FLOOD07306

• County: Weld
• Community: Greeley
• Stream Name: Cache La Poudre River
• Basin: South Platte
• Title: Cache La Poudre River General Investigation Study, Greeley, CO
• Date: 5/1/2005
• Prepared For: Greeley
• Prepared By: USACE, Omaha, NE
• Floodplain - Doc Type: Project

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Collect Data on Public Damages and Emergency Costs (Phase I). The economic
analyst will coordinate with the non-Federal sponsor(s) regarding data on previous flood
damages to structures and contents; data on damages previously experienced for roads, bridges,
sewers, and other public facilities; costs of emergency flood fighting, evacuation, temporary
relocation, cleanup, and public administration costs of disaster relief; and information about
emergency operations plans, To account for these public damages in the Corps analysis, the
economic analyst will determine the percentage they constitute of the historic damages to
structures and contents; or use the percentage of structure, content, and externality damage that
was determined by the Corps in a previous flood damage survey in the Omaha District.

Collect Sample of Land Use Data for Structures, Contents, and Externalities (Phase
I). Considerable land use information has already been provided from a previous study and from
the Sponsor; however, some additional work is required. A "windshield" land,use survey will be
conducted for a stratified sample of structures within the 0.002 percent chance exceedance flood
plain, Each structure will be located and keyed to the stationing along the Cache la Poudre
River. Structure type and use will be categorized and keyed to the depth,damage relationships.
The depreciated replacement value of each sampled structure will be updated to current price
levels based on its estimated size, structural elements, use, depreciation, and square foot cost
(keyed to RS Means for residences and Marshall and Swift for nonresidential structures). The
content value of the residential structures will be 50 percent of the structure value, The percent
to be used for the content value of nonresidential structures will be based on the type of structure
usage, The value of features of the property external to the main structure, such as materials or
equipment stored or displayed outside, parked vehicles, detached garages or storage sheds and
their contents, and landscaping (which are referred to collectively as externalities) will also be
determined, In addition, the economist will collect any additional land use data necessary not
collected during the reconnaissance phase, including land use for which damages would be
expected to be induced by any project alternatives.

Update all Land Use Collected From Reconnaissance Phase (Phase I). The depreciated
replacement value for the structures within the 0.002 percent chance exceedance floodplain will
be calculated based on the most current assessed value of the structures. First floor elevations
and ground elevations will be updated based on 1988 datum, Structure stationing will be
assigned to each structure based on cross,section data along the Cache la Poudre River.

Task 2: Flood Damaae Model

Modify HEC-FDA with R&U Model (Phase I). The Hydrologic Engineering Center
Flood Damage Analysis (HEC-FDA) model with risk and uncertainty (R&U) will be used to
assess flood damages to the City of Greeley, The economist will modify the HEC-FDA model to
develop a study configuration specific for the Greeley study.

Setup aud Input Data into HEC,FDA model (Phase I). The economist will input the
land use data collected in Task I into the HEC-FDA program. Uncertainties associated with first
floor and ground elevations, structure and content values, and damage curves will also be
identified and quantified within the HEC,FDA model for each alternative.

Task 3: Flood Damage Reduction Alternatives
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