A19560_022_LTR_Rev0.pdf

Senversa Pty Ltd Ground Floor, 190 Flinders Street, Adelaide, SA 5000...

Senversa Pty Ltd Ground Floor, 190 Flinders Street, Adelaide, SA 5000 ABN 89 132 231 380 www.senversa.com.au 7 June 2024 Tundi Pawley Development Manager Villawood Properties 135 Fullarton Road Rose Park, SA, 5067 Dear Tundi, Re: Bulk asbestos sampling in soil Area 4 North – Oakden Rise Development, Grand Junction Road, Oakden, South Australia 1.0 Introduction Senversa Pty Ltd (Senversa) has been engaged by Villawood Properties Pty Ltd (Villawood) to conduct additional soil sampling for asbestos in the northern portion of Area 4 of the proposed Oakden Rise development – located on Grand Junction Road, Oakden, South Australia (the site). The site location and approximate boundaries are shown in Figure 1. This investigation forms an addendum to the Detailed Site Investigation (DSI), reporting on works carried out by Senversa in 2023 and 2024 across the entirety of the Area 4 (north) site (Senversa 2024a 1). The DSI was carried out to inform the nature and extent of site contamination present on or below the surface of the site, in the context of the proposed future development (low-density residential and public open space land use). It is noted that the site is subject to a site contamination audit – with Mr Adrian Webber of Mud Environmental Pty Ltd appointed as the site contamination auditor (the auditor). 2.0 Background As described in previous reports completed for the site and summarised in the DSI (Senversa 2024a), the use of ACM was well known and was extensively present in construction materials throughout the former Strathmont Centre facility. McMahon Services (McMahon) was previously engaged to complete the demolition works program – in which they adopted a process to remove ACM from the buildings prior to demolition. 1 Senversa (2024a) Oaken Rise Development, Area 4 (North Portion), Detailed Site Investigation, Grand Junction Road, Oaken, South Australia, 19560-008-RPT-Rev1, 5 March 2024, Rev0 DRAFT A19560_022_LTR_Rev0 7 June 2024 Page 1 of 6 Bulk asbestos sampling in soil Area 4 North – Oakden Rise Development, Grand Junction Road, Oakden, South Australia As part of works associated with the Site Remediation Plan (SRP), on 14 November 2023 Senversa (2024b 2) conducted an inspection across the former developed areas (post-demolition) to assess the risk of ACM remaining on the surface of the site. The inspection was completed in accordance with the auditor-endorsed SAQP (Senversa, 2023a 3) – and consistent with the approach recommended in the WA DoH, 2009 4. The inspection was completed by Senversa consultants who are experienced in the identification of ACM in these settings. The inspection methodology involved: A systematic walkover/inspection completed in a 10 m by 10 m grid pattern, depicted as grey grid tiles in Figure 2. Each grid was subject to two walkovers, completed perpendicular (90 degrees) to one another consistent with WA DoH (2009). Where potential ACM was observed within a specific grid tile, a more detailed walkover/inspection was conducted within and/or adjacent to the specific grid tile – to assess the extent of the observed ACM. Observed ACM was collected for laboratory analysis and was therefore removed from the site. It is considered that potential ACM in the remainder of the grid was sufficiently characterised by this more detailed walkover. The inspection identified a number of potential ACM fragments in 17 locations across the site in surficial soils, with selected samples from the different material types submitted to a NATA accredited laboratory for analysis. The results indicated that asbestos was only present in cement sheet fragments 5 submitted for analysis, at the 10 isolated locations within the footprint of the former developed areas of the site post-demolition. The locations of identified asbestos contamination are presented in Figure 2, marked as location points with a yellow halo. The SRP (Senversa 2024b) suggested that further investigation of this area was required to assess the concentration of asbestos contamination within the Area 4 (north) boundary, and if any future remediation is required. It was considered that the assessment would resolve the data gap regarding the extent of ACM in fill soils. 