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Site Inspection UFP-QAPP Addendum <br />Stockton AASF, Stockton, California <br />696 IJAPP Worksheet #17: Sampling Design and Rationale <br />697 Worksheet #17a -e describes the sampling design, basis for its selection, and field investigation <br />698 details. Field activities will be completed per the Standard Operating Procedures (SOPs) in <br />699 Appendix B. <br />700 The objective of the SI is to identify whether there has been a release to soil and groundwater (if <br />701 present) at each AOI and determine the presence or absence of PFOA, PFOS, and PFBS at or <br />702 above SLs, as well as the presence or absence of 15 additional PFAS at the facility. As discussed <br />703 in Worksheet #10, three AOIs were identified at Stockton AASF. Regional groundwater at <br />704 Stockton AASF generally flows to the east/northeast. <br />705 AOI 1 is the Airfield. Potential PFAS releases to soil occurred at AOI 1 as early as 1992 <br />706 during fire extinguisher familiarization. The training occurred on a once -annual basis until <br />707 approximately 2010 and occurred less frequently after 2010. During the training, personnel <br />708 would discharge the Tri-MaxTM fire extinguishers in the northeast direction towards the <br />709 center of the airfield. The quantity and percentage of AFFF released at AOI 1 are unknown. <br />710 AOI 1 also includes a former Wash Rack; however PFAS releases to the former Wash Rack <br />711 are not known. <br />712 AOI 2 is the Wash Rack. Potential PFAS releases to soil occurred at AOI 2 as early as 1992 <br />713 during fire extinguisher familiarization. The training occurred on a once -annual basis until <br />714 approximately 2010 and occurred less frequently after 2010. A HAZMAT locker was <br />715 observed at AOI 2 for AFFF storage. The quantify and percentage of AFFF released at AOI <br />716 2 are unknown. <br />717 AOI 3 is the Butler Building Parking FTA. Potential PFAS releases to the paved surface at <br />718 Butler Building parking lot occurred as early as 1992 during fire training activities. AOI 3 was <br />719 used for fire training activities that involved extinguishing live fire from jet propellant fuel that <br />720 was poured and then ignited in tray pans. The precise location, amount, and type of AFFF <br />721 released to the pavement and the condition of the pavement are not known. The soil <br />722 beneath the parking lot was disturbed during construction and was used to fill in a <br />723 depression on the west side of the road. Exact locations of soil refill could not be confirmed. <br />724 Environmental media samples will be collected from the AOI in accordance with the applicable <br />725 CSM, as summarized in Table 17-1. Temporary monitoring wells will be installed where PFAS <br />726 were potentially released and downgradient of the potential source areas. <br />727 In instances where deviations from this sampling design and rationale are made due to <br />728 unforeseen Site conditions, a Field Change Request Form will be generated to document the <br />729 change and request feedback from the AECOM Task and Project Managers, USACE, and ARNG. <br />730 amplirm t, asks <br />731 The field program will include tasks as detailed in the following Worksheet elements: <br />732 • Worksheet #17a - Mobilization <br />733 • Worksheet #17b - Direct Push Boring Installation and Soil Sampling <br />734 • Worksheet #17c - Temporary Groundwater Monitoring Well Installation and Grab <br />735 Groundwater Samples <br />736 • Worksheet #17d -Synoptic Water Level Measurements <br />AECOM QAPP Worksheet #17 <br />Page 1 of 10 <br />