MCU14/0106 Appendix E - Engineering Report

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August 2004 -14- 04682104(AB)

 

Table 3: ASS Action Criteria

of: teria if more.

tonnes disturbed.
exture range rtrail =| Acid trail
MeDonald et al. clay oxidisable mol H* / tonne
(1990) . Content ven-dry basis) -| (oven-dry basis)
, TPA
Coarse Texture <5 . 0.03 18

Sands to loamy sands
Medium Texture . 0.03 18
Loams to light clays

Cc.

 

Fine Texture . 0.03 18
Medium to heavy
and cla’

The data quantifying the acid generating potential for soils sampled within the site have been
collated and are summarised in Table C1, with the laboratory reports, in Appendix C.

Samples with pH drops of 2.0 or more pH units or pH <3 after oxidisation are highlighted in
Table Cl. From the laboratory test results, Scr and TAA values above the action levels are also

highlighted.
The following observations are made regarding the investigation results as presented in
Table C1:-

> None of the 36 samples show pH after oxidation of pHr — 2.0, or pHrox of less than 3.0.

> All ten samples selected for laboratory testing returned Sc, results less than the laboratory
detection limit (0.01%S), which is less than the Action Criteria (0.03%S).

> All ten samples tested for TAA returned results above the Action Criteria (18 mol H+/t),
with 9 of 10 results ranging between 31 mol H+/t and 83 mol H+/t (indicating a slight to
moderate existing acidity hazard. The sample from 1.5 m depth in test pit GA18 returned a
TAA value of 147 mol H+/t.

Golder Associates