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.
Hornsby Shire Council
Review of Options for Filling
Hornsby Quarry
Discussion Paper
March 2009
Contents
1.
2.
Introduction
1
1.1
Scope of work
1
1.2
Definitions
1
1.3
Licensing and Section 88 Levy
2
Generation and Disposal of Non-putrescible Solid Waste
and 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 Non-Putrescible 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 Index
Table 1
Existing non-putrescible waste landfills in Sydney
4
Table 2
VENM/Spoil reuse sites
6
Table 3:
Summary and Comparison of the Options
14
Table 4
Financial comparisons of different indicative
scenarios
22
Preliminary SWOT Analysis
24
Table 5
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Figure Index
Figure 1: Location of Non-Putrescible Landfill and VENM sites in
Sydney
7
Figure 2: Location of Hornsby Quarry
9
Figure 3: Section of Backfilled Quarry Void (from PSM, 2007)
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BLANK PAGE
1.
Introduction
Hornsby Shire Council is currently considering two options for the rehabilitation and utilisation of the
Hornsby Quarry:
1.
Filling the quarry with non-putrescible solid waste; or
2.
Filling the quarry with Virgin Excavated Natural Material (VENM).
1.1
Scope of work
This discussion paper provides a brief description of the potential sources and quantities of non
putrescible solid waste and VENM generated in Sydney, a description of the Hornsby Quarry site, a
general 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 of
the evaluation is provided in the body of this report and details are provided in Appendix A.
1.2
Definitions
Non-putrescible Solid Waste
The NSW EPA classify general solid waste as either putrescible or non-putrescible. Non-putrescible
solid waste must not contain any wastes that are capable of significant biological transformation.
Typically, non-putrescible solid wastes include glass, plastic, rubber, plasterboard, ceramics, bricks,
concrete, metal, paper or cardboard, household waste from municipal clean-up that does not contain
food waste, garden waste, wood waste, building and demolition waste, and waste collected by, or on
behalf of, local councils from street sweeping. A more comprehensive definition of non-putrescible solid
waste is provided in the Waste Classification Guidelines Part 1 : Classifying Waste (DECC, 2008).
VENM
The NSW DECC classifies Virgin Excavated Natural Material (VENM) as (from DECC, 2008) natural
material:
»
that has been excavated or quarried from areas that are not contaminated with manufactured
chemicals 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 such
criteria for virgin excavated natural material as may be approved for the time being pursuant to an
EPA gazettal notice.
This definition is used as the legal basis for licensing, and for application (or exemption from) the Section
88 Waste Levy. Clause (a) provides the basic definition of VENM, while clause (b) enables the EPA
influence whether particular materials can be received as VENM, as no additional criteria have been
approved (and published) by EPA.
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1.3
Licensing and Section 88 Levy
Landfills or sites that receive inert wastes, including excavated materials and VENM, are generally
required to be licenced under the Protection of the Environment Operations Act 1997 (POEO Act) as
inert 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 to
impact on ground or surface waters.
All waste disposed of at a licenced landfill site must be recorded and a levy paid to the NSW
Government, under Section 88 of the POEO Act. Currently the levy is $47/tonne of waste received at the
site. The Section 88 levy of the POEO Act only applies to material received at licenced (inert or solid
waste) landfills. It does not apply to facilities that only receive VENM. At licenced landfills, a rebate from
the Section 88 levy can be claimed back from the EPA for material (including VENM), which is received
and used for operational purposes.
An example of how the licencing provisions apply in practice to a VENM only receival site is at the
Besmaw facility, which is located at Captain Cook Drive, Kurnell. This facility uses VENM to
progressively rehabilitate the void created by sand extraction on the property. The operator is not
required to hold an inert waste landfilling licence, and no Section 88 Waste Levy is payable on the VENM
received.
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. These
include requirements to ensure that all material received at the facility is actually VENM, and annual
reporting requirements for the EPA.
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2.
