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_ r <br /> r' t <br /> 1 J ly <br /> 30 May 1997 ; <br /> .� AGE-NC Project No 95-0142' <br />' r Page 4 of 6 t r J <br /> r <br /> were removed Temperature,pH, and conductivity were measured at regular intervals using an ICM , <br />' water analyzer The monitored well stabilization data and the field data sheets are included in <br /> Appendix A Purged water was stored on-site in labeled 55-gallon drum ! 7` <br /> 2 4 6 GROUND WATER SAMPLE COLLECTION <br /> i <br /> A water sample was collected from the purged well MW-5 using new, clean, disposable plastic <br /> bailer Immediately upon retrieval, the sample was transferred into 40-m1 VOA vials containing 0 5 <br />' milliliters of 18%hydrochlone acid as a preservative and was then placed in a chilled container The s <br /> sample was transported in under chain-of-custody to MAI analysis <br /> The sample was analyzed for total petroleum hydrocarbons quantified as gasoline (TPH-g), volatile <br /> aromaticsbenzene toluene eth lbenzene and <br /> ( y xylenes BTE&X) and methyl-tert-butyl ether „ <br /> (MTBE) in accordance with the EPA methods noted above ` <br /> Ir <br /> 3.0. FINDINGS <br /> 3 1 GROUND WATER GRADIENT AND DIRECTION <br /> Ground water at the site ranged from 30 20 feet to 3102 feet below the well casing tops The average <br /> ground water elevation increased approximately 4 feet between December 1996 and March 1997 <br />' The significant increase of ground water elevation has been observed through the Central Valley - <br /> region The,magnitude of this increase is not typical of the seasonal increase observed at the site in <br /> previous years <br /> is <br /> During the March 1997 monitoring event, the hydraulic gradient was approximately 0 00125 ft/ft, <br /> directed toward the east The relative ground water elevation data is depicted in Table 1 - Relative <br /> Ground Water Elevation The relative elevation of ground water surface at the site is illustrated on <br /> Figure 3 - Relative'Ground Water Elevation <br /> I1 > <br /> 32 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> I' TPH-g was detected in sarnples collected from wells VW-I through VW-4'at concentrations ranging <br /> from 3,100 to 190,000 parts per billion (ppb, reported as micrograms per later) BTE&X compounds <br /> Iwere detected in samples from each vapor well,at concentrations,as high as 40,000 ppb (toluene, <br /> . <br /> VW-1) ' Additionally, MTBE was detected in samples collected from each vapor well at <br /> concentrations as high as 700 ppb (VW-1) <br /> i <br /> r 1 <br /> t I <br /> i <br /> - 1 1_ <br />