Regional
Arsenic Leaching Prompts Public Health Advisory in Grass Valley
Author: YubaNet
Published on Jan 31, 2006 - 10:48:00 AM

On January 25, the Regional Water Quality Control Board notified Nevada County, Empire State Park and other state and local agencies of a discharge of hazardous waste that may be a threat to public health and safety. "Arsenic in sediments from drainage surfacing out of the Magenta Drain portal on Empire Mine State Historic Park and flowing through Grass Valley's Veterans Memorial Park exceeds soluble threshold limit concentration," the notification reads.

Not a new problem

The arsenic discharge from the old Empire Mine, now a California State Parks property, is by no means a new phenomenon. The first inspection, according to State Water Board records, took place on March 5, 2002; a second inspection on January 19, 2006. In a sample taken on April 8, 2004, the arsenic concentration in the sediment was measured at 5.53 mg/L (milligrams per liter), which is equivalent to 5.53 ppm (parts per million). EPA standards give 0.010 ppm as maximum contaminant level. According to the Office of Environmental Health Hazard Assessment (OEHHA), arsenic is listed on the list of chemicals known to the state to cause cancer or reproductive toxicity.

The first inspection in 2002 was prompted by a complaint of "orange-colored water" in Wolf Creek. Bright orange-colored water and stained rocks are usually tell-tale signs of acid mine drainage. Acid can form in a mine when air and water come in contact with sulfide-bearing rock - either in underground mine shafts or above ground, where mining operations have stockpiled tailings (pulverized rock largely depleted of gold) and waste rock (which is removed from underground to gain access to the gold-bearing ore). Acid can dissolve toxic metals, which can then seep into the groundwater and waterways.

Senior Water Resource Control Engineer Richard McHenry Water Board said that "the city was very helpful in helping us locate the origin of the contaminants and followed up with State Parks." State Parks was told by the Water Board that the contaminated sediments had to be removed. State Parks also had to apply for a permit to lower the pollutant level.

At a pre-permitting inspection last week at the Magenta Drain, a Grass Valley Parks & Recreation employee encountered the state inspectors, inquired about their presence and informed his department director Sandy Jacobson of the nature of the permit. Jacobson contacted McHenry, who by then had issued the Prop. 65 notice to inform the concerned agencies of the problem of arsenic contamination.

Grass Valley Issues Health Advisory

On Tuesday, YubaNet.com contacted City Manager Gene Haroldsen and Public Works Director Jeff Jewett. Both said they had not yet received the Proposition 65 notice issued by the state, but they were working on language for a public warning in conjunction with State Parks.

Shortly afterward, Public Works Director Jeff Jewett issued the following news release:

"The State of California Regional Water Quality Control Board has issued a Proposition 65 Notice that materials have been released into the Magenta Drain that may be a threat to public health and safety. The Magenta Drain is a stream that flows from the Empire Mine State Historic Park through Memorial Park in the City of Grass Valley. Recent tests have indicated that concentrations of arsenic exceeding threshold limits are present in the magenta Drain.

The City of Grass Valley is posting warnings along the stream today. The public is advised to avoid any contact with the water or sediment in the Magenta Drain until further notice.

The City has been advised that the State of California is working to clean the stream. At this time, specific information regarding the clean up methodology or time frame is not clear. Meanwhile, avoiding contact with the stream water is advised."

For further information, Contact Jeff Jewett, City of Grass Valley, Public Works Director at 530-274-4350 or Ron Munson, State Park Superintendent at 530-273-3884

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