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} Design Group
HERITAGE CHRISTIAN ACADEMY
Industrial Business Park International PUD
Fart Collins, CD
Prepared for:
Heritage Christian Academy
2506 Zurich Drive #1
Fart Collins, CO 00524
Date:
September 18, 2024
19 OLD TOWN SQUARE#238 1 FORT COLLINS,CO 80524 1 970-530-4044 1 www,unitedcivil.com
OVERALL DRAINAGE REPORT
HERITAGE CHRISTIAN ACADEMY UNITED CIVIL
FORT COLLINS, CO Design Group
September 18, 2024
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, Colorado 80521
RE: Heritage Christian Academy Improvements
Fort Collins,Colorado
Project Number:U24018
Dear Staff:
United Civil Design Group, LLC. is pleased to submit this Overall Drainage Report for the Heritage Christian Academy site in
Fort Collins, Colorado. In general, this report serves to document the stormwater impacts associated with future
improvements related to the existing property and the planned site. The site was previously analyzed by Lamp Rynearson
Associates in March 2018. The current condition of the site appears to reflect the design established by Lamp Rynearson
Associates, approved through the Larimer County development review process.The March 2018 Final Drainage Report for
the Industrial Business Park International PUD(referred herein as"The March 2018 Final Drainage Report)is referenced with
this ODP report.
We understand that review by the City of Fort Collins is to assure general compliance with criteria established with the March
2018 Final Drainage Report, and standardized criteria contained in the Fort Collins Stormwater Criteria Manual. This report
was prepared in compliance with technical criteria set forth in the Fort Collins Stormwater Criteria Manual.
If you should have any questions or comments as you review this report, please feel free to contact us at your convenience.
Sincerely,
United Civil Design Group
C,6L-�---k,
Colton Beck, PE
Project Manager
U24018_Drainage Report
OVERALL DRAINAGE REPORT
HERITAGE CHRISTIAN ACADEMY UNITED CIVIL
FORT COLLINS, CO Design Group
TABLE OF CONTENTS
I. General Location and Description......................................................................................................................1
A. Location and Project Description................................................................................................. 1
B. Description of Property................................................................................................................ 2
C. Floodplains................................................................................................................................... 3
II. Drainage Basins and Sub-Basins.........................................................................................................................3
A. Major Basin Description............................................................................................................... 3
B. Sub-Basin Description .................................................................................................................. 3
III. Drainage Design Criteria....................................................................................................................................3
A. Regulations................................................................................................................................... 3
B. Directly Connected Impervious Area (DCIA)................................................................................ 3
C. Hydrological Criteria..................................................................................................................... 4
D. Hydraulic Criteria.......................................................................................................................... 4
E. Modifications of Criteria .............................................................................................................. 4
IV. Drainage Facility Design.....................................................................................................................................4
A. General Concept........................................................................................................................... 4
B. Specific Details............................................................................................................................. 5
V. Erosion Control...................................................................................................................................................7
VI. Conclusions........................................................................................................................................................8
A. Compliance with Standards ......................................................................................................... 8
B. Drainage Concept......................................................................................................................... 8
C. Stormwater Quality...................................................................................................................... 8
VII. References......................................................................................................................................................9
APPENDICES
APPENDIX A—Hydrology Calculations
APPENDIX B—Hydraulic Calculations
B.1 —Low Impact Development Calculations(Reserved for future submittal)
B.2—Water Quality Calculations
B.3—Detention Computations
B.4—Inlet Sizing Calculations(Reserved for future submittal)
B.5—Storm Pipe Calculations (Reserved for future submittal)
B.6—Curb Channel Calculations (Reserved for future submittal)
B.7—Weir Calculations(Reserved for future submittal)
APPENDIX C—Referenced Materials
APPENDIX D—Drainage Plan
I I U24018_Drainage Report
OVERALL DRAINAGE REPORT UNITED CIVIL
HERITAGE CHRISTIAN ACADEMY
FORT COLLINS, CO Design Group
I. GENERAL LOCATION AND DESCRIPTION
A. LOCATION AND PROJECT DESCRIPTION
The Heritage Christian Academy site (referred herein as "the site") exists as a portion of the Industrial Business Park
International PUD, located in the northwest and southwest quarters of Section 8, T7N, R68W of the 6th P.M., City of Fort
Collins, Larimer County, Colorado. The entirety of the property, consisting of approximately 20.1-acres, is located west of
South Timberline Road and east of Mexico Way.The east side of the school property currently exists as a school building with
adjacent parking and athletic field;the west side exists in an overlot graded condition.The future Heritage Christian Academy
site improvements are limited to 13.6-acres of disturbed area west and southwest of the existing school facility.
Dry Creek, the ultimate discharge location for stormwater within the Industrial Business Park International PUD, is located
south of the development. The existing site improvements (i.e., infrastructure east of Munich Way) drain stormwater
primarily to the south by way of surface drainage to drainage swales constructed along International Blvd. Future
improvements (i.e., west of Munich Way) are intended to drain to an existing detention pond (i.e., Pond B) constructed in
2020. Pond B is constructed to release stormwater to an existing drainage Swale system in International Blvd and ultimately
to Dry Creek.
Below is an aerial map depicting the vicinity of the site. Dry Creek exists to the south,and the Timbervine Subdivision borders
the site to the north. Other nearby subdivisions are represented below.
II Ab,
uiiIi i .l l A
i ii
P , �4!!
Site
Pond i
40
FIGURE 1:SITE VICINITY MAP
The site improvements will ultimately include the construction of a new education and athletic facilities with associated
landscaping,walks,and parking lots.This drainage report presents the overall drainage plan for the development. In general,
this report serves to provide an analysis of the drainage impacts associated with the development of site as it relates to
existing and future drainage facilities on-site.The project is currently in the ODP stage; additional design information will be
provided with further site design (i.e., PDP and FDP applications).
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OVERALL DRAINAGE REPORT
HERITAGE CHRISTIAN ACADEMY UNITED CIVIL
FORT COLLINS, CO Design Group
B. DESCRIPTION OF PROPERTY
The property east of Munich Way exists in a fully developed condition.The school facility east of the Munich Way exists with
concrete and asphalt pavement,sidewalks, rooftop,and landscaping. In its existing school facility and associated impervious
areas drain stormwater by means of sheet flow,concrete pans,curb and gutter.The existing site ultimately drains off-site to
drainage swales along International Blvd.
Below are summaries of key components of the school facility in its existing conditions.
Land Use-The site's current land use is commercial/industrial.
Ground Cover-The site exists as a school development with concrete and asphalt pavement,sidewalk, rooftop,and
surrounding grass landscaping.The majority of landscaping is specific to a maintained athletic field.
Existing Topography—The site slopes in a multitude of directions away from the existing on-site building; however,
runoff ultimately drains south down Zurich Drive to a system of drainage swales along International Blvd.
Grades—In general,the existing site is sloped to the east and south at approximately 0.5%to 1.0%.
Soil Type-The USDA's Web Soil Survey shows that the eastern portion of the property consists of both"Type B"and
"Type C"soils, namely Flouvaquents(nearly level)and Loveland Clay Loam (0%to 1%slopes).
Utilities—The following dry utility lines run along the south side of the site: gas, electric, fiber optic. Water mains
and sanitary sewer are also present to the south of the school facility in Zurich Drive.
Drainage Features and Storm Sewer—The eastern portion of the campus is adjacent to the Lake Canal—stormwater
does not appear to be conveyed to this canal. Storm sewer exists at the downstream end of the business park;
however,storm sewer does not exist with the existing school facility.
The property west of Munich Way exists in a partially developed, overlot-graded condition. Apart from the completion of
connecting roadways and underground utilities to support the Industrial Business Park International PUD,the remainder of
the private land remains largely undeveloped.The existing land is currently graded to drain southerly to an existing detention
pond, namely Pond B.
Below are summaries of key components of the western side in its existing conditions.
Land Use-The site's current land use is commercial/industrial.
Ground Cover-The site exists in an overlot grading condition.
Existing Topography—The site generally slopes to the south to an existing detention pond (Pond B).
Grades—In general,the western portion of the site is sloped the south at approximately 0.5%to 2.0%.
Soil Type-The USDA's Web Soil Survey shows that the eastern portion of the property consists of both "Type B"and
"Type C"soils,namely Flouvaquents(nearly level), Loveland Clay Loam(0%to 1%slopes),and Table Mountain Loam
(0%to 1%slopes).The on-site soils provide moderate infiltration and are suitable for development.
Utilities—The following dry utility lines run along the perimeter of the site:gas,electric,cable TV,fiber optic.Water
mains and sanitary sewer are also present in the recently constructed roadways to support the Industrial Business
Park International PUD.
Drainage Features and Storm Sewer—A detention pond (Pond B) exists on-site to support the development of the
school site.This detention pond exists with an outlet structure and outfall system that drains to an existing drainage
Swale in International Blvd.
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OVERALL DRAINAGE REPORT UNITED CIVIL
HERITAGE CHRISTIAN ACADEMY
FORT COLLINS, CO Design Group
C. FLOODPLAINS
The existing site is in the vicinity of the Dry
lam_
Creek Floodplain, which is a FEMA-
designated 100-year floodplain and
floodway. The existing site, being Outside EA OFMINIMALFIL HAZARD
the bounds of the Dry Creek FEMA c
tna eo
floodplain,is located in an area with minimal � � uo;nc t�a
flood risk. The FEMA FIRM Panel # is u ��aw5' 080101
08069CO983H effective 5/2/2012. The
current FEMA FIRM Map is included in the
appendices.
F Amory��i
y'0� 0�Zone AE a't
City�of FAA t Col>>�4,p�
A0ti AFL�OODWAY ,� a
LOMR20-08-0643P Zone AE h
Zone AE �c,a0�
FIGURE 2:FLDDDPLAIN MAP
I I. DRAINAGE BASINS AND SUB-BASINS
A. MAJOR BASIN DESCRIPTION
The existing site is located within the Dry Creek drainage basin. The site drains downstream within the Spring Creek Basin,
while the southern portion of the site drains east, ultimately conveyed to the Cache La Poudre River. No known master
planning improvements are associated with or adjacent to the site.
B. SUB-BASIN DESCRIPTION
A portion of the school property exists within the Industrial Business Park International PUD plans completed by Lamp
Rynearson &Associates. The March 2018 Final Drainage Report, including the associated Drainage Plan, is provided in the
appendices. The project area exists within Basins B1, B2,and B3 of the drainage design.These basins are designed to convey
stormwater to the existing,downstream Pond B within Basin B1.Characteristics of these planned basins are further described
under this cover.
III. DRAINAGE DESIGN CRITERIA
A. REGULATIONS
The design criteria for this study are directly from the City of Fort Collins Storm Drainage Design Criteria and Construction
Standards Manual and the Mile High Flood District Criteria Manuals Volumes 2,and 3 (referred to herein as MHFD).
B. DIRECTLY CONNECTED IMPERVIOUS AREA(DCIA)
The"Four Step Process"that is recommended in Volume 3 of the MHFD in selecting structural BMPs for redeveloping urban
areas. The following portions of this summary describe each step and how it has been utilized for this project:
Step 1—Employ Runoff Reduction Practices
The objective of this step is to reduce runoff peaks and volumes and to employ the technique of"minimizing directly
connected impervious areas" (MDCIA). This project accomplishes this by:
Routing the roof and pavement flows through bioretention facilities and vegetated buffers to increase the time of
concentration, promote infiltration and provide water quality.
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Step 2—Provide Water Quality Capture Volume(WQCV)
The objective of providing WQCV is to reduce the sediment load and other pollutants that exit the site. For this project
WQCV is provided within the existing water quality and detention facility.
Step 3—Stabilize Drainageways
The site is adjacent to Spring Creek and the use of LID will help slow runoff from the site and benefit the stabilization of the
Spring Creek drainageway. In addition,this project will pay stormwater development and stormwater utility fees which the
City uses, in part,to maintain the stability of the City drainageway systems.
Step 4—Consider Need for Site Specific and Source Control BMPs
Site specific and source control BMPs are generally considered for large industrial and commercial sites. The
redevelopment of the existing site will include multiple site specific and source controls, including:
• Dedicated maintenance personnel providing landscape maintenance and snow and ice management.
C. HYDROLOGICAL CRITERIA
City of Fort Collins Rainfall Intensity-Duration-Frequency Curves, provided by Figure RA-16 of the Fort Collins Stormwater
Criteria Manual, are utilized for all hydrologic computations related to the site in its existing/historic and future conditions.
Since this site is relatively small and does not have complex drainage basins,the peak flow rates for design points have been
calculated based on the Rational Method as described in the MHFD and the City of Fort Collins Stormwater Criteria Manual
(FCSCM)with storm duration set equal to the time of concentration for each sub-basin.This method was used to analyze the
developed runoff from the 10-year(minor) and the 100-year(major) storm events.The Rational Method is widely accepted
for drainage design involving small drainage areas(less than 160 acres)and short time of concentrations. Runoff coefficients
are assumed based on impervious area and are given in the Appendices.
D. HYDRAULIC CRITERIA
The developed site will convey runoff to existing design points via swales, concrete pans, and pipes. The City of Fort Collins
Stormwater Criteria Manual (FCSCM)and MHFD are referenced for all hydraulic calculations.
Drainage conveyance facility capacities ultimately proposed with the development project, including an extended detention
pond, shall be designed in accordance with criteria outlined in the FCSCM and/or the Mile High Flood District's Criteria
Manual.
E. MODIFICATIONS OF CRITERIA
The original design of the Industrial Business Park International PUD was completed under design standards per Larimer
County. With the annexation of the property in the City of Fort Collins, the constructed drainage system will be further
analyzed in relation to a new set of standards(i.e.,FCSCM).There are currently no variance requests proposed with the future
stormwater design of the site.
IV. DRAINAGE FACILITY DESIGN
A. GENERAL CONCEPT
Developed runoff will be designed to largely maintain planned drainage patterns.Existing conveyance methods include sheet
flow,concrete pans,curb and gutter,inlets,and storm sewerthat ultimately drain south to Pond B for water quality treatment
and detention storage. Per City standards,water quality and low impact development(LID)will ultimately be proposed with
the project to mitigate the impervious areas that are being modified with the development.
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FORT COLLINS, CO Design Group
B. SPECIFIC DETAILS
Hydrology
Site improvements intend to adhere to the drainage design established by the March 2018 Final Drainage Report and the
FCSCM.The entirety of the school property is to be annexed into the City of Fort Collins,however,the project site is limited
to approximately 14-acres related to the partially developed area of the industrial business park, namely drainage basins B1,
B2,and B3 of the March 2018 Final Drainage Report.The table below summarizes the hydrologic impact associated with the
site improvements relative to the planned conditions provided in the March 2018 Final Drainage Report. Refer to the
Drainage Plan, hydrology calculations,and references attached for additional information.
TABLE 1-HYDROLOGIC SUMMARY
Project Area
Planned Proposed
Overall Area(acre) 13.6 15.3
%Imperviousness 72.0% 72.0%
Composite Cz - 0.75
Composite Cioo - 0.94
A discrepancy in area between the planned basin area and proposed basin area is due to the physical area that drains to the
existing Pond B. Based on existing topography along Zurich Drive and the western side of the school facility, it appears that
more area exists within Basin B than originally assumed.
On-site Basins
The following basins provide drainage delineations for the site in its improved condition. Refer to Appendix A for hydrology
computations and Appendix B for calculations related to Water Quality, Low Impact Development, and other hydraulic
features.
Basin B
Sub-drainage basins 61-133 of the March 2018 Final Drainage Report represent areas where runoff is captured and conveyed
to Pond B. For purposes of this Overall Drainage Report, the mentioned basins are combined into one basin (i.e., Basin B).
This overall basin consists of roofs, concrete and asphalt paving, and landscaping.This basin will be sub-divided into several
basins with future submittals.
Stormwater Quality
Stormwater quality is required to be provided for the new/planned impervious area on the site. The existing Pond B was
designed with 0.48 acre-ft of volume for extended detention purposes—this volume was calculated per MHFD computations
assuming a composite imperviousness of 72.0% and an additional 20%factor for additional capacity. Below is a minimum
required WQCV calculation per the FCSCM.
WQCV=a(0.91i3—1.19i2+0.780 WQCV=Water Quality Capture Volume,watershed inches
WQCV=1.0 x(0.91(0.72)3—1.19(0.72)z+0.78(0.72)) a =1.0 for 40-hr drain times
WQCV=0.28 i = Percent Imperviousness
V=(WQCV)xAx1.2
V=Required WQCV(acre-ft)
V=(°128)x 15.3 x 1.2 A=Tributary catchment area (acres)
V=0.44 acre-ft 1.2=Additional 20%of Required Storage
The original WQCV design of Pond appears to be adequate for City of Fort Collins standards; however,the constructed pond
exists with insufficient volume per the March 2018 Final Drainage Report.The current WQCV capacity is 0.25 acre-ft.To meet
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FORT COLLINS, CO Design Group
requirements per City of Fort Collins, one of the following options, or perhaps a combination of the following options, will
need to be considered with the development of the site:
1) Replace/reconstruct the outlet structure with additional water quality depth.
2) Re-grade the existing pond to generate additional volume.
3) Reduce the required standard WQCV to 50%by implementing LID methods to treat 50%of the site.
4) Reduce the required standard WQCV to 25%by implementing LID methods to treat 75%of the site.
Low Impact Development(LID)
In December of 2015, Fort Collins City Council adopted the revised Low Impact Development (LID) policy and criteria which
requires developments within City limits to meet certain enhanced stormwater treatment requirements in addition to more
standard treatment techniques. The proposed development will be required to meet the newly adopted LID criteria which
requires the following:
- Treat no less than 75%of any newly added impervious area using one or a combination of LID techniques.
- Treat no less than 50%of any newly added impervious area using one or a combination of LID techniques when at
least 25%of any newly added pavement is provided with permeable pavement.
Detention
Detention is required to be provided for the new/planned impervious area on the site. The existing Pond B was designed
with 3.3 acre-ft of required 100-year detention volume;the pond was constructed with a capacity of 4.7 acre-ft.The existing
Pond B was designed assuming a composite imperviousness of 72.0%utilizing the Modified FAA Method.The 100-year release
rate (2.91-cfs) was designed in accordance with criteria established for development within the Dry Creek Basin (i.e., 0.20
cfs/acre).
The nature of the existing detention pond and outlet structure are recognized as design constraints for the school site
improvements; however, modifications to the outlet structure orifice plate may be necessary for 100-year release purposes.
The existing Pond B was designed to detain 13.6-acres of developed area,though it appears that additional developed land
does drain to Pond B. An additional volume of 0.58 acre-ft is anticipated from what was originally assumed (3.3-acre-ft).
Despite this modification to the design of Pond B,the existing pond was constructed with extra capacity up to nearly six acre-
ft.Therefore,provided potential modifications to the 100-year orifice plate,the existing Pond B was sufficiently sized to meet
required detention volume requirements per the FCSCM. Below is a 100-year detention calculation per the FCSCM at a
duration of 120-minutes. Refer to Appendix A and Appendix B for new calculations per FCSCM.
Vi=CIA(60T)
TABLE 2—POND B SUMMARY
Vi=0.94 x 1.84"x 15.29 acres x 60(120min)hr Pond B
Vi=4.36 acre-ft Existing WQCV(ac-ft) 0.25
Required WQCV(ac-ft) 0.44
Vo=Qout(60T)
Vo=2.91cfs x 60(120min) Existing Vim (ac-ft) 3.30
Vo=0.48 acre-ft
Required V1oo (ac-ft) 3.88
Vs=Vi—Vo VMAx (ac-ft) 4.70
Vs=3.88 acre-ft
Bottom of Pond (Elev) 4928.0
To right is a summary of design elements related WQCV(Elev) 4929.6
to existing Pond B. V1oo(EIev) 4932.7
Emergency Spillway(Elev) 4932.7
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FORT COLLINS, CO Design Group
Emergency Spillway
The existing Pond B was designed with a 68-ft long weir, 6-inches in depth, equipped to convey 76.47-cfs. Provided City of
Fort Collins rational calculations, initial runoff computations provided under this ODP Report indicate that the required 100-
year release through the spillway may increase from what was originally calculated in the March 2018 Final Drainage Report.
In the event that a higher total runoff value is conveyed to the existing Pond B, the emergency weir may require
reconstruction.The reconstruction of the emergency spillway may also be necessary based on other design elements with an
improved site.The sufficiency of the previously designed emergency spillway will need to be verified with the development
of the site.
Standard Operating;Procedures(SOPS)
In order for physical stormwater Best Management Practices (BMPs) to be effective, proper maintenance is essential.
Maintenance includes both routinely scheduled activities, as well as non-routine repairs that may be required after large
storms,or as a result of other unforeseen problems. Standard Operating Procedures should clearly identify BMP maintenance
responsibility. BMP maintenance is typically the responsibility of the entity owning the BMP.
Identifying who is responsible for maintenance of BMPs and ensuring that an adequate budget is allocated for maintenance
is critical to the long-term success of BMPs. Maintenance responsibility may be assigned either publicly or privately. For this
project,the privately owned BMPs including grass swales and any installed LID features,are to be maintained by the property
owner.
Storm Sewer
Multiple storm sewers and roof drains will be designed with future site improvements. All storm sewers will be private and
are typically sized to accommodate the flows from the 100-year storm event. Hydraulic computations of these systems will
be provided in Appendix B with future submittals.
Inlets
Multiple inlets will be designed with future site improvements. All proposed storm sewers will be private and are typically
sized to accommodate the flows from the 100-year storm event. Hydraulic computations of these systems will be provided
in Appendix B with future submittals.
v. EROSION CONTROL
Erosion control, both temporary and permanent, is a vital part of any development project. For this project, the site
disturbance is greater than 1 acre; therefore, a CDPHE Stormwater Management Plan (SWMP) will be required.
Comprehensive erosion control measures are included with the site improvements. Refer to the Utility Plans for additional
information. At a minimum,the following temporary BMP's will be installed and maintained to control on-site erosion and
prevent sediment from traveling off-site during construction:
• Silt Fence—a woven synthetic fabric that filters runoff.The silt fence is a temporary barrier that is placed at the base
of a disturbed area.
• Vehicle Tracking Control—a stabilized stone pad located at points of ingress and egress on a construction site.The
stone pad is designed to reduce the amount of mud transported onto public roads by construction traffic.
• Inlet Protection—acts as a sediment filter. It is a temporary BMP and requires proper installation and maintenance
to ensure their performance.
• Straw Wattles — wattles act as a sediment filter in swales around inlets. They are a temporary BMP and require
proper installation and maintenance to ensure their performance.
The contractor shall store all construction materials and equipment and shall provide maintenance and fueling of equipment
in confined areas on-site from which runoff will be contained and filtered. Temporary Best Management Practices (BMP's)
will be inspected by the contractor at a minimum of once every two weeks and after each significant storm event.
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FORT COLLINS, CO Design Group
VI. CONCLUSIONS
A. COMPLIANCE WITH STANDARDS
Storm drainage calculations have followed the guidelines provided by the Mile High Flood District Criteria Manuals Volumes
1, 2 and 3 and the City of Fort Collins Stormwater Criteria Manual., the City of Fort Collins Stormwater Criteria Manual, and
the March 2018 Final Drainage Report.
B. DRAINAGE CONCEPT
To meet City of Fort Collins stormwater criteria,the existing drainage system may require modifications to Pond B.The overall
size and capacity of Pond B was designed and constructed with additional capacity necessary to meet City of Fort Collins
requirements; however, several design features related to both water quality and detention with require verification with
future improvements.
C. STORMWATER QUALITY
Multiple long-term stormwater quality measures will be necessary on-site to provide treatment of stormwater prior to it
being discharged from the site. For this site this includes extended detention and will ultimately include LID techniques
throughout the site.
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FORT COLLINS, CO Design Group
VII. REFERENCES
1. City of Fort Collins Stormwater Criteria Manual,City of Fort Collins,Colorado, December 2018.
2. Mile High Flood District Criteria Manual Volume 1 and 2, Mile High Flood District, Denver, Colorado,January 2016.
3. Final Drainage Report, Lamp Rynearson &Associates, Fort Collins,Colorado, March 2018.
4. Natural Resources Conservation Service Web Soil Survey at:websoilsurvey.nres.usda.gov/app
5. Flood Insurance Rate Map, FEMA, Panel 08069C0983H, https://hazards.fema.gov/femaportal/
6. Stormwater Discharges Associated with Construction Activity,Stormwater Management Plan Preparation Guides,State
of Colorado,www.colorado.com
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APPENDIX A
HYDROLOGY CALCULATIONS
RUNOFF COEFFICIENTS AND%IMPERVIOUS UNITED CIVIL
Heritage Christian Academy,Fort Collins,CO
6
11 1,111111
Basin Design Pt. Areas Composite m osite Runoff Coefficient
Total Total Roof ly Asphalt 8 Recycled Gravel G Lawns(l) Imperviousness C2 Clog
Concretely Asphalt"' Pavers(I)
%I=90% %1=100% %1=80% %1=40% %1=2% (°/al)
C=0.95 C=0.95 C=0.80 C=0.50 C=0.25
acres sf sf sf sf sf sf
31 81 5.91 90.0% 0.74 0.8S
B2 82 4.27 80.0% 0.64 0.80
B3 63 4.39 40.0% 0.29 0.61
Total 81 1 14.571 72.0%
Proposed
Basin Design Pt. Areas Composite m osite Runoff Coefficient
Total Total Roof Asphalt B Recycled Gravel G Lawns(l) Imperviousness C2 Clog
Concretely Asphalt(') Pavers(I)
acres %I=90% %1=100% %I=80% %1=40% %1=2% M)
C=0.95 C=0.95 ME C=0.50 C=0.25
sf sf sf sf sf sf
B B 15.29 665,977 72.0% 0.75 0.94
Notes:
(1) Recommended%Imperviousness Values per Table 4.1-3 Surface Type-Percent Impervious in Fort Collins Stormwater Criteria Manual
(2) Runoff C is based Table 3.2-2.Surface Type-Runoff Coefficients and Table 3.2-3.Frequency Adjustment Factors in Fort Collins Stormwater Manual
(3)the"Total'basin is an analysis of the routed onsite flows.