Generation and Disposal of Non-putrescible Solid
Waste and VENM in Sydney
The potential attractiveness of the Hornsby Quarry site for disposal of non-putrescible waste, or for
VENM/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. A
summary is provided below:
2.1
Sources and Quantities
2.1.1
Non putrescible waste
Approximately 3.5 million tonnes of non-putrescible waste (comprising commercial and industrial and
construction and demolition waste) is disposed of to landfill each year in Sydney (WSC, 2008). Some of
the commercial and industrial waste contains food and has to be disposed of in putrescible waste
landfills, but the majority is non-putrescible or inert. It can therefore be landfilled at a number of landfill
sites 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 to
subdivision design. Small building contractors often do not have the ability to re-use the material on site,
other projects are not conveniently located or able to receive the material when it is required to leave the
building 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 determining
feasible options. Small quantities can be utilised on a large number of construction projects or accepted
at other disposal sites (such as landfills or mining voids), but larger quantities often require special
arrangements to be negotiated. Also, the possibility of such arrangements depends on the timing of other
major 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 very
unreliable, as they depend upon whether any major projects are taking place. A major project like the
cancelled North West Rail Link would have generated 3-4 million m 3 of VENM over a 2 year period, and
most of this material could not have been absorbed by building projects. VENM from the Parramatta Rail
link 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 of
material, and the fact that it is produced for 24 hours a day at a number of worksites, and must be
removed from these worksites within a few hours because of lack of storage space. In this respect, a site
like Hornsby Quarry, with the capacity to take millions of cubic metres of VENM would be very attractive
for proponents of a major project that generated large quantities of VENM.
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2.2
Disposal sites for Non Putrescible Waste
A list of non putrescible waste landfills within Sydney, is shown in Table 1.
Table 1
Existing non-putrescible waste landfills in Sydney
Name
Licensed to
Address
Penrith Waste
(Penrith Waste
Services)
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
(Dial-a-Dump)
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 of
years. There are also large clay mining voids in the Horsely Park area that could potentially be filled with
non-putrescible waste (or VENM). Approximate capacity of potential and approved sites in the Sydney
Metropolitan area for non-putrescible waste is 15 million m 3.
Also, development approval is currently being sought for landfilling of non-putrescible waste at the
Wallgrove Quarry, which has the capacity to receive about 11 million m 3 of waste. If this site is approved
as a non-putrescible landfill, it could make obtaining development consent for another landfill site eg
Hornsby Quarry, more difficult. Director-General’
s Requirements for new landfill sites generally specify
that the Environmental Impact Assessment (EA) must provide a detailed description of the need for the
extra landfill capacity, which takes into account the capacity of other currently available facilities in the
region to accept the type of waste proposed, and the future demand for such a facility. This is commonly
known as the “Justifiable Demand”for the landfill facility.
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2.3
VENM Disposal Options
There are a number of options for disposal of VENM and clean spoil and these are described in the
following paragraphs.
2.3.1
Adaptive reuse into the construction industry
VENM can be accepted and re-used on other construction sites with minimum effort and minimal cost.
VENM does not normally require chemical testing prior to re-use, as it is a natural material by definition,
However is some circumstances, for VENM to be received at another project site, some representative
samples may have to be tested for contamination, but once certified as not contaminated, it can be freely
used. Alternatively, the material can be further processed by an external party for use in the building or
construction industry.
There are a number of applications for shale and sandstones found in the Sydney region. The technique
used to extract the material, or the degree of processing, largely determines the materials likely reuse
application. Hawkesbury sandstone can be used to produce coarse concrete sand (with processing), but
it 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 road
base. Some shale types can be used as fill for building sub-base road pavements others are suited to
crushing, 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 to
use 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 as
cover for contaminated land reclamation projects. The opportunities for reuse of spoil materials in
beneficial land management can sometimes be limited, as appropriate land management projects may
not 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 layer
and construction of perimeter containment (structural) bunding. However, landfill operators / owners are
often 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 as
landscapers and builders), or is excavated from the site itself. Therefore, landfill operators / owners are
not usually seeking large quantities of VENM. But at this site, there will be need to import large
quantities 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 the
Section 88 waste levy. This means that disposal (gate) fees at VENM only sites are significantly lower
compared to other landfills. While there are a number of extractive industry voids in the Sydney region,
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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 km
along Peats Ridge Rd. The quarry has a very large capacity,
Boral
Prospect
recycling
plant
Recycling of sandstone into building materials at the Prospect recycling plant.
