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Remedial Investigation QAPP Stockton Army Aviation Support Facility,California in the string to collect a water sample. Sample points will be purged until water is visually clear of sediment or for a maximum of 20 minutes before collecting groundwater samples. Samples are anticipated to be collected at a frequency of approximately one every 15 feet along the vertical profile of the aquifer being characterized. Frequency and number of samples may vary based on field conditions, soil logging observations, and/or interpreted hydrostratigraphy. Refer to Worksheets #17 & #18 for additional details on the sample design, location,and rationale.All sampling materials will be PFAS-free. Refer to Parsons SOP PFAS ENV-05:Soil Borings and Monitoring Well Installation, Parsons SOP PFAS ENV-12: Soil Description and Classification, and Parsons SOP PFAS ENV-14: Vertical Aquifer Profiling(Appendix D)for additional details. Borings will be abandoned as described in Section 14.2.15. VAP 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; measurements with an engineer's tape to the sample location from two fixed surface features (e.g., building corner)will also be made, if applicable.The surface at each sampling location will be restored to match the surrounding area. 14.2.5 Permanent Monitoring Well Installation New permanent monitoring wells will be installed in several locations across the Facility during RI Mobilization 1. Well installation will be completed in accordance with San Joaquin County Well Standards (Ordinance Code Section 9-1115.6,San Joaquin County, 2005),state guidelines,and Parsons SOP PFAS ENV-05:Soil Boring and Monitoring Well Installation (Appendix D).A drilling contractor certified as a California State Board of Water Well Contractor will be used for installation of monitoring wells. A permit application will be completed with the San Joaquin County Environmental Health Department for approval prior to installations; Parsons will comply with requirements, including inspections, required by San Joaquin County. Following installation, monitoring well construction reports will be filed with the California Department of Water Resources. The specific monitoring locations and target screen intervals are specified in Worksheets#17&#18. An exclusion zone will be established with cones surroundingthe drilling operation. Each well boringwill be hand- cleared to 5 feet bgs prior to drilling in accordance with utility clearance procedures (Section 14.1.4). If soil samples are required to be collected at less than 5 feet bgs at the location,the soil will be collected during hand clearance. 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 will be advanced through a tub or surface casing at the ground surface. Monitoring wells will be installed using sonic drilling to collect continuous soil cores to the target depth(specified in Worksheets #17 & #18). The sonic rig will advance a 6-inch diameter core barrel to obtain continuous subsurface samples in 5-foot or 1-0-foot increments.After a soil core is obtained from the 6-inch core barrel,the 8-inch temporary override casing will be advanced to the same depth as the 6-inch core barrel.The 6-inch core barrel and temporary override casing will be advanced through the subsurface to the target depth specified in Worksheets#17&#18. The soil cores will be continuously logged for lithological descriptions by a field geologist, under the supervision of a California P.G., P.E., or C.E.G., using the USCS. Observations and measurements will be recorded on field forms (digital or untreated hard copy). 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.Additional observations to be recorded may include groundwater or perched water depth, organic material, or cultural debris. Refer to Parsons SOP PFAS ENV-05:Soil Boring and Monitoring Well Installation and Parsons SOP PFAS ENV-12:Soil Description and Classification(Appendix D)for additional details. PARSONS Worksheet#14&16: Project Tasks and Schedule Page 66