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Editorial: Silver Valley water treatment plan good news for everyone

Fri., June 20, 2014

Perhaps it’s an overstatement to claim a new agreement will assure operation of a Silver Valley wastewater treatment plan into perpetuity, but calling the deal approved Wednesday by the Idaho Board of Land Commissioners good news is no stretch at all.

With $15 million from a settlement with the Hecla Mining Co., the U.S. Environmental Protection Agency will expand and manage for as long as 10 years a facility that has been stripping metals, mostly zinc and cadmium, out of water flowing from the long-closed Bunker Hill Mine. The Kellogg plant now treats about 1,500 gallons a day during most of the year, but as much as 8,000 gallons during spring runoff.

The effluent is discharged into the South Fork of the Coeur d’Alene River, which for more than a century has carried mine waste downstream into Lake Coeur d’Alene. Some eventually reaches the Spokane River, so any improvement upstream is good for most people living in the Inland Northwest.

A decade, obviously, is not perpetuity, and that’s where the state of Idaho comes in. The Land Board created a $50 million endowment out of the total $243 million 2011 settlement with Hecla for its contribution to Silver Valley waste. The state’s Endowment Fund Investment Board will manage the money with the expectation that it will, indeed, generate enough income to cover – for all time – treatment plant costs.

Based on a five-year rate of return of 14.3 percent, there’s reason for early optimism on that score.

The EPA will hand responsibility for the plant to the Department of Environmental Quality when its share of the money runs out. For Silver Valley residents, anything that removes the hand of the EPA is a good thing.

But there is work to be done before that happens.

The expanded plant will also treat groundwater contaminated by the piles of Bunker Hill tailings, which over decades pushed the South Fork channel to the north. Wells must be drilled, and a slurry wall inserted to prevent South Fork water from seeping back into the ground.

The valley and the South Fork exchange water much as the Spokane-Rathdrum Prairie Aquifer and Spokane River do.

As much as 40 percent of South Fork flow in the vicinity of the treatment plan is groundwater seepage. Pump too much, and river water will flow back into the ground, not downstream. The slurry wall will keep that from happening.

Besides removing metals, the treatment process also improves water chemistry. Lime used to precipitate out the metals also hardens the water. Fish living in hard water do not absorb metals as readily as they would in softer water.

The EPA will also continue to attack the problem with more surface remediation in South Fork headwaters like Nine-Mile Creek.

The day will probably never come when the South Fork returns to a near-pristine state and the pumps and treatment plant at Kellogg can be shut down. The state, EPA and Coeur d’Alene Tribe have done their best to keep the Kellogg plant operating.

For that, the region should be grateful for a very long time.