COMPLIANCE INFO_1993-1994 - Laserfiche WebLink

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City of Stockton TL# 394-0027-01 March 10, 1994 Page 9 connections. The well filter pack material will consist of appropriately-sized pre-washed sand. The filter material will be placed in the annulus between the boring wall, from the bottom of the boring to approximately 2 feet above the top of the screen. Subsequent to filter pack emplacement, preliminary development may be performed to provide a uniform filter pack about the casing. Approximately three to five feet of bentonite will be placed on the filter pack. The bentonite may consist of 1/4- or 1/2-inch pellets, or may be in the form of a slurry. If pellets are used, they will be hydrated prior to grouting the well, by adding at least one gallon of water for every bucket of pellets. The thickness of the bentonite seal may depend upon local regulatory requirements . The remainder of the well annulus will be sealed with a 6-sack sand-cement, or cement grout slurry containing 3 to 5 percent bentonite. For wells more than 15 feet deep, the seal will be emplaced through the hollow-stem augers, which will extend to within 15 feet of the bentonite seal. If required by the local regulatory agency, the seal will be emplaced by pumping through a tremie pipe which extends to within 15 feet of the bottom of the boring. The tremie pipe or augers are withdrawn from the boring in 5-foot increments as the boring fills with grout. A watertight well cap will be placed on top of each groundwater monitoring well, and a 3-foot steel standpipe with locking cover or a traffic-rated box will be installed around the wellhead. Monitoring wells will be locked to restrict access to unauthorized personnel . Monitoring well construction details will be recorded on the field well construction form. Construction information will be transferred to Monitoring Well construction schematics for presentation in final reports. A-4 Groundwater Monitoring Well Development: When possible, initial well development will be performed during installation of the sand pack. A minimum of 48 hours following installation, groundwater monitoring wells will be developed in order to remove sediment that may accumulate in the well during installation, and to settle the filter pack. Groundwater monitoring well development will be performed using a combination of bailing, pumping, and surging. The development of each groundwater monitoring well will continue until a minimum of five well casing volumes of water have been removed, and the displaced water is relatively clear, free of sediment, and the values of pH, temperature, and specific electrical conductance (EC) have stabilized. Well development data will be recorded on the Sampling/Well Development Log (Attachment A) .