Hornsby€Shire€Council · Hornsby€Shire€Council Review€of€Options€for€Filling Hornsby€Quarry Discussion€Paper March€2009. PUBLIC COPY Certain confidential information

Hornsby Shire Council

Review of Options for FillingHornsby QuarryDiscussion Paper

March 2009

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PUBLIC COPY Certain confidential information has not been released as it is considered Commercial in Confidence as prescribed in section 10A (2)(c)&(d) of the Local Government Act. Certain confidential information if released could confer a commercial advantage to a respondent or prejudice the competitive position of the proponent who supplied it.

21/18362/148916Review of Options for Filling Hornsby QuarryDiscussion Paper

Contents

1. Introduction 1

1.1 Scope of work 1

1.2 Definitions 1

1.3 Licensing and Section 88 Levy 2

2. Generation and Disposal of Nonputrescible Solid Wasteand VENM in Sydney 3

2.1 Sources and Quantities 3

2.2 Disposal sites for Non Putrescible Waste 4

2.3 VENM Disposal Options 5

3. Description of Hornsby Quarry 8

4. General Description of the Two Options 11

4.1 General 11

4.2 Filling with NonPutrescible Solid Waste 11

4.3 Filling with VENM/Spoil 12

5. Summary and Comparison of the Options 13

6. Financial Implications 22

7. SWOT Analysis 24

8. Conclusions 25

9. References and Bibliography 26

Table IndexTable 1 Existing nonputrescible waste landfills in Sydney 4Table 2 VENM/Spoil reuse sites 6Table 3: Summary and Comparison of the Options 14Table 4 Financial comparisons of different indicative

scenarios 22Table 5 Preliminary SWOT Analysis 24

21/18362/ Review of Options for Filling Hornsby QuarryDiscussion Paper

Figure IndexFigure 1: Location of NonPutrescible Landfill and VENM sites in

Sydney 7Figure 2: Location of Hornsby Quarry 9Figure 3: Section of Backfilled Quarry Void (from PSM, 2007) 21

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1. Introduction

Hornsby Shire Council is currently considering two options for the rehabilitation and utilisation of theHornsby Quarry:

1. Filling the quarry with nonputrescible solid waste; or

2. Filling the quarry with Virgin Excavated Natural Material (VENM).

1.1 Scope of workThis discussion paper provides a brief description of the potential sources and quantities of nonputrescible solid waste and VENM generated in Sydney, a description of the Hornsby Quarry site, ageneral description of the two options, a high level evaluation of the two options considering planning,engineering, environmental and financial issues, and some conclusions of the evaluation. A summary ofthe evaluation is provided in the body of this report and details are provided in Appendix A.

1.2 Definitions

Nonputrescible Solid Waste

The NSW EPA classify general solid waste as either putrescible or nonputrescible. Nonputresciblesolid waste must not contain any wastes that are capable of significant biological transformation.Typically, nonputrescible solid wastes include glass, plastic, rubber, plasterboard, ceramics, bricks,concrete, metal, paper or cardboard, household waste from municipal cleanup that does not containfood waste, garden waste, wood waste, building and demolition waste, and waste collected by, or onbehalf of, local councils from street sweeping. A more comprehensive definition of nonputrescible solidwaste is provided in the Waste Classification Guidelines Part 1 : Classifying Waste (DECC, 2008).

VENMThe NSW DECC classifies Virgin Excavated Natural Material (VENM) as (from DECC, 2008) naturalmaterial:

» that has been excavated or quarried from areas that are not contaminated with manufacturedchemicals or process residues, as a result of industrial, commercial, mining or agricultural activities,and

» that does not contain sulphidic ores or soils, and includes excavated natural material that meets suchcriteria for virgin excavated natural material as may be approved for the time being pursuant to anEPA gazettal notice.

This definition is used as the legal basis for licensing, and for application (or exemption from) the Section88 Waste Levy. Clause (a) provides the basic definition of VENM, while clause (b) enables the EPAinfluence whether particular materials can be received as VENM, as no additional criteria have beenapproved (and published) by EPA.


1.3 Licensing and Section 88 LevyLandfills or sites that receive inert wastes, including excavated materials and VENM, are generallyrequired to be licenced under the Protection of the Environment Operations Act 1997 (POEO Act) asinert waste landfills. However, there are exemptions under the Act.

A site that only receives VENM (any amount) is not required to become licenced as a landfill. However,other licences under the POEO Act may be required, particularly if there is potential for site operations toimpact on ground or surface waters.

All waste disposed of at a licenced landfill site must be recorded and a levy paid to the NSWGovernment, under Section 88 of the POEO Act. Currently the levy is $47/tonne of waste received at thesite. The Section 88 levy of the POEO Act only applies to material received at licenced (inert or solidwaste) landfills. It does not apply to facilities that only receive VENM. At licenced landfills, a rebate fromthe Section 88 levy can be claimed back from the EPA for material (including VENM), which is receivedand used for operational purposes.

An example of how the licencing provisions apply in practice to a VENM only receival site is at theBesmaw facility, which is located at Captain Cook Drive, Kurnell. This facility uses VENM toprogressively rehabilitate the void created by sand extraction on the property. The operator is notrequired to hold an inert waste landfilling licence, and no Section 88 Waste Levy is payable on the VENMreceived.

However, the site operator is required to hold an Environmental Protection Licence, under the POEO Act,which outlines the conditions for operating the facility and monitoring environmental impacts. Theseinclude requirements to ensure that all material received at the facility is actually VENM, and annualreporting requirements for the EPA.


2. Generation and Disposal of Nonputrescible SolidWaste and VENM in Sydney

The potential attractiveness of the Hornsby Quarry site for disposal of nonputrescible waste, or forVENM/spoil disposal depends upon the likely sources of each material, the volumes being generated,and the location and costs associated with alternative disposal sites compared with Hornsby Quarry. Asummary is provided below:

2.1 Sources and Quantities

2.1.1 Non putrescible waste

Approximately 3.5 million tonnes of nonputrescible waste (comprising commercial and industrial andconstruction and demolition waste) is disposed of to landfill each year in Sydney (WSC, 2008). Some ofthe commercial and industrial waste contains food and has to be disposed of in putrescible wastelandfills, but the majority is nonputrescible or inert. It can therefore be landfilled at a number of landfillsites across Sydney.

2.1.2 VENM/spoil

The major sources of VENM/spoil are land development and major infrastructure projects. Generally,most VENM generated by land developers is utilised on site, through balanced cut and fill approach tosubdivision design. Small building contractors often do not have the ability to reuse the material on site,other projects are not conveniently located or able to receive the material when it is required to leave thebuilding site. They are often forced to dispose of the spoil at landfill sites, or at VENM only disposal sites,of which there are very few.

When considering spoil reuse / disposal, the order of magnitude and timing are key to determiningfeasible options. Small quantities can be utilised on a large number of construction projects or acceptedat other disposal sites (such as landfills or mining voids), but larger quantities often require specialarrangements to be negotiated. Also, the possibility of such arrangements depends on the timing of othermajor construction projects that require fill coinciding with the period when spoil is being generated.

Estimates of the amount of VENM produced in Sydney annually, and requiring disposal are veryunreliable, as they depend upon whether any major projects are taking place. A major project like thecancelled North West Rail Link would have generated 34 million m3 of VENM over a 2 year period, andmost of this material could not have been absorbed by building projects. VENM from the Parramatta Raillink was used on the M7 Motorway construction project, as well as many other projects around Sydney.

Disposal of spoil from major tunnelling projects is a major issue, because of the large volumes ofmaterial, and the fact that it is produced for 24 hours a day at a number of worksites, and must beremoved from these worksites within a few hours because of lack of storage space. In this respect, a sitelike Hornsby Quarry, with the capacity to take millions of cubic metres of VENM would be very attractivefor proponents of a major project that generated large quantities of VENM.


2.2 Disposal sites for Non Putrescible WasteA list of non putrescible waste landfills within Sydney, is shown in Table 1.

