ARCHIVED REPORTS XR0001708 - Laserfiche WebLink

Home Browse Search

12 February 1999 • AGE-NC Project No. 95-0109 Page 2 of 4 2.2. COLLECTION OF GROUND WATER SAMPLES The depth to water in each purged well was remeasured after purging to ensure a minimum of 80 per cent recharge prior to sampling. Water samples were collected from each purged well using disposable plastic bailers. Immediately upon retrieval,the samples were transferred into 40-m1 EPA- approved VOA vials containing 0.5 ml 18%hydrochloric acid as a sample preservative. The samples were labeled, stored on ice, and transported in a chilled container, under chain-of-custody, to McCampbell Analytical, Inc. (MAI) in Pacheco, California, a California Department of Health Services (DHS)-certified laboratory. All samples were analyzed for: • Total petroleum hydrocarbons quantified as gasoline (TPH-g) in accordance with EPA Method 5030/8015m; • Volatile organic compounds (benzene, toluene, ethylbenzene and xylenes; BTEX) with methyl tertiary-butyl ether(MTBE) in accordance with EPA Method 602; and • Volatile organic compounds with oxygenated compounds (di-isopropyl ether [DIPE], ethyl tertiary-butyl ether [ETBE], MTBE,tertiary-amyl methyl ether [TAME] and tertiary-butanol [TBA]) in accordance with EPA Method 8260/8260m. • 3.0. FINDINGS 3.1. GROUND WATER GRADIENT AND DIRECTION The depth to ground water ranged from 50.65 feet below surface grade (bsg) north of the site to 53.78 feet bsg south of the site. The data indicates an average 1.04 feet increase of ground water elevation since September 1998. Ground water elevations are summarized on Table 1. Ground water elevation contours, based upon data collected on 21 December 1998, are depicted in Figure 3. The inferred ground water flow direction is toward the south. Ground water elevations for MW-I through MW-3 were higher than the surrounding wells. These wells exhibit poor recharge and do not appear to be in equilibrium with the surrounding ground water. Therefore data from these wells was not used to determine the ground water flow direction. The depth to ground water in MW- 9 was higher than expected, based upon data from surrounding wells. Remeasurement of ground water depth following purging confirmed the initially measured depth to ground water. Advanced GeoEnvironmental,Inc.