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Brusca File No. 137-002 Page 5 August 10, 2017 Murphy Parkway Property Soil Gas Monitoring Workplan Soil Gas Monitoring Well Installation The two planned soil gas monitoring wells will be constructed within approximate eight-inch diameter borings drilled with a truck-mounted drill rig using hollow-stem augers. The drilling and well installation will be performed by a C57-licensed contractor. During drilling, soil samples will be collected from the borings for lithologic characterization and the borings will be logged by a Professional Geologist. The borings for the planned soil gas monitoring wells will extend to a depth of ten feet below surrounding grades; this level is anticipated to be above typical groundwater levels at the site. Two-inch diameter Schedule 40 PVC casing will be used for the wells. The lower seven feet of the casings will be screened; the screened portions of the well will be factory slotted (0.020 inch slots). The upper portions of the casings will be solid, and will extend to a level approximately three feet above the ground surface. The annular space surrounding the screened portion of the wells and extending one foot above will be backfilled with washed graded silica sand. A one- foot-thick bentonite plug will be placed and hydrated within the annular space directly above the sand filter, and the remaining annular space above will be backfilled with neat cement grout to the ground surface. A soil gas sampling port will be installed at the upper end of each well and the portions of the casings above the ground surface will be protected with locking steel risers/monuments. Each riser/monument will be labeled with well identification. A detail drawing shown the planned configuration of the soil gas monitoring wells is presented as Plate 3. SOIL GAS MONITORING/TESTING PROGRAM Frequency of Monitoring Soil gas samples will be collected from the two planned soil gas monitoring wells following a one-week equilibration period after well installation. Thereafter, monitoring will be performed on a quarterly basis for a period of one year, and annually for four years thereafter. Following the five years of soil gas monitoring, consideration will be given to discontinuing the monitoring program (based on the results and discussions with the SJCEHD). It is anticipated that at least two sampling events will be conducted prior to construction of the proposed building on the property. The results of those sampling events will be evaluated to determine whether implementation of protective measures (such as a sub-slab vapor membrane or venting system) is warranted in conjunction with building construction at the site. Soil Gas Sampling For each sampling event, the soil gas monitoring wells will be inspected to insure they are sound and without damage. Prior to sample collection, each well will be screened with portable gas indicator (such as a GEM-2000 or equivalent) connected to the sampling ports on the wells. Screening measurements (including methane percentage, carbon dioxide percentage, oxygen percentage, and balance gas percentage) will be recorded. Subsequently, appropriate, laboratory- provided sampling containers (Summa canisters) will be attached to the sampling ports on the wells for the collection of soil gas samples.