Dam Near Done

Standley Lake Rehabilitation Project in Westminster Will Finish Next Spring

The complete makeover of a Westminster reservoir is nearing completion after more than two years of hard work by the local construction and design team.

The aging infrastructure of Arvada's Standley Lake is being replaced or rehabilitated to improve efficiency and safety. The dam was leaking along the outlet pipes and needed to be redesigned to meet current flood control standards.

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The joint venture partnership of R.E. Monks/ASI RCC has been acting as general contractors on the $31 million Standley Lake Dam Improvements project. The owners are the Cities of Westminster, Thornton, Northglenn and the Farmers Reservoir and Irrigation Co. Engineering work on the project is being performed by CH2M Hill, GEI and Rocky Mountain Consultants.

Improvements to the lake include abandoning the existing outlet works, constructing a new outlet works, building additional downstream earth berms and constructing a new, enlarged spillway. Seven structures make up the new spillway, which entails around two million cu yds of concrete.

"Standley Lake was showing some of the same problems that a lot of the little dams built long ago along the Front Range are," said R.E. Monks's Steve Antony. "The whole thing needed to be upgraded to make it more safe and efficient."

The Standley Lake project is about a $9 million contract for his company.

The sitework component entailed moving more than one million cu yds of compacted fill at the rate of about 15,000 to 20,000 cu yds per day, according to Bill Obenchain, project manager with R.E. Monks. The firm is also putting in about 90,000 cu yds of riprap, which is about 60 percent complete this month.

The project has also involved some very complex microtunneling, including - at 1,200 ft long - the longest continuous-bored 72-in. microtunnel in the United States, according to Antony.

Also complete are the new spillway and seven downstream drop structures.

One of the next big landmark events on the project will be the turnover from the old outlet works to the new one in January 2004.

The contract completion of the project was set for Dec. 2004, but it should be done in April 2004.

"This has been a high-profile rehabilitation project," Antony said, "and we've had a good relationship with our joint venture partner all along. It also helped immensely to have CH2M Hill working with us. Their national reputation for quality design is well deserved."

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