FLOOD04031

• County: Statewide
• Community: State of Colorado
• Stream Name: All
• Basin: Statewide
• Title: Subdivision Design in Flood Hazard Areas
• Date: 9/1/1997
• Prepared For: State of Colorado
• Prepared By: FEMA
• Floodplain - Doc Type: Educational/Technical/Reference Information

Chapter 4. Site-Specific Measures
to Minimize Flood Damage and Preserve
Natural Functions of Floodplains

Previous chapters have described the natural and
beneficial functions of the floodplain, the National
Flood Insurance Program (~FTP), the planning context
for floodplain management, and the land-use planning
techniques that can be put in place to help a community
meet floodplain management goals. This chapter
advances the discussion of site-specific standards and
design requirements that a subdivision developer
would have to follm"'T to minimize the impact of a
development on the floodplain and adjacent properties.
The chapter begins with a description of the site plan
revie'\-v process that a developer \vQuld go through .with
community planners to ensure that the full range of
requirements were being folImved. It then describes the
design hierarchy for subdivisions in or near floodplains.
That discussion is folIO\ved by several site design
principles and considerations to minimize the impact of
subdivisions on the floodplain, including methods to
prevent dmvnstream flooding, ensure emergency access

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and reoccupation after a flood event, and minimize the
potential for damage to buildings, utilities, and roads.
Finally, special considerations for design of
subdivisions in alluvial fans and in coastal high-hazard
areas are presented.
The design considerations described in this chapter
should be made part of local ordinances and site plan
revievv procedures. The criteria applied to proposed
developments 'will vary depending on the type of
floodplain, the susceptibility of flooding, and the
development pressures in a community. Additional
information on alluvial fans is available in Alluvial Fans:
Hazards and Management (1989). Additional information
on construction in coastal areas is available in the
Coastal Construction Manual (] 986).

SUBDIVISION AND SITE PLAN REVIEW
Communities use subdivision regulations to ensure
that ne,v residential developments are built with

FenCL'S in floodplains can
iflcrease flood elevations hi!
collecting debris and creaiing
temporary dams. The
Sacramento Coulzll/,
Califomia, floodplain policy
allows limited fCllCing within
a floodplain, provided it
allmos for the passage of
water (such as the three-
board rail fCllce shown here).
(See Appe~dix E for excerpts
from Sacramento COlmty's
floodplain policies).

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