The Kennewick Irrigation District is moving forward on the first part of the estimated $17.2 million project to bring water to Red Mountain.
The district's board unanimously approved going to bid to prepare the future site of the booster pumps and station for the project, meant to bring water from the Yakima River to prime wine grape-growing land in the Red Mountain American Viticultural Area between Richland and Benton City.
Paul Cross from RH2 Engineering of Richland told the KID board Tuesday that geologists are concerned about the strength of the basalt in that area, which could affect the stability of the slope.
If a retaining wall needs to be built, that could add about $2.2 million to the project cost, he said, and the only way to know for sure is to begin the excavation.
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"It's wise to find this out early in the game so that we know where we are at later in the game," said board President Gene Huffman.
Most of the 30,000 cubic yards of rock to be excavated will be removed as part of this phase, Cross said. Some of that rock will be used for access roads.
This phase will cost about $800,000 to $1 million, and is included in the overall $17.2 million project estimate, Cross said.
Landowners will pay for the project using a local improvement district. KID is one of the landowners, with about 620 acres within the boundaries.
The excavation work is scheduled to start around April 1 and be completed by June 7. It's important to be done by then because some of the work in the next phase has to be done in the Yakima River, and the river work only can be done between July 15 and Sept. 15 because of fish, Cross said.
Water will be drawn from the river at a new intake station and delivered through 42-inch steel pipes to a pump tower. Two reservoirs also will be built to hold about 400,000 and 100,000 gallons, respectively, Cross said.
The water will be used to irrigate about 1,785 acres on Red Mountain, allowing more wine grapes to be planted in the area. Cross said the water will require some treatment because it is too dirty to meet the needs of drip irrigation for wine grapes.
Water may be available by June 2014, Cross said. That may not be early enough for planting that year. The previous estimate was spring 2015.
-- Kristi Pihl: 582-1512; firstname.lastname@example.org