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Pilkington North America,Inc. Site Background Page 4 of 4 On May 9, 2005, Condor surveyed the three Site monitor wells and the six recovery wells. The wells had previously been surveyed to an arbitrary datum and were consequently re-surveyed in accordance with the SWRCB's Survey XYZ Guidelines and Restrictions—Electronic Deliverable Format and Data Dictionary manual revised in April 2005. The survey was conducted to comply with AB 2886 (Water Code Sections 13195 — 13198) under the supervision of a licensed land surveyor. The results of the survey are included in the First Quarter Groundwater Monitoring Report—February and March 2005 dated May 24, 2005. Four diesel recovery events were conducted at the Site from April 18, 2005 through May 12, 2005. Free product was observed in four recovery wells (RW-2, RW-3, RW-4, and RW-6). A total of 0.92 gallons of product was recovered during the second quarter 2005..A cumulative total of approximately 142.59 gallons of diesel was recovered from the Site's recovery wells since skimming operations commenced in June 1999. During the second quarterly monitoring event conducted at the Site on May 12 and 13, 2005, Condor sampled two sumps (SE sump and SW sump) and three monitor wells (MW-1, MW-2, and MW-3). Groundwater elevation measurements collected on May 12, 2005 indicated an average depth to groundwater of 12.81 feet below well collar survey points. The average groundwater elevation on May 12, 2005 decreased 0.34 feet since the previous monitoring event on February 8, 2005. The calculated groundwater gradient on May 12, 2005 was 0.0032 ft/ft to the northeast. Total petroleum hydrocarbons quantified as diesel, kerosene, and motor oil were not detected at or above the laboratory reported detection limits in monitor wells MW-1, MW-2, or MW-3. Total petroleum hydrocarbons quantified as diesel were detected in the SW sump. Thirteen diesel recovery events were conducted at the Site from May 20, 2005 through August 18, 2005. Free product was observed in four recovery wells (RW-2, RW-3, RW-4, and RW-6). Approximately 7.7 gallons of diesel siphoned out of the product recovery tank back into RW-4 between the May 12 and May 20 monitoring events when a piece of debris prevented the solenoid valve from closing. All of the siphoned diesel was subsequently recovered and a total of 8.77 gallons of product was recovered during the third quarter 2005. A cumulative total of approximately 143.66 gallons of diesel have been recovered from the Site's recovery wells since skimming operations commenced in June 1999. During the third quarterly monitoring event conducted at the Site on August 17 and 18, 2005, Condor sampled two sumps (SE sump and SW sump) and three monitor wells (MW-1, MW-2, and MW-3). Groundwater elevation measurements collected on August 17, 2005 indicated that the average groundwater elevation decreased 1.72 feet since the previous monitoring event. The calculated groundwater gradient was 0.003 ft/ft to the southeast. Total petroleum hydrocarbons quantified as diesel, kerosene, and motor oil were not detected at or above the laboratory reported detection limits in monitor wells MW-1, MW-2, MW-3, or the SE sump. Total petroleum hydrocarbons quantified as diesel were detected in the SW sump at 1.42 mg/L. P:\1000_pry\1838 PLOF Diesel Line\183 8B\Reports\QMRs 2005\3rd QUARTER\Site Background Condensed Version 110205.doc