HomeMy WebLinkAboutReports - Drainage - 11/19/2025
Preliminary Drainage Report
Fort Collins Southeast Community Center
Rock Creek Drive
Fort Collins, CO 80528
November 19, 2025
CE Project No.: 326-034-24
PREPARED BY:
123 N College Avenue, Suite 200
Fort Collins, CO 80524
970.818.8999
clarkenersen.com
PREPARED FOR:
The City of Fort Collins
222 LaPorte Avenue, Fort Collins, Colorado 80521
Engineer Certification of Drainage Report
Shane Boyle, P.E.
Registered Professional Engineer
State of Colorado No. 40185
Contents
INTRODUCTION 1
DRAINAGE DESIGN CRITERIA 2
PRE-DEVELOPMENT HYDROLOGY 2
Table 1. Existing Runoff Summary 3
POST-DEVELOPMENT HYDROLOGY 3
Table 2. Proposed Runoff Summary 6
DETENTION AND WATER QUALITY 7
Table 3. Detention and Water Quality Summary 7
HYDRAULIC STRUCTURES 7
Table 4. Storm Sewer Summary 8
Table 5. Inlet Summary 8
EROSION CONTROL MEASURES 9
CONCLUSION 9
APPENDIX A. A
General Site Information A
APPENDIX B. B
Hydrologic and Detention Calculations B
APPENDIX C. C
Hydraulic Calculations C
1
INTRODUCTION
The Fort Collins Southeast Community Center (referred herein as “the site”) is located on the southeast corner
of Ziegler Road and Rock Creek Drive, directly west of Fossil Ridge High School. The site is located within the
west half of the southwest quarter of section 4, township 6 north, range 68 west of the 6 th Principal Meridian
in the City of Fort Collins, County of Larimer, State of Colorado.
A geotechnical report was completed for the site and the results showed existing clayey sand and sandy clay
underlain by claystone bedrock that was encountered at depths ranging from 19’ to 28’ depending on the test
hole. Groundwater was found at depths ranging from 15’ to 18’ and are not expected to be an issue for the
proposed project.
Image 1. Aerial Image (Google Earth July 2025)
PROJECT
LOCATION
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ROCK CREEK DRIVE
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DRAINAGE DESIGN CRITERIA
Stormwater for the site will generally flow away from the building and into proposed stormwater
infrastructure. The proposed infrastructure consists of vertical curb and gutter, area inlets, swales, curb inlets,
roof drains, pipes, and a stormwater detention pond. Water quality treatment and detention for the site is
required and will be placed along the southwest and south edges of the site. LID is incorporated into the
downstream drainage system and will treat 100% of the captured site runoff. A SWMP permit will be required
for the proposed project and will be obtained by the contractor before construction starts. BMP’s will be
placed where needed in order to minimize sediment leaving the site. Offsite flows are not anticipated and are
not accounted for in this development. This site is not within a 100-year City or FEMA floodplain. This
drainage and erosion control report is in conformance with the City of Fort Collins’ Storm Drainage Design &
Technical Criteria, applicable Master Plan, the Mile High Flood District Drainage Criteria Manual, and Colorado
Department of Public Health & Environment, Water Quality Control Division.
PRE-DEVELOPMENT HYDROLOGY
The Pre-Development Conditions are undeveloped agricultural soils. The existing slopes on the site range
from 2% to approximately 14%. The existing onsite drainage flows through the site naturally in a sheet flow
manner. Existing drainage patterns on the site are currently divided into four distinct areas and flow paths.
Basin E1 encompasses the middle portion of the site and is conveyed to an existing retention area at the
southern portion of the site. This area currently does not have an outfall, so holds water until it infiltrates.
Basin E2 is located along the eastern edge of the site. This area currently sheet flows into the Fossil Ridge
High School site and is conveyed downstream along with the drainage from the high school. Basin E3 is
located in the northeastern corner of the site. This area includes a large water vault owned by FCLWD and
currently drains into Rock Creek Drive, where it is conveyed east in existing drainage infrastructure before
discharging into FCRID. Finally, Basin E4 is located along the western edge of the site and consists of area that
currently drains into Ziegler Road. This basin primarily includes existing streetside sidewalk that is located
outside the right-of-way. Runoff from Basin E4 is conveyed to the south in curb & gutter, then is conveyed
into Saber Cat Drive, where it joins the rest of the runoff from the high school to be conveyed downstream to
the detention pond located at the southwestern corner of the high school site.
The current ground cover is flat and all pervious cover. The calculations that are shown below in Table 1.
Existing Runoff Summary represents an analysis of the overall site, primarily for use in comparing Existing vs.
Proposed runoff and determining sizing for the proposed detention pond. There are no sensitive or valuable
natural habitat areas located on, or adjacent to, the site. There are no wetlands, open channels, or streams
existing on the site. McClellands Creek is located approximately ½ mile to the south of the site.
3
Table 1. Existing Runoff Summary
BASIN DESIGN PT. AREA
(AC)
% IMP. C10 C100 Q10 (cfs) Q100 (cfs)
E1 E1 6.50 2.0% 0.250 0.313 5.34 13.62
E2 E2 3.34 2.1% 0.251 0.313 2.76 7.02
E3 E3 0.44 3.7% 0.261 0.327 0.56 1.44
E4 E4 0.11 78.1% 0.855 1.000 0.30 0.72
TOTAL SITE 10.4 2.9% 0.257 0.321 10.10 25.79
POST-DEVELOPMENT HYDROLOGY
The scope of this project includes a proposed building, an adjacent parking lot and sidewalks, an outdoor
swimming pool, a rain garden, and a detention pond. The Post-Development Conditions drainage analysis
includes a detailed breakdown and analysis of the area contained within the project boundaries of the
proposed project for use in modeling the proposed storm sewer and sizing of proposed inlets and detention
infrastructure. All stormwater infrastructure proposed with this project will be owned and maintained by the
City of Fort Collins. Since the parcel is owned by the City, no stormwater easements are proposed.
Construction phasing is expected for some of the perimeter parking areas. These areas are being shown as
designed on the Grading plan and are accounted for in the proposed condition drainage calculations for the
site. Refer to the Site Plan for the extents of the phased parking areas. Construction is expected to take
approximately 12 months for full completion.
The calculations that are shown below in Table 2. Proposed Runoff Summary represent the detailed post-
development conditions for the project site. See Appendix B – Hydrologic and Detention Calculations for
Pre-Development and Post-Development Rational Method calculations and Pre-Development and Post-
Development detention calculations. Proposed conditions inlet and storm sewer modeling are shown in
Appendix C. Hydraulic Calculations. See below for a detailed summary of the individual site basins used for
storm sewer modeling, as well as the overall basin used in subsequent water quality and detention volume
calculations. Rainfall intensity data and detention calculations are based on the City of Fort Collins Stormwater
Criteria Manual. The basin boundary map for both Pre-Development and Post-Development Hydrology can
be found in Appendix A – General Site Information. Please note that the total site contribution in the Post-
Development condition is smaller than in the Pre-Development condition due to the outdoor pool areas
being self-contained, so they do not contribute runoff to the overall site.
BASINS P1, P2, and P3
These basins are located along the northern edge of the site and all drain to proposed area inlets and into the
proposed onsite storm sewer system. All of the site area south of the existing roadside sidewalk is included in
these basins. The developed area for these basins is predominantly landscaped areas, along with an
emergency access drive and plaza areas.
4
BASIN P4
BASIN P4 consists of the site area along the western portion of the building. This basin will collect all of the
site runoff west of the exiting roadside sidewalk in a proposed area inlet and into the proposed onsite storm
sewer system. Due to the fact that the existing sidewalk is not completely contained within the right-of-way, it
will not be possible to collect this area along with the rest of the onsite drainage.
BASIN P5
BASIN P5 consists of the roof area of the western portion of the building. This basin will be collected in roof
drains and piped to the proposed onsite storm sewer system. It is expected that there will be more than one
roof drain for this area, but the basin has been combined into a single area for purposes of storm sewer sizing.
BASIN P6
BASIN P6 consists of the area of the site near the front door of the building and consists primarily of
courtyard, sidewalk, and parking areas along with landscape features in the front courtyard. Runoff from this
basin will primarily sheet flow to the curb & gutter located along the southern edge of the basin and then into
a proposed 5’ Type R inlet. This inlet is part of the proposed onsite storm system, which conveys runoff to the
proposed water quality and detention basins.
BASIN P7
BASIN P7 is located at the northeastern corner of the proposed building and consists primarily of the
emergency and maintenance access for the gym and pool area. Runoff from this area will be conveyed via a
combination of sheet flow and concentrated flow into a proposed 5’ Type R inlet. This inlet is the upstream
end of the storm sewer system that runs along the eastern side of the building.
BASIN P8 and P11
BASINS P8 and P11 consist of the roof area for the eastern portion of the building. This basin will be collected
in roof drains and piped to the proposed onsite storm sewer system that runs along the eastern side of the
building. These basins are being calculated separately based on their entrance points into the proposed storm
sewer system.
BASIN P9 and P12
BASINS P9 and P12 consist of the pool deck area outside of the pool surfaces. These basins will be collected in
a proposed trench drain system and conveyed to the proposed onsite storm sewer system. These basins are
being calculated separately based on their entrance points into the proposed storm sewer system. Please note
that the areas within the pools are self-contained and are not included in the drainage calculations for the
proposed site.
BASIN P10
BASIN P10 is a small landscape area at the northeastern corner of the site between the pool deck and the
emergency and maintenance access road. Runoff from this area will be collected in a proposed area inlet and
piped to the proposed onsite storm sewer system.
5
BASIN P13
BASIN P13 consists of the site area to the east of the front door of the building and the parking area south of
the outdoor pool. This basin consists primarily of courtyards, sidewalks, and parking areas along with
landscape features in the front courtyard. Runoff from this basin will primarily sheet flow to the curb & gutter
located along the southern edge of the basin and then through a curb cut into a proposed flared end section.
From there, the runoff will be piped to the proposed onsite storm sewer system.
BASIN P14
BASIN P14 is located at the center of the site and consists of a large portion of the proposed parking area.
This basin also includes some of the phase 2 perimeter parking, which is included in these calculations to
account for the impervious area in the future without needing to modify the proposed storm sewer and
detention system. Runoff from this area will be conveyed via a combination of sheet flow and concentrated
flow in proposed curb & gutter to a curb cut at the southeastern corner of the basin. This curb cut then
discharges into the proposed rain garden.
BASIN P15
BASIN P15 is located at the center of the site and consists of the remainder of the main parking area and the
access drive into the site. This basin also includes some of the phase 2 perimeter parking, which is included in
these calculations to account for the impervious area in the future without needing to modify the proposed
storm sewer and detention system. Runoff from this area will be conveyed via a combination of sheet flow
and concentrated flow in proposed curb & gutter to a curb cut at the southeastern corner of the basin. This
curb cut then discharges into the proposed rain garden.
BASIN P16
BASIN P16 is located at the southern portion of the site and consists primarily of the detention and water
quality basin, along with soft surface paths and a bike trail. This basin will collect all of the site runoff west of
the exiting roadside sidewalk. Due to the fact that the existing sidewalk is not completely contained within the
right-of-way, it will not be possible to collect this area along with the rest of the onsite drainage.
