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Geosynte& Geosyntec° consultants consultants 4.2.3 Utility Survey the vadose zone. Soil samples will be analyzed for the following soil matrix parameters using At least 48 hours prior to intrusive field activities,Underground Services Alert(USA)North 811 the methods indicated,or their equivalents: will be notified of the intent to drill.USA will contact all utility owners of record within the Site • Soil bulk density(ASTM D2937); vicinity and notify them of the intention to conduct subsurface investigations in proximity to buried utilities. All utility owners of record,or their designated agents,will be expected to • Grain density(ASTM D854); clearly mark the position of their utilities on the ground surface for utilities that are located in . Specific gravity(ASTM D854m); public areas. In addition,a private utility locator will be procured to mark private utilities and clear proposed drilling locations.Utilities will be clearly marked on the ground surface and • Organic carbon(Walkley-Black method); subsequent field activities will be planned accordingly. • Moisture content(ASTM D2216);and 4.3 Groundwater Sampling • Grain size analysis(sieving and hydrometer,ASTM D422). The two selected groundwater monitoring wells(MW-007A and PT-l 1)will be sampled in Total porosity will be calculated from soil bulk density and grain density, However,soil samples groundwater samples,the depth to water measurements will be collected.The pump will be accordance with the low flow purging and sampling SOP(Appendix Prior to collecting collected using a dual-tube sampling system may increase soil density and reduce soil porosity. lowered until it is at the top of the screen interval identified for each well to collect a sample that Following soil vapor probe installation and prior to sampling,each probe will be allowed to is representative of the top of the water table.Additional details regarding purging and sampling equilibrate a minimum of two hours.Soil vapor probe purging and sampling activities will be methodologies is provided in Appendix B. conducted in accordance with the soil vapor sampling SOP(Appendix B).Soil vapor samples 4.4 Soil Vapor Sampling will be collected with paired groundwater samples from the groundwater monitoring wells. Soil vapor sampling locations will be selected and marked at each site prior to their collection. 4.5 Indoor Air Sampling At each sample location,a soil probe is inserted into the soil,sealed at the surface using Prior to sample collection,a building survey and questionnaire form will be completed,and bentonite clay,and then purged and sampled through a Teflon®tube into a Summarm canister. when available,the owner/occupant will be interviewed regarding chemical usage and In general,soil vapor probe installation and sampling will follow Advisory—Active,Soil Gus ventilation system operation.Conditions,products,or activities that may affect or interfere with Investigations,published jointly by the DTSC,Los Angeles Regional Water Quality Control the indoor air quality evaluation of COC may be discussed with the owner/occupant. Board(LARWQCB),and San Francisco Bay Regional Water Quality Control Board Owners/occupants may be requested to remove,to the extent possible,products or materials that (SFRWQCB)(DTSC et al,2015), may confound the indoor air quality evaluation of COC prior to sample collection. A pilot hole will be advanced in each of the two study areas to first encountered groundwater, In addition,potential preferential pathways will be identified and noted.Potential preferential which is anticipated to be approximately 50 feet bgs.The soil will be logged in accordance with pathways include utility conduits and other penetrations in the building floor/slabs as determined the SOP to identify permeable zones throughout the soil column and select soil vapor probe by visual inspection in the areas where samples will be collected. depths.Permanent,multi-depth soil va or r ill be ins least five feet the pilot boring using a truck-mounted ydrau ically driven percussion hammer(Geonrobe®)Two multi- Indoor air samples will be collected over an 8-hour period for representative concentrations over depth,permanent soil vapor pro ropose or installation nye existing s lected the anticipated daily exposure period,in accordance with the Supplemental Guidance(CaIEPA, groundwater monitoring wells MW-007A and PT-11.The probes will be installed starting at 5- 2020).Three samples will be collected from each of the two suites,as well as a duplicate sample feet bgs and every 10-Feet thereafter,where permeable layers are identified during the pilot hole and three outdoor air samples.Air samples will be collected into 6-liter stainless steel, advancement and will be completed above the potentiometric surface(saturated zone)located at individually-certified Summa canisters.The canisters will be fitted with an individually-certified approximately 50 feet bgs.The total number of nested probes per wells will vary depending on flow controller that is calibrated to collect a time-integrated sample over either an 8-hour sample subsurface conditions;however,no more than five probes are anticipated per well.Soil vapor period.Air samples will be collected in accordance with the indoor and outdoor air sampling probes will be installed in accordance with the soil vapor sampling SOP,included in Appendix SOP(Appendix B). B. In addition to the laboratory samples,pressure data will be collected from the interior and During the pilot borings,several soil samples will be collected for soil physical properties to exterior of the suites during air sampling activities.Data loggers will be left to record pressure confirm permeable zones selected for vapor points. Samples will be collected directly from the data leading up to,during,and following air sampling,for up to a week in total. dual-tube soil cores at depths ranging from 5 to 50 feet bgs from each distinct layer observed in Based on the results of the initial air sampling activities,BPC may be implemented to create realistic,worst-case scenario conditions by depressurizing the suite and therefore inducing vapor 202W3 Linwln Center VI Pilot Study WP.docs 12 April 2020 202003 Lincoln Center VI Pilot Study WP.dncs 13 April 2020