May 15, 2007
On May 15, crews used ground penetrating radar to look for voids underneath the road after a sinkhole in the project area continued to settle.
The radar looked approximately 12 feet under US 2. There are many variables when looking for voids. A void can be filled with water, gravel, dirt or air. It can be shallow or deep, large or small.
Once the radar work was complete, the data was sent to geotechnical engineers. The engineers analyzed the data and determined that there was no reason to believe large, new sink holes will appear in the area.
The temporary soil nail wall has ensured that the road is safe for travel and can remain open to the general traveling public. Drivers are reminded that a 35 mph speed limit is enforced through the area.
June 21, 2007
WSDOT maintenance crews discovered a small sinkhole in the same location where one developed in April. Although this hole was substantially smaller, crews immediately closed the westbound lane and began alternating traffic in the eastbound lane.
Crews decided to excavate around the hole and discovered that water was still seeping into the ground under the road, causing the earth to settle.
Crews removed saturated soil and any other unsuitable material and replaced it with gravel. Then they compacted the gravel and paved over the hole. They reopened the westbound lane to traffic just before 8 p.m. on June 21.