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Soil Vapor Assessment Work Plan Page 7 CPSA,Lodi,California January 11,2023 • During purging and sampling, a shroud will be placed over the sampling equipment. Helium will be introduced into the atmosphere within the shroud to facilitate leak detection; and, • An individually clean-certified 1-liter SUMMA® canister equipped with a regulator to control the flow into the container to a rate of less than 200 milliliters per minute(ml/min) will be used to collect the samples. Once the samples are collected, the SUMMA®canisters will be stored at ambient air temperature before delivery under chain-of-custody protocols to a California-certified laboratory for testing for PCE and five breakdown products using EPA method TO-15SIM analysis for chlorinated VOCs. Additionally, the leak detection compound (helium) will be analyzed using Modified ASTM Method D-1946. INDOOR AND AMBIENT AIR SAMPLING Figure 3 shows the results of the 2022 indoor and ambient air sampling events in the LCPA that were conducted by CHT as part of the post-decommissioning activities. As depicted in Figure 3, the indoor air samples collected from the 212 W. Pine St. had PCE concentrations above its PCE commercial indoor air ESL value of 2.0 µg/m3. As part of this SVA, the City proposes to collect six(6)indoor air samples in the same rooms/locations of the proposed sub-slab samples, and one ambient air sample outside the building on the alleyway side. The proposed indoor air sample locations are shown in Figure 4. Prior to sampling, a survey of each of the indoor air locations will be conducted to verify the proposed sample locations, as well as to compile a list of chemicals used in the buildings that may represent potential cross contamination for the indoor air samples. Where possible, the following conditions will be imposed during the indoor air sampling: • Activities within the subject building should remain normal during sampling; • No smoking will be permitted in the subject building 4 hours prior to and during sampling. • To the extent possible, windows and doors should remain closed during sampling. • To the extent possible, use of products that include VOCs will not be permitted 24 hours prior to and during sampling. CHT proposes to use Beacon Environmental (Beacon) sorbent filled stainless steel tubes to passively collect VOCs and SVOCs in ambient and indoor air over a 120-hour period using established ASTM methods. Passive sorbent samplers (PSS) do not require pumps or electricity and can be used to collect samples over a brief period of time (hours) to weeks (7 to 30+ days), thereby providing a time-integrated concentration in units of µg/m3. Additionally, low reporting limits can be achieved for a broad range of VOCs because the samplers can be exposed for extended time periods. Following completion of the sampling,the samples will be collected under chain-of-custody documentation and analyzed by Beacon using EPA Method TO-17. The methodology for `Collection of Samples using Sorbent Tubes'is provided in Attachment B. 649 DISTEL DRIVE,LOS ALTOS,CA 94022 TEL:415-424-3009