Document ID: chunk:federal_register_of_legislation:F2013C00288:reg:4:p10
Version: federal_register_of_legislation:F2013C00288
Segment Type: reg
Provision Reference: reg 4 (pt 10/11)
Character Range: 143013–145974

be possible in the initial AS4964 procedure to obtain an estimate of the weight of asbestos (such as small ACM fragments and fibre bundles) which does not pass through the 2 mm sieve. Depending on site circumstances, this information may be useful as part of a weight-of-evidence approach to assessment of asbestos soil concentrations relative to the appropriate screening levels.

As a general guide, where sites are contaminated with bonded ACM only (i.e. no insulation materials or other non-bonded asbestos products) assessment for the presence/absence of free fibres by laboratory analysis is only warranted where greater than 10% of the total bonded ACM is significantly damaged i.e. present as small pieces less than 7 mm x 7 mm or can be crushed/crumbled with hand pressure (significant FA and/or AF is present).

4.11          Assessment against asbestos screening levels and procedure for exceedences
A tiered approach to risk assessment of asbestos contamination is recommended, including development of an appropriate CSM (refer Section 2.4 in Schedule B4).
A weight-of-evidence approach is recommended with consideration given to factors such as the distribution of different fill types, the heterogeneity of the contamination and the uncertainty associated with the sampling methodology. The evaluation and discussion of results should consider any trends across the investigated area including variability and change in asbestos type and condition. For buried asbestos contamination, the impacted units should be identified and discussed separately.

For Tier 1 analysis, the contamination concentrations are compared with the screening levels presented in Section 4.8. If the Tier 1 screening levels are not exceeded, and an appropriate level of investigation has been carried out, then no contamination management actions are required except for ensuring the surface soil is free of visual asbestos. This may be achieved by multidirectional raking or tilling and hand-picking of exposed fragments of bonded ACM.  Final visual inspection of the assessment and remediated areas should not detect any visible asbestos.

When cohesive soils (such as firm clay) or a large surface area is involved it may be more practical to skim the top 5–10 cm of soil for disposal in accordance with jurisdictional requirements. The exposed surface of the site can then be further visually assessed by an appropriately qualified and experienced professional/competent person on a systematic basis. If bonded ACM fragments are found to be present after skimming, some localised hand-picking or additional earthworks may be required until no visible bonded ACM is present.

If exceedences of the Tier 1 screening levels are present, either a Tier 2 analysis should be carried out or a conservative management response implemented. The Tier 2 assessment will comprise a qualitative assessment of risk in many cases and should take into account the nature and extent