C-S02355 Halls Creek Wastewater Treatment Plant and

C-S02355 Halls Creek Wastewater Treatment Plant and Treated Wastewater Management Upgrade Works Approval Application Supporting Information – October 2018

CS02355 Halls Creek WWTP and TWWM upgrade Works Approval Application Supporting Information

Document Information Document Title CS02355 – Halls Creek WWTP and TWWM upgrade. Document reference 19964046

Version Date Author(s) Reviewer(s) Comment Draft 3/09/2018 Craig

Chaudhry

1 WQBU: Bec Revere, Amy Curnow, Andrew Chua

Jim Ghaswala Stuart

Masterson

Care Price Isabel Telles

Silveira

1a Ben Stone 2 2/10/2018 Craig

Chaudhry Edits required by stakeholders

3 2/10/2018 AIPR Scott Mcphee

Received by email

4 (Final) 3/10/2018 Craig Chaudhry

Edits required by stakeholders

4 (Final) 05/10/2018 Juliet Cole (TL GAA EIA and Approvals)

5 (Final) 08/10/2018 Craig Chaudhry Edits (minor) per request of TL

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Contents 1 Purpose ............................................................................................................................... 7

2 Premise and Applicant Details .......................................................................................... 8

2.1 Occupier Details 8 2.2 Premise Details 8 2.2.1 Prescribed Premise Details 8 2.2.2 Siting 10

3 Existing Environment ....................................................................................................... 12

3.1 Specified Ecosystems 12 3.2 Flora, vegetation and fauna 12 3.2.1 Regionally Vegetation Context Halls Creek 13 3.3 Groundwater 13 3.3.1 Halls Creek WWTP 13 3.3.2 Halls Creek Oval 13 3.4 Surface water 14 3.5 Contaminated Sites 15 3.6 Climate 15 3.7 Land use 15 3.8 Effluent quality 15

4 Proposed Recycled Water Scheme at Halls Creek Oval ................................................ 16

4.1 Management Control of the Proposed Recycled Water Scheme 17 4.1.1 Department of Health Approval 17 4.1.2 Recycled Water Supply Agreement 17 4.1.3 Recycled Water Quality Management Plan 17

5 Proposed Activities .......................................................................................................... 18

5.1 Evaporation Pond Works 18 5.2 Treatment Pond Works 18 5.3 Discharge Point Works 18 5.4 Recycled Water Scheme Works 19 5.5 Commissioning Summary 19 5.6 Description of works 20 5.6.1 Construction and Commissioning and Operational Activities 20

6 Regulatory Context and Approvals ................................................................................. 21

6.1 Environmental Protection Act 1986 – Part V 21 6.2 Other Approvals 21

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7 Stakeholder Consultation ................................................................................................ 21

8 Risk Assessment .............................................................................................................. 22

8.1 Bituminous geomembrane 22 8.2 Desludging 22 8.3 Emergency Discharge during Construction and Wet Season Periods 23 8.4 Post-construction phase 23 8.5 Overview 23 8.6 Potential emission sources 24 8.7 Potential exposure pathways 25 8.8 Potential receptors 25

9 Risk assessment of S-P-R linkages ................................................................................ 33

9.1 Overview 33

9.2 Detailed risk assessment methodology 33 9.2.1 Emission likelihood 33 9.2.2 Environmental risk likelihood 33 9.2.3 Human health and amenity 34 9.2.4 Consequence risk rating 35

9.3 Risk rating 38

10 Halls Creek WWTP construction phase detailed risk assessment ............................... 39

10.1 Overview 39

11 Halls Creek WWTP post-construction detailed risk assessment .................................. 44

11.1 Overview 44

12 Halls Creek water reuse detailed risk assessment ........................................................ 48

12.1 Overview 48

13 Proposed Monitoring Program ........................................................................................ 50

13.1 Commissioning Monitoring of Facultative and Maturation Ponds 50 13.2 Commissioning Monitoring of Recycled Water Scheme 50 13.3 BGL Construction Quality Assurance Report 50

14 Fee Calculation ................................................................................................................. 51

15 References ........................................................................................................................ 52

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Appendices Appendix A Environment Policy ............................................................................................ 53

Appendix B Certificate of Title ............................................................................................... 54

Appendix C E.g. additional reports, supporting information etc ......................................... 56

Table of attachments The following table shows how the mandatory attachments referenced in the Department of Water and Environmental Regulation (DWER) application form have been addressed in this document.

•

DWER Attachment

Description Location in this document

Comment

1A Proof of occupier status Appendix A and Section 2.1

1B ASIC company extract N/A 1C Authorisation to act as a representative of

the occupier N/A

2 Premises map/s Appendix C: 2a,2b,2c,2d,2e

3A Proposed activities Section 0

3B Map of area proposed to be cleared (only applicable if clearing is proposed)

Refer to Appendix C

3C Additional information for clearing assessment

Not Applicable

4 Biodiversity surveys (only applicable if biodiversity surveys included in application)

Not Applicable

5 Other approvals and consultation documentation

Section 6

6A Emissions and discharges Section 8 and Appendix C

6B Waste acceptance

7 Siting and location Section 2 and Section 3

8 Additional information submitted

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9 Proposed fee calculation Section 14

10 Request for exemption from publication No exemption requested

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1 Purpose This document has been prepared to support an application for a Works Approval to upgrade the Halls Creek Waste Water Treatment Plant (WWTP).

The Water Corporation of Western Australia (WA) is intending to upgrade the Halls Creek WWTP, located approximately 5.5 km south southeast of the Halls Creek townsite, 300 km south of Kununurra in the Kimberley Region of WA.

The Halls Creek WWTP, originally constructed in 1982, is a pre-existing land use in the Halls Creek Water Reserve (gazetted in 2004), located within the P1 Drinking Water Source Protection Area (DWSPA) and within the 500 m radius well-head protection zones of three nearby town water supply (TWS) production bores. The WWTP is therefore considered to be an incompatible land use. During planning for the WWTP upgrade several studies were undertaken to assess the viability of alternative sites for the WWTP. The outcome of these studies was that relocation was deemed to be non-viable. The primary factors included geotechnical, hydrogeological, financial and heritage constraints associated with alternative sites identified within a 10km radius of the townsite

The current WWTP configuration comprises two facultative ponds operating in parallel discharging to two maturation ponds operating in series. The system is deemed to have a treatment capacity of 600 kL/d. Discharge from the maturation ponds flows into the adjacent 7.4 ha evaporation basin, from where treated wastewater (TWW) is subsequently evaporated. When the evaporation pond capacity is exceeded, or during high rainfall events, excess TWW is discharged to the adjacent China Wall Creek (Refer to Table 1). The overflow is dosed with chlorine tablet before reaching the creek to reduce pathogen loading. This creek flows some 2.5 km southeast into China Wall Pool – a local surface water body of amenity value often used for recreational swimming. Four such events have occurred in the last 18 years, most recently in January 2017. The evaporation basin is therefore understood to be beyond its design capacity, and is routinely operated above the design freeboard levels in order to prevent more frequent overflow events.

Further to this, the existing evaporation basin in-situ clay liner is now some 20 years old, and given the sensitive surrounding land use (DWSPA) and the intention to retain the WWTP in its current location, feedback was sought from the Department of Water and Environmental Regulation (DWER) (Water Source Protection and Environmental Licensing Sections), and Department of Health (DoH) (Water Unit) during the planning phase regarding upgrades to this basin to ensure adequate protection of the water source.

Table 1: WWTP discharge events to China Wall Creek

Date Description

February 2008 Discharge during heavy and sustained rainfall event, but considered to be a breach of licence conditions as not deemed to be a 1 in 10 year event (Water Corp, 2008)

March 2011 Controlled discharge as per the licence conditions, with low environmental impact due to the high dilution of the treated wastewater from the extreme rainfall event (Water Corp, 2011)

January / February 2017 Controlled discharge as per the licence conditions (Water Corp, 2017)

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The primary driver for the proposed upgrades is protection of public health and the environment via mitigation of the risk associated with discharge of TWW to surface water, and/or seepage to groundwater. The proposed upgrades will also cater for growth on a 20 year horizon.

It is proposed this is achieved via:

• Construction of an additional treatment and maturation pond.

• Relining of all existing treatment ponds with a bitumous Geomembrane liner, and enhancements to pond operating freeboard levels.

• Enhancement of the existing evaporation basin; relining with a bitumous Geomembrane liner, and amendments to pond embankments.

• Construction of an additional 3.8ha of evaporation pond area (thus increasing the disposal/treated wastewater management capacity).

• Implementation of a recycled water scheme with the Shire of Halls Creek, including treatment and conveyance infrastructure (further expanding the disposal/treated wastewater management capacity).

The recycled water scheme implementation is to provide an alternative means of disposal from the WWTP, reducing the water volumes that would otherwise be disposed of via the evaporation pond(s) and consequently increasing the storage capacity of the evaporation ponds during period of high rainfall events.

2 Premise and Applicant Details

2.1 Occupier Details The Water Corporation is a statutory entity and was established by Section 4(1) of the Water Corporations Act 1995 (WC Act). The Water Corporation is a body corporate (Section 4 of the WC Act) and as such does not have an ASIC company extract.

The Water Corporation provides water, wastewater and drainage services to Perth and hundreds of towns and communities spread over 2.5 million square kilometres of Western Australia. Water Corporation holds many licences for WWTPs with the DWER.

The Water Corporation operates to an environmental management system certified to ISO 14001, which enables the systematic identification of environmental risks, setting of targets and development of environment improvement plans to reduce risks and ensure its activities are sustainable. The environmental management system is guided by the Corporation’s Environment Policy (Appendix A).

