HomeMy WebLinkAboutCSU SOUTH DORMITORY - SITE PLAN ADVISORY REVIEW - 50-02A - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTTRAPEZOIDAL CHANNEL FOR OVERFLOW
-Channel
New
Mature Channel
Input Values
Ca1c. Values
Input Values
Catc. Values
1
BottomWidth w (ft)
10
1
BottomWidth w (ft)
10
2
Left Side Slope z (ftfft)
4
2
Left Side Slope z (ft/ft)
4
3
Right Side Slope z (ft/ft)
4
3
Right Side Slope z (ft/ft)
4
4
n
0.03
4
n
0.04
5
Normal Depth y (ft)
1.78
5
Normal Depth y (ft)
2.05
6
S (f fft)
0.0060
0.0060
6
S (ft/ft)
0.0060
0.0060
7
Area of Flow
30.47
7
Area of Flow (sf)
37.31
8
Hydraulic Radius
1.23
8
Hydraulic Radius
1.39
9
Hydraulic Depth
1.26
9
Hydraulic Depth
1.41
10
O (cfs)
134.95
10
Q cfs)
133.89
11
V (fps)
4.43
11
V (fps)
3.59
12
Top Width (ft)
24.24
12
Top Width (ft)
26.4
13
Froude Number
0.70
13
Froude Number
0.53
14
Required Freeboard (ft)
1
14
Required Freeboard ft
1
15
Total Top Width
32.24
15
Total Top Width
34.4
5naldrainage The Engineering Company 2/6/2003
POND AND CHANNEL OVERFLOW CACULATIONS
From Rectangular sharp Crested Weir Equation:
Q = CLHA(3/2)
Q = discharge (cfs)
C = discharge coefficient
L = effective length of crest (ft)
H = measured head (ft)
Pond A
Input values Calc. values
Q = 7.38
C = 2.7
H = 0.5
L = 7.73
Pond B
Input values Calc. values
Q =
12.61
C =
2.7
H =
0.67
L =
8.52
Pond C
Input values Calc. values
Q =
133
C =
2.7
H=
1
L =
49.26
Overflow into channel
Input values Calc. values
Q = 133
C = 2.7
H = 1.2
L = 37.47
detention
Pond C - Basin C
storage volume = Max(Vin-Vout)
discharge rate = 0.91 CFS
Storm
Duration
(min)
Rainfall
Intensity
in/hr)
Runoff
Volume
003)
Outflow
Volume
ft"3)
Storage
Volume
(ft43)
Storage
Volume
acre-ft
5
9.95
6925.20
204.75
6720.45
0.15
10
7.72
10746.24
409.50
10336.74
0.24
15
6.52
13613.76
614.25
12999.51
0.30
20
5.60
15590.40
819.00
14771.40
0.34
25
1 4.90
17330.40
1 1023.75
16306.85
0.37
30
4.52
18875.52
1228.50
17647.02
0.41
40
3.74
20824.32
1638.00
19186.32
0.44
50
3.23
22480.80
2047.50
20433.30
0.47
60
2.86
23886.72
2457.00
21429.72
0.49
70
2.60
25334.40
2866.50
22467.90
0.52
80
2.40
26726.40
3276.00
23450.40
0.54
90
2.20
27561.60
3685.50
23876.10
0.55
100
2.05
28536.00
4095.00
24441.00
0.56
t20
1.85
30902.40
4914.00
25988.40
0.60
detention volume needed + WQ volume
= 0.60 + 0.08 0.68 acre-ft.
