"Scouring" water mains helps maintain water quality by removing sediment buildup
The Marin Municipal Water District began its annual water main flushing program to help maintain water quality on January 9 in Fairfax. The 2013 program also includes the San Geronimo Valley, San Anselmo and Ross. Flushing will occur most Wednesdays through March 13 between approximately 8:00 a.m. and 2:30 p.m. Water main flushing is recommended by the California Department of Public Health to remove sediment buildup in transmission and distribution pipelines because the sediment can impair water quality.
Each year MMWD “flushes” approximately 20 percent of its water mains. To flush a water main, selected hydrants along a section of the main are opened. The high velocity of the released water scours the main, removing any collected sediment. After the chloramine is removed by dechlorination tablets, the water is released onto the street and enters the storm drain system. Flushing averages about 15 minutes for each hydrant.
In the past, MMWD performed flushing at night to minimize the impact on residents. In 2011 the district began flushing the pipes during the day to save the overtime costs of sending crews out at night. This year the district will again be flushing the mains in the daytime to reduce costs without compromising water quality.
In addition to water in the street, during flushing customers may notice effects on their own plumbing, including slight pressure drops, air in the lines or “dirty” water. If customers notice these effects, MMWD recommends restricting water use during flushing and then running the cold water for a short time afterward to remove any loosened sediment in the pipeline. Be assured the temporary discoloration is not a health concern.
2013 Water Main Flushing Schedule
Jan. 9: Western Fairfax
Jan. 16: Southeastern Fairfax; San Geronimo Valley Floor (Lagunitas/Forrest Knolls); Upper Woodacre
Jan. 30: Town of Woodacre; Cascade and Scenic areas of Fairfax; Oak Avenue in San Anselmo
Feb. 6: Sir Francis Drake Boulevard from Butterfield to "the Hub"
Feb. 13: The Alameda, Oak Springs and Fawn Drive in San Anselmo; Sky Oaks area of Fairfax
Feb. 27: Sleepy Hollow; Scenic Avenue in San Anselmo
Mar. 6: Downtown Ross and San Anselmo
Mar. 13: Oak Manor and top of Fairfax Manor in Fairfax; Sir Francis Drake Boulevard in Ross; Laurel Grove in San Anselmo/Ross