,400

526,600

526,600

526,800

526,800

5,237,

200

5,237,

200

5,237,

400

5,237,

400

5,237,

600

5,237,

600

G:\32\18107\GIS\Maps\MXD\3218107_003_Figure2-3_LandTenure_RevB.mxd

0 50 10025





Figure 2-3

Job NumberRevision A

32-18107

21 Jul 2016

Land Tenure and UsesDate

Data source: Data Custodian, Data Set Name/Title, Version/Date. Created by:jtoregan


Paper Size A3

LEGENDWaterwayElectrical (OH)Cadastral ParcelDog excersize area

Land Tenure (LISTmap, 2016)Private FreeholdPublic ReserveCrown LandLocal GovernmentCasementLocal Government Act ReserveTas Water

ProposedThe Project SiteFenced Area (STP Operational Boundary)Construction Compound(site office, parking, machinery, laydown,stockpiles and bunded fuel and chemicalstorage)


2.3 Project Rationale and Context

The proposed Project is multifaceted and at its core is driven by a need to improve performance

of the current plant and cater for current and projected increases in flow from the area currently

serviced by the Blackmans Bay STP (Kingston, Huntingfield, Blackmans Bay and southern

Bonnet Hill) heading into the next 20-30 years. The current Blackmans Bay STP is limited in

size and treatment capacity and upgrades are necessary to facilitate ongoing provision of

wastewater treatment to the area services by the existing STP.

With a large number of aging treatment plants across the state, updating of facilities has

become a primary focus for TasWater in the near future. Amalgamation of smaller outdated

STPs into larger centralised schemes is one option that TasWater considers when reviewing its

current wastewater treatment infrastructure across the state; this is often a cost effective and

efficient solution. With this in mind, through the planning of the Blackmans Bay STP upgrade,

consideration was also given to the broader sewage treatment network in the Kingborough

Local Government Area (LGA) and the need to address deficiencies in other smaller local

plants, namely Electrona, Margate and Howden STPs. This has led to the TasWater decision to

decommission Margate, Electrona and Howden STPs and redirect all sewage to the upgraded

Blackmans Bay STP (decommissioning of the other plants and infrastructure to transfer

resulting effluent to Blackmans Bay is outside of the scope of this application).

The proposed Project is not dependant on the decommissioning of the abovementioned STPs,

as the Blackmans Bay STP requires the upgrade regardless.

2.3.1 Amalgamation of Treatment Plants

TasWater has identified the need to improve wastewater treatment in the Kingborough LGA

heading into the next 25-30 years. Issues identified within the current STPs within the LGA

treatment scheme include the following:

The Blackmans Bay STP, which currently services all the urban areas within greater

Kingston, is close to its current treatment capacity and is an aging plant which

underperforms under higher load conditions in the areas of biochemical oxygen demand

(BOD) generation, suspended solids removal and disinfection. There is also a history of

odour complaints associated with the existing plant.

The Margate STP continues to consistently underperform in effluent treatment and requires

upgrading in the near future from a lagoon system and cannot accept any additional

sewage until upgrades are performed.

The lagoon system at Electrona STP underperforms in effluent treatment and, like the

Margate STP, cannot accept any additional sewage until significant upgrades are

undertaken. The current lagoon is overloaded and minimal nutrient removal is achieved.

The Howden STP, although generally functioning satisfactorily, is a small package plant

that would be more cost effective to close and merge the catchment into a larger scheme.

With all major treatment plants mentioned either nearing capacity and/or underperforming,

an increase in both treatment capacity and effectiveness in the immediate future is

required. Amalgamation of the abovementioned STPs into one large STP rather than

separately upgrading each individual plant was in this case seen as the most effective

solution.

Within the Kingborough LGA area, the Blackmans Bay STP was assessed as the most suitable

plant to upgrade in a centralised scheme owing to the following:

It is the largest existing STP and therefore the most cost effective to upgrade;


It has suitable surrounding land for expansion; and

The STP has a superior existing open ocean effluent discharge pipeline (upgraded in

2010), when compared to the remaining plants, which discharge into the lower energy

North West Bay area.

North West Bay is not considered an optimum receiving environment due to several factors. The

shallow waters and sheltered nature of the bay creates a lower energy environment not

conducive to the most effective mixing when compared with an open ocean outfall. Longer

retention times in the bay of discharged effluent may also result in nutrient build-ups. This can

lead to problem algal growth in the shallower areas and is more likely to impact on the

environment, especially the intertidal habitat at the northern end of the bay.

The long term benefits to North West Bay by removing wastewater discharges from these

underperforming STPs is a key driving factor in the amalgamation of these plants into the

Blackmans Bay STP site.

2.3.2 Existing STPs – Treatment Quantity and Quality

To provide background context to the rationale for the need to improve sewage treatment

quality and capacity, the following sections outline flows, quality and trade waste characteristics

of the existing STPs for the licence reporting period of 1 July 2014 to 30 June 2015.

Treatment Volumes

Flow results for the four STPs for the 2014-2015 reporting period are presented in Table 2-1. It

should be noted that licences for these plants are not in the form of modern contemporary

licences and are outdated to a degree.

The results identify the Blackmans Bay STP is at capacity and therefore requires upgrade and

also highlights that the Electrona STP is also approaching capacity.

The Margate STP flows do not suggest a need to immediately upgrade for physical flow

capacity, however the issue with this plant is more related to effluent treatment effectiveness, as

highlighted in the following section.

Table 2-1 Flow Characteristics at Existing STPs for 1 July 2014 – 30 June

2015

STP 2014-2015

Average Daily

Flow (kL/day)

Licence Limit –

Average Dry Weather

Flow (kL/day)

Month with highest

average daily flow

(kL/day Average)

2014-2015

Highest Peaking

Flow (kL)

Blackmans

Bay

3985 4125 4800 (Aug) 15,260

Margate 362 681 474 (Jul) -

Electrona 310 450 492 (Aug) 1,857

Howden 42 100 56 (Jun)

Total 4699 - - -

Table Note – The Blackmans Bay STP also has a licence limit of 15,000 maximum wastewater

throughput (kL/day).


Effluent Quality

Effluent qualities at the four STPs are shown in Table 2-2 for the 2014-15 reporting period. The

table shows the compliance percentage with the STP licenced discharge limits; as can be seen,

non-compliances occur at all STPs for several parameters.

When results are compared to the proposed treatment that will be achieved by the Project in

Section 2.4.3, it can be seen that a large improvement in effluent quality will be achieved when

compared to the current standard.


Table 2-2 Effluent Quality Data for the 1 July 2014 – 30 June 2015 Reporting Period (from Submitted 2014-15 AERs)

Parameter

(mg/L unless

otherwise

stated)

Blackmans Bay STP Margate STP Electrona STP Howden STP M

ed

ian

90

th

Ma

x

EP

N

Lim

it

EP

N

Co

mp

lia

nce

Me

dia

n

90

th

Ma

x

EP

N

Lim

it

EP

N

Co

mp

lia

nce

Me

dia

n

90

th

Ma

x

EP

N

Lim

it

EP

N

Co

mp

lia

nce

Me

dia

n

90

th

Ma

x

EP

N

Lim

it

EP

N

Co

mp

lia

nce

BOD5 22 51 68 40 83% 36.5 72.8 76 66 75% 156 237 280 206 83% 8 24.8 27 15 67%

Suspended

Solids

15.5 24.2 28 60 100% 24.2 50.8 57 66 100% 98 198 418 186 83% 7 22 44 20 83%

Thermotolerant

Coliforms

(cfu/100ml)

155 694 5600 1000 92% 50 154 770 750 92% 255 105400 120000 1000 67% 235 771 970 1000 100%

Oil & Grease 1.4 2.2 2.3 10 100% 2.25 3.47 3.5 10 100% 20.4 58.9 63.4 46 83% 1 1 1 10 100%

Total Nitrogen 42.6 55.0 57.5 - - 55.3 62.73 63.0 44 17% 51.7 57.9 65.0 65 100% 11.9 21.9 22.1 15 58%

Ammonia

Nitrogen

29.8 41.9 43.6 - - 40.2 45.5 47.7 37 33% 32.1 36.4 43.5 45 100% 4.2 17.6 18.5 10 67%

Total

Phosphorus

8.6 9.47 11.8 - - 9.35 9.99 11.7 10 92% 8.15 11.1 11.4 12 100% 1 2.41 3.8 10 100%

Cl 0.76 1.26 2.93 1 75% 1.13 3.0 5.19 1 75% 0.71 6 6 1 73% - - - - -

Min

50

th

Ma

x

EP

N L

imit

EP

N

Co

mp

lia

nce

Min

50

th

Ma

x

EP

N L

imit

EP

N

Co

mp

lia

nce

Min

50

th

Ma

x

EP

N L

imit

EP

N

Co

mp

lia

nce

Min

50

th

Ma

x

EP

N L

imit

EP

N

Co

mp

lia

nce

pH 5.8 7.2 7.5 6.5-

8.5

96% 6.19 7.68 7.86 6.5-

8.5

96% 6.32 7.19 7.43 6.5-

8.5

95% 5.9 7.81 8.55 6.5 -

8.5

92%


Mass Loads

Existing mass loads for the upgraded treatment plant were calculated using the median effluent

quality for each of the contributing treatment plants and flows presented in Table 2-1 and Table

2-2 (July 2014 to June 2015). The parameters selected were based on those for which there is

an existing license condition. The result are provided in Table 2-3.

Table 2-3 Existing Mass Loads

Parameter Blackmans

Bay STP

(kg/day)

Margate

STP

(kg/day)

Electrona

STP

(kg/day)

Howden

STP

(kg/day)

Total kg/day

Combined

Plants

Total

BOD5 87.7 13.2 48.4 0.034 149.3 54.5

TSS 61.8 8.8 30.4 0.029 100.9 36.8

Oil &

Grease 5.6 0.8 6.3 0.004 12.7 4.6

Total

Nitrogen 169.8 20.0 16.0 0.050 205.9 75.1

Ammonia

Nitrogen 118.8 14.5 9.9 0.018 143.2 52.3

Total

Phosphorus 34.3 3.4 2.5 0.004 40.2 14.7

Trade Waste

The existing Blackmans Bay STP accepts sewage from a variety of residential, commercial, and

to a lesser degree, industrial premises, with no trade waste over Category 2C. The key

parameters of concern in the industrial waste stream include: ammonia, nitrogen, biochemical

oxygen demand (BOD), total suspended solids (TSS), total dissolved solids (TDS), sodium and

oil & grease.

Margate and Electrona accept mainly residential and commercial sewage, with the Margate

STP accepting Category 2A and 2B trade waste, and Electrona STP accepting Category 2A

only. No key industrial contaminants of concern were identified from these waste streams.

The Howden STP does not accept any trade waste.

Trade waste customer numbers and accepted volumes for 1 July 2014 – 30 June 2015 at the

three STPs are detailed in Table 2-4. Note that no Category 3 or Category 4 waste is accepted

at any of the STPs.


Table 2-4 Trade Waste Volumes accepted from 1 July - 30 June 2015 at

Blackmans Bay, Margate and Electrona STPs

Trade

Waste

Category

Blackmans Bay STP Margate STP Electrona STP

Number of

Customers

Estimated

Volume

(ML/year)

Number of

Customers

Estimated

Volume

(ML/year)

Number of

Customers

Estimated

Volume

(ML/year)

Cat 1 26 3.0 5 0.6 1 0.1

Cat 2A 47 8.7 10 1.9 4 0.7

Cat 2B 7 2.1 2 0.6 - -

Cat 2C 5 2.5 - - - -

Tankered 1.8 - - - -

Total 85 18.1 17 3.1 5 0.8

2.3.3 Improved Treatment Technology

As can be seen from Section 2.3.2, the existing STPs have several issues with treatment quality

and capacity, with exceedances of some parameters occurring on a regular basis. There is also

the issue of odour complaints at the Blackmans Bay STP; complaints were received several

times over the 2014-2015 reporting period.

The design of the Project will utilise significantly more modern treatment equipment than is

currently employed, including mitigation for problematic issues that have been occurring at the

existing STPs. This includes:

An odour control facility integrated into the primary treatment system to remove and treat

foul air;

Large improvement in nitrogenous compound removal through the use of modern IDEA-

SBRs; and

Upgraded disinfection through the use of an ultraviolet treatment system.

2.4 Project Design Parameters

2.4.1 Proposed Treatment Capacity

The Project is designed to cater for 8.53 ML/day ADWF.

The rationale of the new plant includes having sufficient capacity to treat wastewater received

from the four STP catchments to at least a ~2040 horizon.

A similar methodology to the one outlined below was originally used to calculate the standing

8.53 ML/day treatment design capacity, which has been used extensively in the design process

to date. As this number was calculated a number of years ago, it was seen as prudent to

reassess capacity requirements using more up to date catchment data to ensure the design

capacity was still appropriate.

The following methodology was utilised to determine the required capacity of the new plant and

whether the existing design capacity of 8.53 ML/day was still suitable.


Influent flow data was analysed for the four STPs from the 2014-15 reporting period (and

available TasWater data for the Level 1 Howden STP) to calculate a combined total estimated

ADWF as of June 2015. This was calculated to be approximately 4,400 ML/day ADWF and

presents a starting point for the currently required ADWF treatment capacity of all the STPs.

In order to estimate future flows and hence the new STP size requirement, the percentage

change in population from 2012 – 2040 was calculated and the percentage difference used to

estimate future ADWF requirements.

Projected population growth data for the Kingborough LGA generated by the Department of

Treasury and Finance (DOTF) was utilised to estimate the 2040 population increase.

The data available was for low, medium and high growth rates from 2012 – 2037. Therefore, in

order to estimate further towards 2040, the data was analysed to develop a formula to extend

the projection towards 2040 and beyond. The growth formulas used by the DOTF were found to

be linear and were applied to medium and high growth population estimates to provide a 2040

estimate.

Figure 2-4 provides the projected medium and high population growth for the Kingborough LGA

in a medium growth environment, which equated to a 2040 population projection of 50,089, a

change of approximately 42.7 % from 2012. The projected population increase for a high growth

environment was 58,520, a change of approximately 66.8 % from 2012.

Using the percentage population changes as an estimation figure for future treatment volume

requirements gives the estimates presented in Table 2-5. These projected treatment capacities

are compared to the ‘current’ 4,400 ML/day ADWF from the combined Blackmans Bay,

Electrona, Margate and Howden STPs, using 2014/15 data.

Table 2-5 Required Treatment Capacities

Year Predicted ADWF from Medium

Growth Rates (kL/day)

Predicted ADWF from High

Growth Rates (kL/day)

2040 6,336 7,404

Using the high growth data for conservatism, the projected ADWF treatment capacity required

for the new plant in 2040 is estimated at 7.4 ML/day.

Limitations with the calculation methodology that must be taken into account include that the

numbers used are projections only and that they are for the entire Kingborough LGA, with

potentially more or less growth in the focussed catchment areas of Margate, Electrona, Howden

and Blackmans Bay.

The calculations reaffirm that the original design capacity of 8.53 ML/day ADWF at a 2040

design horizon is more than adequate to treat the projected flow requirements, therefore no

alterations to design capacity were necessary. The 8.53 ML capacity in the design will provide

additional operating headroom in the years leading up to the design horizon, providing a high

degree of redundancy in treatment capacity.


Figure 2-4 Projected Medium & High Population Growth for Kingborough LGA

2.4.2 Proposed Treatment Process - SBR

Two sewage treatment processes were considered for the upgrade of the Blackmans Bay STP

A Membrane Bioreactor (MBR) and a Sequenced Batch Reactor (SBR). The primary difference

between these processes is that the SBR achieves solids removal by sedimentation (wi thin the

bioreactor) while the MBR achieves solids removal through membrane filtration. An SBR has

been selected as the preferred technology as outlined in Section 3.5 - Alternative Treatment

Plant Technology.

Further detail on the specifics of the adopted treatment process are provided in Section 2.5.

2.4.3 Proposed Treated Effluent Quality

The proposed upgrades to the Blackmans Bay STP have been designed to achieve a high level

of effluent quality. Accepted Modern Technology (AMT) limits outlined in the Emission Limit

Guidelines for Sewage Treatment Plants that Discharge Pollutants in Fresh and Marine Waters

(ELG) (June 2001) were used as a basis for effluent quality design and modified to suit site

specific receiving environment conditions. The final design effluent treatment targets for the

upgraded Blackmans Bay STP are displayed in Table 2-6.

By comparing the proposed emission limits below to current plant performance (refer Table 2-2)

it can be seen that a considerable improvement in treated effluent quality is proposed

particularly with respect to nitrogen and ammonia removal.


Table 2-6 Design Effluent Performance of Upgraded STP

Parameter Unit

Median 90th Percentile Max

Normal Winter Normal Winter Normal Winter

Ammonia (as N) mg/L 1 3 2 5 5 10

Total Nitrogen (as N) mg/L 7 15 10 25 15 35

Total Phosphorus mg/L 10 12 15

BOD5 mg/L 10 15 20

TSS mg/L 10 20 30

Oil & Grease mg/L 2 5 10

Thermotolerant

Coliforms

CFU/100ml 200 500 750

pH - 6.5 to 8.5

Table Notes:

*Normal is defined as all months other than winter (i.e. Sept to May inclusive).

**Winter is defined as the months June, July and August inclusive.

Nutrient Removal

The exception to the AMT limits are the concentration limits proposed for total nitrogen,

ammonia, and total phosphorus. For these parameters, adjusted effluent quality targets were

developed by TasWater based on the characteristics of the receiving environment (Derwent

Estuary), as outlined below.

The Derwent Estuary has historically shown significant fluctuations in nutrient concentrations

with seasonal changes (DEP, 2015). Oxides of nitrogen and ammonia/ammonium (the

bioavailable components of total nitrogen) and dissolved reactive phosphate (the bioavailable

form of total phosphorus) historically tend to increase significantly in concentration during winter

months in the lower estuary (DEP, 2015). This is thought to be a combination of both changes in

upstream inputs of nutrients from anthropogenic sources and through natural seasonal oceanic

input variation throughout the year.

Relaxed effluent quality targets (limits) for nutrients are being proposed by TasWater for the

Project, resulting in increases to AMT limits. Specific rationales for each proposed nutrient limit

are provided below.

Total Nitrogen/Ammonia

One of the most significant tasks of the STP is the removal of nitrogenous compounds through

biological nutrient removal processes. These processes are influenced by sewage temperature,

with rates of conversion slowing significantly as influent temperatures drop, resulting in the

requirement to treat the sewage longer in the bioreactor or heating the reaction during winter

months to maintain the same efficiencies as warmer months.

By reducing the degree of treatment required for nitrogenous compounds, significant efficiencies

in power consumption and the STP footprint itself can be made (i.e. smaller bioreactor); forming

the rationale behind the proposed relaxed limits.


With the higher ambient concentrations of nitrogenous compounds in the receiving environment

during winter mentioned previously, the release of effluent with slightly higher concentrations

than AMT during this period is not seen as a significant risk to the receiving environment. This is

covered in detail in Section 6.8 where risks to the marine environment are discussed.

With this in mind, the most cost effective and efficient solution for the Blackmans Bay STP was

to design the plant with seasonal nitrogenous compound removal targets. During winter months

(June, July, August) when influent temperatures are lowest and nitrogen levels highest in the

receiving environment, nitrogen (and ammonia) removal will be relaxed. During the remainder of

the year when influent temperatures are higher and nitrogen levels are lower in the receiving

environment, AMT limits will be adhered to.

Phosphorus

The design of the STP is not specifically aimed at the removal of phosphorus, however some

removal is achieved in the biological processes, through the uptake of phosphorous in activated

sludge biomass, and removal of suspended solids. Removal of additional phosphorus is

possible (if required) but would require the addition of chemicals such as aluminium sulphate or

ferrous chloride into the treatment process. This would result in approximately 15-20% greater

sludge production due to the chemical precipitation required to achieve the required

phosphorous removal.

Algal blooms are considered one of the major potential impacts of eutrophication of a waterway.

As the limiting nutrient in algal growth in the lower portions of the Derwent Estuary is considered

to be nitrogen, relaxation of the effluent concentration limits of phosphorus in comparison to

AMT limits (four-fold increase for 90th percentile effluent) are not seen as a significant risk to the

marine environment. This is considered in more detail in Section 6.8 also.


2.5 Sewage Treatment Plant Design

Following the design capacity rationale outlined in Section 2.4.1, the Project has been designed

to treat an ADWF of 8.53 ML/day, with an estimated 2040 design horizon. The plant has been

designed to provide full treatment at flows up to 34 ML/day (4 x ADWF at the design horizon).

The plant will be capable of hydraulically passing 700 L/s (60.5 ML/day). Management of wet

weather flows is discussed in Section 2.5.9.

The following sections describe the proposed treatment process in sequential order. The

schematic in Figure 2-5 outlines the treatment process in more detail.

2.5.1 Primary Treatment

Inlet Works Structure

The inlet works is an above ground concrete structure which receives the raw sewage, removes

certain contaminants, including screenings and grit. All concrete channels are covered and the

foul air extracted and treated in an odour control unit. The inlet works structure is designed to

hydraulically pass all flows to the plant.

Inlet Screens

Sewage will initially be accepted in a receival chamber where it will be passed through three 3

mm spiral screw screens operating in parallel. A standby unit is provided for redundancy. The

spiral screw screens will capture and remove larger waste contaminants within the influent,

which will be conveyed, washed and dewatered by dewatering screws to an odour-controlled

screening bin for collection. Each screw screen will have a capacity of 304 L/s.

A bypass channel with a manually raked coarse bar screen is provided as a backup to the

primary screens in the event of blockages.

Vortex Grit Chamber and Classifier

Screened sewage is passed into a single vortex grit chamber to remove grit from the screened

sewage. The grit chamber underflow is periodically pumped to the grit classifier where organics

are removed and the grit is conveyed and dewatered to an odour-controlled grit bin for

collection. The vortex grit chamber has a nominal capacity of 880 L/s, suffic ient to process all

screened sewage flows.

A grit chamber bypass is provided for maintenance purposes.

The screened and degritted sewage then passes to the IDEA-SBR for secondary treatment.

RECEIVALCHAMBER

RAWSEWAGESCREENS

CELL #1 CELL #2 CELL #3 CELL #4

EXIST GRAVITY THICKENER

EXISTING AERATION BLOWERS

CENTRIFUGE

BALANCE TANK

GRIT BIN SITE ODOUR CONTROL

UV DISINFECTION

AEROBIC DIGESTER

CENTRATE PUMPS

ACTIVATED CARBON

AERATIONBLOWERS

BIO-TRICKLING FILTER

RAKED SCREEN

STACK

GRITVORTEX

CHAMBER

GRITCLASSIFIER

FLOWSPLITTER

EFFLUENTDISCHARGE

SERVICEWATER

DEWATERED SOLIDS BINS

IDEA-SBR #2

IDEA-SBR #1SEWAGE

AEROBIC DIGESTER

This Drawing must not beused for Construction unlesssigned as Approved

Date

CheckDrafting

Plot Date: Cad File No:

DateDrawnRevisionNo A3Original Size

Title

Project

Client

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DesignConditions of Use.This document may only be used byGHD's client (and any other person whoGHD has agreed can use this document)for the purpose for which it was preparedand must not be used by any otherperson or for any other purpose.

DO NOT SCALE

Note: * indicates signatures on original issue of drawing or last revision of drawing

2 Salamanca Square Hobart TAS 7000 AustraliaGPO Box 667 Hobart TAS 7001T 61 3 6210 0600 F 61 3 6210 0601E [email protected] W www.ghd.com

28 July 2016 - 3:53 PM G:\32\18107\CADD\Drawings\32-18107-B001.dwgPlotted By: Robin Lawson

(Project Director)Approved

JobManager

ProjectDirector

PRELIMINARY

32-18107-B001 A

RSL

AS SHOWN

AJungalwalla

Typewritten text

Figure 2-5


2.5.2 Secondary Treatment

Intermittently Decanted Extended Aeration – Sequential Batch Reactors (IDEA-SBR)

Secondary treatment of the screened and degritted sewage will be provided by two

Intermittently Decanted Extended Aeration – Sequential Batch Reactors (IDEA-SBRs). The

purpose of the secondary treatment is to oxidise organic material, oxidise ammonia and organic

nitrogen to nitrates (“nitrification”), and subsequently convert nitrates to nitrogen gas

(“denitrification”), hence reducing the total nitrogen of the sewage. Suspended solids are also

retained in the IDEA-SBRs.

The terms IDEA and SBR refer to two possible process operating modes. IDEA mode involves

continuous inflow to both bioreactors, whereas SBR mode involves inflow only during the

aerate/react phase.

Under both the SBR and IDEA modes, conditions in each bioreactor are passed through a

series of timed phases to achieve biological processing of the pollutant load (“aeration” phase),

settling of the biomass to leave a clear supernatant layer at the bioreactor surface (“settling”

phase), and removal of the clear supernatant layer as effluent (“decant” phase). On completion

of these three distinct phases, the cycle is repeated.

The sewage feed to each IDEA-SBR tank passes first to a small anoxic selector tank where it is

mixed with return activated sludge (RAS) pumped from the downstream end of the tank. The

selector is configured to provide a high ratio of substrate (“food”) to biomass (“microbes”) to

protect against the proliferation of certain types of filamentous organisms, and promote the

formation of a plant biomass with favourable settleability. The selector is fitted with mechanical

mixers to maintain the biomass in suspension throughout the operational cycle.

The flow from the anoxic selectors will pass to a “swing zone” operated under aerobic or anoxic

conditions as required. Under normal loading conditions, the swing zone will typically be

operated under anoxic conditions with aeration limited to periodic pulsing for mixing purposes.

In this mode, the swing zone shall promote effective denitrification throughout the operational

cycle. During periods of higher than normal loading, or low temperatures, the zone may be

operated aerobically to enhance nitrification.

From the swing zone, the flow will pass to the main zone of the IDEA-SBR tank. During the

“aeration” phase, oxygen is supplied to the main zone of the IDEA -SBR tanks by the Aeration

Blowers via the Fine Pore Membrane Diffusers. The aeration phase will also include periods of

low or no dissolved oxygen during the aeration phase to increase the extent of denitrification .

At the end of the “aeration phase” aeration is stopped to allow the biomass to settle. On

completion of the “settling” phase, the decant mechanism at the downstream end of the tank will

gradually lower to withdraw the clear supernatant, which will flow to the Balance Tank to

moderate the flow prior to disinfection. At the conclusion of the “decant” phase, the IDEA -SBR

tank will have returned to the initial bottom operating water level, the decant mechanisms will be

raised to the park position above the water surface, and the IDEA-SBR tank will return to the

“aeration” phase.

During each operating cycle, a portion of the biomass will be withdrawn from each IDEA-SBR

and transferred to a Gravity Thickener, in order to maintain the desired solids retention time

(sludge age) in the reactor.

The IDEA-SBRs provide full treatment at flows up to 34 ML/day (4 x ADWF at the design

horizon), through operating in a “storm mode” which involves shortening the durations of the

aeration, settling and decant phases. At flows greater than 34 ML/day, the operation of the

system will switch to “continuous decant” mode.


During operation in continuous decant mode, flow is evenly split between both IDEA-SBR tanks

and the aeration system in the main zone of the IDEA-SBR tanks is shutoff, such that they act

as a clarifier.

Management of wet weather flows is discussed in more detail in Section 2.5.9.

2.5.3 Sludge Treatment

Gravity Thickener

The waste biomass or Waste Activated Sludge (WAS) is transferred from the IDEA-SBRs to a

gravity thickener to increase the WAS concentration as required by the Aerobic Digester

downstream. The thickened WAS is pumped from the underflow of the gravity thickener to the

Aerobic Digester, while the resultant supernatant will be transferred to the Balance Tank.

A standby thickened WAS pump is provided for redundancy, and the gravity thickener

supernatant can alternatively be reprocessed through the IDEA-SBR tanks if it is of a poor

quality.

Aerobic Digester

The WAS will be stabilised through aerobic digestion in a four-cell Aerobic Digester. The aerobic

digester cells will be intermittently aerated using Aeration Blowers via Fine Pore Membrane

Diffusers. This aeration pattern will cycle each cell between aerobic conditions (to nitrify the

ammonia released through digestion to nitrate) and anoxic conditions (to denitrify the nitrate

formed) in order to maintain a neutral pH in the digester.

The digester is configured such that one cell can be removed from service without disrupting

digestion in the remaining cells. A standby aeration blower is also provided for redundancy

purposes.

Stabilised sludge will be pumped directly from the final Aerobic Digester cell to the Dewatering

Centrifuges.

Dewatering Centrifuge

The Dewatering Centrifuge is the final step in the sludge treatment process and will dewater the

sludge (biosolids), with the dewatered cake transferred to covered, odour-controlled self-loading

bins for collection and removal offsite. The liquid (centrate) from the separation process will then

be transferred back to the inlet works for treatment.

The sludge transfer pumps, transfer pipeline, centrifuges, sludge transfer conveyors, self-

loading bins, and centrate pipeline will be fully enclosed and continuously ventilated to the

odour control system to prevent odour emissions.

2.5.4 Tertiary Treatment / Disinfection

Balance Tank

The supernatant from the SBRs will be transferred into a Balance Tank, which will be operating

on different timing cycles under ADWF conditions.

The existing secondary clarifier onsite will be reconfigured as the Balance Tank. The outflow

from the Balance Tank will be controlled by an actuated valve during dry weather conditions to

smooth the intermittent decant flows from the IDEA-SBR tanks to the UV disinfection system.

Under the high flows associated with wet weather events, the actuated valve will be closed and

the Balance Tank will operate as a clarifier to capture additional solids from the effluent stream.


Ultraviolet Disinfection

Disinfection of the secondary effluent will be achieved by UV disinfection in three reactors

configured as Duty/Duty/Assist. The plant shall also include provision for the addition of cloth

media filters in the future.

The UV dose applied to the secondary effluent will be adjusted through manipulation of the

power applied to the UV lamps, and during wet weather events, the number of UV reactors in

service. It is anticipated that only one UV unit will be required under the design 2040 ADWF of

8.53 ML/day, with the second and third units used during peak and wet weather events.

The existing chlorine disinfection system will no longer be used.

2.5.5 Effluent Discharge

Following disinfection, the resultant treated effluent will be discharged through the existing 600

m long open ocean outfall to the east of the plant, in approximately 13 m of water. The outfall

includes an 80 m long diffuser at the terminus of the pipeline, the diffuser has 21 individual 80

mm ports spaced at 4 m intervals. The effluent discharge pipeline and diffuser are already in

place and no changes to the outfall or diffuser are proposed as part of this application.

2.5.6 Odour Control

The Odour Control System will continuously extract foul air from the gravity section of the

incoming sewage main, the Primary Treatment Area, Flow Splitter, Biosolids Dewatering

System, Dewatered Cake Self Loading Bins, and General Purpose Pump Station. The forced air

extraction will maintain each of these enclosed process units at a negative pressure to prevent

fugitive odour emissions. Where necessary, the air inlets to these process units will be fitted

with weighted air inlet dampers which will close to limit fugitive emissions on a loss of sealing

(e.g. on opening of an inspection hatch).

The foul air extracted from the process will be treated using a Two Stage Bio-trickling Filter

(BTF) followed by an Activated Carbon Filter, then discharged to the atmosphere via a 12 m

stack.

The BTF removes both volatile organic compounds (VOCs) and hydrogen sulphide, while the

Activated Carbon Filter provides a polishing function.

An odour impact assessment is provided in Section 6.1.

2.5.7 Noise Control

Noise at the Project site will be emitted from several sources, including the inlet works

mechanical equipment, the Motor Control Centre (MCC), generators, extraction fans, IDEA-SBR

and aerobic digester blowers, and air compressors associated with the centrifuge system. The

design limit for noise exposure onsite is set at 70 dBA at 1 m from the envelope of the noise

source, this is in accordance with AS1217.1.

The main mitigation for noise emissions at the plant is through the enclosure of noise emitting

processes and machinery. The following is included in the plant design to mitigate noise

emission from the abovementioned sources:

Blowers are to be installed in acoustic enclosures and under cover;

Acoustic insulation in the MCC room;

The centrifuge system including air compressors will be located inside the biosolids

management building

Odour fans and ducting will meet the design specification of <75 dB; and


Generators to be installed inside acoustic enclosures.

A noise assessment is provided in Section 6.4. The degree of noise mitigation on key

infrastructure will be consistent with the model assumptions in the Noise Assessment (refer

Section 6.4).

2.5.8 Ancillary Components

Motor Control Centre (MCC)

This building will be used to control power to the various motorised items of equipment around

the plant. A new substation will be located adjacent to the MCC.

Amenities Building

The existing control building onsite will be refurbished into an amenities building for staff.

Work Shop

A workshop and storage area will be integrated into the dewatering building.

Fencing

Existing fencing will be extended to encompass the whole of the upgraded facility.

Roads and Turning Areas

A new section of access road is included in the proposed design, which will run between the

SBR and inlet works area around the east of the plant and link with the existing access road as

shown in Figure 2 2.

A new hardstand turning circle area is also included to the east of the dewatering building to

allow trucks to collect biosolid waste from the centrifuge area.

Stormwater Management

Stormwater from the majority of the existing site is captured by drains and stormwater pipes and

transferred to the nearby creeks and over the cliff to the marine environment.

The proposed upgrade will involve small additional roof areas, access roads and hardstand,

resulting in a relatively small increase in stormwater.

The intention of the new design is to minimise collection and concentration of stormwater and

allow natural flows to occur wherever possible. Diversion drains will be installed around the

upslope edge of new hardstand areas to direct clean stormwater away from the site. Any new

roofed structures will be sloped to direct rainwater onto adjacent hardstand areas. New

hardstand areas will be sloped to direct stormwater away from the site and into constructed

grass swales before diffuse discharge into the surrounding environment. Some of the new site

stormwater will be captured by the existing stormwater collection system through natural s urface

drainage (e.g. from parts of the new access road).

The Kingborough Interim Planning Scheme 2015 includes a requirement for sites with new

impervious areas greater than 600 m2 (applicable to this Project) to have a stormwater system

for the new development sufficient to achieve the targets set out in the State Stormwater

Strategy 2010 (unless it is not feasible to do so). In response to this requirement, during the

detailed design phase of the project a detailed stormwater design will be prepared (including

review of the existing stormwater capture) to achieve the stormwater management targets for

new developments as set out in the State Stormwater Strategy 2010 (unless it is not feasible to

do so). Any installed features (such as vegetated swales) will be planned to avoid any impacts

to existing native vegetation.


Contained and potentially contaminated areas of stormwater will be collected via new pipework

and directed to the inlet works of the new plant for treatment. This includes the sludge bund

loading area, the inlet works, screenings and grit collection bin area and the diffuser wash-down

area near the IDEA/SBR tanks.

Landscaping

At the completion of the construction phase all temporary facilities (e.g. construction compounds

etc) will be reinstated and revegetated using native species. In addition to reinstatement of

temporarily disturbed areas (to be done immediately following construction); new landscaped

areas will be created around the new STP to provide visual screening. Landscaping of the site

will involve planting of native tree, shrub and grass species. An indication of the area to be

landscaped is shown on Figure 2-2 with more detailed information provided in the design

drawings in Appendix A. Note that where landscaping is proposed in areas of existing

vegetation, this will be to supplement the existing native vegetation on site and existing native

trees within the landscaping zones will be retained.

2.5.9 Capacity for Upset Conditions

Upset conditions and contingency includes planning for storm and extreme weather events as

well as consideration for power and equipment failure.

The STP will have a number of different operating modes in order to cater for increased inflows

during wet weather – a shortened “storm” cycle and “continuous decant” mode. These are

described below.

The intention of the system design is that pump stations in the Blackmans Bay catchment will be

operated in a way that only triggers the STP to move into “continuous decant” mode when

deemed absolutely necessary. This decision will consider the available wet weather/emergency

storage at the pump stations and the maximum instantaneous pumping rates.

Based on recent experience at the existing Blackmans Bay STP1, it is expected that the

upgraded STP will received flows of greater than 34 ML/d (which would move the STP from

“storm” mode into “continuous decant” mode) on a very infrequent basis. For comparison

purposes, the maximum daily flow received at the Blackmans Bay STP in the three-year period

Jan 2013 – Jan 2016 was 15.9 ML/d.

“Storm” Events (Storm Cycle)

During storm flow events, when influent flows exceed nominally 25-30 ML/d (>3-3.5 x ADWF at

the design horizon), the system will adopt a shorter “storm” cycle, with a reduced aeration phase

(nominally 1 hour rather than the 2 hours under normal dry weather operation). This allows

higher wet weather flows to be treated and achieves compliance with the proposed 90th

percentile emission limits during such storm events.

It should also be noted that it may be possible to operate in “storm” cycle at even higher flows

than stated, depending on the STP’s operating parameters at the time (specifically the settling

capacity of the biomass).

“Extreme” Weather Events (Continuous Decant Mode)

During extreme events where influent flows exceed a flow of greater than 34 ML/d, (>4xADWF

at the design horizon), the system will automatically switch from the “storm” cycle to a

“continuous decant” mode. In this mode of operation flow enters both IDEA-SBR tanks, the

1 The upgrade has been sized to cater for Margate, Electrona and How den flows and peaks are also experienced in their catchments, how ever as Blackmans Bay f low s make up 85% of total f low s and there is considerable redundancy in the design

sizing, additional consideration of peak f low s in these catchments other has not been discussed herein.


aeration system in the main zone is shut-off and the decanters rise to their top level, and the

tanks essentially act as clarifiers.

Extreme weather events are infrequent and typically short in duration, and therefore the plant

will not remain in “continuous decant” mode for extended periods. The plant influent is also

significantly diluted during these extreme wet weather events.

Solids contact stabilisation is achieved by maintaining operation of Return Activated Sludge

(RAS) pumps, and the “first flush” of incoming sewage is diluted in the IDEA-SBR tanks. The

effluent will then pass through the balance tank, where it will operate as a clarifier to capture

additional solids from the effluent stream during wet weather.

All wet weather flows will then pass through the UV disinfection unit for treatment, where all

three UV units will be operative to achieve greater disinfection. Operation in “continuous decant”

mode provides a superior level of treatment to the alternative of bypassing screened and

degritted sewage during extreme events of greater than 34 ML/d, (> 4 x ADWF at the design

horizon).

Power Failure and Equipment Failure

The site and all infrastructure will be subject to a routine maintenance program to limit potential

for equipment failure. In the event of equipment failure there is redundancy built into the design

to provide for back up processing (e.g. multiple process units in most cases) until any issues

can be repaired.

As the Blackmans Bay STP is not a gravity fed plant (i.e. sewage is pumped to the site) any

local power failure may also affect incoming flows to the plant and will be managed at the pump

stations rather than the plant itself. Localised power failure at the site only (i.e. not affecting

pump stations) will be managed in the short term through operation of an emergency generator

(refer Figure 2 1) to maintain critical STP operations.

During operation with the emergency generator, raw sewage will be screened, degritted and

pass through the SBR-IDEA tanks, which will operate in continuous decant mode. In continuous

decant mode, solids contact stabilisation will be achieved by operation of Return Activated

Sludge (RAS) pump. The SBR-IDEA tanks will act as a clarifier, and clear water will pass

through to the effluent balance tank (existing secondary clarifier). The effluent balance tank will

also operate as a clarifier, allowing additional settlement of solids. Effluent will then pass

through the UV disinfection system. The odour control system will continue to operate. SBR-

IDEA aeration, aerobic digestion, and dewatering processes will be suspended during these

power outage events.

Some deviation of effluent quality may be experienced during such a power outage; however,

the frequency and duration of power outages that would require emergency power generation is

limited2 and the residual risk to the environment and sensitive receptors is low (particularly as

the UV disinfection and odour control units will remain operational through emergency generator

use). In addition, the capacity to cater for upset conditions is improved as a result of the plant

upgrade, in comparison to existing conditions.