Total required volume =
n.t.n .. 0rnuWe
Contour
Elevation
(ft)1(515
Area
Volume
(af)
Cumulative
Volume
(of)
Cumulative
Volume
(acre-ft
5015.75
5016
239
19.91666667
19.92
0.00
5017
2453
1152.560248
1172.48
0.03
5018
5112
3702.049655
4874.53
0.11
5019
8165
6579.203293
11453.73
0.26
5020
12960
10470.60236
21924.33
0.50
5020.45
2086917541.2104341
29465.541
0.68
5021.45
Top of Freeboard
detention
Pond B - Basin B
storage volume = Max(Vin-Vout)
discharge rate = 0.15 CFS
n�e..�r..., e.....wea
Storm
Duration
(min)
Rainfall
Intensity
(inlhr)
Runoff
Volume
(ft"3)
Outflow
Volume
ftA3
Storage
Volume
(ftA3)
Storage
Volume
(acre-ft)
5
9.95
3783.49
33.75
3749.74
0.09
10
7.72
5871.06
67.50
5803.56
0.13
15
6.52
7437.69
101.25
7336.44
0.17
20
5.60
8517.60
135.00
8382.60
0.19
25
4.98
9468.23
168.75
9299.48
0.21
30
4.52
10312.38
202.50
10109.88
0.23
40
3.74
11377.08
270.00
11107.08
0.25
50
3.23
12282.08
337.50
11944.58
0.27
60
2.86
13050.18
405.00
12645.18
0.29
70
2.60
13841.10
472.50
13368.60
0.31
80
2.40
14601.60
540.00
14061.60
0.32
90
2.20
15057.90
607.50
14450.40
0.'
100
2.05
15590.25
675.00
14915.25
0.34
120
1.85
16883.10
1 510.00
1 16073.10
1 0.37
Total required volume = detention volume needed + WO volume
0.37 + 0.04 0.41 acre-ft.
Contour
Elevation
ft
Area
A
Volume
(cf)
Cumulative
Volume
(of)
Cumulative
Volume
(acre-ft)
5014.92
4.56
4.56
0.00
5015
171
5016
4150
1721.135755
1725.70
0.04
5017
5753
4929.733318
6655.43
0.15
5018
7460
6588.04526
13243.47
0.30
5018.5
10255
4410.259887
17653.73
6.41
5019.5
TOP OF FREEBOARD
detention
Estimated Detention Pond Volume Required
Ponds sized to capture the developed 100 year flow and release at
the 2-year historic discharge for the entire basin
Inflow Volume - CIAT
Outflow volume = KQT
K - outflow adjustment factor
K=.75
Pond A - Basin A
storage volume = Max(Vin-Vout)
discharge rate = 0.15 CFS
Storm
Duration
(min)
Rainfall
Intensity
(in/hr)
Runoff
Volume
(f A3)
Outflow
Volume
(ftA3)
Storage
Volume
(ft"3)
Storage
Volume
(acre-ft)
5
9.95
2214.50
33.75
2180.75
0.05
10
7.72
3436.37
67.50
3368.87
0.08
15
6.52
4353.32
101.25
4252.07
0.10
20
5.60
4985.40
135.00
4850.40
0.11
25
4.98
5541.81
168.75
5373.06
1 0.12
30
4.52
6035.90
202.50
5833.40
0.13
40
3.74
6659.07
270.00
6389.07
0.15
50
3.23
7188.77
337.50
6851.27
0.16
60
2.86
7638.35
405.00
7233.35
0.17
70
2.60
8101.28
472.50
7628.78
0.18
80
2.40
8546.40
540.00
8006.40
0.18
90
2.20
8813.48
607.50
8205.98
0.19
100
2.05
9125.06
675.00
8450.06
0.19
120
1.85
9W1.78
810.00
9071.78
0.21
Total required volume = detention volume needed + WO volume
0.21 + 0.02 0.23 acre-ft.
