HomeMy WebLinkAboutTIMBERLINE INTERNATIONAL - PDP200014 - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTPrepared for:
Owner/Developer
Mr. Devin Ferrey
FR Holdings, Ltd.
125 S. Howes Street, 2nd Floor
Fort Collins, Colorado 80521
Prepared by:
11582 Colony Row
Broomfield, CO 80021
Phone: (720)259-0965, Fax: (720)259-1519
Project Number: 1805.00-TIM
Drainage Design Considerations
for the
Timberline - International
Preliminary Development Plan (PDP)
Fort Collins, Colorado
August 14, 2020
August 14, 2020
Mr. Matt Simpson
Stormwater Engineering
City of Fort Collins
700 Wood Street
Fort Collins, Colorado 80522
Subject: Drainage Design Considerations for the
Timberline-International Preliminary Development Plan (PDP)
Fort Collins, Colorado
Dear Mr. Simpson:
Wohnrade Civil Engineers, Inc. (WCE) is pleased to submit this final hydrologic and
hydraulic report for the subject project for your review. This report complies with
technical criteria set forth in the City of Fort Collins, Stormwater Criteria Manual, and Mile
High Flood District criteria.
We acknowledge that the City of Fort Collins’s review of this study is only for general
conformance with submittal requirements, current design criteria, and standard
engineering principles and practices.
If you should have any questions or comments as you review this report, please feel free to
contact me at your convenience.
Sincerely,
WOHNRADE CIVIL ENGINEERS, INC.
Mary B. Wohnrade, P.E. - Principal
Professional Engineer - (CO)
Drainage Design Considerations for
Timberline-International PDP
Table of Contents
1. INTRODUCTION ............................................................................................................................. 1
1.1 Objective .......................................................................................................................................... 1
1.2 Project History and Previous Studies ............................................................................................... 1
1.3 Mapping and Surveying ................................................................................................................... 1
2. SITE LOCATION AND DESCRIPTION ....................................................................................... 1
2.1 Site Location ..................................................................................................................................... 1
2.1 Site Description ................................................................................................................................ 2
3. PRE-PROJECT CONDITIONS ....................................................................................................... 2
3.1 Pre-Project Drainage Basins ............................................................................................................. 2
3.2 Pre-Project Drainage Patterns ......................................................................................................... 2
4. POST-PROJECT CONDITIONS .................................................................................................... 3
4.1 Proposed Project Description .......................................................................................................... 3
4.2 Post-Project Drainage Basins ........................................................................................................... 4
4.3 Post-Project Drainage Patterns ........................................................................................................ 4
4.4 Proposed Detention/Water Quality Pond ....................................................................................... 4
5. DESIGN CRITERIA ......................................................................................................................... 6
5.1 Design References ............................................................................................................................ 6
5.2 Hydrologic Criteria ........................................................................................................................... 6
6. EROSION CONTROL ...................................................................................................................... 7
6.1 Low Impact Design (LID) .................................................................................................................. 7
6.2 Erosion Control Plan ........................................................................................................................ 8
6.3 Site Stabilization ............................................................................................................................... 8
7. CONCLUSIONS ................................................................................................................................ 8
7.1 Compliance with Standards ............................................................................................................. 8
7.2 Variances .......................................................................................................................................... 8
8. REFERENCES ................................................................................................................................... 8
Drainage Design Considerations for
Timberline-International PDP
TABLE OF CONTENTS, cont.
Vicinity Map
APPENDICES
Appendix A: Post-Project Condition Hydrology
Appendix B: Detention/Water Quality Pond Design
Appendix C: LID Design
Appendix D: Future Off-site Storm Sewer Preliminary Design
DRAWINGS
Sheet 1 of 1 Post-Project Drainage Plan
Drainage Design Considerations for
Timberline-International PDP
Fort Collins, Colorado
August 14, 2020
1. INTRODUCTION
1.1 Objective
This study documents the results of a
comprehensive hydrologic and hydraulic
analysis for the proposed
Timberline-International PDP project located in
Fort Collins, Colorado.
The project includes new 2,500 sf and 624 sf
commercial buildings, new water and sewer
services lines, site improvements, and an onsite
stormwater detention/water quality pond
(Photo 1).
1.2 Project History and Previous Studies
There are no known hydrologic or hydraulic studies for the Timberline-International
property.
1.3 Mapping and Surveying
Intermill Land Surveying, of Loveland, Colorado, provided field survey information and
topographic mapping of the project site, with a contour interval of 1-foot. The survey
was performed in June 2018, and was referenced to NGS Monuments F136 and C402 on
the NAVD88 datum, and the NAD 83, Colorado State Plane (UTM Zone 13) North Zone
survey coordinate system.
2. SITE LOCATION AND DESCRIPTION
2.1 Site Location
The project is located in the Southwest ¼ of Section 8, Township 7 North, and Range 68
West of the 6th Principal Meridian, City of Fort Collins, Larimer County, Colorado.
The site is bounded by N. Timberline Road on the east, International Boulevard on the
south, Lake Canal on the west, and an existing commercial property on the north.
The project is located outside of any FEMA regulated floodplain, as per the FEMA Flood
Photo 1 – Project Site Looking North
Timberline-International PDP
August 14, 2020
Page 2
Insurance Rate Map (FIRM), Community-Panel Number 08069C-0984H, effective on
May 2, 2012 (see Firmette).
The property is also located adjacent to the Lake Canal, which is not a City of Fort
Collins designated floodplain, as per the online mapping application FCMaps.
2.1 Site Description
The project site is roughly 1.39 acres in size, and is located in a commercial area within
Larimer County, Colorado. The property is currently being annexed into the City of
Fort Collins, Colorado.
The site is currently undeveloped and contains an existing ditch access road, a fill pile,
and some existing utilities.
The site is located in the Dry Creek Drainage Basin, as defined by the City of Fort Collins
Master Drainage Plan. A future off-site storm sewer will be located parallel to the east
property line, which begins at East Ridge Second Filing, and ends at the Dry Creek
channel.
No offsite stormwater runoff enters the site from the adjacent property located to the
north. Stormwater runoff from South Timberline Road enters the property along the
east property line.
A geotechnical subsurface exploration report was prepared by CTL Thompson, and is
dated October 1, 2018 (Reference 4). The subsurface materials encountered consist of
2 to 3 feet of sand and clay over sand and gravel. Groundwater was encountered in
three borings at the time of drilling at a depth of roughly 13-feet, and was measured
three days later at depths ranging from 11.5-feet to 12 feet. Bedrock was not
encountered in any of the four borings within the property. The sand and gravel layer
will facilitate a Partial Infiltration Section as it relates to bioretention.
The USGS Web Soil Survey was also used to identify the hydrologic soils group within
the project limits. The site consists entirely of Group B type soils, which exhibits a
moderate infiltration rate.
3. PRE-PROJECT CONDITIONS
3.1 Pre-Project Drainage Basins
The existing project site includes a single onsite drainage basin that includes the entire
property for a total area of 1.39 acres. There is also a single off-site basin of 0.46
acres, which includes the west half of North Timberline Road.
3.2 Pre-Project Drainage Patterns
Stormwater runoff from the entire property drains overland, across gravel and
Timberline-International PDP
August 14, 2020
Page 3
vegetated surfaces to Lake Canal, which bounds the property on the west and south.
Runoff calculations for the pre-project condition have not been performed, since the
maximum allowable developed release rate is a fixed 0.20 cfs/acre, and is independent
of the historic discharges.
4. POST-PROJECT CONDITIONS
4.1 Proposed Project Description
The proposed project includes new 2,500 and 624 sf buildings, new asphalt parking and
drives, new underground utilities, and a new onsite stormwater detention/water
quality facility.
The widening of N. Timberline Road to the west has also been accounted for in this
drainage analysis. The widening will include a right turn lane for southbound traffic
onto International Boulevard. The street widening has been designed, and will be
constructed as part of this development proposal. Stormwater runoff from the west
half of Timberline Road will be conveyed along the west flowline of Timberline flowing
north to south, and then continue west along the north flowline of International
Boulevard. There are no proposed storm inlets in the adjacent streets as part of this
future improvement.
The preliminary design of a 30-inch diameter off-site storm sewer has also been
included as part of this development proposal (See Appendix D). The off-site sewer
would be located in the center of the existing right-turn lane in N. Timberline Road. A
390-foot long section of this sewer would be constructed as part of this development.
Developed stormwater runoff will be discharged to Lake Canal at a rate not to exceed
0.20 cfs/acre. An agreement has been reached with Lake Canal Company, which
allows for this release. Final engineering plans and the drainage report have been
submitted to Lake Canal Company for review and comment. Written approval has
been received by Lake Canal Company.
