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Monitoring Well Installation Work Plan QUICK N SAVE #1 1901 South El Dorado Street, Stockton, California 1 .0. INTRODUCTION At the request of Mr. Mohamad Matar, Advanced GeoEnvironmental, Inc. (AGE) has prepared the enclosed work plan for 1901 South El Dorado Street, Stockton, California. The work plan was prepared as required by the San Joaquin County Environmental Health Department (EHD) by letters dated 16 January and 28 April 2009, to continue delineation of the lateral and vertical extent of petroleum hydrocarbon-impacted ground water at the site. Site background information is included in Appendix A. The location of the site is illustrated on Figure 1 ; a plan of the site is illustrated on Figure 2. This work plan provides a description of the scope of work and procedures to be used for pilot boring advancement, monitoring well installation, and soil and ground water sample collection and analysis . The plan was prepared in accordance with Central Valley Regional Water Quality Control Board (CVRWQCB) guidelines for the investigation of underground storage tank (UST) sites . 2.0. SCOPE OF WORK Based on analytical data from existing site monitoring wells and soil borings, the lateral extent of hydrocarbon-impacted ground water within the water table is not defined beyond well MW- 1 to the southwest, beyond well MW-4 to the south, and beyondboring B-6 to northeast. Upon examination of the constituent concentration trends analyses in well MW-4, it appears concentrations of total petroleumhydrocarbons quantified as gasoline (TPH-g) andbenzene are sharply declining, with two consecutive quarters of non-detections of TPH-g. Methyl-tertiary butyl ether (MTBE) appears to be gradually declining with three of the four last sampling events below the Water Qauhty Object for drinking water of 13 micrograms per liter (µg/1). Based upon concentration trends in well MW-4, AGE maintains additional water table site assessment to the south does not appear to be warranted at this time. A graphical depiction of concentration trends in well MW-4 is presented as Appendix B . MTBE was reported in the grab ground water sample collected from boring B-6 (22 µg/1) within the water table; no additional analytes were reported in the sample. Based on the low concentration of MTBE reported in B-6, AGE maintains, it does not appear to be cost effective or environmentally warranted to install a ground water monitoring well off-site to the north at this time. Analytical data of samples collected from Cone Penetration Testing (CPT) borings advanced in February 2008 indicate the dissolved plume migrated east to southeast and vertically to a depth of 80 feet bsg; historical data suggests the level of the ground water table was near this depth during drought conditions . Several nearby UST investigations (Charter Way and Lincoln Street) have included similar patterns of dissolved hydrocarbon/adsorbed hydrocarbon migrations (east to southeast) . Advanced GeoEnvironmental, Inc.