BASIN P17
BASIN P17 is the strip of site area along the western edge of the site. This basin consists primarily of the strip
of existing sidewalk that is not contained within the right-of-way and a small portion of the drive entrance
that can’t be captured due to grading into the site. This basin corresponds to Basin E4 in the Pre-
Development Hydrology condition. Due to the added drive area, this basin increases from 0.11 acres to 0.13
acres and from 0.72 to 1.14 cfs. Runoff from Basin E4 is conveyed to the south in curb & gutter, then is
conveyed into Saber Cat Drive, where it joins the rest of the runoff from the high school to be conveyed
downstream to the detention pond located at the southwestern corner of the high school site. As will be
discussed in the Detention and Water Quality section later in this report, the total flow into the high school
site will be reduced with this development and the allowable site release will be below what is allowed per
City criteria, so the small addition in runoff to this basin is considered to be negligible.
6
BASIN P18
BASIN P18 is located in the northeastern corner of the site. This area includes a large water vault owned by
FCLWD and currently drains into Rock Creek Drive, where it is conveyed east in existing drainage
infrastructure before discharging into FCRID. This basin corresponds to Basin E3 in the Pre-Development
Hydrology condition. Due to the onsite grading, this basin decreases from 0.44 acres to 0.16 acres and from
1.12 to 0.53 cfs. Due to the existing grading around the water vault, it is not possible to capture this entire
area of the site.
BASIN P19
BASIN P19 is located along the eastern edge of the site. This area currently sheet flows into the Fossil Ridge
High School site and is conveyed downstream along with the drainage from the high school. This basin
corresponds to Basin E2 in the Pre-Development Hydrology condition. Due to site grading constraints, it is
not possible to capture runoff from the entire basin. In the proposed condition. This basin decreases from 3.34
acres to 0.56 acres and from 7.02 to 2.68 cfs.
Table 2. Proposed Runoff Summary
BASIN DESIGN PT. AREA (AC) % IMP. C10 C100 Q10 (cfs) Q100 (cfs)
P1 P1 0.13 7.9% 0.297 0.372 0.15 0.39
P2 P2 0.59 26.6% 0.446 0.557 0.95 2.44
P3 P3 0.23 10.7% 0.319 0.399 0.29 0.74
P4 P4 0.70 6.7% 0.287 0.359 0.70 1.80
P5 P5 0.69 90.0% 0.950 1.000 3.19 6.86
P6 P6 0.76 60.9% 0.697 0.871 2.16 5.52
P7 P7 0.27 67.6% 0.720 0.900 0.83 2.12
P8 P8 0.41 90.0% 0.950 1.000 1.88 4.03
P9 P9 0.13 90.0% 0.950 1.000 0.56 1.20
P10 P10 0.11 2.0% 0.250 0.313 0.10 0.25
P11 P11 0.56 90.0% 0.950 1.000 2.58 5.56
P12 P12 0.47 90.0% 0.950 1.000 2.20 4.72
P13 P13 0.54 59.5% 0.669 1.836 1.37 3.49
P14 P14 1.19 88.1% 0.873 1.000 4.48 10.48
P15 P15 0.64 93.9% 0.915 1.000 2.85 6.36
P16 P16 1.78 3.3% 0.261 0.326 1.83 4.67
P17 P17 0.13 87.7% 0.927 1.000 0.58 1.29
P18 P18 0.16 3.0% 0.258 0.322 0.21 0.53
P19 P19 0.56 22.6% 0.409 0.511 1.05 2.68
TOTAL SITE 10.1 51.6% 0.628 0.785 20.13 51.44
7
DETENTION AND WATER QUALITY
There is a proposed water quality treatment and stormwater detention basin along the west and southwest
sides of the site to provide detention for the entire site. Stormwater for the developed portion of the site is
collected in the proposed drainage inlets and conveyed to the detention pond via a proposed storm sewer
system or via proposed curb & gutter. Water quality treatment for the site is required and will be satisfied by
the installation of a rain garden adjacent to the detention basin. LID is provided for 100% of the collected site
runoff, thus satisfying the City’s LID requirement.
The detention requirements for the site are provided in the McClellands Creek Stormwater Master Plan. For
this portion of the basin, the allowable release rates are 0.2 cfs per acre for the 10-year storm and 0.5 cfs per
acre for the 100-year storm. This equates to a total allowable release of 2.08 cfs for the 10-year storm and
5.20 cfs for the 100-year storm. However, to simplify the outlet structure, we are proposing a single orifice
opening rather than a 2-stage release. Additionally, in order to take advantage of the available storage in the
detention basin, the proposed release rate will be reduced to 0.94 cfs for the 10-year storm and 1.01 cfs for
the 100-year storm. These release rates allow for a single 3-7/8 inch diameter orifice opening for both the 10-
year and 100-year storms while still allowing for more than 1’ of freeboard in the detention basin.
Detention and water quality calculations are included in Appendix B – Hydrologic and Detention
Calculations and summarized in Table 3 below.
Table 3. Detention and Water Quality Summary
NAME Allowable
Release (cfs)
Provided
Release (cfs)
Qin
(cfs)
Qout
(cfs)
Volume Required
(ac-ft)
Volume Provided
(ac-ft)
10-YEAR DETENTION 2.08 0.94 20.13 0.94 1.447 1.447
100-YEAR DETENTION 5.20 1.01 51.44 1.01 1.817 1.817
RAIN GARDEN 0.212 0.212
TOTAL 2.03 2.03
HYDRAULIC STRUCTURES
Currently, there are no hydraulic structures on site. In the post-project condition, there will be roof drains,
curb inlets, storm pipe and outlet structures as part of this project. Additionally, a detention pond and rain
garden will be constructed that will account for runoff from this site. These new hydraulic structures will
account for all stormwater runoff from the developed site and it will be conveyed to the proposed
downstream detention basin via storm pipe and outfall at a flared end section. Below is a detailed analysis of
the proposed onsite storm sewer system.
8
Storm Sewers
The proposed drainage system was modeled using UD-Sewer software. The storm sewer model output for the
100-year storm is included in Appendix C. Hydraulic Calculations and summarized in Table 4. Storm Sewer
Summary below.
Table 4. Storm Sewer Summary
STORM SEWER Q100 (cfs) PIPE SIZE VELOCITY
ADS DB SL 1 39.11 42” 5.4 FPS
ADS DB SL 2 39.11 42” 5.4 FPS
ADS DB SL 3 35.62 42” 5.4 FPS
CURB INLET 1 17.74 30” 4.3 FPS
ADS DB GL 1 12.22 27” 4.0 FPS
ADS DB SL 8 10.42 24” 3.7 FPS
ADS DB GL 2 3.57 18” 3.1 FPS
ADS DB GL 3 2.82 15” 2.7 FPS
ADS DB GL 4 0.39 12” 2.3 FPS
ADS DB SL 4 17.89 30” 4.3 FPS
ADS DB SL 5 17.89 30” 4.3 FPS
ADS DB SL 6 13.16 27” 4.0 FPS
ADS DB SL 7 7.61 21” 3.4 FPS
ADS DB GL 5 1.46 12” 3.7 FPS
CURB INLET 2 2.12 15” 2.7 FPS
FES IN 3.49 12” 8.1 FPS
Inlets
The proposed drainage inlets were analyzed using UD-Inlet software. The inlet spreadsheet output for the
100-year storm is included in Appendix C. Hydraulic Calculations and summarized in Table 5. Storm Sewer
Summary below.
Table 5. Inlet Summary
INLET NAME Q10 (cfs) PONDING DEPTH Q100 (cfs) PONDING DEPTH
ADS Drain 1 0.7 0.23 1.8 0.33
ADS Drain 2 0.3 0.16 0.7 0.23
ADS Drain 3 1.0 0.26 2.4 0.37
ADS Drain 4 0.2 0.12 0.4 0.18
ADS Drain 5 0.1 0.10 0.3 0.15
Curb Inlet 1 2.2 0.25 5.5 0.39
Curb Inlet 2 0.8 0.33 2.1 0.51
9
EROSION CONTROL MEASURES
A SWMP permit will be required and will be obtained by the contractor before construction begins. The
contractor will incorporate typical BMPs as part of the construction activities, with the intent to follow all State
and City requirements for stormwater runoff control. Permanent erosion control will be provided by paving of
proposed parking areas and sidewalks, slope protection is specific areas, with revegetation and/or landscape
mulch being provided for the remainder of the disturbed construction area. For more in-depth detail on the
erosion control measures, see the erosion control report for this project. A detailed Erosion Control Report per
the City of Fort Collins criteria is provided separately.
CONCLUSION
The proposed drainage design for this site is in conformance with City of Fort Collins published criteria.
Proposed stormwater infrastructure has been designed to adequately and safely convey stormwater runoff to
the proposed detention basin. Release rates from the detention basin are in conformance with the City’s
Stormwater Criteria Manual and the McClellands Creek Stormwater Master Plan. LID treatment is provided for
100% of the captured runoff from the site. No variances from the criteria are proposed with this development.
A
APPENDIX A.
General Site Information
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ROCK CREEK DRIVE
E1
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PREPARED FOR PRELIMINARY
SUBMISSION AND REVIEW ONLY --
NOT FOR CONSTRUCTION.
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Architecture Engineering Planning
Landscape Architecture Commissioning
clarkenersen.com
Kansas City, Missouri
Lincoln, Nebraska
Lawrence, Kansas
Portland, Oregon
Fort Collins, Colorado
Omaha, Nebraska
Charleston, South Carolina
PDP/FDP Submittal -
Round 1
Southeast Community
Center
Rock Creek Dr & Ziegler Rd
Fort Collins, CO 80528
326-034-24
11/19/2025
Existing Conditions
Drainage Plan
C3.08
PROPOSED CONTOUR
EXISTING CONTOUR
LEGEND
FLOWLINE
1
0.50 0.80
BASIN NUMBER
C100
BASIN AREA
MH
DRAIN BASIN LIMITS
PROPOSED STORM INLET
PROPOSED STORM LINE
PROPOSED STORM MANHOLE
EXISTING STORM MANHOLE
SCALE: 1" = 50'
EXISTING CONDITIONS DRAINAGE PLAN
0'25'50'100'
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PROPERTY LINE
PROPERTY LINE
PROPERTY LINE
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P1
0.13 0.37
P5
0.69 1.00
P8
0.41 1.00
P6
0.76 0.87
P13
0.54 0.84
P14
1.19 1.00
P15
0.64 1.00
P9
0.13 1.00
P11
0.56 1.00
P12
0.47 1.00
P4
0.70 0.36
P18
0.16 0.32
P10
0.11 0.31
P16
1.78 0.33
P17
0.13 1.00
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0.59 0.56
P3
0.23 0.40
P7
0.27 0.90
P19
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DRAFT
PREPARED FOR PRELIMINARY
SUBMISSION AND REVIEW ONLY --
NOT FOR CONSTRUCTION.
