FLOOD08216

• Designation Number: 449
• County: Weld
• Community: Frederick
• Basin: South Platte
• Title: Flood Insurance Study - Frederick, Colorado
• Date: 7/1/1982
• Designation Date: 3/1/1997
• Floodplain - Doc Type: Floodplain Report/Masterplan

5.0 INSURANCE APPLICATION

In order to establish actuarial insurance rates, the Federal Emergency
~1anagement Agency has developed a process to transfor~ the data from
the engineering study into flood insurance criteria. This process
includes the determination of reaches, Flood Eazard Factors, and flood
insurance zone designations for each flooding source studied in detail
affecting the To'~ of Frederick.

5.1 Reach Determinations

Reaches are defined as lengths of watercourses having relatively
the same flood hazard, based on the average weighted difference
in water-surface elevations between the 10- and lOO-year floods.
This differences does not have a variation greater than that indi-
cated in the following table for more than 20 percent of the reach.

Average Difference Between
~: and JOO-year Floods

Variation

Less than 2 feet

0.5 foot

Give reaches meeting the above criteria were reauired for the flood-
ing sources of Frederick. Four of these occur in the Divided Flow
Area, and one along the Tri-Aerea Drainageway. The locations of
the reaches are shown on the Flood Profiles.

5.2 Flood Hazard Factors

The Flood Hazard Factor (FHF) is the Federal Emergency Management
Agency device used to correlate flood information with insurance
rate tables. Correlates between property da~age from floods and
their FRF are used to set actuarial insurance premiu~ rate tables
based on FHFs from 005 to 200.

The FHF for a reach is the average weighted difference between the
10- and IOO-year flood water-surface elevations expressed to the
nearest one-half foot, and shown as a three-digit code. For example,
if the difference between water-surface elevations of the 10- and
100-year floods is 0.7 foot, the FHF is 005; if the difference is
1.4 feet, the FHF is 015' if the difference is 5.0 feet, the FHF is
050. When the difference between the 10- and 100-year water-surface
elevations is greater than 10.0 feet, accuracy for the FRF is to
the nearest foot.

5.3 Flood Insurance Zones

After the determination of reaches and their respective Flood
Hazard Factors, the entire incorporated area of the TOvm of
Frederick was divided into zones, each having a specific flood
potential or hazard. Each zone was assigned one of the following
flood insurance zone designations:

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