Table 1 Existing nonputrescible waste landfills in Sydney

Name Licensed to Address

Penrith Waste(Penrith WasteServices)

Penrith Waste Services Pty Ltd 842 Mulgoa Road, Mulgoa 2745

Elizabeth Drive(SITA)

SITA Australia Pty Ltd 1725 Elizabeth Drive, Kemps Creek 2178

Schofields(Hlebar & Draga)

Hlebar; Draga North Street Schofields 2762

Kemps Creek(Kari & Ghossayn)

Kari & Ghossayn Pty Ltd Clifton Ave, Kemps Creek 2171

Kimbriki(Warringah Council)

Warringah Council Kimbriki Road, Terrey Hills 2084

Kurnell(Breen Holdings)

Breen Holdings Pty Ltd Captain Cook Drive, Kurnell 2231

Alexandria(DialaDump)

Alexandria Landfill Pty Ltd 10 Albert Street, St Peters 2044

Brandown Brandown Pty Ltd Lot 9 Elizabeth Drive, Kemps Creek 2178

Blacktown(Blacktown Council)

Blacktown Waste Services Pty Ltd Richmond Road, Marsden Park 2765

Horsley Park(Veolia)

Veolia Environmental Services(Australia) Pty Ltd

Wallgrove Road, Horsley Park 2164

Erskine Park(EnviroGuard)

Enviroguard Pty Ltd Quarry Road off Mamre Road, Erskine Park 2759

It should be noted that the Enviroguard landfill at Erskine Park is destined to close within a couple ofyears. There are also large clay mining voids in the Horsely Park area that could potentially be filled withnonputrescible waste (or VENM). Approximate capacity of potential and approved sites in the SydneyMetropolitan area for nonputrescible waste is 15 million m3.

Also, development approval is currently being sought for landfilling of nonputrescible waste at theWallgrove Quarry, which has the capacity to receive about 11 million m3 of waste. If this site is approvedas a nonputrescible landfill, it could make obtaining development consent for another landfill site egHornsby Quarry, more difficult. DirectorGeneral’s Requirements for new landfill sites generally specifythat the Environmental Impact Assessment (EA) must provide a detailed description of the need for theextra landfill capacity, which takes into account the capacity of other currently available facilities in theregion to accept the type of waste proposed, and the future demand for such a facility. This is commonlyknown as the “Justifiable Demand” for the landfill facility.


2.3 VENM Disposal OptionsThere are a number of options for disposal of VENM and clean spoil and these are described in thefollowing paragraphs.

2.3.1 Adaptive reuse into the construction industry

VENM can be accepted and reused on other construction sites with minimum effort and minimal cost.VENM does not normally require chemical testing prior to reuse, as it is a natural material by definition,However is some circumstances, for VENM to be received at another project site, some representativesamples may have to be tested for contamination, but once certified as not contaminated, it can be freelyused. Alternatively, the material can be further processed by an external party for use in the building orconstruction industry.

There are a number of applications for shale and sandstones found in the Sydney region. The techniqueused to extract the material, or the degree of processing, largely determines the materials likely reuseapplication. Hawkesbury sandstone can be used to produce coarse concrete sand (with processing), butit is likely that its greatest application would be as a select earth fill material in an unprocessed form.

Other potential applications for sandstone include as a lower level pavement material or low grade roadbase. Some shale types can be used as fill for building subbase road pavements others are suited tocrushing, grinding and processing to produce clay for vitrified products, including tiles, pipes and bricks.Low clay content shales are more suited to use as fill, while high clay content shales are more suited touse in brick making.

2.3.2 Adaptive reuse in beneficial land management

VENM can also be used in beneficial land management. For example, shale materials can be suitable ascover for contaminated land reclamation projects. The opportunities for reuse of spoil materials inbeneficial land management can sometimes be limited, as appropriate land management projects maynot be underway in the vicinity of the VENM generating activities.

2.3.3 Landfill management

VENM can be used for operational purposes at landfill sites, such as use in the final landfill capping layerand construction of perimeter containment (structural) bunding. However, landfill operators / owners areoften restricted to the amount of VENM that they are able to claim a Section 88 deduction.

Furthermore, often sufficient material is delivered to the landfill sites by smaller companies (such aslandscapers and builders), or is excavated from the site itself. Therefore, landfill operators / owners arenot usually seeking large quantities of VENM. But at this site, there will be need to import largequantities of VENM for use in regular daily covering of the landfilled waste (see Section 4.2).

