SWMP change reps

Headland Drive Road Reserve. Roof runoff from existing dwellings appears to be a mixture of
discharging directly to ground level & via kerb adaptors to Headland Drive.

The total impervious areas have been estimated using the detailed site survey and was found to be
approximately 1521m2 which equates to approximately 22% of Impervious Area for (Cat A) & 41% of
Impervious Area for (Cat B) respectively.

The existing site catchments are as follows.

Catchment A

    -    Area – 0.4833 Ha
    -    Tc – 15 mins
    -    Fraction Impervious (Fi) – 0.21



Catchment B

    -    Area – 0.1485 Ha
    -    Tc – 13 mins
    -    Fraction Impervious (Fi) – 0.41



Peak flow rates for the median design storm for the existing site are given in Table 6.3

                             Table 6.3 – Existing Site Peak Flow Rates (L/s) (At year 2100)

  Storm Event         Q1             Q2             Q5             Q10            Q20           Q50      Q100
                     (1EY)         (0.5EY)        (0.2EY)      (10%AEP)       (5%AEP)         (2%AEP)   (1%AEP)


        Cat A           79           119            160            186            218           259       287

  Existing PFR

        Cat B           27           39              52             59             69           83        91

  Existing PFR

 (PFR – Peak Flow Rate)

6.1.3     Proposed Site
The development consists of the construction of mixed residential townhouse/ unit development along
with a shared access driveway and ground level landscaping/ courtyards & a community pool area. The
total pervious area for the site was calculated to be approximately 1368m2.


SCG Consulting Engineers                        Page 17                                 SCG Ref: 33132(SWMP).RevC