Soil Capping Procedure
Contaminated Soil
Canberra Brickworks Remediation Project
Block 1 Section 102 Yarralumla
Canberra Central ACT
May 2015
Client: Capcorp Constructions Pty Ltd
Ref: 9623_EAR_Soil Capping Procedure_Rev 1_20150522.docx
Robson Environmental Pty Ltd
p: 02 6239 5656 ~ f: 06239 5669
e: admin@robsonenviro.com.au
PO Box 112 Fyshwick ACT 2609
www.robsonenviro.com.au
ABN: 55 008 660 900
Soil Capping Procedure
Contaminated Soil
1
INTRODUCTION AND BACKGROUND
1.1
Introduction
Capcorp Constructions Pty Ltd (Capcorp) have engaged Robson Environmental Pty Ltd
(Robson) to develop a procedure for the soil capping of approximately 2,700 square
metre (m2) area of contaminated soil identified within the foot print of the Asbestos
Dump (‘AD’).
Robson understands that Capcorp is intending to undertake these works on behalf of
ACT Property Group (ACTPG) to stabilise the ‘AD’ prior to the implementation of future
redevelopment plans which may include high density residential land use for the site.
The objective of these works is to ensure the site is safe for both future maintenance
workers and adjacent residents including the public and businesses.
The principal contaminant of concern is asbestos, however other contaminants identified
at low level concentrations include total recoverable hydrocarbons (TRH), polycyclic
aromatic hydrocarbons (PAH) and sewage indicators including faecal coliform, escheria
coli and total coilform thought to be related to the redundant septic tank within the ‘AD’.
The majority of the fill material is located in the centre of the western boundary of the
Canberra Brickworks site, Block 1 Section 102 Yarralumla ACT 2600 (Canberra Central)
Denman Street Yarralumla ACT 2600. However, the western side of the dump
encroaches on the adjoining block (s), Public Land, Block 20 Section 102 and possibly
Block 1 Section 127 (herein referred to as ‘the site’).
The location of the site is shown in Figure 1, a detailed site plan is provided in Figure 2
and the soil capping plan is provided in Figure 3.
All capping works must be undertaken in general accordance with the relevant sections
of current Site Remediation Action Plan titled:
Robson Environmental Pty Ltd (July 2014) - ‘Remediation Action Plan, Stage 1 and 2
(Includes Hazardous Materials) Canberra Brickworks Remediation Project Block 1
Section 102,
Yarralumla
Canberra
Central
ACT’
(Robson
reference
9623_EAR_RAP_Ver 4_20140730).
1.2
Background
The Canberra Brickworks operated as a Brickworks between 1913 and 1976. Based on
this known manufacturing process the site may have been impacted by a range of
industrial contaminants primarily, hydrocarbons, polycyclic aromatic hydrocarbons and
heavy metals. Other activities that may have caused on site contamination include the
use of explosives for generating raw material for the bricks, pesticides and herbicides
used to maintain the grounds and the use of hazardous materials in the construction of
the buildings, for example asbestos.
Since the brickworks ceased operation in the 1976 the site has been used by various
lessees for commercial purposes. The current lessee Thor’s Hammer runs a large scale
recycled timber business. In the 1970s perhaps due to on-site renovation and poor
management practices the western boundary of the site was apparently used as a dump
Client: Capcorp
Document1
Page 1 of 9
Soil Capping Procedure
Contaminated Soil
site which is the focus of this capping procedure. Based on aerial photographs the
dump becomes apparent in the 1980s. It is understood that hazardous materials have
been dumped in this location, predominantly asbestos. Also, it is thought that the origin
of a proportion of the asbestos waste may have been from external sources.
In August 2006 an Environmental Audit was undertaken by Robson Laboratories Pty Ltd
of the Canberra Brickworks Site and reconfirmed the location of the ‘AD’. Shallow drilling
was undertaken on the eastern boundary of the site for environmental sampling
purposes and no other industrial contaminants were detected in the soil at
concentrations above the sensitive land use criteria (Residential ‘HIL A’ Land Use). The
sensitive land use criteria were applied in this Audit to allow flexibility for future land use.
