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FINAL DRAINAGE AND EROSION
CONTROL REPORT
WARDS REDEVELOPMENT
UNIVERSITY MALL PUD REPLAT NO.2
September 5, 2003
�V
J•R ENGINEERING
A Subsidiary of Westrian
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FINAL DRAINAGE AND EROSION
CONTROL REPORT
WARDS REDEVELOPMENT
UNIVERSITY MALL PUD REPLAT NO.2
September 5, 2003
Prepared by
JR ENGINEERING
2620 E. Prospect Rd., Suite 190
Fort Collins, Colorado 80525
(970)491-9888
Prepared for
GDA Real Estate Services
8301 East Prentice Avenue, Suite 210
Greenwood Village, Colorado 80111
(303)221-5500
Previous revision dates
October 3, 2000
February 23, 2001
September 19, 2001
January 16, 2002
Job Number 9059.03
I
September 5, 2003
Mr. Basil Hamdan
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80521
RE: Final Drainage and Erosion Control Report for Wards Redevelopment - Revised
' Dear Basil:
n
We are pleased to submit to you for your review and approval, this revised Final Drainage and
Erosion Control Study for the Wards Redevelopment. This revised report and plan incorporates
responses to Stormwater's review comments of October 9, 2001 and August 1, 2003. All
computations within this report have been completed in compliance with the City of Fort Collins
Storm Drainage Design Criteria.
We appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
Sincerely,
1
Michael Brake, PE, PIS
Director of Operations
Attachment
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TABLE OF CONTENTS
' PAGE
LETTER OF TRANSMITTAL
TABLEOF CONTENTS............................................................................................................... I
'
1. INTRODUCTION.................................................................................................................2
1.1 Project Description............................................................................................................
2
'
1.2 Purpose and Scope of Report ............................................................................................ 2
1.3 Design Criteria.................................................................................................................. 2
1.4 Master Drainage Plan and Related Drainage Reports.......................................................
2
'
2. EXISTING SITE DRAINAGE.............................................................................................
3
3. PROPOSED DRAINAGE PLAN.........................................................................................
3
3.1 Off -site Flow Routing.......................................................................................................
3
3.2 On -Site Flow Routing.......................................................................................................
4
'
3.3 Hydrologic Analysis of the Proposed Drainage Conditions ..............................................
3.4 Allowable Street Flow Capacities.....................................................................................
6
6
3.5 Storm Drainage Structure Design......................................................................................
6
'
4. WATER QUALITY..............................................................................................................
7
'
5. EROSION CONTROL..........................................................................................................
5.1 Erosion and Sediment Control Measures..........................................................................
7
7
5.2 Dust Abatement.................................................................................................................
7
5.3 Tracking Mud on City Streets...........................................................................................
8
5.4 Maintenance......................................................................................................................
8
5.5 Permanent Stabilization....................................................................................................
8
'
6. MISCELLANEOUS..............................................................................................................8
6.1 Variances...........................................................................................................................8
'
6.2 Irrigation Ditches...............................................................................................................
9
6.3 Maintenance Agreements..................................................................................................
9
'
7. REFERENCES......................................................................................................................9
APPENDIX A - HYDROLOGIC CALCULATIONS
APPENDIX B - STORM DRAINAGE STRUCTURE DESIGN
Final Drainage and Erosion Control Report Page i
Wards Redevelopment September 5, 2003
I
1. INTRODUCTION
' 1.1 Project Description
' The Wards Redevelopment is the redevelopment of the existing Montgomery Wards site
adjacent to the University Mall. This site contains approximately 6.6 acres. The proposed
redevelopment will include adding a new fagade to the building and upgrading the parking
lot and landscaping.
' The site is located in the southwest corner of Rutgers Avenue and South College Avenue, in
Fort Collins, Colorado. It is bounded by College Avenue on the east, the University Center
' on the south, Burlington Northern railroad tracks on the west, and an existing commercial
center on the north. The site lies in Section 23, Township 7 North, Range 69 West of the
' Sixth Principal Meridian, in the City of Fort Collins, Larimer County, Colorado. A vicinity
map is included after the Table of Contents of this report.
