Appendix B - Stormwater Management Plan

5.0       FLOODING ASSESSMENT

5.1       Existing Conditions

The summary below is taken from a previous investigation by Callaghan and Toth, with some updates to current
proposal:

5.1.1     Currently there is no major flood dedicated overland flow path for the runoff from the 3.323ha catchment
          (4.514Ha developed as per Council Master Catchments no 2153 & 2154 in the Appendix and developed
          catchment on plan 1702-01B) to the east of No.14 Eagle Drive (note: of the 4.514ha, our clients land
          falling to this point represents 1.056ha). The problem is also compounded by the fact that existing gully
          pits and pipe drainage at the sag at No.14 Eagle Drive only have the capacity to take a one year storm
          runoff. Therefore runoff overtops the kerb regularly and floods No.14 Eagle Drive and in large storms
          the runoff also floods through No.16 Eagle Drive.

          Both of those occurrences have been verified on site by the owner of No.16 and Rental Agent for No.14.

          The Owner of No.16 said that in large storms the runoff floods No.14 and has entered the house, it also
          backs up and floods down his (No.16) driveway and floods his shed in the south west corner.

          The real estate agent handling the rental of No.14 said that carpet has been replaced as a result of
          flooding, sand bags have been used in other events to stop water entering the house, and that a mound
          has had to be built in the front yard to divert flooding from the road away from the front door and down
          the side of the house.

          A further problem is that this house is also built only 2.7m away from the boundary adjacent where it
          floods through the land. In this location there is not enough room for a Council 3m easement or to lay
          pipes without impact on the house footings.

5.1.2     It can be seen at Eagle Drive (in sag area opposite No.14) that Council has recently replaced and
          lowered the grates to the gully pits in this location in an attempt to alleviate a problem.

5.1.3     The existing undersized stormwater pipe from the sag gully pits at No.14 does not go down the side of
          the house in the lowest point in the street, instead it goes down the north side of No.12.

          This pipe has no easement and the house is built right next to the pipe approximately 0.8m to 1.1m off
          the side boundary. These facts mean this pipe cannot be replaced by a larger pipe to reduce flooding.

5.1.4     A separate flooding problem exists for the properties 31, 29, 27 and 25 Tait Street. Our Clients 1.191ha
          of un-developed land slopes toward the rear of these properties and floods through their yards onto Tait
          Street (see plan 1702-01B).

      This problem was addressed by Council approximately 15 years ago by the construction of an extension of
      the underground drainage system along the frontages of these properties.

      Callaghan and Toth designed this system for Council. The system is in place even though no records exist.
      Its purpose was to allow residents to run a stormwater pipe from our Clients land boundary through to the
      piped extension so as to alleviate the flooding. Unfortunately from discussion with owners they were not
      aware of this option.



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