HomeMy WebLinkAboutSOUTH FORT COLLINS VETERINARY CENTER PUD PRELIMINARY - 46 91 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPRELIMINARY STORM DRAINAGE
AND
EROSION CONTROL REPORT
FOR
SOUTH FORT COLLINS VETERINARY CENTER
OCTOBER 28, 1991
STEWART & ASSOCIATES, INC.
214 North Howes Street
Fort Collins, Colorado 80521
STEWAU&ALSSOCIATES
Consulting Engineers and Surveyors
October 28, 1991
Mr. Glen Schlueter
Storm Drainage Utility
City of Fort Collins
P.O. Box 580
Fort Collins, Colorado 80522-0580
Dear Glen:
This is the preliminary storm drainage and erosion control report for
South Fort Collins Veterinary Center proposed for Lot 7, Creger Plaza. It.
is located on the West side of South Mason Street approximately one_quarter
mile South of Horsetooth Road, and the address is 3801 South Mason Street.
Storm Drainage
The site is in the Mail Creek Drainage Basin. The site has 1.64 acres
and was originally a low area that could not be drained. When Creger Plaza
was developed in 1979 and South Mason Street was built, a 14"x23" oval storm
drain was constructed. The storm drain was sized to carry the runoff after
it has been detained on the site. There is an existing 15—inch concrete
pipe stubbed into the Southeast corner of Lot 7 for the discharge from the
detention pond.
There has been some fill material placed on Lot 7; and the remainder
of the lot is lower than the discharge pipe. Dr. Rainey Corbyn is proposing
to construct a veterinary hospital and dog and cat boarding facilities on
the lot. The enclosed grading plan depicts the proposed building and boarding
facilities. A detention/retention pond is proposed in the southern portion
of the lot. The detention pond has a required volume of 9500 cubic feet,
determined by the mass diagram. The bottom of .the pond will remain at
elevation 5030 which is two feet lower than the outlet pipe invert. The
high water line of the pond will be 5034; therefore, the detention capacity
is from the 5032 contour to the 5034 contour. A restriction plate will be
placed on the outlet pipe to restrict the discharge to 0.47 cubic feet per
second.
The owner and the landscape architect have developed a landscape plan
using xeriscape plant materials in the filled portion of the lot and leaving
the pond in a natural state using wetland vegetation such as sages, rushes
and reeds.
The dog and cat boarding facilities are both indoor and outdoor but
are completely covered by roof. The floor of that entire area slopes to
a trench drain that discharges into the sanitary sewer. There will be no
runoff from the boarding facility entering the storm water swales and the
pond. Therefore, there will not be a storm water quality issue.
James H. Stewart
and Associates, Inc.
214 N. Howes Street
P.O. Box 429
Ft. Collins, CO 80522
303/482-9331
Mr. Glen Schlueter
October 28, 1991
Page 2
Erosion Control
The site has been partially filled, with the remaining area left at the
original pond elevation. The part of the site at the original pond elevation
has little existing ground cover. The filled portion has moderate ground
cover. The prevailing winds are from the.west, and the site is protected
by the Burlington Northern Railroad which is seven feet above the bottom
of the pond. There is no storm drainage flowing onto this site. The borrow
area on the railroad.property catches any flow along the railroad and has
existing wetland plants. Mason Street has been raised to approximately five
feet above the bottom of the pond.
The development of the site will begin with imported fill to the site
for the building and parking lot areas. The building foundation will then
begin which will break up the wind erosion. The parking area grading and
curb installation will follow the building construction. Water erosion will
be mitigated by the retention portion of the pond acting as a permanent
sedimentation trap. As discussed previously, the lower two feet of the pond
will remain below the existing discharge pipe.
A rock filter will not be needed at the entrance to the existing dis—
charge pipe because of the sedimentation trap being two feet lower. This
will allow the Mason Street water to continue to flow through the walk under
drain and into the discharge pipe.
Care will be taken during the importation of the fill to clean up mud
tracked onto the Mason Street pavement.
The finished site will have several forms of ground cover. Part of
the landscaping will be xeriscape plant materials, part will be sod and part
will be wetland vegetation. The rest of the site will be hardsurfaced.
The drainage calculations and the grading and drainage plan are enclosed
as a part of this report. If you have any questions regarding this prelim— —
inary report, please call.
Sincerely,
a
Richard A. Rutherford, P. E. & L. S.
President
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