2.6 Operational Parameters

2.6.1 Staffing Arrangements

The plant will have a rotating roster with three plant operators working ons ite during normal day-

time operating hours (0700 to 1700). Out of hours, a staff member will be on standby duty to

2 TasWater have obtained a Site Specific Reliability Analysis from TasNetworks to understand the power outage risk for the site and have taken that information into account in planning emergency power generation.


attend the plant in the event of unforeseen circumstances, which will be communicated via SMS

from the STP computer controlled system.

Additional staff and contractors will be onsite during maintenance events scheduled throughout

the year, with variable numbers dependant on the event, but not expected to be greater than 25

at any one time.

2.6.2 Operating Hours

The plant process will be automated and operate on a continuous basis throughout the year,

24-hours a day. The site will be manned during operating hours five to six days a week, where

biosolids/screenings collection, system optimisation, maintenance and monitoring will be

undertaken. Outside of daily operating hours (0700 to 1700), the plant will run autonomously

unmanned, with an operator on standby who will be notified by the plant system if any

malfunctions occur.

2.6.3 Traffic and Transportation

The Project will require three full-time staff during operation, resulting in three cars moving to

and from the site each day. Cars and trucks (as needed) will access the site via Treatment Plant

Road, which services the site from Tinderbox Road.

Biosolid waste will be collected on a daily basis by truck, with a maximum of one removal event

expected to be required per day at full operating volume of 8.53 ML/day ADWF (expected to be

reached at the 2040 design horizon) and less in the intervening period. Collection of screening

and grit bins will occur less frequency, with at least one collection event per week expected.

During maintenance periods, a maximum of 25 vehicles are expected at any one time, resulting

in 50 movements in a day, potentially for up to a week, depending on the size of the

maintenance task.

Chemical delivery will occur on an as need basis, expected to be the vicinity of a maximum of

three trucks to and from the site per week.

The proposed traffic volumes during operation are not significantly different from current vehicle

movements for the existing plant.

2.6.4 Energy Use

The Project is estimated to have an energy consumption of 6500 kWh/day at the full operating

volume of 8.53 ML/day ADWF. This capacity can be met by existing infrastructure and power

supply.

2.6.5 Waste Streams

The main waste streams from the plant will be the collected screenings and grit from the primary

treatment area and the dewatered biosolids cake produced by the sludge treatment area. Other

waste streams will include general waste and minor chemical disposal as required.

Screenings and Grit Waste Stream

Front loading skip bins with a nominal 1.5 m3 capacity will be used to store screenings and grit

prior to removal from site. These bins are covered. Screening and grit collection rates vary from

catchment to catchment, and are also dependent on the type of screening and grit removal

installed. Collection rates are also greater during wet weather events.

Estimated collection rates are summarised as follows:


Screenings collected during primary processing will average 0.23 m3/day (0.9 m3/day @ 4 x

ADWF) in the first year of operation, with an average storage capacity of 6.6 days;

Screenings collected to a 2040 design flow will average 0.37 m3/day (1.47 m3/day @ 4 x

ADWF) with an average storage capacity of 4.1 days;

Grit collected during primary processing will average 0.05 m3/day (1.1 m3/day @ 6 x

ADWF) in the first year of operation, with an average storage capacity of 29 days; and

Grit collected to a 2040 design flow will average 0.12 m3/day (2.7 m3/day @ 6 x ADWF) in

the first year of operation, with an average storage capacity of 12 days.

Biosolids Cake Waste Stream

Biosolids cake will be stored in three odour-controlled self-loading bins (10m3), which will be

transferrable onto collection trucks. The bins have been sized appropriately in the design to hold

maximum loads at the 2040 design horizon.

Dewatered biosolids cake production is estimated to an average 5.1 t/day (6.3 t/day max) in the

first year the plant is running and grow incrementally to a 2040 peak of an average of 9.2 t/day

(11.5 t/day max), based on a biosolids cake solids concentration of 16%.

2.6.6 Chemical and Dangerous Goods Storage

Current Chemical Storage

The current STP sites houses a number of chemicals and fuels including:

Gaseous chlorine

Lubricating oils

Diesel for mower

Polyelectrolyte

These goods are stored in accordance with statutory regulations.

Proposed Chemical Storage

As part of the proposed STP upgrade the existing gaseous chlorine system will be

decommissioned and minor changes will be made to existing chemical storage on site, with the

following materials to be stored.

Small quantities of lubricating oils for various mechanical components.

Small quantities of diesel (max 250L) associated with the emergency for generators. Diesel

is classified as a Class 3 Dangerous Good under the Australian Dangerous Goods Code.

Small quantities of cleaning chemicals and descalents.

Polyelectrolyte (flocculent) – to be used in the biosolids dewatering process. The specific

type of polyelectrolyte (either liquid or powder form) will be selected during design and

commissioning. Liquid polyelectrolyte will be delivered in intermediate bulk containers

(IBCs) and powered form polyelectrolyte will be delivered in pallets of 20 kg bags.

Carbon substrate (liquid sugar solution) - Depending on the actual influent characteristics of

the sewage, and the operational performance of the IDEA-SBR process, it may be

necessary to store and dose a carbon substrate, such as liquid sugar solution. The storage

tank would be in the order of 5,000 L.

Nutrients for the Bio-trickling Filter - The nutrient requirements of the bio-trickling filter will

be dependent on the type of proprietary system, however it is likely that small amounts of a


specific nutrient solution will be required to be stored on site and dosed to the bio-trickling

filter module.

The liquid sugar solution will be stored within the bulk chemicals store marked on Figure 2-2,

immediately south of the inlet works. This chemical store will be secured, signed, roofed and

bunded in accordance with statutory requirements.

The other chemicals and fuels will be stored in very small volumes within a designed bunded

storage area in the Dewatering Building (Figure 2-2) including restricted access and appropriate

signage.

Possible Future Chemical Storage

The proposed plant design does not include targeted phosphorus removal and a commitment

has been made to ongoing ambient phosphorus monitoring and retrofit of phosphorus removal if

required in the future. In the event phosphorus removal is required additional chemicals will be

needed on site.

Magnesium hydroxide liquid (up to 30,000L tank) and Aluminium sulphate (up to 30,000L tank)

could be stored on site in the future if phosphorus removal was required. These chemicals are

both defined as Hazardous Substances under the Safe Work Australia classification but are not

considered Dangerous Goods under the Australian Dangerous Goods Code.

If required these chemicals would be stored in the roofed and bunded bulk chemical storage

facility south of the inlet works.

2.7 Pre-Construction and Construction

2.7.1 Construction Overview and Timing

At a high level the construction process involves site establishment, bulk earthworks,

construction of structures, installation of equipment, piping etc and commissioning of the new

STP elements. As the Blackmans Bay STP is an operating site (which will continue to operate

throughout the construction activities to facilitate ongoing wastewater treatment until the new

plant is fully functional) construction sequencing is planned accordingly and dovetails with the

commissioning process.

A number of existing assets will be retrofitted as part of the plant upgrade. This necessitates a

staged and linked approached to construction and commissioning. An important aspect to the

staging is that the construction and process commissioning of the new major structures (such as

the new IDEA-SBR tanks, inlet works and related ancillary items) will occur prior to the retrofit of

existing equipment. This results in a parallel schedule for many of the construction and

commissioning activities. Refer also to Section 2.8 which summarises how the process

commissioning will be undertaken to compliment the staged construct ion approach.

Overall the construction phase is expected to take approximately two years, followed by a

period of approximately six months commissioning (noting that some early commissioning

activities will be conducted during the two year construction period). The proposed two year

construction period does not involve constant ‘building works’ (e.g. earth works and building

construction) but rather reflects a staged approach to gradually bringing each piece of

equipment online in a staged manner aligned with the gradual decommissioning and retrofit of

existing assets. During the two year period there will be short periods of active construction (e.g.

bulk earth works, construction of roadways, erection of new buildings) interspersed with quieter

periods of equipment installation and commissioning.


2.7.2 Construction Process and Staging

The stages described below are indicative and based on preliminary design work completed to

date. Specific details and sequencing may be modified through detailed design and

development of pre-construction and construction planning.

Stage 1 - Procurement

Following completion of the detailed engineering design, major equipment will be procured. This

includes mechanical equipment (e.g. screens, grit removal, aeration blowers, pumps, mixers,

dewatering centrifuge, etc), electrical equipment (e.g. switchgear, PLCs, instrumentation, etc),

building construction materials and other necessary items. The delivery times of these items will

constrain when mechanical installation of these components can commence.

Materials will be delivered to site and stored within the Construction Compound (refer Figure

2-1).

Stage 2 - Site Preparation

Once all necessary approvals are in place mobilisation, site establishment and construction

works will commence as follows:

Mobilisation and Site Establishment - Once the Construction Management Plan has

been approved, equipment will be brought to site and the site office and contact point will

be established (refer Figure 2-1).

Initial Site Works - Temporary boundary fencing and associated signage will be erected

and access points and sign-in procedures enacted. Vegetation clearance will be

undertaken (as delineated in Section 6.7). Sediment controls and water management

procedures for the construction phase will be installed.

Stage 3 - Major Construction and Initial Process Commissioning

This stage involves the construction of the major structures associated with the upgrade works ,

in particular the Primary and Secondary Treatment Areas. These areas involve the majority of

the bulk earthworks, which will be undertaken during this stage. Refer to the cut and fill areas

identified in Figure 2-2 for details.

The construction and initial commissioning of the following areas will occur concurrently and is

expected to take approximately 12 months.

Construction of the Primary Treatment Area - Activities include construction and

installation of inlet works and flow splitter, including drum screens, vortex grit chamber, and

associated valves, pipework, and electrical components. The odour treatment system will

also be installed at this time.

Secondary Treatment Area - Installation of IDEA-SBR tanks, as well as complete

electrical, mechanical and instrumentation and control equipment. This will include pumps,

aeration system, mixers, decant systems, WAS control valves.

Odour Control System - The existing odour control will be temporarily relocated in order to

allow for construction of the new odour control system, blowers and MCC building.

Blowers and MCC Building - Blowers to be installed and MCC building to be constructed,

including new transformer, switchboards, drives, junction boxes, control panels,

communication panels. The standby generator will also be installed in this area.

Pre-commissioning of New Liquid Stream - This involves commissioning of the new

installed assets and processes to ensure everything functions as intended, prior to


shutdown of existing processes to allow for additional minor construction work relating to

the retrofit of existing equipment. Refer to Section 2.8 or commissioning details.

Initial Process Commissioning of New Liquid Stream - This stage is the initial phase of

process commissioning where sludge from the bioreactor at the existing STP setup will be

transferred to IDEA-SBR tank 1 to act as a “seed” sludge. Operation of the new liquid

stream (inlet works and IDEA-SBR tanks) will enable a phased commissioning to

commence which enables certain existing equipment to be taken offline. Refer to Section

2.8 for details on the phased commissioning approach proposed.

Stage 4 - Additional Minor Construction, Retrofit and Integrated Commissioning

This stage involves additional minor construction work, largely associated with the Biosolids

Treatment Area, as well as existing equipment that requires works retrofit and repurpose of

existing assets. This stage involves staged commissioning, as described in Section 2.8.

The construction and commissioning of the following areas is expected to take approximately 12

months.

Retrofit existing secondary clarifier to an effluent balance tank - The necessary

modifications to convert the existing secondary clarifier to an effluent balance tank will be

made. Treated effluent will bypass the balance tank during this time. UV disinfection will

commence at this stage. Refer to Section 2.8 for related commissioning details.

Retrofit primary sedimentation tank to a gravity thickener, and existing bioreactor to

aerobic digester - The necessary modifications to convert the existing primary

sedimentation tank to a gravity thickener will be made. Refer to Section 2.8 for related

commissioning details, and how equipment is proposed to transition during this stage.

Biosolids dewatering - The new dewatering centrifuge and associated solids handling

infrastructure will be installed.

Administration Building - Installation of the permanent Control Room with the new PLC,

SCADA terminals. A shutdown is required to merge the temporary control system, with the

permanent control system located within the Administration Building.

Stage 5 - Site Reinstatement and Landscaping

At the completion of this stage the Construction Compound and associated fencing will be

removed, the Construction Compound area reinstated to its original conditions and the

Suncoast Headlands Track re-established in its final position.

Landscaping will be undertaken in accordance with the landscape plan in Appendix A and the

site will move from construction to commissioning phase.

2.7.3 Construction Compound

As illustrated on Figure 2-1 a Construction Compound will be established on western side of the

site. The Compound will be accessed via the existing gravel road (may require maintenance but

not proposed for widening) and will be the location for all materials storage, parking, site office,

stockpiling, waste storage etc. The Construction Compound will be fenced and signed as a

restricted access zone.

The existing Suncoast Headlands Track will be re-routed along the western side of the

Construction Compound during the construction period and subsequently reinstated to a new

alignment through the middle of the site post construction. The remainder of the site (outside the

fenced STP site and Construction Compound) will remain available for public access and

walking for the duration of the Project.


2.7.4 Construction Traffic

During construction local traffic is expected to increase and will be composed of staff vehicles,

trucks, utes and vans delivering electrical and plumbing equipment. During peak periods in the

construction phase there will be approximately 6-12 trucks visiting the site each day and 20

trade vehicles and 20 cars or other vehicles.

Construction access to the site will be via Treatment Plant Road, Tinderbox Road and then via

either Algona Road or Rolsyn Avenue before hitting the major Highways (Southern Outlet,

Channel Highway, Huon Highway) depending on the direction of travel.

Bulk construction materials including concrete and gravel will be sourced locally, likely travelling

to site from Hobart and the Huon respectively.

Traffic management during construction is addressed in Section 6.20.

2.7.5 Construction Hours

Working hours for construction involving heavy machinery will be restricted to 7am to 6pm

Monday to Saturday. Minor electrical or activities which do not generate noise or dust may occur

outside of these times (but within the hours of 6am to 9pm Monday to Saturday).

2.7.6 Construction Machinery and Equipment

Machinery and equipment used during construction is likely to include:

Mobile cranes (20 T through to 100 T possibly)

Concrete pump

20 T dump truck

30 T excavators

15 T Roller

4.2m Blade Grader

All equipment will be stored (when not in use) either within the STP footprint or within the

Construction Compound. There will be no stockpiling, machinery storage or other activities

outside of the identified STP fenced area and Construction Compound.

There will not be any concrete batching plant or rock crusher on the site.

With respect to bulk materials the construction work will require deliveries of gravel and

concrete, which are to be sourced from local providers. Concrete is expected to be sourced

from suppliers in Hobart and gravel from local quarries within the Kingborough and Huon Valley

municipalities. The project design relies predominately on cut rather than fill so there are no bulk

supplies of fill material required. The fill resulting from the cut on site will be removed to a

suitably licenced facility (by a licenced transporter) with any topsoil retained on site and

stockpiled within the Construction Compound or fenced STP site for subsequent rehabilitation.

Minor quantities of fuels and chemicals may be stored on site during construction including:

Fuels, oils and lubricants

Paints and solvents (several hundred litres)

Cement and bitumen materials; and

Small quantities of disinfectants and cleaning chemicals.

These materials will be housed in a roofed and bunded facility within the construction compound

(refer Section 6.6 for management of hazardous substances).


2.8 Commissioning

2.8.1 Commissioning Planning

Commissioning activities will be carefully planned to ensure a smooth and effective transition

from operation of the current STP to the upgraded STP. A step-by-step approach of the

commissioning activities is provided below, describing a phased approach to minimise

disruption to current operations and to improve quality of treated effluent during commissioning

compared with current operations. The phases described below are indicative and based on

preliminary design work completed to date. Specific details and sequencing may be modified

through detailed design and development of specific commissioning plans and procedures.

The commissioning process outlined below is expected to take approximately 6 months after the

completion of the construction period; noting however that some early commissioning activities

will be undertaken concurrently with the final phases of construction. The result is a 2.5-year

program, with approximately 2 years for construction (includes early phase commissioning)

followed by 6 months of active commissioning.

2.8.2 Commissioning Phases

Phase 1 - Pre-commissioning

This phase will include area-specific handover from the construction to the commissioning

teams. This includes initial checks on completeness of equipment installation and testing

required prior to commissioning. Following this, pre-commissioning tests will be undertaken on

all equipment associated with each functional area of the plant through comprehensive

inspection and test plans (ITPs).

Phase 2 - Wet commissioning

Following pre-commissioning sign-off, wet commissioning shall commence. This stage involves

the testing of all equipment using potable/recycled “clean” water. Typically, the following tasks

will be undertaken:

Pump system capacity testing;

Equipment noise emission testing;

Leak and level testing of diffusers, aeration capacity testing;

Odour control testing, including capture rate, duct air flow balancing and fan capacity

testing;

Testing of hydraulics and control valves throughout system;

Tuning of control loops throughout the STP; and

Simulation of full operational conditions.

Following wet commissioning of an item, it will be left in operation with recirculating temporary

clean water until it can be connected to the new system. This allows the equipment to be tested

for an extended period of time.

During both Phases 1 and 2, the sewage will be treated by the existing STP as per current

operation.

Phase 3a - Process Commission (Liquid Stream with IDEA-SBR 1)

During this initial phase of process commissioning, sludge from the bioreactor at the existing

STP setup will be transferred to IDEA-SBR tank 1 to act as a ‘seed’ sludge.


Once the desired solids concentration in the IDEA-SBR tank is reached, influent from the

existing STP, will be diverted through the new inlet works into IDEA-SBR tank 1, slowly draining

the old bioreactor until empty. The decant from the IDEA-SBR tanks will be diverted directly to

the new UV disinfection system, bypassing the secondary clarifier at this point (still in

construction at this stage). Chlorination at the plant will now be suspended.

Once the mixed liquor concentration in IDEA-SBR tank 1 reaches design levels after

approximately 3-5 weeks, waste sludge will be transferred to IDEA-SBR tank 2 to temporarily

aerobically digest the waste activated sludge (WAS) stream. Dewatering can occur via the new

centrifuge if required.

This process will continue for a further 5-6 weeks without WAS discharge as SBR tank 2

reaches the design level.

The new odour control system will be switched on at this stage.

It is during this time that modifications can be made to existing infrastructure that will be utilised

as part of the upgraded STP. This includes conversion of the primary sedimentation tank to the

WAS gravity thickener, modification of the existing bioreactor to an aerobic digester, and

modification of the existing secondary clarifier to the new balance tank.

Phase 3b - Process Commission Balance Tank

Following modification of the existing secondary clarifier to the new balance tank, flows will be

diverted to the balance tank to attenuate the flow to the UV disinfection units.

Phase 3c - Process Commission Solids Stream

Following completion of the conversion of the existing primary sedimentation tank to the new

gravity thicker and the conversion of the existing bioreactor to the new aerobic digester, the new

units will be process commissioned by receival of the WAS; simultaneously, IDEA-SBR tank 2

will be converted from the primary aerobic digester to its design function as a secondary

treatment process tank.

Following transition into the new sludge treatment system, normal sewage flow will be

transferred to IDEA-SBR tank 2 and plant operation will now be in its fully upgraded form.

The whole process of Phase 3 will take in the vicinity of 3 months to complete.

Phase 4 - Redundant Equipment Decommissioning

The anaerobic digester will be decommissioned during the process commissioning phase with

careful removal of the existing sludge in the four tanks. Several safety procedures will be

carefully followed in the decommissioning phase of the digester as gases pose a safety risk until

all existing sludge is removed. Once the sludge is removed, it will be carted to an appropriate

disposal facility.

Decommissioning of the existing MCC facilities will also be undertaken, as the new controls are

installed.

Phase 5 - Performance Testing

Phase 5 includes the testing of the newly upgraded plant for performance with respect to the

design intent. There will be five groups of performance tests undertaken in order to evaluate the

performance of the new STP against the Project’s requirements.

1. Initial 30 Day system integrity testing

2. Summer period performance tests

3. Winter period performance tests


4. Peak wet weather flow tests

5. Power and consumables test

The initial 30-day system integrity testing will occur at the completion of the commissioning

phase, once the quality of treated effluent and operation of the plant equipment is acceptable.

The results of this performance test will largely confirm whether commissioning has been

successfully completed.

Various aspects of the plant will be monitored to ensure compliance with acceptance testing

criteria. These will include items such as:

Treated effluent quality (e.g. TSS, COD, BOD, TP, TN, Ammonia, pH, alkalinity,

Thermotolerant Coliforms)

Thickened biosolids concentration

Stabilisation of dewatered biosolids

H2S removal in odour control unit

During this time the overall functionality of the integrated STP control system will also be t ested,

including the automatic start sequence of the emergency power generator, and the emergency

shutdown and restart functionality of the STP controls.

2.8.3 Treated Effluent Management During Commissioning

During the commissioning phase outflowing effluent will be tested regularly and continuous

online measurements will be used as appropriate (refer proof of performance testing in the

previous Section).

Treated effluent quality will be maintained as per the current STP emission limits during the six

month commissioning phase. If emission limits (based on the current plant limits) are not being

met corrective action will be undertaken within the plant (including operational changes,

temporary storage or retreatment).

At the end of the 6-month commissioning period treated effluent will meet the newly proposed

emission limits as documented in Section 2.4.3.

2.8.4 Complaints During Commissioning

An online complaints register will be available at all times during commissioning (and

construction) and will be checked daily, with complaints dealt with as soon as possible.

2.9 Off-Site Infrastructure

The site is already serviced by road access (via Treatment Plant Road), power (overhead lines

from the west of the site to the centre of the existing STP), telecommunications and water

supply (enters via the south west of the site to the existing STP).

Minor onsite upgrades to some of these features will be required, including minor maintenance

(no widening) to Treatment Plant Road and the access track to the existing house on site as

well as a new substation within the STP site itself.

The Blackmans Bay STP is being sized for the future design horizon for both the local

catchment as well as the existing Margate, Electrona and Howden STP catchments to allow for

future decommissioning of those other plants. The pipelines required to transport effluent from

those other STPs to the upgraded Blackmans Bay STP do not form part of this application

however; nor is this application contingent on their construction. As such those pipelines are not

considered as part of this application.


There are no other proposed changes to any off site infrastructure required to facilitate the

development.

2.10 Land Tenure and Public Site Access

The existing Blackmans Bay STP is situated on land owned by TasWater and not currently

accessible to the public. The existing site however is surrounded on all sides by land owned by

Kingborough Council and currently available for public recreational use, predominately for

walking and dog exercise.

This proposal will involve the purchase of the land title surrounding the existing STP site from

Kingborough Council to allow for expansion of the STP footprint (the combination of the existing

STP site and the surrounding Council land parcel will form The Site/The Land). Figure 2-3

shows the current land tenure and the proposed parcel to be purchased (the Project Site)

TasWater recognises the current public usage of that parcel of land and will ensure ongoing

public access to the broader site for walking and other recreational activities. In particular, the

Suncoast Headlands Track traverses the site from north to south and this track will be realigned

and retained as part of the works. Access to the track will be maintained during both

construction and operational phases.

During the construction phase temporary fencing will be erected around the construction site

and a new section of the Suncoast Headlands Track established along the western edge of the

property boundary to allow continued access across the site from north/south. Once the

construction phase is completed the temporary fencing will be removed and only the main STP

site itself will be permanently fenced, allowing ongoing recreational access to the remainder of

the site as currently occurs. The Suncoast Headlands Track will be reinstated with only a minor

deviation of its current route.

The construction compound itself will be fully rehabilitated post construction to reinstate the

existing natural and ecological values of the site. A new vegetation screen will be planted along

the western boundary of the new STP to provide screening for nearby residents and users of

the recreational space and Suncoast Headlands Track.

Figure 2-6 illustrates the Suncoast Headlands Track and the construction phase and final

fencing proposal.

Const

ruction

Acces

s Roa


Temp

orary

SCH T

rack (

durin

g con

struc

tion)

Realig

ned S

CH Tr

ack (

post

cons

tructio

n)

Suncoast Headland Track

Suncoast Drive

Suncoast Headland Track

Suncoast Drive

Tinderbox Road

Liberty Court

Wells Parade

Tahun

e Cres

cent

Ephesus Place

Jodie Court

Syracuse Place

Suncoast Drive

Tinde

rbox R

oad

Liberty Court

Tahune Crescent

Wells Parade

Tahun

e Cres

cent

Tahune Crescent

Ephesus Place

Jodie Court

Syracuse Place

526,400

526,400

526,600

526,600

526,800

526,800

5,237,

200

5,237,

200

5,237,

400

5,237,

400

5,237,

600

5,237,

600

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Paper Size A3

LEGENDWaterwayCadastral ParcelDog excersize area

ProposedThe project siteFenced area (STP operational boundary)Construction Compound(site office, parking, machinery, laydown,stockpiles and bunded fuel and chemicalstorage)

Figure 2-6


3. Project Alternatives

3.1 Project Rationale

The rationale behind the Project is outlined in Section 2.3 and at its core is driven by a need to

improve performance of the current STP and cater for projected increases in flow from the area

currently serviced (Kingston, Huntingfield, Blackmans Bay and southern Bonnet Hill) heading

into the next 20-30 years. A very closely linked objective of the Project is to provide the potential

to rationalise the broader STP network of aging infrastructure by providing sufficient capacity in

the upgraded Blackmans Bay STP to cater for projected future flows from the Margate,

Electrona and Howden STPs in order to allow them to be decommissioned in the future.

Details are provided in Section 2.3 of the capacity and deficiencies of these STPs and the

rational for the potential amalgamation.

As noted previously this DPEMP relates only to the Blackmans Bay STP Upgrade and does not

include the decommissioning of the other plants mentioned for potential amalgamation or the

infrastructure required to transfer the sewage catchments from these areas to the Project

Footprint. The Project is not dependent on the amalgamation going ahead, but the plant has

been designed to cater for that eventuality as part of TasWater’s forward planning process.

3.2 Alternative STP Sites

In investigating the amalgamation of STPs in the Kingborough Local Government Area (LGA),

consideration was given to upgrades at any of the existing STP sites as well as the possibility of

a new STP site to which all local effluent could be directed.

The key document investigating these options is the Kingborough Wastewater Management

Strategy, Long Term Strategy (CEE, 2007). This document considers limitations of the existing

STPs (particularly aging infrastructure, STPs at or reaching capacity and existing issues wit h

treatment compliance), the regional context of the existing STPs, the opportunities for reuse

(outlined in Section 3.3), and a risk assessment and investigation of a preferred site for upgrade

and amalgamation. This study considered the regional STPs more broadly (including Taroona

and Woodbridge) but provided focused analysis specifically of the STPs currently proposed for

amalgamation (namely Blackmans Bay, Electrona, Margate and Howden).

The amalgamation of some or all of Blackmans Bay, Margate, Electrona and Howden STPs was

considered in detail by the report; including identification of alternative treatment sites and a

triple bottom line assessment. Alternative sites for amalgamation that were considered included

Margate, Electrona, Howden Road, Barretta Landfill, Brookfield Estate, Electrona Industrial

Zone and Conningham. These options were reviewed and subsequently shortlisted to the four

most suitable sites - Blackmans Bay, Brookfield, Baretta and Conningham. The two existing

sites, Margate and Electrona were discounted due to size limitations and proximity to existing

sensitive uses (e.g. Dru Point Recreation Area) making them unsuitable for expansion to treat

an amalgamated network.

Details of the reuse assessment for these amalgamated flows is available in CEE 2007. The

conclusion of these 2007 investigations was that the most suitable option for combined flows

(Blackmans Bay, Margate and Electrona) when considering economic, environmental and social

factors was a new STP and reuse opportunity at the Brookfield site, followed closely by the

option of upgrading the existing Blackmans Bay STP to take combined flows from the other

existing plants in North West Bay.

The Kingborough Council made a considerable effort to acquire the Brookfield site following the

investigations but was not successful, thereby ruling out this option. Thus the decision was


made to transfer wastes from Margate, Electrona and Howden to the Blackmans Bay plant.

Without the Brookfield site, there is no practical alternative to the continued operation of the

Blackmans Bay STP, as confirmed in a re-assessment of options by Southern Water in 2010.

In summary the culmination of the 2007 study, Kingborough Council’s unsuccessful efforts to

secure the Brookfield property and subsequent assessments undertaken by TasWater

(Southern Water) was that the preferred option would be as proposed – to decommission the

Margate, Electrona and Howden STPs and divert combined flows to an upgraded Blackmans

Bay STP3. The key factors influencing the outcome were:

The existing STPs are at or nearing capacity, as well as experiencing issues with treated

effluent compliance which results in the need to upgrade and expand existing treatment

capacity in the area;

North West Bay is a small and sensitive water body in comparison to the Derwent Estuary

and there is a clearly defined long term objective to remove STP discharges into North

West Bay and redirect those discharges to the Derwent Estuary;

Of the alternative sites assessed (including both existing STPs and greenfield sites) the two

most suitable options were identified to be Brookfield Estate and Blackmans Bay STP;

The new Brookfield Estate STP and associated reuse opportunity was assessed as

requiring more capital investment than Blackmans Bay, but resulted in better social and

environmental outcomes. However, despite considerable effort, the property was not able

to be obtained and therefore the option ruled out; and

The Blackmans Bay site provides suitable size and capacity for upgrade and has an

existing long outfall into the comparatively high energy Derwent Estuary (as compared to

North West Bay) and was therefore assessed overall as being the most suitable option.

3.3 Reuse Investigations

3.3.1 Detailed Reuse Analysis - 2007

As part of the Kingborough Wastewater Management Strategy, Long Term Strategy (CEE,

2007), consideration was also given to reuse opportunities for treated effluent across the

Kingborough municipality for predicted wastewater flows in the years 2015 and 2030.

The 2007 investigation considered reuse flows from all STPs in the Kingborough municipality,

which includes Taroona (now decommissioned) and Woodbridge which are currently not

included in the proposed amalgamation to Blackmans Bay. However, the 2007 study is still

considered a valid information source for the current proposal as (at that time) Blackmans Bay,

Electrona, Margate and Howden STPs made up 90% of flows, with the other plants (Taroona

and Woodbridge) contributing only 10% to the total.

The specific effluent reuse options considered in the development of the sewerage strategy

were:

North Bruny Island, including the Murrayville pastoral reserve located on the east coast

near Barnes Bay, of which about 600 ha is considered suitable for irrigation.

Brookfield (Margate), about 140 ha suitable for irrigation.

3 The decommissioning of Margate, Electrona and Howden and subsequent amalgamation and transfer of their flows to the upgraded Blackmans Bay STP does NOT form part of this application, nor is this application dependant on them. The key reason for inclusion of the broader amalgamation strategy in this DPEMP is to provide context of the chosen sizing and design of the Blackmans Bay STP in order to allow for the potential amalgamation.


Golf Courses and Parks, including:

– North West Bay Golf Course~ 25 ha;

– Kingston Beach golf course

– Parks and ovals in Kingston, Blackmans Bay and Taroona; and

– Dru Point recreation reserve.

The reuse investigation in 2007 (CEE, 2007) involved a water balance for a range of future flow

scenarios and climatic conditions (including the 1 in 10 wet year). The data was used to

consider a number of reuse scenarios, namely:

Full reuse (1 in 10 wet year case) involving large storage of effluent over winter due to

limited capacity for winter irrigation;

Reuse in years of low and average rainfall with a small discharge of effluent in wet years to

avoid carry-over of effluent from one year to the next; and

Partial reuse, consisting of reuse in summer months only with excess effluent to be

discharged via outfall.

This assessment concluded that full effluent reuse is not considered feasible as there is not

sufficient land area available in the region. Similar results were found for the option of full reuse

in dry years and discharge of treated effluent to the environment in wet years; namely

insufficient land availability.

Partial reuse was then investigated further for Bruny Island, Brookfield Estate and other local

opportunities around Margate. A triple bottom line assessment was undertaken for the identified

options.

Reuse of effluent in the summer months on Bruny Island could take approximately 52 % of the

total effluent, but has a very high total capital cost4 of $64 M (for a partial reuse scheme on

Bruny Island) and is not considered viable without external funding. This option also has

substantial social and environmental risks and resulted in a negative overall outcome on the

triple bottom line assessment.

The next largest reuse opportunity identified was Brookfield Estate. This option was further

investigated and found to be able to accommodate only a small proportion (8%) of the total

projected treated effluent volume at a 2030 horizon.

Irrigation on smaller ovals and golf course was found to accommodate only 4% of projected

(2030) treated effluent volumes; resulting in an expensive option for a very small proportion of

effluent.

The resulting outcome of the partial reuse investigations was that the combined issues of land

availability (as noted previously Kingborough Council were unsuccessful in attempts to acquire

Brookfield Estate), social, environmental factors and high capital costs deemed partial reuse

unfeasible.

Other options including industrial reuse, groundwater recharge, river replenishment and direct

provision of treated effluent to households were considered by the 2007 report and discounted

as unfeasible for the Kingborough LGA.

4 Total Capital Costs includes capitalised annual costs at 7%. Numbers are taken from the 2007 reuse investigations (CEE) and therefore are somewhat outdated.


3.3.2 Consideration of New Reuse Opportunities

TasWater has recently (2016) undertaken an internal review of reuse opportunities identified in

the intervening years between the 2007 study and this application. The only new reuse

opportunity identified by TasWater during the period since 2007 is the Arm End Golf Course.

TasWater were approach by the developers of the Arm End Golf Course (across the Derwent

from Blackmans Bay on the tip of the South Arm) to explore opportunities for irrigation water

supply to their development. Initially, consideration was given to provision of treated effluent

from the Rokeby STP; however, this water is fully allocated to current customers in the Coal

River Valley and a supply line would have had to cross the ecologically significant Ralphs Bay.

Subsequently investigations were made into provision of treated effluent from Blackmans Bay

via an undersea pipeline across the Derwent River. The total volume of effluent that the golf

course would require is estimated at 1 ML/day during the summer period and less at other times

of the year. There are minimal additional opportunities for reuse identified at South Arm that

would make it viable for TasWater to fund this reuse project. Given the small proportion of

treated effluent required by the development, the high capital and environmental costs of a

pipeline across the Derwent and the lack of other significant reuse opportunities at South Arm it

is not considered to be economically viable for TasWater to fund a reuse pipeline to the Arm

End Golf Course at this time.

If the golf course development were to proceed and the developer were to fund the reuse

pipeline across the Derwent, there remains opportunity in the future to install the necessary

infrastructure at Blackmans Bay STP to facilitate offtake of treated effluent for reuse.

TasWater will continue discussions with the developer for the Arm End Golf Course and

facilitate future offtake of treated effluent if required as a separate project to the current Project.

3.3.3 Summary

From the 2007 investigation and subsequent considerations, TasWater has determined that full

or partial reuse of treated effluent is not a viable and feasible option for the Project at this time

and therefore will not be committing to a reuse scheme.

However, the proposed Project does not preclude future reuse opportunities and the

improvements in treated effluent discharge quality significantly increases the opportunity for

future reuse in the region. TasWater will continue to investigate opportunities for reuse in the

future.

3.4 Layout at the Blackmans Bay STP Site

Within the Project Site itself the upgraded STP is inherently linked to the existing STP by its

design and therefore must be constructed within and adjacent to the existing plant. This limits

the opportunities for alternative site consideration within the identified Project Site.

The proposed layout (Project Footprint) involves locating the main IDEA-SBRs in an area of

considerable ‘cut’ and as far as possible down the hill towards the existing plant. This serves to

limit visual intrusion and keep the Project as far as practical from the existing residential

properties. The proposed Project Footprint also aims to minimise impacts to native vegetation

and mature eucalypts by siting as much as possible on already cleared land.

The construction compound has been sighted to minimise impacts to native vegetation, utilise

existing infrastructure (access track and house for a site office) and respond to limitations of

terrain. Similarly, site fencing has been modified in response to ecological investigations and

current usage of the existing walking track on site to minimise impacts where possible. The


proposed vegetation screening has been designed to provide a visual buffer to existing

residents as well as recreational users of the broader site.

3.5 Alternative Treatment Plant Technology

Two sewage treatment processes were considered for the upgrade of the Blackmans Bay STP

A Membrane Bioreactor (MBR) and a Sequenced Batch Reactor (SBR). The primary difference

between these processes is that the SBR achieves solids removal by sedimentation (within a

bioreactor) while the MBR achieves solids removal through membrane filtration. It should be

noted that numerous bioreactor configurations can be applied to an MBR, and this selection

depends on the specific design requirements and the treatment objectives.

Through the preliminary design phase, further analysis was undertaken to determine the

appropriate treatment process for the upgrade.

Both MBR and SBR processes were deemed to be capable of achieving the proposed effluent

quality requirements outlined in Section 2.4.3. Both processes were also deemed to produce

comparable odour emissions and allow for appropriate odour management options. Ultimately,

an SBR process was selected based on cost, operability, process robustness and management

of wet weather flows. An analysis of the positive and negative factors for each process type is

summarised in Table 3-1.

Table 3-1 STP Process Selection Criteria

Criteria Membrane Bioreactor (MBR) Sequenced Batch Reactor

(SBR)

Operability × Large number of control loops,

pumps and actuated valves.

× Substantial chemical

use/handling for membrane

cleaning (e.g. citric acid, sodium

hypochlorite)

Additional disinfection only

required for bypass flows

(disinfection provided by

membranes)

Fewer mechanical items,

fewer control loops and

operationally simple

Minimal chemical

requirements

Maintainability × Extensive additional mechanical

equipment (i.e. permeate pumps,

air scour blowers, chemical

cleaning systems). Membrane

renewal and aeration diffusers

required every 7-10 years.

Few mechanical items

(i.e. RAS pumps, mixers,

decanters). Renewal of

aeration diffusers only.

Other additional

equipment

requirements

× Additional finer screening (1-

2mm) required to protect

membranes

× Additional disinfection

required

Effluent quality MBR provides superior effluent

quality in terms of suspended solids

and thermotolerant coliforms

×Class A+ reuse quality water not

utilised by local reuse opportunities

SBR technology can meet

the proposed effluent quality

requirements


Criteria Membrane Bioreactor (MBR) Sequenced Batch Reactor

(SBR)

Footprint Compact bioreactor footprint × Larger bioreactor footprint

Treatment of wet

weather flows

× Need for either large-offline

storage or high membrane

throughput (4xADWF) to treat wet

weather flows

× Odour management

risks/requirements introduced when

storing sewage during wet weather

Cost effective treatment

of wet weather flows by

adopting shortened treatment

cycles

Potential for

malfunctions and

breakdowns

× Potential for membrane fouling

and flux issues

(Significant flux rate reductions

could lead to bypasses during dry

weather. The mitigation against this

would be continual monitoring of

membrane flux, and implementation

of required chemical recovery

cleaning)

× decanter malfunctions can

lead to suspended solids

carryover to downstream

balance tank

(A decanter malfunction

could lead to solids carryover

during dry weather.

Mitigation measures against

this is to provide two

decanters per tank, and also

capture carried over solids in

the downstream balance tank

(the existing secondary

clarifier)

Energy consumption

(OPEX)

× Higher, due to membrane air

scour requirements

Ability to optimise

treatment cycles in dry

weather

Chemical consumption

(OPEX)

× On-going cleaning chemical costs

(e.g. Citric Acid, Sodium

Hypochlorite)

Fewer chemical

requirements

Membrane

replacement (OPEX)

× Membrane renewal required

every 7-10 years.

No renewals on solids

separation equipment

Capital cost × MBR typically ~10-20% more

expensive than an SBR

Less expensive than

MBR


4. Public Consultation

This section provides an overview of TasWater’s commitment to stakeholder and community

engagement implemented to date for the Kingborough Sewage Upgrade Project of which the

upgrade to the Blackmans Bay STP is a component.

Consultation on the Blackmans Bay STP began over a decade ago by the then asset owner,

Kingborough Council, in 2006. This consultation related to the proposed outfall extension but

also considered future expansions of the site. In the intervening years Kingborough Council,

Southern Water and now TasWater has undertaken range of stakeholder and community

engagement activities on various aspects of the overall Kingborough Sewage Upgrade Project.

