Stormwater Technical Memo · MCU23/0096

Figure 2. Extent of Proposed Arts Centre (right) transposed on existing (left).



Table 1. Estimated Surface-Split Breakdown. Note: the garden and green corridor attached to the proposed
building are included in the area calculations.

 Surface-Split                                          Existing                    Proposed
 Roof Area (m2)                                            0                          1,200
 Road/Pathway (m2)                                       1,200                          0
 Garden/Open Space (m2)                                    0                           165
 Total (m2)                                              1,200                        1,365



4      HYDROLOGIC ANALYSIS
In accordance with the Queensland Urban Drainage Manual, peak stormwater flows are
calculated based on impervious fractions. As shown in Table 2, the impervious fraction between
the existing and proposed areas do not significantly change. This indicates that there will not be
any significant changes to peak flows, and as such, detention is not required.
Table 2. Impervious Fraction Estimate.

 Hydrological Assessment                                Existing                    Proposed
 Impervious Area (m2)                                    1,200                        1,200
 Impervious Fraction (%)                                   88                          88




Technical Memo | 21-0211TM-SW01-v3 |Good Shepherd                                             Page 3