HomeMy WebLinkAboutGALLEGOS SUBDIVISION - 10-88 - SUBMITTAL DOCUMENTS - ROUND 2 - DRAINAGE REPORT (2)a
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STEWART&ASSOCIATES
Consulting Engineers and Surveyors
March 16, 1988
Mr. Robert Smith
Director of Storm Drainage Utility
City of Fort Collins
P.O. Box 580
Fort Collins, Co. 80522
Dear Bob:
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The following is a storm drainage report for the Gallegos Subdivision
which is located on the west side of North Taft Hill Road about 200 feet
north of Laporte Avenue. It is located in the West Vine Drainage Basin.
The proposed one lot subdivision lies between two existing residences
and contains a gross area of 0.31 acres. The subdivision is located
within the existing and developed 100 year flood plain. The 100 year
flooding through this site will be shallow sheet flow. The land slopes
from the southwest corner, with an elevation of 5054.9, to the northeast
corner, with an elevation of 5053.9. The expected flood water surface
elevation varies from 5055.0 at the west side of the subdivision to 5054.0
at the east side of the subdivision The proposed minimum finish floor
elevation is 5057.8, and the ground adjacent to the house will be at
elevation 5056.3. This will raise the floor 2.8 feet above the 100 year
flood elevation. The proposed ground elevation will provide good drainage
away from the proposed residence.
According to the West Vine Drainage Basin study, made by Engineering
Professionals, Inc., a basin wide detention pond is proposed in the area
east of Taft Hill Road and south of West Vine Drive. This pond, after
it is constructed, will handle the developed run-off, and no detention
will be required on the site. We propose to not provide detention on
the site, due to the facts that the future pond will handle the run-off,
and also that the peak run-off from this site, before development of
the pond, will be gone downstream before the peak flows from 3800 feet
upstream arrive.
The 100 year flow of the basin in the area of the Gallegos
Subdivision is 750 cubic feet per second as compared to 0.91 cubic feet
per second, which is the 100 year run—off from the Gallegos Subdivision.
The historic 2 year and developed 2, 10, and 100 year run—off flows
from the Gallegos Subdivision are calculated on the attached sheet.
PIR/lkm
enclosure
James H. Stewart
and Associates, Inc.
214 N. Howes Street
PO. Box 429
Ft. Collins, CO 80522
303/482-9331
Sincerely,
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Richard A. Rutherford, P.E. & L.S.
President
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