ARCHIVED REPORTS XR0010529 - Laserfiche WebLink

Home Browse Search

Unit 5-- This unit consists of dark brown clay that is moderately cemented by veins of caliche Small root tubes or desiccation holes are abundant in this unit, which appears to be an ancient soil horizon During excavation, unit 5 emitted strong gasoline odors, and a slight odor was detected in sample JL- P-13 when this unit was sampled Unit 6-- The brown clay is locally underlain by unaltered gray clay This may be a separate hthologic unit, or it may be unweathered parent material for the soil horizon of unit 5 Unit 7-- This fine-to-medium-grained gray sand bed could be traced throughout the excavation and is several feet thick in most places No hydrocarbon odors were detected in this bed during confirmatory sampling Unit 8--Unit 8 was observed only on the east wall at sample point JL-P-23 below a depth of 26 feet It consists of gray to white well-sorted coarse-grained sand typical of mayor stream channels The absence of this bed on the west sidewall suggests that the base may be strongly erosional (Figure 7) Unit 9-- On the west sidewall, greenish-gray plastic clay was observed directly beneath unit 7 at sample point JL-P-14 The coarse-grained sand of unit 8 was not present The clay was traced northward to sample point JL-P-17, where it was 2 feet thick Unit 10-- Sample JL-P-17 was collected from gray, silty, fine-grained sand at a depth of 40 feet on the west sidewall The contact with unit 9 was observed at a depth of 32 feet, and unit 10 extended to the • deepest portion of the excavation at a depth of 41 feet The cross sections illustrate that most layers are flat-lying in the north-south direction but dip from east to west at an inclination of approximately 4 degrees This amount of dip is somewhat greater than expected for the Pleistocene-age strata in the area 5.2 Depth to Groundwater Groundwater was not encountered during excavation Normal soil moisture was present from approximately 30 feet to the base of the excavation, but no increase in moisture content that could be construed as the capillary fringe was observed According to Mr Fisk, water is produced from a domestic well in the rear portion of the property Mr Fisk estimated that at the time of this investigation, groundwater was present at a depth of 38 feet in this well Upgradient collected water sample JL-well from the well faucet for laboratory analysis 6.0 LABORATORY RESULTS The locations of samples JL-P-7 through JL-P-26 are shown in Figures 4 and 6-8 Excelchem analyzed these samples for TPH-gasoline and BTEX, and the analytical results are listed in Table 1 The complete laboratory report is included in Appendix A 5