Date:9/5/2024 C:(United Civil Dropboxt Projectsi U24018-Heritage Christian AcademyiReportstDrainagetCalculationst Hydrology-Fort Collins
TIME OF CONCENTRATION(Y-YR) UNITED CIVIL
Heritage Christian Academy,Fort Collins,CD 7 Design Group
I 1
Basin Llesign Pt. Area Overland Flow (T) Travel/Channelized Time of Flow(T)
CA(') Length Slope T121 Slope Length n R Velocity i3i TIia1 T,+Tt Tc_") FinalT�lsl
acres ft % min % ft fps min min min min
B1 Bl 5.91 13.0
B2 B2 4.27 13.9
B 3 83 4.39 28.1
Proposed Basins
Basin Uesign t. rea Overland Flaw (T.) Travel/Channelized Time of Flow(T)
CXCFig Length Slope T;(') Slope Length a R Velocityi3i T,"i T;+Tc To_(') Fina[T�Isi
acres ft % min % ft fps min min min mfn
B B 15.29 0.75 250 2.0% 37.7 0.5% 935 0.016 0.2 2.3 6.9 44.6 15.2 15.2
Notes:
WC=CX*CF is less than or equal to 1.0(Cf=1.0)
(2)t;=[1.87(1.1-CXCF)L1121
/S113,S=slope in%,L=length of overland flow(200'max urban,500'max rural)
M V=(1.49/n)RZ"5",5=slope in ft/ft,FC5CM Equation 5-4
(4)t,=L/(V*60 sec/min)
1si Maximum t,=total length/180+10
Minimum t,=5 min
Date:9/5/2024. C:(United Civil DropboxlProjects(U24018-Heritage Christian AcademytReports)DrainagelCalculationslHydrology-Fort Collins
TIME OF CONCENTRATION(10-YR) UNITED CIVIL
Heritage Christian Academy,Fort Collins,CO Design Group
7131
Design t. Area Overland Flow (T,) Travel/Channelized Time of Flow(T,)
C'CFgI Length Slope Tis) Slope Length n R Velocity(3) T(4) Ti+Tt T_,15) Fi O,"'
acres ft % min % ft fps min min min min
5.91 13.0
B2 82 4.27 13.9
B3 B3 1 4.39 1 1 28.1
.
Basin Design t. rea Overland Flow (T) Travel/Channelized Time of Flow(T)
CzCF(o Length Slope T(2) Slope Length n R Veloeity(3) T(4) T,+T, T,ma,") FinalT,lsi
acres ft % min % ft fps min min min min
B B 15.29 1 0.75 250 2.0% 37.7 0.5% 935 0.016 0.2 2.3 6.9 44.6 15.2 15.2
Notes:
(i)C=Cx*C,is less than or equal to 1.0(Cf=1.0)
Izl t,_[1.87(1.1-CxC,)Ll2l/S113 S=slope in%,L=length of overland flow(200'max urban,500'max rural)
(3)V=(1.49/n)R2115112,S=slope in ft/ft,FCSCM Equation 5-4
(4)tt=L/(V*60 sec/min)
isl Maximum t,=total length/180+10
i6lMinimum tc=5 min
Date:9/5/2024. C:)United Civil Dropbox)Projects(U24018-Heritage Christian Academy�Reports)Orainage)Calculatlons)Hydrology-Fort Collins
TIME OF CONCENTRATION(100-YR) UNITED CIVIL
Heritage Christian Academy,Fort Collins,CD Design Group
I :
Basin esign t. rea Overland Flow (T) Travel/Channelized Time of Flow(T,)
WF(n Length Slope T,(2) Slope Length n R Velocity(3) Tl(a) T;+Tc Tc_") FinalT'(s)
acres ft % min % ft fps min min min min
B1 Bl 5.91 13.0
B2 B2 4.27 13.9
B3 B3 4.39 28.1
' 1 I
Basin Uesign Pt. Area Overland Flow (T) Travel/Channelized Time of Flow(T)
�WF(o Length Slope Tls) Slope Length n R Velocity(3) Tl(a) Ti-Tt T,.,.") FinalT,(s)
acres h % min % ft fps min min min min
B B 15.29 1 1.00 250 2.0% 10.8 0.5% 935 0.016 0.2 2.3 6.9 17.7 15.2 15.2
Notes:
i'IC=CX*CF is less than or equal to 1.0(Cf=1.25)
(2)t,=[1.87(1.1-CxCF)L"2l/S'i',S=slope in%,L=length of overland flow(200'max urban,500'max rural)
)')V=(1.49/n)R2/3S1/2,S=slope in ft/ft,FCSCM Equation 5-4
0)t,=L/(V*60 sec/min)
)51 Maximum tc=total length/180+10
(6)Minimum t,=5 min
Date:9/5/2024. C:(United Civil DropboxlProjects(U24018-Heritage Christian AcademylReportsl DrainagelCalculationslHydrology-Fort Collins
RATIONAL METHOD PEAK RUNOFF }�� UNITED CIVIL
Heritage Christian Academy,Fort Collins,CO �"c� Design Group
Basin Design Pt. Contributing Area 2-Year IDD-Year Runoff Coefficients Rainfall Intensity Peak Discharge
Basins acre t, 4 C2 CID Ciao 12 Im lion 02 Ro Roo
min min in/hr in/hr fn/hr cis cfs cfs
Ell Bl Bl 5.91 13 13 0.74 0.74 0.85 1.98 3.39 6.92 8.66 14.83 34.76
82 32 32 4.27 14 14 0.64 0.64 0.80 1.92 3.29 6.71 5.25 8.99 22.92
83 133 1133 1 4.39 28 28 1 0.29 0.29 0.61 1 1.34 2.29 4.69 1 1.71 2.92 12.56
Prnposed Basins
Basin Design Pt. Contributing Area 2-Year IDD-Year Runoff Coefficients Rainfall Intensity Peak Discharge
Basins acre it, t, C2 CID Ciao 12 Im lino 92 Din Dino
min min fn/hr in/hr fn/hr cfs cfs cfs
B B B 15.29 15 15 0.75 0.75 0.94 1.87 3.19 6.52 21.44 36.57 93.43
Date:9/5/2024 C:I United Civil Dropboxl Projectst U24018-Heritage Christian Academyt Reports)DrainogetCalculationst Hydrology-Fort Collins
APPENDIX B
HYORAl1LIC CALCULATIONS
WATER QUALITY }�� UNITED CIVIL
Heritage Christian Academy,Fort Collins,CO �"c� Design Group
Required Water guality CaptureVolume
Basin Area Area Imperviousness Watershed WBCV WQ Treatment
(sf) (acres) M (inches) (cf) Method
B 665,977 15.29 72% 0.28 18,929 Extended Detention
Water quality by way of extended detetion provided based on 40-hour storage
Date:9/12/2024 C.,t United Civil Dropboxt Prcjectst U24018-Heritage Christian Academyt ReportstDrainogetCalculationst Hydrology-Fort Collins
DETENTION POND VOLUME(FAA Method) UNITED CIVIL
Heritage Christian Academy,Fort Collins,CO 74.1 Design Group
POND 1 Pond Al
100 Year Storm Into Detention Facility
Area = 665,977 squarefeet
Area = 15.29 acres
C 2 = 0.75
Cioo = 0.94
Release Rate Out of Pond
Q-T = 2.91 cis
Notes:
1. Pond area includes all of Basin B.
2.Cioo value shown is a weighted average of the C values per City of Fort Collins criteria.
3.Release rate per the march 2018 Final Drainage Report,tamp Rynearson&Associates
Detention Volume Calculations
Rainfall Rainfall Inflow Rate Inflow Volume Adjustment Average Outflow Volume Required
Duration(T) Intensity(1) Q,,ECioo*Area*l V;=(Ci,„*T*60) Factor Outflow Rate Vo Qa„*T*60 Storage Volume
m=0.5(1+TJT) Q,,,=m*qa,,, V,=V,-Vo
min in/hr cfs ft3 Is jt3 jt3
5 9.95 142.6 42,773 1.00 2.91 �8.73 411,•900
10 7.72 110.6 66,374 1.00 2.91 1,746 64,628
15 6.52 93.4 84,085 1.00 2.91 2,619 81,466
20 5.60 80.2 96,293 1.00 2.91 3,492 92,801
25 4.98 71.4 107,040 1.00 2.91 4,365 102,675
30 4.52 64.8 116,584 1.00 2.91 5,238 111,346
35 4.08 58.5 122,774 1.00 2.91 6,111 116,663
40 3.74 53.6 128.,620 1.00 2.91 6,984 121,636
45 3.46 49.6 133,865 1.00 2.91 7,857 126,008
50 3.23 46.3 138,852 1.00 2.91 8,730 130,122
55 3.03 43.4 143,279 1.00 2.91 9,603 133,676
60 2.86 41.0 147,535 1.00 2.91 10,476 137,059
70 2.59 37.1 155,875 1.00 2.91 12,222 143,653
80 2.38 34.1 163,699 1.00 2.91 13,968 149,731
90 2.21 31.7 171,007 1.00 2.91 15,714 155,293
100 2.06 29.5 177,111 1.00 2.91 17,460 159,651
110 1.94 27.8 183,473 1.00 2.91 19,206 164,267
120 1,84 26.4 189,835 1.00 2.91 20,952 168,883
Required Detention Volume
V 100 = 168,883 cubic feet
V 100 = 3.88 acre-ft
V MAx = 4.70 acre-ft
Date:9/16/2024 Ca United Civil Dropboxl Projects)U24018-Heritage Christian Academy)Reports)Drainagel Colculationsl Hydrology-Fort Collins
APPENDIX C
REFERENCED MATERIALS
National Flood Hazard Layer FIRMette 1#FEMA Legend
105°2'27"W 40°35'35"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
�• Without Base Flood Elevation(BFE)
.f11 •'r •S; Zone A.V.A99
1 SPECIAL FLOOD
With BFE or Depth zone AE.AO.AH.VE,AR
•'; ( 1 HAZARD AREAS Regulatory Floodway
w • _ ,i ;
. . 0.2%Annual Chance Flood Hazard,Areas
! low; • " It� `• of 1%annual chance flood with average
• ' ' depth less than one foot or with drainage
z � ^� � e areas of less than one square mile Zonex
-
® Future Conditions 1%Annual
OIL _ • •/; r' • ` I ®� Chance Flood Hazard zone x
dr
9,5A�jF r'�r� * •r;�� t Area with Reduced Flood Risk due to
a j r Levee.See Notes.zone x
yy OTHER AREAS OF
FLOOD HAZARD Area with Flood Risk due to Levee zone 0
• A J1
•
� �3 NO SCREEN Area of Minimal Flood Hazard zonex
�„ • Q Effective LOMRs
% OTHER AREAS Area of Undetermined Flood Hazard zone D
' GENERAL -—-- Channel,Culvert,or Storm Sewer
AREA OF MINIMAL F LOOD HAZARD STRUCTURES IIIIIII Levee,Dike,or Floodwall
Zon .
Cross Sections with 1%Annual Chance
17a5 Water Surface Elevation
-
- - Coastal Transect
Unincorporated Areas —513^"' Base Flood Elevation Line(BFE)
�v,aw s
O 080101 • Limit of Study
6. _ Jurisdiction Boundary
Coastal Transect Baseline
OTHER _ Profile Baseline
.�•�ao>`ti ,�� FEATURES Hydrographic Feature
p p � •
�A�' � i Digital Data Available
,r\ � -+• . 1� No Digital Data Available !
MAP PANELS Unmapped V'
0' 0 The pin displayed on the map is an approximate
I t Collins ,��� Zone tic 1 `• anlnt authoritative property location.by the user and es not represent
C>lty�of�F,�.c Co �, � �
OSO 10 i�� ��♦��°
!� 1 -one AE This map complies with FEMA's standards for the use of
.L0 pC ` digital flood maps if it is not void as described below.
FL
Ol 4 \, The basemap shown complies with FEMA's basemap
OODWAY ♦ accuracy standards
LOMR 20_OS 0643P Zor+ieYAE tip. 7 The flood hazard information is derived directly from the
eff i 6451 authoritative NFHL web services provided by FEMA.This map
was exported on 7/24/2024 at 11:03 AM and does not
Zone AE �•�<<f�((~ reflect changes or amendments subsequent to this date and
time.The NFHL and effective information may change or
become superseded by new data over time.
This map image is void if the one or more of the following map
elements do not appear:basemap imagery,flood zone labels,
AML �� �� legend,scale bar,map creation date,community identifiers,
105°1'S0"W 40°35'8"N FIRM panel number,and FIRM effective date.Map images for
Feet 1:6 000 unmapped and unmodernized areas cannot be used for
0 250 500 1,000 1,500 2,000 regulatory purposes.
Basemap Imagery Source:USGS National Map 2023
—
0000"
LAMP RYN r
L.
A,sOCIAT _
OR R�Wmj I 1- n ,' _.
March 2018
Final Drainage Report
Industrial Business Park International PUD
Lots 5-9 and Envelopes B, C, & D Amended Plat
Larimer County, Colorado
Prepared for:
Hartford Homes, LLC
4801 Goodman Road
Timnath, CO 80547
ProJectl! l"�'llt►J0373� �
Project No. 0218008.01 RevlewedByEnglneering
Reviewed By Planning;
Approved By z'
Date Z
JI B
LAMP RYNEARSON Leaving a Legacy of
& ASSOCIATES
ENGINEERS I SURVEYORS I PLANNERS Enduring Improvements to
4715 Innovation Dnve, Suile 100 Our Communities
Fort Collins Colorado 80525
IF] 970 226 0342 Lamp Rynearson Purpose Statement
IF] 970 226 0879
,,,,LRA-Inc com
Copyright Lamp, Rynearson & Associates, Inc., 2018. All rights reserved.
Appendices
Appendix A
1. Vicinity Map
2. Developed Conditions Drainage Plan
3. Dry Creek Basin Stormwater Master Plan
Appendix B
1. Soils Data
2. Floodplain Information
3. Excerpts from Reference Materials
Appendix C
1. Rational Method Calculations
2. Street Capacity Calculations
3. Swale/Weir/Chase Calculations
4. Detention Pond Calculations
FINAL DRAINAGE REPORT
INDUSTRIAL BUSINESS PARK INTERNATIONAL PUD
LOTS 5-9 AND ENVELOPES B, C, & D AMENDED PLAT
LARIMER COUNTY, COLORADO
I. Introduction
This drainage report contains the details for the overall drainage design for the Industrial
Business Park International PUD Lots 5-9 and Envelopes B, C, & D Amended Plat site. The
i report also includes information on the historic drainage patterns for the site and outlines the
previous drainage design information provided in the "Final Drainage Report for Timbervine"
prepared by Galloway in July 2014. Final drainage design information for the proposed site
considers the previous drainage design, the developed site draining to the proposed detention
ponds located along the southern edge of the site, and ultimately discharging to Dry Creek to
the south.
A. Site Location
The project site is located south of the northwest quarter of Section 8, Township 7 North, Range
68 West of the 6th P.M., northeast of Fort Collins, Larimer County, Colorado. More specifically,
the site is situated north of International Boulevard, west of Munich Way, and south of the
Timbervine subdivision. Dry Creek is located south of the site. There are residential
developments along the north and west, with commercial users east of the site. Mexico Way
divides the site into two areas, east and west of the roadway. Refer to Appendix A for a vicinity
map.
B. Property Description
The project site is approximately 27.5 acres of mostly undeveloped land. Historically, the
property has been used as open space. In general,the site slopes from north to south, at slopes
ranging from about 0.4% to 5%.
According to the NRCS website, the site consists of predominantly Type B soils with some Type
C and D soils. According to the NRCS, the Type B soils are classified as Fluvaquents and
sandy loam types while the Type C and D soils are Loveland clay loam and Caruso clay loam,
respectively. The soils description provided in the"Preliminary Soils& Geological Investigation"
prepared by Empire Laboratories, Inc., consists of silty topsoil and/or vegetation underlain by
silty clay and sandy silty clay. See Appendix B for soils data.
The proposed development will contain 10 commercial lots with associated roadways,
walkways, utilities and two detention ponds. The runoff from the site flows to the proposed
detention ponds in the southwest and southeast of the site before discharging offsite into the
median swale along International Boulevard, and then into Dry Creek.
II. Regulations/Design Criteria
The Larimer County Stormwater Design Standards (County Standards), City of Fort Collins
Stormwater Criteria Manual (City Manual), and Urban Drainage and Flood Control District Urban
Storm Drainage Criteria Manual (USDCM), as well as good engineering practices, have been
Copyright Lamp, Rynearson&Associates, Inc.,2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 1
Lots 5-9 and Envelopes B, C,&D Amended Plat
Project No. 0218008.01
I
used to calculate the stormwater runoff and design the stormwater facilities for this site (see
Appendix B for excerpts from reference documents).
A. Hydrologic Criteria
The 2-year(minor)and 100-year(major) design storms were used for the developed discharge,
as indicated in the County Standards. The City of Fort Collins Intensity-Duration-Frequency
curves were used to obtain rainfall data for each storm specified. Because the site is less than
160 acres,the Rational Method was used to calculate developed stormwater runoff. Impervious
values for each basin were assumed based on commercial land use per Table RO-14 in the
City Manual. Runoff coefficient"C" values were taken from Table RO-10 of the City Manual.
B. Hydraulic Criteria
The stormwater structures were designed using techniques developed or adopted by the
Larimer County and/or City of Fort Collins. The stormwater conveyance systems were designed
to capture and convey the minor and major events. The allowable street capacity for the major
event will be based on a maximum depth of 18 inches from the flowline of the street. The
allowable street capacity for the minor event will be based on a maximum depth that will not
allow the stormwater to overtop the curb. Street capacities were analyzed using the Bentley
FlowMaster V8i program. Water quality capture volume (WQCV), the 100-year storm volumes
and outlet/spillway designs were done using the UDFCD's UD-Detention v2.34 spreadsheet
program. The results of the detailed calculations are provided in Appendix C.
III. Historic Drainage
A. Major Basin Description
The site is located in the Dry Creek Basin as illustrated in the City of Fort Collins Stormwater
Master Plan (see Appendix A). Historically, drainage from the site traveled overland to
International Blvd. via the drainage way on the west side of the site,then into the existing median
detention pond. The median detention pond then releases directly to the Dry Creek. According
to the Flood Insurance Rate Map (FIRM)for Larimer County, Colorado, Panel No. 983 of 1420,
Map No. 08069CO983H with an effective date of May 2, 2012, the proposed development is
located entirely outside the special flood hazard boundary for Dry Creek (see Appendix B).
IV. Proposed Drainage Design
The site has been divided into sub-basins, each representing a specific discharge point for the
site. Two detention ponds, Pond A and Pond B, are proposed along the south side of the
property that receive runoff from both onsite and offsite areas. The goal of the proposed
drainage design is to capture the 100-year stormwater volume in addition to water quality
i volume in the ponds and discharge the allowable release rate of 0.2 cfs per acre of developed
land offsite per the Dry Creek Basin Stormwater Master Plan.
The onsite and offsite sub-basins for the proposed development were determined and routed
to establish key stormwater discharge points within the development. Runoff values were
calculated using the Rational Method (see information provided in Appendix C). The
imperviousness is determined to be 80 percent for a commercial site based on Table RO-14 in
the City's Stormwater Criteria Manual. The runoff coefficients corresponding to the percent
imperviousness was obtained from the UDFCD's UD-Rational spreadsheet.
Copyright Lamp, Rynearson&Associates, Inc.,2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 2
Lots 5-9 and Envelopes B,C, &D Amended Plat
Project No. 021800B.01
A hydraulic analysis was completed based on calculated discharges to determine the sizes of
the proposed drainage structures. Detailed design of hydraulic structures, including the
detention pond outlet structures, has been provided in Appendix D.
A. Proposed Basin Descriptions
BASIN A
The"A" basins are situated on the west side of Mexico Way and contain a little less than half of
the site draining to Pond A. All "A" basins are assumed to have commercial land use, other
than the detention pond basin.
Basin Al is located northwest of the site and drainage from this basin directly sheet flows into
Zurich Drive. A mid-block cross pan is proposed at the street low point, flowing to the south
side of Zurich Drive with a sidewalk chase proposed to allow minor storm flows to pass under
the sidewalk without any overtopping. Major storm flows will weir over the sidewalk chase and
be captured by an open channel to the south. Runoff from Basin Al will discharge to the Swale
A at DP1, and then into Pond A.
Basin A2 is situated on the west side of the site and drainage from Basin A2 sheet flows directly
into Pond A.
Basin A3 is located south of the site along the International Boulevard and runoff from this basin
sheet flows into Pond A or a proposed swale along the south of the basin, then into Pond A at
DP 3. All flows from the "A" basins are routed to the Pond A outlet structure at the southeast
corner of the pond.
BASIN B
The"B" basins are located on the east side of Mexico Way and contain a little more than half of
the site draining to Pond B. All "B"basins are also assumed to have commercial land use, other
than the detention pond basin.
Basin B1 is located northeast of the site and drainage sheet flows directly into Zurich Drive. A
mid-block cross pan is proposed at the street low point, flowing to the south side of Zurich Drive
with a sidewalk chase proposed at DP 4. Minor storm flows will pass under the sidewalk without
any overtopping. Major storm flows will weir over the sidewalk chase and be captured by an
open channel to the south, and then into Pond B.
Basin B2 covers the middle of the eastern portion of the site and runoff from this basin sheet
flows into the proposed channel in the middle of the basin, draining from north to south, and
flowing into Pond B at DP 5.
Basin B3 is situated at the southeast corner of the site and drainage sheet flows directly into
i Pond B. All flows from the"B" basins are routed to the Pond B outlet structure at the southwest
corner of the pond.
Copyright Lamp, Rynearson&Associates, Inc.,2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 3
Lots 5-9 and Envelopes B, C,&D Amended Plat
Project No.0218008.01
i
FINAL DRAINAGE REPORT
INDUSTRIAL BUSINESS PARK INTERNATIONAL PUD
LOTS 5-9 AND ENVELOPES B, C, & D AMENDED PLAT
LARIMER COUNTY, COLORADO
I. Introduction
This drainage report contains the details for the overall drainage design for the Industrial
Business Park International PUD Lots 5-9 and Envelopes B, C, & D Amended Plat site. The
report also includes information on the historic drainage patterns for the site and outlines the
previous drainage design information provided in the "Final Drainage Report for Timbervine"
prepared by Galloway in July 2014. Final drainage design information for the proposed site
considers the previous drainage design, the developed site draining to the proposed detention
ponds located along the southern edge of the site, and ultimately discharging to Dry Creek to
the south.
A. Site Location
The project site is located south of the northwest quarter of Section 8,Township 7 North, Range
68 West of the 6th P.M., northeast of Fort Collins, Larimer County, Colorado. More specifically,
the site is situated north of International Boulevard, west of Munich Way, and south of the
Timbervine subdivision. Dry Creek is located south of the site. There are residential
developments along the north and west, with commercial users east of the site. Mexico Way
divides the site into two areas, east and west of the roadway. Refer to Appendix A for a vicinity
map.
B. Property Description
The project site is approximately 27.5 acres of mostly undeveloped land. Historically, the
property has been used as open space. In general,the site slopes from north to south, at slopes
ranging from about 0.4% to 5%.
According to the NRCS website, the site consists of predominantly Type B soils with some Type
C and D soils. According to the NRCS, the Type B soils are classified as Fluvaquents and
sandy loam types while the Type C and D soils are Loveland clay loam and Caruso clay loam,
respectively. The soils description provided in the"Preliminary Soils&Geological Investigation"
prepared by Empire Laboratories, Inc., consists of silty topsoil and/or vegetation underlain by
silty clay and sandy silty clay. See Appendix B for soils data.
The proposed development will contain 10 commercial lots with associated roadways,
walkways, utilities and two detention ponds. The runoff from the site flows to the proposed
detention ponds in the southwest and southeast of the site before discharging offsite into the
median swale along International Boulevard, and then into Dry Creek.
II. Regulations/Design Criteria
The Larimer County Stormwater Design Standards (County Standards), City of Fort Collins
Stormwater Criteria Manual (City Manual),and Urban Drainage and Flood Control District Urban
Storm Drainage Criteria Manual (USDCM), as well as good engineering practices, have been
_ Copyright Lamp, Rynearson &Associates, Inc., 2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 1
Lots 5-9 and Envelopes B, C,&D Amended Plat
Project No.0218008.01
i
used to calculate the stormwater runoff and design the stormwater facilities for this site (see
Appendix B for excerpts from reference documents).
