HomeMy WebLinkAboutCSU PHEMISTER TRAIL - SITE PLAN ADVISORY REVIEW - SPA230001 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTColorado State University
Phemister Trail
Colorado State University
Phemister Trail
Final Drainage Report
DRAFT
September 2023
Colorado State University
Phemister Trail
Contents
List of Tables and Figures..............................................................................................................................2
I. Engineer’s Certification ........................................................................................................................3
II. Background...........................................................................................................................................4
III. Site Location and Description...............................................................................................................4
IV. Existing Conditions ...............................................................................................................................5
V. Drainage Design Criteria.......................................................................................................................6
VI. Proposed Conditions ............................................................................................................................6
A. Hydrologic Method...........................................................................................................................7
B. Water Quality ...................................................................................................................................8
VII. Conclusions and Recommendations.....................................................................................................8
Appendix A: Sub Basin Delineation and Map .............................................................................................9
Appendix B: Existing Conditions Runoff Calculations ...............................................................................10
Appendix C: Proposed Conditions Runoff Calculations ............................................................................11
List of Tables and Figures
Figure 1. Vicinity Map...................................................................................................................................4
Table 1: Phemister Trail - Existing Conditions ..............................................................................................5
Table 2: Phemister Trail - Impervious Areas.................................................................................................6
Table 3: PhemisterTrail - Proposed Conditions ............................................................................................7
Colorado State University
Phemister Trail
I. Engineer’s Certification
“I hereby certify that this report and plan for the Final Drainage Design for the Phemister Trail
Project was prepared by me (or under my direct supervision) in accordance with provisions of
the City of Fort Collins Stormwater Design Standards for the Responsible Parties thereof.”
Keith Meyer, PE
Registered Professional Engineer
State of Colorado, No. 32976
Colorado State University
Phemister Trail
II. Background
Colorado State University (CSU) is seeking to design and construct a shared-use path from Bay
Drive and Centre Avenue to the Gardens on Spring Creek. This project has been made possible
through various funding sources, including the state’s Multimodal Transportation and Mitigation
Options Funds, with sponsorship from Larimer County, CSU’s Alternative Transportation Fee
Advisory Board, and a substantial gift from Bob and Ann Phemister. The various entities,
including the City of Fort Collins (City), Larimer County, and CSU have come together on this
project to provide a solution for those traveling on this corridor to access the CSU campus. This
trail will provide a direct route to Spring Creek Trail without the need to cross Centre Avenue.
Additionally, this path would serve as a detour route when the seasonal flooding of Spring Creek
occurs.
CSU has been coordinating with the City for a number of years to make this project possible. In
2014, CSU received initial approval through the City’s Site Plan Advisory Review (SPAR) process
as part of a detention/water quality pond project submittal. Recently, CSU has been coordinating
with the City on a second SPAR submittal involving the last section of this trail spanning City
owned property near Spring Creek.
III. Site Location and Description
The project is located directly south of CSU’s main campus along the West side of Centre Avenue
from Bay Drive to Spring Creek Trail. The project encompasses approximately 0.31 acres. See the
project location displayed in Figure 1, below.
Figure 1. Vicinity Map
Colorado State University
Phemister Trail
The Phemister Trail project constructs a new bike path connecting the CSU Main Campus spine
to Spring Creek via the Prospect Underpass. The existing sidewalk and curb and gutter will be
expanded near Bay Drive to accommodate the new bike path width. From this location south,
the concrete trail will replace an existing aggregate access road. Near Spring Creek, the trail will
be constructed through upland and wetland vegetation with a new bridge crossing Spring Creek.
Historic runoff patterns will be maintained throughout the project area.
IV. Existing Conditions
The Phemister Trail alignment consists of three primary drainage areas. At the north, concrete
sidewalk, curb and gutter with a parkway strip route runoff to Centre Avenue then south to Spring
Creek. At the center of the project the existing aggregate access road drains west into the
detention pond. At the south, existing ground drains south to Spring Creek.
The existing project area, in total, is approximately 14.9% impervious with surfaces including
concrete sidewalk, gravel access roads, and curb and gutter. The pervious portions of the project
area include landscaping at the north and central portions of the project and undeveloped upland
and wetland areas at the south portion of the project.
