A.
The purpose of the Floodplain Overlay District is to:
(1)
Ensure public safety through reducing the threats to life and personal injury;
(2)
Eliminate new hazards to emergency response officials;
(3)
Prevent the occurrence of public emergencies resulting from water quality, contamination, and pollution due to flooding;
(4)
Avoid the loss of utility services which if damaged by flooding would disrupt or shut down the utility network and impact regions of the community beyond the site of flooding;
(5)
Eliminate costs associated with the response and cleanup of flooding conditions; and
(6)
Reduce damage to public and private property resulting from flooding waters.
B.
Definitions.
(1)
National Flood Insurance Program (NFIP) definitions are found in Title 44 of the Code of Federal Regulations, section 59.1. The definitions below refer to their source; if the definition is from the MA building code, it is from the 9th Edition, which meets the minimum standards of the NFIP.
(2)
In order for the bylaw or ordinance to be clearly understood, it is necessary to define technical terms or key words. An understanding of these terms is a prerequisite to effective administration of the floodplain management bylaw or ordinance.
(3) DEVELOPMENT FLOOD BOUNDARY AND FLOODWAY MAP FLOOD HAZARD BOUNDARY MAP (FHBM.) FLOODWAY FUNCTIONALLY DEPENDENT USE HIGHEST ADJACENT GRADE HISTORIC STRUCTURE(a) (b) (c) (d) NEW CONSTRUCTION RECREATIONAL VEHICLE(a) (b) (c) (d) REGULATORY FLOODWAY SPECIAL FLOOD HAZARD AREA START OF CONSTRUCTION
STRUCTURE SUBSTANTIAL REPAIR OF A FOUNDATION VARIANCE VIOLATION
Per FEMA Region I, these additional definitions must be included in local bylaws or ordinances.
Any man-made change to improved or unimproved real estate, including but not limited to building or other structures, mining, dredging, filling, grading, paving, excavation or drilling operations or storage of equipment or materials. [US Code of Federal Regulations, Title 44, Part 59]
An official map of a community issued by FEMA that depicts, based on detailed analyses, the boundaries of the 100-year and 500-year floods and the 100-year floodway. (For maps done in 1987 and later, the floodway designation is included on the FIRM.)
An official map of a community issued by the Federal Insurance Administrator, where the boundaries of the flood and related erosion areas having special hazards have been designated as Zone A or E. [US Code of Federal Regulations, Title 44, Part 59]
The channel of the river, creek or other watercourse and the adjacent land areas that must be reserved in order to discharge the base flood without cumulatively increasing the water surface elevation more than a designated height. [Base Code, Chapter 2, Section 202]
A use which cannot perform its intended purpose unless it is located or carried out in close proximity to water. The term includes only docking facilities, port facilities that are necessary for the loading and unloading of cargo or passengers, and ship building and ship repair facilities, but does not include long-term storage or related manufacturing facilities. [US Code of Federal Regulations, Title 44, Part 59] Also [Referenced Standard ASCE 24-14]
The highest natural elevation of the ground surface prior to construction next to the proposed walls of a structure. [US Code of Federal Regulations, Title 44, Part 59]
Any structure that is:
Listed individually in the National Register of Historic Places (a listing maintained by the Department of Interior) or preliminarily determined by the Secretary of the Interior as meeting the requirements for individual listing on the National Register;
Certified or preliminarily determined by the Secretary of the Interior as contributing to the historical significance of a registered historic district or a district preliminarily determined by the Secretary to qualify as a registered historic district;
Individually listed on a state inventory of historic places in states with historic preservation programs which have been approved by the Secretary of the Interior; or
Individually listed on a local inventory of historic places in communities with historic preservation programs that have been certified either:
Structures for which the start of construction commenced on or after the effective date of the first floodplain management code, regulation, ordinance, or standard adopted by the authority having jurisdiction, including any subsequent improvements to such structures. New construction includes work determined to be substantial improvement. [Referenced Standard ASCE 24-14]
A vehicle which is:
Built on a single chassis;
400 square feet or less when measured at the largest horizontal projection;
Designed to be self-propelled or permanently towable by a light duty truck; and
Designed primarily not for use as a permanent dwelling but as temporary living quarters for recreational, camping, travel, or seasonal use. [US Code of Federal Regulations, Title 44, Part 59]
See FLOODWAY.
