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Stockton Propeller Sampling and Analysis Plan Based on the information summarized in Table 4,three (3) 2-inch diameter monitoring wells are proposed as shown in Figure 5 to assess first encountered groundwater. Borings will be advanced, and wells constructed by a drilling contractor with a current California C-57 license. A California professional geologist or someone under their direct supervision will supervise well construction and log subsurface material according to the USCS at 5 foot intervals to the full depth of groundwater for each monitoring well. Well depth is anticipated to be up to 80 feet. Screen length and placement will be determined in the field based on field conditions. Based on the review of local geology as summarized in Table 4,there does not appear to be consistent evidence of subsurface conditions such as an aquiclude or aquitard that would support horizontal transmission of liquid from the leach field/septic tank to the proposed locations of the upgradient monitoring well MW-1 or cross gradient monitoring well MW-3. Accordingly, collection of samples at 5- foot intervals from MW-1 and MW-3 will begin 15 ft below the lowest elevation of the septic tank and continue to the full depth of each monitoring well. Sampling may be adjusted based on soil type and field observations. For the proposed monitoring well MW-2 located in the vicinity of the septic tank and leach field, soil samples will be collected for chemical analysis at 5 foot intervals starting at depth of the leach field line(s) or bottom of the septic tank,whichever is shallower, and continue to the full depth of the monitoring well. Sampling may be adjusted based on soil type and field observations. Samples will be collected for chemical analysis using a California modified split spoon sampler equipped with three 6-inch sample sleeves.The ends of the bottom-most intact sleeve from each sample interval will be lined with Teflon sheets and capped. Wells will be constructed with 2-inch diameter Schedule 40 PVC blank and 0.02-inch slotted screened casing. A filter pack of#3 sand will be placed in the annular space around the well casing from total depth to two (2)feet above the top of the well screen. Approximately three (3)feet of bentonite chips will be placed on top of the filter pack and hydrated with clean water to provide a transition seal for the well. Neat cement will be used to backfill the remaining annular space around the well casing. A watertight locking cap will be placed over the top of the well casing, and a traffic rated vault box will be installed around the top of each well. Prior to well construction, an additional USA survey may be completed if necessary, and appropriate permits will be obtained from SJCEHD. Encroachment permits, if needed,will also be obtained. As with soil borings, hand augering and/or an air knife may be used prior to placement of borings for well construction to reduce potential damage to subsurface features. Appropriate permits will be obtained from SJCEHD and encroachment permits, if needed,will also be obtained. Downhole equipment will be decontaminated between sample locations by either pressure washing or steam cleaning. As necessary, hand washing will be done with a non-phosphate cleaning solution. Cleaned equipment will be triple rinsed with clean water prior to reuse. Site personnel will be made aware of the potential presence of human waste in soil and groundwater and will wear appropriate PPE. IDW will be placed in DOT-approved 55-gallon drums and placed on-site pending soil characterization and will then be disposed of properly. In addition to the sample collection criteria described above, a photoionization detector(PID) or similar device will be used in the field and will combined with visual observations to aid in selecting samples for laboratory analysis. Samples from each boring will be placed in appropriate containers and transported to an ELAP-certified analytical laboratory under COC procedures in iced coolers and analyzed for the analytes described in Section 3.4.The first 3 soil samples collected from each boring will be analyzed and if analytes are detected, deeper samples will be analyzed. Conversely, if analysis of 3 contiguous samples reports non-detect,then deeper samples may not be analyzed. Blankinship&Associates, Inc. Page 18 of 20 September 23, 2022 NES, Inc.