A. Hydrologic Criteria
The 2-year(minor)and 100-year(major)design storms were used for the developed discharge,
as indicated in the County Standards. The City of Fort Collins Intensity-Duration-Frequency
curves were used to obtain rainfall data for each storm specified. Because the site is less than
160 acres,the Rational Method was used to calculate developed stormwater runoff. Impervious
values for each basin were assumed based on commercial land use per Table RO-14 in the
City Manual. Runoff coefficient"C" values were taken from Table RO-10 of the City Manual.
B. Hydraulic Criteria
The stormwater structures were designed using techniques developed or adopted by the
Larimer County and/or City of Fort Collins. The stormwater conveyance systems were designed
to capture and convey the minor and major events. The allowable street capacity for the major
event will be based on a maximum depth of 18 inches from the flowline of the street. The
allowable street capacity for the minor event will be based on a maximum depth that will not
allow the stormwater to overtop the curb. Street capacities were analyzed using the Bentley
FlowMaster V8i program. Water quality capture volume (WQCV), the 100-year storm volumes
and outlet/spillway designs were done using the UDFCD's UD-Detention v2.34 spreadsheet
program. The results of the detailed calculations are provided in Appendix C.
III. Historic Drainage
A. Major Basin Description
The site is located in the Dry Creek Basin as illustrated in the City of Fort Collins Stormwater
Master Plan (see Appendix A). Historically, drainage from the site traveled overland to
International Blvd. via the drainage way on the west side of the site,then into the existing median
detention pond. The median detention pond then releases directly to the Dry Creek. According
to the Flood Insurance Rate Map (FIRM)for Larimer County, Colorado, Panel No. 983 of 1420,
Map No. 08069C0983H with an effective date of May 2, 2012, the proposed development is
located entirely outside the special flood hazard boundary for Dry Creek (see Appendix B).
IV. Proposed Drainage Design
The site has been divided into sub-basins, each representing a specific discharge point for the
site. Two detention ponds, Pond A and Pond B, are proposed along the south side of the
property that receive runoff from both onsite and offsite areas. The goal of the proposed
drainage design is to capture the 100-year stormwater volume in addition to water quality
volume in the ponds and discharge the allowable release rate of 0.2 cfs per acre of developed
land offsite per the Dry Creek Basin Stormwater Master Plan.
The onsite and offsite sub-basins for the proposed development were determined and routed
to establish key stormwater discharge points within the development. Runoff values were
calculated using the Rational Method (see information provided in Appendix C). The
imperviousness is determined to be 80 percent for a commercial site based on Table RO-14 in
the City's Stormwater Criteria Manual. The runoff coefficients corresponding to the percent
imperviousness was obtained from the UDFCD's UD-Rational spreadsheet.
Copyright Lamp, Rynearson&Associates, Inc., 2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 2
Lots 5-9 and Envelopes B, C, &D Amended Plat
Project No.0218008.01
A hydraulic analysis was completed based on calculated discharges to determine the sizes of
the proposed drainage structures. Detailed design of hydraulic structures, including the
detention pond outlet structures, has been provided in Appendix D.
A. Proposed Basin Descriptions
BASIN A
The "A" basins are situated on the west side of Mexico Way and contain a little less than half of
the site draining to Pond A. All "A" basins are assumed to have commercial land use, other
than the detention pond basin.
Basin Al is located northwest of the site and drainage from this basin directly sheet flows into
Zurich Drive. A mid-block cross pan is proposed at the street low point, flowing to the south
side of Zurich Drive with a sidewalk chase proposed to allow minor storm flows to pass under
the sidewalk without any overtopping. Major storm flows will weir over the sidewalk chase and
be captured by an open channel to the south. Runoff from Basin Al will discharge to the Swale
A at DPI, and then into Pond A.
Basin A2 is situated on the west side of the site and drainage from Basin A2 sheet flows directly
into Pond A.
Basin A3 is located south of the site along the International Boulevard and runoff from this basin
sheet flows into Pond A or a proposed Swale along the south of the basin, then into Pond A at
DP 3. All flows from the "A" basins are routed to the Pond A outlet structure at the southeast
corner of the pond.
BASIN B
The "B" basins are located on the east side of Mexico Way and contain a little more than half of
the site draining to Pond B. All "B" basins are also assumed to have commercial land use, other
than the detention pond basin.
Basin B1 is located northeast of the site and drainage sheet flows directly into Zurich Drive. A
mid-block cross pan is proposed at the street low point, flowing to the south side of Zurich Drive
with a sidewalk chase proposed at DP 4. Minor storm flows will pass under the sidewalk without
any overtopping. Major storm flows will weir over the sidewalk chase and be captured by an
open channel to the south, and then into Pond B.
Basin B2 covers the middle of the eastern portion of the site and runoff from this basin sheet
flows into the proposed channel in the middle of the basin, draining from north to south, and
flowing into Pond B at DP 5.
Basin B3 is situated at the southeast corner of the site and drainage sheet flows directly into
Pond B. All flows from the "B" basins are routed to the Pond B outlet structure at the southwest
corner of the pond.
Copyright Lamp, Rynearson &Associates, Inc., 2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 3
Lots 5-9 and Envelopes B, C, &D Amended Plat
Project No.0218008.01
BASINS DRAINING DIRECTLY OFFSITE
Basin 01 is a small onsite basin that cannot be routed to the onsite detention ponds due to
previous designs for the Timbervine development to the north at DP 7. The flow from this basin
is captured and accounted for in the Timbervine detention pond.
B. Rational Method Calculations
The runoff from proposed basins were calculated using the Rational Method as they are smaller
than 160 acres per Larimer County Stormwater Design Standards. The Rational Method values
were used for the sizing of channels, sidewalk chases and street capacity calculations. The 2-
year and 100-year criteria were used for the minor and major storm events. The results of the
Rational Method analysis for the developed conditions are shown in Table 1 below (see
Appendix C for detailed rational method calculations):
Table 1 - Rational Method Calculations Summary for Developed Conditions
Percent
Basin Area acres Impervious Q2 cfs Q100 cfs
Al 3.94 90% 7.08 28.24
A2 3.39 2% 0.04 7.23
A3 4.05 80% 5.15 22.29
131 5.91 90% 8.71 34.92
B2 4.27 80% 5.30 22.93
B3 4.39 40% 1.68 12.53
01 0.21 90% 0.43 1.72
C. Stormwater Conveyance Design
Street mid-block cross pans, sidewalk chases and swales are proposed to convey stormwater
runoff through the site into the detention ponds located along the south side of the property.
Streets are designed to handle the minor storm (2-year storm) flows without overtopping the
curbs and the major storm (100-year storm)flows with a maximum allowable depth of 6 inches
above the street crown, meeting or exceeding the City and County stormwater criteria. Peak
flows at specific design points were calculated by directly adding the basin flows at design points
without any routing, and the results are shown in Table 2 below.
Table 2-Summary of Peak Flows at Design Points
Design Q2 (cfs) Q100 (cfs) Design Q2 (cfs) Q100 (cfs)
Point Point
I 7.08 28.24 5 14.01 57.85
2 12.27 57.76 6 15.69 70.38
3 5.15 22.29 7 0.43 1.72
4 8.71 34.92
D. Stormwater Quality and Detention Ponds
Stormwater quality will be mitigated onsite during construction with the use of sediment control
logs, vehicle tracking devices and inlet/outlet protection devices. Long-term stormwater quality
will occur by routing the onsite drainage through grass buffers and vegetated swales located
Copyright Lamp, Rynearson&Associates, Inc., 2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 4
Lots 5-9 and Envelopes B, C,R D Amended Plat
Project No. 0218008.01
i
within open areas. Additional treatment will occur by routing the majority of the runoff into two
onsite detention ponds and releasing it at an attenuated rate over an extended period of time.
The outlet structures for the ponds have been designed to account for 40-hour water quality
capture volumes with 100-year outlets, and emergency spillways draining the uncontrolled 100-
year flows through the ponds in a safe manner. The ponds were sized using the UD-Detention
v2.34 Spreadsheet. The calculations for the detention ponds and spillways along with pond
stage-volume information are included in Appendix C. Table 3 below provides a summary of
the detention pond parameters. As shown in the below table, with higher spillway crest
elevations, both ponds have enough capacity to detain more than the 100-year storm plus
WQCV.
Table 3 — Parameters for Detention Ponds
I �
Parameter Pond A Pond B
WQCV ac-ft 0.317 0.479
Water Surface Elevation at WQCV ft 4927.43 4926.60
Water Surface Elevation at 100- r Storm +WQCV ft 4929.14 4928.67
Storage Volume for 100- r Storm +WQCV ac-ft 2.32 3.30
Storage Capacity at Emergency Spillway ac-ft 3.76 6.07
Minimum Freeboard ft 1.0 1.0
Minimum Effective Pond Elevation 4927.0 4925.0
Outlet Pipe Diameter(in) 18.0 18.0
Maximum Pond Outlet Release Rate(cfs) 2.32 2.91
Spillway Crest Elevation (ft) 4930.0 4930.0
Spillway Length (ft) 68.0 68.0
E. Erosion Control
Based on the swale size calculations provided in Appendix C, the average flow velocities for the
100-year storm event are well below the eroding velocity of 5 feet per second; therefore, lining
the swales with native vegetation/grass is sufficient to provide protection against any potential
erosion and there is no need to provide any hard lining such as riprap.
V. Conclusions
When developed, the site's runoff will be increased. The proposed swales, streets and
stormwater system will capture the increased runoff from the site and will route the storm flows
to the proposed stormwater storage systems and eventually into Dry Creek. All drainage design
considerations contained in this drainage report are in accordance with the Larimer County
Stormwater Design Standards, City of Fort Collins Stormwater Criteria Manual, and the Urban
Drainage and Flood Control District's Urban Storm Drainage Criteria Manuals. In general, the
design presented in this report serves to provide a safe and adequate drainage system for the
Industrial Business Park International PUD development Lots 5-9 and Envelopes B, C, & D
Amended Plat.
I_. Copyright Lamp, Rynearson&Associates, Inc., 2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 5
Lots 5-9 and Envelopes B,C,&D Amended Plat
Project No. 0218008.01
VI. References
1. City of Fort Collins, Fort Collins Amendments to the Urban Drainage and Flood Control
District Criteria Manual(Stormwater Criteria Manual).
2. Larimer County, Stormwater Design Standards, June 20, 2005.
3. Final Drainage Report for Timbervine, Fort Collins, Colorado, prepared by Galloway, July
2014.
4. The Urban Storm Drainage Criteria Manual(USDCM), Volumes 1 and 3, published by the
Urban Drainage and Flood Control District (UDFCD), Denver, Colorado, revised April
2008.
I
I
Copyright Lamp, Rynearson&Associates, Inc., 2018.All rights reserved. March 2018
Final Drainage Report for Industrial Business Park International PUD Page 6
Lots 5-9 and Envelopes B, C. &D Amended Plat
Project No. 0218008.01
Appendix A 1�
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Hydrologic Soil Group—Larimer County Area,Colorado Amber Waves Soils Map
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres In AOI Percent of AOI
7 Ascalon sandy loam,0 B 0.0 0.1%
to 3 percent slopes
122 Caruso clay loam,0 to 1 D 2.4 8.2%
percent slope
33 Fluvaquents,nearly B 11.4 38.6%
level
60 Larim gravelly sandy B 3.7 12.4%
loam,5 to 40 percent
slopes
64 Loveland clay loam,0 to C 5.4 18.1%
1 percent slopes
105 Table Mountain loam,0 B 6.7 22.6%
to 1 percent slopes
Totals for Area of Interest 29.5 100.0%
usDA Natural Resources Web Soil Survey 1/12/2018
Conservation Service National Cooperative Soil Survey Page 3 of 4
Hydrologic Soil Group—Ladmer County Area,Colorado Amber Waves Soils Map
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups(A, B, C, and D)and
three dual classes (AID, BID, and C/D).The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential)when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet.These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential)when
thoroughly wet.These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (AID, BID, or CID), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff:None Specified
Tie-break Rule:Higher
usDA Natural Resources Web Soil Survey 1/1212018
1111111111 Conservation service National Cooperative Soil Survey Page 4 of 4
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City of Ft. Collins pro d Plans
Approved By
Date.
Final Drainage Report
TIMBERVINE
FORT COLLINS, COLORADO
Prepared For:
WW Development
Landon Hoover
1218 West Ash Street, Suite A
Windsor, Colorado 80550
Prepared By:
Galloway
3760 E. 15th Street, Suite 202
Loveland, CO 80538
(970) 800-3300
1 „ Contact: James Prelog
l Project No. SPHLV0001.01
July, 2014
G a n oway
Planning.Architecture.Engineering.
toris unofficial copy was downloaded on Oct-03-2017 from the City of Fort Collins Public Records Website:htip://citydocs.fcgovcom
Drainage Facility Design
4.1 General Concept
In the developed condition, the site is divided into two major basins, Basins A and B.
These basins are further sub-divided into 16 basins for sizing of the inlets, storm sewer
and swales. The site will ultimately consist of ground covered by pavement, rooftops,
and landscape. Runoff from the sub-basins will travel overland to the curb and gutter.
The curb and gutter will convey runoff directly to the swales and local inlets, where it
will enter the storm sewer system. Both the swales and the storm systems will convey the
runoff to the water quality/detention ponds.
Runoff from the exiting water quality/detention ponds will flow south through the storm
sewer and into a drainage channel, which ultimately outfalls to Dry Creek.
Basin A
Basin A is generally located in the eastern portion of the site and has been sub-divided
into ten basins. The basin consists of single-family residential lots. Runoff from the"A"
Basin is conveyed south by storm sewer or bioswale to Water Quality/Detention Pond A.
Basin B
Basin B is generally located in the western side of the site and has been sub-divided into
six basins. The basin consists of single-family residential lots. Runoff from Basin B is
conveyed by curb and gutter and swales to water quality/detention Pond B.
4.2 Specific Details
The most difficult issue for the drainage system for this site was the flatness and lack
cover available for the storm sewer. To solve this issue, runoff is designed to flow
overland where possible. When storm'sewer is necessary, elliptical pipes are designed to
convey flow to the water quality/detention ponds at a minimum slope while still
conveying the necessary runoff.
The water quality/detention ponds will be hydraulically connected. There is a 24-inch
RCP connecting the two ponds with 2 inlets contributing flows. This pipe has a capacity
of 13.76 cfs. The inlets plus the inlet 100 yr flows require 12.73 cfs of which only 8.7 cfs
capacity is needed to allow the ponds to equalize.
The ponds onsite have been analyzed for both detention and water quality. The proposed
ponds have been designed to cumulatively provide the maximum storage volume
capacity calculated for the site. The eastern pond (Pond A) will capture Major Basin A
flows and discharge through the 24-inch RCP connecting Pond A to Pond B and into the
western pond (Pond B). Pond B captures flows from Major Basin B and flows from Pond
A. All flows will be released from the outlet structure in Pond B at the 2-year historical
rate of 7.84 cfs (0.2 cfs/acre, provided by the City of Fort Collins). Detention pond
calculations are located in Appendix D.
-rinibetvine, Final Drainage Report
Page 4 of 9
[rhis unofficial copy was downloaded on Oct-03-2017 from the City of Fort Collins Public Records Website:http://citydoes.fcgoy.com
N*ll'd
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7
Fort Collins Amendments
to the Urban Drainage and Flood Control District Criteria Manual
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, are as follows:
(A) Volume 1, Chapter I-Drainage Policy:
(1) Section I.0 is amended to read as follows:
1.0 Policy
1.1 Drainage Policy
The requirements contained in the Urban Drainage and Flood Control District Criteria
Manual (the "Urban Drainage Manual"), as adopted by the City Council of the City of
Fort. Collins and as modified by these Fort Collins Amendments (together referred to as
the "Fort Collins Stormwater Criteria Manual," the "Stormwater Criteria Manual, or
"Manual')are the basis for all stormwater management within the city of Fort Collins and
are to be used as guidelines in the design and evaluation of all storm drainage facilities.
In general, these requirements address five areas of concern: (1) overall storm drainage
planning and management; (2) the interface between urban development and irrigation
facilities such as dams, reservoirs and canals; (3) the treatment of historic drainageways
and natural channels; (4) the requirements and specifications for engineering design of
storm drainage facilities; and (5) the quality and extent of urban Stormwater runoff and
erosion control.
1.2 Purpose and Scope
(a) The purpose of this Manual is to set forth the technical criteria to be utilized in the
j analysis and design of drainage systems within the city limits of Fort Collins, Colorado
and its Growth Management Area.
(b) Any reference in the Urban Drainage Manual to a city,region or district is to the City
of Fort Collins(the"City") or the Fort Collins area or region.
(c) This Manual applies to all land disturbing activities defined as development in the
Land Use Code of the City of Fort Collins (the "City Land Use Code") or otherwise
regulated by the City, including activities on public or private lands, including but not
limited to activities on private land, public rights-of-way, easements dedicated for public
use,private roads and to all privately,publicly, and quasi-publicly owned and maintained
facilities.
(d) All planned public or private improvements, or any other proposed construction or
development activities regulated by the City must include an adequate plan for storm
drainage. This plan must be based on an analysis and design in compliance with all the
applicable regulations and specifications set forth in this Manual.
(e) Prior to commencement of any construction or development activities subject to the
requirements of this Stormwater Criteria Manual, formal approval must be obtained from
the Executive Director of the Utilities or his designee.
I
i
(B) Volume 1, Chapter 4-Rainfall:
(1) Section 1.0 is deleted in its entirety.
(2) A new Section 1.1 is added, to read as follows:
1.1 General Design Storms
All drainage system design and construction must take into consideration three separate
and distinct drainage problems.
The first is the eightieth (80"i) percentile storm event or the rain event for which 80% of
all rain events have an equal or smaller depth of rain. This storm event is used to design
water quality features. The second is the "Minor" or"Initial Storm", which is the 2-year
storm in the city of Fort Collins. This is the storm that has a probability of occurring, on
the average, once every two (2) years (or one that has a fifty percent chance probability
of exceedance every year). The third is the "Major Storm", which is the 100-year storm
in the city of Fort Collins. This is the storm that has a probability of occurring, on the
average, once every one hundred(100) years (or one that has a one percent probability of
exceedance every year). In some instances the 100-year storm routing of runoff will not
be the same as that for the 2-year storm.
(3) Anew Section 1.2 is added, to read as follows:
1.2 Minor(2-Year)Storm Provisions
The objectives of such drainage system planning are to minimize inconvenience, to
protect against recurring minor damage and to reduce maintenance costs in order to
create an orderly drainage system at a reasonable cost. The 2-year storm drainage system
may include such facilities as curb and gutter, storm sewer, open channels, drainageways,
ponds,rivers,streams,and detention facilities.
(4) A new Section 1.3 is added, to read as follows:
1.3 Maior(100-Year) Storm Provisions
The objectives of the 100-year storm drainage system planning are to eliminate
substantial loss of life or property damage. Major drainage systems may include storm
sewers, open channels, drainageways, ponds, rivers, streams, and detention facilities.
The correlation between the minor and major storm system must be analyzed to ensure
that a well coordinated drainage system is designed and constructed.
(5) Section 2.0 is deleted in its entirety.
(6) Section 2.1 is deleted in its entirety.
(7) Section 2.2 is deleted in its entirety.
(8) Section 3.0 is deleted in its entirety.
li
(9) Section 3.1 is deleted in its entirety.
31
(11) Section 4.0 is amended to read as follows:
i 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 Intensity Intensity Intensity
(min) (in/hr) (in/br) (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
33
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 Intensity Intensity Intensity
(min) (in/hi) (in/hr) (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
34
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.
40
i
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) Anew 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:
J(C, *A,)
C= i-i A (RO-8)
Where: C= Composite Runoff Coefficient
C;=Runoff Coefficient for Specific Area(A;)
A;=Area of Surface with Runoff Coefficient of C;, acres or feet'
n=Number of different surfaces to be considered
A,=Total Area over which C is applicable, acres or feet'
(5) Anew Section 2.10 is added, to read as follows:
41
i
i2.10 Runoff Coefficient Adiustment 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 Frequency Factor
ears Cr
2 to 10 1.00
11 to 25 1.10
26 to 50 1.20
51 to 100 1.25
Note: The product of C times Cf cannot exceed the value of 1, in the cases where it does a value of
I must be used
(6) Section 3.1 is deleted in its entirety.
i (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.e�a.2ov/ednnrmrl/models/swmm/index.h[m).
(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.
I
42
i
Table RO-13
iSWMM Input Parameters
Depth of Storage on Impervious Areas 0.1 inches
Depth of Storage on Pervious Areas 0.3 inches
Maximum Infiltration Rate 0.51 inches/hour
Minimum Infiltration Rate 0.50 inches/hour
Decay Rate 0.0018 inches/sec
Zero Detention Depth 1%
Manning's n Value for Pervious Surfaces 0.025
JManning's n Value for Impervious Surfaces 0.016
4.3.2 Pervious-Impervious Area
Table RO-14 should be used to determine preliminary percentages of impervious land
cover for a given land-use or zoning. The final design must be based on the actual
physical design conditions of the site.
Table RO-14
Percent Imperviousness Relationship to Land Use*
PERCENT IMPERVIOUS
LAND USE OR ZONING
Business:
T 20
CCN, CCR, CN 70
E,RDR, CC,LC 80
C,NC,I,D,HC, CS 90
Residential:
RF,UE 30
RL,NCL 45
LMN,NCM 50
MMN,NCB 70
Open Space:
Open Space and Parks(POL) 10
Open Space along foothills ridge 20
(POL,RF)
RC 20
*For updated zoning designations and definitions, please refer to Article Four of the City Land
Use Code,as amended
43
I (D) Volunrel, Chapter 6-Streets/Inlets/Storm Sewers:
(1) Section 2.2 is amended to read as follows:
2.2 Design Requirements
(a) The Minor (or Initial) Storm is designated as the 2-year storm. The Major Storm is
designated as the 100-year storm.
(b) The encroachment of gutter flow on the street for the 2-year storm runoff must not
exceed the criteria set forth in Table ST-2. A storm drainage system must begin where the
encroachment reaches the limits found in this table.
Table ST-2
Pavement Encroachment Standards for the Minor(i.e., 2-Year) Storm
Street Classification Maximum Encroachment* **
Local (includes places,courts, and alleys) No curb-topping. Flow may spread to crown of
street.
Collector and Arterial (Without Median) No curb-topping. Maximum six (6) inch flow depth
at the gutter. Flow spread must leave at least a six
(6) foot wide clear travel lane on the one-half street
section
Arterial (with Median) No curb-topping. Maximum six (6) inch flow depth
at the gutter. Flow spread must leave at least a
twelve (12) feet wide clear travel lane in each
direction
*Where no curbing exists,encroachment must not extend over property lines.
** These criteria apply only to City streets where no floodplain has been designated. For areas
with designated floodplains,please refer to Chapter 10 of the City Code for further guidance.
(c) Standards for the Major Storm and cross-street flows are also required. The Major
Storm needs to be assessed to determine the potential for flooding and public safety.
Cross-street flows also need to be regulated for traffic flow and public safety reasons.
The City has established street inundation standards during the Major Storm event and
allowable cross-street flow standards for the Minor (2-year) Storm and the Major (100-
year) Storm.
(d) Table ST-3 sets forth the allowable street encroachment for the 100-year storm
runoff.
46
Table ST-3
Street Inundation Standards for the Major(i.e., 100-Year)Storm
Street Classification Maximum Encroachment **
Local,Collector and Arterial(without Median) The depth of water at the street crown shall not exceed six (6)
inches to allow operation of emergency vehicles, the depth of
water over the gutter flow line shall not exceed twelve (12)
inches, and the flow must be contained within the right-of-way
or easements paralleling the right-of-way. The most restrictive
of the three criteria shall govern.
Arterial (with Median) The depth of water must not exceed the bottom of the gutter at
the median to allow operation of emergency vehicles, the depth
of water over Ore gutter flow line shall not exceed twelve (12)
inches, and the flow must be contained within the right-of-way
or easements paralleling the right-of-way. The most restrictive
of the three criteria shall govern.
** These criteria apply only to City streets where no floodplain has been designated. For areas
with designated floodplains,please refer to Chapter 10 of the City Code for further guidance.
(e) Table ST4 sets forth the allowable cross-street flow for the Minor (2-Year) and the
Major(100-Year) Storm events.
iTable ST-4
Allowable Cross-Street Flow
Street Classification Minor 2-Year) Storm Flow Major 100-Year Storm Flaw
Local Six(6) inches of depth in Eighteen(18) inches of depth above
cross pan. gutter flow line.
Collector Where cross pans are allowed, Twelve(12)inches of depth above
depth of flow should not gutter flow line.
exceed six(6) inches in cross
an
Arterial None. No cross flow. Maximum depth at
upstream gutter on road edge of twelve
(12) inches.
(f) Once an allowable spread (pavement encroachment) has been established for the
Minor Storm, the placement of inlets can be determined. The inlets will remove some or
all of the excess stormwater and thus reduce the spread. The placement of inlets is
covered in Section 3.0 of this chapter. it should be noted that proper drainage design
utilizes the full allowable capacity of the street gutter in order to limit the cost of inlets
and storm sewers.
