Earlier this month, MMWD crews conducted a test run of Soulajule Reservoir’s pump station and pipeline. The test—which marked the first time water had been pumped the length of the pipeline in nearly 20 years—is part of a project to replace the 1970s vintage engine driven pumps and ensure the reliability of the Soulajule water supply in the event of drought.
Built in 1979, Soulajule is the newest of MMWD’s seven reservoirs and provides 10,572 acre-feet of storage—about 13 percent of our total reservoir capacity. Constructed in the wake of the 1976-77 drought, Soulajule was designed to provide a reserve supply during such events. The reservoir was most recently tapped for water supply in 1990, the middle of a six-year drought.
Soulajule is tucked into the rolling hills of West Marin, and thus its water must make a bit of a journey before being available for use. Water is first pumped through 3.4 miles of pipeline over a series of hills, including a lift of over 500’. At the end of the pipeline, water spills into a channel and flows into Nicasio Reservoir, from where it can be pumped to the San Geronimo Treatment Plant and then on to customers’ homes and businesses.
Two pumps housed in the Soulajule Pump Station push the water from Soulajule through the pipeline to Nicasio. The pumps, each capable of pumping 6,500 gallons per minute, are powered by two 930-horsepower diesel engines. The aging engines date to the construction of the reservoir and don’t meet current air quality regulations. The district has a temporary permit that allows limited operation, but for the pumps to be used for water supply the engines will need to be replaced.
The test run involved 27 MMWD employees divided into 5 crews along the length of the pipeline. During the test, the pumps were operated separately and simultaneously to move water through the system. Water pressure and flow measurements were collected at the pump station and at several points along the pipeline. The data collected will be used to measure the hydraulics of the pipeline and determine design criteria for the new pumping system.
The test run also served as exercise of the district’s Incident Command System and a training opportunity. Though the pumps are tested from time to time, they haven’t pumped water the length of the pipeline since 1992. Thus the test run had the added benefit of giving a new generation of operators first-hand experience with the system and creating a knowledge base for the future.