Standard water quality treatment and Low Impact Development (LID) has also been
incorporated into the stormwater design for this project, as per City of Fort Collins
criteria.
The proposed road improvements to N. Timberline Road and International Boulevard
will necessitate the extension of the existing 6’H x 14’W RCB culvert in Lake Canal.
The existing box culvert will be extended 20-feet to the northwest, and will require a
new concrete headwall, wingwalls, and guardrail. Structural plans for the proposed
extension have been prepared by Weeks & Associates of Fort Collins, Colorado, and will
be submitted to Lake Canal Company for review and approval.
Timberline-International PDP
August 14, 2020
Page 4
4.2 Post-Project Drainage Basins
The proposed project site has been divided into 4 post-project drainage basins for a
total drainage area of 1.28 acres. Offsite Basin O1 (0.46 acres) extends from the
existing centerline in N. Timberline Road, to the proposed back of walk on the west side
of Timberline, and includes the ultimate widening of Timberline.
Post-project drainage basins and patterns will generally mimic pre-project conditions,
with Basins 1, 1A, and 2 draining in the direction of Lake Canal to a single
detention/water quality facility. The detention/water quality facility will release
developed runoff to Lake Canal at a rate not to exceed 0.20 cfs/acre, as per the Dry
Creek Basin Master Drainage Plan.
4.3 Post-Project Drainage Patterns
Basin 1 (0.29 ac) drains overland across vegetated areas, at slopes ranging from 2.0% to
25%, to the new detention/water quality facility. The drainage pattern within this
basin will generally mimic pre-project drainage patterns. The 10 and 100-year peak
discharges are estimated to be 0.4 cfs and 1.6 cfs respectively.
Basin 1A (0.23 ac) drains overland across vegetated areas, and in vertical curb and
gutter, at slopes ranging from 0.75% to 2.0%, to a 3’W curb opening located in the
southeast corner of the proposed parking lot (Design Point 1A). The drainage pattern
within this basin will generally mimic pre-project drainage patterns. The 10 and
100-year peak discharges are estimated to be 1.1 cfs and 2.0 cfs respectively.
Basin 2 (0.47 ac) drains overland across vegetated areas, at slopes ranging from 1.67%
to 4.42%, to the new detention/water quality facility. The drainage pattern within this
basin mimics pre-project drainage patterns. The 10 and 100-year peak discharges are
estimated to be 1.1 cfs and 3.1 cfs respectively.
Basin 3 (0.29 ac) drains overland across the new ditch access road (gravel surface), and
existing vegetated areas at slopes ranging from 1.55% to 4.0%, towards Lake Canal.
The drainage pattern within this basin mimics pre-project drainage patterns. The 10
and 100-year peak discharges are estimated to be 0.6 cfs and 1.8 cfs respectively.
Offsite Basin O1 (0.46 ac) drains overland across the pavement on Timberline Road to
the proposed vertical curb and gutter on the west side of the southbound lane. The 10
and 100-year peak discharges are estimated to be 2.2 cfs and 4.1 cfs respectively.
Calculations made as part of this investigation, along with other supporting material,
are contained in Appendix A.
4.4 Proposed Detention/Water Quality Pond
The proposed detention/water quality pond is located in the southwest portion of the
property, adjacent to Lake Canal. The pond will detain stormwater runoff from onsite
Basins 1, 1A, and 2. Detention Pond 1 will also act as a rain garden to meet LID
Timberline-International PDP
August 14, 2020
Page 5
requirements.
Detention Pond 1 will provide stormwater detention for events exceeding the WQCV.
The pond has been designed to accommodate the 100-yr flood control volume above
the WQCV. The standard City of Fort Collins Water Quality Outlet Structure will be
used to control the 100-year stormwater release.
The property lies within the Dry Creek Drainage Basin, which requires runoff from the
100-year developed storm to be released at a maximum rate of 0.20 cfs/ac.
Stormwater runoff from onsite Basins 1, 1A, and 2 (0.99 acres) will be released at this
rate. Stormwater runoff from Basin 3 cannot be captured and routed to an onsite
facility, and will therefore drain directly to Lake Canal. The maximum allowable
release from the developed site is 0.20 cfs/ac x 0.99 acres= 0.20 cfs.
As per Colorado Revised Statutes 37-92-602(8), criteria regarding detention drain time
will apply to this project. The spreadsheet (SDI_Design_Data_v1.08.xlsm) developed
by the UDFCD and State of Colorado Division of Water Resources has been used to
verify the 5 and 100-year drain times. The time to drain 97% of all runoff from a
rainfall event that is less than or equal to a 5-year storm drains within 4.6 hours after
the end of the storm event. The time to drain 99% of all runoff, from a rainfall event
that is greater than a 5-year storm, is within 17.4 hours after the end of the storm event.
The completed spreadsheet has been provided in Appendix B of this report.
The computer program, Hydraflow Hydrographs Extension for AutoCAD Civil 3D 2016
was used to route the 100-year design storm through the detention pond. An inflow
hydrograph was developed to route the 100-year storm through the detention pond,
which includes Basins 1, 1A, and 2 (0.99 acres).
Results of the pond routing predict a maximum 100-yr water surface elevation of
4935.78, with an associated storage requirement of 2,602 cu-ft. A 1.75” diameter
orifice will control the release of developed stormwater runoff at a maximum rate of
0.11 cfs. The 100-year storm was routed through the pond, beginning at an elevation
of 4934.76, which is the top of the Water Quality Capture Volume (WQCV=0.015 ac-ft).
An emergency pond overflow weir has also been designed to pass the 100-year peak
inflow (6.8 cfs) to the pond. The notch elevation of the weir will be set at 4937.50, and
the top at an elevation of 4938.00, and will be 10’ in width. The weir will direct
stormwater runoff to the historic discharge location, which is the Lake Canal.
Bioretention has also been incorporated into the detention pond design. The
computer programs UD-BMP (v3.07), developed by the Mile High Flood District
(MHFD), has been used to calculate the required Water Quality Capture Volume
(WQCV), and orifice size based on a 12-hour drain time.
There will be two bioretention areas, one for Basins 1 and 1A, and a second area for
Basin 2. The WQCV calculations have been determined separately for each area, based
Timberline-International PDP
August 14, 2020
Page 6
on fully developed conditions.
Based on the Rain Garden (RG) design procedure in the UD-BMP spreadsheet, the
calculated design volume for Rain Garden No. 1 is 240 cu-ft, and includes runoff from
onsite Basins 1 and 1A. The total volume provided in Rain Garden No. 1 is 2,347 cu-ft.
Based on the Rain Garden (RG) design procedure in the UD-BMP spreadsheet, the
calculated design volume for Rain Garden No. 2 is 191 cu-ft, and includes runoff from
onsite Basin 2 only. The total volume of Rain Garden No. 2 is 2,432cu-ft from elevation
4936.5 to 4937.0.
Calculations made as part of this pond analysis, along with other supporting material,
are contained in Appendix C.
5. DESIGN CRITERIA
5.1 Design References
Drainage design criteria outlined in the City of Fort Collins Stormwater Criteria Manual
(Reference 1), and the Urban Storm Drainage Criteria Manual by the Mile High Flood
District (Reference 2), have been referenced in the preparation of this study.
5.2 Hydrologic Criteria
Due to the relatively small basin size, and in keeping with criteria set forth in the City of
Fort Collins, Stormwater Criteria Manual, the Rational Method has been used to
estimate peak stormwater runoff from the project site.
The initial 2 and 10-year, and major 100-year design storms have been used to evaluate
the proposed drainage system. Rainfall intensity data for the Rational Method has
been taken from IDF equations generated specifically for the project site using the
Hydraflow Hydrographs Extension computer software from Autodesk. Point
precipitation frequency estimates were generated using the NOAA Atlas 14,
Precipitation Data Frequency Server, which are site -specific. The site-specific rainfall
intensities generated from the Data Frequency Server are higher that the intensities
shown in Figure RA-15 of Volume 1 of the UDFCD Drainage Criteria Manual.
Runoff coefficients were derived using the equations described in Table 6-4 from the
Urban Storm Drainage Criteria Manual, Volume 1, Chapter 6, Section 2.5.1 by the Mile
High Flood District. The area of all impervious surfaces was determined for each
drainage basin, including roads, walk, and roofs. It is a much more laborious effort but
provides a more realistic estimate of peak discharge from the developed site.
We believe that using site-specific rainfall data and determining the area of impervious
surfaces for each drainage basin results in the most accurate representation of peak
discharge from both the historic and developed sites.