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:
Architecture Engineering Planning
Landscape Architecture Commissioning
clarkenersen.com
Kansas City, Missouri
Lincoln, Nebraska
Lawrence, Kansas
Portland, Oregon
Fort Collins, Colorado
Omaha, Nebraska
Charleston, South Carolina
PDP/FDP Submittal -
Round 1
Southeast Community
Center
Rock Creek Dr & Ziegler Rd
Fort Collins, CO 80528
326-034-24
11/19/2025
Proposed Conditions
Drainage Plan
C3.09
PROPOSED CONTOUR
EXISTING CONTOUR
LEGEND
FLOWLINE
1
0.50 0.80
BASIN NUMBER
C100
BASIN AREA
MH
DRAIN BASIN LIMITS
PROPOSED STORM INLET
PROPOSED STORM LINE
PROPOSED STORM MANHOLE
EXISTING STORM MANHOLE
SCALE: 1" = 50'
PROPOSED CONDITIONS DRAINAGE PLAN
0'25'50'100'
P
1
DESIGN POINT
B
APPENDIX B.
Hydrologic and Detention Calculations
Runoff Coefficients and % Impervious
Roof (1)Asphalt Walks(1)Gravel(1)Lawns(1)
%I = 90% %I = 100% %I = 90% %I =40% %I=2%
acres sf sf sf sf sf sf C2 C10 C100
E1 E1 6.50 283017 0 0 0 0 283017 2.0% C/D 0.250 0.250 0.313
E2 E2 3.34 145586 0 0 118 0 145468 2.1% C/D 0.251 0.251 0.313
E3 E3 0.44 19304 0 0 0 867 18437 3.7% C/D 0.261 0.261 0.327
E4 E4 0.11 4840 0 0 4183 0 657 78.1% C/D 0.855 0.855 1.000
TOTAL 10.4 452747 0 0 4301 867 447579 2.9% C/D 0.257 0.257 0.321
P1 P1 0.13 5852 0 0 395 0 5457 7.9% C/D 0.297 0.297 0.372
P2 P2 0.59 25701 0 0 7181 0 18520 26.6% C/D 0.446 0.446 0.557
P3 P3 0.23 10116 0 0 996 0 9120 10.7% C/D 0.319 0.319 0.399
P4 P4 0.70 30426 0 0 1621 0 28805 6.7% C/D 0.287 0.287 0.359
P5 P5 0.69 30016 30016 0 0 0 0 90.0% C/D 0.950 0.950 1.000
P6 P6 0.76 32922 0 8745 12282 0 11895 60.9% C/D 0.697 0.697 0.871
P7 P7 0.27 11631 0 7545 268 0 3818 67.6% C/D 0.720 0.720 0.900
P8 P8 0.41 17657 17657 0 0 0 0 90.0% C/D 0.950 0.950 1.000
P9 P9 0.13 5629 0 0 5629 0 0 90.0% C/D 0.950 0.950 1.000
P10 P10 0.11 4575 0 0 0 0 4575 2.0% C/D 0.250 0.250 0.313
P11 P11 0.56 24338 24338 0 0 0 0 90.0% C/D 0.950 0.950 1.000
P12 P12 0.47 20669 0 0 20669 0 0 90.0% C/D 0.950 0.950 1.000
P13 P13 0.54 23560 0 10553 3160 1086 8761 59.5% C/D 0.669 0.669 0.836
P14 P14 1.19 51855 0 40313 5866 0 5676 88.1% C/D 0.873 0.873 1.000
P15 P15 0.64 27864 0 23323 3128 0 1413 93.9% C/D 0.915 0.915 1.000
P16 P16 1.78 77693 0 0 1191 0 76502 3.3% C/D 0.261 0.261 0.326
P17 P17 0.13 5640 0 376 5075 0 189 87.7% C/D 0.927 0.927 1.000
P18 P18 0.16 7162 0 0 81 0 7081 3.0% C/D 0.258 0.258 0.322
P19 P19 0.56 24574 0 1540 4029 0 19005 22.6% C/D 0.409 0.409 0.511
TOTAL 10.1 437880 72011 92395 71571 1086 200817 51.6% C/D 0.628 0.628 0.785
Notes:
(1) Recommended % Imperviousness Values from USDCM Vol 1 - Ch 5 - Table RO-3. Increased Lawns from 0% to 2% Impervious.
(2) Runoff C is based on %I, UDFCD Eq RO-7 and correction factors in Table RO-4.
(3) Impervious area assumed to be 2500 s.f. of roof and 500 s.f. of driveway per single family and twin home lot.
Proposed Basins
Existing Basins
Basin
Areas
Composite
Imperviousness
(%I)
Total TotalDesign Pt.Composite Runoff CoefficientsNRCS Soil
Type
Calculations by: SB
Date: 4/26/2023 \\Ce-co-srv-004\300-399\326-034-24 FoCo Southeast Community Center\Civil\Drainage Calcs\326034 - Drainage Calcs.xlsm
Time of Concentration
Area Length Slope ti
(2)Length Slope Velocity (3)tt
(4)Check tc?Total
Length tc
(5)
acres ft %min ft %fps min min Urban?ft min min
E1 E1 6.50 0.25 780 1.3 39.2 0 1 7 0.7 0.0 39.2 Yes 780 14 14
E2 E2 3.34 0.25 655 1 39.1 0 1 7 0.7 0.0 39.1 Yes 655 14 14
E3 E3 0.44 0.26 10 2 3.8 65 1 7 0.7 1.5 5.3 Yes 75 10 5
E4 E4 0.11 0.85 10 2 1.1 800 1 7 0.7 19.0 20.2 Yes 810 15 15
TOTAL 10.4 0.26 65 2 9.7 0 1 7 0.7 0.0 9.7 Yes 65 10 10
P1 P1 0.13 0.30 80 1.6 11.1 0 1 20 2.0 0.0 11.1 Yes 80 10 10
P2 P2 0.59 0.45 145 1.8 11.7 0 1 20 2.0 0.0 11.7 Yes 145 11 11
P3 P3 0.23 0.32 80 3.0 8.8 0 1 20 2.0 0.0 8.8 Yes 80 10 9
P4 P4 0.70 0.29 305 0.8 28.1 0 1 20 2.0 0.0 28.1 Yes 305 12 12
P5 P5 0.69 0.95 170 1.0 3.5 0 1 20 2.0 0.0 3.5 Yes 170 11 5
P6 P6 0.76 0.70 180 1.8 8.1 0 1 20 2.0 0.0 8.1 Yes 180 11 8
P7 P7 0.27 0.72 100 1.0 6.8 40 1 20 2.0 0.3 7.2 Yes 140 11 7
P8 P8 0.41 0.95 165 1.0 3.5 0 1 20 2.0 0.0 3.5 Yes 165 11 5
P9 P9 0.13 0.95 170 0.2 6.0 0 1 20 2.0 0.0 6.0 Yes 170 11 6
P10 P10 0.11 0.25 70 1.9 10.4 0 1 20 2.0 0.0 10.4 Yes 70 10 10
P11 P11 0.56 0.95 175 1.0 3.6 0 1 20 2.0 0.0 3.6 Yes 175 11 5
P12 P12 0.47 0.95 100 0.4 3.7 0 1 20 2.0 0.0 3.7 Yes 100 11 5
P13 P13 0.54 0.67 240 2.0 9.6 100 2.4 20 3.1 0.5 10.1 Yes 340 12 10
P14 P14 1.19 0.87 125 1.3 4.2 235 0.9 15 1.4 2.8 6.9 Yes 360 12 7
P15 P15 0.64 0.91 100 2.2 2.6 325 0.9 20 1.9 2.9 5.4 Yes 425 12 5
P16 P16 1.78 0.26 300 25.0 9.0 0 1 20 2.0 0.0 9.0 Yes 300 12 9
P17 P17 0.13 0.93 10 2.0 0.8 0 1 20 2.0 0.0 0.8 Yes 10 10 5
P18 P18 0.16 0.26 10 2.0 3.8 0 1 20 2.0 0.0 3.8 Yes 10 10 5
P19 P19 0.56 0.41 20 1.0 5.6 0 1 20 2.0 0.0 5.6 Yes 20 10 6
TOTAL 10.1 0.63 100 2.1 6.7 845 0.4 20 1.3 11.1 17.8 Yes 945 15 15
Notes:
(1) C5 based on initial ground type and Table RO-5 (4)tt=L/(V*60 sec/min)
(2)ti = [1.8(1.1-C5)L1/2]/S1/3, S= slope in %, L=length of overland flow (400' max)(5)tc check (for urban or developed areas only) = total length/180 + 10
(3)V=CvS0.5, S=watercourse slope in ft/ft, UDFCD Equation RO-4 (6)min tc = 5 min
Proposed Basins
Existing Basins
C5
(1)Cv
ti+tt Final tc
(6)
tc Check for Urbanized
Basin
Initial Overland Flow Time (ti)Travel/Channelized Time of Flow (tt)
Design Pt.
