Project Summary (Project No. C2011)
The Eagleridge neighborhood, located within the Lake Whatcom Water and Sewer District’s service area, is a subdivision of 64 single family residential homes situated on the north shore of Lake Whatcom just outside of Bellingham city limits. The District provides water service to Eagleridge residents via an intertie with the City of Bellingham’s water system, and sewer service via a series of gravity sewer mains that flow to the District’s sewage conveyance infrastructure located in Northshore Road. The neighborhood’s water and sewer infrastructure was constructed by the private developer of the subdivision in 1988 and dedicated to the District.
The Eagleridge Water System is classified as a Group A water system regulated by the Washington State Department of Health (DOH) and serves the entire Eagleridge neighborhood, as well as six additional homes located immediately north of Donald Avenue (70 total homes). The DOH water system identification number is 08118. When the water system was originally designed and constructed, the City’s water pressure at the location of the connection (intertie) between the two systems was not sufficient to serve the Eagleridge neighborhood. As a result, a booster pump station was constructed at the location of the intertie (2029 Northshore Road) that consists of a CMU (concrete masonry unit) building that houses three pumps for domestic (general) water service, two pumps for fire suppression, pump controls, and an auxiliary diesel generator (to ensure continuous water service throughout power outages).
At some point between infrastructure construction in 1988 and 2016, the City increased the water pressure in the service area the feeds the Eagleridge water system. During this same timeframe, the District began planning for replacement of the pump control system, which was approaching the end of its useful life. Based on this, a project was identified in the District’s most recent Water System Comprehensive Plan update (approved by DOH in 2018) to study whether part or all of the pump station could be decommissioned. In 2020, the District requested that Wilson Engineering perform a detailed hydraulic analysis to determine if the City’s system pressure on their side of the intertie is sufficient to meet District needs and regulatory requirements in Eagleridge. This analysis is summarized in a technical memorandum “Hydraulic Analysis of the Eagleridge Water System” that can be downloaded from the Project Library below.
Wilson Engineering’s hydraulic analysis concluded that the domestic pumps are no longer necessary and can be removed from service, with the City’s pressure being sufficient to meet regulatory requirements for the domestic demands of the Eagleridge system. However, the fire pumps must remain, as the analysis found that the City pressures were not sufficient to deliver the minimum required flow and pressure in a fire flow scenario. The hydraulic analysis did, however, find that the existing fire pumps are oversized, and concluded that the existing pump control valves for the fire pumps should be modified to add a pressure reducing function.
Based upon the hydraulic analysis, the District has submitted a project proposal to DOH (see Project Library below) to retrofit the control valves of the existing fire pumps to reduce and better regulate the discharge pressure, and to remove the domestic pumps and associated control panel from service.
The primary project benefit will be near- and long-term cost savings realized through not replacing the existing three domestic pumps when they reach the end of their service life, which is estimated at a replacement cost of $275,000, as well as the ongoing cost to operate the domestic pumps (electricity to operate and routine maintenance), which is estimated at $50,000 over the next 20 years.
- Task 1—Hydraulic Analysis/Conversion Design—Complete (August 2020-July 2021)
- Task 2—DOH Project Review—underway (August-September 2021)
- Task 3—Construction—to be initiated following DOH approval (complete December 2021)
The total project cost is estimated to be $33,000.
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Other Reference Materials
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