' 1.2 Purpose and Scope of Report
' This report defines the proposed drainage and erosion control plan for the proposed Wards
Redevelopment. The drainage plan includes consideration of all on -site and tributary off -site
' runoff.
1.3 Design Criteria
' This report and associated calculations were prepared to meet requirements established in the
' "City of Fort Collins Storm Drainage Design Criteria and Construction Standards"
(SDDCCS), dated May 1984 and updated January 1997. The new rainfall criteria as
' amended by Ordinance 42.1999 was used for the 10-year and 100-year design storms.
Runoff computations were made using the rational method. Where applicable, the criteria
established in the "Urban Storm Drainage Criteria Manual' (UDFCD), 1984, developed by
' the Denver Regional Council of Governments, has been utilized.
1.4 Master Drainage Plan and Related Drainage Reports
This site is included in the Spring Creek Major Drainage Basin and a report entitled "Spring
' Creek Master Drainageway Plan' was prepared by Engineering Professionals, Inc., in March
1988. It is not anticipated that the proposed redevelopment of the Wards site will have a
1
Final Drainage and Erosion Control Report page 2
' Wards Redevelopment September 5, 2003
' 3.
negative impact on the Spring Creek Major Drainage Basin, as the site is currently almost
entirely impervious. In fact, the redevelopment of this site will slightly reduce the runoff
with the proposed additional landscape areas.
A portion of this site was included in the "Drainage and Erosion Control Report, University
Center PUD", prepared by Bucher, Willis and Ratliff Corporation, and approved by the City
of Fort Collins on July 24, 1998.
EXISTING SITE DRAINAGE
The existing drainage for this site consists of the flow being split between the east and west
portions of the site. The flows from the eastern portion of the site enter three (3) existing
sump condition area inlets within the parking and drive area. Said inlets are conveyed to an
existing storm sewer system in College Avenue which outlets directly into Spring Creek.
The flows from the western portion of the site are conveyed westerly towards the railroad
tracks. Immediately adjacent to the west edge of the existing parking lot, there is an existing
depression/ponding area that the runoff enters. This depression acts as a sediment
basin/water quality pond. When this area fills with runoff, it overtops and the flows enter an
existing swale along the railroad tracks. The flows are then conveyed northerly in said swale
to the Sherwood Lateral.
The soil on this site is Nunn clay loam, which consists of nearly level soils on high terraces
and fans (USDA,1980). Pertinent characteristics of this soil include slow to medium runoff,
a slight hazard of wind erosion, and a moderate hazard of water erosion. Nunn clay loam is
categorized in Hydrologic Group C.
PROPOSED DRAINAGE PLAN
3.1 Off -site Flow Routing
No off -site flows enter this site.
Final Drainage and Erosion Control Report Page 3
Wards Redevelopment September 5, 2003
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3.2 On -Site Flow Routing
The site was graded so that stormwater runoff is directed away from the existing building and
the proposed building envelope. The flows are still routed as historically with the flows from
the eastern portion of the site conveyed to the existing area inlets and the flows from the
western portion of the site conveyed to the railroad swale and eventually into the Sherwood
Lateral.
A qualitative summarization of the drainage patterns within each sub -basin is provided in the
following paragraphs.
Runoff from Subbasin A is conveyed via roof drains and sheet flow across the rear
parking and drive area to the aforementioned depression along the western portion of
subject site. Said depression acts as a sediment basin/water quality pond/retention
pond. In the major storm event, said depression overtops and the flows enter the
existing swale along the east side of the railroad tracks, is diverted northerly and
conveyed in said swale to the Sherwood Lateral. The amount of runoff generated
from this basin does not change from historic amounts.
