 This image shows the construction of a house elevated with two feet of freeboard next to a pre-FIRM home in Beach Haven West, New Jersey.
Source: FEMA Mitigation Assessment Team Report - Hurricane Sandy in New Jersey and New York (FEMA P-942)
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Welcome to the winter edition of the Floodplain Communicator, published by New Jersey’s National Flood Insurance Program Coordinator’s Office! If you have not already, please do update your subscribers preferences page and answer the questions in our survey. This will help us provide you with information tailored to your interests or location. Since the last edition, there was an opportunity for four free information sessions on dam removal (if you are interested, the recordings can be found here). We were able to send this targeted information to the subscribers who indicated interest in this topic. This opportunity has since passed, but don’t miss out on future opportunities or announcements! Follow this link to update your subscriber preferences page.
In this edition
New model ordinances are now available on the DEP Bureau of Flood Engineering website. These new models represent a departure from the past model ordinances. Previously, models were based upon specific National Flood Insurance Program floodplain characteristics and did not integrate with the two Statewide floodplain management regulations: the Uniform Construction Code and the NJ Flood Hazard Area Control Act. In the past, the DEP had six models (A, B, C, D, D&E, and E) but now there are two: Coastal and Riverine. NFIP communities with any coastal flood hazard should adopt Coastal ordinances and the remaining communities should adopt Riverine ordinances. These ordinances are compliant with the Flood Hazard Area Control Act and encourage coordination with the Construction Official where the NFIP and Uniform Construction Code regulations overlap.
This change in models comes after a recent FEMA review identified gaps in the previous models. It also implements a FEMA recommendation contained in the Post-Sandy Mitigation Assessment Team Report for New York and New Jersey to adopt a model code coordinated ordinance that was under joint development with the International Code Council at the time. Of greatest concern to FEMA was that, during Compliance Assistance Contacts with local floodplain administrators, it became evident that development (including nonstructural development such as filling, grading, excavations, fences, pools, temporary structures, etc.) was occurring in some communities that did not meet Statewide minimum standards as is required by 44 CFR 60.1(d). FEMA also has identified floodplain permitting as a weakness in many NFIP communities. It is anticipated that clearer direction in these new ordinances will guide communities in establishing a floodplain permitting program that is compliant with all State and Federal laws which is separate from the Uniform Construction Code construction permit process.
The DEP will assist all 552 NFIP participating municipalities to transition over to code coordinated ordinances. The DEP and FEMA are looking to give priority to communities that have not yet implemented 1-foot of freeboard in their ordinances, are receiving Letters of Final Determinations from FEMA for effective map adoption or have been identified as having NFIP compliance issues.
The model ordinances are available on the DEP website along with supplemental documents including reference tables cross referencing underlying regulations and an adoption worksheet.
Model Ordinance Information Sessions
The DEP will be offering two virtual information sessions on the new Model Code Coordinated Ordinances. These sessions will be held on March 4th and March 11th at 2pm. Please fill out this survey to register. Invitations to the virtual information sessions will be sent out the day before the scheduled event. One Continuing Education Credit will be offered for Certified Floodplain Managers.
An additional information session will be held on Friday March 19th during the New Jersey Association for Floodplain Management webinar at 12pm. This course will offer one Continuing Education Credit for Certified Floodplain Managers and one Professional Development Hour credit. In order to attend this information session you must be a member of the New Jersey Association for Floodplain Management. Memberships cost $30 and you can follow this link to become a member. If you are a member and would like to attend this session, please follow this link to register.
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The new model code coordinated ordinances refer to the Local Design Flood Elevation. This terminology is not present in the National Flood Insurance Program regulations, Flood Hazard Area Control Act or the Uniform Construction Code. Some readers may ask why new terminology is necessary. The answer is that each of these regulations refers to slightly different terminology (see definitions in Table 1 below) for specifying the lowest floor (or lowest horizontal structural member) but it falls to the local Floodplain Administrator to navigate these regulations to ensure that all minimum regulatory requirements are observed when constructing buildings and structures and observing requirements for residential and critical buildings. The NFIP regulations are considered “minimum requirements”, however, in 44 CFR 60.1(d), it states that “any flood plain management regulations adopted by a State or a community which are more restrictive than the criteria … shall take precedence.” This means that in New Jersey, the use of best available data and the addition of one foot of freeboard to determine design flood elevation for the lowest floor is a minimum requirement that often exceeds the NFIP minimum Base Flood Elevations. A further discussion of this methodology and the means for adding additional freeboard is discussed in the section Flood Hazard Area Control Act Methodology for Determining the Flood Hazard Design Flood Elevation, below.
