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November 5, 2001 53636.001 Mr. Peter Ingram City of Redwood City Page 6 Task 2 - Depth Discrete Soil and Groundwater Sampling and Analyses Task 3 - Soil-Gas Survey Task 4 - Sensitive Receptor Survey and Site Conceptual Model Task 5 - Data Compilation and Evaluation Task 6 - Report Preparation Task 7 - Consultation and Meetings These tasks are further described below: Task 1 - CPT Investigation and Preparation of Geologic Cross-Sections As described in SCI's Work Plan, Harding ESE will conduct a subsurface investigation at the site consisting of 10 to 12 CPT probes. The CPT locations are shown in SCI's Work Plan. The advantages of CPTs are that they can be performed relatively quickly and provide continuous information on subsurface conditions with depth. Prior to conducting field activities, we will obtain a drilling permit from the San Marco County Health Services Agency (SMCHSA). We will also retain the services of a utility locating company to check for underground utilities and obstructions in the vicinity of the CPT locations, and we will notify Underground Service Alert (USA) at least 48 hours prior to conducting field activities. The CPTs will be advanced to a depth of approximately 40 feet below ground surface (bgs) to provide vertical subsurface profiling beyond the depth of the deepest water-bearing zones identified by EFW during their previous CPT investigations. Two of the CPTs will be advanced to approximately 100 feet to evaluate the potential presence of deeper aquifers beneath the site. Once the CPT probes are complete, the probe holes will be backfilled with neat cement using the tremie-method. Harding ESE will compile the new CPT data with previous CPT data to prepare comprehensive cross- sections of subsurface lithology across the entire site. These cross-sections will be used to identify continuous water-bearing zones, and will assist in selecting depth intervals where discrete groundwater and soil samples will be collected for chemical analyses. Task 2 - Depth Discrete Soil and Groundwater Sampling and Analyses To delineate the extent of HVOC impacts in groundwater and soil at the site, Harding ESE will collect depth-discrete groundwater samples using direct push sampling equipment as described in SCI's Work Plan. Shallow soil samples will also be collected at approximately 4 feet bgs for risk assessment analysis purposes. Sampling probes will be located in near proximity to the CPT locations in order to correlate sampling intervals with the water bearing zones identified during the CPT investigation. a Einarson Geoscience, Inc., Source Removal, Formal Davies Properties, November 1995. Harding ESE