In early 2007 a RAP was prepared by Robson Laboratories Pty Ltd. The project was
halted because the ACT Planning and Land Authority (ACTPLA) determined that
Development Approval would be required for a remedial project of this size and the
perceived likely increase in cost associated with the volume of asbestos materials
observed in the dump following the removal of vegetation cover.
A consequence of the partial implementation of the RAP in 2007 was soil samples were
able to be taken from within the dump. The analytical results further demonstrated that
the likely dominant contaminant of concern was asbestos.
In 2014 a RAP was prepared by Robson Environmental Pty Ltd that was designed to
assess the site in two (2) stages. Stage 1 included site establishment, removal of
surface vegetation and surface ACM and undertake an Environmental Site Assessment
(ESA) of the ‘AD’ while Stage 2 would complete the remediation of the ‘AD’.
Stage 1 was completed in December 2014 and the ESA revealed that asbestos is the
contaminant of concern. The ACM is confined to the surface layer of the fill within a
1,260 m2 area of the ‘AD’ while the fill covers a much larger area (3,722 m2) and is likely
to extend beyond the visible boundary of the ‘AD’ extending toward north and east of the
site toward a Lane Poole Place and the Brickwork buildings. Therefore, based on the
survey data collected during the assessment the estimated volumes specific to the ‘AD’
of asbestos waste is 2,610.1 cubic metres (m3) while the estimated total volume of fill
soil (soil, brick, tile, glass, metal ash and slag) including the asbestos is 8,732 m3.
These figures equate to a 4,854.8 tonnes (t) and 16,242 t respectively when using a clay
density of 1.86 t/m3 as referenced from the Australasian Institute of Mining and
Metallurgy (1995) ‘Field Geologist Manual’. However, it must be noted that the
derivation of these figures is based on field observations and interpolation between data
points so a degree of uncertainty must be considered. If one extends the ACM fill
boundary half way between the outlying unimpacted test pits the approximate area is
2,700 m2 and assuming an average depth of 1.5 metres below ground level (mbgl) the
volume of ACM fill could be as high as 4,050 m3 which equates to approximately 7,533 t.
Photographs taken during the Stage 1 assessment works are presented in Appendix 1.
In addition to the above, a NSW Environment Protection Authority (EPA) accredited
Contaminated Sites Auditor has been engaged to review and provide comment on the
work conducted by the environmental consultant in accordance with the NSW
Department of Environment and Heritage (DEC, 2006) ‘Guidelines for the NSW Site
Auditor Scheme (2nd Edition)’ as a part of a non-statutory audit. The site audit boundary
has yet to be determined as it is likely to be inclusive of part of the Yarralumla
Client: Capcorp
Document1
Page 2 of 9
Soil Capping Procedure
Contaminated Soil
Brickworks site (Block 1 Section 102 Yarralumla ACT 2600). Further the dump
encroaches on the adjoining block(s), Public Land, Block 20 Section 102 and possibly
Block 1 Section 127.
Client: Capcorp
Document1
Page 3 of 9
Soil Capping Procedure
Contaminated Soil
2
SOIL CAPPING PROCEDURE
The soil capping procedure is based on the findings of the following report:
Robson Environmental Pty Ltd (February 2015) ‘Stage 1 Environmental Site
Assessment - Canberra Brickworks Remediation Project Block 1 Section 102,
Yarralumla Canberra Central ACT’ (Robson Reference: 9623_EAR_Stage 1 ESA
Report_20150205.docx).
The remedial works completed to date are summarised below:

Site establishment included the set up of perimeter fencing, signage, amenities,
erosion and sediment controls, internal work site zones and haulage route;

The blackberry vine and other ground cover vegetation was removed stockpiled,
wood chipped and reused as ground cover on the ‘AD’ for sealing purposes;

Visible asbestos sheet waste and building waste was largely removed from the
surface of the ‘AD’;

The environmental site assessment (ESA) was completed and the ‘AD’ has been
successfully characterised to enable the determination of the appropriate remedial
method.