Runoff from Subbasin B is conveyed via sheet flow and gutter flow across the
existing parking and drive area north of the northwest corner of the existing building .
to the aforementioned depression along the western portion of subject site. Said
depression acts as a sediment basin/water quality pond/retention pond. In the major
storm event, said depression overtops and the flows enter the existing swale along the
east side of the railroad tracks, is diverted northerly and conveyed in said swale to the
Sherwood Lateral. The amount of runoff generated from this basin does not change
from historic amounts.
Runoff from Subbasin C are conveyed via sheet flow northerly to the existing
parking lot/property north of the Wards Redevelopment site. The amount of runoff
generated from this basin, a total of 0.01 acres, does not change from historic
amounts.
Runoff from Subbasin D is conveyed via sheet flow and gutter flow across the
existing parking and drive area to an existing sump condition area inlet in the access
drive to this site from College Avenue. Said area inlet is located in an existing low
area that acts as a small detention area as the release of flows is controlled by the
Final Drainage and Erosion Control Report Page 4
Wards Redevelopment September 5, 2003
capacity of the existing pipe in College Avenue, the size of the outfall pipe and the
size of the inlet. In the event that the area around said inlet overflows, a sidewalk
chase has been added to allow the flows to enter Subbasin G and be collected in the
existing area inlet. (The existing area inlets in Subbasins D, F, and G all interact to
provide collection for this site.)
Runoff from Subbasin E, the very northeast corner of the site, is conveyed via sheet
flow northerly to the existing parking lot/property north of the Wards Redevelopment
site. The amount of runoff generated from this basin did not change from historic
amounts.
Runoff from Subbasin F is conveyed via sheet flow and gutter flow across the
existing parking and drive area to an existing sump condition area inlet in the existing
parking lot just north of the southeast corner of subject site. Said area inlet is located
in an existing low area that acts as a small detention area as the release of flows is
controlled by the capacity of the existing pipe in College Avenue, the size of the
outfall pipe and the size of the inlet. In the event that the area around said inlet
overflows, a sidewalk chase has been added to allow the flows to enter Subbasin G
and be collected in the existing area inlet.
Runoff from Subbasin G is conveyed via sheet flow to an existing sump condition
area inlet in the existing parking lot. Said area inlet is located in an existing low area
that acts as a small detention area as the release of flows is controlled by the capacity
of the existing pipe in College Avenue, the size of the outfall pipe and the size of the
inlet. In the event that the area around said inlet overflows, a sidewalk chase has
been added to allow the flows to enter Subbasin D and/or F and be collected in the
existing area inlets.
Runoff from Subbasin H is conveyed via sheet flow to an existing low area in the
north side of the southerly access to the site. Historically runoff generated from this
portion of the property wass conveyed to Subbasin F area inlet via surface flow
through the low area. The new design will not change the historic drainage pattern.
The amount of runoff generated from this basin did not change from historic
amounts.
Final Drainage and Erosion Control Report Page 5
Wards Redevelopment September 5, 2003
' 3.3 Hydrologic Analysis of the Proposed Drainage Conditions
' The Rational Method was used to determine the 10-year and 100-year peak runoff rates for
each subbasin. Runoff coefficients were assigned utilizing Table 3-2 of the SDDCCS
' Manual. Rainfall intensity was based on the recently adopted design storm information for
Fort Collins. Details of the hydrologic calculations associated with each subbasin are
included in Appendix A. Table 3.1 provides a summary of the resulting peak flows for all
' subbasins and Design Points (DP's) associated with this site. Q101 in the table includes
applicable carry over flows.
