Chapter 1501:21-13 Classification and Design of Dams, Dikes, and Levees

1501:21-13-01 Classification of dams.

(A) For the purpose of this chapter, dams shall be divided into four classes, which shall be known as class I, class II, class III, and class IV. The chief shall establish a dam's appropriate classification by using the following criteria as a guideline. Such classification shall be established by the chief during the preliminary review described by rule 1501:21-5-02 of the Administrative Code or during the periodic inspection described by rule 1501:21-21-01 of the Administrative Code. The chief reserves the right to reclassify any dam at any time as a result of circumstances not in existence or not known at the time said dam was initially classified.

(1) Dams having a total storage volume greater than five thousand acre-feet or a height of greater than sixty feet shall be placed in class I. A dam shall be placed in class I when sudden failure of the dam would result in one of the following conditions.

(a) Probable loss of human life.

(b) Structural collapse of at least one residence or one commercial or industrial business.

(2) Dams having a total storage volume greater than five hundred acre-feet or a height of greater than forty feet shall be placed in class II. A dam shall be placed in class II when sudden failure of the dam would result in at least one of the following conditions, but loss of human life is not probable.

(a) Disruption of a public water supply or wastewater treatment facility, release of health hazardous industrial or commercial waste, or other health hazards.

(b) Flooding of residential, commercial, industrial, or publicly owned structures. At the request of the dam owner, the chief may exempt dams from the criterion of this paragraph if the dam owner owns the potentially affected property.

(c) Flooding of high-value property. At the request of the dam owner, the chief may exempt dams from the criterion of this paragraph if the dam owner owns the potentially affected property.

(d) Damage or disruption to major roads including but not limited to interstate and state highways, and the only access to residential or other critical areas such as hospitals, nursing homes, or correctional facilities as determined by the chief.

(e) Damage or disruption to railroads or public utilities.

(f) Damage to downstream class I, II or III dams or levees, or other dams or levees of high value. Damage to dams or levees can include, but is not limited to, overtopping of the structure. At the request of the dam owner, the chief may exempt dams from the criterion of this paragraph if the dam owner owns the potentially affected property.

(3) Dams having a total storage volume greater than fifty acre-feet or a height of greater than twenty-five feet shall be placed in class III. A dam shall be placed in class III when sudden failure of the dam would result in at least one of the following conditions, but loss of human life is not probable.

(a) Property losses including but not limited to rural buildings not otherwise described in paragraph (A) of this rule, and class IV dams and levees not otherwise listed as high-value property in paragraph (A) of this rule. At the request of the dam owner, the chief may exempt dams from the criterion of this paragraph if the dam owner owns the potentially affected property.

(b) Damage or disruption to local roads including but not limited to roads not otherwise listed as major roads in paragraph (A) of this rule.

(4) Dams which are twenty-five feet or less in height and have a total storage volume of fifty acre-feet or less may be placed in class IV. When sudden failure of the dam would result in property losses restricted mainly to the dam and rural lands, and loss of human life is not probable, the dam may be placed in class IV. Class IV dams are exempt from the permit requirements of section 1521.06 of the Revised Code pursuant to paragraph (C) of rule 1501:21-19-01 of the Administrative Code.

(B) All pertinent information including any unusual circumstances shall be considered by the chief in establishing an appropriate classification for a dam. Probable future development of the area downstream from the dam that would be affected by its failure shall be considered. Completed downstream hazard mitigation such as acquisition, removal or protection of downstream property may also be considered. However, the above criteria shall in no way preclude the chief's requirement of greater safety in the interest of life, health, or property.

Effective: 05/23/2010
R.C. 119.032 review dates: 03/08/2010 and 05/15/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061
Prior Effective Dates: 4-15-72; 10-15-81; 12-9-99; 1-16-05

1501:21-13-02 Design flood for dams and determination of critical flood.

The magnitude of the design flood for each dam shall be set by the chief and determined from actual streamflow and flood frequency records or from synthetic hydrologic criteria based on current publications prepared by the division, the United States army corps of engineers, the United States geological survey, the national oceanic and atmospheric administration, or others acceptable to the chief.

(A) The minimum design flood will be:

(1) For class I dams, the probable maximum flood or the critical flood;

(2) For class II dams, fifty percent of the probable maximum flood or the critical flood; and,

(3) For class III dams, twenty-five percent of the probable maximum flood or the critical flood.

