Fairfax County, Virginia is made up of over 400 square miles of land and water area and is home to approximately 1.2 million residents. The County’s wastewater utility operates a separate sanitary sewer system. The sanitary sewer consists of over 3,400 miles of pipe ranging from 8 to 72 inches in diameter, 63 pump stations, 57 flow metering stations, 11 rain gauge stations, 153 grinder pumps, and over 100,000 manholes and other structures. The system conveys wastewater to 5 treatment plants with the capacity to treat over 100 million gallons each day.
As is common on the American East Coast, the underground sewer network in Fairfax County is aging. Some areas of the network date back to the 1940s. With surrounding districts starting to face USEPA consent orders for overflow reduction, Fairfax County – with the help of engineers at Dewberry – worked to expand their already successful asset management framework to standardize risk assessment and prioritization to mitigate the risk of being put under a consent decree.
As a part of this objective, the County set forth various goals for their program including:
To help meet these objectives, Fairfax County uses InfoAsset Planner by Innovyze.
InfoAsset Planner is an asset database and risk-based project prioritization tool that helps utilities and consultants plan for repair and replacements on wet infrastructure networks.
How it works: By connecting with existing systems of record – such as ArcGIS, work order software, and hydraulic models – InfoAsset Planner analyzes asset-centric and environmental characteristics to prioritize work by risk level. Then, it provides prescriptive plans that are aligned to capital expense (CAPEX) budgets and existing organizational processes with logic-based Decision Trees.
How Fairfax County Improved its Asset Management: Fairfax County uses InfoAsset Planner to develop models that leverage likelihood of failure (LoF) values, based on condition assessment factors, and consequence of failure (CoF) values, based on factors such as asset proximity to sensitive facilities, to calculate a total risk matrix for their asset network. These risk values, along with unique operational requirements for Fairfax County, feed into a decision support framework so that they can create asset management plans that are transparent, repeatable, and cost-effective.
Fairfax County has a total of 10 Decision Trees in InfoAsset Planner that align with their cross-functional stakeholder’s objective.
These Decision Trees were designed alongside Dewberry and Innovyze and developed to integrate into their existing organizational structure. These Decision Trees are used to support critical decisions including inflow and infiltration (I/I) review and actions, pipe sag evaluation and action, lateral connection repair planning, preventative maintenance, and more.
Now, with a firm understanding of the risks in their system, the asset management team at Fairfax County can prescriptively plan renewal and replacement projects on their wastewater network.
Based on their LoF and CoF models, the County can map and visualize the high-risk areas of the system to identify which projects would do the most to mitigate risk and/or improve service.
As a result of this effort, the professionals at Fairfax County are in high standing with the community, regulators, and their stakeholders. They’ve successfully implemented a forward-looking asset management strategy that meets the needs of the community, protects the surrounding property and ecology, provides transparency to all stakeholders, and maintains fiscal responsibility.