ARCHIVED REPORTS_XR0007029 - Laserfiche WebLink

Home Browse Search

I ' 05 September 2002 AGE-NC Project No 95-0141 Page 2 of 5 ' 2 2 GROUND WATER SAMPLE COLLECTION ' A water sample was collected from each well using a new, clean, disposable plastic bailer Immediately upon retrieval, the sample was transferred into three properly labeled 40-nil. EPA- approved VOA vials containing 0 5 ml 18%hydrochloric acid as a sample preservative The samples were logged on a chain-of-custody form, stored in a chilled container and transported under chain-of custody to Cal Tech Analytical Laboratories (CTEL), a California Department of Health Services ' (DHS)-certified laboratory The ground water samples were analyzed for • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 8015 Modified, • Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 8021, and • The oxygenated compounds df-isopropyl ether (DIPS), ethyl tertiary-butyl ether (ETBE), MTBE, tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), 1,2-dibromoethane '• (EDB) and 1,2-dichloroethane (1,2-DCA) in accordance with EPA Method 8260B, respectively 3.0. FINDINGS Ground water elevations and flow directions were inferred from field data Hydrocarbon-impact to ground water was characterized from laboratory analytical data 31 GROUND WATER ELEVATION AND GRADIENT The average ground water elevation of the seven shallow ground water monitoring wells on 05 August 2002 was approximately 12 85 feet below mean sea level (ms]), with the average depth of water at 20 5 feet below casing tops The ground water table occurred within the screened intervals of wells MW-7 and MW-8 but was between 8 29 and 9 87 feet above the screened intervals in monitoring wells MW-1 through MW-5 Monitoring well MW-6 was designed as a piezometer, with a 5-foot screened interval set at approximately 39 feet below the water table, since it possibly is monitoring a different hydraulic zone, MW-6 was not used to determine gradient and flow direction ' Based on data collected during the August 2002 monitoring event,the groundwater table underlying the site formed a south-southwest-trending nose plunging at a gradient of 0 002 ft/ft The western Ilimb of the trough flowed westerly, the eastern limb's flow direction was southeast Advanced GeoEnvfmnmentat,Inc