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28 December 2020 AdvancedGeo Project No. 17-4073 An Employee-Owned Company Page 4 of 5 � • Total petroleum hydrocarbons as heating oil (TPH-ho). • Benzene, toluene, ethylbenzene, and total xylenes (BTEX compounds). • Methyl tert butyl ether (MTBE) and naphthalene. • Additionally, the sample collected near the location of the former 350-gallon UST of unknown contents will be sampled for semi-volatile organic compounds (SVOC's) and polycyclic aromatic hydrocarboons (PAHs). Laboratory reports of soil analysis, testing methods, laboratory quality assurance/quality control (QA/QC) reports, and sample chain of custody documentation will be presented in a report of findings and recommendations. Soil boring locations are depicted in Figure 2. 3.1.2. Boring Abandonment All soil borings will be permanently sealed to prevent vertical migration of potential contaminants. Soil borings shall be abandoned by backfilling with cement grout from the total depth to surface grade. Borings will be abandoned with grout utilizing tremie procedures. The top three to six inches of the boring abandonments will be completed flush to surface grade with concrete, asphalt, or native soil. The SJCEHD will be notified for grout inspection at least 48 hours prior to conducting grouting procedures. 3.2. WELL DESTRUCTION ACTIVITIES The following procedures will be performed prior to any well destruction activities: • Notify the RWQCB and SJCEHD a minimum of 72 hours prior to commencement of any work, following the date of issue for drilling and/or well permits. • All drilling locations will be marked at least 48 hours in advance for an Underground Service Alert (USA) check of underground utilities or pipes. • All wells will be checked for total depth and well integrity using a Solinst water level meter. Any obstructions found in the well will be removed. AGI is proposing to destroy monitoring wells MW-2 and MW-7 by removing all material within the original boreholes utilizing over-drill techniques. The destruction of these wells will be performed utilizing a track-mounted CME 75 high torque mobile drill rig. MW-2 and MW-7 will be drilled out to one foot deeper than their respective total depths utilizing hollow stem augers of a diameter at least '/4 inch larger than the original borehole. All original well construction materials will be removed (including well casing, screen, filter pack and annular seal) by the drill rig to ensure that no residual contamination is sealed within the abandoned borehole nor a filter pack remaining to act as a vertical conduit.