2012-11-05_HYDROLOGY - C1982057 (2)

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�ZIVZCA Coal company Seneca Coal Compan October 24, 2012 Colorado Department of Health RECEIVED WQCD -PE -B2 f r 4300 Cherry Creek Drive South J'2 Denver, CO 80246 -1530 Divisio,l c„ r;-�ciamation, Mining and Safety RE: Quarterly Discharge Monitoring Report for Seneca Coal Company, Permit CO- 0000221 Dear Sir or Madam: Pursuant to the quarterly reporting requirements contained in Colorado Discharge Permit CO- 0000221 for the Seneca Mine Complex, enclosed find the third quarter 2012 discharge monitoring reports for Outfalls 005, 006 and 008 to 017. In this quarter, intermittent discharges were observed at Outfalls 010, 013, 015 and 017. No flows were observed at Outfalls 005, 009, 011, and 014. All other Outfalls discharged continuously. One excursion of an effluent limit occurred this quarter. On July 17, a pH value of 9.07 was measured at Outfall 013. The limit is 9.0. There was no discharge at this pond during a visit at 9:40 AM on July 16. A thunderstorm occurred later that day, caused the Outfall to start discharging again. Discharge from the Outfall stopped early in the morning of July 18, and has not discharged since then. The high pH is mostly likely due to the presence of algae in the Outfall's pond. The phenomenon of algae causing high pH values is well documented. I have attached the first two pages of one such article to this cover letter, which was taken from this website: https: /, /srac.tamu.edu /index. cfm/ event /getFactSheet /whichfactsheet /205/ I have also attached a photo taken on July 26, which indicates the presence of algae. Seneca considers this to be an upset condition, in that 1) we can identify the cause (as described above) and 2) this sedimentation pond was being properly operated and maintained at the time. Please contact me at 970 - 276 -5209 if you have any questions. Sincerely, Dennis Jones Hydrologist I cc: Mr. Jared Ebert Division of Reclamation, Mining and Safety 1313 Sherman Street, Room 215 Denver, CO 80203 -2273 Seneca Coal Company • P.O. Box 670 • Hayden, Colorado 81639 Telephone (970) 276 -5217 • FAX (970) 276 -5222