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Exhibit 7. Biofilm Control Variables • Dead -end mains. • A comprehensive finished water storage facility program, including design, monitoring, maintenance and inspection efforts. • Comprehensive water main flushing programs. • Unidirectional flushing (UDF) programs. • Potential for water - hammer caused by hydrant exercising. • Potential for low- pressure transients. • Impacts of pipe materials on drinking water quality. • Table -top distribution system water quality emergency response training. Exhibit 1 shows primary and secondary variables thatcan lead to biofilm growth within a distribution system. The participating utility's practices that impacted these primary and secondary variables were systematically evaluated to determine if biofilm growth is likely a very significant or less significant concern. The findings of this evaluation helped one of the participating utilities to justify the lack of need for an aggres- sive, system -wide unidirectional flushing program. This saved significant expenditures on flushing, so the utility could focus on more pressing needs. The project's final report, published by AwwaRF, summarizes project activities and findings, and provides guidance on conducting distribution system audits and preparing utility- specific DSOPs. It contains examples of programs and practices utilities may develop as part of implementing a DSOP such as guidelines for investigating water hammer, and a comprehen- sive management program for finished water storage facilities. Developing a Usable and Integral Tool The DSOP process can be used to optimize all distribution system functions, or to target a few specific distribution system programs for water quality improvements. The DSOP typically includes the following topics: • Water quality goals and monitoring, • Operations management, • Maintenance management, • Facilities planning and engineering, • Construction practices and inspection, • Training, • Customer relations and communication, and • Data integration for water quality management. The focus of each topic is to determine the impact of utility practices on distribution system water quality and to provide a framework for integrating water quality considerations into utility planning processes and programs. The DSOP could be as simple as a three -ring binder with tabbed sections or alternatively, the DSOP could be an electronic document available to utility staff via an intranet. The DSOP should be considered a living document that is continually updated as new information be- comes available or as the utility has resources to further develop related programs and practices. Many of the utilities that have developed DSOPs have commented on how effective the process has been at bringing water quality issues to the forefront of their daily activities, within and across utility boundaries. According to Jeff Swertfeger, senior chemist at the Greater Cincinnati Water Works, "this process was highly successful in developing an internal culture that values water quality and has a realization that every aspectfrom preventive maintenance, to laboratory testing, to main repairs, can affect water quality." The DSOP process has inspired clients to work toward improving documentation, explaining the rationale for their activities (or lack thereof), and estab- lishing proactive responses to a variety of water quality conditions. L Tailored Collaboration Development of Distribution System Water Quality Optimization Plans Melinda J. Friedman, P.E., is HOR's drinking water quality program manager. She can be reached in the Bellevue, Wash., office at (425) 450 -6393 or melindo.friedman@hdrinc.com. References AWWA (American Water Works Association). 2004 G200 -04. AWWA Standard for Distribution Systems Operation and Management. Denver, Colo.: AWWA. Friedman, Melinda; G. Kirmeyer; G. Pierson; S. Harrison; K. Martel; A. Sandvig; A. Hanson. 2005. Development of Distribution System Water Quality Optimization Plans. Denver, Colo.: AwwaRF and AWWA.