HomeMy WebLinkAboutDrainage Reports - 11/16/2005PROPERTY OF
FORT COLM-UTUXMS
Drainage Design Considerations
for
637 Cowan Street
Fort Collins, Colorado
November 5, 2003
CM41
CIVIL ENGINEERS
Final Approved Report
ff Gate o�
1 435 WEST 29TH STREET
LOVELAND, CO 80538
(970) 461 -2661
FAx (970) 461 -2665
www.dmwcivilengineers.com
Drainage Design Considerations
for
637 Cowan Street
Fort Collins, Colorado
November 5, 2003
Prepared for:
Barry Schram
PO Box 270887
Fort Collins, Colorado 80527
Prepared by:
19V I ?L MNG I N I &RS
1435 W. 291i Street
Loveland, Colorado 80538
Phone: (970)461-2661
Fax (970)461-2665
Project Number. 0301.00-COW
.1
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CIVIL ENGINEERS
November 5, 2003
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
1 Re: Drainage Design Considerations for
637 Cowan Street
Fort Collins, Colorado
' Dear Staff:
1435 WEST 29" STREET
LOVELAND, CO 6053E
(970) 461-2661
Fax (970) 461-2555
WWW.DMWCIVILENE3INEERS.COM
' DMW Civil Engineers is pleased to submit this drainage study for 637 Cowan Street for
your review. This report complies with technical criteria set forth in the City of Fort Collins'
Storm Drainage Design Criteria and Construction Standards manual and the Urban Storm
' Drainage Criteria Manual, Volume 3, by the Urban Drainage and Flood Control District.
We acknowledge that the City of Fort Collins' review of this study is only for general
conformance with submittal requirements, current design criteria and standard engineering
principles and practices.
If you should have any questions or comments as you review this report, please feel free
to contact me at your convenience.
Sincerely,
DMW CIVIL ENGINEERS
Jade P. Miller, P.E. (CO #33885)
Project Manager
I
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Drainage Design Considerations for
637 Cowan Street
TABLE OF CONTENTS
VICINITY MAP
Page No.
I INTRODUCTION
1.1 Objective.................................................1
1.2 Project History and Previous Studies ............................
1
1.3 Mapping and Surveying ......................................
1
II SITE LOCATION AND DESCRIPTION
2.1 Site Location..............................................1
2.2 Site Description ............................................
1
III HISTORIC CONDITIONS
3.1 Historic Drainage Patterns ....................................
1
IV DEVELOPED CONDITIONS
4.1 Proposed Site Development ..................................
2
4.2 Developed Drainage Patterns .................................
2
4.3 Detention Pond ...........................................2
V DESIGN CRITERIA
5.1 Design References.........................................2
5.2 Hydrologic Criteria .... :..................................... 2
5.3 Hydraulic Criteria ........................................... 3
VI EROSION CONTROL
6.1 Erosion Control Plan and Criteria .............................. 3
VII WATER QUALITY
7.1 Porous Landscape Detention ................................. 3
VIII CONCLUSIONS
8.1 Compliance with Standards ................................... 4
REFERENCES..................................................4
Drainage Design Considerations for
' 637 Cowan Street
1
EXHIBITS
1 Exhibit 1 637 Cowan Street Drainage Plan
APPENDICES
' Appendix A:
Hydrology Calculations
Appendix B:
Hydraulic Calculations
Appendix C:
Erosion Control Calculations
Appendix D:
Water Quality Calculations
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Vicinity Map
637 Cowan Street - Fort Collins, Colorado
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Drainage Design Considerations
for
637 Cowan Street
Fort Collins, Colorado
' November 5, 2003
INTRODUCTION
1.1 Objective
This study documents the results of a comprehensive hydrologic and hydraulic
' analysis of developed conditions for the proposed 637 Cowan Street development.
The utility plans which accompany this report are entitled Final Construction Plans
for 637 Cowan Street prepared by DMW Civil Engineers, Inc.