(g) Another important design consideration is the frequency of occurrence of the Minor
Storm. In other words, the design engineer must factor into his design how often the
spread of stormwater will reach or exceed the maximum encroachment limit. This is
addressed by assigning a frequency (or recurrence interval) for the Minor Storm for
47
various street classifications. The selection of a design frequency is based on many
factors including street function, traffic load and vehicle speed. In the city of Fort
Collins, the Minor Storm recurrence interval is the 2-year storm for all street
classifications.
(h) For street sump locations, provisions must be included to carry the 100-year runoff in
a pipe or an overflow channel to an acceptable outfall while the maximum water surface
depth criteria as designated in Table ST-2 and in Table ST-3 are not violated.
(i) An access and maintenance easement for the overflow drainage facility must be
provided if that facility is not contained within the public right-of-way.
0) Two additional design considerations of importance in street drainage are gutter
(channel) shape and street slope. Most urban streets contain curb and gutter sections.
Various types exist including spill shapes, catch shapes, curb heads, and roll gutters. The
shape is chosen for functional, economic, or aesthetic reasons and does not dramatically
affect the hydraulic capacity. Swales are common along some urban and semi-urban
streets, and roadside ditches are common along rural streets. Their shapes are important
in determining hydraulic capacity and are covered in the next chapter.
(2) Table ST-2 Pavement Encroachment Standards for the Minor (i.e., 2-Year) Storm is
amended
(3) Table ST-3 Street Inundation Standards for the Major(i.e., 100-Year) Storm is amended
(4) Table ST-4 Allowable Cross-Street Flow is amended
(5) A new Section 3.5 is added, to read follows:
3.5 Inlet Design and Construction Standards
(a) Storm inlets must be designed and installed where sump (low-spot) conditions exist
or when allowable street capacities are exceeded. The outlet pipe of the storm inlet must
be sized on the basis of die theoretical capacity of the inlet, with a minimum diameter of
fifteen (15) inches, or a minimum dimension of twelve (12) inches if elliptical or arch
pipe is used.
I (b) All curb openings must be installed with the opening at least two (2) inches below
I the flow line elevation. The minimum transition length allowed is five (5) feet
(c) Any curb opening greater than six (6) inches in Height must have a metal bar welded
horizontally across the inlet for public safety purposes such that no opening height is
greater than six (6) inches.
(d) All inlet covers must be stenciled or stamped with the following designation: NO
DUMPING-DRAINS TO POUDRE RIVER
(6) A new Section 4.5 is added, to read as follows:
4.5 Storm Sewer System Construction Standards
Construction of all stormwater facilities must be built in accordance the approved Water Utilities
Development Construction Standards or the Water Utilities Capital Construction Standards as
appropriate.
48
(E) Volume 1, Chapter 7-Major Drainage:
(1) Section 3.2.8 is amended to read as follows:
3.2.8 Open Channel Design
The minimum design criteria requirements listed below must be satisfied.
3.2.8.1 Natural Channels (Open Floodplain Design)
For development sites located out of the 100-year floodplain, the following open channel
requirements must be met:
1. If the total flow of the channel and floodplain is confined to an incised channel and
erosion can be expected to endanger adjacent structures, 100-year check structures
are required to control erosion and degradation of the channel area. See Volume 2,
Chapter 8,"Hydraulic Structures", of this Manual for more information. In addition,
sufficient right-of-way must be reserved to install the equivalent of a trapezoidal
grass-lined channel that satisfies the velocity criteria specified in Table MD-2. Extra
width must be reserved where drop structures are needed, in which locations a twenty
(20) foot-wide maintenance access bench must be provided along one side of the
channel.
2. If the floodplain is wide and the low-flow channel represents a small portion of the
floodplain area, low-flow check structures are usually required, unless it can be
demonstrated that the channel will remain stable as the watershed urbanizes.
3. Consult the applicable City's Master Drainage Plan document for guidance on the
design event and stable stream or waterway longitudinal slope.
4. For either of the above cases, a maintenance access trail must be provided. It should
be designed according to the guidelines for grass-lined channels in Section 3.2.8.3,
below.
3.2.8.2 Open Floodway Design (Natural Channel with Floodplain Encroachment)
Although floodplain preservation is preferable,when the development involves
preserving the floodway while filling and building on the fringe area, the open channel
design must meet the all the requirements in listed Section 3.2.8.1 of this chapter,as well
as the following requirements listed below for fill.
The fill slopes must be adequately protected against erosion with:
I. Fill slopes of four to one(4H:IV)or flatter that are vegetated in accordance with the
criteria listed in the"Revegetation"chapter of this Manual(Volume 2, Chapter 12).
2. Fill slopes must be protected by rock(not broken concrete or asphalt) riprap meeting
City criteria with up to two and a half to one(2.5H:1 V)slopes.\
3. Retaining walls must not be not taller than three and a half(3.5) feet,with adequate
foundation protection.
3.2.8.3 Grass-Lined Channel Design
The design for a grass-lined channel must meet the following criteria:
49
I. Side slopes must be four to one(4H:IV) or flatter.
i 2. Continuous maintenance access,such as with a trail,must be provided. The
stabilized trail surface must be at least eight(8)feet wide with a clear width
of twelve (12) feet. It must be located above the minor(2-year) event water
surface elevation, but never less than two (2)feet(three feet for streams with
perennial flow) above that elevation.Trail profiles need to be shown for all
critical facilities such as roadway crossings, stream crossings and drop
structures. All access trails shall connect to public streets.Maintenance trails
need not be paved,but must be of all-weather construction such as aggregate
base course,gusher fines,recycled concrete course or Aggregate Turf
Reinforced Grass Pavement(RGP) described in Volume 3 of this Manual
and capable of sustaining loads associated with large maintenance
equipment. Paved trails are encouraged to allow for recreational use of the
trails. When paved,pavement should be five (5) inches minimum thickness
of concrete (not asphalt).Maximum longitudinal slope for maintenance-only
trails is ten percent(10%),but less than five percent(5%)when used as
multi-purpose recreational trails to meet the requirements of the Americans
with Disabilities Act.The Utilities Executive Director may accept adjacent
public local streets or parking lots as maintenance access in lieu of a trail, if
he or she determines that a modification of this requirement is appropriate.
3. A low-flow or trickle channel is desirable. See Section 41.5 of this chapter
for criteria.
4. Wetland bottom and bioengineered channels are acceptable when designed
according to City wetland bottom channel criteria in Section 4.2 of this
chapter.
5. The channel bottom minimum cross slope for dry bottom channels shall be
one percent(1%).
6. Tributary inflow points shall be protected all the way to the low-flow
channel or trickle channel to prevent erosion.Inflow facilities to wetland
bottom channels shall have their inverts at least two (2)feet above the
channel bottom to allow for the deposition of sediment and shall be protected
with energy dissipaters.
7. All roadway crossings of wetland bottom channels shall incorporate a
minimum of a stabilized two (2)foot drop from the outlet to the bottom of
the downstream channel in order to preserve hydraulic capacity as sediment
deposition occurs over time in the channel.
8. All drop structures must be designed in accordance with the"Hydraulic
Structures"chapter of this Manual.Underdrain and storm sewer outlets
located below the stilling basin's end-sills are not acceptable. Construction
plans must utilize City standard details.
9. Storm sewer outlets must be designed in accordance with the criteria in
Sections 5.0, 6.0, and 7.0 of this chapter. Alternatively,conduit outlet
structures, including low tailwater riprap basins design described in Section
3.0 of the"Hydraulic Structures"chapter of this Manual must be used when
appropriate.
50
place. Often mowing of dry-land native grasses during the growing season may not be
necessary, except for weed control.
i (c) A maintenance access platform with a minimum passage width of twelve (12) feet
shall be provided along the entire length of all major drainageways except at drop
structures,where a twenty(20)foot maintenance platform is needed
(d) When public or private drainage channels and associated facilities abut private
property, it is the responsibility of the parties involved,whether they are public or
private, to develop and implement a policy regarding fencing and safety.
(4) Section 4.1.1.5 is amended to read as follows:
4.1.1.5 Design Discharge Freeboard
All open channels shall be designed with a freeboard. Freeboard for major channels
(defined as those with capacity in excess of one hundred (100) cis) must be a minimum
of one foot of extra depth. Freeboard for minor channels (defined as those carrying less
than one hundred (100) cfs design flow) must be designed to handle a minimum of an
additional 33 percent of runoff, over and above the 100-year design flow.
(5) Table MD-2 is adopted with the following modification:
The minimum riprap Manning's-n value used to check for stability is 0.07.
(6) Table 10-3 is adopted with the following modification:
All references to"District Maintenance Eligibility"shall be deleted.
(7) Table MD-4 is adopted with the following modification:
All references to"District Maintenance Eligibility"shall be deleted.
(8) Section 4.3.6 is deleted in its entirety.
(9) Table MD-6 is adopted with the following modification:
All references to"District Maintenance Eligibility"shall be deleted.
(10) Table MD-7 is adopted with the following modification:
All references to Type VL and Type L riprap designations shall be deleted.
(11) Table MD-10 is adopted with(lie following modification:
All references to Type VL and Type L riprap designations shall be deleted.
(12) Table MD-12 is adopted with the following modification:
I
All references to Type VL and Type L riprap designations shall be deleted.
52
(H) Volume 2, Chapter 10-Storage:
i (1) Section 3.1.1 is amended to read as follows:
3.1.1 Use of Simplified On-Site Detention Sizing Procedures
(a) There are two methodologies approved by the City for sizing detention storage
basins, the Rational Formula-based Federal Aviation Administration (FAA) procedure
and the Storm-water Management Model (SWMM). The City is the determining authority
regarding the appropriate methodology to use under different circumstances. Early
contact with the City is encouraged for the timely determination of the appropriate
detention storage sizing methodology.
(b) In general, the Rational Formula-based FAA procedure may only be used in the
design of detention storage facilities with tributary areas that are less than five (5) acres
in size. The Stormwater Management Model (SWMM) must be used to model and size
stormwater detention storage facilities with tributary areas of twenty (20) acres or more.
Preliminary sizing of detention storage volume may be performed for site planning
purposes using the Rational Formula-based FAA procedure in conjunction with a twenty
(20) percent upward adjustment to account for the larger resulting storage volume that
would be obtained from SWMM modeling.
(c) For tributary areas between five and twenty (20) acres in size, either SWMM or the
Rational Formula-based FAA procedure may be used to calculate detention storage
volume. However, if the Rational Formula-based FAA procedure is chosen as the
preferred method, the resulting storage volume must be increased by a factor of twenty
(20)percent to better match the result that would be obtained from SWMM modeling.
(2) Section 3.1.2 is amended to read as follows:
3.1.2 Detention Pond Hvdrograph Sizing Procedure
(a) Whenever the area limits described above in Section 3.1.1 are exceeded(for tributary
catchments larger than twenty acres for the FAA Procedure)the City requires the use of
hydrograph flood routing procedures (e.g.,using SWMM reservoir routing calculations).
In addition,if there are upstream detention facilities in the watershed that catch and route
runoff for portions of the upstream tributary area, hydrograph routing methods must be
1 employed.
(b) If off-site tributary areas contribute runoff to an on-site detention storage facility, the
total tributary area at existing development mate must be accounted for in the design of the
storage facility by routing the flows generated by that off-site area around the proposed
storage facility or, by fully accounting for these flows in the design of the spillway
system for that storage facility.
(3) Section 3.1.3 is amended to read as follows:
3.1.3 Water Ouality Capture Volume in Sizing Detention Storage
When detention storage volume is sized for a site that also incorporates a water quality
capture volume (WQCV) defined in Volume 3 of this Manual, the 100-year volume
required for quantity detention must be added to the entire WQCV. The WQCV must
also be added in its entirety to the required 5-or 10-year volume.
(4) Section 3.2.1 is deleted in its entirety.
56
The value of Vs increases with time, reaches a maximum value, and then starts to
decrease. The maximum value of Vs is the required storage volume for the detention
facility. Sample calculations using this procedure are presented in Design Example 6.2.
The modified FAA Worksheet of the UD-Detention Spreadsheet performs these
calculations.
(7) Section 3.2.4 is deleted in its entirety.
(8) Section 3.2.5 is deleted in its entirety.
(9) Section 3.2.6 is deleted in its entirety.
(10) Section 3.2.7 is deleted in its entirety.
(11) Section 3.3.3 is amended to read as follows:
3.3.3 Spillway Sizing and Design
(a) The overflow spillway of a storage facility must be designed to pass flows in excess
of the design flow of the outlet works. When the storage facility falls under the
jurisdiction of the Colorado State Engineer's Office (SEO), the spillway's design storm is
prescribed by the SEO. If the storage facility is not a jurisdictional structure, the size of
the spillway design storm must be based upon analysis of the risk and consequences of a
facility failure. Generally, embankments should be fortified against and/or have spillways
that, at a minimum, are capable of conveying the total not-routed peak 100-year storm
discharge from a fully developed total tributary catchment, including all off-site areas, if
any. However, detailed analysis, of downstream hazards must be performed and may
indicate that the embankment protection and, or spillway design needs to be sized for
events much larger than the 100-year design storm.
(b) The detention pond spillway crest must be set at the 100-year water surface elevation
in the pond and the spillway shall be designed such that any spills shall be no more than
six (6) inches in depth at the crest during the 100-year storm. The detention pond top of
embankment shall be set at all points a minimum of one foot above the spillway crest
elevation.
(c) Emergency spillways must be protected from catastrophic erosion failure through the
use of bank protection procedures downhill from the spillway to the toe of slope. The
slope protection for spillway embankments shall be designed in accordance with all the
specifications set forth in Volume 1, Chapter 7, Major Drainage, Section 4.4.4.3, "Riprap
Specifications and Applicability",of this Manual.
(d) A concrete cutoff wall eight inches in thickness, three feet deep, extending five feet
into the embankment beyond the spillway opening is required on private detention ponds
larger than one acre-foot in volume and are also required on all publicly-owned regional
detention ponds larger than that size. The emergency spillway crest elevation must be
tied back to the top of the pond embankment at a maximum slope of four to one.
(12) Section 3.3.4 is amended to read as follows:
3.3.4 Retention Facilities
(a) A retention facility(a basin with a zero release rate or a very slow release rate) is
used on a temporary basis when there is no available formal downstream drainageway,or
one that is grossly inadequate.When designing a retention facility,the hydrologic basis
of design is difficult to describe because of the stochastic nature of rainfall events. Thus,
58
4. Initial Shaping of the Facility: The initial shape of the facility must be based upon site
constraints and other goals for its use discussed under item 1, above. This initial shaping
i is needed to develop a stage-storage-discharge relationship for the facility. The design
spreadsheets of this Manual are useful for initial sizing.
5. Outlet Works Preliminary Design: The initial design of the outlet works entails
balancing the initial geometry of the facility against the allowable release rates and
available volumes for each stage of hydrologic control.This step requires the sizing of
outlet elements such as a perforated plate for controlling the releases of the WQCV,
orifices,weirs, outlet pipe,spillways, etc.
6. Preliminary Designn: A preliminary design of the overall detention storage facility
must be completed using the results of steps 3,4 and 5,above.The preliminary design
phase is an iterative procedure where the size and shape of the basin and the outlet works
are checked using a reservoir routing procedure and then modified as needed to meet the
design goals. The modified design is then checked again using the reservoir routing and
further modified if needed. Though termed"preliminary design,"the storage volume and
nature and sizes of the outlet works are essentially in final form after completing this
stage of the design. They may be modified, if necessary, during the final design phase.
7. Final Design: The final design phase of the storage facility is completed after the
hydraulic design has been finalized. This phase includes structural design of the outlet
structure, embankment design, site grading,a vegetation plan, accounting for public
safety, spillway sizing and assessment of dam safety issues,etc.
(14) Section 4.3 is amended to read as follows:
4.3 Geometry of Storage Facilities
(a) The geometry of a storage facility depends on specific site conditions such as
adjoining land uses, topography, geology,preserving or creating wildlife habitat, volume
requirements, etc. Several key features must be incorporated in all storage facilities
located within the City(see Figure SO-6). These include:
i. Four to one(4H : IV) or flatter side slopes of all banks.
ii. Low-flow or trickle-flow channel unless a permanent pool takes its place or the pond
is designed to handle low flows through infiltration.
iii. Forebay.
iv. Pond bottom sloped at least one percent to drain toward the low-flow or trickle-flow
channel or the outlet.
v. Emergency spillway or fortification of the embankment to prevent catastrophic
failure when overtopped, spillway shall be designed to safely convey the 100-year
overtopping discharge for the entire area tributary to the storage facility.
vi. The micro pool surface elevation must be set at an elevation equal to the invert of
the pond which results in the value of Dmp being set at 0 (D,,(p= 0) as shown in
Figure SO-6 of this Manual.
(b) For safety as well as maintenance considerations, the maximum allowable pending
depth of water in a detention storage facility during the 100-year, 2-hour stone event is
ten(10)feet.
(c) Detention storage facilities must be located at least twenty (20) feet away from an
irrigation canal or ditch. Whenever- a detention pond parallels a canal no more than
twenty percent (201/o) of the detention pond perimeter can be parallel to the irrigation
canal.
60
15. For all landscaped storage facilities the minimum amount of biodegradable,
nontoxic fertilizers and herbicides needed shall be used to maintain the facility.
All landscape debris must be collected and disposed of off-site.
16. All detention facilities must be designed to minimize required maintenance and
to allow access by equipment and workers to perform maintenance. The City will
generally maintain regional facilities and facilities on public lands.Maintenance
responsibility for facilities located on private land shall be the responsibility of
the property owner.
17. The entire detention basin including all appurtenances necessary for the operation
and maintenance of the detention facility and the area within the required
freeboard for the detention storage must be within a dedicated drainage easement.
18. All detention ponds with a water ponding depth of over four(4) feet must have a
water depth gauge. The depth gauge must be referenced to the deepest point in
the pond. The numbers on the gauge shall be visible from the detention pond
access point or the nearest street.
See Volume 3 of this Manual for additional requirements regarding operation and
maintenance of water quality-related facilities, some of which also apply to detention
facilities designed to meet other objectives.
(18) Section 4.11 is amended to read as follows:
4.11 Access
(a) An all-weather stable maintenance access must be provided to the bottom of
detention ponds. The surface of this maintenance access shall constitute a solid driving
surface of gravel, rock, concrete, or gravel-stabilized turf and should allow maintenance
access to the inflow forebay, and the outlet works areas. Maximum grades for equipment
access shall be no steeper than ten percent. For ponds less than one acre-foot in volume,
access may be allowed from an adjacent drivable surface that is not within the detention
pond area as long as equipment can safely reach and maintain all of the facility's features
and appurtenances.
(b) When detention storage facilities abut private property, it is the responsibility of the
parties involved to develop and implement a policy regarding fencing and safety.
(19) A new Section 4.14 is added, to read as follows:
4.14 Trickle Channels in Storage Facilities
(a) Measures must be taken to control standing water and to control nuisance flows.
Detention basin bottoms are recommended to have a minimum cross slope (measured
perpendicular to the trickle channel)of two percent for grassed surfaces and one percent
for pavement surfaces where possible. For cross slopes less than these please refer to the
detailed guidance provided regarding the appropriateness of the use of trickle channels in
the addendum to this Manual titled "Detention Pond Landscape Standards and
Guidelines" dated November 2009.
(b) Whenever trickle channels are called for these must be designed to carry
approximately one percent of the 100-year design flow with a minimum longitudinal
slope of half a percent.
63
LARIMER COUNTY
STORMWATER DESIGN STANDARDS
(ADDENDUM TO THE URBAN STORM DRAINAGE CRITERIA
MANUALS-
VOLUMES 1 , 2 AND 3)
Larimer County Engineering Department
200 West Oak Street, Suite 3000 LARLb1ER
P.O. Box 1190 COUNTY
Fort Collins, CO 80522-1190
ADOPTED: JUNE 20, 2005
PRECIPITATION-FREQUENCY RELATIONSHIPS
Precipitation-frequency relationships are prerequisites for valid drainage planning and design.
For purposes of drainage planning and design in Larimer County. The County was divided into
three major hydrologic areas (Fig. RA-11), as follows:
Area I. The area contained within the watershed boundaries of the master
planned basins surrounding the City of Fort Collins. This area may be
approximately described as the area extending from the east County line
west to the foothills and from the watershed divide between the Cache la
Poudre and Big Thompson rivers at approximately County Road 30 on
the south north to the watershed boundaries of Dry Creek and Boxelder
Creek basins.
I
Area 11. The area near Loveland from the east county line to the first"hogback" on
the west and from the south county line to the watershed divide between
the Big Thompson and Cache la Poudre Rivers on the north.
Area III. The remainder of the county not in Area I or Area 11.
The precipitation-frequency data for each area are different in order to closely match the local
precipitation regimes.
Two sources of information are used in three geographic areas. The first source of information
is the National Oceanic and Atmospheric Administration Precipitation Frequency Atlas of the
Western United States, 2, Volume III-Colorado. These relationships are those used for
hydrological determinations in Areas 11 and III. The second source of information is the City of
Fort Collins rainfall criterion which was developed by a task force following major flooding in the
Fort Collins area in 1997. The City of Fort Collins rainfall information is used for Area I.
The data and procedures used in this section will be revised periodically to keep information
current. The user is expected to use the most-up-date revision of these Standards.
1.1 NOAA Atlas
Procedures developed by the National Oceanic and Atmospheric Administration (NOAA) and
published in Precipitation Frequency Atlas of the Western United States, 2, Volume III-Colorado
(Miller et al., 1973) have been adapted for use in Larimer County. (Hereinafter this publication
will be referred to as NOAA Atlas.)These procedures and data were further verified with 34
years of hourly precipitation data for Fort Collins, and precipitation-frequency curves were
developed for the plains area of Larimer County. Due to the extreme climatological variations in
the mountainous regions of the County, methods were adapted from the NOAA Atlas to
determine precipitation-frequency relationships for these mountainous areas.
The most up-to-date procedures for determining precipitation-frequency relationships, then, are
those contained on the NOAA Atlas. This Atlas presents charts of precipitation of 6- and 24-
hour durations for return periods between 2 and 100 years, and supersedes U.S. Weather
Bureau Technical Paper No. 40 developed in 1961. The main emphasis of the Atlas is to more
accurately depict the variation in the precipitation-frequency regimes for mountainous regions.
I Also, it takes into account regional relationships between stations, and presents a better
regional pattern of precipitation than an analysis of just the stations in Larimer County would
produce.
06/2005
Larimer County Stormwater Design Standards 15
i
6-hour storms as developed from the NOAA Atlas and those developed from only the Fort
Collins station data. This analysis would indicate that the NOAA Atlas data does accurately
predict the precipitation-frequency relationships for the Fort Collins area. A similar analysis of 86
years of Denver data (Urbonas, 1978) produced approximately the same results as the NOAA
Atlas data.
Table RA-2. Comparison of Historical Data for Fort Collins Stations with the NOAA Atlas
Fort Collins station data
34-year Analysis
Return frequency 1940-1973 6-hour Precipitation NOAA Atlas 6 hour precipitation
(inches) (inches)
2-year 1.49 1.43
5-year 1.83 1.96
10-year 2.18 2.28
50-year 3.04 3.08
100-year 3.41 3.45
Precipitation-Frequency relationships for Larimer County were derived by using two methods to
develop the data. Using data from the NOAA Atlas, the variations of precipitation-frequency
relationships along the plains area of Larimer County were analyzed. Then, due to the extreme
changes in precipitation patterns within the mountainous regions of the County, the procedures
of the NOAA Atlas and the data for Larimer County were analyzed to develop site-specific
precipitation-frequency data for the mountainous regions.
1.3.1 Precipitation frequency data for Areas I and II
The rainfall design standards for Area I are based on the City of Fort Collins hydrologic
investigation and rainfall design criteria adopted by the City on March 16, 1999. Precipitation
data for Area 11 have been computed from the NOAA Atlas. These standards should be used
with the procedures presented in Section 4 of this Manual to determine the design hydrology of
the watersheds in Areas I and 11. The computed data are as follows:
Area I Area 11
i Intensity Frequency Duration Curve
(for use with Rational Method) Figure RA-2 Figure RA-3
Design storms: 2 hours— 5 min Table RA-3 Table RA-4
3 hours— 10 min Table RA-5
Precipitation data: 6 hours, and 24 hours Table RA-6
I '
06/2005
Larimer County Stormwater Design Standards 17
Figure RA-2. Rainfall Intensity— Duration — Frequency Curve for Area I
�h N
I I I 1
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(J4/ul) Amsualul
06/2005
Larimer County Stormwater Design Standards 18
i
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r 0 J
LARIMER COUNTY PRECIPITATION
DEPTH - D URA TION - FREQUENCY
DATA B 0 UDARIES
106' WYOMING 105'
78 77 76 75 COLORADO 72 71 70 69 68
WWWW
�11 f
r..\
8
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\y RED FEATHER LAKES
JACKSON
COUNTY
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Rusnc wit yNGTOM
-14� 1
`I 8 �~ - — BELLINE _ R
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COUNTY ] 36 z I
IBERIlpUO
NOT TO SCALE LARLVER UNT_Y_ s
BOULDER COUNTY
AREA I CITY OF FORT COLLINS
lr. AREA 11 NOAA ATLAS — CITY OF LOWLAND
AREA IN NO" ATLAS
FIGURE RA- 1
PRECIPITATION AREA MAP
06/2005
Larimer County Stormwater Design Standards 27
VOLUME1
III Maior Drainage
2.4.3 Permitting and Regulations
Change ...must comply with the National Flood Insurance Program (NFIP)
regulations.
