Code of Massachusetts Regulations
302 CMR - DEPARTMENT OF CONSERVATION AND RECREATION
Title 302 CMR 10.00 - Dam Safety
Section 10.03 - Definitions
In addition to M.G.L. c. 253, § 44 as used in 302 CMR 10.00, the following terms shall have the following meanings:
(1) Undefined Terms. As used in 302 CMR 10.00 any term not defined in accordance with 302 CMR 10.03 shall have the meaning given to the term by any statutes, regulations, executive orders or policy directives governing the subject matter of the term. Examples include terms pertaining to:
(a) Wetlands, which is defined by the Wetlands Protection Act, M.G.L. c. 131, § 40, and its implementing regulations, 310 CMR 10.00: Wetlands Protection, and 33 USC 1341 and 314 CMR 9.00: 401 Water Quality Certification for Discharge of Dredged or Fill Material, Dredging, and Dredged Material Disposal in Waters of the United States Within the Commonwealth regarding Water Quality Certification, as well as other statutes, regulations, executive orders, or policy directives that govern wetlands issues; and
(b) Roadways or traffic, which are defined by the Massachusetts Highway Department's Highway Access Policy (adopted September 17,1991), its Standard Operating Procedure for Review of State Highway Access permits (adopted September 17,1991), and the Guidelines for EIR/EIS Traffic Impact Assessment (1989, as amended) by the Massachusetts Department of Transportation and the Executive Office of Energy and Environmental Affairs, as well as other statutes, regulations, executive orders or policy directives that govern roadway and traffic issues.
(2) Defined Terms. As used in 302 CMR 10.00, the following terms shall have the following meanings:
Abutment. That part of a valley side against which a dam is constructed. An artificial abutment is sometimes constructed as a concrete gravity section, to take the thrust of an arch dam where there is no suitable natural abutment. Right and left abutments are those on respective sides of an observer looking downstream.
Acre-foot. A unit of volumetric measure that would cover one acre to a depth of one foot. It is equal to 43,560 cubic feet. One million U.S. gallons = 3.068 acre foot.
Applicant. Any person making application for a dam safety permit.
Appurtenant Works. Structures, either in dams or separate therefrom, including, but not limited to, spillways; reservoirs and their rims; low level outlet works; and water conduits, including tunnels, pipelines or penstocks, either through the dams or their abutments.
Artificial Impoundment. As applied to dam safety, a reservoir created by a dam.
As-builts. Plans, drawings and all other descriptive and factual information that depict how a dam was actually constructed or repaired. As-builts are required to be submitted to the Commissioner at dam completion.
Axis of Dam. A plane or curved surface, arbitrarily chosen by a designer, appearing as a line in a plan or cross section to which the horizontal dimensions of the dam can be referred.
Baffle Block. A block, usually of concrete, constructed in a channel or stilling basin to dissipate the energy of water flowing at high velocity.
Base Width (Base Thickness). The maximum width or thickness of a dam measured horizontally between upstream and downstream faces and normal to the axis of the dam but excluding projections for outlets, etc.
Beaver Dams. Dams that are constructed by beavers and not subject to 302 CMR 10.00. Control of beaver population and removal of beaver dams is regulated by M.G.L. c. 131, 321 CMR 2.00: Miscellaneous Regulations Relating to Fisheries and Wildlife, and also by the Local Boards of Health and Conservation Commissions.
Berm. A horizontal step or bench in the sloping profile of an embankment dam.
Boil. A disturbance in the surface layer of soil caused by water escaping under pressure from behind a water retaining structure such as dam or a dike. The boil may be accompanied by the deposit of soil particles (usually sand) in the form of a ring (miniature volcano) around the area where the water escapes.
Certificate of Completion. A document signed and stamped by a registered professional engineer with contractor's signature and supporting as-builts, upon completion of the work, attesting that the work has been performed in accordance with the design plans and specifications and permit conditions.
Certificate of Compliance. When a dam has been evaluated, constructed, repaired, altered or removed to the satisfaction of the Commissioner under a properly issued permit, the Commissioner shall issue a certificate of compliance, on a form prescribed by the Commissioner, to the owner certifying that the permitted construction project has been completed in accordance with the plans and specifications and any requirement set forth by the Commissioner. Such certificate shall be recorded by the owner in the registry of deeds in the county where the dam lies. Issuance of such Certificate of Compliance shall release the dam owner from the requirements of the Certificate of Non-compliance.
Certificate of Non-compliance. A certificate issued by the Commissioner when a dam or appurtenant features are in poor or unsafe condition with identified structural deficiencies. Such certificate shall be recorded by the Commissioner in the registry of deeds in the county where the dam lies.
Cofferdam. A temporary structure enclosing all or part of a construction area so that construction can proceed in a dry area. A "diversion cofferdam" diverts a river into a pipe, channel or tunnel.
Commissioner. The Commissioner of the Department of Conservation and Recreation or his or her authorized designee.
Conduit. A closed channel for conveying discharge through or under a dam.
Crib Dam. A gravity dam built up of boxes, cribs, crossed timbers, or gabions and filled with earth or rock.
Culvert. A drain or waterway built transversely under a road, railway, or embankment, usually consisting of a pipe or covered channel of box section. It includes a gallery or waterway constructed through any type of dam, which is normally dry but is used occasionally for discharging water, hence the terms "scour culvert", "draw-off culvert", and "spillway culvert". A roadway or railway culvert may not be considered a dam if its invert is at the natural bed of the water course, it has adequate discharge capacity, and it does not impound water under normal circumstances. A culvert with an installed man made water control device which impounds, releases, or diverts water may be designated by the Commissioner as a dam.
Cutoff Wall. An impervious construction or material which reduces seepage or prevents it from passing through foundation material.
Dam Any artificial barrier, including appurtenant works, which impounds or diverts water, and which:
(a) is 25 feet or more in height from the natural bed of the stream or watercourse measured at the downstream toe of the barrier, or from the lowest elevation of the outside limit of the barrier, if it is not across a stream channel or watercourse, to the maximum water storage elevation; or
(b) has an impounding capacity at maximum water storage elevation of 50 acre feet or more. Any other artificial barrier, including appurtenant works, the breaching of which could endanger property or safety, may be designated by the Commissioner as a dam, and shall be subject to M.G.L. c. 21, § 65 and c. 253, §§ 44 through 48.
Dam shall not mean any of the following:
1. any appurtenant works which temporarily impounds or diverts water used on land in agricultural use as defined pursuant to M.G.L. c. 131, § 40;
2. any barrier or appurtenant works which has a size classification of small or low hazard potential classification that is used on land in agricultural use as defined in M.G.L. c. 131, §40; and
3. any barrier which is not in excess of six feet in height, regardless of storage capacity, or which has a storage capacity at maximum water storage elevation not in excess of 15 acre feet, regardless of height.
The Commissioner shall make such determination by taking into consideration factors such as height, type of structure, condition of structure, volume of the impoundment, extent of development downstream, and other factors deemed appropriate by the Commissioner.
Dam Breach. An eroded or failed section opening through a dam which drains the impoundment. A controlled breach is a design and constructed opening. An uncontrolled breach is an unintentional opening which allows uncontrolled discharge from the impoundment.
Dam Break Analysis. A determination of a flood hydrograph, resulting flood levels and inundation area resulting from a dam breach.
Dam Certificate of Registration. A certificate to be issued by the Commissioner to the dam owner following completion and submittal by the dam owner of the dam registration form.
Dam Failure. A collapse of an impounding structure resulting in an uncontrolled release of impounded water from a dam.
Dam Inspection Form or Format. A form or forms prescribed by the Commissioner containing information relative to the present condition, safety and adequacy of the dam and such other information as the Commissioner may require by regulation, signed by a registered professional engineer and filed with the Department.
Dams Not Regulated by M.G.L. c. 253, §§ 44 through 48. Dams constructed by beavers, created by ice, debris, etc. and any other non-man-made structures.
Dam Registration Form. A form or forms to be provided by the Commissioner to be prepared by the owner and filed with the Commissioner containing the name of the owner, the location and the dimensions of the dam and such other information as the Commissioner may require by regulation.
Dam Safety Engineer. A person who is employed by the department who meets the requirements established by the Department of Personnel Administration.
Database. An electronic database of detailed information about dams. The database is owned, compiled, maintained and distributed by the Commissioner. Requests for database information are subject to M.G.L. c. 4, § 7, clause twenty-sixth (n) (Public Records) until suspended.
DEP. The Department of Environmental Protection.
Department or DCR. The Department of Conservation and Recreation, as established in M.G.L. c. 21 § 1.
