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Ohio Laws and Rules
In addition to the requirements of rule 3701-28-12 of the Administrative Code, wells completed in special geologic conditions shall be constructed according to the following procedures:
(A) Wells completed in unconsolidated and consolidated aquifers may have less than twenty-five feet of casing where geologic and hydro geologic conditions indicate potable water is not present at depths greater than twenty-five feet. Under no conditions shall casing extend to a depth of less than fifteen feet.
(B) 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 cement grout or bentonite grout by pressure grouting.
(C) Wells 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 cement grout or bentonite grout by pressure grouting.
(D) Wells 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 cement grout or bentonite 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.
(E) Wells 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, as applicable:
(1) 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. However, the density of the cement grout may be greater than that required under paragraph (D) of rule 3701-28-111 of the Administrative Code to control flow in the annular space.
(2) If the anticipated flow at the ground surface is excessive, 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 may be removed.
(a) 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. However, the density of the cement grout may be greater than that required under under paragraph (D) of rule 3701-28-111 of the Administrative Code to control flow in the annular space.
(b) 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. However, the density of the cement grout may be greater than that required under paragraph (D) of rule 3701-28-111 of the Administrative Code to control flow in the annular space.
(F) Wells completed in cavernous, highly fractured formations, or mine shafts shall be constructed according to the following, as applicable:
(1) Any cavernous, highly fractured formations or mine shafts that are not being used as a source of water shall have casing installed through the cavernous, highly fractured formations or mine shafts and comply with the following, as applicable:
(a) If cavernous, highly fractured formations or mine shafts are greater than twenty-five feet from the ground surface, then the formation or shaft shall be filled with cuttings, clean gravel or grout, or packers or shale baskets shall be installed at the top and bottom of the formation or shaft. The annular space shall then be filled with cement grout or bentonite grout by pressure grouting.
(b) If cavernous, highly fractured formations or mine shafts are less than twenty-five feet from the 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, highly fractured formations or mine shafts by pressure grouting to a depth of at least five feet beyond the cavernous, fractured formation or mine shaft.
(4) If the cavernous, highly fractured formation or mine shaft is to be used as the source of water supply, then a packer or shale basket shall be installed at the top of the formation or shaft and the annular space shall be filled with cement grout or bentonite grout by pressure grouting.
(G) Wells encountering brine producing formations shall be constructed according to the following procedures:
(1) Any brine producing formations that are encountered during drilling shall have casing installed through the brine producing formation and the annular space contiguous to the brine producing formation shall be filled with cement grout or bentonite grout by pressure grouting or the well shall be sealed to an elevation higher than the top of the brine producing formation. Grouts that are not adversely affected by the brine water shall be used for sealing the well or annular space.
(2) If the brine producing formation cannot be successfully isolated from the water source, then the entire well shall be sealed in accordance with rules 3701-28-07 and 3701-28-071 of the Administrative Code.
R.C. 119.032 review dates: 12/23/2004 and 11/15/2009
Promulgated Under: 119.03
Statutory Authority: 3701.344
Rule Amplifies: 3701.344
Prior Effective Dates: 1/1/2000