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The consultant will be responsible for recording the date and time of <br /> their monitoring activities. The consultant will also be responsible for <br /> reporting any unusual circumstances observed during the monitoring <br /> activities to MCTC and Black & Veatch immediately. Between each <br /> measurement, the consultant will rinse the end of the water level <br /> indicator with deionized water and containerize the rinsate for MCTC' s <br /> discharge to MCTC' s existing water treatment plant system at the facility. <br /> 3.4.2 Neutron Probe Measurements <br /> Neutron probe moderation techniques will be used to monitor the moisture <br /> content of the unsaturated soils. This technique has been widely used by <br /> agronomists and soil scientists and has recently been used in a number of <br /> environmental applications. Neutron probe moderation will involve placing <br /> a probe containing an encapsulated low-level radioactive material (usually <br /> 50mCI Ameri cium(241)-Beryl ium) down the aluminum cased hole of the neutron <br /> probe monitoring tubes as conceptually illustrated in Figure 3-2. Fast <br /> neutrons are emitted from the source and bombard the adjacent soil. The <br /> neutrons collide with H' atoms and are slowed to a rate which is measurable <br /> by a detector. <br /> The number of counts of returning atoms represents the approximate water <br /> content. When the neutron probe monitor is calibrated with true moisture <br /> contents and soil physical property data, it can be used to not only <br /> measure the moisture content, but also to measure the saturation index, or <br /> the soil saturation. <br /> Prior to injecting water into the subsurface system, Black & Veatch will <br /> require that the consultant perform laboratory and field calibrations of <br /> the neutron prove device. The consultant will then perform a suite of <br /> moisture content measurements that will correspond with the initial <br /> moisture content of the subsurface soils. <br /> During the pilot study, Black & Veatch will require the consultant to take <br /> daily measurements of moisture content using the neutron probe device for <br /> the first five to seven days. Thereafter, the consultant will be required <br /> to take measurements at two to three day intervals, or weekly, as required <br /> by Black & Veatch. Neutron probe measurements will be conducted after <br /> water level measurements have been taken at each neutron probe monitoring <br /> tube location. Neutron probe measurements will be taken at discrete <br /> intervals from corresponding with the soil physical data. For each <br /> monitoring tube location, the consultant will record the time of day, <br /> date, depth, counts, count rate, standard count, and the moisture content. <br /> Neutron probe data evaluation will be performed by Black & Veatch and will <br /> involve plotting the moisture content profile over time to determine zones <br /> of saturation and the radius of influence of the injection wells. <br /> During the full-scale flushing operation, periodic measurements of the <br /> moisture content will be conducted using the neutron probe device. The <br /> appropriate frequency of the neutron probe measurements will be determined <br /> based upon the pilot study results. <br /> 11654.652 3-7 <br />