Road Dust Control

Posts Tagged ‘freeport mcmoran’

Suited up with green hard hats, safety vests and protective goggles, five members of the Green Valley Community Coordinating Council’s Environmental Committee headed to Freeport-McMoRan Copper & Gold’s Sierrita operation to see how the mine controls tailings dust.

Chief Environmental Engineer Sherry Burt-Kested, Environmental Manager Chad Fretz and Regional Community Affairs Manager Richard Ducote explained how their impoundment crew works to minimize dust from the mining process.

There is special attention to the 3,500 acres of the mine’s Mill Tailings Impoundment, which is surrounded by about eight miles of berm. Tailings are a by-product of the mining process. The berm refers to residue and rock piled around the edge of the impoundment to help reduce dust.

Fretz said blue-green algae is a native binder for desert soil. First tried on the tailings impoundment in 2003, when added to water in the impoundment area, it helps to minimize dust. He said Freeport McMoRan recycles 30 percent of its water at the mine.

“We anticipate winds, watch the weather, have appropriate staff to tend to tailings and we hear from the ADEQ (Arizona Department of Environmental Quality),” Fretz said.

But even the best plans can face challenges.

Freeport-McMoRan last year paid a $105,000 fine to the state for air-quality violations involving dust coming from the mine in 2006 and 2008.

About 600 homes in Green Valley were affected by the tailings dust in 2006, and an investigation found Freeport-McMoRan had failed to document or act to avoid future problems. The company paid more than $150,000 to help residents clean their homes in 2006.

Today, Freeport-McMoRan staff works around the clock and additional staff will be called to aid the regular impoundment crew of eight when weather conditions forecast problematic winds. Fretz said employees will be pulled off a job to help with dust control as needed. They maintain areas of wet surfaces and look for hot spots of dust within the mine’s 27-square-mile area.

To help spray water faster Freeport McMoRan has purchased Snowcats, large tractor-like vehicles that can spread water 20 feet in each direction.

Burt-Kested said she is constantly looking at new ways to minimize dust.

Along with workers keeping the speed of trucks down to help minimize dust, she touted the expertise of employees who watch for hot spots of dust and work to mitigate it.

More than blue-green algae, Snowcats dispersing water over wide areas and employees keeping an eagle eye out for hot spots, the mine has a Terra-Gator vehicle that disperses seeds so vegetation can grow. It’s another way to reduce dust.

Freeport-McMoRan also has about 100 head of cattle that provide fertilizer to help vegetation grow.

Tags: mill tailings impoundment, freeport mcmoran copper gold, freeport mcmoran, freeport mcmoran copper, air quality violations