4.1 Stakeholder and Community Engagement Plan

At commencement of the Project, a Stakeholder and Community Engagement Plan (the Plan)

was developed to guide consultation activities for the Project. The Plan was developed in line

with TasWater’s commitment to early and thorough consultation with the community to establish

a relationship and create awareness of, and involvement in, the project during the decision

making process. It’s important to note that the Plan and included activities are for both the STP

and the associated infrastructure (pipeline route, potential STPs and subsequent

decommissioning of STPs) which do not form part of this application.

The Plan directed activities such as:

Developing key Project messages and Q&As

Drafting and distributing Project newsletters to the community and stakeholders

Establishing and maintaining a Project webpage, including feedback channels such as a

contact person, contact email address, phone number and postal address

Establishing and managing a database of project stakeholders

Drafting and distributing letters to the community and stakeholders

Conducting one-to-one and small group meetings with landowners, stakeholders and

interested members of the community

Conducting community information sessions to provide Project information

Issues regarding the STP upgrade were raised and discussed with stakeholders during the

preliminary design stage so that the community could provide feedback on the proposal and

raise concerns over potential issues during construction.

4.2 Key Stakeholders Engaged

The key parties actively engaged through the consultation process to date include:

Kingborough community

Blackmans Bay residents

Property owners and adjacent neighbours to STP

Kingborough Council – in particular General Manager, Mayor and Councillors

Tasmanian EPA


4.3 Key Engagement Tools

During the course of the Project’s development a number of community engagement tools have

been employed including:

Community information sessions (a total of four have been held during 2015 and 2016,

each spanning three to four days at local community venues);

Stakeholder meetings (with community groups, local residents, individuals and agencies);

Community survey (undertaken in 2013);

Website and online feedback form;

Emails to subscribed community members (approx. 200);

Newsletters and letters to local residents;

Feedback forms;

Phone calls from the community; and

Stakeholder Workshop – in 2016 TasWater engaged Solutions2 to assist with developing

and implementing a workshop for those in the community with a close interest in the

pipeline routes from Margate, Electrona and Howden STPs to the Blackmans Bay STP as

part of the proposed amalgamation.

4.4 Summary of Feedback Received

Much of the consultation to date has been about the overall Kingborough Sewage Upgrade

Project and therefore relates to a range of issues outside of the boundaries of this application.

Of particular relevance to the Blackmans Bay STP site the following themes have been

identified:

General support for improvements in treatment technology resulting in improved discharge;

Odour, and to a lesser extent noise, are local issues of concern to residents within close

proximity to the plant;

Local residents have expressed concerns over visual intrusion of the plant;

Ecological impacts of the discharge have also been raised but to a lesser degree than other

issues; and

Some participants raised questions on STPs system redundancy and planning for future

sewage loads.

These issues have been considered as part of the design process with efforts made to minimise

visual intrusion (plant placement and extent of proposed ‘cut’), reduce odour and noise effects,

minimise ecological impacts on land and at the outfall and ensure the plant is designed to cater

for future flows and to sustain upset conditions.

These matters are discussed in more detail throughout this DPEMP.

4.5 Future Consultation

TasWater is committed to ongoing stakeholder and community engagement . This includes

consultation prior to the DPEMP submission, through the DPEMP advertisement period and

beyond. TasWater will continue to implement the Stakeholder and Community Engagement

Plan and employ the well-established tools (newsletters, letters, meetings, information sessions

and website) through the project planning, construction and commissioning stages.


5. Existing Environment

The Blackmans Bay upgraded STP is located at the site of the existing STP on the margins of

the Blackmans Bay township in southern Tasmania.

The following sections provide an overview of the planning, environmental and social-economic

conditions of the site and immediate surrounds. An assessment of the potential impact of the

Project on these value is provided under the relevant subheadings in Section 6.

5.1 Planning Aspects and Land Tenure

5.1.1 Development Site

The development site encompasses the existing Blackmans Bay STP and an expansion area

immediately to the west (between the existing plant and original caretaker’s cottage). A map of

the development site and the proposed development and associated infrastructure is identified

in Figure 2-1 and Figure 2-2.

5.1.2 Site History

The existing sewage treatment site was developed by Council in the 1980s. A description of the

existing infrastructure on site is detailed in Section 2 of this DPEMP.

The adjoining Council land, to be acquired for the proposed upgrade works, essentially

comprising a buffer around the existing plant to the adjoining residential areas. It is used for

recreational purposes including walk ing tracks and includes the former treatment plant’s

caretaker’s cottage.

The caretaker’s cottage ceased use in 1988, when the plant supervisor vacated the premises.

Council then sought to occupy the property with a Council employee for security purposes. It is

understood that Council has also rented the property privately (it is assumed after Council

ceased responsibility for the STP). The cottage is currently vacant.

As a sewage treatment plant the site is identified as a potentially contaminated site. See

assessment against the Kingborough Planning Scheme 2015 (in Section 6.11) Potentially

Contaminated Code below and Section 6.5.

5.1.3 Proximity to Sensitive Uses

The site is located within 500 metres of the Blackmans Bay urban and fringe urban areas (see

Figure 5-2).

The former caretaker’s cottage is located 90 m from the boundary of the existing plant. This will

be used as the site office during construction, and will not be used for residential use post

construction. The next nearest residences on Suncoast Drive are located approximately 170m

from the boundary with the existing treatment plant. There are also three properties located on

Tinderbox Road, which are located approximately 200-250m from the existing treatment plant

boundary fence.

There is an existing walking track (Suncoast Headlands Track) to the northwest of the existing

sewage treatment plant; this is part of a network of trails along the foreshore and to the

adjoining dog exercise area to the south.

The existing STP is subject to a 300m attenuation area under the Interim Scheme, the objective

of which is to protect the site from encroachment from sensitive use (refer Section 6.11). There

are already existing residences within the attenuation area to the north and the west.


5.1.4 Land Titles

The land tenure and title details affected by the proposed works are summarised in Table 5-1

and the current property boundaries in Figure 5-1.

The boundaries relative to the proposed works are illustrated in Figure 2-1.

A copy of these two titles is provided as an attachment.

Table 5-1 Land Title Details - Development Site

Address Title Reference

(Folio/Reference) Area Owner Extent of Works

116 Tinderbox

Road,

Blackmans Bay

157728/1 1.59ha Tasmanian

Water and

Sewerage

Corporation Pty

Ltd

Upgrade works

114 Tinderbox

Road,

Blackmans Bay

157728/2 9.704ha Kingborough

Council

Expansion of

existing plant

onto part of site


Figure 5-1 Title Plans


5.1.5 Easements

The development site is affected by the following rights of way and service and drainage

easements which are shown on the title plan and Figure 5-1.

The existing treatment plant (known as lot 1) is together with a:

– Right of Carriage Way and Service Right over the Right of Way (Private) and Service

Easement 12m over the adjoining Council land (known as Lot 2).

– Right of Drainage over the Drainage Easement 12m wide over Lot 2

– Right of Carriageway and Service Right (appurtenant to Lot 1) over the Right of Way

“A” (Private) and Service Easement 6m

– Right of Carriageway and Service Right over the Right of Way “B” (Private) and

Service Easement 6m wide over Lot 3

The adjoining Council land (known as Lot 2) is together with:

– Right of Carriageway and Service Right over the Right of Way “A” (Private) and

Service Easement 6m wide over Lot 3;

– Right of Carriageway and Service Right over the Right of Way “B” (Private) and

Service Easement 6m wide over Lot 3

The adjoining Council land (known as Lot 2) is subject to:

– Right of Carriageway and Service Right (appurtenant to Lot 1) over the Right of Way

(Private) and Service Easement 12m;

– Right of Drainage (appurtenant to Lot 1) over the Drainage Easement 12m

A copy of the relevant schedule of easements is attached.

5.1.6 Land Use Zoning

The existing sewage treatment plant is zoned Utilities. The adjoining Council land to be

acquired for the upgrade works is zoned Environmental Living.

The surrounding area is zoned Residential, Environmental Living, Environmental Management,

and Recreation, which reflects the existing uses of residential, recreational (dog park and trails)

and environmental (foreshore areas, geoheritage features, and trails) that surround the site.

The land zoning of the site and surrounding area is illustrated in Figure 5-2 and summarised in

Table 5-2.


Table 5-2 Land Use Zoning – Location & Description

Location Zoning Description

Development Site

Existing Treatment Plant Utilities TasWater

Adjoining Council Land Environmental Living Council

Surrounding Area

Blackmans Bay urban area General Residential Zone boundary is 150m

North of the existing

Treatment Plant on

Suncoast Drive and

extends North

Blackmans Bay residential

areas to lower density where

existing natural and

landscape values are to be

retained

Environmental Living Zone boundary is 130m

West of the existing

Treatment Plant on

Tinderbox Road and

extends West and South

Derwent River, and adjoining

foreshore and walking tracks

located on DPIPW and

Council land

Environmental Management Closest zone boundary is

30m east of the existing

Treatment Plant and

extends south along the

foreshore. There is

additional EMZ land to the

north.

Blackmans Bay Scout Hall

and designated dog walking

area

Open Space Zone boundary is 77m

south of the existing

treatment plant

Const

ruction

Acces

s Roa


Suncoast Drive

Tinderbox Road

Liberty Court

Wells Parade

Tahun

e Cres

cent

Ephesus Place

Jodie Court

Syracuse Place

Suncoast Drive

Tinde

rbox R

oad

Liberty Court

Tahune Crescent

Wells Parade

Tahun

e Cres

cent

Tahune Crescent

Ephesus Place

Jodie Court

Syracuse Place

526,400

526,400

526,600

526,600

526,800

526,800

5,237,

200

5,237,

200

5,237,

400

5,237,

400

5,237,

600

5,237,

600

G:\32\18107\GIS\Maps\MXD\3218107_005_Figure5-1_LandZoning_RevC.mxd

0 50 10025





Job NumberRevision C

32-18107

27 Jul 2016

Land ZoningDate

Data source: Data Custodian, Data Set Name/Title, Version/Date. Created by:jtoregan


Paper Size A3

LEGENDWaterwayCadastral parcelDog excersize area

Tasmanian Planning Zones (LISTmap, 2016)10.0 General Residential14.0 Environmental Living19.0 Open Space28.0 Utilities29.0 Environmental Mangement

ProposedThe project siteFenced area (STP operational boundary)Construction compound(site office, parking, machinery, laydown,stockpiles and bunded fuel and chemicalstorage)

Figure 5-2


5.2 Environmental Aspects

The following subheadings summarise the environmental context of the site, however full details

for all salient topics are found under the relevant subheadings in Section 6.

5.2.1 Physical Characteristics of the Site

The Project Site is located immediately adjacent to the coast, along the lower Derwent Estuary.

Elevation levels range from sea level to approximately 60 m AHD. The Project area slopes from

hills to the west down to the estuary to the east, the site is bordered by a mosaic of regenerating

cleared land, urban open space and remnant native vegetation. The land surrounding the

current Blackmans Bay STP site is currently owned by Kingborough Council.

In general, the site is partially vegetated with areas of developed space and regenerating

cleared land.

5.2.2 Weather and Climate

The Blackmans Bay region has a cool temperate climate. It is maritime-influenced and

experiences generally cool summers and mild winters. Climatic data from the Hobart weather

station (094029) (BOM 2016) shows:

Temperature ranges from a mean minimum of 4.6 C in July and mean maximum of 21.7 C

in January and February.

Rainfall in the Hobart and Blackmans Bay region is distributed relatively evenly over the

year. The Project Site receives an average annual rainfall of approximately 614 mm. Lower

average rainfall of 39.7 mm occurs in February and the maximum average rainfall of 61.3

mm in October.

The most common winds at Blackmans Bay come from the south-east and the west. There

are fewer winds from the north and south, possibly due to the sheltering effects of the hills

and trees to the north and south of the Project Site. Winds from the south-east occur for

approximately 15% of the time. Further information on wind patterns is provided in Section

6.1.

5.2.3 Geology and Geomorphology

Broadly, the geology of the area around the Project Site consists of hard rock; predominately

Jurassic dolerite. The dolerite intrusion extends about 1 km north and 1 km south of the site,

ending just prior to Tinderbox Road to the west. Further inland, the rock is mainly Triassic quartz

sandstone.

The topsoil at the Project Site is shallow (<100 mm) and is mostly podzolic. There are no known

areas of potential acid sulphate soil near the Project Site.

The geomorphology of the region around the Project Site is characterised by the coastline

directly east of the site (dominated by a steep hard rocky cliff) and a narrow pebble/cobble

beach, with rock shelves extending offshore.

A geoconservation site is mapped on TheLIST database along the coastline within the

boundaries of the Project Site but outside of the proposed Project Footprint.

5.2.4 Natural Hazards

The Site is mapped as low coastal erosion hazard band on TheLIST database, indicating some

risk of coastal regression by 2100. According to TheLIST database the Project Site is not within

a Proclaimed Landslip Zone and is categorised as Low to Medium Landslide Hazard Band. The

Low Hazard Band relates to sites with 11 to 20 degrees’ slope and no known landslide features,


but a susceptibility. The Medium Hazard Band relates to site with a >20 degree slope and with

known landside features or within a landslide susceptible area. The proposed Project features

are predominately concentrated on the parts of the Project Site within the Low Landslide Hazard

Band.

The site is not subject to flooding due to its natural slope towards the Derwent Estuary. The site

is not known to be particularly susceptible to fire.

5.2.5 Surface and Groundwater

Surface drainage flows down gullies to the top of the cliff. Drainage at the existing STP site is

controlled and discharged through existing stormwater pipes.

There are two water bodies within the Project Site, an ephemeral drainage line to the north of

the current STP and a natural waterway to the south. Both waterways are outside of the

proposed Project Footprint.

The surface water bodies drain into the adjacent Derwent Estuary which bounds the site to the

east. Considerable monitoring data is available for the Derwent Estuary, which is characterised

in Section 6.8.

Depth to groundwater at the site is not known and there are no nearby extraction bores.

5.2.6 Reserves and Wilderness Areas

There are Informal Reserves adjacent to The Project Site at both the northern and southern

ends, but no reserves within the site itself. Approximately 0.5 km south of the Project Site is the

Fossil Cove Conservation Area, which will not be impacted by the Project.

There are no wilderness areas in the vicinity of the Project Site.

5.2.7 Existing STP Licence Arrangements

The existing plant is operated by TasWater under the following licence arrangements:

Licence to Operate Scheduled Premises No. 3326 (18/11/1987); and

Permit Conditions - Environmental No. 7551 (10/12/2008).

5.2.8 Ecological Context

Ecological surveys of the Project Site were undertaken in 2014 and again in 2016. These

surveys found the site to contain a mosaic of developed areas, open exotic grassland and

native vegetation communities.

Native vegetation communities found on site in 2016 include Eucalyptus globulus dry forest and

woodland (listed community under the Nature Conservation Act 2002), Eucalyptus amygdalina

forest and woodland on dolerite and Allocasuarina verticillata forest. Small areas of these

communities will be impacted by the Project Footprint, which is predominantly constrained to

already cleared land.

There were no threatened flora species found on site during either of the ecological surveys.

The surveys found relatively limited habitat values for threatened fauna species within the

Project Site, with the exception of the swift parrot which could nest and feed within the eucalypt

species found on site. Some eucalypts will be impacted by the Project; the potential impact of

this is assessed in Section 6.7.

A small number of environmental weeds were identified on the Project Site and their

management forms part of proposed management and mitigation measures in Section 6.7.

Black

mans

BayD

olerite

Conta

ct

526,400

526,400

526,600

526,600

526,800

526,800

527,000

527,000

5,237,

200

5,237,

200

5,237,

400

5,237,

400

5,237,

600

5,237,

600

5,237,

800

5,237,

800

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0 50 10025





Figure 5-3


32-18107

27 Jul 2016

Reserves and Geomorphology FeaturesDate



Paper Size A3

LEGENDContours (10 m)WaterwayElectrical to site (OH)Cadastral ParcelDog excersise areaGeoconservation site (listed)Informal Reserve on other public land

ProposedThe project siteConstruction compound *Existing fenceNew fenceSTP infrastructure

* site office, parking, machinery, laydown, stockpiles and bunded fuel and chemical storage.


5.3 Socio-economic Aspects

This section describes the existing social and economic environment that may be affected by

the Project.

The existing Blackmans Bay STP currently treats wastewater from residences and commercial

areas in Kingston, Huntingfield, Blackmans Bay and southern Bonnet Hill. Following completion

of the Project, wastewater will also potentially be received from Margate, Snug and Electrona as

part of the aforementioned amalgamation scheme. All of these suburbs are part of the

Kingborough LGA.

The Kingborough LGA is essentially residential in character and, according to the ABS 2011

census, has the highest population growth rate in Tasmania (approximately 9% between 2006

and 2011). It is located 12 to 35 km south of Hobart and has a long stretch of coastline (330

km).

The business district is in Kingston, which is the major commercial, retail and administrative

centre in the region. The total population of Kingborough is approximately 34,000 persons (ABS

2011) including 10,000 persons in Kingston (which are generally a younger population) and

over 1,200 persons on Bruny Island.

The median age over the whole of Kingborough is 40 years (36 years in Kingston) and the

population is comprised of 52 % females and 48 % males. The age distribution is illustrated in

Figure 5-4. This figure highlights the gap in 20-30 year ages, while there is a high proportion of

older persons, particularly in the 55 to 65 age groups. Kingborough, and Tasmania in general,

has an aging population both numerically (absolute number of people aged over 65 years) and

structurally (proportion of people aged over 65 years).

Other demographic features of Kingborough are:

There is a higher average income than elsewhere in Tasmania;

Kingborough is above the national average in terms of socio-economic advantage;

Kingborough has lower unemployment than elsewhere in Tasmania;

There is higher educational achievement than in many regions in Tasmania (other than

Battery Point and Sandy Bay); and

Kingborough has a higher proportion of people working in the professions, management or

senior administration positions than other regions of Tasmania.


Figure 5-4 Age and Sex Pyramid for Kingborough (ABS Census, 2006)

According to the 2011 census, employment patterns in Kingborough are: 30 % of residents are

employed in government - professional or administration; 20 % in construction; 15 % in retail; 12

% in health or community service; and 10 % in education. Manufacturing and primary industry

are small sectors of employment in the Kingborough LGA.

The Project offers major advantages to the residents (present and future) of Kingborough,

including:

Allowing for continued development in existing catchments of Kingston, Blackmans Bay

and Huntingfield;

Potentially allowing for continued development in Margate, Snug and Electrona;

Improving odour conditions for residents living near the existing Blackmans Bay STP with

improved odour control;

Reducing nitrogen inputs to the Derwent Estuary with potential for improved water quality

and lower risk of algal blooms; and

Allowing TasWater to consolidate and enhance the overall Kingborough sewerage system

so underperforming STPs at Electrona, Margate and Howden can be closed, providing long

term benefits to North West Bay.


6. Existing Conditions, Potential Effects

and Management

6.1 Air Quality

6.1.1 Existing Conditions

Ambient air quality within the vicinity of the Project is generally considered to be of a good

quality with the exception of fugitive odour events that occur from time to time from the existing

STP.

Between April 2010 and June 2016 TasWater received 38 complaints from the public in relation

to fugitive odour from the existing STP, with 28 of these events occurring between 2013 and

2014. The majority of complaints have been received from properties to the north of the site

including those on Suncoast Drive, Liberty Crescent and Tahune Crescent.

Other than odour from the existing STP, no other air quality issues have been identified in the

area.

6.1.2 Performance Requirements

The Tasmanian Environmental Protection Policy (Air Quality) 2004 (EPP) provides a framework

for the management and regulation of both point and diffuse sources of emissions to air, and for

pollutants with the potential to cause environmental harm. This EPP is made pursuant to the

provisions of section 96A-96O of EMPCA.

The Air Quality EPP goes on further to state a 2 odour unit (OU) 99.5th percentile, 1-hr average

design criteria for new projects. This design criterion is normally applied at the property

boundary (i.e. ‘The Land’).

The key performance requirements relate to maintenance of air quality during the construction

and operational phases of projects to minimise potential impacts to site workers, local residents

and the environment.

6.1.3 Potential Effects, Management and Mitigation

Dust

Dust may be generated throughout the construction phase of the Project through various

pathways, including the excavation of materials for construction, demolition, loading and

unloading of building materials, road construction and vehicular movements throughout the

Project area on unpaved roads. Once operational there is no change to potential dust

generation from this site (compared to the existing STP) and dust management is not

considered to be an issue for the operational phase.

Potential impacts from dust generation during construction include respiratory impacts to

workers, residents, flora and fauna (coating of flora can restrict respiratory processes) and

impacts to visual amenity through dust plumes.

The following management and mitigation measured will be employed during the construction

phase of the Project to minimise dust impacts:

Sealed roads will be used to access the site where available;

All incoming trucks will have their loads covered;


Spraying of stockpiles and roads if dust generation becomes problematic, with the potential

use of dust suppressants if water spraying is not sufficient;

Daily visual monitoring by site staff;

Maintenance of an online complaints register to monitor any dust complaints;

Retaining existing vegetation where possible;

Staging works to minimise areas of disturbance at any one time before working on other

areas;

Using jute mesh where applicable following works;

Redirecting all recreational users of the site to the west of the Construction Compound

during the construction phase (refer Figure 2-6) to limit direct dust exposure; and

Ceasing work in dry and extremely windy conditions.

With these measures in place the residual risks from dust generation are low. The nearest

residence to the site is approximately 170m from the STP fence boundary and offsite dust

impacts at this distance are not expected, with the management measures in place.

With the low potential for impacts for dust, together with the proposed management and

mitigation, residual impacts as a result of the Project are considered likely to be negligible.

Engine Exhaust

Vehicle emissions in the Project area will temporarily increase as a result of the machinery and

vehicles required during construction activities only. The additional volumes of engine exhaust

emissions compared to those emitted under ambient conditions for the area are considered

negligible.

Potential for impacts are limited to recreational users of the adjacent park areas if exposed for

long periods of time, which is considered an unlikely scenario.

Management and mitigation for the Project will include the following aspects:

Emission levels to be taken into account during selection of machinery;

Scheduled maintenance of all vehicles, earth moving equipment and other combustion

engines to maximise emission quality; and

Construction area to be fenced to prevent exhaust exposure to recreational users.

With these management and mitigation measures in place, residual impacts to the environment

from engine exhaust emissions are considered to be negligible.

Odour

Fugitive odorous emissions may be released from the Project from several sources, including

the inlet works, IDEA-SBRs and aerobic digesters. Potential for impacts may also increase as a

result of malfunctioning equipment during STP operation or during upset flow conditions. This

has the potential to impact on the amenity of the local area, including nearby residential

dwellings, with impacts dependant on wind strength, direction, and volume of odorous

emissions.

To assess odour emissions from the upgraded STP MWH was commissioned to prepare a 3D

odour model of the site and proposed development. The full report is provided in Appendix E

with the salient information summarised below.


The odour modelling report considered a total of seven sensitive receptors around the STP site

as illustrated in Figure 6-1. The polygons on the figure represent the current STP boundary

(blue line) and proposed site boundary (the Boundaries of the Land – red line).

The following sensitive receptors were included in the model:

SR1: Rural property to be purchased by TasWater. Note, this property is part of the land to

be acquired by TasWater from Council. The house will be used as a site office during

construction and demolished at the end of the construction period.

SR2: Rural property

SR3: Rural property

SR4: Residential property along Suncoast Drive



SR7: Rural property

Figure 6-1 Sensitive Receptors considered in Odour Assessment (Source:

MWH 2016)


To assess the likely impacts of the Project on the surrounding environment, 3D odour modelling

was undertaken for a variety of scenarios (Appendix E). The defined criteria for the odour

modelling was to achieve no nuisance odours at nearby residences together with meeting the

odour criteria under EPA Tasmania’s Environment Protection Policy (Air Quality) 2004 which

requires an odour limit of 2 odour units based on a 1-hour averaging periods and 99.5%

compliance measured at or beyond the facility boundary.

The modelling was undertaken using the modelling program CALPUFF, which was setup and

performed in accordance with the Tasmanian EPAs current draft of Tasmanian Atmospheric

Dispersion Modelling Guidelines V 0.93e. The full modelling methodology, including

meteorological sources, dispersion options, terrain elevation and odour emission data and

assumptions are available in the full modelling report in Appendix E. An aerial image showing

the main emission source locations is provided below. The following key sources of odour (and

corresponding process units) were considered in the assessment (full details refer Appendix E

and map showing key infrastructure refer Figure 2-2):

Inlet works (INWRKS);

Flow distribution channel (FLWDST);

Inlet works return pump station (IWPUMP);

General purpose pump station(GPPUMP);

IDEA-SBR tanks (numerous emissions based on time-based treatment phases);

Gravity thickener (GRAVTH);

Aerobic digester (DIGAER, DIGANO);

Dewatered cake self-loading bins (SPIROT); and

Odour Control Facility Stack (within the Odour Control Plant) (BTFOCF).

Figure 6-2 Major odour emission sources modelled (Source: MWH 2016)


Five scenarios were considered for modelling for the Project, as listed in Table 6-1. The five

scenarios covered a range of potential events, including inlet works maintenance, sludge

processing upsets, and a simulated worst-case upset in treatment process.

The variance between the scenarios was the Specific Odour Emission Rates (SOERs) used for

each potential odour emitting source within the Project. The SOER was altered for each piece of

equipment or area of the Project, according to each scenario.

The worst-case upset scenario (Scenario 3) simulates a major failure in all process areas. This

is considered an unrealistic event, but was included to demonstrate a simulated worst case.

This scenario should not be considered as a high flow event, or the event of a malfunction in a

single area (both more creditable scenarios) which would result in much lower odour emissions.

A commissioning scenario was also investigated, but as SOERs for the scenario were lower

than the normal operating scenario, modelling was not deemed necessary (i.e. odour profile

during commissioning is likely to be similar or less than under normal “full” operations).

The modelled results are shown in the output diagrams in Figure 6-3 to Figure 6-6. On each of

these images the dashed red line represents the existing STP boundary, the blue dashed line

represents the proposed STP boundary (The Land) to be acquired from Kingborough Council.

The solid coloured lines represent the 2 odour unit contour, based on each modelled scenario.

Table 6-1 Odour Modelling Scenarios

Scenario Description Specific Odour Emission Rates (SOER)

Scenario 1 Normal STP

Operation

Normal Operating SOER as per Appendix E

Scenario 2 Inlet Works

Maintenance

Period

Normal Operating SOER with:

100% increase in SOER for inlet works

Scenario 3 Upset in

Treatment

Process


100% increase in SOER for inlet works, flow distribution

channel, inlet works return pump station, general

purpose pump station, IDEA-SBR tanks, gravity

thickener, and aerobic digester.

Scenario 4 Upset in Sludge

Process


100% increase in SOER for areas surrounding the

centrifuge building

Scenario 5 Commissioning

Activities

Commissioning SOER as per Appendix E

(Model not run as SOERs were less than Normal

Operating SOERs)


Figure 6-3 Odour Modelling Scenario 1: Normal Operating Conditions (Source:

MWH 2016)


Figure 6-4 Odour Modelling Scenario 2: Inlet Works Maintenance (Source:

MWH 2016)


Figure 6-5 Odour Modelling Scenario 3: Upset in Treatment Process (Source:

MWH 2016)


Figure 6-6 Odour Modelling Scenario 4: Upset in Sludge Process (Source:

MWH 2016)


The results show that under normal operating conditions (Scenario 1), the EPA odour criteria

(2 ou) is met well within the Project Site (The Land). Scenario 2 (Inlet Works Maintenance

Period), showed very similar results to normal operating conditions, as was the case in Scenario

4 also (Upset in Sludge Process).

The worst-case Scenario 3 results show that the EPA criteria (2 ou) are not met at the southern

Project Site boundary (The Land), with the 2 OU contour extending ~50 m past the boundary.

As discussed, this scenario is highly improbable, but shows the worst possible case that could

occur as a result of the Project. In their report MWH conclude that this scenario (3) is not

considered to be a realistic scenario and all realistic scenarios resulting in increases in liquid

stream emissions are unlikely to exceed the 2 OU limit at the boundaries of the land.

Regardless of the unlikeliness of this “scenario 3”, consideration is given to how far the

predicted 2 odour unit contour extends beyond the boundary. In this scenario, the 2 odour unit

extends only 50m beyond the boundaries of the land and into a Council owned parcel of land

zoned as “open space”. Given the ownership and zoning (residential development is prohibited

in the open space zone) the potential impacts on this small area of land are minimal even in the

unlikely event of “scenario 3”.

The modelled scenarios focus on impacts outside of the boundaries of the land; however, it is

noted that ongoing recreational use within that boundary will be accommodated by the Project.

The area surrounding the existing STP is already used for walking and other recreation and is

already subject to odour impacts from the existing STP. Under the upgraded STP odour impacts

on this land will be improved (due to improved odour treatment). Of particular note, all scenarios

aside from the unrealistic “scenario 3” result in the 2 odour unit contour being contained almost

entirely within the proposed fenced area of the new STP. The areas of the site likely to be used

for public recreation (western portion) are outside of the modelled are of impact. Given the

current odour conditions of the site, the predicted 2 odour unit contours and the proposed

fenced STP extent, the impact to recreational users of the site from odour is considered to be

negligible.

MWH also investigated management of odour during adverse weather conditions, different

times of day, during biosolids export and during construction with the following findings:

Time of day – as modelling did not show any off site impact for any of the scenarios likely to

eventuate, time of day impacts were not considered further.

Adverse weather conditions - during storm flows the retention time within the sewer

decreases and wastewater tends to become more dilute, reducing odour potential.

However, first flush of stormwater can deposit silted sludge into the inlet works leading to

short periods of increased odour form the inlet works. For a plant the site of Blackmans

Bay, this rarely affects plant downstream of the inlet works and was not considered further.

Odour during biosolids export – This risk will be managed through the design of self-loading

enclosed spirotainer type bins which are filled on demand via enclosed conveyors. The

spirotainers and conveyors are ventilated at a high rate to contain odour and the sludge is

not exposed to atmosphere during its removal. Odour produced from the dewatered

biosolids will be contained at all times. As such odour nuisance caused by out -loading

events is not envisaged with the proposed design.

Construction – A detailed odour mitigation plan will be prepared for the construction phase

of the project and include:

– Network dosing to reduce site gas levels and potential for odour nuisance;

– Maintaining the existing odour treatment as long as possible, until upgraded odour

treatment is operational;


– Regular rebalancing and surveillance of odour control systems during construction to

ensure satisfactory operation;

– Prompt removal of sewage products and cleaning of decommissioned vessels;

– The use of atomization sprays (if required) during the de-gritting and removal of

products from the digester;

– No storage of odorous products on site; and

– Phased start-up of plant to enable new odour control facilities to acclimatise and use

downstream carbon during this period to prevent odorous gas discharge.

The potential for power failure at the site has been addressed under Section 2.5.9 and involves

the supply of emergency power generation in the event of power outage. The odour control

system will continue to operate (through emergency power generation) during power outages

and no significant changes to odour impacts are anticipated. The modelled scenarios include

consideration of upset/malfunction in the treatment process and the potential for changed odour

conditions as a result.

With the odour control measures in place the residual odour impact during both construction

and operation of the upgraded STP is limited and an improvement in relation to current site

conditions.

6.1.4 Monitoring, Review, and Adaptive Management

Along with proactive community consultation leading up to, and during, construction, the

TasWater online complaints register will be the main vehicle for the monitoring of problematic air

emissions. If complaints regarding air quality, including odour are received, the source of the

issue will be isolated and assessed for further management and mitigation.

Visual identification of dust plumes will trigger management and mitigation actions, including

identifying the source of emissions and mitigating accordingly using the options outlined in the

relevant sections above.

Review of air emission management and any incidents that occur throughout each

environmental reporting period will be addressed in annual environmental reports to the EPA.

Commitment 1 Trucks with potentially windblown materials will be

covered.

Commitment 2 Daily visual monitoring of the site for dust will be

undertaken during construction and water sprays applied to roads

and stockpiles if needed.

Commitment 3 A complaints register will be established for both the

construction and operational phases. All complaints will be logged,

actioned and all outcomes documented.

Commitment 4 TasWater will undertake community and stakeholder

engagement leading up to and during construction.


6.2 Surface Water Quality

This section concentrates on potential impacts to freshwater surface waterbodies around the

Project. Potential impacts to the marine environment from effluent discharge from the STP, is

covered in Section 6.8 - Marine and Coastal.


The Project Site is set on easterly sloping land, with the Project Site boundary meeting the sea

cliffs to the east. There are two existing ephemeral waterways within the Project Site:

A modified drainage line to the north-east of the Project Footprint which is not registered on

the Conservation of Freshwater Ecosystem Values (CFEV) database; and

A slightly larger ephemeral creek to the south of the Project Footprint, listed on the CFEV

as a ‘Conservation Value C’ waterway with a naturalness value of ~0.9, meaning the creek

is in close to natural condition and has the lowest rated conservation value.

There is a network of drainage systems on the existing site and the majority of stormwater is

collected and discharged via stormwater drains to the nearby creeks and over the cliffs to the

marine environment.

Existing water quality within the waterways is unknown, with no requirement under the existing

operating licence to monitor the sites.


The key legislation, policy and guidelines of relevance to surface water management in

Tasmania are the:

Water Management Act 1999;

State Policy on Water Quality Management 1997 (Water Policy);

Inland Fisheries Act 1995;

Environment Protection & Biodiversity Conservation Act 1999 (EPBC Act) - noting the

project is a Controlled Action (refer Section 8); and

Tasmanian Threatened Species Protection Act 1995 (TSPA).

No PEVs have been set for either of the waterways on the Project Site and due to their

ephemeral nature are unlikely to support any significant species or communities. However, the

waterways drain to the marine environment, with the PEVs for this environment described in

Section 6.8, and have been adopted for this section.


Potential sources of discharge to local surface waters from the Project include contaminated

stormwater run-off, major leaks from treatment infrastructure, and large scale spills of chemicals

or fuels.

Discharge of contaminated fluids to the waterways surrounding the Project Footprint have the

potential to have acute/chronic toxic effects on flora and fauna in the immediate environment, as

well as the flora and fauna and recreational users in the eventual downstream marine and

coastal environment, including potential for immunological risks to recreational users from

discharge of untreated sewage.

Management of Dangerous Goods and Environmentally Hazardous Materials has been

discussed in detail in Section 6.6, including the management and mitigation for treatment

infrastructure leaks.


The Project Specific Guidelines required confirmation of any vegetation clearance within 10 m of

a waterway or within the coastal area. It is confirmed that there will be no vegetation clearance

within 10 m of any watercourses and there are no works planned for the coastal area east of the

existing STP site.

Construction Phase Management

A Soil and Water Management Plan (SWMP) will be developed for the construction phase and

incorporated into the site Construction Environmental Management Plan (CEMP). The principles

of Soil and Water Management as set out on the EPA website will be followed (and further

detailed in that plan) including:

Minimising areas of soil disturbance, staging the soil disturbance work and retaining

vegetation where possible;

Establishing a stabilised site access and wheel wash point within the Construction

Compound, with resulting drainage to the sediment control features;

Installing diversion drains around the up slope of the construction footprint and any material

stockpiles;

Covering material stockpiles or installing sediment fences down gradient as required; and

Installing and maintaining collection drains and small retention basins to capture site

stormwater during construction.

With the proposed management and mitigation of wastewater and stormwater, the residual risk

of contaminants reaching the identified waterways are considered low, with potential impacts

likely to be negligible.

Operational Management

The proposed upgrade results in a small increase in roofed areas, access roads and hardstand

areas. All new roofed areas will be sloped and drain to adjacent hard stand. New hardstands

will be sloped to direct stormwater away from the site and into constructed grass swales before

diffuse discharge into the surrounding environment. Diversion drains will be installed around the

upslope edge of new hardstand areas to direct clean stormwater away from the site. Some of

the newly generated stormwater will be captured by the existing stormwater drains through

natural surface flows (e.g. from parts of the new access road). These existing drains report to

the nearby creek and over the cliffs to the marine environment.

In accordance with the requirements of the Kingborough Interim Planning Scheme 2015, during

the detailed design phase of the project a detailed stormwater design will be prepared (including

review of the existing stormwater capture) to achieve the stormwater management targets for

new developments as set out in the State Stormwater Strategy 2010 (unless it is not feasible to

do so). Any installed features (such as vegetated swales) will be planned to avoid any impacts

to existing native vegetation.

Potentially contaminated areas of stormwater will be collected via new pipework and directed to

the inlet works of the new plant for treatment. This includes the sludge bund loading area, the

inlet works, screenings and grit collection bin area and the diffuser wash-down area near the

IDEA/SBR tanks.


Weekly monitoring of water and sediment control measures will be undertaken during the

construction phase, with additional monitoring within 24 hrs of any storm event.


Commitment 5 A Construction and Environmental Management Plan

(CEMP) will be developed prior to commencement of construction.

Commitment 6 A Soil and Water Management Plan (SWMP) will be

incorporated into the Site Construction and Environmental

Management Plan (CEMP).

Commitment 7 Weekly monitoring of water and sediment control

measures will be undertaken during the construction period, with

additional monitoring within 24 hrs of a storm event.

Commitment 8 Prior to construction a detailed stormwater design will

be prepared (including review of the existing stormwater capture)

to achieve the stormwater management targets for new

developments as set out in the State Stormwater Strategy 2010

(unless it is not feasible to do so).


6.3 Groundwater


There are no known groundwater investigations from the Project site or direct surrounds. The

closest bore to the Site is up gradient, 850 m to the south west.

Groundwater flow is inferred to drain across the site from west to east following the natural

contour and culminating at the coast line.

There is no known productive aquifer at the Project site, which sits at the bottom of a sloping

catchment. The Project sits on Jurassic dolerite, with an unknown depth to groundwater layers.

From the topography of the site it can be assumed that any groundwater will report to the cliff

faces and drainage lines surrounding the site.

There is potential that the existing STP on the Project site may have leaked over the years into

the groundwater system, however no impacts on the shoreline or drainage lines have been

investigated.

In summary, any groundwater present is not used for consumption and is does not appear to be

supportive of any ecosystems.


The proposal should be consistent with the objectives and requirements of relevant water

management policies and legislation, including the Water Management Act 1999 and State

Policy on Water Quality Management 1997 (Water Quality Policy). In particular, it must be

demonstrated that the proposal will not prejudice the achievement of any water quality

objectives set for water bodies under the State Policy on Water Quality Management, which

defines water quality objectives as the most stringent set of water quality guidelines which

should be met to achieve all of the PEVs nominated for that body of water.

The relevant PEVs for groundwater are based on the Total Dissolved Solids (TDS) of the water.

With results of <1000 mg/L expected in the area (i.e. fresh water), the relevant PEVs are listed

in Table 6-2.

Table 6-2 Relevant Groundwater PEVs and Water Quality Indicators

PEV Existing Use Water Quality Indicators

Maintenance of

Ecosystems

Unknown The water quality objectives to protect environmental

values shall be the criteria specified in the ANZECC

2000 guidelines for the chosen level of ecosystem

protection. In this case the 95% level of protection

(moderately disturbed ecosystems) is appropriate for

toxicants.

Potable None Those criteria specified in the NHMRC & NRMMC

(2011) Australian Drinking Water Guidelines (ADWG)

Potable Mineral

Water

None

Agriculture, Parks

and Gardens

None Those criteria specified in the ANZECC 2000

irrigation guidelines


PEV Existing Use Water Quality Indicators

Stock Watering None Those criteria specified in the ANZECC 2000

livestock drinking water guidelines

Industrial Water

Use

None Those criteria specified in the ANZECC (1992)

guidelines for industrial use. These guidelines have

been rescinded due to the specific nature of water

quality requirements for various industries.

Primary Contact

Recreation

None Those criteria specified in the ANZECC 2000

guidelines which defer to the WHO Guidelines for

safe recreational water environments (current version

2003) which in turn defers to a default value of 10

times the drinking water guideline, in this case

ADWG (NHMRC & NRMMC 2011).

Buildings and

Structures

None The groundwater shall not be corrosive to structures

or building materials (pH, sulfate, redox potential).


