DWR_3391346 - Laserfiche WebLink

Pursuant to a request by the Rocky Mountain Subdistrict Field Office, a visual investigation of the tailings pond, owned by Homestake Mining Company, was made on June 23, 1982, by Stephen W. Dmytriw and John L. Odell, Safety and Health Technology Center, Denver, Colorado. Richard Bohling, Metallurgist, was the company representative at the site. Photographs of the structure are included in the appendix of this report. LOCATION AND OWNERSHIP The site, owned by Homestake Mining Company, is located in a side gulch of Miners Creek of the Rio Grande River, Mineral County, Colorado. The community of Creede is approximately 1 mile northeast of the site. DESCRIPTION The site, at about El. 8950, consists of an embankment approximately 1200 feet long, 90 feet high, and 28 feet wide on the crest. Slopes were approximately 3 horizontal to 1 vertical upstream and 2 horizontal to 1 vertical downstream. The dam is composed of a granular shell outer surface and reportedly a relatively fine-grained central core. The plan also indicates that a chimney and blanket drain are included in the downstream portion of the dam for seepage control. An open -channel spillway has been excavated in original ground through the left abutment (looking downstream). The irregularly shaped spillway section is generally about 24 feet wide at the base, 6 feet deep from the invert to the crest of the dam, and consists of variably sloped sideslopes. A pump is also available at the site to return water back to the plant. The pond, covering about 9 acres and presently 24 feet below the crest, has a 200 -acre watershed upstream. Since the dam exhibits approximately 1-2 feet of camber, freeboard toward the abutments is somewhat less than 24 feet. Small diversion ditches have been constructed around the pond to divert runoff from small storms to an adjacent gulch. Tailings were initially deposited along the upstream face of the dam to form a beach adjacent to the structure. Tailings are now being deposited at the upstream end of the pond in hopes of decreasing seepage through the foundation of the structure. According to Mr. Bohling, facility features could be significantly altered should the company raise the embankment (15 feet) as originally designed. Seepage was emerging from several locations immediately downstream from the dam. The water was creating a boggy area about 50 feet downstream from the toe. Seepage water is returned to the tailings pond by means of a pump located about 200 feet downstream of the boggy area. Flow in excess of the pump's capacity is discharged downstream. A series of pumps had been installed around the seepage areas to function as a relief well system. It was reported that the company had abandoned the pumps because the large amount of sand extracted by pumping was causing the motors to burn out.