2.3.4 VENM only receival sites

VENM can be received at VENM only facilities, such as extractive industry voids, without incurring theSection 88 waste levy. This means that disposal (gate) fees at VENM only sites are significantly lowercompared to other landfills. While there are a number of extractive industry voids in the Sydney region,


not all are potential VENM filling sites and only a few are currently operating as VENM only receival sites.One such site is the Holt Land Rehabilitation site at Kurnell.

Table 2 VENM/Spoil reuse sites

Company Location Spoil Reuse

Rocla Calga quarry Calga quarry is located 40 km north of Hornsby via the F3 Freeway and 1 kmalong Peats Ridge Rd. The quarry has a very large capacity,

Prospectrecyclingplant

Recycling of sandstone into building materials at the Prospect recycling plant.

Moorebankredevelopment site

Beneficial reuse at the Moorebank redevelopment site. Boral indicated thatshale materials could also be accepted at this site.

Boral

Badgery’sCreek BrickPlant

Boral has also indicated that there may be opportunities for reuse of particulartypes and qualities of shale by the Brick Division at it’s Badgery’s Creek plant.

Penrith LakesDevelopmentCorporation

PenrithLakesScheme

Beneficial reuse as fill material in the Penrith Lakes scheme for both shaleand sandstone materials.

Ecocycle / AWJCivil

WetherillPark

AWJ Civil, through Ecocycle can often accept large quantities of VENM forbeneficial reuse in their industrial projects as fill material.

Holt LandRehabilitation

Kurnell VENM only receival site, for land rehabilitation of former sand mining areas.

The locations of the above listed spoil reuse options are spread across the greater Sydney region, asshown on Figure 1.

2.3.5 Disposal at landfill

If the excavated materials (spoil) are classified as inert waste (i.e. their characteristics do not allow themto be classified as VENM), they can be disposed of to an appropriately licensed landfill. Howeverdisposal of the material to landfill incurs a waste levy.

Disposal of clean spoil material at landfills is not a preferred reuse option, but can occasionally benecessary to maintain construction progress. A typical charge is $75 per tonne (at the Kimbriki landfill inTerrey Hills), which includes the waste levy, currently $47/tonne.


Figure 1: Location of NonPutrescible Landfill and VENM sites in Sydney


3. Description of Hornsby Quarry

The Hornsby Quarry is located approximately 1 km west of the Hornsby CBD (see Figure 2). The sitewas worked as a hard rock quarry from the early 1900’s to the late 1990’s.

The total site occupies some 29 hectares, of which quarry void occupies between 8 and 11 hectares.The quarry extends to RL 8m AHD and the surface area of the quarry void at RL 90m AHD isapproximately 80,000 m2 (PSM, 2007). The volume of the quarry void (to RL 90m AHD) has beenestimated to be about 3.3 million m3 (PSM, 2007).

The quarry void is located in the Hornsby diatreme, which is surrounded by Hawkesbury sandstone.Ashfield shale outcrops to the east and north east of the quarry. The diatreme is principally composed ofvolcanic breccia, with zones of muddy breccia. An exposed section of the diatreme within the quarry hasheritage value, and consideration needs to be given to it preservation.

According to PSM (2007) two systems of groundwater occur at the site:

» A shallow perched water system located within the fills and underlying weathered breccia rock; and

» A deeper system located within the fresh breccia and surrounding Hawkesbury sandstone.

PSM (2007) estimates that groundwater inflow to the quarry void to be approximately 0.3 litres persecond at the current water level. It is noted that the groundwater inflow is dependent upon the waterlevel in the quarry and the weather conditions.

Surface water at the site drains either into the quarry void, or into a surface drain located on the northernand western perimeter of the quarry void, which discharges to the southwest into Old Man Creek.

Buffer distances at the site are (see Figure 1):

» Site entrance to Dural St residences: ~150m;

» Internal access rd to TAFE (Main campus):~330m;

» Internal access rd to TAFE (nearest building): ~300m;

» Quarry void to Ferntree Close residences: ~150m;

» Quarry void to Manor Rd residences: ~180m; and

» Quarry void to Mt Wilga Hospital (boundary): ~320m.