TO ... must comply with the National Flood Insurance Program (NFIP)
regulations, as adopted by Larimer County.
3.2.8 Maintenance Eligibility
Delete This section in its entirety.
3.3.4 Maintenance
Change A maintenance access road with a minimum passage width of 12 feet
shall be provided along the entire length of all major drainageways. The
local government may require the road to be surfaced with 6 inches of
Class 2 roadbase or a 5-inch-thick concrete slab.
To Larimer County and the design engineer shall work together to provide
access to all major drainageways as determined appropriate at the time
of preliminary and final design.
4.1.5 Trickle and Low-Flow Channels
Change The capacity of a trickle channel should be approximately 2.0% of the
major (i.e. 100-year) design flow...
To The capacity of a trickle channel should be approximately 0.5 to 1.0% of
the major(i.e. 100-year) design flow...
4.1.8 Maintenance
Change A maintenance access road with a minimum passage width of 12 feet
shall be provided along the entire length of all major drainageways. The
local government may require the road to be surfaced with 6 inches of
Class 2 roadbase or a 5-inch-thick concrete slab.
To Larimer County and the design engineer shall work together to provide
access to all major drainageways as determined appropriate at the time
of preliminary and final design.
4.10 Design Submittal Checklist
Change Table MD-3 to reflect above changes regarding maintenance access
roads and trickle and low-flow channels.
06/2005
Larimer County Stormwater Design Standards 45
i
VOLUME 2
Culverts
1.1.2 Headwater
Delete The headwater elevation for the design discharge should be consistent
with the freeboard and overtopping criteria in the POLICY chapter of this
Manual (Tables DP-1 through DP-3).
To The maximum culvert headwater to diameter ratios are:
STORMWATER FREQUENCY HEADWATER TO DIAMETER
10-Year HW/D <_ 1.0
100-Year HW/D <_ 1.5
The minimum culvert capacities are:
DRAINAGE MINIMUM CAPACITY
CLASSIFICATION (RECURRENCE INTERVAL)
Local 10-Year
Residential Collector& 10-Year
Commercial Collector
Minor Arterial & 100-Year
Major Arterial
When the flow in a roadside ditch exceeds the capacity of the culvert and
overtops the cross street, the flow over the crown shall not exceed the
limits established within Table ST-2A in the Streets/Inlets/Storm Sewers
chapter.
The required size of the culvert shall be based upon adequate hydraulic
design analysis. However, to minimize maintenance requirements, the
minimum allowable culvert size for culverts under County roads shall be
18"for circular culverts or a minimum cross-sectional area of 1.77 square
feet. For culverts in roadside ditches, the minimum size shall be 15"for
circular culverts or a 1.23 square foot cross-sectional area.
2.1.1 Energy and Hydraulic Grade Line
Add The hydraulic grade line and energy grade line shall be determined for
each culvert system and included in the Final Drainage Report. Each
culvert system shall be profiled on the Final Construction Drawings and
shall include the design flow hydraulic grade line.
06/2005
Larimer County Stormwater Design Standards 48
it
3.5.3 Culvert Diameter
Add Culverts smaller than 18 inches in diameter may only be used to convey
roadside ditches under driveways where basin location, site grading, and
roadside ditch depths make an 18 inch diameter culvert impractical.
4.1 Projecting Inlets
Add In the absence of a headwall, both culvert entrance and outlet shall
include a flared end section.
06/2005
Larimer County Stormwater Design Standards 49
VOLUME 2
Storage
2.0 APPLICATION OF DIFFERENT TYPES OF STORAGE
Add 6. Parking lot detention ponds may be utilized when land area for a
grassed lined detention pond is not available. To prevent damage to and
flotation of automobiles, parking lot detention ponds shall not exceed 12
inches in depth at any point. Parking lot detention ponds shall be signed
as such to inform the general public about the potential for flooding. A
parking lot detention pond shall not encroach into a public street.
3.2.4 Multi-Level Control
Delete the 5—or
3.3 Design Storms for Sizing Storage Volumes
Change the 5-, 10-, 25-, and 100-year design storms are often considered
and used.
To Requirements for release of storm water from detention will be based on
physical and legal conditions downstream. Normally, detained runoff may
be released at a rate no greater than the 2 year historic rate of runoff from
the site. Release of detained water will only be allowed where it is shown
that physical and legal conditions downstream can accommodate the
release. A higher rate of release may be allowed, provided that physical
conditions downstream will accommodate the proposed rate of release.
3.3.4 Retention Facilities
Change the runoff equal to 1.5 times the 24-hour
To the runoff equal to 2 times the 24-hour
3.4 Reservoir Routina of Storm Hvdrographs for Sizing of Storage Volumes
Change 2. Determine Hvdrologv: The hydrograph may be available in published
district outfall system planning or a major drainage way master plan
report.
To 2. Determine Hydrology: The hydrograph may be available in the Master
Drainage Plans published by Larimer County, the City of Fort Collins, and
the City of Loveland.
4.3 Geometry of Storage Facilities
Delete or fortification of the embankment to prevent catastrophic failure when overtopped.
0612005
Larimer County Stormwater Design Standards 50
5.0 CRITERIA FOR DISTRICT MAINTENANCE ELIGIBILITY
Delete Entire section
Add Larimer County does not have a program to assist in the on-going
maintenance of major drainage facilities including detention facilities. All
detention ponds shall be considered privately owned and privately
maintained.
III
it
,I
� I
06/2005
Larimer County Stormwater Design Standards 51
Appendix C
__ es
al
verslmr 2ao releases lAey209 2y so-r 109- ne soar
OeslOner:SA
CompenY-tA1.IP RYNFAR50.Y 2'�
Dale:3/1M010 Cells of Ws mbr ar¢Ircr urM uur-,n r
Cells ollFls cob as for opsmal overrdevaaec _ _oho
Q(cIs)=C1A
Pmlecc AMBER WAVE$ CosNW sol wla ee usuRsbazetl movensA (h+t<)`
laaOon:FGRTWLLINO.CALORADOpeak Flow,Gldd
Runoff CoeHldenl,C ill lntemlly,l(INM1r
NR69 pertent tooyr 509-yr Syr SYr 10.yr 2Syr 50-yr IODY< SW"Yr
hub Name ent � Hydr ImPervioucn 3-Yr Yyr 10-yr 3SYr 50-yr 100-yr 5[ 2Syr 50-yr
SOII GI Gr.p 28.29
90.0 0.7/ 0]6 0]0 O01 OP3 9.01 <
0.99
At 3.9r 8 O.d ].23
20 0.01 001 00] 026 03d 04<
4.90
A2 339 B 6.80 5.15 21 Z0
q3 4A5 6 6.93 671 34.92
m0 Oi4 0i] Oi9 082 OB< 0.&5
Bt 5.91 C fil3 630 2993
02 4.27 B
Wo 06 0.67 070 075 OI] 06, ( 1253
4.Efi IN029 032 038 0.50 055 Ofit
83 4,39 B 400
9.i9
oa3 ]2
m az1 B
906 o.i9 076 oie 9.Bt 9e3 a0a
it
i
Worksheet for Local Street Minimum Capacity for Minor Storm
Project Description
Friction Method Manning Formula
Solve For Discharge
Input Data
Channel Slope 0.00500 fUft
Normal Depth 0.50 ft
Section Definitions
Station(ft) Elevation(fl)
0+00 0.72
0+05 0.62
0+11 0.50
0+11 0.50
0+11 0.00
0+13 0.17
0+36 0.63
Roughness Segment Definitions
Start Station Ending Station Roughness Coefficient
(0+00,0.72) (0+05,0.62) 0.035
(0+05,0.62) (0+13,0.17) 0.013
(0+13,0.17) (0+36,0.63) 0.016
Options
current rtougnness Weignteo Pavlovskii's Method
Method
Open Channel Weighting Method Pavlovskii's Method
Closed Channel Weighting Method Pavlovskii's Method
Results
Discharge 7.91 fP/s
Elevation Range 0.00 to 0.72 ft
Flow Area 3.58 ft-
Wetted Perimeter 19.02 ft
Bentley Systems,Inc. Haestad Methods SohBhiftl iftewMasler V81(SELECTserles 1) [08.11.01.031
2/5/2018 5:02:38 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203.755-1666 Page 1 of 2
Worksheet for Local Street Minimum Capacity for Minor Storm
Results
Hydraulic Radius 0.19 ft
Top Width 18.62 ft
Normal Depth 0.50 ft
Critical Depth 0.48 ft
Critical Slope 0.00645 ft/ft
Velocity 2.21 fVs
Velocity Head 0.08 ft
Specific Energy 0.58 It
Froude Number 0,89
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 ft
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 it
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity Ws
Upstream Velocity Infinity ft/s
Normal Depth 0.50 ft
Critical Depth 0.48 It
Channel Slope 0.00500 iVft
Critical Slope 0.00645 ftlft
Messages
Notes
Water is allowed to pond up to the top of street curb.
Bentley Systems,Inc. Haestad Methods Soldl4 rtlOp fewMaster Vei(SELECTseries 1) [08.11.01.03]
2/512018 5:02:38 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 2 of 2
Worksheet for Local Street Minimum Capacity for Major Storm
Project Description
Friction Method Manning Formula
Solve For Discharge
Input Data
Channel Slope 0.00500 ft/ft
Normal Depth 1.13 ft
Section Definitions
Station(ft) Elevation(ft)
0+00 1.13
0+20 0.72
0+25 0.62
0+31 0.60
0+31 0.50
0+31 0.00
0+33 0.17
0+56 0.63
0+79 0.17
0+81 0.00
0+82 0.50
0+82 0.50
0+87 0.62
0+92 0.72
1+13 1.13
Roughness Segment Definitions
Start Station Ending Station Roughness Coefficient
(0+00, 1.13) (0+20,0.72) 0.035
(0+20,0.72) (0+33,0.17) 0.013
(0+33,0.17) (0+79,0.17) 0.016
(0+79,0.17) (0+87,0.62) 0.013
(0+87,0.62) (1+13,1.13) 0.035
Bentley Systems,Inc. Haestad Methods SohH4MlSpfilImMaster V81(SELECTserles 1) [08.11.01.031
2/512018 5:03:52 PM 27 Siemens Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755.1666 Page 1 of 3
Worksheet for Local Street Minimum Capacity for Major Storm
Options
uurtent rmugnness weigmee Pavlovskii's Method
Method
Open Channel Weighting Method Pavlovskii's Method
Closed Channel Weighting Method Pavlovskii's Method
Results
Discharge 153.66 ft-/s
Elevation Range 0.00 to 1.13 It
Flow Area 57.70 ft'
Wetted Perimeter 113.67 It
Hydraulic Radius 0.51 It
Top Width 112.85 it
Normal Depth 1.13 it
Critical Depth 0.98 It
Critical Slope 0.01234 ftlft
Velocity 2.66 ft/s
Velocity Head 0.11 It
Specific Energy 1.24 ft
Froude Number 0.66
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 it
Length 0.00 it
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity ft/s
Upstream Velocity Infinity ft/s
Normal Depth 1.13 It
Critical Depth 0.98 ft
Channel Slope 0.00500 fUft
Critical Slope 0.01234 (flit
Messages
Notes
Bentley Systems,Inc. Haestad Methods Soldl'mdISpfflewMaster V8I(SELECTseries 1) [08.11.01.031
21512018 5:03:52 PM 27 Siemens Company Drive Suite 200 W Watertown,CT 06795 USA +11-203-755-1666 Page 2 of 3
Worksheet for Local Street Minimum Capacity for Major Storm
Messages
Water is allowed to pond 6-inch above the street crown.
I
I
Bentley Systems,Inc. Haestad Methods SohB§MI(�pff1mMaster Val(SELECTseries 1) [08.11.01.03]
215/2018 5:03:62 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 3 of 3
Worksheet for Swale-A-2yr
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Channel Slope 0.00500 ft/ft
Left Side Slope 4.00 ft/ft(H:V)
Right Side Slope 4.00 ft/ft(H:V)
Bottom Width 4.00 ft
Discharge 7.08 fP/s
Results
Normal Depth 0.62 ft
Flow Area - 4.06 ft'
Wetted Perimeter 9.15 ft
Hydraulic Radius 0.44 it
Top Width 8.99 ft
Critical Depth 0.40 ft
Critical Slope 0.02683 ft/ft
Velocity 1.75 ft/s
Velocity Head 0.05 ft
Specific Energy 0.67 ft
Froude Number 0.46
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 it
Length 0.00 h
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 it
Profile Description
Profile Headloss 0.00 it
Downstream Velocity Infinity fits
Upstream Velocity Infinity ft/s
Normal Depth 0.62 ft
Critical Depth 0.40 it
Channel Slope 0-00500 f ift
Critical Slope 0.02683 ft/ft
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMasler VBI(SELECTseries 1) [08.11.01.03]
312812018 3:38:24 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755.1666 Page 1 of 1
Worksheet for Swale-A-100yr
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Channel Slope 0.00500 ft/ft
Left Side Slope 4.00 Rift(H:V)
Right Side Slope 4.00 Wft(H:V)
Bottom Width 4.00 ft
Discharge 28.24 fP/s
Results
Normal Depth 1.24 If
Flow Area 11.10 ft-
Wetted Perimeter 14.22 ft
Hydraulic Radius 0.78 ft
Top Width 13.91 It
Critical Depth 0.87 It
Critical Slope 0.02182 ft/ft
Velocity 2.55 We
Velocity Head 0.10 it
Specific Energy 1.34 ft
Froude Number 0.50
Flow Type Subcrilical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 It
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity Ws
Upstream Velocity Infinity Ws
Normal Depth 1.24 ft
Critical Depth 0.87 It
Channel Slope 0.00500 Wft
Critical Slope 0.02182 Wft
Bentley Systems,Inc. Haested Methods Solution Center Bentley FlowMaster V8i(SELECTseries 1) [08.11.01.031
3/28/2018 3:39:04 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 1
Worksheet for SwaleSize-A with Freeboard (1.33*100yr)
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Channel Slope 0.00500 fHft
Left Side Slope 4.00 ft/ft(H:V)
Right Side Slope 4.00 ft/ft(H:V)
Bottom Width 4.00 it
Discharge 37.56 ft3/s
Results
Normal Depth 1.42 It
Flow Area 13.70 it-
Wetted Perimeter 15.68 it
Hydraulic Radius 0.87 ft
Top Width 15.33 it
Critical Depth 1.01 it
Critical Slope 0.02096 f 1ft
Velocity 2.74 ft/s
Velocity Head 0.12 It
Specific Energy 1.53 ft
Froude Number 0,51
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 it
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 it
Profile Description
Profile Headless 0.00 It
Downstream Velocity Infinity Ills
Upstream Velocity Infinity ft/s
Normal Depth 1.42 It
Critical Depth 1.01 It
Channel Slope 0.00500 ft/ft
Critical Slope 0.02096 fNft
Messages
Notes
Calculates Swale size including freeboard based on 1.33'Q100
Bentley Systems,Inc. Hassled Methods Solution Center Bentley FlowMasler V81(SELECTserles 1) [08.11.01.031
312812018 3:40:28 PM 27 Siemens Company Drive Suite 200 W Watertown,CT 06795 USA+1-203-755-1666 Page 1 of 1
Worksheet for Swale-8-2yr
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Channel Slope 0.00500 ft/ft
Left Side Slope 4.00 ftlft(H:V)
Right Side Slope 4.00 ft/ft(H:V)
Bottom Width 13.00 ft
Discharge 14.01 ft-JS
Results
Normal Depth 0.52 ft
Flow Area 7.88 ft-
Wetted Perimeter 17.31 ft
Hydraulic Radius 0.46 ft
Top Width 17.18 ft
Critical Depth 0.32 ft
Critical Slope 0.02705 fttft
Velocity 1.78 fills
Velocity Head 0.05 It
Specific Energy 0.57 It
Froude Number 0.46
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 ft
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity ft/s
Upstream Velocity Infinity ftts
Normal Depth 0.52 ft
Critical Depth 0.32 ft
Channel Slope 0.00500 ft/ft
Critical Slope 0.02705 ft/ft
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMaster V81(SELECTseries 1) [08.11.01.031
3128/2018 3:48:21 PM 27 Siemens Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 1
Worksheet for Swale-B-100yr
Project Description
Friction Method Manning Formula
Solve For Normal Depth
iInput Data
Roughness Coefficient 0.035
Channel Slope 0.00500 ft/ft
Left Side Slope 4.00 ft/ft(H:V)
Right Side Slope 4.00 11(H:V)
Bottom Width 13.00 ft
Discharge 57.85 ft-Is
Results
Normal Depth 1.16 It
Flow Area 20.53 ft2
Wetted Perimeter 22.59 ft
Hydraulic Radius 0.91 ft
Top Width 22.31 R
Critical Depth 0.78 ft
Critical Slope 0.02083 ftttt
Velocity 2.82 ftts
Velocity Head 0.12 ft
Specific Energy 1.29 ft
Froude Number 0.52
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 R
Length 0.00 it
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity ft/s
Upstream Velocity Infinity ft/s
Normal Depth 1.16 R
Critical Depth 0.78 ft
Channel Slope 0.00500 Rift
Critical Slope 0.02083 ft/ft
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMaster V81(SELECTserles 1) (08.11.01.03]
3/28/2018 3:49:26 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1.203.755-1666 Page 1 of 1
Worksheet for SwaleSize-B with Freeboard (1.33*100yr)
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0,035
Channel Slope 0.00500 ft/ft
Left Side Slope 4.00 Wft(H:V)
Right Side Slope 4.00 ft/ft(H:V)
Bottom Width 13.00 It
Discharge 76.94 fN/s
Results
Normal Depth 1.36 H
Flow Area 25.05 IF
Welled Perimeter 24.21 It
Hydraulic Radius 1.03 It
Top Width 23.87 It
Critical Depth 0.93 It
Critical Slope 0.01985 ft/ft
Velocity 3.07 ft/s
Velocity Head 0.15 It
Specific Energy 1.51 It
Froude Number 0.53
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 It
Length 0.00 It
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity ft/s
Upstream Velocity Infinity firs
Normal Depth 1.36 It
Critical Depth 0.93 ft
Channel Slope 0-00500 ft/ft
Critical Slope 0.01985 ft/ft
Messages
Notes
Calculates swale size including freeboard based on 1.33*C 100
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMaster V81(SELECTseries 1) 108.11.01.031
3/28/2018 3:50:18 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 1
Worksheet for SwaleSize-C-2yr
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Clarinet Slope 0.00500 ft/ft
Left Side Slope 4.00 ft/ft(H:V)
Right Side Slope 4.00 ft/ft(H:V)
Discharge 0.04 fe/s
Results
Normal Depth 0.14 it
Flow Area 0.08 fV
Wetted Perimeter 1.16 it
Hydraulic Radius 0.07 it
Top Width 1.13 ft
Critical Depth 0.09 ft
Critical Slope 0.05210 ft/ft
Velocity 0.50 We
Velocity Head 0.00 it
Specific Energy 0.14 it
Froude Number 0.33
Flow Type Subcd ical
GVF Input Data
Downstream Depth 0.00 it
Length 0.00 it
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0.00 ft
Downstream Velocity Infinity ft/s
Upstream Velocity Infinity fUs
Normal Depth 0.14 it
Critical Depth 0.09 it
Channel Slope 0.00500 ft/ft
Critical Slope 0.05210 fVft
Messages
Notes
Calculates Swale size including freeboard based on 1.33'Q160
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMaster V81(SELECTserles 1) [08.11.01.03]
3/28/2019 3:44:06 PM 27 Siemens Company Drive Suite 200 W Watertown,CT 06795 USA +1-203.755-1666 Page 1 of 1
Worksheet for SwaleSize-C-100yr
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Channel Slope 0.00500 ft/ft
Left Side Slope 4.00 ft/ft(H:V)
Right Side Slope 4.00 Wit(H:V)
Discharge 7.23 W/s
Results
Normal Depth 0.99 It
Flow Area 3.93 ft'
Wetted Perimeter 8.17 ft
Hydraulic Radius 0.48 ft
Top Width 7.93 it
Critical Depth 0.73 it
Critical Slope 0.02604 ft/ft
Velocity 1.84 Ms
Velocity Head 0.05 it
Specific Energy 1.04 it
Froude Number 0.46
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 ft
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 it
Profile Description
Profile Headloss 0.00 it
Downstream Velocity Infinity file
Upstream Velocity Infinity fits
Normal Depth 0.99 ft
Critical Depth 0.73 it
Channel Slope 0.00500 ft/ft
Critical Slope 0.02604 ft/ft
Messages
Notes
Calculates swale size including freeboard based on 1.33'Q100
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMaster Val SELECTserles 1) [08.11.01.03]
e Y Y Y (
312812018 3:44:49 PM 27 Siemens Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755.11666 Page 1 of 1
Worksheet for SwaleSize-C with Freeboard (1.33*100yr)
Project Description
Friction Method Manning Formula
Solve For Normal Depth
Input Data
Roughness Coefficient 0.035
Channel Slope 0.00500 ft/ft
Left Side Slope 4.00 ft/ft(H:V)
Right Side Slope 4.00 ft/ft(H:V)
Discharge 9.62 Wls
Results
Normal Depth 1.10 ft
Flow Area 4.86 1?
Wetted Perimeter 9.09 It.
Hydraulic Radius 0.53 ft
Top Width 8.82 It
Critical Depth 0.81 It
Critical Slope 0.02507 ft1ft
Velocity 1.98 ft/s
Velocity Head 0-06 ft
Specific Energy 1.16 ft
Froude Number 0.47
Flow Type Subcritical
GVF Input Data
Downstream Depth 0.00 ft
Length 0.00 It
Number Of Steps 0
GVF Output Data
Upstream Depth 0.00 ft
Profile Description
Profile Headloss 0-00 It
Downstream Velocity Infinity file
Upstream Velocity Infinity fys
Normal Depth 1.10 It
Critical Depth 0.81 It
Channel Slope 0.00500 ftlft
Critical Slope 0.02507 fUft
Messages
Notes
Calculates swale size including freeboard based on 1.33*0100
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMaster V81(SELECTseries 1) [08.11.01.031
3/28/2018 3:45:41 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1.203-755-1666 Page 1 of 1
Worksheet for Sidewalk Chase A - 2yr
Project Description
Solve For Headwater Elevation
I
Input Data
Discharge 7.08 tl'!s
Crest Elevation 4930.25 it
Tailwater Elevation 4930.25 H
Crest Surface Type Paved
Crest Breadth 5.00 it '
Crest Length 12.00 it
Results
Headwater Elevation 4930.59 it
Headwater Height Above Crest 0.34 it
Tailwater Height Above Crest 0.00 it
Weir Coefficient 2.98 US
Submergence Factor 1.00
Adjusted Weir Coefficient 2.98 US
Flow Area 4.07 fly
Velocity 1.74 ftis
Welted Perimeter 12.68 it
Top Width 12.00 it
Bentley systems,Inc. Haestad Methods Solution Center Bentley FlowMaster V81(SELECTseries 1) [08.11.01.03]
3/2812018 3:51:21 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA +1-203-755-1666 Page 1 of 1
Worksheet for Sidewalk Chase A - 100yr
Project Description
Solve For Headwater Elevation
Input Data
Discharge 28.24 fPls
Crest Elevation 4930.25 ft
Tailwater Elevation 4930-90 it
Crest Surface Type Paved
Crest Breadth 5.00 ft
Crest Length 150-00 ft
Results
Headwater Elevation 4930.90 ft
Headwater Height Above Crest 0.65 ft
Tailwaler Height Above Crest 0.65 ft
Weir Coefficient 3.02 US
Submergence Factor 0.12
Adjusted Weir Coefficient 0.36 US
Flow Area 98.23 ft'
Velocity 0.29 ftts
Welted Perimeter 151.31 ft
Top Width 150.00 it
I
Bentley Systems,Inc. Hassled Methods Solution Center Bentley Flow Master Val(SELECTserles 1) [08.11.01.03]
3/28/2018 3:51:53 PM 27 Siemens Company Drive Suite 200 W Watertown,CT 06795 USA +1-203.755-1666 Page 1 of 1
Worksheet for Sidewalk Chase B -2yr
Project Description
Solve For Headwater Elevation
Input Data
Discharge 8.71 ft-Is
Crest Elevation 0.00 ft
Tailwater Elevation 0.46 ft
Crest Surface Type Paved
Crest Breadth 5.00 ft
Crest Length 12.00 ft
Results
Headwater Elevation 0.48 it
Headwater Height Above Crest 0.48 It
Tailwaler Height Above Crest 0.46 ft
Weir Coefficient 3.01 US
Submergence Factor 0.72
Adjusted Weir Coefficient 2.17 US
Flow Area 5.78 ft'
Velocity 1.51 ftls
Wetted Perimeter 12.96 It
Top Width 12.00 ft
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMaster VBt(SELECTseries 1) [08.11.01.031
3/28/2018 3:52:25 PM 27 Siemons Company Drive Suite 200 W Watertown,CT 06795 USA ♦1Q03-755-1666 Page 1 of 1
Worksheet for Sidewalk Chase B - 100yr
Project Description
Solve For Headwater Elevation
Input Data
Discharge 34.92 fP/s
Crest Elevation 4929.70 it
Tailwater Elevation 4930.63 it
Crest Surface Type Paved
Crest Breadth 5.00 it
Crest Length 200.00 it
Results
Headwater Elevation 4930.63 it
Headwater Height Above Crest 0.93 ft
Tailwater Height Above Crest 0.93 it
Weir Coefficient 3.06 US
Submergence Factor 0.06
Adjusted Weir Coefficient 0.19 us
Flow Area 186.74 W
Velocity 0.19 fUs
Welted Perimeter 201.87 ft
Top Width 200.00 ft
ii
Bentley Systems,Inc. Haestad Methods Solution Center Bentley FlowMaster Val(SELECTseries 1) (08.11.01.03]
3/2812018 3:52:54 PM 27 Slemons Company Drive Suite 200 W Watertown,CT 06795 USA 41-203-755-1666 Page 1 of 1
DETENTION VOLUME SY THE MODIFIED FAA METHOD
Project:Amber Waves
Basin 10:Pond A
(For catchments less than leg acres only.For larger catchments,use hydrograph rowing method)
(NOTE.for celclvnenl9 larger than Hire,CORP hydmgraph and I.W.u.g are ir. znded)
Determination of MINOR Detention Volume Using Modified FAA Method Determination of MAJOR Detention Volince,Using Modified FAA Method
l De=on Information Ift lss Design Nfomulian Ilnoull:
CaYlaneMOrewge lmpen+qusM I== fi023 eM CacrameMOrangelrrom'.sress 1.- 6023 peneM
C a'sMneMvdarr,BMea A= s Cesirean101anage Area A= I1366zcros
PreffewbpmeMMiC55a1Graub TIN= e.C,O PreEero'cpmenfIRrS..'GVe Tppo= AB.C.mD
R¢hm P¢Mdln Oelen'an Corvr01 T= as 125.10.25,50,ar 1001 ReLn Peiutl for Ocicnt.n Comol T= -j2,5,t0.2650.arm01
Lmeol CorceMY.bn0Walenhad TO= Mea True of Counin,on of iNversned To- 4 ru+ez
Na.rtl4 Unt Re!¢ase Rase q= Wye Aroaxbk Uelfis. .Rase p= mzlave
OneYov Pecoccon P+= 062 OreJwvPreopna[on E.
