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Groundwater Monitoring Well Construction Workplan February 2024 provided when the geophysical log may be run and a final well design. The borehole cannot sit idle for long periods of time and construction must continue to prevent borehole collapse. The well casing and screens for each monitoring well will be installed into the borehole separately (deepest monitoring well first) and surrounded with, suitable sand filter packs, with bentonite chip annular seals placed between the filter packs, opposite confining beds. Each monitoring well casing will be equipped with centralizers (three per interval equally spaced around the well casing). Three sets of centralizers will be placed below the screen, immediately above the screen and at 100-foot intervals with at least one centralized placed mid-way within confining beds. The centralizers will have a minimum spacing between the well casing and the expanded centralizers of 2-inches. The bentonite chips will be placed using a tremie pipe after the drilling muds have been thinned down(having a viscosity of 32 seconds or less). The bentonite chips used shall be NSF approved. The bentonite chips will be allowed to hydrate for 1 hour after placement,prior to proceeding with construction. After placement of the deepest monitoring well and filling of the annular space with either bentonite chip or filter pack, the next shallowest monitoring well casing and screen will be placed using the procedures described above until all monitoring well casing and screens are installed and surrounded with annular materials. Volumes of the annular space will be calculated for each bentonite chip and sand interval; however, during placement of long lengths of the bentonite chips, the chips can swell to 5 to 8 times their volume, decreasing the amount of bentonite chips required to be placed. Once the upper bentonite annular seal has hydrated, a neat cement sanitary seal will be placed in the annular space, in one continuous pour using a tremie pipe,between the top bentonite seal to ground surface. The top of the wells will be secured with lockable plugs, within an above-grade steel locking enclosures and by 2-foot-square concrete pad surrounded by four steel bollards. Each well casing will be properly permanently marked with the well identification number. The site geologist will record groundwater elevations from each well following drilling operations and surveying. Well Development DWR will oversee and document monitoring well development activities. Each monitoring well will be developed initially by the driller using a surge block and pumping to immediately begin to clear up the wells and clean up the borehole wall from the drilling process. The wells will be further developed using the air-lift development method. Accumulated sediments in the well bottom will be removed via bailing. Wells will be subsequently developed using a pump with additional surge block until turbidity in the purge water is sustained below 5 NTU during pumping. Well development efforts will be recorded including volume of water and debris removed, and general parameters including temperature, conductivity,pH, and total volume pumped throughout the development process. GEI Consultants, Inc. 22