1.2 Project History and Previous Studies
The proposed development is located at 637 Cowan Street. The site is within the
' Old Town drainage basin but not within any regulatory floodplains. The City has
no drainage study on file for this site.
1.3 Mapping and Surveying
Field survey information and topographic mapping with a contour interval of 1-foot
' was obtained by DMW Civil Engineersfrom Cornerstone Land Surveying, Berthoud,
Colorado. Additional topography outside of the project boundary was taken from
City of Fort Collins Aerial Topography with a two (2) foot contour interval.
' 11 SITE LOCATION AND DESCRIPTION
' 2.1 Site Location
The proposed development is located at 637 Cowan Street. The site is located in
the northeast quarter of Section 13, Township 7 North, Range 69 West of the 6th
' Principal Meridian in the Town of Fort Collins, Colorado and is described as Part
of Block 186, City of Fort Collins (See Vicinity Map).
' 2.2 Site Description
The proposed development site is approximately 0.25 acres. The site has an
existing single-family residence and detached garage.
III. HISTORIC CONDITIONS
' 3.1 Historic Drainage Patterns
Stormwater runoff from 637 Cowan Street drains overland generally from west to
' east at slopes ranging from 0.5% to 1 % toward the existing street. There is an
existing low point immediately east of the existing house which retains some
stormwater runoff.
Drainage Design Considerations DMW Civil Engineers, Inc.
' 637 Cowan Street
November 5, 2003
' IV. DEVELOPED CONDITIONS
4.1 Proposed Site Development
Development of 637 Cowan Street will consist of construction of a new 3-unit, multi-
family residence. The proposed site infrastructure includes onsite parking and
utility services.
4.2 Developed Drainage Patterns
The developed site has been divided into two (2) onsite drainage basins.
Stormwater runoff will be conveyed overland to an onsite water quality area and
' allowed to infiltrate into the ground. Overflow from the water quality pond will flow
into Cowan Street via a 2' metal sidewalk culvert. The peak 100-year developed
discharge from the site will remain virtually unchanged from that which is outlined
in the Old Town Masterplan.
Runoff from Basin 1 (0.29 acres) drains overland to a water quality pond located
' just east of the existing building. Flows in excess of the water quality capture
volume flow into Cowan Street. The peak 2 and 100-year flows from Basin 1 are
0.2 and 1.1 cfs respectively.
' Runoff from Basin 2 (0.08 acres) flows along the gutter of Cowan Street and
combines with runoff from Basin 1. The peak 2 and 100-year flows for both basins
' are 0.4 and 1.4 cfs respectively.
' 4.3 Detention
Onsite water quantity detention has not been provided for 637 Cowan Street. With
an imperviousness value of 0.58, the site is only slightly less pervious that the 0.50
' used in the Old Town Masterplan. The difference in runoff coefficients results in an
increase of runoff from the site of 0.1 and 0.4 cfs for the peak 2 and 100-year flows
respectively. Calculations are provided in Appendix B to illustrate the impact of
' additional flows. Due to site constraints, location and relatively small impact to the
overall basin, a variance is being requested for a waiver of the onsite water quantity
detention requirement.
' V. DESIGN CRITERIA
5.1 Design References
' Drainage design criteria specified in the City of Fort Collins Storm Drainage Design
Criteria and Construction Standards manual and the Urban Storm Drainage Criteria
Manual, Volume 3 by the Urban Drainage and Flood Control District have been
' referenced in the preparation of this study.
5.2 Hydrologic Criteria
The rational method has been used to estimate peak stormwater runoff from the
project site. An initial 2-year and major 100-year design storms have been used to
' evaluate the proposed drainage system. Calculations made as part of this
Page 2
Drainage Design Considerations DMW Civil Engineers, Inc.
' 637 Cowan Street
November 5, 2003
investigation, along with other supporting material, are contained in Appendix A.
