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TECHNICAL APPROACH SUMMARY The objectives of the proposed scope of work are to further investigate the extent of impacted soil and groundwater, establish a groundwater monitoring capability at the site, and survey possible sensitive receptors in the site vicinity. To achieve these objectives , three on-site groundwater monitoring wells will be installed and monitored and sampled on a quarterly basis for at least one year, and a survey of possible sensitive receptors within 2,000 feet of the site will be conducted . One of the proposed wells will be located at the south end of the former UST #2 in the vicinity of the previous Geoprobe soil boring G-3. The boring for this monitoring well will be continuously cored to delineate the subsurface soil sequence and to evaluate the vertical extent of impacted soil . Another of the proposed monitoring wells will be positioned adjacent to the former dispenser island , so that concentrations of petroleum hydrocarbons previously detected at that location can be confirmed and monitored . Given that the regional groundwater flow direction is expected to be toward the northeast, the other proposed monitoring well will be positioned northeast of the former UST #2 . The proposed wells adjacent to the former dispenser island and to the northeast of the former UST will be installed inside the parking garage building . Since groundwater was previously encountered at approximately 25 feet bgs, the wells will be drilled to a total depth of approximately 35 feet, and constructed with a screen interval of approximately 20 to 35 feet bgs. The wells will be surged and purged by the driller, following the placement of the sand pack and prior to the installation of the well seals. A licensed land surveyor will survey each of the newly-installed wellheads. During the drilling , undisturbed soil samples will be collected at 5400t intervals using a modified California split-spoon sampler lined with sample sleeves. The samples collected at the 25, 30 and 35 feet bgs will be analyzed for TPH-as-diesel , TPWas-motor oil , and TPH-as-kerosene by EPA Method 8015M , and for TPWas-gasoline, BTEX, MTBE , DIPE , ETBE , TAME , and TBA by EPA Method 8260B . After the monitoring well seals have set, and then on a quarterly basis thereafter, the wells will be monitored and sampled . Groundwater samples will be analyzed for TPH-as-diesel , TPH-as- motor oil , and TPWas-kerosene by EPA Method 8015M , and for TPH-as-gasoline , BTEX, MTBE , DIPE , ETBE , TAME , and TBA by EPA Method 8260B. All waste soil generated during drilling will be contained in 55-gallon drums. Equipment rinsate and purged groundwater will be contained in separate 55-gallon drums . The waste will be stored temporarily on-site , pending proper disposition . Potential sensitive receptors will be surveyed within 2 ,000-feet of the site. The survey will include a review of water well completion reports at the state of California Department of Water Resources, contact with local and private water purveyors, and a tour of the site vicinity. The results of the well installation and sensitive receptor survey will be documented in an environmental site investigation report. Each of the subsequent quarterly groundwater monitoring and sampling events will be documented in quarterly groundwater monitoring reports. Given standard scheduling assumptions , the project report could be completed by the end of December 2001 . 3