Drainage Area. The area which drains to a particular point on a river or stream.
Drawdown. The lowering of water surface level due to loss of water from a reservoir.
Embankment. The fill material, usually earth or rock, placed with sloping sides which provide a permanent barrier which impounds water.
Emergency Condition. Unsafe dams with highest risk of failure, requiring immediate attention and a predetermined plan of action to reduce the highest level of risk, for the protection of public safety.
Emergency Action Plan. A predetermined plan of action to be taken to reduce the potential for property damage and/or loss of life in an area affected by an impending dam break.
Engineer/Design Engineer. See Registered Professional Engineer.
Factor of Safety. As applied to dam safety, the ratio of the forces or moments resisting mass movement to the forces or moments tending to produce mass movement.
Fees. As applied to dam safety, the cost of services listed under 801 CMR 4.02: Fees for Licenses, Permits, and Services to be Charged by State Agencies (302 CMR: Department of Conservation and Recreation) and provided by the Department.
Flashboards. A length of timber, concrete, or steel placed on the crest of a spillway or other hydraulic control structure to raise the retention water level but that may be quickly removed in the event of a flood either by a tripping device or by a deliberately designed failure of the flashboard or its supports.
Flood Hydrograph. A graphical representation of the flood discharge and/or stage with respect to time for a particular point on a stream or river.
Flow Net. A graphical representation of families of streamlines and equipotential lines, used in groundwater studies to determine quantities, rate, and directions of flow.
Freeboard. The vertical distance between a stated water level and the top of a dam. Net freeboard, dry freeboard, flood freeboard or residual freeboard are measured by the vertical distance between the spillway design flood water level and the top of a dam.
Gravity Dam. A dam constructed of concrete and/or masonry that relies on its weight for stability.
Great Pond. A pond containing in its natural state more than ten acres of land, as defined in 310 CMR 9.02: Definitions.
Great Pond/Enlarged. As applied to dam safety, any change in or addition to an existing Great Pond which raises, or may raise, the normal water level of the water impounded by a Great Pond, by construction of a dam.
Hazard Potential Classification. The rating for a dam based on the potential consequences of failure. The rating is based on potential for loss of life and damage to property that failure of that dam could cause downstream of the dam. The hazard potential classification for a dam has no relationship to the current structural integrity, operational status, flood routing capability, or safety condition of the dam or its appurtenances.
Height of Dam. The vertical distance from the elevation of the dam crest to the lowest point of natural ground, including any stream channel, along the downstream toe of the dam.
Hydraulic and Hydrologic (H&H) Analyses. The analytical process of computing the inflow and outflow from the dam under normal and flood conditions. Such analysis determines normal and maximum reservoir levels, outflows and spillway design and freeboard requirements.
Hydraulic Height. The height to which water is normally retained behind a dam above the lowest point of natural ground, including any stream channel along the downstream toe of the dam.
Inspections.
(a) Additional Required Inspection means an additional inspection by a registered professional engineer of the dam, in accordance with the inspection frequency established by the Commissioner, to detect apparent signs and changes of deterioration in material, developing weaknesses or unsafe hydraulic and/or structural behavior or any other deficiencies of the dam structure or function since the initial Phase I or poor/unsatisfactory condition was determined. The additional inspection report shall follow a form as established by the Commissioner.
(b) Follow-up Inspection means an inspection of dams determined to be in poor or unsafe condition with structural deficiencies performed on a frequency determined by the Commissioner, or as otherwise required for any dam at any time. The Follow-up Inspection report shall follow a form as established by the Commissioner.
(c) Phase I Formal Inspection means the formal visual inspection of the dam, in accordance with the inspection frequency established by, at a minimum, M.G.L. c. 21, § 65, or by the Commissioner, by a registered professional civil engineer to evaluate or reevaluate the safety and integrity of the dam and appurtenant structures to determine if the structure appears to meet current design criteria. Formal inspection includes field observations to detect any signs of deterioration in material, seepage, developing weaknesses or unsafe hydraulic and/or structural conditions and a review of the records on project design, construction and performance. The Phase I Formal Inspection shall determine the overall dam condition. The final Phase I Formal Inspection report shall follow a form or format as established by the Commissioner and shall be filed with the Office of Dam Safety.
(d) Phase II Detailed Inspection means all studies, investigations and analyses ordered by the Commissioner to evaluate the structural stability and hydraulic capacity of a dam or reservoir and appurtenant works. This inspection may include, but is not limited to, updated visual inspection, structural stability analyses, detailed hydrologic/hydraulic assessment, dam breach analyses, subsurface investigation, soil and materials testing, foundation explorations, conclusions, conceptual alternatives, cost estimate and recommendations. This inspection shall be performed by a registered professional civil engineer.
(e) VIF (Verification In Field) Jurisdictional Determination Inspection means an inspection to collect pertinent and sufficient information pertaining to a dam to determine if the Commissioner has a basis for claiming statutory and regulatory jurisdiction of a dam.
Instrumentation. An arrangement of devices installed into or near dams (i.e. piezometers, inclinometers, strain gages, measurement points, seepage measuring devices, etc.) which provide for measurements that can be used to evaluate the structural behavior and performance parameters of the structure.
Inundation Map. A map delineating the area that would be flooded by a particular flood event or dam failure.
Liability. Legal liability associated with the ownership, operation, maintenance, repair and failure of a dam.
Lien. A notice for the payment by the owner of a dam to the Commonwealth of the costs and expenses incurred by the Commonwealth for any actions taken in accordance with M.G.L. c. 253, § 47 and shall be effective upon mailing to the owner at the address shown in the Certificate of Registration and recorded at the Registry of Deeds in the county where the dam lies.
Low Level Outlet (Pond Drain). An installed pipe and operable gate or valve that can be utilized to alter water levels, empty an impoundment, or otherwise meet operational or safety needs.
Materially Alter. Any change to a dam or reservoir which affects the physical parameters and/or safety of the dam or reservoir which may include, but is not limited to, changing the height of a dam, increasing the normal pool or spillway elevation or changing the elevation or physical dimensions of an emergency spillway.
Maximum Impoundment Elevation. The maximum water surface elevation which can be contained by the dam without overtopping the embankment section.
Maximum Water Storage Elevation. The water surface elevation reached during the spillway design flood, which could be below the top of the dam or above the top of the dam.
Normal Water Level. The water surface elevation that is maintained by the dam owner under normal operating conditions.
Office of Dam Safety (OPS). The office of the Department of Conservation and Recreation, composed of technical and administrative staff responsible for administering the Commonwealth's Dam Safety Law and Regulations.
One-hundred-year Storm Event. A storm which is estimated to have a 1% chance of occurrence in any year, or a one in 100 chance of being equaled or exceeded in one year.
Operation and Maintenance Manual (O&MM). A document identifying routine maintenance and operational procedures under routine and storm conditions.
Order. A written document prepared and issued by the Commissioner which mandates specific actions to be accomplished by a dam owner within a specified time frame. Failure to comply with an order shall make the owner subject to fines as provided for in 302 CMR 10.15.
Orientation.
(a) Upstream means the side of the dam that borders the reservoir;
(b) Downstream means the side opposite the upstream side;
(c) Right means the area to the right when the viewer is looking downstream; and
(d) Left means the area to the left when the viewer is looking downstream.
Owner. The person or persons, including any individual, firm, partnership, association, syndicate, company, trust corporation, municipality, agency, political or administrative subdivision of the commonwealth or any other legal entity of any kind holding legal title to a dam, but excluding the United States, its agencies or any person who operates a dam owned by the United States.
Permit or Chapter 253 Dam Safety Permit. A written approval, pursuant to M.G.L. c. 253, §§ 44 through 48, to construct, repair, alter, breach or remove a dam. The technical aspect of the Permit must be reviewed and confirmed complete by an Office of Dam Safety Engineer.
Phreatic Surface. The free surface of groundwater at atmospheric pressure.
Piezometer. As applied to dam safety, an instrument used for measuring water pressure within soil, rock or concrete.
Piping. The progressive development of internal erosion by seepage, appearing downstream as a hole or seam discharging water that contains soil particles.
Poor Condition Dam. A dam whose condition, as determined by the Commissioner, presents a significant risk to public safety located downstream from the dam. Among the deficiencies that may result in this determination are: significant seepage or piping, significant woody vegetation and tree growth on embankments and areas immediately adjacent to the dam and appurtenances, significant erosion or subsidence conditions, significant sink holes, significant sloughing of embankment, significant deficient flood routing spillway capacity and/or condition of outlet(s), significant movement or cracking of structural elements and other significant structural deficiencies.
