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~: C crp~us ~ Yampa Valley iii iiiiiiiiiiiiiiii Cyprus Yampa Valley Coal Corporation 29587 Routt County Road #27 Oak Creek, Colorado 80467 303-879-3800 March 26, 1993 Ms. Anne Ihlenfeldt Colorado Department of Health Water Quality Control Division Attention: Permits and Enforcement 4300 Cherry Creek Drive South Denver, CO. 80222-1530 RECEI~IED MAR 3 ~ 1993 Division of Minerals ,t. Geology Dear Ms. Ihlenfeldt: Re: Discharge Monitoring Reports; NPDES Permit CO-0027154. CvDrus Yampa Vallev Coal Coro. Enclosed, please find the referenced DMRs for the month of FEBRUARY. only outfalls 001; 003, 005, and 006 showed discharge during the period in question. Outfalls 002, 004, 007, 008, 009, 010, 016, and 017 all showed NO DISCHARGE. Wasteload Allocation Data for the pertinent outfalls has been provided in summary format, and is reflected on the enclosed forms. As discussed, Outfall 005 showed no discharge for the first two weeks of the month. As a result, only two full-suite samples were collected for this outfall, both of which were high in iron. The primary effluent source for this outfall consists of underground mine water discharge, the volume of which was increased during de- watering projects over the latter part of the month. It is thought that these dewatering projects are the cause of the exceedence. Due to the lag in receiving analysis data from the lab, CYVCC was not aware of the exceedence until the first week in March, at which time steps were immediately taken to modify flow volumes and routings in order to offset the iron problem at this outfall. Subsequent data from March shows that the iron levels in effluent from this pond have declined below the compliance level during the second week of the month (data for the remainder of March is still pending). In order to offset the iron loading from the mine discharge, we have intensified our recycling efforts, and have decreased our rate of de-watering to this outfall. It is anticipated that the de-watering projects will be completed sometime in late May or early June, at which time dewatering flow rates will return to the previously observed base.