Timberline-International PDP
August 14, 2020
Page 7
6. EROSION CONTROL
6.1 Low Impact Design (LID)
The proposed project has incorporated the 4-step process developed by the Mile High
Flood District (MHFD), for the protection of receiving waters downstream of the project
site. The BMP Selection Tool within the UD-BMP spreadsheet has been used to select
the appropriate BMPs for Steps 1 and 2 of the 4-step process. The project implements
volume reduction strategies including grass swales, and WQCV BMPs including
Bioretention – Partial Infiltration Basins.
Low Impact Development (LID) is a comprehensive land planning and engineering
design approach to managing stormwater runoff with a goal of replicating the
pre-development hydrologic regime of urban and developing watersheds. Volume 3 of
the UDFCD Drainage Criteria Manual emphasizes LID criteria, including Minimizing
Directly Connected Impervious Areas (MDCIA) as the first step in stormwater quality
planning and has provided guidance on LID techniques such as grass swales, grass
buffers, permeable pavement systems, bioretention, and pollution prevention
(pollutant source controls).
Low Impact Development (LID) design will be required for this project using methods
and techniques described in Volume 3, Chapter 1, Section 4.1, Runoff Reduction
Practices. The Water Quality Capture Volume (WQCV) will be treated using an
Extended Detention Basin (EDB) with a recommended 40-hour drain time, as per the
UD-Detention spreadsheet. The opportunity to implementation multiple LID
techniques are limited, due to the size of the site (1.39 acres). Surface runoff from
impervious areas generally drains directly to the detention pond/water quality facility,
which includes two bioretention areas. The length and depth of grass buffers and
grass swales is employed to some extent, but is limited.
The project has also been designed to minimize impacts to the site, and conserve
existing amenities. One example of this would be minimizing the disturbance in
drainage Basin 3 along the east side of Lake Canal, and retaining the existing vegetation.
With the exception of a small portion of the drive entrance, nearly 100% of all newly
added or modified impervious area will be treated by LID techniques. The technique
to be employed will include two bioretention areas (rain gardens), which will be located
within the stormwater detention/EDB pond. The clayey sand, and sand and gravel
layer will facilitate a Partial Infiltration Section as it relates to bioretention. A
perforated underdrain will be installed beneath the bioretention areas in order to
hydraulically connect the two areas.
Calculations made as part of this LID analysis, along with other supporting material, are
contained in Appendix C.
Timberline-International PDP
August 14, 2020
Page 8
6.2 Erosion Control Plan
A proposed rainfall erosion control plan during construction will consist of temporary
structural erosion control measures. Erosion control measures have been specified on
the Grading and Erosion Control Plan, and on three separate drawings contained in the
written Stormwater Management Plan (SWMP). These drawings include a
Pre-disturbance, Interim, and Final Stabilization Plans.
Wohnrade Civil Engineers, Inc. will prepare a separate report containing the
Stormwater Management Plan (SWMP) for this project. A Colorado Discharge Permit
System (CDPS), Stormwater Discharge Associated with Construction Activities
application will also be submitted to the Colorado Department of Public Health and
Environment.
A City of Fort Collins Erosion and Sediment Control Escrow/Security Calculation has
been prepared for this project, and will be included in the written SWMP report.
6.3 Site Stabilization
All areas disturbed by construction will be landscaped, paved, or re-seeded using the
recommended seed varieties, quantities, and application rates as specified on the
project Landscape Plan.
7. CONCLUSIONS
7.1 Compliance with Standards
The proposed drainage improvements been designed to comply with all applicable
drainage criteria, in accordance with the City of Fort Collins Stormwater Criteria
Manual.
7.2 Variances
There are no variances requested as part of this stormwater drainage design.
8. REFERENCES
1. Stormwater Criteria Manual, City of Fort Collins, adopted December 2011.
2. Urban Storm Drainage Criteria Manual, Mile High Flood District, Denver, Colorado,
Revised April 2008.
3. CDOT Drainage Design Manual, Colorado Department of Transportation.
4. Geotechnical Investigation, Proposed Commercial Development, Lot 1, Industrial
Business Park, CTL Thompson, Inc., October 1, 2018.
Project Location
125
S.
Howes
Street
2nd
Floor
Fort
Collins,
CO
80521
Justin
Green
Lake
Canal
Sent
via
email:
justin@lakecanal.com
RE:
Requested
Storm
Water
Outfall
into
Lake
Canal
Mr.
Green;
FR
Holdings,
Ltd.
is
the
owner
of
Lot
1
in
the
Industrial
Business
Park
PUD
in
Fort
Collins,
a
1.39
acre
parcel
that
borders
Lake
Canal
at
the
north
west
intersection
of
Appendix A
Timberline-International
Preliminary Development Plan
August 21, 2020
Runoff Coefficient Calculations
Post-Project Interim Condition, Basin 1
NRCS Soil Type B
Surface Characteristics
Streets:
Paved
Streets:
Gravel
Concrete
Drives
& Walks
Roofs Lawns:
Sandy
Soil
Imperviousness
Area (acres) 0.028 0.000 0.015 0.007 0.240 0.18
Percent Imperviousness 100 40 90 90 2
Total Area (acres) 0.29
NRCS Soil Type
2-Year 5-Year 10-Year 25-Year 50-Year 100-Year 500-Year
A 0.09 0.10 0.11 0.12 0.18 0.25 0.37
B 0.11 0.13 0.20 0.36 0.43 0.51 0.60
C/D 0.12 0.18 0.27 0.42 0.48 0.56 0.65
Post-Project Interim Condition, Basin 2
NRCS Soil Type B
Surface Characteristics
Streets:
Paved
Streets:
Gravel
Concrete
Drives
& Walks
Roofs Lawns:
Sandy
Soil
Imperviousness
Area (acres) 0.125 0.000 0.020 0.029 0.296 0.37
Percent Imperviousness 100 40 90 90 2
Total Area (acres) 0.47
NRCS Soil Type
2-Year 5-Year 10-Year 25-Year 50-Year 100-Year 500-Year
A 0.23 0.24 0.26 0.28 0.34 0.40 0.50
B 0.26 0.29 0.36 0.48 0.54 0.60 0.67
C/D 0.27 0.34 0.41 0.53 0.58 0.64 0.71
Storm Return Period
Runoff coefficient equations taken from Table 6-4 of the Urban Storm Drainage Criteria Manual,
Volume 1, Chapter 6, Section 2.5.1
Runoff coefficient equations taken from Table 6-4 of the Urban Storm Drainage Criteria Manual,
Volume 1, Chapter 6, Section 2.5.1
Storm Return Period
Page 1 of 3
Timberline-International
Preliminary Development Plan
August 21, 2020
Runoff Coefficient Calculations
Post-Project Interim Condition, Basin 3
NRCS Soil Type B
Surface Characteristics
Streets:
Paved
Streets:
Gravel
Concrete
Drives
& Walks
Roofs Lawns:
Sandy
Soil
Imperviousness
