Water Pipelines: Tackling Toxics

by Steven Eng, (M.ASCE), Village Safe Water Engineer; Alaska Department of Environmental Conservation, Juneau, Alaska,

Serial Information: Civil Engineering—ASCE, 1993, Vol. 63, Issue 5, Pg. 77-78

Document Type: Feature article


In the spring of 1988, residents of Girwood, Alaska contacted the state's environmental agency to complain of foul-tasting drinking water. While most complaints came after a four-day power outage, some residents said that the taste and odor problems had been ongoing, to some extent for many years. Because water samples showed levels of perchloroethylene (PCE) were high, the Alaska Department of Environmental Conservation (DEC) issued a health advisory. DEC conducted an intensive sampling of the entire Alyeska Basin subdivision in order to isolate the source of the contamination. Workers took 25 water samples for the analysis of volatile organic compounds using an EPA sampling method. They took many samples at dead-end lines, since the highest contaminant concentrations would be expected there, and on high- and low-pressure sides of a booster pump station. DEC chose to ask the owner to install blow-off or flushing valves at the ends of five dead-end lines. Workers installed a flushing valve consisting of a standard copper service line with saddle corporation stop and valve box. On the water line that serviced the area, crews continuously bled the line at 2-3 gpm for a week, then sampled the water. The PCE had been lowered.

Subject Headings: Water sampling | Valves | Water pipelines | Toxicity | Environmental issues | Power outage | Water conservation | PCE | Alaska | United States

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