2.1
Management Controls
The following controls and monitoring will be in place during the surface asbestos
removal (as required), surface regrading, the placement of the geotextile layer and
subsequent soil capping layer, grass seeding, fencing and site compound and access
road demobilisation until the area has been cleared by an ACT licensed Asbestos
Assessor.
1.
In general the impacted soil will be regraded with suitable earth moving
equipment to ensure that future site maintenance for example, mowing is
possible.
Note: All works must be undertaken in accordance with the ACT EPA (2011)
‘Environment Protection Guidelines for Construction and Land Development in
the ACT’;
2.
Prior to the commencement of the regrading and soil capping works all surface
asbestos containing material that can be removed by hand must be removed by
an ACT licensed asbestos removalist (AAC);
3.
To ensure the installation of the capping layer can be validated at completion, the
existing surface area will be surveyed by a registered surveyor prior to the
capping of the area and on completion of the capping process.
4.
The regrading works within the area of impact must be kept to a minimum to
avoid the unnecessary disturbance of ACM;
5.
To avoid spreading the ACM outside the known area of impact during the
regrading works the area to be capped must be clearly marked and have a
defined entrance and exit zone.
Client: Capcorp
Document1
Page 4 of 9
Soil Capping Procedure
Contaminated Soil
6.
The regrading works must take into consideration the location of the current main
drainage line on site to ensure the possibility of off site contamination is not
exacerbated. To assist with this a civil engineer (Calibre Consulting Pty Ltd) will
be engaged to advise on the management of the drainage line and the general
finished surface of the capping layer;
7.
The soil will be kept moist by the licensed asbestos removalist (AAC) during the
regrading works to prevent dust emissions;
8.
Due to the known presence of asbestos materials in soil, airborne fibre monitoring
will be in place at all times during the movement of the impacted soil;
9.
Due to the large area that will require regrading and soil capping it will be
necessary to ensure all required erosion and sediment controls are in place prior
to commencement of works.
It is anticipated that the proposed capping works for the ‘AD’ is scheduled to commence
on Wednesday 27 May 2015.
The schedule of works is presented below in Table A while the Project Team
Communication Plan is presented in Appendix 2.
Table A. Schedule of Works
Task
Status / Timing
Receipt of Development Approval
Completed in 2014
RAP endorsement by the Auditor
26 May 2015
Site reestablishment
2 days
Site Capping Works
Control Conditions
under
Asbestos
Remove surface ACM, regrade site, install 25 days
geotextile layer, import clean fill and
commence capping works.
Inspect compound and access road for
ACM, remove ACM as required, issue
10 days
Asbestos Clearance Certificate and
remove access road.,
Remove compound
2 days
Reinstate surfaces to existing conditions
2 days
Client: Capcorp
Document1
Page 5 of 9
Soil Capping Procedure
Contaminated Soil
2.2
Capping Layer
Based on the Robson (2015) Stage 1 ESA the asbestos materials identified within the fill
layer are present at the surface in a few locations (TP3, TP8 and TP13) while it was
found at a depth of below 0.5 metres in other locations (TP5 and TP6).
In accordance with WA DOH (2009) ‘Guidelines for the Assessment, Remediation and
Management of Asbestos-Contaminated Sites in Western Australia’ (WA Guidelines)
and if the site were to be classified as commercial which has been determined to be
appropriate considering the proposed long term management required for the site.
Based on this classification all ACM must have a minimum of half a metre (0.5 m) of
clean fill above the ACM impacted soil.
Therefore, with consideration given to the likelihood that the ACM is at the near surface,
a marker layer (geo-textile material) should be placed between the surface of the
identified ACM impacted area (approximately 1,260 m2) and the soil capping layer of
clean fill of 0.5 m deep would be considered adequate.
The purpose of the geotextile layer will not only be to provide a marker layer to alert
future users to be aware that ACM is likely to be below the layer but will also perform as
a barrier to prevent asbestos sheet materials from coming to the surface of the soil cap
over time.
To account for the uncertainty of ACM in the fill extending beyond the identified
boundary, the extent of the soil capping (soil only) should be placed half way between
the known boundary and the test pits where ACM was not identified. Therefore the total
area to be capped is approximately 2,700 m2. However, the depth of the cap may be
reduced in this buffer zone to allow for the adequate grading of the cap to meet the
future site management requirements that is mowing etc.
The capping layer must be clean certified fill with a sufficient clay content so that it is not
easily eroded but will also need to be suitable for seeding for revegetation purposes. It is
understood 50 millimetres (mm) of topsoil will be required as part of the capping layer to
effectively re-establish the vegetation cover with dry land grasses.
2.3
Fill Requirements
Fill to be used for capping purposes could be sourced from three (3) locations which
have been identified as:
A)
Excess on site fill material located at a minimum of 10 metres outside the
boundary of the marked ACM impacted fill area (approximately 2,700 m2);
B)
The road base to be removed from the site compound and access road as part of
the site amenity demobilisation program (placed at depth only);
C)
Imported clean fill.
On Site Fill
Prior to using the on site fill from outside the suspected ACM impacted area, the source
area must be identified and cleared by the Asbestos Assessor. The excavation of the
material must be visually screened for asbestos materials and other contaminants of
concern by an Environmental Scientist / ACT Asbestos Assessor and stockpiled in a
suitable location. A Clearance Certificate must be issued for the material by an Asbestos
Assessor before it is used in the capping layer of the ACM impacted fill area.
Client: Capcorp
Document1
Page 6 of 9
Soil Capping Procedure
Contaminated Soil
Compound and Access Road Base Materials
Prior to using the road base material, the compound and access road surface must be
inspected for asbestos materials by an ACT Asbestos Assessor and a Clearance
Certificate issued. It is expected this material would only be suitable for use in the lower
layers of the capping layer as it is unlikely to meet the revegetation requirement.
Imported Fill
Imported fill is likely to be required on site to meet the capping layer requirements. This
fill must be assessed before it is imported to ensure it is suitable for the proposed site
use which may require chemical testing. The assessment should also be reviewed by
the Site EPA Accredited Auditor prior to the importation of fill. Approval from the ACT ES
to import fill onto a site is required.
As general guidance, the soil is to be either virgin excavated natural material (VENM) or
is to be sampled to confirm that the quality of the soil meets the site assessment criteria.
The aesthetic suitability of the soil will also need to be considered. Material that would
be considered to be aesthetically unsuitable may exhibit one (1) or more of the following
characteristics:

Odorous soil;

Soil with visible chemical or hydrocarbon staining;

Soil with greater than 5 % waste material (e.g. bricks, plastic, metals etc).
2.4
Soil Capping Work Method
The following methodology should be read in conjunction with the following document:

AAC’s Asbestos Removal Control Plan (ARCP).
As part of the validation of the capping works ensure the site has been surveyed prior to
the commencement of works and again on completion of works.
Note: The Dial Before You Dig facility must be implemented prior to the soil
capping works.
I.
AAC (Civil contractor) in consultation with Capcorp Constructions (Site
Superintendent) will organise the sequential reinstatement of the site amenities,
and the secure perimeter temporary fencing to the Site to ensure no
unauthorised entry prior to the commencement of work.
II.
The required PPE will be hard hats, high-viz long sleeve and pant clothing,
glasses, protective boots with a steel toe and gloves.
III.
The ‘AD’ will be set up and managed as an Asbestos removal area by an ACT
licensed asbestos removalist (AAC) in accordance with Safe Work Australia
(2011) ‘How to Safely Remove Asbestos’ - Code of Practice.
IV.
Therefore, further PPE will include P1 disposable masks (respirator) and
coveralls worn by plant operators (outside machinery) and ground personnel
who must work within the exclusion zone associated with the soil capping works.
The coveralls and respirators will be a single use only item and will be discarded
at the end of each working shift as contaminated waste.
V.
