King County Executive Dow Constantine on Feb. 18 announced a change in one of the contractors running the sometimes problematic drilling machines completing the boring needed for the Brightwater sewer project.

In the meantime, one of the two drilling machines stalled for several months is back at work beneath Bothell.

And Brightwater Project Manager Gunars Sreibers said monitoring is continuing near at least two Bothell homes whose owners contend their residences suffered damage from the passage of drilling machines beneath their property.

“While most elements of the Brightwater project are on schedule, I am extremely concerned about construction delays on a remaining two-mile segment of the outflow tunnel and am not confident that the current contractor can complete its construction in a timely manner,” Constantine said in a press release.

“We have an obligation to our ratepayers to pursue other alternatives, and that is what we are doing today.”

Constantine issued a declaration of emergency enabling the county to waive certain legal requirements and hire the West Tunnel contractor Jay Dee, Coluccio and Taisei (JCT) to complete construction of the remaining two miles of the central BT-3 tunnel.

The current Central Tunnel contractor Vinci, Parsons and Frontier-Kemper (VPFK) would remain under contract to complete the eastbound BT-2 tunnel.

The BT-3 tunnel is being built as part of the 13-mile-long Brightwater conveyance system that will carry treated wastewater from the treatment plant to a new outfall in Puget Sound.

JCT is already working on Brightwater’s four-mile-long West Tunnel, which is expected to be completed in the next few weeks.

Construction on the two central tunnels, referred to as BT-2 and BT-3, came to a halt in May 2009, after inspections revealed extensive damage to the rims on two tunnel boring machines.

The damage required complex repairs before additional mining could proceed. The repairs have pushed back the date of tunnel completion, though the Brightwater Treatment Plant itself remains on schedule to open in the fall of 2011.

Using six so-called dewatering wells drilled near Bothell’s Maywood Elementary School, the county reports VPFK successfully repaired the BT-2 machine, nicknamed “Helene,” and tunnel construction resumed Feb. 15, according to Sreibers.

BT-2 has completed about 1.5 miles of the 2.2-mile segment.

According to information released by the county, VPFK estimates that an additional $98 million will be required for them to repair the second damaged machine and complete the BT-3 tunnel. King County staff estimates the project would not be completed until December 2013, a delay Constantine has deemed unacceptable.

Essentially, according to Sreibers, JCT simply will keep drilling after it completes the West Tunnel. The remaining broken boring machine will be removed and JCT will complete the BT-3 tunnel.

The BT-3 machine, nicknamed “Rainier,” began tunneling west from the Brightwater North Kenmore portal, located near the intersection of 80th Avenue Northeast and Northeast 195th Street, in fall 2007.

The machine is currently 330 feet underground and has completed about 1.9 miles of the nearly four-mile segment of tunnel that terminates at the Brightwater Ballinger Way portal, located just west of 19th Avenue Northeast in Shoreline.

King County project managers do not yet know the extent of the costs associated with the delays and repairs, or who will ultimately bear responsibility for any additional costs. Both issues will be subject to negotiation. The King County Council must approve the change in contractor on the BT-3 tunnel.

As for those Bothell homeowners complaining of damage to their residences, Sreibers said officials continue to regularly check equipment monitoring any settling of the ground around the intersection of 90th Avenue Northwest and Northeast 195th Street.

Sreibers said a drilling machine made its way beneath the homes in June 2008. He said the monitors installed last month have detected no problems in the area, adding homeowners are in the process of filing insurance claims with the county.