Machine moves 100 trucks of dirt a day

BOTHELL — No need for picks and shovels when you’ve got this 2,000-ton baby doing the hardest work.

“Luminita,” more than $8 million of Canadian tunneling might, is in Bothell and pointed east for a laser-guided date with Maltby.

Between now and November 2008, the machine will carve a three-mile-long tunnel to King County’s future Brightwater sewage treatment plant.

“The machine does most of the hard and heavy labor,” tunnel project manager John Kennedy said. Carbide-tipped steel grinders will carve a roughly 20-foot-diameter tunnel between 80 feet and 280 feet underground.

At precisely noon Monday, a bottle of Cook’s extra dry champagne ceremoniously zipped down a tether into an 80-foot-deep hole, smashing itself into Luminita.

Three other tunneling machines — Helene, Rainier and one to be named later — will do their share along a 13-mile path between the treatment plant and Puget Sound, where treated sewage will be dumped. These are the same kinds of machines used to dig tunnels for light rail in King County.

Luminita is expected to start chewing through the soil later this week.

Tunnel construction is to cost about $450 million and is expected to finish by fall 2010. All told, the tunnels and treatment plant cost about $1.7 billion.

Luminita, named after an engineer working for the tunneling contractor, doesn’t run on auto-pilot. A driver inside the machine monitors two computer screens, dials and switches.

On average each day, the machine will tunnel through about 70 feet of dirt — mostly sand, clay and some peat, Kennedy said. Concrete lining is built in rings in the tunnel as the machine advances.

In all, crews of 10 to 15 people are needed deep underground to lay rails behind the tunneling machine. They operate a small diesel-powered train that rides the rails, carrying tons of dirt out of the tunnel.

With each advance of the tunneling machine, crews lay more conduit for electricity for lights. They also extend ventilation ducts so powerful fans can pump out diesel exhaust from the train and bring fresh air for crews.

Tunneling is scheduled about 20 hours a day on weekdays with crews underground in 10-hour shifts.

“They eat their lunch down there,” Kennedy said. “For me, it’s just like walking down a hallway. Some people get claustrophobic.”

Above ground, a crane hoists away full carts of dirt and each day fill about 100 truckloads bound for Topsoils Northwest, a company that sells soil, on Highway 9 in Snohomish.

The project is a major milestone for the largest wastewater project in King County’s history, King County Council chairman Larry Gossett said.

Once the tunnels are dug, four pipes will be laid inside: Two pipes with diameters of 66 inches and 48 inches to carry dirty wastewater to the treatment plant; a 7-foot-diameter pipe to carry treated sewage to Puget Sound; and a 27-inch-diameter pipe to carry treated water suitable for use as irrigation.

Without the treatment plant or the pipeline tunnels, new homes and businesses in south Snohomish and North King counties would have nowhere to flush.

Snohomish County is receiving about $70 million in payments towards park, road and stream projects to offset impacts from the treatment plant. The county has received $33.5 million so far.

Reporter Jeff Switzer: 425-339-3452 or

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