2.2 Premise Details

2.2.1 Prescribed Premise Details

2.2.1.1 History The Halls Creek WWTP, initially constructed in 1982, consists of two primary facultative ponds in parallel, followed by two maturation ponds in series, treating wastewater to a secondary standard. The combined flow of the WWTP feeds directly into an adjacent 7.4 ha evaporative pond which

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was added to the system in 1998 to manage treated wastewater disposal. Prior to the construction of the evaporation basin, overflows were discharged to the environment (specifically China Wall Creek) via a series of infiltration channels south of the maturation ponds. Current emergency overflow of TWW from the evaporation basin is discharged via manually operated butterfly valve, ultimately feeding into China Wall Creek.

The Licence (L6268/1991/10) details a treatment quantity limit of 800 m3 per day as a monthly average) for sewage. The waste processing is to be in accordance with the process limits detailed in Table 2.

Table 2: Waste processing

Waste type Process Process requirement

Sewage Biological, physical and chemical treatment

Treatment of sewage waste shall not exceed 800 m3/d (as a monthly average)

Sewage Sludge Storage In accordance with ‘Western Australian Guidelines for Biosolids Management’ (Department of Environment and Conservation, 2012)

Treated Wastewater Disposal Disposal to the Evaporation Pond Emergency Discharge To China Wall Pool only as a result of rainfall in excess of an extreme

rainfall event and to prevent overtopping of the Evaporation Pond.

The licence also provides detail regarding the containment infrastructure, as summarised in Table 3.

Table 3: Containment infrastructure

Vessel or compound Material Requirements

Primary Treatment Pond Wastewater Two ponds lined with clay Secondary Treatment Pond Wastewater Two ponds lined with clay Evaporation Pond Treated wastewater Lined with clay Sludge Drying Area Sewage sludge To be constructed as required. Bunded and lined to achieve

hydraulic permeability of 1 x 10-9 m/s or less, and returns sludge leachate to the start of the treatment process.

2.2.1.2 Part V Operating Licence History The Halls Creek WWTP became a Part V Cat 54 Facility in November 2006.

2.2.1.3 Category Justification The premise will and currently undertakes Sewage Treatment being an existing sewage treatment plant operating under L6268/1991/10 and has a licenced design capacity of 800 m3 per day. This means the category fits the definition of Category 54 by volume, throughput and waste type (Table 4) and does not required to be modified as the proposed works will not exceed the Category or Threshold that the WWTP currently licenced for.

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Table 4 Prescribed Premise Category

Category Description Threshold 54 Sewage facility premises on which

sewage is treated (excluding septic tanks); or From which treated sewage is discharged onto land or into waters

100m3 or more per day (no > than 800m3 per day)

2.2.2 Siting The premise is located within the Halls Creek Local Government Area and comprises of Crown Reserve 40202, Lot 3001 on Plan 53871 (Halls Creek WA 6770). The site lies on the north-western margin of a flat alluvial plain, bounded to the northwest by the Bob Black Range Hills (Refer to Figure 2 Appendix C).

The Shire of Halls Creek Oval (the proposed recycled water scheme irrigation area) is located in Halls Creek township, just north of the Great Northern Highway, Approximately 4.5 km northwest of the WWTP.

A map of the premises is included in Figure 1 and the GPS coordinates for the proposed premise boundary are provided in Table 4a. A copy of the Certificate of title is provided in Appendix B.

Table 4a Proposed Prescribed Premise Boundary Coordinates

Site Boundary Coordinates (MGAZ 52)

Point Easting Northing 1 362891 7981915

2 362722 7982169 3 362680 7982141 4 362669 7982158 5 363268 7982557 6 363536 7982155 7 363328 7982017 8 363081 7982042

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Figure 1 Prescribed Premise Boundary Map (Double Click to Open PDF).

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3 Existing Environment

3.1 Specified Ecosystems The DWER Guidance Statement: Environmental Siting (DER, 2016) lists specified ecosystems that must be considered when assessing the risk of prescribed premises. Analysis against the datasets listed in Appendix 1 of the guidance statement indicates the following specified ecosystems occur adjacent to the premise: Figure 3 in Appendix C shows no specified ecosystems in 3 km of the WWTP.

• No identified specified ecosystems within 1 km of Halls Creek WWTP • No identified specified ecosystems within 2 km of Halls Creek WWTP • No identified specified ecosystems within 3 km of Halls Creek WWTP.

The nearest sensitive receptors to the premise are described in Table 6 below.

Table 6: Nearest sensitive receptors

Sensitive Receptor Distance Comment Groundwater – Town Water Supply (TWS)

within 500 m The WWTP falls within the P1 DWPSA of the Halls Creek TWS, and within the well head protection zone of three of the production bores. The three production bores 4/92, 7/75 and 7/90 (Refer to Figure 3a in Appendix C).

Groundwater Dependent Ecosystems

NA No known groundwater dependent ecosystems have been identified within 3 km of the WWTP

Groundwater Users 1.1 km east There are several known abstraction bores (in addition to the TWS bores) associated with a cattle yard approximately 1.1 km southeast of the WWTP.

Surface Water – China Wall Creek

An ephemeral creek immediately adjacent to the WWTP site

Surface Water – China Wall Pool

2.5 km southeast

A site of amenity value downstream of the site along the course of China Wall Creek and often used by recreational swimmers

Surface Water Users – Agricultural water use (livestock)

Adjacent to China Wall Creek is a wind pump, which is anticipated to abstract water from the groundwater. The site is reportedly to be disused.

Residential Dwellings 100 m south Residential Property 1 km West Nearest residential property

3.2 Flora, vegetation and fauna A total of 13 vegetation communities (Eucalypt Woodland over tussock grassland and Hummock Grassland exist across the WWTP, pipeline and Shire oval area. Of the areas surveyed no other conservation significant flora species, as listed under Wildlife Conservation Act 1950 was recorded with in the Project Footprint (WWTP and Pipeline Area).

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One fauna species of conservation significance, the Rainbow bee-eater (Meropos ornatus; WC Act Schedule 5), was identified in 2017. Excluding the Rainbow bee-eater no other conservation significance species was identified or likely to occur within the Project Footprint.

Estimated clearing with in the Project Footprint is 32ha. Clearing will managed under the Water Corporation’s State Wide Clearing Permit CPS 185/8.

3.2.1 Regionally Vegetation Context Halls Creek Vegetation is sparse and consists of Mitchell and Flinders grasses on black soil plains and spinifex on the red soil and hill slope. Eucalypts are generally restricted to drainage lines and typically present around Halls Creek and its tributaries.

3.3 Groundwater

3.3.1 Halls Creek WWTP The Halls Creek WWTP is underlain by steeply north dipping Moola Bulla Formation strata, comprising pale green shale and siltstone and green fine-grained sandstone which are jointed and extensively fractured in outcrop (Davidson, 1993). The Moola Bulla Formation is unconformably overlain by the King Leopold Sandstone (a blocky thick-laminated sandstone), which forms the most significant groundwater resource in the area – targeted by a number of production bores as part of the Halls Creek Town Water Supply – and the Carson Volcanics. The Carson Volcanics form the core of a south-westerly plunging syncline, flanked to the northwest and southeast by a low lying parallel range of hills formed by the King Leopold Sandstone.

The surficial geology beneath the WWTP is described (Geological Survey of Western Australia, 1999) as a grey clay and silt forming black soil plains. From site investigation undertaken in 1997 the WWTP was shown to be underlain by a sequence of transported brown alluvial clays (Golder Associates, 1997).

Groundwater recharge to the King Leopold Sandstone is primarily by rainfall infiltration over the outcrop area, and from minor lateral groundwater flow from adjacent geological formations. The Moola Bulla Formation is similarly recharged from direct rainfall infiltration, but because of the predominantly shale / siltstone composition it is unlikely that there is significant storage within the Moola Bulla Formation as fractures probably become closed at relatively shallow depths.

Groundwater level measurements following investigations in 1997 and 2017 both indicate the local groundwater flow direction to the northwest – towards production bores which form part of the Halls Creek TWS, as shown on Figure 3 Appendix C. The depth to groundwater, from the recent 2017 investigation at the WWTP site, is between 31.7 m and 38.4 m (October 2017). Contours based on October 2017 monitoring data from both the WWTP and nearby TWS bores are presented on Figure 3 Appendix C, and show a north-westerly trending groundwater gradient, from the WWTP towards the actively abstracting Town Water Supply bores.

The TWS bores are sampled on a monthly basis for conductivity and major analytes. No decline in groundwater quality is noted in the Annual Statements made to DWER (Water Corporation, 2008 to 2017).

3.3.2 Halls Creek Oval The Halls Creek Oval (HCO) is underlain by surficial deposits comprising sand and silt, mainly Aeolian and sheet-wash deposits over a bedrock of undivided metamorphosed (low to high grade)

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sedimentary and volcanic rocks of the Koongie Park Formation (Geological Survey of Western Australia, 1999). Bore logs in the area reportedly identify a brown clay to a maximum depth of 5m, overlying 2m of kaolin and 6m of sandy clays over basalt (Field Capacity, 2017).

There are no site specific water levels available, but water levels from TWS production bores 2/06 and 3/06 indicate a depth to groundwater of approximately 8m may be anticipated at the HCO. The HCO is located 4km away from the perennial watercourse of the Elvire River.

Groundwater Use

The WWTP site falls within the P1 DWSPA for the Halls Creek town water supply (Figure 4 Appendix C), with three bores within 500 m (wellhead protection area) of the WWTP. The corresponding groundwater licence (DWER Licence 110926) is for an annual abstraction of 700,000 kL from a borefield comprising 16 production bores, of which 12 are regularly active. Bores 4/92, 7/75 and 7/90 have been isolated since 2015 due to the proximity of the WWTP. These bores will remain as “emergency use only” until replacements are drilled (Water Corporation, 2018). The Water Corporation is currently undergoing investigation to identify new suitable bore locations. Once commissioned, the three existing bores are likely to be decommissioned. The 13 other bores are meeting ADWG health requirements.