Figure 2: Location of Hornsby Quarry


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4. General Description of the Two Options

4.1 GeneralFilling of the site with either nonputrescible waste or VENM would generally require:

» Determination of the most appropriate level to fill the site, taking into account the heritage value ofthe exposed section of the diatreme, the impacts of the fill type on the final land use, and the desiredfinal land use;

» Engineering design to develop the chosen filling and final rehabilitation scheme;

» Undertaking an Environmental Impact Assessment and obtaining development consent for thescheme, including community consultation;

» Dewatering of the quarry void, which would be a significant activity involving pumping approximately450,000 m3 (or 450ML) of water from the void, and ongoing water management;

» Possible upgrading of the access routes or developing alternative access routes, depending uponthe environmental impacts of the proposed filling rate;

» Establishing suitable facilities at the site including weigh bridge, gatehouse, site office and staffamenities;

» Upgrading internal access roads – to facilitate two way heavy vehicle access into the quarry void,where possible (it may not be possible in all locations, due to physical constraints);

» Possible relocation of the internal access road through Old Man Valley;

» Filling of the site over many years; and

» Rehabilitating the final landform, for the intended final land use.

Aspects of the two filling options are described in more detail in the following sections.

4.2 Filling with NonPutrescible Solid WasteFilling of the Hornsby Quarry void with nonputrescible solid waste would generally involve the followingadditional activities:

» Obtaining all necessary approvals and licensing, including rezoning of the site to allow landfilling,obtaining development consent, and obtaining an Environment Protection Licence for the landfillingoperation;

» Improving access to the site (depending on the filling rate) by identifying suitable routes through thewestern side of Hornsby;

» Preparing the site to receive and landfill general solid waste (nonputrescible), including:

– Establishing suitable facilities at the site including weigh bridge, gatehouse, site office and staffamenities;

– Lining the base and sides of the quarry with low permeability material(s) and establishing leachateand stormwater collection and disposal systems according to DECC requirements for nonputrescible waste landfills;


» Receiving and landfilling nonputrescible solid waste, which may occur over a long period of time,depending on the supply of waste materials and the landfilling rate. There would also be a need toimport VENM or a suitable waste material to cover the landfilled waste;

» Capping and rehabilitating the final landform in accordance with DECC requirements, for the intendedfinal land use; and

» Monitoring and managing the site, until such time as monitoring shows that the landfilled waste hasstabilised and no longer presents a threat to the environment. This could be for a period of greater 50years or more after landfilling ceases. There would also be landfill gas carbon emission liabilitiesunder the proposed Carbon Pollution Reduction Scheme (CPRS) throughout much of this period.

4.3 Filling with VENM/SpoilFilling of the Hornsby Quarry void with VENM/spoil would generally involve the following additional steps:

» Obtaining all necessary approvals and licensing, possibly including possible rezoning of the site toallow filling, and obtaining development consent. Note, an Environment Protection Licence is notrequired for filling with VENM;

» Preparing the site to receive and fill the quarry void with VENM, which may involve establishingsuitable facilities at the site including weigh bridge, gatehouse, site office and staff amenities;

» Improving access to the site (depending on the filling rate) by identifying suitable routes through thewestern side of Hornsby;

» Receiving and filling VENM, which may occur over a long period of time, depending on the supply ofmaterials and the filling rate;

» Rehabilitating the final landform, for the intended final land use; and

» Monitoring and managing the site. Unlike filling the void with waste there would not be a longtermrequirement to monitor leachate or landfill gas, but there would likely be a need to monitor settlementof the fill, at least in the short to medium term.


5. Summary and Comparison of the Options

In this section, the two options are evaluated and compared considering the following:

» Planning and approvals;

» Final land use and landform;

» The type and source of fill material;

» The duration of the filling operation;

» Design, engineering, and operational issues;

» Potential environmental issues, management and monitoring;

» Post closure management; and

» Financial implications.

The results of the evaluation are summarised in Table 3.


Table 3: Summary and Comparison of the Options

Aspect Filling with NonPutrescible Solid Waste Filling with VENM

1. Planning & approvals Rezoning would be required to permit landfilling.

Development consent required. Need to undertakeEnvironmental Impact Assessment (EIA), possibly aPart 3A Assessment due to the large volume ofwaste required to fill the void. It may be very difficultto justify the need / demand for another nonputrescible waste landfill in Sydney, if the currentproposal for the nonputrescible waste filling ofWallgrove quarry proceeds. The NSW DECC policyis to minimise landfill disposal capacity to increasediversion of waste from landfill (for recycling /processing). Due to the controversial nature oflandfill developments it would likely take asubstantial period of time to obtain all the necessaryapprovals, if able i.e. 3 – 5 years. There is apossibility of a Commission of Inquiry or Land &Environment Court action. Cost of obtainingdevelopment consent could be substantial (approx$1 M).

