B3.B Stormwater quality


    Objectives

  • To ensure development does not detrimentally impact on water quality. 
  • To safeguard water quality within drinking water catchments.
  • To safeguard the natural environment.
  • To ensure water quality is protected and maintained during construction and operation of the development.

Development in a drinking water catchment

Development that has the potential to affect water quality in a drinking water catchment will be referred to Hunter Water Corporation under section 51 of the Hunter Water Act 1991 (NSW). Refer to Hunter Water Corporation’s Protecting our drinking water catchments - Guidelines for developments in drinking water catchments for development types that will likely require referral to Hunter Water Corporation. Hunter Water Corporation requires that all development in a drinking water catchment achieves a Neutral or Beneficial Effect.


Controls

B3.7 Requirements for development within a drinking water catchment: 

  • Before water is released into public drainage, the development must achieve a Neutral or Beneficial Effect (NorBE) on water quality, and the following water quality stripping targets (testing of both criteria is required to achieve the better water quality outcome):
    • Total nitrogen retention post-development load: 45%
    • Total phosphorous retention post-development load: 65%
    • Total suspended solids post-development load: 85%
    • Gross pollutants post-development load: 90%
  • Water quality modelling (such as MUSIC modelling or SSSQM certification) must be used to demonstrate the achievement of water quality outcomes and targets.
Control B3.7 does not apply to:
  • Development on lots less than 250m2.
  • Development that, in the opinion of Council, will not impact water quality; or
  • Development where a WSUD strategy applies and supporting information is provided demonstrating that the water quality requirements in the WSUD strategy have been incorporated into the development. 

NorBE Assessments

In demonstrating the achievement of water quality outcomes, NorBE assessment may require an additional risk assessment depending on the development type.

The development must achieve a Neutral or Beneficial Effect (NorBE) on water quality and the following water quality stripping targets:


Total nitrogen retention post-development load

0%

Total phosphorous retention post-development load

0%

Total suspended solids post-development load

0%

Gross pollutants post-development load

0%


B3.8 Requirements for development outside a drinking water catchment:

  • The following water quality stripping targets must be achieved before water is released into public drainage:
      • Total nitrogen retention post-development load: 45%
      • Total phosphorous retention post-development load: 60%
      • Total suspended solids post-development load: 85%
      • Gross pollutants post-development load: 90%
  • Water quality modelling (such as MUSIC modelling) must be used to demonstrate the achievement of water quality outcomes and targets.

Control B3.8 does not apply to:

  • Development that is a dwelling house, semi-detached dwelling, secondary dwelling, dual occupancy, two-lot subdivision, and/or ancillary structure to residential development;
  • Alterations and additions to a dwelling house, semi-detached dwelling, secondary dwelling, and/or ancillary structure to residential development;
  • All minor alterations and additions;
  • Development that, in the opinion of Council, will not impact water quality; or
  • Development where a WSUD strategy applies and supporting information is provided demonstrating that the water quality requirements in the WSUD strategy have been incorporated into the development.


The following water quality stripping targets must be achieved before water is released into public drainage:


Total nitrogen retention post-development load

0%

Total phosphorous retention post-development load

0%

Total suspended solids post-development load

0%

Gross pollutants post-development load

0%


B3.9 Requirements for stormwater quality improvement devices:

  • Devices must be sited and designed to be taken offline from stormwater quantity drainage systems; and
  • Devices must be maintained during the ongoing operation of the development.

B3.10 Erosion and sediment control measures consistent with the 1102 Control of Erosion and Sedimentation (Construction) must be maintained during construction.