Appendix E - Stormwater Management Plan

 C2                                                    SW Treatment Device/s to meet 90/60/45 %Reduction


Results are indicated in the table below:

 Results at Receiving Node         Source Load Residual Load    % Reduction
 Total Suspended Solids (kg/yr)           36300           7740            79
 Total Phosphorus (kg/yr)                   76.4           23.1           70
 Total Nitrogen (kg/yr)                     481            240            50
 Gross Pollutants (kg/yr)                  4620            249            95


    4. Item 16 – conflicts with item 12.
No Conflict. Item 12 is to do with commencement of construction of the biobasins – such as installing the sand. Item
16 has to do with installation of landscaping.
Noted ‐ planting will be undertaken after 80% of building phase completion as per our report and WBD guidelines.
In terms of requiring 80% of upstream earthworks catchment to have suitable groundcover before functional
elements of bioretention basin can be installed, this is not a requirement of Option 1 outlined in the WBD guidelines
as the biobasin functional elements will have suitable sediment protection. Refer to the below procedure.

Option 1 of WBD Construction and Establishment Guidelines (which we are proposing) indicates the following
procedure during construction and building phase:
     During earthworks phase functional elements of basin (outlet, filter, drainage layer) are installed with
       protection (as per below)
     Temporary sediment fences around perimeter of basin, and filter cloth and turf above filter layer so that
       basin can function as a sediment basin during construction
     After 80% building phase completion removal of temporary measures (sediment fence and filter cloth) will
       occur so planting of biobasin can commence.




    5. Item 8 – Should read “…all hardstand areas within the site except for small car parking area adjacent to the
       Southern Basin are treated by the bio-basin. The Trading Post Road by-passes the bio-basin……..”
I propose to change the word biobasin to “water polishing devices “.
Noted – As per the recently updated strategy and Drawing No. B14158.W-SK102 there are some areas near the
entrance and 6 lots immediately north of Trading Post Road cul-de-sac that were modelled as bypassing treatment
(orange hatch on plan). This still achieves the overall load reduction results that have recently been reviewed.

    6. Item 19.10 – The report will specify non-use of fertiliser around water bodies.
What about pesticide use?
Bio-degradable pesticides will be used.
    7. Item 11 – This line item does not agree with the report. Please note that the report has proposed to adopt
       Option 1 of Table 4.4 and section 4.7.2 of Water By Design’s Construction and Establishment Guidelines
       (2011)
These conditions are for Op Works stage 2 and the only device stage 2 has is a biobasin.
See response to Item 4 above.
The SWMP and SMCMP report provides details of design and management of all stormwater management devices
within the overall development (including GPTs, pond and bioretention systems). As indicated in our reports we are
seeking approval for all stormwater management devices in the overall development. Stage 4 and 5 Opworks
Drawings will be provided at a later date.
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