WOODINVILLE, Wash. -- There isn't a nice way of saying this: sewage is a dirty, smelly business. But King County's new, nearly $2 billion sewage treatment system was supposed to be different.

The county promised that Brightwater would protect the public and the environment. But a KOMO Problem Solver investigation has uncovered evidence that King County may be breaking that promise.

Video taken of Horse Creek in Bothell shows how the small stream looked and sounded as gray, silty matter bubbled up through the stream bed, after construction of a Brightwater sewage tunnel hit a snag last August.

There is also cell phone video shot by a worker a week earlier at the construction site where that tunnel starts. A waste tank overflowed, spilling a muddy mix everywhere.

They are two separate incidents, but insiders tell the us that both are evidence King County's construction here is putting the environment at risk.

"It was almost a daily occurrence," says one insider.

Another worker said, "and we're talking thousands and thousands and thousands of gallons of this stuff."

Both asked us to keep their identities hidden.

The North Kenmore Portal is one of seven construction projects in the Brightwater treatment system. Contractor Vinci/Parsons/Frontier-Kemper is constructing two massive underground tunnels to carry sewage to and from the treatment plant.

King County oversees the entire project.

"We are proud of the fact of how we're performing," said Brightwater Project Manager Gunars Sreibers.

But our insiders say the county's inspectors either aren't seeing, or aren't reporting problems.

"You have one inspector per shift," said our second insider, "and if he's down in the tunnel, how's he going to know what's happening upstairs?"

That may be what happened at Horse Creek.

Sreibers said he knew the contractor was having trouble with maintenance in the tunnel. Documents obtained by the Problem Solvers show monitoring wells detected huge spikes in pressure.

Asked whether those spikes should be checked, Sreibers responded, "there's no question that we should be, well we do, we monitor these wells continuously."

But for two days, contractors ignored those pressure spikes while air from the tunnel exploded upward through 160 feet of soil, sending bubbling silt up through Horse Creek and sending the muddy mess further downstream into the Sammamish Slough.

Nobody thought to go above ground to look.

Only after neighbors and the City of Bothell complained did county inspectors notify the Department of Ecology and start testing Horse Creek. They didn't find toxins, just so much silt that it would be hard for fish to breathe.

When asked if this showed a good job of environmental stewardship, Sreibers said, "well again, I think we can all learn from experience."

But our insiders tell us the North Kenmore Portal was a hotbed of problems. Since June, they watched an increasing number of overflows from huge tanks on site. Our first insider told us of the overflows, "I've lost count, we've had so many of them, I mean sometimes it was on a daily basis."

The tanks contain a variety of waste and chemicals - called slurry - used in the mining process. "Some of these chemicals will eat right through your hand," says our first insider.

The spill in late July was so bad that one of the insiders took cell phone video many hours after the spill and cleanup. He drove down the driveway showing us where he says thousands of gallons of slurry had spilled, and he believes flowed into Little Swamp Creek; a stream just downhill from the construction site.

"What in the world is King County doing about this?" asks that insider.

When I first asked King County about this spill Sreibers was certain, "we are absolutely positive that nothing got into the creek."

Then I showed him the video.

"Pictures don't lie and we're certainly interested in making sure that we're not impacting the environment," he said and promised to investigate.

Two days later we returned and showed our video to the county's inspectors. They showed us four photographs - their only pictures of the spill.

The county's photos don't show the bottom of the driveway or Little Swamp Creek. Yet they insist nothing made it to the stream.

"We documented the fact that there was no flow in that ditch on the east side of the road," Sreibers said. We asked how that was documented and Sreibers said, "our inspectors basically confirmed it."

When we asked the county's environmental inspector Chris Tiffany if she'd written a report to document the spill she answered, "No I did not." We asked if she'd taken a water sample; her response, "I didn't need to because there wasn't a discharge."

So there was no environmental report, no photos of the stream, no water samples, just their word to contradict the insider video.

"Ecology should have been notified," said Mark Henley, manager of the state Department of Ecology's Water Quality Program. He also saw our video.

"Anytime there's potential for dirt or mud or slurry to get into the waters of the state we need to be notified," he said.

The Department of Ecology said, in general, King County and the Brightwater project have been good on environmental issues. But they promised that they would investigate our findings thoroughly.

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