FLOOD07170

• County: El Paso
• Community: Manitou Springs
• Stream Name: Fountain Creek
• Basin: Arkansas
• Title: Hydrology for FEMA, Phase II
• Date: 2/1/1994
• Prepared For: FEMA
• Prepared By: RCE
• Floodplain - Doc Type: Floodplain Report/Masterplan

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1. INTRODUCTION

1.1. Evaluation Procedure

The first step in the evaluation of hydrology for FEMA Flood Studies was to obtain all available
existing data for the stream basins in question, These included previous Flood Insurance Studies
(FIS), Master Drainage Reports (MDR), Letter of Map Revisions (LOMR), Letter of Map Amendments
(LOMA), Colorado State Highway Department culvert design analyses, and other related reports,

These documents were reviewed on a stream-by-stream basis to determine the current
applicability of the hydrology presented in each, The pertinent criteria included the existing level of
development in each basin, hydrologic modeling parameters and procedures utilized, and major
discrepancies among different reports for the same basin,

Field reconnaissance was conducted on all the study stream reaches to verify existing

conditions, Where necessary, return field investigations were undertaken to satisfy specific questions

arising from the literature review, Locations of the stream reaches being studied are shown in Figure

1,1,

In the cases where the reported hydrology was determined reasonable (according to FEMA
study guidelines), a modeling check of the parameters used was made to verify the resultant
discharges, For those cases with differing levels of development from existing conditions and/or out
of date design storm criteria, modifications were made to the parameters and a revised modeling
analysis was conducted,

The most detailed evaluations were made for the streams that exhibited major discharge
discrepancies among different reports, There were also cases where the City of Colorado Springs or
EI Paso County questioned the validity of reported discharges, Under these conditions, a detailed
hydrology reanalysis was undertaken, This included complete reevaluation of subbasin boundaries
and areas, Time of Concentration (T c) estimates, soil curve numbers, streamflow routing, and
detention storage routing,

1,1 Resource Consultants & Engineers, I nc,