FLOOD06595

• County: Denver
• County: Douglas
• Community: Cherry Hills
• Stream Name: Blackmer Gulch Tributary
• Basin: South Platte
• Title: Flood Hazard Area Delineation
• Date: 8/1/1981
• Prepared For: Denver, Douglas County
• Prepared By: UDFCD
• Contract/PO #: &&
• Floodplain - Doc Type: Floodplain Report/Masterplan

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FLOOD HAZARD AREA DELINEATION
BLACK~1ER GULCH TRI BUTARY

called for hydraulic calculations to be completed at Holly Street for
both the then existing condition and also for proposed construction which
would raise the street level and add additional culvert capacity. Con-
struction of the proposed improvements was completed during the course
of the study and, therefore, the hydraulic calculations presented in this
study are based on the new construction only.

INTRODUCTION

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Blackmer Gulch Tributary is a relatively small drainage basin whose
flood waters flow into Blackmer Lake, The drainage basin is bordered on
the north by Quincy Avenue and on the south by Belleview Avenue. From
the eastern boundary near Interstate Highway 25, the basin slopes down
towards the western boundary at Blackmer Lake. Length of gulch studied
under this contract is approximately 1,1 miles, all within the City of
Cherry Hills Village, Of the total 305 acres within the drainage basin,
approximately 55 acres is located outside of Cherry Hills Village in
unincorporated Arapohoe County. This area is upstream and east of the
gulch length studied. This study was done under Agreement No. 80-9.4,
dated October 10, 1980, between the Urban Drainage and Flood Control
District and McCall-Ellingson & Morrill, Inc.

DATA FROM OTHERS

The primary objective of this study is to prepare flood plain maps so
that Cherry Hills Village can implement flood plain zoning ordinances and
other land use controls. Hydrological studies were prepared to determine
the 100-year flood hydrograph using the Colorado Urban Hydrograph Procedure
as presented in the Urban Storm Drainage Criteria Manual. Hydraulic analy-
sis was done using the Corps of Engineers' HEC-2 Water Surface Profile
computer program. Flood routing was done for the reach of Blackmer Gulch
Tributary between El Camino Drive and Blackmer Lake. Originally the contract

Hydrology was based on the future totally developed basin as projected
on the City of Cherry Hills Village t1aster Plan adopted February 9, 1970,
and on conversations with the owner/develooer of the area outside of Cherry
Hills Village jurisdiction. Ground control survey and mapping was done by
Landmark Mapping Company. Aerial photography was done on October 9, 1930
by Scharf and Associates. Starting 100-year flood elevation at Blackmer
Lake was taken from the Urban Drainage and Flood Control District's f1ajor
Drainageway Planni~ - Little Dry Cre~ report dated February 1974, and
prepared by McCall-Ellingson & t1orrill, Inc. Data for hydraulic calculations
at Holly Street was taken from field measurements and also from the drawing
entitl ed "Denver ~~ater Department Condui t No. 27 Cross Ora i nage Structure
Sta. 776 + 13.7 Sheet lA," as provided by the Denver Municipal vlater 140rks

SCOPE

Depa rtment.

DESIGN HYDROGRAPHS

Two lOO-year flood hydrographs were prepared for use in this study; the

first being for the upper portion of the basin draining to El Camino drive

and the second being for the entire basin draining to Blackmer Lake.

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