Laserfiche WebLink
STANDARD METALS CORD ATION <br />Mr. Don Simpson <br />Permits and Enforcement Section <br />Water Quality Control Division <br />Colorado Department of Health <br />4210 East Eleventh Avenue <br />Denver Colorado 80220 <br />Dear Don: <br />P.O. Box 247 <br />Silverton, Colorado 81433 <br />(303) 387 -5533 <br />, March 21, 1983 <br />Re: Information Request - Tail Pond <br />No. 4 Seepage Control Plan <br />The information reauested in your letter of February 18, 1983, regard- <br />ing Tail Pond No. 4 seepage control, is presented below. <br />1. Test holes and pits were excavated at the tailings pond site dur- <br />ing the foundation investigation which intercepted ground water <br />at various depths ranging from surface to ten feet. Monitoring <br />wells numbers 1, 2, 7, 11, 13, 19, 16 and 18 (Seepage Control Plan <br />Figure 2. ) penetrate to depths averaging five feet below the <br />tailings alluvium- interface (See Figure 1). It is reasonable to <br />assume from this information that the monitoring wells recently <br />installed in the tailings structure embankment intercept some <br />natural ground waters; however, due to the spatial relationship <br />between the tailing structure ponding area and well location, the <br />majority of water sampled in the wells is believed to originate <br />in the pond. <br />2. The tailings deposition site was excavated down to river gravel <br />in the Animas River Flood Plain during the site preparation phase <br />of tail pond construction. Excavated materials were either stock- <br />piled for reclamation or used in constructing the pond starter <br />dike and toe drain, dependent on material characteristics. The <br />organics and fine were stockpiled, river gravels meeting toe <br />drain permeability requirements were used in constructing the <br />blanket toe drain, and moraine materials meeting starter dike <br />specifications were used in its construction. <br />The blanket toe drain, constructed of river gravels overlain by <br />filter cloth, extends from the upstream toe of highway 110 to <br />a distance approximately 100 feet under the tailings pond embank- <br />ment (see Figure 2). The remainder of the pond lies in direct <br />contact with natural alluvium minus excavated materials. <br />