Att 1 - RFI Amended SWMP

                                                                               23098 - SBSMP/3
                                                                                       Page 7




4.2 Existing Drainage Patterns
Following an assessment of the existing site conditions and drainage infrastructure we can confirm
that the site has the following drainage patterns:

Roofwater Runoff
    1. Roofwater runoff from the site is discharged onto the ground where it sheet flows to the
       Environmental Management and Conservation Area, northeast of the site.
Surface Runoff
    1. Surface runoff from the site sheet flows to the Environmental Management and
       Conservation Area, northeast of the site.
External Catchment
    1. There is an external ground catchment contributing runoff from 52 Elm Street, southwest
       of the site, which sheet flows through the site to the Environmental Management and
       Conservation Area, northeast of the site.

It is noted that all sheet flow traversing across the site becomes concentrated along the eastern
boundary of the site due to an existing bund along this boundary that was constructed as part of
7 Pearl Street. Concentrated flow along this boundary is directed to the Environmental
Management and Conservation Area, northeast of the site.

Refer to Figure 4.1 for a drainage schematic and Appendix A for the detailed site survey plan.


4.3 Lawful Point of Discharge
If the proposed development maintains pre-development flow conditions, the lawful point of
discharge (LPD) is the existing Environmental Management and Conservation Area, northeast of
the site.

In consideration of the site characteristics, surrounding topology and stormwater drainage
infrastructure, the aforementioned proposed lawful point of discharge is considered to be
compliant with the criteria for lawful point of discharge outlined in Section 3.9.1. of QUDM 2017
as per below:

    i) The location of the proposed discharge point is under the lawful control of the local
       government or other statutory authority from whom permission to discharge has been
       received.

    ii) The post development discharge will not cause an actionable nuisance, nor environmental
        or property damage, as the existing flow characteristics and drainage patterns will be
        maintained for the proposed development.

    iii) Authority to discharge over affected properties will not be required as the proposed
         drainage patterns does not impact surrounding properties adjacent to and downstream of
         the subject site.

Refer to Section 5 outlining the Stormwater Quantity aspects of this site and Appendix D for the
Water Quality and Drainage Code.




Site Based Stormwater Management Plan
Proposed Townhouse Development at 5 Pearl Street, Cooroy