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Additional Site Assessment Work Plan GREWAL'S MARKET 4100 Nar�'t Street, Stockton, California 1.0. INTRODUCTION At the request of Mr. Rick Grewal of Grewal's Market,Advanced GeoEnvironmental. Inc. (AGE) has prepared the enclosed additional site assessment work plan for 4100 Ifa,�MeRgtreet in Stockton, California.The work plan includes the advancement of cone penetrometer testing(CPT)soil borings for the collection of soil and ground water data. 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 CPT(Cone Penetrometer Testing) soil boring advancement, ground water sample collection and analysis, and boring abandonment. The plan was prepared in accordance with California Regional Water Quality Control Board- Central Valley Region (RWQCB) guidelines for the investigation of underground storage tank (UST) sites. Based on the data collected to date from previous soil borings and from ground water monitoring wells, AGE previously developed a site conceptual model (SCM) for the release, migration and distribution of contaminants to the subsurface(Site Conceptual Model,dated 29 March 2004).Based on the SCM,the primary contaminates of concern(COCs)at this site were determined to be benzene, toluene, ethylbenzene, total xylenes (BTEX constituents), methyl tertiary butyl ether (MTBE) and 1,2-dichloroethene (1,2-DCA). Furthermore, the vertical and lateral extent of BTEX and MTBE- impacted soil and ground water were determined to be adequately assessed, however, 1.2-DCA- impacted ground water was vertically undefined in the area bound by wells MW-1, MW-2 and MW-4 and laterally undefined towards the south section of the property boundary(downgradient). AGE made recommendations in the above referenced SCM for additional site assessment by advancing two CPT soil borings and collection of deeper ground water samples to define the vertical and lateral extent of dissolved 1,2-DCA; in a letter dated 15 September 2005, the San Joaquin County Environmental Health Department (EHD) concurred with AGE's recommendation and requested that a work plan be submitted to EHD by 01 November 2005. 2.0. BACKGROUND A fully detailed site description, and the regional geologic/hydrogcologic setting of the site can be found in the Site Conceptual Model, dated 29 March 2004. Advanced GeoEnvironmental,Inc.