Opus International Consultants (NSW) Pty Ltd - Transport for NSW ...

Preliminary Site Investigation at63 North Pde, Mt Druitt NSW A. D. Envirotech Australia Pty Ltd1) Specify the characteristics that define the population of interest –It was decided that:- the contamination assessment of the subsurface on the site would be achieved by aninvestigation consisting of exploratory drilling program, and subsequent soil sampling,- soil samples would be submitted for PID testing,- soil samples exhibiting the highest concentrations of volatile compounds from each boreholewould be submitted for laboratory analysis.2) Define the spatial boundary of the decision statement –It was defined that decisions would apply for the whole site.3) Define the temporal boundary of the decision statement -a) Determine the timeframe to which the decision statement applies –It was assumed that the sampling data would represent the current concentrations of volatileanalytes and current and future concentrations of non-volatile analytes on the site.b) Determine when to collect data - Since a number of analytes were subject to volatilisationand/or degradation, the analytical program required temporal constraints. The planning teamplaced deadlines on sampling and reporting:- volatile organic compounds in soils to be tested with PID as soon as samples are retrieved,- samples to be submitted to a NATA accredited laboratory within 72 hours of beingcollected,- analytical results from each sampling round to be completed within 5-10 working days ofsampling.4) Define the scale of decision making –The decision to be made for soils present on site.6.5 Development of Decision RuleDefinition of the parameters of interest and their action levels, specification of the acceptancecriteria for QA/QC validation results.1) Specify the statistical parameter that characterises the population of interest –The planning team was interested in the 95% Upper Confidence Limit (UCL) of thearithmetic average concentrations of metals and metalloids, TPH, BTEX, PAH, OCPs, OPPs,CN, Total Phenolics, Cyanide and PCBs in soil.2) Specify the action levels for the study –The action levels for the decision were the NSW Site Auditor Scheme acceptance criteria forthe contaminants of concern in soils on the site:ArsenicCadmiumChromiumCopperLeadMercuryNickelZincC 6 -C 9 hydrocarbonsC 10 -C 36 hydrocarbonsBenzeneEthyl-benzene500 mg/kg100 mg/kg500 mg/kg5000 mg/kg1500 mg/kg75 mg/kg3000 mg/kg35000 mg/kg65mg/kg1000 mg/kg1 mg/kg3.1 mg/kg4224 63 North Pde Mt Druitt PSI.v1 final Page 26