Construction

Construction of the project has the potential to impact groundwater through spills of liquids,

including hydrocarbons, permeating into the groundwater.

During construction, to mitigate against impacts of fuels and chemical spills, all potentially

hazardous substances will be stored within the Construction Compound in locked and bunded

storage areas. All refuelling of construction machinery will be undertaken in bunded laydown

areas, as detailed in Section 6.6. An emergency spill management protocol will be established

and documented in the Site Construction Environmental Management Plan (CEMP).

The residual risk to groundwater is considered to be low.

Operation

During operation there is the potential for several sources of liquids to enter the groundwater

system. This may include stormwater run-off, hydrocarbon or chemical spills or leaking of

wastewater from treatment facility components (e.g. inlet works or IDEA-SBRs). The potential

impacts would be dependent on the volumes released and the receptors present at the exit

point of the water into the greater environment. Long term leakage of untreated sewage to the

coastline through the groundwater vectors mentioned may result in deleterious impacts to the

marine and coastal environment, including impacts to recreational users of the area.

The majority of the wastewater treatment at the Project will occur in closed vessels and

pipelines, which will be designed with corrosion resistant materials to minimise the chance of

leakages occurring. Computer systems and sensors integrated into the treatment system will be

capable of detecting irregular flows or operational behaviour of equipment, providing feedback

to plant operators to enact on, as reported in Section 6.6.

Regular inspections of areas susceptible to leakages, including pipelines, flanges, water holding

tanks and reactors will be undertaken as part of routine maintenance of the Project.

All hazardous substances and dangerous goods will be stored in roofed and bunded facilities.

Refuelling of machinery such as generators will be a rare occurrence during operation and will


not involve large volumes of fuel. A spills contingency plan will be incorporated into the Site

Operational Management Plan (OMP).

With the outlined control measures in place the risk to groundwater from site operation is

consider to be low and, most importantly, improved from current conditions due to significant

upgrade and improvement to infrastructure on site.


Inspection of the Project components for leaks or risk of leaks will be undertaken on a regular

basis, with each aspect of the treatment process inspected as required by specification of the

manufacturer. Plant operations will be monitored both manually and remotely on a daily basis.

These processes will allow for early detection of any potential leakage risk during operation.

Any spills of potentially environmentally harmful liquids greater than 100 L during construction or

operation will be reported to the EPA and groundwater monitoring will be undertaken if

warranted (as determined by the EPA), with monitoring requirements to be determined in

consultation with the EPA.

No direct groundwater monitoring is proposed at the current time due to the low likelihood of

significant impacts to the groundwater system or the receiving environment.

Commitment 9 Any spills of environmentally harmful liquids greater

than 100 L will be reported to the EPA, with commitment to

undertake a groundwater monitoring event if deemed necessary by

the EPA.


6.4 Noise Emissions

Specialist consultants VIPAC Engineers and Scientists (Vipac) were engaged to undertake

noise assessments for the Project. In 2014 Vipac prepared a preliminary report for the site

which characterised the existing noise environment and established noise criteria for the

upgraded plant to meet. In 2016 Vipac prepared a follow up report which assessed the likely

noise impacts from the proposed STP against the pre-established criteria. The results of those

two assessments is summarised below with the full reports available in Appendix F.


The existing acoustic environment of the residential areas surrounding the Project includes light

traffic noise from the local roads (Tinderbox Road and Suncoast Drive), faint noise from the

existing Blackmans Bay STP, general ‘bush’ related noises, wave action from the estuary and

typical suburban noises; overall the area is classed as acoustically ‘quiet’’ (Vipac, 2016).

As part of the 2014 investigation Vipac measured community noise levels (background noise) at

three residential locations considered typical of houses surrounding the STP. These residential

properties correspond with houses 1, 3 and 5 in the images below. The analysis found relatively

low levels of noise at each of these locations. At house 1 (the existing house within the Site and

proposed for demolition post construction) the dominant noise was waves from the foreshore

with the existing STP also audible from this property. At house 5 (to the west of the STP) the

existing STP was found to be inaudible and bush noises were the main noises registered. At

house 3 (to the north of the STP on Suncoast Drive) wave noise and intermittent traffic noise

from Suncoast Drive were clear with a ‘tone’ also audible from the existing STP (presumed to be

associated with the existing fan).

In general, this represents a fairly quiet ambient noise environment with waves, bush sounds

and traffic noise most common and the existing STP audible from some locations.

As part of the first assessment Vipac also characterised noise sources from the existing STP.

Noise from the existing STP was taken into account when measuring background “community”

noise, which was subsequently used to inform the site specific criteria.

Further details on the existing noise conditions and existing STP are available in the full report

(Appendix F).


The key legislation, policy and guidelines of relevance to noise management in Tasmania are

the:

ANZECC Technical basis for guidelines to minimise annoyance due to blasting

overpressure and ground vibration 1990 (ANZEC 1990);

Environmental Management and Pollution Control Act 1994;

Environmental Management and Pollution Control (Miscellaneous Noise) Regulations 2014

(EMPCR);

Environment Protection Policy (Noise) 2009;

Tasmanian EPA Noise Measurement Procedures Manual (NMPM), dated July 2008; and

Kingborough Council Draft Interim Planning Scheme 2014

The Environment Protection Policy (Noise) 2009 sets out a strategic framework for noise

management in Tasmania focusing on protection of human health, both within the community

and for individual’s health and wellbeing. In addition to protecting community and individuals

(including site workers) from noise impacts, the project also aims to minimise noise impacts to


wildlife. The policy provides guideline levels that, if met, would be expected to protect the

majority of the population.

The Kingborough Council Draft Interim Planning Scheme 2014 also includes acceptable noise

criteria in its Use Standards, which have been included in the establishment of noise criteria.


The project has the potential to impact local residents through the generation of noise during

both the construction and operational phases. The potential for impacts to wildlife from noise are

very limited as no blasting is proposed, construction work will be restricted to daylight hours and

the existing STP already operates 24 hrs a day, therefore local animals are already accustomed

to this noise. As such impacts to fauna have not been considered further.

Noise Criteria

As noted above, in order to assess the potential noise impacts as a result of the Project

TasWater commissioned Vipac to undertake an acoustic assessment of the area in two parts

during 2014 and then 2016. As outlined in Section 6.4.1 the existing noise environment was first

established, with site based measurements at three local properties. These background

measurements were used to determine site specific noise criteria against which the modelled

impacts were assessed. The sites assessed for background noise in 2014 were originally

labelled A, B and C but correspond to locations 5, 1 and 3 respectively in the final modelling

effort (refer figures below). It is noted that house 1 (B in original assessment) is within the Site

and has since been determined by TasWater to be part of the overall land acquisition from

Council and is to be demolished post construction. It is still useful in understanding background

conditions, but is not relevant in assessment of future impacts.

During the operational phase noise criteria were set with reference to the Kingborough Interim

Planning Scheme 2015 and the Victoria Regional Noise lowest base level. The Tasmanian EPP

and NSW Industrial Noise Policy were also considered (refer Appendix F) but were in excess of

the adopted guidelines and therefore the more conservative limit was applied. The Kingborough

Interim Planning Scheme 2015 makes reference to adopting the L90 measured background

level plus 5 dBA (or 40 dBA whichever is lower). This was initially applied to all measured

background sites but those with results lower than the Victoria Lowest Base Level (namely

house 5) were revised to adopt the Victorian Lowest Base level as industry recognised

standard. The resulting noise criteria are illustrated in Table 6-3.

Table 6-3 Noise Criteria for Sensitive Receptors During Operations

House Number Sound Pressure Level, dBA

L90 Night Time

(Monitored) L90 + 5

Minimum Criteria

(Victoria) Project Criteria

5 (low density

housing west of the

Site)

23 28 32 32

1 (within the Site) 30 35 32 35

3 (medium density

housing north of the

Site)

32 37 32 37

Source: Vipac 2016


Once the appropriate criteria to be met was established at the measured receptors, it was

applied to the remaining sensitive receptors in Figure 6-8 using the density of housing as a

guide (i.e. all low density housing to the west and south adopted the same criteria as house 5

and all medium density housing to the north adopted the same criteria as house 3). These

criteria were adopted for normal operations only. Different criteria were adopted for the

construction phase and occasional emergency generator use.

For the construction period and periods of emergency power generation (diesel generator),

noise criteria from the Tasmanian Environmental Protection Policy (Noise) 2009 were applied

(see Table 6-4). These more relaxed criteria were used for construction as construction noise

will be intermittent, only during the day, and only for short periods of time (although the overall

construction period is 2 years, only short periods of noise generating activity will occur within

this period). These more relaxed criteria are adopted for emergency diesel generation given the

infrequent and short duration of such activities and that emergency power generation does not

represent any deviation from current site operations.

Table 6-4 Noise Criteria for Construction and Emergency Diesel Generation

Specific

Environment

Critical Health Effects LAeq

dBA

Time base

(hours)

LAmax fast (dB)

Outdoor living

area

Serious annoyance, daytime

and evening 55 16 -

Moderate annoyance,

daytime and evening 50 16 -

Outside

bedrooms

Sleep disturbance, winder

open (outdoor values) 45 8 60

Source: Tasmanian Environmental Protection Policy (Noise) 2009. Only outdoor criteria adopted.

Noise Modelling Methodology

SoundPLAN software was used for carrying out detailed noise emission spectra and contour

modelling. SoundPLAN via the CONCAWE prediction algorithm models atmospheric attenuation

using Pasquill stability indices in combination with vector wind speed and direction to determine

appropriate frequency dependent attenuation/amplification. Neutral wind weather conditions

were modelled. Other weather conditions were not considered due to the proximity of closest

sensitive receptor locations negating any significant influence from atmospheric conditions.

Sound power levels and sound power level spectra were established using the proposed design

as inputs. The main noise sources included in the model are shown in Figure 6-7. Assumptions

were made in relation to noise control measures on the proposed infrastructure (refer below)

and these form commitments in the detailed design phase in order to achieve the level noise

outputs as modelled.

Two model scenarios were considered, namely normal operations and operations with

emergency power generation. The second run was done to simulate the operation of generator

as well as the STP in power outage scenario

A total of eight houses (sensitive receptors) were included in the model as outlined in the figure

below. As noted previously house number 1 is now to be acquired by TasWater, used as a site

office during construction then demolished so is not considered further in this DPEMP (but is

included in the attached noise reports).


Figure 6-7 Noise Sources from Upgraded STP (Source, Vipac 2016)

Figure 6-8 Residential Locations used for Baseline Noise Assessment

(Source, Vipac 2016)


Noise Modelling Results

Following development of all applicable criteria, the noise modelling was then undertaken using

software and data sources outlined in Appendix F.

The resulting modelled noise contours are presented in Figure 6-9 for normal operations and

Figure 6-10 for normal operations with a generator.

The results from the figures for each of the sensitive receptors are summarised in Table 6-5. As

the plant will operate 24 hours a day modelled south pressure levels are provided for all periods

and not delineated into day and night time.

Table 6-5 Modelled Sound Pressure Levels during Operation

Sensitive

Receptor ID5

Low Level Noise

Emission Criteria (dBA)

Source - Kingborough

Scheme and Victoria

Lowest Base Level

Tasmanian EPP

noise criteria for

outdoor areas and

outside bedrooms

(LAeq dBA)

Model Scenario Results (predicted

sound pressure levels in dBA)

Operations Operations

with generator

Site 2 37 45 to 55 30 43

Site 3 37 45 to 55 33 38

Site 4 32 45 to 55 24 44

Site 5 32 45 to 55 21 35

Site 6 32 45 to 55 16 33

Site 7 32 45 to 55 23 27

Site 8 32 45 to 55 30 34

The results from Table 6-5 show that during normal operations, the relevant noise criteria were

not exceeded at any of the sensitive receptors, with the highest noise levels apparent at Site 3.

Under normal operations the Low Level Noise Criteria apply and are not exceeded at any site

during normal operations.

Under emergency power generation the Tasmanian EPP criteria apply and are not exceeded at

any site during normal operations. Note that although higher criteria have been adopted for

periods of emergency power generation, these are highly infrequent events of short duration

and do not represent any deviation from current operations (which already use emergency

generation in power outages).

It is noted that sound pressure levels at receivers 7 and 8 have the potential to be 1 to 2 dBA

higher under worst case weather conditions. Even with this deviation, they remain within the

adopted criteria.

The stages of construction with highest potential for noise generation were assessed by Vipac,

namely excavation, trenching, concrete works, compaction and tank cleaning. Sound power

data were assessed for each of these stages predicted sound pressure levels generated. For

the construction period, the predicted sounds pressure levels from the three main stages of

construction are presented in Table 6-6. As can be seen in the table, the highest sound

pressure levels are modelled to occur during the major trenching and concrete works.

5 Note that although site 1 has been removed from this s ummary, it is included in the original report and also complies with the adopted criteria.


Predicted levels show that there will be some degree of disturbance, but this will be intermittent

and depend on the stage of construction. The modelled construction phase sound pressure

levels are within the adopted criteria (Tasmanian EPP).

The main mitigating factors for construction noise will be limiting operations of construction

equipment to normal daytime hours, so as to not impact on night time periods. Working hours

for construction involving heavy machinery (as modelled) will be restricted to 7 am to 6 pm

Monday to Saturday.

Table 6-6 Modelled Sound Pressure Levels during Construction

Sensitive

Receptor ID

Tasmanian EPP

noise criteria for

outdoor areas

and outside

bedrooms

(LAeq dBA)

Model Scenario Results (predicted sound pressure levels in dBA)

-30t excavator

and trucks for

earthworks for

IDEA-SBRs

-20t Excavator for trenching

-Concrete trucks and

concrete vibrators

-Compaction equipment and

grade for backfill and road

construction

-Cleaning tanks and

modifications to

existing infrastructure

-20t excavator for

trenching pipelines

Small concrete works

Site 2 45 to 55 37 43 39

Site 3 45 to 55 38 45 41

Site 4 45 to 55 38 42 28

Site 5 45 to 55 27 38 27

Site 6 45 to 55 20 31 22

Site 7 45 to 55 20 34 31

Site 8 45 to 55 33 38 36

Design Commitments

As noted above, the noise modelling work made assumptions about a number of noise

generating elements in order to develop the predictions provided. During the detailed design

phase these assumptions will be reviewed with respect to design elements in order to achieve

the level of sound reduction built into the model. In particular:

The SWL (sound power level) for the inlet works will be 85 or less. A reduction of 3 to 6

dBA may be required on the inlet works to achieve this. If needed this will be achieved by

enclosing the works on the north and east sides with a material with an appropriate sound

transmission loss and lining the internal sides with adsorption.

An enclosure of the odour control fan will be applied that will provide performance of 80

dBA sound pressure level at 1 m or less.

The new odour control fan inlet duct is likely to require a silencer providing 10 dBA insertion

loss with performance across the frequency range 250 Hz to 4 kHz 1/1 octave bands to

achieve a sound power level of 89 or less.

The exhaust of the odour control fan will have a discharge silencer fitted with an insertion

loss performance as stipulated in Table 9 of Vipac 2016 to achieve a sound power level of

84 dBA or less.


Care will be taken in the development and selection of enclosures for the IDEA blowers

such that tonal noise emission breakout does not generate potentially intrusive noise

emissions.


Along with proactive community consultation leading up to, and during, construction, t he

TasWater online complaints register will be the main vehicle for the monitoring of problematic

noise emissions. If complaints regarding noise are received, the source of the issue will be

isolated and assessed for further management and mitigation.

Commitment 10 Noise complaints will be tracked using the online

complaints register. All complaints will be logged, actioned and all

outcomes documented.

Commitment 11 Detailed design will address the required noise limits on

equipment and acoustic enclosures as stipulated in this DPEMP

and the Vipac Noise Report (2016) namely 85 dBA or less for the

inlet works, 80 dBA (at 1 m) or less for the odour control fan,

89 dBA or less for the odour control fan inlet duct and 84 dBA or

less for the exhaust from the odour control fan.

Commitment 12 Care will be taken in the development and selection of

enclosures for the IDEA blowers such that tonal noise emission

breakout doesn’t generate potentially intrusive noise emissions.


Figure 6-9 Predicted Noise Emission Contours for Normal Operations in Neutral Weather (Source: Vipac, 2016)


Figure 6-10 Predicted Noise Emission Contours for Normal Operations with Temporary Power Generation in Neutral Weather

(Source: Vipac, 2016)


6.5 Waste Management

This section outlines the solid waste streams from the upgraded STP during construction and

operation.

The primary liquid waste stream from the site is the treated effluent itself which is discharged via

the existing outfall to the marine environment. As this outfall impacts the marine environment it

is addressed under Marine and Coastal in Section 6.8.


The key legislation, policy and guidelines of relevance to the management of solid and

controlled wastes in Tasmania are:

Environmental Management and Pollution Control Act 1994

Environmental Management and Pollution Control (Waste Management) Regulations 2010

Environmental Management and Pollution Control (Controlled Waste Track ing) Regulations

2010.

National Waste Policy 2009 (NWP)

Used Packaging Materials NEPM

The objectives of the Resource Management and Planning System as set out in Schedule

1 of the Land Use Planning and Approvals Act 1993 (LUPAA)

Specifically, for Biosolid management:

Biosolids Reuse Guidelines August 1999

Approved Management Method for Biosolids Reuse - June 2006

Sewage Sludge Management Plan Guidelines, September 2014

The key performance requirements, as related to the legislation outlined above are:

Approval must be sought prior to controlled wastes being transported from the site;

Controlled wastes must be removed from the site by an approved controlled waste

transporter; and

Controlled wastes must be disposed of at an approved disposal facility.

6.5.2 Project Sources

Construction

During construction, excess fill material will be generated from the cut and fill process to install

the new treatment infrastructure. The vast majority of earthworks for the development is on land

outside of the existing STP site and up gradient from it. There is however a small area of cut on

the western boundary of the existing STP site and other construction works (including new

unloading/loading facility) within the existing STP site. As STPs are potentially contaminating

activities consideration needs to be given for any excavated material from the site to be

contaminated. Management of this risk is outlined below.

Other solid waste streams will include excess construction materials and general waste

generated by the contractors.


Operational

The solid and controlled wastes which will be generated during operation include:

Miscellaneous general waste;

Solids from inlet screening and grit removal; and

Sludge from the treatment process in the form of compressed sludge cake (biosolids cake).

Sludge is classified as a controlled waste in accordance with the Environmental

Management and Pollution Control (Waste Management) Regulations 2010 (Regulation 5);

The estimated quantities of solid wastes generated during operation of the Project are identified

in Section 2.6.5 - Waste Streams. The type of solid waste remains the same for the existing

and upgraded STP, but quantities are increased in line with increases in future flows through

the plant.


Excavated Materials

As stated above the vast majority of all excavated material is from areas outside of and up

gradient from the existing STP site. However, a small area along the western side of the existing

STP boundary (up gradient of the existing plant) will be excavated and some ground

disturbance will occur at the new loading/unloading facility. As the existing STP is a “potentially

contaminating activity” risk of contaminated soil being encountered needs to be considered. To

manage this risk a targeted inspection of areas proposed for subsurface excavations will be

undertaken by a Certified Practitioner (Site Contamination Practitioners Australia) prior to

construction. This inspection will review available history for the site and delineate which areas

proposed for excavation would be considered lower risk and therefore not require classification

and which areas are higher risk and therefore need soil testing and classification (for reuse or

disposal). In accordance with this assessment, areas of higher contamination risk (within the

excavation footprint) will be subject to soil testing and classification. Any resulting material from

these areas will be handled, transported and disposed on in accordance with relevant

guidelines and utilising licenced practitioners.

General Waste

During construction a waste collection area will be established within the Construction

Compound. This area will allow for separation of reusable, recyclable and other waste streams.

All potentially wind-blown wastes will be covered. All wastes will be collected and transported

offsite on a regular basis by licensed contractors to licenced facilities.

During operation small quantities of “general waste” generated will be collected in covered skip

bins (separate for general waste and recyclables) around the Project Site and collected on a

fortnightly basis by a licenced waste removal contractor.

Inlet Screenings

Inlet screenings have the potential to create an odour nuisance if left uncollected, and impact on

the general hygiene of the Project Site.

Inlet screenings will be dewatered, compressed in a screw press and disposed of to a covered

hopper bin that will be removed weekly from site by a licenced waste contractor.


Grit Removal

There are no significant potential effects from collected grit to the environment. Dewatered grit

will be disposed of to a covered hopper bin that will be removed weekly from site by a licenced

waste contractor.

Sludge/Biosolids

During operation, the Project will continuously be generating biosolid waste as a by -product of

the treatment process. The biosolids from the treatment process will be discharged to self-

loading bins via fully enclosed conveyors. Biosolids will be treated to a Class 2 Biosolids

Classification as defined in the Tasmanian Biosolids Reuse Guidelines, 1999, suitable for reuse

in agriculture, forestry or land rehabilitation (as per current arrangements). Subject to testing

(refer below) this waste will be collected on a daily basis (by a licenced operator) and

transported offsite to existing agricultural reuse sites.

Detailed information about biosolids monitoring, handling and management will be incorporated

into a Sewage Sludge Management Plan (SSMP) for the Project, based on the requirements of

the Tasmanian EPA’s Sewage Sludge Management Plan Guidelines, September 2014.

The SSMP for the Project will include, but not be limited to, the following details:

An overview of sludge treatment and handling at the STP, including transportation details.

Setting of satisfactory controls to ensure sludge contaminant quality will be consistently

maintained;

Identify arrangements and alternative pathways for any sludge that does not meet the

criteria for reuse (including transport to a licenced landfill facility if required) and

Define a sludge monitoring program that fully complies with the requirements of the

Biosolids Reuse Guidelines August 1999.


Management of the solid waste streams generated by the Project will be monitored on a

continual basis during operation. Regular internal audits of the waste management system will

also be undertaken by TasWater to identify any efficiencies that may be gained by alt erations to

solids waste producing processes.

The SSMP developed for the Project will be reviewed regularly throughout the commissioning

phase of the Project.

Commitment 13 A targeted inspection of areas proposed for subsurface

excavations will be undertaken by a Certified Practitioner (Site

Contamination Practitioners Australia) prior to construction to

identify any areas of high risk for land contamination for

subsequent soil testing, classification and management.

Commitment 14 A Sewage Sludge Management Plan (SSMP) will be

developed for the Project.


6.6 Dangerous Goods and Environmentally Hazardous Materials


The project must fulfil the requirements of the following legislat ion and policy in relation to

dangerous goods and environmentally hazardous materials:

Australian Code for the Transport of Dangerous Goods by Road and Rail;

Dangerous Substances (Safe Handling) Act 2005 and associated regulations;

Australian Dangerous Goods Code (7th edition); and

Relevant Australian Standards (e.g. AS 1940 and AS 3780).

6.6.2 Project Sources

Construction

Environmentally hazardous materials used during the Project’s construction will include varying

quantities of:

Fuels, oils and lubricants

Paints and solvents (several hundred litres)

Cement and bitumen materials; and

Small quantities of disinfectants and cleaning chemicals.

These materials will be housed in a roofed and bunded facility within the construction compound

(refer Figure 2-1).

Operation

The operational side of the Project will involve the use or production of a number of hazardous

materials.

As outlined in Section 2.6.6 the existing gaseous chlorine system will be decommissioned and

the following chemicals and hazardous substances will be stored in site during operation. Note

that many of these substances are already held on site as part of the existing STP.

Small quantities of lubricating oils for various mechanical components.

Small quantities of diesel (max 250L) associated with the emergency generator. Diesel is

classified as a Class 3 Dangerous Good under the Australian Dangerous Goods Code.

Small quantities of cleaning chemicals and descalents.

Polyelectrolyte (flocculent) in either liquid or powder form. Liquid polyelectrolyte will be

delivered in intermediate bulk containers (IBCs) and powered form polyelectrolyte will be

delivered in pallets of 20 kg bags.

Carbon substrate (liquid sugar solution) stored in a tank approximately 5,000L in size.

Nutrients for the Bio-trickling Filter – The specific nutrient solution is yet to be identified but

small quantities will need to be stored on site.

The liquid sugar solution will be stored within the bulk chemicals store marked on Figure 2-2,

immediately south of the inlet works. This chemical store will be secured, signed, roofed and

bunded in accordance with statutory requirements.


The other chemicals and fuels will be stored in very small volumes within a designed bunded

storage area in the Dewatering Building (Figure 2-2) including restricted access and appropriate

signage.

In addition to the substances outlined above two additional chemicals may need to be stored on

site in the future if phosphorus removal is required as a retrofitted element to the STP. In that

event Magnesium hydroxide liquid (up to 30,000L tank) and Aluminium sulphate (up to 30,000L

tank) could be stored on site in the future. These chemicals are both defined as Hazardous

Substances under the Safe Work Australia classification but are not considered Dangerous

Goods under the Australian Dangerous Goods Code. If required these chemicals would be

stored in the roofed and bunded bulk chemical storage facility south of the inlet works.

The Project will also produce environmentally hazardous waste streams including:

Waste sludge from the digestion process;

Inlet screenings; and

Influent could also be considered an environmentally hazardous waste stream in the event

it was to leak/spill at some stage during the treatment process.


Ineffective management, including storage, transport, handling and use of dangerous goods

and environmentally hazardous material could lead to significant impacts to environmental

receptors within both the terrestrial and aquatic environments.

General dangerous goods and environmentally hazardous materials

Spills of chemicals and fuels have the potential to occur during construction, which may lead to

environmental impacts to both terrestrial and aquatic environments and may lead to personnel

safety issues on site. The same risks and potential impacts as the construction phase for spills

of chemicals or fuels also apply during operation.

Risks from production of waste sludge and inlet screenings are considered low, as these will be

produced in a controlled environment and removed offsite, as explained in Section 6.5.

General dangerous goods and environmentally hazardous material management and mitigation

for the Project will include the following:

Employees and contractor inductions will include information on dangerous goods and

environmentally hazardous materials, their handling, management and any mitigation

measures that may be applicable in the event of a spill incident, in accordance with the

Australian Standards;

Dangerous goods and environmentally hazardous materials storage, handling and clean up

procedures will be incorporated into the site CEMP for the construction phase and the

Operational EMP (OEMP) during the operational phase.

Fuels, oils, and cleaning chemicals will be stored in dedicated bunded areas with suitable

ventilation, roofs, restricted access and signage.

During the construction phase, storage of dangerous goods will either occur at a designed

location within the Construction Compound or within the existing storage locations at the

current STP site.

During operation, these materials will be stored in permanent onsite storage areas; small

quantities will be in the De-Watering Building and any large quantities (sugar solution) will

be in the designated bulk chemical storage shed near the inlet works (Figure 2 2).


Fuel for construction machinery and vehicles will be delivered to fully bunded temporary

fuel storage tanks, with refuelling of machinery occurring within the same bunded area.

Larger volumes of cement and bitumen for road works during construction will be delivered

in suitable trucks as required and will not be stored onsite.

Chemical/fuel clean-up kits will be maintained onsite at several locations during

construction and operation.

If ground spills of dangerous goods/environmentally hazardous materials occur, clean-up

will include collection of all material and affected soil in suitable containers (e.g. skip bins,

44 gallon containers, depending on volumes). Contained soils will then be disposed of at

suitable landfill sites by licenced contractors.

All spills will be reported to the site manager immediately and clean up procedures

commenced. Once cleaned, all spills will be recorded along with information on any follow

up actions or procedure modifications to avoid subsequent spills.

All significant spills of dangerous goods/environmentally hazardous materials (including

those to waterways and/or involving >100 litres) will be reported to the EPA within 24 hours.

Handling of chemicals and their subsequent storage to be kept away from drainage lines.

With these mitigation measures in place the residual risks from the presence of general

dangerous goods and environmentally hazardous materials onsite is considered to be low.

Uncontrolled Wastewater Releases

Release of untreated wastewater onsite from leaks/spills presents potential impacts to human

health, air quality (odour), and environmental receptors in the direct area. This includes

receptors exposed in drainage lines/waterways, as covered in Section 6.2 (Surface Water) and

Section 6.8 (Marine and Coastal).

The largest risk to the environment from environmentally hazardous material discharge from the

Project is considered to be the uncontrolled release of poorly treated effluent to the marine

environment through the effluent discharge pipeline. The likelihood of this occurring is

considered highest during extreme storm events where the system cannot sufficiently handle

the high influent loads received (i.e. >7x ADWF) or as a result of malfunctioning components of

the treatment system (particularly the disinfection system). This could also occur as a result of

power or equipment failure.

Impacts of the release of poorly treated effluent to the aquatic environment has the potential to

impact flora and fauna through direct acute/chronic toxicity (e.g. through nitrogenous

compounds) and through secondary impacts resulting from high loads of suspended particulate

matter and localised reduction in dissolved oxygen. There are also the impacts to recreational

users of the marine area from potential algal blooms (resulting from eutrophication of the marine

environment) and harmful pathogens.

As well as releases to the marine environment there is also the risk of leaks from treatment

infrastructure to the terrestrial environment and subsequently to adjacent drainage lines and

recreational areas.

To manage and mitigate the types of potential scenarios mentioned above, TasWater have

developed a Sewage Treatment Plant Contingency Management Manual (CMM) for existing

sites which references Site Response Procedures for various emergency scenarios. The CMM

and associated procedures will also be applicable to the Project.

The CMM and applicable Site Response Procedures are presented in Appendix C and include

the following:


Excessive Wet Weather

Flood

Spill to Water

Spill to Land

Power Failure

Loss of Disinfection

Fire

Odour

In addition to the CMM, there will be additional Project design features to prevent or minimise

the release of environmentally hazardous wastewater, including:

As outlined in Section 2.5.9 the Blackmans Bay STP is not gravity fed so any power failure

in the area will be managed at pump stations rather than the STP. Localised power failure

at the site only (i.e. not affecting pump stations) will be managed in the short term through

residual storage within the plant itself while a generator is sourced to maintain essential

operations. At this stage it has not been confirmed whether a permanent generator will be

installed on site or a mobile generator kept on standby.

The site and all infrastructure will be subject to a routine maintenance program and in built

to limit potential for equipment failure. In the event of equipment failure there is redundancy

built into the design to provide for back up processing (e.g. multiple process units in most

cases) until any issues can be repaired.

Malfunction sensors have been included in the Project design to detect malfunctioning

treatment infrastructure.

Isolation valves and bypasses have been incorporated in the Project design to allow leaking

infrastructure to be isolated.

With the inbuilt design features, the overall nature of the selected plant and the contingency

measures outlined in the TasWater CMM the residual risk of unplanned discharge of untreated

(or insufficiently treated) effluent is low.

In addition, the risk of such failure is considerably less under the proposed STP upgrade than

the existing plant which is ageing and reaching capacity.


Storage and use of dangerous goods or environmentally hazardous materials, presence of spill

kits and employee awareness will be audited on a monthly basis by operational staff to assess

the suitability of management and mitigation measures in use. Audit and inspection outcomes

that require actioning will be provided to site management for further investigation.

Improvements to storage or use of these materials will be noted in annual environmental reports

to the EPA.

Dangerous goods spills >100 L will be recorded and reported to the EPA, with improvement to

mitigate further spills included in correspondence.

In the case of a large marine discharge event of poorly treated effluent, the following will be

undertaken by TasWater:

Relevant Site Response Procedure to be invoked.

The EPA will be notified.


The cause of the uncontrolled or under-treated discharge will be investigated and

thoroughly reviewed by TasWater to determine whether the incident was avoidable or a

rare circumstantial event (e.g. an unusually large storm).

The results of the investigation will be used to determine if additional mitigation or

management could be incorporated into the Project to either avoid the event reoccurring or

reducing the potential for impact.

Water quality monitoring will be undertaken at incremental distances from the outfall, wi th

sites, number of samples, and monitoring period to be determined based on consultation

with the EPA. The commencement of monitoring will occur as soon as practicable with

regards to mobilisation availability of marine subcontractors and weather conditions.

Commitment 15 All hazardous materials will be stored in suitably

bunded areas in accordance with the relevant guidelines.

Commitment 16 Any spilt waste will be immediately reported to the site

manager and clean-up will occur.

Commitment 17 Inspections and audits of environmentally hazardous

material use and storage will be undertaken monthly.

Commitment 18 Dangerous goods and environmentally hazardous

materials storage, handling and clean up procedures will be

incorporated into the site CEMP for the construction phase and the

Operations and Maintenance Manual during the operational phase.


6.7 Biodiversity and Natural Values

This section considers terrestrial ecological values. Marine values are outlined and assessed

separately in Section 6.8. Surface water impacts are described separately under Section 6.2.


The existing STP site and surrounding land were surveyed for ecological values in

October/November 2014 by TasFlora and again in July 2016 by GHD. TasFlora undertook a

vegetation survey and fauna habitat assessment of three discrete areas of potential disturbance

on 14 October 2014 and 6 November 2014. Subsequent to this, the proposed design and

boundaries of disturbance were altered, and an additional ecological survey was undertaken by

GHD on 7 July 2016 to encompass the expanded Project area.

The entire area detailed in Figure 6-11 as the Project Site was surveyed on foot by a GHD

senior ecologist on 7 July 2016. The total area surveyed was approximately 10.2 hectares. The

results of the TasFlora ecological investigation (2014) are provided in full in Appendix B. The

results of the GHD survey are reported below.

The following summarises the salient information from the detailed ecological studies and

addresses all disturbance areas of the Project Footprint.

Vegetation Communities

The study site is comprised of cleared urban areas and agricultural land, with remnant patches

of native vegetation, and planted eucalypts. Three native vegetation communities (one listed as

threatened) and two agricultural, urban or exotic communities were identified and mapped within

the study area by GHD.

Eucalyptus globulus dry forest and woodland (DGL) - Threatened (2.45 ha)

Eucalyptus amygdalina forest and woodland on dolerite (DAD) (0.72 ha)

Allocasuarina verticillata forest (NAV) (0.52 ha)

Agricultural land (FAG) (4.8 ha)

Urban areas (FUR) (1.71 ha)

Eucalyptus globulus dry forest and woodland (DGL) is listed as threatened under the

Nature Conservation Act 2002. It is also listed as a high priority native vegetation

community under the Kingborough Interim Planning Scheme 2015. This community occurs

around the perimeter of the study area and covers approximately 2.45 hectares. Some

areas of this community, in particular along the southern Project Site boundary, are in

reasonable condition, however, the majority of the community is in poor condition with

several declared weed species such as Rubus fruticosus agg. (blackberry) and

Chrysanthemoides monilifera ssp. monilifera (boneseed), along with many introduced grass

species present. A significant number of the E. globulus trees along the western boundary

of the Project Site appear to have been planted rather than naturally seeded.

Eucalyptus amygdalina forest and woodland on dolerite (DAD) occurs near the

western boundary of the study area and is a transitional community into the area mapped

as Agricultural Land (FAG). The DAD is a highly modified version of what would be

considered a typical example. There were occasional E. amygdalina trees with E. ovata

occurring in the less well drained areas. The understorey is very sparse with a ground layer

of introduced grass species that appear to be regularly mown.

Allocasuarina verticillata forest (NAV) - This community occurs near the coastal fringe of

the study area and occupies approximately 0.52 hectares. It is a typical example of the


community type with Allocasuarina verticillata as the dominant canopy species with the

occasional emergent Eucalyptus globulus tree with a sparse understory of native grasses.

The remainder of the Project Site is a mosaic of agricultural and developed land.

Figure 6-11 shows the location of vegetation communities within the Project Site. On this figure

the mapped trees are those of Eucalyptus globulus and Eucalyptus ovata but the figure does

not show point locations for all trees and shrubs occurring on site. E.globulus and E.ovata were

specifically targeted for individual mapping due to their habitat value for the listed swift parrot

(refer below).

Threatened Flora

According to the Natural Values Atlas (DPIPWE 2016) one threatened flora species has

previously been recorded within 500 m of the study area, Austrostipa bigeniculata

(doublejointed speargrass), which is listed as rare under the TSPA. An additional 19 species

have previously been recorded within 5 km of the site.

No threatened flora species were observed during either of the field survey events (TasFlora

2014, GHD 2016).

The GHD survey was conducted in winter which is considered a sub-optimal time of the year for

survey of flowering plants, in particular it is not a suitable time to survey annual grasses.

However, when considering the condition of the potential habitat available, it is considered

unlikely that threatened species have been over looked. In addition, the TasFlora survey was

conducted in October and November which is a suitable time of year for many seasonal

flowering species and did not find any threatened species either.

Threatened Fauna

No threatened fauna listed under the TSPA or EPBC Act were recorded on site during either the

2014 (TasFlora) or 2016 (GHD) site surveys. No targeted fauna surveys have been undertaken

at the site.

A small number of threatened fauna identified by desktop review (refer to the Natural Values

Atlas report in Appendix B) may occur on site. The key species identified during desktop

research as ‘possibly’ occurring but not detected on site, are summarised as follows (a full list of

species potentially occurring on site and an assessment of likelihood is provided in Appendix B

(TasFlora 2014):

Swift Parrot (Lathamus discolor)

The general area has a high number of Eucalyptus globulus trees along with scattered

individuals of E. ovata which may provide foraging and possibly nesting options for the swift

parrot (Lathamus discolor). Four eucalypts (three E. globulus and one E. ovata) had

observed hollows which may provide nesting habitat for the species. The locations of these

are detailed in Figure 6-11. There are known nesting and foraging locations within 5 km of

the study site, however, there are no recorded observations of the species within the study

area. A number of E. globulus trees had a DBH of greater than 70 cm which in the future

are likely to provide more hollows that may be utilised for nesting.

Eastern Barred Bandicoot (Perameles gunnii)

The Project Site includes potential foraging habitat for this species, occurring amongst the

eucalypt and agricultural areas mapped. Diggings were observed during the field

assessment that are likely to have been made by a bandicoot species however it is quite

possible that at least some if not all of these bandicoot signs were made by the non-

threatened southern brown bandicoot (Isoodon obesulus).


Although the potential for this species remains, there was no confirmed evidence observed

and the Project Site contains limited and lower quality habitat than that available in the

vegetated areas directly adjacent to the site.

Eastern Quoll (Dasyurus viverrinus) - TSPA not listed, EPBC Endangered

The Eastern quoll is now listed as endangered on the EPBC Act but is not listed on the

TSPA.

No Eastern quolls were detected during the site assessments; however, the Project Site

does provide some potential foraging habitat. The Site is unlikely to provide key

denning/nesting habitat, and the potential habitat available is considered low quality in

comparison to the habitat available in the directly adjacent land to the south of the Project

Site.

General Fauna Habitat Values

The study area provides some habitat for fauna species such as birds, bandicoots, wallabies,

and possibly fauna utilising burrows/dens. However, due to the highly modified nature of the site

and its proximity to densely populated residential areas it is not considered prime habitat. In

addition, there are large areas of alternative habitat adjacent to the study area that are of much

higher quality.

An animal burrow was recorded close to the creek near the southern boundary (refer Figure

6-11). Without undertaking a targeted survey (such as a camera survey) it cannot be confirmed

if the burrow is in use or the species that may be utilising the burrow. There were no scats or fur

evident that may provide more conclusive confirmation. Given the proximity of the burrow to

residential development and the existing STP, and a lack of suitable surrounding foraging and

sheltering habitat, it is considered unlikely it would be utilised by threatened species such as the

Tasmanian devil (Sarcophilus harrisii). The burrow is outside of the Project Footprint.

The Project Site contains limited freshwater habitat, although a drainage line is present in the

north-eastern region of the study area, and a minor creek is located at the southern boundary of

the site. These water courses are discussed in further detail in Section 6.2, Surface Water

Quality. These features are unlikely to provide habitat for threatened freshwater fauna species

due to their limited size and ephemeral nature.

Weeds and Pathogens

Six of the plant species recorded within the study area are listed as declared weeds under the

Tasmanian Weed Management Act 1999. These species are:

Ulex europaeus (gorse)

Rubus fruticosus aggregate (blackberry)

Genista monspessulana (montpellier broom)

Chrysanthemoides monilifera subsp. monilifera (boneseed)

Erica lusitanica (spanish heath)

Foeniculum vulgare (fennel)

The above species were recorded as scattered individuals or small patches, generally

distributed in the vicinity of already disturbed areas, associated with the existing STP site.

