CDM News - August 2007 - (Page 4)

Initiative & Innovation Stabilize Mercury Mines During the Gold Rush, miners eager to find their fortunes raced to work in the rich ore deposits of Northern California. More than 200 gold mines were developed and a host of industries sprang up to support the booming effort. One such industry was mercury mining. To extract gold during hydraulic mining, sluice boxes were lined with large quantities of mercury, which formed an amalgam with the gold particles. Luckily for the miners, large mercury deposits were found near many California gold mines. Unfortunately, however, many abandoned mercury mines remain today, and their uncontrolled releases of mercury-laden materials into waterways has contributed to elevated levels in aquatic plants and animals as far away as San Francisco Bay. Although the sites are remote—increasing the challenges for CDM crews—mercury runoff travels surface waters to San Francisco Bay, where officials have issued fish advisories. An Aggressive Strategy At the Turkey Run and Abbott mercury mines, built in 1870, mercury-bearing tailings entered Harley Gulch, a tributary to Cache Creek, which feeds into the Sacramento River and ultimately San Francisco Bay. Dale W. Evans, P.E., CDM vice president, explained, “Dealing with mercury associated with old mines is extremely important in California right now. Regulators are considering both emergency and long-term mitigation measures in impaired watersheds to stop the release of mercury-bearing materials by considering total maximum daily load, or TMDL, assignments under the Clean Water Act.” Abbott mines. Instead of incurring the liability for such costs and other supplemental actions, El Paso Corporation—which obtained the property through a past acquisition—developed a self-directed stabilization approach. Bart T. Wilking, remediation project manager for El Paso Corporation, said, “We challenged ourselves to meet an extremely compressed 9-month timeline from start to ﬁnish. Just 5 weeks after seeing the site, and little more than a week after meeting with EPA, we had mobilized heavy equipment and begun reclamation.” El Paso chose a design-build approach to expedite the schedule, while closely managing costs. “We As it had done with other mercury mine sites, the wanted to take action right away,” Wilking explained. U.S. Environmental Protection Agency (EPA) began “We had a long-term relationship with Dale and his planning an emergency response at the Turkey Run/ crew, which gave us the conﬁdence to use them for

Table of Contents Feed for the Digital Edition of CDM News - August 2007

Contents Envisioning Tomorrow’s Dublin Initiative & Innovation Stabilize Mercury Mines Preserving Old Town Alexandria Taking a Hard Look at Concrete Corrosion Perspective: Harnessing Bioenergy Engineering Better Lives CDM Announces Award-Winning Projects People Highlights

CDM News - August 2007

For optimal viewing of this digital publication, please enable JavaScript and then refresh the page. If you would like to try to load the digital publication without using Flash Player detection, please click here.