The land area subject to flood hazards and shown on a Flood Insurance Rate Map or other flood hazard map as Zone A, AE, A1-30, A99, AR, AO, AH, V, VO, VE or V1-30. [Base Code, Chapter 2, Section 202]
The date of issuance for new construction and substantial improvements to existing structures, provided the actual start of construction, repair, reconstruction, rehabilitation, addition, placement or other improvement is within 180 days after the date of issuance. The actual start of construction means the first placement of permanent construction of a building (including a manufactured home) on a site, such as the pouring of a slab or footings, installation of pilings or construction of columns.
Permanent construction does not include land preparation (such as clearing, excavation, grading or filling), the installation of streets or walkways, excavation for a basement, footings, piers or foundations, the erection of temporary forms or the installation of accessory buildings such as garages or sheds not occupied as dwelling units or not part of the main building. For a substantial improvement, the actual "start of construction" means the first alteration of any wall, ceiling, floor or other structural part of a building, whether or not that alteration affects the external dimensions of the building. [Base Code, Chapter 2, Section 202] |
Means, for floodplain management purposes, a walled and roofed building, including a gas or liquid storage tank, that is principally above ground, as well as a manufactured home. [US Code of Federal Regulations, Title 44, Part 59]
When work to repair or replace a foundation results in the repair or replacement of a portion of the foundation with a perimeter along the base of the foundation that equals or exceeds 50% of the perimeter of the base of the foundation measured in linear feet, or repair or replacement of 50% of the piles, columns or piers of a pile, column or pier supported foundation, the building official shall determine it to be substantial repair of a foundation. Applications determined by the building official to constitute substantial repair of a foundation shall require all existing portions of the entire building or structure to meet the requirements of 780 CMR. [As amended by MA in 9th Edition BC]
A grant of relief by a community from the terms of a flood plain management regulation. [US Code of Federal Regulations, Title 44, Part 59]
The failure of a structure or other development to be fully compliant with the community's flood plain management regulations. A structure or other development without the elevation certificate, other certifications, or other evidence of compliance required in § 60.3(b)(5), (c)(4), (c)(10), (d)(3), (e)(2), (e)(4), or (e)(5) is presumed to be in violation until such time as that documentation is provided. [US Code of Federal Regulations, Title 44, Part 59]
C.
Applicability. The Flood Plain Overlay District is herein established as an overlay district. The District includes all special flood hazard areas in the Town of Dedham designated as Zones A and AE on the Norfolk County Flood Insurance Rate Map (FIRM), dated July 8, 2025, issued by the Federal Emergency Management Agency (FEMA) for the administration of the National Flood Insurance Program (NFIP). The exact boundaries of the District are defined by the 100-year base flood elevations shown on the FIRM and further defined by the Norfolk County Flood Insurance Study report dated July 8, 2025. The FIRM and Flood Insurance Study report is incorporated herein by reference and are on file with the Town Clerk, Planning Board, Building Department, and Conservation Commission.
D.
Abrogation and Greater Restriction. The floodplain management regulations found in this Floodplain Overlay District section shall take precedence over any less restrictive conflicting local laws, ordinances or codes.
E.
Disclaimer of Liability. The degree of flood protection required by this bylaw is considered reasonable but does not imply total flood protection.
F.
Severability. If any section, provision or portion of this bylaw [ordinance] is deemed to be unconstitutional or invalid by a court, the remainder of the ordinance shall be effective.
G.
Designation of Community Floodplain Administrator. The Town of Dedham hereby designates the position of Building Commissioner to be the official floodplain administrator for the Town.
H.
