Response to outstanding issues - ADG1786.25 Dewatering Management Plan_Rev1_07.10.25-compressed · MCU25/0020

ADG Consulting Pty Ltd

 

and at the frequencies stated in Section 6.5.2. Groundwater monitoring bores for groundwater level
gauging external to the excavation footprint are expected to be unable to be established and monitored
prior to and during construction on the site, due to limited space (SCG Consulting Engineers).

Architectural plans of the proposed development and basement arrangement are provided at
Appendix C.

5.6 Groundwater treatment

All extracted groundwater will be treated on-site using available technologies prior to discharge to the
stormwater network. The following treatment measures (or similar depending on final dewatering
contractor selection) will be adopted, and will be installed and operational prior to the commencement
of dewatering:

1. A groundwater pH buffering treatment system (primary treatment)

2. A sedimentation tank to provide additional residence time and sedimentation (secondary
treatment).

3. Installation of fine media filtration to retain suspended sediments and/or heavy metals (tertiary
treatment), if required.

Details of the treatment systems and methodologies are provided in Section 6 of this report.

Note: Consideration should be taken, regarding placement of treatment gear on site to enable easy
cleaning and maintenance throughout the dewatering phase for the project. Consider the potential
requirement for regular de-sludging of sedimentation tank/s to suitable area onsite, if available (cost
minimisation).

5.7. Nominated Hold Points

In accordance with anticipated DA Conditions, nominated hold points to be enacted during construction
have been proposed to facilitate for certification by the suitably qualified person experienced with Acid
Sulfate Soils, as well as Council Development Engineer to ensure all possible avenues for continual
dewatering below permanent groundwater level, including around pipework bedding that outlet to
waterways, are appropriately sealed. The nominated hold points regarding dewatering for this project
are:

1. Prior to commencement of dewatering/initial pump out

2. At finished excavation level, prior to blinding layer application

3. External to basement service installation trench opening/s prior to backfilling.

The above nominated hold points are subject to confirmation by the consulting engineer, and liaison with
council representatives and the Site Manager.

 

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