Laserfiche WebLink
g <br /> 8&W 1 A <br /> Mr <br /> ' �WAU; U <br /> 7T <br /> 001 ME <br /> 3.0 REStILTS OF INVESTIGATION <br /> 3.1 Laboratory Annlyflin <br /> Analytical roculto for soil 04mPle" and groundwater fleMP10a Are <br /> ou"marized in Table 1. Laboratory J4tA ohacta, QpQC rep , <br /> and chain-of-cuntody documantation are pronontod tn AppandixortsD. <br /> 3.2 Quality Ausuranco/QuOlitY Control Evaluation <br /> Standard laboratory QA/QC was followed for analyoin Of soil and <br /> groundwater "ampler. Laboratory spikes and duplicatot, provide an <br /> estimate Of sample Analysis variance in order to establish vari- <br /> ance related to field nampling and laboratory handling. The <br /> laboratory quality control reports for the sample analydan indi- <br /> cate very low analytical variance. <br /> 3.3 Site Stratigraphy <br /> Soil borings generally encountered fine grained, low permeability <br /> voila. Loan and fat cl*Ya wore generally observed In the 15 to <br /> 25 foot zone. sandy silts to silty sands occurred from 15 to 35 <br /> foot again depending on the boring. A return to loan clays <br /> ' agteId the two a oil. borings that wont beyond the 30 foot <br /> dominated auented in Figures 4 and 5, with <br /> dapth. Croan-aectiOnO are pr <br /> plan view orientations shown on Figura 3. <br /> 3.4 Field Inspection <br /> Soils encountered were monitored for organic vapors by placing a <br /> small amount of representative material in a sealed container, <br /> thn chcking for potrulcum hydrocarbon odors. ors were noted <br /> ateeachemeasurement point and recorded on the boroindg 1093- <br /> Soil samples submitted for analysis were selected based on obvi- <br /> oua signs of contamination (i.e. odors, cementation and soil <br /> discoloration) . The sample indicating the highest signs of <br /> contamination were analyzed to determine concentrations. Two <br /> "clean' confirmation samples, representing a to foot Interval, <br /> were collected and analyzed to determine the vortical extent of <br /> the soil cont=ination. The samples to be submitted for analysis <br /> which were at ambient ground temperature, <br /> were cooled as quickly <br /> ajuapoos'b'o by placement in an insulated ice chant with frozen <br /> b ice. After initial cooling, samples were maintained between <br /> 0 and 4 degrees centigrade. Samples were collected, preserved, <br /> and transported with a max/min thermometer under chain-of-custody <br /> in accordance with WaterWork's QA/QC Plan (Appendix C) . <br /> 4.0 CONCLUSIONS <br /> Laboratory analysis of the soils beneath the previous tank pit <br /> shows high levels of gasoline hydrocarbons at depth between 10 <br /> and 20 feet. The concentrations of gasoline hydrocarbons drop <br /> -----off-significantly with depth--- du,- to the low permeability Of the <br />