2006 Water Comprehensive Plan - City of Bellevue

appropriate, PRV records also include remarks of special interest from an operational standpoint,such as whether a valve is equipped with some special modification to provide additionalservices for reducing pressure. In many locations, ancillary equipment has been provided to thePRVs so that the pressure setting can be controlled from the water system operations controlcenter. These modifications allow the operator to remotely adjust the valve and control the flowfrom the zone of supply.Pump StationsElevations within the Bellevue water service area range between 25 and 1450 feet. The supplyhydraulic grade line at the SPU supply connections is generally high enough to serve manyadjacent service areas; thus, several of the connections are equipped with PRVs, as discussedpreviously. During high demand periods, however, the supply gradient falls, and pumping isrequired at some connections. The operation of the pump stations is discussed later in thischapter under "Hydraulic Operations." In addition to those pump stations associated with thesupply connections, a number of areas are at elevations that require pumping of all waterdelivered to the service area, such as the South Bellevue operating area.The pumping stations are listed in Table 6-5. The table indicates the location of pump stations,the zone from which they are supplied, the zone to which they pump, the number of pumpswithin each pump station, the elevation of the station, and some characteristic data about thepumps within the station. The table also includes the type of control system used at the pumpstation. Local automatic control indicates that the pumps turn on and off in response to apressure sensor at the station or in the system near the station. Telemetry control indicates thaton and off switching is done at the Bellevue Service Center. The status report indicates whetherthere is feedback to the operations office indicating that a pump is on, off, ready to come on, orthat some failure is occurring.StorageStorage facilities are located throughout Bellevue’s water system. The storage provides anequalizing effect to meet varying system demands throughout the day, water to meet firedemands, and water for emergencies caused by supply outage or contingency. All of Bellevue’swater storage facilities are all covered, ground-level reservoirs or standpipes.Table 6-6 lists the storage facilities within the Bellevue water system. The table indicates thevolume of storage in million gallons (MG) and the maximum and minimum water levels foreach reservoir within the system. Also shown are the primary zones to which each reservoirsupplies water. The City continuously records the water level of each reservoir at the wateroperations control center.6-16