2.1 Development of Risk-Based Asset Management Framework

Transcription

1 SECTION 2 Development of Asset Management Framework 2.1 Development of Risk-Based Asset Management Framework As part of the master planning effort, WES developed a risk-based asset management framework to augment its current asset management practices. With this new framework, operations and maintenance (O&M) activities and capital investments are evaluated and ranked by priority in terms of risk posed by an asset s failure. Risk is measured in terms of the consequence, which is evaluated by the impact on levels of service, and in terms of likelihood, which is the possibility that the asset will fail. The level of service categories defined for WES are: Health and safety of the public and employees Financial impact Public confidence Environmental compliance System reliability Likelihood of failure was evaluated based on physical condition of the asset, performance, external and internal physical factors affecting the asset, O&M protocols, and reliability history. The consequences of failure categories are assessed individually as negligible, low, moderate, or severe. The likelihood categories are rated as negligible, unlikely, possible, likely, and very likely to contribute to asset failure. With this approach, the likelihood and consequence scores are combined to determine a risk score for each asset. The relative order of risk established by this evaluation is used to guide decisions about operating and maintenance activities, rehabilitation and replacement of system components, and establishing priorities for capital improvement projects. Adopting a risk-based asset management approach to assessing its infrastructure will allow WES to continue to make effective, defensible and reproducible decisions regarding capital rehabilitation and replacement projects, as well as refining its operation and maintenance protocols. With a focus on maintaining its levels of service at the lowest life-cycle cost, WES will create efficiency at all levels of planning and operations. For more information about the asset management framework developed refer to Technical Memorandum 5.1, Pipeline and Pump Station Condition Assessment Evaluation (provided in Appendix E). CCSD1_SSMP_ DOC 2-1

2 2.2 Recommendations To ensure WES receives the most value for the resources invested in this risk-based approach, the following recommendations are offered: Undertake detailed condition assessments of those interceptor segments and subbasins having unacceptable risk, giving priority to those with highest risk. Incorporate condition assessments into planned maintenance activities. Update risk scores based on the most recent condition and performance assessments. Revisit consequence scoring at periodic intervals, no greater than every 5 years, but more frequently as demographics, customer issues, and regulations change. Update asset hierarchy as new assets are added to the system and when assets are removed from the system. Use computerized maintenance management system (CMMS) and geographical information system (GIS) to store consequence and likelihood data, and retrieve the data to perform periodic analysis when preparing capital improvement program (CIP) and revising O&M protocols. Incorporate a risk-based approach into operational and business processes and train staff in its use. Expand the risk-based approach to treatment facility assets. 2.3 Existing System Characterization CCSD #1 is served primarily by gravity-flow sewage collection systems that terminate at the Kellogg Creek Water Pollution Control Plant (WPCP). Pump stations provide service to areas at the edge of the gravity flow basin boundaries. In total, CCSD #1 includes fifteen pump stations and approximately 1.6 million linear feet of collection system pipeline. The existing collection system is briefly characterized in Figures 2-1, 2-2, and 2-3 in terms of pipeline diameter, construction material, and year of installation based on WES data. As shown in Figure 2-1, most the collection system pipelines are 8 inches in diameter. 2-2 CCSD1_SSMP_ DOC

3 FIGURE 2-1 Summary of CCSD #1 Collection System Pipelines by Diameter 1,400,000 1,200,000 Quantity of Pipe in Linear Feet 1,000, , , , , Pipe Diameter in Inches CCSD1_SSMP_ DOC 2-3

4 The currently available inventory of CCSD #1 collection system pipeline materials accounts for approximately 40 percent of the existing system. As shown in Figure 2-2, the majority of the inventoried system is made of concrete pipe. Based on general system knowledge, CCSD #1 staff indicates that most of the un-inventoried portion of the system is probably constructed of PVC. FIGURE 2-2 Summary of Inventoried CCSD #1 Collection System Pipelines by Type of Construction Material 400, , ,000 Quantity of Pipe in Linear Feet 250, , , ,000 50,000 0 ACP CCP CIP CSP DI HDPE NCP PE PVC RCP RPVC STL Type of Pipe Material ACP = asbestos cement pipe; CCP = concrete culvert pipe; CIP = cast iron pipe; CSP = cement sewer pipe; DI = ductile iron; HDPE = high density polyethylene; NCP = concrete pipe; PE = polyethylene; PVC = polyvinyl chloride; RCP = reinforced concrete pipe; RPVC = reinforced PVC; STL = steel. 2-4 CCSD1_SSMP_ DOC

5 The construction history of the collection system is summarized by linear feet in Figure 2-3. As shown, nearly a third of the system was constructed in The primary elements of the system were constructed from 1971 to 1976, including approximately 80,000 feet of interceptor sewer lines. Since that time the system has been expanded incrementally to accommodate community growth. FIGURE 2-3 Summary of CCSD #1 Collection System Pipeline by Construction Year 600, ,000 Pipeline in Linear Feet 400, , , ,000 0 Unknown Pipeline Construction Year 2.4 Data Development Needs Inventory data to support the modeling of the collection system were found to be available and of high quality for the portion of the system analyzed. Invert and ground elevations, pipe slope, diameter and material were all provided by WES from their GIS. No supplemental survey data were required to complete the system model. While portions of the system have been inspected using closed-circuit television (CCTV) techniques, the physical condition data are not compiled into a comprehensive database that is available for analysis. To complement the hydraulic capacity analysis that is the focus of this master plan, the structural condition should be added to future system evaluations. The condition data would also support a pipeline replacement plan consistent with an asset management system. CCTV information would help inform the condition component of the asset management risk scores, and the condition scores in WES s GBA Master Series software system can be determined from future field condition assessments conducted using the approach developed for the pump station evaluation. CCSD1_SSMP_ DOC 2-5

6 Flow monitoring data should continue to be gathered to support future refinements to the system model and to gage potential increases in RDII over time. The asset management information compiled during the pump station and conveyance elements of the master plan project should be incorporated in the GBA software system. GBA can then be used as an asset management tool. Condition assessment should be used to establish a base reference index score that can then be used to establish replacement/repair priorities. Land use data in the Hoodland area was not as complete as the Metro database used in the rest of the service area. Area contributing sanitary sewer flow for existing and future land use conditions would enhance the ability to predict future existing and future peak flow for the design storm conditions. 2-6 CCSD1_SSMP_ DOC