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<br />t <br />and causing muscle damage to my arm, while performing this weekly <br />monitoring. This problem will only will only get worse with the <br />addition of the new Points 015, 016, and 017 in the Seneca II-W <br />South area, which will all be extremely difficult to access. <br />I propose that the weekly pH, flow (manual measurement), and <br />oil/grease (visual) monitoring be changed to monthly at all <br />points except 003 (Point 003 contains runoff from the Seneca II <br />shop area and truck wash, weekly monitoring there would help <br />assure that no contaminants from that area are released). Flow <br />will continue to monitored continuously at all points by way of <br />flow recorders (except in the winter when the floats freeze up). <br />I have attached, for your review, a report that indicates all pH <br />excursions that have occurred at our three mines since 1980. Also <br />attached are pH plots for all NPDES points. The excursion report <br />indicates that only two sites have experienced excursions. Point <br />004 (NPDES4) had 6 excursion out of 727 visits. These excursions <br />occurred in 1984 to 1987. Point 006 (NPDES6) had 8 excursions <br />out of 239 visits. These excursions occurred in 1990 and 1991. <br />All of these excursions were likely the result of algae blooms, <br />which converts bicarbonates into carbon dioxide and free <br />hydroxide, which raises the pH. Both of these ponds were <br />relatively new at the time of the excursions, when total <br />dissolved solids (TDS) values were low. As the TDS values <br />increase with time, so does the buffering capacity of the water, <br />and the algae blooms have less of an effect on the pH values. <br />If your Division agrees with my proposed reduction in monitoring, <br />please inform me with a letter that I may forward to the CDOH so <br />that I can have our NPDES permit amended. Your attention to this <br />matter is greatly appreciated. <br />Sincerely, <br />G d~ <br />Dennis Jon <br />Hydrologist I <br />Enclosures <br />