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Groundwater Monitoring Well Construction Workplan <br /> February 2024 <br /> outside of the known extent of the Corcoran Clay as defined by the USGS. Projections of the <br /> clay based on USGS data suggests that it may be present at about 140 to 250 feet bgs. <br /> Non-Water or Non-Freshwater Bearing Formations <br /> All of the freshwater bearing formations and sediments mentioned above are underlain by <br /> various marine formations and/or igneous and metamorphic rocks, potentially similar to those <br /> exposed in the Coast Ranges. The uppermost beds of the San Joaquin Formation underlie the <br /> freshwater bearing sediments (Hotchkiss 1971)which are predominantly marine in origin and <br /> contain ancient sea water. The exploration borehole will penetrate into the San Joaquin <br /> Formation to confirm its depth and the base of fresh water. Once the final well designs are <br /> selected using geophysical surveys (electric and spontaneous potential), the bottom portions of <br /> the borehole will be selectively filled and bentonite clay layers will be positioned opposite the <br /> top of the formation to prevent releases of saline water into the fresh-water aquifers. <br /> GEI Consultants, Inc. 8 <br />