An Environment Protection Licence would berequired (for landfilling operation). This wouldrequire preparation of engineering drawings andspecifications and a Landfill EnvironmentalManagement Plan (LEMP) that meets DECCrequirements for landfilling operations. An LEMPdetails operational practices, environmentalmanagement and monitoring requirements, andstaging of the landfilling, including site rehabilitationand closure measures..

Rezoning may be required – an assessment of thecurrent LEP would need to be done to confirm this.

Development Approval will be required. Need toundertake some form of Environmental ImpactAssessment (EIA), the extent depending upon theproposed rate of filling.

Environment Protection Licence may not berequired.

Not as controversial a development as landfillingwith waste, due to the lower potential adverseenvironmental impacts, and therefore may be easierto obtain all necessary approvals. But this cannotbe guaranteed, as there would be significantenvironmental impacts for nearby residents if thecurrent site access route is used and there are highrates of filling for extended periods.


2. Final land use and landform Final land use would be constrained by thelandfilled waste, due to large depth of waste andconsequent settlement (possibly 8 – 16 m over a 20to 30 year period), landfill gas management controlmeasures and potential for emissions, and leachatemanagement control measures and potential foremissions. Due to large potential settlement,realistic options for the filled area include openspace, passive recreation (walking trails), andpossibly a nature reserve. Note, there would be aneed for regular monitoring and maintenance of thefinal landfillcapping layer to ensure its integrity.

A number of final landforms have been evaluated byvarious parties. The most practical would appear tobe to fill to the rim of the quarry void (RL88 – 90mAHD) and stabilise the southern and northernbuttresses. However, this option would result in thediatreme being covered. Also this option would notbe suitable for playing fields. Other partial fillingoptions that preserve the views of the diatremehave also been previously considered. Suchoptions create both geotechnical and stormwatermanagement challenges (short and long term),particularly if the void is filled with nonputresciblewaste, which may not be able to be overcome.Also, the volume to be filled is substantiallyreduced, from 4.2 million m3 to 2 million m3.

Final land use would also be constrained, butperhaps not as much, due to lower settlement of thefill (1 – 2m), if properly compacted whilst filling. Noissues with landfill gas or leachate.

Landform options as per nonputrescible wasteoptions, although playing fields may be possible inthe medium term once the major settlement periodhas been largely completed. This period may beable to be accelerated by faster filling of the site.

Filling the site with VENM would reduce thetechnical challenges associated with preservingviews of the diatreme, but long term stormwatermanagement would still be a significant issue.


3. Fill materials Nonputrescible solid waste. See Section 1.2 fordefinition.

Quantity dependent on final landform and density ofthe waste once landfilled. If the site were filled toRL 90m AHD (rim of quarry void) + buttresses (totalfill volume of 4.2 million m3, as per PSM, 2007 – seeFigure 3), would require approximately 5.0 milliontonnes of nonputrescible waste (compacted to anaverage density of 1.2 t/m3).

In addition, approximately 850,000m3 (1.3 milliontonnes) of soil would be required for coveringpurposes, unless an alternative daily cover materialis used. In addition, significant quantities of clayfinal capping and topsoil (80,000 – 100,000m3)would be needed to rehabilitate the site after fillingwas completed.

Virgin Excavated Natural Material (VENM). SeeSection 1.2 for definition of this material.

Quantity dependent on the final landform anddensity of the VENM once placed. Approximately7.1 million tonnes of VENM would be required(@1.7 t/m3) to fill to RL 90m AHD (rim of quarryvoid) and the buttresses as per PSM report (2007) –see Figure 3.

There would be a need for additional cover material.

The sources of VENM in Sydney are wide andvaried. However, to fill the quarry void in theminimum time period would require obtainingmaterial from a series of major infrastructureprojects e.g. CBD or West Metro, M4 East, F3Extension. Typically, more than 1 million tonnes ofVENM could be expected from a large tunnellingproject each year, however the timing of suchprojects is generally uncertain.