(B) Selection of a critical flood as the design flood is acceptable. The design for the critical flood shall be for site-specific conditions and based on a quantitative and relative impact analysis of the downstream critical routing reach. In determining the critical flood, the spillway and storage capacity for the dam shall be designed so that there will be no additional potential for loss of life, health or property in the critical routing reach from overtopping failure of the dam when compared to the potential for loss of life, health or property caused by the flood in the absence of a dam overtopping failure.

(1) Where the incremental depth of flow between the failure and non-failure floods is 2.0 feet or greater, or the product of the average floodplain flow velocity (in feet per second) and the incremental flood depth (in feet) is greater than 7.0, additional potential for loss of life, health or property in the critical routing reach is expected.

(2) If the incremental depth of flow between the failure and non-failure floods is less than 2.0 feet, and the product of the average floodplain flow velocity (in feet per second) and the incremental flood depth (in feet) is less than 7.0, it does not necessarily mean that the critical flood has been determined. Further investigation will be required to determine that no additional potential for loss of life, health or property will occur.

(C) The minimum critical flood shall be as follows:

(1) Forty per cent of the probable maximum flood for a class I dam,

(2) Twenty per cent of the probable maximum flood for a class II dam, and

(3) The one-hundred-year flood for a class III dam.

(D) The owner or applicant shall submit to the chief, in writing, a request for consideration of the critical flood as the design flood. This request shall be accompanied by appropriate supporting calculations. The chief will not consider risk assessment based upon planned evacuation, probability of inhabitation, or monetary recovery of property damage.

(E) If downstream hazard conditions change at any time during the life of the structure, a reevaluation of the critical routing reach and modification of the critical flood may be required by the chief.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 12-9-99; 1-16-05

1501:21-13-03 Spillway design, general requirements.

(A) Every dam shall have a spillway system which will safely operate during the design flood without endangering the safety of the dam.

(B) Each spillway shall include a means of dissipating the energy of flow without endangering the safety of the dam.

(C) The capacity of the spillway system shall be equal to the peak inflow rate of the design flood unless the applicant has demonstrated by flood routing procedures that the dam will safely pass the design flood with the spillway system.

(D) Every upground reservoir shall have an overflow or other device to preclude overfilling the reservoir during normal filling operations. Local watershed drainage into the reservoir must also be included in the design of the overflow device if applicable.

(1) The elevation of an overflow device shall be no more than 0.5 foot above the designed maximum operating pool level of the reservoir.

(2) A device other than an overflow that is used to preclude overfilling must prevent the reservoir from rising 0.5 foot above the designed maximum operating pool level.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061
Prior Effective Dates: 4-15-72; 10-15-81; 12-9-99; 1-16-05

1501:21-13-04 Pipe conduit spillways, general requirements.

(A) All pipe conduits shall convey flow at the maximum design velocity without damage to the interior surface.

(B) Seepage control devices acceptable to the chief shall be installed. .

(C) Adequate allowances shall be incorporated in the design to compensate for settlement and possible elongation of the pipe conduit.

(D) An anti-vortex device that is satisfactory to the chief shall be installed at the intake of all pipe and riser spillway systems. Anti-vortex devices may also be required for other spillway types as necessary to improve the performance of the spillway.

(E) A trash rack that is satisfactory to the chief shall be installed at the intake of all pipe and riser and/or drop inlet type spillway systems to prevent clogging the pipe conduit. Trash rack devices may also be required for other spillway types as necessary to ensure the performance of the spillway.

(F) An emergency overflow spillway shall be required, except when specifically exempted by the chief. A vegetated or unlined emergency spillway will be approved by the chief, but only after the applicant has demonstrated that it will pass the design flood without jeopardizing the safety of the structure. The average frequency of use for a vegetated or unlined emergency spillway must be predicted to be less than the following criteria unless otherwise approved by the chief:

(1) Once in fifty years for class I dams;

(2) Once in twenty-five years for class II dams; and

(3) Once in ten years for class III dams.

(G) The pipe conduit shall be of such size as to remove from the reservoir within ten days following passage of the design flood peak at least eighty percent of the water temporarily detained in the reservoir above the elevation of the primary (principal) spillway.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 4-15-72; 10-15-81; 12-9-99; 1-16-05

1501:21-13-05 Pipe conduit spillways, special requirements.

(A) Pipe conduits shall be of such design as to safely support the total external loads and shall convey flow without rupture or leakage.

(B) Unless otherwise approved by the chief, the minimum inside dimension of the pipe conduit shall be:

(1) Twenty-four inches for class I and class II dams.

(2) Eighteen inches for class III dams.

(C) All pipes shall have the ability to resist corrosion from surrounding soils and impounded materials based on current acceptable testing standards.

