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,,, had occurred. The remainder of the samples that showed elevated levels represent 12.7% of the overburden volume. Studies conducted by the Federal government show that up to 20% of potentially toxic material in a truck and shovel operation would be diluted to acceptable levels. Twentythree of the samples exceeded the Montana guidelines for suspect levels of Molybdenum. Wyoming does not have a suspect level for Molybdenum. Studies have not shown that there is a field occurrence of toxicity to molybdenum and that all surface water and groundwater samples evaluated by the mine are below the detection limit. SAR values in 38.6% of the samples were above the suspect level of 1S in the Wyoming guidelines. The weighted average value is 8.74. Many of the samples were contaminated with drilling mud, drilling foam or other drilling fluid. Kerr cited a study that showed that drilling fluids dramatically increase SAR values above samples taken from highwall or drilled with air. None of the drillholes were drilled using air; therefore, all samples were contaminated and their value for determining SAR is questionable. Acid-Base Potential analysis did not indicate a potential problem with acid forming material. Overall the interpretation of the overburden analysis showed that only Nickel and Selenium were found at levels that were of any concern, and that the mixing of the overburden during haulage would dilute be the few samples that were in the suspect range. A discussion of the analysis and interpretation can be found page 779-16 a of the permit application. Groundwater Alluvium is found sporadically along all draws draining [he mine site, next to the Canadian River and adjacent to the Illinois River near the loadout. Monitoring has been performed along the draw and adjacent to the tipple on the Illinois River. The discontinuous alluvium within the draws draining the Marr permit area is predominately composed of clay with isolated sand and gravel lenses. However, the permeability of the alluvium adjacent to the Illinois River is much higher and is estimated to be 2,500 gallons per day per square foot (gpd/ftZ)• Surface Water The surface hydrology of the general area including the mine plan area consists of the high altitude, semiarid environment found in the upland parks of the Central Colorado Rocky Marr Strip Mine, C-80-006 8 December 9, 1992 aquifer has moderately poor yields, except where it is faulted. The water is slightly alkaline and total dissolved solids concentrations average 500 mg/1. The water is acceptable for stock and limited domestic use.