Golden Gardens Drive Northwest Washout Repair Project
Revised August 26, 2009
This project is complete. Golden Gardens Drive Northwest officially opened back up for public use January 16, 2009. Final touches to the roadway including bicycle markings and signage were added this past March. Also this spring, completing the work in one day, the Seattle Department of Transportation further improved the roadway by paving the area north of the washout project boundaries.
Thank you for your patience in the fall and winter of 2008 as crews built the soldier pile retaining wall, installed the new guardrail, completed revegetation along the hillside, placed jute matting and wood chips, and paved the damaged section of roadway. Golden Gardens Drive Northwest was shut down in December of 2007 after record-breaking rainfall saturated the region and caused a section of the roadway to collapse. In the case of emergency damage to roadways we work to respond as quickly as possible to ensure public safety. City crews responded right away to place emergency control measures including mesh over all exposed ravine soils to secure them (using two layers of bio-degradable erosion prevention fabric); tree-chip mulch at the base of the hill to protect the area used by park goers; and sand bags to prevent additional downstream saturation by channeling water away from the damaged area.
Concurrent with the stabilization of the eroded areas, the City worked to identify funding for the emergency repair while a team of geotechnical experts began to assess the collapsed area to determine appropriate corrective measures necessary to restore the roadway and mitigate future washouts.
The construction work repaired the section of Golden Gardens Drive Northwest that was washed out. A geotechnical study completed in 2008 determined that the collapse of Golden Gardens Drive was initiated by an abnormally large volume of stormwater eroding the steep slope supporting the roadway. The City mitigated this problem by replacing an existing inlet and catch basin and re-building the water pipes near the east entrance of the park. As part of the geotechnical study, the report provided recommendations for reconstruction of the roadway and additional data to better inform re-construction decisions.
Golden Gardens Drive NW has long been utilized by both cars and bicycles. Based on information from traffic studies the roadway has not been shown to be high risk. Data from the Seattle Police Department shows that in the 10 years between January 1998 and January 2008 there were no recorded pedestrian/vehicle accidents or bicycle/vehicle accidents between View Ave. NW and Seaview Ave. NW. Of the 41 vehicle/vehicle or vehicle/object accidents recorded in that decade, there were no fatalities and eight recorded injuries. Safety for all modes of transportation is the goal so SDOT is adding elements such as road markings and improved signage to remind drivers that Golden Gardens Drive is a dual purpose road and used by cyclists as well.