Moorebank
redevelopment site
Beneficial reuse at the Moorebank redevelopment site. Boral indicated that
shale materials could also be accepted at this site.
Badgery’
s
Creek Brick
Plant
Boral has also indicated that there may be opportunities for reuse of particular
types and qualities of shale by the Brick Division at it’
s Badgery’
s Creek plant.
Penrith Lakes
Development
Corporation
Penrith
Lakes
Scheme
Beneficial reuse as fill material in the Penrith Lakes scheme for both shale
and sandstone materials.
Ecocycle / AWJ
Civil
Wetherill
Park
AWJ Civil, through Ecocycle can often accept large quantities of VENM for
beneficial reuse in their industrial projects as fill material.
Holt Land
Rehabilitation
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, as
shown 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 them
to be classified as VENM), they can be disposed of to an appropriately licensed landfill. However
disposal 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 be
necessary to maintain construction progress. A typical charge is $75 per tonne (at the Kimbriki landfill in
Terrey Hills), which includes the waste levy, currently $47/tonne.
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Figure 1: Location of Non-Putrescible Landfill and VENM sites in Sydney
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3.
Description of Hornsby Quarry
The Hornsby Quarry is located approximately 1 km west of the Hornsby CBD (see Figure 2). The site
was 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 is
approximately 80,000 m2 (PSM, 2007). The volume of the quarry void (to RL 90m AHD) has been
estimated to be about 3.3 million m 3 (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 of
volcanic breccia, with zones of muddy breccia. An exposed section of the diatreme within the quarry has
heritage 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 per
second at the current water level. It is noted that the groundwater inflow is dependent upon the water
level 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 northern
and 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.
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Figure 2: Location of Hornsby Quarry
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4.
General Description of the Two Options
4.1
General
Filling of the site with either non-putrescible waste or VENM would generally require:
»
Determination of the most appropriate level to fill the site, taking into account the heritage value of
the exposed section of the diatreme, the impacts of the fill type on the final land use, and the desired
final land use;
Engineering design to develop the chosen filling and final rehabilitation scheme;
»
»
Undertaking an Environmental Impact Assessment and obtaining development consent for the
scheme, including community consultation;
»
Dewatering of the quarry void, which would be a significant activity involving pumping approximately
450,000 m3 (or 450ML) of water from the void, and on-going water management;
»
Possible upgrading of the access routes or developing alternative access routes, depending upon
the environmental impacts of the proposed filling rate;
»
Establishing suitable facilities at the site including weigh bridge, gatehouse, site office and staff
amenities;
»
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 Non-Putrescible Solid Waste
Filling of the Hornsby Quarry void with non-putrescible solid waste would generally involve the following
additional 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 landfilling
operation;
»
Improving access to the site (depending on the filling rate) by identifying suitable routes through the
western side of Hornsby;
»
Preparing the site to receive and landfill general solid waste (non-putrescible), including:
– Establishing suitable facilities at the site including weigh bridge, gatehouse, site office and staff
amenities;
– Lining the base and sides of the quarry with low permeability material(s) and establishing leachate
and stormwater collection and disposal systems according to DECC requirements for nonputrescible waste landfills;
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»
Receiving and landfilling non-putrescible 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 to
import VENM or a suitable waste material to cover the landfilled waste;
»
Capping and rehabilitating the final landform in accordance with DECC requirements, for the intended
final land use; and
»
Monitoring and managing the site, until such time as monitoring shows that the landfilled waste has
stabilised and no longer presents a threat to the environment. This could be for a period of greater 50
years or more after landfilling ceases. There would also be landfill gas carbon emission liabilities
under the proposed Carbon Pollution Reduction Scheme (CPRS) throughout much of this period.
4.3
Filling with VENM/Spoil
Filling 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 to
allow filling, and obtaining development consent. Note, an Environment Protection Licence is not
required for filling with VENM;
»
Preparing the site to receive and fill the quarry void with VENM, which may involve establishing
suitable 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 the
western side of Hornsby;
»
Receiving and filling VENM, which may occur over a long period of time, depending on the supply of
materials 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 long-term
requirement to monitor leachate or landfill gas, but there would likely be a need to monitor settlement
of the fill, at least in the short to medium term.