No evidence of the pathogen Phytophthora cinnamomi was observed within the Project Site

area nor is the site particularly susceptible.


Geoconservation Sites

There is one geoconservation site mapped along the eastern boundary of the Site (Figure 5-3).

This site is the Blackmans Bay Dolerite Contact and is related to coastal exposure of dolerite

along the foreshore. The geoconservation site lies outside of the proposed Project Footprint and

is not expected to be impacted by the Project.

The Kingborough Planning Scheme also mentions two geoheritage features (refer Section

6.10), namely the Blackmans Bay Geoheritage Site and Blackmans Bay Geological Monument.

The address given for these features is Fossil Drive and they are presumed to be part of the

Fossil Cove Conservation Area, approximately 500 m south of the Project Site. No impacts will

occur to these features.

Reserves

There are no reserves within the Project Site.

There are two informal reserves immediately adjacent to (but outside of) the Site on the coast,

one to the north and another to the south (Figure 5-3). There is also a formal reserve, the Fossil

Bay Conservation Area, approximately 500 m south of the Project Site.


The key legislation relevant to protecting flora and ecological communities of relevance to this

project are:

Environment Protection & Biodiversity Conservation Act 1999 (EPBC Act)

Tasmanian Threatened Species Protection Act 1995 (TSPA);

Forest Practices Act 1985 and associated regulations;

Weed Management Act 1999; and

Nature Conservation Act 2002.

In addition to the above legislation assessment of the project also considers the National

Strategy for the Conservation of Australia’s Biological Diversity, the draft Tasmania’s Nature

Conservation Strategy and the Threatened Species Strategy for Tasmania.

Key performance requirements include:

Avoid and/or mitigate against potential impacts to native flora and ecological communities,

particularly species and communities listed under above legislation;

Where possible avoid impacts to significant and listed native fauna and their habitats;

Where avoidance is not possible, establish mitigation measures to ameliorate impacts and

obtain necessary approvals for impacts to protected species; and

Minimise, control and eradicate any declared weed incursions arising from the Project.

6.7.3 Potential Effects

Vegetation Communities

The main impacts on flora and vegetation communities are through vegetation clearing

associated with construction of the new infrastructure.

The anticipated direct impact to vegetation communities is documented in Table 6-7, which

shows the approximate area of impact for each of the vegetation communities found on site.


Table 6-7 Vegetation Communities Impacted by the Development

Vegetation Community Total Present within

Study Area (ha)

Total Impacted by

Proposed Works (ha)

DGL 2.45 0.03

DAD 0.72 0.00

NAV 0.52 0.00

FAG 4.8 1.45

FUR 1.71 1.46

Total all Communities Impacted 2.94 ha

Of the total areas impacted, the majority will be agricultural land (1.45 ha) and urban areas (1.46

ha) rather than native vegetation.

A very small proportion of the threatened native vegetation community Eucalyptus globulus dry

forest and woodland (DGL) present on site will be impacted by the proposed works

(approximately 1.2%), with the majority protected through careful siting of infrastructure and

laydown areas.

The other native vegetation communities on site (DAD and NAV) will not be impacted by the

proposed works.

The overall impact on vegetation communities is not expected to affect the viability of these

communities in the region.

There is no proposal to clear vegetation within 10m of any waterways or along the coastal area

east of the existing STP.

Threatened Flora

No threatened flora was detected during the site surveys (which were generally conducted at

suitable times of year) and therefore there are no impacts to threatened flora anticipated.

Weeds and Pathogens

The proposal has the potential to spread existing weeds within or outside of the site as well as

introducing new weeds or pathogens as a result of construction or operational vehicular and

materials movement. These risks are to be managed in accordance with the Weed and Hygiene

Management Plan as outlined below.

Threatened Fauna

As identified in Section 6.7.1, the site provides possible habitat for a small number of fauna

species listed under the EPBC Act and TSPA as well as providing potential habitat for a range

of non-listed native fauna.

Vegetation clearance, in particular individual E.globulus trees, has been identified as the

primary potential impact to threatened fauna. The swift parrot (Lathamus discolour), Eastern

barred bandicoot (Perameles gunnii) and Eastern quoll (Dasyurus viverrinus) may all utilise the

site, most likely for foraging. With the exception of a small area of DGL to be removed, the quoll

and bandicoot will not be impacted by a loss of reasonable quality foraging habitat. Impacts to

these species are expected to be negligible.


A total of 252 E. globulus trees were recorded within the study area. Up to 31 of these may be

impacted, of which approximately 21 are juveniles. No hollow bearing trees will be impacted by

the works. A replanting proposal (at a ratio of 3:1) is discussed below in 6.7.4 to mitigate this

impact. With replacement planting in place and the mitigation below implemented, any residual

impact on the swift parrot is not expected to be significant.

There will be a small increase in vehicle activity to the site during the construction period,

however the overall traffic volumes are relatively low and will be during daylight hours therefore

increased risk of fauna roadkill is considered to be limited.

There are no works proposed within 10 m of any waterways.

Geoconservation Sites

There are no impacts anticipated to the identified geoconservation sites as they all fall outside of

the development footprint.

Reserves

There are no impacts anticipated to the Reserves identified north and south of the site as no

development will occur near these reserves and all drainage from the Project Site is directly into

the Derwent Estuary not the reserves to the north and south.

6.7.4 Management and Mitigation

The most significant mitigation for impacts to threatened vegetation communities and native

fauna is restricting the clearance of native vegetation wherever possible. This has already been

applied as part of the design process (aiming to site infrastructure on cleared areas where

practical) and the refinement of ancillary features such as the Construction Compound and site

fencing which have been modified to limit ecological impacts.

The mitigation measures outlined below will contribute to protecting both vegetation and native

fauna, and include keeping impacts to already disturbed land where possible, avoiding ancillary

activities in native vegetation and applying weed controls.

Proposed mitigation measures include:

At the commencement of construction, the Construction Compound and the Project Site

will be fenced as illustrated on Figure 2-1. This will protect against fauna inadvertently

falling into open trenches or accessing hazardous area. It also delineates the area of

impact for the Project, which will be restricted to the construction and operational fenced

areas (with additional exclusion zones applied within this area as per the following point).

The fence line will be microsited to avoid individual eucalyptus trees.

Eucalyptus trees to be impacted (removed) by the works will be clearly marked on site and

all other eucalypt trees will be retained.

Temporary high-visibility fencing will be erected around the DGL forest to be retained, to

avoid impacts to the community.

Temporary high visibility fencing will also be erected around the eucalypt trees to be

retained within the STP fence line (refer Figure 6-11) to protect these from accidental

clearance.

All machinery, equipment and personnel will be kept outside of the fenced area protecting

the DGL community and other eucalypts during construction.

In recognition that a number of eucalypt trees will be removed as part of the works, a

landscaping plan has been developed, which includes replacement planting of E. globulus

and/or E. ovata trees elsewhere on the property (refer Landscaping Plan in Appendix A).


For every mature E. globulus/E.ovata tree removed, 3 new E. globulus/E. ovata seedlings

will be planted.

Maintenance (e.g. water, replacement planting) of all E. globulus and/or E. ovata trees

planted will be undertaken for a minimum of five years.

All ancillary activities during construction (e.g. materials stockpiling, site administration,

parking areas) will be within already disturbed land either within the delineated Construction

Compound or within already cleared areas within the proposed fenced STP site.

Areas that are disturbed temporarily (e.g., for access during construction) will be

rehabilitated (back to their original condition) as soon as practicable.

In the unlikely event that threatened flora species are detected up to or during the time of

construction, all practical efforts will be made to avoid such species and if avoidance is not

possible then a permit to take under the TSPA will be sought prior to any impact.

A weed hygiene plan will be developed (to be incorporated into CEMP) and adhered to

during the construction process to prevent the spread of declared weed seed to other sites,

and to prevent the introduction of new declared weeds and soil based pathogens to the

site. The following broad management principles and hygiene protocols will be included:

– Undertake pre-construction weed control with the aim of eradicating the identified weed

locations within the main STP works area to minimise potential for spread during

works.

– Ongoing weed control during construction (6 monthly inspections and control).

– Prior to and after working on site, all machinery will be cleaned following the general

washdown procedure and machinery checklists detailed in the Tasmanian washdown

guidelines for weed disease and control (Rudman et al 2004) to ensure it is free from

weed seeds or soil bearing pathogens. These checklists include the removal of soil,

mud etc. and the blowing out of any dry plant material. A wheel wash will be provided

at the Construction Compound.

– Bare areas of soil remaining after excavation and topsoil stockpiles will be regularly

monitored for new weed germinants and, when required, control measures adopted in

a timely fashion.


The following vegetation, weed and pathogen monitoring is proposed:

An initial pre construction weed treatment will be undertaken, followed by 6 monthly weed

surveys during construction, and additional weed control applied as required.

A post construction weed, pathogen and revegetation success survey will be undertaken at

the completion of construction, with follow up surveys completed annually thereafter for a

period of 5 years.


Commitment 19 All areas of DGL community outside of the immediate

development footprint will be flagged with temporary high visibility

fencing and protected during construction works.

Commitment 20 All eucalypts outside of the immediate development

footprint will be flagged with temporary high visibility fencing and

protected during construction works.

Commitment 21 Replacement planting will be undertaken for all mature

Eucalypt trees removed at a ratio of 3:1 as part of the Landscaping

Plan

Commitment 22 Weed and hygiene management will be incorporated

into the site CEMP following the principles outlined in this DPEMP.

Commitment 23 Annual monitoring for the first five years of the

landscaped area to assess success of tree growth, weed invasion

and replacement plantings.

Commitment 24 An initial pre construction weed treatment will be

undertaken, followed by 6 monthly weed surveys during

construction, and additional weed control applied as required.

Commitment 25 A post construction weed, pathogen and revegetation

success survey will be undertaken at the completion of

construction, with follow up surveys completed annually thereafter

for a period of five years.

FAG

DGL

FUR

NAV

DAD

DAD

FUR

DGL

FAG

526,600

526,600

526,800

526,800

5,237,

200

5,237,

200

5,237,

400

5,237,

400

5,237,

600

5,237,

600

G:\32\18107\GIS\Maps\MXD\3218107_007_Figure6-1_Ecology_RevC.mxd

0 40 8020




TasWaterBlackmans Bay STP DPEMP

Vegetation & Ecological Values


32-18107

28 Jul 2016Date

Data source: DPIPWE (imagery, cadastre), TasWater (infrastructure design), GHD (vegetation communities, points). Created by: jtoregan


Paper Size A3

LEGENDFauna Habitat Values

Bandicoot diggingsBurrow

WeedsBlackberryBoneseedSweet BriarSpanish Heath

Eucalypt SpeciesE. globulus (impacted)E. globulus (retained)E. globulus (retained - hollow habitat)E.ovata (retained)E.ovata (retained - hollow habitat)Ecology study boundary

Proposed DevelopmentNew fenceExisting fenceThe project siteConstruction CompoundInfrastructure footprintCut / fill footprint

Vegetation Communities (GHD Survey, June 2016)Dry eucalypt forest and woodland

Eucalyptus amygdalina forest and woodland on dolerite (DAD)Eucalyptus globulus dry forest & woodland (DGL)

Non-eucalypt forest and woodlandAllocasuarina verticillata forest (NAV)

Agricultural, urban and exotic vegetationAgricultural land (FAG)Urban Areas (FUR)

Drainage lineWaterwayCadastre

Figure 6-11


6.8 Marine and Coastal

This Section outlines the potential effects of the Project on the marine environment, namely

release of treated effluent via the existing outfall.

As the Project does not involve any physical works on the existing outfall or any part of the site

on the coastal (eastern) side of the existing boundary fence, there are no other coastal impacts

anticipated.


Broader Derwent Estuary Environment

The Derwent Estuary in south-eastern Tasmania stretches from the upper head waters at New

Norfolk some 52 km to the mouth of the estuary at the Iron Pot Light (DEP, 2015). The Project is

located on the western shore towards the mouth of the estuary.

The estuary undergoes considerable physical change from the narrow headwaters at New

Norfolk to the estuary mouth, with the widest point at the mouth extending for approximately 5-6

km. Depths range from 3-6 m in the upper reaches of the estuary, to depths from 10-30 m in the

mid to lower regions; a maximum depth of 44 m is located around the Tasman Bridge, the

location of the Lake Illawarra shipwreck.

The upper to mid reaches of the estuary are generally stratified to some degree with a tidal salt

wedge present with the freshwater inputs from the catchment; this is more pronounced in the

very upper reaches. The lower reach around the mouth of the estuary is well mixed and can

generally be considered a marine environment in the areas concerned with the Project; however

partial seasonal stratification does still occur to some degree.

Water temperatures in the Derwent Estuary generally ranges from 12-22 °C and prevailing

winds are from the south-west / north-west depending on time of day.

Tidal currents are generally low in the estuary, with a typically diurnal tidal cycle with a tidal

range of 0.3 to 1.6 m; tidal currents are generally in the 0.1 - 0.2 m/sec range. Flushing periods

for the estuary average approximately 12 days (DEP, 2015).

During summer months, the marine waters entering the estuary are dominated by flows of

nutrient poor sub-tropical waters from the east coast of Tasmania. During the winter months,

marine flows are dominated by nutrient dense sub-Antarctic waters, significantly altering the

water quality dynamics of the estuary during these periods.

Water quality in the estuary obviously varies by location, but is considered relatively good

overall considering the anthropogenic discharges into the estuary. There are 11 STP outfalls

that discharged approximately 42 ML/day into the estuary during 2013-14 (DEP, 2015), of which

Blackmans Bay contributed around 4 ML/day.

Along with treated effluent there are also considerable waste contributions to the system from

the two major industrial complexes along the river, namely the Nyrstar Zinc smelter to the north

of Tasman Bridge and the Norske Skog pulp mill near New Norfolk. Inputs from the smelter

include heavy metals, particulates, sulphur oxides and to a lesser degree nutrients. Inputs from

the pulp mill include organic matter, particulate matter, hydrocarbons and wood resins (DEP,

2015). Additional pollutants also enter the Derwent system through stormwater run-off and

groundwater pathways. The key pollutants of concern for the estuary are nutrients and heavy

metals.

Overall, the Derwent Estuary is not a particularly diverse ecosystem, with dominantly soft

sediment habitat throughout the estuary, with silty mud in the upper to mid reaches, becoming

sandier in the higher energy areas around the mouth of the estuary. There are also areas of


rocky outcrops towards the mid to lower reaches of the estuary where ecological diversity

increases. Several introduced species dominate the estuary, including the Northern pacific

seastar (Asterias amurensis), New Zealand screwshell and the Pacific Oyster. The Spotted

Handfish is one particularly sensitive endemic species that inhabits the estuary around the mid

to lower reaches, listed as Critically Endangered under the EPBC Act.

Estuary Mouth and Outfall Area

As the major potential impact of the Project to the Marine and Coastal environment is concerned

with the STP effluent discharge, the existing conditions of this section are focused on the

environment at the estuary mouth and surrounding the outfall.

As described previously, the effluent outfall pipeline stretches approximately 600 m offshore in

an easterly direction from the Project site. The 80 m diffuser at the terminus of the pipeline sits

in 13-14 m of water. The diffuser includes 21 ports (alternating to the north and south) with an

80 mm nozzle diameter, spaced at 4 m intervals; the terminal port is directed to the east.

As part of the monitoring program for the effluent pipeline, which was extended in 2010 (see

DPEMP from CEE, 2009a), annual water quality and benthic infauna monitoring has occurred. A

baseline ecological assessment was also undertaken prior to the construction of the pipeline in

late 2009 (CEE, 2009b).

The dominant habitat in the area towards the mouth of the estuary and the Project area is sandy

sediment. Along the shoreline on the western side of the estuary, the substrate changes to a

rocky reef / boulder dominant habitat, an extension of the rocky shoreline. There are also

subtidal patches of isolated reef throughout the mouth of the estuary.

Specifically, around the outfall pipeline area, a subtidal boulder reef extends some 200 m

towards the middle of the estuary from the shoreline, before transitioning to a sand dominant

habitat with patchy areas of boulder reef (CEE, 2009b), and finally to a sandy expanse.

The sandy habitats in the estuary mouth area are not especially biodiverse areas, with the

dominant flora and fauna including a range of sparsely distributed algae (generally turfing or

drift algae) and epifauna, including native and introduced seastars and ascidians. The sandy

habitat along the eastern shore, and to a lesser degree on the western shore of the mouth of

the estuary provides important habitat for the EPBC listed Spotted Handfish (Critically

Endangered), with populations residing in lower energy sandy bays around the lower estuary

(including around Bellerive Bluff, Droughty Point and Halfmoon Bay on the eastern shore and

Nutgrove Beach on the western shore). Flathead, flounder and various skates are common

demersal fish in the sandy habitat areas, with common pelagic species including Australian

Salmon, silver trevally and jack mackerel (DEP, 2015).

The rocky shorelines of the lower Derwent Estuary, including the Project area, support a more

diverse range of flora and fauna, typical of the temperate rocky reef habitat around Tasmania.

This includes a variety of species of algae, including introduced and native species. Brown and

green algae generally dominate the rocky substrata around the outfall pipeline (e.g. Ecklonia

radiata, Lessonia corrugate, Caulerpa sp.) (CEE, 2009b, DEP, 2015), along with foliose red

algae (Plocamium species dominate near the outfall) and encrusting coralline algae

(predominantly Feldmania). Of specific importance to the Project is the presence of giant kelp

(Macrocystis pyrifera) in the vicinity of the outfall (discussed further in more detail below). This

species can grow up to 30 m in height from the substrate as it reaches for the surface and forms

forested canopies. Giant kelp forests were once common throughout the lower reaches of the

estuary, but have become less so, most likely due to climatic and anthropogenic induced

changes in the environment.


A variety of sessile and motile invertebrates inhabit the rocky coastline and subtidal reefs

around the outfall, including various species of encrusting and solitary ascidians and sponges,

anemones, zoanthids, seastars, crabs and molluscs (including the commercially important

blacklip abalone). The area also supports communities of the southern rock lobster,

recreationally fished in the area.

A number of fish species also inhabit the rocky reef areas around the outfall, consistent with

similar habitat throughout southern Tasmania. Common fish species include the Banded

Morwong, Bastard Trumpeter and various species of wrasse.

Potential Sensitive Receptors

There are several Federally or State listed marine species or communities that have the

potential to inhabit, or are known to inhabit the area that may be affected by the effluent outfall.

Spotted Handfish (Brachionichthys hirsutus)

When undertaking projects in the Derwent, the potential presence of the Spotted Handfish

(Brachionichthys hirsutus), listed as endangered under the TSPA and Critically Endangered

under the EPBC Act, must be considered. Spotted handfish populations are found in sheltered

bays around the Derwent Estuary and can occur in a depth range from 2 - 30 m, on

unconsolidated substrate (ranging from shell grit to finer sands), but are more common in the

estuary in shallower water from 5 - 10 m (DEP, 2015). The area that may be affected by the

Project (i.e. from the effluent plume), although containing soft sediments in some areas, is not a

known location for Spotted handfish; with only seven known population areas around the

Derwent Estuary (five on the eastern shore and two on the western shore). The site of the

outfall is likely to be too high in energy for the species, as it is subject to open ocean swells. No

Spotted handfish were found on any of the baseline ecological transects surveyed in 2009 as

part of the pipeline extension DPEMP (CEE, 2009b). The closest population to the Project is

likely to be the Halfmoon Bay population on the opposite shoreline to the Project. Therefore, this

species is not considered to be present within the influence of the Project area.

Gunn’s Screw Shell (Gazameda gunnii)

Surveys for the native Gunn’s Screw Shell (Gazameda gunnii), listed as vulnerable under the

TSPA, were undertaken as part of the baseline survey for the effluent pipeline extension (CEE,

2009b). This species has become rare in shallower Tasmanian waters, where it has been

severely outcompeted by the introduced New Zealand screw shell (Maoricolpus roseus). Grab

samples of sediment where taken by CEE (CEE, 2009) around the outfall location, with no

native screw shells identified from the samples. It is considered unlikely that Gazameda gunnii

are present in the area that may be affected by the Project.

Giant Kelp Forests (Macrocystis pyrifera)

As mentioned above, there is a giant kelp forest (Macrocystis pyrifera) present around the

outfall location. When certain criteria are met, forests of Macrocystis are considered under the

EPBC Act as the threatened ecological community titled ‘Giant Kelp Marine Forests of South

East Australia’, listed as ‘Endangered’ under the Act.

The forest was surveyed as part of the baseline study for the outfall extension in 2009 (CEE,

2009). The kelp forest extends several hundred metres in either direction along the shoreline

from centreline of the effluent pipeline. In the 2009 baseline survey of the area, Macrocystis first

appeared around 90 m from the shoreline and extended out to 200 m into deeper waters of 7-

8 m. The forest spread laterally along the coast several hundred metres in 3-8 m of water depth.

The densest area of the kelp forest was found to occur in the 3-6 m depth range (CEE, 2009).

In 2015 CEE undertook an ecological risk assessment to determine whether this kelp forest met

the EPBC Act listing criteria and therefore should be considered part of the Giant Kelp Marine


Forests of South-East Australia (an EPBC Act Listed Threatened Ecological Community). CEE

(2015)6 found that the Giant Kelp forest at Blackmans Bay fulfils most of the criteria to be

considered part of the threatened ecological community, however it does not occur in water

more than 8 m deep (one of the defining characteristics). They therefore concluded the

Blackmans Bay Giant Kelp Forest was not part of the EPBC Act listed Giant Kelp Marine

Forests of South-East Australia. Although the kelp forests have been assessed by CEE as not

meeting the EPBC Act listing criteria, they remain an important ecological feature and have

been considered in the impact and mitigation sections in this DPEMP.

As noted previously the Blackmans Bay STP outfall was extended in 2010 to improve dilution of

the effluent. As part of the approval process for the extension of the original outfall, it was

recognized that nutrients from the then existing Blackmans Bay outfall discharge was likely to

be supplementing the high nutrient requirements of the macrocystis forest to a large degree. In

light of this, three diffuser ports were included in the nearshore section of the outfall extension to

enable the continued ‘fertilisation’ of the forest.

The results of the referral assessment are discussed in detail in Section 7- EPBC Act

Assessment.

Human Receptors

The shoreline immediately surrounding the existing outfall is not commonly used for shore

based fishing or swimming due to its isolation and difficult access, however recreational diving

or fishing from boat is undertaken along the shoreline.

There are no aquaculture leases within the estuary, with the nearest leases being those to the

south within North West Bay and along Bruny Island.

The Tinderbox Marine Reserve extends west from Tinderbox Bay around Passage Point to

approximately 1.5 km south of the existing outfall, and 300 m offshore. This reserve is used

regularly for recreational diving.

Water Quality

Water quality in the area surrounding the effluent outfall has been assessed on an annual basis

by TasWater following the extension of the outfall in 2010. Complimenting this is the extensive

water quality monitoring program undertaken as part of the Derwent Estuary Program, with four

monitoring sites in the vicinity of the Project.

Ambient water quality is summarised in the following sections and is interpreted from the closest

DEP monitoring site to the Project area (site B1 from DEP, 2015, which lies a little under 1km

south of the Project area) from the DEP monthly monitoring results from the State of the

Derwent 2015 report (covering January 2009 - December 2013) and from more recent data

collected from the DEP for the period July 2013 - July 2015, which was made available to

TasWater for the Project. Results are compared to the ANZECC (2000) Physical and Chemical

Stressor Default Trigger Values, which are to be interpreted with caution owing to the absence

of Tasmanian marine and estuarine water quality data in the dataset used in the development of

the trigger values, as stated in the Guidelines (ANZECC, 2000).

Physicochemical Parameters

Salinity in the area of the Project is for the most part unstratified, with concentrations

throughout the water column at a median value of 33.63 PSU (2013-2015 data). However,

stratification does occur sporadically throughout the year following large freshwater inputs

6 CEE 2015, Internal memo - Blackmans Bay STP Upgrade – Assessment of effects on Giant Kelp and North West Bay ecosystem, January 2015


from the catchment after large rain events, dropping salinity in the top layers of water to as

low as ~26 PSU (2013-2015 data).

Dissolved oxygen is generally high in the area around the Project, with a median

concentration > 97% saturation (2013-2015 data). Oxygen concentrations are generally

slightly higher at the top of the water column.

The median pH for the 2013-2015 period ranged from 7.85 - 8.24; with a median result of

8.05, typical of marine waters. There are no significant pH fluctuations with depth of water

column.

Water temperatures range from approximately 10°C in winter months to 18°C in summer

months (2013-2015 data).

Turbidity was generally very low in the area around the Project site, with samples rarely

exceeding 5 NTU, with a median value generally <1 NTU around lower estuary sites (DEP,

2015).

Site specific monitoring around the outfall location commissioned by TasWater (CEE,

2015a) correlates well with the abovementioned physiochemical attributes, as can be

expected given the proximity to the DEP monitoring site.

Nutrients and Algae

Total nitrogen is at times elevated in the Derwent Estuary when compared to the ANZECC

(2000) Physical and Chemical Stressor default trigger value (300 µg/L). This is the case for

most of the middle to lower estuary. Median values have historically been below the trigger

values though. As the estuary system is seasonally dynamic with respect to nutrient inputs,

large variations occur throughout the year. Higher nitrogen loading in the estuary system is

known to occur during winter months as a result of inputs of nutrient rich waters from the

Southern Ocean. TasWater monitoring undertaken found total nitrogen concentrations

around the outfall site ranged from 7 µg/L in November 2013 to 590 µg/L during the

baseline survey in September 2009.

Median levels of oxides of nitrogen (nitrite/nitrate) are below ANZECC (2000) default

stressor trigger values at the nearest DEP monitoring site to the Project, as outlined in

State of the Derwent Estuary 2015 (DEP, 2015); however, concentrations do exceed the

trigger value at times, generally during winter months, owing to the natural flux of nutrients

in the system, as mentioned above. Concentrations were found to be generally lower in

surface waters than bottom waters.

NHx (ammonia and ammonium) concentrations at the DEP monitoring site B1 did not

exceed stressor trigger values from 2009 - 20013 (DEP, 2015), with a median

concentration from 2013-2015 DEP data of 5 µg/L.

From the available data, organic nitrogen compounds appear to be the dominant proportion

of the total nitrogen in the estuary (e.g. particulate organic matter including phytoplankton

and suspended solids).

Total phosphorus concentrations are above ANZECC Guideline (2000) stressor trigger

values from the mid estuary to the well flushed lower parts also, suggesting that the

ANZECC stressor triggers are not appropriate for the estuary for total phosphorus (DEP,

2015).

Reactive phosphorus concentrations, as for total phosphorus, have elevated median values

above the ANZECC Guideline (2000) stressor value from the mid to lower estuary. This

may be a result of naturally higher concentrations throughout the estuary, however

concentrations appear to decline towards the mouth of the estuary according to the DEP


data, suggesting anthropogenic sources in the middle estuary may be contributing to the

concentrations observed.

Chlorophyll-α concentration is used as a proxy indicator of the concentration of

phytoplankton in an aquatic environment. At the DEP monitoring site closest to the outfall,

values have not exceeded ANZECC Guideline (2000) trigger values over the 2009-2013

period (DEP, 2015), suggesting phytoplankton blooms are not a significant issue towards

the mouth of the Derwent Estuary. Nitrogen is believed to be the likely limiting nutrient in

the growth of phytoplankton in the lower portions of the estuary (DEP, 2015), given the

ratios of nitrogen to phosphorus compounds relative to the Redfield ratio.

Metals

There have historically been large inputs of heavy metals into the Derwent Estuary as a result of

industrial water discharges, most significantly from the zinc smelter in the middle section of the

estuary (Lutana) and the paper mill at Boyer.

The most significant heavy metal still affecting water quality in the estuary is zinc; which

continues to be monitored regularly by the DEP. Concentrations around the Project area are

generally below the ANZECC (2000) 99% species protection toxicity threshold triggers;

concentrations exceeding ANZECC (2000) trigger values are most prominent in the middle

estuary area, most likely as a result of legacy groundwater intrusion from the zinc smelter site

into the waterway.


The key legislation, policy and guidelines of relevance to marine and estuarine management in

Tasmania are the:

Water Management Act 1999

State Policy on Water Quality Management 1997 (Water Policy)

Environment Protection & Biodiversity Conservation Act 1999 (EPBC Act)

Tasmanian Threatened Species Protection Act 1995 (TSPA)

Under the Water Policy, the EPA sets a range of environmental values of an aquatic area to be

protected, referred to as Protected Environmental Values (PEVs). For the receiving environment

of the effluent discharge pipeline at Blackmans Bay, the following PEVs were identified (from

EPA, 2003):

Derwent Estuary Area 2 - Lower Derwent Estuary (Tasman Bridge to Tinderbox/South Arm)

A. Protection of Aquatic Ecosystems

i. Protection of modified (not pristine) ecosystems from which edible fish, crustaceans

and abalone, but not other shellfish harvested

B. Recreational Water Quality and Aesthetics

i. Primary contact water quality

ii. Secondary contact water quality

iii. Aesthetic water quality



There is no proposal to change the existing outfall in any way; its existing orientation and

configuration will remain unchanged as a result of the Project. The following assessment relates

to the impact of the proposed change in effluent quality and quantity to be discharged from that

outfall, with no physical changes to the outfall proposed at all.

The proposal does however involve an overall increase in treated effluent to be discharged from

the STP, as well as changes (predominantly improvements) to the treated effluent quality from

the upgraded STP. Details of the proposed quality and quantity from the upgraded STP is

provided in Section 2.4.

Toxicity to Marine Species

Discharge of toxicants to the aquatic environment at concentrations above recommended limits

defined in the literature (e.g. ANZECC (2000) Guidelines) have the potential to induce acute or

chronic effects on both flora and fauna species.

Known toxicants within the Project effluent stream include ammonia and nitrate only.

Investigations on industrial waste streams currently accepted within the existing catchments to

be associated with the Project have not identified any metals or other contaminants of concern

(Section 2.3.2).

Ammonia is generally considered more toxic than nitrate in the marine environment, with no

specific guidelines for nitrate in marine or estuarine waters set in the ANZECC (2000)

Guidelines (default trigger values for freshwater ecosystems are used as a proxy). In order to

define the trigger value for ammonia in the mixing zone study, 80th percentile background data

from the Derwent Estuary Program was assessed from four nearby sites, along with the

ANZECC Guideline limits. The ANZECC (2000) Guideline default trigger value for 95% species

protection (adjusted for pH) was adopted (0.75 mg/L), as the calculated background

concentration was well below this value.

To determine the potential impacts from the effluent discharge and to define a mixing zone for

the project in line with the principles defined in Section 20.3 of the State Policy on Water Quality

Management 1997, near field mixing zone modelling was undertaken. The mixing zone

modelling report is included in Appendix D.

Several modelling runs were performed, with varying effluent flow scenarios (design capacity

ADWF and 4 x ADWF), and receiving environment characteristics, including salinity

stratification, currents and future potential climate change scenarios. Ammonia toxicity trigger

values from the ANZECC (2000) Guidelines (adjusted for ambient pH) were used to define the

mixing zone extents.

The various modelling scenarios (Scenarios 1-8 in Appendix D) all resulted in ammonia being

diluted below toxic concentrations within 5 m of each of the diffuser nozzles. Therefore, no toxic

impacts are predicted by the modelling outside of 5 m to the north and south of the diffuser, and

also 5 m to the east, as the terminal diffuser nozzle is directed perpendicular to the shoreline.

The mixing zone for the existing Blackmans Bay STP effluent discharge is set as 15 m to the

north and 15 m to the south of the diffuser. No ammonia concentrations above tox icant trigger

values have been detected at the edge of this mixing zone during the seven water quality

surveys undertaken by TasWater between 2010 and 2015 (CEE 2010).

As the ammonia dilution requirement for the Project’s effluent will be significantly lower than the

previous effluent as a result of the upgraded treatment system, the current mixing zone is

considered more than sufficient to define the mixing zone for the proposed Project.


In order to maintain the continuity in the water quality monitoring that is undertaken for the

current mixing zone area, it is proposed that the existing mixing zone boundaries are retained

for the Project, with the addition of a 15 m buffer in a radial arc to the east also, to cater for the

terminal ports easterly direction, which was not taken into account when setting the existing

mixing zone.

The substrate within the mixing zone consists of barren sand, with previous surveys (CEE,

2010) not identifying any listed species in the mixing zone, or any other significant ec ological

presence other than benthic infauna. There have been six operational benthic infauna sampling

events undertaken around the outfall between 2010 and 2015 (as well as two baseline events

prior to the outfall extension) (CEE, 2015) to monitor the impacts of the upgraded outfall.

Results have shown a slight difference in the abundance of two infauna families within 10 m of

the diffuser; no additional changes were detected. If these changes were a result of

toxicological effects from the effluent then no additional impacts are expected from the new

Project effluent, as it will have an improved ammonia concentration.

Ammonia concentrations have not been detected above the 0.75 mg/L Project trigger value

during any of the annual water quality monitoring events for the existing diffuser. This includes

sites directly above the diffuser, with the highest concentration measured at this location being

0.137 mg/L in June 2013.

By maintaining ammonia concentrations below 0.75 mg/L at the edge of the proposed mixing

zone (with the easterly modification) the potential for toxic impacts to occur to the marine

ecosystem outside of the mixing zone are considered negligible and therefore the PEVs

associated with aquatic ecosystem protection will not be prejudiced as a result of the Project

from toxicity.

Impacts will be managed and mitigated through maintenance of the effluent quality from the

Project and through the maintenance of the pipeline and diffusers functionality.

Eutrophication

Eutrophication of a waterway is the condition that results from an oversupply of key nutrients to

the environment, namely phosphates and nitrogenous compounds. Eutrophication of a marine

environment can result in a range of impacts to the ecosystem from increased biological

production.

One of the most significant potential impacts as a result of eutrophication is the increased

potential for algal (phytoplankton) blooms to occur. Chemical growth requirements for

phytoplankton are in line with the Redfield ratio of 106C:16N:1P. Within marine environments,

nitrogen is generally the limiting nutrient controlling growth rates, and as mentioned, this is the

case for the Derwent Estuary also (DEP, 2015). Large excessive inputs of nitrogenous

compounds therefore can result in rapid growth of phytoplankton, leading to blooms.

Algal blooms can impact the ecosystem through a number of pathways, including deleterious

effects of toxins produced by phytoplankton, physical obstructions to marine fauna respiratory

systems and through the depletion of oxygen levels in the environment.

Toxins produced from blooms have the potential to harm a variety of marine organisms,

including marine mammals, seabirds and fish. Humans can also be exposed to the toxins

through consumption of filter feeding marine organisms such as oysters. Several bloom events

have affected the Tasmanian shellfish industry in the last decade. Significant fish kills have also

occurred at Atlantic salmon aquaculture facilities within the D’Entrecasteaux Channel and

Tasman Peninsula area as a result of toxic algal blooms.

Secondary impacts to the marine environment from blooms occurs through the depletion of

oxygen as a result of both cellular respiration of the causative algae and through bacterial


degradation of dead algae and other marine algae dying as a result of the reduction in light

penetration from the bloom. This then leads to impacts to other organisms in the affected

ecosystem.

As the Project effluent will contain various concentrations of phosphates and nitrogenous

compounds, an assessment of the effluent composition, mass loads (of nutrients to be released)

and their subsequent fates, and the capacity for the receiving environment to cope with the

additional nutrients must be investigated.

Mass Loads

In considering mass loads to the Derwent Estuary, first an analysis was of the current and

predicted future mass loads from the existing and upgraded Blackmans Bay STP (including

amalgamation of Margate, Electrona and Howden STPs) was undertaken. These results were

then compared against the overall nutrient loads in the estuary from all existing estuary-based

STPs.

The following table (Table 6-8) shows the calculated mass loads from the existing Blackmans

Bay STP (using 2014 - 2015 data), the predicted future mass loads from the upgraded STP in

the first year of operation (including the amalgamated flows from Margate, Electrona and

Howden) and the predicted future mass loads from the upgraded STP at full capacity. The table

shows mass loads calculated on the basis of median effluent quality. As the Project is

proposing a seasonal discharge of total nitrogen and ammonia, mass loads have been

specifically calculated for each period for these parameters, which included 275 days of ‘normal’

and 90 days of ‘winter’. Result have been provided in both kilograms per day and tonnes per

year in Table 6-8.

Table 6-8 Upgraded Blackmans Bay Treatment Plant Mass Loads into

Derwent Estuary (median effluent quality)

Parameter Unit

Current

Blackmans

Bay STP

2015

Upgraded STP

Initial flows post amalgamation

(4.77ML/day ADWF)

Upgraded STP 2040 flows

post amalgamation

(8.53 ML/day AWDF)

Normal Winter

Total

Tonnes

per yr

Normal Winter

Total

Tonnes

per yr

Ammonia (as

N)

kg/day (ton/yr) 118.8

(43.4) 4.7 (1.2)

14.1

(1.3) 2.6

8.5

(2.3)

25.6

(2.3) 4.6

Total Nitrogen

(as N)

kg/day (ton/yr) 169.8

(62.0) 32.9 (9.0)

70.5

(6.3) 15.4

59.7

(16.4)

128.0

(11.5) 28.0

Total

Phosphorus

kg/day (ton/yr) 34.3 (12.5) 47.0 (17.2) 17.2 85.3 (31.1) 31.1

BOD5 kg/day (ton/yr) 87.7 (32.0) 47.0 (17.2) 17.2 85.3 (31.1) 31.1

TSS kg/day (ton/yr) 61.8 (22.6) 44.0 (17.2) 17.2 85.3 (31.1) 31.1

Oil & Grease kg/day (ton/yr) 5.6 (2.0) 9.4 (3.4) 3.4 17.1 (6.2) 6.2

7 Note – these calculations have been based on f low s of 4.698 ML/day ADWF as the calculated current f lows from combined

plants.


Notes - Results in the above tab le are from calculations made at median effluent quality. For

comparison approximate annual mass loads at 90 th percentile and maximum effluent quality (at full

design capacity – 8.53 ML/day ADWF) are as follows:

Total nitrogen 90th percentile effluent quality – 42.7 tonnes per year)

Total nitrogen at max effluent quality – 62.1 tonnes per year

Total phosphorus at 90th percentile effluent quality – 37.4 tonnes per year

Total phosphorus at max effluent quality – 46.7 tonnes per year

As the table illustrates, the upgraded STP will result in a reduction in annual mass load for all

parameters at initial flows (4.7 ML/day ADWF - immediately post upgrade and amalgamation)

with the exception of phosphorus.

Under design capacity flow conditions (8.53 ML/day ADWF) annual mass loads for ammonia,

nitrogen and BOD will still be less than the current mass loads under the existing STP. At

design capacity (8.53 ML/day ADWF), phosphorus annual mass loads are predicted to be more

than double, TSS increase by approximately 50% and oil and grease treble.

These calculations represent changes in mass loads from Blackmans Bay STP to the Derwent

Estuary and do not consider the significant mass load reductions experienced in North West

Bay (a far more closed system) as a result of decommissioning the Margate, Electrona and

Howden STPs.

In order to understand how the changes in mass load relate to the Derwent Estuary overall,

future contributions from the Project were compared to current mass load contributions from all

Derwent Estuary STPs (which have been taken from State of the Derwent Estuary 2015 (DEP,

2015)). The State of the Derwent Estuary 2015 also provides estimates of total mass loads of

nitrogen and phosphorus to the estuary during 2013 from all sources. This data indicates

approximately 2000 tonnes/year of nitrogen entered the estuary in 2013 from rivers, stormwater,

STPs and industry. Of this total, approximately 25% was from STPs within the estuary (all

STPs, not only Blackmans Bay). Over 60% was from river system inputs and the remainder

stormwater and industry. Similar data is presented for phosphorus which indicates

approximately 180 tonnes/year of phosphorus entered the Derwent Estuary in 2013. Of this just

under 50% was from combined STPs and the remainder from rivers (approx. 30%), stormwater

and industry.