There are eight individual groundwater licences in the vicinity of Halls Creek (Refer to Table 7a), typically associated with small abstractions (with the exception of the town water supply abstraction licence). Licence 170223 is associated with a bore providing water to the nearby Halls Creek swimming pool facility; this bore lies within the HCO site.

Table 7a Groundwater licence summary

Licence ID Volume (kL/year) Owner, description

110926 700,000 Water Corporation, town water supply 170223 35,000 Shire of Halls Creek 61702 5,000 Department of Education 48282 2,000 Guerinoni Family Trust 156272 6,000 Kireen Nominees Pty Ltd 165723 99,000 Main Roads 179825 10,000 Kimberley Stampede Rodeo Club 171398 8,000 Housing Authority

Halls Creek Oval (HCO)

The Halls Creek Shire oval is flanked to east, south and west by residential, mixed use and commercial (town center) land uses. Extending beyond the township the surrounding land use is designated as pastoral.

3.4 Surface water China Wall Creek is an ephemeral surface water immediately adjacent to the WWTP. Discharges of TWW from the WWTP to a tributary of China Wall Creek only occur during high rainfall events.

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China Wall Pool is an ephemeral surface water pool that is surrounded by a vein of sub-vertical white quartz rising up to 6m above the surrounding landscape. China Wall Creek is 6km from halls creek township.

3.5 Contaminated Sites There are no contaminated sites within 1km of the Halls Creek WWTP. The Halls Creek WWTP is not classified as a contaminated site as per the DWER Contaminated sites database. There are no contaminated sites within 1 km of the HCO, however 1.25 km from the HCO, just outside the township, is a site classed as Remediated for Restricted Use (hydrocarbon-impacted soils) at Lot 74 on Plan 187987 (Certificate of Title LR3013/521).

3.6 Climate Halls Creek is located in the East Kimberley where the climate is classified as grassland, hot (winter drought) on the Bureau of Meteorology Map of Climate Zones of Australia with a strong wet/ dry seasonal pattern. The mean annual rainfall is 576 mm (1944 to June 2018, from the BoM Halls Creek Meteorological Office (Site 002012), which typically falls during the wet season (November to March) with minimal rainfall during the dry season (April to October) (Refer Graph 1).

Graph 1: Mean monthly rainfall and temperature at Halls Creek Meteorological Office (Bureau of Meteorology Station No. 2012)

3.7 Land use

The Halls Creek WWTP is surrounded by land designated as pastoral (Department of Planning, 2016). To the south of the WWTP is a livestock enclosure, with two stock watering points immediately south of the China Wall Creek.

3.8 Effluent quality

The current Licence (L6268/1991/10) requires quarterly monitoring of selected parameters at the discharge point from the WWTP to the evaporation pond. Wastewater quality monitoring results are presented in the Annual Environmental Report (AER) for the WWTP, in accordance with

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Licence requirements. The most recent results (2017 to 2018 are summarised in Table 7b. No monitoring of discharge water quality is undertaken when discharges occur to the environment.

Table 7b Quarterly effluent quality data at Halls Creek WWTP Pol Pond 2 Dis M/H (discharge point to the evaporation pond) – 2017 to 2018 AER reporting period

4 Proposed Recycled Water Scheme at Halls Creek Oval The proposed Halls Creek Recycled Water Scheme can supply up to 200kL (average irrigation demand is estimated to be 104 kL per day) per day of fit-for-purpose recycled water to the Shire of Halls Creek for irrigation of the 2.1ha HCO. Irrigation of the HCO is classified as a ‘Low Exposure Risk’ scheme and recycled water quality will be in accordance with the DoH Guidelines for the Non-potable Uses of Recycled Water in Western Australia (2011) for ‘Low Exposure’ risk schemes. Additional measures to ensure mitigation of public health risks will include adequate signage and access restrictions, and appropriate irrigation management practices (e.g. night time watering, adequate drying time after irrigation, irrigation not to occur during or immediately after rainfall).

A Nutrient Risk Assessment was completed in 2017 (Field Capacity 2017) for the proposed Halls Creek Recycled Water Scheme. The Nutrient Risk Assessment assessed the site based on the guidance of Water Quality Protection Note (WQPN) 22 (DoW, 2008). Under this assessment, the HCO falls under ‘Risk Category D’ being that the closest perennial water course is the Elvire River, it is greater than 4km away, and the soils are defined as fine sands. Based on the proposed recycled water quality to be supplied under the scheme, water quality falls within the FRP (Filterable Reactive Phosphorus) and IN (Inorganic Nitrogen) requirements for a Category D irrigation site (refer to Table 8).

Table 8 WQPN 22 limit vs recycled water quality Risk Category WQPN Inorganic

Nitrogen (as N) Limit WQPN Filterable Reactive Phosphorous (as P) Limit mg/L

Average WWTP TWW Inorganic Nitrogen (as N) mg/L

Average WWTP TWW Filterable Reactive Phosphorous (as P) mg/L

D 30 mg/L (480kg/ha/year)

7.5 mg/L (120/kg/hectare/year)

8.5 mg/L (150kg/ha/year)

2.26 mg/L (27kg/ha/year)

Mon

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(mg/

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Bioc

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(mg/

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E. C

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(CFU

/100

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Nitr

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nitr

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as N

(m

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pH

(labo

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Tota

l su

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solid

s (m

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Tota

l di

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solid

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Tota

l nitr

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(m

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Tota

l ph

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(m

g/L)

July 2017 26 15 >24000 <0.05 8.12 15 920 35 6.7 October 2017 11 25 390 0.31 8.91 95 1100 23 5.7 January 2018 5.5 65 260 0.052 7.88 80 980 22 4.8 April 2018 15 85 24000 0.094 7.95 210 1010 32 6.6

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The application rates of HCO was also assessed against the Turf Guidelines for the Swan Coastal Plain (Swan River Trust, 2014) – with application, rates adjusted for Halls Creek climatic conditions. Again, nutrient application rates were deemed low risk (Field Capacity, 2017). The nutrient risk assessment nominated sustainable irrigation rates for the HCO of no more than (Category D) 480kg/ha/yr of IN and 120kg/ha/year of FRP adherence will ensure irrigation application matches turf water demand and as a result environmental impacts are unlikely.

4.1 Management Control of the Proposed Recycled Water Scheme

4.1.1 Department of Health Approval The recycled water scheme will operate under a Shire of Halls Creek DoH Approval, to be obtained prior to scheme operations. Preliminary approval to proceed with establishment of the scheme was obtained from DoH in July 2018. The final DoH Approval for the Halls Creek Recycling Scheme will specify conditions to operate, including monitoring requirements and recycled water quality targets in accordance with ‘Low Exposure Risk’ schemes.

4.1.2 Recycled Water Supply Agreement A Recycled Water Supply Agreement (RWSA) between Water Corporation and Shire of Halls Creek is currently being finalised. This RWSA stipulates conditions and requirements for the supply and use of the recycled water, including:

• roles and responsibilities of both the supplier (Water Corporation) and the recipient (Shire of Halls Creek);

• permitted uses of the recycled water; • recycled water entitlement; • specifying the ‘Delivery Pont’- the location within the recycled water scheme which

delineates responsibility of the recycled water; • supplier and recipient infrastructure obligations; and • water quality requirements at the Delivery Point.

The term of the RWSA will be ten years from the date of execution. The RWSA is required to be finalised and executed before DoH will grant final approval to operate the scheme.

4.1.3 Recycled Water Quality Management Plan The Recycled Water Quality Management Plan (RWQMP) will outline the source, supply and management of recycled water for approved uses by the Shire of Halls Creek. The RWQMP has been prepared jointly by Shire of Halls Creek and Water Corporation staff and will be finalised prior to the scheme being granted DoH approval to operate. The RWQMP follows the principles of the Australian Guidelines for Water Recycling: Health and Environmental Risks (Phase 1) (2006) and DoH Guidelines for the Non-potable Uses of Recycled Water in Western Australia (2011) and includes:

• water quality objectives for ‘Low Exposure Risk’ schemes at the point of use; • public health risk assessment and mitigation (including ensuring adequate watering times,

public access restrictions, not watering after wet weather events, etc.); • Identification of hazards and critical control points; • how the scheme will be operated (including disposal of water that does not meet

specifications); • monitoring plan (both during commissioning and operations);

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• employee training and public education; • incident and emergency response; • community involvement and education; • documentation and reporting; and • evaluation and audit.

5 Proposed Activities This application is to allow for the construction of the following assets and works:

5.1 Evaporation Pond Works • Installation of an internal diving wall in the existing 7.1 ha Evaporation Basin to create

Evaporation Basins B and C o Evaporation Basin B (5.28 ha, depth 1.8 m) and Evaporation Basic C (1.82 ha.,

depth 2.0 m). • Construction of an additional 3.7 ha Evaporation Basin A, with an operation depth of

1.55 m. The basin is to be lined with Bituminous Geomembrane liner. • All basins are to be relined with a Bituminous Geomembrane liner (Permeability is > 10-

9 m/s complying with Water Quality Protection Note 26: Liners for containing pollutants, using synthetic membranes

5.2 Treatment Pond Works • Construction of an additional facultative treatment (Facultative Pond No. 1) and maturation

pond (Maturation Pond No. 1). • Refurbishment of the four existing wastewater treatment ponds (Facultative Ponds No. 2

and 3 and Maturation Ponds No. 2 and 3) such that they: o all relined with Bituminous Geomembrane Liner o embankments altered to a 4:1 embankment slope o embankments are adequately raised such as 500 mm freeboard from TWL is

provided. • Configuration of the resultant six ponds for parallel operation of the three facultative ponds

and series operation of the three maturation ponds. The volume of the six ponds provides 25 days hydraulic retention at the maximum month WWTP inflow, including the provision of baffle curtains in the three maturation ponds to reduce short circuiting.

