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11-?5~9~ TL'E lO~Ja FaS J03 7b:OJ90 <br />E <br />S Cwl Compu~y <br /> <br />CDPHE ^9CU <br />NOU d5 1997 <br />Ill lllllllllllll III <br />999 <br />Seneca Coal Com <br />1, 1997 <br />Industrial Permits and Enforcement Program <br />Colorado Department of Health <br />WQCD-PE-S2 <br />4300 Cherry Creek Drive South <br />Denver, CO 80222-1530 <br />Attn. Carla Lenkey <br />RE: IIpeet Condition at Discharge Point 006, Permit No. CO-0000221 <br />Dear Ms .~ Lenlcey, ~ ~ ~ ~ ~ ~ - <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 18"' to the 22°°. 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 2.5o 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 />29"', and was filled back in today at 10 AM. Durinq that period, <br />approximately 1.5 acre-feet. of water was discharged. A sample of <br />this water was collected at noon on the 30`°. Although_ no lab <br />results a=e $ack yet, ~it is ceitaiii 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 />moot <br />Senses Coei Company • P.O. Drewar D • Hayden. Colorado 81639 <br />Telephone (970) 2763707 • FqX (970) 2763074 <br />