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WARDS REDEVELOPMENT
Table 3.1- Drainage Summary Table
Design
Point
Tributary
Sub -basin
Area
(ac)
C (10)
C (100)
to (10)
(min)
to (100)
(min)
a(10)tot
(CIS)
0(100)tot
WS)
1
A
2.57
0.92
1.00
5.0
5.0
11.5
25.6
2
B
0.63
0.78
0.98
5.0
5.0
2.4
6.1
3
c
0.01
0.49
0.61
5.0
5.0
0.0
0.1
4
D
1.53
0.84
1.00
5.0
5.0
6.3
15.2
5
E
0.09
0.95
1.00
5.0
5.0
0.4
0.9
6
F
0.96
0.76
0.95
5.0
5.0
3.6
9.1
7
G
0.79
0.91
1.00
5.0
5.0
3.5
7.9
8
H
0.18
0.85
1.00
5.0
5.0
0.7
1.8
3.4 Allowable Street Flow Capacities
The proposed development of this site does not affect any street flows. Therefore, street flow
calculations are not included in this report.
3.5 Storm Drainage Structure Design
Storm drainage structures for this site include sidewalk culverts, curb cuts and existing area
inlets and storm drainage pipes. The capacity of sidewalk culverts and curb cuts was
determined using the computer program FlowMaster, which uses Manning's Equation.
FlowMaster results are included in Appendix B. The sidewalk culverts and curb cuts have
capacity to convey peak flows from the 10-year storm within criteria set fourth by the
SDDCCS Manual. 100-year flows will overtop the curb and follow the drainage paths as
indicated on the Drainage and Erosion Control Plan included in the back pocket of this
report.
Final Drainage and Erosion Control Report Page 6
Wards Redevelopment September 5, 2003
' 4.
WATER QUALITY
An existing depression along the western property line of this site acts as a sediment
basin/water quality pond/retention pond. As part of the redevelopment of this site, this area
will be cleaned up so it functions better. (Some small trees as well as brush, weeds and trash
will be removed. In addition, the grassy area at the west edge of the existing parking lot will
be re -graded to allow sheet flow into the existing depression (there is no curb and gutter) so
that more of the runoff is directed to this area.). In an on -site meeting with Glen Schlueter of
the City of Fort Collins' Stormwater Department, it was stated that this facility was adequate
for this site.
For the eastern portion of the site, the existing area inlets are being utilized and the parking
lot is being modified only slightly. Therefore, the implementation of new water quality
structures is not possible.
EROSION CONTROL
5.1 Erosion and Sediment Control Measures
Erosion and sedimentation will be controlled during construction by inlet filters, and seeding
and mulching or sodding in all landscape areas. These measures are designed to limit the
overall increase in sediment yield due to construction activities as required by the City of
Fort Collins. Erosion control calculations are not included, as the existing site grading is not
significantly changing, and all drainage structures are existing.
5.2 Dust Abatement
During the performance of the work required by these specifications or any operations
appurtenant thereto, whether on right-of-way provided by the City or elsewhere, the
contractor shall furnish all labor, equipment, materials, and means required. The Contractor
shall carry out proper efficient measures wherever and as necessary to reduce dust nuisance,
and to prevent dust nuisance that has originated from his operations from damaging crops,
orchards, cultivated fields, and dwellings, or causing nuisance to persons. The Contractor
will be held liable for any damage resulting from dust originating from his operations under
these specifications on right-of-way or elsewhere.
Final Drainage and Erosion Control Report page 7
Wards Redevelopment September 5. 2003
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6.
1
5.3 Tracking Mud on City Streets
It is unlawful to track or cause to be tracked mud or other debris onto city streets or rights -of -
way unless so ordered by the Director of Engineering in writing. Wherever construction
vehicles access routes or intersect paved public roads, provisions must be made to minimize
the transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. The
contractor will be responsible for clearing mud tracked onto city streets on a daily basis.
5.4 Maintenance
All temporary and permanent erosion and sediment control practices must be maintained and
repaired as needed to assure continued performance of their intended function. Straw bale
dikes will require periodic replacement. Sediment traps (behind straw bale barriers) shall be
cleaned when accumulated sediments equal approximately one-half of trap storage capacity.
Maintenance is the responsibility of the developer.