Calculations by: SB
Date: 4/26/2023 \\Ce-co-srv-004\300-399\326-034-24 FoCo Southeast Community Center\Civil\Drainage Calcs\326034 - Drainage Calcs.xlsm
Rational Method Peak Runoff
Final
tc
(6)I2 I10 I100 Q2 Q10 Q100
acre min in/hr in/hr in/hr cfs cfs cfs
E1 E1 6.50 14 0.250 0.250 0.313 1.92 3.29 6.71 3.12 5.34 13.62
E2 E2 3.34 14 0.251 0.251 0.313 1.92 3.29 6.71 1.61 2.76 7.02
E3 E3 0.44 5 0.261 0.261 0.327 2.85 4.87 9.95 0.33 0.56 1.44
E4 E4 0.11 15 0.855 0.855 1.000 1.87 3.19 6.52 0.18 0.30 0.72
TOTAL 10.4 10 0.257 0.257 0.321 2.21 3.78 7.72 5.91 10.10 25.79
P1 P1 0.13 10 0.297 0.297 0.372 2.21 3.78 7.72 0.09 0.15 0.39
P2 P2 0.59 11 0.446 0.446 0.557 2.13 3.63 7.42 0.56 0.95 2.44
P3 P3 0.23 9 0.319 0.319 0.399 2.30 3.93 8.03 0.17 0.29 0.74
P4 P4 0.70 12 0.287 0.287 0.359 2.05 3.50 7.16 0.41 0.70 1.80
P5 P5 0.69 5 0.950 0.950 1.000 2.85 4.87 9.95 1.87 3.19 6.86
P6 P6 0.76 8 0.697 0.697 0.871 2.40 4.10 8.38 1.26 2.16 5.52
P7 P7 0.27 7 0.720 0.720 0.900 2.52 4.31 8.80 0.48 0.83 2.12
P8 P8 0.41 5 0.950 0.950 1.000 2.85 4.87 9.95 1.10 1.88 4.03
P9 P9 0.13 6 0.950 0.950 1.000 2.67 4.56 9.31 0.33 0.56 1.20
P10 P10 0.11 10 0.250 0.250 0.313 2.21 3.78 7.72 0.06 0.10 0.25
P11 P11 0.56 5 0.950 0.950 1.000 2.85 4.87 9.95 1.51 2.58 5.56
P12 P12 0.47 5 0.950 0.950 1.000 2.85 4.87 9.95 1.28 2.20 4.72
P13 P13 0.54 10 0.669 0.669 0.836 2.21 3.78 7.72 0.80 1.37 3.49
P14 P14 1.19 7 0.873 0.873 1.000 2.52 4.31 8.80 2.62 4.48 10.48
P15 P15 0.64 5 0.915 0.915 1.000 2.85 4.87 9.95 1.67 2.85 6.36
P16 P16 1.78 9 0.261 0.261 0.326 2.30 3.93 8.03 1.07 1.83 4.67
P17 P17 0.13 5 0.927 0.927 1.000 2.85 4.87 9.95 0.34 0.58 1.29
P18 P18 0.16 5 0.258 0.258 0.322 2.85 4.87 9.95 0.12 0.21 0.53
P19 P19 0.56 6 0.409 0.409 0.511 2.67 4.56 9.31 0.62 1.05 2.68
TOTAL 10.1 15 0.628 0.628 0.785 1.87 3.19 6.52 11.80 20.13 51.44
Proposed Basins
Existing Basins
Design Pt.AreaBasin
C100
Rainfall IntensityRunoff Coefficients
C2
Peak Discharge
C10
Calculations by: SB
Date: 4/26/2023 \\Ce-co-srv-004\300-399\326-034-24 FoCo Southeast Community Center\Civil\Drainage Calcs\326034 - Drainage Calcs.xlsm
Water Quality
Area (acres)Area (acres)Watershed WQCV* (cf)
(sf)(acres)(inches)(Extended Detention)
Site 437,880 10.05 51.6%0.21 9,228
9,228
* based on 40 hr storage and additional 20% for extended detention
Basin %I
Required Water Quality Capture Volume
Total
Calculations by: SB
Date: 4/26/2023 \\Ce-co-srv-004\300-399\326-034-24 FoCo Southeast Community Center\Civil\Drainage Calcs\326034 - Drainage Calcs.xlsm
Detention Pond Volume
(FAA Method)
10 year storm into detention facility
Area (sf) Area (acres)C100
437880 10.05 0.63
Release rate out of detention system based on
Qout (cfs) cfs/acre Tc (min)
0.94 0.094 9
Rainfall
Intensity
Inflow
Volume
Adjustment
Factor
Average
Outflow Rate Outflow Volume Required
Storage Volume
I Vi=(Qin*T*60)m= 0.5(1 +
Tc/T)Qav = m*Qout Vo=Qav*T *60 Vs=Vi-Vo
min in/hr cfs ft 3 cfs ft 3 ft 3
5 9.95 62.8 18,840 1.40 1.33 398 18,441
10 7.72 48.7 29,234 0.95 0.90 540 28,695
15 6.52 41.2 37,035 0.80 0.76 682 36,354
20 5.60 35.3 42,413 0.73 0.69 823 41,589
25 4.98 31.4 47,146 0.68 0.64 965 46,181
30 4.52 28.5 51,350 0.65 0.61 1,107 50,243
35 4.08 25.8 54,076 0.63 0.59 1,249 52,828
40 3.74 23.6 56,651 0.61 0.58 1,390 55,261
45 3.46 21.8 58,961 0.60 0.57 1,532 57,429
50 3.23 20.4 61,158 0.59 0.56 1,674 59,484
55 3.03 19.1 63,108 0.58 0.55 1,816 61,292
60 2.86 18.1 64,982 0.58 0.54 1,957 63,025
70 0.00 0.0 0 0.56 0.53 2,241 -2,241
80 0.00 0.0 0 0.56 0.53 2,524 -2,524
90 0.00 0.0 0 0.55 0.52 2,808 -2,808
100 0.00 0.0 0 0.55 0.52 3,091 -3,091
110 0.00 0.0 0 0.54 0.51 3,375 -3,375
120 0.00 0.0 0 0.54 0.51 3,658 -3,658
Max Volume, ft 3 =63,025
Max Volume, ac-ft =1.447
Rainfall
Duration (T)
Qin=
∑C100*Area*I
Comments
Includes area draining to the detention pond. Entire site = 10.1 acres.
Comments
Allowable 10-year release = 0.2 cfs/acre = 2.08 cfs for the entire
site.
Required Detention Volume
Calculations by: SB
Date: 4/26/2023
\\Ce-co-srv-004\300-399\326-034-24 FoCo Southeast Community Center\Civil\Drainage Calcs\326034 - Drainage Calcs.xlsm
Detention Pond Volume
(FAA Method)
100 year storm into detention facility
Area (sf) Area (acres)C100
437,880 10.05 0.78
Release rate out of detention system based on
Qout (cfs) cfs/acre Tc (min)
1.01 0.100 9
Rainfall
Intensity
Inflow
Volume
Adjustment
Factor
Average
Outflow Rate Outflow Volume Required
Storage Volume
I Vi=(Qin*T*60)m= 0.5(1 +
Tc/T)Qav = m*Qout Vo=Qav*T *60 Vs=Vi-Vo
min in/hr cfs ft 3 cfs ft 3 ft 3
5 9.95 78.5 23,549 1.40 1.41 424 23,126
10 7.72 60.9 36,543 0.95 0.96 574 35,969
15 6.52 51.4 46,294 0.80 0.81 725 45,569
20 5.60 44.2 53,016 0.73 0.73 876 52,140
25 4.98 39.3 58,933 0.68 0.68 1,027 57,906
30 4.52 35.7 64,187 0.65 0.65 1,177 63,010
35 4.08 32.2 67,595 0.63 0.63 1,328 66,267
40 3.74 29.5 70,814 0.61 0.62 1,479 69,335
45 3.46 27.3 73,702 0.60 0.60 1,630 72,072
50 3.23 25.5 76,447 0.59 0.59 1,781 74,666
55 3.03 23.9 78,885 0.58 0.59 1,931 76,953
60 2.86 22.6 81,228 0.58 0.58 2,082 79,146
70 0.00 0.0 0 0.56 0.57 2,384 -2,384
80 0.00 0.0 0 0.56 0.56 2,685 -2,685
90 0.00 0.0 0 0.55 0.55 2,987 -2,987
100 0.00 0.0 0 0.55 0.55 3,288 -3,288
110 0.00 0.0 0 0.54 0.54 3,590 -3,590
120 0.00 0.0 0 0.54 0.54 3,892 -3,892
Max Volume, ft 3 =79,146
Max Volume, ac-ft =1.817
Comments
Required Detention Volume
Rainfall
Duration (T)
Qin=
∑C100*Area*I
Includes area draining to the detention pond. Entire site = 10.1 acres.
Comments
Allowable 100-year release = 0.5 cfs/acre = 5.20 cfs for the entire
site.
Calculations by: SB
Date: 4/26/2023
\\Ce-co-srv-004\300-399\326-034-24 FoCo Southeast Community Center\Civil\Drainage Calcs\326034 - Drainage Calcs.xlsm
DETENTION VOLUME PROVIDED
RAIN GARDEN
CONTOUR SURFACE SURFACE DEPTH BETWEEN SURFACE CUMULATIVE CUMULATIVE
ELEVATION AREA (A) AREA (B) CONTOURS VOLUME VOLUME VOLUME
(ft)(ft^2)(ft^2)(ft)(ft^3)(ft^3)(acre-ft)
INVERT 4,911.00 4700 0 0 0 0 0.000
4,912.00 5800 4700 1.0 5240.37 5,240 0.120
4,913.00 7000 5800 1.0 6390.60 11,631 0.267
4,914.00 8000 7000 1.0 7494.44 19,125 0.439
Volume Required =9228
WSEL =4912.62
DETENTION BASIN
CONTOUR SURFACE SURFACE DEPTH BETWEEN SURFACE CUMULATIVE CUMULATIVE
ELEVATION AREA (A) AREA (B) CONTOURS VOLUME VOLUME VOLUME
(ft)(ft^2)(ft^2)(ft)(ft^3)(ft^3)(acre-ft)
INVERT 4,911.00 0 0 0 0 0 0.00
4,911.50 500 0 0.5 83.33 83 0.00
4,912.00 1700 500 0.5 520.33 604 0.01
4,912.50 4200 1700 0.5 1428.68 2,032 0.05
4,913.00 8500 4200 0.5 3112.49 5,145 0.12
4,913.50 13000 8500 0.5 5335.32 10,480 0.24
4,914.00 16500 13000 0.5 7357.64 17,838 0.41
4,914.50 19000 16500 0.5 8867.66 26,705 0.61
4,915.00 20000 19000 0.5 9748.93 36,454 0.84
4,915.50 22000 20000 0.5 10496.03 46,950 1.08
4,916.00 24000 22000 0.5 11496.38 58,447 1.34
4,916.50 26000 24000 0.5 12496.67 70,943 1.63
4,917.00 28000 26000 0.5 13496.91 84,440 1.94
10-Year Volume Required =63,025
10-Year WSEL =4916.18
100-Year Volume Required =79,146
100-Year WSEL =4916.80
Orifice Calculations
10-Year Volume Provided, ft 3 =63,025
100-Year Volume Provided, ft 3 =79,146 Is Water Quality Volume Included in Detention No
Water Quality Volume, ft 3 =9,228
Total Volume Provided, ft 3 =88,374
Invert Elevation, ft = 4911.00
10-Year W.S. Elevation, ft = 4916.18
10-year Depth D, ft = 5.18
100-Year W.S. Elevation, ft = 4916.80
100-year Depth D, ft = 5.80
Spill Elevation, ft = 4918.00
Pond Freeboard = 1.20
Orifice Flow Rate, Q (cfs) = CoAo(2gHo)0.5 Area of orifice Ao, ft2 = Q
Co = 0.65 Co(2gHo)0.5
Q = Qout of pond, cfs = 0.94
gravitational acceleration g, ft/sec 2 = 32.2
diam, ft = 0.321
Effective head on orifice Ho = D-1/2diam, ft = 5.02
Area of orifice Ao, ft 2 = 0.08
Area of orifice Ao, in 2 = 11.64
diam, in = 3.85 3 7/8
Square Opening, in =3.41
Detention Volume and Depth
10-Year Orifice Opening
Calculations by:
Date: 4/26/2023 \\Ce-co-srv-004\300-399\326-034-24 FoCo Southeast Community Center\Civil\Drainage Calcs\326034 - Drainage Calcs.xlsm
C
APPENDIX C.
Hydraulic Calculations
MHFD-Inlet, Version 5.03 (August 2023)
Worksheet Protected
INLET NAME ADS Drain 1 ADS Drain 2 ADS Drain 3
Site Type (Urban or Rural)
Inlet Application (Street or Area)AREA AREA AREA
Hydraulic Condition Swale Swale Swale
Inlet Type User-Defined User-Defined User-Defined
USER-DEFINED INPUT
User-Defined Design Flows
Minor QKnown (cfs)0.7 0.3 1.0
Major QKnown (cfs)1.8 0.7 2.4
Bypass (Carry-Over) Flow from Upstream Inlets must be organized from upstream (left) to downstream (right) in order for bypass flows to be linked.
