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l `? <br />?ti <br />?, ?' *:? <br />?' <br />The New Horizon Mine has two significant differences to the results observed at Seneca n. First, the <br />calcite present in the spoil at New Horizon seems to react with acid produced by the oxidation of pyrite <br />and take a substantial amount of sulfate from solution into solid calcium sulfate. This beeps the dissolved <br />solids content somewhat constant no matter how high or low the the inflow water quality is with regard <br />to TDS, Second, the Seneca Tl site is a dryland reclaimed area where the only recharge into the span is <br />a minor amount from precipitation and seepage from the underburden aquifers. Total measured discharge <br />from. the spoil was only 3" per year. The New Horizon Mine is principally irrigated with water of very <br />good quality over a large portion of the year. As described earlier, this results in a total movement through <br />the spoil of approximately l ?" per year. Since the amount of water moving through the New Horizon <br />spoil is sa much greater, it should oxidize the pyrite much more rapidly and also flush other salts which <br />are contributing to the increase in TDS at a much higher rate. For this reason, a ratio of the discharge at <br />both sites could be used to predict the tune frame of slightly elevated spoil water quality. This ratio, <br />3116", as applied to 1500 years, results in a time frame of 280 years until all the pyrite is oxidized. When <br />considering all the variables involved, this means that it could dissipate within a range of loo to 500 <br />years. The TDS should begin to drop before this time. Vince the pyrite is fully oxidized and other salts <br />are flushed out, the spoil water quality should approach the irrigation water quality, possibly dropping <br />to 300 ppm TDS. <br />Irn acts ?'a Receivir? ?Va?ers <br />Since these spoil springs were never present in the pre-mine landscape, their impact to the quality of the <br />receiving waters must be addressed. The sample point Spoil Spring 1 represents the span water discharge <br />from the New Hon.zon #l Mine and has been monitored since 157. Spoil Spring Z discharges into Tuttle <br />Draw a short distance downstream. Tuttle Draw enters the San Miguel River approximately Z miles to <br />the southwest. <br />Sample site SW-N1 is located in Tuttle Draw immediately upstream of any influence from the mine. <br />Sample data over the past 12 years from sites SW-Nl and Spoil Spring 1 have shown that the TDS of the <br />waters drops significantly when irrigation is active in the area. Therefore, the impacts to the receiving <br />waters will be studied for both cases, with and without irrigation. The irrigation case corresponds to the <br />Septemberl0ctobertune period when flows are fairly low in the San Miguel River. The non-irrigation <br />period corresponds to MarchlApril when flows in the San Miguel are usually at peak. <br />The spoil water inflows from both mine areas influence the quality of Tuttle Draw to a minor degree. <br />However, as these flows enter the San Miguel River where the flow is significantly larger than the Tuttle <br />Draw flaw} the impact is negligible. During periods of irrigation, Tuttle Draw is flowing at a higher rate <br />while the River is running low, which is the time of maximum impact of the spoil water flows. During <br />this period of tirn.e, the increase in TDS of the River ranges from. 620 to 652 ppm, or an increase of 5.1 %, <br />It should be noted that Tuttle Draw flows are always higher in TDS than the River, regardless of the spoil <br />,springs, therefore, the impact from the spoil springs may a ? to 3°?o increase in TDS. During <br />MarchlApril, the river is flowing fast and Tuttle Draw is at low flow, therefore the increase in TDS for <br />the river is only ? ppm, or an increase of 0.4°0. Also, these impacts are for the time when the spoil <br />material is leaching salts at a maximum. As described earlier, the TDS levels will drop as pyrite and salts <br />are leached out of the spoil, lessening the impact to the waters downstream even. further. <br />Calamity Draw is not included in the above table since the spoil springs from both mine areas will not <br />enter this stream. This intermittent stream should not be affected in the long term by the mining and <br />reclamation operation. <br />overall, the effects of the spoil springs are not significant to the waters downstream..