222.6—National Program for Inspection of Non-Federal Dams.

(a) Purpose. This regulation states objectives, assigns responsibilities and prescribes procedures for implementation of a National Program for Inspection of Non-Federal Dams.

(b) Applicability. This regulation is applicable to all Divisions and Districts having Civil Works functions.

(2) Freedom of Information Act, Pub. L. 87-487, 4 July 1967.

(3) ER 500-1-1.

(d) Authority. The National Dam Inspection Act, Public Law 92-367, 8 August 1972 authorizes the Secretary of the Army, acting through the Chief of Engineers, to carry out a national program of inspection of non-Federal dams for the purpose of protecting human life and property.

(e) Scope. The program provides for:

(1) An update of the National Inventory of Dams.

(2) Inspection of the following non-Federal dams (the indicated hazard potential categories are based upon the location of the dams relative to developed areas):

(i) Dams which are in the high hazard potential category (located on Federal and non-Federal lands).

(ii) Dams in the significant hazard potential category believed by the State to represent an immediate danger to the public safety due to the actual condition of the dam.

(iii) Dams in the significant hazard potential category located on Federal lands.

(iv) Specifically excluded from the national inspection program are:

(A) Dams under the jurisdiction of the Bureau of Reclamation, the Tennessee Valley Authority, the International Boundary and Water Commission and the Corps of Engineers and

(B) Dams which have been constructed pursuant to licenses issued under the authority of the Federal Power Act, and

(C) Dams which have been inspected within the 12-month period immediately prior to the enactment of this act by a State agency and which the Governor of such State requests be excluded from inspection.

(f) Objectives. The objectives of the program are:

(1) To update the National Inventory of Dams by 30 September 1980.

(2) To perform the initial technical inspection and evaluation of the non-Federal dams described in paragraph 222.8(e) of this section to identify conditions which constitute a danger to human life or property as a means of expediting the correction of hazardous conditions by non-Federal interests. The inspection and evaluation is to be completed by 30 September 1981.

(3) To obtain additional information and experience that may be useful in determining if further Federal actions are necessary to assure national dam safety.

(4) Encourage the States to establish effective dam safety programs for non-Federal dams by 30 September 1981 and assist the States in the development of the technical capability to carry out such a program.

(g) Program execution— (1) Responsibilities. The owner has the basic legal responsibility for potential hazards created by their dam(s). Phase II studies, as described in Chapter 4, Appendix D, and remedial actions are the owner's responsibility.

(ii) The State has the basic responsibility for the protection of the life and property of its citizens. Once a dam has been determined to be unsafe, it is the State's responsibility to see that timely remedial actions are taken.

(iii) The Corps of Engineers has the responsibility for executing the national program. The Federal program for inspection of dams does not modify the basic responsibilities of the States or dam owners. The Engineering Division of the Civil Works Directorate is responsible for overall program goals, guidance, technical criteria for inspections and inventory and headquarters level coordination with other agencies. The Water Resources Support Center (WRSC) located at Kingman Building, Fort Belvoir, Virginia 22060 is responsible for:

(A) Program Coordination of both the inventory and inspection programs.

(B) Developing and defining functional tasks to achieve program objectives.

(D) Compiling and disseminating progress reports.

(E) Monitoring and evaluating program progress and recommending corrective measures as needed.

(F) Collecting and evaluating data pertaining to inspection reports, dam owners' responses to inspection report recommendations, attitudes and capabilities of State officials, State dam safety legislation, Architect-Engineer performance, etc., for defining a comprehensive national dam safety program.

(G) Responding to Congressional, media, scientific and engineering organization and general public inquiries.

Division and District offices are responsible for executing the program at the State level. Assignment of Division reponsibilities for States is shown in Appendix A.

(2) State participation. Where State capability exists, every effort should be made to encourage the State to execute the inspection program either with State personnel or with Architect-Engineer (A-E) contracts under State supervision. If the State does not have the capability to carry out the inspection program, the program will be managed by the Corps of Engineers utilizing Corps employees or contracts with A-E firm.

