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Mayo and Assocla~es, LC <br />• sediments is small relative to the recharge and discharge rates, and 3) the alluvial sediments <br />are in good cotmection with surface water flows. The overall storage capacities of alluvial <br />spring groundwater systems are large. <br />5.2 Mantle Cover Springs <br />Mantle cover springs display large seasonal discharge variations. These springs have very <br />large springtime high-flow discharge rates, while each commonly ceases flowing entirely <br />during the fall and winter months. This suggests that, like the alluvial groundwater systems, <br />the mantle cover groundwater systems have an appreciable capacity to transmit water, but <br />that the storage volumes of these systems are small relative to the recharge and discharge <br />rates. <br />• <br />Two springs in particular, G-22 and CR-12, occasionally discharge copious volumes of water <br />(Figures l lb and ] lc, respectively). Spring G-22, which has had a measured discharge rate <br />greater than 450 gpm, is located near the bottom of the Sylvester Gulch drainage. The <br />extremely large volume of this discharge indicates that it likely has an good hydrodynamic <br />connection with a surface water feature and that it is greatly influenced by seasonal <br />snowmelt. Spring CR-12 is also likely influenced by surface water. Mr. Ron Hanna of <br />WATEC, who has for several years perfornred spring discharge measurements for West Elk <br />Mine, suggests that this spring is highly influenced by up-stream discharge of surface flow, <br />and that the actual discharge of water from CR-12 is probably meager (personal <br />communication, 1998). The fact that each of the mantle cover springs dry out completely in <br />. the fall suggests that they are not sustained by areally extensive groundwater systems. <br />Characterization of Groundwater Systems in the Vicinity of the West Elk Mine, Somerset, Colorado <br />29 January 1999 <br />Page 63 <br />