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INTRODUCTIOtV <br />This report presents the results of pump tests conducted on test wells <br />NNG-10 and NNG-21 of the proposed Northern Natural Gas coal mine near t•teeker, <br />Colorado. <br />NNG-10 <br />Test well NNG-10 is located on the south limb of a large synclinal basin <br />near the entrance to the existing Sewanee Mine. The well will be used as <br />a water supply for mining operations. The well aras drilled through an inter- <br />bedded sequence of sands, shales and coal. The well was cased with five and <br />one half inch (o.d.) casing and cemented to a depth of 1146 feet. The casing <br />was perforated in three sand zones at depths of 580-565 feet, 712-752 feet, <br />and 996-1002 feet. The casing was perforated at four shots per foot. On <br />October 12, 1977, a 4 inch diameter, submersible pump was set at depth 250 <br />feet. An air line, for water level measurement, was installed to depth 240 <br />feet. <br />A 5 hour pump test was conducted by this firm on October 17, 1977. The <br />results of the test are presented on Table 1. The pump test produced an average <br />flow of 28 gallons per minute. The water level was drawn down from an initial <br />depth of 20.5 feet to 250 feet (pump elevation) in 8 minutes. The recovery <br />was monitored for approximately 2 hours during trhich less than 10 feet of <br />recovery was observed (i.e., the pressure gauge on the air line showed 0 psi). <br />At that time, electrical problems made it necessary to restart the pump. <br />After the pump was shut off, recovery was again observed during a 2.4 hour <br />interval, and no pressure was observed in the air line (i.e., less than 10 <br />. feet of recovery was observed). <br />Because of the very low recovery rate (less than 4 feet per hour), it <br />was decided that an adequate water supply (100 gallons per hour minimum) could <br />-1- <br />