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10 October 1997 <br /> AGE-NC Project No '95-0142 <br /> Page 2 of 4 r <br /> r <br /> 22 GROUND WATER SAMPLE COLLECTION <br /> Water samples were collected from each purged well (MW-3,MW-4,MW-5,VW-1 through VW-4) <br /> - using new,clean,disposable plastic bailers Immediately upon retrieval,the samples were transferred <br /> Into 40-m1 VOA vials containing 0 5 milliliters of 18%hydrochloric acrd as a preservative and were <br /> then labeled and placed in a chilled container The samples were transported in under chain-of- <br /> custody to McCampbell Analytical, Inc , (MAI) in Pacheco, California for analysis <br /> All samples were analyzed-in-accordance with, EPA Method 8015/5030 for total petroleum <br /> hydrocarbons quantified as gasoline (TPH-g), EPA Method 602 for volatile organic compounds <br /> (benzene, toluene, ethylbenzenc and xylenes BTE&X) and methyl-tert-butyl ether (MTBE) and <br /> EPA Method 8260 for oxygenated fuel additives <br /> 3 0. FINDINGS <br /> 3 1 GROUND WATER GRADIENT AND DIRECTION <br /> Ground water at the site ranged from 3100 feet to 32 44 feet below the well casing tops The average <br /> ground water elevation decreased approximately 0 6 feet between June and September 1997 <br /> During the September 1997 monitoring event,the hydraulic gradient was approximately 0 008 ft/ft,' <br /> directed toward the northeast from TKI-90 The relative ground water elevation data Is depicted in <br /> ITable 1 -Relative'Ground Water Elevation Data ,The relative elevation of ground water surface at <br /> the site is Illustrated on Figure 3 - Relative Ground Water Elevation <br /> I3 2 'ANALYTICAL RESULTS'OF O GROUND WATER SAMPLES <br /> I r <br /> TPH-g was detected in samples collected from wells VW-1 through VW-4 at concentrations ranging <br /> from 110 to 190,000 parts per billion(ppb, reported as micrograms per liter) BTE&X compounds <br /> were detected in-samples from each vapor well at concentrations as high as 38,000 ppb (toluene, <br /> VW`1) - <br /> Benzene was detected in VW-1 at a concentration of 29,000 ppb MTBE was detected in water <br /> samples collected from each vapor well at concentrations as high as 920 ppb (VW-1) by EPA <br /> method 8020 and were confirmed at concentrations as high as 720 ppb by EPA method 8260 <br /> TPH-g was detected in the sample collected from well MW-5 at a concentration of 300 b BTE&X <br /> - p pp , <br /> compounds were detected in the same sample at concentrations as high as 9 1 ppb (benzene) MTBE <br /> Advanced GeoEnvironmental,Inc <br /> I i <br />