HomeMy WebLinkAboutOVERLAND HILLS SUBDIVISION 2ND FILING FINAL - 38 90C - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTOVERLAND HILLS SECOND FILING
FINAL DRAINAGE REPORT
DECEMBER 1, 1990
PREPARED BY
STEWART & ASSOCIATES, INC.
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SITE LOCATION:
The site is located in the Northwest a of Section 33, Township 7 North,
Range 69 West of the Sixth P.M., Fort Collins, Larimer County, Colorado.
The area is 9.1916 acres more or less. It is located in the Springcreek
Drainage Basin.
EXISTING CONDITIONS:
The site is bounded on the East by Tract A. Springfield Sixth Filing,
which is a detention pond. It is bounded on the South by an existing
single family residence and a portion of the Overland Hill First proposed
subdivision. There is no development on the West or North side. The
site drains South to North and then West to the Springcreek Drainageway.
The average slope is about 1.6%. There is no offsite drainage from the
North or West sides of this proposed site. There will be some offsite
flows from the existing single family ,residence to the South. This
offsite drainage flows to Spring Creek accross the back of Lot 4 and
is not routed through our street system. This area is minimal and has
little effect on our developed site. There will not be any runoff from
Overland Hills First Filing. That water is rerouted to pass through
the Springfield Detention Pond. The existing site runoff to Springcreek
is Q2 = 2.7 c.f.s., Q10 = 5.1 c.f.s. and Q100 = 10.3 c.f.s.
DEVELOPED CONDITIONS:
The proposed site will be divided into 4 lots served by a cul-de-sac
from Horsetooth Road. The average size lot will be about 2.3 acres gross.
Because of the proximity to Springcreek Drainageway there will be no
detention for these 4 lots. Tract "A" has been platted and will be deeded
to the City for open space. The 100 year floodway lies in this tract.
The site is divided into Basin "A" and Basin "B". All of the runoff
from Basin "A" flow directly to Spring Creek drainageway. The Q2 = 0.94
c.f.s., Q1n = 1.76 c.f.s. and Q100 = 3.37 c.f.s. The runoff from basin
"B" flows io the curb inlet shown on Horsetooth Road. Q2 =4.78 c.f.s.,
Q10 = 8.25 c.f.s., and QjQO = 16.91 c.f.s. A 10.00 foot wide curb inlet
is required on Horsetooth Road to handle the 10 year flows. The South_
-- - one half of Horsetooth Road can handle 6 c.f.s. which exceeds the
developed 2 year flow.
The 100 year floodway line and the 100 year floodplain line shown on
the enclosed drawing were taken from the "Floodplain Analysis for Overland
Hills Subdivision" for Filings 1 and 2 completed this year by Resource
Consultants, Inc. We are including with this report a copy of the outflow
from the detention pond on Tract "A" of Springfield Sixth Filing. An
easement has been granted from Kim Stuart to the Springfield Homeowners
Association for this outflow Swale. Also included is a plan of the
downstream outfall across the farm land of Day.id and Mary Whitham.
Negotiations are underway at this time to secure an outfall easement.
Franklin D. Blake, P.E. & L.S.
COMPUTATIONS
Stewart & Associates, Inc. 214 N. Howes St. Ft. Collins, CO 80521 (303) 482.9331
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COMPUTATIONS
Stewart & Associates, Inc. 214 N. Howes St.
By: --1!Date Client:
Date Project:
Ft. Collins, CO 80521 (303) 482-9331
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COMPUTATIONS -
Stewart & Associates, Inc. 214 N. Howes St. Ft. Collins, CO 80521 (303) 482-9331
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