Pipestem Dam given lower safety rating

The Pipestem Dam received the lowest safety rating of the four North Dakota dams owned by the U.S. Army Corps of Engineers in the newly released Dam Safety Action Classification.

A press release dated March 2 defined the DSAC rating system and listed Pipestem Dam at a level 3 while Garrison, Bowman Haley and Snake Creek, the three other dams in North Dakota owned by the Corps of Engineers, received level 4 ratings.

“The DSAC ratings are a description of relative risk,” said Paul Johnston, public affairs officer for the Omaha District of the Corps of Engineers. “They go from a five, which is no risk, to a one that means it needs immediate attention.”

Johnston said a 3 rating indicates there is no immediate risk but the situation warrants extra monitoring.

“We’ve been monitoring there for some time,” he said. “The conditions aren’t new, but the rating system is.”

Bob Martin, manager of the Pipestem Dam and Jamestown Reservoir, agrees.

“We will continue with several different monitors that measure ground water pressure and ground water drainage,” he said. “As the water rises monitoring will be performed more frequently.”

Martin said monitoring at Pipestem involves wells of various depths placed around the dam.

“There are 45 pipes drilled down into the soil above and below the dam to monitor the pressure,” he said. “We’ve been monitoring these since the dam was built 30 years ago but they added additional monitors after 1997.

The high water during the spring of 1997 also caused other problems.

“We had some seepage around the right abutment in 1997,” Martin said. “We pumped water from that area downstream and in 1998 put in a collector system.”

Martin likened the collector system to placing drain tile around a home. It allows the water to be pumped from the area keeping the soil more dry and stable.

Both Martin and Johnston said the DSAC rating will draw attention to Pipestem Dam when it comes to funding.

“The ranks the corps gives the dams make sure that the necessary resources are directed at the dams that need it,” Johnston said.

Sun reporter Keith Norman can be reached at (701) 952-8452 or by e-mail at knorman@jamestownsun.com

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