Callaghan & Toth 24-4-14 Response to Information Request

Stormwater Quality

9. Submit a stormwater quality management plan prepared by an RPEQ for the ultimate
development of the site showing how stormwater from the development will be treated
to meet current best practice load based reduction targets.

Response:

A Stormwater Quality Management Plan has been prepared to demonstrate that load based
reduction targets are achievable for the ultimate development. The SWQMP assesses the
pollutant loads from all five stages of the development including the already approved and
completed Stage 1 and 2.

The attached SWQMP shows that the stormwater treatment train which was modelled using
MUSIC V6.0.3 achieves the following load based reductions:

 

 

 

 

 

 

: MUSIC REDUCTION | POLLUTANT LOAD
Ge RESULTS _|_ REDUCTION TARGETS
Flow 3%
Total Suspended Solids 81% 80%
Total Phosphorous 58% 60%
Total Nitrogen 51% 45%
Gross Pollutants 99% 90%

 

 

 

 

 

Development in Riparian Buffer

10. Provide an amended plan for the development indicating
e. Any new lots and infrastructure removed from within the riparian buffer
f. Disturbance for roadworks and infrastructure (only for the access road from
Blue Wren Place) minimised within the riparian buffer and a minimum setback
of 5m from the top of the most eastern bank of the waterway to any
infrastructure / road

Response:

Drawing Number 1225-33 shows the riparian zones for Stages 3 and 5. The plan shows
the 5m and 10m riparian buffers from top of bank along the waterways to correspond to
Council's Biodiversity Overlay map. The eastern tributary from Lake MacDonald Drive, is
only partly mapped as Riparian Buffer Area on the Biodiversity Overlay (Map OM3.1) and as
such a buffer of 5m from the invert of the creek is provided on this section of the waterway
which is not riparian buffer area.

Areas of disturbance to the riparian buffer areas are highlighted in orange and include:
e Lot 15 encroaching into the 10m buffer;

A pedestrian walkway bridge over the eastern tributary between Stages 3 and 5;

Stormwater drainage outlets into the western tributary;

Bioretention Swales encroaching into 10m buffer on the western tributary; and

Some road encroaching into the 10m buffer on the western tributary.

The minimum setback of 5m from the top of the most eastern bank of the western tributary to
any infrastructure / road is generally achieved, apart from stormwater infrastructure
encroaching slightly into this 5m buffer.

It should be noted that the western tributary will be reshaped and the following works
undertaken to improve flood storage for the site, reduce maintenance requirements, remove
mosquito breeding habitat, and improve drainage. See Drawing 1225-33 which shows the

X:\WOBSI\CT Projects in progress\1225 30 lots lake MacDonald Drive\Correspondence\stage 3 & 4\Response to Info_Request_Jan2014.doc