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SAP/QAPP Addendum Lodi-125 N Stockton Final March 24,2025 SITE-SPECIFIC QAPP WORKSHEET #10 (CONTINUED) PROBLEM DEFINITION • Geophysical Surveys:The purpose of the survey will be to assess the presence of an underground storage tank(UST) or backfill materials consistent with a former UST excavation within an area approximately 10 feet by 10 feet.The geophysical survey will be performed using a Geonics EM61 MK2 time-domain metal detector and a GSSI SIR4000 ground-penetrating radar(GPR)with a 350- megaHertz transducer antenna.The purpose of the EM61 survey will be to detect and map possible USTs,vaults,sumps,metallic underground lines,and buried metal within the survey area.The purpose of the GPR survey will be to detect and map possible former backfilled excavations and buried pipelines and utility lines.The EM61 data will be conducted along transects nominally spaced 2 feet apart across the survey area. GPR transects will also be conducted along transects nominally spaced 2 feet apart and over detected EM61 anomalies of interest.The recorded EM61 data will be downloaded to a portable computer in the field for preliminary analysis and quality control review in the field. EM61 data will be processed and gridded using Geosoft Oasis montaj software. Seequent Oasis montaj software will be used for overlaying and comparing EM61 and GPR data,mapping interpretations of anomalous features,and creation of final maps.In addition,detectable underground utilities and pertinent surface features will be mapped using a differential global positioning system (DGPS). • Hazardous building materials survey: - Asbestos—suspected asbestos containing material (ACM) samples collected from the house and outbuilding will be analyzed via polarized light microscopy(PLM) per EPA Method 600/R-93/116. Samples yielding PLM results indicating less than 3 percent asbestos will undergo further asbestos analysis via EPA's 1,000-point-count method.A California-certified asbestos consultant or certified site surveillance technician will collect samples of suspected ACM. - Lead—buildings will be assessed using XRF screening per U.S.Department of Housing and Urban Development(HUD) and EPA guidelines,and from analyses of paint chip samples via EPA Method 700013.A Lead-Related Construction Inspector/Risk Assessor certified by California Department of Public Health will collect paint chip samples of suspected LBP. - PCBs—samples of caulk will be analyzed for polychlorinated biphenyls (PCBs) following EPA online guidance and EPA Title 40 Code of Federal Regulations(CFR) 761.62(b)(4)(ii). EPA specifies prudent public health SLs of PCB exposures below which EPA believes will not cause harm. EPA has set an SL of 50 mg/kg for PCBs in materials,and therefore this will be the benchmark used for 16