(h) Update of National Inventory of Dams. (RCS-DAEN-CWE-17/OMB No. 49-RO421)

(1) The National Inventory of Dams should be updated and verified to include all Federal and non-Federal dams covered by the Act. Those dams are defined as all artificial barriers together with appurtenant works which impound or divert water and which: (1) Are twenty-five feet or more in height or (2) have an impounding capacity of fifty acre-feet or more. Barriers which are six feet or less in height, regardless of storage capacity or barriers which have a storage capacity at maximum water storage elevation of fifteen acre-feet or less regardless of height are not included.

(2) Inventory data for all dams shall be provided in accordance with Appendix B.

(3) The hazard potential classification shall be in accordance with paragraph 2.1.2 Hazard Potential of the Recommended Guideline for Safety Inspection of Dams (Appendix D to this section).

Table 2—Hazard Potential Classification

Category	Urban development	Economic loss
Low	No permanent structure for human habitation	Minimal (Undeveloped to occasional structures or agriculture).
Significant	No urban development and no more than a small number of habitable structures	Appreciable (Notable agriculture, industry or structures).
High	Urban development with more than a small number of habitable structures	Excessive (Extensive community, industry or agriculture).

(4) As in the original development of the inventory, the States should be encouraged to participate in the work of completing, verifying and updating the inventory. Also, when available, personnel of other appropriate Federal agencies should be utilized for the inventory work on a reimbursable basis. Work in any State may be accomplished:

(i) Under State supervision utilizing State personnel or Architect-Engineers contracts.

(ii) Under Corps supervision utilizing Corps employees, employees of other Federal agencies or Architect-Engineer contracts.

(5) A minimum staff should be assigned in Districts and Divisions to administer and monitor the inventory activities. Generally, the work should be accomplished by architect-engineers or other Federal agency personnel under State or Corps supervision. Corps personnel should participate in the inventory only to the extent needed to assure that accurate data are collected.

(6) The National Inventory of Dams computerized data base in stored on the Boeing Computer Services (BCS) EKS computer system in Seattle, Washington. The data base uses Data Base Management System 2000 and is accessible for query by all Corps offices.

(7) Appendix B indicates details on accessing and updating inventory data.

(8) Appendix I describes the procedure for using NASA Land Satellite (LANDSAT) Multispectral Scanner data along with NASA's Surface Water Detection and Mapping (DAM) computer program to assist in updating and verifying and National Inventory of Dams.

(9) All inventory data for dams will be completed and verified utilizing all available sources of information (including LANDSAT overlay maps) and will include site visitation if required. It is the responsibility of the District Engineer to insure that the inventory of each State within his area of responsibility is accurate and contains the information required by the General Instructions for completing the forms for each Federal and non-Federal dam.

(i) [Reserved]

(j) Inspection Program. (RCS-DAEN-CWE-17 and OMB No. 49-RO421)

(1) Scheduling of inspections. The Governor of each State or his designee will continue to be involved in the selection and scheduling of the dams to be inspected. Priority will be given to inspection of those dams considered to offer the greatest potential threat to public safety.

(i) No inspection of a dam should be initiated until the hazard potential classification of the dam has been verified to the satisfaction of the Corps. Dams in the significant hazard category should be inspected only if requested by the State and only then if the State can provide information to show that the dam has deficiencies that pose an immediate danger to the public safety. Guidance for the selection of significant category non-Federal dams on Federal lands will be given in the near future.

(ii) Selection for inspection of non-Federal dams located on Federal lands or non-Federal dams designed and constructed under the jurisdiction of some Federal agency, should be coordinated with the responsible Federal agency. The appropriate State or regional representative of the Federal agency also should be contacted to obtain all available data on the dam. Representatives of the agency may participate in the inspection if they desire and should be given the opportunity to review and comment on the findings and recommendations in the inspection report prior to submission to the Governor and the dam owner. Examples of such dams are: non-Federal dams built on lands managed by National Forest Service, Bureau of Land Management, Fish and Wildlife Service, etc.; non-Federal dams designed and constructed by the Soil Conservation Service of the U.S. Department of Agriculture; high hazard mine tailings and coal mine waste dams under the jurisdiction of the Mine Safety and Health Administration, Department of Labor.

