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1 <br /> 1 <br /> 18 March 1996 <br /> r AGE-NC Project No 95-0143 <br /> Page 3 of 4 <br />' 3 2 COLLECTION OF GROUND WATER SAMPLES <br /> Water samples were collected from each purged well using new disposable bailers and transferred into <br /> 40-m1 EPA vials containing hydrochloric acid as a sample preservative The samples were transported <br />' <br /> in a chilled contarmer to McCampbell Analytical, Inc , Pacheco, California (MAI), and were analyzed <br /> for total petroleum hydrocarbons quantified as gasoline (TPH-g) and volatile organics (benzene, <br /> toluene, ethylbenzene and xylenes BTE&X) in accordance with EPA methods 5030 and 602, <br />' respectively <br />' 4.0. FINDINGS <br /> 4 1 RELATIVE GROUND WATER ELEVATION AND GRADIENT <br /> The relative elevation of ground water in each well was calculated by subtracting the depth to water <br /> from the surveyed casing elevation (Table 1) Ground water rose an average of 0 66 feet between <br /> November 1995 and February 1996 The approximate gradient was calculated to be 0 0018 ft/ft <br /> directed north to northeast Relative ground water elevation contours for the February 1996 <br /> monitoring event are illustrated as Figure 3 <br /> I42 ANALYTICAL RESULTS OF WATER SAMPLES <br /> TPH-g was detected in samples from 1VRAI-6, MW-7 and MW-9 at concentrations of 1,500 ,ug/1 <br /> (micrograms per liter, equivalent to parts per billion ppb), 27,000 ppb and 64,000 ppb, respectively <br /> BTE&X were detected in the same wells at concentrations as high as 13,000 ppb (xylenes, MW-9) <br /> Free product was encountered in MW-3,therefore, no Sample was collected Petroleum hydrocarbons <br /> wei e not detected in samples from MW-10, MW-14, MW-15, MW-16 or MW-17 Analytical results <br /> are summarized on Table 3 The laboratory report (MAI Laboratory I D pros 61436 - 61443) and <br /> chain-of-custody form are included in Appendix B <br /> 5 0. CONCLUSIONS & RECOMMENDATIONS <br /> Petroleum hydrocarbons were not detected in wells MW-10, MW-14, MW-15, MW-16 and MW-17, <br /> thereby defining the maximum extent of impacted ground water Only a thin layer of free product is <br /> still present in MW-3 However, the dissolved hydrocarbon plume extends at least 200 feet north of <br /> the former UST area Removal of free product, when present, should continue at the site <br /> An air sparging pilot test was performed at the former Chase Chevrolet facility at 423 North Madison <br /> Street, one block to the east of the site, and a Corrective Action Plan (CAP) submitted Since the two <br /> I <br />