Rainfall intensity data for the rational method has been taken from rainfall intensity
' data tables contained in the City of Fort Collins Storm Drainage Design Criteria and
Construction Standards manual (see Figure 3-1 a). Composite runoff coefficients
Were generated using Table 3-3 and 3-4 of the City of Fort Collins Storm Drainage
' Design Criteria and Construction Standards manual.
5.3 (Hydraulic Criteria
' The computer program °Flowmaster° has been used to analyze the capacity of
proposed pipes and chases for the site.
EROSION CONTROL
6.1 Erosion Control Plan and Criteria
The erosion control plan presented here is intended to control rainfall erosion. The
Erosion Control Reference Manual for Construction Sites (ECRM), City of Fort
Collins, has been referenced for this erosion control plan.
' The proposed rainfall erosion control plan during construction will consist of
temporary structural erosion control measures. Temporary sediment control
' consisting of silt fencing will surround areas of the proposed construction. In
addition to silt fence, Pond 1 will be utilized as a sediment basin for additional
' sediment control. See the Grading and Erosion Control Plan for locations of
proposed erosion control measures.
' VII. WATER QUALITY
7.1 Porous Landscape Detention
' The City of Fort Collins requests that 40 hour extended detention basins be used
for water quality. Because of physical restraints of this site, this BMP was not
practical. Constructability was also a factor when evaluating the 40 hour extended
' detention basin. Because of the low flows routed through this pond, orifice sizing
and trash rack construction would have been difficult. It was for these reasons that
a porous landscape detention basin is proposed for water quality.
The porous landscape detention consists of a low lying vegetated area underlain
by a sand bed. This BMP allows water quality containment volume below the invert
' of the pond outlet. Accumulated runoff ponds in the vegetated zone and gradually
infiltrates into the underlying sand bed and subgrade. A total water quality
containment volume of 176 cubic feet is provided for the developed site.
Page 3
Drainage Design Considerations DMW Civil Engineers, Inc.
t 637 Cowan Street
November 5, 2003
' Vlll. CONCLUSIONS
8.1 Compliance with Standards
All drainage analyses have been performed according to the City of Fort Collins'
' Storm Drainage Design Criteria and Construction Standards manual and the Urban
Storm Drainage Criteria Manual, Volume 3, by the Urban Drainage and Flood
Control District.
1
1
Page 4
1
Drainage Design Considerations
637 Cowan Street
November 5, 2003
REFERENCES
DMW Civil Engineers, Inc.
' 1) Storm Drainage Design Criteria and Construction Standards, City of Fort
Collins, Colorado, May, 1997, revised 1999
' 2) Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control
District, Wright McLaughlin Engineers, Denver, Colorado, June, 2001.
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PROPOSED WATER 1
POROUS CONTROL POND'
POROUS LANDSCAPE
DETENTION W/SUBDRPNWOC
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LEGEND:
ST--
DISTNG STORM SEWER
O--ST
E%ISTNG STORM SEWER WRN INLET
PROPOSED STORM SEWER OR CULVERT
PROPOSED STORM SEWER OR CULVERT WITH INLET
5030 —
"STING CONTOUR
i 20 — PROPOSED CONTOUR
LAURELSTREET — — — — PROJECT BOUNDARY
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DESIGN DRAINAGE BASIN BOUNDARY
40 0 40 80 120 Feet V BASIN LABEL
5.0
AREA IN ACRES
( IN FEET ) Qi DESIGN POINT
1 inch = 40 ft.
PROPOSED RIPRAP OUTLET PROTECTION
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Appendix A
11
Table 3-3
RATIONn MTHOD RIMVF COEFFICIENTS !OR CMMSIM ANALTSIS
'
Character of Surface Runoff Coefficient
Streets. Parking Lots,. Drives'
'
Asphalt....................
0.95
0.95
Concrete..
Gravel ...................................
0.50
'
Roofs ..........................................
0.95
Lawns, Sandy Soil:
Flat
0.20
'
Averagege 2to 2 79,.
