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Geosyntec° Geosynte& consultants consultants intrusion.BPC uses a blower door to manipulate the pressure inside the building suite.Air 5. REPORTING AND SCHEDULE samples will be collected using Summa canisters while the building is depressurized.The suggested operating procedures for BPC are included in Appendix B. Pending CVRWQCB approval of the above scope of work,field implementation of soil vapor probe installation can commence within four weeks.Soil vapor probe installation is anticipated 4.6 Sub-Slab Sampling to be completed within one week.Groundwater monitoring wells and soil vapor probes should Permanent sub-slab probes will be installed in each of the suites.Sub-slab probes will be be sampled together after the soil vapor probes are allowed to equilibrate in accordance with the installed by drilling a small diameter hole through the concrete slab and placing%4-inch Teflon® agency guidance(DTSC et al,2015).Temporal data will be collected to obtain a more tubing fitted with a stainless-steel filter or Vapor Pin®through the hole.The sub-slab probes will comprehensive understanding of the seasonal effects on vapor off-gassing and migration.At be constructed in accordance with the soil vapor sampling SOP provided in Appendix B. least two sampling events(winter and summer)are proposed.Sampling may be conducted in Sub-slab probes will be installed and sampled following the completion of indoor air sampling in conjunction with the on-going groundwater monitoring that occurs at the Site. accordance with the Supplemental Guidance allowed to equilibrate at least two hours prior to sampling. Indoor air and sub-slab soil vapor data should be collected in a similar timeframe as the groundwater and soil vapor data.Indoor air and sub-slab sampling events in occupied suites need Sub-slab samples will be collected from the probes using one-liter(1L)Summa canisters.Prior to be coordinated with the occupying business'operations.The number of indoor air and to purging and sampling activities,a shut-in test and leak check will be completed in accordance sub-slab sampling events will be determined following the initial sampling event. with the SOP(Appendix B).Approximately three volumes will be purged from the sub-slab probe.One purge volume includes the internal volume of the tubing and Vapor Pin®.Purging Results from the initial investigation will be summarized in a memorandum within four weeks of and sampling will commence following a successful shut-in and leak test(i.e.no evidence of validation of all analytical data.The memorandum will summarize the findings from the leaks are found during the tests).Sub-slab samples will be collocated with indoor air samples. investigation and propose next steps as warranted. 4.7 Data Analysis and Decision Methodology Following the completion of the initial groundwater,soil vapor,indoor air,and sub-slab soil vapor sampling,the data will be evaluated and incorporated into the VI CSM.Additional investigation may be warranted if the problem statements identified in Section 3 are not addressed.The following scenarios have been identified as potential outcomes of this study: • If soil vapor analytical results do not show detected concentrations of VOCs in the vadose zone,then an assumption can be made about the geologic nature of the aquifer preventing off-gassing of VOCs from groundwater into the vadose zone. • If soil vapor analytical results show detected concentrations of VOCs in the vadose zone, additional investigation may be needed to determine the source of the VOCs detected (i.e.off-gassing from groundwater or residual vadose zone source material). • If the results from the sub-slab and indoor air sampling indicate no vapor intrusion risk (i.e.no elevated concentrations of VOCs in sub-slab or indoor air),a second sampling event may occur at least two months after the initial sampling in a new season(as defined by the Supplemental Guidance)to provide another line of evidence that no vapor intrusion potential is present. • If the results from the subsurface indicate a vapor intrusion potential(i.e.elevated concentrations of VOCs in shallow soil vapor samples)for one or both of the suites but no vapor intrusion is detected,BPC may be implemented to create worst-case scenario conditions and additional indoor air samples may be collected. 202003 Lincoln Center VI Pilot Study WPAnes 14 April 2020 202003 Lincoln Center VI Pilot Study WP.doo.¢ 15 April 2020 4.