Arsenic and old mines: how to fix bad drinking water |

Arsenic and old mines: how to fix bad drinking water

Some western Nevada County households that have relied on under-the-sink filters to remove arsenic from their drinking water for the past decade could soon get relief, according to federal officials.

A hearing is scheduled next week to address public concerns of drinking water contaminated by the abandoned Lava Cap Mine, a gold and silver mine that operated from 1961 and 1943. The comment period began July 30 and will end on Aug. 29.

A week from today, federal Environmental Protection Agency representatives will give background on the so-called Superfund site and proposed alternatives to remedy the tainted groundwater found beneath it.

Since 1999, the EPA has been investigating the 30-acre mine site sandwiched between Lava Cap Mine Road and Lost Lake.

Early water samples taken at the property showed eight to 10 wells serving five households with arsenic levels above safe drinking water standards, said Rusty Harris-Bishop, remedial project manager for the site.

“We’ve been maintaining and providing filters since then. We don’t believe anyone is drinking water above the standards now,” Harris-Bishop said.

But reverse osmosis, or water filteration, units require constant maintenance to work properly, Harris-Bishop said.

Ingesting arsenic contaminated drinking water is known to cause cancer to humans. Absorption of arsenic through the skin by bathing or washing is considered a minimal health risk.

Processing ore to extract gold and silver from the mine produced finely ground tailings containing naturally occurring arsenic and other trace metals, according to the EPA.

“We’ve focused on the mine first to get that stabilized because that’s kind of the source,” Harris-Bishop said.

Cleaning up the ground water is the second phase of the superfund project.

In recent years, construction crews worked to place a plastic and earthen cap over four acres of toxic mine tailings, Harris-Bishop said. To date, the EPA has spent $22 million cleaning up the site, one of 94 in California and 1,255 listed as priority Superfund sites nationwide. The sites include different types of toxic waste, not just from mining.

At the public meeting, Harris-Bishop will discuss four alternatives for permanently removing water-related health risks to those households that now depend on groundwater near the mine.

Tapping into Nevada Irrigation District’s municipal water supply is the preferred method the EPA is proposing and the most costly. Installing a new pipeline at an estimated cost of over $4 million is infrastructure the EPA would foot the bill for, Harris-Bishop said.

A later phase of the project will include cleaning up Lost Lake and its surrounding flood plain. Signs of fishing and dog prints in the mud show people frequent the area, Harris-Bishop said.

Long-term exposure is of most concern, he said.

The wetland was originally built as a holding tank for mine tailings and has 40 to 80 feet of accumulated deposits built up from the past 70 years.

“It would be physically impossible to dig them all out,” Harris-Bishop said.

To contact Staff Writer Laura Brown, e-mail or call 477-4231

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