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M location and the extent of hydrocarbon impact to soil and groundwater has not been fully defined at the site. Therefore, an additional subsurface investigation is warranted and GHD has initiated the off-site access process. 2.0 SITE GEOLOGY AND HYDROGEOLOGY Soils encountered at the site during previous investigations include silt, clay, silty sand, and gravel typical of fluvial deposits. Predominantly lean clay and silt with minor amounts of fine sand and gravel are present approximately from 30 to 50 feet bgs. Shallow groundwater was initially encountered at approximately 27 feet bgs, is unconfined, and underlain by hard silt and clay units beginning at approximately 45 feet bgs. Shallow groundwater has been measured to be between approximately 26.7 and 27.9 feet bgs and calculated by GHD to flow due north from seven groundwater monitoring events dating back to 2011. Well construction data and historical groundwater levels are presented in Table 1, with historical groundwater flow and hydraulic gradient shown on Table 2. 3.0 PROPOSED TASKS GHD proposes to install three (3) new groundwater monitoring wells (MW-5 through MW-7). Up to two (2) soil samples will be collected from each monitoring well boring. For analytical purposes up to 6 soil samples are proposed in order to define the lateral extent of petroleum hydrocarbon impact. Groundwater samples will be collected from the newly installed monitoring wells after development as part of the regular groundwater sampling routine. Off-site access on to the adjacent property to the north is required. GHD has made initial contact and discussed the scope of work required by the CVRWQCB to define the extent of petroleum hydrocarbons. All necessary information has been provided to the CVRWQCB so that they can obtain the written access agreement. The top of casing elevation for the new groundwater monitoring wells installed at the site will be surveyed relative to mean sea level. The horizontal location of the new monitoring wells will also be surveyed with high precision utilizing global positioning system equipment. The locations of the proposed monitoring wells are shown on the attached Figure 2. 3.1 PRE-FIELD ACTIVITIES Prior to initiating the drilling and sampling activities, each proposed monitoring well location will be marked with white paint and Underground Services Alert(USA)will be notified at least 48 hours before the field event, in order to clear subsurface utilities.A private underground locating company will also be hired to clear each drilling location. A soil boring and well construction permit will be obtained from the San Joaquin County Environmental Health Department (SJCEHD). Additionally, the SJCEHD, the CVRWQCB, and DGS-RESD will be notified of the proposed field activities at least five (5) days in advance. 3.2 DRILLING AND MONITORING WELL INSTALLATION Monitoring well installation will be performed utilizing a truck mounted hollow-stem auger drill rig and sampled every five (5)feet using a California style split spoon sampler. Drilling and sampling equipment will be decontaminated before and after each use using a steam cleaner. Soil cuttings and decontamination rinsate will be stored in labeled Department of Transportation (DOT) approved 55- gallon drums, pending evaluation of disposal options. 03009-10017-37110 3 of 6 March 2014