Stormwater harvesting – standards, regulations and Industry practice Presentation to Recycle Water May BH:

Overview Current status of stormwater harvesting in VIC Typical SWH project’s components & function Melbourne Water Guidelines for SWH diversion Overview Functional requirements Base flow & maintenance flow requirements Design examples Joint initiatives of Melbourne Water and IPWEA IVS – independent verification of stormwater treatment devices Stormwater Harvesting Guidelines Questions BH:

Definitions o Urban stormwater - “net increase in run off and decrease in groundwater recharge resulting from the introduction of impervious surfaces such as roofs and roads within urban development” o “Urban stormwater” is only available within the urban growth boundary o Base flow in waterways is not considered urban stormwater - no access to base flow will be permitted BH:

Interim allocation rules If stormwater is flowing to the sea via a drain, 100% of the stormwater may be harvested If stormwater is flowing to a stream from an existing development up to 50% of existing stormwater can be harvested for use and 50% is reserved for the environment If there is a scheme to harvest more than 50% of the resource a study is required to assess implications for the environment All stormwater generated from new development is available for harvesting BH:

Licensing The harvesting of water from Melbourne Water’s drains and waterways requires a licence under Section 51 of the Water Act BH:

Administration Stormwater harvesting schemes continue to be managed through voluntary application of national and state guidelines Relevant guidelines: Australian guidelines for water recycling: managing health and environmental risks (phase 2) - stormwater harvesting and reuse (NRMMC, EPHC et al. 2009) No compliance monitoring requirements (voluntary compliance) BH:

Stormwater Harvesting Scheme Major Components BH:

Need to set some definitions… BH:

Guidelines for Stormwater Harvesting on Melbourne Water assets Design, Construction & maintenance of diversion structures BH:

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To assist stormwater harvesting proponents Melbourne Water has developed standard drawings and associated technical guidelines for the design, construction and maintenance of diversion structures for stormwater harvesting on Melbourne Water assets. The availability of these drawings and guidelines is expected to deliver the following benefits: To assist proponents and applicants in developing a suitable design likely to be supported by Melbourne Water To ensure that Melbourne Water’s operational and environmental requirements are met and the outcome is therefore consistent with stormwater harvesting principles. BH:

BH: Functional requirements reliable diversion of designed flow rates and volumes and uniform diversion rate control min hydraulic impact on the existing drainage system automatic operation and reliable performance (e.g. no moving parts) minimal risk of blockage minimum maintenance requirements safe access for inspection, maintenance and cleaning allowance for flow calibration and metering structural integrity prescribed flow is being passed through (environmental and/or self-cleansing flows) ability to be isolated or shut off in case of maintenance requirement or pollution incident.

BH: Base flows and self-cleansing velocities For all new diversion structures constructed on Melbourne Water drainage assets, allowance should be made to pass low/base flows through the system both prior to and during times of flow diversion in order to avoid sediment deposition and associated maintenance problems in the drainage network. The minimum self-cleansing velocities for the design of these flows must be calculated on a case by case basis using the boundary shear stress approach. These calculations shall demonstrate that the design solution allows for the continuation of base flows through the system and that these flows produce the boundary bottom shear stress equal to or exceeding the pre-set minimal boundary bottom shear stress of τ ≥ 1.5 Pa.

Design Examples BH:

Design Examples BH:

(A)Independent verification scheme for stormwater treatment devices (B)Development of Storm Water Harvesting Guidelines – VIC BH: Current Industry Initiatives

Overview Joint initiatives of Melbourne Water and IPWEA Participation and support from Environmental Protection Authority Victoria (EPA Vic), Victorian Department of Health (DOH VIC), Victorian Civil Contractors federation, Storm Water Victoria, CSIRO, Monash Uni and other industry representative BH:

Independent verification scheme for stormwater treatment devices BH:

Project Objectives The overall aim of this project is to establish the regulatory and administrative framework, product testing and validation protocols and performance database for the storm water treatment devices to enable the better utilization and broader uptake of Integrated Water Cycle Management (IWCM) in Victoria BH:

Concept BH: a REGULATIONS ADMINISTRATION TECHNICAL

Jurisdiction and extent The proposed IVS is developed and implemented in the state of Victoria, Australia serving as a pilot for the broader National scheme. Devices covered by the scheme This Independent Verification scheme applies to pre-engineered, commercially- available technologies for storm water treatment. BH:

Development of Storm Water Harvesting Guidelines – VIC BH:

Project Objectives The objective of this project is to produce comprehensive guidelines for the practical implementation of storm water harvesting schemes in VIC as part of an Integrated Water Cycle Management (IWCM) approach. The resultant document has the potential to be included as an appendix to the new revision of Urban storm water best practice environmental management guidelines (BPEMG), adding consolidated knowledge from across Australia to the practical implementation of SWH schemes. BH:

Concept BH:

Conclusions Stormwater harvesting schemes continue to be managed through voluntary application of national and state guidelines with no regulatory compliance monitoring requirements Definitions and interpretations vary greatly across the industry No verification and/or validation requirements for performance Number of industry initiatives both at the state and National level Future directions BH:

Questions BH: