HomeMy WebLinkAboutHORSETOOTH WEST MASTER PLAN - 14-88 - CORRESPONDENCE - STORMWATER-RELATED DOCUMENTSMarch 4, 1988
Mr. Ted Shepard
City of Fort Collins
Planning and Development
Box 580
Fort Collins, Colorado 80522
RE: HORSETOOTH WEST MASTER PLAN
DRAINAGE CONCEPT
FORT COLLINS, COLORADO
Dear Ted:
GEFROH HATTMAN INC.
ARCHITECTS/PLANNERS
CONSTRUCTION MANAGEMENT
135 West Swallow Road
Fort Collins, CO 80525
(303) 223-7335
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The purpose of this letter is to outline the concept for disposing of storm
water runoff from this 60.45 acre parcel which will be known as the Horse -
tooth West Master Plan. The property is a mixed land use project with such
uses as single-family detached housing, multifamily attached housing, an
elementary school site, a child care center site, a neighborhood center,
and a road side commercial site.
Area -- The site is located at the Northwest intersection of Taft Hill
Road and Horsetooth Road with frontages of approximately 1400 feet and 2000
feet respectfully. The property is developed on three sides with residential
uses of various densities from estate type lots to a mobile home park. The
undeveloped property lies to the West.
Off -Site Contribution -- is1considered non-existentlwhen reviewing the
topography. The area crowns approximate y in the Southwest corner of the
property. Irrigation canals West of the site will intercept - C
off from of� site, The majority of this adjacent property runoff flows ,
North and West into Spring Creek.
The subject property is a relatively level property sloping from the South-
west corner to the Northeast corner. Previously used for crop land, there was
no significant topographic changes that occurred on site. The average slope
of the land is between one percent and two percent consistently cross contour. �QiC
Ijti 1�%" Historically runoff from the
I�North to Spring Creek.
n� Criteria -- Due to the size
which will be developed for
.I,oi1 Rational Method as found in
The Rational Method relates
cv�l
rano(�
property has flowed to Taft Hill Road then heads��y
of the study area for purposes
each individual parcel as it is
the Urban Storm Drainage Manual
runoff to rainfall intensities:
of calculations /a4l
designed, the a--rw
wi l l be followed. drV44Z4,
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Mr. Ted Shepard
HORSETOOTH WEST MASTER PLAN
DRAINAGE CONCEPT
March 4, 1988
Page 2
Q = CiACf
Q = Maximum Peak Rate - (C.F.S.) G
C = Runoff Coeff i c i en
i = Average Rain Intensities of in./hr.
Cf = Frequency Factor „,,,,I.�,G
A, r,�i Q
The runoff coefficients will vary from the historic factor due to type of /& I
uses. These factors when used in the calculations will reflect the City of
Fort Collins Storm!t Drainage criteria. Rain fall intensities will be deter-
mined from City of Fort Collins Storm Drainage IntensityACurves.
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Method -- The Master Plan indicates various land uses which will handle storm
drainage in various fashions. The single-family areas are intended to use
a combination of curb inlets and conduits to transport runoff East to the
drainage facility adjacent to Taft Hill. Primary detention for these two
major areas will occur at that facility prior to being- released down stream
a t h i s_tor-i-c_ ra tes\�_ Ar
0
The Neighborhood Center and the auto -related commercial area will provide de-
tention on site on hard surfaced parking areas prior to releasing at historic
rates through an inlet and conduit system to the facility at Taft Hill prior
to releasing down stream.
The school site, the child care and the multi -family areas will use combin-
ations of parking lot and landscape area -type detention and release through
swales, concrete channels, curbs and inlet and conduit systems. Runoff will
be transported to the facility at Taft Hill prior to being released down
stream.
0
Due to the locations of these�to
parcels from the common detention and
rc�
release area flows will be stageinimize the size of one facility and
providing the majority of t e detention being resolved on the individual
j� parcels will handle nuisance flows and prevent curb topping in storms from
two years through 100-year occurrences.
Sincerely yours, _
GEFROH HATTMAN I
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