Table 6-9 shows the 2013/2014 total mass loads from all Derwent Estuary STPs as well as the

approximate total mass loads for other additional parameters relating to STP effluent (approx.

only). The existing total mass loads figures for all STPs in 2013-14 were then adjusted with the

calculated future mass load contributions from the Project (including amalgamated plants) to

provide an approximate indication of the predicted future mass load contribution from all

Derwent Estuary STPs. This table represents approximate data and does not allow for change

to any other STP in the future (which in reality is likely) and should be used as a general

indicator of changes over time, not as precise data. Also – the calculated change in mass loads

from Blackmans Bay STP over time is slightly different in Table 6-8 and Table 6-9 as the former

uses measured 2015 flows and the latter uses approximate 2013 flows from the DEP. The input

data for each table therefore is slightly different.


Table 6-9 Approximate Mass Load Contributions to the Derwent Estuary

(median effluent quality)

Parameter Unit Approximate total

mass loads into the

Derwent Estuary

from all sources in

2013 (source: DEP

2015)

Current (2013/14)

mass loads from

all STPs

discharging to

Derwent Estuary

(source: DEP

2015)

Approx future (2040) mass

loads from all STPs discharging

to Derwent Estuary (with

2013/14 DEP data adjusted for

upgraded STP at 8.53 ML/day

ADWF using median effluent

quality)

Ammonia (as N) ton/yr Not available 281 247

Total Nitrogen

(as N)

ton/yr 2,000 492 458

Total

Phosphorus

ton/yr 180 88 108

BOD5 ton/yr 500 396 390

TSS ton/yr 34,000 285 284

The table shows that total ammonia and nitrogen mass loads from combined STPs are

predicted to reduce over time as a result of the Blackmans Bay STP upgrade, despite increased

flows. This is a result of significant improvements in nitrogen treatment as a result of the

upgraded plant. Overall this predicts that nitrogen inputs will reduce significantly as a result of

the Project and hence reduce the risk of eutrophication in the marine environment.

Biochemical oxygen demand and total suspended solids will decrease slightly, which is

significant given that more than double the current effluent volume will be discharged at the

design horizon discharge rate of 8.53 ML/day. Note - these figures are slightly different to the

Table 6-8 as a result of using 2015 vs 2013 input data.

The Project will result in an increase in mass load of total phosphorus. The percentage

contribution from the STP will increase significantly, and the total load to the estuary from all

STPs would increase in mass by over 20% when compared to the 2013-14 mass loads of total

phosphorus to the Derwent Estuary from all sources, including STPs, industry, stormwater and

from river discharge was estimated at ~180 tonnes during 2013 (DEP, 2015). Of this total, the

STPs were estimated to make up the majority source, at almost 50%. Based on these historical

figures, at the design horizon flow of 8.53 ML/day, the total load to the estuary would increase to

~200 tonnes/year, a ~10% increase. This is assuming that no upgrades to any of the existing

STPs occur, which is considered unlikely.

The impacts of this additional phosphorus to the nutrient balance of the waterway are very much

dependent on the input location and the subsequent transport and fate of the additional mass

load. For example, if the additional phosphorus was released in the predominately freshwater

areas in the upper estuary, where phosphorus is the limiting factor in algal growth (especially

during winter were freshwater dominates the water column in these areas), the potential for

impacts would be expected to be significantly more likely than for a release in a

marine/estuarine environment. To qualify this, far-field dispersion modelling that has been

undertaken by the CSIRO was examined for the estuary.


Far-Field Dispersion

To understand the likelihood of potential impacts from the additional phosphorus, numerical

hydrodynamic modelling undertaken by the CSIRO for the Derwent Estuary was analysed

(Herzfeld et al, 2005). The modelling included the simulated continual release of tracers from

point source locations around the estuary to analyse the percentile distributions of the tracer

over an approximate 3-month period during 2003-2004. One of the point source locations

analysed by the model was the pre-extension discharge pipeline at the Blackmans Bay STP (in

~5 m of water). The results therefore provide a reasonable indication of distribution of effluent

that would occur from the Project’s effluent discharge.

Figure 6-12 shows the modelled 50th (median) and 95th percentile concentration in the Derwent

Estuary from the simulated tracer release from the Blackmans Bay STP site after the 3 month

release period (note concentration scales are mg/L). The modelled output suggests that the

majority of the release is concentrated in an area along the Tinderbox coastline, with

concentrations lowering towards the east and to the middle of the estuary rapidly, with the

lowest concentrations in the upper estuary region and within the lower half of the Ralphs Bay

area. With a degree of caution, it can be estimated that the additional phosphorus loads will

follow a similar dispersion pattern, with the majority of loads concentrated around the Project

outfall towards the mouth of the estuary.

Figure 6-12 Modelled 50th

and 95th percentile (left and right respectively)

tracer concentrations from the pre-extension Blackmans Bay STP

marine outfall over a 3-month period from December 2003 - March

2004 (from Herzfeld et al, 2005)


As the majority of the phosphorus is likely to be concentrated in the lower portion of the estuary,

potential for eutrophication and subsequent algal blooms is considered unlikely owing to

nitrogen being the limiting factor for algal growth in this predominantly marine area, as

discussed previously.

The monitoring program outlined below includes the sampling of chlorophyll -α and phosphorus

in order to monitor ambient phosphorus concentration changes and identify any indications of

eutrophication (i.e. algal concentration increases). If changes in chlorophyll -α are detected in

line with increasing phosphorus levels in the region of the outfall, then further investigations will

be undertaken. If risks of elevated phosphorus are identified, the STP will have additional

phosphorus removal retrofitted and emission limits reviewed in consultation with the EPA.

Impacts to Potential Sensitive Receptors

Potential toxic impacts from the effluent discharge, as discussed, are expected to be restricted

to within several meters either side of the diffuser. As previously identified, the outfall site is

within a sandy habitat and there are no sensitive receptors identified within the mixing zone. The

potential for the listed Spotted handfish or Gunns screw shell to occur in the area has been

assessed as unlikely through marine surveys of the area (CEE, 2009).

The giant kelp forest present at Blackmans Bay is the most significant sensitive receptor

identified in the immediate vicinity of the outfall. As previously discussed, it is theorised that the

persistence of this kelp forest over previously forested locations in the estuary is to some

degree a result of the high nutrients, specifically nitrogenous compounds, supplied by the

current outfall (via the ‘fertiliser ports’ and the diffuser).

As the Project has been designed to meet AMT treatment limits for nitrogenous compounds

(with the exception of the ‘Winter’ period), the resulting effluent stream will contain significantly

lower concentrations of nitrogen compared to the existing effluent stream. Therefore, there is

potential to significantly impact the kelp forest by modifying the nutrient source.

As part of the mixing zone modelling undertaken for the Project (Appendix D), DEP water quality

data from a combination of four sites within the lower estuary area were analysed to estimate

ambient concentrations of nitrogenous compounds in the area. These results were then

compared with the monitoring results collected by TasWater (CEE, 2015a) for the area

surrounding the outfall. This assessment allows a comparison between the available nutrients in

the area that may be impacted (i.e. in the vicinity of the kelp forest) and the ambient conditions

of the general area. This can then be used to determine the order of difference that would likely

result from reducing the nutrient output at the diffuser on nitrogenous compounds, and hence

the potential impacts on the kelp forest. The concentrations of total nitrogen and ammonia for

both areas are displayed in Table 6-10. It is noted that the outfall itself may have an effect on

the ambient concentrations in the lower estuary sites.


Table 6-10 Nitrogenous Compounds Concentration Comparison between

Ambient Lower Derwent Estuary and Outfall Monitoring Sites

Parameter Percentile

Lower Estuary

(2004-2015)

(Source: DEP

data)

Outfall North (2011-2015)

(CEE, 2015a data)

Outfall South (2011-2015)

(CEE, 2015a data)

Distance from Outfall 10 m 100 m 1000 m 10 m 100 m 1000 m

Total

Nitrogen

(mg/L N)

Median 0.270 0.300 0.310 0.280 0.280 0.320 0.255

80th

Percentile

0.316 0.326 0.322 0.370 0.334 0.370 0.320

NHX (mg/L

N)

Median 0.006 0.025 0.011 0.008 0.012 0.010 0.009

80th

Percentile

0.013 0.053 0.019 0.009 0.083 0.054 0.012

The results suggest that total nitrogen concentrations between ambient background sites and

the outfall site are similar. Ammonia is elevated at 10 m and 100 m from the outfall compared to

ambient concentrations, but no large difference is seen at 1000 m.

This analysis (although limited) suggests that there are slightly elevated levels of

ammonia/ammonium directly around the outfall, but total nitrogen is at similar concentrations to

ambient waters around the outfall. No data was available for oxides of nitrogen around the

outfall to compare nitrate/nitrite concentrations to ambient conditions, which is an important

factor in determining the bioavailable fraction of total nitrogen.

Further water quality monitoring around the kelp forest itself would be required to establish a

confident determination of probable impacts from reducing effluent nitrogen concentrations; a

determination of the likely impacts to the kelp forest are therefore difficult to ascertain.

Fertiliser ports on the existing effluent pipeline will remain to deliver a proportion of the available

nitrogen in the Project effluent to the forest. Monitoring will be undertaken (refer below) to

assess any changes in kelp forest over time. If the persistence of the kelp forest is found to be a

direct result of the anthropogenic input of nutrients, it is considered unsustainable in the long-

term to maintain the forest through releasing effluent of a lower quality than AMT standards.

The rocky reef environment along the shoreline and several hundred metres offshore is not

expected to be significantly impacted. A reduction in nutrients may alter the species of algae

that grow on the reef, but the ecosystem as a whole will remain as per surrounding rocky reef

areas (e.g. tinderbox area).

Human Receptors

The key risks for human receptors from the marine environment as a result of STP effluent

include contact with waters containing elevated levels of pathogens (measured as

thermotolerant coliforms and enterococci), primary exposure to toxicants released from algal

blooms (as a result of eutrophication), and exposure to toxicants from consumption of harvested

filter feeding molluscs (e.g. oysters and muscles) that have ingested toxicants from algal

blooms.

With respect to thermotolerant coliforms, ANZECC (2000) Guidelines suggest a safe

concentration of faecal coliforms for primary contact activities (swimming/diving) to be <150

CFU/100 ml (or 35 enterococci 100ml) and <1000 CFU/100 ml (or 230 enterococci/100ml) for

secondary contact (boating/fishing). The proposed emission limits for the upgraded STP are 200


CFU/100 ml (median), 500 CFU/100 ml (90th percentile) and 750 CFU/100 ml (max). As the

mixing zone analysis shows (Appendix D) at 90th percentile emission limits from the plant

(500CFU /100mL - which is already below the secondary contact trigger) dilution to the primary

contact trigger is achieved within the proposed mixing zone (in fact within approximately 5 m of

the diffusers). As no swimming or diving is permitted within the mixing zone, risks to human

health from contact with pathogens is considered to be low.

The risk of algal bloom (and associated human impacts) is addressed above under

“eutrophication” and is mitigated predominantly as nitrogen is the limiting factor in the marine

environment of the lower estuary and the proposed STP upgrade results in a significant nitrogen

reduction and is not expected to pose any increase risk of algal bloom.

Analysis undertaken for the STP to date and from the trade waste input streams indicates there

are no heavy metals or other parameters of concern likely to occur in the effluent with the

potential to accumulate in filter feeders (hence, posing little risk human receptors).

There are no aquaculture leases within proximity of the existing outfall, with the nearest leases

being in North West Bay. No impacts are expected to these leases as a result of the upgraded

Blackmans Bay STP. Water quality within North West Bay (where the nearest leases lie) will be

significantly improved as a result of the Blackmans Bay Upgrade and eventual decommissioning

of the Electrona and Margate STPs (which currently discharge into North West Bay).


The ambient environment around the current outfall mixing zone is considered to already be

well described following the historic work undertaken by both TasWater and the DEP. The

ecology of the area, the sediments and water quality has been monitored annually since the

extension of the current outfall and the DEP has been monitoring water quality at several

reference sites monthly for a number of years. Therefore, as the existing mixing zone is not

being significantly altered as result of the Project (with the minor exception of the eastern end of

the diffuser), it is considered that sufficient information to characterise ambient conditions has

already been captured, and a full 12-month ambient monitoring program is not warranted in this

instance.

The following monitoring program therefore aims to expand the current monitoring regime to

ensure it is more robust, and to build on it in areas where new potential impacts are present

(e.g. the effects of the nutrient loss to the giant kelp forest).

Water Quality Monitoring

The marine water quality monitoring program for the Project will be based on the existing

program (CEE, 2015a), with the inclusion of additional monitoring sites and parameters. The

methodology for sample collection will remain as per the existing program.

The water quality monitoring sites, parameter groups, and sampling frequencies are shown in

Table 6-11. The parameter groups mentioned in the table refer to those listed in Table 6-12.

Monitoring sites are shown spatially in Figure 6-13.


Table 6-11 Water Quality Monitoring Sites, Parameter Groups and

Monitoring Frequency

Site Name Parameters Depths Frequency

Outfall A**, B, C, D* surface, mid, bottom -biannually prior to

commissioning

(summer / winter) at the

approval of the Project

-Once during the 6

month commissioning

period

-biannually in the year

following

commissioning

-Annually following year

1

North of Outfall (15

m, 50 m, 100 m, 250

m)

A**, B, C, D* 15 m - surface, mid,

bottom

Remaining - mid

South of Outfall (15

m, 50 m, 100 m, 250

m)

A**, B, C, D* 15 m - surface, mid,

bottom

Remaining - mid

East of Outfall (15 m) A**, B, C, D* 15 m - surface, mid,

bottom

Reference Sites 1, 2

(DEP Sites B1 & B2)

A**, B, C, D* mid

Kelp Sites (N, S, O) A**, B surface, mid, bottom

*Group D (Metals) parameters to be ceased following 12-month post-commissioning monitoring if no

difference between pre-commissioning and post-commissioning identified.

**Depth profile of whole water column at 1 m intervals to be collected.

Table 6-12 Water Monitoring Parameters

Parameter

Group A: Physicochemical (in situ)

pH, Temperature, Salinity, Dissolved oxygen, Turbidity

(Instrument sensitivity to suit ANZECC (2000) Guideline physical and chemical stressors

concentration values)

Group B: Nutrients (laboratory)

Total Nitrogen, Ammonia as N, Nitrate as N, Nitrite as N, Total Phosphorus as P, Reactive

Phosphorus as P, Chlorophyll-α

(Lab sensitivity to suit concentrations from ANZECC (2000) Guideline physical and chemical

stressors concentrations)

Group C: Other (laboratory)

Chloride, Oil and Grease, Total Dissolved Solids, Total Suspended Solids, Thermotolerant

Coliforms

Group D: Metals (laboratory)

Dissolved metals suite (Sb, As, Be, B, Cd, Cr, Co, Cu, Pb, Mn, Mo, Ni, Se, Ag, Sn, Zn)

(Lab sensitivity to suit concentrations from ANZECC (2000) Guideline 95% protection for

toxicants where possible)


Benthic Infauna

Benthic infauna monitoring will be undertaken as per the methodology outlined in CEE (2015b).

Frequency of proposed sampling is identified in Table 6-13. Following the 12-month post

commissioning period, sampling frequency is to be reduced to once every three years as any

impacts detected in the first year following commissioning would not be expected to change as

rapidly. Sampling every three years will follow increases in flows to the design horizon to some

degree. Once full design capacity has been reached, the necessity for benthic infauna sampling

shall be re-assessed in consultation with the EPA.

Table 6-13 Benthic Infauna Site and Frequency

Site Name Frequency

Outfall -Once pre commissioning

-Once during the 6-month commissioning

period

-biannually in the year following

commissioning

-Triennially following first 12 months

North of Outfall (15 m, 50 m, 100 m, 250 m)

South of Outfall (15 m, 50 m, 100 m, 250 m)

East of Outfall (15 m)

Kelp Monitoring

Giant kelp will be monitored by divers swimming four 100 m transects at the sites and

frequencies identified in Table 6-14. Monitoring methodology is proposed as follows:

Number of stipes counted within 1 m of the transect, changing sides every 10 m of the

transect.

Canopy density estimated every 10 m, based on a 0-4 ranking, with 0 being no coverage, 1

being 25% and 4 being 100%.

Table 6-14 Giant Kelp Forest Monitoring Sites

Site Frequency

0-100 m north of fertiliser ports -Once pre commissioning

-Twice in first 12 months following

commissioning

- Annually following year 1 (frequency to be

reviewed three years following

commissioning with the EPA)

0-100 m south of fertiliser ports

0-100 m south (outer) of fertiliser ports

As well as diver surveys, a trial of mapping the kelp forest area using visible fronds on the

water’s surface to delineate the occupancy area will be trialled during the first diver survey, with

TasWater and survey sub-contractors to determine the effectiveness of this methodology. If

successful, mapping will occur during each giant kelp survey.


Review and Adaptive Management

The results of the monitoring program will be provided annually to the EPA with a section in the

report identifying the effectiveness of the program, any noted significant impacts and any

suggested changes to the program and suggested management/mitigation if required.

Should significant results be detected in the first 12-months following the commissioning period

from any of the sampling program components, the EPA will be informed as soon as

practicable.

Adaptive management may include altering the treatment process or methodology, which will be

undertaken with guidance from the EPA. This includes improvements to phosphorus removal

within the upgraded STP, in the event elevated phosphorus levels are identified as having a

detrimental impact in the receiving environment.

Commitment 26 Receiving waters monitoring will be undertaken at 15

sites (as shown in Figure 6-13) biannually pre-commissioning,

during commissioning and in the first year of operation and annual

thereafter.

Commitment 27 Benthic infauna monitoring will be undertaken at 10

sites (as shown in Figure 6-13) once pre-commissioning, once

during commissioning, biannually in the first year and triennially

thereafter.

Commitment 28 Kelp monitoring will be undertaken at 4 sites, once pre-

commissioning, twice in the first year following commissioning

and annually thereafter (until reviewed with the EPA).

Commitment 29 If the monitoring program reveals marine impacts as a

result of phosphorus in the STP discharge, the EPA will be

contacted and phosphorus removal will be retrofitted to the STP

and new emission limits established in consultation with the EPA.

Proposed mixing zone

Giant Kelp

Kel

p N

orth

Kel

p S

outh

Kel

p O

uter

Outfall 15 m East

15 m South

15 m North

50 m South

50 m North

250 m South

250 m North

100 m South

100 m North

the LIST © State of Tasmania

526,800

526,800

527,000

527,000

527,200

527,200

527,400

527,400

5,237

,200

5,237

,200

5,237

,400

5,237

,400

5,237

,600

5,237

,600

5,237

,800

5,237

,800

G:\32\18107\GIS\Maps\MXD\3218107_008_Figure6-12_MarineMonitoring_RevC.mxd

0 40 8020


Horizontal Datum: GDA 1994Grid: GDA 1994 MGA Zone 55 o

© 2016. Whilst every care has been taken to prepare this map, GHD (and DATA CUSTODIAN) make no representations or warranties about its accuracy, reliability, completeness or suitability for any particular purpose and cannot accept liability and responsibility of any kind(whether in contract, tort or otherwise) for any expenses, losses, damages and/or costs (including indirect or consequential damage) which are or may be incurred by any party as a result of the map being inaccurate, incomplete or unsuitable in any way and for any reason.


Job NumberRevision A

32-18107

08 Aug 2016

Marine Monitoring Sites

Date



Paper Size A3

LEGENDWater quality and benthic infaunaWater quality only

Kelp survey transectsDiffuserEffluent Pipeline

Giant KelpProposed mixing zone

Reference East (DEP-B3)

Reference West (DEP-B1)

the LIST © State of Tasmania

Location Easting Northing

250 m North 527367 5237630

100 m North 527367 5237480

50 m North 527367 5237430

15 m North 527367 5237395

Outfall 527367 5237380

15 m South 527367 5237365

50 m South 527367 5237330

100 m South 527367 5237280

250 m South 527367 5237130

15 m East 527413 5237380

Reference West (DEP-B1) 527780 5236750

Reference East (DEP-B3) 530740 5236350

Kelp North 526943 5237430

Kelp South 526943 5237330

Kelp Outer 526993 5237330

Location Easting Northing

Kelp North (start) 526940 5237480

Kelp North (f inish) 526940 5237380

Kelp South (start) 526940 5237380

Kelp South (f inish) 526940 5237280

Kelp Outer (start) 526990 5237380

Kelp Outer (f inish) 526990 5237280

Water quality and benthic infauna sampling

Kelp transects

Figure 6-13


6.9 Greenhouse Gases and Ozone Depleting Substances

This section considers the potential implications of the proposal on greenhouse gas production

and ozone depleting substances.


Climate change and greenhouse gas emissions are currently regulated under the National

Greenhouse and Energy Reporting Act 2007. The National Greenhouse and Energy Reporting

Scheme (NGERS) was formed in 2007 under the Act to provide a reporting framework for

greenhouse emissions. The Act outlines threshold emissions for greenhouse gas and energy

consumption (Section 13 of the Act), under which level companies are not required to report on

energy consumption or greenhouse emissions, these are:

50,000 tonnes of equivalent CO2 per annum (tCO2-e/annum) for a corporate threshold or

25,000 tCO2-e/annum for a facility threshold; and

200 terajoules/annum (TJ/annum) for a corporate threshold or 100 TJ/annum for a single

facility threshold.

6.9.2 Energy Consumption and Emissions

Construction Power and Fuel Consumption

Construction of the project will require several thousand litres of diesel for heavy machinery,

including excavators, cranes and dozers, as well as diesel generators required during

construction. Electricity supply will also be required for a range of features during the

construction phase, as well as the ongoing powering of the existing STP site.

Operation Power and Fuel Consumption

The Project is estimated to have an energy consumption of 6500 kWh/day at the full operating

volume of 8.53 ML/day ADWF. Additionally, there will be the potential to use small volumes of

diesel for emergency power generation.

NGERS Calculations

Table 6-15 displays the emission calculations for the operation of the Project, using the ‘Indirect

emissions from consumption of purchased energy’ calculation (DoE, 2014). Although the

consumption and emissions from the Project do not trigger the ‘facility’ threshold, TasWater’s

combined infrastructure exceeds the corporate threshold reporting requirement and therefore

TasWater are required to submit annual NGERs reports across all their assets. Calculations for

this Project will be included in these reports.

Omitted from the estimates in Table 6-15 are any fuels used in the construction or operation of

the Project, as these are only used for construction and very intermittently in emergency or

shutdown events during operation.


Table 6-15 NGERS Calculations for the Project

Aspect Project NGERS ‘facility’ threshold

Electricity Consumption 6500 kWh/day N/A

Energy Consumed

(TJ/annum)

8.541 100

CO2 Emissions* (tCO2-

e/annum)

474.5 25,000

*Emission factor of 0.2 kg CO2-e/kWh for used for Tasmania from NGA Factors to calculate figure

Ozone Depleting Substances

Ozone depleting substances will be used in insignificant quantities for the Project for

refrigeration facilities for staff (this is no change from current operations).


In order to reduce carbon emissions and implement best practice greenhouse impact

management, the following management and mitigation is proposed for the Project.

To minimise power consumption, the following is proposed where practicable:

Use of energy efficient processing equipment;

Use of energy efficient lighting around the site where suitable (e.g. LEDs); and

Administration spaces built to 5-star energy efficiency code.


Consumption of fuel and power will be recorded monthly and assessed on an annual basis with

any potential improvements in energy efficiency to be investigated and actioned upon. This may

include upgrades to pumps and other equipment if more efficient options become avai lable.

As mentioned, TasWater operates a large number of sewage treatment facilities as well as

other infrastructure and are required to submit annual NGERs reports; the energy consumption

from the Project will be included in the calculations for submission to the Commonwealth

government.


6.10 Heritage

This section considers the potential impacts of the Project on identified Aboriginal and European

heritage values. Assessment of potential impacts to geoheritage sites has also been

undertaken.


Aboriginal Heritage

TasWater sought advice from Aboriginal Heritage Tasmania (AHT) in 2012 about Aboriginal

heritage values at the existing Blackmans Bay STP site and immediate surrounds. Advice was

provided by AHT on 25 January 2012 advising that there were no known Aboriginal heritage

sites recorded within, or close proximity to, the Project Site and due to the area being highly

disturbed there was deemed a low probability of Aboriginal heritage being present. AHT

concluded that there was no requirement for an Aboriginal heritage investigation and AHT had

no objection to the Project proceeding.

European Heritage

In 2015 TasWater commissioned a search of the Tasmanian Heritage Register and any places

on the Tasmanian Historic Places Inventory. There were no listed heritage features identified

within or immediately surrounding the Project Site which could be impacted by the Project.

A review of the EPBC Act Protected Matters Search Tool (August 2016) indicates no National

Heritage or World Heritage Places within or immediately surrounding the Site.

A review of the Kingborough Interim Planning Scheme Registers reveals two geoheritage sites

within 1 km of the Project Site as discussed below.

Geoheritage

There is one geoconservation site mapped along the eastern boundary of the Project Site

(Figure 5 3). This site is the Blackmans Bay Dolerite Contact and is related to coastal exposure

of dolerite along the foreshore. The geoconservation site lies outside of the proposed Project

Footprint and is not expected to be impacted by the Project.

The Kingborough Planning Scheme also mentions two geoheritage features (refer Section

6.7.1), namely the Blackmans Bay Geoheritage Site and Blackmans Bay Geological Monument.

The address given for these features is Fossil Drive and they are presumed to be part of the

Fossil Cove Conservation Area, approximately 500 m south of the Project Site. No impacts will

occur to these features as a result of the Project.


Aboriginal Heritage

Relevant legislation for the protection of Aboriginal heritage in Australia includes the Aboriginal

Relics Act 1975 at State level in Tasmania and the Aboriginal and Torres Strait Islander

Heritage Protection Act 1984 at a Commonwealth level.

European Heritage

The key legislation in Tasmania relating to European heritage is the Historic Cultural Heritage

Act 1995. This legislation is governed by the Tasmanian Heritage Council (THC), who is

consulted with to identify any places listed on the Tasmanian Heritage Register that may be

affected by a proposal, and to identify any subsequent development approval requirements.


At a Commonwealth level, Declared World Heritage Area properties and values, places listed on

the National Heritage List and any places listed or interim listed on the Register of the National

Estate and values need to be considered.


Aboriginal Heritage

As noted above there are no known Aboriginal heritage features within or surrounding the Site

and AHT confirmed that no further investigations were required and that they had no objection

to the Project.

No impacts to Aboriginal heritage are anticipated as a result of the Project.

European Heritage

As outlined above there are no known European heritage features within or immediately

surrounding the Project Site and therefore no impacts are expected as a result of the Project.

Geoheritage

There are two geoheritage sites on the Kingborough Interim Planning Scheme Register, which

lie approximately 500 m south of the Project Site and well outside of the Project Footprint. There

will be no impact to these features as a result of the Project.

There is also a geoconservation site mapped on The LIST along the coastline within the Project

Site, however all active construction works for the Project Footprint are outside of this

geoconservation site and no impacts are expected as a result of the Project.


To avoid impact to the known geoconservation site along the coastline (Figure 5-3) the works

for the Project will be contained within the western side of the current fence line of the existing

STP site and within the temporarily fenced construction compound, which are outside of the

mapped geoconservation site.

Although there are no known Aboriginal or European heritage features within the Project

Footprint, there always remains potential for unanticipated discovery of heritage features during

excavation work. To manage this risk, an Unanticipated Discovery Plan (available from

Aboriginal Heritage Tasmania) will be included in the CEMP for the Project and followed by all

contractors.


As outlined above, an Unanticipated Discovery Plan will be included in the Site CEMP and

followed in the event of discovery of previously undetected heritage features.

Commitment 30 An Unanticipated Discovery Plan will be included in the

Site CEMP and followed in the event of discovery of previously

undetected heritage features.


6.11 Land Use and Development


The site is an existing sewage treatment plant. The plant has existed since the 1980s and is

subject to a 300m attenuation area under the Interim Scheme, the objective of which is to

protect the site from encroachment from sensitive use. There are existing residences within the

attenuation area to the north and the west.

The adjoining Council land essentially comprises a buffer between the plant and these

residential areas and is used for walking trails.


Planning Scheme

The site is located within the Kingborough Municipality. The applicable planning scheme is the

Kingborough Interim Planning Scheme 2015 (the Interim Scheme) and the relevant planning

authority is the Kingborough Council (the Council). An assessment against the relevant

provisions of the Interim Scheme is provided in Section 6.11.3 of this DPEMP.

Environmental Management and Pollution Control Act 1994

The proposed development is level 2 activity under Schedule 1 of EMPCA. Accordingly, the

application is deemed to be discretionary in accordance with Section 57 of the Land Use

Planning and Approvals Act 1993.

Council will refer the application to the EPA for assessment. In accordance with Section 25(2)

of EMPCA, Council is not required to assess any matter addressed in the EPA Board’s

assessment. Relevant to this assessment are environmental matters relating to noise and

odour. Accordingly, a planning assessment has not been undertaken against the planning

scheme requirements for these matters as these are addressed as part of the EPA assessment.

Water and Sewerage Industry Act 2008 & Water and Sewerage (General) Industry

Regulations 2009

Sections 56H and 56I of the Water and Sewerage Industry Act 2008 prescribe that certain

works do not require planning approval, as they are not regarded as development for the

purposes of the Land Use Planning and Approvals Act 1993. This includes:

Subdivision of land necessary to give effect to the acquisition subject to meeting the criteria

prescribed in the Water and Sewerage (General) Industry Regulations 2009; and

Construction of sewerage infrastructure by TasWater in accordance with the above

Regulations.

No subdivision is proposed as part of the proposal, as the whole of Council land is proposed to

be acquired. Accordingly, it is only necessary to identify those sewage infrastructure works that

are not considered to be development, and therefore do not form part of the works to be

assessed by Council as part of the planning approval.

Also, the underground pipelines and pump stations do not form part of the scope of the

development application as per the assessment against Regulation 11 of the Water and

Sewerage (General) Industry Regulations 2009 below.


Table 6-16 Regulation 11 of the Water and Sewerage (General) Industry

Regulations 2009

Clause Regulation Assessment

11. Work that is not

use or development

under Land Use

Planning and

Approvals Act 1993

For section 56I(b) of the Act, the following

are prescribed:

a) the removal, repair, maintenance,

modification, installation, erection or

use of a pump station associated with

the distribution or removal of water or

sewage;

b) the removal, repair, maintenance,


use of a fluoridation station associated

with the provision of water;

c) the removal, repair, maintenance,


use of a chlorination station

associated with the provision of water,

if the chlorine used or stored is not at

any time in a gaseous form;

d) the laying, removal, repair,

maintenance, modification or use of

any underground pipeline for the

removal or distribution of water or

sewage;

da) the installation, removal, repair,

maintenance, modification,

replacement or use of a meter for

water infrastructure, whether the

meter is above or below ground, if the

installation, removal, repair,

maintenance, modification,

replacement or use is associated with

the provision of water by a regulated

entity;

e) the clearing or lopping of trees,

branches or other vegetation to the

extent necessary to protect water

infrastructure, sewerage infrastructure

or water quality, except if those trees

are on –

i. the Register of the National

Estate kept by the Australian

Heritage Commission; or

ii. the National Trust Register.

The following works fall

within the scope of

Regulation 11 and do not

require planning approval:

Pump stations -

subclause a)

Underground pipelines -

subclause d)

Vegetation clearance, to

extent required to protect

sewerage infrastructure -

subclause e).


6.11.3 Assessment of Planning Aspects

The Project is to upgrade and expand the existing Blackmans Bay STP. This will result in an

expansion of the development footprint bringing the plant closer by approximately 10-20 metres

to the three residences located within the Environmental Living Zone to the west. It will also

result in rerouting of the Suncoast Headlands Track during and post construction. As previously

identified, the proposed upgrade works will address deficiencies with the current plant to meet

emission limits and manage odour impacts. The Project aims to significantly improve plant

performance to the Tasmanian EPA’s Accepted Modern Technology (AMT) performance.

Assessment of an Application

In determining a permit application Council must have regard to (Clause 8.10.1 of the Interim

Scheme):

a) all applicable standards and requirements in this planning scheme; and

b) any representations received pursuant to and in conformity with ss57(5) of the Act,

but in the case of the exercise of discretion, only insofar as each such matter is

relevant to the particular discretion being exercised

In determining any discretionary aspects of the proposal Council must in addition to

8.10.1, have regard to 8.10.2:

a) the purpose of the applicable zone;

b) any relevant local area objective or desired future character statement for the

applicable zone;

c) the purpose of any applicable code; and

d) the purpose of any applicable specific area plan.

but only insofar as each such purpose, local area object or desired future character

statement is relevant to the particular discretion being exercised.

The proposal requires exercise of discretion in relation to Utility Zone development standards in

relation to building height, fencing and setbacks; and Environmental Living Zone in relation to

use, use standards, setbacks, design and environmental values. The proposal also requires

discretion under the Potentially Contaminated Land, Stormwater Management and Coastal

Erosion Hazard Area Codes.

An assessment in accordance with subclause 8.10.1(a) and Clause 8.10.2 of the Scheme is

provided below.

Planning Scheme Objectives

The Planning Scheme Objectives applicable to the proposal include:

The efficiency of existing physical infrastructure is maximised.

Physical infrastructure and servicing is planned, co-ordinated and delivered in a timely

manner to support the regional settlement pattern and specific growth management

strategies.

Local infrastructure (roads, water, sewerage etc) is planned and delivered in a manner

that enables the efficient development of land, both now and into the future.

Local infrastructure is constructed so that it provides a safe and convenient service to

users.


Local infrastructure is designed to a high standard and ensures the protection of local

environmental conditions.

Consistent with the above objectives the proposed upgrade works will cater for projected

increase in sewage flow to the Blackmans Bay STP from the immediate catchment. In addition,

the upgrade has been planned as part of a strategic rationalisation of STPs in the broader area

and will be designed to cater for current and projected future loads from the ageing Margate,

Electrona and Howden STPs, which are planned for decommissioning. As well the proposed

works will improve the environmental operation of the existing plant to current standards.

Use Categorisation

The use classification for the proposed use and development is ‘Utilities’ which is defined in

Table 8.2 of the Scheme as follows:

Utilities:

Use of land for utilities and infrastructure including:

a) telecommunications;

b) electricity generation;

c) transmitting or distributing gas, oil or power;

d) transport networks;

e) collecting, treating, transmitting, storing or distributing water; or

f) collecting, treating, or disposing of storm or floodwater, sewage or sullage.

Examples include an electrical sub-station or power line, gas, water or sewerage main,

optic fibre main or distribution hub, pumping station, railway line, retarding basin, road,

sewage treatment plant, storm or flood water drain, water storage dam and weir.

6.11.4 Utilities Zone

Use Table

Utilities are a Permitted use within the Zone.

Use Standards

Clause Interim Scheme Compliance Assessment

28.3 Hours of

Operation, A1

Hours of operation of a use within 50

m of a residential zone must be

within 7.00 am to 7.00 pm, except if:

for office and administrative tasks; or

(ii) a Utilities use.

Complies with subclause (ii)

as the use is Utilities

28.3.2 Noise, A1 Noise emissions measured at the

boundary of a residential zone must

not exceed the following:

55 dB(A) (LAeq) between the hours

of 7.00 am to 7.00 pm;

5dB(A) above the background (LA90)

level or 40dB(A) (LAeq), whichever is

Complies. See summary of

noise assessment report

findings at Section 6.4 of this

DPEMP.



the lower, between the hours of 7.00

pm to 7.00 am;

65dB(A) (LAmax) at any time.

Measurement of noise levels must be

in accordance with the methods in

the Tasmanian Noise Measurement

Procedures Manual, issued by the

Director of Environmental

Management, including adjustment

of noise levels for tonality and

impulsiveness.

Noise levels are to be averaged

over a 15 minute time interval.

28.3.3 External

Lighting, A1

External lighting (not including street

lighting) within 50 m of a residential

zone must comply with all of the

following:

a) be turned off between 10:00 pm

and 6:00 am, except for security

lighting;

b) security lighting must be baffled

to ensure they do not cause

emission of light outside the

zone.

Not applicable as the

proposed lighting will be

located in excess of 50m

from the boundary with the

General Residential Zone.

There will be new security

and operational lighting

around the new

infrastructure. Lighting will be

free standing and building

mounted and will be angled

towards the building.

28.3.4 Commercial

Vehicle Movements,

A1

Commercial vehicle movements,

(including loading and unloading

and garbage removal) to or from

a site within 50 m of a residential

zone must be within the hours of:

a) 7am to 7pm Monday to Friday

inclusive.

b) 9am to 5pm Saturdays

c) Nil on Sundays and Public

Holidays.

Not applicable as outlined

above the proposed works

are not within 50m of a

‘residential zone’. As outlined

in Section 2.6.2 of the

DPEMP any deliveries will be

conducted during manned

operating hours (0700 to

1700) five to six days a

week.

28.4.1 Building

Height, A1

Building height must be no more

than: 10 m.

Partially Complies. The

maximum building height is

7m, except for the odour

stack which is 12m

28.4.1 Building

Height, P1

Building height must satisfy all of the

following:

Complies. There is not

DFCS (subclause a). The

stack is required for the

functional requirement of the

plant in accordance with



a) be consistent with any Desired

Future Character Statements

provided for the area;

b) be compatible with the scale of

nearby buildings unless the

height is necessary for the

functional requirements of

infrastructure;

c) not unreasonably overshadow

adjacent public space;

d) allow for a transition in height

between adjoining buildings,

where appropriate.

subclause b) and will not

result in an unreasonable

impact on the adjoining

council land (subclause c).

The stack will be internal the

site, and given the distance

to the nearest residential

dwelling it is not necessary to

provide for any transition in

height in accordance with

subclause d).

28.4.1 Building

Height, A2

Building height within 10 m of a

residential zone must be no more

than 8.5 m.

Not applicable. No buildings

are within 10m of a

‘residential’ zone.

28.4.2 Setback, A1 Building setback from frontage must

be no less than: 10 m.

Complies. The site is

accessed via a private right

of way arrangement (see

Section 5.1 of the DPEMP).

The nearest road is

Tinderbox Road, which is

located in excess of 10m

from the nearest building.

28.4.2 Setback, A2 Building setback from a residential

zone must be no less than:

a) 5 m;

b) half the height of the wall,

whichever is the greater.

Complies, the buildings are

located in excess of 5m from

the General Residential

Zone.

28.4.4 Outdoor

Storage Areas, A1

Outdoor storage areas for non-

residential uses must comply with all

of the following:

a) be located behind the building

line;

b) all goods and materials stored

must be screened from public

view;

c) not encroach upon car parking

areas, driveways or landscaped

areas.

Complies. No outdoor

storage is proposed, with all

storage internal to the

buildings.

28.4.5 Fencing, A1 Fencing must comply with all of the

following:

Assessment required against

P1.



a) fences and gates of greater

height than 2.1 m must not be

erected within 10 m of the

frontage;

b) fences along a frontage must

be 50% transparent above a

height of 1.2 m;

c) height of fences along a

common boundary with land in

a residential zone must be no

more than 2.1 m and must not

contain barbed wire.

A new fence will be located

as shown on the site plan

and will be the same as

existing which is 2.4m high

cyclone fencing with 3

strands barbed wire at the

top.

28.4.5 Fencing, P1 Fencing must contribute positively to

the streetscape and not have an

unreasonable adverse impact upon

the amenity of land in a residential

zone which lies opposite or shares a

common boundary with a site, having

regard to all of the following:

a) the height of the fence;

b) the degree of transparency of

the fence;

c) the location and extent of the

fence;

d) the design of the fence;

e) the fence materials and

construction;

f) the nature of the use;

g) the characteristics of the site,

the streetscape and the locality,

including fences;

h) any Desired Future Character

Statements provided for the

area

Complies. The proposed

fencing is for security

purposes and is consistent

with the existing fencing.

