ARCHIVED REPORTS XR0012922 - Laserfiche WebLink

Home Browse Search

Groundwater Sampling Each exploratory boring was sampled. The ground water samples collected from the boreholes was used for a rapid reconnaissance of site groundwater contamination. The boreholes were sampled using the Wright Sampling Protocol, a brief summary of which follows: Each borehole was advanced about 4-feet into the aquifer. The water entering the borehole was sampled using a clean bailer, and carefully poured into the appropriate laboratory prepared container with minimum cavitation. Depth to groundwater measurements was made to the nearest one-one hundredth of one foot at the surface grade, and also checked for the presence of separate phase product. Each water sample was labeled, logged onto a chain-of-custody form, and placed in a chilled ice chest. Upon completion of the borehole sampling, the borehole was sealed as noted above. Subsurface Conditions Six exploratory soil borings were advanced on-site at the locations shown on Figure 1. PB-1 through PB-6 were drilled for site assessment for possible vadose zone contamination in the former tank pit area and dispenser. The site is underlain by clayey soils which contain silt and sand to depths of roughly 6- to 10-feet. These sediments are in turn underlain by sandy and clayey sediments to the maximum depth explored of 15-feet. The sediments appear to grade laterally with each other and lateral and vertical changes occur over the site. Concrete rubble and fill sediments were observed in the former aviation gas underground storage tank pit, and were underlain by native soils. Upon completion of sampling groundwater all borings were sealed with cement grout using a tremie line. Groundwater was encountered in each borehole at depths of roughly 8- to 11-feet and is interpreted to be unconfined in the area. Slow entry was observed in some boreholes. The boreholes were terminated into a clay strata which is assumed to be continuous under the site. The irrigation canal just north of the site was filled with water and was flowing to the east. It is surmised that recharge occurs through the unlined canal bottom when the canal is filled. While regional groundwater flow in this area is interpreted to be northerly, recharge from the canal may locally influence shallow subsurface flow. Chemical Analysis and Results Nine soil and six groundwater samples were analyzed at Priority Environmental Laboratories, Inc. in Milpitas, CA, a State certified analytical laboratories. Samples were tested for the following; Total Petroleum hydrocarbons as Gasoline (TPHG), as Aviation Fuel (TPHA), as Kerosene (TPHK), Benzene (B), Toluene (T), Ethylbenzene (E), Xylene (X), Methyl-tertiai- buyti-ether (METE) and Total Lead using EPA Methods 5030, 8015, 8020, 602 and 7420. The results are attached (see Appendix D) and listed below in Tables 1 and 2. Haley Flying Services Project No. 4111 Page 4