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- i ASTM C494 Standard Specifications for Chemical Admixtures for Concrete. Additives must be approved by the Engineer. The sand shall be washed clean prior to mixture. 2. Special care shall be exercised to control the heat of hvdration generated during tilt setting and curing of cement in the annular seal to prevent deformation of the plastic casing. Caution should be exercised when using additives that accelerate cement setting as they tend to increase the rate of heat generation during setting. 3. Grout used for well abandonment by pressure grouting and for bottom plugs will be a neat cement grout or bentonite clay mixture. The cement shall meet the requirements. including latest revisions, of ASTM C150 Standard Specifications for Portland Cement Type 11. or an approved equivalent. Any additives shall meet the requirements- including the latest revisions,of ASTM C494 Standard Specifications for Chemical Admixtures tix Concrete. Additives must be approved by the Engineer. The sand shall be washed clean prior to mixture. G. Bottom Plug and Intermediate Bentonite Annular Seal: 1. The bottom plug, shall be a mixture of equal parts granular bentonite and sand. The sand shall be washed clean prior to mixing. 2. Intermediate bentonite clay seals (annular seals) via the annular space surrounding the 6 inch diameter well casing may be required to prevent vertical movement of lower quality groundwater. 3. The intermediate annular seal shall be a mixture of equal parts granular bentonite and washed sand. 4. The intervals for the intermediate annular seals will he determined by the Engineer on the basis of field conditions revealed by the borehole. H. Well Head and Surface Seal: I. The well shall be finished with the 6 inch PVC casing rising a minimum of 12 inches above the ground surface(above grade)and protected with a water tight steel cap. 2. The concrete for the pad surrounding the well head shall be ready-mixed conforming,to ASTM C94. 3/4 inch (3/4") maximum aggregate size, 3.000 psi minimum. 28-day strength,with a two to four inch(2"4")slump,and a minimum of 517 pounds of cement per cubic yard. 3. In the case where the pump head and motor assembly is installed directly over the casing, a watertight seal(gasket)shall be placed between the pump head and the pump base(slab). or a water-tight seal (gasket) shall be placed between the pump base and the rim of the casing,or a well cap shall be installed to close the annular opening between the casing and the pump column pipe. 4. Where a submersible pump is used,the opening between the well casing and any pipes or cables which enter the well shall be closed by a watertight seal or well cap. 5. Openings into the top of the well designed to provide access to the well (e.g. for measuring,chlorinating,adding gravel.etc.)shall be protected against entrance of surface waters or foreign matter by installation of watertight caps or plugs. I) A sounding hole tap (through well cap) must be provided for measurement of depth to groundwater. 2) A watertight seal or gasket shall be placed between the pump discharge head and the discharge line,or in the event of a below-ground discharge.hetween tite discharge pipe and discharge line. 6. Openings designed to permit the entrance or egress of air or gas(air or casing vents)shall terminate above the ground and above the known Flood levels (72 incites above grade), and shall be protected against the entrance of foreign material by installation of down- turned and screened"U"bends. GRINDSTONE JOE'S SUMMARY OF WORK REPLACEMENT WELL. 01 11 00-5 tune 25,2019