Receive Bypass Flow from:No Bypass Flow Received No Bypass Flow Received No Bypass Flow Received
Minor Bypass Flow Received, Qb (cfs)0.0 0.0 0.0
Major Bypass Flow Received, Qb (cfs)0.0 0.0 0.0
Watershed Characteristics
Subcatchment Area (acres)
Percent Impervious
NRCS Soil Type
Watershed Profile
Overland Slope (ft/ft)
Overland Length (ft)
Channel Slope (ft/ft)
Channel Length (ft)
Minor Storm Rainfall Input
Design Storm Return Period, Tr (years)
One-Hour Precipitation, P1 (inches)
Major Storm Rainfall Input
Design Storm Return Period, Tr (years)
One-Hour Precipitation, P1 (inches)
CALCULATED OUTPUT
Minor Total Design Peak Flow, Q (cfs)0.7 0.3 1.0
Major Total Design Peak Flow, Q (cfs)1.8 0.7 2.4
Minor Flow Bypassed Downstream, Qb (cfs)0.0 0.0 0.0
Major Flow Bypassed Downstream, Qb (cfs)0.0 0.0 0.0
INLET MANAGEMENT
MHFD-Inlet, Version 5.03 (August 2023)
Worksheet Protected
INLET NAME
Site Type (Urban or Rural)
Inlet Application (Street or Area)
Hydraulic Condition
Inlet Type
USER-DEFINED INPUT
User-Defined Design Flows
Minor QKnown (cfs)
Major QKnown (cfs)
Bypass (Carry-Over) Flow from Upstream
Receive Bypass Flow from:
Minor Bypass Flow Received, Qb (cfs)
Major Bypass Flow Received, Qb (cfs)
Watershed Characteristics
Subcatchment Area (acres)
Percent Impervious
NRCS Soil Type
Watershed Profile
Overland Slope (ft/ft)
Overland Length (ft)
Channel Slope (ft/ft)
Channel Length (ft)
Minor Storm Rainfall Input
Design Storm Return Period, Tr (years)
One-Hour Precipitation, P1 (inches)
Major Storm Rainfall Input
Design Storm Return Period, Tr (years)
One-Hour Precipitation, P1 (inches)
CALCULATED OUTPUT
Minor Total Design Peak Flow, Q (cfs)
Major Total Design Peak Flow, Q (cfs)
Minor Flow Bypassed Downstream, Qb (cfs)
Major Flow Bypassed Downstream, Qb (cfs)
INLET MANAGEMENT
ADS Drain 4 ADS Drain 5 Curb Inlet 1
AREA AREA STREET
Swale Swale In Sump
User-Defined User-Defined CDOT Type R Curb Opening
0.2 0.1 2.2
0.4 0.3 5.5
No Bypass Flow Received No Bypass Flow Received No Bypass Flow Received
0.0 0.0 0.0
0.0 0.0 0.0
0.2 0.1 2.2
0.4 0.3 5.5
0.0 0.0 N/A
0.0 0.0 N/A
MHFD-Inlet, Version 5.03 (August 2023)
Worksheet Protected
INLET NAME
Site Type (Urban or Rural)
Inlet Application (Street or Area)
Hydraulic Condition
Inlet Type
USER-DEFINED INPUT
User-Defined Design Flows
Minor QKnown (cfs)
Major QKnown (cfs)
Bypass (Carry-Over) Flow from Upstream
Receive Bypass Flow from:
Minor Bypass Flow Received, Qb (cfs)
Major Bypass Flow Received, Qb (cfs)
Watershed Characteristics
Subcatchment Area (acres)
Percent Impervious
NRCS Soil Type
Watershed Profile
Overland Slope (ft/ft)
Overland Length (ft)
Channel Slope (ft/ft)
Channel Length (ft)
Minor Storm Rainfall Input
Design Storm Return Period, Tr (years)
One-Hour Precipitation, P1 (inches)
Major Storm Rainfall Input
Design Storm Return Period, Tr (years)
One-Hour Precipitation, P1 (inches)
CALCULATED OUTPUT
Minor Total Design Peak Flow, Q (cfs)
Major Total Design Peak Flow, Q (cfs)
Minor Flow Bypassed Downstream, Qb (cfs)
Major Flow Bypassed Downstream, Qb (cfs)
INLET MANAGEMENT
Curb Inlet 2 User-Defined
STREET
In Sump
CDOT Type R Curb Opening
0.8
2.1
No Bypass Flow Received
0.0
0.0
0.8
2.1
N/A
N/A
Analysis of Trapezoidal Channel (Grass-Lined uses SCS Method)
NRCS Vegetal Retardance (A, B, C, D, or E)A, B, C, D, or E =
Manning's n (Leave cell D16 blank to manually enter an n value)n =0.016
Channel Invert Slope SO =0.0001 ft/ft
Bottom Width B =2.06 ft
Left Side Slope Z1 =50.00 ft/ft
Right Side Sloe Z2 =50.00 ft/ft
Check one of the following soil types:
Soil Type: Max. Velocity (VMAX) Max Froude No. (FMAX)
Non-Cohesive 5.0 fps 0.60
Cohesive 7.0 fps 0.80
Paved N/A N/A
Minor Storm Major Storm
Maximum Allowable Top Width of Channel for Minor & Major Storm TMAX =50.00 50.00 ft
Maximum Allowable Water Depth in Channel for Minor & Major Storm dMAX =0.68 0.68 ft
Allowable Channel Capacity Based On Channel Geometry Minor Storm Major Storm
MINOR STORM Allowable Capacity is based on Top Width Criterion Qallow =4.6 4.6 cfs
MAJOR STORM Allowable Capacity is based on Top Width Criterion dallow =0.48 0.48 ft
Water Depth in Channel Based On Design Peak Flow
Design Peak Flow Qo =0.7 1.8 cfs
Water Depth d =0.23 0.33 ft
Inlet Design Information (Input)
Type of Inlet Inlet Type =
Angle of Inclined Grate (must be <= 30 degrees)θ =0.00 degrees
Width of Grate W =2.06 ft
Length of Grate L =2.06 ft
Open Area Ratio ARATIO =0.66
Height of Inclined Grate HB =0.00 ft
Clogging Factor Cf =0.50
Grate Discharge Coefficient Cd =N/A
Orifice Coefficient Co =0.64
Weir Coefficient Cw =2.05
MINOR MAJOR
Water Depth at Inlet (for depressed inlets, 1 foot is added for depression)d =0.23 0.33
Total Inlet Interception Capacity (assumes clogged condition)Qa =1.3 2.3 cfs
Bypassed Flow Qb =0.0 0.0 cfs
Capture Percentage = Qa/Qo C% =100 100 %
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
User-Defined
MHFD-Inlet, Version 5.03 (August 2023)
AREA INLET IN A SWALE
SECC
ADS Drain 1
This worksheet uses the NRCS vegetal
retardance method to determine
Manning's n for grass-lined channels.
An override Manning's n can be
entered for other channel materials.
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Choose One:
Non-Cohesive
Cohesive
User-Defined
Paved
326034 - Inlet Calculations.xlsm, ADS Drain 1 11/17/2025, 12:42 PM
Analysis of Trapezoidal Channel (Grass-Lined uses SCS Method)
NRCS Vegetal Retardance (A, B, C, D, or E)A, B, C, D, or E =
Manning's n (Leave cell D16 blank to manually enter an n value)n =0.016
Channel Invert Slope SO =0.0001 ft/ft
Bottom Width B =2.06 ft
Left Side Slope Z1 =50.00 ft/ft
Right Side Sloe Z2 =50.00 ft/ft
Check one of the following soil types:
Soil Type: Max. Velocity (VMAX) Max Froude No. (FMAX)
Non-Cohesive 5.0 fps 0.60
Cohesive 7.0 fps 0.80
Paved N/A N/A
Minor Storm Major Storm
Maximum Allowable Top Width of Channel for Minor & Major Storm TMAX =50.00 50.00 ft
Maximum Allowable Water Depth in Channel for Minor & Major Storm dMAX =0.68 0.68 ft
Allowable Channel Capacity Based On Channel Geometry Minor Storm Major Storm
MINOR STORM Allowable Capacity is based on Top Width Criterion Qallow =4.6 4.6 cfs
MAJOR STORM Allowable Capacity is based on Top Width Criterion dallow =0.48 0.48 ft
Water Depth in Channel Based On Design Peak Flow
Design Peak Flow Qo =0.3 0.7 cfs
Water Depth d =0.16 0.23 ft
Inlet Design Information (Input)
Type of Inlet Inlet Type =
Angle of Inclined Grate (must be <= 30 degrees)θ =0.00 degrees
Width of Grate W =2.06 ft
Length of Grate L =2.06 ft
Open Area Ratio ARATIO =0.66
Height of Inclined Grate HB =0.00 ft
Clogging Factor Cf =0.50
Grate Discharge Coefficient Cd =N/A
Orifice Coefficient Co =0.64
Weir Coefficient Cw =2.05
MINOR MAJOR
Water Depth at Inlet (for depressed inlets, 1 foot is added for depression)d =0.16 0.23
Total Inlet Interception Capacity (assumes clogged condition)Qa =0.8 1.4 cfs
Bypassed Flow Qb =0.0 0.0 cfs
Capture Percentage = Qa/Qo C% =100 100 %
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
User-Defined
MHFD-Inlet, Version 5.03 (August 2023)
AREA INLET IN A SWALE
SECC
ADS Drain 2
This worksheet uses the NRCS vegetal
retardance method to determine
Manning's n for grass-lined channels.
An override Manning's n can be
entered for other channel materials.
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Choose One:
Non-Cohesive
Cohesive
User-Defined
Paved
326034 - Inlet Calculations.xlsm, ADS Drain 2 11/17/2025, 12:42 PM
Analysis of Trapezoidal Channel (Grass-Lined uses SCS Method)
NRCS Vegetal Retardance (A, B, C, D, or E)A, B, C, D, or E =
Manning's n (Leave cell D16 blank to manually enter an n value)n =0.016
Channel Invert Slope SO =0.0001 ft/ft
Bottom Width B =2.06 ft
Left Side Slope Z1 =50.00 ft/ft
Right Side Sloe Z2 =50.00 ft/ft
Check one of the following soil types:
Soil Type: Max. Velocity (VMAX) Max Froude No. (FMAX)
Non-Cohesive 5.0 fps 0.60
Cohesive 7.0 fps 0.80
Paved N/A N/A
Minor Storm Major Storm
Maximum Allowable Top Width of Channel for Minor & Major Storm TMAX =50.00 50.00 ft
Maximum Allowable Water Depth in Channel for Minor & Major Storm dMAX =0.95 0.95 ft
Allowable Channel Capacity Based On Channel Geometry Minor Storm Major Storm
MINOR STORM Allowable Capacity is based on Top Width Criterion Qallow =4.6 4.6 cfs
MAJOR STORM Allowable Capacity is based on Top Width Criterion dallow =0.48 0.48 ft
Water Depth in Channel Based On Design Peak Flow
Design Peak Flow Qo =1.0 2.4 cfs
Water Depth d =0.26 0.37 ft
Inlet Design Information (Input)
Type of Inlet Inlet Type =
Angle of Inclined Grate (must be <= 30 degrees)θ =0.00 degrees
Width of Grate W =2.06 ft
Length of Grate L =2.06 ft
Open Area Ratio ARATIO =0.66
Height of Inclined Grate HB =0.00 ft
Clogging Factor Cf =0.50
Grate Discharge Coefficient Cd =N/A
Orifice Coefficient Co =0.64
Weir Coefficient Cw =2.05
MINOR MAJOR
Water Depth at Inlet (for depressed inlets, 1 foot is added for depression)d =0.26 0.37
Total Inlet Interception Capacity (assumes clogged condition)Qa =1.6 2.8 cfs
Bypassed Flow Qb =0.0 0.0 cfs
Capture Percentage = Qa/Qo C% =100 100 %
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
User-Defined
MHFD-Inlet, Version 5.03 (August 2023)
AREA INLET IN A SWALE
SECC
ADS Drain 3
This worksheet uses the NRCS vegetal
retardance method to determine
Manning's n for grass-lined channels.