3.0 Objectives The objectives of the additional sampling were to: Adequately assess the extent of ACM in surface soils identified at isolated locations within the footprint of the former developed areas of the site post-demolition. Assess if the fill material containing ACM is suitable to be retained on-site, or should be disposed of to a suitably licensed landfill. 2 Senversa (2024b) Oaken Rise Development, Area 4 (North Portion), Site Remediation Plan, Grand Junction Road, Oaken, South Australia, 19560-014-RPT-Rev0, 12 March 2024, Rev0 DRAFT 3 Senversa (2023a). Sampling, Analysis and Quality Plan, Oakden Rise Development, Area 4 (northern portion), Grand Junction Road, Oakden, South Australia, 19560-010-RPT-Rev1, 29 May 2023. 4 WA DOH Guidelines for the Assessment, Remediation and Management of Asbestos Contaminated Sites 2009 5 Asbestos was indicated by the laboratory to be absent in the fibre-backing of vinyl floor-covering materials. A19560_022_LTR_Rev0 7 June 2024 Page 2 of 6 Bulk asbestos sampling in soil Area 4 North – Oakden Rise Development, Grand Junction Road, Oakden, South Australia 4.0 Methodology and Scope of Works 4.1 Relevant Standards and Guidelines To address the project objectives relating to ACM described above, Senversa undertook a further soil investigation which was considered to be consistent with the guidance provided in the following guidelines: National Environmental Protection (Assessment of Site Contamination) Measure 1999, as amended in 2013 (NEPM 2013). Guidelines for the Assessment, Remediation and Management of Asbestos Contaminated Sites in Western Australia (WA DoH, 2009). 4.2 Fieldworks Methodology The assessment included the following scope adopting the methodology described in the WA DoH 2009, and is consistent with the proposed strategy within the SRP (Senversa 2024b): The nominated ten, 10 x 10 m grid tiles where ACM was previously identified in the November 2023 walkover formed the basis of this extended investigation. Where the ACM was identified close to the boundary of the grid tile, the adjacent tile was also included in the proposed testing area (Figure 2). Based on this, 25 grid tiles formed the extent of the future laboratory testing and analysis of bonded soil asbestos concentrations using the gravimetric approach. An intrusive soil investigation was completed, comprising the excavating and sampling of 25 test pits (ATP01 – ATP25) within the nominated (and surrounding) 10 x 10 m grid tiles. Prior to excavation, the surface was re-checked for potential ACM fragments. The test pits were excavated down to natural soil, up to a depth of 1.1 m below ground level (bgl). Sampling locations are shown in Figure 3. Senversa completed in-situ bulk sampling and sieving of fill material from each test pit location:  One approximately 10 kg sample of soil was collected from the excavation pile of fill material and screened manually through a 7 mm sieve. The retained soils were weighed in the field.  Any potential bonded ACM was identified and collected into laboratory supplied sample bags.  The samples were taken to the NATA accredited analytical laboratory; ALS Environmental (ALS) and potential ACM fragments were weighed and assessed for the presence or absence of asbestos. The percentage (weight/weight) of bonded ACM in soils were calculated as a concentration adopting the gravimetric approach, and using the assumption that cemented sheeting contains 15% (by weight) of asbestos fibres in the material (WA DoH 2009). 