Antero Dam and Reservoir Rehabilitation

Project Location: Park County Colorado

Owner: Denver Water

GC: Tezak Heavy Construction

Project Revenue:  $205,000.00

Project Timeline: August 2014-October 2014

Summary:

The Antero Dam is owned by Denver Water and supplies drinking water to the greater Denver metro region almost 140 miles away. This earthen dam was built in 1909 and needed significant repairs.

The Challenge:

The Antero Dam is located on the South Platte River in Park County, Colorado.

Over the decade before our work there, the dam was closed due to fluctuating surface water levels. Denver Water needed to install a toe drain at the bottom of the dam, which was not included in the original design. Dewatering of the toe drain excavation was needed to reduce seepage that would cause instability of the dam.

The remote project location and complex geology consisting of layers of clays, silts and sands made the dewatering a challenge. Griffin employed a combination of installation methods to most efficiently install the dewatering system.

The Solution:

Griffin installed 930 vacuum wellpoints along both sides of toe drain excavation. During installation of the wellpoints, increased soil instability required that we seamlessly switch from the jetting method to a drilling method to complete the installation. Griffin installed four (4) 500 ft. wellpoint systems. Each system produced 200-300 gallons per minute (GPM) for a total of 1200 GPM.

The Griffin Difference:

Griffin worked with all necessary parties to complete a stamped and approved engineering plan prior to starting the dewatering process. Even when the installation method had to be adjusted mid-way through the project, Griffin modified the plan without delay to complete the installation on schedule. Griffin’s engineered dewatering plan allowed for the toe drain to be installed successfully with no delays despite difficult soil conditions.

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