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' EEC S411-4 Und'irst Stockton August 8,2002 I On Wednesday August 7,2002, EEC mobilized to the site to determine if additional UST's were present EEC subcontracted the service of Gasch and Associates, Inc (Gasch) of Rancho Cordova, California,to perform a subsurface geophysical survey to determine if additional UST's were present Gasch performed the survey by dividing the 90 foot by 100 foot site, into 10 foot grids The geophysical survey was conducted utilizing a cesium vapor magnetometer ' Based on the preliminary, onsite indications of the geophysical survey, EEC identified several test pit locations to be excavated to detennine if underground storage tanks and associated pipelines were present On August 7, 2002, six of these test pits were excavated Excavation of ' the test pits revealed the presence of underground piping near the northern property boundary This underground piping appears typical of gasoline service station piping In addition, hydrocarbon odors and staining were identified while excavating the northernmost test pits Due ' to the presence of the hydrocarbon-impacted soil, EEC halted excavation activities, until the SJCEHD could be notified Excavation of the test pits was halted before the area of the suspected UST was excavated ' A detailed computer analysis of the geophysical survey data has identified a large magnetic anomaly near the northeastern portion edge of the site This anomaly may suggest the location of ' an underground storage tank(s) The computer imaging of the survey is presented in Figure 3 The area of the magnetic anomaly will be excavated on Monday, August 12, 2000, to determine the presence or absence of the UST(s) Based on the likelihood that UST's are present, EEC will ' begin the permitting process for UST removal, to avoid delays in tank removal UST removal permitting will be submitted under a separate attachment Previous reports prepared for the adjacent properties indicate that first groundwater is expected to be encountered at a depth of approximately 29 to 45 feet below grade in the site vicinity(EEC, February 1998) ' Proposed Assessment and Remediation Strategy Based on the discovery of hydrocarbon-impacted soil and underground storage tank related ' piping, EEC is proposing to conduct the following scope of work, on a fast-track basis • Prepare and implement a site specific Health and Safety Plan ' • Complete the excavation of a test pit in the area suspected to contain an underground storage tanks Test pits will be excavated to depths of approximately 15 feet bgs The location of the suspected tank is shown on Figures 2 and 3 ' • Obtain approval of this workplan by the SJCDEH • Delineate and excavate hydrocarbon-impacted soil that is located within the areas that will be disturbed during construction activity The delineation and excavation will be conducted utilizing a backhoe or excavator If additional delineation or remediation is required, UniFirst ' will address this assessment/remediation after the site preparation is complete and construction of the facility is underway or completed • Segregate soil in the field utilizing field observations and a photo-ionization detector(PID) ' • When excavation limits have been reached, EEC will collect confirmation soil samples Because the configuration and final excavation limits are not known at this time, EEC can only provide general guidelines by which confirmation testing will be conducted 1