An override Manning's n can be
entered for other channel materials.
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Choose One:
Non-Cohesive
Cohesive
User-Defined
Paved
326034 - Inlet Calculations.xlsm, ADS Drain 3 11/17/2025, 12:42 PM
Analysis of Trapezoidal Channel (Grass-Lined uses SCS Method)
NRCS Vegetal Retardance (A, B, C, D, or E)A, B, C, D, or E =
Manning's n (Leave cell D16 blank to manually enter an n value)n =0.016
Channel Invert Slope SO =0.0001 ft/ft
Bottom Width B =2.06 ft
Left Side Slope Z1 =50.00 ft/ft
Right Side Sloe Z2 =50.00 ft/ft
Check one of the following soil types:
Soil Type: Max. Velocity (VMAX) Max Froude No. (FMAX)
Non-Cohesive 5.0 fps 0.60
Cohesive 7.0 fps 0.80
Paved N/A N/A
Minor Storm Major Storm
Maximum Allowable Top Width of Channel for Minor & Major Storm TMAX =50.00 50.00 ft
Maximum Allowable Water Depth in Channel for Minor & Major Storm dMAX =1.00 1.00 ft
Allowable Channel Capacity Based On Channel Geometry Minor Storm Major Storm
MINOR STORM Allowable Capacity is based on Top Width Criterion Qallow =4.6 4.6 cfs
MAJOR STORM Allowable Capacity is based on Top Width Criterion dallow =0.48 0.48 ft
Water Depth in Channel Based On Design Peak Flow
Design Peak Flow Qo =0.2 0.4 cfs
Water Depth d =0.12 0.18 ft
Inlet Design Information (Input)
Type of Inlet Inlet Type =
Angle of Inclined Grate (must be <= 30 degrees)θ =0.00 degrees
Width of Grate W =2.06 ft
Length of Grate L =2.06 ft
Open Area Ratio ARATIO =0.66
Height of Inclined Grate HB =0.00 ft
Clogging Factor Cf =0.50
Grate Discharge Coefficient Cd =N/A
Orifice Coefficient Co =0.64
Weir Coefficient Cw =2.05
MINOR MAJOR
Water Depth at Inlet (for depressed inlets, 1 foot is added for depression)d =0.12 0.18
Total Inlet Interception Capacity (assumes clogged condition)Qa =0.5 0.9 cfs
Bypassed Flow Qb =0.0 0.0 cfs
Capture Percentage = Qa/Qo C% =100 100 %
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
User-Defined
MHFD-Inlet, Version 5.03 (August 2023)
AREA INLET IN A SWALE
SECC
ADS Drain 4
This worksheet uses the NRCS vegetal
retardance method to determine
Manning's n for grass-lined channels.
An override Manning's n can be
entered for other channel materials.
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Choose One:
Non-Cohesive
Cohesive
User-Defined
Paved
326034 - Inlet Calculations.xlsm, ADS Drain 4 11/17/2025, 12:43 PM
Analysis of Trapezoidal Channel (Grass-Lined uses SCS Method)
NRCS Vegetal Retardance (A, B, C, D, or E)A, B, C, D, or E =
Manning's n (Leave cell D16 blank to manually enter an n value)n =0.016
Channel Invert Slope SO =0.0001 ft/ft
Bottom Width B =2.06 ft
Left Side Slope Z1 =50.00 ft/ft
Right Side Sloe Z2 =50.00 ft/ft
Check one of the following soil types:
Soil Type: Max. Velocity (VMAX) Max Froude No. (FMAX)
Non-Cohesive 5.0 fps 0.60
Cohesive 7.0 fps 0.80
Paved N/A N/A
Minor Storm Major Storm
Maximum Allowable Top Width of Channel for Minor & Major Storm TMAX =50.00 50.00 ft
Maximum Allowable Water Depth in Channel for Minor & Major Storm dMAX =1.00 1.00 ft
Allowable Channel Capacity Based On Channel Geometry Minor Storm Major Storm
MINOR STORM Allowable Capacity is based on Top Width Criterion Qallow =4.6 4.6 cfs
MAJOR STORM Allowable Capacity is based on Top Width Criterion dallow =0.48 0.48 ft
Water Depth in Channel Based On Design Peak Flow
Design Peak Flow Qo =0.1 0.3 cfs
Water Depth d =0.10 0.15 ft
Inlet Design Information (Input)
Type of Inlet Inlet Type =
Angle of Inclined Grate (must be <= 30 degrees)θ =0.00 degrees
Width of Grate W =2.06 ft
Length of Grate L =2.06 ft
Open Area Ratio ARATIO =0.66
Height of Inclined Grate HB =0.00 ft
Clogging Factor Cf =0.50
Grate Discharge Coefficient Cd =N/A
Orifice Coefficient Co =0.64
Weir Coefficient Cw =2.05
MINOR MAJOR
Water Depth at Inlet (for depressed inlets, 1 foot is added for depression)d =0.10 0.15
Total Inlet Interception Capacity (assumes clogged condition)Qa =0.4 0.7 cfs
Bypassed Flow Qb =0.0 0.0 cfs
Capture Percentage = Qa/Qo C% =100 100 %
Major storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
User-Defined
MHFD-Inlet, Version 5.03 (August 2023)
AREA INLET IN A SWALE
SECC
ADS Drain 5
This worksheet uses the NRCS vegetal
retardance method to determine
Manning's n for grass-lined channels.
An override Manning's n can be
entered for other channel materials.
Minor storm max. allowable capacity GOOD - greater than the design flow given on sheet 'Inlet Management'
Choose One:
Non-Cohesive
Cohesive
User-Defined
Paved
326034 - Inlet Calculations.xlsm, ADS Drain 5 11/17/2025, 12:43 PM
Project:
Inlet ID:
Gutter Geometry:
Maximum Allowable Width for Spread Behind Curb TBACK =0.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.013
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =31.0 ft
Gutter Width W =1.00 ft
Street Transverse Slope SX =0.023 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.013
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =12.0 18.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 12.0 inches
Check boxes are not applicable in SUMP conditions
MINOR STORM Allowable Capacity is not applicable to Sump Condition Minor Storm Major Storm
MAJOR STORM Allowable Capacity is not applicable to Sump Condition Qallow =SUMP SUMP cfs
MHFD-Inlet, Version 5.03 (August 2023)
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
SECC
Curb Inlet 1
326034 - Inlet Calculations.xlsm, Curb Inlet 1 11/17/2025, 12:44 PM
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from above)alocal =3.00 3.00 inches
Number of Unit Inlets (Grate or Curb Opening)No =1 1
Water Depth at Flowline (outside of local depression)Ponding Depth =4.0 5.7 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) =N/A N/A feet
Width of a Unit Grate Wo =N/A N/A feet
Open Area Ratio for a Grate (typical values 0.15-0.90)Aratio =N/A N/A
Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =N/A N/A
Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =N/A N/A
Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =N/A N/A
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) =5.00 5.00 feet
Height of Vertical Curb Opening in Inches Hvert =6.00 6.00 inches
Height of Curb Orifice Throat in Inches Hthroat =6.00 6.00 inches
Angle of Throat Theta =63.40 63.40 degrees
Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =1.00 1.00 feet
Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =0.10 0.10
Curb Opening Weir Coefficient (typical value 2.3-3.7)Cw (C) =3.60 3.60
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =0.67 0.67
Low Head Performance Reduction (Calculated)MINOR MAJOR
Depth for Grate Midwidth dGrate =N/A N/A ft
Depth for Curb Opening Weir Equation dCurb =0.25 0.39 ft
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate =N/A N/A
Curb Opening Performance Reduction Factor for Long Inlets RFCurb =1.00 1.00
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination =N/A N/A
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition)Qa =2.8 5.4 cfs
WARNING: Inlet Capacity < Q Peak for Major Storm Q PEAK REQUIRED =2.2 5.5 cfs
INLET IN A SUMP OR SAG LOCATION
MHFD-Inlet, Version 5.03 (August 2023)
CDOT Type R Curb Opening
H-VertH-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT Type R Curb Opening
Override Depths
326034 - Inlet Calculations.xlsm, Curb Inlet 1 11/17/2025, 12:44 PM
Project:
Inlet ID:
Gutter Geometry:
Maximum Allowable Width for Spread Behind Curb TBACK =0.0 ft
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)SBACK =ft/ft
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)nBACK =0.013
Height of Curb at Gutter Flow Line HCURB =6.00 inches
Distance from Curb Face to Street Crown TCROWN =24.0 ft
Gutter Width W =1.00 ft
Street Transverse Slope SX =0.030 ft/ft
Gutter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)SW =0.083 ft/ft
Street Longitudinal Slope - Enter 0 for sump condition SO =0.000 ft/ft
Manning's Roughness for Street Section (typically between 0.012 and 0.020)nSTREET =0.013
Minor Storm Major Storm
Max. Allowable Spread for Minor & Major Storm TMAX =12.0 18.0 ft
Max. Allowable Depth at Gutter Flowline for Minor & Major Storm dMAX =6.0 12.0 inches
Check boxes are not applicable in SUMP conditions
MINOR STORM Allowable Capacity is not applicable to Sump Condition Minor Storm Major Storm
MAJOR STORM Allowable Capacity is not applicable to Sump Condition Qallow =SUMP SUMP cfs
MHFD-Inlet, Version 5.03 (August 2023)
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
SECC
Curb Inlet 2
326034 - Inlet Calculations.xlsm, Curb Inlet 2 11/17/2025, 12:44 PM
Design Information (Input)MINOR MAJOR
Type of Inlet Type =
Local Depression (additional to continuous gutter depression 'a' from above)alocal =3.00 3.00 inches
Number of Unit Inlets (Grate or Curb Opening)No =1 1
Water Depth at Flowline (outside of local depression)Ponding Depth =5.0 7.1 inches
Grate Information MINOR MAJOR
Length of a Unit Grate Lo (G) =N/A N/A feet
Width of a Unit Grate Wo =N/A N/A feet
Open Area Ratio for a Grate (typical values 0.15-0.90)Aratio =N/A N/A
Clogging Factor for a Single Grate (typical value 0.50 - 0.70)Cf (G) =N/A N/A
Grate Weir Coefficient (typical value 2.15 - 3.60)Cw (G) =N/A N/A
Grate Orifice Coefficient (typical value 0.60 - 0.80)Co (G) =N/A N/A
Curb Opening Information MINOR MAJOR
Length of a Unit Curb Opening Lo (C) =5.00 5.00 feet
Height of Vertical Curb Opening in Inches Hvert =6.00 6.00 inches
Height of Curb Orifice Throat in Inches Hthroat =6.00 6.00 inches
Angle of Throat Theta =63.40 63.40 degrees
Side Width for Depression Pan (typically the gutter width of 2 feet)Wp =1.00 1.00 feet
Clogging Factor for a Single Curb Opening (typical value 0.10)Cf (C) =0.10 0.10
Curb Opening Weir Coefficient (typical value 2.3-3.7)Cw (C) =3.60 3.60
Curb Opening Orifice Coefficient (typical value 0.60 - 0.70)Co (C) =0.67 0.67
Low Head Performance Reduction (Calculated)MINOR MAJOR
Depth for Grate Midwidth dGrate =N/A N/A ft
Depth for Curb Opening Weir Equation dCurb =0.33 0.51 ft
Grated Inlet Performance Reduction Factor for Long Inlets RFGrate =N/A N/A
Curb Opening Performance Reduction Factor for Long Inlets RFCurb =1.00 1.00
Combination Inlet Performance Reduction Factor for Long Inlets RFCombination =N/A N/A
MINOR MAJOR
Total Inlet Interception Capacity (assumes clogged condition)Qa =4.2 8.0 cfs
Inlet Capacity IS GOOD for Minor and Major Storms (>Q Peak)Q PEAK REQUIRED =0.8 2.1 cfs
INLET IN A SUMP OR SAG LOCATION
MHFD-Inlet, Version 5.03 (August 2023)
CDOT Type R Curb Opening
H-VertH-Curb
W
Lo (C)
Lo (G)
Wo
WP
CDOT Type R Curb Opening
Override Depths
326034 - Inlet Calculations.xlsm, Curb Inlet 2 11/17/2025, 12:44 PM
Program:
UDSEWER Math Model
Interface 2.1.1.4
Run Date:
11/17/2025 11:42:11 AM
UDSewer Results Summary
Project Title: New UDSEWER System Module
Project Description: Default system
System Input Summary
Rainfall Parameters
Rainfall Return Period: 100
Rainfall Calculation Method: Formula
One Hour Depth (in): 3.67
Rainfall Constant "A": 28.5
Rainfall Constant "B": 10
Rainfall Constant "C": 0.786
Rational Method Constraints
Minimum Urban Runoff Coeff.: 0.20
Maximum Rural Overland Len. (ft): 500
Maximum Urban Overland Len. (ft): 300
Used UDFCD Tc. Maximum: Yes
Sizer Constraints
Minimum Sewer Size (in): 8.00
Maximum Depth to Rise Ratio: 0.90
Maximum Flow Velocity (fps): 18.0
Minimum Flow Velocity (fps): 0.0
Backwater Calculations:
Tailwater Elevation (ft): 4916.18
Manhole Input Summary:
Given Flow Sub Basin Information
Element
Name
Ground
Elevation
(ft)
Total
Known
Flow (cfs)
Local
Contribution
(cfs)
Drainage
Area
(Ac.)