4.3 Investigation and Screening Levels The soil investigation level adopted for asbestos in bonded ACM in a Residential A setting with garden/accessible soil, is 0.01%(w/w), in accordance with the NEPM 2013 and the WA DoH 2009. The soil open space investigation level for asbestos in bonded ACM is higher, at 0.04%(w/w). However, the open space investigation level was not adopted as it is considered that preparing the whole site for residential purposes only is more consistent with the precautionary principal. A19560_022_LTR_Rev0 7 June 2024 Page 3 of 6 Bulk asbestos sampling in soil Area 4 North – Oakden Rise Development, Grand Junction Road, Oakden, South Australia 5.0 Assessment Results 5.1 Field Observations Soil conditions were generally consistent with those encountered during the initial DSI fieldworks carried out by Senversa (2024a). A detailed description of the materials encountered is provided within the soil bore logs together with photographs in Attachment A. The following key observations were made: Fill materials were encountered in the soil bores and generally consisted of poorly graded, fine to coarse grained, low plasticity clayey sand or sandy silt. Depths of fill ranged from 0.4 m to 1.1 m bgl. Potential ACM cement fragments were observed at surface level in ATP18, ATP19, ATP23, and an ACM cement pipe fragment was observed at the surface of ATP24. Potential ACM in the form of inferred vinyl flooring fragments was observed in ATP15 and ATP16. Potential ACM was not observed below surface level or at other test pit locations. The bonded ACM is considered in good condition, with no evidence of significant weathering or friable portions of sheeting or pipe. Trace amounts of anthropogenic materials including brick fragments, cement fragments, vinyl, plastic, wire, asphalt and tiles were observed in the shallower portions of the test pits except ATP05, ATP08, ATP09, ATP12, ATP17, and ATP25. Natural soils were encountered in the test pits except ATP10 (due to refusal), and generally consisted of orange, brown to red brown silty or sandy clay of high plasticity (inferred to be the Pooraka Formation). No olfactory indicators of contamination were noted during the investigation. 5.2 Analytical Results Results based on the sample collection, sieving, and weighing conducted by Senversa, as well as laboratory analyses and guideline exceedances, are provided in Table 1 (attached). Laboratory documentation is provided in Attachment B. As discussed above, fibrous materials were observed on the surface at 6 locations out of the 25 that were investigated. Of those, the laboratory results showed that at two locations where vinyl flooring materials were collected (ATP15 and ATP16) the fragments had no asbestos, but rather organic fibres. The materials collected from the remaining four locations, in the form of cement sheeting/piping, were reported by the laboratory as positive for asbestos. The four ACM samples’ weight/weight content was calculated to be greater than the residential land use criteria of 0.01% w/w listed in WA DoH (2009), with the exceedances detailed in Table 4.1 below. Table 4-1: Estimate of Asbestos in Soil Concentration Sample ID/ Bulk weight Weight of bonded Weight of bonded Non-friable asbestos ACM Location (kg) ACM (g) asbestos (g)* content (w/w %) ATP18 10.0 53.0 7.95 0.0795 ATP19 9.60 28.0 4.20 0.0438 ATP23 11.3 66.8 10.0 0.0885 ATP24 9.70 2,190 329 3.39 *Section 4 WA DoH 2009, the content of asbestos in bonded ACM from asbestos cement sheeting was assumed to be 15%. A19560_022_LTR_Rev0 7 June 2024 Page 4 of 6 Bulk asbestos sampling in soil Area 4 North – Oakden Rise Development, Grand Junction Road, Oakden, South Australia 6.0 Remediation 6.1 Remediation Objectives The remedial objectives for the portion of the site impacted by asbestos are as follows: Mitigate or remove the risks posed by the identified asbestos contamination. Make the site suitable for the proposed residential land and open space use. Undertake the remedial works in a manner consistent with relevant regulatory provisions and guidance. Remedial works should also be undertaken in a manner that mitigates risks to worker health and safety, adjacent landholders and the environment. 6.2 Remediation Approach and Rational The proposed remediation approach is consistent with that detailed in the SRP (Senversa 2024b) and will be completed in accordance with the guidelines (WA DoH 2009, NEPM 2013). Table 6-1: Remediation Approach and Rational Remediation Step Rational Excavation (initially to 0.1 m bgl) in Initial proposed excavation of relevant grids to a depth of 0.1 m bgl is based on our the four 10 x 10 m grids where experience that ACM has been observed and collected from surficial locations only, with surface asbestos concentrations the following additional justification: exceeded the guidelines The presence of ACM was well known and was extensively present in construction materials throughout the former Strathmont Centre facility and therefore it follows that during demolition works, some ACM may have been left on the surface. ACM was not observed within the deeper portions of the test pits completed as part of the works (Section 5.1). Further, as per field observations in the DSI report (Senversa 2024a), Section 6.6.2, “No ACM was observed within or in the near vicinity of where stockpiles, test pits, soil bores or validation samples were assessed” and Section 7.0 “… confirmed ACM was collected during the systematic site walkover/inspection across the former developed areas (post-demolition).” Therefore, it is assumed to be isolated to the surface rather than present throughout the depth of historical fill materials. Construction and demolition (C&D) waste, typically associated with ACM, was also present predominantly within the upper portions of the historical fill materials observed within the test pits excavated as described above. As limited C&D waste is present within the deeper fill material, it follows that ACM may also be limited in deeper fills. Conversely, the shallower C&D waste also confirms that debris from demolition was left on or near the surface of the site. Excavation of only the four 10 x 10 m In the November 2023 walkover, confirmed asbestos materials were located in 10 grids where surface asbestos areas, most of which were within or adjacent to the former building footprints concentrations exceeded the (Figure 2). Conversely, many of the areas where fibrous materials (e.g., vinyl guidelines flooring) were located but were reported to be asbestos free, were located away from the former building footprints. In this investigation, the locations of the three fragments of asbestos sheeting were observed in areas consistent with former building footprints, evident in Figure 2. The piece of asbestos pipe was found towards the eastern boundary and not associated with former buildings. It follows that the spatial distribution of confirmed ACM has generally been limited to the area along the southern portion of Area 4 (north) where the former buildings were present, and that removing the C&D materials from those four areas is likely to complete the remediation of the residual incidence of ACM distribution from the demolition works, subject to successful validation and adherence to the Unexpected Finds Protocol in Section 9.2 of the SRP (Senversa 2024b). A19560_022_LTR_Rev0 7 June 2024 Page 5 of 6 Bulk asbestos sampling in soil Area 4 North – Oakden Rise Development, Grand Junction Road, Oakden, South Australia Remediation Step Rational Removal off-site Based on the discussion above, the preferred remediation method is removal of the surface 0.1 m of material and offsite disposal of the asbestos contaminated soils to an appropriately licenced facility. Senversa has estimated an approximate 40 m3 of soil is required to be removed from site based on an affected area of approximately 400 m2, and estimated depth of asbestos impacts to 0.1 m bgl. This should be repeated if validation is not successful. Remediation Validation Final validation of the excavation base and walls by visual assessment is required to determine that no fibrous materials or significant C&D waste (with which the fibrous materials are associated) are present. This assessment will be completed by a suitably experienced and trained environmental professional / competent person and in accordance with Section 7.2 of the SRP (Senversa 2024b). The final excavation extents should be surveyed. 7.0 Conclusions and Recommendations Senversa concludes that the presence and extent of non-friable asbestos soil contamination has been appropriately assessed in accordance with the relevant regulatory guidance and national guidelines in the context of the proposed residential and open space land uses. This investigation indicated that asbestos (in the form of cement sheet fragments, and a portion of a pipe) was present at concentrations above the adopted residential land use guidelines in surficial soils at four isolated locations within the footprint of the post-demolition areas of the site. The four areas constituting 10 x 10 m grids where the ACM was observed, are to be excavated and should be disposed of to a suitably licensed landfill. Senversa has estimated an initial 40 m3 of soil is required to be removed from site based on the 4 affected areas of approximately 100 m2 each, and estimated depth of asbestos impacts to 0.1 m bgl. Should validation be unsuccessful, based on visual assessment as described in this document, further excavation may be required. If you have any comments or questions, please do not hesitate to contact the undersigned or Simon Welsh at [email protected] or via mobile on 0456 004 055. Yours sincerely, Darcy Rawson-Currie Andrew Howes Environmental Scientist Principal Environmental Scientist Enclosures Figure 1: Site Location Figure 2: ACM Grid Areas of Assessment Figure 3: Asbestos content in Soil Table 1: Soil Analytical results Attachment A: Soil Lithology Logs and Photographs Attachment B: Laboratory Documentation Limitations Senversa has prepared this document for use only by its client for the specific purpose described in its proposal, which is subject to limitations. Matters of possible interest to third parties may not have been specifically addressed for the purposes of preparing this document and Senversa’s use of professional judgement for the purposes of the work means that matters may have existed that would have been assessed differently on behalf of third parties. A19560_022_LTR_Rev0 7 June 2024 Page 6 of 6 Bulk asbestos sampling in soil Area 4 North – Oakden Rise Development, Grand Junction Road, Oakden, South Australia Figures A19560_022_LTR_Rev0 7 June 2024  ± CIRCUIT SUNSET Adelaide Women's Prison TION ROAD GRAND JUNC Oakden Fire Station LURLINE AV SAHMRI Preclinical ENUE Imaging and Research Laboratories DALLY ROAD COURT SUDHOLZ RO FULTON STRE Former RE Strathmont U AT Centre FE BLACKS RO AD ET BISHOP PL AD PARK TERR ACE ACE EN UE HILLTOP DR IVE SWANSON AV FOSTERS RO ED WA BEN R DS UIT COUR HIDCOTE CIRC T THA AD LL A SALTRAM PA T LEWIS COUR ACORN PARA VEN STREET UE STREET PETWORTH DOVECOTE RADE Path: S:\01_Jobs\5.SA_Jobs\A19560_VILLAWOOD_OAKDEN_ENV SERVICES\APRX\A19560_022 ACM Area 4 North.aprx VI CT DE BROOKDAL OR IA DR IV E Site CAMB Location RIDG E ST E CLOSE RE URT HERITAGE CO ET W URT HANBURY CO AK MONTACUTE BUCKINGHAM Y TRINITY WA EH IV E OAKDALE DR ASHDOWN ST UR CE ST LD PLA AVENUE FFIE SHE OLD HALL CO ATTINGHAM CR DRIVE H STREET Former Oakden Older FARNBOROUG STREET REET Persons Mental WOODLAND Health Facility LY LER DRIVE D AR N URT EV TO IVE O UL PARKVIEW DR ENUE N AREMONT AV HB ESCENT CL MIT AV UE SS AVEN MILBANK EN S O Map data © OpenStreetMap DRIVE WHIST SIRR U E R T STANDEN CO URT contributors, Microsoft, Facebook, Inc. C OU E YS KEW DRIVE ANNESLEY ST REET and its affiliates, Esri Community GR Maps contributors, Map layer by Esri STREET BROOKSIDE Legend Created: M. Black Date: 7/06/2024 Figure No: 1 Site Boundary Area 4 (northern portion) Area 4 Reviewed: D. Rawson-Currie Revision: 0 Title: Site Location Area 1 Approved: S. Welsh Scale: 1:5,000 (A3) Area 2 Project: Additional Soil Sampling for Asbestos Area 3 File: A19560_022_F001_Site Location Plan_Area4 Area 3B 0 25 50 100 150 200 250 Location: Grand Junction Road, SA Metres Notes: Aerial Imagery (22/05/2022) © Nearmap Coordinate System: GDA 1994 MGA Zone 54 Client: Villawood Properties © Senversa 2024  ± Adelaide Women's Prison TION ROAD GRAND JUNC Electrical Power House Building/Structure 2 Oakden Fire Station ! ? Z ! ! ? Approximate Boundary of Former Market Garden V ! ! ? 6b Nurses Home Operations ?! ! ! ?! ! ! ? ! ! ? 6c 6d Sta D 6a ffF 6 lats ! ! ? R ! ! ? Maintenance Workshop ! ? K ? Q! ! ! ? (including spray booth and paint storage) ! ! ? 5 Linen and UST and Clothing Store ! ?3 Associated Path: S:\01_Jobs\5.SA_Jobs\A19560_VILLAWOOD_OAKDEN_ENV SERVICES\APRX\A19560_022 ACM Area 4 North.aprx Infrastructure ! ? M 4 ! ! ? !