2007-11-20_REVISION - M1982015 (12)

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' in pre-preserved clean laboratory supplied 40-milliliter VOA vials. The samples were placed on ice in a cooler for transport to Environmental Chemistry Services ' (ECS) in Castle Rock, Colorado. The samples were analyzed for benzene, toluene, ethyl benzene and total xylenes (BTEX), and total volatile petroleum hydrocarbons (TVPH) by EPA Method 82608. None of the samples contained any detectable BTEX or TVPH. These sample locations are shown on Figure 2. ' The surface water sampling results are summarized on Table 2. No BTEX or TVPH were detected above the laboratory reporting limits in any of the surface water samples. The water samples were collected following the Colorado VOC ' Sample Preservation Policy, (version June 22, 1998). The laboratory reports are included in Appendix 3. ' On January 3 and 8, 2007, six soil borings were drilled to a depth approximately 20 feet bgs to determine the level and extent of gasoline contamination that may be present in soils in the immediate vicinity and to the north of the SHT. The soil samples were collected using a Geoprobe drilling rig equipped with 5-foot ' continuous 2-inch diameter sampling barrels with clear PVC liners. The soil samples were extruded from the liners and logged for lithology, soil classification, and sample collection. A portion of each sample was placed in new plastic bags ' for screening of volatile organic compounds (VOCs) using a calibrated photo- ionization detector (PID). The observations were recorded on boring logs which are included in Appendix 2. ' Twelve composite soil samples (two from each soil boring) representing approximately 4-foot intervals were placed in four, 2-ounce clean laboratory supplied glass jars. The sample jars were placed on ice in a collar for transport ' to ECS. The samples were analyzed for BTEX and TVPH by EPA Method 8260B. Based on the lab results, none of the samples contained any detectable BTEX or TVPH. Based on field observations, it did not appear there were ' petroleum impacts in the soils with the exception of a slight gasoline odor at the soil/groundwater interface at approximately 12 to 13 feet bgs in MW-1. The boring locations are shown on Figure 2. The soil laboratory results are summarized on Table 3. The laboratory report is included in Appendix 3. Six 2 -inch diameter temporary groundwater monitoring wells constructed with Schedule 40 PVC were installed to a depth of approximately 20 feet determine ' groundwater quality and area hydrogeology. Stick-up steel protective covers were placed over the wells. The well completion details are included on the boring logs in Appendix 2. ' The wells were developed using new disposable PVC bailers until fines were removed from the wells. Groundwater in the wells was allowed to stabilize for 24 ' hours. The depth to groundwater was measured using a decontaminated oil/water interface probe for purposes of obtaining groundwater elevations. The wells were sampled on January 10, 2007 for BTEX and TVPH. Based on ' the lab results, benzene was detected in MW-1 at a concentration of 2,700 mg/L along with other BTEX compounds. None of the other wells contained any detectable BTEX or TVPH. The well locations are shown on Figure 2. The ' groundwater laboratory results are summarized on Table 4. The laboratory report is included in Appendix 3. 9