Alternative Alignment Figure From Transmission Main Pipe Routing Evaluation

Paxton Transmission Main & Booster Pump Station

Client—City of Kelso, Washington

The City’s Capital Improvement Plan (CIP) identifies several water system projects to help improve and maintain the City’s water system. The City hired Gibbs & Olson to provide design and bid phase services for the Paxton Transmission Main and a new booster pump station facility for the existing Paxton Road Reservoir. These two improvement projects were identified in the City’s CIP.

The Paxton Transmission Main project will eliminate an aging water main and resolve easement encroachment issues that have resulted in residential structures being built over the existing pipeline. Gibbs & Olson evaluated two alignment alternatives to replace the water main. The selected alternative will replace 1,100 feet of existing asbestos cement piping with 1,700 feet of new 16-inch ductile iron piping. The project also includes fittings, valves, water services, fire hydrants, appurtenances and surface restoration.

The new pump booster pump station facility will be constructed on an existing concrete slab at the Paxton Reservoir site. Gibbs & Olson prepared a project report for review and approval by the Washington State Department of Health. The booster pump facility will be a package system designed to increase domestic water service pressure to 15 residences that are currently served directly from the Paxton Road Reservoir with less than 30 psi of water pressure. The package system includes two variable frequency drive pumps (with a capacity of 30 gallons per minute), valves, piping, electrical, control and pump enclosure. A manual transfer switch and generator receptacle will be provided and electrical design and coordination with Cowlitz PUD will be included in the overall design. The project also includes installing 500 feet of 4-inch ductile iron water main to serve the 15 residential connections.

Both projects are currently under construction and expected to be completed July 2023.