• Disposal pump station to pump TWW from Maturation Pond No.3 to Evaporation Basin A; • Installation of a Geobag staging bund at the WWTP to be lined to WQPN 26 requirements,

and to include a return drain line for sludge leachate to be directed back to the facultative ponds.

• Construction of drainage channel around the WWTP to capture stormwater runoff and direct away from the WWTP.

5.3 Discharge Point Works • Tablet chlorine disinfection system on the discharge outlet pipe (downstream of the V notch

weir).

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• Installation of an access chamber on the overflow from Evaporation Basin C, including online level monitoring and a V notch weir for monitoring and quantifying discharges with a high level alarm linked to SCADA (monitoring).

5.4 Recycled Water Scheme Works WWTP works:

• Installation of two recycled water pumps from Maturation Pond 3 (Reuse Pump Station). • Construction of a treated wastewater management (TWWM) compound, including course

screen filtration and a chlorine gas disinfection system. • Installation of a new solar power supply, including instrumentation, control and

communication equipment. • Permanent diesel generator and external self bunded fuel tank to provide backup power for

three days operation if solar power is not available.

Offsite works: • A 1.8 km DN100 PVC-O potable water supply main to the WWTP. • Pigging of an existing unused ‘cut and capped’ DN150 AC pressure main (pigged material

discharged back to the WWTP for treatment in the ponds). • A 1.6 km DN150 PVC-O extension of the existing DN150 AC pressure main along Duncan

Highway to the irrigation site (HCO) (refer to Attachment 2e Appendix C). • Installation of a new double-skinned 200 kL steel sheet and liner tank, to be used to store

bore water for supply to the SHC Aquatic Centre. • Installation of a new inlet to the existing 200 kL Irrigation Tank, including SCADA linked

magnetic flowmeter; • Installation of SCADA linked pressure (level) instrumentation on the existing 200 kL

Irrigation Tank; • Installation of a new automated scour valve on the low-level outlet of the existing 200 L

Irrigation Tank; • Connection of the existing 200 kL tank scour to the local sewer network via a DN100 PVC-

O scour main. • Installation of tertiary barriers and signage to meet DoH requirements at the HCO.

5.5 Commissioning Summary

The approval is to allow commissioning of

• Facultative Ponds • Maturation Ponds • Installation of the geobag staging bund • Evaporation Pond A, B and C • TWWM Infrastructure • Recycled Water Scheme infrastructure • Discharge Point monitoring treatment infrastructure.

After Commissioning the approval is to allow the operation of

• Facultative Ponds • Maturation Ponds

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• Geobag staging bund • Evaporation Pond A, B and C • TWWM Infrastructure • Discharge Point monitoring a treatment infrastructure • Supply of TWW to the Halls Creek Oval.

5.6 Description of works

5.6.1 Construction and Commissioning and Operational Activities Construction activities are detailed into seven estimated phases in Table 9 below.

Table 9 Construction activities broken into phases

Phase Period Detail 1 April to June 2019 • Construction of New Facultative and

Maturation Ponds (lined with BGM) and Evaporation Basin A and recycled water pipeline extension.

• Recycled water pipe remains offline until treatment plant works completed.

• Existing Facultative, Maturation and Evaporation Ponds remain online and maintain existing capacity.

2 July to September 2019 • Facultative and Maturation Ponds 1 are complete and undergo commissioning

• Desludging of Facultative and Maturation Ponds (drain and dry method).

• Continued Construction of Evaporation Pond A (includes lining BGM).

• Refurbishment of Facultative and Maturation Ponds 2 and 3 (includes lining with BGM). Capacity of WWTP maintained

3 October to November 2019 • Evaporation Pond A remains offline. All

Facultative and Maturation Ponds are online and functional.

4

December 2019 to March 2020 • No construction occurring at WWTP in normal storage mode to existing evaporation basin due to wet season.

5 April to August 2020 • Evaporation Pond A commissioned and

temporary pumping from Maturation Pond 3 to Evaporation Pond A (maintained capacity of WWTP).

• Original Evaporation pond is refurbished

(relined and split into two basin B and C – intersecting wall)

• Construction of Disposal Pump Station.

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Phase Period Detail • Construction of Reuse Pump Stations • Construction of TWWM Facility including

filtration and chlorination systems • Commissioning of Disposal Pump Station

6 September to November 2020 Commission and Operation of Evaporation Pond B and C

Construction of required connections and communications to HCO site

7 December 2020 Operation of Treatment Plant, connecting

pipework to oval infrastructure. Recycled Water Scheme commissioning.

Commissioning of Reuse Pump Stations and TWWM facility

***Refer to Figure 5 in Appendix C: Halls Creek WWTP Upgrade and TWWM Schedule of Works. ***Note works phases are estimates; and phase dates and timing are subject to change.

6 Regulatory Context and Approvals

6.1 Environmental Protection Act 1986 – Part V The upgrade of Halls Creek WWTP will occur within the proposed premise boundary depicted in Figure 1. A licence currently exists (L6268/1991/10) for the operation of the Halls Creek WWTP.

6.2 Other Approvals

• No de-watering required, no 5C licence required.

• Clearing exemption expected however subject to Water Corporation internal CPS assessment.

• Obtained Aboriginal Heritage Approvals (Section 18, Regulation 10).

7 Stakeholder Consultation • Consultation for the establishment of the Halls Creek Recycled Water Scheme has been

conducted with the Shire of Halls Creek.

• Consultation of the WWTP location and ongoing operation has been carried out with DoH and DWER.

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8 Risk Assessment A risk assessment has been prepared to consider the risks of the construction and ongoing operation of Halls Creek WWTP and recycled water scheme. The risk assessment has been based on the DER Guidance Statement: Risk Assessments (DER, 2017).

8.1 Bituminous geomembrane

The bituminous geomembrane (BGM) lining solution that is to be used to line the existing and new treatment pond / basin facilities at the WWTP, comprises a bitumen impregnated geotextile (achieving a permeability of less than 6*10-14) with a sand coated surface for texture. This was considered the most appropriate liner for installation at the WWTP (GHD, 2018a), as it provides a sufficiently low permeability barrier whilst being robust in terms of both maintenance, trafficability and a high temperature resistance. In particular the capability of BGM to be able to accommodate extended periods during which the evaporation basins are dry, as is expected based on water balance modelling of the upgraded WWTP.

8.2 Desludging

The refurbishment of the existing facultative and maturation ponds, will require desludging. Furthermore, as part of ongoing operational maintenance desludging will be undertaken at intervals of between 10 and 20 years or as required through routine surveillance of sludge depth. Table 9a details methodology of desludging during construction and operation.

Table 9a Desludging method construction and operation

Stage Description

Construction 1 Pond is taken offline / bypassed 2 Pond is mechanically drained of clear fluid using a submersible pump, which transfers fluid to another pond

in the treatment process. 3 Ponds are to be excavated (Drain and Dry and Cut) and sludge material transported to constructed hard

stand sludge drying areas lined with bunding. 4 The filtrate is drained by gravity back to the start of the treatment process or to be contained and managed

within the hard stand lined area. Operation 1 Pond is taken offline / bypassed 2 Drain and Dry Method: Sludge removed mechanically and placed on hard stand area with a leachate drain

back to the treatment ponds Or Online Desludging: Pond is kept online and a sludge rat traverses the pond surface suckering sludge via pipe to geobags contained with the hard stand area and slurry water content is returned to the treatment pond

3 Sludge left on hardstand area either in or not in geobags would be disposed of either to landfill once dried or sent for applicable re-use

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** Desludging methods may change but will be carried in accordance with the Western Australian guidelines for bio solids management (2012).

8.3 Emergency Discharge during Construction and Wet Season Periods

The likelihood of discharge of TWW from the Halls Creek WWTP during construction works is considered rare. The construction works will not increase the risk of emission of TWW to the tributary of China Wall Creek as no construction works will be conducted in the Wet Season and storage capacity will be retained during and after works stages. In the event of a high rainfall (which would be the likely cause of an overflow event), the discharge of TWW will be managed by the following controls:

• Upon discovery notification to DWER Pollution Watch as required by the licence conditions or S72 requirements.

• Upon discovery notification to the Shire of Halls Creek of the incident as per the existing discharge notification agreement.

• Upon discovery notification to the Department of Health of the incident. • Contingency Tablet chlorination (basket) of the TWW discharges point (to the tributary of

China Wall Creek. • Mosquito Management (baiting) of pooled water surrounding the discharge area. • Deployment of Health Warning Signage at China Wall Pool Creek and the area of

discharge tributary of China Wall Pool Creek.

8.4 Post-construction phase

Following completion of construction works the WWTP facility will have been expanded to provide treatment capacity sufficient to achieve a 25 day retention time minimum within the treatment ponds, and able to provide sufficient capacity for currently projected population growth at Halls Creek. The increased capacity of the evaporation ponds is sufficient to provide a greater buffer during high rainfall events, minimising the volumes discharged to the environment during such events.

8.5 Overview

Since the construction and post-construction risk assessment is for the same site, there is a degree of overlap between the two. Consequently, the initial source-pathway-receptor summary for the two scenarios are combined, with an individual detailed risk assessment completed for both the construction and post-construction phase. A schematic outline of the two settings is presented in Figure 6 and Figure 7.

