HomeMy WebLinkAboutAFFORDABLE SELF STORAGE - PDP - PDP170005 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTFINAL DRAINAGE AND EROSION
CONTROL REPORT
FOR
AFFORDABLE STORAGE
(LOT 9, BLOCK 4,
EVERGREEN REPLAT 1)
FINAL DRAINAGE AND EROSION
CONTROL REPORT
FOR
AFFORDABLE STORAGE
(LOT 9, BLOCK 4,
EVERGREEN REPLAT 1)
Prepared for:
Affordable Storage
Prepared by:
North Star Design
700 Automation Drive, Unit I
Windsor, Colorado 80550
(970) 686-6939
January 24, 2017
Job Number 177-10
ii
January 24, 2017
Shane Boyle
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 80522-0580
RE: Final Drainage and Erosion Control Report for Affordable Storage
Dear Shane,
I am pleased to submit for your review and approval, this Final Drainage and Erosion Control
Report for Affordable Storage (Lot 9, Block 4, Evergreen Replat 1). I certify that this report for
the drainage design was prepared in accordance with the criteria in the City of Fort Collins
Storm Drainage Manual.
I appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
Sincerely,
Patricia Kroetch, P.E.
700 Automation Drive, Unit I
Windsor, CO 80550
Phone: 970-686-6939
Fax: 970-686-1188
iii
TABLE OF CONTENTS
TABLE OF CONTENTS ............................................................................................................... iii
1. GENERAL LOCATION AND DESCRIPTION
1.1 Location ...................................................................................................................1
1.2 Description of Property ............................................................................................1
2. DRAINAGE BASINS AND SUB-BASINS
2.1 Major Basin Description ..........................................................................................1
2.2 Sub-Basin Description .............................................................................................2
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations ..............................................................................................................2
3.2 Development Criteria Reference and Constraints ...................................................2
3.3 Hydrologic Criteria ..................................................................................................2
3.4 Hydraulic Criteria ....................................................................................................3
4. DRAINAGE FACILITY DESIGN
4.1 General Concept ......................................................................................................3
4.2 Specific Flow Routing .............................................................................................3
4.3 Drainage Summary ..................................................................................................5
5. STORMWATER MANAGEMENT CONTROLS
5.1 Written Analysis .....................................................................................................5
5.2 SWMP Contact Information ...................................................................................6
5.3 Identification and location of all potential pollution sources ..................................7
5.4 Best Management Practices (BMP’s) for Stormwater Pollution Prevention ...........7
5.5 BMP Implementation ...............................................................................................9
6. CONCLUSIONS
6.1 Compliance with Standards ..................................................................................12
6.2 Drainage Concept ..................................................................................................12
7. REFERENCES ..................................................................................................................13
APPENDICES
A Vicinity Map
B Hydrologic Computations
C Hydraulic & BMP Sizing Calculations
D Detention Pond Sizing Calculations
E BMP Schedule and Cost Estimate
F Figures and Tables
1
1. GENERAL LOCATION AND DESCRIPTION
1.1 Location
This site is located on the north side of Conifer Street, east of Red Cedar Circle in the
Northwest Quarter of Section 1, Township 7 North, Range 69 West of the Sixth Principal
Meridian, in the City of Fort Collins, Larimer County, Colorado. See the Vicinity Map
in Appendix A of this report.
This project is bounded on the north and east by existing developed sites, on the west by
existing Red Cedar Circle and on the south by existing Conifer Street.
1.2 Description of Property
The entire project consists of approximately 3.2 acres. The site is currently undeveloped,
with areas of existing volunteer weeds and grasses. It appears that the north portion of
the site was previously used for vehicle parking and storage for the adjacent lot. A
detention pond exists on this portion of the site and with this development, the outlet
structure and pipe will be removed. The site currently drains south into the adjacent
street after attenuation in the detention pond.
Proposed development on-site will include six storage buildings, private drives between
the buildings, a parking area and sidewalks. Existing drainage patterns will be altered to
route flow to a proposed detention pond in the southeast corner of the site which will
release into the existing storm system near this location.
2. DRAINAGE BASINS AND SUB-BASINS
2.1 Major Basin Description
The proposed development lies within the Dry Creek Drainage Basin. Stormwater
detention is required for this basin but water quality extended detention is not required
because it is provided in the North East College Corridor Outfall (NECCO) detention
pond. The City requirement for stormwater detention in the Dry Creek basin is a single-
stage detention with a 100-year release rate of 0.2 cfs per acre.
2
2.2 Sub-basin Description
Runoff from this site currently flows to the existing street. From there, the runoff flow
east on Conifer to an existing inlet near the intersection of Blue Spruce Drive and
Conifer. With the proposed drainage concept for this site, the runoff from the site will
flow to a proposed on site detention pond and be released at the rate of 0.2 cfs per acre
into the storm system in Conifer.
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations
This report was prepared to meet or exceed the “City of Fort Collins Storm Drainage
Design Criteria Manual” specifications except where variances are requested as noted in
Section 4.2 of this report. Where applicable, the criteria established in the “Urban Storm
Drainage Criteria Manual” (UDFCD), 2001, developed by the Denver Regional Council
of Governments, has been used.
3.2 Development Criteria Reference and Constraints
The runoff from this site has been routed to conform to the requirements of the Dry
Creek Drainage Basin and the City of Fort Collins Stormwater Department. Both
stormwater runoff detention and water quality extended detention are required for this
site with on-site detention and offsite water quality. The release rate from the site will be
0.2 cfs per acre.
3.3 Hydrologic Criteria
Runoff computations were prepared for the 10-year minor and 100-year major storm
frequencies utilizing the rational method. All hydrologic calculations associated with the
basins are included in Appendix B of this report. Standard Form 8 (SF-8) provides time
of concentration calculations for all sub-basins.
Detention volume was calculated using the predetermined release rate of 0.2 cfs per acre.
The FAA method for detention pond sizing was utilized to determine the required
volume. Refer to the detention calculations included in Appendix C of this report.
3
3.4 Hydraulic Criteria
Hydraulic elements have been designed per City of Fort Collins standards to adequately
convey the 100-year storm runoff from this site to the proposed detention pond. A
proposed 12” storm pipe will convey the detained runoff from the site to a new manhole
located on the existing 24”storm pipe in Conifer Street.
4. DRAINAGE FACILITY DESIGN
4.1 General Concept
The runoff from this site will flow primarily west to east in the drive aisle to the main
drive aisle where it will be directed south into the detention pond. The runoff from the
site will either flow on the surface or enter a storm pipe via an inlet. On-site runoff will
also be conveyed to the detention pond via flows in LID swales along the south property
boundary to an area inlet and storm pipe. The detained runoff will discharge into the
existing storm pipe located in Conifer Street.
4.2 Specific Flow Routing
With this design, the site has been broken into 7 basins which described in the following
paragraphs.
Basin 1 is located in the northmost portion of the site. This Basin contains the northmost
private drive, a portion of Building E, the east leg of Building D and the north half of
Building C. The runoff from this basin will flow east in a concrete pan will be collected
in an area inlet. The storm pipe then conveys the flows to the south into the detention
pond.
Basin 2 is located in the central portion of the site. This Basin contains the middle drive
aisle, a portion of Building E, the south half of Building C, the north half of building B
and a portion of the south leg of Building D. The runoff from this basin will flow east in
a concrete pan to the north-south drive aisle. The flow will be combined with the runoff
from Basin 3 and then be directed south and into Rain Garden #1. The flow will then
enter the detention pond.
4
Basin 3 is located in the central portion of the site. This Basin contains the southmost
drive aisle, a portion of Building E, the south half of Building B and the west half of
Building F. The runoff from this basin will flow east in a concrete pan to the north-south
drive aisle. The flow will be combined with the runoff from Basin 2 and then be directed
south and into Rain Garden #1. The flow will then enter the detention pond.
