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
Page Three

A copy of Section III, HYDROLOGY, of Volume I of the Planning
Report is attached as Exhibit A to provide additional back-
ground data concerning the hydrology.

The flow magnitudes used for the determination of the flood
profile and the resulting flood hazard areas are presented
on the Discharge Probability Profile Charts attached to this
report. Exhibit B gives the 100-year flows for Weir Gulch.
Note that approximately 75% of the 100-year flood peak flow
is diverted from the main drainageway at Barnum Park (Federal
at Sixth Avenue). These waters will overflow onto Sixth Avenue
and proceed east to the river through a heavy industrialized
area. As a result, flows in the channel are near capacity and
flooding in the area will result from shallow overland flows
lost from the main floodway at Barnum Park.

Exhibit C shows the 100-year discharge profile estimated for
Sanderson Gulch, reflecting the effect of Smith Reservoir
and Kendrick Reservoir and neglecting the existence of Jewell
Park Pond, the Green Gables Golf Course entrance road, Clair-
field Reservoir and Bit-O-Sea Reservoir.

III. CROSS SECTIONS

The cross sections used for the determination of the 100-year
storm viater surface profile have been plotted on the cross
section sheets accompanying the plan and profile base maps.
Each section is keyed to the plan and profile portion of the
maps by the appropriate section number.

In certain instances, the cross sections do not cover the
total width of the delineated flood plain. The extent of the
cross sections plotted has been the limitation of the topography.
In all cases, the main channel is shown which carries the flood
flows of hazardous velocities and depths. In certain areas,
overbank flooding will be experienced outside the limits of the
channel section plotted.

The sources of the cross sections have been the topographic
mapping used for the base sheets. Supplemental field surveys
were taken at selected road crossings to verify the maps and
provide additional information. The two-foot contour, 1" s 100' scale
mapping used for \'jeir Gulch was flmlD in November, 1971, as part
of the Sanderson-Weir GUlch planning project. The Sanderson Gulch
mappina was flown in July, 1969, under a Denver Parks Contract.
This base mapping was also prepared at two-foot contours and
1" = 100' scale.

The field survey work completed to supplement the maps was not
done independently of the maps. Pll survey data was done in a
relative manner and tied to mapped elevations. No bench marks
were used. A record of control information used for mapping