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:y <br />P•lemo-Roger Funston <br />February 22, 1980 <br />Page -2- <br />aquifer. Add to Map III-1 coal subcrops under the 'dilliams Fork <br />and Yampa Rivers. <br />3) The coal aquifers have not been described. Provide information <br />on their hydraulic characteristics, water quality, and zones of <br />recharge and discharge. <br />4) The baseline water quality for both surface and groundwater has <br />been limited to constituents in the effluent limitations. The <br />data should also show seasonal variations of major and minor <br />ions, and trace metals. <br />a) Present surface water data in three categories - the Yampa <br />River above the confluence, the Yampa River below the confluence, <br />and the Williams Fork River. <br />b) Groundwater data should be presented on the basis of individual <br />aquifers (Yampa alluvium, Williams Fork Alluvium, Trout Creek Ss, <br />diddle Ss, Twenty tgile Ss, and the coal aquifers). <br />5) Tables III-II and III-12 provide data on wells and springs in the <br />vicinity of the minesite. Which are wells, and which are springs. <br />These wells and springs should be located on a map. Provide the <br />seasonal discharge for each spring. Provide the seasonal water <br />quality for each spring. <br />6) The baseline conditions at this minesite include the effects of <br />past mining activities (surface and underground). <br />a) What effect has past underground mining activities had upon <br />groundwater quality and movement? <br />b) What effect has previous surface operations had upon groundwater <br />movement: Has a spoil aquifer reestablished itself? liow does the <br />water quality in the spoils aquifer compare with that 'in natural aquifers? <br />c) What is the source of water pumped from the N9 mine? Provide <br />information on the quality and quantity of this water. <br />PROBABLE HYDROLOGIC COPJSEQUENCES - This section should be expanded to <br />discuss possible changes in surface o-;ater quality and quantity, ground- <br />water quality and quantity, and the recharge, movement, and discharge of <br />groundwater. (Discuss each ground~•~ater aquifer separately). Changes <br />may or may not occur, but each aspect of the hydrologic system should <br />ba discussed in terms of possible effects. Data and analysis should be <br />used to support all conclusions. <br />In addition some specific topics that should be discussed include: <br />1) De~vatering of coal and/or sandstone aquifers. <br />2) The possibility of a temporary reversal of the <br />piezometric surface in some aquifers during mining. <br />This analysis should consider the possible effects <br />upon surface flow and alluvial aquifers under a variety <br />of flow conditions (low, average, and high). <br />