Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:5:p6
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 5 (pt 6/10)
Character Range: 160696–163558

HSLs for vapour intrusion? NO
  4.       Are direct contact HSLs relevant? YES (proposed low density residential land use) however there is no soil contamination at surface (95% UCL for all the identified contaminants of concern was less than the appropriate investigation and screening levels).
  5.       Are ecological considerations relevant? YES (proposed low density residential development with exposed areas of soil). Site summary information indicates that the soil GM for 0–2 m was less than the applicable ESLs. A comparison with soil data for deeper horizons is not relevant as the ESLs are applicable to the top 2 m of soil.
  6.       Are management limits relevant? YES (decommissioned industrial site proposed for sensitive land use). Compare soil results with the relevant management limits for residential use. NO exceedences indicated.
'Clean fill' and soil values mg/kg, refer Table 1B(7) for management limits (fine soil)
                  F1   F2     F3     F4
Fill GM 0 – 2 m   <10  < 10   <50    <100
Soil GM 2 – 4 m   130  160    1,100  260
Management limit  800  1,000  3,500  10,000

  7.       Are aesthetics relevant? YES (sensitive land use proposed) As 2 m of clean fill is present across the site issues of soil staining or odours are unlikely. The assessor will also need to consider the likelihood of uncontrolled excavations exposing contaminated material at depth.

Outcome      * No exceedences are indicated from the comparisons with the relevant HSLs, ESLs and management limits for the proposed residential land use.
             * Evaluation of the data for naphthalene, BaP, total PAHs and lead would also be required.

Evaluation and conclusion
A multiple-lines-of-evidence approach is recommended for the evaluation of vapour intrusion risks. Although no unacceptable vapour intrusion risks were identified in the assessment above, the assessor would need to take into account the level of uncertainty associated with the data and whether a sufficient margin of safety was present, particularly in relation to the adjusted groundwater HSLs.
Further consideration should be given to the confidence in the site CSM particularly with regards to seasonal trends in groundwater quality and possible variation in depth to the water table. If the watertable is likely to rise by more than 2 m, then the maximum concentrations of benzene recorded in MW 1 (7 mg/L) and MW3 (8 mg/L) would be close to/at the level of the adjusted HSL of 8 mg/L for 2 m  <4 m depth (Table 1A(4) with x10 adjustment).
Given the sensitivity of the proposed land use (low density residential), consideration should be given to collecting further data such as conducting a soil vapour survey of the source area.
The level of groundwater contamination present is of concern. The groundwater quality is unacceptable for human consumption and should be