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Fish Creel: Alluvial Wells
<br />Water quality is monitored at several alluvial wells located along Fish Creel:. Alluvial wells going downstream
<br />include 006AY-1, 006 -AZ -3, AVF-13, 006 -AW -2 (abandoned in 2003), AVF-14, AVF-15, 008 -AU -3 and 008 -AW -
<br />3. Figures 4j through 4q present water quality data (conductivity) for these sites, respectively. Tables 8m through 8t
<br />present a summary of period of record water quality data for these sites, respectively.
<br />Water quality data indicates that prior to 1995 there were no significant influences from discharges from disturbed
<br />areas to Fish Creek upstream of alluvial monitoring wells. Water quality is characterized by sodium bicarbonate
<br />dominance, TDS on the order of 760 mg/l, and a tendency for dominance of sodium, calcium and sulfate.
<br />Well data indicates some mining influence on water quality over the period 1995 to date. When compared with
<br />upstream alluvial Well 006 -AY -1 (Figure 4j), Well 006 -AZ -3 (Figure 4k), located downstream of discharge site 115,
<br />has exhibited an increasing trend in conductivity (1,300 to 1,800 umhos/cm) and total dissolved solids (600 to 1,500
<br />mg/1) since 1995. This is not as readily apparent in the alluvial wells located downstream of 006 -AZ -3. Water quality
<br />data for the alluvial wells also exhibits seasonal fluctuations, reflecting recharge of the alluvium during spring runoff.
<br />(b) The application shall contain additional information, which describes the recharge, storage, and discharge
<br />Zn
<br />characteristics of aquifers and the quality and quantity of ground water for the proposed permit and adjacent
<br />areas, according to the parameters and in the detail required by the Division. The application shall also
<br />provide well locations and reported yields from all wells within the proposed permit and adjacent areas,
<br />which are registered with the Office of the State Engineer.
<br />Twentymile Park, which includes the proposed permit and adjacent areas, lies within a semi -arid climatic zone with an
<br />average annual precipitation of only 16 inches. With the exception of the spring snowmelt, which results primarily in
<br />surface runoff, most of the precipitation received is lost through evapotranspiration and sublimation. As a result, the
<br />amount of precipitation available for groundwater recharge is limited.
<br />All ground vvatei aquifers ii7 the general arca, ex%Xpi elle alluvial aquifets, are recharged by infiltration in uuLcrop
<br />areas. Outcrop areas for the principal groundwater aquifers are shown on the Twentymile Sandstone Potentiometric
<br />Surface Map (Map 33).
<br />BEDROCK AQUIFERS
<br />The conii7uratioin of the potent)onnetric surface for the Wadffe overburden aquifer (Map 13, Twentymile Park
<br />Hydrology) indicates the direction ofground water movement in this unit. Given that the strata in the lower portion of
<br />the ,'Villiams Fork Formation (ic: `.'adge Overburden , V'adgc Scam, VIVadge/Wolf Creek Interburdcn, and `VIVolfCreck
<br />Seam) generally function as a single hydrologic unit, any ground water movement within this unit would be similar.
<br />Ground water movement is generally oriented perpendicular to the potentiometric contours in the direction of
<br />decreasing potentiometric elevation. The map indicates that ground water tends to move from the recharge areas at
<br />the outcrops of these units, near the southern and western margins of Twentymile Park Basin, toward the center of the
<br />basin, reflecting the structural dip of the lithologic units. The general trend of ground water movement in the Permit
<br />_^ rea is to the north and northwest. It should be noted. hovrever, that due to closed basin conditions and the lack of
<br />:iC rt- unT�arrF
<br />ground Aer oiovemeint from the Vadge/Wulf Creek Irnterburden and Wolf Creel, Seam, any ground
<br />ai" lt' alovai-nent wvithiin these ui-Jts L'v'Gull be c'�1iStrained bpi the hot`Eonn of coal st ucture. as showii oil Mal) FX53-M1,
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<br />c�laraCter;sties o.`speci ze inter-a'Is `.;')thin tine "Yacht 0,verburden v'e tested titi:izrng temporary ,Veli pacl'ers and
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