Leslie Vale Quarry Traffic Impact Assessment Pty Ltd Leslie Vale Quarry... · Leslie Road connects between Summerleas Road to the east and Huon Road to the west, running parallel

HBMI

Leslie Vale Quarry Traffic Impact Assessment

May 2012

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Contents

1. Introduction 4

1.1 Background 4

1.2 Traffic Impact Assessment (TIA) 4

1.3 Project Scope 5

1.4 Subject Site 5

1.5 Information and Data Sources 7

1.6 Planning Scheme 7

2. Existing Conditions 8

2.1 Transport Network 8

2.2 Road Safety Performance 11

2.3 Existing Quarry Operations 12

2.4 Future Quarry Activity 14

3. Proposed Development 15

3.1 Development Proposal 15

3.2 Traffic Generation 15

4. Traffic Impacts 16

4.1 Surrounding Road Network Impacts 16

4.2 Pavement Impacts 16

4.3 Sight Distance Assessment 18

4.4 Access Impacts 19

4.5 Road Safety Impacts 24

5. Recommendations 25

5.1 Intelligent Transport Systems – Dynamic Signage 25

5.2 Leslie Road/ Jamiesons Road Priority 25

5.3 Pavement Repair 26

6. Conclusions 27

Figure Index Figure 1 Subject Site (Source: LIST Database, DPIPWE) 6

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Figure 2 Access Configuration 6 Figure 3 Huon Highway (east) 9 Figure 4 Huon Highway (west) 9 Figure 5 Leslie Road south 10 Figure 6 Private access road 11 Figure 7 Yearly Tonnage Data 13 Figure 8 Leslie Vale Quarry delivery times 13 Figure 9 Pavement damage 18 Figure 10 Priority Definition 26

Table Index Table 1 Existing yearly quarry output 12 Table 2 2011 Turning Movements 20 Table 3 Base 2021 Turning Movements 20 Table 4 Proposed 2021 Turning Movements 21 Table 5 SIDRA Results – Base Traffic Volumes 22 Table 6 SIDRA Results – Proposed Traffic Volumes 23

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Leslie Vale Quarry – Traffic Impact Assessment

1. Introduction

1.1 Background Midson Traffic were engaged by HBMI to prepare a Traffic Impact Assessment (TIA) for a proposed change of operations at the Leslie Vale Quarry on Huon Highway, Leslie Vale.

1.2 Traffic Impact Assessment (TIA)

A traffic impact assessment (TIA) is a process of compiling and analysing information on the impacts that a specific development proposal is likely to have on the operation of roads and transport networks. A TIA should not only include general impacts relating to traffic management, but should also consider specific impacts on all road users, including on-road public transport, pedestrians, cyclists and heavy vehicles.

This TIA has been prepared in accordance with the Department of Infrastructure, Energy and Resources (DIER) publication, A Framework for Undertaking Traffic Impact Assessments, 2007. This TIA has also been prepared with reference to the Austroads publication, Guide to Traffic Management, Part 12: Traffic Impacts of Developments, 2009.

DIER recognises that most land use developments generate traffic, and generally attract more private transport movements rather than trips utilising public transport. DIER seeks to move towards a more sustainable transport system through improved transport considerations at a development level. It is, therefore, necessary to address the impact of motor vehicles and road traffic effects on the environment.

The effects of development proposals should be responsibly assessed, giving consideration to expected future traffic movements. DIER relies on the preparation of a TIA in order to adequately assess traffic impacts on the surrounding transport network for each development.

A TIA is not a promotional exercise undertaken on behalf of a developer; a TIA must provide an impartial and objective description of the impacts and traffic effects of a proposed development. A full and detailed assessment of how vehicle and person movements to and from a development site might affect existing road and pedestrian networks is required. An objective consideration of the traffic impact of a proposal is vital to enable planning decisions to be based upon the principles of sustainable development.

The Environment Protection Authority requires a TIA that specifically contains the following information:

Intended vehicle type, future tonnages and traffic volumes, proposed times of transport;

Data describing current levels of traffic use for comparison purposes;

Existing pavement, turning paths of the vehicles intending to use the junctions and available sight distances;

Details of any junction deficiencies along with the scope of any junction upgrading that may be required;

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Any new road accesses or proposed changes of the current layout of the existing junction of the Huon Highway/ Leslie Road; and

Potential for adverse effects of traffic, including noise, dust, vibration, safety, congestion and effects on road pavements, bridges and culverts should be assessed.

1.3 Project Scope

Preparation of a TIA examining the traffic impacts associated with the proposed development in accordance with DIER and Council requirements as follows:

Review of the existing road environment in the vicinity of the site and the traffic conditions on the road network;

Provision of information on the proposed development with regards to traffic movements and activity;

Consultation with DIER and Council;

Identification of the traffic generation potential of the proposal with respect to the surrounding road network in terms of road network capacity; and

Traffic implications of the proposal with respect to the external road network in terms of traffic efficiency and road safety.

1.4 Subject Site

The subject site is the Leslie Vale Quarry and is located south of the Huon Highway in Leslie Vale. Access to the site is via a private road connecting to Leslie Road, which intersects the Huon Highway at a ‘give-way’ controlled intersection.

The subject site and access configuration are shown in Figure 1 and Figure 2 respectively.

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Figure 1 Subject Site (Source: LIST Database, DPIPWE)

Figure 2 Access Configuration

Subject Site

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1.5 Information and Data Sources

The following organisations were contacted during the preparation of this report:

Department of Infrastructure, Energy and Resources (DIER) – Crash and traffic data;

Kingborough Council – Planning Scheme and traffic network information;

Integrated Land Management & Planning – General project information; and

HBMI – General project information and truck movement information.

1.6 Planning Scheme

The Kingborough Planning Scheme 2000 outlines the traffic, access and parking requirements for developments in the Kingborough municipality and is referred to as the Planning Scheme throughout this report.

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2. Existing Conditions

2.1 Transport Network For the purpose of this assessment, the transport network consists of the following roads:

Huon Highway,

Leslie Road, and

The private access road to the quarry.

Each of these is examined in detail in the following sections.

2.1.1 Huon Highway

Huon Highway is classified as a ‘Category 2 – Regional Freight Route’ under the DIER publication, Tasmanian State Road Hierarchy, 2007. The function of Category 2 roads is as follows:

Regional Freight Roads link major production catchments to the Trunk Roads – for example, the Circular Head, Dorset, Huon Valley and Derwent Valley areas. They carry a large number of both heavy freight and passenger vehicles. Together with Regional Access Roads, they provide safe and efficient access to Tasmania’s Regions.

Regional Freight Roads facilitate:

heavy inter-regional and sub-regional freight movement;

passenger vehicle movement;

commercial interaction; and

tourist movement.

They are also the Tasmanian Government’s preferred heavy freight vehicle routes where alternative routes exist.

Huon Highway is a two-lane, two-way road for the majority of its length and connects between Southern Outlet, Kingston, and Kingfish Beach Road, Southport. Huon Highway provides access to Huonville, the Huon Valley and the southern regions of Tasmania.

The Huon Highway has overtaking lanes in both directions to the east of the subject site. On the western side of Leslie Road, the west-bound overtaking lane ends approximately 400 metres downstream from the intersection. It has a pavement width of approximately 15 metres, increasing to approximately 21 metres to allow for two channelised right-turn lanes at the Leslie Road intersection.

Huon Highway carries approximately 7,850 vehicles per day1 near the subject site with 6.8% heavy vehicles. The eastbound peak traffic volume is approximately 708 vehicles per hour (between 7.00 am

1 DIER traffic data, 2009, recorded 280m east of Sandfly Road (approximately 4.2km west of subject site)

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and 8.00 am) and the westbound peak traffic volume is approximately 666 vehicles per hour (between 5.00 pm and 6.00 pm). The Huon Highway experiences a seasonal variation in the order of 7.7%.

A speed limit of 100-km/h applies to Huon Highway near the Leslie Road intersection. Huon Highway looking east and west of the Leslie Road intersection is shown in Figure 3 and Figure 4 respectively.

Figure 3 Huon Highway (east)

Figure 4 Huon Highway (west)

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2.1.2 Leslie Road

Leslie Road is classified as a ‘Category 6 – Other Road’ under the Planning Scheme. Category 6 roads are often of a rural standard or are local streets with low traffic volumes and provide access to properties.

