S25-107-Stormwater Report

Best Practice Erosion And Sediment Control                   Erosion Hazard Assessment Form


[6]   REQUIREMENTS:
      All developments that involve earthworks or construction within a natural
      watercourse (whether that watercourse is in a natural or modified condition) must
      submit a conceptual ESCP to the regulatory authority for review and/or approval
      (as required by the regulatory authority) during planning negotiations.

      Permits and/or licences may be required from the State Government, including
      possible submission of the ESCP to the relevant Government department.

[7]   REQUIREMENTS:
      No areas of soil disturbance shall be left exposed to rainfall or dust-producing
      winds at the end of a development without an adequate degree of protection
      and/or an appropriate action plan for the establishment of at least 70% cover.

      COMMENTS:
      Grass seeding without the application of a light mulch cover is considered the
      least favourable revegetation technique. A light mulch cover is required to
      protect the soil from raindrop impact, excessive temperature fluctuations, and the
      loss of essential soil moisture.

[8]   COMMENTS:
      All receiving waters can be adversely affected by unnatural quantities of
      sediment-laden runoff. Freshwater ecosystems are generally more susceptible to
      ecological harm resulting from the inflow of fine or dispersible clays than saline
      water bodies. The further inland a land disturbance is, the greater the potential
      for the released sediment to cause environmental harm as this sediment travels
      towards the coast.

      For the purpose of this clause it is assumed that all sediment-laden runoff will
      eventually flow into saline waters. Thus, sediment-laden discharges that flow first
      into freshwater are likely to adversely affect both fresh and saline water bodies
      and are therefore considered potentially more damaging to the environment.

      This clause does not imply that sediment-laden runoff will not cause harm to
      saline waters.

[9]   COMMENTS:
      This clause refers to subsoils exposed during the construction phase either as a
      result of past land practices or proposed construction activities. The exposure of
      subsoils resulting from the excavation of minor service trenches should not be
      considered.

[10] WARNINGS:
     The greater the extent of external catchment, the greater the need to divert up-
     slope stormwater runoff around any soil disturbance.

      COMMENTS:
      The ability to separate “clean” (i.e. external catchment) stormwater runoff from
      “dirty” site runoff can have a significant effect on the size, efficiency and cost of
      the temporary drainage, erosion, and sediment control measures.




IECA (Australasia)                           November 2008                          Page 6