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Ms. Carla Lenkey, CDHPE <br />April 28, 1998 -page 2 <br />sample was collected, discharge was estimated at approximately 93 cfs. An inspector from the <br />Division of Minerals and Geology and a representative from Trapper marked the high water <br />level occurring in the pond spillway at the time of this event and measured the flow velocity. <br />A subsequent survey of the pond spillway was completed to determine cross-sectional area and <br />flow was estimated from this information. The calculated 10-yeaz, 24-hour discharge for the <br />pond at outfall 002 is 28.9 cfs. since the measured flow clearly exceeded the design flow, the <br />alternative limitations for dischaz a caused reci itation realer than or 0- . <br />ear, -our recipitation event apply. The outfall was in com liance with these limitations. <br />It should be noted that as ocumen to e G Inspection Report dated 3/26/98, flow was <br />measured at approximately 7.4 cfs at 11:40 a. m. on the day this sample was collected. One <br />hotu later, flow had increased to over 11.5 cfs. At approximately 4:00 p.m., flow had <br />increased to 93 cfs and the water sample was collected. The increase in runoff during the day <br />was attributable solely to snowmelt. Significant flooding in Craig, Colorado was documented <br />to occur on the same afternoon. A review of the enclosed weather data shows an unseasonable <br />warming trend occurring during this time frame. <br />At outfall 005, the primary 30-day average and daily maximum limitations for TSS and the <br />primary 30-day average limitation for total 'von were exceeded by a sample collected 3/26/98. <br />However, the alternate daily maximum limitation for settleable solids applicable in the event of _ <br />discharge caused by precipitation less than or equal to the 10-year, 24-hour precipitation event, <br />was met. This pond had not dischazged prior to this date during the quarter. Discharge <br />occurred solely in response to snowmelt runoff and as a result, the alternative limitations are <br />applicable. <br />At outfall 013, the primary 30-day average and daily maximum limitations for TSS and total <br />iron were exceeded by a sample collected 3/25/98. A prior sample, collected 3/18/98, was in <br />compliance. [n addition, the alternate daily maximum limitation for settleable solids <br />applicable in the event of discharge caused by precipitation less than or equal to the 10-year, <br />24-hour precipitation event, was exceeded by the sample collected 3/25/98. This pond had not <br />dischazged prior to this date during the quarter. Discharge occurred solely in response to _ <br />snowmelt runoff. However, at the time the sample was collected, the runoff volume was not _ <br />exceeding the designed 10-year, 24-hour event discharge. As a result, an exceedance of the ~, <br />30-day average settleable solids limitation is reported. The pond was documented to have <br />ceased discharging on 3/31/98. <br />At outfall 015, the primary 30-day average and daily maximum limitations for TSS and the <br />primary 30-day average limitation for total iron were exceeded by a sample collected 3/24/98. <br />However, the alternate daily maximum limitation for settleable solids applicable in the event of <br />discharge caused by precipitation less than or equal to the 10-year, 24-hour precipitation event, <br />was met. This pond had not dischazged prior to this date during the quarter. Discharge <br />occurred solely in response to snowmelt runoff and as a result, the alternative limitations are <br />applicable. <br />At outfall 017, the primary 30-day average and daily maximum limitations for TSS and total -~ <br />iron were exceeded by a sample collected 3/19/98. However, the alternate daily maximum -~ <br />limitation for settleable solids applicable in the event of discharge caused by precipitation less <br />