Sink Holes
Brightwater TREATMENT SYSTEM   -   King and Snohomish Counties, Washington
Seattle Times

For the second time during construction of the Brightwater sewage-treatment plant,
 a large sinkhole has opened up above the 13-mile tunnel being mined to carry treated waste to Puget Sound.

March, 2011; In Bothell a new hole, up to 30 feet wide and more than 15 feet deep,
opened up in a wooded area in Bothell. It was discovered this month after
a neighbor reported to the city that a tree was leaning against a cable-TV line.

The treatment plant is almost complete, and all but 1.5 miles of the 13-mile tunnel are finished.
The sewage-treatment plant and pipelines are supposed to be fully operational by mid-2012.

A 30-foot-wide, 15-foot-deep sinkhole obliterated the driveway of a Kenmore resident
after a Brightwater tunnel-boring machine passed below the house in March 2009.
 Officials said the machine excavated too much sandy soil.