A total of 4 sub-basins have been identified and analyzed to understand the historic runoff
conditions. Appendix A can be referenced for the existing subbasin delineation. This appendix
shows the mapped area of each sub-basin. As shown in Appendix A the north end of the project
is labeled Sub-basin 1. Flows are routed onto Centre Ave where they flow south via curb and
gutter to an inlet and pipe configuration which then routes flows to Spring Creek. Sub-basin 2,
which makes up the majority of the project, routes flows into the detention/water quality pond
area directly west of the project site. Sub-basin 3 routes flows directly into Spring Creek, un-
detained. Sub-basin 4 routes flows from the Gardens at Spring Creek north to Spring Creek, also
un-detained.
Appendix B can be referenced for the hydraulic calculations showing existing conditions runoff.
Appendix B includes runoff coefficients, time of concentration, and rational method calculations.
Table 1, below summarizes the existing drainage conditions of the project area.
Table 1: Phemister Trail - Existing Conditions
Sub-Basin ID Size (sf)
Composite
Runoff
Coefficient
Q - 2 year
(cfs)
Q - 10 year
(cfs)
Q - 100 year
(cfs)
1 146,901 0.60 5.34 9.11 22.33
2 359,860 0.16 2.87 4.91 12.54
3 75,518 0.15 0.57 0.98 2.51
4 132,718 0.25 2.20 3.76 9.61
Colorado State University
Phemister Trail
Table 2 below summarizes the existing impervious areas of each sub-basin.
Table 2: Phemister Trail – Impervious Areas
Sub-Basin ID
Total Sub-
Basin Area
(sf)
Impervious
Area (sf)
% of Total Sub-
Basin Area
1 146,901 81,817 76.87%
2 359,860 7,448 7.00%
3 75,518 0 0.00%
4 132,718 17,166 16.13%
Totals 714,997 106,431 100.00%
From this data, the total impervious percentage of the entire project area is 14.9%
V. Drainage Design Criteria
The runoff and drainage calculations were developed in accordance with the Fort Collins
Stormwater Criteria Manual (Manual). The drainage design considers the existing conditions and
historical overland flow, 2-year, 10-year and 100-year storm events respectively, throughout the
project. The primary goal of the drainage design is to maintain historic drainage patterns
resulting in no impact to the historic drainage conditions.
VI. Proposed Conditions
The proposed conditions match the existing conditions and historic drainage patterns along the
Phemister trail alignment. All areas of the corridor experience a minor change in developed
conditions flow as a result of impervious/pervious area changes, and varying cross and
longitudinal slopes. Overall, the proposed impervious area has been calculated at 15.6%. The
change of impervious area from existing to proposed is 0.70% considering the addition of
Phemister Trail to the existing sub basins.
Appendix D can be referenced for the hydraulic calculations showing proposed condition runoff.
Appendix D includes runoff coefficients, time of concentration, and rational method calculations.
Table 3 below summarizes the proposed drainage conditions of the project area compared to the
existing conditions.
Colorado State University
Phemister Trail
Table 3: Phemister Trail – Proposed Conditions
Sub-
Basin
ID
Size (sf)
Composite
Runoff
Coefficient
Q - 2 year
(cfs)
Increase
(cfs)
Q - 10
year
(cfs)
Increase
(cfs)
Q - 100
year
(cfs)
Increase
(cfs)
1 146,901 0.60 5.40 0.06 9.22 0.11 22.59 0.26
2 359,860 0.17 3.10 0.23 5.30 0.39 13.52 0.98
3 75,518 0.16 0.62 0.05 1.06 0.07 2.70 0.19
4 132,718 0.25 2.24 0.04 3.83 0.07 9.78 0.17
A high-level summary of the proposed changes and how they affect various drainage patterns is
provided below.
•Sub Basin 1: Considering the northern segment of the Phemister Trail, the proposed
improvements entail minor adjustments to the existing curb and gutter, and extending
the sidewalk to integrate the new bike path. The design diligently preserves historical
flow patterns, directing runoff to the established inlet at Spring Creek via Center Ave. The
anticipated alteration in flows at this inlet is deemed negligible, necessitating no
supplementary infrastructure upgrades.
•Sub Basin 2: Within this stretch of the Phemister Trail, the concrete path is slated for
construction within existing landscaped and improved areas, replacing the aggregate base
course roadway. Flow patterns will mirror the existing conditions, guiding runoff off to
the detention/water quality pond area west of the site. The expected change in
developed condition flows from the trail improvement is negligible therefore warranting
no additional drainage improvements in this sub basin.
•Sub Basin 3: This section of the Phemister Trail maintains established overland flow
patterns with developed conditions runoff routed to Spring Creek un-detained. Runoff
will sheet flow across grassland and wetland areas to Spring Creek. The projected
increase in flow conditions of 0.19 cfs in the 100-year event is very minimal warranting
no further improvements.
•Sub Basin 4: The southern section of the Phemister Trail spans Spring Creek connecting
the north trail to the Gardens. This portion of the trail project also routes developed
condition flows directly to Spring Creek un-detained. Runoff will sheet flow across
grassland and wetland areas to Spring Creek. The projected increase in flow conditions
of 0.17 cfs in the 100-year event is very minimal warranting no further improvements.
A. Hydrologic Method
In order to perform developed condition hydraulic calculations, the study area for
Phemister Trail was delineated into drainage sub basins based on existing and
Colorado State University
Phemister Trail
proposed topography. There are a total of 4 sub basins identified along the project
(Appendix A). Each existing and proposed sub basin was analyzed to determine
impervious and pervious areas. Impervious surfaces were assumed to have a runoff
coefficient of either 0.95 for concrete/asphalt surfaces and 0.50 for gravel surfaces.
Pervious surfaces were assumed to have a runoff coefficient of 0.15, in compliance
with Section 3.0 of the Fort Collins Stormwater Criteria Manual. Developed condition
composite runoff calculations can be found in Appendix C.
B. Water Quality
The approach to maintaining water quality within the respective sub basins is to
simply match existing conditions utilizing existing water quality features. Sub basin 1
flows are routed to an inlet in Centre Ave. then to a subsurface pipe which drains to
Spring Creek. Here, flows are filtered through wetlands prior to the Spring Creek
receiving waters. In sub basin 2 all developed condition flows have been directed into
the existing detention/water quality pond. Flows are filtered through wetlands in this
pond prior to discharge to Spring Creek. Sub basins 3 and 4 will maintain overland
flow conditions directing developed condition flows through upland and wetland
areas prior to discharge to Spring Creek. Low impact development features are not
provided as part of this project design.
VII. Conclusions and Recommendations
In summary, the improvements associated with the Phemister Trail have minimal impact on the
existing drainage runoff and quality. The proposed impervious area is within 1.0% of the
existing conditions. This results in minor changes in stormwater runoff, warranting no
necessary alterations to the existing infrastructure or water quality features across the project
study area.
Colorado State University
Phemister Trail
Appendix A: Sub Basin Delineation and Map
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SCALE: 1" =60'
060'60' 120' 180'
(True scale for 22x34 sheet size)
Appendix A
132,713 sf
Sub Basin 1
Sub Basin 2
Sub Basin 3
Sub Basin 4
Colorado State University
Phemister Trail
Appendix B: Existing Conditions Runoff Calculations
Phemister Trail
Runoff Coefficient Calculation
Character of Surface Runoff
Coefficient C
Area
A (ft2)Ci*A
Asphalt/Concrete 0.95 81,817 77,726
Landscape or Pervious surface 0.15 65,084 9,763
146,901 87,489
0.60
Character of Surface Runoff
Coefficient C
Area
A (ft2)Ci*A
Asphalt/Concrete 0.95 - -
Gravel 0.50 7,448 3,724
Landscape or Pervious surface 0.15 352,412 52,862
TOTAL 359,860 56,586
0.16
Character of Surface Runoff
Coefficient C
Area
A (ft2)Ci*A
Asphalt/Concrete 0.95 - -
Landscape or Pervious surface 0.15 75,518 11,328
75,518 11,328
0.15
Character of Surface Runoff
Coefficient C
Area
A (ft2)Ci*A
Asphalt/Concrete 0.95 17,166 16,308
Landscape or Pervious surface 0.15 115,552 17,333
132,718 33,641
0.25
9/21/2023
TOTAL
Sub Basin 2 -
Streets, Parking Lots, Drives:
Lawns, Sandy Soil:
Sub Basin 1 -
Streets, Parking Lots, Drives:
Lawns, Sandy Soil:
Lawns, Sandy Soil:
TOTAL
Sub Basin 3 -
Streets, Parking Lots, Drives:
Lawns, Sandy Soil:
TOTAL
Sub Basin 4 -
Streets, Parking Lots, Drives:
Appendix B
Phemister Trail
Time of Concentration Project Location: Phemister Trail Calculated By: NDND
Date: 9/21/2023
Site Calculations:
Design Storm (yr): 2
Basin Data Final tc Remarks
Basin Sub-basin
Area
(Ac)Ci*A
Frequency
Adustment
Factor
C2Cf
Length
(ft)Start Elev. End Elev.
