Acid Sulphate Soils Guideline

Draft Identification and investigation of acid sulfate soils and groundwater

Introduction
Investigations
Using Lab Results
Groundwater
Further Information
References
App. 1: Risk Map
App. 2: Indicators
App. 3: Soil pH

App. 4: Action Criteria

Draft Identification and investigation of acid sulfate soils and groundwater

4.0 Using laboratory results from Step 2

4.1 For all disturbances

If no single laboratory result exceeds the texture-based ASS Action Criteria in Appendix 4 (i.e. absence of ASS has been confirmed), then the applicant can submit the application with the supporting information.

If any one of the laboratory results exceed the texture-based ASS Action Criteria, indicating that existing and potential acidity must be managed, then the appropriate level of treatment [low (L), medium (M), high (H), very high (VH) or extra high (XH)] can be determined using the highest single laboratory result and the total volume of disturbance together with Table 5. If the level of treatment is very high (VH) or extra high (XH) then additional laboratory analysis will normally be required to give a better quantification of the location, the maximum amount of existing acidity plus potential acidity and volume of ASS to be disturbed.

TABLE 5 Existing treatment levels and aglime required to treat the total weight of disturbed ASS based on soil analysis (adapted from Queensland SPP Guidelines 2/02).

4.2 For non-linear disturbances up to 1000 m³

If the combination of the disturbance volume and the highest laboratory result applied to Table 5 indicate that a very high (VH) or extremely high (XH) level of treatment is required, additional samples will need to be analysed in accordance with the full requirements of the Guidelines for Sampling and Analysis of Lowland Acid Sulfate Soils (ASS) in Queensland 1998. (i.e. one sample per 0.5 metre interval analysed). Treatment and management are discussed in the Treatment and Management of Disturbed Acid Sulfate Soils DEWCP 2003 and the Queensland Soil Management Guidelines - Acid Sulfate Soil Technical Manual 2002 available on www.environ.wa.gov.au. The results from these additional analyses can then be used to calculate average existing, plus potential acidity content, for each depth interval and develop a more refined cost-effective treatment plan.

4.3 For linear disturbance

If the volume of soil to be disturbed between sampling points multiplied by the average S% of this volume is less than the VH category as shown in Table 5, then sampling at 100 m intervals is acceptable. Where this is not the case, then a greater sampling intensity would be expected (ie 50m intervals).

4.4 Conclusion

Preliminary sampling intensities in Table 1 and 2 do not provide sufficient detail on the existing and potential acidity required for using different liming rates with different soil layers. Further analysis of the stored samples and/or more detailed justification will be required if the proponent wants to neutralise different layers of the soil with different amounts of neutralising agent, or use the average of all laboratory analyses as the basis for lime application rates. In such cases, more detailed calculations involving weight (using volume and bulk density) will be necessary by referring to the Treatment and Management of Disturbed Acid Sulfate Soils DEWCP 2003 and the Queensland Soil Management Guidelines - Acid Sulfate Soil Technical Manual 2002.