Swmp

Catchment A will be detained through the use of a in-ground open detention basin, Bio-Retention Bed
(BR-A) located in the northeast corner of the site to detain all flows from Catchment A

For catchment B it is proposed to utilize a series of underground detention tanks to capture all roof
water from building 5, 6 & 7. Tank overflows & all groundwater runoff will then drain to an in-ground
open bio retention/ detention basin, (BR-B) located at the southern corner of the site on Headland Dr.

We propose for the detention systems to cater for flows up to the Q100 storm event and a limit the peak
flow rates of pre-development levels for all storms up to the Q100 storm event.

For proposed Catchment A, the proposed BR-A will have the following properties: -

         •      Base Area                            =     98m2
         •      Internal Depth                       =     1.0m
         •      Low Flow Orifice                     =     275mm diameter
         •      High Flow Orifice                    =     250mm diameter
         •      Overflow Wier Elevation From Base =        1.0m
         •      Required Volume                      =     100m3
         •      Provided Volume                      =     110m3

For proposed Catchment B, the proposed inground detention tanks, located under the driveway will have
the following properties:

Detention Tank for Building 5 roof water:

         •      Base Area                            =     26m2
         •      Internal Depth                       =     1.1m
         •      Low Flow Orifice                     =     55mm diameter
         •      High Flow Orifice                    =     75mm diameter
         •      Required Volume                      =     23m3
         •      Provided Volume                      =     28m3

Detention Tank for Building 6 & 7 roof water:

         •      Base Area                            =     24m2
         •      Internal Depth                       =     1.9m
         •      Low Flow Orifice                     =     95mm diameter
         •      High Flow Orifice                    =     100mm diameter
         •      Required Volume                      =     45m3
         •      Provided Volume                      =     48m3


SCG Consulting Engineers                  Page 19                            SCG Ref: 33132(SWMP).RevB