| q1. What is a dam?
a1. A dam is any artificial dike,
levee or other barrier, together with appurtenant
works, which is constructed for the purpose
of impounding water on a permanent or temporary
basis, that raises the water level five feet
or more above the usual, mean, low water height
when measured from the downstream toe-of-dam
to the emergency spillway crest or, in the
absence of an emergency spillway, the top-of-dam.
See the graphical
demonstration of the definition of a dam.
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q2. How do I measure
dam height?
a2. Height of dam is the vertical
dimension when measured from either the invert
of the outlet pipe or, in the absence of an
outlet pipe, the lowest point in the stream
bed or ground surface at the downstream toe
of dam, whichever is lower, to the top-of-dam.
See the graphical
demonstration of the definition of a dam.
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q3. Do I need a permit
to work on my dam?
a3. If you are performing any work
outside of general maintenance (ie: light
vegetation removal, clearing of debris, and
filling of minor erosion and animal burrows)
that affects the physical structure or performance
of a dam, a permit from this office must be
obtained. If you are unsure of whether or
not a permit is required for the type of work
that you are planning, please contact this
office prior to commencement of the activities.
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q4. What kind of
permit do I need?
a4. A Dam
Construction Permit Application is required
for the following:
- Construction of a new dam.
Repair, modification or rehabilitation
of an existing dam.
- Removal of an existing dam.
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q5. What is required
for a permit for dam construction, repair
or rehabilitation?
a5. In addition to a completed Dam
Construction Permit Application, the requirements
of the New
Jersey Dam Safety Standards (N.J.A.C.
7:20-1.6 Sections a-c) and (N.J.A.C. 7:20-1.7
Sections a-g) Application Stages must be met.
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q6. What is required
for a permit for dam removal or decommissioning?
a6. In addition to a completed Dam
Construction Permit Application, the requirements
of the New
Jersey Dam Safety Standards (N.J.A.C.
7:20-1.7 Sections h-i) Application Stage must
be met.
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q7. What qualifies
as a Class IV dam?
a7. A Class IV Dam must meet the following:
- Drainage area must be less than 150 acres.
Dam Height must be less than 15 feet.
Dam must not have the potential to impound
more than 15 acre-feet of water.
Dam must pose Low Hazard potential.
- Spillway capacity must safely pass the
24-hour 100-year frequency Type III storm
plus 50 percent.
The complete definition of a Class IV dam
is listed in the New
Jersey Dam Safety Standards (N.J.A.C.
7:20-1.8 a-4). You may also see the graphical
demonstration of the definition of a dam.
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q8. Are trees allowed
on dams?
a8. No. Significant vegetation impedes
the inspection process and can hide serious
deficiencies that may be occurring at a dam.
Additionally, the root structure of trees
affects the structural integrity of the dam,
can cause seepage pathways for water through
the dam, and can cause significant section
loss if uprooted. Any one of these factors
alone can contribute to the failure of a dam.
For a complete listing of general requirements
and design criteria, please refer to the New
Jersey Dam Safety Standards (N.J.A.C.
7:20-1.4 and1.9).
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q9. Are dams in the
Pinelands area exempt from state statutes?
a9. The Safe Dam Act grants the Department
jurisdiction over dams within the pinelands
region that meet the following requirements:
dam height greater than eight (8) feet, reservoir
greater than 100 acres in area or contributing
drainage area exceeding 1 square mile. However,
the Department does not regulate any dam used
for agricultural purposes within the special
agricultural production area (SA) within the
pinelands region. Please contact this office
if you are unsure whether or not a dam meets
these specifications.
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q10. What do the
different classifications of dams mean?
a10. There are four hazard classifications
of dams in New Jersey. The classifications
relate to the potential for property damage
and/or loss of life should the dam fail:
- Class I (High-Hazard Potential) - Failure
of the dam may result in probable loss of
life and/or extensive property damage.
Class II (Significant-Hazard Potential)
- Failure of the dam may result in significant
property damage; however loss of life is
not envisioned.
Class III (Low-Hazard Potential) - Failure
of the dam is not expected to result in
loss of life and/or significant property
damage.
- Class IV (Small-Dam Low-Hazard Potential)
- Failure of the dam is not expected to
result in loss of life or significant property
damage. Dam must also meet the requirements
of a Class IV dam above.
For a complete descriptions of the Dam Classifications,
see the New
Jersey Dam Safety Standards (N.J.A.C.
7:20-1.8).
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q11. What is an
Emergency Action Plan (EAP)?
a11. The purpose of an EAP is to help
save lives and reduce property damage in the
event of a dam failure or other uncontrolled
release of water. An EAP is a formal document
that:
- Identifies Potential Emergency
Conditions and Specifies Pre-Planned Responses.
- Provides for Early Notification
to Local, County and State OEM Officials.
- Provides Inundation Mapping of
Potentially Flooded Areas.
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q12. What dams require
Emergency Action Plans (EAPs)?
a12. All Class I (High-Hazard Potential)
and Class II (Significant-Hazard Potential)
dams require Department-approved Emergency
Action Plans (EAPs). It is the responsibility
of the owner of the dam to review and update
the EAP annually. See the Guidelines
for Developing an Emergency Action Plan for additional information.
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q13. What are dam
inspections?
a13. Dam Safety Inspections are intended
to identify conditions that may adversely
affect the safety and functionality of a dam
and its appurtenant structures; to note the
extent of deterioration as a basis for long
term planning, periodic maintenance or immediate
repair; to evaluate conformity with current
design and construction practices; and to
determine the appropriateness of the existing
hazard classification. For addition information
regarding the different types of dam inspections
and a standard regular inspection checklist,
please see the Inspection
Guidelines.
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q14. How often are
dams required to be inspected?
a14. The inspection requirements depend
on the size and hazard classification of the
dam:
Dam
Size/Type |
Regular
Inspection |
Formal
Inspection |
| Class
I Large Dam |
annually |
once
every 3 years |
| Class
I Dam |
once
every 2 years |
once
every 6 years |
| Class
II Dam |
once
every 2 years |
once
every 10 years |
| Class
III Dam |
once
every 4 years |
only
as required |
| Class
IV Dam |
once
every 4 years |
only
as required |
For complete inspection and operating requirements
for dams, see the New
Jersey Dam Safety Standards (N.J.A.C.
7:20-1.11).
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q15. What is an
Operation and Maintenance Manual (O&M)?
a15. An Operation and Maintenance
Manual (O&M) is a formal document that
provides guidance and instruction to project
personnel for the proper operation and maintenance
of the reservoir and dam. All dam owners are
required to develop and use a Department-approved
O&M. For additional information regarding
the O&M, see the New
Jersey Dam Safety Standards (N.J.A.C.
7:20-1.11) and the Sample
Operation and Maintenance Manual.
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