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WORK PLAN FOR INSTALLATION OF PIEZOMETERS Irerracon Seefried Warehouses Tracy, Califomia November 12, 2019 Terracon Project No. NA185181 each select sampling location. GPR activities will be completed on the first day of planned drilling activities. 2.6 Soil Borings No later than 48 hours to the start of field work, Terracon will notify SJCDEH of our proposed work day and confirm that a representative of the SJCDEH will be available for construction and grout placement inspection. Three soil borings will be advanced using a hollow -stem auger drill rig to a depth of approximately 20 feet below ground surface (bgs). Drilling activities will be performed by a California C-57 licensed driller. During drilling activities, soil samples will be not be collected due to already collecting soil samples during a previous geotechnical investigation at this site. 2.7 Piezometer Design/Installation Terracon proposes to drill 6 -inch diameter borings to a maximum depth of 20 feet bgs. Twenty - foot long, two-inch diameter Schedule -40 polyvinyl chloride (PVC) pipe will be installed in each boring. Each piezometer will include 10 feet of 0.020 -inch slotted screen and 10 feet of blank casing. Each piezometer will have #3 sand (or equivalent) backfilled from total depth to one foot above the screen interval, or to approximately 9 feet bgs. A two -foot hydrated bentonite plug will be placed above the filter sand pack from 9 to 7 feet bgs, and Portland neat cement grout will be added from 7 feet bgs to approximately 0.5 feet bgs. Each piezometer will be finished at the surface with an above ground locking monument that will be cemented in place. Terracon staff will schedule the piezometer construction and grout inspection with the SJCDEH no later than 48 hours prior to planned field work activities to ensure the availability of an SJCDEH representative. Additionally, Terracon will confirm the field work date and inspection time with the inspector 24 hours prior to field work. 3-n GENERAL COMMENTS The scope of services is based on the assumptions and limitations noted below. Limitations Terracon's services will be performed in a manner consistent with generally accepted practices of the professional undertaken in similar studies in the same geographic area during the same period. Terracon makes no warranties, express or implied, regarding its services, findings, conclusions or recommendations. Please note that Terracon does not warrant the work of laboratories, regulatory agencies or other third parties supplying information used in the preparation of the report. These Responsive Resourceful Reliable 3