2011-07-27_HYDROLOGY - C1981010 - Laserfiche WebLink

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( TRAPPER MINE CERTIFIED Colorado Department of Public Health and Environment WQCD -PE -B2 4300 Cherry Creek Dr. South Denver, CO 80222 -1530 To whom it may concern: P.O. Box 187 TRAPPER MININI INC. July 22, 2011 Subject: Second Quarter 2011 Colorado Wastewater Discharge Monitoring Reports Permit No. CO- 0032115 Recove JUL 2 l 201 Division of Reclaman, Mining and SafeiJ Enclosed are Trapper Mine's Second Quarter 2011 Colorado Wastewater Discharge Monitoring Reports for the period 04/1/11- 06/30/11. During this quarter, eleven NPDES outfalls were active. Outfalls 001, 002, 011 and 020 discharged throughout the quarter. Outfall 009 discharged only once in May. Outfall 017 discharged periodically each month. Outfalls 013, 018 and 021 discharged early in the quarter until mid May to Early June. Outfalls 022 and 024 discharged during May and June. Outfalls 005, 008, 012, 014, 015, 016, 019, and 023 did not discharge during the quarter. Trapper Mine and Northwest Colorado in general experienced an exceptional winter. In many locations it was a record setting winter. Snow pack was deeply accumulated around the mine site, especially at higher elevations. The snow was slow to melt due to unseasonably cool temperatures in late winter and early spring. Accumulated snow was still visible on many parts of the mine site at higher elevations until mid to late May. Additionally rain fell through much of the quarter. April was the wettest on record for the site at 3.64" of precip for the month. All of this accumulated moisture produced a great deal of runoff. Eleven sites discharging at one time is the most active outfalls the site has had. 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 NOAA 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 outfall 011, 017 and 020. No exceedances of WET test limitations were observed at any tested outfalls. Primary effluent limitations were exceeded at three outfalls during the quarter. These exceedances were in direct response to snowmelt and or precipitation events resulting from snowfall and rain on the site. Samples taken April 5, 2011 showed an exceedance of TSS and iron at outfalls 002, and 020 due to a snow storm the day before. Above freezing temperatures melted the snow within a few days and consequently increased runoff during this period. On May 10 TSS was exceeded at outfall 024. Measurable rain had fallen the night before, but due to the elevation of outfall 024, snowmelt from Aspen and mountain brush covered north facing slopes had created the discharge at the site. 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. To better catalog snowpack and subsequent snowmelt conditions on the site please see attached photographs. Each photo is designed to be a representative image of the areas and watersheds contributing to runoff on the site for the date noted. 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 TSS 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. Craig, Colorado 81626 (970) 824 -4401