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Page 3 of 7 k1a.e Results Report for Limited Subsurface Investigation Third Quarter 2000 Groundwater Monitoring Report Moore Petroleum Bulk Plant,5491 F Street,Banta,-California On April 8 and 9, 1999, Apex personnel supervised the advancement of eight soil borings at the subject property. The results of all soil and water sampling were documented in the report entitled Results Report for Subsurface Investigation and Second Quarter 1999 Groundwater Monitoring dated June 1, 1999. Apex submitted the Workplan for Limited Subsurface Investigation dated April 27, 2000, proposing the installation of three additional groundwater monitoring wells and one deep soil boring. On May 25, 2000,the County verbally, conditionally approved the Workplan on the condition that boring SB-Deep utilize continuos coring techniques. On August 22, 2000, the County approved the Workplan in a letter(Appendix A). SUBSURFACE INVESTIGATION Soil Borin>r Activities On July 25 and 26, 2000, Apex advanced four soil borings for the purpose of defining the lateral and vertical extent of the petroleum hydrocarbons in the shallow groundwater in the area of the subject site. Three of the four soil borings were drilled to a depth of 20 feet below grade surface (bgs) and completed as monitoring wells (MW-10, MW-11, MW-12) to assess the lateral extent of contaminant migration in soil and groundwater. One soil boring was completed to a depth of 39-feet bgs (SB-Deep) to assess the vertical extent of contaminant migration in soil in the vicinity of well MW-8 (Figure 2). Shallow Soil Borings Three soil borings (MW-10, MW-11, and MW-12) were advanced to 20-feet bgs at locations shown on Figure 2. These three borings were located to determine the lateral extent of soil contamination at the site. The borings were converted to monitoring wells for subsequent groundwater monitoring to determine the lateral extent of groundwater contamination. Boring MW-12 was located between the contamination source area and the Rhodes residence domestic well. Well MW-12 will act as a sentinel well for the Rhodes domestic well. Boring MW-11 was located at the north property boundary and boring MW-10 was located north of the office building (Figure 2). Three soil samples were collected from each boring location at the 5-, 10-, and 20-feet depth intervals. -The boring 'logs and well construction details are presented in Appendix B. All drilling and soil sampling activities were done in accordance with Apex's SOP included in Appendix C