botantinn PmvidM
Contour
Elevation
(ft)
Area
(
Volume
(�
Cumulative
Volume
(�
Cumulative
Volume
(acre-ft)
5016
0
5017
3831
1277
1277.00
0.03
5018
5428
4606.372368
5883.37
0.14
5019
7594
6480.766145
12364.14
0.28
5019.5
7594
3797
16161.14
0.37
5020.5
TOP OF FREEBOARD
m m m m m m
DISCHARGE CALCULATIONS
Q = CIA
BASIN
Composite
C
100-yr
Composite
C
Area
(acres)
Rainfall Intensity
Peak Runoff
2 YEAR
(in/hr)
10 YEAR
(in/hr)
100 YEAR
(in/hr)
2 YEAR
(cfs)
10 YEAR
(cfs)
100 YEAR
(cfs)
A
0.61
0.76
0.98
2.85
1 4.87
9.95
1.69
2.89
7.38
B
0.63
0.78
1.62
2.85
4.87
9.95
2.89
4.94
12.61
C
0.82
1.00
2.32
.85
4.87
9.95
5.43
9.27
23.08
Overall Basin
0.71
0.89
4.91
f2.85
4.87
9.95
10.00
17.09
43.65
Historic Basin
0.21
026
4.91
.19
2.04
1 4.16
1.21
2.08
5.30
M M M
toc
M M M M M M M
TIME OF CONCENTRATION / INTENSITY CALCULATIONS
Time of Concentration (for overland flow) = 1.8 ( 1.1 - C)LA0.5 / (SA0.33)
Time of Concentration (for channelized flow) = Basin Length / (Velocity, A 80)
Intensity
Basin
Route Descrip
Type
Flow Length
Slope
Overland
Time (Ti)
Channel
Time (Tt)
Total Time
Tc Check Tc
2 yr
10 yr
100 yr
ft.(percent)
"C"
min
Vel. f
min
TOC min
L/180 +10
in./hr.
in./hr.
in./hr.
A
From rooftop
roof
into detention pond A
Due to short
flow length,
minumum of
Tc = 5 min
5
2.85
4.87
9.95
B
From rooftop
roof
Into detention pond B
Due to short flow length,
use minumum
of Tc = 5
min
5
2.85
4.87
9.95
C
From southwest
side of parking lot
Paved
383
4.0
4
2.4
to detention pond C
sheet flow
2
5
2.85
4.87
9.95
Overall Developed
From southwest
Basin
side of parking lot
Paved
to detention pond C
sheet flow
Due to short flow
length,
use minumum
of Tc = 5
min
5
2.85
4.87
9.95
Overall Historic
From south east
Overland
450
2.0
0.2 27.3
Basin
side of property,
pasture
336
1.0
T.87.0
east
34
34
1.19
2.04
4.16
Page 1
' BASIN DESCRIPTION
' Basin A Sub -basin draining to north detention pond.
Basin B Sub -basin draining to the detention pond west of the building
Basin C Sub -basin for the majority of the parking lot.
1
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COMPOSITE C VALUE CALCULATIONS - Major Drainage Basins
C VALUES: (FROM TABLE 3-1 OF URBAN DRAINAGE CRITERIA MANUAL)
2 YEAR
Historic / Lawns
0.20
Paved Streets
0.95
Roofs
0.95
Walks
0.95
COMPOSITE C VALUE = (c1A1 +c2A2 + c2A3...... ) / A
BASIN
AREA
IN:
100-yr
Composite
C
Ag. / Grass
(acres)
Paved
Streets
(acres)
Roofs
(acres)
Walks
(acres)
TOTAL
AREA
(acres)
Compsite
C
A
0.45
0.00
0.35
0.18
0.98
0.61
0.76
B
0.70
0.36
0.35
0.21
1.62
0.63
0.78
C
0.40
1.86
0.00
0.06
2.32
0.82
1.00
Overall Basin
1.54
2.22
0.70
0.45
4.91
0.71
0.89
Historic Basin
4.86
0.00
0.05
0.00
4.91
0.21
0.26
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HYDROLOGY AND DETENTION CALCULATIONS
C
CROSS SECTION C-C
Cross Section for Irregular Channel
Project Description
Project File
fA2002 projects102-129\eng data\jamescou.fm2
Worksheet
SECTION C-C
Flow Element
Irregular Channel
Method
Manning's Formula
Solve For
Water Elevation
Section Data
Wtd. Mannings Coefficient
0.035
Channel Slope
0.010300 ftfft
Water Surface Elevation
5,021.96 ft
Discharge
133.00 efs
N
C
0
m
m
w
LM
Y.31 PM
O.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0
Station (ft)
FlowMaster v5.13
Haesfad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1685 Page 1 of 1
CROSS-SECTION C-C
Worksheet for Irregular Channel
Project Description
Project File
f:12002 projects\02-129\eng data\jamescou.fm2
Worksheet
SECTION C-C
Flow Element
Irregular Channel
Method
Manning's Formula
Solve For
Water Elevation
Input Data
Channel Slope
0.010300 ft/ft
Elevation range: 5,020.31 ft to 5,022.00 ft.
