PHOENIX (Aug. 9, 2010) – Arizona Department of Environmental Quality officials announced today that a $595,370 Water Quality Improvement Grant has been awarded to the Franciscan Friars of California, Inc. for a topsoil cap at the abandoned Gibson Mine site to reduce the leaching of copper into Pinto Creek.

About 82,000 tons of topsoil will be laid about 2 feet deep over about 10 acres of the disturbed surface of the abandoned mine site, located northwest of Miami in Gila County. The soil will be graded in such a way as to slow and dissipate runoff and will be heavily seeded with native plant species.

Discussions are under way with the Arizona Department of Transportation for the potential donation and delivery of topsoil from nearby road construction sites.

“This is another important project to reduce contamination into Pinto Creek from an abandoned orphan mine. ADEQ is pleased to be working with the Franciscan Friars to boost the health of Arizona’s waterways,” ADEQ Director Benjamin H. Grumbles said.

A ridge runs through the mine site, separating the runoff into two subwatersheds. One side of the mine is the drainage area for Gibson Mine tributary and Pinto Creek in the Salt River watershed. The other side flows into an unnamed tributary of Mineral Creek in the Gila River watershed.

ADEQ awarded a $570,106 grant to the mine owners in 2005 to remove tailings piles that were leaching copper into Pinto Creek and $140,171 in 2006 to construct a detention and treatment basin to catch and filter runoff from the Mineral Creek side of the abandoned mine site, limiting copper-laded runoff to the creek.

ADEQ’s program is funded through a partnership with the U.S. Environmental Protection Agency under the Clean Water Act.

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Source: ADEQ Media
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