0.15
0.20
Steep >7%.. '................................
'
Lawns, Heavy Soil: ...................
Flat <2l..
0.20
Average 2 to 7%.. ........
0.25
Steep>71.....................................
0.35
' Table 3-4
AA?20N71L MffiTHOD FREQUENC! ADJUS70M FACTORS
' Storm Retarn Period Frequency Factor
(o+are) G
2 to 10 1.00
' 11 to 25 1.10
26 to 50 1.20
51 to 100 1.25
' Note: The product of C times Cr shall not exceed 1.00
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City of Fort Collins
Rainfall Intensity -Duration -Frequency Table
for using the Rational Method
(5 minutes - 30 minutes)
Figure 3-1a
Duration
{minutes)
2-year
Intensity
;fir
10-year
Intensity
inlhr
100-year
Intensity
in/hr
5.00
2.85
4.07
9.95
6.00
2.67
4.56
9.31
7.00
2.52
4.31
8.80
8.00
2.40
4.10
8.38
9.00
2.30
3.93
8.03
10.00
2.21
3.78
7.72
11.00
2.13
3.63
7.42
12.00
2.05
3.50
7.16
13.00
1.98
3.39
6.92
14.00
1.92
3.29
6.71
15.00
1.87
3.19
6.52
16.00
1.81
3.08
6.30
17.00
1.75
2.99
6.10
18.00
1.70
2.90
5.92
19.00
1.65
2.82
5.75
20.00
1.61
2.74
5.60
21.00
1.56
2:67
5.46
22.00
1.53
2.61
5.32
23.00
1.49
2.55
5.20
24.00
1.46
2.49
5.09
25.00
1.43
2.44
4.98
26.00
1.40
2.39
4.87
27:00
1.37
2-34
4.78
28.00
1.34
2.29
4.69
29.00
1.32
2.25
4.60
30.00
1.30
2.21
4.52
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02
_01
2 4 6 10 20
Average velocity (ft/see)
00-4-TR-GF. Sm-ond F(I.Anne 1996)
EQUATION FOR FIGURE 3-1:
PAVED: V=20.3282(s)"
UNPAVED: V=16.1345(sr,5
s= slope in ft/ft
FIGURE 3-1 a 1
AVERAGE VELOCITIES
k� FOR SHALLOW CIVIL ENDINEERB
NA
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Character of Surface
Runoff
Project 637 Cowan Street
Coef dent
Calculations By. J. Miller
Streets B Parking Lots:
Date. September 24, 2003
Paved ...........................
0.95
Gravel ...........................
0.50
Ddves & Walks .............
0.95
Roofs ...........................
0.95
Lawns, Sandy Soil.
0.10
Lawns, Heavy Sal:
0.20
Runoff Coefficients taken from Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 33
Basin
Basin
Area of
Area of
Area of Dries
Area of floors
Area of t.aam and
Weighted
ID
Area
Paved
Gr"
and Walks
t andsc O
Runoff
coeff tent
(Aaes)
Sheets
(ems)
Sheets
(As)
(Ms)
(Acres)
(ass)
1
0.29
0.00
0.00
0.07
0.08
0.16
0.48
2
0.08
0.06
0.00
0.02
0.00
0.00
0.95
1-2
0.37
0.06
0.00
0.09
0.08
0.16
0.58
Page 1 of 2
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Character of Surface
Runoff
Project: 637 Cowan
Coetfittient
Calculations By: J. Miller
Streets 6 Parking Lots:
Date: September 24, 2003
Paved
Gravel ...........................
0.50
Dives & walks .............
0.95
Roofs ...........................