5.5 Permanent Stabilization
All soils exposed during land disturbing activity (stripping, grading, utility installations,
stockpiling, filling, etc.) shall be kept in a roughened condition by ripping or disking along
land contours until mulch, vegetation or other permanent erosion control is installed. No
soils in areas outside project street rights of way shall remain exposed by land disturbing
activity for more than thirty (30) days before required temporary or permanent erosion
control (e.g. seed/ mulch, landscaping, etc.) is installed, unless otherwise approved by the
Stonmwater Utility. Vegetation shall not be considered established until a ground cover is
achieved which is demonstrated to be mature and stable enough to control soil erosion as
specified in paragraph 11.3.10 of the City of Fort Collins Storm Drainage Construction
Standards.
MISCELLANEOUS
6.1 Variances
As stated in Section 4, Water Quality, water quality is being provided in the rear of the site
by an existing depression and the existing parking lot in the front of the site does not allow
for the creation of water quality provisions. It is proposed that water quality not be provided
in the existing parking lot in the front of the site due to the current lack of space for water
quality and due to the fact that the site does not currently provide water quality. This minor
Final Drainage and Erosion Control Report page g
Wards Redevelopment September 5, 2003
amendment will not significantly alter stormwater characteristics from present day
conditions, and it is not anticipated that public health, safety, and or welfare problems will be
created if this variance is approved. Therefore, due to the constraints of the exiting site, a
variance is requested for water quality. No other variances are required or are being
' requested for this site.
' 6.2 Irrigation Ditches
There are no irrigation ditches impacted by the development of this site. (The flow to the
' Sherwood Lateral is not changed.)
6.3 Maintenance Agreements
The developer will be responsible for the maintenance of all temporary and permanent
drainage structures.
' 7. REFERENCES
City of Fort Collins, "Storm Drainage Design Criteria and Construction Standards",
(SDDCCS), dated May 1984.
' 2. "Drainage and Erosion Control Report, University Center PUD", by Bucher, Willis
and Ratliff Corporation, and approved by the City of Fort Collins on July 24, 1998.
' 3. "Spring Creek Master Drainageway Plan" by Engineering Professionals, Inc., March
1988.
4. Soil Survey of Larimer County Area, Colorado. United States Department of
Agriculture Soil Conservation Service and Forest Service, 1980.
' 5. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated March 1969, and Volume 3, dated September
1992.
Final Drainage and Erosion Control Report page g
Wards Redevelopment September 5, 2003
0
APPENDIX A
HYDROLOGIC CALCULATIONS
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RUNOFF COEFFICIENTS & % IMPERVIOUS
LOCATION: WARDS REDEVELOPMENT
PROJECT NO: 9059.03
COMPUTATIONS BY: M. Brake
DATE: 9/5/2003
Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Streets, parking lots (asphalt)
Sidewalks (concrete)
Roofs.
Lawns (flat <2%, sandy soil),
Runoff
%
coefficient
Impervious
C
0.95
100
0.95
96
0.95
90
0.10
0
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 8525
SUBBASIN
DESIGNATION
TOTAL
AREA
(ee.)
TOTAL
AREA
(sq.ft)
ROOF
AREA
(sq.n)
PAVED
AREA
(sq.ft)
SIDEWALK
AREA
(sq.tt)
LANDSCAPE
AREA
(sq.ft)
RUNOFF
COEFF.
