FLOOD00689

• Designation Number: 136
• County: Arapahoe
• Community: Littleton
• Stream Name: Slaughterhouse Gulch
• Title: Major Drainageway Planning - Slaughterhouse Gulch, Littleton
• Date: 5/1/1974
• Designation Date: 5/1/1979
• Floodplain - Doc Type: Floodplain Report/Masterplan

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Along the south tributary, an improved sewer was recommended
which would extend from the main stream to Littleton Boulevard
along Windermere Street and then easterly along Littleton
Boulevard to Datura Street. It was proposed that inlets
be provided along the alignment with a large grated inlet
at Datura Street to collect all street flows. With the
high damage potential associated with the area, extensive
improvements of this magnitude can easily be justified,
economically. The cost estimated for these improvements
would be approximately $579,000 while benefits were on the
order of $3,382,000, giving a cost benefit ratio of 5.84.
The cost information for Alternate 2 for both the main stream
and the south tributary are shown on Table VI.

Alternate No. 3 proposed the Same improvements proposed
for Alternate No.2 with the addition of modifications to
the Powers Park Detention Pond. At the park, consideration
was given to increasing the flood storage volume available
at the site to reduce downstream flows. This in effect,
would tend to reduce the potential flood damages of the
areas below Powers Park. With Powers Park being an on-
channel type of detention pond, which must pass the total
flood hydrograph characteristic of that point, coupled with
the various land constraints surrounding Powers Park,
improvements could be made so the flooding potential pre-
sently associated with Berry Circle below the park would be
reduced to a degree of flooding presently characteristic of
the 7 year storm event. This improvement would certainly
reduce the damage along Berry Circle but certainly would not
eliminate them. The area would still have to be flood plain
zoned and qualified for flood insurance.

With these improvements on the main stream, the total cost
of this alternate was estimated to be approximately $919,500
with benefits on the order of $1,172,300 or a benefit-cost
ratio of 1.28.

On the south tributary, the proposed improvements included
the lowering of Windermere Street a maximum of approximately
1 1/2 to 2 feet for a distance of 650 feet north of Powers
Avenue. Also additional surface inlets would be provided
along the existing storm sewer to utilize available pipe
capacity. The suggested improvements would reduce the anti-
cipated damages for the 2 year storm through the total reach
of the south tributary study area to zero. Damages would
still be associated with the flood events associated with
the 1ess.frequent storms, particularly in the area above
Powers Avenue. The greatest share of the reduced damage
would be attributed to the apartment buildings along the
west side of Windermere Avenue north of Powers Street.

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