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Mr. Buehler February 9, 2024 Page 4 of 7 Since these wells will be installed adjacent to previously installed and logged monitoring wells (MW-1, MW-6, and MW-7), soil will be collected from 100 to 120 feet bgs using a split-spoon sampler, or equivalent, and logged by a field scientist in general accordance with the Unified Soil Classification System (USCS) and field-screened for volatile organic compounds (VOCs) using a hand-held photo-ionization detector (PID). Soil samples will be collected at areas with observed staining and at locations containing PID readings greater than 10 parts per million.Soil samples will be collected in laboratory supplied containers, labeled, sealed in a plastic bag, and immediately placed in a chilled cooler for delivery to a California-certified laboratory. Samples will be analyzed for total petroleum hydrocarbons (TPH) by United States Environmental Protection Agency (USEPA) Method 8015 and VOCs by USEPA Method 8260B. The wells will be constructed using 2-inch diameter schedule 40 polyvinyl chloride (PVC) casing with 0.020-inch machine slotted screen from approximately 100 feet to 120 feet bgs. Well screen depths may be adjusted in the field based on depth to water observations. A filter pack consisting of #2/12 Monterey sand will extend from the bottom of the screen to two feet above the top of the screen. The screened interval will be surged and bailed to set the filter pack. Above the filter pack, a 2-foot hydrated bentonite seal will be placed. The annulus will then be backfilled to the surface using bentonite-cement grout. The well will be finished with a 12-inch diameter traffic- rated well box installed flush to grade and secured with concrete. A minimum of 48 hours following installation, well development will be conducted using surging and bailing techniques. Approximately ten casing volumes are planned to be purged during development of each well. During development, water quality parameters including conductivity, pH, and temperature will be monitored to calculate stabilization within 10%of each parameter and ensure that groundwater entering the wells is representative of the water-bearing zone. Following development, the wells will be allowed to recover for a period of at least 24 hours prior to sampling. A California-licensed land surveyor will survey and assign the monitoring well location unique, grid- based coordinates using the North American Datum, 1983 (NAD83) geographic coordinate datum, within a minimum horizontal accuracy of +/- 0.05 feet. Well casing and groundwater elevations will use the North American Vertical Datum of 1988 (NAVD88) and will be recorded to a minimum accuracy of+/-0.01-foot elevation. A water level meter accurate to +/- 0.01 feet will be used to measure depth to water and total well depth prior to sample collection. Groundwater samples will be collected during the next groundwater monitoring event from the seven existing monitoring wells (MW-1 through MW-7) if sufficient water is present,the observation well (OBS-1), and the newly installed wells (MW-1 D, MW- 6D, and MW-7D) utilizing low-flow purging techniques. Each sample will be decanted into a laboratory supplied container, labeled, and placed in an ice-filled cooler. Quality control samples, including a trip blank and a duplicate, will be collected to verify that handling, storage, equipment decontamination, and transportation procedures are adequate and appropriate. Water samples will be submitted under standard COC protocol to a State-certified laboratory. The samples will be analyzed using USEPA Method for Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX), tert-amyl methyl ether (TAME), tert-butyl alcohol (TBA), diisopropyl ether (DIPE), ethyl-tert-butyl ether (ETBE), methyl-tert-butyl ether (MTBE), 1,2-dibromoethane (EDB), and 1,2-