286 natas
Oeel90 RaNNIIIOFFormula 1=Cj PJ(C,-T,)a05 Donani RaNf.1110FFarmula 1=C�P+I(gHd•C1 p850
Coeffrt'eMOro Q= 2850 CoaffitimiOre C,=__
COelfo'cel Ca= 10 CceffltieMT'w Cc= 10
Coefic'enlTNea C5= O]89 Coamozenc Tum. Cs= 0799
Def,min,finn or Avormour Oufflaso from tho Basin'Calculatedi- neterindriation of Averion,Outflow from the Basin fCalculated],
1 R.111c.fSOem C= 037 R-1f Co.11-ra C= OS]
,1-1..Runolf Op%e= 8n2 cis IMbNP.arflugll Po-n= 430E C1s
A'-Va Peak011I.File 0pu, 228 cfs Ardanif'¢Poisrurb NRak PoaN= 228 old
N.V.FM Mm.r Slane.Volume= 7351 cublcleel Nod FAA Nalor St..,ie Volume= 72.03 cubic feel
M on FM Minor Storage Volume= 9All re." Nod FAA Major Storage Volume= 1.667 r..n
Raman R3nla'I tend. Adyz Average c OWlox $Nrrye RaNal Resdal InMN ur'-snue Asv V%. c OuHb'N Storage
Tore n Imere, Vourne Facl 0%npN V..wn ve+me O'raan beiratr Vicuna. rxlm Cocoa, Volrne Vdmm
mn[es imeres" om feel cfs al -T d m'm095 ieMs]h a art ets yefeel a 4-1
- 0do 0ON 0.SO _ 000 00uo _ own 0 one ONO _ 000 000 _ 0ffoo 0a00
2 329 ONO 100 228 Boos 0032 2 114i 0205 TOO 228 0.006 0.199_
d 291 0068 100_ 228 0013 Boss 6 10.16 0361 100 228 000 0351
6 262 0091 100 22a 0.019 _ 0072 6 _914 UAW _ IN 228 0019 O471
B 239 AIll IN _ 220 0025 Boss 8 833 0596 _ TOO 228_ 0025 057t
ID 2. 0.128 1SO 228 0031 00% 10 i6T 005 low 228 0031 085b__
iP 201 0142 _ IN - 228 0038 at" 12 ill 0]63 IN 228 - 0038 0125
155 14 ISO 0 IN 228 0046 0111 14 554 0831 I00 228 0044 0]0]
16 1.T9 0.t66 094 - 004] 0.119 16 623 0.891 O94 213 0047 08e4
IB 169 0.1]6 _ 0.9 202 .0% 0.126 18 588 0:946 0.89 aW ONO 0In.
20 160 0185 ON _Inc, dew 0132 w 557 005 085 to 0053 0942
22 142 o.le4 Dios f% Boss 0,137 22 529 1040_ 052 166 0ass 0984
'1 24 TAB Owl 019 I80 0060 s142 2l 505 1082 0.i9 Ias ONO 1021
11 26 1.38 0303 OW V5 0063 OA6 26 L82 I.I20 0,T] 175 0053 058
28 132 0215 Ol5 ill ONO old. 28 4.W 1.156 0]5 1.71 0066 1090
30 t21 0221 073 167 Bass 0.152 So 4.d4 11. 0.73 15, 0069 1,121 _
32 1.22 0227 0]2 1W _ 0012 OA55 32 427 1221 0.]2 104 0072 f.b9
34 118 _ 0233 0.71 161 0075 _ OIST 3d 412 L25t 0l1 Let _0075 1175
36 114 0238 069 158 0Ora 0160 Be 3W 1275 _ 069 ISS ST'd 1200_ _
38 LID 0243 O6B IN ON. 0.161 3B 384 tan O" ISe OOS2 12"
L0. 107 0240 O68 1S4 0065 0163 40 372 "no am IU 0055 1245
61 103 0252 087 152 Boss__ 0.164 42 36l 1351 _ 06] 152 _ OaBe 1266
44 1an 02% ass I50 0091 c%5 44 350 W]] a" 150 0091 _ I266
46 098 _02fio 065 1<B DO" 01. 40 340_ 1599 00 1.48 0094 t3N
4B 095 02" O6s 1A] 009T_ 0.161 48 331 1420 _ San IA] Offer 1322
50 092 02" aM sA6 else 0.168 50 L�221440 0W Il6 0.100 1339
52 0.90 02I2 00 144 0,103 O.I88 52 1A59 0f3 IA6 0.103 I356ON 021. 063 1A3 010] 0168 54 1.00 _ Os3 1.13 016r 13]I
Be Oas ova ass 1.42 O.I to 0.169 56 1495 063 T42 0.Ila 1386
58 084 0282 062 TO of i3 0.169 5B ISi3 062 Ili 0113 IA0.
60 082 0285 062 IAO O.It6 0169 60 1.SSo - 062 IAO0116 Ldld62 ON 0288 all 139 oII9 olof 62 1548 .61 139 OA 19 142]
Ol8 0291_ 0fii L39 0.122 0.168 64 IS82 061 139 0.122 1440
66 0.]] 021 O61 t3B 0125 Ora 66 1.SA O81 133 O.I25 1.452
68 0]5 .19. 060 13] OA29 OAS, 68 Tied_ OSo 13] 0.129 I463
]0 0A 0.299 060 13] 0132 0,16i ]0 I ar, 0 0 13] 0.132 14]5]2 0.72 0302 .60 136 elite O.IBT ]2 1.620 O60 f36 SAM]4 0]I 0304 059 Lm 0.138 O.ISF ]4 1.630 05, _IS SABA L496
76 0"0 0307 059 Las 0.141 0166 1. 2A3 tsar 059 135 0.141 15%
]8 O6B 0309 0.9 134 0,144 else Te 2.38 1.0 059 134 Slow 151.
SO San 0311 059 136 0.N7 __a", BO 234 1,673 059 1'M dial 1526
82 ___O68 0314 1159 133 also 0,10 82 2d0 1685 _ 059 133 0160 IS35
Ba o65- 0318 .58 133 0,154= OA62 81 226 1 B9710 - 0SO 133 OrlOA54 _1544-
68 064 0320 058 132 O.ISI Staff 222 1.]01 05. 132 SAN 1552
BB 062 0322 O58_ 1.32 0.153 0.159 BeBB 2.19 1321 am 132 0.163 L569
90 062 0324 O56 132 0.163 0159 90_ 2.12 1132 0Y 132_ 0.163 _ 1569_
92 ON 0324_ 058 "1 0,169 SAW 92 2.0 Ilf3 047 13I 0.16a.9 19r
96 O60 0328 051 1So OA72 0.15] ON 2% Li54 _ __OS] lID _ 0169 I585
92
98 __eba 0328 05T 130 OIT2 _ 0.155 96 20B il7a_ 057 130 0.172 1.592_
1 _ 05B 0330 057 130 _ 0.I76 0.155 _ to 2.G3 1.773 05T 1.30 0.176 16NO
%
_IW 09 _0332 057 1311 0.119 0154 IW 200 _ I185 051 130 0.179 1.606
102 ON _ 03U 057 t29 0.182_ 0.152 102 19] LISS _ 05r 139 061.a lA13
1" O56 Begs OOr 129 clan 0.15t I" 1.94 two 05) Ifs_ 66185 1620_
IN o55 _ OJ38_ Oct _ "a 01180 Tied 10. 192 IBN a5] I 0.188 lain
t08 - Ofid Dail 056 129 0.191 _O.MS We 169 1824 _ _O55 - 129 0let - I.B33-
TO O53 0.341 058 128 0.194 014T 110 187 1833 O% .8 0,194 1639
_112 053 0. 058 "a 0.I.8 OA45 112 184 IB42 0Be tan 0198 1645
114 052 OJaS O56 Ifa 0201 0144 114 182 1851 _ _O50 128 _ 0241 1.01
116 OSi 0316 OBe 128 0101 0.142 118 1.]8 I660 O56 12 0204 _ 1556__
_ 1to 051 ONa_ O56 13] _ 0.20r 0.161 Its I.]i 1.6. 056 _ 13] 020T _ Lfifi2 _
110 ogle I2] .I ] fi 0210
Nod FMNlnor Msms.VoWme(cubla ni= 1,151 Nod FM Major Senate Volume(cubic A). 72,633
Nod.FM Minor Stares*Vdoma(acre A)- 0.1687 Nod.FAANajor Manage Volume(acre Of= iefi14
UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2.M.Released November 2g13
Ponca,1NT,m,on Q 3411EW ORouluirE cne,Vert fed FM 11.J 1 S,4'51 PM
i
DETENTION VOLUME BY THE MODIFIED FAA METHOD
Project:Amber Waves
Basin ID:Pond A
Inflow and Outflow Volumes vs.Rainfall Duration
1.6
1.8
1.4 •
1.2 �
1
E
>° 0.8
0.6
0.4
0.2
0
i 0 20 40 60 80 100 120 140
Duration(Minutes)
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UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2.34,Released No.e ,2013
P ALOdeterfiat_Y[UWWGM1'MGELsm,IM4li¢dFM 3!W018,451 MA
STAGE-STORAGE SIZING FOR DETENTION BASINS
Project: Amber Waves
Basin ID:Pond A
a+n Slk SkpeZ pv 'S�SIeeL rava�.
4 Hn Fb eN Fbr
1r: � ,.
l -
1KDR�'C se flee,
L__ < r Sileflryei �ti
4 � L L
Design Information jigged): Check Basin Shang.
Width of Basin Ballom,W 0 Right Triangle OR...
Length of Boom Bottom,L =�# Isosceles Triangle OR...
Dam Sideslope(H:V),]a= N0 Ruching te OR...
Circle/Ellipse OR...
Irregular (Use Owunde values in cells G32:G52)
MINOR MAJOR
Storage Requirement from Sheet'Modified FAA': 0.1] 1.fi7 acre-8.
Stage-Storage Relationship: Storage Requirement from Sheel'Hydragmph': acre-#.
Storage Requirement from Sheet'FullSpecbum`. acre-ft.
pLabelsWater Side Basin Basin Surface Surface JBa.
Surface Volume Target Volumes
Surface Slope Widthat Length at Area at Area al Area at Below for WOCV,Minor,Elevallon (H:V) Stage Stage Stage Stage Stage Stage &Major Storage
h 1tl0 it 0 ftR' Usercres acre-R Volumes
fin ul Below El. loui ul midget but ul OverideI.O.Wl foul utl (tor gal seek4927.00 tin oil 260740.599 0.000
4927.10 0.00 0.00 28 781 0.661 0.063
4927.20 0.00 0.00 31489 0.723 0.132
4927.30 0.09 0.00 34 197 0.785 0.208
4927.40 0.00 0.00 36904 0.847 0.299
. 4927.50 0.00 0,00 39612 0.909 0.377 0.317
P
4927.60 0.60 0.00 40,960 20,450 0.940 0.469
4927.70 0.00 0.00 42,308 24,613 0.971 0.565
4927.80 0.00 0.00 43,656 28 912 1.002 0.664
4927.90 0.00. 0.00 45,004 33,345 1.033 0.765
4928.00 0.00 0.00 46,352 37,912 1.054 0.870
4928.10 0.00 0.00 47,947 42,627 1.101 0.979
4928.20 0.00 0.00 49,542 47,502 1.137 1.090
4928.31) 0.00 0.00 51137 52536 1.174 1.206
4928.40 0.00 0.00 52 732 57 729 1.211 1.325
4928.50 0.00 0.00 54327 630B2 1.247 1.44E
4928.60 0.00 0.00 55.922 68.595 1.284 1.575
4928.70 0.00 0.00 57,517 74 266 1.320 1.705
4928.80 0.00 0.00 59 111 80 098 1.357 1.839
4928.90 0.00 0.011 60,706 86 089 1.394 1.976
4929.00 0.00 0.00 62,301 92,239 1.430 2.118
100 VR 4929.10 0.00 0.00 64127 98561 1+472 2,263 2.317
4929.14 4929.20 0.00 0.00 65952 105064 1.514 2.412
4929.30 0.00 0.00 67,777 111,751 1.556 2.565
4929AO 0.00 0.00 69603 118620 1.698 2.723
4929.50 0.00 0.00 71,428 125,671 1.640 2.885
4929.60 0.00 0.00 73254 132906 1.682 3.051
492970 0.00 0.00 75079 140322 1.724 3.221
4929.80 0.00 0.00 76 904 147,921 1.765 3.396
4929.90 0.00 0.00 78,730 165,703 1.807 3.574
4930.00 0.00 0.00 80555 163667 IA49 3.757
4930.10 0.00 0.00 81752 171783 1.877 1944
4930.20 0.00 0.00 82949 18001a 1,904 4A33
4930.30 0.00 0.00 84,146 188,372 1.932 4.324
4930.40 0.00 0.00 85,342 196,847 1.959 4.519
4930.50 0.00 0.0) 86539 205441 1.987 4.716
#N/A #NJA
#N/A I 4N/A
#NIA #NIA
#NJA #NJA
#NJA #NJA
#WA #NJA
#NIA #NIA
11N/A #N/A
PandA_UO-Deten9on_@ 34_NEW DRAINAGEAsm,Basin 3/2612018,4:52 PM
i
STAGE-STORAGE SIZING FOR DETENTION BASINS
Project:
Basin ID:
STAGE-STORAGE CURVE FOR THE POND
4931.00
4930.50
4930.00
4929.50
a
x 4929.00
w
rn
m
rn
4928.50
4928.00
4927.50
4927.00
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50 5.00
Storage (acre-feet)
PondA_UD-Delention_J.34_NEW DRAMAGE.Asm,Basin 3128/2018,4:52 PM
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RESTRICTOR PLATE SIZING FOR CIRCULAR VERTICAL ORIFICES
Projeet: Amber Waves
Basin ID: Pond A
Oia.
TO
% 0 0 /— 0 0
O n O O
Y.
k1 Vedical N2 Vedical
Sizing the Restrictor Plate for Circular Vertical Orifices or Pipes onoutl Orifice OMce
Water Surface Elevation at Design Depth Efiar WS= 4929.14 feet
Pipc/Wtr1kcal OMce Entrance lined Elevation Elee lmad= 492700 feet
Required Peak Flow through Office at Design Depth 0= 2.28 cfs
PipeNedical Onrc,Demeter Dia= 18.0 Inches
Office Coeffdenl C.= 0.61
Full-flow Capacity(Calculated)
Full-flow area X to sq 0
Half Central Angle in Radians Theta= 3.14 rad
Full-flaw capacity Of= 10.2 cfs
Percent of Design Flew= 448%
Calculation of Odflce Flow Condition
Half Central Angle(G<Thela<3.1416) Theta=[Met.
(ad
Flanamea fb= sit it
Top weft of Office(inches) 1 Inches
Height from Inaerl of Orifice to Bottom of Plate(feel) Y.= feet
Elevation of Bottom of Plate Elev Plate Bellpm Edge= feet
Resultant Peak Flow Through Office at Design Depth Da=
Width of Equivalent Rectangular Vertical Orifice Equivalent Width= 0:89 fast
Ili
PandA_UD-Detention_v2.34_NEW DRAINAGE.Amp,Restdclor Plate 3128/2018,3:58 PM
STAGE-DISCHARGE SIZING OF THE WEIRS AND ORIFICES(INLET CONTROL)
Prolecb Amber Waves
Basin 10:Pond A
P.-nand n.J.,I IEaa+JVJ, R.a, f P--r+.
Pet InrJ+a315v9n 5uacl x+ r -Inca
Current Routing Order Is 43 Li LI
Oecion Wfomwtinn Meutl: M1 Hero. 42 Hmia. M1 Vert. M2 Ved
Circular ON,: Dauseterinmches Qia.= ina,ea
OR
Reclou,nar Opera,, Widlhin Feel W= 8N 0.89 n.
LBrghlHeghtfor Ventroh L.,H= 3.N 0.37 1 !1.
Percentage of Open Area After Trash Rack Reduction %o,pen= 50 1N
Onfce Coefficient Ca= 011 0.61
Was Coefficient C.71 2.a4
Ounce Elevation patlom for Verucat �=j 4928.00 1 1 4927.00 fl.
Czlcu Wien of Collection Ca eaeit¢
Net OpeNn9Area(aile,T..h Rack Reduction) 7b= 4.50 0.33 sq.ft.
OPTIONAL:User-Ovende Net Opening Area A,= sg11
Pefi.d.ras Weir Lengh L,= 900 fl.
OPTIONAL:User-Owride Weir Length L,=mO-
TopElevationofVerticalOnfica Opening,Tap= 492T37 it.
Center Elevation of Vertical Orifice Opening,Can= 4927.19 1
Routing 3: Single Stage-Water flows through WOCV plate and#1 horizontal opening Into#1 vertical opening. This flow will be applied to
culvert sheet(#2 vertical&horizontal openings Is not used).
Hodzontal Orifices Vertical Odfices
meek Water WOCV M1 Hertz- M1 Her¢. 121-loriz. M2 Hm¢. M1 VerL M2 Vert. Total rargel vw.res
1MWQLV,MYIY, fink.. P131GRiser Was 011rlce Weir Orr. Cat.Wo Collection Collection fs WOCV,Miw.
M Mlapr fifer.'¢ Elevation Flow Flow Flow Fbw Flow Capacity Capacity Capacity 4Napr smra9e
W&ekvaalvs It cfs cis are Us cis cis cfs fits Vmv
lineup iLrked User-Inked) tau WI lou 11 tou W II teal u.n out ul
4927.00 ON 000 pop 0.00. Ono 010 Ono 0.00
4927.10 0.N 010 0.N Ono 0.00 OA0 0.00 0.00
4W7.20 am 0.0 o.N 0.00 Ono 0.28 0.00 0.00
4927.30 0.00 oleo 0.N Ono 0,00 0.51 Ono 0.00
4927AO 0,01 0.N 0.N 000 000 0.75 0.0 not
WQCV4927.43 4927.50 0.01 0.N 000 &00 0.60 0.91 0.00 0.01
4927.4 4927.60 0,02 ran 0.00 0.00 0.131) TU 0.00 0.02
4927.70 0.03 0.N 0.N 0.N 000 T16 (TOO 0.03
4927.80 a." 0.N 0.00 ON ON 1.27 0,N 0.04
4927.90 ON 0.N 000 0.00 0.N 1.37 0:N 0.04
4928.00 Tog Ono e.N 0.N 0.N 1.46 0.N tons
4928.10 0.06 011 &97 OM 000 1.55 0a 0.87
4928.20 0.07 2,29 985 ON 0.00 1.63 one 1.63
4928.30 008 420 12A7 0.N 0.00 111 Of10 1.71
4928.40 009 6.47 1393 0.00 000 1J8 0.N 1.78
4928.50 0.09 9.04 15.58 000 000 1.85 0.N Cas
4928.60 0.10 11.88 17,06 0.00 0.N 1.92 ON 1.92
4928.70 0.10 1497 18A3 0.00 Ono 1.99 eN 1.99
4928.80 0.11 18.29 Min 0.00 GIN 7.05 0.N 2.05
4928.90 0.11 21,82 20,90 0eo 000 2.12 0.00 2.12
4929.00 0.12 2556 22113 0.00 0.00 2.18 0eo 2.19
4929.10 0.12 2R49 23AO 0.00 0,00 2.24 000 2.24
4929.20 0.13 33,60 24A3 Ono 0.00 229 0.00 2.29
4929.30 0,13 37.89 25A2 Ono 000 2.35 0,00 2.35
4929.40 0.13 IZU Moo 0.00 0.00 2.40 0.00 2.40
4929.50 0.14 46.96 2&98 000 0.00 2A6 ON 2.46
4929.60 MIA 51.73 2786 coo 0.00 2.51 ON MIA
4929.70 MIA 5865 2872 one 0.00 2.56 ON MIA
4929.80 MIA 61.73 20.55 0.N 010 2.61 TOO MIA
4929.90 MIA 66.94 N36 one Ono 2.66 0.N MN/A
4930.00 MIA 7229 3IA5 0.N 000 2,71 0.N MIA
4930.10 MIA 77.78 31.92 ON 0.00 2.76 0.N MIA
4930.20 MIA 83,41 32.67 000 000 2.80 one MIA
4930.30 MIA 89-16 3341 0.00 0.00 2.85 0.00 MIA
4930.40 MIA ogre 34.13 0.N 000 2.90 eon MNIA
4930,50 MN/A 101.03 1 34.83 0.00 ON 294 0.00 MN/A
MIA MIA MN/A MNIA MIA MIA 0.00 MN/A
MN/A MNIA MIA MIA MN/A MNIA 0.00 MIA
MIA MNIA MN/A MIA MIA MIA 0.00 MIA
MIA MNIA MIA MIA MIA MIA 0.0 MNIA
MIA MIA MIA MNIA MNIA MA ON MIA
MIA WA MIA MIA MN IA I MNA one MIA
MIA MN/A MIA I MIA MIA I MIA ON pN/A
MNIA MIA MIA I MIA I MNIA I MIA 0.N MIA
PondA LID-Detention V2.34 NEW ORAINAGE.Asm,Outlet 3/28I2018,4:02 PM
STAGE-DISCHARGE SIZING OF THE WEIRS AND ORIFICES(INLET CONTROL)
Pro)ecl: Amber Waves
Basin ID:Pond A
STAGE-DISCHARGE CURVE FOR THE OUTLET STRUCTURE
4931
4930.5
4930
W
v
4929.5
W
Ol
w
W
O)
to 4929
4928.5
4928
4927.5 —
4927
0 0.5 1 1.5 2 2.5 3
Discharge (cfs)
PondA UPDelenton v2.34 NEW DRAINAGE.Asm,Gullet 3I2812018,4:02 PM
i
STAGE-DISCHARGE SILNG OF THE OUTLET CULVERT(INLET vs.OUTLET CONTROL WITH TAILWATER EFFECTS)
Prolecl: Amber Wevea
Basin In:Pond A
_.� e ID O Ir
Status:S out Contains Enms See C dEu of Rouge s a.
Design Information Iliin&
Custer QNM:Banal Pameter in lMps D= 18
CustarC an le4(Edge Type(rMosa rrmn µ6Jonn KB uare Entw Ibad2aa8n
11H.
Box(Wen:BauciYk13ft(Rfs0)in Feet IkyN IRse)= n.
BoxCWen:Banal lYdlll(Span)a Feet \YdU 8 an= IL
BoxCWen:Into Edge TyPo(choose fromgddo'nnfin era EE a.193.15E ftatm Wm na'I
N Iotwues W= 1
Kiel EknN'n al Gl.M linen le..= 4927.00 it.aas.
0WeI EImLwre103.eM1 ImM Oe..= 4926]5 f.no,
CJrtrl LergN n Fee L= 5f10 ft.
Marrends Rsuknss = Oo1J11
Bem Less Coefrcnn K,- o.m
Eno Loss Cnelkane K,= IGO
Design Information lcalculatedl:
Encece Loss Coefnuen K.-
fiction Loss ConditionsW=
Stan or At Loss eoelruene 14=
OnionInel Condemn Ceerccxn C.=
M'remm Eree9y ComRun Coefrxien K1_=
Calculations of Culvert Ca aci out ut:
Water Sure. Tessa., CuNert CuNert Mosinee CanlrolOng Iran
Maine. Surface Inle4eonlrol 0ulle4Conlral W N OCUert CUNan E9uatlan
From SM1en Elevalfon I'l.ae Hosanna Frain Sken Flexeala Bsetl
"Basle ft cra c!s -Ou1M11 as
R.linked) mll k-11 eN (indent) crf linked eW N oN
e927,00 Beat
e92],10 O.oO
e927620 a..
a92a30 am
4927.10 D.ol
4927.W 0.01
e927.60 0.02
492>.80 0.08
8927.90 a."
492&00 0.05
4928.10 0.87
4928.20 1,61
4929.30 1.>1
4941.40 A8
e928.50 1.85
4928.50 1.92
492a10 1.99
1920.80 105
4928.90 112
4929.00 2.18
4929.10 2.28
492"0 2.29
a929.30 2.35
4929.40 2A0
492950 2A6
4929.60 MA
4929.70 BWA
4929.80 aWA
4929.90 9WA
e9306m 9WA
49MLI0 9WA
e930.20 1 BWA
e930.30 BWA
e930A0 8WA
4930.50 8WA
0.00 MA
0.00 MA
0.0 MA
OWN MA
0.01, MA
D.m 9WA
D.m MA
D.Oo BWA
PrcEA U0,0mustcn W.3J iEW DR MGE sonw W.ert WM2018.4:10 PM
i
STAGE-DISCHARGE SIZING OF THE OUTLET CULVERT(INLET vs.OUTLET CONTROL WITH TAILWATER EFFECTS(
PM&cl: Amber Waves
Basin In:Pond A
STAGE-DISCHARGE CURVE FOR THE FINAL OUTLET PIPE CULVERT
4931.00 -
4930.50
4930.00
4929.50
W
W 4929.00
w
m
IB
N 4928.50
4928.00
4927.50
4927.00
0.00 10.00 20,00 30,00 40.00 50.00
Discharge (CIS)
Pw WOenuoo J1.31 NEW OMMGEd ,GAM W210MM4:10PM
i
STAGE-DISCHARGE SIZING OF THE SPILLWAY
Project: Amber Waves
Basin ID: Pond
Design Information(input):
Bottom Length of Weir L=M309
feel
Angle of Side Slope Weir Angle= degrees
Elev.for Weir Crest EL.Crest= feet
Cost.for Rectangular Weir C„.=
Coef.for Trapezoidal Weir CL=
Calculation of Spillway Capacity(oulpull:
Water Rect. Triangle Total Total
Surface Weir Weir Spillway Pond
Elevation Flowrate Flowrate Release Release
#. c/s cis cis cis
(linked) (output) (output) (output) (output)
4927.00 0.00 0.00 0.00 0.00
4927.10 0.00 0.00 0.00 0.00
4927.20 0.00 0.00 0.00 0.00
4927.30 0.00 0.00 0.00 0.00
4927.40 1 0.00 0.00 0.00 0.00
4927.50 0.00 1 0.00 0.00 0.00
4927.60 0.00 1 0.00 0.00 0.00
4927.70 0.00 1 0.00 0.00 0.00
4927.80 0.00 0.00 0.00 0.00
4927.90 0.00 0.00 0.00 0.00
4928.00 0.00 0.00 0.00 0.00
4928.10 0.00 0.00 0.00 0.00
4928.20 0.00 0.00 0.00 0.00
4928.30 0.00 0.00 0.00 0.00
4928.40 0.00 0.00 0.00 0.00
4928.50 0.00 0.00 0.00 0.00
4928.60 0.00 0.00 0.00 0.00
4928.70 0.00 1 0.00 0.00 0.00
4928.80 0.00 0.00 0.00 0.00
4928.90 0.00 0.00 0.00 0.00
4929.00 0.00 0.00 0.00 0.00
4929.10 0.00 0.00 0.00 0.00
4929.20 0.00 0.00 0.00 0.00
4929.30 0.00 0.00 0.00 0.00
4929.40 0.00 0.00 0.00 0.00
4929.50 0.00 0.00 0.00 0.00
4929.60 0.00 0.00 0.00 0.00
4929.70 6.64 1 0.04 6.68 6.68
4929.80 18.79 0.22 19.01 19.01
4929.90 34.53 0.61 35.14 35.14
4930.00 53.16 1.25 54.41 54.41
4930.10 74.29 2.18 76.47 76.47
4930.20 97.65 3.45 101.10 101A0
4930.30 123.06 5.07 128.13 128.13
4930.40 150.35 7.07 157.42 157.42
4930.50 179AO 9.50 188.90 188.90
#N/A #N/A #N/A #N/A #N/A
#N/A MIA #N/A #N/A #N/A
#N/A MIA #N/A #N/A #N/A
#N/A #NIA #N/A MIA #N/A
N
N/A #N/A #N/A #NIA #N/A
NIA #N/A #N/A #NIA #N/A
NIA #N/A #N/A f!N/A #N/A
NIA #N/A #N/A I #N/A #N/A
PondA_UD-Detention_v2.34_NEW DRAINAGE.Asm,Spillway 3126/2018,4:54 PM
i
STAGE-DISCHARGE SIZING OF THE SPILLWAY
Project: Amber Waves
Basin ID: Pond
STAGE-STORAGE-DISCHARGE CURVES FOR THE POND
Storage(Acre-Feet)
0 1 2 3 4 5
4931
4930.5
4930
i
W 4929.5
d
a
� 4929
N
4928.5
4928
i
4927.5
1
4927
0 50 100 150 200
Pond Discharge(cfs)
PondA_UD-Detention_V2.34_NEW DRAINAGE.Asm.Spillway 3126I2018,4:54 PM
DETENTION VOLUME BY THE MODIFIED FAA METHOD
Project!AMBER WAVES
Basin ID:POND B
(For catchments less than 160 acres only.For larger catchments,use hydrograph routing method)
(NOTES for catchments larger than 90 acres,CUHP hydrograeh and rooting are recommended)
Oetemdnation of MINOR Detention Volume Using Modified FAA Method Dete,minatlon of MAJOR Detention Volume Using Modified FAA Method
resign johmestian INnIHI: Dmmu Information Hi l 111
Co.:o Oranzge lmp¢MoaralleN rearm MOn'.a3elmperv.Wsmis I== 12N portent
Caoni,no t�9e Area A= ne coacmeMO,a'raaa Nea A= 14US ones
PmearoopmenllatC8..Gaup Tyf¢= J �I
B.C,orD PreEew`amer.lelC6661 Gw Trys= AB,C.orO
Reran PenMl-Drume-C-10 T= rs12.5.10,25.50.a100) ReAvn PMgrilm ONamoo CwNd T=�erel 310'11,1 .or 1001
Tool Conte rhanol Wa:en"a0 TC= M Tonal COrceNa:anal WXerslsE To- n=:
Asurr�`e Util Release Gore 9= abve M. .tMlReacaTSe a= ILWC
Om-bv P-bution P,= O62 laa OmJ precplran P,= 2B6 ,[hero
Oetl8n Ra1n1a111OFFermula I-C(PJ(Ca1T.PCr DeNBniedonIIOF Formula 1=Cj PraCaeT.YCr
CcetrpeMOre Cr= 1050 CO¢I!yMOre C,= 28ZO
CaetvardTaa Cr_ 10 Cadocna N.o Cr= 10
Caelr,umi Tee. Cl- 0]89 Cadfictere Tbee Cr= 0,789
natenedInguinn of AVerma Outficoa finern the Basin(Calculated), Determination of Averane Outflow from the Basin lCalculartang:
Banco Coefficient C= 047 R."CcellitieM C= 263
IMax PeARuoll o''.n= 13N cls hrbriM.Rmoll Op i1= 6096 crs
N orabb Prok"lox Rate Opan1= 211 .1. APo.b'e Pera Ozer Ra'A OpaN= 2.91 CIa
Mad FM Minor Storage Volume= 13,852 materiel Nod.FAA Major S10ra9e Volume= IbbS mblefeet
Mat FAA M lnorStorage Vol 0318 r.-a Nad.FAA Nelor role,.,.Volume+ 2388 .A
R.MYI Rental 111 Ad;usM t Arer]0 q]Jlax 5!mal R3Ny1 RaNtl (.a Adiusane,4 Andage OWgx Samoa
Deafen to.-ty Vo'ume Famr oddrx VA.na V.'um OI.- many VOLne FxW, Orders VoNm Vorum.
ronjuS InURs/M aeMeel cis 2VPIe¢I -,a., ,n:Nes aeJaslM me,feel m. do som fee, acm1eel
2 _ 329 0W2 led 29f OOb 00. 2 11d] 0290 1.00 291 me____ 0182
d 2,91 0.110 100 291 0.016 DO" 4 _ 1016 ObM IN 291 Sate SAN
fi 262 0f45 IN 22, 0024. 0Jm_ _ 6_ 94 0694 IW sel 0024 SAM
_8 _ 239 0.180 IN 291_ 0032 0.t18 8 an Sets _ Led 291 0032 _ "11
_10 .10 0207 100_ 291 OOIO 0J6] 10 767 0S. 100 29, _ _ONO 0.
- 12 204 - am, 100 291 O.bB OJ03 12 7.11 1.079 1On 291 0No - 101
N Too 0251 100 29, 0056 0195 14 666 I.A5 tan 291 0056 1.119
_I6 1.]B 02]0 ON 2]3 .060 0210 I6 613 1261 OW 2]3 OON 120,
10 169 0286 099 259 0.084 0222 t6 588 1,330 0.89 Sea Sam 1.214
10 ISO 03b _ 085 OAS 0068 D233 1. 0.57 1408 _ D85 OAS 0068 1340
_22 152 0315 082 238 0072 0243 22 529 1.472 002 238 D07Z I400
I 24 1L5 0327 079 231 0076 0251 24 505 101-- 0.79 231 am _ Ia55
26 1.38 Q3J9 0]] 2Od 0090 D259 26 402 I585 0]] 224 &ON I505
28 132 _SON 0.75 2.19 OOS4 0286 28 4.62 1.06 0t5 2,19 GAIN 161,
30 127 aON 0.73 214 00N 0272 30 646. 1.683 0l3 2.14 D008__ I5us
32 122 0370 072 20a 0092 02T] 32 42] 1728 032 2W 0092 I nli
34 1.18 OH]9 0.i1 2W Sage _0282 _ 34 4.12 1.]]0 07I 20 ONO I1i1
_ 36 114 038] 0.69 202 OIW- 028T 36 - 397 1809 0.9- 2,02 0,100 1"1
0 30 1.10 0395 a 199 ..1" 0291 39 384 190 0,68 I'm 0.m4 I'll
40 10] 0403 068 I9] SAN 0294 40 312 IZ92 on Iw 0.108 V za
42 103 _ OL10 067 196 D112 _ 029] 42 361 1916 _ 067 I'm0.112 _ IBOa
46_ tda OAI] 086 192 O.I Ifi 0me 44 350 1In ON 192_ 0.1T Id"
46 09B Od23_ D65 I90 0.120 0303 46 300 I9]9 065 1m 0,120 _18i9
-So _ 095 04. - ON 188 0124 _0305 40 331 - 2009__ 065 188 KM
_ I685
50 092 OA% IT" I86 0.120 can' 50 322 2037 a6d 1M INN
52 090 OA42 063 105 0132 03M 52 314 2065 063 185 1932
54 0so 0447 063 I63 0336 0311 be 306 2091 _ 053 1as 1955
N am OA53 063 182 0.140 D.12 56 2" 2,117 069 1.82 _ 19]6
be am 0158 052 I01 0.IM D313 58 _2W 2.141 062 lei 199]
60_ O82 0463 062 1 0 0,149 0315 60 ON - 2.10 O62 1.0 Oats62 080 04. 06, I]9 010 0315 62 2.79 2189 061 1.]9 2035
64 0.18 OA]3 061 1]0 OJ6] B316 64 273 0110 O61 1lfi sued
66 0:]] 04]] 061 LT) 0.161, 031] 6fi 2fi] 2232 051 I]] 207168 02S 0182 0So U6 SAM 031] ae 262 2353 ON 1T6 2088
__ 0 0.14 SAN 0.60 125 OJ69 Said ]025] 22]J O60 1.]5 2.105
-74 0.]2 049a ON LT4 On3 0315 ]2 252 2312 0. qi 2e20
]4 0.10 DA99 059 L]3 0.n] 03ta 74 2.47 2312 Gas O3 0.18, 2,136
Zia,
]6 am 0No 059 L]3 0.101 0318 76 2.39 2WI 059 V3 0.181 2151
]o O68 0iO3 059 V2 0,189 0318 ]B _ 2J8 23d9 059 V2 GIBS 2.165
BO 087 0500 069 VI 0.189 0318 00 231 2357 _ 059 Vt 0193 2,179
82 08S able ass 1]I _ 0.193 03b 82 2So 2385 059 1.]1 0.19J 2192
1 1 as 069- 0.514 058 VD 0.197 0317- - 86 226_ 2119 058 - 1]0_ 0201 -2205
II11 06 0.64 0514 am 1.69 0201 031] 06 222 2.619 058 169 0201 2210
08 063 0521 -050 1.69 0205 0318 as 1.19 2.435 O58 169 0305 2230
90 062 0524 059 1Go 0209 0316 ro 2,15 2A51 _ .58 168 0209 22 2
92 061 0.528 058 _ I'M 0213 0315 92 2_12 240 058 _ 16B 0213 22M
94 ON 05)1 0.5] 1.67 02t7 0314 _ 94 209 2492 0_5,]_ I67 0217 2265_
1 I 96_ 059 0511 -0.57 1.51 _ 0121 _ 0313- 96 206 - -2A9], _ 05] I67 0221 _"IS
1111 99 058 0537 0.57 16] 0225 .312 98 203 2511 0b] 167 02]5 2201
IN 057 ame 05, 168 0229 0.311 to 2SO 2526 057 165 0129 2Our
102 _ _ 056 _ 0543 057 I6fi 0233 DJII f02 1.97 2540__ 051 1so 0233 2307
Ica .56 0546 057 To 0237 0Me 104 LW 2554 057 165 _ _0237 2317
IN O55 _ D519 _057 LAS 0241 0308 IN 192 2568 057 _I AS 0241 23V
118 - _Dad _ San _ GN 1,65 DNfi _ _0307_ IN - 119 2601 = _OSB -Ib5 0245 2336_
110 0, 053 0555 Dan 164 62d9 N6 To I87 25M 056 Cu 0149 am
112 053 05H D 6 1" 9253 0305 1f2 Ib 2607 056 16d 0253 2354
1f4 _052 _ 0560 .56 1,64 0257 _ 030 114 16o2 3s20 066 1fid 026] 23a3_
Ila _ .51 0563 ON 163 0261 0J02 116 V9 2632 .55 163 0261 2311
118 O51 8568 058 _ 1.63 0265 0301 its �.11 2b5 050 __163__ 02as 23M
0. .. 056 1 ISO 0. 163
Nod FM Minor Nagger VeWme(cubic A)= 13A52 Mad.FMNalor Slarage Valeme(cable h)= 104,01S
Nod.FMNInor Stange Volume(acre&T- 03la0 Mad FMM.lm Stange Volume(ecrehl- 2381,
UDFCD DETENTION BASIN VOLUME ESTIMATING WORKBOOK Version 2 34,Released November 2013
Plen-A Murr:'on_J1>4_]EW DRAONGE,eno.Ved Seat FAA 3r2We,8,4Se Pla
i
DETENTION VOLUME BY THE MODIFIED FAA METHOD
Project:AMBER WAVES
Bain in:POND B
Inflow and Outflow Volumes vs.Rainfall Duration
a
2.5
2
•••
w
m
w
m 1.5 •
E �•
i o
0
1
0.5
0
0 20 40 80 80 100 120 140
Duration(Minutes)
I
UDPCO DETENTION BASIN VOLUME ESTIMATING WORKBOOK Verson 2 36,Released November 2013
PanOB IAAeiehan J[.Ji I1 DRAINAG .,Ikd.c(FPA WW4316.4MPM
i
STAGE-STORAGE SIZING FOR DETENTION BASINS
Project: Amber Waves
Basin ID:Pond B
s:rsyz .�Rvr
" L t r Ste Slrye2 r -.-�
Oeslgn Information In off; Check Basin Sha a
Width of Basin Bmlom,W 0 Right Triangle OR...
Length of Basin Bottom,L = itIsosceles Triangle OR...
Dam Side-slope(H:V),Za= R/ft Rectangle OR...
Circle/Ellipse OR...
Irregular (Use Ovande values In cells G32:G52)
MINOR MAJOR
Storage Requirement fmm Sheet'Modified FAA': 0.32 2.39 acre-ft.
Stage-Storage Relationship: Storage Requirement from Sheet'Hydmgraph': acre-it
Storage Requirement from Sheel'Full-Spectrum': acre-ft.
Labels Water Side Basin Basin Surface Surface Volume Surface Volume Target Volumes
for WOCV,Minor, Surface Slope Width at Length at Area at Area at Below Area at Below for WDCV,Minor,
&Major Storage Elevation (H:V) Stage Stage Stage Stage Stage Stage Stage &Major Storage
Stages ft NB ft ft ft, fe User 0a acres acre-ft Volumes
Innull fir'.11 Below El. ww.ul Igu loud loumutl Overide I.uft,,W lout ,A Igulpul (for coal Seek
4925.00 enput 0 0,000 0.000
4925.10 0.00 0.00 1440 72 0.033 0.002
4925.20 0.00 0.00 2880 288 0.056 0.007
4925.30 0.00 0.00 4,321 648 0.099 0.015
4925.40 0.00 0.00 5,761 1,152 0.132 0.026
4925.50 0.00 0.00 7201 1800 0.165 0.041
4925.60 0.00 0.00 8,641 2.592 0.198 0.060
4925.70 0.00 0.00 10,082 3,529 0.231 0.081
4925.80 0.00 0.00 11522 4609 0.265 OA06
4925.90 0.00 0.00 12.962 5,833 0.298 0.134
4926.00 0.00 0.00 14402 7201 0.331 0.165
4926.10 0.00 0.00 17,131 8,778 0.393 0.202
4926.20 0.00 0.00 19,860 10,627 0.456 0.244
4926.30 0.00 0.00 22 589 12.750 0.519 0.293
4926.40 0.00 0.00 25,318 15145 0.581 0.348
WOCV 4926.50 0.00 0.00 28047 17813 0.644 OA09
49 66.60 4926.69 0.00pa.ao 311776 20.755 0.707 0.476 0.479
4926.70 0.09 33505 23969 0.769 0.550
4926.80 0.00 36233 27455 0.832 0.630
4926.90 0.0 30,962 31,215 0.894 0.717
4927.00 0.00 41691 35248 0.957 0.809
4927.10 0.00 44709 38565 1.026 0.908
4927.20 0.00 47,726 44190 1.096 1.014
4927.30 0.00 50]44 49,113 1.165 1.127
4927.40 0.00 53,762 54,338 1.234 1.247
4927.50 0.00 5fi 779 59 865 1.303 1.374
4927.60 0.00 59.797 65 694 1.373 1.508
4927.70 0.00 0.00 62.814 1 71,825 1.442 1.649
4927.80 0.00 0.00 65 i32 1 78.257 1.511 1.797
4927.90 0.00 0.00 68,850 84,991 1.581 1.951
4928.00 0.00 0.00 71,867 92,027 1.650 2.113
4928.10 0.00 0.00 73418 99291 1,085 Z279
4928.20 0.00 0.00 74,970 106,711 1.721 2.450.
4928.30 0.00 0.00 76,521 144,285 1.757 Z624
4928AO 0.00 OAO 78072 122015 1.792 2.801
4928.50 0.00 0.00 7962 129900 1.828 2.982
100 VR 4928.60 0.00 0.00 81,175 137,940 1.864 3.167 3.295
4928.67 4928.70 0.00 0.09 82726 146135 1.899 3,355
4928.80 0.00 0.00 84277 164485 1.935 3.546
4928.90 0.00 0.0 85828 162990 1970. 3.742
4929.00 0.00 0.00 87 380 171 650 2.00B 3.941
4929.50 0.00 0.00 92 912 216 723 2.133 4.975
4930.09 0.00 0.00 98445 264562 2.260 6.0]4
4930.50 OAO 0.10 1 1 101211 314476 2.323 1 7.219
i
PgndB_UD-D.hmgon_W.34_NEW ORAINAGE.tlsm,Basin 3126/2018,4:58 PM
STAGE-STORAGE SIZING FOR DETENTION BASINS
Project
Besin ID:
STAGE-STORAGE CURVE FOR THE POND
4931.00 - - -
4930.50
4930.00
4929.50
N
N
w 4929.00
N
4928.50
4928.00
4927.50 -
4927.00
0.00 1.00 2,00 3.00 4.00 5.00 6.00 7.00 8.00
Storage (acre-feet)
PondB_UD-Detention_W.34_NEW DRAINAGE.Asm,Basin 312612818,4:58 PM
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RESTRICTOR PLATE SIZING FOR CIRCULAR VERTICAL ORIFICES
Project: Amber Waves
Basin ID: Pond B
Dio.
To
0
% oty- )
N1 Vertical N2 Vertical
S'inp the Reshiclor Plate for Circular Vertical Orifices or Pipes(input) Orifice Od6ce
Water Surface Elevation at Design Depth EIev INS= 4928.8] feet
PipeNedical Duties Entrance loved Elevation Elay.loved= 4926.00 feel
Required Peak Flow through Ounce at Design Depth 0= 2.91 ors
PipeNertical Orifice Diameter(inches) Die= 18.0 inches
Ounce Cesffichmt Ce= 0.61
Full-flow Car eciN(Calculated)
Full-nowarea Af= 1.]] sgit
Half Central Angle in Radians Theia= 3.14 red
Full-nowespacity Of- 14.8 cfs
Percent of Desgn Fl.=1 607%
Calculation of Ounce Flow Condition
Half Central Angle(0<Thata<3.1416) Theia= 102 red
Flowarea A.= 0.32 sgfl
Top width of Critics(inches) Te= 16.29 inches
Height from Invert of Orifice to Bottom of Plate(feet) Y.= 0.w feel
Elevaton of Bottom of Plate Elev Plate Bottom Edge= 4 925.36 feet
Resultant Peak Flow Through Orifice at Design Depth Do= 2.9 1 lots
Width of Equivalent Rectangular Vertical Orifice Equivalent Width= 6.91 I (feat
it
PcndB UD-Detention v2.34 NEW DRAINAGE.dsm,Reslrictor Plate 3/28/201 a,4:04 PM
i
RESTRICTOR PLATE SIZING FOR CIRCULAR VERTICAL ORIFICES
Project: Amber Waves
Basin ID: Pond B
Din.
0
x 0 0
0 0 0
Yn
NI Vertleal 02VOrified
put) Orifice ical
Sizing the Reslrictor Plate for Circular Vertical Orifices or Pipes(ince
Water Surface Elevation at Design Depth Ease WB= 42MU leaf
PlpeAnertical Onfice Entrance lnved Elevation E,ev.Invert= 49"00 feel
Required Peak Flow through Orfce at Design Depth Q= 2.91 crs
PipeNedinal Onfiee Diame far(inches) Dia= i8.0 inches
Office Ccefiidenl Ca= 0.61
Full-Bow Capacity(Calculated)
Full-Oowarea Af= 1.77 sq8
Half Central Mite in Fact... Thela= 3.14 red
Fall-flowcapaciy Qf= 14.8 cfs
Percent of Design Flow= 507%
Calculation of Office Flow Condition
Half Central Angle(0<Theta<3.1416) Thele= tA2 rod
Flowarea Ao= 0.32 sq8
Top width of CO.(.mass) T. 18.29 Inches
Height Gem loved of Ofce to Bottom of Plate(f ct) Ye= 0.35 feet
Elevation of Bottom of Plate Else Plate Bottom Edge= 4,925.35 feel
Resultant Peak Flaw Through Office at Desgn Depth Qu= 2.9 on,
Width of Equivalent Rectangular Vertical Office Equivalent Width= 0.91 /eat
i
PondB LID-Detention v2.34 NEW DRAINAGExIsm,Restriclor Plate 32812018,4:06 PM
STAGE-DISCHARGE SIZING OF THE WEIRS AND ORIFICES(INLET CONTROL)
Project: Amber Waves
Basin to:Pond B
eaV Snrdrrei l5wdudr r nrz
a..........r rs..p.ms<i ar_an-4
Current Routing Order is#3
peslan Inrn,matian enpyl: #1 Hanz #2 Hertz #1 VeM1 #2 Vert.
GrcWrOpening: Cizmelerinbwhes Dia.= I aches,
OR
Reclanguar O,nr,g: Width in Feet W-1 300 1 0,91 1a.