Basin 4 is located in the southern portion of the site. This Basin contains Building A and
a landscape area south of Building A. The roof of Building A is sloped to drain to the
south where the runoff will enter a Grassed Swale/Bioswale in the landscape area. The
flow will then be directed east where it will enter an area inlet and be directed to the
detention pond.
Basin 5 is located in the east portion of the site. This Basin contains the east drive aisle,
the east half of Building E, a small portion of Building D, the trash enclosure and the east
half of Building F. The runoff from this basin will flow south in a concrete curb to a curb
opening. The flow will then be directed south and into Rain Garden #2. The flow will
then enter the detention pond.
Basin 6 is located in the southeast portion of the site and contains the detention pond
(landscape area). The the bottom of the detention area is sloped to drain southeast. This
basin accepts runoff from Basins 1, 2, 3, 4 and 5. The detained runoff will enter the
existing storm system via a new storm pipe with an orifice to restrict flows to 0.2cfs per
acre.
Basin 7 is the site area that drains to the street undetained. A majority of the area that is
draining to the street is a narrow landscape strip located along the perimeter of the site.
The impervious area is a portion of the drive entry that drains to Red Cedar and a portion
of the drive entry that drains to Conifer Street.
Drainage design for this site has been designed to convey on-site runoff to the proposed
detention pond and incorporate the required LID enhancement features. On-site runoff
will be conveyed to the detention pond via surface flow in the drive aisles, in the LID
swale and subsurface in the perforated pipes. The detention pond will release the
detained runoff from the site at the rate of 0.2 cfs per acre.
4.3 Drainage Summary
5
This site has been designed to meet or exceed the “City of Fort Collins Storm Drainage
Design Criteria Manual” specifications. The proposed drainage design for this site has
been designed to convey on-site runoff to the detention pond while minimizing future
maintenance. The site incorporates LID (Low Impact Development) treatment areas
including an LID swale with underdrain along the south property line and two rain
garden areas at the edge of the detention area. Refer to the end of Appendix E for a table
indicating the size of each LID treatment area and the area of the site that drains to each
LID treatment area.
All drainage facilities proposed with this project, including the detention pond, LID
features, area inlets, storm pipe and outlet structure are private and will be owned and
maintained by the property owner.
5. STORMWATER MANAGEMENT CONTROLS
5.1 Written Analysis
The soils on this site are classified by the USGS Soil Survey as Nunn Clay Loam and are
classified in the hydrologic group C. The soils are described as having a slow runoff rate
and the hazard of water erosion is moderate and the hazard of wind erosion is moderate.
The site is surrounded by developed sites including streets and paved areas. The
construction shall utilize silt fence around the perimeter to control sediment transport
from rainfall and from wind. The silt fence that is located in the proposed pavement areas
will be removed prior to placing new pavement. Rock socks will be utilized in the
existing curb and the newly constructed swales to capture sediments that are not fully
contained by the silt fence placement. The locations of the rock socks will be in the areas
of concentrated flow such as in the existing curb, at the new swales and as needed.
The site will also utilize a vehicle tracking control pad at each entrance to minimize
sediment from being tracked onto adjacent pavements. Sediment that is tracked will be
removed and placed within the site or permanently disposed of offsite. A concrete
washout will be used on site during the concrete placement. All hardened concrete will
be disposed of offsite. These BMP’s have not been located on the site map due to the
6
fact that the site is very small and these BMP’s will need to be placed by the contractor in
locations that are most beneficial and will minimize disruption of adjacent traffic.
Permanent erosion control consists of covering the soils with a building, concrete walks,
concrete drives and sod. No soil will be left exposed to erosion after the construction is
complete. Refer to the landscape plan for areas of and instructions for placement of sod
and soil amendments required prior to placement of sod.
Refer to Appendix D for the timing of the construction phases and the sequential
installation of all BMP phasing for this site.
Refer to the Appendix D for the Erosion Control Surety calculations.
5.2 SWMP contact information
Permit holder:
Name:
Address:
Phone Number:
Email Address:
Appointed agent:
Name:
Address:
Phone Number:
Email Address:
7
5.3 Identification and location of all potential pollution sources
Potential Pollutant Source Activity Potential Pollutant Generated Applicable to
this project
Disturbed Areas Sediment X
Soil stockpiles Sediment X
Travel to adjacent public streets Tracked sediment X
Contaminated soils Sediment, chemicals
Loading and unloading chemicals Chemicals
Unloading of building materials Trash, debris X
Outdoor storage of chemicals Chemicals
On site equipment maintenance Oil, grease
On site equipment fueling Diesel, gasoline X
Dust generating activities Particulates, sediment X
Use of fertilizer, pesticides, herbicides Fertilizer, pesticides
Use of detergents, solvents, oils Detergents, solvents, oil X
Waste dumpsters, waste piles Chemicals, trash, debris X
Concrete washout Concrete, sediment, wash water X
On site equipment washing Detergents, oil
On site asphalt batch plant Asphaltic cement, sediment
On site concrete batch plant Cement, sediment
Portable toilets Domestic sewage X
5.4 Best Management Practices (BMP’s) for Stormwater Pollution Prevention
Structural Practices for Erosion and Sediment Control
Structural practices for the site will consist mainly of silt fence and rock sock filters and are
described in detail in the following paragraphs. These BMP's are expected to change as the
construction progresses and it is the responsibility of the contractor to ensure appropriate BMP's
are in place and/or removed at the appropriate time in the construction sequence. All temporary
and permanent erosion and sediment control practices must be maintained and repaired as
needed to assure continued performance of their intended function.
Silt fence and rock sock filters shall be in place prior to commencement of construction
activities. During clearing and grubbing necessary for silt fence installation, all cleared material
shall be placed on the uphill side so that if erosion occurs from the cleared material, the sediment
will be trapped and not transported downstream. Rock socks shall be implemented in the existing
curb line as shown on the Drainage & Erosion Control Plan.
8
All BMP's shall be installed per the details shown on the construction plan set.
Temporary & Permanent Structural BMP’s:
Structural BMP Approximate location on site Applicable to this
Project
Silt Fence Site perimeter, refer to site map X
Straw bale dams
Rock Socks At sidewalk culverts, in swales, at new inlet,
in existing gutters, refer to site map X
Earthen diversion dams
Vegetated swales
Sediment trap/pond
Pipe slope drains
Geogrid
Inlet/outlet protection In the detention Pond X
Culverts
Riprap
Erosion control mats
Inlet protection
Vehicle Tracking Control Pad At site entrance, refer to site map X
Concrete Washout To be located by Contractor, near site entry X
Non-Structural Practices for Erosion and Sediment Control:
Soils exposed during the earthwork phase and landscape prep phase shall be kept in a roughened
condition by ripping or disking along land contours until mulch, vegetation, or other permanent
erosion control is installed. No large amount of soils (in excess of 15 yards) will be allowed to be
stock piled on site. Overburden from the utility pipe trenching will be piled adjacent to trenches
upstream of sediment controls and will be replaced in the trenches within 72 hours.
Excess excavated materials from the demolition and grading phases of the project that cannot be
reused on site will be exported as it is excavated. This includes any asphalt pavement from the
existing site that is to be removed.
A vehicle tracking pad will be installed at a location most beneficial to the site construction as
determined by the contractor. Vehicles will not be permitted in the excavated area if soil is
muddy. Gravel sub base will be placed and compacted in the areas indicated for pavement
following excavation. In the current pre construction state the site enables tracking of silt onto
the adjacent streets during wet conditions. During construction activities the street will be
monitored for foreign debris tracked out of the site and mechanical sweeping and clean up will
be performed as needed.
9
No area shall remain exposed by land disturbing activity for more than thirty (30) days before
required temporary or permanent erosion control (e.g. seed/mulch, landscaping, etc.) is installed.