For projects in the north and north west of Sydney,Hornsby Quarry would be a convenient VENMdisposal location.

Between large projects, it may be possible to attract(through competitive pricing) 50,000 100,000tonnes per year of VENM from small to mediumsized building projects.


4. Duration of the fillingoperation

The duration of the landfilling operation would bedependent on the filling rate, which would bedependent on the nonputrescible waste disposalmarket. There is likely to be more nonputresciblewaste available (than VENM) and therefore thequarry void would likely be filled much quicker. At500,000 tonnes of waste per year, which is a largescale landfilling operation, the site would be filled in~10 years.

A high and stable filling rate could be achieved if amajor waste management company were engagedto undertake the filling eg. WSN and / or TPI, asthey have access to large quantities of wastethrough their waste transfer stations, and largevehicles that could bulk haul the same amount ofwaste in fewer loads.

At 50,000 tonnes per year, which is a significantlylower rate of landfilling, consistent with the averagerate at which rock was extracted from the quarry,and transported from the site, the duration of fillingwould be about 100 years.

The duration of filling is likely to be longer due to alower rate of filling, dependent on the timing andscale of major developments / infrastructureprojects that generate VENM e.g. North WestMetro, M4 East, F3 extension.

At 500,000 tonnes per year the duration of fillingwould be approximately 14 years

At 50,000 tonnes per year the duration of fillingwould be approximately 140 years.


5. Design, engineering andoperational issues

Local access roads may require upgrading,depending on the rate of landfilling.

Site entrance may need to be relocated, dependingon the rate of landfilling.

Internal site access roads require upgrading. Singlelane traffic flow (in some locations) may causeoperational problems.

Need to implement landfill leachate containment,collection, treatment and disposal system, whichwould be technically very challenging due to thedepth of waste to be placed at the site, and thephysical setting within the quarry void.

Also need to implement landfill gas managementmeasures during landfilling.

There would be significant engineering challenges ifthe void were partially filled to preserve the view ofthe diatreme. This would include geotechnical aswell as stormwater and leachate managementissues.

Same possible need to upgrade local roads, siteaccess road and entrance, plus internal site accessroads, depending on the rate of landfilling.

No need for leachate containment, collection,treatment and disposal system.

No need for landfill gas management measures.

Reduced engineering issues if the site is partiallyfilled to preserve views of the diatreme, but thesewould still be significant.


6. Environmental issues,management and monitoring

Potential environmental issues include:

» Traffic noise and nuisance;

» Landfill leachate emissions and contamination oflocal surface and groundwater;

» Landfill gas emissions, which, if not properlymanaged, could present a hazard to users of thesite and surrounding land

» Odour nuisance;

» Other noise, dependent on the scale of thelandfilling operation

» Pest and vermin, including birds (minor risk);

» Litter, around the site boundaries and possiblyalong roads leading to the site (minor risk);

» Stormwater runoff quality;

The rate of landfilling would determine the flow ofvehicles to / from the site, and its consequentimpacts. A landfilling rate of 500,000 tonnes peryear would mean approximately 80 100 largetrucks per day e.g. semitrailers, or trucks withtrailers. However if only 50,000 tonnes per year waslandfilled, there may be no large trailers, but therecould be up to 70 smaller trucks (averaging 3m3)per day, plus local residents with cars and trailers.

Whilst traffic impacts would only occur during filling,potential leachate and landfill gas impacts, andimpacts on stormwater quality, would exist for aperiod of 30 to 50 years after filling has stopped.

Potential environmental issues:

» Traffic noise and nuisance;

» Dust, dependent on method of filling

» Other noise, dependent on the scale of thelandfilling operation (minor risk only);

» Stormwater runoff quality (minor risk only)

» Note, the rate of filling would determine the flowof vehicles to / from the site, and consequentimpacts.

A filling rate of 500,000 tonnes per year would meanapproximately 80 100 large trucks per day e.g.semitrailers, or trucks with trailers.

However if only 50,000 tonnes per year waslandfilled, there may be no large trucks, but therecould be up to 70 smaller trucks (averaging 3m3)per day.


