Overview of Federal and State Floodplain Management Programs

Transcription

1 Overview of Federal and State Floodplain Management Programs Peter DeMeo, PE Supervising Environmental Engineer New Jersey Department of Environmental Protection Division of Land Use Regulation October 16, 2014

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8 Federal and State Floodplain Management Programs Different authority Different scope Different goals and purposes in some areas Different means of implementation

9 Basic Comparison Federal Administered by FEMA and implemented locally State Administered and implemented by NJDEP Community participation in NFIP is voluntary NJDEP requirements are mandatory Uses 100-year flood Uses 100-year flood in tidal areas and larger flood in non-tidal areas* *Explained shortly

10 Basic Comparison (continued) Federal Sets minimum requirements for buildings State Sets minimum requirements for all structures (roads, bridges, utilities, etc.) Lowest floor of buildings must be at or above 100- year flood elevation Lowest floor of buildings must be at least one foot above flood hazard area design flood elevation* *Also explained shortly

11 Basic Comparison (continued) Federal Does not limit flood storage displacement (net-fill) State Limits flood storage displacement (net-fill) in non-tidal areas Focuses on how flooding impacts development Focuses on how flooding impacts development and how development impacts flooding

12 Basic Comparison (continued) Federal Different floor elevation standards for Zone AE and Zone V State Some differentiation between Zone AE and V Generally does not permit wet flood-proofing (except for water-dependent uses and some other limited cases) Permits wet floodproofing for nonresidential buildings that cannot feasibly be elevated or dry floodproofed

13 Basic Purpose of NJ FHA rules 1. Prevent flooding from getting worse Development can obstruct flood flows and displace flood storage, which makes floodplains deeper and wider, and subjects more people and property to flooding

14 Basic Purpose of NJ FHA rules 2. Protect people, property & the environment Sets floor elevation for habitable buildings Sets design standards for all structures in flood hazard area Sets access requirements for roads & buildings Sets limits on riparian zone vegetation removal Ensures that development does not adversely impact T&E species, aquatic biota, etc.

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16 Brief History of State program 1929: State begins regulating stream encroachments 15-year flood was design standard for most construction work. For drainage basins over 50 square miles, a 50- year flood was used. 1962: Governor Hughes authorizes the State to delineate and mark flood hazard areas

17 Brief History of State program 1970: NJDEP formed Assumes responsibility for stream encroachment program 1972: Governor Cahill signs the Flood Plains Act Authorizes NJDEP to adopt floodway regulations and to promulgate minimum standards for local rules and regulations concerning development in the flood fringe

18 Brief History of State program 1974: NJ Water Policy and Supply Council sets NJ s design flood and floodway limits Equal to 125% of FEMA 100-year flow rate Additional flow determined to be necessary as a factor-of-safety to account for potential future increases in flood elevations due to development Floodway to be computed based on 0.2-ft rise (other States use 1-ft rise) resulted in wider floodways that other States

19 Brief History of State program 1975: NJDEP adopts floodway rules to: Minimize flood damage caused by land uses Minimize degradation of water quality from point and non-point pollution sources Protect wildlife and fisheries by preserving and enhancing the environment of the floodplain. Applied only to development within the floodway

20 Brief History of State program 1977: NJDEP adopts 0% net-fill restrictions in the Central Passaic River Basin Placing fill in the flood fringe displaces floodwaters and therefore causes flooding to increase in depth and extent 1980: Flood Hazard Area Control Act adopted Grants NJDEP broad powers to regulate development in flood hazard areas

21 Brief History of State program 1984: NJDEP adopts 20% net-fill restriction Applies to all other non-tidal flood hazard areas 1995: New stream encroachment rules adopted Increased protection of near-stream vegetation Lowest floor of buildings must be set at or above design flood elevation (NJDFE in non-tidal areas)

22 Brief History of State program 2007: Stream encroachment rules repealed and new flood hazard area rules adopted 50, 150 & 300-ft riparian zones established 0% net-fill applied to all non-tidal flood hazard areas New process to verify extent of flood hazard areas and riparian zones Six methods to calculate flood hazard area Lowest floor of buildings must be set at least one foot above design flood elevation

23 Brief History of State program 2013: NJDEP adopts emergency amendments to flood hazard area rules Incorporated FEMA advisory and work maps Incorporated new FEMA maps that show flood hazard area design flood elevation Changed how to calculate flood hazard area design flood elevation