(iii) Indian-owned dams on trust lands are considered to be non-Federal dams. All dams in the high hazard potential category will be inspected. Privately-owned dams located on Indian lands are to be included in the program, however BIA-owned dams on Indian lands are Federal dams and are exempt.

(2) Procedures. The Division Engineer is responsible for the quality of inspections and reports prepared by the District Engineer. Close liaison between the District Engineer and the State agency or A-E firm responsible for the inspections will be required in order to obtain a dependable result. To avoid undesirable delays in the evaluation of safety of individual dams, contracts with A-E's or agreements with States which are managing the program will provide that reports be completed and furnished to the District Engineer within a specified time after completion of the on-site inspection of the dam.

(i) Inspection guidelines. The inspection should be conducted in accordance with the Recommended Guidelines for Safety Inspection of Dams (Appendix D to this section). Expanded Guidance for Hydrologic and Hydraulic Assessment of Dams is provided in Appendix C. The criteria in the recommended guidelines are screening criteria to be used only for initial determinations of the adequacy of the dam. Conditions found during the investigation which do not meet the guideline recommendations should be assessed as to their importance from the standpoint of the degree of risk involved.

(ii) Coordinators. Experience has shown that coordination and communications among technical disciplines, Public Affairs Office, emergency officials, training officers, operations personnel, State representatives and A-E firms has been best in those districts where one person was delegated the responsiblity for coordinating the actions of all involved elements. Each district should evaluate its overall coordination procedures to insure that all involved elements have the best possible access to necessary data.

(iii) Field investigations should be carried out in a systematic manner. A detailed checklist or inspection form should be developed and used for each dam inspection and appended to the inspection report. The size of the field inspection team should be as small as practicable, generally consisting of only one representative of each required discipline in order to control the costs of the inspection without sacrificing the quality of the inspection. The inspection team for the smaller less complex dams should be limited to two or three representatives from appropriate technical areas with additional specialists used only as special conditions warrant. The larger more complex projects may require inspection teams of three or four specialists. Performance of overly detailed and precise surveys and mapping should be avoided. Necessary measurement of spillway, dam slopes, etc. can generally be made with measuring tapes and hand levels.

(iv) Additional engineering studies. Dam inspections should be limited to Phase I investigations as outlined in Chapter 3 of Appendix D. However, if recommended by the investigating engineer and approved by the District Engineer, some additional inexpensive investigations may be performed when a reasonable judgment on the safety of the dam cannot be made without additional investigation. Any further Phase II investigation needed to prove or disprove the findings of the District Engineer or to devise remedial measures to correct deficiencies are the responsibility of the owner and will not be undertaken by the Corps of Engineers.

(v) Assessment of the investigation. (A) The findings of the visual inspection and review of existing engineering data for a dam shall be assessed to determine its general condition. Dams assessed to be in generally good condition should be so described in the inspection report. Deficiencies found in a dam should be described and assessed as to the degree of risk they present. The degree of risk should consider only loss of life and/or property damage resulting from flooding due to dam failure. Loss of project benefits i.e., municipal water supply, etc., should not be considered. If deficiencies are assessed to be of such a nature that, if not corrected, they could result in the failure of the dam with subsequent loss of life and/or substantial property damage, the dam should be assessed as “Unsafe.” If the probable failure of an “Unsafe” dam is judged to be imminent and immediate action is required to reduce or eliminate the hazard, the “unsafe” condition of the dam should be considered an “emergency.” If the probable failure is judged not to be imminent, the “unsafe” condition should be considered a “non-emergency.”

