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Mr. Barton • • January 9, 2015 Page 4 of 5 The proposed borings will be completed to approximately 160 feet bgs. Following real-time analysis of soil stratigraphy, specific intervals for grab groundwater sampling will be selected based on probable water bearing zones. Per CRWQCB request and based on the previous CPT investigation identified permeable zones, SGI anticipates groundwater samples will be collected near the current water table and depths of approximately 130 feet bgs, 140 feet bgs, and 155 feet bgs. Groundwater samples will be collected using a hydro-punch sampler which utilizes an expendable tip at the end of a direct-push rod that is advanced to the base of the targeted depth interval. During direct-push rod placement each joint will be sealed with Teflon TM tape. Upon reaching the targeted depth direct-push rods will be retracted between two to five feet (various intervals) and a poly vinyl chloride (PVC) screen attached to blank PVC casing housed within the direct-push rod is exposed to the formation. After the sample is collected from each interval, the down-hole rods are retracted from the borehole, decontaminated (per standard procedures), and re-equipped with an expendable tip and internal casing/screen. Each groundwater sample will be collected from unique borings located approximately one to two feet from the initial Iithologic boring to prevent potential cross contamination. Grab groundwater samples will be submitted to a California-certified laboratory under chain of custody protocol and analyzed for TPHg by United States Environmental Protect Agency (USEPA) Modified 8015B and BTEX, 5-oxygenates (DIPE, EtBE, MtBE, TAME, and TBA), and lead scavengers (1,2-DCA and EDB) by USEPA Method 8260B. Field observations will be documented on a daily field record. An experienced SGI field scientist, working under the direct supervision of a California Professional Geologist, will oversee CPT borings and groundwater sampling. All sampling equipment will be steam-cleaned to prevent cross contamination between sample intervals. Decontamination water will be placed in labeled Department of Transportation (DOT) approved 55-gallon steel drums and placed on-Site pending receipt of the analytical results. All waste will be properly disposed in accordance with the applicable federal, state, and local regulations. GEOTRACKER Investigation data including laboratory analytical results, field data, boring/CPT logs, and the final report will be uploaded to GeoTracker as required. PROJECT REPORTING AND SCHEDULE Results of the investigation (including methodologies used for CPT borings, data collection, grab groundwater sampling, and waste disposition) will be included in an Off-Site Investigation Report (Report). The Report will be reviewed in its entirety and signed by a California Professional Geologist and include Site investigation activities and discussion of results. SGI will commence work following the approval of this Work Plan by CRWQCB. SGI estimates Site investigation activities will take approximately five days to complete, and a report submitted for review within four weeks of receipt of all analytical data. The Source Group,Inc.