Additionally, ASCE 24-14 Building Classes III and IV require either additional freeboard on top of the State minimums or that the structure be built to the 500-year flood elevation, whichever is more restrictive. It should also be noted that some communities have adopted ordinances with even higher freeboard requirements than the State that would also have to be considered. Therefore, defining a new term, the Local Design Flood Elevation, clarifies that this is the final decision of the Floodplain Administrator after considering all State, Federal, and local data and permitting as required by 44 CFR 60.3 and 60.3(a)2.
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TABLE 1: Distinguishing Between Flood Elevation Terminology in New Jersey
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Regulation
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Terminology |
How Determined? |
Freeboard |
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NFIP
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Base Flood Elevation (BFE)
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BFE’s are specified in FEMA mapping products. Often “BFE” is preceded by “preliminary”, “advisory”, or “effective” to denote which BFE is referred to when there are more than one map issued for an area and the elevations are not equivalent.
Note: When preliminary maps are issued by FEMA, the Floodplain Administrator must choose the more restrictive Base Flood Elevation and more restrictive flood zone when comparing effective and preliminary mapping. This avoids increased insurance premium costs and possible flood damage for property owners when preliminary mapping becomes the effective map.
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No freeboard is required under the NFIP regulations.
However, in riverine areas, regulating to the BFE without adding freeboard to designate a structure’s lowest floor (or lowest horizontal structural member in a V or Coastal A zone) results in a lower elevation than is required by the State’s Flood Hazard Area Control Act and the State’s Uniform Construction Code Design Flood Elevation (DFE).
In tidal areas, the BFE is equivalent to the Flood Hazard Area Control Act Design Flood Elevation (FHDFE) but regulating to this elevation would not meet the State’s Flood Hazard Area Control Act or the State Uniform Construction Code freeboard requirements for structures.
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Flood Hazard Area Control Act
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Flood Hazard Design Flood Elevation (FHDFE)
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The FHDFE is determined using the best available flood hazard data plus an additional factor of safety depending upon the calculation methodology found in N.J.A.C. 7:13-3. A more specific discussion of these determinations is given in Table 2.
Floodplain Administrators must consider the most recent best available data in developing the FHDFE. This may include:
- The FEMA Effective Map Base Flood Elevation
- Any FEMA Preliminary Map Base Flood Elevation
- Any work maps, Advisory Base Flood Elevations, Flood Insurance Study data
- Any State-studied Stream Elevations
Then, the Floodplain Administrator must choose the most restrictive flood zone and elevation.
If there is no base flood elevation because a watercourse hasn’t been studied in a watershed which is 50 acres or greater, Flood Hazard Area Control Act Rules provide guidance for calculation in NJAC 7:13-3.5 and 3.6.
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Freeboard for the lowest floor (or lowest horizontal structural member) elevation is addressed in N.J.A.C. 7:13-12.5 and is added for habitable structures regulated through individual permits, general permits, permits-by-rule, and general permits-by-certification.
In riverine areas, the lowest floor elevation is the greater of one foot or the freeboard dependent upon the structure’s ASCE 24 building class.
In tidal areas, the lowest floor elevation (or lowest horizontal structural member elevation in a V or Coastal A zone) is the greater of one foot or the freeboard required dependent upon the structure’s ASCE 24 building class and whether it is located in a Coastal A or V Zone.
Freeboard requirements for lowest floor elevations are identical to those required by the Uniform Construction Code.
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Uniform Construction Code (UCC)
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Design Flood Elevation (DFE)
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The UCC DFE is equivalent to the higher of the FHDFE or the Local Design Flood Elevation (exclusive of any freeboard added by local ordinance) because elevation decisions made in permits pursuant to the Flood Hazard Area Control Act or local ordinances are considered “prior approvals” by the UCC.
In riverine areas, FEMA BFE’s are not equivalent to the FHDFE so they are also not equivalent to the DFE in these areas. See Table 2, Method 3, below for more information.
In tidal areas, the best available most recent flood hazard data FEMA has provided is evaluated as part of the calculation of the FHDFE. Because of the appealed 2014 Preliminary Coastal mapping which will be in effect until it is replaced in 2024, this review must include a review of FEMA preliminary mapping and any adopted advisory base flood map products which differ from FEMA’s effective BFEs. Floodplain Administrators and Construction Officials should not assume that FEMA’s effective BFE is equivalent to the State’s minimum elevation in tidal areas without doing a comparison of the mapping. Because this evaluation of best available data has to occur every time a flood elevation is calculated, tidal base flood elevations are considered design flood elevations instead of base flood elevations to avoid confusion with any FEMA BFE that is lower than the FHDFE required by the Flood Hazard Area Control Act.
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Freeboard is discussed in Chapters 2 (Basic Requirements for Flood Hazard Areas that are not identified as Coastal High Hazard Areas and Coastal A Zones) and 4 (Coastal High Hazards and Coastal A Zones).
