Appendix B - Stormwater Management Plan

          The proposed easement through 29 Tait Street is not designed or required to take overland flow from the
           subdivision. It will only house a 300mm pipe for inter-lot drainage. As per following section 5.5.2 and below
           we explain and provide calculations that overland flows to properties fronting Tait Street in minor and major
           events will reduce due to new road and inter-lot stormwater pits in proposed lots 1-5 and 7-9.

           There are existing pipes in Tait Street that were designed to cater for inter-allotment flows from properties
           behind them. There is a 300mm concrete pipe parallel to Tait Street, with a maximum of two lots using the
           system at present for roofwater before they enter existing gully pit in Tait Street.
           Total usage of inter-lot stormwater:
                     2 existing lots
                     9 lots from 20 Eagle Drive subdivision
                     5 lots from 28 Elkhorn Drive
                     Total lots 16, at normal rates of 10l/s per lot this is 160l/s
                     300mm pipe capacity at 2.65% grade from survey of invert levels is 220l/s
                     Therefore existing pipe capacity of 220l/s is above required 160l/s maximum inflow

       As a comment on other existing drainage pipes in Tait Street, the overall catchment falls to Tait Street at
        present and overall flow to low point in road reserve opposite 25-27 Tait Street will be the same.

           The development will have detention for its own catchment to limit to pre-development levels. Given that the
           developer is already spending a significant amount of money on purchasing 14 Eagle Drive and improving
           many existing drainage issues it is unreasonable to consider further improvements downstream on Tait
           Street.

           Also we note that Master Drainage Catchment (see Appendix) would have been used to design the existing
           stormwater system in Tait Street, with catchment and developed flows as per developed catchment (see
           Plan 1702-01B). However Operational Works detail design will need to investigate detention basin outlet
           into existing stormwater system is acceptable, but extent of works would be limited to basin requirements.




Eagle Rise Estate                                                                                                pg. 4