The fencing also relates to

an internal site, that is

surrounded by open space,

such that it will not affect the

‘streetscape’.

28.4.6 Environmental

Values, A1

No trees of high conservation value

will be impacted.8

Partly complies as (see

Section 6.7 of DPEMP)

found that as there were:

No trees listed in the

Threatened Species

Protection Act 1995

8 A tree of high conservation value is defined as “means a tree that is of a species that is listed in the Threatened Species Protection Act 1995 or the Environment Protection and Biodiversity Conservation Act 1999 (Cth) and/or provide potential or significant habitat for a threatened species listed in either of those acts”



or the Environment

Protection and

Biodiversity

Conservation Act

1999 (Cth) are

impacted.

The surveys found

relatively limited

habitat values for

threatened fauna

species within the

Project Site due to

the highly modified

nature of the site and

its proximity to

densely populated

residential areas; as

well as large areas of

alternative habitat

adjacent to the study

area that are of

much higher quality

The swift parrot could

however potentially nest

and feed within the

eucalypt species found

on site. Some eucalypts

will be impacted by the

Project. Assessment is

therefore required

against P1 in relation to

the potential habitat

values associated with

the trees of high

conservation value


Values, P1

Buildings and works are designed

and located to avoid, minimise,

mitigate and offset impacts on trees

of high conservation value.

Complies. The potential

impact is assessed in

Section 6.7 of the DPEMP.

The key outcomes as

relevant to Council’s

Biodiversity Offset Policy are

summarised and expanded

as follows:

The survey and mapping

identified 5 E. globulus trees

with a DBH of 40 or greater



have been recorded in the

area that maybe impacted.

There are 128 E. globulus

trees with a DBH of >40

recorded in the study area.

The 2014 ecological work

assessed the threatened

vegetation community within

which the trees are located

as being of low condition.

The assessment of low

condition of the vegetation

communities is based on the

absence of diversity in the

understorey and ground

layer components.

Conservation significance

and overall condition of

vegetation communities was

assessed in accordance with

the TASVEG 2004 and

Regional Forestry

Agreement (RFA)

classification and associated

criteria.

A replanting proposal (at a

ratio of 3:1) is proposed in

accordance with the

commitments outlined in

6.7.4 of DPEMP and

landscaping plan in Appendix

A

6.11.5 Environmental Living Zone

The expansion area is on the adjoining Council land which is zoned Environmental Living. It is

considered that the zoning is not an accurate reflection of the existing land use which is

recreational in nature and essentially a buffer for the existing plant. While there is a dwelling on

the site it is the former caretaker’s cottage for the treatment plant and does not reflect a

historical residential use of the site. The site was formerly zoned Primary Industries and

Environmental Management.

Council officers have indicated that they will not alter the zoning as an urgent amendment, and

as the proposed works can be considered under the current zoning, without a need for an

amendment, the following assessment is provided against the current zoning – although many

of the standards are not relevant to the existing site characteristics. TasWater may seek to alter

the zoning to Utilities to reflect the use of the site via a separate application subsequent to

approval.


Use Table

Utilities are a Discretionary use within the Zone.

Use Standards


14.3.1 Non

Residential

Use, A1

Hours of operation must be within:

8.00 am to 6.00 pm Mondays to Fridays

inclusive;

9.00 am to 12.00 noon Saturdays;

nil Sundays and Public Holidays;

except for office and administrative tasks or

visitor accommodation..

Assessment required

against P1

The facility is a 24

operation with manned

operating hours (0700 to

1700) five to six days a

week.

14.3.1 Non

Residential

Use, P1

Hours of operation must not have an

unreasonable impact upon the residential

amenity through commercial vehicle

movements, noise or other emissions that

are unreasonable in their timing, duration or

extent.

Complies. Commercial

vehicle movements will be

undertaken during manned

operating hours and will be

accessed via the internal

road arrangements which

are some distance from the

nearest residents along

Tinderbox Road.

The proposal is also

assessed to be acceptable

in terms of noise as per

Scheme standards (see

Section 6.4 of this DPEMP)

and other emissions

including odour, dust and

exhaust (see section 6.1 of

this DPEMP).

14.3.1 Non

Residential

Use, A2

Noise emissions measured at the boundary

of the site must not exceed the following:

a) 55 dB(A) (LAeq) between the hours of

8.00 am to 6.00 pm;

b) 5dB(A) above the background (LA90)

level or 40dB(A) (LAeq), whichever is

the lower, between the hours of 6.00 pm

to 8.00 am;

c) 65dB(A) (LAmax) at any time.

Complies see noise

assessment findings at

Section 6.4 of this DPEMP.


Development Standards


14.4.1 Building Height,

A1

Building height must be no

more than:

7.5 m.

Complies. The maximum building

height is 7m

14.4.2 Setback, A1 Building setback from

frontage must be no less

than: 30 m.

Complies. The buildings in the

expansion area are located in

excess of 30m from the nearest

road, being Tinderbox Road.

14.4.2 Setback, A2 Building setback from side

and rear setbacks must be no

less than: 30m

Assessment required against P2

as the proposed buildings within

the expansion area are to be built

over the boundary with the

TasWater site. The facility is

however located in excess of 30m

from the boundaries with the

adjoining residential properties

within the Environmental Living

and General Residential Zones.

14.4.2 Setback, P2 Building setback from side

and rear boundaries must

maintain the desirable

characteristics of the

surrounding landscape and

protect the amenity of

adjoining lots, having regard

to all of the following:

a) the topography of the

site;

b) the size and shape of the

site;

c) the location of existing

buildings on the site;

d) the proposed colours and

external materials of the

building;

e) visual impact on skylines

and prominent ridgelines;

f) impact on native

vegetation;

g) be sufficient to prevent

unreasonable adverse

impacts on residential

Complies. The proposed building

setback is required for the

operational requirements of the

plant. The additional footprint is

located immediately adjacent to

the existing site and minimises

the impacts in terms of

excavations and vegetation

clearance required. Additional

revegetation is proposed as

illustrated in the landscaping plan

which will assist in screening the

plant as viewed from the adjoining

properties within the

Environmental Living Zone

(noting that the plant achieves the

necessary setback to these

properties). In addition the

proposed expansion area will be

cut into the slope of the site

minimising the visual appearance

of the building as viewed from the

adjoining residential properties.



amenity on adjoining lots

by:

i. overlooking and loss

of privacy;

ii. visual impact, when

viewed from

adjoining lots,

through building bulk

and massing.

14.4.3 Design, A1 The location of buildings and

works must comply with any

of the following:

a) be located within a

building area, if provided

on the title;

b) be an addition or

alteration to an existing

building;

c) be located on a site that

does not require the

clearing of native

vegetation and is not on a

skyline or ridgeline.

Assessment required against P1.

because:

The proposed works are not

located within a building area, as

none is provided on title

(subclause a)

The proposal includes new

buildings (subclause b); and

Requires native vegetation

clearance (subclause c).

However the site is not located on

a skyline or ridgeline consistent

with part of subclause c).

14.4.3 Design, P1 The location of buildings and

works must satisfy all of the

following:

a) be located in an area

requiring the clearing of

native vegetation only if:

i. there are no sites

clear of native

vegetation and clear

of other significant

site constraints such

as access difficulties

or excessive slope;

ii. the extent of clearing

is the minimum

necessary to provide

for buildings,

associated works and

associated bushfire

protection measures;

Complies

The vegetation clearance is

minimised to that reasonably

required to accommodate the

proposed expansion immediately

adjacent to the existing plant.

Landscaping of the site post

construction will involve planting

of native tree, shrub and grass

species. An indication of the area

to be landscaped is shown on

Figure 2-2 with more detailed

information provided in the design

drawings in Appendix A. Note that

where landscaping is proposed in

areas of existing vegetation, this

will be to supplement the existing

native vegetation on site and

existing native trees within the

landscaping zones will be

retained.



iii. the location of

clearing has the least

environmental

impact;

b) Not applicable

c) be consistent with any

Desired Future Character

Statements provided for

the area or, if no such

statements are provided,

have regard to the

landscape.

Subclause b) is not applicable.

There is no DFCS for the Zone

(subclause c).

14.4.3 Design, A2 Exterior building surfaces

must be coloured using

colours with a light

reflectance value not greater

than 40 percent.

Complies. The proposed new

buildings are likely to be

constructed from concrete and

can be conditioned to comply with

this standard.

14.4.3 Design, A3 The combined gross floor

area of buildings must be no

more than:

300 m2..

Complies. The combined GFA of

the building within the

Environmental Zone will be less

than 300m2.

14.4.3 Design, A4 Fill and excavation must

comply with all of the

following:

a) height of fill and depth of

excavation is no more

than 1 m from natural

ground level, except

where required for

building foundations;

b) extent is limited to the

area required for the

construction of buildings

and vehicular access.

Assessment is required against

P4, as the proposed cut exceeds

1m in height.

14.4.3 Design, P4 Fill and excavation must

satisfy all of the following:

a) there is no unreasonable

impact on natural values;

b) does not detract from the

landscape character of

the area;

Complies. The proposed

excavations are limited to that

necessary to accommodate the

proposed expansion area and will

minimise the visual impact of

these structures as viewed from

adjoining residential properties.

The works will be undertaken in

accordance with relevant



c) does not unreasonably

impact upon the privacy

of adjoining properties;

d) does not affect land

stability on the lot or

adjoining land.

standards to ensure that they do

not affect land stability.

Outbuildings Not applicable.


Values, A1

Development must be located

within a building area on a

plan of subdivision.

Assessment required against P1

as there is no building plan for

this site.


Values, P1

The application is

accompanied by an

environmental management

plan for the whole site, setting

out measures to be put in

place to protect flora and

fauna habitats, riparian areas,

any environmental values

identified as part of a site

analysis, and identify

measures to be used to

mitigate and offset adverse

environmental impacts.

Complies. The proposal is a level

2 activity. This DPEMP outlines

the impacts on the environmental

values, including measures to

mitigate and offset impacts. The

EPA conditions will be included

as part of the DA permit in

relation to the environmental

aspects of the proposal.

6.11.6 Codes

Bushfire Prone Areas Code

This land is located within a bushfire prone area being land that is within 100m of an area of

bushfire-prone vegetation equal to or greater than 1 hectare. This Code applies to:

a) development, on land that is located within, or partially within, a bushfire-prone area,

consisting of the subdivision of land; and

b) a use, on land that is located within, or partially within, a bushfire-prone area, that is a

vulnerable use or hazardous use.

The Code does not apply under subclause a) as no subdivision is proposed, and the proposal

does not comprise of a vulnerable use or hazardous use. TasWater has confirmed that

hazardous chemicals will not be stored on site in quantities exceeding that prescribed in the

Regulations.

Also, the EPA will assess the bushfire impacts and mitigation (see Section 6.16 of this DPEMP).

Potentially Contaminated Land Code

This Code applies to the development comprising of land that is, and adjoins an activity listed in

Table E2.2 of the Code as a potentially contaminating activity (existing treatment plant) and is

not identified as an exempt activity. The following Performance Criteria under Clause E2.6.2 of

the Interim Scheme apply to excavation of potentially contaminated sites:


Excavation does not adversely impact on health and the environment, having regard to:

a) an environmental site assessment that demonstrates there is no evidence the land is

contaminated; or

b) a plan to manage contamination and associated risk to human health and the environment

that includes:

i. an environmental site assessment;

ii. any specific remediation and protection measures required to be implemented before

excavation commences; and

iii. a statement that the excavation does not adversely impact on human health or the

environment.

As detailed in Section 6.5, the vast majority of all excavated material is from areas outside of

and up gradient from the existing STP site. However, a small area along the western side of the

existing STP boundary (up gradient of the existing plant) will be excavated and some ground

disturbance will occur at the new loading/unloading facility. As the existing STP is a “potentially

contaminating activity” risk of contaminated soil being encountered needs to be considered. To

manage this risk a targeted inspection of areas proposed for subsurface excavations will be

undertaken by a Certified Practitioner (Site Contamination Practitioners Australia) prior to

construction. This inspection will review available history for the site and delineate which areas

proposed for excavation would be considered lower risk and therefore not require classification

and which areas are higher risk and therefore need soil testing and classification (for reuse or

disposal). In accordance with this assessment, areas of higher contamination risk (within the

excavation footprint) will be subject to soil testing and classification. Any resulting material from

these areas will be handled, transported and disposed of in accordance with relevant guidelines

and utilising licenced practitioners.

Landslide Code

The site is identified as being partially subject to a landslide hazard area overlay (low and

medium) as illustrated in Figure 6-14 comprising an area with slope of between 11-20 degrees.

Buildings are exempt from the Code within the Low Landslide Hazard Area under Clause E3.4c)

of the Scheme. The proposed buildings are also exempt pursuant to Clause E3.4 e) of the

Scheme within the Medium Landslide Hazard Area as the gross floor area within the hazard

area is no more than 200 m2.


Figure 6-14 Landslide Hazard Area Overlay & Development Site (Low

Landslide Hazard Area on the Left and Medium Hazard Landslide

Area on the Right)

Road and Railway Assets Code

This Code applies as the proposed development will intensify the use of the existing vehicular

access via Tinderbox Road.


E5.5.1 Existing road

accesses and junctions, A3

The annual average daily

traffic (AADT) of vehicle

movements, to and from a

site, using an existing access

or junction, in an area

subject to a speed limit of

60km/h or less, must not

increase by more than 20%

or 40 vehicle movements per

day, whichever is the

greater.

Complies. As outlined in

Section 6.6.3 of the DPEMP

the AADT vehicle

movements to and from the

site using the existing access

will not be more than 40

vehicle movements per day.

E5.6.2 Road accesses and

junctions, A2

No more than one access

providing both entry and exit,

or two accesses providing

separate entry and exit, to

roads in an area subject to a

speed limit of 60km/h or less.

Complies. No new accesses

are proposed.

Parking and Access Code

This Code applies to all use and development. There is however no car, motorcycle or bicycle

parking requirements for a Utilities.



E6.7.1 Number of

Vehicular Accesses A1

The number of vehicle access

points provided for each road

frontage must be no more than 1

or the existing number of vehicle

access points, whichever is the

greater.

Complies. No Change

E6.7.4 On-Site Turning,

A1

On-site turning must be provided

to enable vehicles to exit a site in

a forward direction, except where

the access complies with any of

the following

a) it serves no more than two

dwelling units;

Complies. Access and

Parking will be upgraded

consistent with this standard.

Stormwater Management Code

The proposal will involve the upgrade of existing parking and internal road network.


E7.7.1 Stormwater

Drainage and Disposal,

A1

Stormwater from new impervious

surfaces must be disposed of by

gravity to public stormwater

infrastructure.


P1 as the site is not

connected to Council’s

stormwater system.

E7.7.1 Stormwater


P1

Stormwater from new impervious

surfaces must be managed by

any of the following:

a) disposed of on-site with

soakage devices having

regard to the suitability of the

site, the system design and

water sensitive urban design

principles

b) collected for re-use on the

site;

c) disposed of to public

stormwater infrastructure via

a pump system which is

designed, maintained and

managed to minimise the risk

of failure to the satisfaction of

the Council.

As outlined in Section 2.5.8 of

the DPEMP, the site has

some existing stormwater

collection systems, which

discharge to the onsite creeks

and over the cliffs to the

marine environment.

The intention of the new

design is to minimise

collection and concentration

of stormwater and allow

natural flows to occur

wherever possible. Diversion

drains will be installed around

the upslope edge of new

hardstand areas to direct

clean stormwater away from

the site. Any new roofed

structures will be sloped to

direct rainwater onto adjacent

hardstand areas. New

hardstand areas will be

sloped to direct stormwater

away from the site and into



constructed grass swales

before diffuse discharge into

the surrounding environment.

Some of this new stormwater

may report to the existing

collection system by way of

natural ground flows (e.g.

from the new road access).

Detailed drainage designs will

be prepared as part of the

detailed design process.

Contaminated drainage and

stormwater will be collected in

bunded areas and pumped to

the inlet of the treatment plant

for treatment.

Construction surface water

management is addressed

under Section 6.2.3

E7.7.1 Stormwater

Drainage and Disposal

A2

A stormwater system for a new

development must incorporate

water sensitive urban design

principles R1 for the treatment

and disposal of stormwater if any

of the following apply:

a) the size of new impervious

area is more than 600 m2;

b) new car parking is provided

for more than 6 cars;

c) a subdivision is for more

than 5 lots.


P2 as the size of new

impervious area exceeds

600m2 primarily comprising

the new internal road.

However only 4 new car

parking spaces are provided,

and no subdivision is

proposed.

E7.7.1 Stormwater


P2

A stormwater system for a new

development must incorporate a

stormwater drainage system of a

size and design sufficient to

achieve the stormwater quality

and quantity targets in

accordance with the State

Stormwater Strategy 2010, as

detailed in Table E7.1 unless it is

not feasible to do so.

During the detailed design

phase a detailed stormwater

design will be prepared for all

new hardstand and roofed

areas. This detailed design

will comply with the

requirements of the State

Stormwater Strategy 2010 for

new developments (unless it

is not feasible to do so).


Attenuation Code

The site is subject to a 300 m buffer area over the current plant. The proposal is exempt from

the Code pursuant to Clause 9.4.1a) activities requiring assessment under the Environmental

Management and Pollution Control Act 1994 by the Board of the Tasmanian Environment

Protection Authority.

Biodiversity Code

The site is subject to a Biodiversity Conservation Area. The proposal is exempt from the Code

pursuant to Clause 10.4.1a) clearance and conversion or disturbance associated with a Level 2

Activity under the Environmental Management and Pollution Control Act 1994;.

Waterway and Coastal Protection Code

The site is within a Waterway and Coastal Protection Area. The proposal is exempt from the

Code pursuant to Clause 11.4.1a) development associated with a Level 2 Activity under the

Environmental Management and Pollution Control Act 1994;

Historic Heritage Code

The Code applies as the site contains a heritage listed place: Blackmans Bay Geoheritage Site

& Blackmans Bay Geological Monument; Fossil Cove Drive, Blackmans Bay – Ref No 1. As

outlined in Section 6.10 of this DPEMP the proposal no works are proposed to the site or within

the immediate vicinity. Accordingly, no impacts are anticipated from the proposed works.

Coastal Erosion Hazard Code

This Code applies as the site is within a Coastal Hazard Area as shown on the planning scheme

maps (Figure 6 9). Accordingly, buildings and works must satisfy all of the following:

a) not increase the level of risk to the life of the users of the site or of hazard for

adjoining or nearby properties or public infrastructure

b) erosion risk arising from wave run-up, including impact and material suitability, may

be mitigated to an acceptable level through structural or design methods used to

avoid damage to, or loss of, buildings or works

c) erosion risk is mitigated to an acceptable level through measures to modify the

hazard where these measures are designed and certified by an engineer with

suitable experience in coastal, civil and/or hydraulic engineering

d) need for future remediation works is minimised;

e) health and safety of people is not placed at risk;

f) important natural features are adequately protected;

g) public foreshore access is not obstructed where the managing public authority

requires it to continue to exist;

h) access to the site will not be lost or substantially compromised by expected future

erosion whether on the proposed site or off-site;

i) provision of a developer contribution for required mitigation works consistent with

any adopted Council Policy, prior to commencement of works;

The proposal complies with the above criteria as it is located within the footprint of the existing

plant, will be undertaken in accordance with a construction and environmental management

plan pursuant to subclauses e) and f) and will maintain public foreshore access which are

located outside of the development footprint.


Figure 6-15 Coastal Erosion Hazard Overlay & Development Site

Signs Code

A sign on the new access gate measuring approximately 1200 by 800 mm stating STP Site and

no public access is proposed. There will also be temporary construction signage. The signage

will not be illuminated. The proposed signage is defined as a building site sign and wall sign

under the Code and is exempt under Table 17.1 of the Code.


6.11.7 Effects on Local Land Uses

The Project Site is currently used for recreational walking and will continue to be available to the

public during construction and once the new STP is operational.

The Suncoast Headlands Track traverses the STP site and will be temporarily relocated during

construction and then reinstated slightly west of its current alignment post construction (refer

Figure 2-6). New landscaping will be provided along the western side of the upgraded STP to

provide visual screening of the new STP from the new access track and nearby houses. As the

track will remain open to the public during both construction and operational phases, potential

impacts to this recreational feature are considered to be negligible.

Immediately south of the existing STP site and partially within the new Site is a dog exercise

area. This area will not be impacted in any way by construction activities and will remain

accessible via the current vehicular access and remain connected to the Suncoast Headlands

Track as noted above. There may be minor noise and odour impacts affecting the area but

these will be largely unchanged (if not slightly improved) than current conditions with the

existing STP. As such impacts to this recreational feature are considered to be negligible.

There is a scout hall west of the STP Site, which will not be impacted in any way by the

development.

Residential properties in the areas surrounding the site will be subject to minor changes in

odour and noise and assessed under Sections 6.1 and 6.4 respectively.

There are no tourist activities, camping areas, industries or commercial activities within or

immediately adjacent to the Site which would be impacted by the development. There is no

agricultural use of the Site and no impacts to agriculture are expected.


6.12 Visual Impacts


The existing Blackmans Bay STP has been in operation for over 30 years. It pre-dates many of

the adjacent residential properties.

The Project Site is sloped from west to east and contains existing open areas and trees,

providing some visual screening of the proposed infrastructure for surrounding residents.


Tasmania’s landscape is an important consideration in any land use planning exercise because

of its cultural, ecological and/or scenic qualities. The proposed Project Footprint is directly

adjacent to and within the existing Blackmans Bay STP.

The key legislative documents addressing visual impacts in the area are the:

Kingborough Interim Planning Scheme 2015

The objectives of the RMPS as set out in Schedule 1 of LUPAA

These two documents deal with the broader issues of maintaining the environmental and social

values of the area (of which the visual landscape is a relevant factor).


The proposed Project involves retrofitting existing infrastructure as well as construction of new

infrastructure. The most visible new elements at the site will be the two IDEA-SBR tanks. The

tanks will be constructed west of the existing STP within an area of significant ‘cut’. By cutting

into the natural sloped bank to accommodate the new tanks, much of the potential visual impact

is mitigated.

Preliminary visual analysis was undertaken by Lester Frank as part of the Project’s planning

phase. This involved early stage visual representations taken from a series of potential vantage

points around the Project including properties on Suncoast Drive and Tinderbox Road,

immediately west of the Project. These representations provide an indication of the comparative

visual impact of the existing STP and proposed Project, but do not include any existing trees or

those proposed to be planted as part of the Project, so significantly over-represent the overall

visual intrusion.

Review of the images produced shows the proposed Project is just visible from the property at

90 Tinderbox Road (viewing at approx. 1.8 m from existing floor level) in the absence of any

trees. From houses on Suncoast Drive both the existing STP and the Project are visible (in the

absence of any trees), each showing a similar visual footprint, with the Project further up the

slope, but otherwise similar in scale. As noted above these images do not consider the existing

trees on site. As illustrated on the Project site plans (Figure 2-1) there are a large number of

existing trees already on site, sitting in the line of sight between the Project and existing

residential properties. In addition, TasWater propose a new vegetation screen (refer Figure 2-1)

along the entire western boundary of the Project Footprint, providing considerable visual

screening once established (noting that it will take some years for the vegetation to mature).

This vegetation screen is in addition to rehabilitation of all temporarily disturbed areas (i.e.

construction compound) to their original condition, immediately post construction. The Project

will also employ paints and building finishes that blend into the surrounding environment to

minimise visibility.


With the existing and proposed tree screen in place, the overall visibility of the Project from

existing residential properties will be relatively low and largely similar in overall context to the

existing STP.

The Project is not expected to be visible from local public roads, namely Tinderbox Road and

Suncoast Drive, due to topography and existing visual obstructions (houses and trees).

The existing STP is visible to recreational users of the surrounding open space (e.g. walkers).

The Project will be similarly visible, with the exception that proposed vegetation screening will

assist over time with screening of the Project from the Suncoast Headlands Track.

The images from the preliminary visual analysis are available on request.


Along with proactive community consultation leading up to, and during, construction the

TasWater online complaints register will be the main method of recording visual impact

complaints arising from the Project.

Commitment 31 A vegetation screen will be planted along the western

boundary of the Project Footprint as outlined on the Figures in this

DPEMP.


6.13 Socio-economic Issues

The proposed Project involves upgrade of the existing Blackmans Bay STP, providing additional

sewage capacity both for the immediate region, and potentially for the Margate, Electrona and

Howden catchments if the amalgamation of these STP catchment to the Project occurs.

Overall the Project is expected to benefit Kingborough residents, both now and for future

generations, by accommodating regional growth in the area and improving the overall quality of

water discharged to the River Derwent, along with improved odour and noise for residents.

It requires a large capital investment (approximately in the vicinity of $30-40 million) in order to

facilitate long term reliable sewage treatment within the Kingborough LGA and accommodate

future development within the region.

Salient social and economic features of the development include:

Capital investment – in the vicinity of $30 to $40 million.

Annual expenditure – estimated to be approximately $1 million/yr (excluding interest and

capital repayments) and will be obtained via existing rates.

Design horizon – Capacity to treat sewage from existing developments and projected future

growth in the region up to ~2040; catering for the current Blackmans Bay STP catchment,

as well as potentially the Margate, Electrona and Howden STP catchments to

accommodate their potential future amalgamation into the Blackmans Bay STP.

Employment Opportunities:

– Approximately two year construction period followed by a six-month commissioning

period (with some early commissioning work undertaken during construction) during

which time local employment opportunities exist in design, construction, materials

supply and commissioning.

– Once operational the Project will accommodate three local operational staff plus

additional resources during maintenance periods. This is relatively unchanged from

existing conditions.

Materials Supply – Where possible local materials will be sourced for construction, with all

gravel and concrete to be sourced from local quarries and suppliers.

Impacts on local and regional economies – the most significant economic impact from the

Project will be increased reliability of sewage treatment in the region and the opportunity for

future development, which would otherwise be constrained by an ageing and ‘at capacity’

treatment plant.

Impacts on local social and community amenity – The area surrounding the existing STP is

used in a recreational capacity, predominantly by walkers and forms part of the Suncoast

Headlands Track. The proposed upgrade will include a temporary diversion of the access

track around the Construction Compound. Once operational the access track will be

reinstated in a similar alignment to its current position and be improved by proposed

landscaping (refer Figure 2-6). The area surrounding the Project Footprint will continue to

be made available for public recreation.

The Project also facilitates ongoing development of local community assets by providing

reliable sewage treatment with capacity for regional growth.

Impacts on land values – The upgraded STP is not expected to detract from local land

values immediately adjacent to the Project Site as it already contains an operating STP and

although the Project Footprint increases the current STP footprint, amenity impacts such as

odour will be better controlled through more contemporary plant design (refer Section 6.1).


By upgrading the existing STP the Project also allows for ongoing development within the

region, therefore supporting future growth and land values.

Impacts on local industries – The Project will allow for future growth in local industries by

accommodating future wastewater generation, which would otherwise be limited by the

capacity of the existing STP.

The local amenity issues associated with the Project (noise, odour, slight increase in

footprint) are highly localised and ameliorated by the fact there is already an operating STP

within the Project Site and through controls stipulated in the relevant sections (e.g. odour

control facility, noise mitigations, landscaping etc.).

Overall the Project is expected to have a positive socio-economic effect by increasing capacity

and reliability of wastewater treatment, thereby facilitating regional growth.


6.14 Health and Safety Issues

6.14.1 Legislative, Policy and Performance Requirements

During construction and operation, the Project will demonstrate compliance with:

Workplace Health and Safety Act 2012 and associated Workplace Health and Safety

Regulations 2012;

Relevant Australian Standards (including AS/NZS 4804:2001 Occupational Health and

Safety Management Systems);

Australian Code for the Transport of Dangerous Goods by Road and Rail;

Dangerous Substances (Safe Handling) Act 2005 and associated regulations;

Australian Dangerous Goods Code (7th edition); and

Fair Work Act 2009.

6.14.2 Construction Impacts, Management, and Mitigation

For the construction phase a site specific Health and Safety Management Plan (HSMP) will be

developed prior to construction works.

The construction stage of the proposed Project will be undertaken by construction contractors. It

will be a requirement of the engagement process that the successful contractors will undertake

works in accordance with the Tasmanian Workplace Health and Safety Act 1995 and

Regulations 1998 and AS 4804 Occupational Health and Safety Management Systems.

Additionally, Contractors will be required to:

Prepare and implement a HSMP specific to their role in the proposed Project (this may be

required to be submitted to the Workplace Safety Division) this will include;

– Site control, access, inductions, training and reporting protocols to ensure all

contractors, staff and visitors are registered, inducted, managed on site and recorded

as leaving when vacating the site;

– Road traffic management (including facilitating safe pedestrian crossing of Treatment

Plant Road during construction);

– Speed limit restrictions in required working areas;

– Noise and dust management;

– Provision of personal protective equipment (PPE) for workers and any site visitors;

– Fire prevention and management;

– Specified working arrangements in accordance with the Fair Work Act 2009;

– Proper handling of waste materials;

– Hazardous substance handling and storage, with management of emergency spill

situations (to be managed and mitigated in accordance with those measures outlined

in Section 6.6).

– Fencing off of potentially dangerous areas to the public, in particular the Construction

Compound and main Project Footprint site;

– Use of appropriate signage at all necessary locations in accordance with appropriate

standards and regulations (site entrances, fenced off areas etc.);

– Provide notification of incidents to the relevant competent authority as soon as

reasonably practicable after the occurrence of an accident/incident; and


– All workers/contractors to be inducted in site specific health and safety aspects prior to

commencing work.

6.14.3 Operational Impacts, Management, and Mitigation

The existing Blackmans Bay STP operates under TasWater’s Work Health and Safety Policy.

The Project will continue to operate under this Policy as well as all relevant legislation.

The Project will be fully fenced with cyclone fencing and two locked security gates. Only

authorised personnel and inducted visitors will be granted access to the site. All chemicals and

hazardous substances will be stored in locked compounds within the dewatering building or the

bulk chemicals store.

A site specific Operations and Maintenance Manual will be prepared for the Project and will

address Health and Safety issues including:

Identification of safety hazards and controls;

Procedures for operational control of potentially hazardous equipment;

Roles and responsibilities for specific management representatives who have a defined role

for occupational health and safety management of the facility;

Development of a competency, training and awareness program for employees associated

with the facility;

Development of an Emergency Response Plan; and

Development of an incident management system.

All workers/contractors will be inducted in site specific health and safety aspects prior to

commencing work.


Health and safety audits will be undertaken on at least a monthly basis with results recorded

and provided to the relevant regulatory authority as required.

Incidents will be managed in accordance with WorkSafe Tasmania requirements, including

reporting of incidents to the required agencies.

If safety issues are identified during construction and operation, works in the area(s) of concern

will be halted until a safe alternative can be developed and implemented.

Commitment 32 A Health and Safety Management Plan (HSMP) will be

prepared for the construction phase and incorporated into the Site

CEMP.

Commitment 33 Health and safety management will be included in the

site specific Operations and Maintenance Manual.


6.15 Hazard Analysis and Risk Assessment

6.15.1 Hazard Identification and Risk Assessment Methodology

A preliminary hazard identification and risk assessment was undertaken for the Project based

on the processes outlined in Australian/New Zealand Standard AS/NZS 4360:1999 Risk

Management.

The hazard identification process involved the following:

Identifying the potential major environmental hazards associated with all aspects of the

Project;

Identifying the potential environmentally detrimental outcomes that could result for each of

these hazards; and

Generating a list of the major hazards and the potential environmental outcomes to be risk

assessed.

Once the key hazards and potential environmental outcomes had been identified, they were

firstly evaluated without considering mitigation strategies and then with strategies in place. In

most cases there was a decrease in risk due to the proposed management and mitigation

measures. Results from the risk assessment are shown in Table 6-21. The likelihood,

consequence and risk ranking criteria are outlined below.

Measures to manage and mitigate against the risks identified in this assessment are included in

the relevant sections of the DPEMP.

Likelihood

For the likelihood of an event occurring, the ranking and associated criteria are presented in

Table 6-17. The likelihood of occurrence assessment takes into account built-in design

functions.

Table 6-17 Likelihood Ranking with Design Control

Ranking Descriptor Detail Description

A Almost Certain Is expected to occur

B Likely Will probably occur

C Possible May occur at some time

D Unlikely Could occur at some time

E Rare May occur only in exceptional circumstances

Consequence

Consequences are based on severity of impacts and recovery times of ‘environmental factors’

which include ecological, landscape and socioeconomic receptors. The ranking and associated

criteria are presented in Table 6-18.


Table 6-18 Environmental Consequence Ranking

Ranking Descriptor Detail Description

1 Insignificant No significant impacts to sensitive environmental factor(s)

2 Minor Short term localised impacts to environmental factor(s), recovery

measured in weeks to months.

3 Moderate Detectable impacts on environmental factor(s) at a local level,

recovery measured in months to years.

4 Major Significant impacts on environmental factor(s) at a regional

scale, recovery measured in years to decades

5 Catastrophic Large scale detrimental effect on environmental factors (s), long

term recovery over decades.

Risk Ranking

Environmental risk is determined using a matrix that incorporates the likelihood and

consequence of the aspect being assessed. The matrix used in this assessment is presented in

Table 6-19, with the definition of each risk colour presented in Table 6-20.

Table 6-19 Risk Matrix

Likelihood

Consequences

1

(Insignificant)

2

(Minor)

3

(Moderate)

4

(Major)

5

(Catastrophic)

A (Almost Certain)

B (Likely)

C (Moderate)

D (Unlikely)

E (Rare)

Table 6-20 Risk Rating Key for Proponent Action and Ultimate

Acceptability

Risk Rank Description

Tolerable Risk reduction not required

Risk Reduction Required Risk reduction measures need to be implemented so that risk is

as low as reasonably practicable

Unacceptable Risk is too great for activity to proceed


6.15.2 Environmental Hazard Identification and Risk Assessment Outcomes

The environmental hazard identification process and risk assessment procedure has been combined into a single table that assesses all potential major

environmental events in Table 6-21.

Table 6-21 Environmental Hazard Identification and Risk Assessment Outcomes

Major

Environmental

Hazard Event

Potential Environmental Impacts

Risk Ranking

Pre-Management

Risk Mitigation Action

(Prevention or Contingency)

Risk Ranking

Post-Management

Lik

elih

ood

Conseq

uence

Rankin

g

Lik

elih

ood

Conseq

uence

Rankin

g

Clearance

outside of

defined

footprint

Impacts to vegetation and fauna

habitat

C 1 Development footprint delineated on all CEMP mapping,

on-site marking of key sensitive areas, induction and tool

box training for all site staff and visitors and routine audits

of construction footprints.

D 1

Fuel or

chemical spill

Ecological impact on aquatic

flora and fauna in surface

drainage lines and downstream

environment

Contamination of land.

D 3 Fuels and chemicals to be stored in designated roofed,

bunded and secure storage facilities during constriction

(Construction Compound) and operation (within

dewatering building and bulk chemicals store).

Refuelling of equipment during construction to be

undertaken in bunded areas.

Fuel and chemical spill clean-up procedures to be

included in CEMP and OMP documents.

Staff to be trained in spill containment.

D 2


Major

Environmental

Hazard Event


Risk Ranking

Pre-Management



Risk Ranking

Post-Management

Lik

elih

ood

Conseq

uence

Rankin

g

Lik

elih

ood

Conseq

uence

Rankin

g

Burst

treatment

pipelines or

leaking

infrastructure.

Ecological impact on aquatic

flora and fauna in surface

drainage lines and downstream

environment.

Public health and amenity risks.

E 3 Sewage Treatment Plant Contingency Management

Manual developed for the Project with Site Response

Procedures.

Regular infrastructure maintenance, including regular

pipeline flange replacement.

Major

introduction of

weeds or

pathogens

during

construction

phase.

Impacts to existing flora and

fauna values in area.

C 2 Weed and hygiene management and mitigation measures

included in CEMP (e.g. wash-down procedures, staff

training, weed control prior to construction).

D 2

Release of

poorly treated

effluent

through

mechanical

failure or

power outage.

Ecological impacts and potential

human health risks in the

receiving environment

D 3 Redundancy in plant design and emergency generator for

power failures.

Regular maintenance and audits of control systems and

infrastructure by operational staff.

Sewage Treatment Plant Contingency Management

Manual developed for the Project with Site Response

Procedures

Operational staff member on standby when STP is not

manned, with alarm system to automatically notify

standby staff in case of system failure.

D 2


Major

Environmental

Hazard Event


Risk Ranking

Pre-Management



Risk Ranking

Post-Management

Lik

elih

ood

Conseq

uence

Rankin

g

Lik

elih

ood

Conseq

uence

Rankin

g

Release of

substandard

treated effluent

during storm

or large flow

events

Ecological impacts and potential

human health risks in the

receiving environment

A 2 Operational staff onsite or standby staff to alter treatment

methodology to storm mode.

Design capacity of the plant to cater for significantly

increased flows during storm events.

A 1

Large fugitive

odour release

Impacts to amenity of local

residents

C 1 Regular maintenance and audits of odour control systems

and infrastructure by operational staff.

Maintain complaints register and action any complaints

immediately.

D 1

Fire resulting

from

construction or

operation

becomes out

of control or

external fire

Terrestrial habitat destruction

Safety of site personnel and

surrounding residents

D 4 Fire response Site Response Procedure included in

Sewage Treatment Plant Contingency Management

Manual.

Operational and construction staff briefed in emergency

management.

Firefighting equipment on site with staff trained in fire

response.

Vegetation maintenance in proximity to STP.

Bushfire emergency plan will be included in healthy and

safety documentation, including muster points and

firefighting equipment locations.

E 4


6.15.3 Hazard Analysis Conclusions

The hazard analysis identified fire as the most significant risk to the environment as a result of

the Project. This situation is unchanged from current conditions. Preventative measures and

response procedures are deemed adequate to reduce the risk to as low as reasonably practical.


6.16 Fire Risk


The Project Site contains existing trees and is bounded to the west and south by significant

tracts of native vegetation. The closest responding fire brigade to this location would be

Blackmans Bay volunteer brigade.


The construction and operation of the Project must fulfil the requirements of the following

legislative and policy requirements in relation to fire risk:

Fire Services Act 1979

Workplace Health and Safety Act 1995

Buildings and associated fire controls must be designed in accordance with the Building Code

of Australia.


Project Potential Fire Sources

There are a number of potential anthropogenic sources of fire within the Project area both

during construction and operation, including:

Use of vehicle and machinery around dry vegetation (e.g. exhaust system contact);

Hot work around dry vegetation (e.g. welding, electrical work);

Discarded cigarettes;

Electrical faults in facilities (e.g. process plant, administration building, pump stations); and

Storage and use of chemicals and flammable hydrocarbons around site.

These risks (with the exception of elevated risk during the construction phase) are largely

similar to risks from the existing STP (albeit slightly lowered due to decommissioning of the

chlorine gas system).

As well as fires potentially originating from within the Project site, there are a number of external

sources of fire including lighting strikes, arson and burn-offs.

Potential Effects and Management

Any fire originating within or external to the site has the potential to impact on infrastructure,

environmental values and possibly even endanger lives. In addition, any fire event puts

pressure on the State Emergency Services.

The proposed Project poses a small increase in fire risk during construction (new ignition

sources) and a slightly decreased risk once operational due to the decommissioning of the

chlorine gas system which reduces site wide ignition sources. The risk to the infrastructure from

bushfire remains similar.

To manage construction phase fire risk:

All vehicles and machinery will be kept in good working order to minimise the potential for

fires on site;

Any fuels required during the construction phase will be limited in quantity and will be

stored in appropriately bunded facilities;


Appropriate firefighting equipment will be kept on site during the construction phase and

site staff trained in emergency procedures and use of firefighting equipment; and

Fire risk will be included in the CEMP with emergency protocols clearly defined.

