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rn <br /> _m� ..a,. <br /> ' The variability of analytical results between the WESTON split samples and the Board <br /> split samples may be significant. The 6 March total nitrogen results from AnLab were <br /> ' consistently 2 times the results obtained by WESTON's Stockton Laboratory. For the <br /> most recent sampling event, WESTON used a different laboratory (Sequoia Analytical <br /> ' Laboratory) and the total leachable nitrogen results from AnLab were 2.5 time higher <br /> than Sequoia's. The consistently higher AnLab results appear to indicate that AnLab <br /> uses laboratory procedures and/or equipment that are different from those used by other <br /> laboratories. <br /> During a 2 August 1995 telephone conversation, WESTON was informed by Ms. Wendy <br /> ' Wyels that for comparison purposes, the following formula should be used to evaluate <br /> the TCLP data: <br /> ' analytical result x 20 (dilution factor) <br /> 10 (attenuation factor) <br /> ' The result from this formula should be compared to the following criteria which as been <br /> established by the Board for the Koppel Terminal site: <br /> ' • 10 mg/I for nitrate as N, and <br /> • 0.037 mg/1 for ammonia as N. <br /> By using this formula, results for all WESTON and Board samples exceed the 0.037 mg/1 <br /> criteria for ammonia. Samples containing leachable nitrate in excess of the Board's <br /> criteria of 10 mg/1 include: SBI-3', SB3-3', and SB3-6'. <br /> Total nitrogen concentrations were detected in the decontamination blank at 0.18 mg/1 <br /> which is approximately the detection limit for ammonia. This indicates that <br /> decontamination procedures were sufficient. <br /> ' There is a laterally continuous clay layer at the site, however, it varies significantly in <br /> thickness and does not appear to prevent downward migration of total leachable nitrogen <br /> in excess of the Board's criteria for this site. <br /> ' 5 <br />