(B) Adequacy of spillway. The “Recommended Guidelines for Safety Inspection of Dams,” Appendix D, provide current, acceptable inspection standards for spillway capacity. Any spillway capacity that does not meet the criteria in the “Guidelines” is considered inadequate. When a spillway's capacity is so deficient that it is seriously inadequate, the project must be considered unsafe. If all of the following conditions prevail, the Governor of the State shall be informed that such project is unsafe:

(1) There is high hazard to loss of life from large flows downstream of the dam.

(2) Dam failure resulting from overtopping would significantly increase the hazard to loss of life downstream from the dam over that which would exist just before overtopping failure.

(3) The spillway is not capable of passing one-half of the probable maximum flood without overtopping the dam and causing failure.

Classification of dams with seriously inadequate spillways as “unsafe, non-emergency” is generally a proper designation of the urgency of the unsafe condition. However, there may be cases where the spillway capacity is unusually small and the consequences of dam overtopping and failure would be catastrophic. In such cases, the unsafe dam should be classified as an emergency situation.

(vi) All inspection reports will receive one level of independent review by the Corps. If the reports are prepared by the Corps, the independent review may be performed internally within the district office. However, in cases which involve significant economic, social or political impacts and technical uncertainties in evaluating the dams, advice may be obtained from the staffs of the Division Engineer and the Office, Chief of Engineers.

(3) Reports— (i) Preparation. A written report on the condition of each dam should be prepared as soon as possible after the completion of the field inspection and assessment. A suggested report format is attached as Appendix E. It is important that the inspection report be completed in a timely manner. For inspections being done by Corps employees, it is suggested that once an inspection team has been assigned to a dam inspection it be allowed to complete the inspection and report without interruption by other work.

(ii) Review and approval. The coordinating engineer should determine which disciplines should review the report and establish a procedure to accomplish the review in a timely manner. A review panel, made up of the appropriate Division and Branch Chiefs has worked well in some districts. Use of a review panel should be seriously considered by all districts. All inspection reports shall be approved by the District Engineer who will maintain a complete file of final approved reports. Any State or Federal agency having jurisdiction over the dam or the land on which the dam is built should be given the opportunity to review and comment on the report prior to submission to the Governor or dam owner. The District Engineer will transmit final approved reports to the Governor of the State and the dam owner (or the Governor only, when requested in writing by State officials). If the report is initially furnished to the Governor only, a period of up to ten days may be allowed before the report is furnished to the dam owner. If the Governor or the owner indicates additional technical information is available that might affect the assessment of the dam's condition, the District Engineer will furnish the proposed final report to the Governor and the owner and establish a definite time period for comments to be furnished to the District Engineer prior to report approval.

(iii) In general the Governor will be responsible for public release of an inspection report and for initiating any public Statements. However, an approved report must be treated as any other document subject to release upon request under the Freedom of Information Act. The letters of transmittal to the Governor and owner should indicate that under the provisions of the Freedom of Information Act, the documents will be subject to release upon request after receipt by the Governor. Proposed final reports will be considered as internal working papers not subject to release under the Freedom of Information Act. Corps personnel, A-E contractor personnel and others working under supervision of the Corps will be cautioned to avoid public statements about the condition of the dam until after the District Engineer has approved the report. The Corps will respond fully to inquiries after the Governor has received the approved report or been notified of an unsafe dam. An information copy of the report should be sent to the District office normally having jurisdiction if other than the District responsible for the inspection.

(iv) Follow-up action. A Federal investment of the magnitude anticipated for this inspection program makes it desirable that a reporting system be established to keep the District Engineer abreast of the implementation of the recommendations in the inspection reports. The letters of transmittal to the Governor and owner will request that the District Engineer be informed of the actions taken on the recommendations in the inspection reports. However, the National Dam Inspection Act only authorizes the initial inspection of certain dams; therefore, once a report is completed no reinspection will be undertaken.

