SEATTLE, WA — Otak, working as a sub-consultant to HNTB Corporation, is providing design and engineering services on a project for the Washington State Department of Transportation (WSDOT) to renovate or replace up to 450 culverts and restore safe fish passages throughout the state’s Northwest Region. The current goal is to complete 450 culverts in two phases, the first phase is to complete Preliminary Hydraulic Designs (PHDs) for all the culverts within the next three years, and to complete the final designs and construction within the next 10 years.

The Otak team is being led by Russ Gaston, Principal and Project Manager. Otak’s Stream Design Engineers are playing a role in the hydrologic design that must meet the project’s criteria and be in compliance with state and federal regulations. In addition, Otak is applying its experience with MicroStation, the CAD software WSDOT uses.

Otak has initiated scoping on to complete PHDs for 10 of the fish passage culverts, to have them completed within three months after WSDOT provides surveys of each location. The team will determine if a more efficiently designed culvert, a bridge, or natural streaming will be the best solution at each location. The culverts, generally placed under roadways, need to allow a flow of water that is not too fast or too shallow or results in a waterfall at either end.

“The job is not simply to replace culverts but to look at alternatives such as avoiding passage near a road, using bridges, or adding water passages that mimic natural streams,” Gaston said. Otak’s Stream Design Engineers are conducting a preliminary hydrologic design report to examine the movement of water and overall watershed sustainability to determine the best way forward for each culvert.