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,J <br />E~~A <br />S Coal Company Seneca Coal Company <br />October 31, 1997 <br />Industrial Permits and Enforcement Program <br />Colorado Department of Health <br />WQCD-PE-B2 <br />4300 Cherry Creek Drive South <br />Denver, CO 80222-1530 <br />Attn. Carla Lenkey <br />RE: IIpset Condition at Discharge Point 006, Permit No. CO-0000221 <br />Dear Ms. Lenkey, <br />Per our phone conversation yesterday, this letter serves to update <br />your Division of the status of the upset condition at Pond 006 <br />reported to you originally in a letter dated September 26, 1997. <br />The rainfall event referenced in that letter amounted to 4.36 <br />inches from September 18Ch to the 22°d. This is equivalent to 26 <br />percent of the average annual amount observed at the NOAA Hayden <br />Weather Station located seven miles away. The highest 24 hour <br />total was 1.80 inches, which was above the 10 year, 24 hour event <br />in this area of 1.70 inches. The 100 year, 24 hour event for this <br />area is 2.50 inches. <br />As a result of this high rainfall, this sediment pond was filled <br />with sediment to within one foot from the principal spillway <br />elevation. In order to facilitate the removal of this sediment, a <br />ditch was dug through the dam at an elevation of about one foot <br />below the principle spillway in order to remove the remaining <br />water. This ditch started to discharge water at 2 PM on October <br />29t°, and was filled back in today at 10 AM. During that period, <br />approximately 1.5 acre-feet of water was discharged. A sample of <br />this water was collected at noon on the 30t°. Although no lab <br />results are back yet, it is certain that the water discharged <br />exceeds the effluent limits for suspended solids and total iron. <br />Now that the ditch through the dam has been backfilled, any water <br />entering the pond will once again be discharged through the <br />principle spillway. Sediment removal has begun around the <br />principle spillway first, and will proceed until as much sediment <br />as possible is removed from the pond. This will take about a month <br />to complete. Please feel free to call me at 970-276-5109 if you <br />have any questions. <br />1 <br />Seneca Coal Company • P.O. Drawer D • Hayden, Colorado 81639 <br />Telephone (970) 276.9707 • FAX (970) 276014 <br />