(4) Unsafe dams. The investigating engineer will be required to immediately notify the District Engineer when a dam is assessed as being unsafe. He will also indicate if probable failure of the unsafe dam is judged to be imminent and immediate action is required to reduce or eliminate the threat. The District Engineer will evaluate the findings of the investigating team and will immediately notify the Governor and the owner if the findings are Unsafe Non-Emergency or Unsafe-Emergency. The appropriate State agency and the Corps of Engineers officials having emergency operation responsibility for the area in which the dam is located will also be notified. The information provided in the unsafe dam notice shall be as indicated in Appendix F. Any emergency procedures or remedial actions deemed necessary by the District Engineer will be recommended to the Governor who has the responsibility for any corrective actions. As provided in ER 500-1-1, Corps assistance under Pub. L. 84-99 “Advance Measures,” may be made available to complement the owner's and Governor's action under certain conditions and subject to the approval of the Director of Civil Works. The District Engineer's Emergency Operation Officer will coordinate the advance measures request in accordance with existing procedures. Coordination will be maintained between the District responsible for emergency action under Pub. L. 84-90 and the District responsible for the inspection.

(5) Emergency action plans. An emergency action plan should be available for every dam in the high and significant hazard category. Such plans should outline actions to be taken by the operator to minimize downstream effects of an emergency and should include an effective warning system. If an emergency action plan has not been developed, the inspection report should recommend that the owner develop such an action plan. However, the Corps has no authority to require an emergency action plan.

(k) Progress reports. Progress reports should be submitted monthly by the Division Engineer to WRSC. The reports shall include progress through the last Saturday of the month and should be mailed by the following Monday. The reports shall contain the information and be typewritten in the format shown in Appendix G. Copies of Unsafe Dam Data Sheets will be submitted with the progress report. Copies of the completed inspection report for Dams in the Unsafe-Emergency category will be submitted also. (RCS-DAEN-CWE-19)

(l) Contracts— (1) Corps of Engineers supervision. Contracts for performing inventory and inspection activities under supervision of the Corps of Engineers shall be Fixed-Price Architect Engineer Contracts for Services. A sample scope of work setting forth requirements is provided in Appendix H. Experience has shown that costs for individual dam inspection have been lower when multiple inspections are included in one contract. Therefore, each A-E contract should include multiple dam inspections where practicable. Corps participation in A-E inspections should be held to a minimum. Corps representatives should participate in only enough A-E inspections to assure the equality of the inspections.

(2) State supervision. Contracts with States for performing inventory and inspection activities under State supervision may be either a Cost-Reimbursement type A-E Contract for Services or a Fixed-Price type contract. The selection of Architect-Engineers by the State should require approval of the Corps of Engineers Contracting Officer. The negotiated price for A-E services under cost-reimbursement type contracts with States will also require approval by the Contracting Officer. Contracts with States should require timely submission of the inspection reports to the District Engineer for review and approval. The contract provisions should also prevent public release of or public comment on the inspection report until the District Engineer has reviewed and approved the report. Corps of Engineers participation in State inspections should be limited to occasional selected inspections to assure the quality of the State program.

(m) Training. As indicated in paragraph (f) of this section, one objective of the inspection program for non-Federal Dams is to prepare the States to provide effective dam safety programs. In many States this will require training of personnel of State agencies in the technical aspects of dam inspections. The Office, Chief of Engineers is studying the need for and content of a comprehensive Corps-sponsored training program in dam inspection technology. Pending the possible adoption of such a comprehensive plan, division and district Engineers are encouraged to take advantage of suitable opportunities to provide needed training in dam safety activities to qualified employees of State agencies and, when appropriate, to employees of architect-engineer firms engaged in the program. The following general considerations should be observed in providing such training:

(1) Priority must be placed on inspection of dams and updating the national dam inventory; hence, diversion of resources to training activities should not deter or delay these principle program functions.

(2) Salaries, per diem and travel expenses relating to training activities of State employees will be a State expense. There will be no tuition charge for State employees.

