SITE HISTORY - Laserfiche WebLink

Home Browse Search

'`r" N.W." man crew were supplied by Turner Drilling. The borings were advanced using eight-inch diameter continuous flight hollow stem augers. Auger returns were monitored during drilling activities for the presence of organic vapors using a photo-ionization detector (PID: Thermo Environmental 580A, 10.0 eV, calibrated to isobutylene). Discrete soil samples were collected in all borings at five-foot intervals. Soil samples were not analyzed in Boring B2 and B3 due to the absence of organic vapors. Soil samples were collected at depths of 25, 30, and 35 feet bgs; and at 50, 55, and 60 feet bgs in Boring B4. A 140-1b hammer was used to advance a sampler loaded with three precleaned 2 x 6 inch brass sleeves. The number of blows required to advance the sampler in 6-inch increments was recorded on the boring logs (See Appendix A). To avoid cross contamination, the y hollow stem augers and drill bit were steam cleaned by the drill crew utilizing a portable decontamination unit, prior to drilling each boring. Prior to the collection of each sample, the sampling equipment was decontaminated in a tri-sodium phosphate (TSP) solution and rinsed twice with water. For each sample collected, the lead brass sleeve was removed and immediately covered with aluminum sheets, capped, sealed with tape, and logged under chain of custody procedures. The samples were immediately placed in a chilled container. Upon completion of drilling activities, the samples were transported and relinquished to McCampbell Analytical, Inc., a state certified analytical laboratory, for analysis. Soil from the middle brass sleeve was extruded into a plastic bag and screened for organic vapors using a photo-ionization detector (PID). The reading was recorded on the boring log, and the soil was described in accordance with the Unified Soil Classification System. 3.2 Laboratory Analysis of Soil Samples Selected soil samples were analyzed for total petroleum hydrocarbons (TPH) as gasoline and volatile aromatics(BTE&X)in accordance with EPA methods 8015m and 8020, respectively. All samples were analyzed by McCampbell Analytical, Incorporated. 3.3 Findings 3.3.1 Stratigraphy The borings penetrated soil units consisting of various mixtures of clay, silt, and sand from the surface to 60 feet bgs. A dense, very cohesive, brown clay was encountered in Boring B4 from a depth of 45.5 - 49 feet bgs. This clay layer may have created a barrier to petroleum hydrocarbons transport into greater depths. The variations in the depth of the contacts between sand beds and finer-grained beds such as silts in adjacent borings suggests considerable interfingering of the units. These characteristics are typical of fluvial channel and overbank deposits. G-1.0-1 Audis Servk-.Inc. 6 902-SC$m. RpUDoe'L BuMie r