Source Zone Delineation Demonstration Report - Triad Resource ...

3.0 WIRELINE CPT SOIL SAMPLING DEMONSTRATIONThe design of the Wireline CPT demonstration was based on data obtained from previous siteinvestigation and characterization activities conducted at OU 12. To formulate the design basis,numerous data sources were reviewed, including site stratigraphy obtained from cone penetrometersoundings, groundwater analytical data, and soil-gas concentration data obtained during the two phases ofsoil-gas sampling conducted within the suspected OU 12 source zone. These data were used to formulatethe preliminary CSM and identify the initial sampling plan associated with the Wireline CPTinvestigation. An adaptive sampling and analysis strategy was used during the demonstration and wasbased on field-generated data subjected to professional interpretation by the Core Technical Team.Characterization of the spatial extent and magnitude of TCE contamination in the vadose zone wasconcurrent with field sampling efforts. Iterative, short-delay modeling of the extent of contaminationprovided field personnel with guidance for selecting new Wireline CPT sampling locations during siteinvestigation activities.3.1 Wireline CPT Technical ApproachThe Wireline CPT demonstration was conducted within the vadose zone and capillary fringe underlyingthe general area defined as the suspected zone at OU 12. The investigation focused on TCE analysis ofvadose zone soils, since the TCE groundwater plume emanating from OU 12 had been previouslydefined.Based on the indirect evidence cited in Section 2.0 of this report in relation to the suspected source zonelocation, high-density soil sampling and analysis coupled with a judgment-based decision process forsample selection was utilized during the Wireline CPT demonstration. Judgment-based samplingdecisions were intended to maximize the likelihood of locating and delineating the suspected TCE sourcezone at OU 12 within the limited deployment time allocated. The total decision error (sampling error andmeasurement error) associated with this demonstration was minimized by the following:Collecting a high number of soil samples within a vertical trace using CPT coupled with the Wirelinesoil sampler.Processing a high number of soil samples using Tri-Corders Environmental, Inc.'s DSITMS (EPASW 846 modified method 5035).Providing a high number of quality assurance (QA) samples relative to the number of site samplesusing the DSITMS.Using a judgment-based sampling and analysis strategy based on in-field expertise to guide soilsampling and analysis.The initial proposed sampling transect for the Wireline CPT demonstration is shown in Figure 3-1. Thisinitial sampling transect was based on the fact that the recently discovered buried drums did not correlateexactly with the apparent origin of the groundwater plume or the highest concentration of TCE observedduring the soil-gas survey at OU 12. It was surmised that any TCE trapped within the vadose zone wasMarch 2003 3-1 OU 12 Demonstration ReportFinal