Requirement to Submit New Technical Data. If the Town acquires data that changes the base flood elevation in the FEMA mapped Special Flood Hazard Areas, the Town will, within six months, notify FEMA of these changes by submitting the technical or scientific data that supports the change(s.) Notification shall be submitted to:
FEMA Region I Risk Analysis Branch Chief |
And copy of notification to: |
Massachusetts NFIP State Coordinator MA Dept. of Conservation & Recreation |
I.
Variances to Building Code Floodplain Standards. The Town/City will request from the State Building Code Appeals Board a written and/or audible copy of the portion of the hearing related to the variance, and will maintain this record in the community's files.
The Town/City shall also issue a letter to the property owner regarding potential impacts to the annual premiums for the flood insurance policy covering that property, in writing over the signature of a community official that (i) the issuance of a variance to construct a structure below the base flood level will result in increased premium rates for flood insurance up to amounts as high as $25 for $100 of insurance coverage and (ii) such construction below the base flood level increases risks to life and property.
Such notification shall be maintained with the record of all variance actions for the referenced development in the floodplain overlay district.
J.
Variances to Local Zoning Bylaws Related to Community Compliance with the National Flood Insurance Program (NFIP). A variance from these floodplain Bylaws must meet the requirements set out by State law, and may only be granted if:
K.
Permits are Required for all Proposed Development in the Floodplain Overlay District. The Town of Dedham requires a permit for all proposed construction or other development in the floodplain overlay district, including new construction or changes to existing buildings, placement of manufactured homes, placement of agricultural facilities, fences, sheds, storage facilities or drilling, mining, paving and any other development that might increase flooding or adversely impact flood risks to other properties.
L.
Assure that all Necessary Permits are Obtained. The Town of Dedham's permit review process includes the use of a checklist of all local, state and federal permits that will be necessary in order to carry out the proposed development in the floodplain overlay district. The proponent must acquire all necessary permits, and must submit the completed checklist demonstrating that all necessary permits have been acquired.
M.
Unnumbered A Zones. In A Zones, in the absence of FEMA BFE data and floodway data, the building department will obtain, review and reasonably utilize base flood elevation and floodway data available from a Federal, State, or other source as criteria for requiring new construction, substantial improvements, or other development in Zone A as the basis for elevating residential structures to or above base flood level, for floodproofing or elevating nonresidential structures to or above base flood level, and for prohibiting encroachments in floodways.
N.
Floodway Encroachment. In Zones A and AE, along watercourses that have not had a regulatory floodway designated, the best available Federal, State, local, or other floodway data shall be used to prohibit encroachments in floodways which would result in any increase in flood levels within the community during the occurrence of the base flood discharge.
In Zones A1-30 and AE, along watercourses that have a regulatory floodway designated on the Norfolk County FIRM, encroachments are prohibited, including fill, new construction, substantial improvements, and other development within the adopted regulatory floodway unless it has been demonstrated through hydrologic and hydraulic analyses performed in accordance with standard engineering practice that the proposed encroachment would not result in any increase in flood levels within the community during the occurrence of the base flood discharge.
O.
Recreational Vehicles. In A and AE Zones, all recreational vehicles to be placed on a site must be elevated and anchored in accordance with the zone's regulations for foundation and elevation requirements or be on the site for less than 180 consecutive days or be fully licensed and highway ready.
P.
Reference to existing regulations. The FPOD is established as an overlay district to all other districts. All development in the district, including structural and nonstructural activities, whether permitted by right or by special permit must be in compliance with Chapter 131, Section 40 of the Massachusetts General Laws and with the following:
Q.
Procedures. Any work within a FPOD shall require a Special Permit issued by the Board of Appeals. Notice of each such Flood Plain special permit application shall be given to the Town Public Works Department, to the Town Administrator, the Board of Selectmen, the Board of Health, the Planning Board, and the Conservation Commission, as well as all other parties deemed necessary by the Board of Appeals.
