Operation and Maintenance of WSUD Infrastructure

Operation and Maintenance of WSUD Infrastructure

A Presentation by Iouri Vaisman (MD, IV Water)

Operation and maintenance of WSUD and stormwater harvesting assets present some significant problems within the industry. Some excellent solutions have been developed to cope with the issues in the operation and maintenance of such schemes over the past decade however these experiences are currently not well known within the industry. In an effort to capture best practices in the operation and maintenance of WSUD and stormwater harvesting projects and provide a forum for knowledge sharing around these issues IPWEA VIC has organized a workshop on 3rd June 2014 at Banyule City Council. The workshop was fully booked in advance with more than 55 people attending on the day.

"Councils are very sensitive to the risk of grant-funded or gifted assets that become long term financial liabilities due to their maintenance and renewal requirements."
 - Municipal Association of Victoria Submission to the Office of Living Victoria’s Melbourne’s Water Future, September 2013

SIA Supported Initiatives

  • Stormwater Harvesting and Reuse Technical Tour, Adelaide 2011
  • Industry Testing and Validation Program - Gross Pollutant Traps
  • Regional Stormwater Projects Tour – Geelong, 2012

IPWEA VIC Support of Stormwater Initiatives

  • Independent verification of stormwater treatment devices (joint submission to OLV)
  • Stormwater Harvesting Guidelines (joint submission to OLV and Living Rivers)
  • Development of expertise in WSUD asset management

Various Components of WSUD


The differences between WSUD, Treatment Prior to Discharge Stormwater Harvesting are not well defined and/or clearly understood by the industry.

Practice Area Planning and Design Standards Functionality and Performance Assessment Rationale Operation and Maintenance Data and Experience
Drainage, Conveyance, Flood Mitigation Well established standards and tools (e.g. design, tables, software) Well established practice Over 50 yrs. of good data
WSUD - Treatment prior to discharge Guidelines and recommendations (not standards) (some software e.g. music) Not well established practice 3 - 10 yrs. of scattered data Some guidelines on operation and maintenance published
Stormwater Harvesting Absence of established standards and tools Not established practice 1 - 5 yrs. of little data

  • The robust engineering basis for the planning, design, construction, operation and maintenance of urban stormwater harvesting is yet to be developed
  • In the absence of the established engineering basis for stormwater harvesting – designers of these schemes frequently resort to the approaches borrowed from the more traditional disciplines such as municipal drainage and water sensitive urban design (WSUD)

Life of a Stormwater Project

Lifecycle of Assets

Acquisition of Assets Disposal of Assets
Operation and Maintenance Renewal of Assets

Lifecycle Costs

The key components of a life cycle assessment:

  • Capital expenditure
  • Installation
  • Operation
  • Ongoing maintenance and labour costs
  • Replacement costs and timing for significant expenditure
  • Lifespan
  • Decommissioning costs

Indicative Life Cycle Costs Chart

Operation and Maintenance of WSUD Assets



Funding Sources

Internal Sources:

  • Capital works
  • Asset renewal programs
  • Traffic management programs
  • Parks

External Sources:

  • Melbourne Water stormwater funding
  • DSE alternative water sources fund
  • Water retailers water saving funding
  • Federal funding such as community water grants

Sources of Operation and Maintenance Budget

- WSUD offset developers

- Stormwater management levy

- Council rates
(capture, treat, use)
- Offset potable water costs

- End user contribution

  • There is a difference in the source of funding between those two groups
  • Who can charge customers for water? Water retailers role and interest in stormwater harvesting

Delivery Options

Design - tender - construction:

  • Typical delivery option
  • Estimated costs vs contracter costs
  • Contractor guarantees the delivery but not performance
  • Hand over protocol (especially for bio-filters/wetlands)
  • Commissioning protocols

Design and construct:

  • Not commonly associated with stormwater projects but used extensively in waste water treatments
  • Performance guarantee provided by the contractor
  • Can be expanded to design, build and operate
  • Generally more cost effective