(3) Architect-Engineer firms will be required to pay expenses and tuition costs for their employees participating in Corps-sponsored training activities.

(4) Corps-sponsored training will require that each trainee is a qualified engineer or geologist and will concentrate on engineering technology related directly to dam safety. (This may require screening of proposed candidates for training.)

(5) Under this program, the Corps will not sponsor training that is intended primarily to satisfy requirements for a degree.

(6) Training by participation in actual dam inspections and/or management of the inspection program should be encouraged.

Appendix A to § 222.6—Division Assignments

To facilitate better coordination with the States, the Division Engineers are responsible for the dam inspection program by States as follows:

New England Division: Maine, Rhode Island, Connecticut, Vermont, New Hampshire, Massachusetts

North Atlantic Division: New York, New Jersey, Pennsylvania, Delaware, Maryland, Virginia, District of Columbia

Ohio River Division: West Virginia, Ohio, Kentucky, Tennessee, Indiana

South Atlantic Division: North Carolina, South Carolina, Georgia, Florida, Alabama, Puerto Rico, Virgin Islands

Lower Mississippi Valley Division: Mississippi, Louisiana, Missouri

North Central Division: Michigan, Wisconsin, Illinois, Minnesota, Iowa

Southwestern Division: Arkansas, Oklahoma, Texas, New Mexico

Missouri River Division: Kansas, Nebraska, South Dakota, North Dakota, Wyoming, Colorado

North Pacific Division: Oregon, Idaho, Montana, Washington, Alaska

South Pacific Division: Utah, California, Arizona, Nevada

Pacific Ocean Division: Hawaii, Trust Territories, American Samoa

Appendix B to § 222.6—Inventory of Dams

(RCS-DAEN-CWE-17 and OMB No. 49-RO421)

1. The updating of the inventory will include the completion of all items of data for all dams now included in the inventory, verification of the data now included in the inventory, and inclusion of complete data for all appropriate existing dams not previously listed. Data completion, verification and updating will be scheduled over a three year period.

2. The inventory data will be recorded on Engineering Form 4474 and 4474A (Exhibit 2). The general instructions for completing the forms are printed on the back of the forms. Parts I and II of the forms are to be fully completed. The instruction for completing Item 29, Line 5, Para. II (Engr Form 4474A) is revised to conform identically with the hazard potential classification contained in the recommended guidelines for safety inspection of dams. Additional data has been added to designate Corps districts in which the dam is located, Federal agency owned dams, Corps owned dams, Federal agency regulated dams, dams constructed with technical or financial assistance of the U.S. Soil Conservation Service, and privately owned dams located on Federal property.

3. All inventory data will be verified utilizing all available sources of information and will include site visitation if required.

4. The Inventory Data Base is stored on the Boeing Computer Services (BCS) EKS System in Seattle, Washington. The data is available to all Corps offices for queries using Data Base Management System 2000 (S2K).

a. To access the National Data Base log on BCS and type the following:

GET,DAMS/UN=CECELB

CALL,DAMS

b. For current information and changes to the National Inventory Data Base, type:

OLD,HOTDAM/UN=CEC1AT

LIST

5. The inventory update data will be furnished and the National Data Base will be updated on a monthly basis. The monthly submission will cover all dams whose inventory data were completed since the last report. The update data will be loaded directly onto the Boeing Computer by the field office.

a. The procedure for loading the data on the Boeing Computer can be printed by accessing the Boeing Computer and listing the information file “HOTDAM.” (See paragraph 4b. above.)

b. It is the responsibility of the submitting office to edit the data prior to furnishing it for the update. Editing will be accomplished by processing the data using the Inventory Edit Computer program developed by the Kansas City District. This procedure is described in the “HOTDAM” file.

6. Federal agencies will be uniformly designated by major and minor abbreviations according to the following list whenever applicable to Items 46 through 53. Abbreviations are to be left justified within the field with one blank separating major and minor abbreviations.

