Graham Construction & Management Inc., of Spokane, has been awarded a $10.5 million contract to construct two large maintenance buildings near Wanapum Dam, in central Washington, for the Grant County Public Utilities District.

The dam is on the Columbia River about six miles south of, or downstream from, Vantage, Wash., which is where Interstate 90 crosses the river between Grant and Kittitas counties.

Work on the project is expected to begin this month and to take about a year to complete.

One of the planned structures will be a 48,500-square-foot warehouse for maintaining large pieces of equipment used in the operation of the dam, such as the metal doors that control the water flow, says project manager Tim Steinbrecher of Graham Construction.

The other building will be an 11,700square-foot structure used mostly for maintaining the district's vehicles, he says. As part of that portion of the project, Graham also will construct a covered refueling station for the vehicles, he says.

The buildings that Graham will erect are what are called concrete sandwich panel tilt-up structures, Steinbrecher says, which involve casting the concrete walls before vertically raising them into place. The slabs for the walls will consist of two panels of concrete with insulation in between, he says.

Steinbrecher says the PUD has been using other facilities near the dam to store its equipment and maintain its vehicle fleet.

Bernardo Wills Architects PC, of Spokane, designed the buildings, and the Spokane office of DCI Engineers was contracted to provide structural and civil engineering services for the project, he says.

The Wanapum Dam was completed in 1963, and has 10 150,000 horsepower turbines with a total rated power-generating capacity of 1,038 megawatts. A megawatt of power is enough to serve about 750 homes. It and its reservoir, Lake Wanapum, are named after the Wanapum Indians, who live along a stretch of the river from Vantage south toward Pasco, Wash.