Twanoh State Park

Mason County, Washington

HWA provided geotechnical services for the design of a new sewer system for Twanoh State Park.

The work included a new collection system throughout the park, a new pump station and force main to transport sewage to the septic tanks, and new septic tanks. Our work included assessing the application rate of the existing drain field. Borings and test pits were performed to characterize soil and ground water conditions in the park. Construction of the new sewage system was completed in 2006.