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1 <br /> I <br /> 4.0 CLEAN-UP CRITERIA <br /> I <br /> Clean-up guidelines are provided in the Colorado Department of Labor and 1-mployment, Oil <br /> IInspection Section document: "Storage Tank Facility Owner/Operator Guidance D tcuments, July 1, <br /> 1995". Acceptable soil contamination levels depend upon the Remedial Action Category (RAC) of the <br /> ground water in the area. <br /> The Remedial Action Category I (RAC I) includes ground water which is currently, or has been used in <br /> the past for drinking water; or is within 500 feet or within the influence of a drinking water-supply <br /> well. RAC lI includes ground water which has the potential of being used as a private drinking water <br /> supply; or ground water not included in RAC I (such as within 500 feet from, or within the zone of <br /> influence of a drinking water-supply well). RAC III ground water designation is assiEned on a case-by <br /> case basis, and includes ground water not being used, and with little or no potential fcr being used as a <br /> public or private drinking water supply. <br /> Assuming that the site lies within the RAC 11 designation, the above guidelines state chat "Soils which <br /> are contaminated and which have impacted or have the potential to impact RAC II ground water should <br /> be remediated to concentrations of less than or equal to 50 mg/Kg BTEX and 250 mg'Kg TPH. These <br /> levels may be determined to be more or less stringent based upon risk assessmer.t and feasibility <br /> studies. Monitoring of ground water not previously impacted may be required." <br /> 1 <br /> 5.0 EXPLORATORY EXCAVATIONS/PID SCREENING <br /> 1 <br /> Umetco personnel utilized a track-hoe to perform exploratory excavations within the area of the <br /> suspected fuel spill (see Figure 5-1). The bottom of all of the exploratory excavations (trenches) <br /> extended down to the top of a sandstone caprock layer. The depth to the top of the caprock was <br /> observed to range from approximately 0.5 feet to approximately 3.0 feet below the original ground <br /> Isurface. <br /> 8 <br /> 1 <br /> 1 <br />