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F. Borehole Bottom Plug I. If the borehole is drilled deeper than the well depth as determined by the Engineer. Contractor shall fill the borehole with a mixture of bentonite and sand to no more than 10 feet below and no less than 5 feet below the bottom of the well. The bentonite-sand mixture shall be allowed to set for no less than 24 hours prior to the well installation within the borehole, unless approved by the engineer. 2. The method of bottom plugplacementshall be by hydraulically pumping the grout through a tremie pipe from the bottom of the annulus upward. The rate of materials placement shall not exceed 1-1/2 feet per minute, as measured by a sounding line, and placement shall proceed without interruption until completion,unless approved by the Engineer. 3.2 WELL DEVELOPMENT A. General: Between 24 and 48 hours of emplacement of the grout(cement)seal,Contractor shall begin development of the well in conformance with the following Specifications. Tile Contractor shall furnish all materials. equipment,and labor required to develop the well B. Initial development: 1. Residual drilling fluids shall be air-lifted pumped from the well. 2. Drilling fluids are to be held in containers provided by the Contractor for subsequent disposal. C. ' Chemical dispersant(as needed or as selected by Contractor): I. Use of drilling mud dispersant shall be at the discretion of the Contractor. i 2. if selected by Contractor, once residual drilling fluids have been removed from the well. the Contractor shall install a polymer drilling mud dispersant into the well. a. The dispersant shall be installed according to manufacturer's recommendations. D. Line Swabbing: I. After drilling mud dispersant(if selected by Contractor)has been installed in the well,the well shall be line swabbed throughout the perforated interval(s). Periodically, the Contractor shall remove from the well all sand,silt,and clay that have accumulated at the bottom. Swabbing in the perforated casing sections shall continue until no additional appreciable quantity of sand, silt, or clay have been washed through the screen. It is expected that swabbing and bailing of the screen intervals shall continue for a minimum of 12 hours or until sand silt and clay have been washed throughout the screen to the satisfaction of the Engineer. Upon completion of the procedure. the well shall be bailed clean of all accumulated sediment to its full depth. E. Completion of Well Development:The well shall be considered thoroughly developed when: I. The water produced reaches field-measured turbidity reading of 2. Accumulated fill shall be removed from well such that when sounded,the total well depth will be within 6 inches of the completion depth of the well. 3. Testing of the well indicates that formation damage (e.g. well bore skin) arising from drilling activities has been restored. 3.3 WELL TESTING A. Water Quality Testing of Completed Well: 1. Upon completion of the developed well, Engineer shall collect a representative sample of the well water and deliver it to a California FLAP certified laboratory for testing. 2. Cost for laboratory testing shall be at the expense of the Contractor. GRINDSTONE.JOE'S SUMMARY OF WORK June 25,2019 REPLACEMENT WELL 01 1100-9