Code of Massachusetts Regulations › 302 CMR - DEPARTMENT OF CONSERVATION AND RECREATION › Title 302 CMR 10.00 - Dam Safety › Section 10.06 - Size and Hazard Potential Classification

Current through Register 1525, July 5, 2024
(1)
General
. Dams
			 shall be classified for purposes of establishing inspection schedules and
			 adherence to design criteria, in accordance with their potential for damage to
			 life or property in the area downstream from the dam in the event of failure of
			 the dam or appurtenant facilities. This determination shall be made by the
			 Commissioner and noted on the owner's Certificate of Registration. It may be
			 necessary to periodically reclassify dams as additional information becomes
			 available and/or conditions change. The criteria established in 302 CMR
			 10.06(2) through (4) shall be used by the Commissioner to determine the size
			 and hazard potential classification based upon the extent of development
			 downstream from the dam, taking into consideration factors such as height, type
			 of structure and volume of impoundment, pursuant to M.G.L. c. 253.
(2)
Size
			 Classification
. The classification for size based on the height of
			 the dam and storage capacity shall be in accordance with 302 CMR 10.06(2):
Size Classification Table.
The height of the dam is
			 established as described in 302 CMR 10.06 with respect to maximum water storage
			 elevation. The storage capacity of the dam is the volume of water contained in
			 the impoundment at maximum water storage elevation measured as defined in 302
			 CMR 10.06(2). Size class may be determined by either storage or height,
			 whichever gives the larger size classification.
SIZE CLASSIFICATION TABLE
Category
Storage (acre-feet)
Height (feet)
Non-jurisdictional*
Not in excess of 15 regardless of height
Not in excess of six regardless of storage
							 capacity
Small
>= 15 and <50
>= 6 and <15
Intermediate
>= 50 and <1000
>= 15 and <40
Large
>= 1000
>= 40
*For dams not in excess of 6 feet in height or having
							 maximum impounding capacity not in excess of 15 acre-feet, the Commissioner
							 shall make jurisdictional determination by taking into consideration factors or
							 combination of factors such as height, type of structure, volume of the
							 impoundment, extent of downstream development, and other factors deemed
							 appropriate by the Commissioner.
(3)
Hazard Potential Classification
. The classification
			 for hazard potential shall be in accordance with 302 CMR 10.06(3):
Hazard Potential Classification Table.
The hazards pertain to
			 potential loss of human life or property damage in the event of failure of the
			 dam or appurtenant works. Development of the area downstream from the dam that
			 would be affected by its failure shall be considered in determining the
			 classification. Dams will be subject to reclassification if the Commissioner
			 determines the hazard potential has changed.
HAZARD POTENTIAL CLASSIFICATION TABLE
High Hazard Potential (Class I)
Dams located where failure will likely cause loss of
							 life and serious damage to home(s), industrial or commercial facilities,
							 important public utilities, main highway(s) or railroad(s).
Significant Hazard Potential (Class II)
Dams located where failure may cause loss of life and
							 damage to home(s), industrial or commercial facilities, secondary highway(s) or
							 railroad(s) or cause interruption of use or service of relatively important
							 facilities.
Low Hazard Potential (Class HI)
Dams located where failure may cause minimal property
							 damage to others. Loss of life is not expected.
(4)
Dams in Series
. If an upstream dam failure has the
			 capability to create failure of a downstream dam because of its failure flood
			 wave, it shall have the same or higher hazard potential classification as the
			 downstream dam. If the failure flood wave of the upstream dam will not cause
			 failure of the downstream dam, the upstream dam may have a different hazard
			 potential classification from the downstream dam.
(5)
Failure Damage
.
			 The extent of potential damage resulting from a dam breach may justify
			 designating damage as either major or minor.
(a) Such a designation may be made after a
			 detailed analysis has established the relative impact of the probable dam
			 breach and has considered the following factors:
1. the conditions prior to and after a dam
			 breach;
2. the extent to which
			 access has been affected, both before and after a dam breach; and
3. the extent of damage.