9.1 Field Observations
9.1.1 Lithology and Soil Observations
Borehole drilling was conducted via mechanical drill rig on 26 and 27 September 2019. Photographs are presented in Appendix B and borelogs are presented in Appendix O. A summary of lithological conditions is presented in Table 9.1A and Table 9.1B.
Concrete was approximately 0.2 m in thickness, encountered at locations BH03 and soil vapour probe locations SV01, SV02 and SV05 to SV18. Asphaltic hardstand was present from the ground surface to 0.05 m bgl at locations BH02, MW03, MW04 and MW06. Hardstand pavements were typically underlain by a thin layer (~0.1 m) of sub-grade gravels. Fill material was encountered at every soil sample location. The encountered materials appeared to comprise reworked natural soils and bedrock similar to the natural soils observed at the site. Fill was generally shallow (<1 m), with deeper fill observed at BH01 (to 2.4 m bgl), BH05 (to 1.3 m bgl) and MW01 (to 1.8 m bgl).
Anthropogenic inclusions (<10 %) were observed in shallow fill at BH01 (asphalt, brick, concrete), BH05 (concrete), BH06 (asphalt, gravel) and (>10 % and < 20 %) in MW01 (gravel, plastic), MW04 (asphalt) and MW06 (gravel).
Natural soils at the site comprised generally silty and sandy clays underlain by dark grey shale to the depth of the investigation. No indicators for the presence of ASS, salt scarring or leaching were observed during site sampling.
Table 9.1A Bottom Depth of Encountered Lithology in Monitoring Wells (m bgl)
Lithology Borehole
MW01 MW02 MW03 MW04 MW05 MW06
Hardstand NP NP 0.051 0.051 NP 0.051
Fill 1.8 0.8 0.4 0.3 0.3 0.4
Natural
(Soil) 4.0 1.5 0.7 1.6 1.5 0.4
Natural
(Bedrock) NE 4.0 3.0 4.6 9.0 0.8
Hole Depth 4.0 4.0 3.0 4.6 9.0 8.8
Notes: NP = Not present, NE = Not encountered, 1 = asphaltic hardstand, 2 = concrete hardstand Table 9.2A Bottom Depth of Encountered Lithology in Boreholes (m bgl)
Lithology Borehole
BH01 BH02 BH03 BH04 BH05 BH06 BH07
Hardstand1 NP 0.051 0.2 NP NP NP NP
Fill 2.4 0.15 0.3 0.2 1.3 0.4 0.2
Natural
(Soil) 2.9 1.0 1.0 1.0 2.0 1.0 NE
Natural
(Bedrock) 3.0 NE NE NE NE NE NE
Hole Depth 3.0 1.0 1.0 1.0 2.0 1.0 0.2
Notes: NP = Not present, NE = Not encountered, 1 = asphaltic hardstand, 2 = concrete hardstand 9.1.2 Groundwater Field Observations
A groundwater monitoring event (GME) was conducted on 30 September 2019 (3 days following well installation). All six installed wells were dipped with an interface probe to evaluate whether
standing water was present. No groundwater was encountered within any of the six well installed, to a maximum depth of 9.0 m bgl.
©JBS&G Australia Pty Ltd | 57518/138923 Rev 1 33 9.2 Laboratory Analysis Results
Detailed laboratory reports and chain of custody documentation are provided in Appendix L.
Summarised soil analytical data from the current assessment are presented in:
• Table A Soil Analytical Results (Land Use Suitability); and
• Table B Soil Vapour Analytical Results (Land Use Suitability).
9.2.1 Soil Contaminant Analytical Results
A summary of soil analytical results is presented in Table 9.2 following.
Table 9.2 Summary of Soil Analytical Results
Analytical Group Number of Primary
Samples Analysed Number of Screening
Criteria Exceedances Statistical Significance Further Interpretation
Heavy metals 16 0 NA None
TRHs 10 1 NSS Yes
BTEXN 10 0 NA None
PAHs 16 0 NA None
OCPs 10 0 NA None
PCBs 10 0 NA None
VOCs 2 0 NA None
Asbestos (500 mL) 15 0 NA None
ASLP (Nickel) 3 0 NA None
Notes: NSS = Not statistically significant exceedance, NA = not assessed, 1 – discussed further in the following subsections.
Per Table 6.1.5 no further statistical assessment was undertaken where no exceedances of the site screening criteria were identified. Exceedances of screening criteria are further discussed following.
A total of 10 soil samples were analysed for TRH concentrations. Elevated TRH- fraction range >C16- C34 was detected in near surface fill in one sample (MW01 0-0.1 – 350 mg/kg) and its intra-lab duplicate (QC01 – 320 mg/kg), and the adopted ecological criterion (ESL- 300 mg/kg) was exceeded.
The concentrations did not exceed any relevant health investigation criteria. Statistical assessment, presented in Appendix P, of the soil data set for this TRH fraction range indicates the following information:
• The maximum concentration is less than 250 % of the screening criterion;
• The standard deviation is less than half of the screening criterion; and
• The 95 % UCL for the dataset is less than the screening criterion.
Per the decision rule presented in Table 6.1.5 there are no statistically significant exceedances of the site screening criterion.
9.2.2 Asbestos Identification
A single sample of bonded cementitious material was assessed for the presence of asbestos (FRAG01). The sample was determined to be absent detectable asbestos.
©JBS&G Australia Pty Ltd | 57518/138923 Rev 1 34 9.2.3 Soil Vapour Field Screening
Temporary sub-slab vapour probes were installed to a maximum depth of 0.3 m bgl at seventeen locations (Figure 4B). A summary of screening data is presented in Table 9.3 following. Soil vapour screening field sheets are presented in Appendix O.
Table 9.3 Summary of Soil Vapour Screening
Probe Location PID (ppm) CH4 (%) CO2 (%) O2 (%) Analysis
SV01 0.1 0.0 1.1 12.2 No
SV02 1.6 0.0 0.6 16.1 No
SV05 2.8 0.0 1.7 1.7 Yes – PID and CO2
SV061 0.4 0.0 0.0 20.0 No
SV07 1.8 0.0 6.3 6.3 No
SV08 2.5 0.0 1.9 12.0 Yes – PID and CO2
SV09 4.9 0.0 2.3 19.4 Yes - PID and CO2
SV10 2.1 0.0 7.9 6.7 No
SV11 3.7 0.0 3.2 17.3 Yes
SV12 2.2 0.0 0.8 17.1 Yes
SV13 3.0 0.0 1.4 16.6 Yes
SV14 10.9 0.0 0.0 14.1 Yes
SV15 4.2 0.0 7.8 8.5 Yes
SV16 3.3 0.0 6.1 6.0
SV17 2.5 0.0 0.0 17.1
SV18 3.3 0.0 0.0 18.0
SV19 2.9 0.0 4.6 17.8
Notes: 1) unable to purge due to impermeable substrate.
The locations selected for analysis generally exhibited higher PID readings (indicating potential VOC presence), elevated carbon dioxide and/or depleted oxygen (indicating microbial processes which may relate to interaction with contaminants).
9.2.4 Soil Vapour Analytical Results
Soil vapour samples from eight selected soil vapour probes were analysed for concentrations of VOCs. No VOCs were detected in soil vapour above the laboratory limit of detection in any of the analysed samples. Further, no VOCs were identified at concentrations exceeding the adopted site assessment criteria.
©JBS&G Australia Pty Ltd | 57518/138923 Rev 1 35