Engineering & Mining Journal

JUL 2018

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ENVIRONMENTAL MANAGEMENT 28 E&MJ • JULY 2018 www.e-mj.com mining is on the order of 16 million to 18 million tons if one extrapolates from the figures from 1873 to 1964. Of this, about 12 million tons is reasonably ac- counted for, mostly in the Mayflower Mill impounds [where impounding began in 1935]. The majority of the remaining 4 million to 6 million tons were likely di- rectly discharged to surface drainages. Even when tailings were impound- ed rather than expelled directly to area streams, significant discharges took place. In 1947, the sand wall on the Mayflower tailings impoundment No. 1 collapsed and a large quantity of waste and tailings spilled into Boulder Creek and then the Animas River. In 1975, the main Mayflower tailings impoundment washed out, resulting in the discharge of 100,000 tons of tailings and waste into Boulder Gulch and the Animas River. Considerable cleanup was required and Standard Metals, the own- er of the property at the time, received a $40,000 fine for the incident, which was the largest environmental fine in Colora- do's history. In 1978, Lake Emma broke through into the 2580 Stope on Sunny- side Mine level C and flooded the mine, stripping timbers from the main shaft, crushing equipment and filling tunnels with mud. At the Gladstone portal, an estimated 5 million to 10 million gallons of water blew out the walls of the portal building. The Animas River turned black from the glacial mud and sediment well past Farmington, New Mexico. There was an extensive legacy of man- made, systematic, and cataclysmic dis- charges of metals and acidity to the upper Animas River basin prior to 1985. Before the 1970s, there were no measurements of any of these discharge quantities, but they were clearly significant. Miners were not required to reclaim their sites until the 1970s and most followed the accept- able practices of their time. This massive industrial mining and milling complex resulted in enormous amounts of metals loading in the Animas River, which fur- ther limited aquatic life, including trout populations downstream from Silverton. 5 Years of SGC Mining in Silverton Caldera SGC was formed in September 1985 and acquired the Sunnyside mine from Stan- dard Metals on November 19, 1985. The Sunnyside mine was discovered in 1873 by Ruben McNutt and George Howard. Standard Metals had operated the prop- erty since 1960, but by 1985 they were in bankruptcy. The mine was not commer- cially producing and was under a Cease and Desist Order for violations of its min- ing permit and two of its three water-dis- charge permits. The third water-discharge permit was under a notice of violation, which, due to Standard's neglect, ma- tured into a Cease and Desist Order by December 1985. Standard's permit violations included inadequate storm-water discharge con - trol, lack of water treatment, unapproved disposal of pond sludge waste, a poorly constructed and inappropriately located waste rock dump, unapproved disposal of approximately 8,000 cubic yards of trash, failed revegetation, spring flow running through tailings ponds, and mining im- pacts in unpermitted areas including the Terry Tunnel and seven acres in the Sun- nyside Basin, specifically the collapsed Lake Emma. Water permit violations in- cluded exceedances of cyanide, pH, zinc, total suspended solids, copper and lead discharge limits. The water treatment facilities at Glad- stone were not operating and were in such a state of disrepair that SGC had to apply for bypass approval to remain in compliance while critical upgrades were completed. The Colorado Mined Land Reclamation Division's July 10, 1985, inspection of Standard's operation noted the following: evident that water quality above and below the site is poor; drainage control at the American Tunnel is poor; water treatment not running; untreated water routed through ponds, then dis- charged to North Fork of Cement Creek; waste rock dump constructed with little engineering concern in a swampy area; sludge has been disposed at waste rock dump, trash improperly disposed. Stan- dard Metals' answer to these violations was to advise the regulatory agencies that Standard could not respond due to their bankruptcy filing and lack of resources. SGC promptly brought all discharge permits into compliance, redesigned the mining operation, and completed a sub - stantial mine permit amendment in coop- eration with Colorado regulatory agencies. Specifically, SGC removed scrap iron, broken ore cars and locomotives, made drainage improvements, and constructed Before and After: Mayflower Impoundments Nos. 3 and 4 as seen in 1992 (left). SGC regraded the top of No. 3 (foreground), capped it with subsoil and reseeded it. SGC relocated 80,000 tons of waste to No. 4, regraded the area, and re-seeded it. This is how it appeared in 1995 (right).

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