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Site Inspection UFP-QAPP Addendum Stockton AASF, Stockton, California 866 temperature blank will be placed in each cooler to ensure that samples are preserved at or below 867 4 degrees Celsius (°C) during shipment. 868 Each sample will be collected into laboratory -supplied bottleware and submitted to the laboratory 869 for analysis of selected parameters. Samples will be analyzed for PFAS by liquid chromatography 870 tandem mass spectrometry (LC/MS/MS) compliant with Quality Systems Manual (QSM) 5.3 Table 871 B-15. Additionally, one soil sample per AOI from a location in the source area will be analyzed for 872 total organic carbon (TOC) (USEPA Method 9060A) and pH (USEPA Method 9045D). Additionally, 873 up to one soil sample per AOI will be submitted for grain size analysis with sieve and hydrometer 874 (American Society for Testing and Materials [ASTM] D-422) (i.e., clay content). The grain size 875 analysis will be performed where extensive horizontal and vertical clay units are identified by the 876 field geologist, if these conditions are encountered in the field. All sample containers will be PFAS 877 free. The laboratory method detection limits (DLs) for these analytes are presented in Worksheet 878 #15. Samples will be packaged on ice and transported daily via overnight commercial carrier 879 under standard chain of custody (CoC) procedures to the laboratory (see SOP 3-04). 880 QAPP Worksheet #17c 881 Sampling Design and Rationale 882 Temporary Groundwater Monitoring Well Installation and Grab Groundwater Samples 883 Boreholes for temporary wells will be created using a Geoprobe® DT45 or DT60 dual -tube 884 sampling system (or equivalent). Once the borehole has been advanced to the specified depth, 885 the temporary well will be constructed using a 5 -foot section of 1 -inch Schedule 40 poly -vinyl 886 chloride (PVC) screen with sufficient casing to reach ground surface. New PVC pipe will be used 887 for each sampling location. The target screen interval for each location will be the top of the 888 groundwater table, which is expected to be encountered no deeper than 35 feet bgs at Stockton 889 AASF. The proposed well locations are shown on Figures 17-1. The target screen intervals and 890 rationale for the sampling locations are described in Table 17-3. 891 Table 17-3: Groundwater Sample Rationale and Proposed Screen Intervals A01= area of interest bgs = below ground surface 895 A grab groundwater sample will be collected at each temporary well using a peristaltic pump with 896 tubing that has been determined to be PFAS-free (i.e. high-density polyethylene [HDPE] or other 897 PFAS-free material). If the peristaltic pump cannot generate enough hydraulic lift to bring the 898 groundwater to the surface, groundwater samples will be collected using a PFAS-free bladder 899 pump or other sampling device. Prior to sampling, the temporary well will be purged in order to 900 remove sediment, to the extent reasonable, in an effort to minimize the turbidity of the sample 901 (see SOP 3-37: Grab Groundwater Sampling Techniques for additional details). The degree of 902 purging will be dependent on groundwater recharge within the well. If sufficient groundwater 903 recharge is observed, the well will be purged until the turbidity is <_ 25 nephelometric turbidity units AECOM QAPP Worksheet #17 Page 6 of 10 Number of Target Screen Interval .. Rationale AOI 1 5 Top of groundwater table, Five temporary wells proposed adjacent to potential or (est. 30-35) suspected release areas. AOI 2 2 Top of groundwater table, Two temporary wells proposed (one downgradient of, (est. 30-35) and one within, the suspected release area) Top of groundwater table, Three temporary wells proposed (two downgradient of AOI 3 3 (est. 30-35) the suspected release area and one within soil backfill area) Notes: A01= area of interest bgs = below ground surface 895 A grab groundwater sample will be collected at each temporary well using a peristaltic pump with 896 tubing that has been determined to be PFAS-free (i.e. high-density polyethylene [HDPE] or other 897 PFAS-free material). If the peristaltic pump cannot generate enough hydraulic lift to bring the 898 groundwater to the surface, groundwater samples will be collected using a PFAS-free bladder 899 pump or other sampling device. Prior to sampling, the temporary well will be purged in order to 900 remove sediment, to the extent reasonable, in an effort to minimize the turbidity of the sample 901 (see SOP 3-37: Grab Groundwater Sampling Techniques for additional details). The degree of 902 purging will be dependent on groundwater recharge within the well. If sufficient groundwater 903 recharge is observed, the well will be purged until the turbidity is <_ 25 nephelometric turbidity units AECOM QAPP Worksheet #17 Page 6 of 10