History of the Raw Water Transmission Main
Raw water is supplied by gravity to the water treatment plant by a raw water transmission main that runs from the Lower Flower Creek Reservoir, through Cabinet Heights, and to the water treatment plant.
The original main was a 16-inch wood-stave pipe and was replaced between the mid-1950s and 1980. The upper section of this main, immediately after leaving the lower reservoir, was constructed in 1980 with 24-inch cement-lined ductile iron pipe. The lower section of this main was constructed between the mid-1950s and the mid-1960s with 20-inch asbestos-cement (AC) pipe. The total length of the raw water transmission main is approximately 8,900 feet.
The cement-lined ductile iron portion of this main appears to be in good condition. However, operators have reported that breaks in the AC portion of this line have been difficult to repair due to the brittle nature of AC pipe. A break in this main would leave the City with only 15 hours of water to make the repairs.
According to the American Water Works Association, the average service life for AC pipe is 40 to 60 years. The AC pipe is approximately 50 years old and may be nearing the end of its service life.
Project Overview
The City of Libby will replace AC portion of the raw water transmission main. This replacement could occur with two methods of pipe installation: (1) open trench along or adjacent to the Forest Service road and (2) trenchless pipe bursting through the Cabinet Heights area. The estimated Total Project Cost is $1,888,000. The estimated construction start date for the raw water transmission main replacement is April 2013.
The City of Libby has submitted a funding application to the United States Department of Agriculture – Rural Development. The City may be eligible for up to 45% grant funding for this project with the remaining 55% funding through a low interest loan. This funding is anticipated to be available in late 2012.
Project Area Map