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L <br /> <br />detection of pond leakage and to augment the original <br />• monitor wellfield which was constructed in 1980. These <br />e>:fisting wells were located 150-200 feet away and would not <br />provide sufficient warning to prevent leakage in to the <br />Animas River, In addition, it was found that three of the <br />previously drilled monitor wells, nos. 1, 16 and 22, had <br />been destroyed. Numbers 1 and 16 should, however, be <br />repaired or replaced to provide information on ground water <br />east of the ponds. <br />LEAKAGE TEST <br />The leakage test consisted of the gravity injection of <br />sodium fluorescein dye into the previously described <br />injection wells on the new pond. Time did not permit <br />injection into the wells on the old pond, however dye blocks <br />were placed in the injection wells off set to M4B and M4C, <br />which had water standing in them. No dye was observed in the <br />corresponding monitor wells. <br />Oye was also placed in monitor well MW-2 in an attempt to <br />estimate the rate of ground water movement. Because of the <br />high concentrations of dye remaining in this well throughout <br />the program, it was not possible to sample ground water <br />quality. <br />• It was originally proposed to inject into a single well <br />offset 75 feet up hydraulic gradient from each of the 3 well <br />clusters of monitor wells. Flooding was commenced in such an <br />injector in pattern 3 on the new pond on September 12th. Sir, <br />12 ounce dye blocks were placed in the injection well and <br />water was pumped from the decant pond using a 1/1/2 >; 1/14 <br />inch centrifugal pump, maintaining the liquid level at the <br />top of the casing. Flows were measured with a 1" F:ent <br />totalizing flow meter. Because of very slow injection rate, <br />0.4 gph, and the large volume that would have to be flooded <br />before breal: through would occur at the nearest monitor <br />well, the operation was shut down on September 17 th after <br />having pumped 199 gallons. The program was revised to inject <br />into 10 foot offset wells as previuusly described. <br />Simultaneous injection was commenced at M1A, M1B and M1C on <br />September 17th. On September 19th all the remaining <br />injection wells on the new pond, with the er.ception of M3C, <br />were placed in operation. A single 12 ounce block of dye was <br />placed in each well. This size block will dilute to 1 ppm in <br />26000 gallons of water. One ppm is the lower limit of <br />detection by optical fluorescence. Well M3C was not placed <br />in operation as by this time the shoreline of the decant <br />pond had risen to within 10 feet of the injection well, <br />which remained completely dry, testifying to the <br /> <br />-7- <br /> <br />