Draft Decision Process for Stormwater Management Released

The Department of Water has released the Decision Process for Stormwater Management in WA: Draft for Consultation for comment until 21 October 2016.

Urban development should be designed to ensure that liveable, resilient, sustainable and productive cities and communities are created by interconnecting the built, social and natural environments. Urban stormwater systems play a significant role in creating water sensitive cities and communities.

The decision process outlines the State government’s approaches and criteria for planning and designing new and existing (retrofitting) stormwater systems throughout Western Australia.

This, the third edition of the Decision Process, is a part of the Department of Water’s Stormwater Management Manual for Western Australia.

This update was developed to:

  • apply current best practice international approaches and criteria for small rainfall event management
  • review requirements for the north-west and north of Western Australia when applying the 1-year, 1-hour average recurrence interval rainfall event criterion to avoid over-sized systems
  • consider shallow groundwater management at the beginning of the stormwater management decision process
  • strengthen the case for small rainfall event management to be considered early in the design of urban stormwater management systems
  • incorporate the new rainfall event terminologies from Engineers Australia’s review of Australian Rainfall and Runoff
  • explain how to include natural hydrological processes in stormwater management
  • provide an explanation of stormwater management relating to management of receiving water bodies and their buffers
  • consider urban liveability and amenity in the design of stormwater and shallow groundwater management systems
  • provide updated information on stormwater management in the land and water planning process.

The Decision Process provides clear guidance for planning and designing  urban stormwater systems that:

  • protect public health and safety
  • protect public and private infrastructure and buildings from flooding
  • protect and enhance sensitive receiving environments by managing the water cycle, water quality, habitat diversity and biodiversity
  • enable economically sustainable construction, maintenance and renewal/replacement costs
  • achieve good urban amenity.

Innovation is encouraged, especially in constrained and challenging sites, and therefore the decision process does not prescribe one type of design or method.

The decision process includes two key figures. Figure 1 shows the process of integrating stormwater management into the land-use planning system. Figure 2 illustrates the design process and criteria for stormwater management in Western Australia to aid those designing and assessing the urban form. New to this document is a suite of conceptual diagrams (figures 3–16) that visually represent the logic of stormwater management for different site conditions and scales. These diagrams provide examples and are not intended as a one-size-fits-all solution.

The Department welcomes your comments on this document. Closing date for submissions is 21 October 2016.

Submissions can be mailed to:

Department of Water
Attn: Emma Monk, Urban Water Branch
PO Box K822
Perth WA 6842

Alternatively, submissions can be emailed to: stormwater@water.wa.gov.au