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Geosyntec <br /> consultants <br /> 2.2 1993 Pond Area Investigations <br /> ' In the mid-1980s, low levels of 1,2-dichloropropane (1,2-DCP) were detected in off-site <br /> groundwater samples collected from wells near the Site. These detections initiated <br /> investigations to identify the source(s) of the CDCs. One suspected source was the <br /> former North Pond(Sierra-Pacific, 2001). <br /> In 1993, monitoring wells MW-2 and MW-4 were installed in the vicinity of the former <br /> North and South Ponds, respectively, as shown in Figure 2. During drilling, soil <br /> ' samples were collected at 45 and 75 It bgs at MW-2 and at 45 ft bgs at MW-4 (Condor, <br /> 1993). The soil samples were analyzed for nitrate, 1,2-DCP, and total kjeldahl nitrogen <br /> ' (TKN). <br /> Results for the three soil samples collected during the installation of MW-2 and MW-4 <br /> in 1993 are as follows: <br /> • 1,2-DCP was not detected in either sample collected at 45 ft bgs, <br /> ' • Nitrate was detected at low levels in all three samples, and <br /> • TKN was only detected in the samples collected at 45 ft bgs (Condor, 1993). <br /> ' 2.3 1994/1995 Pond Investieation <br /> ' In 1994 and 1995 Sierra-Pacific Groundwater Consultants, Inc. (Sierra-Pacific) <br /> performed a second investigation that was focused on the two ponds. In each pond, soil <br /> samples were collected from two borings advanced in September 1994 and from two <br /> additional borings advanced in January 1995. The sampling program is summarized <br /> ' below (Sierra-Pacific, 1995): <br /> • Former North Pond Area: <br /> o Two borings with samples collected from 0 - 3 and 3 - 6 ft bgs in <br /> September 1994; and <br /> ' o Two borings with samples collected from 5.5 - 6, 10.5 - 11, 15.5 - 16, <br /> 30.5- 31, 50.5 - 51, and 70.5 - 71 It bgs in January 1995. <br /> Work Plan_Stwkton Pond Inv_01-07-08 3 01.07.08 <br /> 1 <br />