Station (ft)
Elevation (ft) Start Station End Station Roughness
0.00
5,022.00 0.00 95.00 0.035
51.00
5,021.00
60.00
5,020.31
64.00
5,021.42
95.00
5,022.00
Discharge
133.00 cfs
Results
Wtd. Mannings Coefficient
0.035
Water Surface Elevation
5,021.96
ft
Flow Area
47.62
ft2
Wetted Perimeter
91.25
ft
Top Width
91.05
ft
Height
1.65
ft
Critical Depth
5,021.80
ft
Critical Slope
0.023153 ft/ft
Velocity
2.79
ft/s
Velocity Head
0.12
ft
Specific Energy
5,022.08
ft
Froude Number
0.68
Flow is subcritical.
LOB FlowMaster v5.13
3:18 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1
CROSS-SECTION B-B, JAMES COURT
Cross Section for Irregular Channel
Project Description
Project File fA2002 projects\02-129\eng data\jamescou.fm2
Worksheet CROSS-SECTION B-B
Flow Element Irregular Channel
Method Manning's Formula
Solve For Water Elevation
Section Data
Wtd. Mannings Coefficient
0.017
Channel Slope
0.017300 ft/ft
Water Surface Elevation
5,021.82 ft
Discharge
133.00 cfs
N
C
O
N
N
W
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0
Station (ft)
Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666
FlowMaster v5.13
Page 1 of 1
'
Project Description
SECTION B-B
Worksheet for Irregular Channel
'
Project File
f:\2002 projectsX02-129\eng data\jamescou.fm2
Worksheet
CROSS-SECTION B-B
'
Flow Element
Method
Irregular Channel
Manning's Formula
Solve For
Water Elevation
Input Data
Channel Slope
0.017300 ft/ft
'
Elevation range: 5,020.93 ft to 5,022.30 ft.
Station (ft)
Elevation (ft) Start Station End Station
0.00
5,021.90 0.00 54.00
'
16.50
5,021.82 54.00 72.00
16.50
5,021.40
18.50
5,021.44
35.00
5,021.41
'
51.50
5,021.10
53.50
5,020.93
53.50
5,021.43
'
54.00
5,021.43
55.00
5,021.86
72.00
5,022.30
Discharge
133.00 cfs
'
Results
Wtd. Mannings Coefficient
0.017
Water Surface Elevation
5,021.82
ft
'
Flow Area
18.62
ftz
Wetted Perimeter
39.42
ft
Top Width
38.41
ft
'
Height
0.89
ft
Critical Depth
5,022.07
ft
Critical Slope
0.006910
ft/ft
'
Velocity
7.14
fus
Velocity Head
0.79
ft
Specific Energy
5,022.61
ft
Froude Number
1.81
'
Flow is supercritical.
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k34 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06706 (203) 755-1666
Roughness
0.016
0.035
FlowMaster v5.13
Page 1 of 1
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CROSS-SECTION A -A, JAMES COURT
Cross Section for Irregular Channel
Project Description
Project File M2002 projectsX02-129\eng data\jamescou.fm2
Worksheet CSU Housing / James Court
Flow Element Irregular Channel
Method Manning's Formula
Solve For Water Elevation
Section Data
Wtd. Mannings Coefficient
0.017
Channel Slope
0.014200 ft/ft
Water Surface Elevation
5,022.52 ft
Discharge
133.00 cfs
W
0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0
Station (ft)
Notes:
CROSS-SECTION A -A, JAMES COURT
L403 FlowMaster v5.13
3:12 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06IM (203) 755-1666 Page 1 of 1
Worksheet
Worksheet for Irregular Channel
Project Description
'
Project File
c:lhaestad\fmwlproject1.fm2
Worksheet
CSU Housing / James Court
Flow Element
Irregular Channel
'
Method
Manning's Formula
Solve For
Water Elevation
' Input Data
Channel Slope
0.014200 ft/ft
' Elevation range: 5,021.52 ft to 5,023.00 ft.
Station (ft)
Elevation (ft)
Start Station
0.00
5,023.00
0.00
' 15.55
5,022.37
15.55
16.05
5,022.37
53.55
16.05
5,021.87
' 18.05
5,022.04
34.55
5,022.10
51.05
5,021.69
53.05
5,021.52
'
53.05
5,022.02
53.55
5,022.02
54.00
5,022.42
'
71.25
5,023.00
Discharge
133.00 cfs
' Results
Wtd. Mannings Coefficient 0.017
'
Water Surface Elevation 5,022.52
ft
Flow Area
21.63
fF
Wetted Perimeter
46.36
ft
Top Width
45.18
ft
Height
1.00
ft
Critical Depth
5,022.71
ft
Critical Slope
0.006907 ft/ft
Velocity
6.15
ft/s
Velocity Head
0.59
ft
' Specific Energy
5,023.11
ft
Froude Number
1.57
Flow is supercritical.
End Station
15.55
53.55
71.25
Roughness
0.035
0.016
0.035
' tr03 FlowMaster v5.13
t44 PM Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 (203) 755-1666 Page 1 of 1
No Text
No Text
No Text
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Offsite flows as projected by Ayres Associates
(Refer to existing conditions exhibit, figure 2.2)
Peak Runoff
2 YEAR
10 YEAR
100 YEAR
Element
(cfs)
(cfs)
(cfs)
240
0.6
20.3
85.8
91
11.2
36.6
133.4
277
4.2
34.8
128.8
Element 277 also has detention volume:
' 2-yr. 0.31 acre-ft
10-yr. 0.42 acre-ft
100-yr. 0.75 acre-ft
fl
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OFF -SITE RUNOFF
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APPENDIX
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III. SUMMARY
This drainage plan has provided for both on and off -site drainage with a storm sewer system and
detention area. Discharge from this site will not adversely affect the surrounding and/or downstream
properties in the given design storms. Due to releases being restricted to the 2-year historic storm,
drainage conditions for downstream areas will actually improve from existing conditions during larger
storm events. It should be recognized that storms of greater magnitude than studied could cause flooding
and greater storm water quantities.
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III. SUMMARY
0
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3. Off -site Flows
' Ayres Associates are currently finishing a master drainage plan for the CSU Campus. According their
calculations, water spills from Larimer County Canal No. 2, located west of the campus, in even a 2-year
storm. The water from the ditch then travels east and splits at Shields Street, some flowing north and
some crossing Shields and continuing east. The flow crossing Shields Street enters James Court and
receives some additional drainage from adjacent properties. At the end of James Court, the drainage
flows into a poorly maintained drainage swale behind the Campus Gardens Apartments before entering
the Project site. During a 100-year storm, approximately 133.4 cfs enters the Project site from this
drainage swale. Calculations show that the 133 cfs in James Court stays within the limits of the curb and
gutter, but the existing swale at the end of James Court is drastically undersized and probably causes
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flooding of the adjacent buildings during a significant storm event.
C. Hydraulic Design
1. Detention Pond Design
As previously mentioned, the detention volumes of the ponds are sized to detain the storm runoff from the
100-year developed storm and release at a net rate equal to the 2-year historic runoff for the entire basin.
An orifice plate will be installed on each outlet pipe to ensure that the release amount is not exceeded
when the ponds are full. A spillway for each pond will be designed to carry flows in excess of the 100-
year storm after the ponds are full.
Off -site runoff will be routed through detention pond C and spilled to a channel on the south side of the
proposed building, where it will discharge into the area directly to the east of the site. A wall will be built
to deflect the water coming from James Court into the detention pond. The length and height of this wall
were determined by calculating the extent of inundation of the street.
5
' II. HYDROLOGY AND HYDRAULIC DESIGN
A. Introduction
Storm drainage conditions for the 2-year, 10-year and 100-year flows were analyzed for both on -site and
off -site flows. Both the historic and proposed development situations were investigated as part of this
1 analysis. Drainage facilities were designed to carry these flows as outlined in the City of Fort Collins
Storm Drainage Design Criteria. The drainage design for the developed conditions was based on the type
of development as indicated by the construction drawings.
' The rational method, which is commonly used in Colorado, was used to size the storm sewer system and
' detention pond. The rational method is recommended by the City of Fort Collins for sites less than 5
acres. Detention facilities were sized to adequately detain the storm runoff from the 100-year developed
storm event and release at a rate equal to the 2-year historic runoff. Historic condition runoff estimates are
obtained by modeling the existing watershed conditions.
B. Hydrology
1. Historic Conditions
' The proposed building site is currently a landscaped park. The proposed parking lot area is currently
vacant/agricultural ground. The historic drainage pattern sheet flows from west to east. A low area in the
center of the property acts as a very wide channel which directs all flows to the east into the Horticulture
area on campus.
2. Developed Conditions
The drainage exhibit (enclosed with this report) illustrates the proposed drainage scheme. The general
drainage pattern channels the flow via sheet flow or storm sewer to one of three detention ponds.
' Drainage in the detention ponds is released at a controlled rate into a City storm sewer located on the
south side of Pitkin Street. This storm sewer eventually outfalls into Spring Creek, located south of the
CSU Campus.
Basin A is located on the northeast side of the site and drains into detention pond A. In this basin, flow is
' generated from the building roof and the courtyard area on the east side of the building.
' Basin B is comprised of the access drive and the west side of the building. The flows from this basin
drain into detention pond B.
Basin C is comprised of the parking lot, southwest of the proposed building. This largely impervious area
drains into detention pond C.
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II. HYDROLOGY AND
HYDRAULIC DESIGN
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I. INTRODUCTION
The proposed CSU Student Housing, located within the City of Fort Collins, Colorado, consists of
approximately 5 acres. The site is currently used for agricultural purposes.
The CSU Student Housing site comprises part of the western half of Section 14, Range 69 West,
ex
Township 7 North, =k County, Colorado. More specifically, CSU Student Housing is bordered
to the North by Pitkin Street and to the South by the Lake West Apartments.
' The purpose of this report is to provide a description of the existing drainage conditions and to predict the
effect of development on future drainage. Based on this information, a plan was developed to handle the
drainage concerns. This plan is presented by the construction plans prepared for the Project.
A. Scope of Work
The areas of emphasis, included as part of this investigation, are:
1. A hydrologic analysis.
' 2. Analysis of detention.
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TABLE OF CONTENTS
I. INTRODUCTION..........................................................................................................................3
A. Scope of Work...........................................................................................................................
3
IL HYDROLOGY AND HYDRAULIC DESIGN
...........................................................................4
A. Introduction...............................................................................................................................
4
'
B. Hydrology..................................................................................................................................4
1. Historic Conditions.............................................................................................................
4
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2. Developed Conditions.........................................................................................................4
3. Off -site Flows.....................................................................................................................
5
C. Hydraulic Design.......................................................................................................................
5
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1. Detention Pond Design.......................................................................................................
5
III. SUMMARY....................................................................................................................................
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APPENDIX
Off -site Runoff
Hydrology and Detention Calculations
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Final Drainage Report
for
CSU Student Housing
City of Fort Collins, Colorado
February 6, 2003
Prepared for:
Colorado State University
Facilities Management
Fort Collins, CO 80523
By:
The Engineering Company
2310 East Prospect Road
Fort Collins, CO 80525
970-484-7477
Project No.: 02-129
I
FINAL DRAINAGE REPORT
FOR
CSU STUDENT HOUSING
CITY OF FORT COLLINS, COLORADO
FEBRUARY 2003