(a) The annular space or any opening surrounding a well casing shall be completely filled with neat Portland cement grout or with approved bentonite clay/cement grout from an elevation above the established grade of the surface at the well into a continuous impervious formation, or to a safe depth below the probable present or future operating water level. The minimum width of the annular space for grouting shall provide a clearance of at least one and one-half inches. Grouting space shall be at least three inches larger than the outside diameter of the casing.
(b) The annular space between the inner or protective casing and the outer casing or hole shall be filled with cement or approved bentonite grout. Any outer casing installed shall be removed during the grouting procedure unless approved by the Health Director prior to the grouting procedure.
(1) Cement grout shall be proportioned of cement and the minimum quantity of water (five to six and one-half gallons per cubic feet of cement) required to give a mixture of such consistency that it can be forced through the grout pipe.
(2) Bentonite clay grout may be used when installed by a method approved by the Virginia Department of Health and the Director.
(c) Grouting shall be done by a method which forces the grout from the bottom of the space to be grouted towards the surface. The method of mixing and the consistency of the grout shall insure that the grout fills the annual space. A suitable retainer, packer or plug shall be provided at the lower terminus of the grouting so that grout will not leak through into the water-bearing formation. The grouting shall be done continuously and in such a manner as will insure the entire filling of the annular space in one operation. No drilling operation or other work in the well shall be permitted within seventy-two hours after the cement grouting of casings. If high early strength Portland cement is used, this period may be reduced to twenty-four hours.
(Ord. 88-14. Passed 9-19-88.)