Chapter 375: DETERMINATION OF THE SAFETY AND SUFFICIENCY OF A DAM OR RESERVOIR

SUMMARY: This Chapter describes the scope of a dam inspection, the engineering and hydrologic performance criteria that are used in the determination of whether a dam or reservoir is unsafe or insufficient, and the time schedule and hearing procedures that apply to dam and reservoir inspection.

1. Introduction

The determination of the "safety and sufficiency of a dam or reservoir" as defined in 38 M.R.S.A. § 811 shall be made pursuant to this rule. When a dam or reservoir is in addition found to be "unsafe or dangerous to the lives or property of persons residing, carrying on business, or employed near or below the same" (§812), the inspector of Dam shall recommend alterations, repairs and additions to the dam or reservoir for the protection of life and property. These include but are not limited to recommendations that the reservoir level be lowered in a safe manner, that structural repairs or additions be made to the dam or reservoir, that certain operating procedures be adopted or implemented, or that the dam or reservoir be removed. Failure of the dam owner to comply with these recommendations may result in court action as described in 38 M.R.S.A. §812.

2. Scope of Dam inspection

A. The inspector of Dam shall make a safety assessment of a given dam or reservoir with a degree of thoroughness appropriate for the particular facility, taking into account such factors as:

a. consequences of a total failure of the facility b. stage of life of the project c. level of safety required d. nature of the facility and its site

The Inspector of Dam shall first make the appropriate determination of the level of consequences of a complete failure of the dam or reservoir. He shall then determine appropriate criteria for the performance of the facility. Next, he shall make a site inspection in which he searches for any field evidence of possible malfunctions of the facility. During or following the site inspection, the Inspector of Dam shall obtain any available documents on the investigation, design, construction, and performance of the dam.

B Following such site inspection, the Inspector of Dams shall take the testimony of witnesses concerning the safety and sufficiency of the dam or reservoir as provided in 38 M.R.S.A. § 811 and according to the procedure for the conduct of hearings contained in 01-019 CMR ch. 30.4 and .5. For purposes of this chapter, unless the content otherwise indicates, all references to "The Chairman of the Soil and Water Conservation Commission" and "The

Commission" which appear in 01-019 CMR ch. 30.4 and .5 shall be deemed to refer to the Inspector of Dams.

3. Decision

A. Following the determination of the consequences of failure, the site inspection and hearing, and appropriate analyses, the Inspector of Dams shall forthwith report his findings and his opinion of the safety and sufficiency of the dam or reservoir to the Commissioner of the Department of Agriculture, Conservation and Forestry. Pursuant to 38 M.R.S.A. §812, said findings and opinion shall include the Inspector's conclusion as to whether or not such dam or reservoir is unsafe or dangerous to the lives or property of persons residing, carrying on business or employed near or below the same.

B. Such findings and opinion shall simultaneously be mailed to a representative of the petitioners, any intervenors, and the owners of the dam or reservoir. Within fourteen days of their receipt of such findings and opinion, these parties may file with the Inspector proposed findings, written comments, statements and arguments thereon. In the discretion of the inspector, additional time may be granted if the dam or reservoir owner desires to commission, at his own expense, an additional safety assessment of the dam or reservoir. Such request must be made within fourteen days of receipt of the Inspector's findings and opinion. Title 01-019 CMR ch. 30.5M shall apply to these proceedings as modified by the procedures set forth herein.

C. Upon the expiration of the comment period or the Inspector's receipt of an additional safety assessment, as the case may be, the record shall be closed (subject to 01-019 CMR ch. 30.5N). The Inspector shall thereupon issue a final report to the Commissioner of Agriculture, Conservation and Forestry. In the case of finding a dam to be unsafe, or insufficient, the Commissioner shall notify all interested parties, including owners with riparian rights, municipalities in which the dams are located and any other persons or organizations he deems necessary.

