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Former Beacon Station No 12419 March 18, 2002 <br /> Stockton California Problem Assessment Re ort/Correcttve Action Plan <br /> i 6.0 ADDITIONAL SITE INVESTIGATION <br /> The additional investigation was developed in response to SJCEHD requests, contained in a <br /> letter dated 1 I July 2000 (Appendix C), to complete the investigative phase for this site by <br /> defining vertical and lateral extent of petroleum hydrocarbon-impacted soil and groundwater <br /> in the area of soil boring SB-6 (air sparge well AS-1) The additional investigation included <br /> advancement of three soil borings, and conversion of the borings to air sparge wells AS-2 <br /> and AS-3, and monitoring well MW-1 I <br /> Horizon obtained a well permit (Appendix C) from the SJCEHD allowing installation of the <br /> wells A site specific Health & Safety Plan was prepared to identify and mitigate potential <br /> site hazards encountered during fieldwork Underground Services Alert (USA) was notified <br /> to identify the locations of underground utilities Fieldwork was conducted in accordance <br /> with Horizon's Field Methods and Procedures (Appendix D) <br /> 6.1 Well Drilling and Installation, and Soil Sampling <br /> g <br /> On 20 and 21 September 2000, Horizon witnessed drilling and soil sampling of three well <br /> borings, and installation of two air sparge wells and one monitoring well at the locations <br /> shown on Figure 2 The wells were drilled and installed by V & W Drilling, Inc (V & W) <br /> utilizing a BK-81 hollow-stem auger rig fitted with 8-inch diameter augers <br /> Prior to drilling with the hollow-stem augers, a hand auger boring was advanced to <br /> approximately 5 feet bsg to check the location for unidentified underground utilities During <br /> drilling, soil samples were collected from the air sparge well AS-2 boring at 5-foot intervals <br /> from 90 to 130 feet bsg, and from the air sparge well AS-3 boring at 5-foot intervals from 6 <br /> to 86 feet bsg Soil analytical data are available from the adjacent air sparge well AS-1 <br /> boring (soil boring SB-6 drilled in September 1998) from approximately 21 to 88 feet bsg <br /> Soil samples were not collected from the monitoring well MW-II boring because it was <br /> located adjacent to air sparge well AS-3 <br /> 419PARCAP3-02 doc 6 <br /> Project No 1419 23 HORIZON ENVIRONMENTAL INC. <br />