(D) Corrugated metal pipe shall not be used.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 4-15-72; 10-15-81; 12-9-99; 1-16-05

1501:21-13-06 Requirements for drains and other pipe conduits.

(A) Dams in class I, class II, and class III shall include a device to permit draining the reservoir within a reasonable period of time as approved by the chief. Pipe conduits used for lake drains shall have a minimum inside diameter of not less than four inches.

(B) Valves or sluice gates in pipe conduits shall be installed upstream from the centerline of the dam unless otherwise approved by the chief.

(C) All pipe conduits used as drains, water supply lines, or other pressure-flow conduits, regardless of classification of the dam, shall meet the requirements of paragraphs (A), (B), (C), and (E) of rule 1501:21-13-04 of the Administrative Code and paragraphs (A), (C), and (D) of rule 1501:21-13-05 of the Administrative Code.

(D) When the drain outlets into a pipe-conduit upstream from the centerline of the dam, seepage control devices may be omitted from the drain.

(E) All new dam construction shall include a bulkhead for the outlet works unless specifically exempted by the chief.

Effective: 05/23/2010
R.C. 119.032 review dates: 03/08/2010 and 05/15/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061
Prior Effective Dates: 4-15-72; 10-15-81; 12-9-99; 1-16-05

1501:21-13-07 Freeboard requirements for dams.

Sufficient freeboard shall be provided to prevent overtopping of the top of the dam due to passage of the design flood and other factors including, but not limited to, ice and wave action. The chief may approve a lower freeboard requirement if the dam is armored against overtopping erosion.

(A) For class I and class II dams that are upground reservoirs, the minimum elevation of the top of the dam shall be at least five feet higher than the elevation of the designed maximum operating pool level unless otherwise approved by the chief.

(B) For class III dams that are upground reservoirs, the minimum elevation of the top of the dam shall be at least three feet higher than the elevation of the designed maximum operating pool level unless otherwise approved by the chief.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 4-15-72; 10-15-81; 12-9-99; 1-16-05

1501:21-13-08 Additional design requirements for dams.

(A) The safety factors for the various elements of the dam shall conform to good engineering practice as approved by the chief. The safety factors and the design standards that are used by the applicant shall agree with the approved design assumptions.

(B) Inspection devices such as piezometers, settlement platforms, stand-pipes, tell-tale stakes, monitoring weirs, inclinometers, and permanent bench marks, may be required by the chief for the division's and the owner's use in the inspection of the structure during and after completion of construction.

(C) The chief may require dams to have a staff gauge to allow monitoring of lake levels within a range from the lower of five feet below normal pool or the normal drawdown level, to the top of dam elevation. The design of the staff gauge will be reviewed and approved by the chief.

(D) Grass vegetation or other vegetation of similar properties are the only acceptable vegetative covers for earthen dam embankment surfaces or vegetated earth spillways. Trees and brush are not acceptable surface covers.

(E) The applicant shall demonstrate to the satisfaction of the chief that the structure will be consistent and in accordance with all applicable state and local floodplain regulations and requirements.

Effective: 05/23/2010
R.C. 119.032 review dates: 03/08/2010 and 05/15/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061
Prior Effective Dates: 4-15-72; 10-15-81; 12-9-99; 1-16-05

1501:21-13-09 Classification of levees.

(A) For the purpose of this chapter, levees shall be divided into four classes, which shall be known as class I, class II, class III, and class IV. The chief shall establish a levee's appropriate classification by using use the following criteria as a guideline. Such classification shall be established by the chief during the review of the preliminary design report described by rule 1501:21-5-02 of the Administrative Code or during the periodic inspection described by rule 1501:21-21-01 of the Administrative Code. The chief reserves the right to reclassify any levee at any time as a result of circumstances not in existence or not known at the time said levee was initially classified.

(1) A levee shall be placed in class I when sudden failure of the levee would result in one of the following conditions.

(a) Probable loss of human life.

(b) Structural collapse of at least one residence or one commercial or industrial business.

(2) A levee shall be placed in class II when sudden failure of the levee would result in at least one of the following conditions, but loss of human life is not probable.

(a) Disruption of a public water supply or wastewater treatment facility, or other health hazards.

(b) Flooding of residential, commercial, industrial, or publicly owned structures.

(c) Flooding of high-value property.

(d) Damage or disruption to major roads including but not limited to interstate and state highways, and the only access to residential or other critical areas such as hospitals, nursing homes, or correctional facilities as determined by the chief.

(e) Damage or disruption to railroads or public utilities.

(3) A levee shall be placed in class III when sudden failure of the levee would result in at least one of the following conditions, but loss of human life is not probable.

