2012-08-30_HYDROLOGY - C1981019 - Laserfiche WebLink

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COAL s COMPANY f'C PRODUCTION Ms. Kelly Morgan Colorado Department of Public Health and Environment Water Quality Control Division 4300 Cherry Creek Drive South Denver, CO 80222 -1530 5731 State Highway 13 Meeker, Colorado 81641 August 27, 2012 PuG 3 0 VA/ Rec \a{ g oo ' Wing & Sa RE: Upset Conditions of Total Suspended Solids at Outfall 010A, Colowyo Coal Company L.P. (Colowyo) CDPS Permit No. CO- 0045161. Dear Ms. Morgan, Per my voicemail on Thursday August 23, 2012, this letter is to inform you in writing of the upset conditions of Total Suspended Solids (TSS) for the month of August 2012. Colowyo sampled Outfall 010A on August 8, 2012 and laboratory analysis was received on August 21, 2012. The Outfall 010A results indicated elevated TSS concentrations (139 mg /L). The elevated TSS concentration is above the Daily Maximum limit (70 mg /L). However, the Settleable Solids limits were not exceeded at this outfall during this event. Colowyo believes the TSS concentration for this outfall reflects the development of algae in the pond due to regional uncharacteristic weather patterns which qualifies as an upset condition. The sample taken on August 8, 2012, was retested to ensure that the first results were correct. The rerun showed results that coincided with the original results. Colowyo does not believe the upset conditions of Total Suspended Solids are a result of sediment flowing into the pond, but rather the development of algae in the pond due to regional uncharacteristic weather patterns. Colowyo has experienced unseasonably high temperatures during the months of May, June, July and August, 2012. Colowyo has received very limited precipitation during the month of August 2012, and the precipitation events were short in duration. East Taylor Pond does receive inflow from a small spring; however, flow rates are minimal and steady with minimal TSS loading. East Taylor Pond was dredged during August of 2011, and 2088 yards of material was removed form East Taylor Pond. Please see attached climatological data. Colowyo's historical laboratory analysis data does not show a trend toward any type of elevated levels at this outfall. The elevated levels Colowyo does experience are associated with either a precipitation or runoff event. Colowyo does not believe that the elevated levels are related in any way to a lack of proper pond function as routine inspections of the pond show that it is functioning as designed in accordance with Part II .A. 7. b. of the permit. Colowyo currently has sediment control logs (wattles) installed between East Taylor Pond and Outfall 010Ato further minimize TSS concentrations. The facility has also commenced dredging of the East Taylor Pond for dredging on August 24, 2012, to ensure that sediment is not an issue. Colowyo will continue to closely monitor this and all other outfalls for indications of proper impoundment function. es Prof).