0.95
Lewes, Sandy Soil:
0.10
Lawns, Heavy Sort:
0.20
Runoff Coefficients taken from Fort Collins Storm Drainage Design Criteria and Construction Standards, Table 3-3
Basin
Basin
Area of
Area of
Area of Dries
Area of Roofs
Area of Lawn and
Weighted
ID
Area
Paved
Gravel
and Walks
landscape
Runoff
(Acres)
Sheets
(Acres)
Streets
(Acres)
(Acres)
(Acres)
(Acres)
Coefficlaht
x 1.25
1
0.29
0.00
0.00
0.07
0.06
0.16
0.60
2
0.06
0.06
0.00
0.02
0.00
0.00
1.00
1-2
0.37
0.06
0.00
0.09
0.06
0.16
0.73
Page 2 of 2
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Appendix B
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11
1
Drainage Design Considerations
for
637 Cowan Street
Fort Collins, Colorado
November 5, 2003
I. INTRODUCTION
1.1 Objective
This study documents the results of a comprehensive hydrologic and hydraulic
analysis of developed conditions for the proposed 637 Cowan Street development.
The utility plans which accompany this report are entitled Final Construction Plans
for 637 Cowan Street prepared by DMW Civil Engineers, Inc.
1.2 Project History and Previous Studies
The proposed development is located at 637 Cowan Street. The site is within the
Old Town drainage basin but not within any regulatory floodplains. The City has
no drainage study on file for this site.
1.3 Mapping and Surveying
Field survey information and topographic mapping with a contour interval of 1-foot
was obtained by DMW Civil Engineers from Cornerstone Land Surveying, Berthoud,
Colorado. Additional topography outside of the project boundary was taken from
City of Fort Collins Aerial Topography with a two (2) foot contour interval.
II SITE LOCATION AND DESCRIPTION
2.1 Site Location
The proposed development is located at 637 Cowan Street. The site is located in
the northeast quarter of Section 13, Township 7 North, Range 69 West of the 6th
Principal Meridian in the Town of Fort Collins, Colorado and is described as Part
of Block 186, City of Fort Collins (See Vicinity Map).
2.2 Site Description
The proposed development site is approximately 0.25 acres. The site has an
existing single-family residence and detached garage. .
HISTORIC CONDITIONS
3,1 Historic Drainage Patterns
Stormwater runoff from 637 Cowan Street drains overland generally from west to
east at slopes ranging from 0.5% to 1% toward the existing street. There is an
existing low point immediately east of the existing house which retains some
stormwater runoff.
' Drainage Design Considerations
637 Cowan Street
November 5, 2003
DMW Civil Engineers, Inc.
' IV. DEVELOPED CONDITIONS
4.1 Proposed Site Development
Development of 637 Cowan Streetwill consist of construction of a new3-unit, multi-
family residence. The proposed site infrastructure includes onsite parking and
utility services.
' 4.2 Developed Drainage Patterns
The developed site has been divided into two (2) onsite drainage basins.
' Stormwater runoff will be conveyed overland to an onsite water quality area and
allowed to infiltrate into the ground. Overflow from the water quality pond will flow
into Cowan Street via a 2' metal sidewalk culvert. The peak 100-year developed
' discharge from the site will remain virtually unchanged from that which is outlined
in the Old Town Masterplan.
Runoff from Basin 1 (0.29 acres) drains overland to a water quality pond located
just east of the existing building. Flows in excess of the water quality capture
volume flow into Cowan Street. The peak 2 and 100-year flows from Basin 1 are
' 0.2 and 1.1 cfs respectively.
Runoff from Basin 2 (0.08 acres) flows along the gutter of Cowan Street and
t combines with runoff from Basin 1. The peak 2 and 100-year flows for both basins
are 0.4 and 1.4 cfs respectively.
' 4.3 Detention
Onsite water quantity detention has not been provided for 637 Cowan Street. With
' an imperviousness value of 0.58, the site is only slightly less pervious that the 0.50
used in the Old Town Masterplan. The difference in runoff coefficients results in an
increase of runoff from the site of 0.1 and 0.4 cfs for the peak 2 and 100-year flows
' respectively. Calculations are provided in Appendix 8 to illustrate the impact of
additional flows. Due to site constraints, location and relatively small impact to the
overall basin, a variance is being requested for a waiver of the onsite water quantity
' detention requirement.