24 FloodHazardArea

25 FloodHazardArea In NJ, the flood hazard area is determined by the extent of the Flood Hazard Area Design Flood

26 FloodHazardArea The flood hazard area is comprised of the floodway and flood fringe

27 What is a 100-Year Flood? More accurately described as a 1% flood Within a given year, this flood has a one percent probability of occurring Over time, a flood of this magnitude happens about once every century at a given location

28 NJ Flood Hazard Area Design Flood In tidal areas:equal to FEMA 100-yr flood Use FEMA effective map, or newer advisory/work map, whichever has higher flood elevation

29 NJ Flood Hazard Area Design Flood In fluvial areas: equal to FEMA 100-yr flood plus a factor-of-safety NJDEP flood maps: based on 125% of 100-yr flow Use highest FEMA elevation above + 1 foot or use flood hazard area design flood elevation from NJDEP mapping whichever is higher Or you can calculate flood based on 125% of 100-yr flow

30 Flood Mapping Sources NJDEP flood mapping FEMA flood mapping Self-calculated mapping

31 NJDEP Flood Mapping About 2,500 miles of streams & rivers have State flood mapping Mostly in fluvial (non-tidal) areas Listed in Flood Hazard Area Control Act rules Rule can be downloaded at: Get copies by calling (609)

32 FEMA Flood Insurance Study (FIS) Contains: Information regarding flooding in a community, developed as the basis and in conjunction with the FIRM Flooding sources Flood history Stillwater elevations for various return periods Hydrology and hydraulic information Source: FEMA

33 Finding and Using a FIS The FEMA Map Service Center: (or Google search for FEMA MSC" and "FIS ) FIS tutorial: htm (or Google search for FEMA," "FIS," and "tutorial") Source: FEMA

34 FEMA Flood Insurance Rate Maps FIRMs are used to determine flood insurance rates and premiums FIRMs depict BFEs or flood depths, floodways, and common physical features (e.g., roads) Information shown on FIRMs affects design FEMA FIRM Tutorial link: Source: FEMA

35 AE-Zone vs. V-Zone V-Zone: Wave Height at least 3 feet AE-Zone: Wave Height less than 3 feet Note: Portions of the A-Zone with a wave height of between 1.5 to 3 feet are referred to as the Coastal A-Zone

36 Incorporating FEMA maps NJDEP is working with FEMA to remap the State s flood hazard areas People will easily see NJDEP & FEMA mapping online FEMA is putting NJDEP s design flood elevation on its maps

37 Incorporating FEMA maps If FEMA adopts a map showing NJDEP design flood elevation, it will automatically become a NJDEP map and replace any old flood maps FEMA adopted such mapping along the Delaware River in Hunterdon, Warren & Sussex Counties, so the FHA rule automatically incorporated it, as of 1/24/13

38 State vs. FEMA NJDEP FHA: Surface of lowest floor must be elevated at least one foot above design flood elevation regardless of A zone or V zone. Lowest floor must therefore be: One foot above the BFE in tidal areas; and At least two feet above the BFE in fluvial areas

39 State vs. FEMA FEMA/UCC: In Zone AE: surface of lowest floor must be elevated to at least the BFE. In Zone V: lowest horizontal member must be elevated to at least the BFE(and may be required to be 1 ft. above BFE depending on the angle of the member compared with wave direction)

40 State vs. FEMA Therefore: In Zone AE, NJDEP is more stringent than Uniform Construction Code In Zone V, Uniform Construction Code may be more stringent than NJDEP (depending on the thickness of the floor and direction of waves)

41 NJDEP Floor Elevations The FHA rules set standards for the lowest floor of habitable buildings Non-habitable buildings do not need to be elevated Note: NJDEP sets floor elevation but UCC sets specific building standards

42 Habitable Buildings The lowest floor of residential buildings must be elevated one foot above the design flood elevation Lowest floor means the top of the floor the walking surface* An unfinished enclosure, such as a crawl space, entryway and/or garage is not considered the lowest floor *Note: FEMA/UCC measure this differently in Zone V

43 NJDEP Lowest Floor

44 NJDEP Lowest Floor

45 Habitable Buildings The lowest floor of non-residential buildings must be: Elevated one foot above the design flood elevation; or If elevating is not feasible, it must be dry flood-proofed; or If dry flood-proofing is not feasible, it must be wet flood-proofed

46 For More Information: Peter DeMeo, PE Supervising Environmental Engineer NJDEP Division of Land Use Regulation Trenton, NJ Phone: (609) Website: