HomeMy WebLinkAboutDrainage Reports - 05/04/1987RMINC
Engineering Consultants
2900 South College Avenue
Fort Collins, Colorado 80525
303/226.4955
May 4, 1987
Ms. Susan Hayes
City of Fort Collins
P.O. Box 570
Fort Collins, Colorado 80522
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RE: FINAL DRAINAGE REPORT FOR THE CENTRE FOR ADVANCED TECHNOLOGY
SECOND FILING
Dear Susan:
This third filing of the Centre for Advanced Technology is lo-
cated in the Southwest corner of the future intersection of Cen-
ter Avenue and Meadowlark Avenue. The west boundary of this site
is the New Mercer Ditch. The property is located in the South-
west Quarter of Section 23, Township 7 North, Range 69 West of
the 6th Principal Meridian.
The site currently is covered with natural Colorado field grasses
and slopes to the southeast at less than 22.. ( A field road .,,, tnE�
meanders through the site. Along with the New Mercer Ditch that M,v 537 hGrc,,
borders to the West.) When fully developed this property will
consist of business/office buildings, parking areas and
landscaped areas (see plan).
Using the most current City of Fort Collins criteria, and the ra-
tional formula a 2 year historic maximum release rate was calcu-
lated to be 0.51 cfs. With this release rate, a required pond
volume of 0.34 acre-feet was determined (see Supplementary Cal-
culation sheet). The pond and site grading are shown on the at-
tached drainage plan. The pond will temporarily discharge into
an overland swale which will direct flows into the Meadowlark
Avenue drain proposed in the Centre for Advanced Technology Spe-
cial Improve 7t District.
WAit,,C la 141S
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Other Offices: Vail, Colorado 303/476-6340 • Colorado Springs, Colorado 303/574-3504
When this site drainage and grading plan and design is
implemented, drainage flows will pass through the streets and
parking areas to the pond in a safe and controlled manner.
Sincerely,
RBD, Inc. E.
Stan A. Myers, P.E. r
Project Manager
*
DATE: 5/1/87
PROJECT: C"A, I.
JOB NUMBER:
DESIGN ENGINEER:
BASIN DESIGNATION =
0J5-02R
NICKEL
DETERMINE E:I57IN8 Q FOR 2 YEAR STORM
HISTORIC RUNOFF COEFFICIENT .2
BASIN SLOPE: .5 ^ PERCENT
BASIN LENGTH 470 FEET
AREA: 7.V57 AF�RES
HlST TC = 1
>)*SQRROOT 470
HISTORIC RAINFALL INTENSITY:
HISTORIC OUTFALL: ^5096791
* .2
))/ "5
45.95959 MINUTES
1"238889 INCHES/HOUR
CUBIC FEET PER SECOND
DETERMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS
DEVELOPED STORM: 1o3
DEVELOPED RUNOFF COEFFICIENT
CCFAC
2.057
"666�
D|/RA/IvN
MIN
5
10
15
30
45
60
90
120
180
360
*
1"712452
GROSS VOL,
CU. FT"
4685"27
7212.85
9185,595
12699°55
15257°95
l6090"2
177B4"82
17754"71
19234.27
21453"6
YEAR STORM
"666
1^25
OUTFLOW VOL"
CU. FT"
152^9037
305.8074
458^7111
917"4272
1376^133
1834"845
2752.267
3669.689
5504"533
11809^o7
*
DETENTION VOL"
CU. FT
4532"366
69V7°042
8726.684
11782^1J
138B1"B2
14255,36
14632.55
14085.02
13729"73
10444^s4
RE8UIRED DETENTION VOLUME IS 14632.55 CU, FT" OR
"5159171 ACRE FEET
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