By Dennis Box

The Courier-Herald

Digging holes in the dirt has come a long way in Bonney Lake - about 600 feet.

Trenchless Construction drilled a 600-foot long hole for a water main beneath the flume that flows into Lake Tapps at Inlet Island along 218th Avenue East.

The hole is 60 feet beneath the road and 16 feet below the flume.

The drilling was part of a larger water main job that is bringing Tacoma Water to the east side of the city's water service area. DDJ Construction Company of Ravensdale is building the water main.

The main line will run along 214th and 218th Avenue East, beginning near Kelly Lake Road and extending north to about 34th Street East.

A decision was made by Pierce County officials to run the waterline below the flume rather than attached it to the bridge.

"At the time the bridge was constructed there would have been knockouts on it for the waterline to be attached," Public Works Director Dan Grigsby said. "And the weight of the line would have needed to be considered."

The drilling company drilled under the canal first with a 6-inch drill.

"Then we drilled a 24-inch hole," foreman Mark Handy said. "The last drilling was 30 inch. Then we ran a 20-inch pipe through."

According to Handy the pipe is made of polyethylene, is bendable and provides a 16-inch inside diameter main for water.

"When we drill the hole we have electronic sensors inside the bits that tell us exactly where the bit is and if it is overheating," Handy said. "A radio frequency is sent that tells us the depth and angle."

Once the pipe is drawn though the hole, Bentonite is pumped into the opening. Bentonite is a ground-up clay compound that keeps the sides of the hole from caving in around the pipeline.

The water line was in place under the flume Thursday and the construction crew was finishing the last few details of the job.

"This is a good job," drilling locator Jim Perry said. "We get paid for playing in the dirt."

Grigsby said the project is ahead of schedule and water could be running through the pipeline by the end of August.

Once DDJ completes the north-south pipeline, it will begin work on a water line running from 96th street at the peaking storage site and tying in at Kelly Road.

The council passed a resolution July 21 approving the DDJ contract for the peaking storage water main project.

"It saves money because DDJ doesn't have to break down their equipment," Grigsby said. "They can just move over and start working on the other pipeline."

The contract for the north-south pipeline was $2.4 million. The peaking storage water main will run $736,248 with an authorization of up to another $147,200 for contingencies, construction management and inspections.

Dennis Box can be reached at dbox@courierherald.com.