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Rimrock Mine Annual Water Report 1993 and 1994 RFC~iv~o Permit C-89-074 JAN ~ ~ ~gg5 plvision o1 wt1°erals & Geology Surface Water- Year 1993 During year 1993, the mine was active and the pit area west of Engleville Gulch was opened up. The runoff from all disturbed area was channeled to the sediment pond located near the low point on the north end of the permit area, adjacent to Engleville Gulch. A principal and emergency spillway from the pond both discharge directly into Engleville Gulch. During 1993, the staff gage located at the bridge (north end of the permit area) did not record any significant flows during the year. The Gulch did flow a few gallons per minute in the Spring in response to snowmelt. No large events were recorded in the Gulch. No water quality is available for the Gulch. All disturbed area flows were kept out of the Gulch and no sediment from the newly disturbed area was delivered to the Gulch. Also, during 1993, the sediment pond did not discharge from either the principal or emergency spillways. The pond discharges are covered by an NPDES permit with the Colorado Department of Health. All quarterly monitoring forms (DNB's) reported no discharge. The Engleville Mine Discharge point, (END) located immediately east of the permit area, did discharge and water samples were taken on a quarterly basis and analyzed. The analysis is enclosed in this report with the ground water sampling analysis. This mine discharge is from the extensive old Engleville Mine, which covers a few square miles underground to the south, in the Starkville Seam. This discharge was recorded prior to Rimrock Mine startup and is not the responsibility of Rimrock Coal Company. It is monitored to provide information on the overall hydrologic balance. During 1993, flows of approximately 0.25 gallons pre minute were measured quarterly for the Engleville Mine Discharge. This is similar to pre-mine levels and the water quality is also similar to pre-mine data. Overall, it was evident that any Rimrock Mine activities affected the prevailing hydrologic balance.