2008-01-24_HYDROLOGY - C1981010 - Laserfiche WebLink

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4AlPPB& MINIBG IBC. January 15, 2008 CERTIFIED Ms. Carla Lenkey ~~AN ~ 42008 Colorado Department of Public Health and Environment t~ivision or WQCD-PE-B2 Minin keclama~on, 4300 Cherry Creek Dr. South 9 and Safety Denver, CO 80222-1530 Subject: Fourth Quarter 2007 Colorado Wastewater Discharge Monitoring Reports Permit No. CO-0032115 Dear Ms. Lenkey: Enclosed are Trapper Mine's First Quarter 2007 Colorado Wastewater Discharge Monitoring Reports for the period 10/1/07-12/31/07. During this quarter, five NPDES outfalls were active. Outfalls 001 and 002 discharged routinely throughout the quarter. Outfalls 011, 020 and 021 discharged in response to intense fall precipitation event in early October. Outfalls 005, 008, 009, 012, 013, 014, 015, 016, 017 018, 019, 022, 023 and 024 did not discharge during the quarter. Values reported on the enclosed DMRs represent the maximum (or minimum as applicable) monthly/daily values generated at each outfall during the quarter. Also enclosed are monthly NOAH weather summaries for the reporting period and WET test report forms as applicable. Three outfalls, were sampled for WET analyses during the quarter. Two species acute tests were completed at outfalls Ol.l, 020 and 021. No exceedances of WET test limitations were observed at any tested outfalls. All active outfalls experienced intense fall precipitation events during the quarter. On October 15` and god the site recorded 0.44 and 0.42 inches of precipitation respectively. The enclosed NOAA weather summary reports show the temperatures and precipitation measurements for the period mentioned. Daily precipitation measurements are recorded at 7:00 a.m. as well as daily maximum and minimum temperatures from the previous 24 hours. Primary effluent limitations were exceeded on two outfalls, (011 and 020) for TSS. The alternate limitations will be applied to outfalls 011 and 020 due to the aforementioned precipitation event. Samples were taken at each outfall during routine weekly monitoring. The samples taken October god exceeded limitations due to heavy runoff associated with the precipitation event. Heavy rains and cool weather in the final week of September may have attributed to saturated soils and water levels in ponds at spillway levels. The alternate limitations for Settleable Solids, applicable in the event of discharge caused by precipitation (or snowmelt) less than or equal to the 10-year, 24-hour precipitation event, was met at all outfalls. No exceedances of primary effluent limitations for pH occurred during the quarter. Trapper is required to maintain sediment levels in ponds at or below 60% of the pond volume. All outfalls have been properly maintained and no ponds exceeded the 60% threshold for sediment accumulation. All structures operated properly and were not compromised in any way. The exceedances occurred solely in response to discharge caused by precipitation and/or snowmelt, therefore the alternative limitations are applicable for this event. All other operations were properly conducted concerning the sediment control structures at Trapper Mine. P.O. Box 187 Craig, Colorado 81626 (970) 824-4401