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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.
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Table 3:
Summary and Comparison of the Options
Aspect
Filling with Non-Putrescible Solid Waste
Filling with VENM
1. Planning & approvals
Rezoning would be required to permit landfilling.
Rezoning may be required – an assessment of the
current LEP would need to be done to confirm this.
Development consent required. Need to undertake
Environmental Impact Assessment (EIA), possibly a
Part 3A Assessment due to the large volume of
waste required to fill the void. It may be very difficult
to justify the need / demand for another nonputrescible waste landfill in Sydney, if the current
proposal for the non-putrescible waste filling of
Wallgrove quarry proceeds. The NSW DECC policy
is to minimise landfill disposal capacity to increase
diversion of waste from landfill (for recycling /
processing). Due to the controversial nature of
landfill developments it would likely take a
substantial period of time to obtain all the necessary
approvals, if able i.e. 3 – 5 years. There is a
possibility of a Commission of Inquiry or Land &
Environment Court action. Cost of obtaining
development consent could be substantial (approx
$1 M).
Development Approval will be required. Need to
undertake some form of Environmental Impact
Assessment (EIA), the extent depending upon the
proposed rate of filling.
Environment Protection Licence may not be
required.
Not as controversial a development as landfilling
with waste, due to the lower potential adverse
environmental impacts, and therefore may be easier
to obtain all necessary approvals. But this cannot
be guaranteed, as there would be significant
environmental impacts for nearby residents if the
current site access route is used and there are high
rates of filling for extended periods.
An Environment Protection Licence would be
required (for landfilling operation). This would
require preparation of engineering drawings and
specifications and a Landfill Environmental
Management Plan (LEMP) that meets DECC
requirements for landfilling operations. An LEMP
details operational practices, environmental
management and monitoring requirements, and
staging of the landfilling, including site rehabilitation
and closure measures..
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2. Final land use and landform
Final land use would be constrained by the
landfilled waste, due to large depth of waste and
consequent settlement (possibly 8 – 16 m over a 20
to 30 year period), landfill gas management control
measures and potential for emissions, and leachate
management control measures and potential for
emissions. Due to large potential settlement,
realistic options for the filled area include open
space, passive recreation (walking trails), and
possibly a nature reserve. Note, there would be a
need for regular monitoring and maintenance of the
final landfill-capping layer to ensure its integrity.
A number of final landforms have been evaluated by
various parties. The most practical would appear to
be to fill to the rim of the quarry void (RL88 – 90m
AHD) and stabilise the southern and northern
buttresses. However, this option would result in the
diatreme being covered. Also this option would not
be suitable for playing fields. Other partial filling
options that preserve the views of the diatreme
have also been previously considered. Such
options create both geotechnical and stormwater
management challenges (short and long term),
particularly if the void is filled with non-putrescible
waste, which may not be able to be overcome.
Also, the volume to be filled is substantially
reduced, from 4.2 million m3 to 2 million m3.
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Final land use would also be constrained, but
perhaps not as much, due to lower settlement of the
fill (1 – 2m), if properly compacted whilst filling. No
issues with landfill gas or leachate.
Landform options as per non-putrescible waste
options, although playing fields may be possible in
the medium term once the major settlement period
has been largely completed. This period may be
able to be accelerated by faster filling of the site.
Filling the site with VENM would reduce the
technical challenges associated with preserving
views of the diatreme, but long term stormwater
management would still be a significant issue.
15
3. Fill materials
Non-putrescible solid waste. See Section 1.2 for
definition.
Virgin Excavated Natural Material (VENM). See
Section 1.2 for definition of this material.
Quantity dependent on final landform and density of
the waste once landfilled. If the site were filled to
RL 90m AHD (rim of quarry void) + buttresses (total
3
fill volume of 4.2 million m , as per PSM, 2007 – see
Figure 3), would require approximately 5.0 million
tonnes of non-putrescible waste (compacted to an
average density of 1.2 t/m3).
