Fish passage was being blocked through three culverts along Ostrich Creek due to high velocity conditions and the presence of large outfall drops. This project involved the demolition of the existing culverts, grading, new stream crossing structures, and stream restoration. Crossing structures were selected based on a cost-benefit analysis. Two of the new stream crossings consisted of bridges to optimize the ecological benefits realized by the project. The third crossing consisted of a 146-foot long 3-sided box culvert with a 17-foot clear span. The crossing design followed the stream simulation method according to the 2013 WDFW Water Crossing Design Guidelines. Stream restoration provided riparian plantings and large woody materials (LWM) placed in the new streambed to enhance conditions for salmonid rearing. This project was funded using a Public Works Trust Fund.
Parametrix completed hydrology studies, engineering design, environmental permitting, and engineering services during construction. In addition to barrier removal, the project alleviated periodic flooding occurring at two of the culvert locations due to the undersized culvert pipes. Permitting was driven predominantly by in-water work requirements and the project’s status as a Fish Habitat Enhancement project. Permits included concurrence with the Governor’s Executive Order 05-05 (cultural resources), Nationwide Permit 27 for Aquatic Habitat Restoration through the USACE and a Hydraulic Project Approval.