4. Definition of "Unsafe and Insufficient"

A dam or reservoir shall be declared to be "unsafe" or "insufficient" if the Inspector of Dams, after utilizing all available data and testimony and making appropriate calculations using known values or reasonable assumptions, finds that the dam or reservoir does not meet minimum performance criteria appropriate to the facility. The types of performance features that should be evaluated are listed below:

A. Forces acting on the dam and evidence of horizontal translation that suggests there is too much force acting at any time against the facility;

B. Evidence of large total or differential deformation;

C. Evidence of slumps or bulges on the faces of the dam; an end-of-construction or steady state factor of safety against shear sliding and the factor of safety under conditions of reservoir drawdown and during appropriate earthquake loading;

D. Evidence that the phreatic surface within the dam during the full reservoir condition exists

on the downstream face of the dam except through properly designed drains; evidence of bulges, seeps, or soft zones on the downstream face of the dam or on the immediate abutments; evaluation of the effective stress within the dam;

1. E. Evidence that the dam is experiencing internal erosion of dam material or that the dam abutments or foundation could be subject to piping; an evaluation of internal drain design; an evaluation of seepage gradient within the dam;
2. F. An evaluation of the quantity and quality of seepage through the dam
3. G. An evaluation of whether a dam or reservoir is safe from runoff overtopping that could wash out the containment structure. In making this evaluation, the inspector shall consider whether the dam can safely sustain overtopping by the appropriate design storm, and if not, whether an emergency spillway is present. In appropriate cases where it is determined that an emergency spillway should be present, and only one spillway exists, the principal spillway may be considered to serve as an emergency spillway, provided that the principal spillway is large enough so that it cannot be blocked by driftwood and other floating or suspended debris. For each class of structure identified in paragraphs (1), (2) and (3), the inspector shall consider whether an emergency spillway is able to transmit without erosion, or whether the dam can retain its integrity during overtopping, a storm of the frequency specified
4. (1) For class 'a' structures, which are located in rural, agricultural, or urban areas dedicated to remain in flood tolerant usages where failure may only damage non-residential buildings, agricultural land, floodplains, or township and country roads: 25-year storm or flood;
5. (2) For Class 'b' structures, which are located in predominantly rural or agricultural areas where failure may damage homes, industrial or commercial buildings, highways or railroads, or where failure may cause interruption of use or service of utilities: 100-year storm or flood;
6. (3) For Class 'c' structures, where failure may cause loss of life: maximum probable flood.
7. H. An evaluation of the minimum freeboard during the reservoir levels that will prevail during the appropriate design storm or flood described in sub-section G above; in a reservoir where landsliding of earth or rack into the reservoir is possible, the potential for wave generation and wave run-up on the dam;
8. I. Evidence of holes or burrows that could render the dam unsafe;
9. J. Consequences of inappropriate dam placement;
10. K. An earthdam shall not be covered by brush, shrubs, or trees;
11. L. The mechanical facilities that provide control of the water levels in a reservoir shall be in good working order.

5. Qualifications in Declaring a Dam Safe

The Inspector of Dam shall declare a dam or reservoir 'safe' if he finds no evidence that the dam or reservoir is unsafe during his field inspection or through his calculations of the safety based upon reasonable assumptions. In a case where the Inspector is of the opinion that there are insufficient field measurements or other data to verify definitively that certain safety criteria have been met (such as described in section 3, Sub-sections A through L), then the Inspector of Dam may declare a dam or reservoir safe subject to further specific studies which he shall recommend to the dam owner. The Inspector may also declare a dam safe subject to review by the Inspector at some later date.

STATUTORY AUTHORITY:

38 M.R.S.A. '811 et seq.; 5 M.R.S.A. '8051; Batterton v. Francis, 432 U.S. 416, 424, n. 9 (1976), General Electric Co. v. Gilbert, 429 U.S. 141-45 (1976), and Skidmore v. Swift & Co., 323 U.S. 134, 14 (1944), as to the inherent authority of an agency to promulgate interpretative regulations as opposed to regulations having the force of law. See also 2 Davis, Administrative Law '7.9 et seq. (2d ed. 1979).

EFFECTIVE DATE:

June 30, 1981

EFFECTIVE DATE (ELECTRONIC CONVERSION):

May 4, 1996

CONVERTED TO MS WORD:

May 20, 2008

CORRECTIONS:

February, 2014 – agency names, formatting