MCU14/0056 Response to SARA - Consulting Report

                                                                                                            ENG
                                                Engineering Report & Stormwater Management Plan
                                        Date:          27/01/2015     Document No.:     14012-ENG-04.Docx

                                         By:              AvT          Revision No.:              F


measures are in place at the Lake Macdonald Water Treatment Plant to cope with the
additional sediment from the site.

     Earthworks
The earthworks required for the site will potentially be the largest source of sediment runoff
from the site. It is anticipated that the proposed earthworks will be staged to minimise
exposure of subsoils as the staged earthworks areas will be smaller and therefore can be more
easily managed to reduce erosion and sediment runoff from the site. The proposed erosion
and sediment control treatment devices are to be installed and functional prior to starting the
earthworks.

     Roadworks
Runoff from the proposed roads is to be treated in accordance with the Water Quality
Objectives outlined in the State Planning Policy 2013. The roads and water quality treatment
devices are to be properly installed by the contractor and maintained by the property owner.

     Stormwater
The proposed stormwater drainage system has been designed to exceed the requirements for
water quality as specified in the State Planning Policy (2013). This is achieved by providing two
treatment measures that can independently treat the stormwater runoff to meet the water
quality objectives. The first system to treat the stormwater runoff is the in ground proprietary
device and the second system is a biofiltration system. Both of these systems have been sized
to independently treat the stormwater runoff on their own, however both will be provided.
Typically both systems will be in use with the runoff from each catchment being first treated
by the in ground system to meet the water quality objectives and then through the
bioretention system which will effectively treat the stormwater runoff twice. In the event that
one of the systems fails then as a backup system the other system will treat the runoff to
meet the water quality objectives.

The water quality treatment devices are to be properly installed by the contractor and
maintained by the property owner. In the event that both systems fail then the owner is to
contact Unity Water and SEQ Water to ensure that adequate measures are in place at the
Lake Macdonald Water Treatment Plant to cope with the waste that may leave the site.

     Sewer Reticulation
The proposed sewer pump station is to be fitted with emergency storage as well as emergency
alarms. A requirement of the Property Management Plan for the site will be that should the
pump station be nearing capacity the Site Management will shut down all facilities to prevent
additional waste from leaving the site. The owner is to contact Unity Water and SEQ Water to
ensure that adequate measures are in place at the Lake Macdonald Water Treatment Plant to
cope with the waste that may leave the site.




A PO Box 26, Carina Q 4152                                                                 27 | P a g e
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