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0 Additional Site Investigation Work Plan CL� UPRR Bunkers—Tracy,CA } oup October 30, 2023 r Upon completion,each boring will be backfilled with neat cement grout mixed at a ratio of three(3)gallons of water to one 47-pound bag of cement.The grout will be poured into the borings or pumped through a tremie pipe as required by the SJCEHD inspector.The backfilled boreholes will be capped with cement or soil to match the surrounding ground surface. 3.2.1 SOIL SAMPLE COLLECTION The borings will be sampled continuously using a macro-core sampler fitted with a plastic liner.The soil will be characterized and logged using the Unified Soil Classification System (USCS)and field screened for volatile organic compounds(VOCs) using a photo-ionization detector(PID) calibrated to 100 parts per million (ppm)of isobutylene. Discrete soil samples for potential laboratory analysis will be retained from each boring approximately every two(2)to three(3)feet of depth (John P. Christopher 1997).Sample depths may be adjusted to target different lithologic units six(6) inches thick or greater.Additional samples for analysis may be collected based on odor, color indicative of chemical staining, non-aqueous phase liquid,or a PID reading greater than 15 ppm. 3.2.2 GROUNDWATER SAMPLE COLLECTION If groundwater is encountered in the exploratory borings, a single groundwater grab sample will be collected.A pre-packed well screen will be lowered into the chosen boring to intersect the water table (California State Water Resources Control Board 2015).The pre-pack well screen is to minimize sediment in the sample.The temporary well will be sampled using a clean,disposable bailer the day after installation to allow for sufficient sample media in the well.At least three well volumes of groundwater will be purged before a sample is collected.Groundwater parameters(pH,conductivity)will be taken during well purging.After sampling the temporary well will be removed, and the boring abandoned per permit requirements. Note that the pre-pack screen will be properly disposed of, and the solid polyvinyl chloride(PVC)casing will be either disposed of or decontaminated for additional use. 3.2.3 EQUIPMENT DECONTAMINATION The drilling rods and sample collection equipment will be decontaminated prior to use and between boring locations using a pressure washer with hot water or a non-phosphate detergent wash and triple-rinse protocol. The water generated will be stored in Department of Transportation (DOT)-approved,open-top 55-gallon drums. 3.2.4 LABORATORY ANALYSIS PROGRAM Soil and groundwater samples collected for chemical analysis will be sealed in appropriate, laboratory-provided containers, labeled,and packed on ice for transport to a California-certified laboratory following chain of custody procedures.The soil samples for VOC analysis will be processed for submission to the laboratory using a TerraCore-type soil sampler in accordance with United States Environmental Protection Agency(U.S. EPA) Method 5035.The samples will be analyzed for the following: • Diesel range organics(DRO)and oil range organics(ORO) by U.S. EPA Method 8015B. • Benzene,toluene,ethylbenzene,xylenes(BTEX), methyl tertiary butyl ether(MTBE)and naphthalene by U.S. EPA Method 8260E(California State Water Resources Control Board 2015). • The 16 priority pollutant polycyclic aromatic hydrocarbons(PAHs) naphthalene,acenaphthene, acenaphthylene,anthracene, phenanthrene,fluorene,chrysene,fluoranthene, pyrene, benzo(b)fluoranthene, benzo(a) pyrene, benzo(k)fluoranthene, benzo(a)anthracene, indeno(1,2,3-c,d)pyrene,dibenz(a,h)anthracene, benzo(g,h,i)perylene by U.S. EPA Method 8270 SIM (California State Water Resources Control Board 2015). �INOGENIX ALLIANCE uS_atnteagroup.cam 3