December 1, 2007Asset management is a planning process that ensures that you get the most value from each of your assets and have the financial resources to rehabilitate and replace them when necessary.
At its most basic level, asset management involves the systematic collection of key data and the application of analytical tools such as life-cycle cost analysis and risk assessment. Asset management thus provides information that managers can use to make sound decisions about their capital assets and allows decision-makers to better identify and manage needed investments in their organization’s infrastructure.
The key elements of a comprehensive asset management program are:
• Level of service definition
• Selection of performance goals
• Information system
• Asset identification and valuation
• Failure impact evaluation and risk management
• Condition assessment
• Rehabilitation and replacement planning
• Capacity assessment and assurance
• Maintenance analysis and planning
• Financial management
• Continuous improvement
Case Study: Fairfax County, Va.
Fairfax County is a region in northeastern Virginia located along the western bank of the Potomac River. Between 1970 and 2000, the county’s population grew from 300,000 to 950,000, resulting in steady suburban residential development and a number of high-technology business and industrial parks.
The Fairfax County Wastewater Collection Division (WCD) sewer collection system serves 234 sq miles of Fairfax County and nearly 85 percent of its population. The 3,100-mile sanitary sewer system contains 60 pump stations, 279 grinder pumps, 51 permanent flow meters and 11 rain gauges. The oldest system components were installed in areas that developed around the City of Alexandria and Arlington County in the 1940s and 1950s. Components were added as the system grew south and west over the next 60 years. Older lines were constructed using vitrified clay pipe. Lines installed between 1950 and 1970 were primarily concrete and lines installed after 1970 were made of PVC. The system collects an average of 100 million gal per day (mgd) of flow and delivers it to five treatment plants.
WCD began tracking sanitary sewer overflows (SSOs) closely in 1995, when there were 128 occurrences. There were no known water quality violations as a result of SSOs, and 22 sewer damage claims were paid to private property owners. WCD’s primary reason for embarking on major operational and management changes were based on its desire to improve customer service and to prepare for the anticipated EPA SSO control rule, which at that time was in the early stages of development.
In 1995, WCD’s wet weather peak flows of more than 80 mgd were well over its allocation of 65 mgd. Rather than construct a large wastewater storage facility to contain excess peak volumes, WCD opted to reduce I/I into its system in the service area. In addition, WCD began tracking SSOs throughout the collection system.
The SSES included CCTV inspection of all trunk sewers. The video revealed that several large diameter (15-in.and above) lines were severely deteriorated due to age and corrosion. These trunk sewers were rehabilitated during 1995 and 1996 using the cured-in-place pipe (CIPP) relining process to restore structural integrity; however, little I/I improvement was observed.
In 1996, using flow data from the hydraulic study, WCD ranked the three Alexandria Sewer Authority (ASA) sub-sewersheds according to the severity of I/I, and discovered where the most serious problems were concentrated. Comprehensive television inspection was performed on all sewer mains in this area, revealing a large number of deteriorated lines. These lines were rehabilitated using trenchless rehabilitation processes, including CIPP, fold-and-form, pipe bursting and a robotic point repair system. These repairs yielded significant progress toward WCD’s goal of reducing peak flows to the ASA plant, with peak flows reduced to below 50 mgd — well below the target reduction of 65 mgd.
The rehabilitation project also led to a slight reduction in SSOs, but the continuing incidence of basement backups and manhole surcharges indicated that more work was needed. As a result of the SSO data tracking and the extensive video inspections, WCD learned that most SSOs resulted from grease buildup and root intrusion. Because the rehabilitation efforts had been focused in the ASA area, the number of blockages had remained high in other parts of the system. WCD realized that in order to address the blockages effectively, the program had to be expanded to the entire system, and had to address operation and maintenance (O&M) issues, as well as rehabilitation needs.
The asset management program includes the activities listed below:
1. Adequate Maintenance Facilities and Equipment
One of the most important features of the program is to ensure field crews have state-of-the-art equipment and knowledge to operate it. WCD operates six combination units, four sewer rodding machines, various cleaning devices and pole-mounted digital cameras for visual inspection. Two Extend-a-Jet units allow crews to park their equipment in an accessible area and extend sewer cleaning devices into easements farther from the road. Staff responsible for sewer inspection and cleaning are trained by equipment manufacturers.
2. Development & Maintenance of a Map of the Collection System
In 2000, all of the collection system was digitized and added as a separate layer to the Fairfax County geographical information system (GIS). All sewer lines, pump stations and manholes are included in this GIS layer. As new sewer lines are added, the developer provides WCD with as-built drawings that are used to update both the maps and the GIS.
3. Management of Information & Use of Timely Information to Establish and Prioritize Activities
WCD uses a computerized asset management system (linked to GIS system) to track all related information, including maintenance, rehabilitation, and emergency calls. Such linkages would allow various departments within WCD to work more closely on capacity analysis, short- and long-term activity planning, budget, rate setting, and annual reporting.
4. Routine Preventive Operation and Maintenance Activities
WCD believes that a formal operations and maintenance plan is a necessity. Line cleaning and routine maintenance includes rodding and flushing of lines blocked by tree root intrusion and heavy grease accumulation. Routine pump station maintenance is also conducted to ensure around-the-clock operation without service interruption. To protect manholes from damage during road construction, WCD coordinates manhole maintenance with planned street repaving. When a repaving project is scheduled, WCD raises the manhole covers to the height of the finished pavement, which ensures that street crews do not seal off the manhole covers. WCD has a grease control program for commercial facilities, since most of the blockages caused by grease buildup have occurred at or downstream of commercial centers. WCD has permanently assigned a crew to inspect grease-buildup “hot spots” on an ongoing basis. This has virtually eliminated sewer blockages at these locations.
Between 1995 and 2001, WCD reduced the number of SSOs by 67 percent (from 128 in 1995 to 48 in 2001) and also made significant reductions in the impact of SSOs on the environment and private property. During the same time period, the number of claims paid to homeowners for private property damage caused by SSOs decreased from 22 in 1995 to six in 2001.
WCD’s I/I reduction goal was to decrease its peak flow to the ASA wastewater treatment plant from 85 mgd in 1995 to a maximum of 65 mgd. With the exception of an extremely heavy rain associated with Hurricane Floyd in September 1999, peak flows have remained around 50 mgd even during heavy rainfall events.
WCD is part of an enterprise fund that includes all three divisions of the Fairfax County Wastewater Management Program. While some revenue bond financing is used to support treatment plant expansions, WCD’s annual operating expenses are covered by customer revenues. Fees are charged at a rate of $3.74 per 1,000 gal of water used. When comparing average annual sewer service billings for the regional jurisdictions, Fairfax County has the lowest average annual sewer service billings at $266 (Oct. 1, 2006). Other regional jurisdictions range from $270 to $475. The affordability of sewer fees is demonstrated by the fact that 99 percent of customers pay their bills on time each year.
Between 1995-2001, WCD invested $106.4 million in its program. Of this total, 61 percent, or $65.3 million, was dedicated to O&M, compared to 39 percent, or $41.1 million spent on rehabilitation. The average annual O&M budget is $14 million (2007) and the average annual rehabilitation budget is about $10 million.
Sanjiv Gokhale is a professor of civil engineering and director of construction management program at Vanderbilt University, Nashville, Tenn.