2020-06-26_GENERAL DOCUMENTS - C1981041

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POWDERHORN COAL C014PANY 1994 ANNUAL HYDROLOGIC REPORT AND MINE INFLOWS STUDY OCTOBER 1, 1993 THROUGH SEPTEMBER 30, 1994 Introduction During the 1994 Water Year, the Year, the names of the Roadside and Cameo No. I mines were changed to the Roadside South Portal and the Roadside North Portal respectively. Production of coal continued to be primarily from the Roadside South during this Year. A small amount of coal was mine from the Roadside North in May 1994 and since the end of this reporting period the focus of mining has changed to the Roadside North due to a thicker seam and higher. quality. The management role of Peabody Western Coal Company in Flagstaff, Arizona, was reduced during the Year but their environmental department continued to provide assistance for hydrologic reporting. The delay in preparation of this report was partially due to delays in programming changes that were made by Flagstaff in the hydrologic reporting system to make it a mine site PC based system. The general, format of this report is the same as in previous years. Some of the numerous tables and graphs that were prepared for the 1993 AHR have not been repeated due to their lack of significant information. Lowess and Trilinear diagrams are again used in this report. Changes in the monitoring and reporting during the Year include the addition of outfall. 015 to our CDPS permit, the elimination Of Chronic Whole Effluent Tests from our discharge monitoring requirements, the addition of 30 new piezometers on the Cameo Refuse Disposal Area No. 1, commitment to quarterly water level monitoring at the Unit Train Loadout piezometers , annual full suite analysis of two piezometers at the Unit Train Loadout, and the addition of quarterly monitoring of the water level In old portions of the Roadside South. There was error in getting sample bottles in time for full suite samples in September 1994 and as a result water quality information taken on October 3, 1994 was included in this report. Surface Water Water flow and quality on the Colorado River is monitored by the U.S. Geologic Survey (USGS) at various locations. The closest location is Station No. 09095500 which is located upstream approximately 7 miles north east of the mine site. Water quality and flow from this site are used as a general representation of the Colorado River upgradient of our mining operation. There is a diversion to the Government Highline Canal, the addition of Plateau V() N'I'A N A R I F X I I I B 1'1' 11 DRNIS Dki. #Sl,- I I