Potential emission sources are summarised in Table 10, with contaminants of potential concern summarised in Table 11. Potential exposure pathways – detailing differences between construction and post-construction phases – are summarised in Table 13, and potential receptors in Table 14. A detailed assessment of the source-pathway-receptors is presented in Table 15.

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8.6 Potential emission sources

Potential emission sources and associated contaminants of concern are summarised in Tables 10 and 11 respectively.

Table 10 Potential emission sources – construction / post-construction

Emission source Construction phase Post-construction phase

Untreated Wastewater (Facultative / Maturation Ponds)

Discharge directly to the environment during heavy rainfall events (via evaporation pond). Existing capacity will be maintained at pre-construction level to ensure no change in risk level compared to normal operations.

Construction to incorporate chlorination dosing (via tablet) at the point of overflow discharge (via evaporation pond). Increased capacity and freeboard over current operations will reduce frequency of overflows.

Treated Wastewater (Evaporation Pond)

Facultative and Maturation (sludge) Sludge removed during construction Sludge removed as part of regular maintenance (10 to 20 year intervals or as required)

Evaporation ponds(TWW)

Diesel generator / bunded fuel tank (hydro carbons)

Permanent system to be installed during construction phase, but temporary system to be used during construction to pump TWW water to Evaporation Basin A during refurbishment of existing evaporation basin.

Permanent bunded system.

Other offsite / regional diffuse sources Surrounded by pastoral land, no significant sources of contamination. Construction Machinery (Noise) Earth works on all WWTP ponds, TWWM Not applicable

and Sludge compounds Construction Machinery Earth Works (Dust)

Earth works on all WWTP TWWM Not applicable and Sludge compounds

Table 11 Key contaminants of potential concern (CoPC)

Contaminant Comment

Nutrients (N, P, NOx, NHx) Some groundwater and surface water monitoring undertaken to date. No analysis of heavy metals, phenols or PFAS undertaken as part of regular effluent quality monitoring. Phenols have not been encountered at levels of concern in Western Australian WWTPs. Phenol impacts are associated with wastewater facilities with significant industrial trade waste or landfill leachate acceptance. The Water Corporation does not accept landfill leachates and does not consider phenols to be a risk in regional locations. PFAS are known to be ubiquitously present at WWTPs at concentrations below drinking water health criteria. PFOS is known to marginally exceed the 99% ecological protection values outlined in the NEMP (Feb 2018). The Water Corporation is working closely with DWER on the management of diffuse PFOS impact in wastewater at a Statewide level and does not consider operational monitoring.

Heavy metals Phenols PFAS Microbial pathogens (E.coli and Enterococci)

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8.7 Potential exposure pathways

Potential exposure pathways during the construction and post-construction phase work are summarised in Table 12.

Table 12 Potential exposure pathways – construction / post construction

Item Pathway Construction phase Post-construction

Wastewater / sludge

Direct exposure to wastewater and / or sludge Pathway present Pathway present Contaminants leaching through the unsaturated zone to groundwater

Pathway present Pathway severed by BGL

Discharge of treated effluent to the adjacent creek during period of high rainfall

Pathway present Pathway present, but capacity of WWTP increased so reduced

Groundwater Lateral transport of dissolved phase contaminants


Off-site abstraction and incidental direct contact with impacted by groundwater by down-hydraulic gradient bore users.


Abstraction and ingestion of impacted groundwater by livestock.

Pathway potentially present

Pathway potentially present

Surface water Downstream transport of contaminants Pathway present Pathway present, but capacity of WWTP increased

Odour Wind migration of odours (operation) Pathway present Pathway present Noise Wind migration of noise (Construction) Pathway present Not Applicable Dust Wind migration of dust (Construction) Pathway present Not Applicable

8.8 Potential receptors Potential receptors associated with the WWTP are summarised in Table 13.

Table 13 Potential receptors – construction / post construction

Item Comment

Groundwater – Town Water Supply The WWTP falls within the P1 DWPSA of the Halls Creek TWS, and within the well-head protection zone of three of the production bores. The three production bores (4/92, 7/75 and 7/90).

Groundwater Dependent Ecosystems No known groundwater dependent ecosystems have been identified in the environs of the WWTP

Groundwater Users (other) There are several known abstraction bores, other than those of the TWS (discussed above) in the environs of the WWTP, notably associated with a cattle yard approximately 1.1 km southeast of the WWTP.

Surface water – China Wall Creek An ephemeral creek immediately adjacent to the WWTP site.

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Item Comment

Surface water – China Wall Pool A site of amenity value approximately 2.5 km southeast of the WWTP, downstream of the site along the course of China Wall Creek.

Surface water users – Agricultural water use (livestock)

Approximately 100m south of the WWTP, adjacent to China Wall Creek is a wind pump, which is anticipated to abstract water from groundwater. [no specific details available] The site is reportedly disused (C.Chaudhry, Pers. Comms, 23/07/2018).

Human Health – on site maintenance workers

Operators routine maintenance

Human Health – China Wall Pool users (amenity)

China Wall Creek Pool is often used by recreational swimmers

Human Health – Residents (amenity) Resident with 1km of the WWTP

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Table 14 Wastewater treatment plant risk assessment (construction and post-construction)

Source Zone Contaminant of potential concern

Potential exposure pathways

Potential receptors

S-P-R linkage status

Discussion Data gaps

WWTP water treatment areas, incorporating: Settling

ponds Evaporation

pond Sludge

processing facility

Residual soil contamination from overflow events

Nutrients (N, P, NOx, NHx)

Infiltration of wastewater with contaminants leaching through the unsaturated zone to groundwater, with subsequent lateral transport of dissolved phase

Abstraction Followed by ingestion and / or incidental contact with impacted groundwater by off-site bore users (including livestock)

Potentially complete

The WWTP lies within the DWPSA for the Halls Creek town water supply. Groundwater flow direction from the WWTP toward nearby production bores has been induced by pumping from the town borefield. The WWTP lies within the wellhead protection distance (500m) of three of the town water supply bores. These bores are not currently active. Installation of the BGL should sever this pathway for the post-construction phase.

Recent drilling (2017) has expanded the available monitoring bore network near the WWTP.

Heavy metals Phenols PFAS Microbial pathogens (E.coli and Enterococci)

Microbial pathogens (E.coli and Enterococci)

Direct contact (i.e. ingestion or dermal contact) with impacted soils or waters.

On-site maintenance workers

Incomplete Operational controls are in place to minimise exposure to wastewater and potentially contaminated soil.

Odours Airborne migration Nearby residents, visitors and commercial property owners/users.

Incomplete No odour complaints noted in the AER documentation (2004 to present). Closest residential property approximately 1 km west of the WWTP.

WWTP Overflow Discharge


Overflow of wastewater to the China Wall Creek and China Wall Pool

Ingestion and / or incidental contact with impacted surface water by off-site

Potentially complete

The WWTP may overflow, during extreme (>1/10 year) rainfall events, leading to discharge of partially untreated water to the adjacent creek. The volumes discharged would be significantly diluted by the

Water Corporation installation a V Notch monitoring device as apart of upgrade.

Microbial pathogens (E. coli and Enterococci) Heavy metals Phenols

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Potential receptors



PFAS users rainfall event.

There is a nearby windpump anticipated to be providing water for livestock, immediately south of the WWTP, which may be at risk – it is not clear where the water is sourced from (groundwater (considered likely) or surface water). Following the site upgrades the volume of overflow water and recurrence interval should be reduced, furthermore the discharged water will have additional level of treatment (chlorine dosing at the overflow outflow point) than is currently achieved.

WWTP soil / pond liner material (during construction and subsequent sludge management)


Direct contact (i.e. ingestion or dermal contact) with impacted soils

Ingestion and / or incidental contact with impacted soils by on-site workers during construction phase

Incomplete Operational controls to minimise exposure to wastewater and potentially contaminated soil. Material to be transported to local landfill in accordance with current best practice. Installation of the BGL and construction of an appropriately bunded geobag area should sever this pathway for the post-construction phase.

Chemistry of current pond liner / sludge material is unknown. Chemistry of new pond liner and sludge drying area is known.

Microbial pathogens (E.coli and Enterococci) Heavy metals Phenols PFAS

WWTP soil / pond liner material (disposal)


Leaching to groundwater

Groundwater Incomplete Use of appropriate staging bund for on-site treatment

Excavated sludge material to be contained within geobag staging bund at WWTP site Excavated sludge material to be disposed of in accordance with best practice at the Halls Creek landfill

Chemistry of current pond liner / sludge material is unknown. Chemistry of future pond liner / sludge material will

Microbial pathogens (E.coli and Enterococci) Heavy metals Phenols

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Potential receptors



PFAS Disposal to suitable landfill site following onsite treatment

site. Material subject to suitable testing prior to disposal at landfill to minimise residual risks prior to disposal.

be known.

Untreated Wastewater Pipeline (from Halls Creek to WWTP)


Potential leakage from pipeline, leading to infiltration of untreated wastewater with contaminants leaching through the unsaturated zone to groundwater, with subsequent lateral transport of dissolved phase.

Abstraction followed by ingestion and / or incidental contact with impacted groundwater by off-site users.

Potentially complete – although currently no strong evidence of deteriorating water quality at the nearby TWS bores 3/92 and 1/93 (<100 m away from pipeline).

Potential for the pipeline containing untreated effluent to leak, although no deterioration in groundwater quality noted at 3/92 and 1/93. Condition survey conducted no leakage identified

Microbial pathogens (E. coli and Enterococci) Heavy metals Phenols PFAS

Diesel generator and fuel source

Hydrocarbons Potential leakage of fuel to surface water or infiltration through unsaturated zone to groundwater

Groundwater / nearby surface water (China Wall Creek)

Incomplete – use of appropriately bunded system.

