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04 January 1999 <br /> AGE-NC Project No. 95-0100 <br /> Page 2 of 5 <br />' Three sets of soil gas/vapor influent and effluent samples and one single influent sample were <br /> collected during the third and forth quarters of 1998. Soil gas/vapor samples were collected on: 29 <br /> ' July(one sample from the effluent due to sample bag failure),31 August/0I September, 01 October <br /> and 25 October 1998 in Tedlar vapor bags using a vacuum pump attached to the influent and effluent <br /> stream. The samples were labeled, placed in a cooler and transported under chain-of-custody to <br /> McCampbell Analytical,Inc. (MAI) in Pacheco. The samples were analyzed by: <br /> • EPA Method 8015Modified for total petroleum hydrocarbons quantified as gasoline(TPH-g) <br /> and <br /> • EPA Method 8020 for volatile aromatics; benzene,toluene, ethylbenzene and total xylenes <br /> (BT EX). <br /> 1 • <br /> The results of the laboratory analysis are summarized in Table 1. <br /> 3.0. FINDINGS <br /> 3.1. SOIL GAS/VAPOR EXTRACTION <br /> ' The SVE unit operated at varying rates during the observation period. Extraction flow rates were <br /> calculated to range from 75 to approximately 90 standard cubic feet pre minute (scfm). Typical <br /> ' operation of the SVE achieved approximately 80 scfm during the period. An induced vacuum of <br /> approximately 20 inches of water was measured in the piping between the blower and extraction <br /> well. <br /> ' One measurement of the induced vacuum of approximately 0.22 inches was measured at well VW-2, <br /> a distance of 20 feet from the extraction well VW-1. Well VW-2 was not under a vacuum when the <br /> induced vacuum was measured. <br /> The SVE unit operated for a total of 1,328 hours during third and part of the forth quarters of 1998. <br /> ' The SVE unit experienced poor operation during November and early December to weather and <br /> suspected power failures. <br /> set of soil gas/vapor samples collected on 29 July 1998'had TPH-g detectedm-'6e�irifluenf vapor <br /> stream at concentrations of 900 micrograms per liter ( zg/1). Toluene, ethyl-benzene and xylenes <br /> were detected in the influent sample at concentrations of 29µg/l, 39,ug/l and 200µg/l, respectively. <br /> 1 • <br /> Advancer!Geo£nviroamental,Inc. <br />