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. • Evaluate the presence of groundwater southeast of the site • Further assess site geology • Further characterize the extent of free product southeast of the site To accomplish these objectives, Stratus implemented the following work activities • Advanced five (5) off-site soil borings (B-44 to B-48) to depths ranging from approximately 105 to 140 feet bgs using the mud rotary drilling method Soil cores were continuously recovered from the borings, beginning at depths ranging from approximately 40 to 55 feet bgs • Collected soil samples from the soil cores recovered from borings B-44 through B-48 for analytical purposes • Drilled and installed 4-inch diameter monitoring wells MW-16 through MW-20 to depths ranging from approximately 98 to 115 feet bgs using 10-inch diameter hollow stem augers • Developed and sampled the newly installed monitoring wells • Surveyed the elevation and horizontal coordinates of borings B-44 through B-48 and wells MW-16 through MW-20 • Prior to implementation of field activities, an access agreement to the property situated south- southeast of the former ARCO station was secured from the property owner Drilling permits were obtained from SJCEHD and encroachment permits were obtained from the County of San Joaquin Department of Public Works (CSJDPW) and the California Department of Transportation (Caltrans) Drilling locations were marked 48 hours prior to fieldwork Underground Service Alert, SJCEHD, CSJDPW, Caltrans, ARCO, and the off-site property owner were notified 48 hours prior to beginning work activities Standard field practices and procedures for all fieldwork are described in Appendix A All work was conducted under the direct supervision of a State of California Professional Geologist Copies of the drilling permits and encroachment permits are provided in Appendix B Field Activities Exploratory Soil Borings A Stratus geologist was on-site to oversee Gregg Drilling and Testing, Inc of Martinez, California (C-57 #485165), complete borings B-44 through B-48 between November 14 and 21, 2005 The initial 5 feet of each borehole were advanced with water knife and vacuum extraction to minimize the possibility of damaging underground utilities Borings B-44 through B-48 were subsequently advanced using the mud rotary drilling method Each boring was advanced using a 2 5-inch diameter core barrel advanced ahead of a 5-inch diameter drill bit The drilling mud consisted of water and powdered bentonite, circulated into and out of the borehole from a steel container situated immediately adjacent to the borehole On reaching the total depth, the drilling mud was removed from the subsurface and the borehole was backfilled to surface grade with neat cement K 1Bp Arco for URS1fi OMeports16100 assessment rpt&scm update doe Page 4 STRATUS