Response to RFI 30-03-22

Item 2.
Analysis has been undertaken for the 1% AEP (2100) for the detention tank, biobasin 1 and
biobasin 2 with severe blockage. The bio basins are just starting to overflow but with
minimal discharge of 9 litres/second.

Item 3.
Detention tank and bio basin levels have been modified as necessary.

Item 4.
The drains model has been provided with the response for Council to check the calculations
and model assumptions. A hard copy of the data model output is also included.

Item 5.
The drainage model has been provided with this response. The program is available for
Council from Watercom to view the model to carry out their review. We have also provided
a hard copy of the model data and output.

Item 6.
    (a) An overflow flow path has been incorporated into the stormwater infrastructure.
        Blockage of any stormwater pits will allow the overland flow to discharge through
        the carpark and into biobasin 2.
    (b) Rock energy dissipaters have been included to the biobasins
    (c) Retaining wall heights have had to be increased slightly due to Council’s
        requirements for 1% AEP (year 2100) 1:2000 year ARI and severe blockage
        modelling. We have no alternative with regards to altering these heights.
    (d) Supporting calculations have been provided for a 20% increase in the 1% AEP
        generally as requested. The swale drain easily carries the flow.
    (e) Deluca will be providing the approval as requested
    (f) End of swale calculations are provided as per item (d)
    (g) Provided in drawings
    (h) Provided in drawings
    (i) Provided in drawings
    (j) Provided in drawings



Attachements:

Swale Drain Calculations
Drains Model
Model Data Spreadsheet
Model Output Spreadsheet




 Neil McKenzie& Associates | 20004 RFI OPW21/0272                                   2