7. Procedures for Revising and Updating the Inventory of Dams Master File.

a. To Change Correct or Add an Item. Submit a change card that contains the identification assigned to the dams (Columns 1 thru 7), the proper card code (Column 80) and only the item or items changed, corrected or added. Data on the master file is added or replaced on an item for item basis.

b. To Delete an Item. Submit a change card that contains the identification assigned to the dam, (Columns 1 thru 7), the proper card code (Column 80), and an asterisk (*) in the left most column of the item or items to be deleted. More than one item can be changed, corrected, added on or deleted from the same card.

c. To Delete the Entire Data for a Dam from the Master File. Submit a zero (0) card punched as follows:

Columns 1 thru 7—Item 1 identification assigned to the dam

Columns 8 thru 10—Item 2, Division Code

Columns 11 thru 16—The word DELETE

Columns 17 thru 79—Blank Spaces

Column 80—A zero

8. Keypunch Instructions and Punched Card Formats.

a. Table 1 describes the character set to be used for keypunch cards of Engr. Forms 4474 and 4474A.

b. Exhibit 1 is the EDPC keypunch instructions and punch card formats defining the data fields (Items) and card columns to be used in preparing punched cards in compliance with the requirements of this regulation.

c. Exhibit 2 are prints of Engr. Forms 4474 and 4474A which are laid out in punch card format to facilitate punching cards directly from the completed forms.

Code of Federal Regulations

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Appendix C to § 222.6—Hydrologic and Hydraulic Assessment of Dams

1. Phase I inspections are not intended to provide detailed hydrologic and hydraulic analyses of dam and reservoir capabilities. However, when such analyses are available, they should be evaluated for reliability and completeness. If a project's ability to pass the appropriate flood (see Table 3, page D-12 of Recommended Guidelines) can be determined from available information of a brief study, such an assessment should be made. It should be noted that hydrologic and hydraulic analyses connected with the Phase I inspections should be based on approximate methods or systematized computer programs that take minimal effort. The Hydrologic Engineering Center (HEC) has developed a special computer program for hydrologic and hydraulic analyses to be used with the Phase I inspection program. Other Field Operating Agencies have developed similar computer programs or generalized procedures which are acceptable for use. All such efforts should be completed with minimum resources.

2. A finding that a dam will not safely pass the flood indicated in the Recommended Guidelines does not necessarily indicate that the dam should be classified as unsafe. The degree of inadequacy of the spillway to pass the appropriate flood and the probable adverse impacts of dam failure because of overtopping must be considered in making such classification. The following criteria have been selected which indicate when spillway capacity is so seriously inadequate that a project must be classified as unsafe. All of the following conditions must prevail before designating a dam unsafe:

a. There is high hazard to loss of life from large flows downstream of the dam.

b. Dam failure resulting from overtopping would significantly increase the hazard to loss of life downstream from the dam from that which would exist just before overtopping failure.

c. The spillway is not capable of passing one-half of the probable maximum flood without overtopping the dam and causing failure.

3. The above criteria are generally adequate for evaluating most non-Federal dams. However, in a few cases the increased hazard potential from overtopping and failure is so great as to result in catastrophic consequences. In such cases, the evaluation of condition 2c should utilize a flood more closely approximating the full probable maximum flood rather than one-half the flood. An example of such a situation would be a large dam immediately above a highly populated flood plain, with little likelihood of time for evacuation in the event of an emergency.

4. Conditions 2a and 2b require an approximation of housing location in relation to flooded areas. Resources available in Phase I inspections do not permit detailed surveys or time-consuming studies to develop such relationships. Therefore, rough estimates will generally be made from data obtained during the inspection and from readily available maps and drawings. Brief computer routings such as the HEC-1 dam break analysis, using available data, are recommended in marginal cases. The HEC-1, dam break version, is available on the Boeing Computer Services or may be obtained from the Hydrologic Engineering Center, Davis, California. Available resources do not permit detailed studies or investigations to establish the amount of overtopping that would cause a dam to fail, as designated in condition 2c. Professional judgment and available information will have to be used in these determinations. When detailed investigations and studies are required to make a reasonable judgment of the conditions which designate an unsafe dam, the inspection report should recommend that such studies be the responsibility of the dam owner.