Leslie Road connects between Summerleas Road to the east and Huon Road to the west, running parallel to the Huon Highway and providing access to a number of residential properties. It crosses the Huon Highway twice, once passing underneath the highway and once at-grade with a give-way intersection directly near the subject site. The intersection has dedicated right turn lanes on the Highway to each leg of Leslie Road. The width of Leslie Road at the intersection of the Highway on the Quarry approach is approximately 36 metres. This provides sufficient width for the manoeuvring of heavy vehicles associated with the quarry’s operations.

Near the subject site, Leslie Road is a sealed, two-lane, two-way road with a pavement width of approximately 7 metres. Between Summerleas Road and Huon Highway on the southern side, Leslie Road is unsealed for a large part of its length.

South of the Huon Highway, Leslie Road carries a very low traffic volume. The majority of traffic on this road is accessing the quarry.

Leslie Road looking towards the Huon Highway intersection from the south is shown in Figure 5.

Figure 5 Leslie Road south

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2.1.3 Private Access Road

A private access road (Jamiesons Road) connects between the Leslie Vale Quarry and Leslie Road. The road has an average pavement width of approximately 10 metres and services the heavy vehicle traffic coming from the quarry.

The private access road from its intersection with Leslie Road is shown in Figure 6.

Figure 6 Private access road

2.2 Road Safety Performance

Crash data can provide valuable information on the road safety performance of a road network. This information can be utilised as a tool to assist in identification of possible road safety deficiencies associated with a network.

Crash data was obtained from DIER for the most recent 10 year time period (1 January 2001 to 26 July 2011) for Huon Highway and Leslie Road, Leslie Vale.

The crash data is summarised as follows:

A total of 31 crashes occurred during this ten year period. Of these, 5 involved minor injury, 2 required the application of first aid at the scene, 3 involved serious injury, 1 resulted in fatal injury and the remaining 20 were property damage only.

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The majority of crashes, 22, occurred mid-block on Huon Highway. There were 3 crashes on the intersection of Leslie Road and Huon Highway and the remaining 6 crashes occurred along Leslie Road north of Huon Highway (not the leg that accesses the Quarry site).

The most common crash type was loss of control type crashes, involving a vehicle leaving the carriageway on a curve or a straight, with 14 occurrences. There were also 6 rear end collisions, 4 side swipes, 3 miscellaneous crashes, 2 crashes involving a vehicle striking an animal, an adjacent approach crash and a single head on collision.

The fatal crash occurred in 2006 and was a head on collision mid-block on Huon Highway approximately 400 metres west of the Leslie Road intersection.

The crash history does not suggest that there are any specific, existing road safety deficiencies on Huon Highway or Leslie Road in the vicinity of the subject site. The mid-block crashes are consistent with a rural highway with a 100-km/h speed limit. There are two important considerations with respect to the proposed development:

1. None of the crashes reported involved heavy vehicles.

2. A relatively small number of crashes were reported at the intersection of Huon Highway and Leslie Road (3 total in 10 years).

2.3 Existing Quarry Operations

Recently, the Leslie Vale Quarry has experienced a significant boost in output such that it is currently operating outside its existing permit (750,000 tonnes per annum.) producing approximately 945,000 tonnes in the 2010/ 2011 financial year. The relatively large increase in output in the 2010/11 financial year was associated with the construction of large infrastructure projects, including the Brighton and Kingston Bypasses, which are now completed or nearing completion.

A summary of the yearly quarry output is displayed in Table 1 and Figure 7 along with the number of individual deliveries generated. Note that, on average, approximately 10% of transactions are split loads, where there is a single truck and trailer combination with different products in each. This results in the number of total deliveries being less than the number of total transactions.

Table 1 Existing yearly quarry output

Year No. Transactions Total Output Number of Deliveries

2006/07 34,805 651,665 T 31,325

2007/08 37,265 729,424 T 33,539

2008/09 32,802 621,311 T 29,522

2009/10 40,874 770,817 T 36,787

2010/11 46,801 944,692 T 42,121

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Figure 7 Yearly Tonnage Data

During the 2010/2011 financial year the quarry generated an average of approximately 150 heavy vehicle trips per day with peak activity mid-week with closer to 170 heavy vehicle trips per day. These trips occur between the hours of 6:00 am and 3:30 pm. The delivery times as recorded over four days in April 2011 are shown in Figure 8.

Figure 8 Leslie Vale Quarry delivery times

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2.4 Future Quarry Activity

As discussed in Section 2.3, the recent increase in quarry activity has been associated with the construction of large infrastructure projects such as the Brighton Bypass, where high quality blue stone aggregate was required in high quantities. The output from the quarry has been demand driven by these infrastructure projects. These projects are now coming to a close, and the output from the quarry will decrease as a result.

The Brighton Bypass projects (northern and southern sections) were the largest transport infrastructure projects ever undertaken in Tasmania. It is unlikely that projects in the foreseeable future will result in such large demands for quality blue stone products of the magnitude experienced by the combination of these projects (including the Kingston Bypass).

Furthermore, expansion of the Dysart Quarry is also proposed by HBMI, which is intended to provide high quality blue stone aggregate and other products to the local area, will also reduce the demand for products from the Leslie Vale Quarry.

The future demands for the Leslie Vale Quarry are forecast to reduce from current levels in immediate term.

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3. Proposed Development

3.1 Development Proposal It is proposed to increase the level of production of the Leslie Vale Quarry from its current permitted output of 750,000 tonnes per year to 1,000,000 tonnes per year in line with the current operating conditions.

3.2 Traffic Generation

Traffic generation rates are based on the existing operation of the quarry as summarised in Section 2.3 of this report. Based on the 2006/ 07 to 2010/ 11 data, the site generates an average of 46.7 trips per 1,000 tonnes resulting in an average load of 21.4 tonnes per delivery.

A production level of 1,000,000 tonnes per year is therefore expected to generate a total of 46,738 deliveries, increasing the average daily traffic generation of the site to 166 vehicles per day and peaking at 189 vehicles per day. This compares with 35,054 deliveries per year, 125 trucks per day average and peak of 142 trucks per day for the approved 750,000 tonnes per year.

Assuming an hourly traffic distribution as shown in Figure 8 above, the proposed development is expected to generate an additional 41 heavy vehicle trips per hour during peak times compared to approved operating conditions (and an additional 47 trucks per day during peak times). This increase only applies when the quarry is operating at the proposed maximum level of 1,000,000 tonnes per annum. As noted in Section 2.4 of this report, the likely production will reduce from current levels as a result of the completion of large transport infrastructure projects.

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4. Traffic Impacts

4.1 Surrounding Road Network Impacts The proposed development, if operating at full capacity, will generate an additional 47 heavy vehicles per hour onto the Huon Highway during the morning peak period (8:00am – 9:00am). The existing traffic volumes on Huon Highway have been factored up by a growth rate of 2.3% (historic growth rate between 1989 and 2008) and by the seasonal variation of 7.7% to obtain base 2021 peak traffic volumes:

2021 Eastbound traffic (8:00am – 9:00am) 842 vehicles per hour

2021 Westbound traffic (8:00am – 9:00am) 277 vehicles per hour

Therefore, given that the general capacity of a two-lane, two-way road is approximately 1,000 vehicles per hour in each direction, there is sufficient spare capacity in Huon Highway to cater for the very minor increase of 47 vehicles per hour due to the proposed development when the quarry is operating at the proposed maximum level.

As noted in Section 2.4 of this report, the likely production will reduce from current levels as a result of the completion of large transport infrastructure projects. This reduction will reduce the transport impacts associated with the quarry activity, particularly at the junction of Huon Highway and Leslie Vale Road.

The capacity of the Huon Highway/ Leslie Road intersection, including appropriate treatment measures, is discussed in Section 4.4 of this report.

4.2 Pavement Impacts The proposed increase in quarry production will generate a significant amount of truck activity on the Private Access Road, Huon Highway and a short section of Leslie Vale Road in between when the quarry is operating at this capacity. Generally, the effect of light vehicles on road pavement is negligible and pavement fatigue results from heavy vehicle traffic.

The general method for determining the impact of heavy vehicles on road pavements is by using the Equivalent Standard Axle (ESA) to standardise truck loads. The majority of traffic generated by the quarry is Austroads Class 4, Three Axle Truck, with or without attached trailer.

