Harvest Scientific Services

Stormwater Modelling

 

Storm water quality impacts need to be assessed as part of most developments, whether they are residential subdivisions or quarry developments. The purpose of such assessments is to ensure that cumulative impacts on the aquatic and riparian environments within river catchment systems are minimised and that the development can demonstrate Neutral or Beneficial (NorBE) impacts  on water quality in the receiving environment. Construction impacts are generally managed under the auspices of an Erosion and Sediment Control Plan (ESCP). 

These assessments also take into consideration existing catchment documents such as the Drinking Water Catchments Regional Environmental Plan No 1, the Hawkesbury Nepean Catchment Action Plan (HNCAP), the River Health Strategy (RHS) and Sydney Regional Environmental Plan 20 (SREP 20).

NorBE impacts can be determined by assessing pre-development status against post-development status by using the storm water modelling program Music (v3.01). Criteria adopted for any one development are based on a number of guidelines which outline desired pollutant and nitrogen loads post development. Model inputs include pluvial data as well as potential evapo-transpiration (PET) data obtained from the nearest Bureau of Meteorology (BOM) station. In addition, the nature of the site soil properties together with rainfall threshold values are used. By imposing a selection of stormwater treatment nodes, the outputs, which include:

• Total Suspended Solids (TSS)
• Total phosphorous (TP)
• Total Nitrogen (TN)

can then be calculated and assessed against NorBE.

Harvest Scientific Services has the necessary skills and training to use the Music modelling prgram to assess stormwater quality impacts.
 

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