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GRAND VALLEY COAL COMPANY <br />P.O. Box 70 <br />Loma, Colorado 81524-0070 <br />(970) 858-3608 Fax (970) 858 - 7690 <br />October 28, 1997 <br />Colorado Department of Public Health and Environment <br />4300 Cherry Creek Drive South <br />Denver, Colorado 80222-1 5 3 0 <br />Re: Storm Exemption Request CO-0038342 <br />To Whom it May Concern; <br />Grand Valley Coal Company requests relief from the effluent limitations for Total Suspended <br />Solids for a discharge that occurred on September 21, 1997. The discharge was the result of a <br />series of storms that occurred in the mine area from August 18, 1997 through August 22 , 1997. <br />The series of storms were from the remnants of hurricane Linda which moved through western <br />Colorado. The precipitation that occurred on those days is tabulated below <br />Date 24HR Precip. Cumulative Precip. <br />9-18 0.4" 0.4" <br />9-19 0.4" 0.8" <br />9-20 0.75" I.55" <br />9-21 2.50" 4.05" <br />9-22 1.2" 5.25" <br />The 10 year 24 hour precipitation event for the area is 1.7 inches. The storm on September <br />21, 1997 approximates the 100 yeaz 24 hour event (2.6 inches). It should also be noted that over <br />3.3 inches of precipitation occurred in 27 hours from the storm on September 21, 1997. The <br />discharge on September 21, 1997 was necessary to regain storage capacity in the sedimentation <br />facilities. The capacity regained was adequate to allow total retention of the runoff from the <br />storm on September 22, 1997. The pond at McClane Canyon is designed to totally retain the <br />volume of four, 10 year 24 hour events but was not adequate to retain the volume from the series <br />of storms that occurred. <br />On September 22, 1997, Mr. John Kubic of CDOH was informed of the need to discharge <br />and that a storm exemption would probably be necessary. Enclosed are the discharge monitoring <br />reports for the third quarter of 1997. The quality of the effluent exceeded the limitations for total <br />suspended solids (150 vs 75 max) . The effluent limitations for Iron and settleable solids were not <br />exceeded. The storm discharge was the only discharge for the quarter. <br />Please contact me if there are questions or if additional information is required. <br />cerely~j~ <br />John M. Walters <br />Manager of Mine Services <br />