Barney Dam

Barney Reservoir is located at the headwaters of the North Fork Trask River in Oregon's northern Coast Range, and diverts water eastward into the water supply system for the City of Hillsboro and the Tualatin Valley. Water demands in the valley were creating a need for increased output from the reservoir. Cornforth Consultants was retained by the Cities of Hillsboro, Beaverton, Forest Grove, the Tualatin Valley Water District, and the Clean Water Services (formerly USA) as the Prime consultant to perform studies to raise the dam.

Cornforth Consultants investigated various conceptual options, and recommended an earth and rockfill design that raised the existing dam's height from 72 to 131 feet, and increased the reservoir's storage capacity from 4,000 to 20,000 acre-feet. Preliminary design consisted of an evaluation of seismic hazards in the region (including the great Cascadia Subduction Zone), geologic reconnaissance, 67 exploratory borings, groundwater investigations, geophysical explorations, hydraulic pressure testing, and rock and core materials sources.

Final Design involved engineering analyses to study the raised embankment, static and seismic stability, seepage paths beneath the dam, foundation materials, and rock source materials. In addition, Cornforth Consultants developed the Engineer's construction cost estimate, provided construction sequencing over several seasons, evaluated constructibility issues, provided construction plans and specifications, and coordinated the bidding and awarding of the contract. Quality control and assurance was provided during the 4-year construction period.