Runoff
Coefficient
5yr
Coefficient
Overland
Length
(ft)
Overland
Slope
(%)
Gutter
Length
(ft)
Gutter
Velocity
(fps)
FES 4911.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
ADS DB SL 1 4917.70 39.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
ADS DB SL 2 4918.36 39.11 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
ADS DB SL 3 4918.97 35.62 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
CURB INLET 1 4919.96 17.74 5.52 0.76 0.70 0.70 180.00 1.80 0.00 1.79
ADS DB GL 1 4921.25 12.22 1.80 0.70 0.29 0.29 305.00 0.80 0.00 1.79
ADS DB SL 8 4924.19 10.42 6.86 0.69 0.95 0.95 170.00 1.00 0.00 2.00
ADS DB GL 2 4921.25 3.57 0.74 0.23 0.32 0.32 80.00 3.00 0.00 2.00
ADS DB GL 3 4920.50 2.82 2.44 0.59 0.45 0.45 145.00 1.80 0.00 2.00
11/17/25, 11:47 AM UDSEWER Math Model Interface Results: New UDSEWER System Module 11/17/2025 11:42
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ADS DB GL 4 4919.91 0.39 0.39 0.13 0.30 0.30 80.00 1.60 0.00 2.00
ADS DB SL 4 4921.20 17.89 0.00 0.00 0.95 0.95 100.00 0.40 0.00 0.00
ADS DB SL 5 4921.28 17.89 4.72 0.13 0.95 0.95 170.00 0.20 70.00 3.63
ADS DB SL 6 4921.34 13.16 5.56 0.56 0.95 0.95 175.00 1.00 0.00 0.00
ADS DB SL 7 4920.75 7.61 4.03 0.41 0.95 0.95 165.00 1.00 0.00 0.00
ADS DB GL 5 4920.50 1.46 1.46 0.24 0.66 0.66 70.00 1.90 0.00 2.00
CURB INLET 2 4920.20 2.12 2.12 0.27 0.72 0.72 100.00 1.00 40.00 2.00
FES IN 4917.65 3.49 3.49 0.54 0.67 0.67 240.00 2.00 100.00 1.55
Manhole Output Summary:
Local Contribution Total Design Flow
Element
Name
Overland
Time
(min)
Gutter
Time
(min)
Basin Tc
(min)
Intensity
(in/hr)
Local
Contrib
(cfs)
Coeff.
Area
Intensity
(in/hr)
Manhole Tc
(min)
Peak
Flow
(cfs)
Comment
FES 0.00 0.00 0.00 0.00 0.00 3.53 11.08 7.38 39.11 Surface Water Present (Upstream)
ADS DB SL 1 0.00 0.00 0.00 0.00 0.00 3.53 11.08 7.38 39.11 Surface Water Present (Downstream)
ADS DB SL 2 0.00 0.00 0.00 0.00 0.00 3.53 11.08 7.38 39.11
ADS DB SL 3 0.00 0.00 0.00 0.00 0.00 3.17 11.25 7.06 35.62
CURB INLET 1 0.00 0.00 8.91 10.38 5.52 1.77 10.03 9.74 17.74 Used Minimum Tc
ADS DB GL 1 0.00 0.00 13.10 8.87 1.80 1.24 9.88 10.12 12.22 Used Minimum Tc
ADS DB SL 8 0.00 0.00 8.71 10.47 6.86 1.03 10.08 9.62 10.42 Used Minimum Tc
ADS DB GL 2 0.00 0.00 9.68 10.05 0.74 0.38 9.44 11.32 3.57 Used Minimum Tc
ADS DB GL 3 0.00 0.00 12.07 9.19 2.44 0.30 9.26 11.85 2.82 Used Minimum Tc
ADS DB GL 4 0.00 0.00 9.82 10.00 0.39 0.04 10.00 9.82 0.39 Used Minimum Tc
ADS DB SL 4 0.00 0.00 0.00 0.00 0.00 1.40 12.80 4.48 17.89
ADS DB SL 5 0.00 0.00 5.00 38.22 4.72 1.40 12.80 4.48 17.89 Used Minimum Tc
ADS DB SL 6 0.00 0.00 8.74 10.45 5.56 1.27 10.33 9.02 13.16 Used Minimum Tc
ADS DB SL 7 0.00 0.00 8.98 10.35 4.03 0.74 10.25 9.20 7.61 Used Minimum Tc
ADS DB GL 5 0.00 0.00 11.99 9.22 1.46 0.16 9.22 11.99 1.46 Used Minimum Tc
CURB INLET 2 0.00 0.00 7.75 10.91 2.12 0.19 10.91 7.75 2.12 Used Minimum Tc
FES IN 0.00 0.00 10.75 9.65 3.49 0.36 9.65 10.75 3.49 Surface Water Present (Upstream)
Used Minimum Tc
Sewer Input Summary:
Elevation Loss Coefficients Given Dimensions
Element
Name
Sewer
Length
(ft)
Downstream
Invert
(ft)
Slope
(%)
Upstream
Invert
(ft)
Mannings
n
Bend
Loss
Lateral
Loss
Cross
Section
Rise
(ft or in)
Span
(ft or in)
ADS DB SL 1 113.50 4911.01 0.4 4911.46 0.016 0.03 0.00 CIRCULAR 42.00 in 42.00 in
ADS DB SL 2 103.70 4911.48 0.4 4911.89 0.016 0.05 0.00 CIRCULAR 42.00 in 42.00 in
ADS DB SL 3 105.90 4911.91 0.4 4912.33 0.016 0.05 0.00 CIRCULAR 42.00 in 42.00 in
CURB INLET 1 62.50 4912.35 0.4 4912.60 0.016 0.05 0.00 CIRCULAR 30.00 in 30.00 in
ADS DB GL 1 195.00 4912.62 0.4 4913.40 0.016 0.05 0.00 CIRCULAR 27.00 in 27.00 in
ADS DB SL 8 304.60 4913.41 0.4 4914.63 0.016 0.05 0.00 CIRCULAR 24.00 in 24.00 in
ADS DB GL 2 63.00 4914.65 0.4 4914.90 0.016 0.05 0.00 CIRCULAR 18.00 in 18.00 in
ADS DB GL 3 103.80 4914.91 0.4 4915.33 0.016 0.05 0.00 CIRCULAR 15.00 in 15.00 in
ADS DB GL 4 140.30 4915.35 0.4 4915.91 0.016 0.05 0.00 CIRCULAR 12.00 in 12.00 in
ADS DB SL 4 97.30 4912.35 0.4 4912.74 0.016 0.05 0.00 CIRCULAR 30.00 in 30.00 in
ADS DB SL 5 132.60 4912.76 0.4 4913.29 0.016 0.05 0.00 CIRCULAR 30.00 in 30.00 in
11/17/25, 11:47 AM UDSEWER Math Model Interface Results: New UDSEWER System Module 11/17/2025 11:42
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ADS DB SL 6 84.50 4913.30 0.4 4913.64 0.016 0.05 0.00 CIRCULAR 27.00 in 27.00 in
ADS DB SL 7 68.90 4913.65 0.4 4913.93 0.016 0.05 0.00 CIRCULAR 21.00 in 21.00 in
ADS DB GL 5 97.10 4913.97 1.0 4914.94 0.016 0.05 0.00 CIRCULAR 12.00 in 12.00 in
CURB INLET 2 91.90 4913.94 0.4 4914.31 0.016 0.05 0.00 CIRCULAR 15.00 in 15.00 in
FES IN 120.20 4911.88 4.8 4917.65 0.016 0.05 0.00 CIRCULAR 12.00 in 12.00 in
Sewer Flow Summary:
Full Flow Capacity Critical Flow Normal Flow
Element
Name
Flow
(cfs)
Velocity
(fps)
Depth
(in)
Velocity
(fps)
Depth
(in)
Velocity
(fps)
Froude
Number
Flow
Condition
Flow
(cfs)
Surcharged
Length
(ft)
Comment
ADS DB SL 1 51.84 5.39 23.33 7.13 27.25 5.92 0.74 Pressurized 39.11 113.50
ADS DB SL 2 51.84 5.39 23.33 7.13 27.25 5.92 0.74 Pressurized 39.11 103.70
ADS DB SL 3 51.84 5.39 22.21 6.90 25.58 5.81 0.76 Pressurized 35.62 105.90
CURB INLET 1 21.13 4.31 17.11 6.13 21.04 4.82 0.67 Pressurized 17.74 62.50
ADS DB GL 1 15.96 4.01 14.54 5.60 17.70 4.42 0.69 Pressurized 12.22 195.00
ADS DB SL 8 11.66 3.71 13.87 5.54 17.70 4.20 0.62 Pressurized 10.42 304.60
ADS DB GL 2 5.41 3.06 8.65 4.25 10.67 3.27 0.67 Pressurized 3.57 63.00
ADS DB GL 3 3.33 2.71 8.09 4.18 10.60 3.04 0.59 Pressurized 2.82 103.80
ADS DB GL 4 1.84 2.34 3.10 2.43 3.76 1.86 0.69 Pressurized 0.39 140.30
ADS DB SL 4 21.13 4.31 17.18 6.15 21.18 4.83 0.67 Pressurized 17.89 97.30
ADS DB SL 5 21.13 4.31 17.18 6.15 21.18 4.83 0.67 Pressurized 17.89 132.60
ADS DB SL 6 15.96 4.01 15.12 5.75 18.68 4.48 0.66 Pressurized 13.16 84.50
ADS DB SL 7 8.16 3.39 12.26 5.22 16.06 3.86 0.59 Pressurized 7.61 68.90
ADS DB GL 5 2.90 3.70 6.14 3.61 6.02 3.70 1.04 Pressurized 1.46 97.10
CURB INLET 2 3.33 2.71 6.97 3.80 8.70 2.87 0.66 Pressurized 2.12 91.90
FES IN 6.36 8.10 9.58 5.19 6.34 8.28 2.25 Supercritical
Jump 3.49 113.95
A Froude number of 0 indicates that pressured flow occurs (adverse slope or undersized pipe).
