08/1491 - MCU - Detached House [As Published] · 132008.1491

ACID SULFATE MANAGEMENT PLAN
FOR A PROPOSED DEVELOPMENT AT
51 WITTA CIRCLE, NOOSA HEADS

4 INTRODUCTION

Bio-Track Pty Ltd has been commissioned by Middap Ditchfield Pty Ltd to prepare an acid sulfate soil
management ptan (ASSMP) for a proposed development at 51 Witta Circle, Noosa Heads. This study is
based upon soil chemical analysis data, site drawings and bore tog information. A copy of this information
is included as Appendix 1.

2 SUMMARY OF CONTROL MEASURES

Itis anticipated some or all of the excavated material will be removed. Given the difficulty of separating soil
strata during a relatively small scale excavation it is recommended all soil being excavated is to be treated
with agricuitural lime at a rate of 8 kilograms of lime per cubic metre of soil. This allows for a bulk density
of 1.8 tons/m3 and provides a safety facto of 2.2. Analytical data is available to a depth of 2.2 m below
ground level and the depth of excavation may extend to 3 metres. The lime treatment rate has a slightly
higher safety factor than normal to cover the uncertainty of soil properties in the 2.2 to 3.0 m depth range.

One validation sample will be taken for chemical analysis using either the SPOCAS or chromium reducible
sulphur test suite.

The need for de-watering will depend on the tide and recent rainfall. With luck de-watering may not be
required. In the event that de-watering is necessary then the water to be extracted needs to be pH checked
and treated to maintain the discharge water pH between the values of 5.5 and 8.5.

3 DESCRIPTION OF THE STUDY AREA

The proposed development area has the following attributes:

Location 51 Witta Circle, Noosa Heads
Area 624 square metres

Existing Elevation ~3mAHD

Elevation of Final Cut ~0.2 m AHD

Depth of Cut ~3m

Volume of Cut ~150 m3

Cut Material sand

Parent Materia! beach sand

3.1 Acid Sulfate Soil Properties

The surface soil (0-0.7 m) is weakly acid and has a very low buffering capacity. The sub-surface soit (1.2-
2.2 m below ground level is weakly acid and has a significant sulphide concentration (>0.03% chromium
reducible sulphur), These soils are regarded as potential acid sulfate soil and will require management.

Oxidation of this material will lead to development of acidity. Treatment of the sub-soil with agricultural lime
will neutralise this potential acidity.

3.2 Surface Drainage

Surface drainage has not been studied. The site is immediately adjacent to a canal or channet and
drainage wiil either be north to the kerb storm water drain and into the canal or as overland flow south into
the canal.

3.3 Sub-Surface Drainage

The groundwater has not been studied but the direction of flow is expected to be south into the canal.
3.4 Groundwater

Groundwater has been observed at a depth of 2.5 metres.

Bio-Track Pty Ltd 1