HomeMy WebLinkAboutTIMAN PUD PARCEL "A" - PRELIMINARY - 26-88C - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT•
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Engineering Consultants
2900 South College Avenue
Fort Collins, Colorado 80525
303/226-4955
April 4, 1988
Susan Hayes
City of Fort Collins
Storm Drainage Department
P.O. Box 580
Fort Collins, Colorado 80522
RE: TIMAN P.U.D. - PARCEL A - PRELIMINARY DRAINAGE REPORT
Dear Susan:
On behalf of Jeff Timan, RBD Inc. submits the following Prelimi-
nary Drainage Report for Parcel A of the Timans P.U.D.
Site Location
Parcel A of the Timan P.U.D. is located along the northern
property line adjacent to Skyway Drive. It is bounded on the
east by a proposed private drive, on the south by the under-
developed portion of the P.U.D. and on the west by the Foothills
Gateway property.
Existing Drainage
The site currently slopes steeply to the east at a slope of 8 to
10 percent. The area has been used historically for pasture.
The site drains to a low area along the State Highway 287 roadway
embankment. The area is drained by a 24 inch RCP culvert which
runs under the highway and commercial areas on the opposite side
of the highway. No offsite flows are anticipated through this
parcel.
Proposed Drainage
The proposed facility will include a large warehouse facility,
two parking areas, a private access drive and landscaping.
Detention will be facilitated using the forementioned low area
below and east of the private drive. Onsite flows will be
diverted to this area through a system of area inlets, storm
drain piping, grass and rip -rapped swales and curb and gutter.
Other Offices: Vail, Colorado 303/476-6340 • Colorado Springs, Colorado 303/574-3504
The entrance to the 24 inch outlet will be redesigned, in order
to limit outfall to the required rate.
Conclusion
Calculations which substantiate the proposed approach appear in
the attached Appendix. All calculations reflect use of the City
of Fort Collins Storm Drainage Criteria. Detailed calculations
for the sizing of culverts and the design of outlet works will be
submitted with the Final Drainage Report. The approach outlined
in this report should provide for the efficient and safe con-
veyance of drainage through the site.
Sincerely,
RBD, Inc.
Stan A. Myers, P.E.
cc: 272-001
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APPENDIX
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CLIENT _ri 1A AN _ JOB NO. ;;?�
PROJECT T 1 t.1 k k1 PADEL A CALCULATIONS FOR PA'hS F Caue C'Gt`7r,
MADE BY DATE CHECKED BY DATE _ SHEET OF
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DATE: 3Z24Z88
PROJECT: TIMAN
JOB NUMBER:
DESIGN ENGINEER:
BASIN DESIGNATION
272-001
5AM
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DETERMINE EXISTING D FOR 2 YEAR STORM
HISTORIC RUNOFF COEFFICIENT .25
BASIN SLOPE: 4.2 PERCENT
BASIN LENGTH 920 FEET
AREA: 4.16 ACRES
HIST TC = 1.B7*(I.1-( 1 + .25
)>*SORROOT 920 >>Z 4.2
1/3 = 29.89596 MINUTES
HISTORIC RAINFALL INTENSITY: 1.464578 INCHES/HOUR
HISTORIC OUTFALL: 1.520161 CUBIC FEET PER SECOND
DETERMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS
DEVELOPED STORM: 100
DEVELOPED RUNOFF COEFFICIENT
ECFAE
4.16
.63
DURATION
MIN
10
15
30
45
60
90
120
180
360
_.276
GROSS VOL.
CO. FT.
9563.115
13798.51
17572.46
24294.81
29189.16
30791.29
33257.95
33965.57
36796.03
41041.73
YEAR STORM
.63
1.25
OUTFLOW VOL.
CU. FT.
456.9483
913.8966
1370.845
2741.69
4112.535
5493.38
8225.07
10966.76
16450.14
32900.28
DETENTION VOL.
CU. FT
8566.186
12884.62
16201.62
21553.12
25076.62
25297.92
25032.88
22998.81
20345.89
8141.449
REQUIRED DETENTION VOLUME IS 25297.92 CU. FT. OR
.5807602 ACRE FEET
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