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<br />- III IIIIIIIIIIIIIIII <br />STATE OF COLOI~UU <br />DIVISION OF MINERALS AND GEOLOGY <br />DnpanmeN of Nalurdl Resources <br />1 111 Sherman 51., Room 215 <br /> <br />Denver, Gduratlo 80203 I~ <br />I'hnnc 13U}I Itbh-35h7 ~ <br />E~7( 11(1 p H 1'_-N106 <br /> DEPARTMENT OF <br /> NATURAL <br /> RESOURCES <br /> Roy Ruiner <br /> Governor <br />January 5, 1998 I,m~ s lo~hhe,d <br /> E,ecuu•e Direaor <br /> <br />Mr <br />Michael G <br />Altavilla nachael B. lung <br />. <br />. Dmlrlon Direaa <br />Seneca Coal Company <br />P.O. Drawer D <br />Hayden, CO 81639 <br />RE: Seneca II-W Mine (C-82-057) <br />1996 Annual Hydrology Report & Annual Reclamation Report <br />The Division of Minerals and Geology received the 1996 Annual Hydrology Report (AHR) and <br />Annual Reclamation Report (ARR) for the Seneca II-W Mine on Mazch 3, 1997 and April 4, <br />1997, respectively. <br />The ARR was submitted and is in compliance with Rule 2.04.13. The Division has no comments <br />that need to be addressed by the operator. <br />The AHR was found to be ahigh-quality document, containing the necessary information for <br />analysis. The AHR could be improved by two means. First, Seneca could relate the results to <br />the PHC section of the permit and second, Seneca could use the same scale on the plots where <br />possible. Some are way out of the range of others, but for our purposes, variation in TDS content <br />of 100 mg/1 at a given sampling location is not significant compared to variations of 2 or 3 orders <br />of magnitude, the range over which we aze observing changes at some locations. <br />The Division has a few comments regazding the conformance of the hydrologic system to the <br />predictions in the PHC; <br />Surface Water <br />The quality of the water in the Hubberson Gulch "system" and the Dry Creek "system" have not <br />reached the high dissolved salts levels predicted in the permit. At Hubberson Gulch, the water <br />downstream of NPDES point 006 has increased about 2~0 mg/I, but has reached a maximum on <br />one occasion of only 1700 mg/I, much less than the predicted post-mining concentration of 2200 <br />mg/1. Most measurements indicate levels about 830 mg/I. At Dry Creek, the NPDES discharge <br />point has seen water increase from 1 100 mg/I to nearly 1500 mg/I, but at the monitoring site <br />downstream of the conFluence of that tributary with Dry Creek. the measurements have fallen <br />within the historic range, 1000 mg/I less than predicted. <br />