Geotech Report - Acid Sulfate Soil Assessment

 

SECTION 5 - COMMENTS

5.1 Assessment Criteria for Acid Sulfate Soils

ASS in Queensland are assessed in accordance with the Queensland Acid Sulfate Soils Investigation Team
(QASSIT) Guidelines for Sampling and Analysis of Lowland Acid Sulfate Soils (ASS) in Queensland 1998
(QASSIT Guidelines) and the State Planning Policy 2/02 Guideline Planning and Managing Development
Involving Acid Sulfate Soils. The State Planning Policy 2/02 Guideline provides Action Criteria for assessing the
results of laboratory testing quantifying the acid producing effects based on the sum of existing plus potential
acidity. These action criteria are presented in Table 4.

Table 4: Action Criteria Based on ASS Analysis for Three Broad Texture Categories

Action Criteria Action Criteria
Type of Material (1 - 1000 tonnes disturbed) (> 1000 tonnes disturbed)
Existing + Fptential Acidity Existing + Potential Acidity
Equivalent Equivalent Acidity | Equivalent | Equivalent Acidity
ik Teanbbiie een Sulfur (%S) | (molHtitonne) | Sulfur (%S) | (mol H*/tonne)
5 "! | (oven-dry basis) | (oven-dry basis) | (oven-dry basis) | (oven-dry basis)
Coarse Texture
ede tober aendl <5 0.03 18 0.03 18
Medium Texture
Sandy loams to light clays on 0.06 id 9.03 8
Fine Texture

Medium to heavy clays, silty clays 240 ort 62 0.03 18
As the amount of natural soil to be disturbed during the proposed works is anticipated to exceed 1,000 tonnes of

soil, the ‘greater than 1000 tonne’ Action Criteria of 0.03 %S from Table 4 has been used as the basis for
assessment of site soils.

5.2 Acid Sulfate Soils

Samples tested from within the fill material and natural sands/silty sands reported net acidity levels less than
0.03% and these materials are therefore not considered to be ASS.

Samples tested from within the natural silty clays indicated levels of actual acidity below laboratory reporting
limits, with one exception. The silty clays are therefore considered to include an apparently limited amount of
ASS, potentially at isolated locations. Whilst the amount of ASS in the silty clay soils appears to be relatively
low, under State Planning Policy 2/02 they will nevertheless require management and treatment to neutralise
any net acidity, if they are to be disturbed. As such, an Acid Sulphate Soil Management Plan (ASSMP) is
required and a draft ASSMP is presented in Appendix C for consideration.

 

Residential Development Page 9 of 10
215-219 David Low Way, Peregian Beach
Project No. 07160 18 June 2007