Provided both any temporary and subsequently the permanent generator (and fuel) system are appropriately bunded the risk to the environment and site users should be minimal.

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Potential receptors



Construction Works (Dust Emissions)

Migration via wind or vehicle movement

Residents Incomplete Generation of dust may occur locally at site during proposed earthworks required for the construction of the Halls Creek WWTP Ponds and TWWM Compound. Potential sources of generation of dust emissions during construction are from the movement of soil by mobile plant and the generation of dust from wind action across open areas of soils (e.g. disturbed areas, stockpiles). The objective and performance indicators will be included in the EMP for the project. The contractor responsible for the works will be contractually bound to take all reasonable and practicable measures to meeting the CEMF and this objective. Objective Activities do not unreasonably affect the amenity of surrounding landowners and users. Performance Indicators • No visible dust plumes

extending more than 10m off the development envelope boundary; and

• No substantiated complaints relating to dust impacts

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Potential receptors



Construction Works (Noise Emissions)

Migration via wind Residents Incomplete Given the scale and duration of works it is expected that dust generation would not impact on surrounding vegetation and impacts would therefore be limited to amenity. Dust generation from site could potentially extend to nearby residents located approximately 1km away from the disturbance area. It is expected that with standard dust management practices in place the consequence would be localised, temporary and minimal in nature. This would equate to a consequence rating of Slight. With standard management practices it is expected that dust emissions of this nature would be associated with abnormal climatic/weather conditions and therefore would probably not occur in most circumstances. The likelihood of Unlikely the risk rating is Low.

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Potential receptors



Operation and Construction of Treatment Ponds(Odour)

Migration via wind Residents Potentially Complete

Construction Potential sources of odour from the Halls Creek WWTP could originate during the desludging process. During desludging weather condition will be considered and works will not be conducted in high wind situations towards residential receptors. Operation – No odour complaints in reference to Halls Creek WWTP historically. Distance to nearest resident receptor is significant (1km)


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9 Risk assessment of S-P-R linkages

9.1 Overview

The following assessment of S-P-R linkages identified as potentially complete in the construction and / or post-construction CSM has been developed for the Halls Creek WWTP with reference to the Environmental Risk Assessment Guidance Document. The risk assessment does not include potential off-site sources of contamination as these are not under the direct control of the Water Corporation.

9.2 Detailed risk assessment methodology

The basis for the risk assessment process has been adapted from the DWER (2017) Guidance Statement: Risk Assessments as follows:

• Is an emission occurring (likelihood)?

• Is a receptor being exposed to the emission through an identified actual or likely pathway? (Likelihood).

• What are the potential adverse effects to the receptor from exposure to the emission? (Consequence).

9.2.1 Emission likelihood

The likelihood risk rating criteria use, as summarised in Table 15a, has been adapted from the Water Corporation S389 and DER (2017) Risk Assessment Guidance Document.

Table 15a Likelihood of risks occurring adapted from Water Corporation S389 and DER (2017)

Rank Descriptor Predicted Frequency Known Frequency

A Almost certain Expected to occur in most circumstances Event is occurring permanently or has occurred more than once a year

B Likely Will probably occur in most circumstances Has occurred once per year C Possible Could occur at some time Has occurred once in 5 years D Unlikely Will probably not occur in most circumstances Has occurred once in 10 years E Rare May only occur in exceptional circumstances Has occurred once in 30 years

The likelihood of a risk event occurring is predominantly based on treatment and disposal concentrations or volumes and the proximity of potential receptors to the site, with the closer a receptor is to the site the increased likelihood of an event occurring.

9.2.2 Environmental risk likelihood

The likelihood of a risk to environmental receptors is determined by the extent to which the pathway is demonstrated. The pathway for wastewater is demonstrated as summarised in Table 15.


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Table 15b Pathway assessment

Item Criteria

Receptor Distance Groundwater Depth Gradient / flow direction Soil type and nutrient load capacity Surface water Ability for surface runoff / overflow Contaminant Contaminant load

The environmental risk likelihood scale is presented in Table 16.

Table 16 Environmental risk likelihood factors

Rank Descriptor Distance to sensitive environmental receptor

Depth to groundwater Nutrient load and soil type

A Almost certain <100 m <3 mbgl B Likely 101 to 500 m 3 to 10 mbgl Exceeds WQPN22 C Possible 501 to 1000 m 10 to 25 mbgl D Unlikely 1,001 to 2,000 m > 25 mbgl Does not exceed WQPN22 E Rare > 2,000 m - Reference Adapted from DER (2016)

Draft Environmental Standard: Composting (Table 1, Pg.6)

Adapted from DER (2016) Draft Environmental Standard: Composting (Table 3, Pg.7)

Department of Water (2008) Water Quality Protection Note 22 – Irrigation and Nutrient Rich Wastewater

9.2.3 Human health and amenity

Table 17 Human health risk likelihood factors

Rank Descriptor Distance to abstraction bore

Depth to groundwater Concentration of CoPCs > human health criteria

A Almost certain <100 m <3 mbgl B Likely 101 to 500 m 3 to 10 mbgl Exceeds human health criteria C Possible 501 to 1000 m 10 to 25 mbgl D Unlikely 1,001 to 2,000 m

> 25 mbgl Does not exceed human health criteria

E Rare > 2,000 m - Reference Adapted from DER (2016)

Draft Environmental Standard: Composting (Table 1, Pg.6)

Adapted from DER (2016) Draft Environmental Standard: Composting (Table 3, Pg.7)

DER (2014) Assessment and Management of Contaminated Sites


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Table 18 Amenity risk likelihood factors

Rank Descriptor Distance to residential / commercial property Odour and / or noise complaints

A Almost certain <600 m Greater than one per year B Likely 600 to 1000 m Once per year C Possible 1000 to 1600 m One per 5 years D Unlikely 1600 to 2200 m One per 10 years E Rare >2,200 m One per 20 years Reference Adapted from DER (2016) Draft Environmental

Standard: Composting – Table 10, pg. 14 Adapted from Water Corporation S389 Risk Assessment Criteria

9.2.4 Consequence risk rating

Consequences of risk have been broadly divided into either environmental or public health and amenity risks and have been adapted from the risk assessment guidance (DER, 2016, Water Corp 2018) to include risks specific to WWTPs. Table 19 presents the consequence criteria from the Water Corporation Risk Assessment Matrix (S389) and the DER (2017) Guidance Statement: Risk Assessments, to allow comparative risk rating results as perceived by Water Corporation and the regulator.


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Table 19 Consequences of risks occurring adapted from Water Corporation S389 and DER (2017)

Rank* Environment [Water Corporation S389]

Environment [DER, 2017] People and public (human health) [Water Corporation S389]

Social amenity [Water Corporation S389]

Public health and amenity (includes air and water quality, noise and odour) [DER, 2017]

5 –

Cata

stro

phic

/ Sev

ere

Significant extensive impact on the environment

Impacts are irreversible and / or permanent

On-site impacts catastrophic Off-site impacts local scale: high level or

above Off-site impacts wider scale: mid-level or

above Mid to long term or permanent impact to

an area of high conservation value or significance^

Specific Consequence Criteria for environment are significantly exceeded

Multiple fatalities, and / or

Onset of life shortening occupational illness for multiple persons

Significant extensive impact on social amenity

Impacts are irreversible and / or permanent

Loss of life Adverse health effects: high

level or ongoing medical treatment

Specific Consequence Criteria for public health are significantly exceeded

Local scale: permanent loss of amenity

4 –

Maj

or

Extensive, long term impact on the environment

Recovery – several years to several decades

Uncertain reversibility of remediation

On-site impacts high level Off-site impacts local scale: mid-level Off-site impacts wider scale: low-level Short term impact to an area of high

conservation value or special significance^

Specific Consequence Criteria for environment are exceeded

Single fatality, and / or Injury / illness resulting

in significant permanent disability or life shortening illness

Extensive, long term impact on social amenity

Recovery – several years to several decades

Uncertain reversibility of remediation

Adverse health effects: mid-level or frequent medical treatment

Specific Consequence Criteria for public health are exceeded

Local scale impacts: high level impact to amenity


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Rank* Environment [Water Corporation S389]

Environment [DER, 2017] People and public (human health) [Water Corporation S389]

Social amenity [Water Corporation S389]

Public health and amenity (includes air and water quality, noise and odour) [DER, 2017]

3 –

Mod

erat

e

Long term impact on the environment

Recovery – several months to several years

Challenging remediation

On-site impacts: mid-level Off-site impacts local scale: low-level Off-site impacts on wider scale: minimal Specific Consequence Criteria for

environment are at risk of not being met

Serious injury / illness, requiring specialist medical treatment or hospitalisation, resulting in loss of functional ability (Restrictive Duties Injury (RDI)) to time off work (Lost Time Injury (LTI)).

Long term impact to social amenity

Recovery – several months to several years

Challenging remediation

Adverse health effects: low-level or occasional medical treatment

Specific Consequence Criteria for public health at risk of not being met

Local scale impacts: mid-level impact to amenity

2 –

Min

or

Short term or low-level long-term impact on the environment

Recovery – 1 week to several months

Easy remediation

On-site impacts: low level Off-site impacts local scale: minimal Off-site impacts wider scale: not

detectable Specific Consequence Criteria for

environment likely to be met

Injury / illness requiring medical treatment, nil loss of function ability (Medical Treatment Injury (MTI))

Short term or low-level mid-term impact to social amenity

Recovery – 1 week to several months

Easy remediation

Specific Consequence Criteria for public health are likely to be met

Local scale impacts: low-level impact to amenity

1 –

Insig

nific

ant/

sli

ght

No lasting effect on the environment

Recovery – less than 1 week

Cosmetic remediation

On-site impact minimal Specific Consequence Criteria for

environment will be met

Injury / illness requiring no treatment or first aid treatment only (Minor Injury (MI))

No lasting effect on social amenity

Recovery – less than 1 week

Cosmetic remediation

Specific Consequence Criteria for public health will be met

Local scale: minimal impacts to amenity

* consequence ranking nomenclature from both Water Corporation S389 and DER (2017) have been included as appropriate


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9.3 Risk rating

Based on site specific data the risk assessment matrix has been completed separately for environmental, human health and amenity risks identified as likely incomplete, unknown or complete in the construction and future conceptual site model. The likelihood and consequence of each risk has been assessed separately with reference to the Water Corporation S389 risk assessment matrix as presented in 20.

Table 20 Risk rating matrix adapted from Water Corporation S389 and HSEAA-P-191 High Potential Incident Procedure

Consequences Level of Risk

5 – catastrophic High (17) High (20) Extreme (22) Extreme (24) Extreme (25) 4 – major Medium (11) High (18) High (19) Extreme (21) Extreme (23) 3 – moderate Low (6) Medium (10) High (14) High (15) High (16) 2 – minor Low (3) Low (5) Medium (9) High (12) High (13) 1 – insignificant Low (1) Low (2) Low (4) Medium (7) Medium (8) Likelihood E – rare D – unlikely C – possible B – likely A – almost certain

For comparative risk rating results between the Water Corporation and the regulator, the risk table from the DER (2017) documentation has been adapted to allow comparison with the Water Corporation matrix (S389), Table 21.

Table 21 Risk rating matrix adapted DER (2017) Guidance Statement: Risk Assessments

Consequences Level of Risk

5 – catastrophic High (18) High (20) Extreme (22) Extreme (24) Extreme (25) 4 – major Medium (12) High (14) High (19) Extreme (21) Extreme (23) 3 – moderate Medium (7) Medium (11) Medium (13) High (16) High (17) 2 – minor Low (3) Medium (5) Medium (6) Medium (10) High (15) 1 – insignificant Low (1) Low (2) Low (4) Medium (8) Medium (9) Likelihood E – rare D – unlikely C – possible B – likely A – almost certain


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10 Halls Creek WWTP construction phase detailed risk assessment

10.1 Overview

Site specific information has been used to complete the following risk rating of identified environmental, human health and amenity risks at the Halls Creek WWTP under construction phase operational conditions. Potential risks have been rated using the Water Corporation Risk Assessment Matrix (S389) and DER (2017) Guidance Statement: Risk Assessments in order to rate and compare the risks as perceived by the Water Corporation and DWER.

The risk assessment, Table 22 is based on the S-P-R linkages identified in the construction phase conceptual model and does not include potential sources of contamination from off-site sources as these sites are not under the direct control of the Water Corporation.

Controls for the management of identified risks are included to allow an assessment of residual risk following implementation of the controls.


Page 40

Table 22 Halls Creek construction phase detailed risk assessment

Receptor Risk Likelihood Consequence (Water Corporation S389)

Consequence (DER, 2017)

Risk rating (S389)

Risk rating (DER, 2017)

Recommended management of risk requirements (controls)

Residual risk (S389)

Residual risk (DER, 2017)

Environmental

China Wall Creek

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS)

Close proximity to WWTP (<100m), but WWTP designed to accommodate 1 in 10 year flood events. Emission likelihood [Unlikely, D]

Short term or low level long term impact on the environment [Minor, 2]

Off-site impacts on local scale: low level [Minor, 2]

Low (5) Medium (5)

Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or site specific consequence criteria [Recreational Waters Guidelines] Construction work undertaken during dry season. Overflow events have only occurred during wet season. The construction is to be phased such that the overall capacity of the WWTP is maintained or increased from current capacity during the construction programme. Additionally, if discharge was to occur during a significant rainfall event TWW would be disinfected via tablet chlorination at the point of discharge. Predicted likelihood (dry season): Rare, E Predicted consequence: Minor, 2

Dry season: Low (3) Wet season: Low (5)

Dry Season: Low (3) Wet Season: Medium (5)


Page 41



Risk rating (S389)





China Wall Pool


Distance to receptor (>2,000 m) [Rare, E]

Short term or low level long term impact on the environment [Minor, 2]

Off-site impacts: low level [Minor, 2]

Low (3) Low (3) Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or site specific consequence criteria [Recreational Waters Guidelines] Construction work undertaken during dry season. Overflow events have only occurred during wet season. The construction is to be phased such that the overall capacity of the WWTP is maintained or increased from current capacity during the construction programme. Additionally, if discharge was to occur during a significant rainfall event TWW would be disinfected via tablet chlorination. Predicted likelihood (dry season): Rare, E Predicted consequence: Minor, 2

Dry season: Low (3) Wet season: Low (3)

Dry Season: Low (3) Wet Season: Low (3)

Livestock

Livestock water (via wind pump)


Distance to receptor (<200 m) [Likely, B]

Short term or low level long term impact on the environment. [Minor, 2]

Off-site impacts on local scale: low level. [Minor, 2]

High (12) Medium (10)

Confirmation of water source for wind pump – may be up gradient of treatment plant discharge point. Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or specific consequence criteria [Livestock Drinking Water Quality]. Predicted Likelihood, D Predicted Consequence, Insignificant, 1

Low (2) Low (2)

Human Health


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Risk rating (S389)





TWS bores within wellhead protection zone distance of WWTP (<500 m)

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) leaching from the WWTP to abstraction bores 4/92, 7/75 and 7/90

Depth to groundwater (>30 mbgl) [Unlikely, D]

Leachable concentrations of CoPCs from sludge at WWTP are unknown. Potential for long-term impact to the environment with recovery time of several months to years. [Moderate, 3]

Leachable concentrations of CoPCs from sludge at WWTP are unknown. Specific Consequence Criteria for environment are at risk of not being met [Moderate, 3]

High (15) High (16) Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or specific consequence criteria [Drinking Water Quality] Predicted likelihood: Likely, B (based on distance to receptor) Predicted consequence, insignificant, 1

Medium (7) Medium (8)


TWS bores beyond wellhead protection zone distance of WWTP (>500 m)

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) leaching from the WWTP to remainder of TWS (excluding 4/92, 7/75 and 7/90)

Depth to groundwater (>30 mbgl) [Unlikely]

Leachable concentrations of CoPCs from sludge at WWTP are unknown. Potential for long-term impact to the environment with recovery time of several months to years. [Moderate, 3]

Leachable concentrations of CoPCs from sludge at WWTP are unknown. Specific Consequence Criteria for environment are at risk of not being met [Moderate, 3]

Medium (10)

Medium (13)

Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or specific consequence criteria [Drinking Water Quality] Predicted likelihood: Unlikely, B (based on distance to receptor) Predicted consequence, insignificant, 1

Low (2) Low (3)

Distance to receptor (>1000 m) [Unlikely to rare]

Amenity


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Risk rating (S389)





China Wall Pool

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) in overflow water during large rainfall events

System designed to accommodate 1 in 10 year flood events. Emission likelihood [Unlikely, D]

Injury / illness requiring medical treatment, nil loss of function ability. [Minor, 2]

Short Term or low level mid-term impact to social amenity. [Minor, 2]

Low (5) Medium (5)

Community awareness programmes (signage, information) during overflow events, to minimise contact with overflow waters. Large amount of dilution of overflow effluent expected during heavy rainfall events. Additionally, if discharge was to occur during a significant rainfall event TWW would be disinfected via tablet chlorination at the point of discharge. Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or specific consequence criteria [Recreational Waters Guidelines]. Predicted Likelihood, D Predicted Consequence, Insignificant, 1

Low (2) Low (2)


11 Halls Creek WWTP post-construction detailed risk assessment

11.1 Overview

Site specific information has been used to complete the following risk rating of identified environmental, human health and amenity risks at the Halls Creek WWTP under the future operational conditions (i.e. post construction). Potential risks have been rated using the Water Corporation Risk Assessment Matrix (S389) and DER (2017) Guidance Statement: Risk Assessments in order to rate and compare the risks as perceived by the Water Corporation and DWER.

The risk assessment, Table 23, is based on the S-P-R linkages identified in the post-construction phase conceptual model and does not include potential sources of contamination from off-site sources as these sites are not under the direct control of the Water Corporation.



Table 23 Halls Creek post-construction phase detailed risk rating



Risk Rating (S389)

Risk Rating (DER, 2017)

Recommended Management of Risk Requirements (Controls)

Residual Risk (S389)

Residual Risk (DER, 2017)

Environmental

Groundwater CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) leaching from the WWTP

Depth to groundwater beneath WWTP >25 m. [D – Unlikely]

Low level long term impact on the environment [Minor – 2]

Off-site impacts – local scale: low level (Minor -2)

Low (5) Medium (5)

Installation of BGL during construction phase is anticipated to sever the existing pathway. Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or specific consequence criteria [Drinking Water Quality] Predicted likelihood, E, rare Predicted consequence, Insignificant, 1

Low (1) Low (1)

China Wall Creek

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) leaching from the WWTP

Overflow of WWTP during 1:10 year rain events. [D – unlikely]

Short term or low level long term impact on the environment – Minor (2)

Off-site impacts – local scale: low level (Minor – 2)

Low (5) Medium (5)

Overall capacity of the WWTP to retain water will have increased as a consequence of the construction works. Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or site specific consequence criteria [Recreational Waters Guidelines]

Low (1) Low (1)

China Wall Pool

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) leaching from the WWTP

Overflow of WWTP during 1:10 year rain events. [D – unlikely]



Low (5) Medium (5)

Low (1) Low (1)

Livestock

Livestock water (via wind pump)

CoPCs (nutrients, heavy metals, microbial pathogens,


Short term or low level long term impact on the

Off-site impacts on local scale: low level. [Minor, 2]


Confirmation of water source for wind pump – may be up gradient of treatment plant discharge point. Residual risk

Low (2) Low (2)




Risk Rating (S389)





phenols, PFAS) environment. [Minor, 2]

assumes concentrations of CoPCs are not elevated in comparison to background and / or specific consequence criteria [Livestock Drinking Water Quality]. Predicted Likelihood, D Predicted Consequence, Insignificant, 1

Human Health

TWS bores within wellhead protection zone distance of WWTP (<500 m)

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) leaching from the WWTP to abstraction bores 4/92, 7/75 and 7/90

Distance to closest bore ~250 m (7/90). [B – Likely]

Low level impact on the environment [Minor – 2]

Off-site impacts – local scale, low level [Minor – 2]


Installation of BGL is anticipated to sever the existing pathway. Review of need to maintain cessation of abstraction from 7/90, 2/89 and 4/92.

