HomeMy WebLinkAboutPACE MEMBERSHIP WAREHOUSE INC PUD - PRELIMINARY - 76-88B - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORT• 0
INC
Engineering Consultants
2900 South College Avenue
Fort Collins, Colorado 80525
303/226-4955
September 26, 1988
Ms. Susan Hayes
City of Fort Collins
P.O. Box 580
Fort Collins, Colorado 80522
RE: PRELIMINARY DRAINAGE REPORT FOR THE PACE MEMBERSHIP
WAREHOUSE
Dear Susan:
The PACE Membership Warehouse site is located 1/2 mile south of
Harmony Road on the west side of U.S. Hwy. 287 in Larimer County,
Colorado. (see the following vicinity map). Annexation is cur-
rently bringing this site within City limits. More specifically
this location is in the middle east side of Section 2, Township 6
North, Range 69 West of the 6th Principal Meridian.
This site currently is occupied by a residence with a large open
grassed field between it and College Avenue. The site slopes at
about 1% to 3%+ in a southeasterly direction except for a major
drainage way that exists just south of this property which
creates some slopes greater than 3%.
This property along with the above mentioned drainageway are ex-
plained in the Fossil Creek Drainage Basin Master Drainage way
Planning Study, by Simons, Li and Associates, Inc., August, 1982.
This site, being directly adjacent to the major drainageway and
per City staff comment during the conceptual review, is not
required to have detention because it is thought that the onsite
flows would peak much earlier than the total basin peak.
Onsite flows are separated into two areas. The first, Basin "A",
will drain directly into the major drainageway for the Fossil
Creek Drainage Basin, as previously explained. The second area,
Basin "B", will have some parking lot detention (see following
calculation sheet) but ultimately, through a pipe system, will
empty into the same drainageway as explained above. An emergency
overflow area, located in the southeast corner of this site, is
to be constructed for any excess flows or flows due to plugging
of the inlets.
Other Offices: Vail, Colorado 303/476-6340 • Colorado Springs, Colorado 303/574-3504
0 •
Offsite flows are identified by two basins, 02 and 01. Basin 01
is a small area west of this site that is a part of the Bur-
lington Northern R.R. right-of-way. These flows will simply pass
through Basin "A" and directly into the major drainageway. Basin
02 is north of this site and will drain into the parking lot
detention pond located in Basin "B". The flows will either pass
through the storm system or go over the emergency spillway if on -
site detention capacities are reached (100 year design storm +).
If the flows go over the spillway they would be draining as they
did historically.
All onsite drainage facilities will be sized during final design
to reflect the above drainage pattern and city of Fort Collins
criteria to promote safe stormwater drainage through the
property.
Sincerely,
RBD, Inc.
Brian Cole, P.E.
Project Engineer
Lloyd G. McLaughlin
Project Manager
I
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*
UASS P]sGPAM METHOD
for
DEVENTION VOLUMES
COMMENTS, 100 YEAR STORi'l
TIAXIMUM ALLOWABLE RELEASE (CFS) = 5.3
RATIONAL EQUATION: Q = CIA
C = � /i(area>
TIME OF CONCENTRATION = 42.84
TIME
CA
I
INFLOW
OUTFLOW
STORAGE
(min)
(in/hr)
(cu ft)
(cu ft)
(cu ft)
(ac ft)
____________________________________________________________________
5
6.16
9
16632
1590
15042
0.345316
10
6.16
7.3
26980.8
3180
23800.8
0.546391
15
6.0
6
33264
4770
28494
0.654132
20
6.16
5.2
38438.4
6360
32078.4
0.736418
25
6.16
4.6
42504
7950
34554
0.793250
30
6'16
4.15
46015.2
9540
36475.2
0.837355
35
6.16
3.8
49156.8
11130
38026.8
0.872975
40
6.16
3.5
51744
12720
39024
0.895867
45
6.16
3,25
54054
1431O
39744
0.912396
50
6.16
3
55440
15900
39540
0.907713
55
6.16
2.8
56918.4
17490
39428.4
0.905151
60
6.16
2.6
57657.6
19080
38577.6
0.885619
To.
6.16
2.3
59505.6
22260
37245,6
0.855041
30
6.16
2.05
60614'4
25440
35174.4
0.807493
90
6'11
1.85
61538.4
28620
32919.4
0.755702
100
6.16
1.7
62832
31800
31032
0.712306
1]0
6.16
1,55
63016.8
34980
28036.8
0.643636
U 120
6.16'
1.45
64310.4
381%
26150.4
0.600330