Temporary & Permanent non-structural BMP’s:
Non-Structural BMP Approximate location on site Applicable to this
Project
Surface roughening Entire site X
Soil stockpile height limit (less than
10’)
Perimeter vegetative buffer North boundary of site X
Minimization of site disturbance
Mulch
Seed & mulch stockpiles after 30 days
Stockpile toe protection (silt fence,
wattles or ditch)
Preservation & protection of existing
vegetation & trees North boundary of site X
Good site housekeeping (routine
cleanup of trash & constr debris) Entire Site X
Sweeping & scraping of hardscape
areas On and off site pavements X
Heavy equip staged on site, properly
maintained & inspected daily (no
onsite maintenance)
Staging area X
5.5 BMP Implementation
1) Phased BMP Implementation
BMP’s are expected to change as the construction progresses and it is the responsibility of
the contractor to ensure appropriate BMP’s are in place and/or removed at the appropriate
time in the construction sequence. A construction sequence schedule has been included on
the Drainage & Erosion Control Plan and included in the construction plans for this site.
All BMP’s shall be inspected and repaired or replaced as required to satisfy the conditions of
the Stormwater Discharge Permit. All BMP’s must be maintained and repaired as needed to
assure continued performance of their intended function. Refer to Appendix D for the BMP
schedule and estimated costs.
10
2) Materials Handling and Spill Prevention:
Materials Handling & Spill
Prevention BMP Approximate location on site
Applicable to this
Project
Portable toilets, anchored &
located away from drainages Contractor to determine X
Fuel storage located in bulk tanks
with secondary containment &
spill kit
Mobile fueling performed at least
200 feet away from drainages &
fully attended
Contractor to determine X
Fertilizers, form oil, solvents,
cleaners, detergent stored in 55 gal
or smaller containers, kept in
storage units
Contractor to determine X
Dumpsters containing used
chemicals containers & liquid
wastes kept covered
Contractor to determine X
Equipment cleaning (on site) uses
no detergents & flows to onsite
retention basin
In case of a release of fuel or other
chemicals, absorbent booms or
earthen berms will be immediately
constructed to contain the spill &
prevent runoff to adjacent surface
waters
Location of spill X
MSDS sheets for onsite chemicals
will be kept at the construction
trailer to facilitate spill response &
cleanup
Contractor to determine X
3) Dedicated Asphalt or Concrete Batch Plant:
Not proposed with this development
4) Vehicle Tracking Pad:
Vehicle tracking control pad shall be installed wherever construction vehicle access routes
intersect paved public roads. Vehicle tracking control pads shall be installed to minimize the
transport of sediment (mud) by runoff or vehicles tracking onto the paved surface. Any mud
tracked to public roads shall be removed on a daily basis and after any significant storm that
causes sediment to be transported. It is unlawful to track sediment/mud onto public streets
and may be enforced by the City of Fort Collins, by the State of Colorado or by the EPA.
11
5) Waste Management and Disposal:
Portable toilets will be anchored & periodically maintained by waste management company.
Dumpsters on site will be covered & periodically emptied by waste management company.
Concrete waste will be allowed to harden and then will be removed from site.
No washing activities will occur on site.
Location of the concrete washout is shown on the site map. The washout will be suitably
deep to accommodate all anticipated concrete truck wash water. Waste concrete will be
allowed to harden & be removed from site periodically as the washout reaches 50% of
capacity. Truck wash water will not be allowed to reach the curb & gutter or any other water
course.
6) Groundwater and Stormwater Dewatering:
No groundwater was encountered during soils exploration therefore ground water is not
anticipated to be an issue. If groundwater is encountered a groundwater discharge permit
shall be obtained and a detailed report shall be completed describing the location and the
route of where pumped groundwater will be conveyed and the measures taken to prevent the
transport of any pollutants to downstream waters.
7) Inspection & Maintenance:
It is required that routine site inspections are performed to effectively address maintenance
and repair of Best Management Practices (BMP's). The site inspections are to be performed
by the contractor or an inspector designated by the administrator at a minimum of once every
fourteen (14) calendar days on active construction sites and after any significant storm event
(an event causing runoff). As part of the site inspections the inspector is required to keep
documentation of all inspections and BMP maintenance, including an updated Site Map
indicating new BMP's or the removal of BMP's since the previous inspection.
Any maintenance, repair, or necessary installation of BMP's that are noted during the
inspection must be completed within seven (7) calendar days from the date of the
inspection
12
6. CONCLUSIONS
6.1 Compliance with Standards
All computations that have been completed within this report are in compliance with the
“City of Fort Collins Erosion Control Reference Manual for Construction Sites”, the
“City of Fort Collins Storm Drainage Design Criteria Manual”, and the “Urban Storm
Drainage Criteria Manual”.
6.2 Drainage Concept
The proposed drainage concepts presented in this report and on the construction plans
adequately provide for the collection and conveyance of on-site runoff to the detention
area. Conveyance elements exist to adequately convey detained runoff downstream.
If, at the time of construction, groundwater is encountered, a Colorado Department of
Health Construction Dewatering Permit would be required.
13
7. REFERENCES
1. Urban Drainage and Flood Control District, “Urban Storm Drainage Criteria
Manual”, 2001 Edition Volume 1 updated June 2001, January 2004 and April
2008; Volume 2 updated June 2001 and April 2008; and Volume 3 updated
November and December 2010.
2. The Fort Collins Amendments to the Urban Drainage and Flood Control District
Criteria Manual, adopted by the City Council of the City of Fort Collins, as
referenced in Section 26-500 (c) of the Code of the City of Fort Collins.
3. ORDINANCE NO. 152, 2012 of the Council of the City of Fort Collins amending
Chapter 26 of the Code of the City of Fort Collins and the Fort Collins
Stormwater Criterial Manual to incorporate provisions implementing Low Impact
Development (LID) Principles.
A
APPENDIX A
VICINITY MAP
B
APPENDIX B
HYDROLOGIC COMPUTATIONS
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION: Affordable Storage
PROJECT NO: 177-06
COMPUTATIONS BY: ppk
DATE: 1/29/2017
Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
% Runoff
Impervious coefficient
C
Streets, parking lots (asphalt): 100% 0.95
Sidewalks: 96% 0.95
Gravel: 40% 0.50
Roofs: 90% 0.95
Lawns (flat <2%, heavy soil): 0% 0.20
SUBBASIN TOTAL TOTAL ROOF PAVED SIDEWALK GRAVEL LANDSCAPE % RUNOFF
DESIGNATION AREA AREA AREA AREA AREA AREA AREA Impervious COEFF.
(ac.) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (sq.ft) (C)
1 0.58 25060 13790 11270 0 0 0 94% 0.95
2 0.38 16404 6674 9,730 0 0 0 96% 0.95
3 0.58 25205 5322 17750 1,125 0 1,008 94% 0.92
4 0.82 35744 29464 0 0 0 6,280 74% 0.82
5 0.24 10355 4097 6258 0 0 0 96% 0.95
6 0.36 15575 0 0 0 0 15,575 0% 0.20
7 0.29 12,448 0 1350 0 0 11,098 11% 0.28
Total 3.23 140,791 59,347 46,358 1,125 0 33,961 72% 0.77
Equations
- Calculated C coefficients & % Impervious are area weighted
C = (Ci Ai) / At
Ci = runoff coefficient for specific area, Ai
Ai = areas of surface with runoff coefficient of Ci
n = number of different surfaces to consider
At = total area over which C is applicable; the sum of all Ai's
Flow.xls Cval
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION: Affordable Storage
PROJECT NO: 177-06
COMPUTATIONS BY: ppk
DATE: 1/29/2017
2-yr storm Cf = 1.00
FINAL REMARKS
tc
DESIGN SUBBASIN(s) Area C Length Slope ti Length Slope n Vel. tt tc = Total L tc=(l/180)+10
POINT (ac) (ft) (%) (min) (ft) (%) Manning (ft/s) (min) ti + tt (ft) (min) (min)
(1) (2) (3) (4) (5) (6) (7) (8) rough. (9) (10) (11) (12) (13) (14)
1 1 0.58 0.95 25 2.5 1.0 270 1.0 0.016 2.0 2.24 3.2 295 11.6 5.0
1 2 0.38 0.95 25 2.0 1.1 388 1.0 0.016 2.0 3.30 4.4 413 12.3 5.0
1 3 0.58 0.92 25 2.0 1.3 328 1.0 0.016 2.0 2.79 4.1 353 12.0 5.0
1 4 0.82 0.82 125 1.0 5.7 327 0.5 0.030 0.8 7.19 12.9 452 12.5 12.5
1 5 0.24 0.95 15 2.5 0.8 168 1.0 0.016 2.0 1.39 2.2 183 11.0 5.0
1 6 0.36 0.20 16 20.0 2.4 105 0.5 0.016 1.4 1.23 3.6 121 10.7 5.0
1 7 0.29 0.28 10 20.0 1.7 85 0.1 0.016 0.4 3.15 4.9 95 10.5 5.0
1 ALL 3.23 0.77
EQUATIONS:
tc = ti + tt
ti = [1.87 (1.1 - CCf ) L0.5 ] / S 1/3
tt = L/Vel. Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + tt and urbanized basin check
min. tc = 5 minutes
TIME (ti)
TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
STANDARD FORM SF-2
TIME OF CONCENTRATION - 2 YEAR
SUB-BASIN DATA INITIAL /OVERLAND
Flow.xls TOC-2
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
LOCATION: Affordable Storage
PROJECT NO: 177-06
COMPUTATIONS BY: ppk
DATE: 1/29/2017
100-yr storm Cf = 1.25
FINAL REMARKS
tc
DESIGN SUBBASIN(s) Area C C*Cf Length Slope ti Length Slope n Vel. tt tc = Total L tc=(l/180)+10
POINT (ac) (ft) (%) (min) (ft) (%) Manning (ft/s) (min) ti + tt (ft) (min) (min)
(1) (2) (3) (4) (5) (6) (7) (8) rough. (9) (10) (11) (12) (13) (14)
1 1 0.58 0.95 1.00 25 2.5 0.7 270 1.0 0.016 2.0 2.24 2.9 295 11.6 5.0
1 2 0.38 0.95 1.00 25 2.0 0.7 388 1.0 0.016 2.0 3.30 4.0 413 12.3 5.0
1 3 0.58 0.92 1.00 25 2.0 0.7 328 1.0 0.016 2.0 2.79 3.5 353 12.0 5.0
1 4 0.82 0.82 1.00 125 1.0 2.0 327 0.5 0.030 0.8 7.19 9.2 452 12.5 9.2
1 5 0.24 0.95 1.00 15 2.5 0.5 168 1.0 0.016 2.0 1.39 1.9 183 11.0 5.0
1 6 0.36 0.20 0.25 16 20.0 2.3 105 0.5 0.016 1.4 1.23 3.5 121 10.7 5.0
1 7 0.29 0.28 0.35 10 20.0 1.6 85 0.1 0.016 0.4 3.15 4.7 95 10.5 5.0
1 ALL 3.23 0.77 0.97
EQUATIONS:
tc = ti + tt
ti = [1.87 (1.1 - CCf ) L
0.5
] / S
1/3
tt = L/Vel. Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + tt and urbanized basin check
min. tc = 5 minutes
TIME OF CONCENTRATION - 100 YR
STANDARD FORM SF-2
SUB-BASIN DATA
TIME (ti)
INITIAL /OVERLAND TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
tc CHECK
(URBANIZED BASIN)
Flow.xls TOC-100
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550
RATIONAL METHOD PEAK RUNOFF
(2-YEAR)
LOCATION: Affordable Storage
PROJECT NO: 177-06
COMPUTATIONS BY: ppk
DATE: 1/29/2017
2-yr storm, Cf = 1.00
TOTAL REMARKS
Design Tributary A C*Cf tc i Q (2) from Q (2) Q(2)tot
Sub-basin (new) Design
Point (ac) (min) (in/hr) (cfs) Point (cfs) (cfs)
1 1 0.58 0.95 5.0 2.85 1.6 1.6 To area inlet 1
1 2 0.38 0.95 5.0 2.85 1.0 1.0 To Rain Garden 1
1 3 0.58 0.92 5.0 2.85 1.5 1.5 To Rain Garden 1
1 4 0.82 0.82 12.5 2.02 1.4 1.4 To grassed swale (inlet 2)
1 5 0.24 0.95 5.0 2.85 0.6 0.6 To Rain Garden 2
1 6 0.36 0.20 5.0 2.85 0.2 0.2 Det Pond
1 7 0.29 0.28 5.0 2.85 0.2 0.2 To Street
1 ALL 3.23 0.77
Q = Cf C iA
Q = peak discharge (cfs)
C = runoff coefficient
Cf = frequency adjustment factor
i = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
DIRECT RUNOFF CARRY OVER
Flow.xls Q2
North Star Design, Inc.
700 Automation Drive, Unit I
Windsor, CO 80550 RATIONAL METHOD PEAK RUNOFF
(100-YEAR)
LOCATION: Affordable Storage
PROJECT NO: 177-06
COMPUTATIONS BY: ppk
DATE: 1/29/2017
100-yr storm, Cf = 1.25
TOTAL REMARKS
Des. Area A C*Cf tc i Q (100) from Q (100) Q(100)tot
(new) Design
Point Design. (ac) (min) (in/hr) (cfs) Point (cfs) (cfs)
1 1 0.58 1.00 5.0 9.95 5.7 5.7 To area inlet 1
1 2 0.38 1.00 5.0 9.95 3.7 3.7 To Rain Garden 1
1 3 0.58 1.00 5.0 9.95 5.8 5.8 To Rain Garden 1
1 4 0.82 1.00 9.2 7.97 6.5 6.5 To grassed swale (inlet 2)
1 5 0.24 1.00 5.0 9.95 2.4 2.4 To Rain Garden 2
1 6 0.36 0.25 5.0 9.95 0.9 0.9 Det Pond
1 7 0.29 0.35 5.0 9.95 1.0 1.0 To Street
1 ALL 3.23 0.97 5.0 9.95 31.1 31.1
Q = C iA
Q = peak discharge (cfs)
C = runoff coefficient
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
DIRECT RUNOFF CARRY OVER
Flow.xls Q100
C
APPENDIX C
HYDRAULIC & BMP SIZING CALCULATIONS
Grass Type Limiting Manning's n
A0.06
B0.04
C 0.033
D0.03
E 0.024
Analysis of Trapezoidal Grass-Lined Channel Using 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 = 0.0100 ft/ft
Bottom Width B = 0.00 ft
Left Side Slope Z1 = 15.87 ft/ft
Right Side Slope Z2 = 21.74 ft/ft
Check one of the following soil types:
Soil Type: Max. Velocity (VMAX) Max Froude No. (FMAX)
Sandy 5.0 fps 0.50
Non-Sandy 7.0 fps 0.80
Minor Storm Major Storm
Max. Allowable Top Width of Channel for Minor & Major Storm TMAX = 30.00 30.00 feet
Max. Allowable Water Depth in Channel for Minor & Major Storm dMAX = 0.70 0.70 feet
Allowable Channel Capacity Based On Channel Geometry Minor Storm Major Storm
MINOR STORM Allowable Capacity is based on Depth Criterion Qallow = 42.58 42.58 cfs
MAJOR STORM Allowable Capacity is based on Depth Criterion dallow = 0.70 0.70 ft
Water Depth in Channel Based On Design Peak Flow
Design Peak Flow Qo = 1.60 5.70 cfs
Water Depth d = 0.20 0.33 feet
AREA INLET IN A TRAPEZOIDAL GRASS-LINED CHANNEL
Affordable Storage
Inlet 1
Minor storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
Major storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
Choose One:
Sandy
Non-Sandy
Inlet No.1.xlsm, Area Inlet 1/29/2017, 3:28 PM
AREA INLET IN A TRAPEZOIDAL GRASS-LINED CHANNEL
Affordable Storage
Inlet 1
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 = 2.00 feet
Length of Grate L = 3.00 feet
Open Area Ratio ARATIO = 0.70
Height of Inclined Grate HB = 0.00 feet
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 = 0.20 0.33
Total Inlet Interception Capacity (assumes clogged condition) Qa
= 1.47 3.00 cfs
WARNING: Inlet Capacity less than Q Peak for Minor and Major Storms Bypassed Flow, Qb = 0.13 2.70 cfs
Capture Percentage = Qa/Qo = C% 92 53 %
Warning 04: Froude No. exceeds USDCM Volume I recommendation.
User-Defined
Inlet No.1.xlsm, Area Inlet 1/29/2017, 3:28 PM
1/26/2017 UDSEWER Math Model Interface Results: New UDSEWER System Module 01/26/2017 15:04
file:///C:/Users/Patricia/Documents/report0.html 1/2
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)
OUTFALL
1 72.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
STMH 1 72.00 3.00 0.00 0.00 1.00 0.95 0.00 0.00 0.00 0.00
Inlet 1 71.90 3.00 3.00 0.58 1.00 0.95 25.00 2.00 240.00 2.83
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)
1/26/2017 UDSEWER Math Model Interface Results: New UDSEWER System Module 01/26/2017 15:04
file:///C:/Users/Patricia/Documents/report0.html 2/2
Existing Calculated Used
Element
Name
Peak
Flow
(cfs)
Cross
Section Rise Span Rise Span Rise Span
Area
(ft^2) Comment
STMH 1 3.00 CIRCULAR 15.00 in 15.00 in 15.00 in 15.00 in 15.00 in 15.00 in 1.23
Inlet 1 3.00 CIRCULAR 15.00 in 15.00 in 15.00 in 15.00 in 15.00 in 15.00 in 1.23
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): 68.80
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)
STMH 1 68.85 69.10 0.00 0.00 69.55 69.96 69.83 0.30 70.13
Inlet 1 69.12 69.90 0.00 0.00 69.97 70.70 70.15 0.76 70.90
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.
0.00 20.50 41.00 61.50 82.00 102.50 123.00 143.50 164.00 184.50 205.00
68.54
68.84
69.14
69.44
69.74
70.04
70.34
70.64
70.94
71.24
71.54
71.84
HGL
EGL
Grass Type Limiting Manning's n
A0.06
B0.04
C 0.033
D0.03
E 0.024
Analysis of Trapezoidal Grass-Lined Channel Using 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 = 0.030
Channel Invert Slope SO = 0.0050 ft/ft
Bottom Width B = 4.00 ft
Left Side Slope Z1 = 4.00 ft/ft
Right Side Slope Z2 = 4.00 ft/ft
Check one of the following soil types:
Soil Type: Max. Velocity (VMAX) Max Froude No. (FMAX)
Sandy 5.0 fps 0.50
Non-Sandy 7.0 fps 0.80
Minor Storm Major Storm
Max. Allowable Top Width of Channel for Minor & Major Storm TMAX = 30.00 30.00 feet
Max. Allowable Water Depth in Channel for Minor & Major Storm dMAX = 1.50 1.50 feet
Allowable Channel Capacity Based On Channel Geometry Minor Storm Major Storm
MINOR STORM Allowable Capacity is based on Depth Criterion Qallow = 49.70 49.70 cfs
MAJOR STORM Allowable Capacity is based on Depth Criterion dallow = 1.50 1.50 ft
Water Depth in Channel Based On Design Peak Flow
Design Peak Flow Qo = 1.40 6.50 cfs
Water Depth d = 0.24 0.55 feet
AREA INLET IN A TRAPEZOIDAL GRASS-LINED CHANNEL
Affordable Storage
Inlet 2
Minor storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
Major storm max. allowable capacity GOOD - greater than flow given on sheet 'Q-Peak'
Choose One:
Sandy
Non-Sandy
Inlet No.2.xlsm, Area Inlet 1/29/2017, 3:28 PM
AREA INLET IN A TRAPEZOIDAL GRASS-LINED CHANNEL
Affordable Storage
Inlet 2
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 = 2.00 feet
Length of Grate L = 3.00 feet
Open Area Ratio ARATIO = 0.70
Height of Inclined Grate HB = 0.00 feet
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 = 0.24 0.55
Total Inlet Interception Capacity (assumes clogged condition) Qa
= 1.84 6.48 cfs
WARNING: Inlet Capacity is less than Q Peak for Major Storm Bypassed Flow, Qb = 0.00 0.02 cfs
Capture Percentage = Qa/Qo = C% 100 100 %
User-Defined
Inlet No.2.xlsm, Area Inlet 1/29/2017, 3:28 PM
1/26/2017 UDSEWER Math Model Interface Results: Storm 2 01/26/2017 15:15
file:///C:/Users/Patricia/Documents/report0.html 1/2
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)
OUTFALL
1 72.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Inlet 2 71.00 6.50 6.50 0.82 1.00 0.82 25.00 20.00 220.00 6.71
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
1/26/2017 UDSEWER Math Model Interface Results: Storm 2 01/26/2017 15:15
file:///C:/Users/Patricia/Documents/report0.html 2/2
Inlet 2 6.50 CIRCULAR 18.00 in 18.00 in 18.00 in 18.00 in 18.00 in 18.00 in 1.77
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): 68.80
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)
Inlet 2 68.98 69.40 0.00 0.00 69.97 70.60 70.40 0.48 70.88
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.
0.00 7.00 14.00 21.00 28.00 35.00 42.00 49.00 56.00 63.00
68.68
68.98
69.28
69.58
69.88
70.18
70.48
70.78
71.08
71.38
71.68
71.98
HGL
EGL
Sheet 1 of 1
Designer:
Company:
Date:
Project:
Location:
1. To identify potential BMPs, what best describes
the type of site?
SKIP # 2
2. Does the typical section include a parking lane, shoulder,
median, or otherwise allow for surface BMPs?
3. Is the site comprised of Hydrologic Soil Group A or B soils?
SKIP # 4
4. Is the tributary impervious area
1
greater than 1 acre?
5. Is the depth of bedrock greater than 5 feet?
SKIP # 6-8
6. Is the tributary impervious area
1
greater than 5 acres?
7. Is a water source available for use?
(baseflow or groundwater)
8. Is the BMP in a developing watershed?
9. Are BMPs allowed in the right-of-way?
SKIP # 10
10. Does the community have an established Fee in Lieu
Program in place?
11. Step 1 of Four Step Process: Permeable Pavement- Partial or No Infiltration (4)
MDCIA / Volume Reduction (Not WQCV) BMPs Green Roof (1)
12. Step 2 of Four Step Process: Permeable Pavement- Partial or No Infiltration (4)
WQCV BMPs Bioretention- Partial or No Infiltration (4)
Green Roof (1)
Underground BMPs with Full WQCV (2)
Regional Water Quality Treatment (3)
Notes: 1. In the Front Range of Colorado, irrigation, at least periodically in dry times, will be required to sustain a green roof.
2. Underground BMPs should only be considered when surface-based BMPs are not practicable and only when approved by the local
jurisdiction. See the Underground BMP Fact Sheet for additional restrictions on use.
3. If a regional facility will be used to provide the WQCV, some degree of onsite treatment/MDCIA will still likely be required.
4. No Infiltration= underdrain and liner, Partial Infiltration= underdrain and no liner, Full Infiltration= no underdrain and no liner.
Design Procedure Form: BMP Selection Tool
Patricia Kroetch
North Star Design Inc
January 29, 2017
Affordable Storage
UD-BMP (Version 3.06, November 2016)
Choose One
Highly Urbanized Sites
Conventional Sites
Choose One
YES
NO
Choose One
YES
NO
Choose One
YES
NO
Choose One
YES
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 95.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.950
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.36 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 41,609 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 1,241 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 0.0 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 791 sq ft
D) Actual Flat Surface Area AActual = 799 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 1833 sq ft
F) Rain Garden Total Volume VT= 1,316 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = 1.0 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 1,241 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 1 in
Design Procedure Form: Rain Garden (RG)
PPK
North Star Design, Inc.
January 29, 2017
Affordable Storage
Basin 2 and 3
UD-BMP (Version 3.06, November 2016)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_Basin 2 and 3.xlsm, RG 1/29/2017, 3:42 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
PROVIDE A 30 MIL (MIN) PVC LINER WITH CDOT CLASS B
GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW
THE LINER IF THE SUBGRADE IS ANGULAR
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
PPK
North Star Design, Inc.
January 29, 2017
Affordable Storage
Basin 2 and 3
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_Basin 2 and 3.xlsm, RG 1/29/2017, 3:42 PM
Sheet 1 of 1
Designer:
Company:
Date:
Project:
Location:
1. Design Discharge for 2-Year Return Period Q2 = 1.70 cfs
2. Hydraulic Residence Time
A) : Length of Grass Swale LS = 255.0 ft
B) Calculated Residence Time (based on design velocity below) THR= 5.2 minutes
3. Longitudinal Slope (vertical distance per unit horizontal)
A) Available Slope (based on site constraints) Savail = 0.005 ft / ft
B) Design Slope SD = 0.005 ft / ft
4. Swale Geometry
A) Channel Side Slopes (Z = 4 min., horiz. distance per unit vertical) Z = 4.00 ft / ft
B) Bottom Width of Swale (enter 0 for triangular section) WB = 4.00 ft
5. Vegetation
A) Type of Planting (seed vs. sod, affects vegetal retardance factor)
6. Design Velocity (0.85 ft / s maximum for desirable 5-minute residence time) V2 = 0.81 ft / s
7. Design Flow Depth (1 foot maximum) D2 = 0.38 ft
A) Flow Area A2 = 2.1 sq ft
B) Top Width of Swale WT = 7.0 ft
C) Froude Number (0.50 maximum) F = 0.26
D) Hydraulic Radius RH = 0.29
E) Velocity-Hydraulic Radius Product for Vegetal Retardance VR = 0.24
F) Manning's n (based on SCS vegetal retardance curve D for sodded grass) n = 0.200
G) Cumulative Height of Grade Control Structures Required HD = 0.00 ft
AN UNDERDRAIN IS
8. Underdrain REQUIRED IF THE
(Is an underdrain necessary?) DESIGN SLOPE < 2.0%
9. Soil Preparation
(Describe soil amendment)
10. Irrigation
Notes:
Design Procedure Form: Grass Swale (GS)
PPK
North Star Design, Inc.
January 29, 2017
Affordable Storage
Basin 4
UD-BMP (Version 3.06, November 2016)
Choose One
Temporary Permanent
Choose One
Grass From Seed Grass From Sod
Choose One
YES NO
UD-BMP_Basin 4.xlsm, GS 1/29/2017, 3:37 PM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 96.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.960
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.37 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 10,355 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = 316 cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 0.0 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 12 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 199 sq ft
D) Actual Flat Surface Area AActual = 230 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 542 sq ft
F) Rain Garden Total Volume VT= 386 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided?
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = 1.0 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 316 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 1/2 in
Design Procedure Form: Rain Garden (RG)
PPK
North Star Design, Inc.
January 29, 2017
Affordable Storage
Basin 5
UD-BMP (Version 3.06, November 2016)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_Basin 5.xlsm, RG 1/29/2017, 3:39 PM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
PROVIDE A 30 MIL (MIN) PVC LINER WITH CDOT CLASS B
GEOTEXTILE ABOVE IT. USE THE SAME GEOTEXTILE BELOW
THE LINER IF THE SUBGRADE IS ANGULAR
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
PPK
North Star Design, Inc.
January 29, 2017
Affordable Storage
Basin 5
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_Basin 5.xlsm, RG 1/29/2017, 3:39 PM
D
APPENDIX D
DETENTION POND SIZING CALCULATIONS
MINIMUM DETENTION VOLUME REQUIRED
FAA METHOD
(100-YEAR)
LOCATION: Affordable Storage
PROJECT NO: 177-10
COMPUTATIONS BY: PPK
SUBMITTED BY: North Star Design, Inc.
DATE: 1/29/2017
Equations: A trib. To pond = 3.23 acre
QD = CiA C100 = 0.77
Vi = T*CiA = T*QD Developed C*A = 2.5 acre
Vo =K*QPO*T QPO = 0.65 cfs (0.2 cfs per acre)
S = Vi - Vo K = 1 (from fig 2.1)
Rainfall intensity from City of Fort Collins IDF Curve
Storm Rainfall QD Vol. In Vol. Out Storage Storage
Duration, T Intensity, i (cfs) Vi Vo SS
(min) (in/hr) (ft3) (ft3) (ft3) (ac-ft)
5 9.95 24.7 7424 194 7230 0.166
10 7.72 19.2 11520 388 11133 0.256
20 5.60 13.9 16713 775 15938 0.366
30 4.52 11.2 20235 1163 19072 0.438
40 3.74 9.3 22324 1550 20774 0.477
50 3.23 8.0 24100 1938 22162 0.509
60 2.86 7.1 25607 2326 23282 0.534
70 2.62 6.5 27368 2713 24655 0.566
80 2.38 5.9 28413 3101 25312 0.581
90 2.22 5.5 29815 3488 26327 0.604
100 2.05 5.1 30591 3876 26715 0.613
110 1.93 4.8 31681 4264 27417 0.629
120 1.80 4.5 32233 4651 27582 0.633
130 1.60 4.0 31039 5039 26000 0.597
140 1.40 3.5 29248 5426 23822 0.547
150 1.20 3.0 26861 5814 21047 0.483
160 1.15 2.9 27458 6202 21256 0.488
170 1.10 2.7 27905 6589 21316 0.489
180 1.05 2.6 28204 6977 21227 0.487
Required Storage Volume: 27582 ft3
0.633 acre-ft
STAGE - STORAGE TABLE
(100-YEAR)
LOCATION: Affordable storage
PROJECT NO: 177-10
COMPUTATIONS BY: PPK
SUBMITTED BY: North Star Design, Inc.
DATE: 8/1/2008
100 yr Detention Volume Required = 0.633
Water Quality Volume Required = 0.000
Total Volume Required= 0.633
Surface Incremental Total
Stage Area Storage Storage
(ft) (ft2) (ac-ft) (ac-ft)
4766.00 0
4767.00 2,767 0.021 0.02
4768.0 6,160 0.094 0.09
4769.0 7,510 0.227 0.25
4770.0 8,985 0.189 0.44
100 yr WSEL 4770.90 10,425 0.200 0.638
4771.0 10,585 0.224 0.66 <==SPILLWAY ELEV
4772.0 18,345 0.328 0.99
Detention Pond Outlet Sizing
(100 yr event)
LOCATION: Affordable Storage
PROJECT NO: 177-10
COMPUTATIONS BY: PPK
SUBMITTED BY: North Star Design, Inc.
DATE: 1/29/2017
Submerged Orifice Outlet:
release rate is described by the orifice equation,
Qo = CoAo sqrt( 2g(h-Eo))
where Qo = orifice outflow (cfs)
Co = orifice discharge coefficient
g = gravitational acceleration = 32.2 ft/s
Ao = effective area of the orifice (ft2)
Eo = greater of geometric center elevation of the orifice or d/s HGL (ft)
h = water surface elevation (ft)
Qo = 0.65 cfs
outlet pipe dia = D = 12.0 in
Invert elev. = 4766.00 ft
Eo = 4766.14 ft
h = 4771.0 ft - 100 yr WSEL
Co = 0.62
solve for effective area of orifice using the orifice equation
Ao = 0.059 ft2
= 8.5 in2
orifice dia. = d = 3.30 in
Check orifice discharge coefficient using Figure 5-21 (Hydraulic Engineering )
d / D = 0.27
kinematic viscosity, u = 1.22E-05 ft2/s
Reynolds no. = Red = 4Q/(pdu) = 2.47E+05
Co = (K in figure) = 0.62 check
Use d = 3.30 in
A o = 0.059 ft 2 = 8.55 in 2
Q max = 0.65 cfs
Emergency Overflow Spillway Sizing
LOCATION: Affordable Storage
PROJECT NO: 177-10
COMPUTATIONS BY: PPK
SUBMITTED BY: North Star Design, Inc.
DATE: 5/24/2005
Equation for flow over a broad crested weir
Q = CLH3/2
where C = weir coefficient = 2.8
H = overflow height
L = length of the weir
The pond has a spill elevation 0 ft above the maximum water surface elevation in the pond
Spillway will be designed with 0725 ft flow depth, thus H = 1 ft
Size the spillway assuming that the pond outlet is completely clogged.
Q (100) = 31.3 cfs
Spill elev = 4970.90 ft 100 yr WSEL = 4970.9 ft
Top of berm elev.= 4972.00
Weir length required:
L = 11 ft
Use L = 20 ft
v = 1.42 ft/s
Stormwater Facility Name:
Facility Location & Jurisdiction:
User (Input) Watershed Characteristics User Defined User Defined User Defined User Defined
Watershed Slope = 0.010 ft/ft Stage [ft] Area [ft^2] Stage [ft] Discharge [cfs]
Watershed Length‐to‐Width Ratio = 1.60 L:W 0.00 0 0.00 0.00
Watershed Area =3.23acres 1.00 922 1.00 0.27
Watershed Imperviousness = 77.0% percent 2.00 4,107 2.00 0.40
Percentage Hydrologic Soil Group A =0.0%percent 3.00 10,813 3.00 0.50
Percentage Hydrologic Soil Group B = 0.0% percent 4.00 19,049 4.00 0.58
Percentage Hydrologic Soil Groups C/D = 100.0% percent 4.90 27,776 4.90 0.64
5.00 28,823 5.00 0.65
User Input 17 5.50 35,968 5.50 11.15
6.00 43,112 6.00 31.10
User Input: Detention Basin Characteristics
WQCV Design Drain Time = 40.00 hours
After completing and printing this worksheet to a pdf, go to:
https://maperture.digitaldataservices.com/gvh/?viewer=cswdif,
create a new stormwater facility, and
attach the pdf of this worksheet to that record.
Routed Hydrograph Results
Design Storm Return Period = WQCV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year
One‐Hour Rainfall Depth = 0.53 0.98 1.36 1.71 2.31 2.91 3.67 in
Calculated Runoff Volume = 0.083 0.200 0.298 0.392 0.559 0.723 0.940 acre‐ft
OPTIONAL Override Runoff Volume = acre‐ft
Inflow Hydrograph Volume = 0.082 0.200 0.298 0.392 0.559 0.722 0.939 acre‐ft
Time to Drain 97% of Inflow Volume = 368 10 14 17 21 hours
Time to Drain 99% of Inflow Volume = 47911141822 hours
Maximum Ponding Depth = 1.79 2.58 2.99 3.30 3.75 4.12 4.53 ft
Maximum Ponded Area = 0.078 0.183 0.247 0.305 0.389 0.462 0.553 acres
Maximum Volume Stored = 0.049 0.149 0.237 0.323 0.477 0.634 0.842 acre‐ft
Location for 1‐hr Rainfall Depths (use dropdown):
Workbook Protected Worksheet Protected
Stormwater Detention and Infiltration Design Data Sheet
Affordable Storage
Affordable Storage, Fort Collins, CO
SDI_Drain time check_FC_Rainfall.xlsm, Design Data 1/29/2017, 3:55 PM
Doing_Clear_FoYes
CountA= 1
0123
#N/A
#N/A
0123
#N/A
#N/A
Check Data Set 1 Check Data Set 1
Area
Discharge
Stormwater Detention and Infiltration Design Data Sheet
0
5
10
15
20
25
0.1 1 10
FLOW [cfs]
TIME [hr]
100YR IN
100YR OUT
50YR IN
50YR OUT
25YR IN
25YR OUT
10YR IN
10YR OUT
5YR IN
5YR OUT
2YR IN
2YR OUT
WQCV IN
WQCV OUT
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
0.1 1 10 100
PONDING DEPTH [ft]
DRAIN TIME [hr]
100YR
50YR
25YR
10YR
5YR
2YR
WQCV
SDI_Drain time check_FC_Rainfall.xlsm, Design Data 1/29/2017, 3:55 PM
E
APPENDIX E
BMP SCHEDULE & COST ESTIMATE
1/30/2017
Calculation for Required LID Treatment
New Impervious Area 106730 sq. ft.
Required Minimum Impervious Area to be Treated (75%) 80048 sq. ft.
Impervious Area Treated by LID Treatment Method #1 (Rain
garden) 40601 sq. ft.
Impervious Area Treated by LID Treatment Method #2 (Rain
garden) 10355 sq. ft.
Impervious Area Treated by LID Treatment Method #3
(Grassed swale/bioswale) 29464 sq. ft.
Total Impervious Area Treated 80420 sq. ft.
AFFORDABLE STORAGE
LID Summary Table
Project: Disturbed Acres: 3.23
EROSION CONTROL BMPs Units
Estimated
Quantity
Unit
Price
Total
Price
L.F. 1295 $3.00 $3,885.00
each 10 $85.00 $850.00
each 1 $180.00 $180.00
each 2 $1,500.00 $3,000.00
each 1 $1,200.00 $1,200.00
Sub-Total: $9,115.00
1.5 x Sub-Total: $13,672.50
Amount of security: $13,672.50
Total Acres x Price/acre: $3,876.00
$1,200.00 Sub-Total: $3,876.00
1.5 x Sub-Total: $5,814.00
Amount to Re-seed: $5,814.00
Minimum escrow amount: $3,000.00
Erosion Control Escrow: $13,672.50
Erosion and Sediment Control Escrow/Security Calculation
for The City of Fort Collins
BMP Amount
Silt Fence
Concrete Washout
Reseeding Amount
Rock Berm
Miniumum Escrow Amount
Affordable Storage
Unit Price of Seeding per acre:
“The amount of the security must be based on one and one-half times the estimate of the cost to install the approved measures, or one and one-half times
the cost to re-vegetate the disturbed land to dry land grasses based upon unit cost determined by the City's Annual Revegetation and Stabilization Bid,
whichever is greater. In no instance, will the amount of security be less than one thousand five hundred dollars ($1,500) for residential development or three
thousand dollars ($3,000) for commercial development”
Rock Sock
Vehicle Tracking Control Pad
(add all other BMPs for the site in this list)
Final Escrow Amount
1/29/2017 2:29 PM N:\177-10 Affordable Storage\drainage\FC Escrow.xls
F
APPENDIX F
FIGURES AND TABLES
33
(11) Section 4.0 is amended to read as follows:
4.0 Intensity-Duration-Frequency Curves for Rational Method:
The one-hour rainfall Intensity-Duration-Frequency tables for use the Rational Method
of runoff analysis are provided in Table RA-7 and in Table RA-8.
