2012-05-07_HYDROLOGY - C1981010 - Laserfiche WebLink

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`TRAPPER MINEI CERTIFIED Ms. Carla Lenkey Colorado Department of Public Health and Environment WQCD -PE -B2 4300 Cherry Creek Dr. South Denver, CO 80222 -1530 TRAPPER MININI INC. April 18, 2012 Subject: First Quarter 2012 Colorado Wastewater Discharge Monitoring Reports Permit No. CO- 0032115 Dear Ms. Lenkey: P Box 187 Enclosed are Trapper Mine's First Quarter 2012 Colorado Wastewater Discharge Monitoring Reports for the period 01/1/12- 03/31/12. During this quarter, eleven NPDES outfalls were active. Outfalls 001, 002, 011 and 020 discharged routinely throughout the quarter. Outfalls 005, 013, 014, 015, 017, 018 and 021 discharged in response to spring snowmelt occurring in March. Outfalls 008, 009, 012, 016, 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 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 outfalls 011, 020 and 021. Outfall 017 did not have mine water discharged. No exceedances of WET test limitations were observed at any tested outfalls. This winter resulted in average to below average snow pack for the site during the reporting period. However late storms did significantly increase our snowpack before warm temperatures forced a quick spring thaw event. The runoff this season appeared to initially flow on frozen ground and existing snowpack. The runoff event that ensued was significant in several of the discharge watersheds. Despite the warm winter, periods of cold nights and warm days produced a great deal of ice in drainageways. This appeared to further intensify the spring melt event. During routine sampling in March this even appeared to peak. On March 6 peak flows for the period were recorded at most outfalls that discharged. The following week on the 13` outfalls that had not previously discharged had filled their impoundments were discharging at small rates. Significant snowfall at the end of February and the 1 and 2n of March along with cool temps gave way to highs in the 50's on March 6` and T The following week, temps rose into the 60's for much of the remainder of the month. The sharp rise in temperature induced the runoff event during the week of March the 5` The enclosed NOAA weather summary reports show the temperatures and snow depth 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. To further catalog the events of the early March a series of photographs are attached showing the site on March 6` and March 13' and surrounding areas. Please note the stark contrast in the photos over a period of a week and the loss of snowpack. Primary effluent limitations were exceeded at six 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 March 6, 2012 showed an exceedance of TSS at outfalls 001, 011, 017, 020 and 021 and that of iron at outfalls 017, and 020 due to the spring runoff. Primary effluent limitations for TSS and iron were also exceeded at outfall 018 on the 13` due to runoff. This outfall sits at higher elevation than the others and showed a delay in snowmelt at this 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. Craig, Colorado 81626 (970) 824 -4401