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<br />Water Inflow L Discharge <br />Previous hydrologic reports have given evidence that the inflow of <br />water to the mine can be attributed to dewatering of a perched <br />aquifer as well as surface water infiltration alone the faults of <br />the graben. During idle nears a clear picture of rnine water <br />inflows was obtained because the mechanism of mine dewatering_ was <br />direct discharge to NPDES point 002. The quantity of water <br />discharged was recorded on a meter and a correlation with <br />precipitation was msde. The steady decrease in the amount of <br />water pumped frorn the mine during the idle years is evidence of <br />iPie creation of a dcwatered zone in the saturated coal strata. <br />The decrease is also evidence that there is little comrt~ur:ication <br />with the comparatively large aquiver witP~in the East Salt Creek <br />alluvium across the west fault of the graben. <br />WitFi the resumption of mining. water was not. disci~argeii morn tyre <br />mine; rather. ~•~ater was used ar stored in sumps unclcrgrour~d in <br />anticipation of increased needs. Since water was not bein+a <br />discharged regularly. correlat.iun of disctr~rges with prucipit.ation <br />and monthly inf-low for the year was not oc+ssible. The majority of <br />±'I-ie water that infilt.rat.ed the rr~iiie wac used for dose supuression <br />tl~ie m i n i nq cvc i e . ihereforr• , rnine dew~t er ! nu_ became a funct i or. of <br />t!-~c amount o` COd i produced. <br />o-Jiu_n mining resumed, additional area i:~: the saturatc•c portion of <br />t I i e graben Was opened i ncreas i nq the r i uw of Water into the rti i r ie. <br />Water has also been imported to the it.o for use on :-odds and at <br />Lf:e bathhouse. Estimates o= the .mount .P ~~~:~ter use_+ indiu;yte <br />that the inflow of water- has incrcasee t'. approximately ..6 <br />gci ions per rr:inute from thF• O.b gal Ions +er minute reG+orted for <br />ihc• last period. A tabulation of water inflow/outflow r=rom the <br />mint- is included as Table i. -cable 2 i_, ~ record or" t.h~e flows for <br />tl-ic• aer i od i 981 to 1939. <br />Sours of Water Inflow <br />!~s detailed in pr-evipus reports. tl~e water flowing into the mine <br />seems to be v mix of water infilt.rat.inq tt,e uraben along the. <br />fau 1 t5 and water w!-i i ch i s storerJ i n the coa 1 seam. Tl ic~ zone of <br />saturation of the coal seam was initially estimated using the <br />results of exploration drilling. Tire driilinq indicated that <br />holes in the hic•Clane graben were dry: specifically, holes 7-15-3 <br />and 7-21-1. Additionally, a piezorneter instailcd downdia frorn the <br />mine O'Jt.51de of tiny graben has not realized water to date. Since <br />the weI 1 is down-dip and is dry. ~a1t Creek surmises tl-gat tf~e <br />water flowing into the mine is from a perched aquifer in the area <br />of tyre coal mine. <br />Page - Z <br />2/19/90 <br /> <br />