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REV: 12-02-2021 VR <br />Report includes findings, opinions and conclusions, photographs, site map, historical <br />sources, and qualifications in a manner consistent with standard practices. <br />Focused Phase II Subsurface Investigation: <br />AEI will advance six (6) soil borings at the Site to collect soil, groundwater, and soil gas <br />samples. The borings will be advanced to 12 feet below ground surface (bgs) for the <br />collection of soil samples; groundwater samples will be collected at four of these <br />locations. The attached figure depicts the soil boring locations. Four (4) of the soil borings <br />will be converted to soil gas probes for the collection of soil gas samples. AEI proposes <br />the following tasks to perform the investigation: <br />Obtain a drilling permit for the proposed exploratory borings from the County of San <br />Mateo Groundwater Protection Program. <br />Prepare a Site-specific health and safety plan (HASP) for the project. <br />Notify City and property contact person of the nature and schedule of the work. <br />Mark and notify the local underground service alert to identify public utilities in the <br />planned work area(s). <br />Arrange for a private utility locating service to check planned drilling locations for <br />possible utilities. <br />AEI will contract a licensed driller to advance six (6) soil borings at the Site with a <br />truck-or track mounted direct-push drilling rig, depending on access limitations. The <br />locations of the proposed borings are shown on the attached figure. <br />Each soil boring will be logged by AEI staff; soil core will be logged and described in <br />general accordance with the Unified Soil Classification System (USCS); soils will be <br />screened with a portable organic vapor meter (OVM) or photoionization detector (PID) <br />and for sensory perception. Soil samples will be collected at select intervals for <br />potential laboratory analysis. It is expected that 1 to 2 soil samples will be selected <br />from each boring for analysis. <br />After drilling the borings, a temporary well will be constructed in up to four (4) of the <br />borings using well materials consisting of 1-inch diameter, 0.010 slotted, polyvinyl <br />chloride (PVC) piping installed in the borehole to facilitate collection of a groundwater <br />sample. The borehole will be left open up to 4-hours to facilitate groundwater <br />collection. <br />The soil borings for the collection soil gas samples will be completed as temporary <br />gas probes with the probe tip located at approximately 5-feet bgs. Sampling of soil <br />gas will be conducted following a minimum of 2-hour equilibration time by vacuum <br />testing and purging the wells and by using helium as a tracer compound. The soil gas <br />samples will be collected through a calibrated flow controller and into one-liter <br />laboratory-supplied evacuated canisters. <br />Samples collected for potential laboratory analysis will be sealed, labeled, and entered <br />onto chain-of-custody documentation for transportation for analysis to a state-certified <br />laboratory. <br />The following types and number of soil analyses are included: <br />o Total petroleum hydrocarbons (TPH) multi-range using U.S. Environmental Protection <br />Agency (EPA) Testing Method 8015M.........................................9 samples <br />o Volatile organic compounds (VOCs) using EPA Testing Method 8260B......9 samples <br />o “CAM 17” metals using EPA Testing Method 6020/7471 .............................9 samples <br />ATTY/AGR.2021.314/AEI Consultants (Page 12 of 15)