FLOOD04641

• County: Denver
• Community: All
• Stream Name: All
• Basin: South Platte
• Title: Proposed Hydrology for use in Hydraulic Analysis of FEMA Flood Studies and Restudies
• Date: 9/1/1989
• Prepared For: State of Colorado
• Prepared By: Resource Consultants
• Floodplain - Doc Type: Educational/Technical/Reference Information

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ranching. Some development involving commercial and
residential use has occurred along lower Marksheffel Road
between the Chicago Rock rsland and Pacific Railroad and
Constitution Avenue. Soils in the north of the basin are
predominantly of type "A" classification; those in the south
are tYPB "B".

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Three previous studies were available for review. These were
the FIS, -=- II Paso County (Reference 19) and the Sand Creek
Master ;Drainage Plannin.; Study -=- City of Colorado Sorings f. II
Paso County -=- Development of Alternate Plans developed by
Simons, Li and Assoc., Inc. (SLA) in cooperation with Finn &
Associates, Ltd. (Reference 17). The SLA work was supported by
recently completed efforts (unpublished as of this writing)
underway by Kiowa Engineering Corporation (KEC) for the Aries
propertIes. A copy of the Kiowa work as submitted for review
by the City of Colorado Springs and El Paso County was made
avaIlabie to RCI for consideration in the development of this
report (Reference 20).

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10.2 Previous Studies

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Details of the hydrologic analyses done for the FIS and SLA can
be found In this report under the sections for Sand Creek Main
Stem and Sand Creek West Fork, respectively. Neither of these
studies were conducted according to current DCM criteria. The
third analysis by KEC is much more recent (January, 1989) and
incorporates current criteria in its analysis.

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FIS
SLA
KEC

6.50
6.31
5.92

410

1,000

1,300
2,480
2,026

2,000

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Two-hour AMC III and 21,-11Our AMC II storms were modeled by KEC
with TR-20 for both existing and future conditions. Rainfall
depths of 3.1 inches and 4.5 inches were used for the 100-year
2-hour and 24-hour storms, respectively. Channel routing was
Included.

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A summary of peak dIscharges for the three previous studies is
provided in Table 10.1. In the case of the KEC, only
discharges for the 2-hour AMC III storm under existing
conditions are shown.

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TABI.E 10.1

- SUMMARY OF !lET PEAK DISCHARGES FROM PREVIOUS REPORTS

DRAINAGE AREA

PEAK DISCHARGES igill
AT THE CONFLUENCE WITH SAND CREEK EAST FORK
10 YR 50 YR 100 YR 500 YR

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REPORT

u:auare mi 1 as)

557

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10.3 Hydrologic Analysis

Review of the KEC work resulted in the conclusion that the
analysis was reasonable for existing conditions and abided by

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1,2

R€~OURC€ CON~UlTI\NT~ INC

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