FLOOD01785

• County: Larimer
• Community: Fort Collins
• Stream Name: South Platte Tributaries
• Title: Hazard Mitigation 404 Grant Application Floodproofing
• Date: 9/1/1999
• Prepared For: Larimer County
• Prepared By: Fort Collins
• Floodplain - Doc Type: Miscellaneous

City ofF on Collins

Hazard Mitigation 404 Grant Application

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handle the volume of water, caused many streets to flood. Several
businesses and private residences sustained flood damage, mainly to
basement levels. The flooding affected the older section of town the
worst, due to a combination of that area receiving the most rainfall and
having an out-dated storm drainage system. The total damage was
$438,000, as a result of 51 homes with flooded basements and 16 low-
lying businesses with damage in the Old Town area. Flooding of Poudre
Valley Hospital occurred because roof drains were unable to handle the
volume of water on the roof.

Localized flooding associated with the 1997 Flood also affected Old Town
and several neighborhoods on the west side of the city. These areas
experienced considerable damage and were constructed prior to current
storm drainage criteria.

The rains in late April and early May of 1999 set several records. April
was the second wettest month since record keeping began in Fort Collins
in 1889_ A total of8.29" fell at the CSU Main Campus gage in April with
7.64" of that coming after the 20th of the month. The rainfall total for
April 29-30 was 4,15"_ This value is within the top ten 2-day total rainfall
for the CSU Main Campus gage_

Flooding in Fort Collins

The City of Fort Collins has experienced a variety of flooding problems
including: loss of life in high velocity floodplains; vehicles being caught in
flooded intersections; severe damage to buildings and mobile homes subject to
water greater than 3 feet deep; varying degrees of damage to buildings due to
shallow flooding less than 3 feet deep; erosion and undermining damage to
bridges, culverts and stream bank protection; and damage to streets and utilities.
This application will focus on just one of these problems, varying degrees of
damage to buildings due to shallow flooding less than 3 feet deep. Existing
programs of the City's Stormwater Division already address some of the other
flooding problems and will continue to address them in the future. There is,
however, no existing program to address a means of protecting buildings subject
to shallow flooding.

The first step in defining this particular problem is to inventory the existing
buildings subject to flooding_ The City has approximately 797 commercial and
residential structures in the federally regulated (NFIP) floodplains of the Cache
La Poudre, Spring Creek, Dry Creek, Cooper Slough, and Boxelder Creek. The
City also has locally designated floodplains including Old Town, West Vine, and
Fossil Creeks, with approximately another 50-100 structures in those floodplains_
There were approximately 230 flood insurance policies in effect when the July
flood occurred.

In addition to the regulated floodplains, the Fort Collins Stormwater Division has
subdivided the City into Stormwater Basins (Map 3, Fort Collins Drainage
Basins). Each Stormwater basin has an associated Master Plan, which includes
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