Table RA-7 -- City of Fort Collins
Rainfall Intensity-Duration-Frequency Table
for Use with the Rational Method
(5 minutes to 30 minutes)
2-Year 10-Year 100-Year
Duration
(min)
Intensity
(in/hr)
Intensity
(in/hr)
Intensity
(in/hr)
5 2.85 4.87 9.95
6 2.67 4.56 9.31
7 2.52 4.31 8.8
8 2.4 4.1 8.38
9 2.3 3.93 8.03
10 2.21 3.78 7.72
11 2.13 3.63 7.42
12 2.05 3.5 7.16
13 1.98 3.39 6.92
14 1.92 3.29 6.71
15 1.87 3.19 6.52
16 1.81 3.08 6.3
17 1.75 2.99 6.1
18 1.7 2.9 5.92
19 1.65 2.82 5.75
20 1.61 2.74 5.6
21 1.56 2.67 5.46
22 1.53 2.61 5.32
23 1.49 2.55 5.2
24 1.46 2.49 5.09
25 1.43 2.44 4.98
26 1.4 2.39 4.87
27 1.37 2.34 4.78
28 1.34 2.29 4.69
29 1.32 2.25 4.6
30 1.3 2.21 4.52
34
Table RA-8 -- City of Fort Collins
Rainfall Intensity-Duration-Frequency Table
for Use with the Rational Method
(31 minutes to 60 minutes)
2-Year 10-Year 100-Year
Duration
(min)
Intensity
(in/hr)
Intensity
(in/hr)
Intensity
(in/hr)
31 1.27 2.16 4.42
32 1.24 2.12 4.33
33 1.22 2.08 4.24
34 1.19 2.04 4.16
35 1.17 2.0 4.08
36 1.15 1.96 4.01
37 1.16 1.93 3.93
38 1.11 1.89 3.87
39 1.09 1.86 3.8
40 1.07 1.83 3.74
41 1.05 1.8 3.68
42 1.04 1.77 3.62
43 1.02 1.74 3.56
44 1.01 1.72 3.51
45 0.99 1.69 3.46
46 0.98 1.67 3.41
47 0.96 1.64 3.36
48 0.95 1.62 3.31
49 0.94 1.6 3.27
50 0.92 1.58 3.23
51 0.91 1.56 3.18
52 0.9 1.54 3.14
53 0.89 1.52 3.1
54 0.88 1.5 3.07
55 0.87 1.48 3.03
56 0.86 1.47 2.99
57 0.85 1.45 2.96
58 0.84 1.43 2.92
59 0.83 1.42 2.89
60 0.82 1.4 2.86
36
RAINFALL INTENSITY-DURATION-FREQUENCY CURVE
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
0.00 10.00 20.00 30.00 40.00 50.00 60.00
STORM DURATION (minutes)
RAINFALL INTENSITY (inches/hour)
2-Year Storm 10-Year Storm 100-Year Storm
Figure RA-16 City of Fort Collins Rainfall Intensity-Duration-Frequency Curves
(13) Section 5.0 is deleted in its entirety.
(14) Section 6.0 is deleted in its entirety.
(15) Section 7.0 is deleted in its entirety.
(16) Section 7.1 is deleted in its entirety.
(17) Section 7.2 is deleted in its entirety.
(18) Section 7.3 is deleted in its entirety.
(19) Section 8.0 is deleted in its entirety.
(20) Table RA-1 is deleted in its entirety.
40
Table RO-10
Rational Method Minor Storm Runoff Coefficients for Zoning Classifications
Description of Area or Zoning Coefficient
R-F 0.3
U-E 0.3
L-M-In 0.55
R-L, N-C-L 0.6
M-M-N, N-C-M 0.65
N-C-B 0.7
Business:
C-C-N, C-C-R, C-N, N-C, C-S 0.95
R-D-R, C-C, C-L 0.95
D, C 0.95
H-C 0.95
C-S 0.95
Industrial:
E 0.85
I 0.95
Undeveloped:
R-C, T 0.2
P-O-L 0.25
For guidance regarding zoning districts and classifications of such districts please refer to
Article Four of the City Land Use Code, as amended.
41
Table RO-11
Rational Method Runoff Coefficients for Composite Analysis
Character of Surface Runoff Coefficient
Streets, Parking Lots,
Drives:
Asphalt 0.95
Concrete 0.95
Gravel 0.5
Roofs 0.95
Recycled Asphalt 0.8
Lawns, Sandy Soil:
Flat <2% 0.1
Average 2 to 7% 0.15
Steep >7% 0.2
Lawns, Heavy Soil:
Flat <2% 0.2
Average 2 to 7% 0.25
Steep >7% 0.35
(4) A new Section 2.9 is added, to read as follows:
2.9 Composite Runoff Coefficient
Drainage sub-basins are frequently composed of land that has multiple surfaces or zoning
classifications. In such cases a composite runoff coefficient must be calculated for any
given drainage sub-basin.
The composite runoff coefficient is obtained using the following formula:
( )
t
n
i
i i
A
C A
C
∑
= = 1
*
(RO-8)
Where: C = Composite Runoff Coefficient
Ci = Runoff Coefficient for Specific Area (Ai)
Ai = Area of Surface with Runoff Coefficient of Ci, acres or feet2
n = Number of different surfaces to be considered
At = Total Area over which C is applicable, acres or feet2
(5) A new Section 2.10 is added, to read as follows:
42
2.10 Runoff Coefficient Adjustment for Infrequent Storms
The runoff coefficients provided in tables RO-10 and RO-11 are appropriate for use with
the 2-year storm event. For storms with higher intensities, an adjustment of the runoff
coefficient is required due to the lessening amount of infiltration, depression retention,
evapo-transpiration and other losses that have a proportionally smaller effect on storm
runoff. This adjustment is applied to the composite runoff coefficient.
These frequency adjustment factors are found in Table RO-12.
Table RO-12
Rational Method Runoff Coefficients for Composite Analysis
Storm Return Period
(years)
Frequency Factor
Cf
2 to 10
11 to 25
26 to 50
51 to 100
1.00
1.10
1.20
1.25
Note: The product of C times Cf cannot exceed the value of 1, in the cases where it does a value of
1 must be used
(6) Section 3.1 is deleted in its entirety.
(7) Section 3.2 is deleted in its entirety.
(8) Section 3.3 is deleted in its entirety.
(9) A new Section 4.3 is added, to read as follows:
4.3 Computer Modeling Practices
(a) For circumstances requiring computer modeling, the design storm hydrographs must
be determined using the Stormwater Management Model (SWMM). Basin and
conveyance element parameters must be computed based on the physical characteristics
of the site.
(b) Refer to the SWMM Users’ Manual for appropriate modeling methodology, practices
and development. The Users’ Manual can be found on the Environmental Protection
Agency (EPA) website (http://www.epa.gov/ednnrmrl/models/swmm/index.htm).
(c) It is the responsibility of the design engineer to verify that all of the models used in
the design meet all current City criteria and regulations.
4.3.1 Surface Storage, Resistance Factors, and Infiltration
Table RO-13 provides values for surface storage for pervious and impervious surfaces
and the infiltration rates to be used with SWMM. Table RO-13 also lists the appropriate
infiltration decay rate, zero detention depth and resistance factors, or Manning’s “n”
values, for pervious and impervious surfaces to be used for SWMM modeling in the city
of Fort Collins.
NO
Choose One
YES
NO
Choose One
YES
NO
Choose One
YES
NO
Choose One
YES
NO
Linear Construction in Urbanized Areas
Choose One
YES
NO
UD-BMP_Basin 2 and 3.xlsm, BMP Selection Tool 1/29/2017, 3:33 PM
(min)
Peak
Flow
(cfs)
Comment
OUTFALL 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Inlet 2 0.00 0.00 NaN 7.93 6.50 0.82 7.93 NaN 6.50
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)
Inlet 2 69.70 68.98 0.6 69.40 0.015 0.03 0.00 CIRCULAR 18.00 in 18.00 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
Inlet 2 7.07 4.00 11.83 5.28 13.60 4.54 0.76 Subcritical 6.50 0.00
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
Manhole Tc
(min)
Peak
Flow
(cfs)
Comment
OUTFALL 1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
STMH 1 0.00 0.00 0.00 0.00 0.00 0.58 5.17 NaN 3.00
Inlet 1 0.00 0.00 NaN 5.17 3.00 0.58 5.17 NaN 3.00
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)
STMH 1 49.40 68.85 0.5 69.10 0.015 0.03 0.00 CIRCULAR 15.00 in 15.00 in
Inlet 1 156.00 69.12 0.5 69.90 0.015 0.05 0.00 CIRCULAR 15.00 in 15.00 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
STMH 1 3.97 3.23 8.36 4.27 9.74 3.56 0.74 Subcritical 3.00 0.00
Inlet 1 3.97 3.23 8.36 4.27 9.74 3.56 0.74 Subcritical 3.00 0.00
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: