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;' MINE WATER DISCHARGE SITES <br />Two mine water discharge sites associated with the TCC operations aze monitored. Site 109 requires quarterly <br />monitoring for flows, field parameters, and water quality samples, and site 115 is monitored as an NPDES <br />discharge point in accordance with the requirements set forth under NPDES Permit No. CO-0042161. <br />Monitoring requirements at both sites were fulfilled during 1996. Discharge from site 115 was sporadic and <br />occurred for only short periods during the first part of the yeaz (see Figure 112). The site 115 pumping system <br />experienced a breakdown in July of 1995 which caused the system to be idled until October. Upon reactivating <br />the system, total recoverable iron limitations were not met on a consistent basis. Modifications to the chemical <br />treatment methodology utilized at the site were attempted in order to reestablish discharge compliance during the <br />period from November through February. The modifications entailed the use of sodium hydroxide solution to <br />elevate the pH of the discharge water to a range where the aluminum chloride flocculant would work more <br />effectively. Numerous difficulties were encountered primarily involving sodium hydroxide's propensity to <br />solidify at relatively high temperatures. <br />Mining in the Southwest Mining District was completed in February 1996 and with this occurrence, the need to <br />continue dewatering operations at site 115 was eliminated. TCC has since developed a plan to recirculate water <br />accumulating in the Southwest Mining District and utilize it for dust control purposes elsewhere in the mine. A <br />water level measuring point was established at the Fish Creek Borehole in July of 1996. The water elevation was <br />recorded at 5774.2' in July and increased to 5787.5' by October. Before being recirculated, water will be allowed <br />to accumulate to elevation 5960'. / ~ ~~ (~ -~ f ~ /,~~ ~~~,l~.~yu,~, ~ ~S <br />~FG '1D vy I,_ °t 1 <br />Table 58 provides a summary of the 1996 Water Year data collected from site 109. Table 58a provides a period <br />of record statistical summary of collected data at the site. Table 58b presents water meter readings at site 109 for <br />the 1996 Water Year. A malfunction of the water meter at site 109 occurred during the last quarter of the year. <br />Flow estimates for the last quarter of the 1996 Water Year as presented on Table 58 and yearly flows as provided <br />on Table 50 are approximated utilizing the measured flows occurring at the site during the same quarter last year. <br />Figure 111 provides a graphical representation of period of record field conductivity for mine water discharged at <br />site 109. During the year, new maximum values. for total recoverable mercury and lab conductivity were <br />established with new minimums noted for nitrite, ammonia, and SAR (Table 58). <br />1996 Water Year data for mine water discharge site 115 is presented on Table 59. Table 59a provides the period <br />of record statistical summary. Table 59c presents water pumping records at site I15 for the 1996 Water Year. <br />Figures 112 and 113 provide graphical representations of Water Year flow rate data and field conductivity data <br />respectively. <br /> <br />-13- <br />