Low (3) Low (3)

TWS bores beyond wellhead protection zone distance of WWTP (>500 m)

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) leaching from the WWTP to remainder of TWS (excluding 4/92, 7/75 and 7/90)




Medium (10)

Medium (13)

Installation of BGL is anticipated to sever the existing pathway.

Low (2) Low (3)

Amenity

China Wall Pool

CoPCs (nutrients, heavy metals, microbial pathogens, phenols, PFAS) in

System designed to accommodate 1 in 10 year

Injury / illness requiring medical treatment, nil loss of function ability.

Short Term or low level mid-term impact to social amenity. [Minor,

Low (5) Medium (5)

Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or specific consequence criteria [Recreational

Low (2) Low (2)




Risk Rating (S389)





overflow water during large rainfall events

flood events. Emission likelihood [Unlikely, D]

[Minor, 2] 2] Waters Guidelines]. Community awareness programmes (signage, information) during overflow events, to minimise contact with overflow waters. Improvements to discharge point basket tablet chlorination and monitoring of flow. Capacity of WWTP has been increased as a consequence of refurbishment / expansion, lowering likelihood of overflow events. Predicted Likelihood, D Predicted Consequence, Insignificant, 1


12 Halls Creek water reuse detailed risk assessment

12.1 Overview

Site specific information has been used to complete the following risk rating of identified environmental, human health and amenity risks associated with the proposed water reuse scheme for water from the Halls Creek WWTP under the future operational conditions (i.e. post construction). Potential risks have been rated using the Water Corporation Risk Assessment Matrix (S389) and DER (2017) Guidance Statement: Risk Assessments in order to rate and compare the risks as perceived by the Water Corporation and DWER.

The risk assessment, Table 24 is based on the S-P-R linkages identified in the water reuse conceptual model and does not include potential sources of contamination from off-site sources as these sites are not under the direct control of the Water Corporation.



Table 24 Halls Creek water reuse scheme risk assessment



Risk Rating (S389)





Environmental

Groundwater CoPCs (heavy metals, phenols, PFAS, chlorine) remaining within the TWW leaching into local groundwater following application to the oval.

Depth to groundwater (~8 mbgl) [Likely, B]




Reuse scheme RWQMP and RWSA management practices. Restricted provision of TWW to Re-Use Scheme no more than 200kL per day

Medium(5) Medium(5)

Human Health

TWS bores CoPCs (heavy metals, phenols, PFAS, chlorine) remaining within the TWW leaching into local groundwater following application to the oval




Low (5) Medium (5)

Significant distance from proposed discharge point, no significant risk. Residual risk assumes concentrations of CoPCs are not elevated in comparison to background and / or specific consequence criteria [Drinking Water Quality]

Low (1) Low (1)

Town Oval Bore [supplying water to swimming pool facility]

Distance to receptor <100 m [Almost certain, A]



High (13) High (15) Shire will monitor the bore water quality To mitigate the risk alternative source(s) of water for the swimming pool (e.g. TWS) should be considered. Residual risk assessment based on alternative unimpacted source of water.

Low (1) Low (1)


13 Proposed Monitoring Program

13.1 Commissioning Monitoring of Facultative and Maturation Ponds

The following sampling will occur during commissioning of the Facultative and Maturation Ponds

13.2 Commissioning Monitoring of Recycled Water Scheme A validation and verification monitoring program will be implemented during commissioning of the Shire of Halls Creek Recycled Water Scheme. The following sampling will be carried in accordance with the requirements for ‘Low Exposure’ risk level schemes as per the DoH Guidelines for the Non-potable Uses of Recycled Water in Western Australia (2011).

13.3 BGL Construction Quality Assurance Report

At the end of completion of the Halls Creek WWTP Upgrade, a Construction Quality Assurance Report will be provided to DWER “describing the quality assurance processes

Frequency Period Parameter Fortnightly Commissioning Period 4

Weeks pH Total dissolved solids

Suspended Solids

BOD5

BOD5 Filtered

Conductivity

Total Kjeldahl nitrogen (TKN)

Ammonium (as N)

Total nitrogen (TN)

Total phosphorus (TP)

COD

E Coli

Helminths

Frequency Parameter Compliance Value

6 samples during commissioning

E.coli <1000 CFU/100mL BOD <20 mg/L pH 6.5 – 8.5 Residual Chlorine 0.2 – 2.0 mg/L


undertake by a qualified engineer during the lining and construction of treatment and evaporation ponds at Halls Creek WWTP.”.

14 Fee Calculation Total Works Approval Fee was determined to be $20,503.00


15 References

Field Capacity (2017) Proposed Halls Creek Effluent Reuse Scheme Irrigation Management Plan & Preliminary Nutrient Risk Assessment

Department of Environment Regulation (2017), Risk Guidance Statement: Risk Assessments, February 2017

Department of Environment Regulation (2017), Risk Guidance Statement: Risk Assessments, February 2017

Department of Environment Regulation (2016), Guidance Statement: Environmental Siting, November 2016

Department of Water (2018) Water Quality Protection Note, Irrigation with nutrient - rich wastewater. July 2008

Swan River Trust (2014) Western Australian environment guidelines for the establishment and maintenance of turf grass areas

Department of Health (2011) Guidelines for the No –potable Uses of Recycled Water in Western Australia

Davidson. W.A (1992 Halls Creek Town Water Supply Groundwater Drilling Investigation 1992, Geological Survey of Western Australian Hydrogeology Report 1992/47

Laws, A. T (1986) Halls Creek Town Water Supply Proposed Frilling Programme, Geological Survey of Western Australia Hydrogeology Report 2734

Department of Environment and Conservation (2012) Western Australian guidelines for bio solids management


Appendix A Environment Policy

Double Click Image to Open


Appendix B: Certificate of Title




Appendix C. additional reports, supporting information etc

Attachment 2a : Prescribed Premise Boundary

Double Click image to Open


Attachment 2b: Halls Creek WWTP Process Control Diagram Conceptual Model

Double Click image to Open


Attachment 2c: Prescribed Premise Layout and Infrastructure Map


Attachment 2d: Halls Creek Re-Use Scheme Location Map


Figure 4: Water Source Protection Area


Figure 5: Halls Creek Wastewater Treatment plant Schedule of Works (Construction, Refurbishment and Operation).

Year

Mon

th

1 2 3 1 2 3 A B C DPS

RPS

Chlo

rine

Mod

ule

SHC

Oval

W

orks

Pipe

line

January - O O - O O - - - - -

February - O O - O O - - - - -March - O O - O O - - - - -April C O O C O O C - - - - C

May C O O C O O C - - - - CJune C O O C O O C - - - - CJuly O R R O R R C - - - - -

August O R R O R R C - - - - -September O R R O R R C - - - - -October O O O O O O - - - - - - Evaporation basin A complete but offline.

November O O O O O O - - - - - -December O O O O O O - - - - - -

January O O O O O O - - - - - -February O O O O O O - - - - - -March O O O O O O - - - - - -April O O O O O O O R R C C C - -

May O O O O O O O R R C C C - -June O O O O O O O R R C C C - -July O O O O O O O R R C C C - -August O O O O O O O R R C C C - -September O O O O O O O O O O - - - - DPS commissioned transferring water from Maturation Pond 3 to Evaporation Basin A.

October O O O O O O O O O O - - C -November O O O O O O O O O O - - C -December O O O O O O O O O O O O O O Treatment plant, connecting pipeline to oval constructed. Site fully commissioned and operational.

Maturation PondsFacultative Ponds

OO

O

OOO

Comment

O

O

Wet season (no construction)

O

O

Refurbishment of existing Facultative and Maturation Ponds. Recently constructed Fac/Mat ponds online, maintain capacity of WWTP.

TTWMEvaporation Basins

Construction of new Facultative and Maturation Ponds, and Evaporation Basin. Existing Fac., Mat and Evap remain online and maintain existing capacity. Pipeline connecting WWTP with Shire Oval completed, but offline until treatment plant works completed.

OO

2019

Wet season (no construction)

Temporary pumping from Maturation Pond 3 to Evaporation Pond A. Evaporation Pond A maintains capacity of WWTP whilst original evaporation pond is refurbished and split into two basins (B and C). Will require generator and associated fuel source (appropriately bunded).2020

OOO


Figure 2: Halls Creek WWTP Geology


Figure 6: Halls Creek Wastewater Treatment plant Construction Phase Model


Figure 7: Halls Creek Wastewater Treatment plant Post Construction Phase Model

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Figure 3a: Halls Creek Town Water Supply Bores and WWTP Groundwater Bores


Figure 8: Halls Creek WWTP and Re-Use Project Flora Communities


Figure 3: Halls Creek WWTP Specified Ecosystems Search


Documents

C-S02355 Halls Creek Wastewater Treatment Plant and