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accordance with United States Environmental Protection Agency(EPA) Method 5035 sampling protocol. A sample will also be collected by transferring soil into a laboratory-supplied,four-ounce, wide-mouth, unpreserved glass jars, which are sealed with a threaded, Teflon-lined lid.The jars will be filled with soil to capacity to minimize headspace and reduce the potential for volatilization. The jars and VOA vials will be labeled for identification and stored in an iced cooler; • After soil sampling to the terminal depth and/or groundwater, groundwater samples will be collected by withdrawing the drill rods from the subsurface and installing 3/4-inch diameter temporary monitoring wells within the open boreholes. Each monitoring well will consist of a 5- or 10-foot long, 0.010-inch factory-slotted polyvinyl chloride (PVC) screen (depending on depth to groundwater) at the terminal end and blank PVC risers from the top of the screen interval to the ground surface. Groundwater samples will be retrieved from each monitoring well using a new section of 3/8-inch diameter polyethylene tubing with a check valve at the terminal end or through a peristaltic pump and conveyed into hydrochloric acid-preserved VOA vials. Each vial will be filled with no observable headspace or air bubbles to minimize the potential for volatilization, labeled for identification, and stored in an iced cooler. New screens and tubing will be used for each monitoring well.The risers will be decontaminated between boreholes to prevent cross-contamination; • Up to 30 soil samples and two groundwater will be prepared for laboratory analysis. Based on field- screening results, analyze one soil sample per boring and each groundwater sample (four soil and two groundwater samples total) for CVOCs via EPA Method 8260; • A temporary soil gas probe will be installed in a step-out borehole at 5 and 15 feet bgs after soil and groundwater sampling for each boring. To construct the temporary soil gas probes, the borings will be backfilled with dry, granular bentonite to approximately 6 inches below the desired sampling depth. A new section of diameter Nylaflow tubing with a new '/4-inch diameter polypropylene filter at the terminal end will be inserted into the boring at the desired sampling depth. One-inch diameter polyvinyl chloride(PVC)casing will be used as a guide for the tubing to ensure that the desired sampling depth is achieved. Sand will be poured into the boring annulus to form an approximately 1-foot long sand pack around the polypropylene filter, at which time the PVC piping will be withdrawn. Approximately 1-foot of dry, granular bentonite will be placed atop the sand pack and the remainder of the borehole will be backfilled with hydrated bentonite to the ground surface to form a seal. The sampling end of the tubing will be fitted with a valve for sampling. The final screening depth at each borehole will be adjusted based on the encountered lithology. In general, probes will be screened within coarser-grained materials and clayey/saturated intervals will be avoided, if possible; • Two temporary sub-slab soil gas probes will be installed in the adjacent suites (Suites 306 and 308B) collocated with the indoor air samples, immediately beneath the building foundation slab; • Soil gas samples will be collected in general accordance with the July 2015 DTSC and Los Angeles RWQCB "Advisory — Active Soil Gas Investigations." Each probe will be allowed to equilibrate for a minimum of two hours after installation prior to sampling. After equilibration, the sample tubing and sampler screen were purged of ambient air and Partner will collect and prepare up to 10 soil gas samples for laboratory analysis using laboratory-provided, batch-certified SUMMA canisters and flow controllers with a 5- to 10-minute sample period. Each soil gas sample (up to 10 soil gas samples total) will be analyzed for CVOCs via EPA Method TO-1 5; • After sampling activities, borings will be backfilled per SJCEHD requirements (e.g., tremie grouting with Portland neat cement grout) and capped with concrete; • Compare data to applicable screening criteria, and prepare two reports (one report per parcel) summarizing field activities, methods, and findings; and • Submit the pertinent data to the SJCEHD for review. Page 4 PARTNER