If the sewer is not pressurized, full flow represents the maximum gravity flow in the sewer.
If the sewer is pressurized, full flow represents the pressurized flow conditions.
Sewer Sizing Summary:
Existing Calculated Used
Element
Name
Peak
Flow
(cfs)
Cross
Section Rise Span Rise Span Rise Span Area
(ft^2)Comment
ADS DB SL 1 39.11 CIRCULAR 42.00 in 42.00 in 42.00 in 42.00 in 42.00 in 42.00 in 9.62
ADS DB SL 2 39.11 CIRCULAR 42.00 in 42.00 in 42.00 in 42.00 in 42.00 in 42.00 in 9.62
ADS DB SL 3 35.62 CIRCULAR 42.00 in 42.00 in 42.00 in 42.00 in 42.00 in 42.00 in 9.62
CURB INLET 1 17.74 CIRCULAR 30.00 in 30.00 in 30.00 in 30.00 in 30.00 in 30.00 in 4.91
ADS DB GL 1 12.22 CIRCULAR 27.00 in 27.00 in 27.00 in 27.00 in 27.00 in 27.00 in 3.98
ADS DB SL 8 10.42 CIRCULAR 24.00 in 24.00 in 24.00 in 24.00 in 24.00 in 24.00 in 3.14
ADS DB GL 2 3.57 CIRCULAR 18.00 in 18.00 in 18.00 in 18.00 in 18.00 in 18.00 in 1.77
ADS DB GL 3 2.82 CIRCULAR 15.00 in 15.00 in 15.00 in 15.00 in 15.00 in 15.00 in 1.23
ADS DB GL 4 0.39 CIRCULAR 12.00 in 12.00 in 9.00 in 9.00 in 12.00 in 12.00 in 0.79
ADS DB SL 4 17.89 CIRCULAR 30.00 in 30.00 in 30.00 in 30.00 in 30.00 in 30.00 in 4.91
ADS DB SL 5 17.89 CIRCULAR 30.00 in 30.00 in 30.00 in 30.00 in 30.00 in 30.00 in 4.91
ADS DB SL 6 13.16 CIRCULAR 27.00 in 27.00 in 27.00 in 27.00 in 27.00 in 27.00 in 3.98
11/17/25, 11:47 AM UDSEWER Math Model Interface Results: New UDSEWER System Module 11/17/2025 11:42
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ADS DB SL 7 7.61 CIRCULAR 21.00 in 21.00 in 21.00 in 21.00 in 21.00 in 21.00 in 2.41
ADS DB GL 5 1.46 CIRCULAR 12.00 in 12.00 in 12.00 in 12.00 in 12.00 in 12.00 in 0.79
CURB INLET 2 2.12 CIRCULAR 15.00 in 15.00 in 15.00 in 15.00 in 15.00 in 15.00 in 1.23
FES IN 3.49 CIRCULAR 12.00 in 12.00 in 12.00 in 12.00 in 12.00 in 12.00 in 0.79
Calculated diameter was determined by sewer hydraulic capacity rounded up to the nearest commercially available size.
Sewer sizes should not decrease downstream.
All hydraulics where calculated using the 'Used' parameters.
Grade Line Summary:
Tailwater Elevation (ft): 4916.18
Invert Elev.Downstream Manhole
Losses HGL EGL
Element
Name
Downstream
(ft)
Upstream
(ft)
Bend
Loss
(ft)
Lateral
Loss
(ft)
Downstream
(ft)
Upstream
(ft)
Downstream
(ft)
Friction
Loss
(ft)
Upstream
(ft)
ADS DB SL 1 4911.01 4911.46 0.00 0.00 4916.18 4916.44 4916.44 0.26 4916.70
ADS DB SL 2 4911.48 4911.89 0.01 0.00 4916.45 4916.69 4916.71 0.24 4916.94
ADS DB SL 3 4911.91 4912.33 0.01 0.00 4916.74 4916.94 4916.95 0.20 4917.15
CURB INLET 1 4912.35 4912.60 0.01 0.00 4916.96 4917.14 4917.16 0.18 4917.34
ADS DB GL 1 4912.62 4913.40 0.01 0.00 4917.20 4917.66 4917.35 0.46 4917.81
ADS DB SL 8 4913.41 4914.63 0.01 0.00 4917.67 4918.64 4917.84 0.97 4918.81
ADS DB GL 2 4914.65 4914.90 0.00 0.00 4918.75 4918.86 4918.82 0.11 4918.92
ADS DB GL 3 4914.91 4915.33 0.00 0.00 4918.87 4919.16 4918.95 0.30 4919.25
ADS DB GL 4 4915.35 4915.91 0.00 0.00 4919.24 4919.27 4919.25 0.03 4919.27
ADS DB SL 4 4912.35 4912.74 0.01 0.00 4916.96 4917.24 4917.16 0.28 4917.44
ADS DB SL 5 4912.76 4913.29 0.01 0.00 4917.25 4917.63 4917.45 0.38 4917.83
ADS DB SL 6 4913.30 4913.64 0.01 0.00 4917.67 4917.90 4917.84 0.23 4918.07
ADS DB SL 7 4913.65 4913.93 0.01 0.00 4917.92 4918.16 4918.08 0.24 4918.32
ADS DB GL 5 4913.97 4914.94 0.00 0.00 4918.27 4918.51 4918.32 0.25 4918.57
CURB INLET 2 4913.94 4914.31 0.00 0.00 4918.28 4918.42 4918.32 0.15 4918.47
FES IN 4911.88 4917.65 0.02 0.00 4916.70 4918.45 4917.01 1.86 4918.87
Bend and Lateral losses only apply when there is an outgoing sewer. The system outfall, sewer #0, is not considered a sewer.
Bend loss = Bend K * V_fi ^ 2/(2*g)
Lateral loss = V_fo ^ 2/(2*g)- Junction Loss K * V_fi ^ 2/(2*g).
Friction loss is always Upstream EGL - Downstream EGL.
Excavation Estimate:
The trench side slope is 1.0 ft/ft
The minimum trench width is 2.00 ft
Downstream Upstream
Element
Name
Length
(ft)
Wall
(in)
Bedding
(in)
Bottom
Width
(ft)
Top
Width
(ft)
Trench
Depth
(ft)
Cover
(ft)
Top
Width
(ft)
Trench
Depth
(ft)
Cover
(ft)
Volume
(cu. yd)Comment
ADS DB SL 1 113.50 4.50 6.00 7.25 0.00 0.87 0.00 9.98 7.12 2.37 125.58 Sewer Too Shallow
ADS DB SL 2 103.70 4.50 6.00 7.25 9.95 7.10 2.35 10.44 7.35 2.60 209.49
ADS DB SL 3 105.90 4.50 6.00 7.25 10.41 7.33 2.58 10.78 7.52 2.77 222.04
CURB INLET 1 62.50 3.50 6.00 6.08 11.74 7.41 3.83 13.22 8.15 4.57 133.58
ADS DB GL 1 195.00 3.25 6.00 5.79 13.43 8.11 4.82 14.45 8.62 5.33 470.28
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ADS DB SL 8 304.60 3.00 4.00 5.50 14.68 8.42 5.59 18.12 10.14 7.31 919.31
ADS DB GL 2 63.00 2.50 4.00 4.92 18.58 10.08 7.83 12.20 6.89 4.64 167.33
ADS DB GL 3 103.80 2.25 4.00 4.63 12.42 6.86 4.90 10.09 5.69 3.73 155.10
ADS DB GL 4 140.30 2.00 4.00 4.33 10.30 5.65 3.98 8.00 4.50 2.83 146.16
ADS DB SL 4 97.30 3.50 6.00 6.08 11.74 7.41 3.83 15.42 9.25 5.67 236.32
ADS DB SL 5 132.60 3.50 6.00 6.08 15.38 9.23 5.65 14.48 8.78 5.20 365.44
ADS DB SL 6 84.50 3.25 6.00 5.79 14.71 8.75 5.46 14.15 8.47 5.18 214.48
ADS DB SL 7 68.90 2.75 4.00 5.21 14.62 8.25 5.71 12.89 7.38 4.84 150.96
ADS DB GL 5 97.10 2.00 4.00 4.33 13.56 7.28 5.61 11.12 6.06 4.39 162.94
CURB INLET 2 91.90 2.25 4.00 4.63 13.37 7.33 5.37 11.53 6.41 4.45 160.93
FES IN 120.20 2.00 4.00 4.33 12.96 6.98 5.31 4.33 0.50 0.00 113.55 Sewer Too Shallow
Total earth volume for sewer trenches = 3953 cubic yards.
The trench was estimated to have a bottom width equal to the outer pipe diameter plus 36 inches.
If the calculated width of the trench bottom is less than the minimum acceptable width, the minimum acceptable width was used.
The sewer wall thickness is equal to: (equivalent diameter in inches/12)+1 inches
The sewer bedding thickness is equal to:
Four inches for pipes less than 33 inches.
Six inches for pipes less than 60 inches.
Eight inches for all larger sizes.
11/17/25, 11:47 AM UDSEWER Math Model Interface Results: New UDSEWER System Module 11/17/2025 11:42
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