FLOOD05470

• County: Denver
• Community: Denver, Lakewood
• Stream Name: Sanderson Gulch, North Sanderson Gulch
• Basin: South Platte
• Title: Flood Hazard Area Delineation - Supplementary Report
• Date: 3/1/1975
• Prepared For: Denver / Lakewood
• Prepared By: UDFCD
• Floodplain - Doc Type: Floodplain Report/Masterplan

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SUPPLEMENTARY REPORT

FLOOD Hl\Zl\HD ~1J\PS
SANDERSON GULCH & HElP Gl'LCH
DENVER, COLORP.DO
/11\PCH. 1975

I. GENERl'.L

The flood hazard areas on Sanderson Gulch and Heir Gulch in
Denver, have been delineated on base plan and profile maps
as reauested by the City of Denver and the Urban Drainage
and Flood Control District. The majority of the effort re-
quired to provide these maps was done during the Major
Drainageway Planning project for Sanderson Gulch and Weir
Gulch. For a review of that project, refer to the two-
volume report entitled, "Major Drainageway Plannina, Sander-
son Gulch/l^leir Gulch".

The objective of the planning project was to develop a viable
plan for improvements to the total length of each of the drain-
ageways. This provided the cities adjoining the gulches with
the information needed to improve the drainage facilities in a
staged or priority fashion when monies become available. It
became evident that some control was needed by the City over
these drainageways prior to the time when improvements could he
made. Thus, the flood hazard areas have been delineated for
the gulches to permit immediate r~gulation.

II. HYDHOLOGY

In the study mentioned above, hydrologic studies were completed
for both the Weir Gulch Basin and the Sanderson Gulch Basin.
These studies were based on criteria outlined in the Denver
Regional Council of Governments' Urban Storm Drainage Criteria
~lanual. A thorough description of the hydrologic studies is
presented in Section II of Volume I of the Master Plan Report.

To summarize the bases of these studies, the basins were con-
sidered to be fully developed followinq a development pattern
which has alreaay~en-established within the basiin. Presently
each basin is approximately 80 to 85% developed. A full range
of storm frequencies was considered in the original hydrologic
study varying from the two-year storm event to the 100-year
storm event. The flood hazard areas delineated on the "ccompanying
maps are for the 100-year storm frequency only. The effect of
each of the reservoirs along the gUlches was considered in the
development of the downstream flows.