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>� specific basis by the Health Officer. Includes observation <br /> and monitoring wells. A grout seal greater than shown may be <br /> required. <br /> 4. . Where adverse conditions exist, the above seal depths <br /> shall be increased or decreased or special means of <br /> protection shall be provided as approved by the <br /> Health Officer. <br /> S. All sealing shall be permanent. <br /> P. SEALING MATERIAL: The sealing material shall consist of <br /> neat cement grout, or sand-cement grout. <br /> Cement used for sealing mixtures and materials used as <br /> additives shall meet requirements of appropriate ASTM <br /> standards. * <br /> *American Society for Testing and Material (ASTM) C150 <br /> "Standard Specification for Portland Cement" types I, <br /> III, V, and ASTM C494' "Standard Specification for <br /> Chemical Admixtures for Concrete% <br /> 1 . Water used for sealing mixtures shall be of <br /> potable quality. <br /> 2. Neat cement grout shall be composed of one sack of <br /> Portland cement (94 lbs. ) to 4-1/2 to 6-1/2 gallons <br /> of water. <br /> 3. Sand-Cement grout shall be composed of not more than <br /> two parts by weight of sand and one part of Portland <br /> cement to 4-1 /2 to 6-1/2 gallons of water per sack of <br /> cement. <br /> 4. Special quick-setting cement, retardants to setting <br /> and other additives, including hydrated lime, to make <br /> mixture more fluid (up to 10 percent of the volume of <br /> cement) and bentonite (up to 5 percent) to make <br /> mixture more fluid and reduce shrinkage may be used. <br /> 5. Used drillers mud, cuttings or chips from drilling <br /> the bor-hole shall not be used as sealing material . <br /> 6. Where thermoplastic casing is used, caution shall be <br /> exercised to control the heat generated during the <br /> curing of the cement (heat of hydration) . Additives <br /> which accelerate the curing process shall not be used <br /> where thermoplastic casing is installed. * <br /> *Refer to "Manual on the Selection and Installation <br /> of Thermoplastic Water Well Casing" or <br />