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0 0 Monitoring Well Installation Work Plan White Slough Water Pollution Control Facility Soil sampling will be conducted of the borehole at 5-foot intervals for visual classification of soils using the following procedure. • The borehole will be drilled to the desired sampling depth. • The modified split-spoon will be loaded with three 2-inch-diameter by 6-inch-long brass tubes and attached to the drill rod. • The drill rod with the split-spoon sampler will then be deployed to the bottom of the borehole and advanced using a percussion hammer(140-pound hammer with a standard 30-inch drop) across the sampling interval (18 inches). • The drill rod and sampler will then be retrieved from the borehole, the split-spoon sampler will be split apart, and the sample containers (tubes) will be collected. The lower two tubes will be used for visual-manual soil description. The field geologist will also maintain daily field logs that will include information on the date and time of arrival, general site conditions, and other applicable field observations relating to the installation. 4.2.2 Well Materials and Construction Procedures The well riser casing will be constructed of 2-inch diameter, square-threaded and flush jointed Schedule 40 polyvinyl chloride (PVC) well pipe (Figure 4-1). The well screen will be 2-inch diameter, slotted Schedule 40 PVC pipe. If flowing sands or excessively fine soils are encountered, a field decision will be made to include a 5-foot blank section of casing (sand sump)below the screen. The well will be provided with a PVC top cap and locking cover. The sand filter pack will consist of Lonestar #2/12, or similar, washed sand. The well will be screened across the first occurrence of groundwater. The screen length for the monitoring well will be 15 feet, set with the bottom of the screen approximately ten feet below the anticipated lowest annual static water level. Actual depths and construction details will be based on conditions encountered during drilling. A well screen slot size of 0.020 inches will be used, a size that will retain 90 percent or more of the selected filter pack material. A bentonite slurry will be used as a seal above the sand pack to prevent downward seepage along the casing. The remainder of the annulus will be grouted with 7 gallon/sack neat cement. The well will be installed through the inside of the hollow-stem auger to prevent the collapse of the boring wall. The casing will be extracted one section at a time as sufficient well materials are placed in the borehole to offset the earth pressure acting against the boring wall. Initially, one to two feet of sand pack will be placed in the bottom of the boring. The well screen with attached PVC plug will be placed on this sand pack. Unperforated 2-inch diameter PVC casing will complete the upper portions of the well. A sand pack will be placed in the annular space between the well screen and the boring wall. The sand pack will be placed to approximately two feet above the top of the well screen. A minimum of one foot of bentonite slurry will be placed above the uppermost sand pack as a seal. WEST YOST ASSOCIATES 6 City of Lodi September 2014 Monitoring Well Installation Work Plan w\c\21 3\06-14-31\wp\W P\083014_1 R W P