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<br />Auger hole tests were performed to determine the hydraulic conductivity, <br />(permeability) of the alluvial flood plain materials. The permeability <br />determined from the auger hole tests ranged from 0.014 ft/d to 2 ft/d. <br />Attempts to conduct an auger hole test at one hole failed because the <br />permeability was too high. A pump test was performed on that hole, and <br />from the observed drawdown, the permeability was estimated to be about <br />1,880 ft/d. <br />fie alluvial flood plain ground water is a calcium-bicarbonate type water <br />with a chemistry similar to that of the Purgatoire River (see permit <br />application Exhibit 6, Figures 12 and 14 ), but with slightly higher <br />concentrations of the major ions. The only significant difference with <br />respect to the major ions is an elevated sodium concentration in the <br />alluvium relative to that in the stream. Although seepage from the New <br />Elk Mine refuse pile has high sodium concentrations, mining activities <br />are not the sole cause of the elevated sodium levels. Sodium is high in <br />all four wells. The sodium is probably being contributed, in part, by <br />the dissolution of one or more sodium salts contained in the soils or <br />alluvium. <br />Concentrations of major ions and the conductivity of alluvial wells at <br />the downstream Golden Eagle Mine site are less than the concentrations <br />and conductivities of wells at the New Elk Mine site (Exhibit 6, Table <br />3). This is probably the result of inflows of better quality water from <br />the North Fork of the Purgatoire that joins the Middle Fork of the <br />Purgatoire between the two mine sites. <br />D. Surface Water <br />The Purgatoire River, a tributary of the Arkansas River, is the major <br />surface drainage feature of the area. The headwaters of the Purgatoire <br />are located on the eastern slope of the Sangre de Cristo Range west of <br />the study area. The three major branches of the river, the North Fork, <br />Middle Fork, and South Fork, all converge within the study area. The New <br />Elk Mine is located on the Middle Fork, about 1.5 miles upstream of the <br />confluence of the North and Middle Forks of the river. The Golden Eagle <br />Mine is located downstream of the confluence of the North and Middle <br />Forks of the Purgatoire River, and approximately two miles upstream of <br />the confluence of the South Fork and the main stem of the Purgatoire <br />River at Weston. <br />The headwaters of the Purgatoire River system are in excess of 9,000 ft. <br />elevation and receive substantial snowfall. For example, the mean annual <br />precipitation at North Lake at the head of the North Fork (elevation <br />8,800 ft.) is 20.55 in. of which 7.48 in. is in the form of snow. On the <br />other hand, the mean annual precipitation at Trinidad (elevation 6,030 <br />ft.) is 13.22 in, and only 2.19 in, of this total is in the form of <br />snow. The disturbed areas of the mine sites are between 7,000 and 7,500 <br />ft. in elevation and are located between the Trinidad and North Lake <br />stations. The mean annual precipitation at the New Elk Mine is <br />calcu]ated to be 16.9 in. with snowfall contributing 5,00 in. to this <br />total. <br />-16- <br />