Weekday visitors to Mount Rainier National Park might face traffic delays starting today when work begins on rebuilding an embankment along the Nisqually Road.
Park Superintendent Dave Uberuaga said contractors will install a log-crib flood protection structure and reconstruct the eroding roadway embankment six miles east of the Nisqually entrance, the park’s busiest.
During a December 2009 flood, a 110-foot-long by 30-foot-high section of the river bank was undermined and slumped into the Nisqually River. The slide came within 7 feet of the roadway edge at milepost 6.0, about a halfmile from Longmire.
Entrix Inc. of Seattle designed the log-crib structure. It involves cabling together more than 200 horizontally layered logs to 22 vertical anchor logs that will be driven 15 feet into the river bed and held down by large river boulders.
The structure will form the base so crews can rebuild the roadway embankment. It also will provide a roughened face to reduce river flow velocities and the rate of river bank scour.
In addition to protecting the embankment, the structure will mimic natural river banks throughout the park where large standing and downed trees provide protection . Park staff members plan to plant the rebuilt embankment with native trees, shrubs and grasses to eventually re-establish the forest edge lost to the river.
Saybr Construction Inc. of Tacoma, was awarded a nearly $450,000 contract to build the log structure.
The company is to deliver rock to form an access ramp down to the river today, said Eric Walkinshaw, the park’s civil engineer. There likely will be minimal traffic delays as the trucks dump the rock over the edge, he said.
In mid-September, the company will begin delivering the logs, creating periodic traffic delays as the logs are unloaded, Walkinshaw said. “The delivery and unloading of the rocks and logs are the project activities that will most impact traffic,” he said. According to the preliminary schedule, work should be completed by the end of September.
During equipment and log delivery, visitors should anticipate delays of no more than 20 minutes at the work site. Most of the work will take place in the river bed and should not affect visitors driving on the park’s mosttraveled road.
Work will be done primarily Mondays through Thursdays, with some work on Fridays if necessary. No work is scheduled on weekends.