Area (acres) 0.090 0.000 0.000 0.000 0.200 0.32
Percent Imperviousness 100 40 90 90 2
Total Area (acres) 0.29
NRCS Soil Type
2-Year 5-Year 10-Year 25-Year 50-Year 100-Year 500-Year
A 0.19 0.20 0.22 0.24 0.30 0.36 0.46
B 0.23 0.25 0.32 0.45 0.51 0.58 0.66
C/D 0.23 0.30 0.37 0.50 0.55 0.62 0.69
NRCS Soil Type B
Surface Characteristics
Streets:
Paved
Streets:
Gravel
Concrete
Drives
& Walks
Roofs Lawns:
Sandy
Soil
Imperviousness
Area (acres) 0.118 0.000 0.038 0.036 0.038 0.81
Percent Imperviousness 100 40 90 90 2
Total Area (acres) 0.23
NRCS Soil Type
2-Year 5-Year 10-Year 25-Year 50-Year 100-Year 500-Year
A 0.63 0.65 0.67 0.66 0.71 0.74 0.78
B 0.65 0.68 0.71 0.76 0.78 0.80 0.83
C/D 0.65 0.70 0.73 0.77 0.79 0.81 0.85
Runoff coefficient equations taken from Table 6-4 of the Urban Storm Drainage Criteria Manual,
Volume 1, Chapter 6, Section 2.5.1
Storm Return Period
Post-Project Interim Condition, Basin 1A
Runoff coefficient equations taken from Table 6-4 of the Urban Storm Drainage Criteria Manual,
Volume 1, Chapter 6, Section 2.5.1
Storm Return Period
Page 2 of 3
Timberline-International
Preliminary Development Plan
August 21, 2020
Runoff Coefficient Calculations
Post-Project Interim Condition, Basin O1
NRCS Soil Type B
Surface Characteristics
Streets:
Paved
Streets:
Gravel
Concrete
Drives
& Walks
Roofs Lawns:
Sandy
Soil
Imperviousness
Area (acres) 0.367 0.000 0.038 0.000 0.055 0.87
Percent Imperviousness 100 40 90 90 2
Total Area (acres) 0.46
NRCS Soil Type
2-Year 5-Year 10-Year 25-Year 50-Year 100-Year 500-Year
A 0.71 0.72 0.74 0.72 0.77 0.79 0.82
B 0.72 0.74 0.77 0.80 0.82 0.84 0.86
C/D 0.71 0.75 0.78 0.81 0.82 0.84 0.87
Post-Project Interim Condition, Basins 1, 1A, 2 (Detention Pond Inflow)
NRCS Soil Type B
Surface Characteristics
Streets:
Paved
Streets:
Gravel
Concrete
Drives
& Walks
Roofs Lawns:
Sandy
Soil
Imperviousness
Area (acres) 0.271 0.000 0.073 0.072 0.574 0.42
Percent Imperviousness 100 40 90 90 2
Total Area (acres) 0.99
NRCS Soil Type
2-Year 5-Year 10-Year 25-Year 50-Year 100-Year 500-Year
A 0.27 0.28 0.30 0.31 0.38 0.44 0.53
B 0.30 0.33 0.39 0.51 0.56 0.62 0.69
C/D 0.31 0.38 0.44 0.55 0.60 0.66 0.72
Storm Return Period
Runoff coefficient equations taken from Table 6-4 of the Urban Storm Drainage Criteria Manual,
Volume 1, Chapter 6, Section 2.5.1
Storm Return Period
Runoff coefficient equations taken from Table 6-4 of the Urban Storm Drainage Criteria Manual,
Volume 1, Chapter 6, Section 2.5.1
Page 3 of 3
City of Fort Collins, Colorado,
Overland Flow, Time of Concentration:
Ti= 0.395(1.1-C5)L1/2 / S1/3
Gutter/Swale Flow, Time of Concentration:
Tt= L / 60V
Tc= Ti + Tt
Intensity, (i) taken from intensity formula for Timberline-International PDP, i =30.11/(Tc+10.70)0.83 Calculations by: M. Wohnrade
Velocity, (V) taken from Figure 3-1 Project: Timberline-International PDP
Rational Equation: Q = ciA Date: August 21, 2020
C5
Length, L
(ft)
Slope, S
(ft/ft)
Ti
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(fps)
Tt
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(fps)
Tt
(min)
1A 1A 0.0 0.23 0.65 0.68 31.2 0.025 3.2 58.0 2.4 3.15 0.3 0.0 0.0 0.00 0.0 5.0 3.06 0.5
1 1 0.0 0.29 0.11 0.13 19.6 0.211 2.8 0.0 0.0 0.00 0.0 28.0 7.2 4.33 0.1 5.0 3.06 0.1
2 2 0.0 0.47 0.26 0.29 31.8 0.086 4.1 0.0 0.0 0.00 0.0 171.4 2.0 2.28 1.3 5.3 3.01 0.4
3 3 0.0 0.29 0.23 0.25 25.0 0.032 5.3 0.0 0.0 0.00 0.0 0.0 0.0 0.00 0.0 5.3 3.02 0.2
O1 O1 0.0 0.46 0.72 0.74 52.3 0.050 2.8 233.3 0.4 1.29 3.0 0.0 0.0 0.00 0.0 5.8 2.94 1.0
1 1,1A,2 0.0 0.99 0.30 0.33 31.8 0.086 3.9 0.0 0.0 0.00 0.0 171.4 2.0 2.28 1.3 5.1 3.04 0.9
Rainfall intensity values were generated using the NOAA Atlas 14, Precipitation Data Frequency Server, and are specific to the site.
Note:
Tc
(min)
Intensity, i
(in/hr)
Flow, Q
(cfs)
Post-Project Conditions
2-Yr Runoff Computations
Design
Point Basins
Upstream
Time of
Concentration
Tc
Area, A
(acres)
Runoff
Coefficient
c
Overland Flow Gutter/Pipe Flow Swale Flow
City of Fort Collins, Colorado,
Overland Flow, Time of Concentration:
Ti= 0.395(1.1-C5)L1/2 / S1/3
Gutter/Swale Flow, Time of Concentration:
Tt= L / 60V
Tc= Ti + Tt
Intensity, (i) taken from intensity formula for Timberline-International PDP, i =64.81/(Tc+10.70)0.83 Calculations by: M. Wohnrade
Velocity, (V) taken from Figure 3-1 Project: Timberline-International PDP
Rational Equation: Q = ciA Date: August 21, 2020
C5
Length, L
(ft)
Slope, S
(ft/ft)
Ti
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(fps)
Tt
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(fps)
Tt
(min)
1A 1A 0.0 0.23 0.71 0.68 31.2 0.025 3.2 58.0 2.4 3.15 0.3 0.0 0.0 0.00 0.0 5.0 6.59 1.1
1 1 0.0 0.29 0.20 0.13 19.6 0.211 2.8 0.0 0.0 0.00 0.0 28.0 7.2 4.33 0.1 5.0 6.59 0.4
2 2 0.0 0.47 0.36 0.29 31.8 0.086 4.1 0.0 0.0 0.00 0.0 171.4 2.0 2.28 1.3 5.3 6.48 1.1
3 3 0.0 0.29 0.32 0.25 25.0 0.032 5.3 0.0 0.0 0.00 0.0 0.0 0.0 0.00 0.0 5.3 6.49 0.6
O1 O1 0.0 0.46 0.77 0.74 52.3 0.050 2.8 233.3 0.4 1.29 3.0 0.0 0.0 0.00 0.0 5.8 6.32 2.2
1 1,1A,2 0.0 0.99 0.39 0.33 31.8 0.086 3.9 0.0 0.0 0.00 0.0 171.4 2.0 2.28 1.3 5.1 6.54 2.5
Note:
Rainfall intensity values were generated using the NOAA Atlas 14, Precipitation Data Frequency Server, and are specific to the site.
Post-Project Conditions
10-Yr Runoff Computations
Design
Point Basins
Upstream
Time of
Concentration
Tc
Area, A
(acres)
Runoff
Coefficient
c
Overland Flow Gutter/Pipe Flow Swale Flow
Tc
(min)
Intensity, i
(in/hr)
Flow, Q
(cfs)
City of Fort Collins, Colorado,
Overland Flow, Time of Concentration:
Ti= 0.395(1.1-C5)L1/2 / S1/3
Gutter/Swale Flow, Time of Concentration:
Tt= L / 60V
Tc= Ti + Tt
Intensity, (i) taken from intensity formula for Timberline-International PDP, i =109.19/(Tc+10.70)0.83 Calculations by: M. Wohnrade
Velocity, (V) taken from Figure 3-1 Project: Timberline-International PDP
Rational Equation: Q = ciA Date: August 21, 2020
C5
Length, L
(ft)
Slope, S
(ft/ft)
Ti
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(fps)
Tt
(min)
Length, L
(ft)
Slope, S
(%)
Velocity, V
(fps)
Tt
(min)
1A 1A 0.0 0.23 0.80 0.68 31.2 0.025 3.2 58.0 2.4 3.15 0.3 0.0 0.0 0.00 0.0 5.0 11.11 2.0
1 1 0.0 0.29 0.51 0.13 19.6 0.211 2.8 0.0 0.0 0.00 0.0 28.0 7.2 4.33 0.1 5.0 11.11 1.6
2 2 0.0 0.47 0.60 0.29 31.8 0.086 4.1 0.0 0.0 0.00 0.0 171.4 2.0 2.28 1.3 5.3 10.91 3.1
3 3 0.0 0.29 0.58 0.25 25.0 0.032 5.3 0.0 0.0 0.00 0.0 0.0 0.0 0.00 0.0 5.3 10.94 1.8
O1 O1 0.0 0.46 0.84 0.74 52.3 0.050 2.8 233.3 0.4 1.29 3.0 0.0 0.0 0.00 0.0 5.8 10.65 4.1
1 1,1A,2 0.0 0.99 0.62 0.33 31.8 0.086 3.9 0.0 0.0 0.00 0.0 171.4 2.0 2.28 1.3 5.1 11.03 6.8
Note:
Rainfall intensity values were generated using the NOAA Atlas 14, Precipitation Data Frequency Server, and are specific to the site.