7. Post closure management Post closure management and monitoring would besignificantly more complex due to:

» Large settlement of the landfilled waste;

» Leachate management;

» Landfill gas management;

» More rigorous environmental monitoring;

Active management and monitoring would berequired for 30 to 50 years or more.

Post closure management and monitoring would beless due to:

» Less settlement;

» No landfill leachate or landfill gas; and

» Less monitoring.

Period of active management and monitoring maybe less than 10 years.


Figure 3: Section of Backfilled Quarry Void (from PSM, 2007)


7. SWOT Analysis

A preliminary SWOT (strengths, weaknesses, opportunities and threats) analysis of the two options, attwo different filling rates, is presented below in Table 5.

Table 5 Preliminary SWOT Analysis

Option Strengths Weaknesses Opportunities Threats

Filling with nonputrescible waste –low rate (less than50,000 tonnes peryear)

Approval processmay be easier andresident concernsshould be minimised.Traffic impacts maybe more acceptableto local residents.

Filling of sitewould takeapproximately 100years. Long termenvironmentalissues

There are relatively fewwaste disposal sites inSydney, therefore itmay be popular for localresidents and businessin northern Sydney. Thesite will outlast Kimbrikiby many years – willend up as the only nonputrescibles, lowvolume disposal site innorthern Sydney.

Liner and leachatecollection system are stillrequired, even for very lowfilling rates. Gate feeswould need to berelatively high because ofhigh fixed costs, plus levy– site may becomecommercially unattractivefor waste companies touse.

Filling with nonputrescible waste –high rate (more than500,000 tonnes peryear)

Site could potentiallybe filled in 1020years, with highrevenue for Council.

Potential majorimpact on localresidents. CPRSliability andenvironmentalmonitoring andmanagement willbe long termissues. However,revenue can allowfor this.

Revenue from high ratelandfilling could be usedto purchase affectedproperties. Gate feescan be lowered asthroughput increases.

New landfills in WesternSydney such as WallgroveQuarry may be approved,which are moreconvenient for wastecompanies than HornsbyQuarry.

Filling with VENM –low rate (less than50,000 tonnes peryear)

Site is well locatedfor smaller projects inwest, north and northwest. No CPRSliability if VENM usedinstead of waste.Traffic impacts maybe more acceptableto residents

Amount of VENMavailable fromsmaller projectslikely to be small,so filling couldtake > 100 years.

There are very few siteswhere Section 88 levy isnot payable, so gatefees could be keptrelatively low.

Low rate of filling makesoperational costs for sitequite high – still need tohave staff on site, plusamenities and maintainsite roads for long period.

Filling with VENM –high rate(more than 500,000tonne per year)

Large revenue overshort period (possiblynet $2030 millionover 2 years) duringmajor projects, ifaverage of 1 millionm3 of VENM isreceived each year.

Traffic impactswould beconsiderable forlocal residents,Large projectsinfrequent – maytake a few largeprojects over 20years to fill thevoid.

Site could be run on acampaign basis, everytime a large projectoccurs, specialarrangements madewith residents, use forgeneral buildingprojects in between.

Other sites will also beavailable, but none are innorth


9. References and Bibliography

Department of Environment and Climate Change, 2008. Guide to Licensing Under the Protection of theEnvironment Operations Act 1997 Part B.

NSW EPA, 1996. Environmental Guideline: Solid Waste Landfills. ISBN 0 7310 3774 X

PSM, 2007. Former CSR Quarry & Associated Lands. Report prepared for Hornsby Shire Council,February 2007.

WCS, 2008, The Blue Book – Australian Waste Industry 2007/8 Industry and Market Report, WrightCorporate Strategy

21/18362/148916 Review of Options for Filling Hornsby QuarryDiscussion Paper

GHD

10 Bond Street Sydney NSW 2000T: 2 9239 7100 F: 2 9239 7199 E: [email protected]

© GHD 2009

This document is and shall remain the property of GHD. The document may only be used for the purposefor 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

Reviewer Approved for IssueRevNo. Author

Name Signature Name Signature Date

A S Dever D Gamble Draft 17.3.09

B S Dever D Gamble D Gamble 20.3.09

C S Dever D Gamble D Gamble 20.3.09

D S Dever D Gamble D Gamble 20.3.09

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