FLOOD10401

• County: El Paso
• Community: Colorado Springs
• Stream Name: Fountain Creek
• Basin: Arkansas
• Title: Fountain Creek Drainage Basin Planning Study - Volume 1
• Date: 7/1/1994
• Prepared For: Colorado Springs
• Prepared By: Muller Engineering Company, Inc.
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Recommendation - ExistinQ Conditions

From the information presented in the immediately preceding sections of this
report conclusions can be reached on existing condition flow values and/or
methods which come the closest to producing those values. Other considerations
also enter into the process of actually deciding upon flow values to be adopted.
Those include: '

1. The purpose for which the flows are to be used.
2. The scientific supportability and level of uncertainty associated with
the flows proposed for adoption.
3. The local government philosophy of flood control, current flood
regulations and consistency/fairness in handling flood-related issues.
4. The threat of flood damage and loss of life and the effectiveness of
timely flood warning programs.
5. Economic impact.

Factoring these characteristics into the decision making process is difficult and
subjective, however, it is necessary to do so.

Based on the information of the previous section of this report we believe the
values in Table 4.9-1 at the hydrologic index locations and the study limits are
the most reasonably accurate existing conditions hydrologic peak flows which can
be developed with the information available.

TABLE 4.9-1
MOST REASONABLY ACCURATE PEAK FLOW VALUES

Design
Point

la-Year

lOa-Year

At Manitou Gage
(Upstream Study Limit)
Upstream of Confluence
Downstream of Confluence
At Tejon Gage
At Downstream Study Limit

24
27A
27B
29
31

2,000 ( 3,300t)*
2,500 ( 4,400 )*
8,500 ( 9,200 )*
9,000 (10,000!)*
9,500 (10,500!)*

9,000 (16,000)*
10,000 (20,500)*
30,000 (42,200)*
33,000 (45,000)*
34,000 (48,000)*

* Currently Adopted Regulatory Values

The design storm method produces peak flow values which approximate the most
reasonably accurate values as illustrated by Table 4.7-4, which is summarized by
values at hydrologic index locations and the study limits in Table 4.9-2. As can
be seen from Figures 4.8-1 and 4.8-2, the design storm method produces peak flow
values which are lower than the current regulatory flows but still in the upper
portion of the flow frequency envelope. Based upon the results of this existing
conditions flow evaluation we recommend using the design storm method, as
described herein to produce design flows for use in this study.

4.0-28