(1)
The Board of Appeals, in hearing such application, shall consider, in addition to any other factors said Board deems pertinent, the following aspects with respect to flooding and FPOD zoning provisions; that any such building or structure shall be designed, placed, and constructed to offer a minimum obstruction of the flow of water; and that it shall be firmly anchored to prevent floating away.
R.
Base flood elevation data. Base flood elevation data is required for subdivision proposals or other developments greater than 10 lots or 2.5 acres, whichever is lesser, within unnumbered A zones.
S.
Watercourse alteration and relocation. In cases where a project will alter or relocate a watercourse, the following must be notified:
T.
Review of all project proposals. All projects shall be reviewed to assure the following:
U.
Permitted uses. The following activities are permitted within the FPOD upon receipt of a building permit, where required:
(1)
Development for recreational purposes, including but not limited to: walking trails and bicycle paths, athletic fields, parks, beaches, and boat landings.
(2)
Horticultural and Agricultural purposes, including those associated with commercial farming.
(3)
Construction of a structure provided that the following criteria are met:
(a)
Structure shall not be utilized for residential purposes.
(b)
The lowest floor of the structure shall be located at least one foot above the 100-year flood elevation for the site as noted on the FEMA map referenced above.
(c)
The structure shall not impede the flow of flood waters.
(d)
Volumetric flood compensation at a ratio of 2:1 for every cubic foot of fill, structure, or other obstructions placed within the Flood Plain District. Calculations prepared by a Professional Engineer licensed by the Commonwealth of Massachusetts shall be submitted to the Board of Appeals as part of the permit application.
(e)
Any structure shall have direct pedestrian access to uplands area located outside of the FPOD. Such access shall be reviewed and approved by the Dedham Fire and Police Departments.
(f)
Any public works projects, including but not limited to: drainage, sewerage, or flood control project, including any associated structures.
V.
Prohibited uses. The following uses are prohibited within a FPOD:
(1)
No land fill or dumping in any part of the District without proper volumetric compensation at a ratio of 2:1 for every cubic foot filled. This includes fill utilized for landscaping purposes.
(2)
No damming or relocation of any water course except as part of an overall drainage basin plan proposed by a public authority.
(3)
No permanent outside storage of materials or equipment. This includes storage of materials for retail sale.
(4)
No land, building, or structure shall be used for sustained human occupancy except dwellings theretofore lawfully existing, or land, buildings, or structures which comply with the provisions of this Bylaw.
(5)
Storage of fertilizers, chemicals, or manure associated with agricultural uses.
(6)
Motor vehicle storage, sales, or maintenance facilities. This includes parking areas designated for temporary storage of vehicles awaiting repairs or unregistered vehicles, whether stored or for sale.
(7)
Underground storage tanks other than storage or septic tanks associated with a subsurface disposal system or sewerage pumping station.
(8)
Storage of any chemical or material classified as hazardous by Local, State, or Federal statutes and regulations.
W.
Portion of parcel within FPOD. The above prohibitions will only apply to the portion of a parcel which is located within a FPOD, and not the entire parcel.
X.
Federal flood insurance program.
(1)
The Federal Flood Insurance Rate Map (FIRM) shall be, for purposes of administration of and conformity with the requirements of the Federal Flood Insurance Program, placed on file with the Town Clerk and Building Inspector, and shall be considered an appendix to this Bylaw.
(2)
Until such time as a regulatory floodway is designated, no new construction, substantial improvements, or other development (including fill) shall be permitted within Zones A and AE on the FIRM unless it is demonstrated that the cumulative effect of the proposed development, when combined with all other existing and anticipated development, will not increase the water surface elevation of the base flood at any point within the community or along the regulated section of the waterway.
(3)
Where a specific area or parcel of land appears on the FIRM as being within the 100-year flood elevation and an applicant, having satisfied the intent of Subsection L(2) above, wishes to seek relief from the placement of the area or parcel within a flood hazard zone, or a release from the mandatory purchase of flood insurance, said applicant shall follow the procedures contained in a Letter of Map Amendment as outlined in Title 44 of the Code of Federal Regulations (CFR), Part 70.