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AEI Project No. 305662 ' March 16, 2012 Page 2 of 2 ' Metals. The following constituents of concern (CDCs) were detected in groundwater: Chloroform (320 parts per billion - ppb), and TPH (430 ppb). The CDCs were detected above their respective Regional Water Quality Control Board (RWQCB) Environmental Screening Levels (ESLs) of 70 ppb and 100 ppb, respectively. Additionally Advanced GeoEnvironmental Inc. performed a Preliminary Site Assessment in ' January and February 1998 and determined that no USTs were present onsite. However; in October 1998, the San Joaquin County Environmental Health Department (SJCEHD) responded to a complaint that a UST(volume not stated) had been removed from the subject property and was being stored on site. As a result, the SJCEHD required the property owner to obtain a tank identification number and complete state UST forms. In September 1999, the complaint log indicated that a UST was removed under permit. The incident, which originated in October 1998, was noted as "abated" in February 2000. No UST removal reports or confirmation ' soil/groundwater sample data was on file with the SJCEHD. Due to the fact that TPH and Chloroform were reported above ESLs in groundwater at the site and the lack of any documented samples collected from either of the UST removals, AEI issued a proposal to ' further investigate these issues. The scope of the proposed investigation is detailed below. II Geology and Hydrogeology ' According to the previous investigations at the property noted above and in the Phase I ESA, the soils consist of silty clay to a depth of at least 25 feet bgs, the maximum depth explored. ' According to the Phase I ESA, the depth to groundwater is approximately 47 feet bgs. According to information from a nearby site (2050 East Fremont Street), the direction of groundwater flow beneath the property is inferred to be to the northeast. ' III Scope of Work Drilling permits will be obtained from San Joaquin County Environmental Health Department (SJCEHD) for this investigation. The public underground utility locating service Underground Service Alert will be notified to identify public utilities in the work area. Private utility locating ' will be conducted an independent utility locating company to identify underground utilities on the property. A site-specific health and safety plan will be prepared, reviewed by onsite personnel, and kept onsite for the duration of the fieldwork. This work will be performed under the oversight of a licensed professional. Geophysical Survey ' AEI will arrange for a geophysical survey to investigate the possible presence of USrs throughout the site, as accessible. The purpose of the survey is to assess whether any USTs ' remain in place or whether evidence of former UST cavity(s) are present. The survey will be performed in the western portion of the northern parking lot area of the site in the area denoted by the Sanborn maps as being "oil and gas" (Figure 2). ' A magnetometer will be employed to identify any large magnetic anomalies. Ground- penetrating radar (GPR) will also be used to either confirm the size and orientation of any 1