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d.GROUNDVVATER <br />n <br />LJ <br />LJ <br />~J <br />The permit area is basically divided into two distinct parts, an upper bench and lower bench. The <br />lower bench (all azeas below the upper irrigation ditch) have approximately 4-6 feet of soil and <br />overburden over a gravel zone of 20 feet thickness. The upper bench has 20 feet of overburden over <br />the same thickness of gravel. These are the first two terraces of Quaternary age gravels above the <br />Colorado River. Permeability and transmissivity is fairly high in the gravel zone since the <br />percentage of fines is less than 30%. <br />Below this gravel zone is the very thick and impermeable Mancos Shale, which forms the base of <br />the lower Colorado River valley. Test borings on the United site and groundwater studies on the <br />Gilsonite property reveal that the ground water table is approximately 4452 feet elevation at the <br />southwest corner of the permit and 4462 feet at the northeast corner. These elevations aze 7-22 feet <br />below the existing surface. The levels will fluctuate depending on the time of year and in response to <br />irrigation use upstream. See the enclosed hydrologic map and cross-section developed by <br />consultants analyzing the Gilsonite Refinery, immediately to the west of the permit area. <br />There are no groundwater wells within reasonable distance to the operation that are used as a source <br />of water. There are many test wells and piezometers that are being actively monitored on the FMM <br />property and these wells will be used by FMM and CDPHE to monitor the effects of gravel pit <br />pumping on petroleum hydrocarbons, free product and other contaminants that exist on the FMM <br />property for the Elam operation. Since the water gradient is from northeast to southwest, no <br />movement from the Gilsonite property to the United site is expected. <br />15 Road Pit 10/02 <br />36 <br />