Ohio Administrative Code|Rule 3745-9-06 | Well construction, specific geologic conditions.

                                                
(A) In addition to the requirements of
		  rule 3745-9-05 of the Administrative Code, a well completed in specific
		  geologic conditions shall be constructed according to the following
		  procedures:
(1) Where consolidated
			 formations are encountered within twenty-five feet of the ground surface, an
			 oversized borehole shall be drilled and the annular space shall be filled with
			 grout by pressure grouting.
(2) A well completed
			 where multiple aquifers are present shall have the casing extend through
			 aquifers that are not contributing to the water supply of the well. The annular
			 space contiguous to aquifers that are not contributing to the water supply of
			 the well shall be filled with grout by pressure grouting.
(3) A well completed in
			 confined aquifers shall have the casing extend through the confining layer to
			 the top of the aquifer. The annular space contiguous to the confining formation
			 shall be filled with grout by pressure grouting. Filter packs and formation
			 stabilizers shall not extend significantly into a confining formation or allow
			 interconnection of two separate aquifers along the annular space.
(4) A well completed in
			 aquifers with hydrostatic heads greater than the land surface elevation shall
			 have casing and grout installed to protect the aquifer, prevent erosion of the
			 overlying geologic materials and confine the flow to within the casing, and
			 shall be constructed according to the following procedures:
(a) If the anticipated flow at the ground surface is not
				excessive, after the borehole is drilled, and the casing set, the water in the
				casing may be pumped to lower the water level in the casing and the annular
				space. The annular space shall then be filled with cement grout by pressure
				grouting. The density of cement grout shall be sufficient to control flow in
				the annular space, but no less than that required by rule 3745-9-07 of the
				Administrative Code.
(b) If the water flow at the ground surface is anticipated to
				exceed five gallons per minute, an upper enlarged borehole shall be drilled
				partially into the confining formation. The upper enlarged borehole shall be at
				least four inches in diameter larger than the nominal diameter of the outer
				well casing. The annular space between the upper enlarged borehole and outer
				well casing shall be filled with cement grout by pressure grouting. The outer
				casing may be left as permanent casing once the well is completed, or it may be
				removed. Where outer casing is not removed, the casing shall be withdrawn at
				least five feet to ensure grout contact with the formation.
(i) If the confined
				  aquifer is consolidated, a smaller diameter borehole shall be drilled through
				  the upper enlarged borehole, the inner casing shall be firmly seated into the
				  bedrock, and the remaining annular space shall be filled with cement grout by
				  pressure grouting. The density of cement grout shall be sufficient to control
				  flow in the annular space, but no less than that required by rule 3745-9-07 of
				  the Administrative Code.
(ii) If the confined
				  aquifer is unconsolidated, a smaller diameter borehole shall be drilled through
				  the upper enlarged borehole, with casing and a screen installed into the
				  confined aquifer. The well shall be double-cased, and the remaining annular
				  space filled with cement grout by pressure grouting. The density of cement
				  grout shall be sufficient to control flow in the annular space, but no less
				  than that required by rule 3745-9-07 of the Administrative Code.
(5) A well completed in a
			 cavernous formation or mine shall be constructed according to the
			 following:
(a) A cavernous formation or mine that is not being used as a
				source of water shall have casing installed through the formation or mine, as
				follows:
(i) If a cavernous
				  formation or mine is greater than twenty-five feet below ground surface, then
				  the formation or mine shall be filled with cuttings, clean gravel or grout.
				  Packers or shale traps shall be installed at the top and bottom of the
				  formation or mine. The annular space shall then be filled with grout by
				  pressure grouting.
(ii) If a cavernous
				  formation or mine is less than twenty-five feet below ground surface, casing
				  shall be installed in an enlarged borehole and the annular space shall be
				  filled with a cement grout containing additives that promote bridging of the
				  cavernous formation or mine by pressure grouting to a depth of at least five
				  feet beyond the formation or mine.
(b) If a cavernous formation or mine will be the source of water
				supply, then a packer or shale trap shall be installed at the top of the
				formation or mine and the annular space shall be filled by pressure grouting
				with grout.
(6) A well encountering
			 brine producing formations shall be constructed according to these procedures.
			 Brine producing formations that are encountered during drilling shall have
			 casing installed throughout the entire formation. The annular space contiguous
			 to the brine producing formation shall be filled with grout by pressure
			 grouting, or the well shall be sealed to an elevation higher than the top of
			 the brine producing formation. Grout that is not adversely affected by the
			 brine water shall be used for sealing the well or annular space.
(7) Except when a well is
			 completed in the upper-most weathered portion of a consolidated formation, a
			 well completed in a consolidated formation shall have the casing extend into
			 the formation so that the well casing will not settle or shift, and will have a
			 proper annular seal.