According to the Austroads Vehicle Classification System (2004), Class 4 vehicles have 3 axles in 2 axle groups, resulting in the following axle configurations:

Class 4 vehicle

1x SADT 0.6 ESA 1x TADT 1.0 ESA

Class 4 vehicle with trailer

1x SADT 0.6 ESA

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2x TADT 2.0 ESA

Assuming that approximately one quarter of the trucks have trailers attached, the additional average pavement load due to the proposed increase in operations is 1.85 ESA per vehicle resulting in a total of 8,541 ESA per year.

The Huon Highway is classified as a ‘Category 2 – Regional Freight Route’ and is part of the State preferred heavy vehicle route. The pavement effects of the minor increase in heavy vehicle traffic (in the order of 8,541 ESA per year) will be negligible as the road has been constructed to a high standard to cater for heavy freight volumes (note that it currently carries in the order of 280,000 ESA per year).

The private road that provides access to the quarry is in generally good condition with the current heavy vehicle volumes using it. The increase of 8,541 ESA per year is not expected to cause a large amount of deterioration on the pavement in the short to medium term.

No information was available regarding the construction date or maintenance regime for the Council owned Leslie Road between Huon Highway and the private access road, however, there is a significant amount of pavement damage near the intersection with Huon Highway (Figure 9) and the pavement is appears to be nearing the end of its useful life.

As noted in Section 2.4 of this report, the likely production will reduce from current levels as a result of the completion of large transport infrastructure projects. This reduction will reduce the traffic generation from current levels to volumes experienced 2 to 3 years prior, therefore the cumulative impacts associated with the quarry’s operation over time may not be as significant if production does not line up with capacity.

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Figure 9 Pavement damage

4.3 Sight Distance Assessment

The Austroads publication, Guide to Road Design, Part 4A: ‘Unsignalised and Signalised Intersections’, 2009 (Austroads Guide) defines Safe Intersection Sight Distance as follows:

SISD is the minimum distance which should be provided on the major road at any intersection.

SISD:

provides sufficient distance for a driver of a vehicle on the major road to observe a vehicle on a minor road approach moving into a collision situation (e.g. in the worst case, stalling across the traffic lanes) and to decelerate to a stop before reaching the collision point

is viewed between two points to provide inter-visibility between drivers and vehicles on the major road and minor road approaches. It is measured from a driver eye height of 1.1 m above the road to points 1.25 m above the road which represents drivers seeing the upper part of cars.

assumes that the driver on the minor road is situated at a distance of 5.0 m (minimum of 3.0 m) from the lip of the channel or edge line projection of the major road. SISD allows for a 3 s observation time for a driver on the priority legs of the intersection to detect the problem ahead (e.g. car from minor road stalling in through lane) plus the SSD

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provides sufficient distance for a vehicle to cross the non-terminating movement on two-lane two-way roads, or undertake two-stage crossings of dual carriageways, including those with design speeds of 80 km/h or more

should also be provided for drivers of vehicles stored in the centre of the road when undertaking a crossing or right-turning movement

enables approaching drivers to see an articulated vehicle, which has properly commenced a manoeuvre from a leg without priority, but its length creates an obstruction

is measured along the carriageway from the approaching vehicle to the conflict point, the line of sight having to be clear to a point 5.0 m (3.0 m minimum) back from the holding line or stop line on the side road.

The Planning Scheme requires that a desirable ESD of 500 metres or a minimum SISD of 250 metres be provided for a 100-km/h prevailing vehicle speed in a rural environment (2.0 second reaction time). The available sight distance at the Leslie Road/ Huon Highway intersection is approximately 300 metres on the eastern approach and 400 metres on the western approach. Therefore, the available sight distance exceeds the Planning Scheme SISD requirements for the prevailing vehicle speeds.

4.4 Access Impacts The intersection of Huon Highway and Leslie Road is currently a give-way controlled intersection with the Huon Highway forming the major road in an east-west direction and Leslie Road forming the minor road. The intersection leg affected most by the proposed development is the southern Leslie Road approach providing access to the Leslie Vale Quarry.

The existing intersection contains two auxiliary right-turn lanes into Leslie Road north and Leslie Road south and the Huon Highway has two lanes in each direction surrounding the intersection with the exception of eastbound traffic to the west of the intersection which has only one lane.

At present, due to the high number of heavy vehicle turning movements, the intersection is performing close to capacity regarding movements out of Leslie Road south during the morning peak period. There are two broad options for improvement: at-grade treatment or grade separation.

The Austroads Guide states the following with regard to the grade separation of traffic movements:

Generally at-grade intersections can be designed to provide adequate capacity and safety. However, situations do arise where a particular traffic movement results in serious congestion or a road safety problem that cannot be resolved through traffic management or at-grade treatment. In such cases the road authority may choose to grade separate one or more movements. These treatments can involve various layouts to suit local situations and traffic movements and typically have the normal features of an at-grade design (e.g. auxiliary lanes). To improve safety they may result in the major road intersections comprising only left turns and auxiliary lanes.

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In order for grade separation to be necessary, it must be demonstrated that no at-grade treatment can resolve serious congestion or road safety issues with the intersection.

4.4.1 Turning Movement Counts

A turning movement survey of the Huon Highway/ Leslie Road intersection was undertaken on 17th August, 2011, during morning peak hour (between 8:00 am and 9:00 am). The results of the survey are displayed in Table 2 below.

Table 2 2011 Turning Movements

Time Huon Hwy (E) Leslie Rd (S) Huon Hwy (W) Leslie Rd (N)

L T R L T R L T R L T R

8:00 – 8:15 4 58 4 3 0 5 4 176 2 36 1 3

8:15 – 8:30 2 51 3 2 1 3 3 161 2 30 1 3

8:30 – 8:45 5 40 5 4 0 5 1 154 1 31 0 4

8:45 – 9:00 4 38 4 1 0 3 0 134 2 14 0 1

Average (vph) 15 187 16 10 1 16 8 625 7 111 2 11

Trucks (%) 67% 7% 0% 90% 0% 50% 13% 1% 71% 3% 0% 0%

Assuming a constant growth rate of 2.3%, equal that that recorded to the west of the Kingston Interchange between 1989 and 2008, the expected base turning movements in 2021 are as summarised in Table 3.

Table 3 Base 2021 Turning Movements



Average (vph) 15 235 20 10 1 16 10 785 7 139 3 14

Trucks (%) 67% 7% 0% 90% 0% 50% 13% 1% 71% 3% 0% 0%

Adding the traffic generation of the proposed development during morning peak period, the proposed 2021 turning movements are as listed in Table 4.

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Table 4 Proposed 2021 Turning Movements



Average (vph) 17 235 20 11 1 18 10 785 8 139 3 14

Trucks (%) 71% 7% 0% 91% 0% 56% 13% 1% 75% 3% 0% 0%

4.4.2 SIDRA Analysis

Intersection Analysis software, SIDRA Intersection 5.1 (Akcelik and Associates), was used to determine the likely performance impacts that the proposed development is likely to have on the Huon Highway/ Leslie Road intersection.

SIDRA utilises complex analytical traffic models coupled with iterative approximation technique to provide estimates of capacity and performance of intersections. SIDRA is endorsed as a modelling tool by Austroads.

One of the key SIDRA outputs is an indication of level of service (LOS) at intersections. The LOS concept describes the quality of traffic service in terms of 6 levels, with level of service A (LOS A) representing the best operating condition (i.e. at or close to free flow) and level of service F (LOS F) representing the worst (i.e. forced flow).

The SIDRA modelling incorporated the high proportion of heavy vehicles on the Quarry approach to the intersection, and the increased gap acceptance required by this class of vehicle on this approach.

The results of the SIDRA analysis for base traffic volumes, in 2011 and 2021, are summarised in Table 5.

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Table 5 SIDRA Results – Base Traffic Volumes

Movement Level of Service Average Delay (s) 95% Queue Length (m)

2011 2021 2011 2021 2011 2021

Leslie Road (S) L LOS F LOS F 60.3 165.0 11.5 25.1

T LOS F LOS F 55.4 160.0 11.5 25.1

R LOS F LOS F 58.4 163.1 11.5 25.1

Huon Highway (E) L LOS C LOS C 16.8 16.8 0.0 0.0

T LOS A LOS A 0.0 0.0 0.0 0.0

R LOS C LOS C 15.9 17.9 0.6 0.9

Leslie Road (N) L LOS C LOS C 17.6 24.6 7.5 15.0

T LOS B LOS C 14.8 21.8 7.5 15.0

R LOS C LOS C 17.3 24.3 7.5 15.0

Huon Highway (W) L LOS B LOS B 13.0 13.0 0.0 0.0

T LOS A LOS A 0.0 0.0 0.0 0.0

R LOS C LOS C 19.5 20.2 0.5 0.5

All Vehicles NA NA 4.5 7.3 11.5 25.1

The SIDRA analysis shows that the Leslie Road south leg of the Huon Highway/ Leslie Road intersection is currently operating at capacity and that given the background traffic growth on Huon Highway and in the surrounding area, delays are expected to exceed 160 seconds for vehicles exiting Leslie Road by the year 2021 regardless of the additional traffic generated by the proposed development.

The ten forecast traffic volumes with the traffic generation of the proposed development added were also analysed for the intersection. Table 6 summarises the results for the existing intersection configuration.

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Table 6 SIDRA Results – Proposed Traffic Volumes

Movement Level of Service Average Delay (s) 95% Queue Length (m)

Base Prop. Base Prop. Base Prop.

Leslie Road (S) L LOS F LOS F 165.0 270.1 25.1 42.2

T LOS F LOS F 160.0 265.1 25.1 42.2

R LOS F LOS F 163.1 268.5 25.1 42.2

Huon Highway (E) L LOS C LOS C 16.8 17.0 0.0 0.0

T LOS A LOS A 0.0 0.0 0.0 0.0

R LOS C LOS C 17.9 17.9 0.9 0.9

Leslie Road (N) L LOS C LOS C 24.6 24.6 15.0 15.1

T LOS C LOS C 21.8 21.8 15.0 15.1

R LOS C LOS C 24.3 24.4 15.0 15.1

Huon Highway (W) L LOS B LOS B 13.0 13.0 0.0 0.0

T LOS A LOS A 0.0 0.0 0.0 0.0

R LOS C LOS C 20.2 20.6 0.5 0.6

All Vehicles NA NA 7.3 10.2 25.1 42.2

In its current configuration, the Huon Highway/ Leslie Road intersection will be unable to cater for the increased traffic loads when the quarry is operating at the proposed limit of 1,000,000 tonnes per annum due to the proposed development with delays approaching 5 minutes during morning peak hour. This only occurs for one hour on week days during the morning peak period – outside this period, the intersection operates at a much higher level of service.

It should be noted however, the only intersection leg experiencing high delays following the expansion of the Leslie Vale Quarry is the Leslie Road south approach, which is predominantly used by the quarry. The SIDRA outputs are a reflection of the larger gap acceptance requirements for trucks. The associated delays only apply to the vehicles on the quarry approach to the intersection due to the high proportion of heavy vehicles using this approach.

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4.4.3 Road Safety Performance

There is a large amount of heavy vehicle activity at the Huon Highway/ Leslie Road intersection, particularly concerned with turning movements into and out of the Leslie Road south leg. The presence of heavy vehicles accessing a high speed road such as the Huon Highway creates an inherent road safety concern.

The road safety issues associated with this intersection are considered to be relatively minor, however, for the following reasons:

While entering sight distance is not provided, the sight distance at the intersection exceeds the minimum Safe Intersection Sight Distance requirements in both directions; and

The crash history at the intersection does not suggest that there are any existing specific road safety deficiencies with only 3 incidents in the most recent 10 year time period. This is important as the proposed development is an extension of activity that is already dominant at this intersection, and has been for some time. The proposed development is a formalisation of the existing operations at the site.

Safety at the intersection can be improved with at-grade treatments such as the provision of an auxiliary left turn lane into Leslie Road south. Grade separation of this intersection is not warranted on road safety or capacity grounds in accordance with Austroads recommendations.

4.5 Road Safety Impacts

No significant detrimental road safety impacts are foreseen for the proposed development based on the following:

There is sufficient capacity in the Huon Highway to safely absorb the minor increase in heavy vehicle traffic in the surrounding road network on all approaches except for the Quarry approach, which can be controlled through careful operational management.

There is ample sight distance available at the Huon Highway/ Leslie Road intersection for the prevailing vehicle speeds in accordance with the Planning Scheme requirements.

There is no crash history to suggest that there are any existing road safety deficiencies in the vicinity of the subject site.

The proposed development is not a new development but an expansion of existing activity and as such, heavy vehicle movements into and out of the site will not be seen as an unusual event by other motorists.

As noted in Section 2.4 of this report, the likely production will reduce from current levels as a result of the completion of large transport infrastructure projects. This reduction will reduce the traffic generation from current levels to volumes experienced 2 to 3 years prior.

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5. Recommendations

In light of the above findings, a number of traffic management changes are recommended. These are outlined in the following sections.

5.1 Intelligent Transport Systems – Dynamic Signage

Through discussions with DIER, it is recommended that dynamic signage be investigated for the northern approach to the intersection. There are a number of options that may be considered to assist the sight distance issue for this approach. These are as follows:

5.1.1 Time Activated Truck Warning Signage

Dynamic signage can be installed that is activated automatically based on time of day. For the quarry operations, it may be activated between the hours of 6:00am and 3:00pm as this period captures the majority of truck movements to and from the site.

The main issues associated with this proposal is that trucks operate outside these hours, so there is a risk that motorists may be caught ‘unaware’ of a slow moving truck entering the intersection. The relatively lengthy time that the signs are operational may also cause complacency for motorists that drive along Huon Highway regularly.

5.1.2 Vehicle Activated Truck Warning Signage

Dynamic signage can be installed that is activated by the presence of a vehicle propped on Leslie Road at the Huon Highway junction. The presence of the vehicle can trigger an appropriate warning sign (such as “Caution Trucks Entering XXm”).

The advantages of this method is that it provides more relevant information for an approaching motorist. The disadvantage is that it the message may not be displayed to motorists that have already passed the sign when the vehicle is propped on the Leslie Vale Road approach.

Care would be required to ensure that the detectors pick up the right size vehicles (ie. If the message warns of trucks, but a car activates the sign, etc).

5.2 Leslie Road/ Jamiesons Road Priority

The intersection of Leslie Vale Road and the Quarry is poorly defined. Line marking and give way signage should be installed to assign priority to Jamiesons Road as this is the higher trafficked road and already appears to be the priority for motorists. This is shown conceptually in Figure 10.

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Figure 10 Priority Definition

5.3 Pavement Repair

It is recommended that action be taken to repair the pavement in Leslie Road at the intersection of Leslie Road and Huon Highway to cater for the heavy vehicle traffic using the Leslie Road/ Huon Highway intersection (refer to Figure 9).

27


6. Conclusions

This traffic impact assessment (TIA) investigated the road and traffic impacts of the proposed expansion of operations at the Leslie Vale Quarry, Leslie Vale. Access to the site is via an access road connecting to Leslie Road, which adjoins the Huon Highway at a give-way intersection.

This TIA has been conducted following a review of available traffic data and information, Austroads Guidelines, Australian Standards, Planning Scheme and other supplementary traffic data and information.

The key findings of the report are as follows:

The proposed development is for an increase of output from the quarry to 1 million tonnes per annum. The output from the quarry in 2010/11 approached this level, at 944,000 tonnes. The relatively large increase in output during that year was predominantly a result of the construction of a number of unprecedented large infrastructure projects (namely the Kingston and Brighton Bypasses). The completion of these projects, in conjunction with the proposed expansion of the Dysart Quarry, will result in a decrease in production at the Leslie Vale Quarry over the next few years. This will result in reduced traffic impacts compared to current operations.

The traffic generated by the proposed development, when operating at the proposed maximum output, will be in the order of 47 heavy vehicles during morning peak hour, will not have any significant adverse impacts on the surrounding road network in terms of traffic efficiency or road safety.

Adequate sight distance is provided at the site access in accordance with the Planning Scheme requirements for the prevailing vehicle speeds.

The existing pavement at the Leslie Road/ Huon Highway intersection should be repaired.

Dynamic warning signage should be considered for the northern approach to the Leslie Road junction on Huon Highway. Further investigation should be undertaken to determine the most appropriate method of providing the warning, and the content of the message.

Based on the findings of this report, and subject to the recommendations above, the proposed development is supported on traffic grounds.

28


Midson Traffic Pty Ltd ABN: 26 133 583 025

18 Earl Street Sandy Bay TASMANIA 7005 T: (03) 6210 0745 E: [email protected] W: www.midsontraffic.com.au

© Midson Traffic Pty Ltd 2012

This document is and shall remain the property of Midson Traffic Pty Ltd. The document may only be used for the purposes 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.

Document Status

Revision Author Review Date

0 Mark Petrusma Keith Midson 24 August 2011

1 Mark Petrusma Keith Midson 9 December 2011

2 Keith Midson Zara Kacic-Midson 14 May 2012

3 Keith Midson Zara Kacic-Midson 25 May 2012

mailto:[email protected]

http://www.midsontraffic.com.au/

HBMI

Resource Management Plan

June 2006

2

HBMI Resource Management Plan June 2006

Contents 30 Year Pit Plan for Dolerite Quarry 3 Overburden Management Plan 19

M:\8 Divisional Procedures, Handbooks, Manuals & Codes\Procedures and Documentation\Quarry\Resource Management Plan.doc

3


30 Year Pit Plan

for

HBMI

June 2006

Angelo Labriola Technical Services Manager Orica Quarry Services

4


Introduction On the 15th and 16th of May, 2005, Angelo Labriola of Orica Quarry Services conducted a visit to the HBMI Leslie Vale dolerite quarry in Tasmania. The objective of the visit was to assist the quarry in their development plans for future extraction. Critical decisions are required for ramp locations that will impact schedule of rock removal from the quarry as well as the cost of extraction, particularly as influenced by haul distances. This study focuses on two haul options, and the corresponding quantities and haul distances associated with each. Production HBMI’s Leslie Vale quarry currently produces approximately 50,000 – 60,000mt per month. This financial year, production is expected to reach approximately 640,000mt. Future development will see production requirements increase at the quarry, potentially reaching as high as 1Mmt per annum. For the purposes of this report, an average production rate of 750,000mt per annum is assumed. The primary crusher has a nameplate capacity of up to 400mt per hour. It’s current throughput lies in the range of 290 – 330mt/hr (based on a 9 hr shift). Average crusher throughput rates of up to 340mt/hr are expected by HBMI. Current Haul Road Route The current haul road route travels along the northern end of the current quarry limit. It then follows the current western limit and down to the south, accessing both the 58mRL current pit floor level and the 74mRL level from the south. This results in a haul route length of approximately 1.3km from the 58mRL level to the primary crusher. A key objective of the quarry pit plan going forward is to minimise haul route length for a development period time window of up to 20 years. Future Haul Route Options The site visit and investigation suggested that two haul roads should be developed for the Leslie Vale quarry. One of these roads, which for the purposes of this report shall be named Haul Road A, traverses along the eastern quarry boundary and then to the south, reaching the current 58mRL pit floor and providing access to future deeper levels as necessary. Haul Road A is further subdivided into two alternative options, which shall be named A1 and A2. Haul Road A1 provides a slightly shorter and steeper

5


access, but minimises the extent to which the current wall on the eastern end needs to be cut to facilitate creating a haul road of minimum 15m road width. Haul Road A2 follows a similar trajectory to the east and south, except that it cuts further into the current eastern wall of the quarry. This route sees the haul road essentially being created where the current Red Rock Road traverses beyond the perimeter of the pit at its east and south-eastern end. The Haul Road A2 alignment allows for an extra approximately 25m of pit wall width to be removed from the current eastern wall. At the time of the site visit, there was not a certain view on the worth of extracting a significant amount of material from the current eastern wall. Historically, this material was deemed to be troublesome to fragment and process, although this may require re-evaluation due to changes in the crushing circuit since then. The second proposed route, Haul Route B, travels along the northern boundary of the quarry. It commences where the current haul road does but then cuts into the pit to meet the 74mRL level. This road ultimately also provides a haul route for the material in the proposed new development zone to the northwest of the current quarry pit boundary. This new pit development area has a surface footprint extension measuring approximately 250m wide by 150m long. The proposed Haul Road routes A1, A2 and B are shown on Figure 1 on the following page.

6


Figure 1: Proposed Haul Route layouts – HBMI Leslie Vale Quarry

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Volumes and Scheduling The following section outlines the calculated volumes of each slice using Orica’s SHOTPlus survey and blasting control software. The required haul road accesses are also outlined. Overburden – SE corner of quarry In order to access material in the upper reaches of the SE corner of the quarry, it is necessary to first remove the overburden layer. There is evidence to suggest that this layer will create difficult blast condition with respect to desired fragmentation, based on the natural joint spacing exhibited in the rock. This is shown in Figure 2. Figure 3 shows the lateral extent of the overburden layer in the south wall of the eastern part of the quarry. Figure 4 shows a plan view of the quarry highlighting the region of overburden that must be initially removed to provide access to the benches below.

Figure 2: Overburden layer, showing open jointing/discontinuities

8


Figure 3: Overburden layer in the southern section of the eastern side of the quarry.

Figure 4: Overburden layer, detailing approximate area and bench

height.

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9


The overall volume contained in the overburden area is: 11,516 sqm x 6 m = 69,096 m3 = 200,380 mt The overburden material is to be accessed using the current haul road to the upper reaches of the eastern and south-eastern end of the quarry. Base of Overburden to 74mRL To strip the remainder of the pit to 74mRL, two haulage ramps are required to provide optimum haulage for this level and for ongoing efficient extraction from the quarry. Haulage Ramp A is required to be established, commencing a 1:10 or 10% grade from a lateral distance approximately 100m from survey station 43. Commencing the 10% grade at this point will see the haulage ramp intersect 74mRL at the bottom SE corner of the quarry pit. This will allow access to a calculated area of 17,934sqm at an average bench height of 16m, beneath the current overburden area in the southeast part of the quarry. Haulage Ramp B can also be commenced at the northern end of the quarry. This ramp commences its 10% grade from the current northern access/haulage road at a point near survey station 42. An approximate length of 150m is required to arrive at 74mRL, which occurs immediately to the south east of where the new development area meets the current pit workings. The sequence of establishing these ramps is critical to maintaining access to the current 58mRL working floor. A plan view of the ramp layout and available volumes to the 74mRL level is shown in Figure 5 on the following page. The ramp layout shown in Figure 5 is the A1 option, and the volumes reflect this option. Corresponding volumes for option A2 are presented later in this report.

10


Figure 5: Haulage ramps and material areas for the base of the overburden to 74mRL.

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Approx Average BH = 6mApprox Average BH = 16m


17,934 Msq13,842 Msq

5,432 Msq

Base of overburden to RL 74

52,308 MsqApprox Average BH = 12m

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11


The following considerations are important for the development and mining of the quarry up to 74mRL:

Ramp A needs to be started ASAP. This is both to allow mining of area A in Figure 5, and also to allow for a drop cut to be created to open up an alternative access to 58mRL. This will then allow shorter haul routes to be optimised.

The current main haul ramp that follows the western perimeter of the current pit boundary currently serves as the only access down to 58mRL. Because of this, the new development area (Area D in Figure 5) cannot be fully developed to 74mRL until an alternative ramp access (Haul Road A) is developed to the south-east to 58mRL.

The construction of Haul Road B to 74mRL has already started with some overburden being removed. Drill and Blast will be required to cut in part of the new access. Some fill material could be sourced from rock available immediately adjacent to where the ramp will descend, to complete Ramp B. This is shown in Figure 6.

Figure 6: Location of Ramp B in the northern end of the quarry, showing

the requirement for cut and fill, as well as a source of fill material.

12


The overall volume contained from the base of the overburden area to 74mRL is: Region A: 17,934 sqm x 16 m = 286,944 m3 = 832,138 mt Region B: 5,432 sqm x 7 m = 38,024 m3 = 110,270 mt Region C: 13,842 sqm x 6 m = 83,052 m3 = 240,851 mt Region D: 52,308 sqm x 12 m = 627,696 m3 = 1,820,318 mt Total: 3,003,577 mt 74mRL to 58mRL Both Haulage Ramps A and B will service extraction from 75mRL to 58mRL. Haulage Ramp A will continue to provide the shortest route for material extracted from the eastern and southern parts of the quarry, while Haulage Ramp B will provide efficient haul routes for material extracted in the new development area. Haulage Ramp A continues its 1:10 or 10% grade for another 160m to reach 58mRL, as detailed in the previous section of this report, it is advantageous to create this ramp cut early to allow an alternative extraction route for material currently being extracted from the 58mRL floor. Haulage Ramp B progresses towards the west, between the current and new pit development areas. To reach 58mRL it is also extended by approximately 160m on a 10% grade. A plan view of the ramp layout and available volumes to the 58mRL level is shown in Figure 7 on the following page.

13


Figure 7: Haulage ramps and material areas for excavation of 74mRL to 58mRL.

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An approximate average bench height of 14m has been determined for 74mRL to 58mRL. The overall volume contained from 74mRL to 58mRL is: 156,997 sqm x 14 m = 2,197,958 m3 = 6,374,078 mt Proposed new bench - 58mRL to 44mRL Both Haulage Ramps A and B extend 160m at a 10% grade to reach the 16m increase in quarry pit depth. Again, Haulage Ramp A will continue to provide the shortest route for material extracted from the eastern and southern parts of the quarry, while Haulage Ramp B will provide efficient haul routes for material extracted in the new development area. There has been no confirmation from HBMI that there are plans to extend the quarry to 44mRL. This is an initial long-term view at best, and should be re-evaluated with time, as other factors could well influence overall cost efficiencies, eg: relocation of the crusher, in-pit crushing, etc. A plan view of the ramp layout and available volumes to the 44mRL level is shown in Figure 8 on the following page.

15


Figure 8: Haulage ramps and material areas for excavation of a possible 58mRL to 44mRL scenario.

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16


An approximate average bench height of 16m has been suggested for a possible 58mRL to 44mRL extension. The overall volume contained from 58mRL to 44mRL is: 213,429 sqm x 16 m = 3,414,864 m3 = 9,903,106 mt A2 Haulage Ramp Option The A2 haulage ramp uses the current Red Rock road alignment and consequently pushes the planned haul road a further 25m to the east on average. This occurs for a length of approximately 145m, adding approximately 3,625 sqm of area to each level. It is understood from Leslie Vale quarry personnel that there are doubts about the suitability of this rock for quarrying operations based on unfavourable experience with it in the past. It may be possible, though, to alter blast design parameters to provide adequate fragmentation in this area, should the specification of the rock itself be desirable to HBMI. The following table summarises the approximate additional tonnages expected from using the A2 route rather than the A1 route for the eastern and southern haul road.

Level Approximate additional tonnes Overburden 5,256 mt Base of overburden to 74mRL 168,200 mt 74mRL to 58mRL 147,175 mt 58mRL to 44mRL – proposed level 168,200 mt Total: 488,831 mt

17


Summary of Approximate Expected Material Quantities The table below summarises the expected material quantities from each level based on the haulage ramp options discussed in this report.

Level Ramp A1 & B Ramp A2 & B

Overburden 200,400 mt 205,600 mt

Base of overburden to 74mRL

3,003,600 mt 3,171,800 mt

74mRL to 58mRL 6,374,100 mt 6,521,300 mt

Subtotal: 9,578,100 mt 9,898,700 mt

Additional Bench/Level

58mRL to 44mRL – proposed level

9,903,100 mt

10,071,300 mt

Total: 19,481,200 mt 19,970,000 mt

Therefore, based on an average production rate of 750,000mt per annum, the access and pit development designs in this report through to the 58mRL level will allow for a quarry plan of approximately 13 years. The addition of another bench to the 44mRL level will double this time span. Haul Ramp Distances The present haul ramp results in a distance of approximately 1.3km from the primary crusher to the bottom of the pit (58mRL). The approximate distances to the various pit levels based on the new ramp designs are:

Sector Ramp A1 Ramp B

Primary to 74mRL 335m 470m



Note that the distances in the table above are to the entry points of each level. To determine the distance to a point of interest, the distance along the bench needs to be determined from the ramp entry points indicated in the plans (Figures 5, 7, 8) in this report.

18


Conclusion HBMI’s Leslie Vale quarry requires rapid consolidation of a plan for future ramps, which in turn need to be commenced in the short term to best meet the quarry’s development needs. A double ramp solution is favoured, with one ramp at the eastern end of the quarry, and another from the northern end, travelling down the current western limit of the pit. This will serve to provide access points to current and future ramps that will minimise haul distances and haul times. This should greatly assist the quarry’s objective of lifting production to 750,000tpa. Without developing a new bench from 58mRL to 44mRL, and based on a 750,000tpa production rate, the suggested ramp plan will yield approximately 9.5 – 10 Mmt, equating to a 13 year plan. Developing another bench from 58mRL to 44mRL could double this. Angelo Labriola Technical Services Manager Orica Quarry Services

19


OVERBURDEN

MANAGEMENT PLAN

HBMI QUARRY

Leslie Vale, Tasmania

Prepared by Michael Hazell in consultation with John Sherburd

July 2006

20


Introduction

Following the development of the Haul Ramp Development Plan written by Angelo Labriola of Orica Quarry Services, Michael Hazell, under the instruction of John Sherburd – HBMI Quarry Manager – has prepared the following plan to manage the overburden management area at HBMI Quarry. The plan was developed July 2006

Location

The overburden dump is located to the south of the main pit entrance at the 58RL Level and faces a large bush hill which also comes under the quarry lease. There are no homes or public roads in sight range within the overburden management area.

Topographical Features

The overburden management area sits above a forested gully comprising of mainly eucalypt trees. The land surface is mildly steep, covered with weathered dolerite and can be considered very stable.

History

The area has been used for the relocation of overburden by HBMI since the early 1990’s. Older area’s of overburden have since been rehabilitated with eucalypts common to the area as per the photo below:

Above: Location of overburden management area

21


Environmental Aspects

The following environmental aspects have been identified with the overburden management area:

Aspect Likelihood Impact Environmental Concern

Noise 1 1 1

Dust 1 1 1

Damage to Aesthetics 2 1 2

Damage to Flora and Fauna 3 1 3

Watercourse Siltation 4 2 8

Land Slip 1 5 5

From the above table, it is deemed that watercourse siltation and potential landslip are the biggest impacts to be managed and thus are given the bulk of consideration in this plan.

OH & S Aspects

The following OH&S aspects have been identified with the overburden management area:

Above: rehabilitated overburden

Above: Aspects and Impacts register. (a score of 25 being the maximum score. The lower the score, the lower the environmental concern)

22


Aspect Likelihood Impact Danger Rating

Rolling or falling off the edge 2 5 10

Traffic or pedestrian collision 1 4 4

From the above table, it is deemed that rolling or falling off of the edge of the land fill area is the biggest danger to be managed and thus is the biggest OH&S issue discussed in this plan.

Volumes

It is expected that there is enough room in the Overburden Management Area to relocate approximately 50,000m3 of clean fill based on a current area of approximately 95m long, 50m wide and 10m high. Provided the land is stable, a further layer could be built in order to relocate more material

Above: OH & S Aspects and Impacts register. (a score of 25 being the maximum score.)

23


Overburden Management Area Design

Minimising watercourse siltation and land slipping is a primary objective with the Overburden Management Area whilst maintaining a safe working site. This shall be achieved by:

1. Minimising water accessing loose and non protected fill 2. controlling water run off away from the outer edge and into nominated

drains by the use of U drains and berms 3. minimising erosion of running water 4. catching any water-borne sediments before it leaves the Overburden

Management Area 5. Compacting loose material (where practical) with heavy machinery 6. Planting trees on the overburden area 7. Conducting regular monitoring of the drains and edges.

Step 1 shall be achieved by ensuring all drains leading up to the Overburden Management Area divert water away from loose and non protected fill. This includes haul road side drains and water run off from the actual quarry pit.

Diagram 1 (above)

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50m

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North

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Step 2 (controlling water run off away from the outer edge and into nominated drains) will be achieved by following the following design of the heap:

Profile (Diagram 2)

Plan (Diagram 3)

Water that falls on the top of the heap will fall towards the haul road and away from the outer edge. It will then be directed into U drains on the side of the heap that lead into a drain running along side of the haul road. U drains will be lined with spalls to reduce water run off speed. Step 3 and 4 (minisising erosion of running water and catching any water-borne sediments) will be achieved by placing spalls at strategic places to slow water flow.

North

South

North South

25


Water drains will be as wide as practically possible. Once water has been directed around the overburden pile it will be diverted back into the natural creek area as quickly and as practically possible to reduce further erosion.

.

Step 5 (compacting material) will be achieved by the use of heavy machinery working on the heap. Drivers will be made aware of the role that their machines play in the compaction process whilst working on the heap but will be advised that they are not to operate heavy machinery so close to an edge as to endanger their lives or plant or machinery. Berms will be built on all finished edges at least 1 meter in height so as to provide clear indication of where an edge is. Only loaders or dozers will be able to push material off the edge where and when required and dump trucks will not be allowed to tip off within 10m from any edge.

Right: Pictures of where the water exits back into the natural bush. Monitoring will ensure that water entering the bush is not heavily contaminated with sediments. Water running off the overburden area will not be allowed to run down this existing bush track creating further erosion.

26


Step 6 (Planting trees on the overburden area) will be done using native plants and bushes that are common to the area and will be done when various stages have been completed and is safe to do so. Step 7 (Conducting regular monitoring of the drains and edges) must be conducted regularly to check for erosion of the heap, sedimentation traps and tension cracks on the heap. These checks would be done on a daily basis when work was being conducted on the Overburden Management Area. If a tension crack was to ever develop it must be reported to the Quarry Manager immediately. Water must not be allowed to enter tension cracks as this would exacerbate the problem and may eventually lead to a land slip As part of the overall environmental management plan for the quarry, Mafeking Creek – the main creek below the Overburden Management Area - will be monitored on a quarterly basis for water quality.

Above: A dump truck tips off on the overburden management area.

27


Sequence of Implementation

Step 1. Complete the bottom layer so that it meets up with the toe of the second layer. This may include the removing of some trees as they will be killed when their lower trunk/rootsystem is covered in fill

Step 2 Using incoming fill, reverse the current angle of the slope of the bottom layer so that water is not able to run off the outside edge. This would also include straightening and tidying up the outside edge (over the length of the site) and building a minimum 1m high berm where required.

Step 3 Ensure all drains, as shown in diagram 1 are in and operating and that water will not flow too fast and not onto the overburden area off the haul road. (The drain running alongside the overburden area should not be too narrow but shall be a wide U drain that can be driven over if necessary.) Step 4 Begin the second layer, working west to east ensuring:

1. Dump trucks aren’t tipping over or close to the edge 2. fill is pushed onto the bottom layer only and not over the side edge into

the bush 3. a berm is constructed on all edges whilst working the layer east. (as per

diagram 2)

Right: Area to be filled

Right: Edge to be straightened and berm installed

28


4. water does not flow off the outside edge but towards the inside edge.(as per diagram 2)

5. U drains are built on the inside wall of the heap (as per diagram 3) and covered with spalls

6. regular monitoring of drains and erosion is done and, 7. regular monitoring for land slip signals are conducted – especially tension

cracks on or near edges. 8. Maintain compaction of the top surface by use of heavy machinery (not to

close to edges)

Step 5 Plant the outer edge with eucalypts and other native trees. This should be done at various stages whilst working on the second layer as it will increase slope stability and decrease any visual impact plus make it possible to go up a third layer if necessary. Step 6 (if or when necessary) Whilst maintaining the above design principals, construct the third layer above the second layer. Caution must be made not to damage rehabilitation works done on the second layer. The third level may not be able to be 10m high (as per the second layer) as it may not be practical or safe to do so and should be decided if or when the time arrives.

Below: an indication of how the third layer could look:

Leslie Vale Quarry

Overburden Stockpile Monitoring Plan

Prepared By: Barry Williams

Date: 22 May 2012

Issue Date Recipient Organisation

Draft 1 12 May 2012 John Sherburd HBMI P/L

Final 22 May 2012

Appendix 12 Overburden Stockpile Monitoring Plan Final

Integrated Land Management and Planning | Introduction 2

TABLE OF CONTENTS 2 Introduction .................................................................................................................................... 3

3 Current Situation ............................................................................................................................. 3

4 Risk assessment .............................................................................................................................. 4

5 Aims................................................................................................................................................. 5

6 Rainfall records ............................................................................................................................... 5

7 Stability monitoring......................................................................................................................... 5

8 Water quality monitoring ............................................................................................................... 6

8.1 New sampling sites ................................................................................................................. 6

8.2 Climatic trigger for sampling ................................................................................................... 7

9 Acceptable limits for TSS ................................................................................................................. 7

10 Reporting..................................................................................................................................... 7

11 Early intervention ........................................................................................................................ 7

12 Appendix ................................................................................................................................... 11

12.1 Risk Assessment Matrix ........................................................................................................ 11

12.2 Risk Level Action table .......................................................................................................... 11

12.3 Hierarchy of controls............................................................................................................. 11

13 References ................................................................................................................................ 12

Tables

Table 1: Environmental Risks .................................................................................................................. 4

Table 2: Occupational risks ..................................................................................................................... 4

Table 3: Historic daily rainfall (94239) .................................................................................................... 7


Integrated Land Management and Planning | Introduction 3

1 INTRODUCTION H.B.M.I. Pty Ltd operates a quarry at Leslie Vale south of Kingston. The operation encompasses three

extractive pits, two smaller operations targeting red gravel and limestone and one large pit

extracting fresh dolerite. The fresh dolerite is covered by a layer of weathered dolerite of varying

thickness. The overburden is mixed with heavy clay seams and has little economic value.

An overburden management plan was developed in 2006 that determined the ideal location for the

overburden stockpile would be in the gully directly southwest of the pit, see site plan included as

Figure 1. In this situation the completed stockpile would screen the exposed south eastern aspect of

the quarry.

2 CURRENT SITUATION The design philosophy for the overburden stockpile was to use an existing dump area in a gully as a

base, building up a stockpile on top to form an artificial ridge to screen the quarry. The layers applied

would be graded towards the quarry so that runoff would be directed into a controlled drainage

system and not allowed to cascade down the long outside batters. The drainage system was to direct

the runoff water around the outside of the dump in natural ground.

In practice, runoff water has percolated through the permeable fill material until it has found the

natural surface and followed this surface under the dump. Where the fill batter and the natural

surface meet, the runoff water has built up pore pressure within the fill materials causing localised

slip that has destabilised the batter above until a thin outer layer of the standing stockpile has

moved down slope. The product of the slip has been deposited in the gully below the stockpile. This

deposited material appears to continue to move, apparently liberating silt into water running

beneath and discharging into the Mafeking Creek at the point of convergence.


Integrated Land Management and Planning | Risk assessment 4

3 RISK ASSESSMENT The Overburden Management Plan (Hazell, 2006) found the following risks were apparent with the

establishment of the overburden stockpile.

TABLE 1: ENVIRONMENTAL RISKS

Hazard Likelihood / Consequence

Risk rating Controls Risk rating with

control

Excessive noise impact on neighbours.

D / 2 Low Stockpile developed to screen vehicle movements (3)

(E / 3) Low

Excessive dust causes visual impact.

D / 2 Low Slow vehicle speeds (5) (E / 2) Low

Visual impact

C / 3 Moderate Minimise extent of disturbance (3)

(D / 3) Low

Impact on native flora and fauna

B / 3 High Minimise extent of disturbance (3)

Reinforce accidental spill procedure (5)

Have spill kits on hand at all times (6)

(D / 3) Low

Sediment is deposited in watercourse

B / 3 High Direct runoff to defined paths separate from stockpiles (4)

Encourage vegetation (4)

(C / 3) Moderate

Landslip C / 4 High Compact material in layers (5)

Keep runoff and drainage away for stockpile (4)

Encourage vegetation (4)

(D / 4) Moderate

TABLE 2: OCCUPATIONAL RISKS

Hazard Likelihood / Consequence

Risk rating Controls Risk rating with

control

Reversing over edge C / 5 Extreme No dumping over edge (5)

(F / 5) Low

Traffic / pedestrian collision.

C / 5 Extreme Slow vehicle speeds (5) (E / 5) Moderate

The Risk Assessment Matrix, Risk Level Action table and Hierarchy of Controls are located in the

appendices.


Integrated Land Management and Planning | Aims 5

4 AIMS There are a number of engineering solutions that can be employed to resolve the stability problems

with the overburden stockpile. There will be actions to control runoff water from behind the

stockpile; control runoff water from the stockpile surface; stabilise the stockpile and to capture

water below the stockpile to retain the entrained silt.

The actual solutions implemented will depend on several variables such as:

Has the stockpile reached equilibrium or is part of the batter still moving and if so by how

much?

Is the current state of the stockpile contributing to the sediment load in the Mafeking Creek

and if so by how much?

What is the actual slope of the stockpile outer batter and is this slope sustainable?

The aim of this monitoring program is to gather information over a period of time to answer the

questions posed above. The evaluation of the monitoring program will ensure that the final solutions

agreed to resolve the overburden stockpile stability problems will be targeted, appropriate and

effective.

