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5 <br /> October 21, 2015 <br /> Reference: Response to California Regional Water Quality Control Board, Central Valley <br /> Regional Letter dated June 15, 2015 and Request for Additional Methane and Soil <br /> Gas VOC Investigation <br /> Subcontractors will also develop a Site-specific HASP and JLAs for tasks applicable to their scope <br /> of work (e.g., driving, advancing soil vapor points, etc.). Appropriate subcontractor HASPS will also <br /> be available on Site. <br /> Laboratory Analyses <br /> Shallow soil gas probe samples will be analyzed by the on-Site mobile laboratory for the following <br /> analyses: <br /> • Fixed gases (carbon dioxide, oxygen, methane, and helium) by ASTM Method D-1946 <br /> • TPH-GRO, BTEX compounds, and Naphthalene by US EPA Method TO-15 full scan; <br /> • Carbon ranges (C5-C8 aliphatics, C9-C18 aliphatic and C9-C16 aromatics) by EPA Method <br /> TO-15 or TO-3 cannot be analyzed by the mobile lab but may be evaluated during future <br /> sampling. <br /> Data Verification <br /> Upon receipt of final laboratory reports, Stantec will perform data verification,which will include: <br /> • Verifying that batch quality control (QC) samples were analyzed at the proper frequency <br /> and that results were within specifications; <br /> • Verifying that holding times were met and that reporting units and quantitation limits are <br /> correct; <br /> • Evaluating whether corrective action (reanalysis of QC or project samples) is needed and, <br /> if so, is performed and documented; <br /> • Verifying that the project and QC sample results were properly reported and flagged; and <br /> • Preparing batch narratives that adequately identify and discuss any problems <br /> encountered. <br /> REPORT PREPARATION <br /> Data gathered during the investigation activities proposed herein will be documented in an <br /> investigation report. The report will include a discussion of field activities, tabulated soil vapor <br /> analytical results, a Site location map, an updated Site plan showing the final locations of the <br /> shallow soil gas sampling points, certified laboratory analysis reports and chain-of-custody <br /> documentation, discussions of the findings based on the new data, and conclusions and <br /> recommendations, as appropriate. <br /> 9 <br />