Quantity dependent on the final landform and
density of the VENM once placed. Approximately
7.1 million tonnes of VENM would be required
3
(@1.7 t/m ) to fill to RL 90m AHD (rim of quarry
void) and the buttresses as per PSM report (2007) –
see Figure 3.
In addition, approximately 850,000m 3 (1.3 million
tonnes) of soil would be required for covering
purposes, unless an alternative daily cover material
is used. In addition, significant quantities of clay
final capping and topsoil (80,000 – 100,000m 3)
would be needed to rehabilitate the site after filling
was completed.
There would be a need for additional cover material.
The sources of VENM in Sydney are wide and
varied. However, to fill the quarry void in the
minimum time period would require obtaining
material from a series of major infrastructure
projects e.g. CBD or West Metro, M4 East, F3
Extension. Typically, more than 1 million tonnes of
VENM could be expected from a large tunnelling
project each year, however the timing of such
projects is generally uncertain.
For projects in the north and north west of Sydney,
Hornsby Quarry would be a convenient VENM
disposal location.
Between large projects, it may be possible to attract
(through competitive pricing) 50,000 - 100,000
tonnes per year of VENM from small to medium
sized building projects.
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4. Duration of the filling
operation
The duration of the landfilling operation would be
dependent on the filling rate, which would be
dependent on the non-putrescible waste disposal
market. There is likely to be more non-putrescible
waste available (than VENM) and therefore the
quarry void would likely be filled much quicker. At
500,000 tonnes of waste per year, which is a large
scale landfilling operation, the site would be filled in
~10 years.
A high and stable filling rate could be achieved if a
major waste management company were engaged
to undertake the filling eg. WSN and / or TPI, as
they have access to large quantities of waste
through their waste transfer stations, and large
vehicles that could bulk haul the same amount of
waste in fewer loads.
The duration of filling is likely to be longer due to a
lower rate of filling, dependent on the timing and
scale of major developments / infrastructure
projects that generate VENM e.g. North West
Metro, M4 East, F3 extension.
At 500,000 tonnes per year the duration of filling
would be approximately 14 years
At 50,000 tonnes per year the duration of filling
would be approximately 140 years.
At 50,000 tonnes per year, which is a significantly
lower rate of landfilling, consistent with the average
rate at which rock was extracted from the quarry,
and transported from the site, the duration of filling
would be about 100 years.
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5. Design, engineering and
operational issues
Local access roads may require upgrading,
depending on the rate of landfilling.
Site entrance may need to be relocated, depending
on the rate of landfilling.
Internal site access roads require upgrading. Single
lane traffic flow (in some locations) may cause
operational problems.
Need to implement landfill leachate containment,
collection, treatment and disposal system, which
would be technically very challenging due to the
depth of waste to be placed at the site, and the
physical setting within the quarry void.
Same possible need to upgrade local roads, site
access road and entrance, plus internal site access
roads, 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 partially
filled to preserve views of the diatreme, but these
would still be significant.
Also need to implement landfill gas management
measures during landfilling.
There would be significant engineering challenges if
the void were partially filled to preserve the view of
the diatreme. This would include geotechnical as
well as stormwater and leachate management
issues.
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6. Environmental issues,
management and monitoring
Potential environmental issues include:
Potential environmental issues:
»
Traffic noise and nuisance;
»
Traffic noise and nuisance;
»
Landfill leachate emissions and contamination of
local surface and groundwater;
»
Dust, dependent on method of filling
»
»
Landfill gas emissions, which, if not properly
managed, could present a hazard to users of the
site and surrounding land
Other noise, dependent on the scale of the
landfilling operation (minor risk only);
»
Stormwater runoff quality (minor risk only)
»
Note, the rate of filling would determine the flow
of vehicles to / from the site, and consequent
impacts.
»
Odour nuisance;
»
Other noise, dependent on the scale of the
landfilling operation
»
Pest and vermin, including birds (minor risk);
»
Litter, around the site boundaries and possibly
along roads leading to the site (minor risk);
»
Stormwater runoff quality;
The rate of landfilling would determine the flow of
vehicles to / from the site, and its consequent
impacts. A landfilling rate of 500,000 tonnes per
year would mean approximately 80 - 100 large
trucks per day e.g. semi-trailers, or trucks with
trailers. However if only 50,000 tonnes per year was
landfilled, there may be no large trailers, but there
could be up to 70 smaller trucks (averaging 3m 3)
per day, plus local residents with cars and trailers.