The plant and truck operators will remain in their vehicle at all times with the
windows closed. As the plant and truck operators will not be entering or exiting
Client: Capcorp
Document1
Page 7 of 9
Soil Capping Procedure
Contaminated Soil
their vehicle, they will not be required to wear coveralls or dust masks. Airborne
fibre monitoring to the National Association of Testing Authority (NATA)
requirements will be carried out in representative excavator cabins and truck(s)
and PPE requirements will be re-assessed by the hygienist on the basis of the
fibre concentration results.
VI.
The regrading and management of all soils containing ACM will be overseen by
an ACT licensed Class A or B asbestos removalist. The licensed asbestos
removal Supervisor (AAC) will be on site at all times.
VII.
The regrading works within the ACM impacted area should be kept to a
minimum to prevent the unnecessary disturbance of ACM.
VIII.
To avoid spreading the ACM outside the known area of impact during the
regrading works the area to be capped must be clearly marked and have a
defined entrance and exit zone.
IX.
Grading works within the asbestos impacted area must be worked from the
boundary to the centre of the impacted area which will further reduce the risk of
the spread of asbestos impacted fill.
X.
The installation of the geotextile layer and the soil capping works will continue to
completion and Robson will progressively inspect the capping works area to
ensure the known contaminated soil is appropriately capped.
XI.
Any large items (e.g. tree trunks, large rocks, large pieces of concrete etc) that
require removal to facilitate the capping of the site will be cleaned of any
contaminants as per instructions by the ACT Asbestos Assessor. These
materials are likely to be stockpiled on site and recycled off site under a
separate program of works.
XII.
It is not expected that asbestos impacted soil is to be removed from site but in
the event there is a requirement the activity must be undertaken in accordance
with the ACT EPA Information Sheet 4 and Sheet 5 (refer Appendix 3);
XIII.
Control airborne fibre monitoring to the National Association of Testing Authority
(NATA) requirements will also be undertaken proximal to the regrading, capping
and stockpiling works (if required) and on the perimeter fence. A 10 metre
exclusion zone will be in place around the soil capping works.
XIV.
Water spray/misting will be used as required to minimise dust generation as
required.
XV.
The asbestos removalist (AAC) will utilise a bucket, sponge, spray bottles, rags
and water hoses to address personnel and equipment decontamination
requirements during the soil regrading works (including the decontamination of
plant at the completion of works) within a designated decontamination zone.
XVI.
The work area will be appropriately signed and barricaded to prevent access
and potential exposure.
XVII.
A Clearance Certificate would be generated following satisfactory monitoring
results and visual inspection of the site including the site compound and site
access road and will be forwarded to all concerned parties and to the ACT EPA
for its records at the satisfactory completion of site works.
Client: Capcorp
Document1
Page 8 of 9
Soil Capping Procedure
Contaminated Soil
On successful completion of the capping of the ‘AD’, the demobilisation and the securing
of the site, an Environmental Management Plan (EMP) is recommended for the site to
allow for the on-going safe maintenance of the site.
The EMP should be prepared in general accordance with the requirements of the ACT
EPA (2009) ‘Environmental Guidelines for Preparation of an Environment Management
Plan’.
THIS DOCUMENT MUST NOT BE REPRODUCED EXCEPT IN FULL AND MUST BE
READ IN CONJUNCTION WITH THE REPORT TERMS AND CONDITIONS
INCLUDED WITH THIS DOCUMENT.
For an on behalf of, Robson Environmental Pty Ltd.
Ben Kendon
Senior Consultant – HAZMAT
Asbestos Assessor (ACTPLA)
License No: 2006638
ATTACHMENTS
Report Terms and Conditions
Figures
Figure 1:
Site Location Plan
Figure 2:
General Site Plan
Figure 3:
Soil Capping Plan
Appendices
Appendix 1: Photographs
Appendix 2: Project Team Communication Plan
Appendix 3: ACT EPA Information Sheets 4, 5 and 6
Client: Capcorp
Document1
Page 9 of 9
Soil Capping Procedure
Contaminated Soil
Client: Capcorp
Document1