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Remedial Investigation QAPP Stockton Army Aviation Support Facility,California Monitoring wells will be constructed of 2-inch diameter, schedule 40 poly-vinyl chloride (PVC), 10-foot long 0.01-inch slotted screens, and 10-foot sections of schedule 40 PVC flush threaded riser pipe. A 10 to 20-grade silica sand filter pack material will then be placed in the annulus between the well pipe and casing. The height of the filter pack above the top of the screen interval will be 2 feet. As the filter pack is placed in the borehole, the temporary casing will periodically be vibrated and pulled up, allowing the well materials to settle into the borehole. If stick-up casings are used, protective bollards will be installed at each corner of the concrete well pad. Time-release bentonite chips will be placed in the annulus, above the filter pack, and allowed to hydrate. The bentonite seal will be at least 2 feet thick. The hydration time will be per the recommendations of the bentonite manufacturer, which is 2 hours for typical types of bentonite chips. Once the bentonite seal has hydrated, cement-bentonite grout will be placed in the annulus from the top of the bentonite seal up to the ground surface. Cement-bentonite grout placement will continue until the outer casing is removed from the borehole. Monitoring wells will be completed as either flush-mounts using an 8-inch diameter, bolt-down manhole cover with 12-inch poly skirt or stick-up well casings with manhole/standpipe centered in a 2-foot by 2-foot by 8-inch- thick concrete pad. The preference of flush-mount or stick-up well casings will be determined based on Facility preference. 14.2.6 Soil Sample Collection from Permanent Well Borings During installation of permanent monitoring wells, borings will be advanced using sonic drilling as described above in the procedures for Permanent Monitoring Well Installation. All soil cores collected via drilling for well installation will be logged for Iithological descriptions.Atotal of three soil samples will be collected from each well location for PFAS analysis: one surface soil sample (0 to 1 ft bgs; collected during the hand clearance process), one shallow subsurface soil sample from 5 to 6 ft bgs (collected during the hand clearance process), and one subsurface soil sample approximately 9 to 10 ft bgs. One soil sample (from various depth intervals at each location) will be analyzed for TOC (USEPA Method 9060A) and pH (USEPA Method 9045D). Geotechnical soil samples will be collected from the deepest sample intervals at permanent monitoring well locations. Soil samples will be analyzed under standard turnaround time(TAT)for grain size analysis with sieve and hydrometer (ASTM D-422), as specified in Worksheets#17 &#18. Each sample will be collected into laboratory-supplied bottleware and submitted to the laboratory.The laboratory method DLs for these 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-05:Soil Borings and Monitoring Well Installation (Appendix D)for additional details. 14.2.7 Permanent Monitoring Well Development Permanent monitoring wells will be developed no sooner than 48 hours after completion of well installation when a cement bentonite grout is used to seal the annular space but shall be developed within seven days of well installation. Development will be completed by a combination of surging with a surge block, and over-pumping with a submersible monsoon pump or Waterra pump and associated high-density polyethylene(HDPE)tubing, in accordance with Parsons SOP PFAS ENV-06:Monitoring Well Development(Appendix D). Water clarity will be visually monitored and water quality parameters, including dissolved oxygen (DO), specific conductivity (SC), oxidation reduction potential (ORP), pH, temperature, and turbidity will be measured using a flow-through cell (per Parsons SOP PFAS ENV-03:Groundwater Sampling)approximately every 5 minutes during purging to determine progress of development.The water quality meter will be calibrated initially and continually throughout its usage each day, as needed.A calibration check will be performed at the end of each day. Each PARSONS Worksheet#14&16: Project Tasks and Schedule Page 67