Clark Fork closes in on Plains sewage lagoons

In the most recent round of Mother Nature versus the Town of Plains it seems the town is losing, but not giving up. With a heavy snow pack, warm weather and strong currents, the river has come within 130 feet of the Wastewater Treatment Facility's UV treatment structure and the river hasn't shown signs of slowing.

The U.S. Army Corps of Engineers (USACE) arrived at the site Monday with an excavator and an army of dump trucks to place tons of large jagged rocks along the shoreline of the town and Randy Garrison's property, which border's the town's sewage lagoon.

Contracted trucks from companies in Sanders and Lake County dropped nearly 30 loads of rock Sunday. They anticipated dropping 40 truckloads Monday. The plan is to line about 1,200 feet of shoreline with the riprap in hopes of slowing the erosion process and saving the UV facility. The town has been losing ground to the river for more than 20 years, said Mayor Dan Rowan, who had been inspecting the erosion nearly every day for the last three weeks.

"I'm extremely happy that we're getting some help with this," said Rowan. A USACE representative from Spokane examined the lagoon last week and found it a significant concern, according to Rowan. Rowan said the excavator first reconfigured the shoreline to make it slope, which helps keep the rocks in place. He said a portion of the river at the site is nearly 40 feet deep.

Rowan said it was critical to stop the erosion from reaching the UV treatment site, the final station before it can safely be pumped into the river. "If that goes, we'll be out of business. Sewage has to go through that process to go into the river," said Rowan, who's been checking on the erosion situation everyday for the last three weeks. "We've lost about 18 to 20 feet in a little over a week," he said.

Sanders County Emergency Manager Bill Naegeli was at the scene and said he feels this will definitely slow the erosion process. "We're hoping this will be a permanent fix," said Naegeli. Greg Dicken of the Plains Public Works Department said this is the fourth time riprap has been placed to combat the erosion, although he noted that in previous times, it has never been this length of riprap.

The town has been concerned about the erosion at the lagoon for several years. Riprap was placed along the shoreline near the sewage lagoon six years ago, but it has been washed away. Rowan said about 200 feet of shoreline at the lagoon has been lost to erosion by the Clark Fork River in the last 20 years.

The 46-acre Wastewater Treatment Facility was created in 1983 at the end of Helterline Drive, but Rowan believes the erosion problems didn't really begin until after the winter of 1996-97, when a large deposit of gravel built up on the opposite side of the river.

The town sewage goes through four treatment ponds before it gets to the UV treatment site. The structure is protected by a small amount of riprap on the west side of the building and sets about 10 feet above the waterline. Rowan said the land between it and the river is mostly sand and small gravel and it wouldn't take much for the river to take it away.

Last year, former Mayor Greg Eitelberg placed several wooden stakes about three feet from each other in an effort to get a better visual of the erosion progress. His last stake was washed away sometime Sunday night or early Monday morning.

Surveyor Ron Warren has provided the town with Google Earth photographs of the site with overlays that show where the shoreline had been since 1995. Sanders County Commissioner Carol Brooker, who visited the site last week, offered county gravel and rocks to help slow the erosion.

The town council has already approved for the construction of a 250-foot long steel barrier that would be driven 40 feet into the ground. However, the construction, which would cost $1.1 million, depends on the approval of four grants. And even if the town receives the grants, the money would probably not be available until next year, according to Rowan, who added that they must get all four grants to do the work. "That won't hold forever, but it may buy us some time to explore other options," said Rowan.

Another option the council considered was to place riprap along some 750 feet of the shoreline properties of Garrison and the town at a price tag of $2.75 million. But the riprap plan would also only band-aid the situation.

"The only guaranteed fix would be moving the lagoon," said Rowan, but he said that would cost over $7 million and the town would have to find adequate property."

Sanders County Commissioners on Monday declared a state of emergency because of flooding in the county.