Work begins on $1M trench to stave off Matanuska River erosion

BUTTE — Construction of a rock-filled trench began Tuesday to protect the Old Glenn Highway and utilities from the bank-eating Matanuska River roiling about 120 feet away.

Gov. Bill Walker declared a disaster for the area late Monday after the river began threatening numerous properties — and the Old Glenn, a state road.

But given tight state and local budgets, it appears there isn't enough money to construct a trench long enough to fully protect against the river's potentially destructive force.

Tons of rock thundered from dump trucks Tuesday as the Alaska Department of Transportation and Public Facilities began work on a 500-foot trench to be filled with boulders upriver from Maud Road.

Workers on Tuesday afternoon were piling rock next to the highway but the plan is to lay the trench on the river side of the Matanuska Electric Association power poles, officials say. As of late afternoon, crews lacked permission to dig from a private landowner at the start of the trench; the rest of the project falls on Matanuska-Susitna Borough land.

The $1 million to pay for the work comes out of a state emergency fund made accessible by the emergency disaster declaration, according to Marc Luiken, the state DOT commissioner.

The DOT's hydrologist, however, is recommending a 1,000-foot trench. There isn't enough funding available to do that now, officials said.

The trench isn't specifically intended to protect private property, though officials hope it also has that effect. Instead, it's designed to protect the road and electric and telecommunications utilities, authorities say.

The Matanuska is threatening riverside homes from Mile 12.5 to Mile 15 along the Old Glenn Highway. Authorities this week started warning people with homes in the path of the river to consider putting an evacuation plan in place.

A flood model shows about 40 properties and 15 structures in the river's path if the erosion continues.

The section of trench that remains unfunded would wrap around an old gravel pit, keeping the river's flow from reaching a lower channel that could funnel water to many properties.

Downriver property owner Scott Easler said the project "will offer no protection" unless the state continues the trench back toward the river from the Maud Road access, which at this point isn't in the plans.

"There is only so much money. That's the difficulty with all of this," said Mat-Su Assembly member Jim Sykes, a daily presence at the river.

The borough has only about $1 million of its own in an emergency account and can't spend all of it on the river, Sykes said.

Since late July, the river has taken about 100 yards of bank by one estimate. It chewed through about 40 feet in just a few days last week, though its progress was slowed this week, partly by trees cut and lashed to a borough-owned riverbank.

Borough officials requested a state disaster declaration after realizing the force of the river was threatening to flood numerous properties.

The river isn't flooding, DOT hydrologist Paul Janke said Tuesday, as he eyed the turbid water. Instead, the silt-laden water naturally forms gravel bars that drive the current toward the bank, making it nearly impossible in any given year to predict what the river will do until flooding becomes imminent.

"We're being as proactive as we think we can with public funding," he said.

A 1980s-era flood dike along the bank washed out years ago and was never replaced.

Residents along the river have called for years for the government to dredge a channel away from the bank, but due to a combination of cost, tricky permitting and questions about the potential success of such measures, those plans never materialized.

Property owners in the area in 2013 rejected a proposal to develop a new tax district to help pay for measures to stem erosion and flooding.

Dave Blair lives across the Old Glenn from the project and got home from work Tuesday to watch crews clearing giant cottonwoods in the path of the trench.

"You would think that this would have started a whole lot sooner," Blair said. "I'm certainly grateful it's happening now."

Correction: This story has been edited to reflect that the name of the DOT hydrologist quoted is Paul Janke, not Paul Banke.