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TECHNICAL APPROACH SUMMARY The objectives of the proposed scope of work are to assess the lateral extent of impacted 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 welts will be installed and sampled on a quarterly basis,the on-site domestic well will be sampled on a quarterlybasis, and a survey of potential sensitive receptors will be conducted. The proposed wells will be installed east,west and northwest of the former USTs. The well to w the northwest will be positioned between the former USTs-and the operating on-site domestic well. Since groundwater is anticipated at a depth of approximately 80 feet, the proposed two- inch diameter wells will consist of approximately 20 feet of well screen, spanning from .. approximately 70 to 90 feet below ground surface (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. During drilling, undisturbed soil samples will be collected at 5-foot intervals using a modified California split-spoon sampler, logged and screened with a PID. Unless field observations dictate otherwise, four soil samples per soil boring will be submitted for laboratory analysis. Each of the soil samples will be analyzed forTPH-as-gasoline, BTEX, MTBE, DIPS, ETBE, TAME, TBA and 1,2-DCA by EPA Method 8260B. A licensed surveyor will surrey each of the newly-installed wellheads. The surveyor will �- measure the elevation of the top of well casings to the nearest 0.01 foot, referenced to a benchmark. The locations of the wells and other site features will also be surveyed. w... The newly-installed wells and the on-site domestic well will be sampled on a quarterly basis for at least one year. Each groundwater sample will be analyzed for TPH-as-gasoline, BTEX, MTBE, DIPE, ETBE,TAME, TBA and 1,2-DCA by EPA Method 8260B. All waste soil generated during drilling will be stockpiled at the site pending analytical results and proper disposition. The soil will be placed on plastic sheeting and covered. Equipment rinsate and purged groundwater will be contained in 55-gallon drums for temporary on-site storage. Potential sensitive receptors will be surveyed within 2,000-feet of the site (i.e., site vicinity). The survey will include a review of water well completion reports at the state of California Department of Water Resources, contact with local water purveyors, and a tour of the site vicinity. The results of the well installation, domestic well sampling, and sensitive receptor survey will be +-- documented in a monitoring well installation report. Each of the subsequent quarterly groundwater monitoring and sampling events will be documented in quarterly groundwater monitoring reports. All reports will be prepared and stamped by a state of California Registered Geologist and submitted to PHSIEHD and RWQGB. Given standard turnaround for regulatory review and approval of this work plan and cost pre- approval from the UST Cleanup Fund, the field work could be completed as early as July 2000. Given standard turnaround for laboratory analyses and report preparation, the project report could be completed and published as early as August 2000. 3