(C)
%
Impervious
A
2.57
111,900
70,300
38,000
0
3,600
0.92
91
B
0.63
27,443
0
22,062
0
5,381
0.78
80
C
0.01
436
0
200
0
236
0.49
46
D
1.53
66,647
0
58,206
0
8,441
0.84
87
E
0.09
3,920
0
3,920
0
0
0.95
100
F
0.78
33,977
0
32,512
0
1,465
0.91
96
G
0.79
34,412
0
32,947
0
1,465
0.91
96
H
0.18
7,841
0
6,875
0
966
0.85
88
TOTAL
6.58
:A
Eauations
- Calculated C coefficients & % Impervious are area weighted
C=I(Ci Ai) /At
Ci = runoff coefficient for specific area, Ai
Ai = areas of surface with runoff coefficient of Ci
n = number of different surfaces to consider
At = total area over which C is applicable; the sum of all Ai's
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JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
RATIONAL METHOD PEAK RUNOFF
(City of Fort Collins, 10-Yr Storm)
LOCATION: WARDS REDEVELOPMENT
PROJECT NO: 9059.03 -
COMPUTATIONS BY: M. Brake
DATE: 9/5/2003
10 yr storm, Cf 1.00
DIRECT RUNOFF
CARRY OVER
ITOTAL
REMARKS
Design
Point
Tributary
Sub -basin
-
A
(ac)
C Ct
tc
(min)
i
(irVhr)
Q (10)
(cis)
from
Design
Point
O (10)
(cfs)
0(10)tot
(ols)
1
A
2.57
0.92
5.0
4.87
11.54
11.5
2
B
0.63
0.78
5.0
4.87
2.40
2.4
3
C
0.01
0.49
5.0
4.87
0.02
0.0
4
D
1.53
0.64
5.0
4.87
6.28
6.3
5
E
0.09
0.95
5.0
4.87
0.42
0.4
6
F
0.78
0.91
5.0
4.87
3.47
1
3.5
7
G
0.79
0.91
5.0
4.87
3.52
3.5
8
H
0.18
0.85
5.0
4.87
0.74
0.7
Q=gCiA
Q = peak discharge (cfs)
C = runoff coefficient
Ct = frequency adjustment factor
i = rainfall intensity (in/hr) from City of Fort Collins IDF curve (4/16/99)
A = drainage area (acres) I = 41.44 J (10. ic)OJ'4
905903flowads
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
RATIONAL METHOD PEAK RUNOFF
(City of Fort Collins, 1 00-Yr Storm)
LOCATION: WARDS REDEVELOPMENT
PROJECT NO: 9059.03
COMPUTATIONS BY: M. Brake
DATE: 9/5/2003
100 yr storm, C1= 1.25
DIRECT RUNOFF
CARRYOVER
ITOTAL
REMARKS
Des.
Point
Area
Design.
A
(ac)
C Cf
tc
(min)
i
(hlhr)
O (100)
(CIS)
from
Design
Point
O (100)
(CIS)
O(100)tot
(CIS)
1
A
2.57
1.00
5.0
9.95
25.56
25.6
2
B
0.63
0.98
5.0
9.95
6.14
6.1
3
C
0.01
0.61
5.0
9.95
0.06
0.1
4
D
1,53
1.00
5.0
9.95
1522
152
5
E
0.09
1.00
5.0
9.95
0.90
0.9
6
F
0.78
1.00
5.0
9.95
7.76
7.8
7
G
0.79
1.00
5.0
9.95
7.86
7.9
6
H
0.18
1.00
5.0
9.95
1.79
1.8
Q=CiA
Q = peak discharge (cfs)
C = runoff coefficient
i = rainfall intensity (in/hr) from City of Fort Collins OF curve (4/16/99)
A = drainage area (acres) I = 84.682 / (10+ tcf'P'6
JR Engineering
WARDS REDEVELOPMENT
Table 3.1 - Drainage Summary Table
Design
Point
Tributary
Sub -basin
Area
(ac)
c (10)
c (100)
tc (10)
(min)
tc (100)
(min)
Q(10)tot
(cfs)
G(100)tot
(cfs)
1
A
2.57
0.92
1.00
5.0
5.0
11.5
25.6
2
B
0.63
0.78
0.98
5.0
5.0
2.4
6.1
3
c
0.01
0.49
0.61
5.0
5.0
0.0
0.1
4
D
1.53
0.84
1.00
5.0
5.0
6.3
15.2
5
E
0.09
0.95
1.00
5.0
5.0.