Slope
(%)
ti
(min)
Length
(ft)Start Elev. End Elev.
Slope
(%)
Roughness
Coefficient
Hydraulic
Radius
(ft)
Velocity
(ft/s)
tt
(min)
tc
(min)L tc
tc
(min)
Minimum
(min)
Sub Basin 1 1 3.372 0.60 1 0.60 0 5010 5010 0.00% 0.00 803 5010 5000.5 1.18% 0.013 0.074 2.20 6.09 6.09 803 14.46 6.09 5.0
Sub Basin 2 2 8.261 0.16 1 0.16 890 4999 4991 0.90% 54.50 0.00% 0.00 54.50 890 10.00 10.00 5.0
Sub Basin 3 3 1.734 0.15 1 0.15 123 4995.5 4991 3.66% 12.79 0.00% 0.00 12.79 123 10.00 10.00 5.0
Sub Basin 4 4 3.047 0.25 1 0.25 36 4999 4994.4 12.78% 4.06 0.00% 0.00 4.06 36 10.00 5.00 5.0
Design Storm (yr): 10
Basin Data Final tc Remarks
Basin Sub-basin
Area
(Ac)Ci*A
Frequency
Adustment
Factor
C2Cf
Length
(ft)Start Elev. End Elev.
Slope
(%)
ti
(min)
Length
(ft)Start Elev. End Elev.
Slope
(%)
Roughness
Coefficient
Hydraulic
Radius
(ft)
Velocity
(ft/s)
tt
(min)
tc
(min)L tc
tc
(min)
Minimum
(min)
Sub Basin 1 1 3.372 0.60 1 0.60 0 5010 5010 0.00% 0.00 803 5010 5000.5 1.18% 0.013 0.074 2.20 6.09 6.09 803 14.46 6.09 5.0
Sub Basin 2 2 8.261 0.16 1 0.16 890 4999 4991 0.90% 54.50 0.00 54.50 890 10.00 10.00 5.0
Sub Basin 3 3 1.734 0.15 1 0.15 123 4995.5 4991 3.66% 12.79 0.00 12.79 123 10.00 10.00 5.0
Sub Basin 4 4 3.047 0.25 1 0.25 36 4999 4994.4 12.78% 4.06 0.00 4.06 36 10.00 5.00 5.0
Design Storm (yr): 100
Basin Data Final tc Remarks
Basin Sub-basin
Area
(Ac)Ci*A
Frequency
Adustment
Factor
C2Cf
Length
(ft)Start Elev. End Elev.
Slope
(%)
ti
(min)
Length
(ft)Start Elev. End Elev.
Slope
(%)
Roughness
Coefficient
Hydraulic
Radius
(ft)
Velocity
(ft/s)
tt
(min)
tc
(min)L tc
tc
(min)
Minimum
(min)
Sub Basin 1 1 3.372 0.60 1.25 0.74 0 5010 5010 0.00% 0.00 803 5010 5000.5 1.18% 0.013 0.07 2.20 6.09 6.09 803 14.46 6.09 5.0
Sub Basin 2 2 8.261 0.16 1.25 0.20 890 4999 4991 0.90% 52.22 0.00 52.22 890 10.00 10.00 5.0
Sub Basin 3 3 1.734 0.15 1.25 0.19 123 4995.5 4991 3.66% 12.28 0.00 12.28 123 10.00 10.00 5.0
Sub Basin 4 4 3.047 0.25 1.25 0.32 36 4999 4994.4 12.78% 3.76 0.00 3.76 36 10.00 5.00 5.0
Initial/Overland Time (t i) Travel Time (tt)tc Alternative Method
Initial/Overland Time (t i) Travel Time (tt)tc Alternative Method
tc Alternative MethodInitial/Overland Time (t i) Travel Time (tt)
Appendix B
Phemister Trail Project Location: Phemister Trail
Storm Drainage Design Calculated By: ND
Date: 9/21/2023
Site Calculations:
Direct Runoff
Basin Storm Event Area
C2 Final tc C2*A I Q
Total
Volume
(Ac)(Ac)(in/hr)(cfs)(cf)
Sub Basin 1 2-Year 3.372
0.60
6.09 2.008 2.66 5.34 1,601
Sub Basin 2 2-Year 8.261 0.16 10.00 1.299 2.21 2.87 861
Sub Basin 3 2-Year 1.734 0.15 10.00 0.260 2.21 0.575 172
Sub Basin 4 2-Year 3.047 0.25 5.00 0.772 2.85 2.201 660
Basin Storm Event Area
C2 Final tc C2*A I Q
Total
Volume
(Ac) (Ac) (in/hr) (cfs) (cf)
Sub Basin 1 10-Year 3.372 0.60 6.09 2.008 4.54 9.11 2,734
Sub Basin 2 10-Year 8.261 0.16 10.00 1.299 3.78 4.91 1,473
Sub Basin 3 10-Year 1.734 0.15 10.00 0.260 3.78 0.983 295
Sub Basin 4 10-Year 3.047 0.25 5.00 0.772 4.87 3.761 1,128
Basin Storm Event Area
C2 Final tc C2*A I Q
Total
Volume
(Ac) (Ac) (in/hr) (cfs) (cf)
Sub Basin 1 100-Year 3.372 0.74 6.09 2.511 8.89 22.33 6,698
Sub Basin 2 100-Year 8.261 0.20 10.00 1.624 7.72 12.54 3,761
Sub Basin 3 100-Year 1.734 0.19 10.00 0.325 7.72 2.509 753
Sub Basin 4 100-Year 3.047 0.32 5.00 0.965 9.95 9.605 2,882
Appendix B
Colorado State University
Phemister Trail
Appendix C: Proposed Conditions Runoff Calculations
Phemister Trail
Runoff Coefficient Calculation
Character of Surface Runoff
Coefficient C
Area
A (ft2)Ci*A
Asphalt/Concrete 0.95 83,125 78,969
Landscape or Pervious surface 0.15 63,776 9,566
146,901 88,535
0.60
Character of Surface Runoff
Coefficient C
Area
A (ft2)Ci*A
Asphalt/Concrete 0.95 8,404 7,984
Gravel 0.50 919 460
Landscape or Pervious surface 0.15 350,536 52,580
TOTAL 359,859 61,024
0.17
Character of Surface Runoff
Coefficient C
Area
A (ft2)Ci*A
Asphalt/Concrete 0.95 1,061 1,008
Landscape or Pervious surface 0.15 74,457 11,169
75,518 12,177
0.16
Character of Surface Runoff
Coefficient C
Area
A (ft2)Ci*A
Asphalt/Concrete 0.95 17,937 17,040
Landscape or Pervious surface 0.15 114,776 17,216
132,713 34,257
0.26
Streets, Parking Lots, Drives:
Lawns, Sandy Soil:
TOTAL
Sub Basin 3 -
Streets, Parking Lots, Drives:
Lawns, Sandy Soil:
TOTAL
Sub Basin 4 -
9/12/2023
TOTAL
Sub Basin 2 -
Streets, Parking Lots, Drives:
Lawns, Sandy Soil:
Sub Basin 1 -
Streets, Parking Lots, Drives:
Lawns, Sandy Soil:
Appendix C
Phemister Trail
Time of Concentration Project Location: Phemister Trail Calculated By: NDND
Date: 9/21/2023
Site Calculations:
Design Storm (yr): 2
Basin Data Final tc Remarks
Basin Sub-basin
Area
(Ac)Ci*A
Frequency
Adustment
Factor
C2Cf
Length
(ft)Start Elev. End Elev.
Slope
(%)
ti
(min)
Length
(ft)Start Elev. End Elev.
Slope
(%)
Roughness
Coefficient
Hydraulic
Radius
(ft)
Velocity
(ft/s)
tt
(min)
tc
(min)L tc
tc
(min)
Minimum
(min)
Sub Basin 1 1 3.372 0.60 1 0.60 0 5010 5010 0.00% 0.00 803 5010 5000.5 1.18% 0.013 0.074 2.20 6.09 6.09 803 14.46 6.09 5.0
Sub Basin 2 2 8.261 0.17 1 0.17 890 4999 4991 0.90% 53.78 0.00% 0.00 53.78 890 10.00 10.00 5.0
Sub Basin 3 3 1.734 0.16 1 0.16 123 4998 4991 5.69% 10.91 0.00% 0.00 10.91 123 10.00 10.00 5.0
Sub Basin 4 4 3.047 0.26 1 0.26 36 4999 4994.4 12.78% 4.04 0.00% 0.00 4.04 36 10.00 5.00 5.0
Design Storm (yr): 10
Basin Data Final tc Remarks
Basin Sub-basin
Area
(Ac)Ci*A
Frequency
Adustment
Factor
C2Cf
Length
(ft)Start Elev. End Elev.
Slope
(%)
ti
(min)
Length
(ft)Start Elev. End Elev.
Slope
(%)
Roughness
Coefficient
Hydraulic
Radius
(ft)
Velocity
(ft/s)
tt
(min)
tc
(min)L tc
tc
(min)
Minimum
(min)
Sub Basin 1 1 3.372 0.60 1 0.60 0 5010 5010 0.00% 0.00 803 5010 5000.5 1.18% 0.013 0.074 2.20 6.09 6.09 803 14.46 6.09 5.0
Sub Basin 2 2 8.261 0.17 1 0.17 890 4999 4991 0.90% 53.78 0.00 53.78 890 10.00 10.00 5.0
Sub Basin 3 3 1.734 0.16 1 0.16 123 4998 4991 5.69% 10.91 0.00 10.91 123 10.00 10.00 5.0
Sub Basin 4 4 3.047 0.26 1 0.26 36 4999 4994.4 12.78% 4.04 0.00 4.04 36 10.00 5.00 5.0
Design Storm (yr): 100
Basin Data Final tc Remarks
Basin Sub-basin
Area
(Ac)Ci*A
Frequency
Adustment
Factor
C2Cf
Length
(ft)Start Elev. End Elev.
Slope
(%)
ti
(min)
Length
(ft)Start Elev. End Elev.
Slope
(%)
Roughness
Coefficient
Hydraulic
Radius
(ft)
Velocity
(ft/s)
tt
(min)
tc
(min)L tc
tc
(min)
Minimum
(min)
Sub Basin 1 1 3.372 0.60 1.25 0.75 0 5010 5010 0.00% 0.00 803 5010 5000.5 1.18% 0.013 0.074 2.20 6.09 6.09 803 14.46 6.09 5.0
Sub Basin 2 2 8.261 0.17 1.25 0.21 890 4999 4991 0.90% 51.33 0.00 51.33 890 10.00 10.00 5.0
Sub Basin 3 3 1.734 0.16 1.25 0.20 123 4998 4991 5.69% 10.44 0.00 10.44 123 10.00 10.00 5.0
Sub Basin 4 4 3.047 0.26 1.25 0.32 36 4999 4994.4 12.78% 3.73 0.00 3.73 36 10.00 5.00 5.0
tc Alternative MethodInitial/Overland Time (t i) Travel Time (tt)
Initial/Overland Time (t i) Travel Time (tt)tc Alternative Method
Initial/Overland Time (t i) Travel Time (tt)tc Alternative Method
Appendix C
Phemister Trail Project Location: Phemister Trail
Storm Drainage Design Calculated By: ND
Date: 9/21/2023
Site Calculations:
Direct Runoff
Basin Storm Event Area
C2 Final tc C2*A I Q
Total
Volume
(Ac)(Ac)(in/hr)(cfs)(cf)
Sub Basin 1 2-Year 3.372
0.60
6.09 2.032 2.66 5.40 1,620
Sub Basin 2 2-Year 8.261 0.17 10.00 1.401 2.21 3.10 929
Sub Basin 3 2-Year 1.734 0.16 10.00 0.280 2.21 0.618 185
Sub Basin 4 2-Year 3.047 0.26 5.00 0.786 2.85 2.241 672
Basin Storm Event Area
C2 Final tc C2*A I Q
Total
Volume
(Ac) (Ac) (in/hr) (cfs) (cf)
Sub Basin 1 10-Year 3.372 0.60 6.09 2.032 4.54 9.22 2,767
Sub Basin 2 10-Year 8.261 0.17 10.00 1.401 3.78 5.30 1,589
Sub Basin 3 10-Year 1.734 0.16 10.00 0.280 3.78 1.057 317
Sub Basin 4 10-Year 3.047 0.26 5.00 0.786 4.87 3.830 1,149
Basin Storm Event Area
C2 Final tc C2*A I Q
Total
Volume
(Ac) (Ac) (in/hr) (cfs) (cf)
Sub Basin 1 100-Year 3.372 0.75 6.09 2.541 8.89 22.59 6,778
Sub Basin 2 100-Year 8.261 0.21 10.00 1.751 7.72 13.52 4,056
Sub Basin 3 100-Year 1.734 0.20 10.00 0.349 7.72 2.697 809
Sub Basin 4 100-Year 3.047 0.32 5.00 0.983 9.95 9.781 2,934
Appendix C