A filling rate of 500,000 tonnes per year would mean
approximately 80 - 100 large trucks per day e.g.
semi-trailers, or trucks with trailers.
However if only 50,000 tonnes per year was
landfilled, there may be no large trucks, but there
could be up to 70 smaller trucks (averaging 3m 3)
per day.
Whilst traffic impacts would only occur during filling,
potential leachate and landfill gas impacts, and
impacts on stormwater quality, would exist for a
period of 30 to 50 years after filling has stopped.
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7. Post closure management
Post closure management and monitoring would be
significantly more complex due to:
Post closure management and monitoring would be
less due to:
»
Large settlement of the landfilled waste;
»
Less settlement;
»
Leachate management;
»
No landfill leachate or landfill gas; and
»
Landfill gas management;
»
Less monitoring.
»
More rigorous environmental monitoring;
Period of active management and monitoring may
be less than 10 years.
Active management and monitoring would be
required for 30 to 50 years or more.
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Figure 3: Section of Backfilled Quarry Void (from PSM, 2007)
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Review of Options for Filling Hornsby Quarry
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7.
SWOT Analysis
A preliminary SWOT (strengths, weaknesses, opportunities and threats) analysis of the two options, at
two different filling rates, is presented below in Table 5.
Table 5
Preliminary SWOT Analysis
Option
Strengths
Weaknesses
Opportunities
Threats
Filling with non
putrescible waste –
low rate (less than
50,000 tonnes per
year)
Approval process
may be easier and
resident concerns
should be minimised.
Traffic impacts may
be more acceptable
to local residents.
Filling of site
would take
approximately 100
years. Long term
environmental
issues
There are relatively few
waste disposal sites in
Sydney, therefore it
may be popular for local
residents and business
in northern Sydney. The
site will outlast Kimbriki
by many years – will
end up as the only non
putrescibles, low
volume disposal site in
northern Sydney.
Liner and leachate
collection system are still
required, even for very low
filling rates. Gate fees
would need to be
relatively high because of
high fixed costs, plus levy
– site may become
commercially unattractive
for waste companies to
use.
Filling with non
putrescible waste –
high rate (more than
500,000 tonnes per
year)
Site could potentially
be filled in 10-20
years, with high
revenue for Council.
Potential major
impact on local
residents. CPRS
liability and
environmental
monitoring and
management will
be long term
issues. However,
revenue can allow
for this.
Revenue from high rate
landfilling could be used
to purchase affected
properties. Gate fees
can be lowered as
throughput increases.
New landfills in Western
Sydney such as Wallgrove
Quarry may be approved,
which are more
convenient for waste
companies than Hornsby
Quarry.
Filling with VENM –
low rate (less than
50,000 tonnes per
year)
Site is well located
for smaller projects in
west, north and north
west. No CPRS
liability if VENM used
instead of waste.
Traffic impacts may
be more acceptable
to residents
Amount of VENM
available from
smaller projects
likely to be small,
so filling could
take > 100 years.
There are very few sites
where Section 88 levy is
not payable, so gate
fees could be kept
relatively low.
Low rate of filling makes
operational costs for site
quite high – still need to
have staff on site, plus
amenities and maintain
site roads for long period.
Filling with VENM –
high rate
(more than 500,000
tonne per year)
Large revenue over
short period (possibly
net $20-30 million
over 2 years) during
major projects, if
average of 1 million
3
m of VENM is
received each year.
Traffic impacts
would be
considerable for
local residents,
Large projects
infrequent – may
take a few large
projects over 20
years to fill the
void.
Site could be run on a
campaign basis, every
time a large project
occurs, special
arrangements made
with residents, use for
general building
projects in between.
Other sites will also be
available, but none are in
north
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9.
References and Bibliography
Department of Environment and Climate Change, 2008. Guide to Licensing Under the Protection of the
Environment 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, Wright
Corporate Strategy
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