2006 Water Comprehensive Plan - City of Bellevue

Discussion:The Utility’s goal is to provide system static pressure of at least 30 psi, measured at the servicemeter, except during fire flow and other emergency conditions which may cause lower systempressures. The Utility has investigated the level of service provided at 30 psi and determined itprovides adequate pressure to meet normal residential needs. Property owners, however, mayinstall private booster pumps to achieve higher pressures, if they choose. Customer complaintsof low water pressure are often caused by corroded internal plumbing which restricts flowvolume, rather than system pressure. In such cases, increased system pressure would make verylittle difference in actual service provided.Where modification of utility lines would significantly improve flow, such as replacement ofsingle service lines that serve more than one home with adequate internal plumbing, the Utilityshould make such modification.Service ReliabilityThe Utility shall invest resources as necessary to construct, maintain and renew watersystem infrastructure and equipment such that Utility customers are provided consistent,reliable service. Wherever practicable, the distribution system shall have 100 percentoperational redundancy. Connections between adjacent water distribution or supplysystems should be encouraged to improve reliability and reduce vulnerability to loss ofwater service.Discussion:The Utility shall provide sufficient maintenance and use appropriate operation practices to keepthe water system infrastructure in good working order. Where operation and maintenanceprocedures are not sufficient or cost effective, capital projects shall be scheduled and funded toreplace or rehabilitate infrastructure facilities.Wherever possible, the Utility shall anticipate system interruptions and shall design and operatethe system to minimize the impact of such interruptions to customers. For that reason:• No more than 250 customers should generally be supplied water from a single source.• Onsite or portable emergency power generation should be provided at all pump stations.• To the extent practicable, equipment redundancy should be provided (i.e., providefacilities to pump maximum demand flow rates, even with one pump out of service.)• Where service reliability can be increased, interties with neighboring jurisdictions shouldbe considered and interties between regional water suppliers should be encouraged.2-4