In areas which are not in V Zones or Coastal A Zones:
- Flood Design Class I, II, and III structures must be elevated 1 foot above the DFE.
- Flood Design Class IV structures must have the lowest floor elevated either 2 feet above the DFE or elevated to the 500-year flood elevation, whichever is higher.
In areas which are in V Zones and Coastal A Zones:
- Flood Design Class I and II structures must be elevated 1 foot above the DFE.
- Flood Design Class III structures must be elevated either 2 feet above the DFE or elevated to the 500-year flood elevation, whichever is higher.
- Flood Design Class IV structures must be elevated either 3 feet above the DFE or elevated to the 500-year flood elevation, whichever is higher.
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Local Model Code Coordinated Ordinance
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Local Design Flood Elevation (LDFE)
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Because of the NFIP precedence rule (44 CFR 60.1(d)) requiring that higher State standards be encouraged and take precedence, LDFEs must, at a minimum, be equivalent to the FHDFE.
NFIP participating communities may also adopt more restrictive flood mapping pursuant to ASCE24-14 -1.3 for regulatory purposes as described in C1.3 provided that any LDFEs specified by these maps meets or exceeds the FHDFE and are adopted and referenced in the community’s Flood Damage Prevention Ordinance.
Some communities also regulate to the 2013 FEMA Advisory Base Flood Elevations, which have been superseded by more recent flood insurance data (the 2014 Preliminary FEMA Coastal mapping). In communities where these were adopted by local ordinance, advisory base flood elevations and flood zones must also be compared to the FHDFE, with the most restrictive elevation and zone selected as the LDFE.
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The LDFE ensures that the most restrictive freeboard specified by the Flood Hazard Area Control Act and the Uniform Construction Code regulations are followed and adds any additional local freeboard specified by the Flood Damage Prevention Ordinance.
Some communities in New Jersey, especially some receiving Nation Flood Insurance Program Community Rating System insurance discounts, have ordinances adding up to 3-feet of freeboard.
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Understanding how Flood Hazard Design Flood Elevations are developed is important for Floodplain Administrators to ensure that Local Design Flood Elevations are compliant with State law. The Flood Hazard Area Control Act Rules specify six methods for calculating Flood Hazard Area Design Flood Elevations and considering the best available flood hazard data in State flood hazard permits.
Table 2 below distinguishes between these methodologies. As required by the Flood Hazard Area Control Act Rules, the most restrictive elevation should be chosen when there is available mapping or calculated using Methods 5 or 6 where mapping is not available. If a State regulated activity has not received a Flood Hazard Design Flood Elevation Verification Letter, a local Floodplain Administrator may require that the applicant apply for one as part of the prior-approval process.
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Table 2 Determining the New Jersey Flood Hazard Design Flood Elevation and Lowest Floor Requirements
Note: Local Design Flood Elevations shall be no lower than the Flood Hazard Design Flood Elevation
| Method Number |
Rule Citation |
Mapping Source |
Appropriate Use to determine the Flood Hazard Design Flood Elevation |
Determining Lowest Floor Requirements for a habitable building. Freeboard and final lowest floor elevation must be no lower than required by Uniform Construction Code Rules? ** |
| 1 |
NJAC 7:13-3.3 & Appendix 2 |
State (Department) Studied Watercourses determined based upon 125% of the 100-year flow rate |
Mapped riverine areas specified in Appendix 2 of N.J.A.C. 7:13 |
The greater of one foot or the freeboard dependent upon the Uniform Construction Code building class |
| 2 |
NJAC 7:13-3.4 |
FEMA Mapping* in Tidal areas |
A flood profile must exist with a 100-year elevation |
The greater of one foot or the freeboard required dependent upon the Uniform Construction Code building class and if the structure is located in a Coastal A or V Zone |
| 3 |
NJAC 7:13-3.4 |
FEMA Mapping* in Fluvial Areas |
A flood profile must exist with a 100-year elevation. One foot of elevation is added to define the Flood Hazard Design Flood Elevation when using this method |
The greater of one foot or the freeboard dependent upon the Uniform Construction Code building class |
| 4 |
NJAC 7:13-3.4 |
FEMA Hydraulic Method (for determining a floodway when FEMA has not mapped one) * |
A 100-year flow rate is provided for the regulated water AND hydraulic analysis such as a standard step backwater analysis comparing pre- and post-construction water elevations is performed using either 125% in a fluvial area or 100% in a tidal area of the 100-year flow rate |
The greater of one foot or the freeboard dependent upon the Uniform Construction Code building class and if the structure is located in a Coastal A or V Zone. |
| 5 |
NJAC 7:13-3.5 and Appendix 1 |
Area determined by Approximation |
Calculation is dependent upon Watershed Management Area and Drainage Basin size according to the map and table provided in Appendix 1 of N.J.A.C. 7:13 |
The greater of one foot or the freeboard dependent upon the Uniform Construction Code building class |
| 6 |
NJAC 7:13-3.6 |
Area determined by Calculation |
Base flood flow used in calculations is 125% of the 100-year flow rate the applicant calculates |
The greater of one foot or the freeboard dependent upon the Uniform Construction Code building class |
* FEMA flood mapping is defined in NJAC 7:13-1.2 and includes the information adopted as part of the most recent effective flood insurance study , dated on or after January 31, 1980, or any more recent advisory or proposed (preliminary) mapping, if the more recent advisory or proposed (preliminary) mapping results in higher elevations, wider floodway limits, or greater flow rates than depicted in the most recent effective FEMA flood insurance study or indicates a change from an A zone to a V zone or Coastal A zone.
