2007-11-20_REVISION - M1982015 (14)

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6.0 Quarry Pond #1 Sparging Activities ' On February 27, 2007, E-21 installed air-sparging equipment along the southeast corner of Quarry Pond #1 where benzene concentrations had been detected during previous surface water body sampling. The equipment consisted of a positive displacement blower powered by a generator. New flexible fire hose was connected from the blower ' to a PVC manifold that contained 10-foot sections of new screened 2-inch diameter PVC well piping. The screened pipe was placed in the corner of the pond and submerged to produce vigorous bubbling of the upper water column along approximately 60 feet of the ' corner of the pond in the immediate vicinity of the staff gauge at Quarry Pond #1. The pond sparging equipment operated continuously from February 27, to March 20, ' 2007. Samples were collected during the pond sparging and immediately after shut down. Based on the laboratory results, no BTEX compounds were detected in this area of the pond. The water sampling results are presented on Table 3. The laboratory reports are included in Appendix 4. Photos of the pond sparging are presented in ' Appendix 3. 7.0 Additional Site Characterization Activities (February to March, 2007) 7.1 New Well Installations and Samplina Activities t From February 28, 2007 to March 12, 2007, E-21 supervised the installation of 21 new groundwater monitoring wells and two pilot testing wells after the slurry wall was completed through the area of the release. The wells were installed using a truck mounted drilling rig equipped with 6-1/4 O.D. hollow stem augers. The borings were ' advanced to a depth of 18 to 24 feet depending upon bedrock depth. Soil samples were collected using a split spoon sampler. Soils were logged for lithology, soil classification, and sample collection documentation. A portion of each sample was placed in new ' plastic bags for screening of volatile organic compounds (VOCs) using a calibrated PID. The field observations were recorded on boring logs which are included in Appendix 5. The samples were analyzed for BTEX and TVPH by EPA Method 8260B. Based on the lab results, only MW-4R and MW-9 contained detectable levels of BTEX or TVPH. None of the other samples collected from the borings contained detectable levels of BTEX or TVPH. The boring locations are shown on Figure 1. The soil laboratory results are summarized on Table 4. The laboratory report is included in Appendix 4. The wells were constructed using Schedule 40 PVC to a depth of approximately 18 to ' 24. Stick-up steel protective covers were not installed over the wells for future planning purposes. Each well's top of casings were surveyed by Carroll Lange for map coordinates and elevations. The well completion details are included on the boring logs ' in Appendix 5. 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. Purge water from the well development was containerized for waste characterization and disposal. The soil cuttings were placed in the roll-offs that were on site to containerize the remaining material excavated from the SHT. 8