Columbia Water Supply Project

CLIENT City of Pasco

Location Pasco, WA

Shannon & Wilson provided construction observation and review services for the new Columbia River Intake in West Pasco.

The work is part of a $7.5 million project for the west Pasco water treatment plant and includes two 250-hoursepower pumps, each with a capacity of six million gallons a day. Shannon & Wilson provided construction observation of shoring (i.e., secant pile wall), microtunneling, and dewatering elements.

The project included: 

  • An approximately 85-foot-deep secant pile shaft which will house 25 1/2 -foot-diameter wet well upon completion. The secant pile wall specifications require minimum 30-inch-diameter individual shafts overlapping such that a minimum eight-inch-thick wall is achieved within the overlap sections.
  • A 48-inch diameter, approximately 227-foot-long intake pipeline extending beneath the Columbia River to the wet well.
  • A screen structure over the intake pipeline within the Columbia River.
  • A control building constructed over the secant pile shaft/wet well footprint.

Scott Garbs

Andrew Tangsombatvisit
Geotechnical Staff

Clinton Wilson
Senior Associate

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