Known Issues

  • Large percentage of externally funded WSUD projects have underestimated project delivery costs 50% to 100%
  • These discrepancies only transpired at the construction tender stage (once the funding contracts have been signed)
  • The accuracy of estimated operation and maintenance costs will be tested in the next few years

Local Government have certain barriers to overcome in the selection of the best (not cheapest) advise in the areas of WSUD

Maintenance Planning

Developing an Asset Management Strategy

  • Current asset stock
  • Condition of current assets
  • Operating and maintenance costs
  • Future renewal profile
  • The funding bas for operation, maintenance and renewal

The strategy should be converted into action through the asset management plan

Asset Management Plan

The asset management plan generally requires three (3) different planning horizons:

  • 20+ years for forecasts
  • 4+ years tied to council plan
  • Annual planning tied to council budget

The asset management plan is not a static document and should be regularly reviewed (every 4-5 years) in the light of experience gained and lessons learned by the council.

Asset Maintenance

  • Proactive planned maintenance
  • Reactive unplanned maintenance
  • Rectification
  • Maintenance of asset records
  • Conditions assessments audits
  • Renewal

"Failing to plan means planning to fail"

Proactive Maintenance

Proactive maintenance is a set of scheduled tasks to ensure that the WSUD asset is operating as designed.

Reactive Maintenance

Reactive maintenance is undertaken when a problem or fault is identified that is beyond the scope of proactive maintenance.

Reactive maintenance often requires a swift response and may involve specialist equipment or skills.


Rectification of a WSUD asset is undertaken when the system is not functioning as intended, and proactive and reactive maintenance activities are unable to return the asset to functional condition.

Asset condition assessment is typically required to inform the decision process. (e.g. to increase maintenance frequency or to rectify an asset)

Rectification Assessment Process

  • Problem
  • Cause
  • Investigation requirements
  • Rectification
  • Feasibility assessment
  • Why did it happen?

Condition assessment and audits

It is recommended that audits of WSUD systems are undertaken periodically to:

  • Monitor the condition of assets
  • Assess the effectiveness of maintenance (especially important when assets are maintained by an external party)
  • Determine likely timeframes for renewal
  • It is recommended that audits are undertaken of:
    • Each asset at least every 10 years
    • All assets covered by a maintenance contract at the start and end of the contract
    • A sample of assets covered by a maintenance contract each year

In-House and Outsourcing Management Options

A brief discussion on sourcing expertise to manage WSUD/stormwater harvesting projects

Maintenance Options

Maintenance of stormwater treatment systems may be:

  • Undertaken in-house using works crews
  • Outsourced to a single contractor
  • Outsourced to separate contractors

Maintenance contract should outline:

  • Scope of works
  • Project duration
  • Performance criteria
  • Activity specifications
  • Reporting and audit requirements

Asset Maintenance Plan

Maintenance plans should be developed for all WSUD assets.

The plans need to clearly identify the maintenance requirements and state who is responsible for the on-going maintenance.

All maintenance plans should be approved by council prior to commencement of the maintenance period.

In brief a maintenance plan should include:

  • Inspection frequency
  • Maintenance frequency
  • Data collection / storage requirements (i.e. during inspections)
  • Detailed cleanout procedures (main element of all plans) including:
    • Equipment needs
    • Maintenance techniques
    • Occupational health and safety
    • Public and safety
    • Environmental management considerations
  • Disposal requirements (of material removed)
  • Access issues
  • Stakeholder notification requirements
  • Data collection requirements
  • Design details

Performance Assessment of WSUD Projects

Targets (Treatment Prior to Discharge)

All WSUD projects need to be measured, and their contribution to improving water quality logged as progress in meeting a water quality improvement target for that municipality.

Pollutant Target
Total suspended solids 80% reduction
Total phosphorus 45% reduction
Total nitrogen
Litter 70% reduction

Melbourne Water is providing support to all municipal councils to undertake municipal target setting and reporting.