Lenph(Haght for Venkaft L.rH=l 3.00 1 0.35 1 ft,
Percentage of Open Area After Trash Rack Reduction %o,pen-I 50 1 100 %
cot"Coeffnienl C.- 061 1 1 0.61
Weir Coaffcienl C== 2,U
Critics E kuoafion(BoOom for Vedx,aft Eo=j 492660 1 492500 f-
9aleulation of Cnlleelinn Cxnnelty.
Net Opening Area(after Trash Rack Reductnn) A.= 450 0,32 sq.8
OPTIONAL:User-Ovende Net Opening Area q,= sq.It
Perimeter as Web Length L.- 900 ft
OPTIONAL:Uaer-Ovedde Whir LerlgOl L.=mft
Top Elsr ikhn of Vertical Orifice Opening,Tap= 4925.35 ft
Chose,Elevation of Vertical Ofifne Opening,Can= 492518 ft
Routing 3: Single Stage-Water flows through WQCV plate and#1 horizontal opening into#1 vertical opening. This flow will be applied to
culvert sheet(#2 vertical&horizontal openings is not used).
Horizontal Odfices Vertical Orifices
La6ds Wale, WOCV 41 Hans. #1 Hor¢. #2 Fare #2 Horz. #1 Vent 42 Vert, Total TargalVd z
for WOCV,Minor. Surface Ptnemiser Web OrRCe Weir OMae Colecggn Collection Collection for WOOV.Mint,
4 Mapf storage Elevation Flow Fbw Fbw Flow Flow Capacity Capacity Capacity 4Masorslvage
W.S.6lawgere ft cfs cis she cfs cfs cfe cfs cfs Va .
in ul Orkedl $0.02
d fie I o .0 1 11 ou t 1 (output) Inn rcr oat zeexl
4925.00 O.N ON 0.N men 0.N 0.00 O0a
4925.100.00 em ON 0.0 0.10 0.00 0.00
4925.20OZO ON ON 6.00 028 0.00 0.00
4925.300.00 O00 0.N ON 0.52 coo 0.00
4925.40Oct0.00 000 040 ON 0.74 0.00 0.01
4925.500.N ON 0.00 ON M 0.N 0.02
4925.60 0.00 O.co 0.N 0.00 1.02 0. 0.03
4925.700.00 000 0.00 moo 1A4 6.00 0.04
4926.80 0.00 0N 0.00 000 1.24 0.00 0.05
4925.90 000 0N 0.00 OZO 1.33 0.00 0.06
4926.00 0.a0 0.00 ON 0.00 tat 0.00 0.01
4926.10 . 0.0 ON 0.00 0.00 1.51 0.00 0.09
4926.20 0.11 o.N 0.00 ON POO 1.59 0.00 0.11
4926.30 0.12 0.N 0.00 ON 0.N 1.66 0.00 0.12
4926.40 0.13 0.N 0.00 ON 0:N 1.73 0.00 0.13
4926.50 0.14 0.N 0.00 0.00 0.00 1.80 0.00 0.14
4926.60 OA4 O.m 0.00 000 0.00 1.87 0. 0 0.14
4926.70 0.15 0.81 6,97 0.00 ON 1.93 0.N 0.96
4926.80 0.16 IN 9.85 0.00 MOO 2.00 O.N ZOO
4926.90 0.17 4.20 12.07 0.00 BOO 2.06 0.00 2.06
4927.00 OAT 6,17 13.93 000 0.00 2.12 ON 2.12
4927.10 0.18 9.04 1558 ON 0.00 2.17 MOO 2.17
4927.20 0.19 11,88 ITT 0.00 000 2.23 0.0 2.23
4927.30 0.19 1497 1843 OMO 0.00 2.28 MOO 2.28
4927.40 0.20 18.29 19.70 ON 000 ZU 0.00 2.34
4927.50 &20 21.82 2000 ON 0.N 239 0.00 239
4927.60 0.21 25.56 2203 ON o.N 2.44 MOO 244
4927.70 0.21 29.0 23,10 ON ON 2.49 0.00 2A9
4927.80 0.22 33.60 24A3 ON 0.N 254 0.00 2.54
4927.90 0.23 3789 25.12 0.00 0.00 2.59 000 2.59
4928.00 0.23 4234 26.06 ON ON 2.63 0.N 2.63
4928.10 o24 46,98 26.98 000 0.N 2.68 ON 2.69
4928.20 0.24 5173 2T86 0.00 000 272 ON 2.72
4928.30 024 56.65 28.72 000 0.00 2.77 0.29 2.77
49MAO 025 61.73 29.55 ON 0.00 Z81 0.00 2.81
4928-50 0.25 66.94 30.36 ON 000 2.86 0.00 Z86
100YR4928.67 4928.60 0.26 72.29 31,15 0.N 0100 2.90 OZO 2.90 2.91
4928.70 0.26 71]8 3192 ON ON 294 0.00 2.9/
4928.80 0.27 83.41 32.67 ON 0.N 2.98 MOO 2.98
4929.90 0.27 89.16 3341 000 O.N 3.02 0.00 3.02
4929.00 028 95.03 34.13 ON ON 3.06 0.00 IN
4929.50 0.30 12823 37.51 0.00 0.00 3.26 0.00 0.26
4930.90 031 160.24 4062 ON 0.00 3.4d %0 3M
MOM 0.33 INO6 4350 ON 0.00 3.61 000 3.81
Panda UD-Detention V2.34 NEW DRAINAGE.Idsm,Outlet 713112018,11:41 AM
STAGE-DISCHARGE SIZING OF THE WEIRS AND ORIFICES(INLET CONTROL)
Pmjecl: Amber Waves
Basin 10:Pond B
STAGE-DISCHARGE CURVE FOR THE OUTLET STRUCTURE
4931 -- - —
4930.5
4930
N
N
, 1 4929.5
O7
07
w
N
Of
r
W 4929
4928.5
4928
4927.5
4927
0 0.5 1 1.5 2 2.5. 3 3.5 4
Discharge (cfs)
Panda UD-Dalenlion W.34 NEW DRAINAGE.tlsm,OuIIeI 7/3112018.11:41 AM
Sharlene Shadowen
From: mailer@digitaldataservices.com
Sent: Tuesday, July 31, 2018 12:21 PM
To: Sharlene Shadowen
Subject: Stormwater Detention and Infiltration Facility- Pond A- Industrial Business Park
Thank you for submitting to the Colorado Stormwater Detention and Infiltration database. Your facility has been
recorded and the local jurisdiction has been notified.
Facility ID: SWDF-201 8073 1 1 12046
Name: Pond A- Industrial Business Park
Division: South Platte
Jurisdiction: LarimerCo
Design Storm: 100-Year
Water Surface Acres: 1.86
Edit Key: 9238607eI849cfd6c7e886d4130fd33a
If you wish to edit the facility in the future, you will need the Edit Key listed above. If you lose the key, you will not
be able to edit the facility information in the future.
J
t
E:= Stormwater Detention and Infiltration Design Data Sheet
Stormwater Facility Name: POND A-INDUSTRIAL BUSINESS PARK INTERNATIONAL PUD,LOTS 5-9 AND ENVELOPES B,CAN D O
Facility Location&Jurisdiction: INTERNATIONAL BLVD&MEXICO WAY,LARIMER COUNTY
User Input:Watershed Characteristics User Defined User Defined User Defined User Defined
Watershed Slope= 0.010 ft/ft Stage[it] Area(ft-21 Stage Ift] Discharge Ids)
Watershed Length= 300 it 0.00 26,074 0.00 0.00
Watershed Area= 11.38 acres 0.50 39,612 0.50 0.01
Watershed Imperviousness= 60.2% percent 1.00 46,352 1.00 0.05
Percentage Hydrologic Soil Group A= 0.0% percent 1.50 54,327 1.50 1.85
Percentage Hydrologic Soil Group B= 100.0% percent 2.00 62,301 2.00 2.18
Percentage Hydrologic Soil Groups C/D= 0.0% percent 2.10 64,127 2.10 1 2.24
Location for 1-hr Rainfall Depths(use dropdown):
Userinput W
WQCV Treatment Method= Wended Detention
After completing and printing this worksheet to a pdf,go to:
httos,//manerture dieitaldataservices.com/evh/?viewer=cswdif
create a new stormwater facility,and
attach the pdf of this worksheet to that record.
Routed H drogra h Results
Design Storm Return Period= WQCV 2 Year S Year 10 Year 50 Year 100 Year
One-Hour Rainfall Depth= 0.53 0.82 1.14 1.40 2.17 2.86 in
Calculated Runoff Volume= 0.225 0.421 0.625 0.857 1.593 2.236 acre-ft
OPTIONAL Override Runoff Volume= acre-ft
Inflow Hydrograph Volume= 0.224 0.421 0.624 0.856 1.593 2.236 acre-ft
Time to Drain 97%of Inflow Volume= >62 >62 >62 >62 >62 >62 hours
Time to Drain 99%of Inflow Volume= >62 >62 >62 >62 >62 >62 hours
Maximum Ponding Depth- 0.32 0.55 0.76 0.98 1.53 1.98 it
Maximum Panded Area= 0.80 0.92 0.99 1.06 1.26 1.42 acres
Maximum Volume Stored- 0.224 0.419 0.621 0.851 1.490 2.093 acre-ft
SDI_Design_Data_v1.08_Pond A.xlsm,Design Data 7/31/2018,11:37 AM
Stormwater Detention and Infiltration Design Data Sheet
�100YR IN
80
100YR OUT
—50YR IN
70 SOYR OUT
60 —IOYR IN _
--- 10YR OUT
SO —5YR IN
••• SVR OUT —
E
340 2YR IN
a
- 2YR OUT
30 —WQCV IN -- — — --
•••••WQCVOUT
20
10 _
0.1 TIMB[hr] 30
2.5
—100YR
—50YR
2 — —
—10YR
—5YR
x
x1.5 - —2YR
1, c
0z —WQCV
0
Q
0.5 __-
0 -
0.1 - 1 10 100
DRAIN TIME{hr]
SDI_Design_Data_v1.08_Pond A.xism,Design Data 7/31/2018,11:37 AM
STAGE-DISCHARGE SIZING OF THE OUTLET CULVERT(INLET vs.OUTLET CONTROL WITH TAILWATER EFFECTS(
Props: Amber Waves
Bolo In:Poor]8
e Of
Status:start Contains Errors.see C E ad EnwLsl Rartie
x �
Deslan Information tlnDUllo
fieJar Culvert:Barrel Disputer F lalaas o= le
fwWar Cl orl:I"Ed3e Type lelWee Iran 0l u61) I l5nagen,EN Mr,Hear-1n
OR,
Boa CJ.erl:Barre,HVe(Bee)n Feel HeyM lliee)= X.
Box Cuhert:Bane,mlu(SPan)Is Fast 1Y•iIF 6 an= II.
Box CukeR lrbtEdja TypelWose lrom g4Mnn K1) aeE ex/�15d fWcf e4'n aatl
NarMr of Korean Is, 1
IrlelE taan at "lmen la I93500 4ale,
Cutlet EIevu0onat CWert lme. Oe-,= d920.2s X.ow,
GAMLeyuii Feel L-
M alirds RoyM1nss Is0.0130
BeM Loss Gelfekrd K 0:00
Ent Loss Coofr sont
Design Information Icalculateltl:
E lens CeN K..
Fokas Loss Coefficient K=
maA CsuftarkNs K.
e;ake Intel Cae[an
c[enlden e,=
kf[Lrarn Ere,CwSM1bn fwunckat NEr,
Calculations of Culvert Ca act out ut:
Water6url3m TalNnler CUNert CovertfiO.DZ
s Controllers Inlet
Elevation Sea.. Inlet-Control DudeLCanlad Cowers Ecun.u.
From Sneer Elevallen Flosrate FlOvmteel Normal. Used
-.-r- X are are, ' If.
X.linked :in uln 4naan gut ul Out atst toaster) OIrt
e925.00
e925.10
e925.20
e925A0
e925A0
4925.0 4925M
a925]° I 1 0."
e925.80 0.05
4925.90 D.06
t926.00 0.02
4926.10 0.09
t926R0 sit
4926.2° 0.12
4926A0 0.1J
8926.50 O.tI
4926.60 0.1e
e926.20 0.96
e92680 2.00
M6.90 2-06
e922.00 1 2.13
4922.10 2f2
e922.20 2.23
4922.30 L28
e9n.40 13[
192180 139
4927.60 2.44
4922.70 2A9
e927.50 2.58
e922.90 2.69
4928.00 2 w
0928.10 2.69
[92830 2.72
e92830 2A
e928A0 2.81
4938.50 2.66
e92880 2.90
492830 2.98
4929.90 2.99
4928.90 3.02
4929.00 3.06
e921.50 3,26
e930.00 3.44
193080 3.61
PadB M-Dater[ear JLB[_N NY 0WAGENun,CiAert Y2&201l%a:08 Pk1
i
STAGE-DISCHARGE SIONG OF THE OUTLET CULVERT(INLET vs.OUTLET CONTROL WITH TAILWATER EFFECTS)
Prgecc Amber Waves
Baal.IM PoetlO
STAGE-DISCHARGE CURVE FOR THE FINAL OUTLET PIPE CULVERT
4931.00 -
4930.50
4930.00
4929.50
I �
N 4929.00
W
G
m
m 4928.50
4928.00
4927.50
4927.00
0.00 10.00 20.00 30.00 40.00 50,00
Discharge (cfs)
PggB IA-patMIm JGN tEIV OMItKGEtlsm Glrol y2G�1119,J'.OB PM
STAGE-DISCHARGE SIZING OF THE SPILLWAY
Project: Amber Waves
Basin ID: Pond B
Design Information finpull:
Bottom Length of Weir L=M309
feet
Angle of Side Slope Weir Angle= degrees
Elev.for Weir Crest EL.Crest= feet
Cost.for Rectangular Weir C„.=
Coef.for Trapezoidal Weir Ct=
Calculation of Spillway Capacity!output):
Water Rect. Triangle Total Total
Surface Weir Weir Spillway Pond
Elevation Flowmte Flowrate Release Release
8. cis cis cis cis
(linked) (output) (output) (output) (output)
4925.00 0.00 0.00 0.00 0.00
4925.10 0.00 0.00 0.00 0.00
4925.20 0.00 0.00 0.00 0.00
4925.30 0.00 0.00 0.00 0.00
4925.40 0.00 0.00 0.00 1 0.00
4925.50 1 0.00 0.00 0.00 0.00
4925.60 0.00 0.00 0.00 0.00
4925.70 0.00 0.00 0.00 0.00
4925.80 0.00 0.00 0.00 0.00
4925.90 0.00 0.00 0.00 0.00
4926.00 0.00 0.00 0.00 0.00
4926.10 0.00 0.00 0.00 0.00
4926.20 0.00 0.00 0.00 0.00
4926.30 0.00 0.00 0.00 0.00
4926.40 0.00 0.00 0.00 0.00
4926.50 0.00 0.00 0.00 0.00
4926.60 0.00 0.00 0.00 0.00
4926.70 0.00 0.00 0.00 0.00
4926.80 0.00 0.00 0.00 0.00
4926.90 0.00 0.00 0.00 0.00
4927.00 0.00 0.00 0.00 0.00
4927.10 0.00 0.00 0.00 0.00
4927.20 0.00 0.00 0.00 0.00
4927.30 0.00 1 0.00 0.00 1 0.00
4927.40 0.00 0.00 0.00 0.00
4927.50 0.00 0.00 0.00 0.00
4927.60 0.00 0.00 0.00 0.00
4927.70 0.00 0.00 0.00 0.00
4927.80 0.00 0.00 0.00 0.00
4927.90 0.00 0.00 0.00 0.00
4928.00 0.00 0.00 0.00 0.00
4928.10 0.00 0.00 0.00 0.00
4928.20 0.00 0.00 0.00 0.00
4928.30 0.00 0.00 0.00 1 0.00
4928.40 0.00 0.00 0.00 0.00
4928.50 0.00 0.00 0.00 0.00
4928.60 0.00 0.00 0.00 0.00
4928.70 0.00 0.00 0.00 0.00
4928.80 0.00 0.00 0.00 0.00
4928.90 0.00 0.00 0.00 0.00
4929.00 0.00 0.00 0.00 0.00
4929.50 0.00 0.00 0.00 0.00
4930.00 0.00 0.00 0.00 0.00
4930.50 1 74.29 1 2.16 1 76.47 1 76.47 -
PondB_UD-Detention_v2.34_NEW DRAINAGEAsm,Spillway 3/26/2018,5:00 PM
i
STAGE-DISCHARGE SIZING OF THE SPILLWAY
Project: Amber Waves
Basin ID: Pond B
STAGE-STORAGE-DISCHARGE CURVES FOR THE POND
Storage(Acre-Feet)
0 1 2 3 4 5 6 7 8
4931
4930-5
4930
00
0 4929.5
!
m
m 4929
N
4928.5
4928
4927.5
4927
0 10 20 30 40 50 60 70 80 90
- Pond Discharge(cfs) —
PondB_UD-Detention_v2.34_NEW DRAINAGE.Asm,Spillway 3126/2018,5:00 PM
I
Sharlene Shadowen
From: mailer@digitaldataservices.com
Sent: Tuesday,July 31,2018 12:23 PM
To: Sharlene Shadowen
Subject: Stormwater Detention and Infiltration Facility- Pond B - Industrial Business Park
Thank you for submitting to the Colorado Stormwater Detention and Infiltration database. Your facility has been
recorded and the local jurisdiction has been notified.
Facility ID: SWDF-201 8073 1 1 1 2234
Name: Pond B - Industrial Business Park
Division: South Platte
Jurisdiction: LarimerCo
Design Storm: Water Quality
Water Surface Acres: 1.86
Edit Key: 4ab02CO23653269ecce7def5e3a40a01
If you wish to edit the facility in the future, you will need the Edit Key listed above. If you lose the key, you will not
be able to edit the facility information in the future.
i
Stormwater Detention and Infiltration Design Data Sheet
Stormwater facility Name: POND B-INDUSTRIAL BUSINESS PARK INTERNATIONAL PUD,LOTS 5.9 AND ENVELOPES B,CAN D D
Facility Location&Jurisdiction: INTERNATIONAL BLVD&MEXICO WAY,LARIMER COUNTY
User Input:Watershed Characteristics User Defined User Defined User Defined User Defined
Watershed Slope= 0.009 Wit Stage[it] Area IfM2] Stage[ft] Discharge(cfs)
Watershed Length= 1300 it 0.00 0 0.00 0.00
Watershed Area= 14.57 acres 1.00 14,402 1.00 0.07
Watershed Imperviousness= 72.0% percent 2.00 41,691 2.00 2.12
Percentage Hydrologic Soil Group A= 0.0% percent 3.00 71,867 3.00 2.63
Percentage Hydrologic Soil Group e= 60.0% percent 3.60 81,175 3.60 2.90
Percentage Hydrologic Soil Groups C/D= 40.0% percent
Location for 1-hr Rainfall Depths(use dropdown):
Userinput
WOCV Treatment Method= Extended Detention V
After completing and printing this worksheet to a pdf,go to:
https,//manerture.dieitaidatasemices.com/gvh/7viewer=cswdif
create a new stormwater facility,and
attach the pdf of this worksheet to that record.
Routed H drogra h Results
Design Storm Return Period= WOCV 2 Year 5 Year 10 Year 50 Year 100 Year
One-Hour Rainfall Depth= 0.53 0.82 1A4 1.40 2.17 2.86 in
Calculated Runoff Volume= 0.345 0.669 0.996 1.302 2.262 3.117 acre-ft
OPTIONAL Override Runoff Volume= acre-R
Inflow Hydrograph Volume= 0.344 0.668 0.995 1.302 2.262 3.116 acre-ft
Time to Drain 97%of Inflow Volume= 50.4 47.5 44.9 42.9 38.6 35.9 hours
Time to Drain 99%of Inflow Volume= 56.4 55.9 55.2 54.6 54.1 54.1 hours
Maximum Ponding Depth= 1.28 1.66 1.96 2.20 2.85 3.32 ft
Maximum Ponded Area= 0.50 0.74 0.93 1.10 1.54 1.36 acres
Maximum Volume Stored= 0.281 0.516 0.764 1.015 1.866 2.651 acre-fit
SDI_Design_Data_v1.08_Pond B.xlsm,Design Data 7/31/2018,12:12 PM
Stormwater Detention and Infiltration Design Data Sheet
45 —100YR IN
SOOYR OUT
40 50YR IN —
50YR OUT
35 �10YR IN
-- 10YR OUT
30 I
—5YR IN
25 ""• 5YR OUT - - --
3 —2YR IN - -
0
u 20 __-. 2YR OU
15 T —
WQCV IN
•••••WQCV OUT � --- - —
0 _.. _ .
0.1 TIME[hr] 30
3.5
_100YR
3 —50YR -
—IOYR
2.5
—SYR
x —2YR
W 2
z -
Z WQCV
s
z
g 1.5 - - _- - - - --
0.5 --
0
0.1 1 —— to 100
DRAIN TIME[hr]
'SDI_Design_Data_v1.08_Pond S.xlsm,Design Data 7/31/2018,12:12 PM
APPENDIX D
DRAINAGE PLAN
LEGEND
DP DESIGN POINT
D1
FLOW DIRECTION UNITED CIVIL
X BASIN DESIGNATION Design Group
XX.X X.XX 2-YR RUNOFF COEFF. CIVIL ENGINEERING&CONSULTING
X.XX 100-YR RUNOFF COEFF. 19 OLD TOWN SQUARE#238
FORT COLLINS,CO 80524
BASIN AREA(ACRE) (970)530-4044
www.unitedcivil.com
BASIN BOUNDARY
00) y
N 7
O E
L -O
co
f0 N
C
� m a)
G
\ \ 0w
O O m
C L C
_ - U (0
0 30' 60' 120' z r
o amo
J / — SCALE: 1"=60' r aca
I � % vv � � _�v v ma)
_� \ a a
I — � En En 2
(1)
\ ZURICH DRIVE ' " \ J \ \ \ J — \\\\\ NOl nvo
\ 0
k 49 �9 g933, 9�A EXISTING SCHOOL04
o
\ I I I I 9R\ I \ �• i -4937_ _ \� 1 \ \ \\ �� � 1 \\\\ 00
\cl I
ll I \ \\
/ ` / \• \/ \ \\\ LLI cn
f ,4935
UR��
�
\
IIII \
— — J
11/ - - 15.29 0.75
I I I Illlll _ _ _—\1\1\1\ll�ll I\ \ 0.94 // I 1 1 \ \ \\ \ � x \ I I I
I 1 \ � I � � � � L.I.J
IIIIIIIIjIIII — Illlllllllllll \\ \\ /; I I\\ _� r , CD
�IIIIIIIII�II jlljllljllll II \� \1 I 'IIII \\ <<` —JII `\ / \ \ l r Illlll
Q IIIIIIIIII I`- -4947
IIIIIIIIIII
o
\ IIII l�_4944= 111 IIIII / I I I \ 1 I• I \ \ \ I Illlll
LU II I I I I— -4943 — =Ijl Illlll / 1 I I 1 1\ \ \ ( 9 l I l I w
1 (I\\l\� —4941 =JIIII Ill /_/ \ \ I I I 1 \ l \ \ \ ° IIIII 0 Q
—4940— / \ \ \ \ I ` l \ \ IIII W U
IIII - - 4939- - -_//Ill \/ I II ` — °
II
=4938= /> \ 1 III II t /\_ — ICJ r � a
V Z
-I. J5s I s34\ N I I \ 1 Q
935�
III%G4940-/� \\\ I \ \ \ co
>j'
�✓ I I I � \ ---ill\\��,��;=���iJiJ - � � � � _
W
— —
1 1 ,4933' I � —\ \ I I \ \ \ w Q
`� \\
o I I � �- ) \` / \ �' III I II \ — � � _I � \ _
Q \ 1 I . I I I 9 I POND B SUMMARY I \ -
_ _ _ I I \
W \ \ ��\493349324931- - - - - - - - - - - - - - - -- l ` - - - - - -- - - - - - - - - - - - - - - R9� \ EXISTING POND B
WQCV = 0.25 AC-FT I \ \ \ \ O
I (/ \ \R I V100 = 3.3 AC-FT (WQCV+ 100-YR) / \ \ w
� \ I I POND B 0 R9� �� VMAx -4.7 AC-FT \ \\ \ �
o J / 1 I III �\\ ` \ \ �' Q100 = 2.91 CFS ` \ \ \
I/ I I I I I / \ \ I W
Q
\�/ IIII , REQUIRED POND B a
- - - - - - \ - - - WQCV = 0.48 AC-FT
Q IIII _ �g29 �;:'\ / V100 = 3.9 AC-FT (WQCV + 100-YR) \ \
z r / / / I I I QlOo = 2.91 CFS
I I \
Z cn ? \\\ DP
_ _ _w = � B __EXISTING OUTLET STRUCTURE_
Al
LLI
00
cli
tF
& — - — \
CL 0
0
w — — \
a � ` ♦` ST1 \ \ SHEET NUMBER
X INTERNATIONAL BLVD 4— 4 \
Li) J 0-
w W C6.00
\ \
P � � 1 OF 1 SHEETS
Q
z >_
44\,
v
o o � SCALE
o IL VERTICAL: 1"=N/A
N Z
Z =)
Z v HORIZONTAL: 1"=60'
di
a a JOB NUMBER
0 o a
U24018