5 RAINFALL RECORDS There is no doubt that the problems with the stability of the overburden stockpile are affected by

rainfall, both percolating through the product and cascading down slope. All the data captured by

the Overburden Stability Monitoring Program will analysed in the context of the recorded rainfall.

A rain gauge has been set up on the Leslie Vale Quarry site and the actual rainfall will be recorded six

days per week on a daily basis. The amount in the gauge will be recorded at 9:00 am each day to find

the actual 24 hour total for the site and the results tabulated. A sample rainfall recording chart is

included in the appendices.

6 STABILITY MONITORING To devise a solution to stabilise the outer batter of the overburden stockpile it is essential to

determine whether the deposited material is still moving and by how much.

If the deposit is in equilibrium and unlikely to move further it will be possible to stabilise with a

targeted planting of deep rooted shrubs and trees that will not only fix the deposit in place but also

screen the surface visually and help to control runoff water. A revegetation program will not be

successful however if the material is still moving. In this situation a structural solution may be

necessary to fix the deposit in place before the planting takes place.

To accurately record the movement of the outer batter of the stockpile a surveyor has been engaged

to install 5 permanent stakes in the surface of the stockpile. The locations of these stakes have been

accurately recorded. Subsequently, the surveyor will return each quarter to record the location of

the stakes and the rate of movement over time. The rate of movement during different seasonal

conditions will thus be recorded. The location of the recording stations are displayed on the plan

reproduced here as Figure 2.


Integrated Land Management and Planning | Water quality monitoring 6

7 WATER QUALITY MONITORING A report prepared in 2008 on the health of the North West Bay River catchment shows that in rain

events there is a problem in the lower reaches. This river health assessment concentrated on overall

river health as determined by macro-invertebrate diversity, but water quality was sampled and

reported over the period. Figure 3 is an extract from the 1:25000 series topographic maps with the

location of the sampling sites and the corresponding results for turbidity. There is no direct

correlation between turbidity and silt load although suspended solids, among other things, can

influence turbidity.

This river health assessment was conducted before the overburden stockpile was established and

well before the slump that has prompted this monitoring program. Clearly there are other factors

affecting the quality of the water in the North West Bay River.

The original risk assessment reproduced earlier in the document shows that the threat of siltation to

the receiving aquatic environment carries a moderate residual risk. The actual impact of the

stockpile in its current state is unknown. The current water quality program is deficient in that the

source of the silt entrained water is not identified if poor water quality is recorded. The testing is

undertaken regardless of the prevailing weather conditions so events of heavy rainfall where it is

likely that water quality will be affected are not targeted.

This targeted water quality monitoring program will add two more recording locations to the two

that are currently used. The two new sites will positively identify the source of turbid water should

water quality problems arise. Also the monitoring program will be triggered when a rainfall event

occurs that could potentially lead to water quality problems.

7.1 NEW SAMPLING SITES

In addition to the existing sampling sites on the downstream side of the culvert under the Huon

Highway and below the spillway on the Mafeking Creek dam two more sites will added:

A new sampling site will be established on the upstream side of the confluence of the

Mafeking Creek and the watercourse emanating from the overburden stockpile gully.

A new sampling site will be established on the downstream side of the confluence of the

Mafeking Creek and the watercourse emanating from the overburden stockpile gully.

The locations of the two new sites are recorded on the site plan Figure 1 as WQ1 and WQ2. Access

to the two new sites will be via a new access walking track highlighted in yellow on Figure 1.


Integrated Land Management and Planning | Acceptable limits for TSS 7

7.2 CLIMATIC TRIGGER FOR SAMPLING

Historic records for rain fall at weather stations close to the Leslie Vale site are displayed in table 2

below:

TABLE 3: HISTORIC DAILY RAINFALL (94239)

Year No. days when rainfall exceeds 10mm No. days when rainfall exceeds 25 mm

2006 11 2

2007 21 5

2008 15 4

2009 40 11

2010 21 6

2011 37 9

(BOM, 2012)

Based on the data above it is proposed that a 24 hour rainfall total of 20mm and above will be used

as the trigger to initiate the water quality testing program. On the day the record is made there will

be four samples taken, one each from the standard sites and one each from the new targeted sites.

Each sample will be tested for Total Suspended Solids (TSS) in accordance with the methods set out

in “Standard Methods for the Examination of Water and Wastewater” 17th Edition (1989), APHA – or

“Analysis of Raw, Potable & Waste Waters” HMSO 1972. The results will be tabulated and retained

for the preparation of a report at the culmination of the monitoring program.

8 ACCEPTABLE LIMITS FOR TSS In evaluating the data the results must be compared with the limits for TSS in inland waters set out

in the Quarry Code of Practice 1999. The code imposes a limit of 30 mg/L unless there is a dilution

factor of at least 50 times in the receiving environment, in which case a limit of 60 mg/L is imposed.

9 REPORTING The data gathered recording quarry site rainfall, total suspended solids for rainfall events and mass

movement of the stockpile will be complied into a report that will be prepared annually. The report

will compare the parameters with acceptable limits and the current assumptions of the causes and

effects of the overburden stockpile stability problems.

At the end of the monitoring period, a final report will be prepared that will draw on the evidence

complied over the monitoring period to make recommendations as to what final solutions will be

employed to treat the stability problem and diminish the risk. The monitoring period is proposed for

three years.

10 EARLY INTERVENTION If the routine monitoring shows evidence that the movement of the outer batter of the overburden

stockpile is accelerating or that acceptable water quality parameters are being regularly exceeded an

early intervention strategy will be developed to initiate early action to contain and mitigate the

effects..

H.B.M.I. Pty Ltd – Leslie Vale Quarry

Figure 1: Site Plan with new water quality monitoring points and access shown

Aerial imagery dated February 2011

Dolerite pit

Overburden stockpile

Limestone pit

Red gravel pit

Monitoring WQ2

Monitoring WQ1


Integrated Land Management and Planning | 10

Spring 2005 2.76

Autumn 2006 1.21

Spring 2007 1.84

Spring 2005 1.46

Autumn 2006 0.38

Spring 2005 11.03

Autumn 2006 1.17

Spring 2007 9.29

Spring 2005 14.3

Autumn 2006 1.08

Figure 3: Extract from 1:25000 topographic series showing water sampling points for River Health Assessment (DPIW, 2008)



11 APPENDIX

11.1 RISK ASSESSMENT MATRIX

Likelihood

Consequence

1 2 3 4 5 6

Insignificant Minor Moderate Major Extreme Catastrophe

A Almost certain

Low Moderate High Extreme Extreme Extreme

B Likely Low Moderate High Extreme Extreme Extreme

C Possible Low Low Moderate High Extreme Extreme

D Unlikely Low Low Low Moderate High Extreme

E Rare Low Low Low Low Moderate High

F Extremely rare

Low Low Low Low Low Moderate

11.2 RISK LEVEL ACTION TABLE

Risk rating Low Moderate High Extreme

Action Acceptable, activity can proceed, with controls.

Quarry Manager to assess efficacy of controls and authorise activity.

SHE Manager to assess efficacy of controls and authorise activity.

Unacceptable, activity cannot proceed.

11.3 HIERARCHY OF CONTROLS

Control Example

1 Eliminate Don’t proceed with activity or fundamentally rework activity to remove hazard.

2 Substitute Introduce alternative activity with lower risk rating.

3 Isolate Install permanent design features to protect against hazard.

4 Engineer out Change equipment used or introduce features to lower risk rating e.g. improved silencers on equipment.

5 Administrate Reinforce active controls through documented work procedures and toolbox meetings.

6 Response equipment

Provide workers with equipment to reduce severity of consequences e.g. hydrocarbon spill kits.



12 REFERENCES BOM. (2012, May 11). Climate Data Online. Retrieved May 11, 2012, from Australian Government -

Bureau of Meteorology:

http://www.bom.gov.au/jsp/ncc/cdio/weatherData/av?p_nccObsCode=136&p_display_type

=dailyDataFile&p_startYear=2011&p_c=-1783473529&p_stn_num=094239

DPIW. (2008). River Health of the North West Bay River Catchment - Water Assessment Branch.

Hobart: Department of Primary Industries and Water.

Hazell, M. a. (2006). Overburden Management Plan - HBMI Quarry, Leslie Vale Tasmania. Hobart:

unpublished.

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