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V 10 . !I 28 July 2003, r 5w i i AGE-NC Project`No_95-0114 'P4ge'2 of 5 2.2. COLLECTION AND ANALYSIS:OF GROUND WATER.SAMPLES_ Ground water samples were collected from.the purged wells using.new disposable bailers.following:f recovery,of at least.80%o of the pre=purge,casmg water'volurne. immediately upon retrieval, the,; ' samples were transferred into 40-ml-EPA-approved volatile organic analysis(VOA)vials containing 0.5 aril of hydrochloric acid(18%0)as a sample preservative,and were properly labeled.The samples:' were 'transported in a..chilled• container under chain-of-custody'to. Cala Tech- Environmental. Laboratories; Inc. (CTEL); a`.State'of California Department of Health:Services;{DHS}-ceifiified laboratory in Paramount, California. The samples were analyzed.for: ; • Volatile organic.com pounds VOCs `iricludin� benzene toluene eth lbenzene and xylenes p { )� g Y. „ Y (BTE&X)and the fuel additives ethylene dibromide(EDB);.1,2-dichloroethane(1;2713CA), tertiary butanol (TBA), di-isopropyl ether (RIPE);ethyl tert butyl ether,(ETBE), tert amyl m6thyl ether(TAME), and methyl tertiary butyl ether(MTBE)by EPA Method 8260B; and • . Total petroleum hydrocarbons quantified as stoddard solvents (TPH=ss) by EPA Method 8015 Modified. 3.0. FINDINGS ; Ground water flow direction and gradient were inferred from the field data. The current distribution of dissolved petroleum hydrocarbons and dissolved chlorinated'hydrocarbons was assessed from, laboratory analytical results of the soil and-ground water samples: I ' 3.1. GROUND WATER GRADIENT AND'DIRECTION During the May 2003 ground water monitoring'event, the depth to ground water at,the'site fanged from 24.37 to 25.47 feet below the tops of the well casings.The ground water elevation ranged from 15.36 to 16.24 feet below mean sea level (MSL). The ground water flow direction was toward the o ° ,northeast from well MW-5 toward well MW-10,with a gradient of approximately 0.0013 feet/feet: Ground water elevation data are summarized'in Table 1. The contoured ground Water elevation for theground water monitoring event is depicted in Figure 3, Wells MW-1 through MW-5 were screened between 30 or 34 and 50.feet bsg;wells_MW-6 through MW-10,were screened between 20,or 25 and 45 or 50 feet bsg., The ground',water level was more -than 16 feet above the tops of the screened intervals ofwells MW 71 and MW-2,almost 6 feet above ' the tops of the screened intervals ofwells MW-3R,MW-4 and MW-5,and at the tops of the screened intervals`of wells MW-6 through MW_10. n ; Advanced GeoEnvironmentstL Inc. ;