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Remedial Investigation QAPP Stockton Army Aviation Support Facility,California 14.2.3 Soil Boring Sample Collection Surface and subsurface soil samples will be collected from soil borings to ensure contamination identified during the SI has been delineated at depth,to provide data for preliminary screening and evaluation of results as part of the comprehensive HHRA and ERA,and to assist in identifying whether additional subsurface sampling should be performed during Mobilization 2 to further delineate soil contamination. Soil borings will be advanced using sonic drilling methods with hand clearance to 5 feet bgs prior to drilling.A total of four discrete soil samples will be collected from each location:surface soil sample(0 to 1 ft bgs;collected during the hand clearance process), subsurface soil from 5 to 6 ft bgs,subsurface soil from 9-10 ft bgs and subsurface soil approximately 2 ft above the groundwater table. An exclusion zone will be established with cones surrounding the drilling operation. Each boring will be hand- cleared to 5 feet bgs prior to drilling in accordance with utility clearance procedures(Section 14.1.4).The drilling team will place plastic sheeting under the drill rig and will pull it up around the tracks to act as a containment barrier. The drill equipment will be advanced through a tub or surface casing at the ground surface. Refer to Worksheets #17 & #18 for additional details on the sample design, location, and rationale. All sampling materials will be PFAS-free. Lithological descriptions of recovered soil cores will be logged by a field geologist under the supervision of a California P.G., P.E.,or C.E.G., usingthe Unified Soil Classification System (USCS)and in general accordance with the ASTM International Standard D2488 (Standard Practice for Description and Identification of Soil, Visual- Manual Procedure).To the extent possible,field personnel will generate and maintain complete logging records for all soil boring locations, including descriptions of surface soils(i.e.,0-2 ft. bgs)recovered during hand clearing activities. Observations and measurements will be recorded on field forms and in a non-treated field logbook. Photographs of the boring cores will also be taken.At a minimum, depth interval, recovery thickness, moisture, relative density, color(using a Munsell soil color chart), and texture (using the USCS) will be recorded. Refer to Parsons SOP PFAS ENV-05. Soil Borings and Monitoring Well Installation and Parsons SOP PFAS ENV-12: Soil Description and Classification (Appendix D)for additional details. Each soil sample will be collected into laboratory-supplied bottleware and submitted to the laboratory for analysis. The soil sample will be collected using a PFAS-free approved sampling tool (e.g., stainless steel, trowel, or scoop). The laboratory method DLs for the sampled analytes are presented in Worksheet #15. The required sample containers, preservatives, and holding times are specified in Worksheets#19&#30. Refer to Parsons SOP PFAS ENV-02: Soil Sampling, Parsons SOP PFAS ENV-05: Soil Borings Monitoring Well Installation, and Parsons SOP PFAS ENV-12:Soil Description and Classification (Appendix D)for additional details. Borings will be abandoned as described in Section 14.2.15. Subsurface soil sample locations will be marked with a pin flag, stake, or white board with sample identification number, photo-documented, and recorded with a hand-held GPS device.The surface at each sampling location will be restored to match the surrounding area. 14.2.4 Vertical Aquifer Profiling Grab Groundwater Sample Collection VAP sample depths will be determined based on the observed soil lithology, identifying zones of high hydraulic conductivity in which transport may be likely.The lithology boring will be abandoned per Parsons SOP PFAS ENV- 14:Vertical Aquifer Profiling(Appendix D),and a new boring will be advanced for VAP sample collection adjacent to the lithology boring. VAP sampling will be performed using sonic drilling push-ahead sampling.The sampling tool is driven ahead of the drilling operation, in an undisturbed area of soil 18 to 24 inches beyond the drill casing.The push-ahead device is engaged,exposing the screen interval for sample collection. Depending on the depth of the sample interval, a peristaltic pump or bailer/submersible pump(up to 2-inch diameter) can be run PARSONS Worksheet#14&16: Project Tasks and Schedule Page 65