Compiled Reference Document - MCU25/0020 (As Published)

ADG Consulting Pty Ltd

 

Tertiary treatment — may be required following initial testing of extracted groundwater.

A filtration treatment system with specialised fine filtration media and chlorine dosing will be utilised to
provide the required heavy metal removal (specifically for total and dissolved iron) where not
precipitated and retained within the sedimentation tank/s (secondary treatment). This treatment system
will provide tertiary treatment of the groundwater prior to offsite discharge. This type of fine media
filtration treatment system is a forced-flow system under pressure, and generally capable of treating flow
rates of up to 20 L/sec per filtration unit (therefore residence time is inconsequential to treatment quality
achieved).

Tertiary treatment will only be required if the required water quality is unable to be achieved following
primary and secondary stages of treatment. Subject to the results of field and laboratory testing during
the pre-discharge monitoring event.

6.4.2 Dewatering strategy

The Site Manager, Dewatering Contractor and ADG Consulting will, where practicable prior, formulate a
dewatering strategy to ensure that the dewatering treatment system is sufficient to meet the
requirements of the project and that the necessary equipment can be accommodated within the site
prior to the commencement of dewatering.

Where the construction of the proposed development requires occupation of the road reserve (verge
area and/or road formation) for either short term or long term, a road reserve permit must be obtained
from Council prior to any occupation of the road reserve.

6.4.3 Initial pump-out
Prior to discharge of any extracted groundwater to the canal system, the following pre-dewatering

procedure will be undertaken:

1. The basement area will be excavated down to the standing groundwater level.

2. The initial dewatering discharge will be directed (via the treatment systems) into the excavation and
allowed to infiltrate/recharge the aquifer. This process will provide initial clarification of the extracted
groundwater as disturbed sediment loads are typically reduced following the initial pump-out.

3. Samples of the treated groundwater will be recovered and analysed for the parameters detailed in
Table 2 and Table 3.

4. The extracted groundwater will be directed into the canal system following confirmation that the
water quality complies with the discharge criteria.

6.5 Monitoring
6.5.1 Visual monitoring

Visual inspections of the site and dewatering equipment shall be undertaken daily by the Site Manager
to identify the following:

— Quantity of chemical product within the dosing system
— _ Effective operation of all dewatering treatment equipment

— Short circuiting of water around baffles and filter media in sediment tanks, where required to be
installed.

— Visible hydrocarbon sheens and odours
— Green blue or extremely clear water indicating high levels of dissolved aluminium.
6.5.2 Water quality monitoring

Water quality monitoring will be undertaken for the duration of dewatering activities at the site by a
suitably qualified and independent person. The monitoring will include analysis of the extracted
groundwater, treated discharge water and off-site monitoring in the receiving waters (in the mixing zone
within a 20 m radius of the discharge point). The exact location within the receiving waterway (Noosa

 

ADG1786.25 Dewatering Management Plan_Rev1_07.10.25 Page 14