Code of Massachusetts Regulations › 302 CMR - DEPARTMENT OF CONSERVATION AND RECREATION › Title 302 CMR 10.00 - Dam Safety › Section 10.14 - Design and Construction Criteria for New and Existing Dams

Current through Register 1525, July 5, 2024
(1)
General
. Design
			 and construction of dams shall comply with 302 CMR 10.14. Design and
			 construction standards that are not included in 302 CMR 10.14, shall conform to
			 design procedures established by: The U.S Army Corps of Engineers, the U.S.
			 Bureau of Reclamation, the U.S. Natural Resources Conservation Service and
			 other generally accepted engineering practices and principles. Where specific
			 site conditions may exist which warrant appropriate changes in the following
			 design and construction criteria, the Commissioner shall review and approve the
			 design.
(2)
Foundations
			 and Abutments
. The foundations and abutments investigation shall
			 consist of borings, test pits, and other subsurface exploration necessary to
			 assess the soil, rock, and groundwater conditions.
(3)
Construction
			 Materials
. Specifications for construction materials shall
			 establish minimum acceptance criteria so that anticipated design properties are
			 achieved. If the use of onsite borrow materials is specified, exploration,
			 testing, and calculations shall be performed to indicate that there are
			 sufficient quantities of material available that meet the design
			 criteria.
(4)
Surveys
. Surveys shall be made with sufficient
			 accuracy and scale to locate the proposed construction and to define the volume
			 of the storage in the reservoir. The downstream area shall be investigated in
			 order to delineate the area of potential damage in case of failure. Locations
			 of centerlines, and other horizontal and vertical control points, shall be
			 shown on a map of the site.
(5)
Hydrologic Investigation
. The drainage area shall be
			 determined. Present land use shall be considered in determining the runoff
			 characteristics of the drainage area. All hydrologic assumptions and design
			 calculations shall be included in the report.
(6)
Spillway Design
.
(a) The spillway system shall have a capacity
			 to pass a flow resulting from a design storm, as indicated in the following
			 table, unless the applicant provides calculations, designs and plans to show
			 that the design flow can be stored, passed through, or passed over the dam
			 without failure occurring.
SPILLWAY DESIGN FLOOD DESIGN STORM
Hazard Potential
Size
Existing Dams
New Dams
Low
small
50 year
100 year
intermediate
50 year
100 year
large
100 year
100 year
Significant
small
100 year
500 year
intermediate
100 year
500 year
large
500 year
½ PMF
High
small
500 year
PMF
intermediate
½ PMF
PMF
large
½ PMF
PMF
(b)
			 Vegetated earth or unlined emergency spillway(s) will be approved when
			 computations indicate that it will pass the design flood without jeopardizing
			 the safety of the structure. The risk of recurring storms, excessive erosion,
			 and inadequate vegetative cover will be considered acceptable in such a
			 spillway when its average frequency of use is predicted to be no more than
			 indicated in the following table.
EMERGENCY SPILLWAY FREQUENCY TABLE
Hazard Potential
Size
Existing Dams
New Dams
Low
small
25 years
25 years
intermediate
25 years
25 years
large
25 years
25 years
Significant
small
25 years
50 years
intermediate
25 years
50 years
large
50 years
50 years
High
small
50 years
100 years
intermediate
50 years
100 years
large
100 years
100 years
(c)
			 The Department recognizes that the relationships between valley slope and
			 width, total reservoir storage, drainage area, and other hydrologic factors
			 have a critical bearing on determining the safe spillway design flood. Rational
			 selection of a safe spillway design flood for specific site conditions based on
			 quantitative and relative impact analysis is acceptable. The spillway may be
			 sized so that the increased downstream damage resulting from an overtopping
			 failure of the dam
(i.e.,
the selected spillway design
			 capacity has been exceeded) would not be significant when as compared with the
			 damage caused by the flood in the absence of dam overtopping failure. In
lieu
of quantitative and relative impact analysis, the
			 preceding table shall be used as spillway design criteria.
(d)
Lined Spillways and
			 Channels
. The design report shall include design data criteria for
			 open channel, drop, ogee, and chute spillways and other spillway types that
			 include crest structures, walls, channel linings, and miscellaneous details.
			 All masonry or concrete structures shall have joints that are relatively water
			 tight and shall be placed on foundations capable of sustaining applied loads
			 without undue deformation. Provisions must be made for handling leakage from
			 the channel or under seepage from the foundation which might cause saturation
			 of underlying materials or uplift against the undersurfaces.