(a) Property losses including but not limited to rural buildings not otherwise described in paragraph (A) of this rule.

(b) Damage or disruption to local roads including but not limited to roads not otherwise listed as major roads in paragraph (A) of this rule.

(4) A levee having a height of not more than three feet shall be placed in class IV. When sudden failure of the levee would result in property losses restricted mainly to the levee and to the owner's property or to rural lands, and loss of human life is not probable, the levee may be placed in class IV. Class IV levees are exempt from the permit requirements of section 1521.06 of the Revised Code pursuant to paragraph (C) of rule 1501:21-19-01 of the Administrative Code.

(B) All pertinent information including any unusual circumstances shall be considered by the chief in establishing an appropriate classification for a levee. Probable future development of the area adjacent to the levee shall be considered. However, the above criteria shall in no way preclude the chiefs requirement of greater safety in the interest of life, health, and property.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 10-15-81; 12-9-99; 1-16-05

1501:21-13-10 Levees, general requirements.

(A) Future development of areas upstream, downstream, and adjacent to the levee shall be considered in the design.

(B) The levee shall operate safely during all floods up to the design flood elevation.

(C) Provisions for drainage of the area protected by the levee shall be incorporated into the structure. Measures shall be included to prevent flooding of this area by backflow through the drainage system.

(D) The levee must be protected from or designed to prevent erosive velocities along the structure and its foundation.

(E) Grass vegetation or other vegetation of similar properties are the only acceptable vegetative covers for earthen levee embankment surfaces. Vetch, trees and brush are not acceptable surface covers.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 10-15-81; 12-9-99; 1-16-05

1501:21-13-11 Levees, special requirements.

(A) Hydraulic analyses shall be conducted to determine flood elevations for stream reaches affected by the construction of a levee and in accordance with rule 1501:21-13-10 of the Administrative Code. The analyses must provide flood depth and velocity data during the one-hundred-year, twenty-five-year, and five-year flood events, and for the top-of-levee flood event. For construction of new levees, the flood depths and velocities must be determined with and without the levee. The impact of increased flood depths and velocities on property and structures must be provided.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 10-15-81; 12-9-99; 1-16-05

1501:21-13-12 Design flood for levees.

(A) The design flood shall be established by the chief in concert with the applicant's desired level of protection, but with the utmost interest in safeguarding life, health, and property. For class I levees, the minimum design flood will be the one-hundred-year flood or the critical flood. The design for the critical flood shall be for site-specific conditions and based on a quantitative and relative impact analysis of the protected area. In determining the critical flood, the levee shall be designed so that there will be no additional potential for loss of life, health or property from overtopping failure of the levee when compared to the potential for loss of life, health or property caused by the flood in the absence of a levee overtopping failure.

(B) The magnitude of the design flood shall be determined from actual streamflow and flood frequency records or from synthetic hydrologic criteria based on current publications prepared by the division, the national oceanic and atmospheric administration (NOAA), the United States army corps of engineers, the United States geological survey, or others specifically approved by the chief.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 10-15-81; 12-9-99; 1-16-05

1501:21-13-13 Freeboard requirements for levees.

(A) For levees in class I, the minimum elevations of the top of the levee shall be at least three feet higher than the maximum adjacent water surface elevations during passage of the design flood. The chief may approve a lower freeboard requirement with acceptable documentation.

(B) For levees in class II and class III, the minimum elevations of the top of the levee shall be two feet higher than the maximum adjacent water surface elevations during passage of the design flood.

(C) Where special conditions of severe frost damage, ice damage, stream obstruction, wave action, or impact of other structures may occur, the chief may require elevations higher than required in paragraph (A) of this rule.

Effective: 05/23/2010
R.C. 119.032 review dates: 03/08/2010 and 05/15/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 10-15-81; 12-9-99; 1-16-05

1501:21-13-14 Additional design requirements for levees.

(A) The safety factors of the various elements of the levee shall conform to good engineering practice as approved by the chief. The safety factors and the design standards that are used by the applicant shall agree with the approved design assumptions.

(B) Design references that are used shall be cited in the information that is submitted to the chief.

(C) Inspection devices, which include but are not necessarily restricted to settlement platforms, tell-tale stakes, inclinometers and permanent bench marks, may be required by the chief for the division's and the owner's use in the inspection during and after completion of construction.

R.C. 119.032 review dates: 03/08/2010 and 03/05/2015
Promulgated Under: 119.03
Statutory Authority: 1521.06
Rule Amplifies: 1521.06 , 1521.061 , 1521.062
Prior Effective Dates: 10-15-81; 12-9-99; 1-16-05