Environmental

The purpose of the Coweeman Mitigation Bank project was to reclaim a 46 acre site which was once part of the floodplain surrounding the Coweeman River. To complete the mitigation work in 6 months, multiple crews were required to move over 110,000 cubic yards of material for embankment. A major part of this project was reclaiming one of the tributaries of the river that had become clogged with sediment and was negatively impacting the fish habitat. To optimize the stream for fish life, our crews re-excavated, realigned, and lined the entire stream bed with small aggregate material. Other work on the project included placing two precast box culverts in place of failing CMP culverts where the access road crossed the streams. In order to establish long-term habitat growth, crews constructed a log jam structure at the upstream end of the project and installed over seventy five (18” diameter and greater), logs with rootwads throughout the wetland, with an additional fifty logs driven into the ground throughout the site to function as anchors for the rootwad logs. Once all earthwork, logs placement, and heavy equipment use was complete, the whole site was seeded with grasses native to the wetlands in the area resulting in what now looks like a natural northwest Washington wetland.