** For the purposes of this column, one foot of freeboard is considered. If the permitted use is a Class III or Class IV use, additional freeboard will be added when the Flood Hazard Area Control Act permit is issued. Prior to issuance of a local Flood Damage Prevention permit, the Floodplain Administrator must review all Flood Hazard Area Control Act permits for changes in use (i.e. from a Class II apartment complex to a Class III assisted living facility). If this has occurred, the Floodplain Administrator must add additional freeboard to comply with the Uniform Construction Code. Class III and Class IV structures will require an additional freeboard of 1 foot and 2 feet, respectively, be added to any Flood Hazard Design Flood Elevation where the structure use has changed since permit issuance. This elevation must then be compared with the 500-year flood elevation to determine the most restrictive elevation.
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Determining a Local Design Flood Elevation involves:
- Integrating three sets of regulations;
- Evaluating FEMA effective and preliminary Flood Insurance Studies, State-studied streams and any flood mapping adopted by local ordinance;
- Determining State and local freeboard requirements;
- Adjusting for datum changes; and
- Choosing the more restrictive of adding freeboard or requiring construction to the 500-year flood for critical buildings.
When Floodplain Administrators make accurate decisions, no one seems to notice. However, when inaccurate decisions are made, they can directly impact insurance affordability for property owners and subject structures to a higher risk of flooding.
Recognizing that accuracy and documentation were two things that would help guide the decision-making process, a worksheet that can be used by Floodplain Administrators to accurately determine the proper flood elevations is available on the Bureau of Flood Engineering website. To demonstrate how this worksheet is completed, three examples are also available on the website:
- A coastal example with a datum change;
- An example of a critical building in a riverine area with a State study; and
- An example in an Approximate A zone where no Base Flood Elevation is specified.
We are interested in hearing your feedback on these worksheets. Please let us know if they are helpful or if you have any ideas for improving them.
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FEMA is in the process of conducting a Coastal Restudy to re-examine the flood hazard for coastal New York and New Jersey. This restudy is in response to New York City’s appeal of the 2013-2015 preliminary Flood Insurance Rate Maps. This study will utilize new storm surge analysis and wave modeling, that will produce revised flood maps for many coastal communities in the study area. In New Jersey these counties include Atlantic, Ocean, Monmouth, Essex, Hudson, Middlesex and Union. In New York, the study area includes Westchester County and the five boroughs of New York City. This study was initiated in the Fall of 2017. The draft flood hazard work maps are scheduled to be available in 2023 followed by the preliminary Flood Insurance Rate Maps in 2024. Once these preliminary products are released, meetings will be held to present them to the community officials (Consultation Coordination Officer Meeting) and general public (Open House Meeting) to allow time for feedback on the maps. Both meetings are expected to be held in 2024. Additionally, Flood Risk Review Meetings may be held to give community officials the opportunity to review and provide early feedback on these draft preliminary Flood Insurance Rate Map and Flood Insurance Study report. This meeting is expected to be held in 2023.
As the study is underway, FEMA is keeping stakeholders from the study area updated on its progress. This has included a series of in-person kick-off meetings for most communities in April 2018, a series of community update meetings in Fall 2019 and four bi-annual newsletters. In November 2020, FEMA hosted a series of virtual meetings to share an update on the results of the second Intermediate Data Submittal. Recordings of these meetings along with the bi-annual newsletter can be found on FEMAs Coastal Restudy website.
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Recently, the DEP has completed a project that will now allow flood maps and profiles to be downloaded. These maps were issued as "paper maps" and are available digitally in ArcGIS or a web map. Profiles for these maps can also be accessed. Instructions for using these maps and profiles are available on the Bureau of Flood Engineering website. Previously, these were only available by requesting a CD from the Bureau of Flood Engineering. A list of state-delineated waters is provided in the Appendix 2 of the Flood Hazard Area Control Act (N.J.A.C. 7:13) which lists the waters in which the DEP has promulgated a flood hazard area. In most cases, this delineation includes a flood hazard design flood elevation and a floodway limit. Follow these links to view the flood map layer and flood profiles.
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