While traffic is still diverted around the closure of 10th Street and Koosbay Boulevard in Coos Bay, the ramming of the replacement pipe has been completed and the city is expecting to re-open the street sometime next week.

Tenth Street was closed on March 22, at the intersection of Hemlock Avenue, and Koosbay Boulevard has been closed at the intersection with 10th Street, due to ongoing sinkholes and water problems under the street.

Following heavy rainstorms in January, stormwater backed up onto private property and the city quickly began a ramming project to replace the deteriorated drainage pipe below 10th Street with another 36-inch pipe to avoid further damage to home owners in the area. An engineer and contracting crew began to ram sections of the pipe below the street in a project that was estimated to take only a week, and has now lasted several weeks due to poor weather and unforeseen problems.

A 12-foot deep and 12-foot wide sinkhole formed in early March and was quickly patched by city workers, but the sinkhole reformed again on Friday, March 17, and part of the intersection at Koosbay Boulevard and 10th Street was closed. City officials decided the street was vulnerable to significant instability until the deteriorated pipe was completely filled with a slurry of concrete and closed 10th Street and Koosbay Boulevard until further notice.

According to Coos Bay Community Services Director Jim Hossley, the two streets could be opened to through traffic again sometime next week, although the exact day is not known at this time.

The streets will re-open following the completion of the entire ramming project, which is entering the final phase now, Hossley said. The crew will now clean out the new pipe that was shoved through the hill below 10th Street from the dirt and debris that has accumulated in the far end of the pipe, then a hose will be run through the old pipe to verify blockages and fill it with a slurry of concrete.

“Unfortunately I don't know the exact timing on when we'll start the process, but once we do it should only be a one or two day project,” Hossley said.

While the sinkholes formed during the long ramming process, Hossley said he doesn't believe the sinkholes were directly caused by vibrations of shoving the new 36-inch pipe below the street. The sinkholes collapsed the street surface but revealed sections of the old deteriorated pipe, leading the city and the contractor to conclude holes in the pipe caused the soil to be eroded by water moving down through rips in the pipe. The surface collapsed once there was no ground to support its weight.

Filling the entire pipe with concrete will keep more sinkholes forming below the street from deteriorated soil between the surface and the deteriorated pipe, Hossley said.

Although the streets will remain closed until the old pipe is filled, the city plans to re-open 10th Street and Koosbay Boulevard before filling in and fixing the latest sinkhole at the corner of Koosbay.

“If once they finish doing the filling the pipe, the weather is good, we'll be able to get in and fix the sinkhole. It will just depend on the weather,” he said.

On Monday, officials from the Federal Emergency Management Agency will tour the city and assess the various utility and street damage caused by the heavy stormwater and flooding during the January storms. Hossley said he hopes the city will qualify for some emergency funding assistance, as the 10th Street repairs and other damages may cost the city in excess of $200,000.