0.4
0.9
6
F
0.78
0.91
1.00
5.0
5.0
3.5
7.8
7
G
0.79
0.91
1.00
5.0
5.0
3.5
7.9
8
H
0.18
0.85
1.00
5.0
5.0
0.7
1.8
905903flow.xis, SU MMARY
r,
J
I
1
APPENDIX B
STORM DRAINAGE STRUCTURE DESIGN
1
JR Engineering
DETENTION VOLUME CALCULATIONS
Rational Volumetric (FAA) Method
100-Year Event
LOCATION: WARDS REDEVELOPMENT
PROJECT NO: 9059.03
COMPUTATIONS BY: M. Brake
DATE: 9/5/2003
Equations: Area trib. to pond =
1.53
Developed flow = Qp = CIA C (100) =
0.91
Vol. In = Vi = T C I A = T Qp Developed C A =
1:4
Vol. Out = Vo =K Qao T Release rate, Opo =
2.6
storage=S=Vi -Vo K=
0.9
Rainfall intensity from City of Fort Collins IDF Curve with updated (3.67") rainfall
acre
acre
cfs
(from fig 2.1)
Storm
Duration, T
(min)
Rainfall
Intensity, I
(inthr)
Op
(cfs)
Vol. In
Vi
(ft)
Vol. Out
Vo
(ft')
Storage
S
(ft)
Storage
S
(ac-ft)
5
9.95
13.9
4173
702
3471
0.08
10
7.77
10.9
6515
1404
5111
0.12
20
5.62
7.9
9430
2808
6622
0.15
30
4.47
6.2
11245
4212
7033
0.16
40
3.74
5.2
12549
5616
6933
0.16
50
3.23
4.5
13564
7020
6544
0.15
60
2.86
4.0
14394
8424
5970
0.14
70
2.57
3.6
15096
9828
5268
0.12
80
2.34
3.3
15706
11232
4474
0.10
90
2.15
3.0
16246
12636
3610
0.08
100
1.99
2.8
16729
14040
2689
0.06
110
1.86
2.6
17169
15444
1725
0.04
120
1.75
2.4
17571
16848
723
0.02
130
1.65
2.3
17943
18252
-309
-0.01
140
1.56
2.2
18289
19656
-1367
-0.03
150
1.48
2.1
18612
21060
-2448
-0.06
160
1.41
2.0
18916
22464
-3548
-0.08
170
1.35
1.9
19203
23868
-4665
-0.11
180
1.29
1.8
19474
25272
-5798 1
-0.13
Required Storage Volume: 7033 fts
0.16 acre-ft
905903flow.xls,FAA-100yr -Basin D
JR Engineering
DETENTION VOLUME CALCULATIONS
Rational Volumetric (FAA) Method
100-Year Event
LOCATION: WARDS REDEVELOPMENT
PROJECT NO: 9059.03
COMPUTATIONS BY: M. Brake
DATE: 9/5/2003
Equations: Area trib. to pond = 0.79
Developed flow = Qp = CIA C (100) = 0.91
Vol. In = Vi = T C I A = T Qp Developed C A = 0:7
Vol. Out = Vo =K QPo T Release rate, QPo = 2.6
storage = S = Vi - Vo K = 0.9
Rainfall intensity from City of Fort Collins IDF Curve with updated (3.67) rainfall
acre
acre
cis
(from fig 2.1)
Storm
Duration, T
(min)
Rainfall
Intensity, I
(in/hr)
Qo
(cfs)
Vol. In
Vi
(ft3)
Vol. Out
Vo
(ft)
Storage
S
(ft)
Storage.
S
(ac-ft)
5
9.95
7.2
2155
702
1453
0.03
10
7.77
5.6
3364
1404
1960
0.04
20
5.62
4.1
4869
2808
2061
0.05
30
4.47
3.2
5806
4212
1594
0.04
40
3.74
2.7
6480
5616
864
0.02
50
3.23
2.3
7004
7020
-16
0.00
60
2.86
2.1
7432
8424
-992
-0.02
70
2.57
1.9
7795
9828
-2033
-0.05
80
2.34
1.7
8110
11232
-3122
-0.07
90
2.15
1.6
8388
12636
-4248
-0.10
100
1.99
1.4
8638
14040
-5402
-0.12
110
1.86
1.3
8865
15444
-6579
-0.15
120
1.75
1.3
9073
16848
-7775
-0.18
130
1.65
1.2
9265
18252
-8987
-0.21
140
1.56
1.1
9443
19656
-10213
-0.23
150
1.48
1.1
9610
21060
-11450
-0.26
160
1.41
1.0
9767
22464
-12697
-0.29
170
1.35
1.0
9915
23868
-13953
-0.32
180
1.29
0.9
10055
25272
-15217
-0.35
Required Storage Volume: 2061 ft3
0.05 acre-ft
905903flow.xis,FAA-100yr -Basin G
JR Engineering
1
1
1
1
DETENTION VOLUME CALCULATIONS
Rational Volumetric (FAA) Method
100-Year Event
LOCATION: WARDS REDEVELOPMENT
PROJECT NO: 9059.03
COMPUTATIONS BY: M. Brake
DATE: 9/5/2003
Equations: Area trib. to pond = 0.96
Developed flow = Qp = CIA C (100) = 0.90
Vol. In = Vi = T C I A = T Qo Developed C A = 0.9
Vol. Out = Vo =K QPo T Release rate, Oao = 2.6
storage = S = Vi - Vo K = 0.9
Rainfall intensity from City of Fort Collins IDF Curve with updated (3.67') rainfall
acre
acre
cfs
(from fig 2.1)
Storm
Duration, T
(min)
Rainfall
Intensity, I
(in/hr)
OD
(cfs)
Vol. in
VI
(ft)
Vol. Out
Vo
(fe)
Storage
S
(ft)
Storage
S
(ac-ft)
5
9.95
9.0
2687
702
1985
0.05
10
7.77
7.0
4194
1404
2790
0.06
20
5.62
5.1
6070
2808
3262
0.07
30
4.47
4.0
7239
4212
3027
0.07
40
3.74
3.4
8078
5616
2462
0.06
50
3.23
2.9
8731
7020
1711
0.04
60
2.86
2.6
9266
8424
842
0.02
70
2.57
2.3
9718
9828
-110
0.00
80
2.34
2.1
10110
11232
-1122
-0.03
90
2.15
1.9
10457
12636
-2179
-0.05
100
1.99
1.8
10769
14040
-3271
-0.08
110
1.86
1.7
11052
15444
-4392
-0.10
120
1.75
1.6
11311
16848
-5537
-0.13
130
1.65
1.5
11550
18252
-6702
-0.15
140
1.56
1.4
11773
19656
-7883
-0.18
150
1.48
1.3
11981
21060
-9079
-0.21
160
1.41
1.3
12176
22464
-10288
-0.24
170
1.35
1.2
12361
23868
-11507
-0.26
180
1.29
1.2
12536
25272
-12736
-0.29
Required Storage Volume: 3262 W
0.07 acre-ft
905903flow.xis,FAA-100yr -Basin F & H
' Worksheet
Worksheet for Circular Channel
Project Description
'
Project File
untitled.fm2
Worksheet
Existing Pipe Assumption
Flow Element
Circular Channel
Method
Manning's Formula
Solve For
Full Flow Capacity
Input Data
Mannings Coefficient 0.013
'
Channel Slope 0.5000 %
Diameter 12.00 in
'
Results
1
1
C
r
Depth
1.00
ft
Discharge
2.52
cfs
Flow Area
0.79
ft2
Wetted Perimeter
3.14
ft
Top Width
0.00
ft
Critical Depth
0.68
ft
Percent Full
100.00
Critical Slope
0.007704 ft/ft
Velocity
3.21
fUs
Velocity Head
0.16
ft
Specific Energy
FULL
ft
Froude Number
FULL
Maximum Discharge
2.71
cfs
Full Flow Capacity
2.52
cfs
Full Flow Slope
0.005000 ft/ft
t07103
03:58:01 PM
FlowMaster v5.15
Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1