Compiled Reference Document - MCU25/0020 (As Published)

Once basement excavation has achieved the final design level a reinforced concrete structural slab and
perimeter walls will be constructed to seal the basement and achieve a ‘tanked structure’, whereby no
permanent dewatering will be required (during operation).

8.4          Water Quality Management
Erosion and sediment control measures are expected to be applied in accordance with current industry
best practice to contain and control site runoff waters during construction.
Extracted groundwater and captured stormwater shall be monitored and maintained within a pH range
of 6.5 to 8.5. No uncontrolled release of waters will be allowed to occur during construction. The
performance criteria detailed in Table 6 must be met prior to release. The Contractor shall be
responsible for ensuring relevant water quality criteria are met prior to discharge.

Table 6: Water Quality Release Criteria

                        Indicator                                       Release Limit
                            pH                                            6.5 to 8.5
                Total Suspended Solids                                    < 50 mg/L
                 Dissolved Aluminium                                      < 0.3 mg/L
                     Dissolved Iron                                       < 0.2 mg/L
                                                      No visible litter, sheen or odour washed from the
                 Litter/Gross Pollutants               site or deposited in waters downstream of any
                                                                            discharge

Groundwater extracted during construction would be expected to require quality adjustment prior to off-
site release to stormwater. At a minimum, this is expected to involve buffering (increasing) of the pH to
within the range 6.5 to 8.5 by the addition of a suitable agent, followed by the addition of a flocculant,
and sufficient settling/contact times to reduce turbidity and metal loads. Effective treatment of
groundwater to achieve suitable release criteria requires reasonable spatial and temporal consideration.
An experienced dewatering contractor should be consulted to ensure appropriate outcomes can be
achieved.



9.           Limitations
Your attention is drawn to the document Limitations, which is included in Appendix C of this report. The
statements presented in this document are intended to advise you of what your realistic expectations of
this report should be, and to present you with recommendations on how to minimise the risks associated
with the services provided by Tectonic for this project.




Geo-environmental Investigation Proposed Residence
4 June 2025 | 25040-001-Rev1                                                                             24