Probable Maximum Flood (PMF). The most severe flood that is considered reasonably possible at a site as a result of the most severe combination of critical meteorological and hydrologic conditions possible in the region. PMFs are based on National Oceanic and Atmospheric Administration (NOAA) Probable Maximum Precipitation Estimates published in Hydrometerological Report No. 51 and applicable NOAA guidance documents.
Registered Professional Engineer. In the context of dam engineering, means a civil engineer licensed and registered in the Commonwealth of Massachusetts with experience in dam safety inspections and engineering.
Removal. The physical removal or engineered breaching of a dam to the extent that no water can be impounded by the dam.
Repairs means any work done at a dam which affects the integrity of the dam. This includes, but is not limited to, work requiring excavation into the embankment fill or foundation of a dam or work requiring removal or replacement of major structural components of a dam.
Reservoir. The area which contains or will contain the body of water impounded by a dam.
Riprap. A layer or layers of sufficiently large uncoursed stones, broken rock, or pre-cast blocks placed in random fashion on the upstream or downstream slope of an embankment dam, on a reservoir shore, on the sides of a channel or other elements of a dam to provide protection from erosion expected to be caused by wave action, freeze thaw cycles, flowing water or other erosive forces. Riprap is sometimes referred to as armoring.
Risk. A measure of the likelihood and severity of adverse consequences. In dam safety applications, life-safety risk is expressed in units of loss-of-lives per year; economic, societal and environmental risks are expressed in units of dollars per year. The risk may be associated with an individual failure mode or it may be total risk, representing the cumulative risk associated with all failure modes.
Risk Assessment. As applied to dam safety, the process of identifying the likelihood and consequences of dam failure to provide the basis for informed decisions on a course of action.
Roll Dams. Low head dams usually run-of-the-river overflow weir or spillway structures that produce vertical water surface drops of one to 15 feet and change river flows from super-critical to sub-critical.
Run-of-the-river-dam. A dam situated on a river or stream whose spillway length and width of impoundment is nearly equal to the width of the original river or stream bank to bank and likely having minimal storage available for flood attenuation.
Safety Evaluation. As applied to dam safety, the process of determining the ability of a dam and its appurtenances to pass a given flood.
Seepage. The interstitial movement of water that may take place through a dam, its foundation, or its abutments.
Siphon/Inverted. A conduit or culvert to permit water to pass under an intersecting roadway, stream or other obstruction.
Spillway. A structure over or through which non-storm related and flood flows are discharged. If the flow is controlled by gates or other works of control, it is a controlled spillway; if the elevation of the spillway crest is the only control, it is an uncontrolled spillway.
Spillway/Auxiliary or Emergency Spillway. A secondary spillway designed to operate only during flood events that exceed the principal spillway capacity or operate in tandem with the principal spillway.
Spillway(s) Design Flood (SDF). The flood used in the design of a dam and its appurtenant works particularly for sizing the spillway(s) and outlet works, and for determining maximum temporary storage and height of dam requirements.
Stoplogs. Logs, timbers, steel or alloy beams placed on top of each other with their ends held in guides on each side of a channel or conduit to control water level in reservoir.
Tailwater Level. As applied to dam safety, the level of water in the discharge channel immediately downstream of the dam. Tailwater levels can be those levels that result from normal to flood flow (SDF) conditions.
Toe of Dam. The junction of the downstream face of a dam with the ground surface, also referred to as downstream toe. For an embankment dam, the junction of the upstream face with ground surface is called the upstream toe.
Unsafe Condition Dam. A dam whose condition, as determined by the Commissioner, is such that a high risk of failure exists and the dam condition presents a high risk to public safety located downstream from the dam. Among the deficiencies that may result in this determination are: severe seepage or piping, severe woody vegetation and tree growth on embankments and areas immediately adjacent to the dam and appurtenances, severe erosion or subsidence conditions, severe sink holes, severe sloughing of embankment, severely deficient flood routing spillway capacity and/or condition of outlet(s), severe movement and/or severe cracking of structural elements and other severe structural deficiencies.
Uplift. As applied to dam safety, the upward pressure in the pores of a material (interstitial pressure) or on the base of a structure.
Weir. A barrier installed in an open channel stream or constructed waterway used for measuring and/or controlling the flow of water. Types of weir include broad crested weir, sharp-crested weir, ogee weir, and V-notched weir.