Post-Project Conditions
100-Yr Runoff Computations
Design
Point Basins
Upstream
Time of
Concentration
Tc
Area, A
(acres)
Runoff
Coefficient
c
Overland Flow Gutter/Pipe Flow Swale Flow
Tc
(min)
Intensity, i
(in/hr)
Flow, Q
(cfs)
WOHNRADE CIVIL ENGINEERS,
Precipitation Frequency Data Server 7/22/18, 7:26 AM
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.5887&lon=-105.0300&data=depth&units=english&series=pds Page 1 of 4
NOAA Atlas 14, Volume 8, Version 2
Location name: Fort Collins, Colorado, USA*
Latitude: 40.5887°, Longitude: -105.03°
Elevation: 4942.3 ft**
* source: ESRI Maps
** source: USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
Sanja Perica, Deborah Martin, Sandra Pavlovic, Ishani Roy, Michael St. Laurent, Carl Trypaluk, Dale
Unruh, Michael Yekta, Geoffery Bonnin
NOAA, National Weather Service, Silver Spring, Maryland
PF_tabular | PF_graphical | Maps_&_aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1
Duration
Average recurrence interval (years)
1 2 5 10 25 50 100 200 500 1000
5-min 0.261
(0.208‑0.321)
0.308
(0.246‑0.379)
0.406
(0.323‑0.501)
0.507
(0.401‑0.629)
0.677
(0.529‑0.906)
0.831
(0.626‑1.12)
1.01
(0.727‑1.38)
1.20
(0.829‑1.69)
1.50
(0.986‑2.16)
1.75
(1.11‑2.51)
10-min 0.382
(0.305‑0.470)
0.450
(0.360‑0.555)
0.594
(0.473‑0.734)
0.743
(0.587‑0.922)
0.991
(0.775‑1.33)
1.22
(0.916‑1.63)
1.47
(1.06‑2.02)
1.76
(1.21‑2.48)
2.19
(1.44‑3.16)
2.56
(1.62‑3.68)
15-min 0.465
(0.372‑0.573)
Precipitation Frequency Data Server 7/22/18, 7:26 AM
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.5887&lon=-105.0300&data=depth&units=english&series=pds Page 2 of 4
PF graphical
Back to Top
Maps & aerials
Small scale terrain
Precipitation Frequency Data Server 7/22/18, 7:26 AM
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.5887&lon=-105.0300&data=depth&units=english&series=pds Page 3 of 4
Large scale terrain
Large scale map
Large scale aerial
+
–
3km
2mi
+
–
100km
60mi
+
–
100km
60mi
Precipitation Frequency Data Server 7/22/18, 7:26 AM
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=40.5887&lon=-105.0300&data=depth&units=english&series=pds Page 4 of 4
Back to Top
US Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring, MD 20910
Questions?: HDSC.Questions@noaa.gov
Disclaimer
+
–
100km
60mi
6-8 Urban Drainage and Flood Control District March 2017
Urban Storm Drainage Criteria Manual Volume 1
Table 6-3. Recommended percentage imperviousness values
Land Use or Percentage Imperviousness
Surface Characteristics (%)
Business:
Downtown Areas 95
Suburban Areas 75
Residential lots (lot area only):
Single-family
2.5 acres or larger 12
0.75 – 2.5 acres 20
0.25 – 0.75 acres 30
0.25 acres or less 45
Apartments 75
Industrial:
Light areas 80
Heavy areas 90
Parks, cemeteries 10
Playgrounds 25
Schools 55
Railroad yard areas 50
Undeveloped Areas:
Historic flow analysis 2
Greenbelts, agricultural 2
Off-site flow analysis (when land use not
defined)
45
Streets:
Paved 100
Gravel (packed) 40
Drive and walks 90
Roofs 90
Lawns, sandy soil 2
Lawns, clayey soil 2
Hydraflow Rainfall Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2018 by Autodesk, Inc. v12 Sunday, 07 / 22 / 2018
Return Intensity-Duration-Frequency Equation Coefficients (FHA)
Period
(Yrs) B D E (N/A)
1 0.0000 0.0000 0.0000 --------
2 30.1069 10.7000 0.8283 --------
3 0.0000 0.0000 0.0000 --------
5 49.7989 10.7000 0.8283 --------
10 64.8100 10.7000 0.8283 --------
25 81.7580 10.7000 0.8283 --------
50 96.2848 10.7000 0.8283 --------
100 109.1975 10.7000 0.8283 --------
File name: LEG.IDF
Intensity = B / (Tc + D)^E
Return Intensity Values (in/hr)
Period
(Yrs) 5 min 10 15 20 25 30 35 40 45 50 55 60
1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
2 3.08 2.45 2.05 1.77 1.56 1.40 1.27 1.17 1.08 1.00 0.94 0.88
3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
5 5.09 4.05 3.38 2.92 2.58 2.31 2.10 1.93 1.78 1.66 1.55 1.46
10 6.62 5.27 4.40 3.80 3.35 3.01 2.73 2.51 2.32 2.16 2.02 1.90
25 8.35 6.64 5.55 4.79 4.23 3.80 3.45 3.16 2.93 2.73 2.55 2.40
50 9.84 7.83 6.54 5.65 4.98 4.47 4.06 3.73 3.45 3.21 3.01 2.83
100 11.16 8.87 7.42 6.40 5.65 5.07 4.61 4.23 3.91 3.64 3.41 3.21
Tc = time in minutes. Values may exceed 60.
Rainfall Precipitation Table (in)
Precip. file name: S:\PROJECTS\CR16\DRNG\CR16-Civil 3D Hydroflow Rainfall Data.pcp
Storm
Distribution 1-yr 2-yr 3-yr 5-yr 10-yr 25-yr 50-yr 100-yr
SCS 24-hour 0.00 1.78 0.00 2.28 4.25 5.77 6.80 4.63
SCS 6-Hr 0.00 1.23 0.00 1.61 2.60 0.00 0.00 3.76
Huff-1st 0.00 0.00 0.00 0.00 4.00 5.38 6.50 0.00
Huff-2nd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-3rd 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-4th 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Huff-Indy 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00
Custom 0.00 0.00 0.00 0.00 3.90 5.25 6.00 0.00
0 5 10 15 20 25 30 35 40 45 50 55 60
Intensity (in/hr)
0.00 0.00
2.00 2.00
4.00 4.00
6.00 6.00
8.00 8.00
10.00 10.00
12.00 12.00
14.00 14.00
Time (min)
IDF file: LEG.IDF
Hydrographs
Hydraflow IDF Curves
Appendix B
Project:
Basin ID:
Depth Increment = ft
Required Volume Calculation Top of Micropool -- 0.00 -- -- -- 0 0.000
Selected BMP Type = EDB -- 1.00 -- -- -- 2,576 0.059 1,262 0.029
Watershed Area = 0.99 acres Note: L / W Ratio < 1
-- 2.00 -- -- -- 3,601 0.083 4,340 0.100
Watershed Length = 187 ft L / W Ratio = 0.8 -- 3.00 -- -- -- 8,714 0.200 10,534 0.242
Watershed Slope = 0.007 ft/ft -- 4.00 -- -- -- 15,540 0.357 22,661 0.520
Watershed Imperviousness = 42.00% percent -- -- -- --
Percentage Hydrologic Soil Group A = 0.0% percent -- -- -- --
Percentage Hydrologic Soil Group B = 100.0% percent -- -- -- --
Percentage Hydrologic Soil Groups C/D = 0.0% percent -- -- -- --
Desired WQCV Drain Time = 40.0 hours -- -- -- --
Location for 1-hr Rainfall Depths = Denver - Capitol Building -- -- -- --
Water Quality Capture Volume (WQCV) = 0.015 acre-feet -- -- -- --
Excess Urban Runoff Volume (EURV) = 0.044 acre-feet -- -- -- --
2-yr Runoff Volume (P1 = 0.87 in.) = 0.025 acre-feet 0.87 inches -- -- -- --
5-yr Runoff Volume (P1 = 1.15 in.) = 0.037 acre-feet 1.15 inches -- -- -- --
10-yr Runoff Volume (P1 = 1.45 in.) = 0.056 acre-feet 1.45 inches -- -- -- --
25-yr Runoff Volume (P1 = 1.96 in.) = 0.098 acre-feet 1.96 inches -- -- -- --
50-yr Runoff Volume (P1 = 2.43 in.) = 0.132 acre-feet 2.43 inches -- -- -- --
100-yr Runoff Volume (P1 = 2.97 in.) = 0.177 acre-feet 2.97 inches -- -- -- --
500-yr Runoff Volume (P1 = 4.5 in.) = 0.299 acre-feet 4.50 inches -- -- -- --
Approximate 2-yr Detention Volume = 0.024 acre-feet -- -- -- --
Approximate 5-yr Detention Volume = 0.035 acre-feet -- -- -- --
Approximate 10-yr Detention Volume = 0.051 acre-feet -- -- -- --
Approximate 25-yr Detention Volume = 0.067 acre-feet -- -- -- --
Approximate 50-yr Detention Volume = 0.078 acre-feet -- -- -- --
Approximate 100-yr Detention Volume = 0.096 acre-feet -- -- -- --
-- -- -- --
Stage-Storage Calculation -- -- -- --
Zone 1 Volume (WQCV) = 0.015 acre-feet -- -- -- --
Zone 2 Volume (100-year - Zone 1) = 0.081 acre-feet
-- -- -- --
Select Zone 3 Storage Volume (Optional) = acre-feet
-- -- -- --
Total Detention Basin Volume = 0.096 acre-feet
-- -- -- --
Initial Surcharge Volume (ISV) = user ft^3
-- -- -- --
Initial Surcharge Depth (ISD) = user ft
-- -- -- --
Total Available Detention Depth (Htotal) = user
ft -- -- -- --
Depth of Trickle Channel (HTC) = user ft
-- -- -- --
Slope of Trickle Channel (STC) = user
ft/ft -- -- -- --
Slopes of Main Basin Sides (Smain) = user
H:V -- -- -- --
Basin Length-to-Width Ratio (RL/W) = user -- -- -- --
-- -- -- --
Initial Surcharge Area (AISV) = user ft^2
-- -- -- --
Surcharge Volume Length (LISV) = user ft
-- -- -- --
Surcharge Volume Width (WISV) = user ft
-- -- -- --
Depth of Basin Floor (HFLOOR) = user ft
1 User Defined Stage-Area Boolean for Message
1 Equal Stage-Area Inputs 1 Watershed L:W
1 CountA
0 Calc_S_TC
H_FLOOR
L_FLOOR_OTHER
0.00 ISV 0.00 ISV
0.00 Floor 0.00 Floor
0.72 Zone 1 (WQCV) 0.72 Zone 1 (WQCV)
1.96 Zone 2 (100-year) 1.96 Zone 2 (100-year)
0.00 Zone 3 0.00 Zone 3
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
UD-Detention, Version 3.07 (February 2017)
0.000
0.135
0.270
0.405
0.540
0.000
0.090
0.180
0.270
0.360
0.00 1.00 2.00 3.00 4.00
Volume (ac-ft)
Area (acres)
Stage (ft.)
