HomeMy WebLinkAboutFloodplain Development Guidance(ENG-FINAL) 03212017SP-001-E2
Purpose: To provide guidance for development in and adjacent to the regional 1% annual chance floodplain as shown in FEMA’s Flood Insurance Rate Maps and Flood Insurance Study, consistent with Edina City Code floodplain districts overlay ordinance Chapter 36, Article X. Other known local flood issues will be addressed on
a case by case basis; contact the Engineering Department for requirements.
Scope: All development in and adjacent to the regional 1% annual chance floodplain (also called the 100 year
floodplain) as determined by FEMA. Development in the floodplain includes new structures, additions, grade changes, excavation, fill, accessory structures, walls, and obstructions.
Additional survey requirements All survey points must be provided to the tenth of a foot and in NGVD29 datum.
1.Existing and proposed Lowest Floor Elevation (LFE): lowest floor means the lowest floor of the lowest
enclosed area, including basement.2.Base Flood Elevation (BFE): the elevation of the modeled 1% annual chance flood. This information can be
provided by the Water Resources Coordinator, call 952-826-0445.
3.Ordinary High Water Level (OHWL): for lakes, ponds, and wetlands, the OHWL is the elevation delineatingthe highest water level that has been maintained for a sufficient period of time to leave evidence upon the
landscape, commonly the point where the natural vegetation changes from predominantly aquatic to
predominantly terrestrial. For Minnehaha Creek and Nine Mile Creek, the OHWL is the elevation of the top ofthe bank of the channel. The Minnesota Department of Natural Resources (MN DNR) determines OHWLs; in
the absence of a MN DNR defined OHWL, the Normal Water Level (NWL) may be used. OHWL and NWLcan be accessed at https://www.barr.com/maps/edina/index.html.a.Setbacks: All principal and accessory structures shall maintain a minimum setback of 50 feet from the
OHWL, except that all principal and accessory structures shall maintain a minimum setback of 75 feetfor Indianhead Lake, Arrowhead Lake, Mirror Lake, and Lake Cornelia.
4.Lowest Adjacent Grade (LAG): the lowest natural ground level that is immediately adjacent to the structure.
a.For window wells, the LAG is taken at the bottom of the window well.5.Final as-built survey for new construction or additions in the Special Flood Hazard Area must include an
Elevation Certificate. A copy of the form is available at http://edinamn.gov/engineering_flood_resources.
Floodplain development Development standards are intended to prevent loss of life, reduce property damage, result in no adverse impact to
adjacent properties, and protect and enhance the natural and beneficial functions of floodplains.
The lowest floor elevation (LFE) of a new home or addition must be a minimum of 2 feet above the 1%
annual chance base flood elevation (BFE).
Compensatory storage required if fill is to be placed in the 1% annual chance floodplain.
Retaining walls must have low flood damage potential and not obstruct flows.
Expansion or enlargement of nonconforming primary structures located within the floodway is prohibited.
Any other proposed development in the floodway, including placement of fill, will require ‘no-rise’certification and supporting hydraulic analysis from a professional engineer showing that the proposed
development will result in no increase in the 1% annual chance base flood elevation. A no-rise
certification form is available at http://edinamn.gov/engineering_flood_resources.
EDINA BUILDING SAFETY POLICY/INFORMATION1
Floodplain Development - Residential
subject
City Ordinance – Chapter 36, Article X
code reference
Engineering Department
department approval
SP-001-E2
policy number
03/21/2017
revision date
0/01/2 017
effective date
1 of 2
page number 1.All Building Safety sheets adopted by Fire Department and Inspections Department. 2. Policy -B suffix developed by Inspections Dept. –F, Fire Dept. – E, Engineering
SP-001-E2 Page 2
I:\Building\SafetyPoliciesInformation\2017\Website\Floodplain Development Guidance(ENG-FINAL) 03212017.
Substantial Improvement for structures in the regional 1% annual chance floodplain Nonconforming uses and structures are subject to substantial improvement limitations. Within any consecutive
365-day period, any reconstruction, rehabilitation (including normal maintenance and repair), repair after damage, addition, or other improvement of a structure may not equal or exceed 50 percent of the market value of the
structure before the start of construction of the improvement. If a structure is substantially improved, the requirements for new construction will be applied. Any correction of existing violations of State or Community health, sanitary, or safety code specifications which have been identified by the community code enforcement
official and which are the minimum necessary to assure safe living conditions do not count toward the substantial improvement limit.