HomeMy WebLinkAboutDrainage Reports - 02/16/1989.t
a/i41/8y
TMIfC
Engineering Consultants
2900 South College Avenue
Fort Collins, Colorado 80525
303/226-4955
January 10, 1989
Ms. Susan Hayes
Storm Drainage Department
City of Fort Collins
P.O. Box 570
Fort Collins, Colorado 80522
RE: FINAL DRAINAGE REPORT FOR THE THIRTEENTH FILING OF THE
CENTRE FOR ADVANCED TECHNOLOGY
Dear Susan:
The Thirteenth Filing of the Centre for Advanced Technology is
located in the area between the Eleventh Filing and Sixth Filing,
see Final Grading and Drainage Plan. This area is located near
the middle of the south half of Section 23, Township 7 North,
Range 69 West of the 6th Principal Meridian.
This report is supplementary to the Final Drainage Report for the
Eleventh Filing of the Centre for Advanced Technology, by RBD,
Inc. Engineering Consultants, September 6, 1988. The reader is
urged to review the above reference in order to get a complete
picture of the site drainage. The above report considers the
Thirteenth Filing to be a part of the preliminary parcel "U".
The Thirteenth Filing has minor changes from the preliminary
submittal, as part of parcel "U" but the changes do not sig-
nificantly change the drainage approach. The drainage approach
included a large parking lot detention pond created for the
development of Third, Sixth and Eleventh Filings and the rest of
Parcel "U". The revised Grading Plan shows some minor
adjustments, but the pond information remains the same.
Since the construction drawings for Eleventh Filing will also in-
clude the construction drawings for Thirteenth Filing, City staff
requested an additional plan. This plan was entitled the
"Thirteenth Filing Temporary Grading and Drainage Plan", and is
attached to this report for the readers convenience. This plan
is created to establish a temporary detention pond for the
drainage area if the Thirteenth Filing is built prior to Eleventh
Filing. It also defines the parking lot area which will be in -
Other Offices: Vail, Colorado 3031476-6340 • Colorado Springs, Colorado (719) 598-4107
n
J
stalled with the Thirteenth Filing. This would mean that Third,
Sixth, and Eleventh Filings undeveloped portion of Parcel "U" and
undeveloped Eleventh Filing will drain to and detained in the
temporary detention pond. The pond and allowable release rate
calculations are attached. This plan also shows that storm drain
system will be constructed with the Thirteenth Filing.
The temporary pond was sized for a required 1.22 ac-ft. of volume
and a maximum release rate of 1.7 cfs, based on City specifica-
tion of using the rational formula for a 100 year design storm.
This would create a maximum pond depth of 3.81 ft. Outfall will
be limited by an orifice plate attached to the outlet pipe.
This project was designed according to City of Fort Collins
requirements and specifications.
Sincerely,
RBD, In .
Stan A. Myers, P.E.
Brian H. Cole, P.E.
[17
0 24933
.p+
e
�aral;
'•�' i_
VICINITY MAP NO SCALE'
PROSPECT AVENVE IUDDD
DDD
�D
LPRINO CREE%
2 3
� `AAillfA N0.1 C `
SITE LOCATION W
W
S V
T 1
Ay (NVE s Y9 2
0(NTAC � o
Y �
x
y OA L
O D
Y
OT. \r:i ROAD
DAI'F-.-
PROJECT: CAT 13TH
g3B NUMBER: 035-078
-DES4GN
BASIN DESIGNATION =
TOTAL SITE PLUS FILING 3 AND 6 WITH -PARCEL "U" UNDEVELOPED
Z_T_"_kNLw t3twou"spuzo> V I L. 1 N " %%
DETERMINE EXISTING 0 FOR 2 YEAR STORM
9
HISTORIC RUNOFF COEFFICIENI
BASIN SLOPE.- .5 --
BASIN LENGTH l000
AREA: 9.640001 ACRES
HIST TC = 1.97*0.1-( 1
))*SQRROOT loot)
113 zu -
.2
PERCENT
FEET
.2
67.03894 MINUTES
HISTORIC RAINFALL INTENSITY: .8807274 INCHES/HOUR
i 69 nnA -----
DETFRMINATION OF DETENTION POND VOLUME FOR DEVELOPED CONDITIONS
DEVELOPED STORM: 100 YEAR STORM
_DqvsLQR-FD ENT-
CCFAG.- .51 -- - - -- * ,
6.1455
DURATION
GROSS VOL.
OUTFLOW VOL.
--MI44-
F-T� -
- - -CU" FT.
5
16914.09
509.4127
10
25884.85
1018.825
15
-4528.238
3f.)
45575.03
3056.476
45
54756.41
4584.715
60-
-57743wl2----
-61-12.953
90
62389.12
9169.43
120
63716.55
12225.91
ISQ
69026.26 --
10308.86
36o
76990.92
36677.72
DETENTION VOL.
CU.- FT
16304.6a
24866.02
31436.23
42318.55
50171.69
516730. 17
5S219. 69
51490.64
50687.4
40313.1.
RFPHTRED DETENT-1-QN--VGLUMF--IS- -- - --57,219.69 -- CU. F'l . OR
1.221756 ACRE FEET