Area (acres) Volume (ac-ft)
0
100
200
300
400
0
5
10
15
20
0.00 1.00 2.00 3.00 4.00
Area (sq.ft.)
Length, Width (ft.)
Stage (ft)
Length (ft) Width (ft) Area (sq.ft.)
UD-Detention_v3.07.xlsm, Basin 8/21/2020, 10:06 AM
Project:
Basin ID:
Stage (ft) Zone Volume (ac-ft) Outlet Type
Zone 1 (WQCV) 0.72 0.015 Orifice Plate
Zone 2 (100-year) 1.96 0.081 Circular Orifice
Zone 3
0.096 Total
User Input: Orifice at Underdrain Outlet (typically used to drain WQCV in a Filtration BMP) Calculated Parameters for Underdrain
Underdrain Orifice Invert Depth = N/A ft (distance below the filtration media surface) Underdrain Orifice Area = N/A ft
2
Underdrain Orifice Diameter = N/A inches Underdrain Orifice Centroid = N/A feet
User Input: Orifice Plate with one or more orifices or Elliptical Slot Weir (typically used to drain WQCV and/or EURV in a sedimentation BMP) Calculated Parameters for Plate
Invert of Lowest Orifice = 0.00 ft (relative to basin bottom at Stage = 0 ft) WQ Orifice Area per Row = 9.028E-04 ft
2
Depth at top of Zone using Orifice Plate = 0.72 ft (relative to basin bottom at Stage = 0 ft) Elliptical Half-Width = N/A feet
Orifice Plate: Orifice Vertical Spacing = 2.90 inches Elliptical Slot Centroid = N/A feet
Orifice Plate: Orifice Area per Row = 0.13 sq. inches (diameter = 3/8 inch) Elliptical Slot Area = N/A ft
2
User Input: Stage and Total Area of Each Orifice Row (numbered from lowest to highest)
Row 1 (required) Row 2 (optional) Row 3 (optional) Row 4 (optional) Row 5 (optional) Row 6 (optional) Row 7 (optional) Row 8 (optional)
Stage of Orifice Centroid (ft) 0.00 0.24 0.48
Orifice Area (sq. inches) 0.13 0.13 0.13
Row 9 (optional) Row 10 (optional) Row 11 (optional) Row 12 (optional) Row 13 (optional) Row 14 (optional) Row 15 (optional) Row 16 (optional)
Stage of Orifice Centroid (ft)
Orifice Area (sq. inches)
User Input: Vertical Orifice (Circular or Rectangular) Calculated Parameters for Vertical Orifice
Zone 2 Circular Not Selected Zone 2 Circular Not Selected
Invert of Vertical Orifice = 0.72 ft (relative to basin bottom at Stage = 0 ft) Vertical Orifice Area = ft
2
Depth at top of Zone using Vertical Orifice = 1.96 ft (relative to basin bottom at Stage = 0 ft) Vertical Orifice Centroid = feet
Vertical Orifice Diameter = inches
User Input: Overflow Weir (Dropbox) and Grate (Flat or Sloped) Calculated Parameters for Overflow Weir
Not Selected Not Selected Not Selected Not Selected
Overflow Weir Front Edge Height, Ho = ft (relative to basin bottom at Stage = 0 ft) Height of Grate Upper Edge, Ht
= feet
Overflow Weir Front Edge Length = feet Over Flow Weir Slope Length = feet
Overflow Weir Slope = H:V (enter zero for flat grate) Grate Open Area / 100-yr Orifice Area = should be > 4
Horiz. Length of Weir Sides = feet Overflow Grate Open Area w/o Debris = ft
2
Overflow Grate Open Area % = %, grate open area/total area Overflow Grate Open Area w/ Debris = ft
2
Debris Clogging % = %
User Input: Outlet Pipe w/ Flow Restriction Plate (Circular Orifice, Restrictor Plate, or Rectangular Orifice) Calculated Parameters for Outlet Pipe w/ Flow Restriction Plate
Not Selected Not Selected Not Selected Not Selected
Depth to Invert of Outlet Pipe = ft (distance below basin bottom at Stage = 0 ft) Outlet Orifice Area = ft
2
Circular Orifice Diameter = inches Outlet Orifice Centroid = feet
Half-Central Angle of Restrictor Plate on Pipe = N/A N/A radians
User Input: Emergency Spillway (Rectangular or Trapezoidal) Calculated Parameters for Spillway
Spillway Invert Stage= ft (relative to basin bottom at Stage = 0 ft) Spillway Design Flow Depth= feet
Spillway Crest Length = feet Stage at Top of Freeboard = feet
Spillway End Slopes = H:V Basin Area at Top of Freeboard = acres
Freeboard above Max Water Surface = feet
Routed Hydrograph Results
Design Storm Return Period = WQCV EURV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 500 Year
One-Hour Rainfall Depth (in) = 0.53 1.07 0.87 1.15 1.45 1.96 2.43 2.97 4.50
Calculated Runoff Volume (acre-ft) = 0.015 0.044 0.025 0.037 0.056 0.098 0.132 0.177 0.299
OPTIONAL Override Runoff Volume (acre-ft) =
Inflow Hydrograph Volume (acre-ft) = 0.015 0.043 0.025 0.036 0.055 0.098 0.131 0.176 0.298
Predevelopment Unit Peak Flow, q (cfs/acre) = 0.00 0.00 0.01 0.02 0.20 0.75 1.14 1.66 2.97
COUNTA for Basin Tab = 1 Ao Dia WQ Plate Type Vert Orifice 1 Vert Orifice 2
Count_Underdrain = 0 0.11(diameter = 3/8 inch) 2 2 1
Count_WQPlate = 1 0.1(4diameter = 7/16 inch)
Count_VertOrifice1 = 0 0.18(diameter = 1/2 inch) Outlet Plate 1 Outlet Plate 2 Drain Time Message Boolean
Count_VertOrifice2 = 0 0.2(4diameter = 9/16 inch) 1 1 5yr, <72hr 0
Count_Weir1 = 0 0.29(diameter = 5/8 inch) >5yr, <120hr 0
Count_Weir2 = 0 0.(36 diameter = 11/16 inch) Max Depth Row
Count_OutletPipe1 = 0 0.42(diameter = 3/4 inch) WQCV 68 Watershed Constraint Check
Count_OutletPipe2 = 0 0.(50 diameter = 13/16 inch) 2 Year 90 Slope 0.010
COUNTA_2 (Standard FSD Setup)= 0 0.58(diameter = 7/8 inch) EURV 119 Shape 1.00
MaxPondDepth_Error? FALSE 0.(67 diameter = 15/16 inch) 5 Year 109
Hidden Parameters & Calculations 0.76 (diameter = 1 inch) 10 Year 137 Spillway Depth
(diameter 0.86 = 1-1/16 inches) 25 Year 193
WQ Plate Flow at 100yr depth = 0.02 (0.diameter 97 = 1-1/8 inches) 50 Year 229
CLOG #1= 0% (diameter 1.08 = 1-3/16 inches) 100 Year 262 1 Z1_Boolean
Cdw #1 = (1.diameter 20 = 1-1/4 inches) 500 Year 325 0 Z2_Boolean
Cdo #1 = (diameter 1.32 = 1-5/16 inches) Zone3_Pulldown Message 1 Z3_Boolean
Overflow Weir #1 Angle = (1.diameter 45 = 1-3/8 inches) 1 Opening Message
CLOG #2= 0% (diameter 1.59 = 1-7/16 inches) Draintime Running
