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per centimeter. Mean values also indicate that the water has elevated concentrations (on a total <br /> metal basis) of cadmium, copper, iron, lead, manganese and zinc with respect to Colorado water <br /> quality standards (1986) for domestic water supplies. <br /> The majority of the total metals load and the acid entering the American Tunnel originates <br /> downstream of the SJCMV property line. Figures 11, 12, and 13 are profiles of water <br /> chemistry along the American Tunnel. Figure 11 shows that on October 2 and 3, 1991 the flow <br /> in the American Tunnel had a n arly neutral pH until it encountered water entering from the <br /> fracture zone at the "steel sets" between 3020 and 3220 feet from the end of the track. Water <br /> from the steel sets fracture zone was sufficiently acidic to reduce the pH of the overall flow to <br /> approximately 5.5. <br /> The total load of metals carried by a stream is the flow rate times the total metals <br /> concentrations. Figure 12 shows that the total metals load of iron, zinc, and manganese in <br /> American Tunnel ditch water dramatically increases after the steel sets fracture zone. The load <br /> of iron, zinc, and manganese continues to increase at a lesser rate throughout the last 2500 feet <br /> of the American Tunnel where dtipping water enters the tunnel from relatively minor joints. <br /> Figure 13 shows that the total metals load of copper and cadmium in American Tunnel ditch <br /> water also increases at the steel sets fracture zone. The load of cadmium does not increase <br /> downstream of this point, but the load of copper continues to increase in the last 2500 feet of <br /> the tunnel. <br /> sanjuan\sunny\11036 1\oct9 1.Rpt 43 <br /> e�� snon HY[ano=se,,nm <br />