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12 October 1995 <br /> . AGE-NC Project No. 95-0112 <br /> Page 5 of 6 <br /> 4.2. FIELD AND LABORATORY RESULTS OF SOIL SAMPLES <br /> ' Organic vapors were detected in boring SW-1 from depths of 40 to 55 feet at concentrations up to <br /> 660 parts per million (ppm). Organic vapors were detected in boring SW-2 from depths of 40 to 60 <br /> ' feet at concentrations up to 762 ppm. <br /> Three soil samples form each boring were submitted to Alpha Analytical Laboratory (AAL) for <br /> ' analysis. TPH-g was detected in samples SWI-50, SW240 and SW2-50 at concentrations of 97, 1.4 <br /> and 120 mg/kg (ppm), respectively. Toluene, ethylbenzene and xylenes were detected in samples <br /> SWI-50 and SW2-50 at concentrations up to 3.5 ppm. No petroleum hydrocarbons were detected <br /> ' in samples SWI-40, SWI-55 or SW2-55. <br /> ' 4.3. GROUND WATER ELEVATION AND FLOW DIRECTION <br /> The relative elevation of ground water in each well was calculated by subtracting the ground water <br /> ' depth from the surveyed casing elevation (Table 2). Ground water elevation has risen an average of <br /> 0.19 feet since the April 1995 monitoring event. <br /> MGround water flow continues to slope to the southwest at the site (Figure 3). A large mounding was <br /> observed near MW-4. The overall gradient is similiar to that during previous monitoring events. <br /> 1 <br /> 4.4. LABORATORY ANALYSIS OF GROUND WATER SAMPLES <br /> ' - was detected in round water samples from MW-1, MW-3, MW-4 and MW-5 at <br /> TPH g $ P <br /> concentrations of 37,000, 18,000, 150 and 942 gg/l (parts per billion: ppb), respectively. BTE&X <br /> ' were detected in samples from MW-1, MW-3 MW-4, MW-5 and MW-8 at concentrations up to <br /> 6,200 ppb (benzene in MW-1). Petroleum hydrocarbons were not detected in samples from MW-6 <br /> or MW-7. The analytical results of all water samples are summarized in Table 3. The laboratory <br /> ' report and chain-of-custody are included in Appendix D. <br /> 4.5. SOIL AND GROUND WATER REMEDIATION <br /> The installation of the vapor extraction and air sparging unit took place on 13 and 31 July 1995, <br /> respectivley. Organic vapor-readings(PID)were collected intemn ttently at the;site-during-the start-up -< <br /> period. PID readings collected between 13 July and 31 July ranged from 1351 ppm to 1620 ppm. <br />