Murdoch University

Water Sensitive Stormwater Policy

Policy Statement

Water Sensitive Urban Design principles are adopted as Murdoch University’s preferred approach for the management of stormwater. The principles of Water Sensitive Urban Design should be demonstrated in the planning and refitting of future campus development.

The extent to which the various management practices are selected for implementation will depend on the scale of development and in-situ environmental constraints.

Definitions

“best management practice” refers to those practices in “A manual for managing urban stormwater quality in Western Australia” (Water and Rivers Commission, August 1998) will be used in conjunction with the principles of this policy and specifications and conditions relating to development of the University’s campuses.

“treatment train” means the application of a series of physical stormwater best management practices to achieve improved drainage water quality.

“multiple use corridor” refers to a linear open space which integrates drainage function as well as conservation and recreation values.

“Xeric Landscape” is a landscape consisting of native or adapted plants which require nil or minimal watering

Policy Objectives

1. This policy is to assist in:

• Protecting water quality and recharging local aquifers.
• Protection from flooding and inundation;
• Fostering improvements in local habitat values;
• The maintenance of ecological processes;
• The promotion of natural landscapes.

2. The policy seeks to retain or enhance drains by adopting the characteristics of natural systems within multiple use open space, that provide habitat for wildlife and passive recreation opportunities wherever possible.

Policy Principles

Design and assessment of best management practice.

The application of water sensitive planning and management principles involves:

i. incorporation of water resource issues early in the land use planning process
ii. addressing water resource management at the catchment or sub-catchment level
iii. storage and stormwater treatment as close to source as possible and the use of a treatment train approach
iv. buildings being protected from flooding or damage by surface or groundwater
v. a stormwater system design that incorporating the natural features of waterways to improve water quality
vi. the use of vegetation (particularly indigenous vegetation) in stormwater management to promote filtering and slowing stormwater runoff to maximise the settling of particulate pollutants and materials
vii. the use of multiple use open space/corridors when appropriate

The following are examples of structural best management practices that encompass the above principles:

• Onsite detention
• Stormwater infiltration systems
• Buffer strips
• Pollutant traps (eg Continuous Deflection Separators)
• Grass or reed swale drains
• Broken or flush kerbing
• Ponds and wetlands
• Pervious paving materials
• Native or Xeric landscaping

Selection of best management practices should follow those suggested in the Water and Rivers Commission’s Manual for Managing Urban Stormwater Quality in Western Australia.

Policy Implementation

This policy will be implemented as an environmental planning control. It remains a requirement of contractors to demonstrate an understanding of these principles through their application.

Monitoring and Auditing

Performance indicators for this policy will be assessed on a situational basis at the site planning stage.

Authorised By:

Signed by VC on behalf of the senate.

Responsibilities

The responsibility for the application of the Water Sensitive Stormwater Policy lies with the Murdoch University administration and the Murdoch University Environment Committee.

Related Policies or Procedures

Principle Environmental Policy
Biodiversity Policy
Draft Water Conservation Policy
All contract and tender documentation related to stormwater management.

Guiding Principles – Expanded

Incorporation of water resource issues early in the land use planning process

The earlier that stormwater management is addressed in the planning process, the more opportunity there is for integrating structural mechanisms to ensure water quality. This should form part of the initial site analysis prior to structure planning. Where the use of ponds or wetlands is not feasible, the use of swales and inline controls such as pollutant traps may be appropriate.

Storage and stormwater treatment should occur as close to source as possible.

Stormwater treatment such as detention should occur at source or on-site if practicable. Structural best management practices are most effective when they can be combined in a treatment train preferably connected by grass or reed swales or multiple use corridors (through open space). Storage areas should be an integral part of the landscape, wherever possible. The use of the treatment train can increase pollutant removal effectiveness, allow for filtration of suspended solids, or overcome site factors that limit the effectiveness of a single measure.

The detention capacity of the treatment train should be, wherever possible, capable of retaining the first flush and constructed according to the design criteria provided by the Water and Rivers Commission hydrological effectiveness graphs (Manual for Managing Urban Stormwater Quality in Western Australia pp 20, 21)

Wherever possible use should be made of stormwater runoff. Car parks should direct runoff water into landscaped swales by use of flush or broken kerbing to reduce the irrigation requirement and filter stormwater pollutants. Porous paving materials should be encouraged, especially in areas that are infrequently used or carry low traffic volume areas.

Development of Open Space

To maintain as much as possible pre-urban levels of stormwater infiltration development paved areas should not exceed 60% of any total area. Drainage from paved areas should be directed to garden beds or lawn, and/or the use of porous paving surfaces encouraged.

Low water and nutrient requiring plants should be required in landscaping such as native or adapted xeric plants to reduce the need for artificial fertilisers and watering.

Incorporating landscape enhancing features to improve water quality

Features that improve water quality that should be incorporated into stormwater drainage systems include:

• Native vegetation particularly sedges and grasses should be used to promote filtering of nutrients and sediments;
• Boulders or riffles to improve water aeration and oxygenation
• Ponds, pools or stormwater gullies designed as sediment traps
• Drain or watercourse profiles that provide a range of fauna habitats.