33522 Stormwater report018-01 SWQA issued 180704 · MCU18/0001

                                                                                    CIVIL ENGINEERING PROJECT MANAGEMENT
                                                                                           SEDIMENT AND EROSION CONTROL




           CONCLUSION


Based on the calculations and report provided by Aquaintel (2014), the existing infiltration system would need
to be adjusted to accommodate the additional volume generated by the increase in impervious area of the
proposed dwelling. However, if the fraction of impervious was to reduce to a percentage less than 70%, then
the volume calculated would be adequate.
It is recommended as part of the proposed construction to divert a portion of the proposed roof water
catchment to the Stevens Street frontage. This reduction in impervious area will ensure the capacity of the
infiltration system is not exceeded and also reduce the loading on this system in major events.

The design of the proposed dwelling dramatically changes the runoff characteristics of the lot and would
negate the need for an existing catch drain (and easement over the same) along the eastern boundary. It is
recommended that the catch drain and easement (as shown in Appendix C) be removed and replaced with a
roof water pipe system to direct all runoff (other than those being diverted to the Stevens Street frontage) to
the infiltration system. The runoff will enter the system via the existing 900x600 field inlet located in the
driveway. Any adjustments made to this field inlet are not to include the existing invert levels or the connected
grated drain levels.




Glenn Ainsworth
CPEng MIEAust RPEQ (19204)
Bax Engineering Pty Ltd




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   2261 david low way, peregian beach, qld 4573       acn: 626671092             [email protected]