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DWR_3391346
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Last modified
2/20/2019 9:44:10 AM
Creation date
2/20/2019 8:24:27 AM
Metadata
Fields
Template:
Dam Safety
Document Date
6/23/1982
Document Type - Dam Safety
Report
Division
3
Dam ID
200224
Subject
HOMESTAKE TAILING POND, LOWER DAM - INVESTIGATION AND EVALUATION
DWR Send/Recipient
ALAN PEARSON - DSB
Outside Send/Recipient
MINE SAFETY AND HEALTH ADMINISTRATION
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Pursuant to a request by the Rocky Mountain Subdistrict Field Office, a <br />visual investigation of the tailings pond, owned by Homestake Mining <br />Company, was made on June 23, 1982, by Stephen W. Dmytriw and John L. Odell, <br />Safety and Health Technology Center, Denver, Colorado. Richard Bohling, <br />Metallurgist, was the company representative at the site. Photographs <br />of the structure are included in the appendix of this report. <br />LOCATION AND OWNERSHIP <br />The site, owned by Homestake Mining Company, is located in a side gulch <br />of Miners Creek of the Rio Grande River, Mineral County, Colorado. The <br />community of Creede is approximately 1 mile northeast of the site. <br />DESCRIPTION <br />The site, at about El. 8950, consists of an embankment approximately <br />1200 feet long, 90 feet high, and 28 feet wide on the crest. Slopes <br />were approximately 3 horizontal to 1 vertical upstream and 2 horizontal <br />to 1 vertical downstream. The dam is composed of a granular shell outer <br />surface and reportedly a relatively fine-grained central core. The plan <br />also indicates that a chimney and blanket drain are included in the <br />downstream portion of the dam for seepage control. <br />An open -channel spillway has been excavated in original ground through <br />the left abutment (looking downstream). The irregularly shaped spillway <br />section is generally about 24 feet wide at the base, 6 feet deep from <br />the invert to the crest of the dam, and consists of variably sloped <br />sideslopes. A pump is also available at the site to return water back <br />to the plant. <br />The pond, covering about 9 acres and presently 24 feet below the crest, <br />has a 200 -acre watershed upstream. Since the dam exhibits approximately <br />1-2 feet of camber, freeboard toward the abutments is somewhat less than <br />24 feet. Small diversion ditches have been constructed around the pond <br />to divert runoff from small storms to an adjacent gulch. Tailings were <br />initially deposited along the upstream face of the dam to form a beach <br />adjacent to the structure. Tailings are now being deposited at the <br />upstream end of the pond in hopes of decreasing seepage through the <br />foundation of the structure. According to Mr. Bohling, facility features <br />could be significantly altered should the company raise the embankment <br />(15 feet) as originally designed. <br />Seepage was emerging from several locations immediately downstream from <br />the dam. The water was creating a boggy area about 50 feet downstream <br />from the toe. Seepage water is returned to the tailings pond by means <br />of a pump located about 200 feet downstream of the boggy area. Flow in <br />excess of the pump's capacity is discharged downstream. A series of <br />pumps had been installed around the seepage areas to function as a <br />relief well system. It was reported that the company had abandoned the <br />pumps because the large amount of sand extracted by pumping was causing <br />the motors to burn out. <br />
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