SITE INFORMATION AND CORRESPONDENCE

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California Stop Page 2 2224 Manthey Road August 31, 2011 Stockton, California 95206 at this time. Impacted soil and groundwater appear to be located mainly in the dispenser and underground storage tank (UST) areas and the shallow groundwater flow direction is generally toward the southeast, based on the rose diagram submitted by AGE. Since the proposed deep well location appears to be cross gradient of the dispensers and where AGE proposes to install a shallow well, the EHD believes the proposed shallow well east of the building should suffice for defining the petroleum hydrocarbon plume in this direction. AGE proposes to collect soil samples at five-foot intervals beginning at 15 feet bsg at each borehole to screen for volatile organic compounds (VOCs) using an organic vapor analyzer (OVA) with a photo-ionization detector (PID), and for lithologic evaluation and analysis by a State of California Department of Public Health-certified laboratory. AGE proposes to analyze select soil and grab groundwater samples for total petroleum hydrocarbons as gasoline (TPH- g); benzene, toluene, ethylbenzene and total xylenes (BTEX); methyl tertiary-butyl ether (MTBE); tertiary-amyl methyl ether (TAME) and tertiary-butyl alcohol (TBA). Following the well installations, AGE proposes to monitor and collect groundwater samples quarterly from the newly installed wells for a minimum of one year and analyze the groundwater samples for these same constituents. The EHD approves the proposals as presented above. In summation, these include the installation of: • One deep monitoring well near MW-1, screened between approximately 70 and 80 feet bsg; • One soil boring at the northwest corner of the site advanced to approximately 30 feet bsg to collect a grab groundwater sample; • Two shallow monitoring wells, screened between approximately 10 and 30 feet bsg, at locations illustrated on Figure 2 of Additional Site Assessment Work Plan— June 2011; and • One off-site monitoring well located on the 1-5 south on-ramp with a 20-foot screen interval at a depth interval comparable to the other on-site shallow wells, having adjusted for the elevation of the on-ramp. In Soil Vapor Extraction Pilot Test/Ozone Feasibility Work Plan (SVE/OZ work plan) AGE proposes to omit performing the ozone BST as directed by the EHD by letter dated 30 March 2011, and instead proposes to apply data from an ozone BST completed at the Lopez Property site located at 1601 Turnpike Road to assess conditions at this subject site. AGE states that the Turnpike site is approximately 3,000 feet northeast of this subject site and shares similar depth-to-groundwater measurements, geology and "sediments". AGE also indicates that "this offsite BST approach appears to be acceptable" to the California Regional Water Quality Control Board — Central Valley Region (CRWQCB). The EHD approves omitting the performance of an ozone BST at this subject site and proceeding with ozone feasibility pilot study, pending concurrence from the CRWQCB. In the SVE/OZ work plan, AGE proposes to install three 4-inch diameter SVE wells, each screened between approximately 5 and 20 feet, at locations illustrated on Figure 2 of this work plan to target the gasoline-impacted soil detected in shallow soil samples collected near dispensers 1, 2 and 4. AGE proposes to collect soil samples at each of the three SVE boreholes at five-foot intervals beginning at 5 feet bsg for Iithologic classification, and