Jun 22 2014

EBMUD Replaces 10 Miles of Pipe Each Year

The East Bay Municipal Utility District (EBMUD) water distribution system includes about 4,100 miles of pipe with the average age being 53-years-old. According to Director of EngineeringĀ  Xavier Irias, “50 years is not old for a pipe. It’s just middle-aged. Some pipes last for 100 years. Ripping out everything and starting over doesn’t make sense.”

The infrastructure renewal program is mostly based on leak rate, not age of pipe. Cast iron pipes from the 1930’s, 1940’s and 1950’s leak more than the very thick-walled cast iron pipes from the late 1800’s. Asbestos cement pipe is more age sensitive than cast iron pipe; over time calcium leaches out of asbestos cement pipe, accelerating its deterioration. Slip-lining is a possible rehabilitation option for the asbestos cement pipe when the hydraulics allow for a reduction in pipe diameter.

The single most important cause of pipe failure is unstable soil; for example, in filled land or land slide areas. Each year EBMUD replaces less than .2% of the total network, a replacement cycle of 400 years. Of the current 10 miles per year, one to two miles will be replaced using horizontal directional drilling in place of open trench installation, but only inĀ flat residential neighborhoods with straight pipe alignments and minimal utility conflicts. Over the coming decades the goal is to increase the annual replacement rate to 40 miles of pipe per year, or 1% of the pipe system.

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