2015-04-28 Planning and Organisation Committee Agenda

PLANNING & ORGANISATION COMMITTEE MEETING AGENDA                                   28 APRIL 2015


Water Supply Catchment
Operational Phase (completed development)
The applicant submits that, because the water supply now falls outside the jurisdiction of
Council, the water quality parameters required by the lake’s managing authority, Seqwater,
should apply. Seqwater provided written advice stating the proposed water quality treatment
is consistent with the Seqwater Development Guidelines: Development Guidelines for Water
Quality Management in Drinking Water Catchments 2012.
The applicant has demonstrated they have proposed all engineering solutions currently
considered reasonable and practical for development sites in order to reduce the additional
volume of constituents to the water catchment. Despite this, stormwater quality modelling
predicts that the development will still result in an increase in Nitrogen, Phosphorous and
sediment loads during the operational phase. The development will have an effect on the
quality of water entering the Lake Macdonald catchment due to the conversion from a
greenfield to a largely impermeable site, which will increase the load of nitrogen,
phosphorous and other water constituents to the tributaries that enter Lake Macdonald.
Notably, Seqwater’s third party advice to Council highlights that land use planning for local
water supply catchments remains a matter for Local Governments, it states:
… Seqwater’s advice in no way indicates general support of such a development in a
drinking water catchment area, however recognises that measures have been proposed in
the application which stand to minimise the risk to water quality in Lake Macdonald to an
acceptable level. Seqwater’s review of the application material has not given consideration
to the suitability of the proposed development for the site’s zoning or any precinct, overlays
or development intent expressed by Council’s planning scheme.
Construction Phase
Rainfall events exceeding the design capacity of construction sediment basins (i.e. events
above 46mm) will result in discharges of sediment from the site and into the water supply
catchment. If the development is approved conditions should be applied that Restricting the
construction phase to low rainfall months, with any incomplete construction fully stabilised in
rainfall events throughout the rainy season months of December to March could assist in
minimising potential discharges
Flooding
A detailed Site-Based Stormwater Quantity Management Plan prepared by Storm Water
Consulting was submitted. The flood modelling for the developed site includes the proposed
buildings as a blocked obstruction and the future development area was assumed to be
constructed at an elevation of 108.0m AHD (Australian Height Datum) (equating to the
highest calculated Q100 water level on the site). With the exception of a large stormwater
detention and treatment basin, the development footprint does not extend into the area
affected by the 100yr ARI flood (ARI - Average Recurrence Interval). The assessment
shows marginal increases in flood levels (1-3mm) during a 1yr, 5yr and 10yr ARI storm
events but decreases are expected during a 20yr, 50yr and 100yr ARI storm events. The
minor event increases are considered acceptable and the development will not adversely
impact neighbouring properties and the roads.
Noise
The submitted Acoustic Assessment report prepared by MRG Environmental provides an
assessment of the likely noise impacts on the development (in particular from the highway)
and the development’s impacts on nearby residents. Council officers engaged Savery &
Associates to undertake a peer review of the report. The assessment adopts DTMR noise
criteria for buildings and these criteria are reinforced by the State’s concurrence agency
response in regard to traffic noise. The development incorporates acoustic barriers up to 5m



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