TasWater already has an established Fire Management Plan (covering the existing STP) to

which will be applied to the Project. Site specific measures will include:

Provision of adequate fire hydrants and water for firefighting (in accordance with the

Building Code);

All chemicals and fuels will be correctly stored in purpose-built storage facilities with

appropriate signage and extinguishers present, away from any potential ignition sources;

Site specific fire management will be documented including muster points and emergency

contact details;

Staff and contractor inductions will include a fire safety element, outlining subjects such as

designated smoking areas, site evacuation protocols and muster points; and

Regular fire drills will be undertaken at the site (at least once annually).


Monitoring of fire preparedness will be undertaken through regular annual audits of firefighting

equipment (including water storage and hydrant systems) and through random drill events.

If fire events do occur at the site, actions will be reviewed post-event and changes made to

management and mitigation measures in the original plans where appropriate.


6.17 Infrastructure and off-site Ancillary Facilities

The proposed Project does not involve any changes or upgrades to offsite infrastructure. There

may be some minor modifications to overhead power lines within the Project Site but there will

be no changes to external roads, power lines, pipelines or other infrastructure.

The proposed STP upgrade will involve increased use of existing road networks during the

construction period, with almost no change to operational phase traffic from existing conditions.

Traffic and potential impacts to the regional road network are addressed under Section 6.20 and

are determined to be minimal.

This application relates only to the Project within the Project Site (The Boundaries of the Land)

as delineated in Figure 2-1. The associated decommissioning of Electrona, Margate and

Howden STPs and the piping of sewage from these sites to the newly upgraded Blackmans Bay

STP is excluded from this Project. The Blackmans Bay STP has been sized to accommodate

the potential amalgamation but is not contingent upon it as the current STP requires upgrade to

cater for existing and projected loads from the Blackmans Bay catchment regardless.

In conclusion, there are no measurable impacts to offsite infrastructure anticipated as a result of

the Project.


6.18 Environmental Management Systems

6.18.1 TasWater’s Environmental Management

TasWater operates under a companywide Environmental Policy which sets out the overall

company objectives with respect to environmental management. The Environmental Policy is

approved by the TasWater Board, and the TasWater CEO is responsible for ensuring

companywide compliance with the policy. All staff are required to comply with the spirit and

letter of the policy and its associated procedures. The Policy also requires staff to undertake

training as required, to stay current with the objectives of the Policy.

TasWater also has an Environment and Public Health Committee, whose role is to assist the

Board in fulfilling its responsibilities in relation to environmental and public health management,

performance and compliance. The Committee has a publically available charter and has a role

in assessing emerging environmental and public health issues, overseeing strategic direction,

reviewing the efficacy of the policy and monitoring progress and compliance.

Within this overarching environmental framework this particular project will have a set of

environmental responsibilities during construction and once operational as outlined below.

6.18.2 Construction Environmental Management

Prior to commencement of construction of the Project a CEMP will be prepared which

addresses environmental management during construction and will capture all relevant

management measures and commitments from this DPEMP and associated permits. Based on

the assessment in this DPEMP, the CEMP will provide a tabular summary of the environmental

aspects and impacts of the construction work.

The CEMP will encompass the relevant issues identified in this DPEMP and include, but not be

limited to the following key elements:

Site Management – A system will be developed to manage entry and exit from the site to

ensure that impacts from works do not occur outside the Project area. This includes site

fencing arrangements (as set out in this DPEMP), public access arrangements and fencing

of sensitive vegetation (as set out in this DPEMP).

Erosion Control – The CEMP will include a Soil and Water Management Plan (SWMP) in

accordance with relevant EPA guidance documents, which ensures no significant erosion

or runoff as a result of construction works.

Dangerous Goods – A system will be established for managing the delivery, storage, use

and disposal of all dangerous goods required for construction.

Air Quality – A visual monitoring program to identify unacceptable levels of dust during

construction will be implemented. The CEMP will also outline mitigation measures to be

employed in the event that dust levels are identified as elevated. Such measures may

include the use of water carts, or ceasing work in certain weather conditions.

Noise Management – The CEMP will outline measures for notifying the closest local

residents of noise generating activities, as well as stipulating clear hours of operation (in

accordance with this DPEMP). The CEMP will also outline any necessary controls to

ensure noise levels at the construction site are in accordance with workplace standards,

including measures such as the use of hearing protection if required.

Traffic Management – The CEMP will outline clear procedures for traffic management,

including signage, timing, safety and notification of local area users.

Health and Safety – A system will be developed to manage health and safety on site during

the works.


Waste Management – Procedures for waste management during construction, including the

designation of specific lay-down areas (within the Construction Compound) and transport

and disposal procedures will be developed.

Weed and Disease Control – The CEMP will develop and implement procedures for wash-

down and (if required) disinfection of equipment before entering the site in order to avoid

the introduction of weeds, pest and diseases. This section will also outline weed control

measures to be implemented before and after construction to ensure the works do not

increase the infestation of weeds presently located within the Project Site.

Incident Management – An incident reporting and follow up system will be established in

order to respond effectively and efficiently in the event of an environmental incident.

The CEMP will also set out a program of training. All site staff will undergo a basic

environmental induction to explain the Project Site and Footprint, the Project itself, sensitive

features, risks and impacts, their roles/responsibilities, spill and clean up procedures, reporting

protocols, specific site procedures and environmental issues and features. Additional specific

training may be given to site staff on ad hoc issues identified.

TasWater will appoint a Project Manager for the construction phase. During construction the

Contractor’s Site Manager will be responsible for implementation of the CEMP. Regular

meetings will be held during construction between the TasWater Project Manager and the

Contractors Site Manager to ensure compliance and adherence to the CEMP.

Ultimately, the TasWater CEO will be responsible for ensuring environmental compliance of the

Project.

6.18.3 Operational Environmental Management

Prior to commencement of the operational phase a site specific Operational and Maintenance

(O&M) Manual will be prepared for the upgraded plant. This is a standard TasWater document,

modified to suit the specifics of each STP site.

The O&M Manual will incorporate all salient information from this DPEMP, the commitments in

this DPEMP and resulting permits.

Training will be provided to all site workers with respect to the content of the O&M Manual in

accordance with TasWater’s established training regimes.

The Site Operator will be responsible for day-to-day implementation of the O&M Manual. The

Site Operator reports to the Area Coordinator then to the Manager, Department Manager and

then General Manager. Ultimately, the TasWater CEO will be responsible for ensuring

environmental compliance of the Project.


Monthly audits of compliance against the CEMP will be undertaken during the construction

phase.

The O&M Manual will be reviewed every 5 years once established.

Commitment 34 A site specific Operations and Maintenance Manual will

be prepared and reviewed every five years once established.


6.19 Cumulative and Interactive Impacts

The key discharges from the Project which have the potential for cumulative consideration with

other existing and approved developments in the region are air impacts (odour), noise impacts,

traffic, tree clearance and treated effluent discharge. Each of these matters has been

considered in detail in the relevant sections of this DPEMP. In each of those assessments the

potential for cumulative impacts with existing (ambient) conditions and developments is

provided9. There are no known pending developments in the region that would affect those

assessments.

The most critical cumulative impact to consider with respect to the Project is the discharge of

treated effluent into the marine environment. As outlined in Section 6.8, the Project will

discharge increased flows with significantly improved effluent quality for most parameters

compared to the current Blackmans Bay STP. The Project may also potentially facilitate the

amalgamation of Margate, Electrona and Howden STPs into Blackmans Bay thereby removing

treated effluent from the lower energy North West Bay and transferring it (via the Project effluent

discharge pipeline) into the higher energy Derwent Estuary. The assessment of impact to the

marine environment associated with the Project is provided in Section 6.8 and already takes into

consideration the existing marine environment and its known inputs through the assessment of

available ambient data.

In summary, there are cumulative impacts associated with odour, noise, tree clearance, traffic

and treated effluent discharge but all of these matters have been considered as part of the

detailed assessments in the relevant sections (by including background conditions in each

assessment) and there are no additional cumulative impacts anticipated.

9 E.g. noise assessments consider the background noise environment as part of the modelling, receiving waters

assessments consider the existing conditions in the receiving environment as part of the modelling exercise etc.


6.20 Traffic Impacts


The existing Blackmans Bay STP site is accessed from Treatment Plant Road, which is a

subsidiary road of Tinderbox Road East. Under routine operations, the current daily traffic to the

site includes approximately five cars and one to two trucks visiting the site per day.

The local road network can be seen on Figure 2-1.


Construction

During construction of the Project local traffic is expected to increase and will be composed of

staff vehicles, trucks, utes and vans delivering building materials and equipment. During peak

periods in the construction phase there will be approximately 6-12 trucks visiting the site each

day and 20 trade vehicles and 20 cars or other vehicles. Although the construction phase is up

to two years in duration, peak traffic volumes will only be experienced for very short periods

during this time, when active phases of construction are occurring (e.g. bulk earthworks and

building construction). During the remaining time only small volumes of vehicles will be

accessing the site each day.

During periods of intense vehicular activity to the site the increased traffic volumes (particularly

large vehicles) have the potential to generate noise and dust nuisance to local residents. The

key management measures to alleviate these impacts are restrictions on construction hours,

covering of potentially windblown loads and washing of trucks prior to exit as outlined below.

Construction access to the site will be via Treatment Plant Road, Tinderbox Road and then via

either Algona Road or Roslyn Avenue before reaching the major Highways (Southern Outlet,

Channel Highway, Huon Highway) depending on the direction of travel.

There are no residential properties on Treatment Plant Road and it is understood that

approximately 8,000 vehicles a day currently use Tinderbox Road East. The increase in traffic

caused during the construction process is considered to be both manageable and a relatively

minor impact.

The roads to be used for construction are Council and State Roads and considered to be of

suitable capacity to cater for the proposed temporary increase in traffic.

Operation

The proposed traffic volumes during operation are not expected to be significantly different from

current vehicle movements for the existing STP.

As outlined in Section 2.6.3 the expected traffic to the site once the Project construction is

complete and the plant reaches full capacity (noting truck movements will be less in the

intervening period) is:

Three staff cars per day

One truck per day (on average) collecting biosolids (at max plant capacity);

One truck per week collecting grit and screenings;

Up to three trucks per week delivering chemicals or other supplies.

This equates to approximately three cars and 1-2 trucks per day visiting the Project site during

normal operations; this is almost unchanged from current conditions.


During maintenance periods up to 25 vehicles could visit the site on any one day, but this would

be limited to infrequent events lasting up to one week at a time and is consistent with the current

STP.

Vehicles will be visiting the site during normal operating hours and will not be travelling off-road,

therefore the potential for noise or dust impacts above existing levels is low.


To address the residual impact during construction, the following management measures are

proposed.

All loads entering or leaving the site with potentially windblown materials will be covered

(refer Section 6.1.3).

A wheel wash will be installed at the site entrance and all vehicles with visible mud or dirt

will be washed upon entry and prior to leaving to minimise spread of weeds or dust/mud

onto surrounding roads.

The Contractor will develop a Traffic Management Plan prior to construction which will be

adhered to for the life of the construction phase. This may include the need for specific

traffic management personnel at both the site access and Treatment Plant Road.

The Contractor will also provide sufficient onsite parking (within the Construction

Compound and already cleared areas within the newly fenced Project site) for workers and

deliveries to avoid any offsite parking.

The Contractor will avoid the period of peak traffic (morning and evening) for delivery of

equipment and building materials where practicable.

6.20.4 Monitoring, Review and Adaptive Management

TasWater is committed to proactive community and stakeholder engagement leading up to, and

during, construction. The Contractor will maintain an online complaints register for any traffic

complaints received. Any complaint received will be promptly dealt with including informing the

complainant of the resolution, and keeping a record of the complaint and its resolution.

Commitment 35 The contractor will prepare Traffic Management Plan

(either stand alone or as part of the CEMP) prior to construction.

Commitment 36 An online complaints register will be maintained during

the construction period and any traffic related complaints will be

registered, addressed and reported back to the complainant.


7. EPBC Act Assessment

7.1 Background

The Project has not been referred to the Commonwealth Department of the Environment (DoE)

as it has been assessed as unlikely to significantly impact on any Matters of National

Environmental Significance (MNES) or other matters protected under the EPBC Act. An outline

of the assessment is provided below.

7.2 Matters of National Environmental Significance

The online Protected Matters Search Tool was used to investigate the Project Site and its

surrounds (using a 2 km buffer) for any MNES or other matters present. The EPBC Act

Protected Matters Report generated is included in Appendix B, with findings summarised as

follows:

World Heritage Properties - no world heritage properties within the Project Site or buffer

area queried.

National Heritage Places - no natural heritage places within the Project Site or buffer area

queried.

Wetlands of International Importance - no wetlands of international importance within the

Project Site or buffer area queried.

Listed threatened species - listed species predicted and/or known to occur within 2 km of

the Project Site. Further information is provided below.

Listed Threatened Ecological Communities (TEC) - TEC likely to occur within area. Further

information is provided below.

Migratory species - Potential for migratory species to occur within or nearby to the site.

Further information is provided below.

Commonwealth Reserves - no Commonwealth Reserves within or nearby to the site

Great Barrier Reef Marine Park - No impacts to the Great Barrier Reef.

Nuclear actions - No nuclear actions are proposed.

Water resource in relation to coal seam gas development and large coal mining - not

applicable

Potential impacts on identified protected.

7.3 Listed Ecological Communities

Giant Kelp Marine Forests of South-East Australia are listed as a TEC under the EPBC Act. In

the Derwent Estuary immediately east of the site, and located inshore from the existing outfall

from the STP, is the Blackmans Bay Giant Kelp Forest. In 2014 CEE undertook an ecological

risk assessment to determine whether the kelp forest met the TEC listing criteria to be

considered part of the Giant Kelp Marine Forests of South-East Australia.

CEE (2015)10 found that the Giant Kelp forest at Blackmans Bay fulfils most of the criteria to be

considered part of the TEC, however it does not occur in water more than 8 m deep (one of the

10 CEE 2015, Internal memo - Blackmans Bay STP Upgrade - Assessment of effects on Giant Kelp and North

West Bay ecosystem, January 2015


defining characteristics). They therefore concluded the kelp forest to not fulfil the TEC definition

for Giant Kelp Marine Forests of South-East Australia.

There are no other EPBCA listed ecological communities within the Project site (or adjacent and

potentially impacted by the Project).

Based on this assessment by CEE, no significant impacts to listed ecological communities are

anticipated.

7.4 Listed Threatened Species and Migratory Species

7.4.1 Flora

There were no EPBC Act listed flora species recorded within the Project Site and given the

timing of the surveys and vegetation communities encountered it is considered unlikely that any

were overlooked. Therefore no impacts to listed flora species are anticipated (Section 6.7.3).

7.4.2 Fauna

As outlined in Section 6.7, a small number of EPBC Act listed threatened and migratory species

may occur within the Project Site. The points below are a summary of pertinent information. A

full assessment is provided in Section 6.7.

Swift parrot (Lathamus discolour)

– The swift parrot may forage and nest within the Project Site, which contains two of their

preferred feeding tree species E. globulus and E. ovata. There are also a small number

of hollow bearing eucalypts within the Project Site but outside of the Project Footprint.

In summary, no hollow bearing trees will be impacted by the proposed works, and only

1.2% (approximately) of the available E. globulus foraging habitat on the Project Site

will be cleared. TasWater have made a commitment to plant new E.globulus for all

mature E.globulus removed at a ratio of 1 to 3. Overall the impacts to swift parrot

through tree clearance are not likely to significantly impact the species.

Eastern barred bandicoot (Perameles gunnii)

– The Eastern barred bandicoot may forage within the grassy eucalypt forest on site,

however the site is unlikely to provide key habitat for this species (in the context of

better quality habitat available in the local area). The loss of up to 1.2% of E. globulus

forest is not expected to significantly impact the Eastern barred bandicoot.

Eastern quoll (Dasyurus viverrinus)

– The Eastern quoll may also occur on site however the site is unlikely to provide key

denning/nesting habitat. The loss of the small area of E. globulus forest will not

significantly impact the Eastern quoll.

The project is considered not likely to have a significant impact on the identified threatened

fauna species potentially occurring, namely the swift parrot (Lathamus discolour), Eastern

barred bandicoot (Perameles gunnii), or the Eastern quoll (Dasyurus viverrinus).

Whilst other EPBC Act listed species fauna (including migratory species) may occur in the

marine environment offshore from the Project the potential for impact to such species is

considered to be low as outlined in Section 6.8 and significant impacts are unlikely.


8. Monitoring and Review

In order to monitor ongoing performance of the STP and success of the mitigation measures in

this DPEMP, the following monitoring is proposed:

Treated effluent monitoring;

Sludge monitoring;

Receiving waters monitoring;

Terrestrial ecology monitoring; and

Construction phase monitoring.

Details of each monitoring programs are provided in the relevant section of this DPEMP and

summarised below. The outlined monitoring programs are proposed and will be subject to EPA

and Council consideration and inclusion in resulting permits. Commitments in relation to this

monitoring are provided below or under the relevant section of this DPEMP.

8.1.1 Treated Effluent Monitoring

Flow meters will be installed on the new STP to measure flows of treated effluent from the plant.

Treated effluent will be sampled immediately prior to discharge (tap on the discharge pipe).

Grab samples will be taken and analysed for a range of parameters as summarised in Table

8-1. Relevant QA/QC samples will be collected also.

The treated effluent is considered to be adequately characterised already and no contaminants

of concern were identified from existing effluent analysis (aside from normal wastewater

toxicants such as ammonia). This analysis also took into account potential additional STP waste

streams and trade waste sources from the potential amalgamation STPs. Therefore, whole of

effluent toxicity (WET) testing is not proposed at this stage.

Table 8-1 Treated Effluent Sampling

Parameter Units of measurement Sampling frequency

Flow (influent) ML/day Continuous (flow meter) (checked

weekly)

Flow (effluent) ML/day Continuous (flow meter) (checked

weekly)

Water quality (in-situ)

pH - Weekly

Temperature °C Weekly

Conductivity µS/cm Weekly

Water quality (grab sample) (Laboratory)

Biochemical Oxygen

Demand

mg/L Weekly

Suspended Solids mg/L Weekly


Parameter Units of measurement Sampling frequency

Ammonia-Nitrogen mg/L Weekly

Nitrate-Nitrogen mg/L Weekly

Nitrite-Nitrogen mg/L Weekly

Total Nitrogen mg/L Weekly

Total Phosphorus mg/L Weekly

Oil and Grease mg/L Weekly

Thermotolerant Coliforms cfu/100mL Weekly

Enterococci cfu/100mL Weekly

As, Cd, Cr (tot), Cu, Pb,

Mn, Hg, Ni, Se, Zn

mg/L Annually

Commitment 37 Continuous flow monitoring will be undertaken at the

STP to measure inflows and outflows from the plant.

Commitment 38 Weekly and annual treated effluent grab samples will be

collected and analysed for the parameters outlined in Table 8-1.

8.1.2 Sludge/Biosolids monitoring

Biosolids will be monitored in accordance with the Tasmanian Biosolids Reuse Guidelines 1999,

or as otherwise approved by the EPA Director.

Commitment 39 Biosolids will be monitored in accordance with the

Tasmanian Biosolids Reuse Guidelines 1999, or as otherwise

approved by the Director.


8.1.3 Receiving Environment Monitoring

Receiving environment monitoring is outlined in Section 6.8.4, with sampling sites illustrated on

Figure 6-13. The proposed sampling program is summarised below, but for full details refer

back to the relevant section. Water monitoring is conducted at a number of different depths at

each site (refer Section 6.8.4) for details.

Table 8-2 Receiving Environment Monitoring

Monitoring Type Sites Parameter Frequency

Water

Monitoring

Outfall

North of outfall (15m,

50m, 100m and

250m)

South of outfall (15m,

50m, 100m and

250m)

East of Outfall (15m)

Reference sites 1

and 2 (DEP sites B1

& B3)

Physicochemical* (pH,

Temperature, Salinity,

Dissolved oxygen, Turbidity)

Nutrients** (Total Nitrogen,

Ammonia as N, Nitrate as N,

Nitrite as N, Total Phosphorus

as P, Reactive Phosphorus as

P, Chlorophyll a)

Other** (Chloride, Oil and

Grease, Total Dissolved

Solids, Total Suspended

Solids, Thermotolerant

Coliforms)

Dissolved metals suite** (Sb,

As, Be, B, Cd, Cr, Co, Cu, Pb,

Mn, Mo, Ni, Se, Ag, Sn, Zn) to

be ceased 12 months post

commissioning if no difference

pre and post commissioning

detected

-biannually prior to

commissioning

(summer / winter) at

the approval of the

Project

-Once during the 6-

month

commissioning

period

-biannually in the

year following

commissioning

-Annually following

year 1

Kelp sites 1, 2,3 Physicochemical* (pH,

Temperature, Salinity,

Dissolved oxygen, Turbidity)

Nutrients** (Total Nitrogen,

Ammonia as N, Nitrate as N,

Nitrite as N, Total Phosphorus

as P, Reactive Phosphorus as

P, Chlorophyll a)

Benthic Infauna Outfall

North of outfall (15m,

50m, 100m and

250m)

South of outfall (15m,

50m, 100m and

250m)

East of the outfall

(15m)

Collection of benthic infauna

samples as per the

methodology stipulated in CEE

(2015b)

-Once pre

commissioning

-Once during the 6-

month

commissioning

period

-biannually in the

year following

commissioning


Monitoring Type Sites Parameter Frequency

-Triennially following

first 12 months

Kelp Monitoring 0-100 m north of

fertiliser ports

0-100 m south of

fertiliser ports

0-100 m south of

fertiliser ports (outer)

Diver transects counting

number of stipes within 1m of

transect, changing sides every

10m of transect. Also canopy

density estimated every 10m,

based on a 1-4 ranking with 1

being no coverage, 1 being

25% and 4 being 100%.

-Once pre

commissioning

-Twice in first 12

months following

commissioning

- Annually following

year 1 (frequency to

be reviewed three

years following

commissioning with

the EPA)

* In situ and depth profile of whole water column at 1m intervals to be collected.

** Laboratory

8.1.4 Terrestrial Ecology Monitoring

The following terrestrial ecology monitoring is proposed to manage the risk of weeds/pathogens

at the site as well as measuring the success of proposed revegetation and landscaping:

An initial pre construction weed treatment will be undertaken, followed by 6 monthly weed

surveys during construction, and additional weed control applied as required.

Results of 6 monthly surveys will be documented and provide to TasWater (and regulatory

authorities on request)

A post construction weed, pathogen and revegetation success survey will be undertaken at

the completion of construction, with follow up surveys completed annually thereafter for a

period of 5 years.

The surveys will include the establishment of photo points in the revegetated/landscaped

areas in order to assess long term survival rates of planted species, weed invasions,

success of any watering regimes and requirements for supplementary plantings.

The result of each survey event will be documented and made available to regulatory

authorities on request.

All monitoring will be undertaken by a suitably qualified person with experience in weed and

revegetation monitoring. Any remedial actions as a result of the monitoring program will be

communicated to TasWater and actioned.

8.1.5 Construction Phase Monitoring

During the construction phase routine monitoring will be undertaken (to be stipulated in the

CEMP). As a minimum the following is proposed:

Daily visual inspections of dust from earthworks;

Weekly visual inspections of run-off from works, sedimentation ponds and any diversion or

perimeter drainage lines for integrity and effectiveness;

Regular inspection of machinery for fluid leaks;

Regular (monthly) audits of hazardous material storage, including identification of any non-

compliant storage locations or conditions;


Regular (monthly) audits of waste management including identification of any windblown

waste, odorous waste or opportunities for recycling;

Surveillance during earthmoving for unanticipated heritage finds;

Construction phase weed surveys (outlined above);

Health and safety monitoring; and

Construction waste monitoring.

All monitoring and audits during construction will be documented and provided to TasWater (or

regulatory authorities) on request.


9. Decommissioning and Rehabilitation

The proposed upgraded Blackmans Bay STP has a design life in the order of 50 to 100 years.

In addition, the planning undertaken by TasWater (and other parties) in recent years has

considered the overall Kingborough sewage network, not only Blackmans Bay in isolation. As a

result, the proposed Blackmans Bay STP upgrade has been designed with capacity up to at

least 2040, including allowance for the future amalgamation of Electrona, Margate and Howden

STPs into Blackmans Bay STP as part of this planning process. This process provides a reliable

indication that the upgraded STP will not be in line for decommissioning for a very long time.

At such time as decommissioning is required, the following broad steps will apply:

Decommission all plant and infrastructure and divert effluent elsewhere (location to be

determined in the future);

Undertake a preliminary Environmental Site Assessment to understand contamination risk;

Disconnect all site services and dismantle and remove all above ground infrastructure;

Undertake intrusive Environmental Site Assessment (if required) and excavate and

remediate any contaminated materials;

Regrade the site to a stable condition;

Landscape the site with local native species to complete the surrounding land; and

Undertake validation sampling and final contamination reporting.

A detailed Decommissioning and Rehabilitation Plan will be prepared for the site at such time as

directed by the EPA.

Commitment 40 A Decommissioning and Rehabilitation Plan will be

prepared for the site at such time as directed by the EPA.


10. Commitments

A summary of commitments is made in Table 10-1 below. The responsible party for all

commitments is TasWater.

Table 10-1 Commitments

No. Commitment Section of DPEMP

1 Trucks with potentially windblown materials will be covered. Air

2 Daily visual monitoring of the site for dust will be untaken

during construction and water sprays applied to roads and

stockpiles if needed.

Air

3 A complaints register will be established for both the

construction and operational phases. All complaints will be

logged, actioned and all outcomes documented.

Air

4 TasWater will undertake community and stakeholder

engagement leading up to, and during, construction.

Air

5 A Construction and Environmental Management Plan

(CEMP) will be developed prior to commencement of

construction.

Surface Water

6 A Soil and Water Management Plan (SWMP) will be

incorporated into the Site Construction and Environmental

Management Plan (CEMP).

Surface Water

7 Weekly monitoring of water and sediment control measures

will be undertaken during the construction period, with

additional monitoring within 24hrs of a storm event.

Surface Water

8 Prior to construction a detailed stormwater design will be

prepared (including review of the existing stormwater

capture) to achieve the stormwater management targets for

new developments as set out in the State Stormwater

Strategy 2010 (unless it is not feasible to do so).

Surface Water

9 Any spills of environmentally harmful liquids greater than 100

L will be reported to the EPA, with commitment to undertake

a groundwater monitoring event if deemed necessary by the

EPA.

Groundwater

10 Noise complaints will be tracked using the online complaints

register. All complaints will be logged, actioned and all

outcomes documented.

Noise

11 Detailed design will address the required noise limits on

equipment and acoustic enclosures as stipulated in this

DPEMP and the Vipac Noise Report (2016); namely 85dBA

or less for the inlet works, 80dBA (at 1m) or less for the

odour control fan, 89dBA or less for the odour control fan

Noise



inlet duct and 84dBA or less for the exhaust from the odour

control fan.

12 Care will be taken in the development and selection of

enclosures for the IDEA blowers such that tonal noise

emission breakout doesn’t generate potentially intrusive

noise emissions.

Noise

13 A targeted inspection of areas proposed for subsurface

excavations will be undertaken by a Certified Practitioner

(Site Contamination Practitioners Australia) prior to

construction to identify any areas of high risk for land

contamination for subsequent soil testing, classification and

management.

Waste

14 A Sewage Sludge Management Plan (SSMP) will be

developed for the Project.

Waste

15 All hazardous materials will be stored in suitably bunded

areas in accordance with the relevant guidelines.

Dangerous Goods

and Hazardous

Materials

16 Any spilt waste will be immediately reported to the site

manager and clean-up will occur.

Dangerous Goods

and Hazardous

Materials

17 Inspections and audits of environmentally hazardous

material use and storage will be undertaken monthly.

Dangerous Goods

and Hazardous

Materials

18 Dangerous goods and environmentally hazardous materials

storage, handling and clean up procedures will be

incorporated into the site CEMP for the construction phase

and the Operations and Maintenance Manual during the

operational phase.

Dangerous Goods

and Hazardous

Materials

19 All areas of DGL community outside of the immediate

development footprint will be flagged with temporary high

visibility fencing and protected during construction works.

Biodiversity

20 All eucalypts outside of the immediate development footprint

will be flagged with flagged with temporary high visibility

fencing and protected during construction works.

Biodiversity

21 Replacement planting will be undertaken for all mature

Eucalypt trees removed at a ratio of 3:1 as part of the

Landscaping Plan.

Biodiversity

22 Weed and hygiene management will be incorporated into the

site CEMP following the principles outlined in this DPEMP.

Biodiversity



23 Annual monitoring for the first five years of the landscaped

area to assess success of tree growth, weed invasion and

replacement plantings.

Biodiversity

24 An initial pre construction weed treatment will be undertaken,

followed by 6 monthly weed surveys during construction, and

additional weed control applied as required.

Biodiversity

25 A post construction weed, pathogen and revegetation

success survey will be undertaken at the completion of

construction, with follow up surveys completed annually

thereafter for a period of 5 years.

Biodiversity

26 Receiving waters monitoring will be undertaken at 15 sites

(as shown in Figure 6 12) biannually pre-commissioning,

during commissioning and in the first year of operation and

annual thereafter.

Marine and

Coastal

27 Benthic infauna monitoring will be undertaken at 10 sites (as

shown in Figure 6 12) once pre-commissioning, once during

commissioning, biannually in the first year and triennially

thereafter.

Marine and

Coastal

28 Kelp monitoring will be undertaken at 3 sites; once pre-

commissioning, twice in the first year following

commissioning and annually thereafter (until reviewed with

the EPA).

Marine and

Coastal

29 If the monitoring program reveals marine impacts as a result

of phosphorus in the STP discharge, the EPA will be

contacted and phosphorus removal will be retrofitted to the

STP and new emission limits established in consultation with

the EPA.

Marine and

Coastal

30 An Unanticipated Discovery Plan will be included in the Site

CEMP and followed in the event of discovery of previously

undetected heritage features.

Heritage

31 A vegetation screen will be planted along the western

boundary of the new STP as outlined on the Figures in this

DPEMP.

Visual

32 A Health and Safety Management Plan (HSMP) will be

prepared for the construction phase and incorporated into

the Site CEMP.

Health and Safety

33 Health and safety management will be included in the site

specific Operations and Maintenance Manual.

Health and Safety

34 A site specific Operations and Maintenance Manual will

prepared and reviewed every 5 years once established.

EMS



35 The contractor will prepare Traffic Management Plan (either

stand alone or as part of the CEMP) prior to construction.

Traffic

36 An online complaints register will be maintained during the

construction period and any traffic related complaints will be

registered, addressed and reported back to the complainant.

Traffic

37 Continuous flow monitoring will be undertaken at the STP to

measure outflows from the plant.

Monitoring

38 Weekly and annual treated effluent grab samples will be

collected and analysed for the parameters outlined in Table

8 1.

Monitoring

39 Biosolids will be monitored in accordance with the

Tasmanian Biosolids Reuse Guidelines 1999, or as

otherwise approved by the Director.

Monitoring

40 A Decommissioning and Rehabilitation Plan will be prepared

for the site at such time as directed by the EPA.

Decommissioning


11. Conclusion

The Blackmans Bay STP upgrade involves capacity and performance improvements to the

existing Blackmans Bay STP, located in southern Tasmania.

The upgrade will benefit the Kingborough area, both now and for future generations, by

improving capacity and performance of the Blackmans Bay STP and allowing TasWater to

consolidate and enhance the Kingborough sewerage system to accommodate future growth in

the area and centralise waste from local catchments so underperforming STPs at Electrona,

Margate and Howden can be closed - providing long term benefits to North West Bay. It will

also improve overall effluent treatment to improve the quality of water discharged to the

Derwent Estuary and meet EPA compliance requirements.; as well as improving odour and

noise issues for local residents.

The Project involves retrofitting of some existing infrastructure on site, construction of some new

infrastructure and continued use of the existing treated effluent outfall into the Derwent Estuary.

The plant upgrades are crucial to address ageing infrastructure, limits to future capacity, existing

issues with meeting emission limits and ongoing odour issues. The STP upgrade has been

sized to accommodate future amalgamation of Margate, Electrona and Howden STPs into

Blackmans Bay. These plants are also experiencing issues with ageing infrastructure and future

capacity limitations. By closing these plants treated effluent can be removed from North West

Bay (where the plants currently discharge) and redirected through the newly upgraded

Blackmans Bay STP to the higher energy Derwent Estuary. This poses a significant positive

outcome for North West Bay.

For most parameters, the upgraded STP will achieve significantly improved treated effluent

quality. This results in an improvement to the receiving environment, particularly with regard to

nitrogen and ammonia, which are predicted to achieve a reduction in overall mass loads to the

Derwent Estuary even at the full flows from the upgraded STP (8.53 ML/day ADWF) due to the

significant improvement in nitrogen removal from the new plant. Some parameters however will

see a gradual increase in mass loads (particularly phosphorus) to the Derwent Estuary due to

the proposed emission limits and the gradual increase in flows from Blackmans Bay and the

redirection of Margate, Electrona and Howden flows from North West Bay to the Derwent

Estuary. The impact to the receiving environment has been assessed in detail in Section 6.8.

The proposal involves some clearance of mature eucalypt species and a very small area of a

threatened vegetation community but is predominantly focused on already disturbed land.

TasWater has committed to a landscaping program replacing all mature eucalypts removed with

new trees at a ratio of 3 to 1.

There will be some changes to odour and noise impacts from the upgraded STP on the

surrounding properties (refer Sections 6.1 and 6.4) but these are within established guideline

limits and generally represent a similar or improved situation in comparison to current

conditions.

Overall the Project offers a significant improvement in wastewater treatment capacity, quality

and reliability, while posing a relatively small number of environmental and social impacts.

Treatment plant upgrades and expansions are an essential part of maintaining the State’s

wastewater assets for current and projected population growth and the Blackmans Bay site has

been carefully selected and designed to minimise impacts as far as practical whilst allowing the

provision of long term wastewater treatment in the Kingborough region.


12. Limitations

This report: has been prepared by GHD for TasWater and may only be used and relied on by

TasWater for the purpose agreed between GHD and the TasWater for understanding the

environmental and planning implications of the proposed development.

GHD otherwise disclaims responsibility to any person other than TasWater arising in connection

with this report. GHD also excludes implied warranties and conditions, to the extent legally

permissible.

The services undertaken by GHD in connection with preparing this report were limited to those

specifically detailed in the report and are subject to the scope limitations set out in the report.

The opinions, conclusions and any recommendations in this report are based on conditions

encountered and information reviewed at the date of preparation of the report. GHD has no

responsibility or obligation to update this report to account for events or changes occurring

subsequent to the date that the report was prepared.

The opinions, conclusions and any recommendations in this report are based on assumptions

made by GHD described in this report. GHD disclaims liability arising from any of the

assumptions being incorrect.

GHD has prepared this report on the basis of information provided by TasWater and others who

provided information to GHD (including Government authorities)], which GHD has not

independently verified or checked beyond the agreed scope of work. GHD does not accept

liability in connection with such unverified information, including errors and omissions in the

report which were caused by errors or omissions in that information.


13. References

ANZECC & ARMCANZ (2000) National Water Quality Management Strategy: Australian and

New Zealand Guidelines for Fresh and Marine Water Quality.

BOM (2016). http://www.bom.gov.au/climate/averages/tables/cw_094029.shtml (accessed

26/7/2016)

CEE (2007) Kingborough Wastewater Management Strategy, Long Term Strategy Consulting

Environmental Engineers, 2009

CEE (2009a) Development Plan and Environmental Management Plan for Blackmans Bay

Outfall Extension. Consulting Environmental Engineers, 2009.

CEE (2009b) Marine Baseline Study for Blackmans Bay Outfall Extension, Baseline Monitoring

Report: Blackmans Bay Outfall Extension. Consulting Environmental Engineers, December,

2009.

CEE (2015a) Blackmans Bay Outfall: Water Quality Monitoring Program. Consulting

Environmental Engineers, December 2015

CEE (2015b) Blackmans Bay Outfall: Marine Ecological Monitoring Program, Infauna

Community and Giant Kelp, Sixth Operational Survey. Consulting Environmental Engineers,

December 2015

CEE (2015c), Internal memo – Blackmans Bay STP Upgrade – Assessment of effects on Giant

Kelp and North West Bay ecosystem, January 2015.

DEP (2015) Coughanowr C, Whitehead S, Whitehead J, Einoder L, Taylor U and Weeding, B,

2015. State of the Derwent estuary: a review of environmental data from 2009 to 2014. Derwent

Estuary Program

DoE (2014). National Greenhouse Accounts Factors, Australian National Greenhouse Accounts.

Department of the Environment, July 2014.

DPIPWE (2016) Natural Values Atlas, viewed 19/07/2016, Department of Primary Industries,

Parks, Water and Environment (DPIPWE), Hobart.

EPA (2003). Protected Environmental Values (PEVs) for the Derwent Estuary downstream of

the New Norfolk Bridge to Tinderbox/South Arm, EPA, December 2003.

Herzfeld, M., Parslow, J., Margvelashvili, N., Andrewarth, J.R., and Sakov, P. Numerical

Hydrodynamic Modelling of the Derwent Estuary, Final Report. CSIRO, Hobart, March 2005.

Tasflora (2014) Flora and Fauna Assessment – Blackmans Bay Wastewater Treatment Plant

Upgrade, November 2014, Sandy Bay.

Vipac (2016) Blackmans Bay STP Environmental Noise Assessment Report No. 421451-01.

Vipac Engineers & Scientists, Kings Meadows Tasmania, July 2016.

http://www.bom.gov.au/climate/averages/tables/cw_094029.shtml

GHD | Report for TasWater - Blackmans Bay STP DPEMP, 3218107

Appendices


Appendix A - Design Drawings

Site plan

Elevations

Landscape Plan


Appendix B - Ecological Appendices

TasFlora (2014) Flora and Fauna Assessment Blackmans Bay Wastewater Treatment Plant

Upgrade

Natural Values Atlas Report (2016)

EPBCA Protected Matters Search Report (2016)


Appendix C - Sewage Treatment Plant Contingency Management Manual

TasWater (2015) Sewage Treatment Plant Contingency Management Manual


Appendix D - Near-field Modelling of Effluent

GHD (2016) Blackmans Bay STP DPEMP Near Field Modelling of Effluent


Appendix E - Odour Modelling Report

MWH (2016) Blackmans Bay Wastewater Treatment Plant Odour Impact Assessment


Appendix F - Noise Modelling Report

Vipac (2016) Blackmans Bay STP Environmental Noise Assessment

Vipac (2014) Blackmans Bay STP Stage 1 Acoustic Assessment


Appendix G - Marine Monitoring Reports

CEE (2015a) Blackmans Bay Outfall: Water Quality Monitoring Program. Consulting

Environmental Engineers, December 2015.

CEE (2015b) Blackmans Bay Outfall: Marine Ecological Monitoring Program, Infauna

Community and Giant Kelp, Sixth Operational Survey. Consulting Environmental Engineers,

December 2015.

CEE (2015c), Internal memo – Blackmans Bay STP Upgrade – Assessment of effects on Giant

Kelp and North West Bay ecosystem, January 2015.


Appendix H – EPA Project Specific Guidelines

EPA (2014) Final DPEMP Project Specific Guidelines for TasWater Blackmans Bay WWTP

Upgrade, Blackmans Bay, Tasmania

GHD

2 Salamanca Square T: 61 3 6210 0600 F: 61 3 6210 0601 E: [email protected]

© GHD 2016

This document is and shall remain the property of GHD. The document may only be used for the purpose for which it was commissioned and in accordance with the Terms of Engagement for the commission. Unauthorised use of this document in any form whatsoever is prohibited.

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Document Status

Rev No.

Author Reviewer Approved for Issue

Name Signature Name Signature Date

A Various D Elson DRAFT A Jungalwalla

DRAFT 8/8/2016

B Various A Jungalwalla

DRAFT A Jungalwalla

DRAFT 16/8/2016

1 Various A Johnson

A Jungalwalla

25/10/2016

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