V. DESIGN CRITERIA
' 5.1 Design References
Drainage design criteria specified in the City of Fort Collins Storm Drainage Design
Criteria and Construction Standards manual and the Urban Storm Drainage Criteria
' Manual, Volume 3 by the Urban Drainage and Flood Control District have been
referenced in the preparation of this study.
5.2 Hydrologic Criteria
The rational method has been used to estimate peak stormwater runoff from the
' project site. An initial 2-year and major 100-year design storms have been used to
evaluate the proposed drainage system. Calculations made as part of this
' Drainage Design Considerations
637 Cowan Street
November 5, 2003
DMW Civil Engineers, Inc.
' investigation, along with other supporting material, are contained in Appendix A.
Rainfall intensity data for the rational method has been taken from rainfall intensity
' data tables contained in the City of Fort Collins Storm Drainage Design Criteria and
Construction Standards manual (see Figure 3-1a). Composite runoff coefficients
' were generated using Table 3-3 and 3-4 of the City of Fort Collins Storm Drainage
Design Criteria and Construction Standards manual.
5.3 Hydraulic Criteria
The computer program "Flowmaster" has been used to analyze the capacity of
proposed pipes and chases for the site.
VI. EROSION CONTROL
' 6.1 Erosion Control Plan and Criteria
The erosion control plan presented here is intended to control rainfall erosion. The
Erosion Control Reference Manual for Construction Sites (ECRM), City of Fort
' Collins, has been referenced for this erosion control plan.
The proposed rainfall erosion control plan during construction will consist of
' temporary structural erosion control measures. Temporary sediment control
consisting of silt fencing will surround areas of the proposed construction. In
addition to silt fence, Pond 1 will be utilized as a sediment basin for additional
sediment control. See the Grading and Erosion Control Plan for locations of
proposed erosion control measures.
' VII. WATER QUALITY
' 7.1 Porous Landscape Detention
The City of Fort Collins requests that 40 hour extended detention basins be used
for water quality. Because of physical restraints of this site, this BMP was not
' practical. Constructability was also a factor when evaluating the 40 hour extended
detention basin. Because of the low flows routed through this pond, orifice sizing
and trash rack construction would have been difficult. It was for these reasons that
' a porous landscape detention basin is proposed for water quality.
The porous landscape detention consists of a low lying vegetated area underlain
by a sand bed. This BMP allows water quality containment volume below the invert
of the pond outlet. Accumulated runoff ponds in the vegetated zone and gradually
' infiltrates into the underlying sand bed and subgrade. A total water quality
containment volume of 176 cubic feet is provided for the developed site.
11
Drainage Design Considerations DMW Civil Engineers, Inc.
637 Cowan Street
November 5, 2003
Vill. CONCLUSIONS
8.1 Compliance with Standards
All drainage analyses have been performed according to the City of Fort Collins'
Storm Drainage Design Criteria and Construction Standards manual and the Urban
Storm Drainage Criteria Manual, Volume 3, by the Urban Drainage and Flood
Control District.
Drainage Design Considerations DRAW Civil Engineers, Inc.
' 637 Cowan Street
November 5, 2003
' REFERENCES
1) Storm Drainage Design Criteria and Construction Standards, City of Fort
Collins, Colorado, May, 1997, revised 1999
' 2) Urban Storm Drainage Criteria Manual, Urban Drainage and Flood Control
District, Wright McLaughlin Engineers, Denver, Colorado, June, 2001.
