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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over thE! broad crested spillway from the reservoir, the flow is
through another natural channel that leads to culverts under
Lake and then Nevada Avenues.

Shortly downstream of Nevada Avenue I the watercourse is routed
through a 132 inch CMP culvert that necks down to 60 inches
over its 1,100 foot length before resurfacing at Southgate
Avenue. The land under which this culvert is placed is
dIrectly adjacent to the Sears Shopping Center complex. At
this point, the channel becomes concrete lined for 1,100 feet
through a park area of Stratton Meadows to a point near the
intersection of Corona and Montrose Avenues. There it enters
an 8 by 5 feet RCB culvert that flows under Corona Avenue to
CheyennE! Road.

From this location, the channel is concrete lined for the rest
of the dIstance to Interstate 25. At the Interstate, the flow
is directed northward through an earth "borrow" ditch to its
outflow point approximately 1,600 feet further. A 30 inch CMP
culvert under the Interstate is presently the sole conveyance
of the watershed to Fountain Creek on the east side of the
highway. In summary, I-he length of the Spring Run Channel from
BIg Stratton Reservoir to Interstate 25 is approximately 2
miles at an average slope of 1.5%.

There are few storm sewers existing in the basIn at present.
Most rainfall runoff converges on the main channel by means of
street and gutter flow.

Hydrologically, this watershed can be interpreted as two
separate sections divided by the detention storage provided by
the Big Stratton Reservoir. Al though not operated primarily as
a storm detention facility, this reservoir serves to
effectively regulate the runoff flowing into it. rn addition,
there are three undeveloped ponding areas downstream of Big
Stratton at the culverts under Lake Avenue, Nevada Avenue, and
the Sears Shopping Center. These four detention storage
"facilIties" serve to attenuate the peak storm flow
drastically. For all practIcal purposes, the peak flow of
concern for the areas helow Nevada Avenue originates in those
areas below this detention storage.

Two previous studies have been done on Spring Run. They are
the Englneeriru; Study of the Southwest Area Draina~e Basin
(ESSW) (Reference 12), and the Park Meadows Channel/Cheyenne
Creek Q~fall Preliminary Desi~n of Draina~e Imorovements
(PMCC) (Reference 13).

Previous Studies

The hydrology for Spring Run conducted by the ESSW was done at
the same time as that for Cheyenne Run and was based on the
same parameters (6-hour event occurring tmder AMC II conditions
with type IIA distribution and a 3.5 inch rainfall depth). In

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