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One grab groundwater sample will be attempted to be collected from the boring. Upon completion of drilling and soil sampling, the DPT tooling will be removed and a 10-foot length of 2-inch diameter PVC casing with an attached 5-foot PVC slotted screen will be lowered down into the boring. A grab groundwater sample will be collected using a new, clean, disposable weighted polyethylene bailer equipped single-check-valve lowered into the borehole with a disposable cord. Once full, the bailer will be removed, and the water will be transferred into laboratory-provided clean sample containers. If groundwater is not encountered, the boring will be left open for up to one-half hour to allow water to infiltrate into the borehole. If groundwater is present at the end of the half-hour waiting time, grab groundwater samples will be collected for analysis, as described above. If groundwater is not present, no further attempt will be made to collect groundwater samples at that location and the boring will be backfilled with neat cement grout. Used tubing and bailers will be contained in a DOT-approved drum for disposal at a later date. Groundwater samples for VOC and total petroleum hydrocarbons as gasoline (GRO) analysis will be collected in three forty-milliliter “VOA” vials preserved with a few drops of hydrochloric acid. Groundwater samples for PCB, total petroleum hydrocarbons as diesel (DRO), and metals analysis will be collected in two one-liter amber glass bottles for each analyte (four one-liter amber glass bottles in total) with no preservative. The laboratory will filter groundwater samples prior to acid preservation and analysis for dissolved metals. Soil and groundwater samples will be placed in laboratory-supplied glassware containing the appropriate preservative, labeled, and placed under chain of custody in a chilled cooler full of ice. Soil samples submitted for laboratory analysis will be shipped to a California State-certified laboratory for analysis. Upon completion of soil and groundwater sampling, a Portland Type II grout or grout/bentonite slurry will be placed by tremie pipe from the top of the bottom of the borehole to approximately six inches below grade. The borehole will be completed at the surface to match the surrounding surface and evidence of sampling will appear to be a concrete patch approximately 2 to 4 inches in diameter for paved areas or a dirt hole approximately 2 to 4 inches in diameter in landscaped areas. Our field team will clean up the areas surrounding the boring (sweeping up soil cuttings, concrete chips, etc.) and wipe down surfaces if dust was generated and deposited nearby. After completion of the borehole, drilling equipment will be decontaminated using a steam cleaner and captured in a 5-gallon bucket. Decontamination water and soil generated during well installation activities will be transferred from the buckets to DOT-approved 55-gallon drums to disposal at a later date pending the results of waste profile sampling. The boring location will take approximately 1 to 2 hours from start to finish. The boring location will be surveyed by AECOM with a handheld GPS unit. Sample Handling Soil samples will be stored in clean, laboratory-provided containers. Groundwater samples will be stored in clean, laboratory-provided bottles. The bottles/containers/tubes will be labeled with site-specific labels, placed on ice, and picked up by a courier and delivered to a State of California certified analytical laboratory for analysis, under AECOM chain of custody procedures. The samples will be analyzed using the appropriate EPA methods. Samples will be analyzed on a standard turn-around time. One duplicate sample will be collected for every ten samples collected. Trip blanks will be submitted daily to the laboratory for analysis of VOCs to ensure the integrity of the samples during the shipping process. Investigation Derived Waste Disposal Soil cuttings, decontamination water, and other drilling wastes (such as used personal protective equipment [PPE] like gloves, paper towels, etc.) from sampling activities will be stored in DOT-approved 55-gallon drums and left at a designated location approved by the building managers until sampled, analyzed, characterized, and profiled for off- site disposal. AECOM assumes that Caltrans will provide an EPA ID number and sign any hazardous waste manifests for off-site soil disposal of hazardous soils. ATTY/AGR.2025.012/BMR-Bay LP (700, 720, and 740 Bay Road) (Page 14 of 16)