[1
1
n
' 22 Metal Sidewalk Culvert
Worksheet for Rectangular Channel
Project Description
'
Workaheet
Flow Element
Z Metal Sidewalk Culvert
Rectangular Channel
Method
Manning's Formula
Solve For
Discharge
Input Data
Mannmgs Coefflcienl 0.013
'
Slope
0.010000 ft/ft
Depth
0.50 ft
Bottom Width
2.00 ft
'
Results
Discharge
550 cfs
Flow Area
1.0 W
Wetted Perimeter
3.00 ft
Top Width
2.00 ft
Critical Depth
0.62 ft
t
Critical slope
0.005490 ftM
Velocity
5.50 Ills
Velocity Head
0.47 ft
Specific Energy
0.97 ft
Fmude Number
1.37
Flow Type
Supercrdfcal
11
1
fAdraaings%CwN kcaw.fm2 Davis, Miller A Wohnrads Civil Engineers, Ina
' 05/09M 10:06:00 AM 0 liaesfad Melhads, Inc. 37 Broakside Road Waterbury, CT 06708 USA (203) 755-1666
Project Engineer. OMW
FW"Aastar %Z.1 [614kl
Page 1 or 1
100-Year Historic Site Gutter Flow
Worksheet for Gutter Section
Pra]ed
WoAtsheet Hollywood curb
Type Gutter Section
Solve For Spread
Input Data
slope
0.005400 f fft
Discharge
2.20 cts
Gutter Width
2.00 ft
Gutter Cross Slope
0.083000 fVR
Road Cross Slope
0.020000 Nit
Mannings Coefficient 0.013
Results
Spread
8.91 ft
Flow Area
0.9 ftz
Depth
0.30 ft
Gutter Depression
1.5 in
Velocity
2.39 fLis
Mtkr 637 Cowan Street Project Engineer: DMW
f.WrwA VsNomMecslcow.Hn2 DOVia. Millar A Wbhnrada CIVIL Ee91e410M. Ino. FIOWMaster %6.1 (614k]
OGM&M 09:05:0e AM 011matad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA (2W) 755-10M Pepe 1 of 1
100-Year Developed Site Gutter Flow
Worksheet for Gutter Section
[J
Project Dntsa"on
Worksheet Holywood curb
Type Gutter Section
Solwe For Spread
Input Data
Slope
0.005400 fl!R
Discharge
2.60 cis
Gutter Width
2.00 It
Gutter Cross Slope
0.083000 It/R
Road Cross Slope
0.020000 tuft
Mannings Coefficient
0.013
Results
Spread
9.64 ft
Flow Area
1.1 fe
Depth
0.32 It
Gutter Depression
1.5 In
Velocity
2.46 ft/s
Titter 637 Cowan Street Project Engineer: DMW
mcirawingalcowtdowom.fm2 Davis, Miller & Wohnrede Civil Engineers, ma. FlowMasfer va.t (614k)
I
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1
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1
Rainfall Performance Standard Evaluation
Project.
637 Cowan Street
STANDARD FORMA
Calculations By: J. Miller
Project No.:
0301.00-COW
Client:
Barry Schram
Date: 5/12/03
DEVELOPED
ERODIBILITY
As°
L.gb
A b X L6b
SSE
Alb X S,b
LE
Sb
PS
SUBBASIN
ZONE
(ac)
(ft)
(%)
(ft)
1-2
MODERATE
0.37
145.0
53.7
1.00
0.4
- yyh�>
a.D•i�C* -s
-
:e7"
..yz' T+
+s �'..'
Y
Fi `°'
a._
EXAMPLE CALCULATIONS
Lb = SUM(Asb*Lsb)/A
Sb = SUM(Asb*Ssb)/A
PS (during constriction) = 75.4 (From Table 8-A)
PS (after construction) = 75.4/0.85 = 88.7
1
1
F:XDrawings1 VAMCSICOW-ECForrMwpd
DMW Civil Engineers
F
1
1
11
1
Effectiveness Calculations
Project: 637 Cowan Street STANDARD FORM B
Calculations By., J_ Miller
Project No.: 0301.00-COW
Client: Barry Schram Date: 5/12/03
EROSION CONTROL METHOD
C-
P-Factor
Comment
Factor
Value
Value
Roads ! Walks
0.01
1.00
Existing and proposed pavement
Hay or Straw Mulch
0.06
1.00
Apply after planting grass seed
Sediment Basin
1.00
0.50
Water quality pond
Sift Fence
1.00
0.50
Along south & north of project
MAJOR
PS
SUB-
AREA
CALCULATIONS
BASIN
N
BASIN
(AC)
1-2
75.4
0.37
DURING CONSTRUCTION:
Plan intent: Seed and Mulch disturbed areas
Impervious area = 0.22 acres
Impervious:
Grass seed and mulch = 0.15 acres
Pervious:
Weighted C Factor=
((0.01 x 0.22)+(0.06 x 0.15)10.37 = 0.030
Weighted P Facto—0.50 = 0.60
EFF = [1-(C x P)]100=(1-(0.030 x 0.50) x 100 =
98.5 > 75.4
' F:1Drm&gslCOVICMSICOW-ECFwnB.wpd DN{W Civil Engineers
I
Engineer's Estimate of Probable Cost
' for Erosion Control Escrow Security
1
Project:
637 Cowan Street
Icalculations
I
By: JJ.
Miller
Pro ect No:
0301.00-COW
Date:
05/12/03
Itemized Costs:
Item
WnV
Quanfity-n
os
Total
-Siltence
Mulching
AG—
----D-T5
$,
subtotal
Multiplier
Total
Formula Based:
UnW
Quantityro
os
o a
Revegetaboff <5 Ac.
u t ier
oa
Escrow Security (greater of two estimates above, $1000 min.:
51,000.00
t-Unit Cost based upon RSMeans Sde Work and Landscape Cast Data, 2003 Edition, adjusted for City of Fart Cdhns.
1
r
1
I
1
1
u
I
Appendix D
I
Design Procedure Form: Porous Landscape Detention (PLD)
Designer:
J. Miller
Company.
DUN Civil Engineers
Date:
May 12, 2003
Project:
637 COWAN STREET 0301.00 • COW
Location:
Fort Collins, CO
1. Basin Storage Volume
( I, =100% if all paved and roofed areas uts of PLD)
I, =
60.00 %
A) Tributary Area's Imperviousness Ratio (i = b/ 100)
i =
0.60 =
B) Contributing Watershed Area Including the PLD (Area)
Area =
10,990 square feet
C) Water Quality Capture Volume (WQCV)
WQCV =
0.10 : watershed inches
(WQCV =0.8'(0.91'I'-1.19.12+0.78"1))
0) Design Volume: Vol„m = (WQCV 112)' Area
Vol =
173:0. . ; cubic feet
2. PLD Surface Area (ApLD) and Average Depth (ds,)
Ap,o =
176 square feet
(d,,,: = (Vol / Apw), Mira=05, Max=10)
dw =
Eva.0 feet
3. Base Course (See Figure PLD-1)
X
6" (Min.) Sandy Loam Turf Layer, Plus 18" (Min.)
Layer of 25% Peat and 75% Sand Min, Plus 9"
(Men.) Layer of ASSHTO #8 Coarse Aggregate
(CDOT Section 703 Specification).
Other:
5. Draining of porous pavement (Check a, or b, or c, answer d)
Infiltration to Subgrade with Permeable
Based on answers to 5a through 5d, check the appropriate method
Membrane: 5(c) checked and 5(d) = no
a) Check boot if subgrade is heavy or expansive clay
Underdrain with Impermeable
b) Check box if subgrade is silly or clayey sands X
�
Membrane. 5(a) checked or 5(d) = yes
c) Check box If subgrade is well -draining soils
X:
Underdrain with Permeable Membrane.
d) Does tributary catchment contain land uses that may have
5(b) checked and 5(d) = no
petroleum products, greases, or other chemicals
present, such as gas station, yes no
Other:
hardware store, restaurant, etc.? X,
Notes:
i
2
0.08
ImmempWN R'IIjkMF—
%Q1
�II
mm
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