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0 i <br /> INTERNATIONAL TECHNOLOGY CCRPC:,A.TION <br /> Ms. Wendy Wyels <br /> Page 2 <br /> 2. The location of the deeper soil boring has been identified on Figure 3 as SB-5. This <br /> location is downgradient of the site and is in close proximity to the proposed monitoring <br /> well MW-8. The deeper soil boring will be advanced to the next lower groundwater- <br /> bearing zone which is expected at a depth of less than 35 feet below ground surface. <br /> 3. A review of the historical soil sample analytical data (Table 1) suggests that nitrates and <br /> petroleum hydrocarbons exist at relatively low concentrations beneath the site. In <br /> addition, a review of historical groundwater sample data (Tables 2 and 3) indicates that <br /> nitrate, ammonia, pesticides, herbicides and petroleum hydrocarbons exist in groundwater <br /> beneath the site. To attempt to identify a source of nitrate, ammonia and pesticides, <br /> certain vadose zone soil samples will be collected and analyzed. The soil and <br /> groundwater sampling program is summarized in Table 5. Soil samples from all <br /> geoprobe locations and two of the proposed monitoring wells (MW-6 and MW-7) will <br /> be analyzed for nitrate. Soil samples from the geoprobe and monitoring well locations <br /> in the central and northern portions of the site will be analyzed for ammonia which has <br /> been detected in the existing groundwater wells in the northern portion of the site (MW- <br /> 1,4 and 5). To evaluate a possible source of triazine pesticides from the former storage <br /> trailers southwest of MW-2, one geoprobe soil sample from SB-7 will be analyzed by <br /> EPA 619. To better define the downgradient and vertical extent of petroleum <br /> hydrocarbons, one deep and one shallow soil sample from the deeper geoprobe boring <br /> (SB-5) will be analyzed for TPH-diesel, TPH-gasoline and BTEX. <br /> To compensate for the reduction in pesticide and herbicide soil sample analyses, IT has <br /> added two geoprobe groundwater grab sample locations downgradient of the site (SB-13 <br /> and SB-14). <br /> 4. To clarify and summarize the specific analytical program proposed for the site, geoprobe <br /> and monitoring well locations and the corresponding groundwater and soil sample <br /> analyses are outlined in Table 5. <br /> Monitoring Well Installation (Section 2.1.3) <br /> 1. IT plans to install four monitoring wells at locations indicated on Figure 3. At least one <br /> proposed well (MW-8) will be positioned downgradient of the plume. <br /> 2. Currently, the groundwater table is above the top of the screen interval of the existing <br /> wells. This condition may present ambiguous groundwater gradient and groundwater <br /> quality data. As such, IT proposes to install the new wells such that the screened <br /> interval (5 to 20 feet below ground surface) coincides with the current groundwater <br /> elevation. When calculating groundwater flow direction and gradient, the differences <br /> between the new and existing wells will be evaluated and compared. <br /> 3. IT will open all the wells to allow equilibrium prior to groundwater monitoring activities. <br /> IT Corporo ton S a wholly owned suir=cri r._rernatlonal Technology CoMoro fon <br />