14 Mar 2023

Major Contract Awarded for Fresno Dam Modifications in the US

14 Mar 2023  by   

NW Construction is to begin modifying the Fresno Dam in Montana, US, in April after winning an almost $43.6 million contract from the US Bureau of Reclamation.

Built in 1939 on the Milk River in north-central Montana, the 84-year-old homogenous embankment earth dam has experienced 7-10ft of settlement since construction. USBR evaluated the risk associated with differential settlement-driven cracking and internal erosion and determined that a modification was required. To mitigate the risk, a sand and gravel filter and toe drain system will be added, with an embankment fill overlay and a vertical sand filter trench.

The dam is a compacted earthfill dam with a structural height of 110ft and a crest length of 2070ft. It contains 2,105,000 cubic yards of material. An overflow-type spillway at the north end of the dam provides for a flow of 51,360 cubic feet per second through the concrete-lined channel. The outlet works discharge a maximum of 2,500 cubic feet per second through two 72-inch steel pipe conduits. A conservation storage of 91,746 acre-feet is impounded in Fresno Reservoir.

Project benefits include irrigation and municipal water supply, fish and wildlife enhancement, flood control, and recreation.


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