SITE INFORMATION AND CORRESPONDENCE_1992

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C-SHADIRFS92.4/WPADD 1.18 07/21/92 interval, and DDT alone in the 10- to 15-ft interval (Table 3-1). The highest concentration of DDT in any of the soil boring samples was 2.10 µg/g, of DDE was 0.775 gg/g, and of DDD was 0.044 µg/g. The surface sample Sl-Sl contained 0.396 µg/g DDT, 0.224 Ag/g DDE, and 8.32 µg/g dieldrin. Three additional 15-ft-deep borings were drilled close to the original boring, Sl-Bl, in a second sampling effort of the RI (ESE, 1990). These borings were 14 Sl-B2, S1-B3, and S1-B4 (Fig. 3-1). A total of nine samples (plus one duplicate), one from each 5-ft interval (0 to 5, 5 to 10, and 10 to 15 ft, denoted as -A, -B, and -C, respectively), were collected and analyzed for organochlorine pesticides, BTEX, TRPH, arsenic, and other metals. Sample S1-B2-A contained 0.012 µg/g DDE and 0.020 gg/g DDT, and sample Sl-B4-A contained 0.012 µg/g DDD and DDE each (Table 3-1). No chlordane was detected in any sample, and no pesticides were detected in the samples collected below 5 ft. None of the samples contained BTEX or TRPH, and no anomalously high metals concentrations were noted (metals are not shown in Table 3-1). 3.1.2 CURRENT U-NESI'IGATION For the most recent investigation, five composite surface (0- to 0.5-ft-deep) soil samples (CHLOR 1 through CHLOR 5, plus a duplicate) were collected at the pesticide mix area. Samples CHLOR 1, 2, and 3 were collected near the head of the drainage ditch, and CHLOR 4 and 5 were collected approximately 110 ft,: downstream (to the east). CHLOR 1 was a composite of six grab samples; . CHLOR 2, 3, and 4 were composites of four grab samples each; and CHLOR 5 was a composite of five grab samples (Fig. 3-1). All of the samples were analyzed for organochlorine pesticides. The highest levels of chlordane (55 pg/g) and dieldrin (0.162 tig/g) were found at CHLOR 4; much lower levels of chlordane were detected in all of the remaining samples, and lower levels of 3-3