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r Stantec 2010 TIDEWATER STOCKTON WORK PLAN 3.2 FURTHER ASSESSMENT AT WATERFRONT TOWERS One of the purposes of this investigation is to further define the presence and the extent of petroleum hydrocarbon-affected soil and groundwater in the WFT area where SPH has been observed. A CPT rig will be used to identify lithological units beneath the WFT parking lot. The CPT rig will also use LIF (also known as Rapid Optical Screening Tool or ROSTTM) to identify areas with SPH during boring advancement. The CPT/ LIF soundings will be used to further define areas at the site for future remedial efforts, to assess potential impacts from previous site activities, and to better define hydrocarbon impact to groundwater. The following section describes the standard field procedures used to collected subsurface geologic data by CPT and estimating the in-situ concentration of hydrocarbons using LIF. 3.2.1 Continuously Cored Direct Push Boring Methodology Stantec will advance one direct push boring (DP-22) to approximately 60 feet bgs in the area of observed SPH at the WFT (Figure 3). The boring will be continuously cored from the surface to the total depth of the boring to collect lithological data for comparison purposes while advancing the CPT/LIF borings in the area. Soil will be visually inspected and classified using the Unified Soil Classification System (USCS). Observations of hydrocarbon staining and photo-ionization detector(PID) readings will be recorded on the boring log. Select soil samples will be submitted for laboratory analytical testing in an attempt to quantify the hydrocarbon concentrations for comparison to CPT/LIF data. The soil samples selected for laboratory analysis will be based on the highest PID headspace field measurement and field observations. Each collected sample will be appropriately labeled to identify the sample number, project name, facility number, date and time of sample collection, and the sampler's initials. Soil samples will be placed in an ice- chilled cooler and transported to a State-certified analytical laboratory for testing under chain-of- custody procedures. 3.2.2 CPT and LIF Methodology Stantec will advance approximately eight CPT/LIF borings (DP-23 through DP-30) to depths of up to 60 feet bgs in the area of observed SPH at the WFT, and depending on findings from DP-22, to better characterize lithology and extent of petroleum hydrocarbon impact (Figure 3). The presence and relative concentration of hydrocarbons will be interpreted from the total fluorescence intensity observed at specific depths in each boring location. Lithologic and relative hydrocarbon concentration data will be interpreted in real-time by the field geologist. Since this portion is intended to be iterative, the exact number, depth, and location of the borings may vary based on the ongoing field interpretation of the data, with the overall goal of estimating the presence and extent of SPH. 3.2.2.1 Rapid Optical Screening Tool Testing Fugro Geosciences' ROSTTA/ LIF system will be used for this investigation to screen soils for petroleum hydrocarbon constituents. The system consists of a tunable laser mounted in the 3.8