20517 App N.pdf [As Published] · 132007.1259

 

The pH screening tests can be used for preliminary identification of potential or actual ASS, using a combination
of three trigger factors’ as follows:

(a) The strength of the reaction with peroxide is a useful indicator but cannot be used alone. Organic
matter and other soil constituents such as manganese oxides can also cause a reaction.
(b) A pHrox value at least one unit below pH may indicate a potential acid sulfate soil (PASS). The greater
the difference between the two measurements, the more indicative the value is of a PASS. The lower

the final pHrox value the better the indication of a positive result.

(c) If the pHrox <3, and the other two conditions apply, then it strongly indicates a PASS. The more the
pHrox drops below 3, the more positive the presence of sulphides.

The results of the screening tests undertaken on samples recovered from the bores are given in Table 2,
together with an indication of which (if any) trigger factors were noted.

Table 2: Summary of Screening Test Results

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sample i Screening Test Indicators
Material . 7
Bore | Depth Type Reaction | pHr | pHrox | Strong reaction pHe-pHroot | pHrox<3
(m) with peroxide

0.0-0.25 Fill Medium | 4.7) 2.0 v v
0.25-0.5 Fill Medium | 48) 29 v ne
0.5-0.75 Fill Strong 46) 14 v v v
0.75-1.0 Fill and Silty Clay Strong 55 | 12 ¥ v v

1 1.0-1.25 | Silty Clay and Silty Sand Strong 5.4 47 v v v
1.25-1.5 Silty Sand Weak 66} 23 v v
4.5-1.75 Silty Sand VeryWeak | 5.2} 1.9 v v
1.75-2.0 Silty Sand Very Weak | 5.0 28 v v
2.0-2.25 Silty Sand VeryWeak | 4.9} 28 v v
0.0-0.25 Fill Very Strong | 6.5 | 2.7 v v v
0.25-0.5 Fill Very Strong | 5.3 | 2.1 v v v
0.5-0.75 Fill Very Strong | 5.1 15 v v v
0.75-1.0 Fill and Silty Clay Strong 63 | 1.7 v v v

2 1.0-1.25 | Silty Clay and Silty Sand Strong 66] 1.3 v v v
1.25-1.5 Silty Sand Medium | 54] 19 v v
1.5-1.75 Silty Sand Medium | 5.7 | 2.4 v v
1.75-2.0 Silty Sand Medium 5.4 18 v v
2.0-2.25 Silty Sand Medium | 5.1 1.8 v v

 

 

 

 

 

 

 

 

 

1 Ahern C.R., Ahern M.R., Powell B. Guidelines for Sampling and Analysis of Lowland Acid Sulfate Soils (ASS) in

 

Queensland 1988

Residential Development Page 6 of 10
215-219 David Low Way, Peregian Beach

Project No. 07160 18 June 2007