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~~~~m <br />July 24, 1996 <br />Larry Henderson <br />Trapper Mining Company <br />P.O. Box 187 <br />Craig, CO 81626 <br />RE: Ground-water Sampling <br />Dear Larry: <br />~oOp~T <br />The third quarter water quality samples at the Trapper Mine are typically <br />pump samples unless the well does not produce an adequate rate. Bail samples are <br />used for some wells in this case. The third quarter pumping over the years has <br />demonstrated that the field parameters stabilize much more quickly than three casing <br />volumes as is typical in ground water wells that are sampled frequently. Therefore, <br />the stabilization of the field parameters is also used as a criteria for taking the sample <br />during the third quarter. Several of the wells during the third quarter are pumped at <br />least three casing volumes. During the third quarter sampling only one of these <br />wells, GB2, showed a significant change in the field parameters during the August of <br />1995 sampling. Prior years of sampling of well GB2, the field parameters have not <br />changed significantly with pumping time. Some of the wells are not pumped three <br />casing volumes due to the very low yield from the well. The quantity of water <br />storage in some of the deep wells is large and, therefore, the stabilization of the field <br />parameters is used instead of pumping three casing volumes because of the time <br />required. Wells GB2 and GB5 were pumped for 5.9 and 3 casing volumes during the <br />third quarter sampling in 1995. Well GAI had to be bailed due to the well <br />containing a very small amount of water. Well GA2 was not sampled because it had <br />gone dry. Wells GC1, GC2 and GC3 had casing volumes pumped from 1.~7, 3.8 and <br />5.8, respectively. Well GC1 was pumped only 1.7 casing volumes because the well <br />was running dry. Well GD3 was pumped for seven casing volumes while wells GE1, <br />GE2 and GE3 were pumped for from 0.2 to 1.1 casing volumes due to their field <br />parameters being stable and the large volume of storage in these wells. Well GF2 was <br />pumped for 0.8 casing volumes due to the large amount of storage in this well. Well <br />GF4 is a flowing well that flows at only approximately 0.10 gpm. Therefore, only <br />0.04 casing volume was produced from this well. Wells GFS, GF6, GF7 and GF11 <br />HYDRO-ENGINEERING <br />4685 South Magnolia Casper, Wyoming 82604 Ph (307) 266-6597 Fax (307) 266-6597 <br />