5. During the inspection of a dam, consideration should be given to impacts on other dams located downstream from the project being inspected. When failure of a dam would be likely to cause failure of another dam(s) downstream, its designation as an unsafe dam could result in multiple impacts. Therefore, the information should be explicitly described in the inspection report. Such information may be vital to the priorities established by State Governors for dam improvements. Similarly, when the failure of an upstream dam (classified as unsafe) could cause failure of the dam being inspected, this information should be prominently displayed in the inspection report.

6. The criteria established in paragraph 2 for designating unsafe dams because of seriously inadequate spillways are considered reasonable and prudent. They provide a consistent bases for declaring unsafe dams and also serve as an effective compromise between the Recommended Guidelines and unduly low standards suggested by special interests and individuals unfamiliar with flood hazard potential.

7. The Hydrometeorological Branch (HMB) of the National Weather Service has reviewed some 500 experienced large storms in the United States. The purpose of the review was to ascertain the relative magnitude of experienced large storms to probable maximum precipitation (PMP) and their distribution throughout the country. Their review reveals that about 25 percent of the major storms have exceeded 50 percent of the probable maximum precipitation for one or more combinations of area and duration. In fact some storms have very closely approximated the PMP values. Exhibits C-1 thru C-5 indicate locations where experienced storms have exceeded 50 percent of the PMP.

8. There are several options to consider when selecting mitigation measures to avoid severe consequences of a dam failure from overtopping. The following measures may be required by a Governor when sufficient legal authority is available under State laws and a dam presents a serious threat to loss of life.

a. Remove the dam.

b. Increase the height of dam and/or spillway size to pass the probable maximum flood without overtopping the dam.

c. Purchase downstream land that would be adversely impacted by dam failure and restrict human occupancy.

d. Enhance the stability of the dam to permit overtopping by the probable maximum flood without failure.

e. Provide a highly reliable flood warning system (generally does not prevent damage but avoids loss of life).

Table 1—Storms With Rainfall ≥150% of PMP, U.S. East of the 105th Meridian (for 10 mi2, 6 Hours; 200 mi2, 24 Hours and/or 1,000 mi2, 48 Hours)

Storm date	Index No.	Corps assignment No. (if available)	Storm center		Latitude	Longitude
Storm date	Index No.	Corps assignment No. (if available)	Town	State	Latitude	Longitude
July 26, 1819	1		Catskill	NY	42°12′	73°53′
Aug. 5, 1843	2		Concordville	PA	39°53′	75°32′
Sept. 10-13, 1878	3	OR 9-19	Jefferson	OH	41°45′	80°46′
Sept. 20-24, 1882	4	NA 1-3	Paterson	NJ	40°55′	74°10′
June 13-17, 1886	5	LMV 4-27	Alexandria	LA	31°19′	92°33′
June 27-July 11, 1899	6	GM 3-4	Turnersville	TX	30°52′	96°32′
Aug. 24-28, 1903	7	MR 1-10	Woodburn	IA	40°57′	93°35′
Oct. 7-11, 1903	8	GL 4-9	Paterson	NJ	40°55′	74°10′
July 18-23, 1909	9	UMV 1-11B	Ironwood	MI	46°27′	90°11′
July 18-23, 1909	10	UMV 1-11A	Beaulieu	MN	47°21′	95°48′
July 22-23, 1911	11		Disclaimer All information on our site are collected from Internet. Please contact us if any information is a violation of your rights, we will remove them from our site. You can send email to: zhongyuan@live.com. Copyright © 2010-2022 Laws-info.com \| All rights reserved. Tips

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222.6—National Program for Inspection of Non-Federal Dams.

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