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Off-Site Groundwater Well Installation Work Plan McBillin Real Estate Investment Property 2154 South El Dorado Street Stockton, San Joaquin County,California Page 5 listed as extending from 125 feet bgs to 108 feet bgs (two (2) feet above the screened interval) utilizing a#2 Monterey sand. A two (2) foot bentonite seal followed by grout to within one (1) foot of the surface (where the well box and surface completion are installed) complete the well. Apex proposes to retain the services of a California C-57 licensed contractor to complete the installation of two (2) groundwater monitoring wells. The installation will be consistent with the description for MW-12 that is outlined above and depicted in the attached Appendix C. To install each groundwater monitoring well, Apex will begin each location as a soil boring. The first five (5) feet at each soil boring location will be completed by hand-auger as a precaution to avoid striking any underground utilities. Upon completion of hand-augering at each soil boring location, hollow- stem auger drilling methodologies will be utilized to advance each borehole to a total depth of 125 feet bgs as outlined above. Split spoon sampler will be utilized to collect soil samples at five (5)foot intervals to allow for lithologic description and later preparation in boring logs to be submitted in a report of findings. Soil samples from each location will be screened utilizing a photoionization detector (PID) at 5-foot intervals. Upon completion of the hand auger and hollow-stem soil boring activities, the proposed monitoring wells will be installed by the licensed driller utilizing a 4-inch hollow-stem auger. The new well locations are depicted within the attached Figure 4. All soil generated during the well installation activities shall be stored onsite in Department of Transportation-approved 55-gallon steel drums, pending proper off-site disposal under manifest. Each monitoring well will be secured in a traffic-rated vault box. Soil Sampling Since the location of the proposed monitoring wells are located more than 800 feet away from primary and secondary source locations, Apex is not proposing to collect soil samples for discrete analysis during the monitoring well installation well process. Groundwater Monitoring Well Development Not less than 72 hours after installation, Apex staff will complete development of the newly installed groundwater monitoring wells proposed within this Workplan. Prior to well development activities each well will be opened to allow for equilibration. Measurements of the depth to water and total depth of each well will be taken and recorded. Surging of each monitoring well for 15 minutes will be completed to flush sediment from the well screen and the filter pack. Following well surging,two (2) well volumes will be removed from the well through disposable bailer. The wells will be allowed to recover (keeping track of the time it takes to recover) at which point a two (2)-inch submersible pump will be placed approximately six (6) inches off the bottom of each well. Once in place, pumping will begin at a rate that was monitored to be the equivalent to the recharge rate at each monitoring well. Water quality parameters temperature, pH, specific conductance, dissolved oxygen, and turbidity will be measured during the purging of each monitoring well using a Horriba U-50 (or similar)multiparameter instrument and recorded for documentation in the report of findings referenced below. To prevent cross contamination in the wells and groundwater samples, all equipment will be