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• tation over the catchment area results in 0.89 acre feet of surface runoff, 1.17 acre feet of evapotranspiration, and 0.06 acre feet of infiltration. • Inasmuch as the catchment area above the tailings pond embankment is limited in size, water runoff inflow from rainfall and melted snow is not significant. The rate of the surface water runoff ie also quite low, ae the drainage area is on a gentle elope, with only a 20 foot difference in elevation firm the top of the tailings embankment to the crest of the ground behind it. ~ All of the made rovidin aocees to this milleite and tailin p g ge pond area were constructed many years ago. While some grading was done to improve the surface conditions of these roads, no major relocation work will be necessary. These access made will remain in place after the cessation of milling operations by C.O.M. Inc. • Security croneideratione and safety monitoring of the tailings embankment were also accounted for in the selection of this site. By closing the lower access mad below the tailings pond, and fencing the perimeter of the mill mmplex, both the property and the public are protected from one another. Since the • tailings pond is located near the milleite, the tailings discharge and decantation lines can be easily observed and closely monitored. ~ Guidelines for the design, construction, operation, and maintenance of mill tail- i d h b ngs pon s ave een established by the U.S. Bureau of Mines, the Colorado / Division of Mines, and the Colorado Water Quality Control Commission. Using ~ • these guideline C.O.M. Inc. designed a tailings pond that was built by employ- ~_ {~~~~~ ing a u~etream metho 0 onetruction, operation, and maintenance of the tailin c epe c t ge dam design was ch~en bg cause it provided structural stability, afforded adequate storage capacity, w`ad utilized readily available borrow material, and allowed for the construction of • an embanlmient that was built in several stages. Environmental mnaidera- tione were also taken into account, when this particular deai was selected for tailings disposition. The design principles for an stream tailin are - k ~ LJ compatible with the location selected for tailings impo en ,and with the w.,~ ~c~a,. - ~ type of milling operation that ie being c o n duct ed y C.O.M. Inc. ' ~ p nn COw9{Yf~t~J-~ ~~i • ~ The upstream method o ilinge dam cone chon a with the construc- tion of a low r~ , or tce t was built to contain the tailings during the initf s gee o epoei on. Tailings are discharged off the upetneam face of the toe dam at regular intervals from spigots connected to a peripheral (.oti~ discharge line. A favorable gravity separation of the tailings results from this k~ f i type of discharge. The coarsest sand particles drop out closest to the point of _ _ • discharge, and the forest particles (the slimes) flow into the center of the tail- ings dam, where the eaceae water forms a localized pond. Because of the relatively large size differential between the coarse and fine fractions of the tailings, the coarse sand particles form a beach in front of the spigots. The sand beach that is formed around the upstream perimeter of the starter dike ie • used for raising the height of the impoundment dam. This ie accomplished in stages. When the initial pond is nearly filled, the starter dike is raised with -~ •