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5tantec 2010 TIDEWATER STOCKTON WORK PLAN CPT truck that is connected to a down-hole sensor. The down-hole sensor consists of a small sapphire window mounted flush with the side of the cone penetration probe. The laser and associated equipment transmit 50 pulses of light per second to the sensor through a fiber optic cable. The wavelength of the pulsed excitation light is tunable and can be set to wavelengths of 266 (nm) or to wavelengths between 280 and 300 nm. The laser light passes though the sapphire window and conveyed to a detection system within the CPT rig. The emission data resulting from the pulsed laser is averaged into one reading per one-second interval (Approximately one reading per 2 cm vertical continuous intervals). For this project, ROSTTM will be operated in multi-wavelength mode (MWL). MWL mode emits fluorescence at four monitoring wavelengths (340, 390, 440, and 490nm). These four wavelengths cover a color range of light produced by light fuels to heavy contaminants when exposed to excitation light. The relative percentage of fluorescence measured at each monitoring wavelengths is plotted continuously on the ROSTTM logs as four continuous "color bands." The width of the color bands represents the relative percentage of the contaminant. By comparing the relative percentage ratios of field data to those created by reference standards, interpretations of product type can be made. Relative concentration estimates are based on the intensity of the fluorescence. 3.2.2.2 Pore Pressure Dissipation Testing Pore pressure dissipation testing (PPDT) is performed to determine the approximate pressure of groundwater above a particular datum. PPDT is performed by stopping the advance of the CPT cone and measuring the in-situ pore pressure until it reaches a static level. Once a static pore- pressure is obtained, the pressure head above the test depth is determined by multiplying the change in pore pressure pore pressure by a factor of 2.31 pounds per square inch (psi) per foot of above the test depth. 3:2.3 Boring Abandonment Upon completion, each boring location is abandoned by inserting a ''/2 inch PVC tremie pipe to the total depth (TD) of the boring. The tremie pipe connects to a grout pump and a mixture of 5% bentonite/Portland Cement grout, or other approved sealing material, is pumped into the base of the boring. The tremie pipe is raised as the level of the grout rises with the sounding. The mixture is brought to within six inches from surface and capped with concrete or paving material, if necessary, to match the surrounding area. All abandonment activities will be conducted under the direct supervision of a Stantec geologist and will be performed by a state licensed contractor. 3.2.4 Equipment Decontamination Between locations all steel rods are removed from the ground for decontamination. The standard decontamination procedure is to pressure wash all pipes with potable water supplied by a steam cleaner. 3.9