1. Ltr_160923_BA4090_Response to Information Request

        Information Required: Demonstrate how the detention tank will be able to be accessed for
        maintenance or repair purposes.

Response: Access to the detention tank is provided at the rear of the proposed buildings. A minimum
of 2.2m vertical clearance is provided for maintenance purpose such as filter cartridge replacement.
An additional drawing (B16239-CSK03) has been prepared to demonstrate the minimum clearance.
For further details please refer to Attachment D for Lamberts & Rehbein complete response and
updated drawings.
        Item 6: It is unclear from the provided drawings whether the stormwater 360 will be sitting
        within the detention tank, and whether submersion of the outlet will affect the performance of
        the Stormwater 360.

        Information required: Demonstrate how the efficiency of the Stormwater 360 will not be
        inhibited by its submersion within the detention tank.

Response: The StormFilter cartridges are located within the detention tank as shown in Attachment
C on Lambert & Rehbein’s plans B16239-CSK02. The majority of stormwater pollutants are typically in
the “first flush”. The StormFilter cartridges are located at the inlet to the detention tank within the
treatment chamber created by an internal 920mm high wall.

Incoming flows will build up behind the 920mm high inner wall, creating the necessary head to drive
the passive filtration cartridge. Treated stormwater water is discharged from the treatment chamber to
the main detention tank via pipes contained within a false floor under the filter cartridges. Higher flows
overtop this inner wall and fill the detention storage component of the tank. The cartridges will
continue to operate when the tank is filled above the inner wall height. The cartridges also provide
treatment for low flows.

For further details please refer to Attachment D for Lamberts & Rehbein complete response and
updated drawings.


        Item 7: Specific Outcome O9 of the Water Sensitive Design Code requires that runoff from the
        site is treated through natural treatment strategies. It is noted that the proposal is for all runoff
        to either be treated via a non-natural device or enter the receiving stormwater network directly.
        The Water by Design Deemed to Comply Solutions applies to this site and provides that a bio
        retention basin with filter media area of 2.2% of the catchment area (i.e. 53m²) will achieve the
        water quality reduction targets. Treatment via this method will facilitate compliance with
        Specific Outcome O9 of the Water Sensitive Design Code.
        In addition ongoing maintenance of the water quality treatment device will be responsibility of
        the property owner. Given the underground nature of the proprietary stormwater quality
        treatment device, a condition requiring for the applicant to enter into a contract for ongoing
        maintenance of the device will be needed.

        Information required: Where it is demonstrated it is not feasible for all runoff to be treated via
        natural treatment strategies, provide a letter signed by the applicant acknowledging the
        ongoing maintenance responsibilities and costs for a proprietary device compared to a natural
        treatment option.