Targets (Stormwater Harvesting)

  • Product water quantity
  • Product water quality
  • Reliability of supply (is water available when most needed e.g. irrigation season)
  • Is system performing as designed:
    • Ease of operation
    • Maintenance regime
  • Monitoring the environmental impact (e.g. soil tests for irrigation)
  • Inspections
  • Performance Audits

Sample audit scope

  • Assess the information such as asset location, type and contributing catchment
  • Calculate the theoretical annual pollution load per device
  • Inspect the sites, walk the catchment, confirm the types of assets (e.g. gross polutant traps
  • Adjust the theoretical model with further observations
  • Assess the theoretical loads against the practical cleaning history based on council data
  • Report on recommendations, confirm list/type of council assets, assess the device performance (theory vs practice), and any discrepancy between theory and cleaning records and recommendations

"Typically this exercise delivers 10% saving on the annual cleaning budget (based on gross-polutant trap audits)"

Project Stakeholders

  • Assets owner
  • Scheme Operator
  • Water supply/distribution to end users
  • Customers
  • Regulators

It is important to understand the responsibilities and risks (liabilities) associated with each of the listed groups.

"A risk management plan is the most appropriate mechanism for legal compliance and liability management of WSUD projects and should be included in the council's risk register and/or the council's environmental management system."

Stormwater Harvesting Scheme - Major Components

Stormwater harvesting scheme flowchart.

Independent verification scheme for stormwater treatment devices

Selecting the right treatment train to meet the water quality objectives is essential for the successful and sustainable operation of WSUD systems.

At present there are no standard methods or guidelines for testing, validation and performance assessment of stormwater treatment devices in Australia. A large number of stormwater practitioners dependent on in-house expertise and manufacturer's advice in selecting appropriate stormwater treatment strategies and estimating costs to operate and maintain these assets.

Development of Stormwater Harvesting Guidelines

One of the major barriers to the wider uptake of WSUD and particularly stormwater harvesting is the absence of comprehensive guidelines. Such guidelines would allow the stakeholders in schemes (councils, water authorities, regulators, consultants, contractors and other groups) to have a uniform reference document outlining current best practice including legislative framework, design/functionality, construction, operation and maintenance.


  • As the number of stormwater assets maintained by Victorian Local Government increases – so does the need to have a well defined operation and maintenance strategy, clear understanding of expected performance, reliable estimate of all the costs and a competent team to support it
  • WSUD and stormwater harvesting schemes continue to be managed through voluntary application of national and state guidelines
  • Definitions and interpretations vary greatly across the industry
  • Verification and/or validation requirements for the performance are unclear
  • Number of industry initiatives both statewide and nationwide

Looking Into the Future

  • The pace that the stormwater market in Australia grows will, to a large degree, depend on the certainty that it can offer to the public, the clients and the Government in delivering the stated objectives. Amongst other things, the clear path on how to achieve the stated objectives (i.e. guidelines) and the means to verify that it actually works (i.e. validation and verification protocols) is required
  • The increased certainty in the requirements for and the performance of the stormwater treatment components delivered by these guidelines and protocols should allow the market to offer/request a guarantee of performance
  • The guarantee should open more opportunities for funding, delivery, operation and maintenance of stormwater projects, leading to the greater uptake of stormwater treatment and utilization of water as a resource
  • As part of IPWEA initiative we are currently researching the best practice in operation and maintenance of stormwater harvesting projects with the intention of being able to provide some benchmarking data for the industry to use
  • Collection of data from operational projects in various states across Australia has already commenced
  • Operation and Maintenance questionnaires developed and distributed via the IPWEA Vic website
  • The data collected will not identify any organization and will not be used for any commercial purposes
  • Findings will be published on IPWEA website for members to use

Guidelines and References

  • Melbourne Water Guidelines
  • Melbourne Water WSUD Maintenance Guidelines
  • Melbourne Water WSUD Maintenance Life Cycle Costing Data
  • WSUD Inspection & Maintenance Guidelines, Blacktown Council, NSW
  • WSUD Audit Guidelines, Stormwater Victoria

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