Cdw #2 = (1.diameter 73 = 1-1/2 inches) Outlet Boolean Outlet Rank Total (1 to 4)
Cdo #2 = (diameter 1.88 = 1-9/16 inches) Vertical Orifice 1 0 0 0
Overflow Weir #2 Angle = (2.diameter 03 = 1-5/8 inches) Vertical Orifice 2 0 0 Boolean
Underdrain Q at 100yr depth = 0.00 (diameter 2.20 = 1-11/16 inches) Overflow Weir 1 0 0 0 Max Depth
VertOrifice1 Q at 100yr depth = 0.00 (2.diameter 36 = 1-3/4 inches) Overflow Weir 2 0 0 0 500yr Depth
VertOrifice2 Q at 100yr depth = 0.00 (diameter 2.54 = 1-13/16 inches) Outlet Pipe 1 0 0 0 Freeboard
EURV_draintime_user = (2.diameter 72 = 1-7/8 inches) Outlet Pipe 2 0 0 0 Spillway
Count_User_Hydrographs 0 (diameter 2.90 = 1-15/16 inches) 0 Spillway Length
CountA_3 (EURV & 100yr) = 0 3.09(diameter = 2 inches) Button Visibility Boolean FALSE Time Interval
CountA_4 (100yr Only) = 0 (use 3.29 rectangular openings) 1 Button_Trigger
0 Underdrain
1 WQCV Plate
0 EURV-WQCV Plate
0 EURV-WQCV VertOrifice
0 Outlet 90% Qpeak
0 Outlet Undetained
S-A-V-D Chart Axis Override X-axis Left Y-Axis Right Y-Axis
minimum bound
maximum bound
UD-Detention, Version 3.07 (February 2017)
Detention Basin Outlet Structure Design
0
1
2
3
4
5
6
0.1 1 10
FLOW [cfs]
TIME [hr]
500YR IN
500YR OUT
100YR IN
100YR OUT
50YR IN
50YR OUT
25YR IN
25YR OUT
10YR IN
10YR OUT
Detention Pond 1 Stage-Storage Rating
Project: 142 Timberline
Basin Description: Detention Pond 1
Contour Contour Depth Incremental Cumulative Incremental Cumulative
Elevation Area (ft) Volume Volume Volume Volume
(sq. ft) Avg. End Avg. End Conic Conic
(cu. ft) (cu. ft) (cu. ft) (cu. ft)
4,934.00 0.00 N/A N/A 0.00 N/A 0.00
4,935.00 2,576.02 1.00 1288.01 1288.01 858.67 858.67
4,936.00 3,600.56 1.00 3088.29 4376.30 3074.03 3932.71
4,937.00 8,714.26 1.00 6157.41 10533.72 5972.09 9904.80
4,938.00 15,540.49 1.00 12127.38 22661.10 11963.98 21868.78
Detention Pond 1 Stage-Storage Rating Above WQCV
Project: 142 Timberline
Basin Description: Detention Pond 1
Contour Contour Depth Incremental Cumulative
Elevation Area (ft) Volume Volume
(sq. ft) Conic Conic
(cu. ft) (cu. ft)
4,934.76 0.00 N/A N/A 0.00
4,935.00 2,576.02 1.00 205.27 205.27
4,936.00 3,600.56 1.00 3074.03 3279.3
4,937.00 8,714.26 1.00 5972.09 9251.39
4,938.00 15,540.49 1.00 11963.98 21215.37
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 08 / 17 / 2020
Hyd. No. 1
Basins 1, 1A, 2
Hydrograph type = Rational Peak discharge = 6.849 cfs
Storm frequency = 100 yrs Time to peak = 5 min
Time interval = 1 min Hyd. volume = 2,743 cuft
Drainage area = 0.990 ac Runoff coeff. = 0.62
Intensity = 11.158 in/hr Tc by User = 5.00 min
IDF Curve = TIM.hxp Asc/Rec limb fact = 1/1.67
1
0 1 2 3 4 5 6 7 8 9 10 11 12 13
Q (cfs)
0.00 0.00
1.00 1.00
2.00 2.00
3.00 3.00
4.00 4.00
5.00 5.00
6.00 6.00
7.00 7.00
Q (cfs)
Time (min)
Basins 1, 1A, 2
Hyd. No. 1 -- 100 Year
Hyd No. 1
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 08 / 17 / 2020
Hyd. No. 2
Pond 1 100-yr Routing
Hydrograph type = Reservoir Peak discharge = 0.105 cfs
Storm frequency = 100 yrs Time to peak = 13 min
Time interval = 1 min Hyd. volume = 12,181 cuft
Inflow hyd. No. = 1 - Basins 1, 1A, 2 Max. Elevation = 4935.78 ft
Reservoir name = Pond 1 - w/ WQCV Max. Storage = 2,602 cuft
Storage Indication method used.
2
0 300 600 900 1200 1500 1800 2100 2400 2700 3000
Q (cfs)
0.00 0.00
1.00 1.00
2.00 2.00
3.00 3.00
4.00 4.00
5.00 5.00
6.00 6.00
7.00 7.00
Q (cfs)
Time (min)
Pond 1 100-yr Routing
Hyd. No. 2 -- 100 Year
Hyd No. 2 Hyd No. 1 Total storage used = 2,602 cuft
Pond Report 3
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Monday, 08 / 17 / 2020
Pond No. 1 - Pond 1 - w/ WQCV
Pond Data
Pond storage is based on user-defined values.
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)
0.00 4934.76 n/a 0 0
0.24 4935.00 n/a 205 205
1.24 4936.00 n/a 3,074 3,279
2.24 4937.00 n/a 5,972 9,251
3.24 4938.00 n/a 11,964 21,215
Culvert / Orifice Structures Weir Structures
[A] [B] [C] [PrfRsr] [A] [B] [C] [D]
Rise (in) = 1.75 Inactive 0.00 0.00
Span (in) = 1.75 15.00 0.00 0.00
No. Barrels = 1 1 0 0
Invert El. (ft) = 4934.00 4934.00 0.00 0.00
Length (ft) = 0.00 30.00 0.00 0.00
Slope (%) = 0.00 1.00 0.00 n/a
N-Value = .013 .013 .013 n/a
Orifice Coeff. = 0.60 0.60 0.60 0.60
Multi-Stage = n/a No No No
Crest Len (ft) = 10.00 0.00 0.00 0.00
Crest El. (ft) = 4937.50 0.00 0.00 0.00
Weir Coeff. = 2.60 3.33 3.33 3.33
Weir Type = Broad --- --- ---
Multi-Stage = No No No No
Exfil.(in/hr) = 0.000 (by Contour)
TW Elev. (ft) = 0.00
Note: Culvert/Orifice outflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s).
Stage / Storage / Discharge Table
Stage Storage Elevation Clv A Clv B Clv C PrfRsr Wr A Wr B Wr C Wr D Exfil User Total
ft cuft ft cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs cfs
0.00 0 4934.76 0.07 ic 0.00 --- --- 0.00 --- --- --- --- --- 0.067
0.24 205 4935.00 0.08 ic 0.00 --- --- 0.00 --- --- --- --- --- 0.077
1.24 3,279 4936.00 0.11 ic 0.00 --- --- 0.00 --- --- --- --- --- 0.112
2.24 9,251 4937.00 0.14 ic 0.00 --- --- 0.00 --- --- --- --- --- 0.138
3.24 21,215 4938.00 0.16 ic 0.00 --- --- 9.19 --- --- --- --- --- 9.352
Weir Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Monday, Aug 17 2020
Detention Pond 1 - Emergency Overflow Weir - Q100= 6.8 cfs
Trapezoidal Weir
Crest = Sharp
Bottom Length (ft) = 10.00
Total Depth (ft) = 0.50
Side Slope (z:1) = 4.00
Calculations
Weir Coeff. Cw = 3.10
Compute by: Known Q
Known Q (cfs) = 6.80
Highlighted
Depth (ft) = 0.34
Q (cfs) = 6.800
Area (sqft) = 3.86
Velocity (ft/s) = 1.76
Top Width (ft) = 12.72
0 2 4 6 8 10 12 14 16 18
Depth (ft) Detention Pond 1 - Emergency Overflow Weir - Q100= 6.8 cfs Depth (ft)
-0.50 -0.50
0.00 0.00
0.50 0.50
1.00 1.00
Length (ft)
Weir W.S.
Stormwater Facility Name:
Facility Location & Jurisdiction:
User Input: Watershed Characteristics User Defined User Defined User Defined User Defined
Watershed Slope = 0.020 ft/ft Stage [ft] Area [ft^2] Stage [ft] Discharge [cfs]
Watershed Length = 203 ft 0.00 0 0.00 0.07
Watershed Area = 0.99 acres 0.24 205 0.24 0.08
Watershed Imperviousness = 42.0% percent 1.24 3,279 1.24 0.11
Percentage Hydrologic Soil Group A = percent 2.24 9,251 2.24 0.14
Percentage Hydrologic Soil Group B = 100.0% percent 3.24 21,215 3.24 9.35
Percentage Hydrologic Soil Groups C/D = percent
User Input 17
WQCV Treatment Method = 40.00 hours
After completing and printing this worksheet to a pdf, go to:
https://maperture.digitaldataservices.com/gvh/?viewer=cswdif
create a new stormwater facility, and
attach the pdf of this worksheet to that record.
Routed Hydrograph Results
Design Storm Return Period = WQCV 2 Year 5 Year 10 Year 50 Year 100 Year
One-Hour Rainfall Depth = 0.53 0.85 1.12 1.41 2.34 2.84 in
Calculated Runoff Volume = 0.015 0.025 0.036 0.054 0.127 0.170 acre-ft
OPTIONAL Override Runoff Volume = acre-ft
Inflow Hydrograph Volume = 0.015 0.024 0.035 0.054 0.126 0.169 acre-ft
Time to Drain 97% of Inflow Volume = 2.3 3.3 4.6 6.4 13.2 16.9 hours
Time to Drain 99% of Inflow Volume = 2.3 3.4 4.6 6.6 13.5 17.4 hours
Maximum Ponding Depth = 0.62 0.82 1.01 1.26 1.84 2.08 ft
Maximum Ponded Area = 0.03 0.05 0.06 0.08 0.16 0.19 acres
Maximum Volume Stored = 0.007 0.015 0.025 0.042 0.110 0.152 acre-ft
Location for 1-hr Rainfall Depths (use dropdown):
Workbook Protected Worksheet Protected
Stormwater Detention and Infiltration Design Data Sheet
Pond 1
N. Timberline Road and International Boulevard, Fort Collins, Colorado
SDI_Design_Data_v1.08.xlsm, Design Data 8/21/2020, 10:02 AM
WQCV_Trigger = 1
RunOnce= 1
CountA= 1
Draintime Coeff= 1.0
0 1 2 3
#N/A
#N/A
0 1 2 3
#N/A
#N/A
Check Data Set 1 Check Data Set 1
Area
Discharge
Stormwater Detention and Infiltration Design Data Sheet
0
0.5
1
1.5
2
2.5
3
3.5
4
0.1 1 10
FLOW [cfs]
TIME [hr]
100YR IN
100YR OUT
50YR IN
50YR OUT
10YR IN
10YR OUT
5YR IN
5YR OUT
2YR IN
2YR OUT
WQCV IN
WQCV OUT
0
0.5
1
1.5
2
2.5
0.1 1 10 100
PONDING DEPTH [ft]
DRAIN TIME [hr]
100YR
50YR
10YR
5YR
2YR
WQCV
SDI_Design_Data_v1.08.xlsm, Design Data 8/21/2020, 10:02 AM
Appendix C
Sheet 1 of 1
Designer:
Company:
Date:
Project:
Location:
1. To identify potential BMPs, what best describes
the type of site?
SKIP # 2
2. Does the typical section include a parking lane, shoulder,
median, or otherwise allow for surface BMPs?
3. Is the site comprised of Hydrologic Soil Group A or B soils?
4. Is the tributary impervious area1 greater than 1 acre?
SKIP #6-10
5. Is the depth of bedrock greater than 5 feet?
6. Is the tributary impervious area1 greater than 5 acres?
7. Is a water source available for use?
(baseflow or groundwater)
8. Is the BMP in a developing watershed?
9. Are BMPs allowed in the right-of-way?
10. Does the community have an established Fee in Lieu
Program in place?
11. Step 1 of Four Step Process: Grass Buffer
MDCIA / Volume Reduction (Not WQCV) BMPs Grass Swale
Permeable Pavement- Full Infiltration (5)
Green Roof (3)
12. Step 2 of Four Step Process: Permeable Pavement- Full Infiltration (5)
WQCV BMPs Bioretention- Full Infiltration (5)
Sand Filter Extended Detention Basin- Full Infiltration (5)
Green Roof (3)
Regional Water Quality Treatment (4)
Notes: 1. 'Tributary impervious area' refers to the impervious area draining to the BMP, not the total area of the project site.
2. For a successful wetland channel or basin, a water source (groundwater or baseflow) will be required.
3. In the Front Range of Colorado, irrgation, at least periodically in dry times, will be required to sustain a green roof.
4. If a regional facility will be used to provide the WQCV, some degree of onsite treatment/MDCIA will still likely be required.
5. No Infiltration= underdrain and liner, Partial Infiltration= underdrain and no liner, Full Infiltration= no underdrain and no liner.
6. Consider this BMP for a portion of your site. It's best suited for impervious tributary areas of approximately one acre or less.
Design Procedure Form: BMP Selection Tool
Mary B. Wohnrade, P.E.
Wohnrade Civil Engineers, Inc.
September 10, 2020
Timberline-International
Timberline Road, Fort Collins, CO
UD-BMP (Version 3.07, March 2018)
Choose One
Highly Urbanized Site
Conventional Site
Choose One
YES
NO
Choose One
YES
NO
Choose One
YES
NO
Choose One
YES
NO
Choose One
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 46.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.460
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.16 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 22,651 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.35 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 240 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 9 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 208 sq ft
D) Actual Flat Surface Area AActual = 2576 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 3601 sq ft
F) Rain Garden Total Volume VT= 2,347 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided? 2
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = N/A ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = N/A cu ft
iii) Orifice Diameter, 3/8" Minimum DO = N/A in
Design Procedure Form: Rain Garden (RG)
Mary B. Wohnrade, P.E.
Wohnrade Civil Engineers, Inc.
August 26, 2020
Timberline-International - Rain Garden No. 1
Fort Collins, Colorado
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.07-Rain_Garden_No_1.xlsm, RG 8/26/2020, 10:29 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Mary B. Wohnrade, P.E.
Wohnrade Civil Engineers, Inc.
August 26, 2020
Timberline-International - Rain Garden No. 1
Fort Collins, Colorado
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_v3.07-Rain_Garden_No_1.xlsm, RG 8/26/2020, 10:29 AM
Sheet 1 of 2
Designer:
Company:
Date:
Project:
Location:
1. Basin Storage Volume
A) Effective Imperviousness of Tributary Area, Ia Ia = 37.0 %
(100% if all paved and roofed areas upstream of rain garden)
B) Tributary Area's Imperviousness Ratio (i = Ia/100) i = 0.370
C) Water Quality Capture Volume (WQCV) for a 12-hour Drain Time WQCV = 0.14 watershed inches
(WQCV= 0.8 * (0.91* i3 - 1.19 * i2 + 0.78 * i)
D) Contributing Watershed Area (including rain garden area) Area = 20,473 sq ft
E) Water Quality Capture Volume (WQCV) Design Volume VWQCV = cu ft
Vol = (WQCV / 12) * Area
F) For Watersheds Outside of the Denver Region, Depth of d6 = 0.35 in
Average Runoff Producing Storm
G) For Watersheds Outside of the Denver Region, VWQCV OTHER = 191 cu ft
Water Quality Capture Volume (WQCV) Design Volume
H) User Input of Water Quality Capture Volume (WQCV) Design Volume VWQCV USER = cu ft
(Only if a different WQCV Design Volume is desired)
2. Basin Geometry
A) WQCV Depth (12-inch maximum) DWQCV = 9 in
B) Rain Garden Side Slopes (Z = 4 min., horiz. dist per unit vertical) Z = 4.00 ft / ft
(Use "0" if rain garden has vertical walls)
C) Mimimum Flat Surface Area AMin = 152 sq ft
D) Actual Flat Surface Area AActual = 2785 sq ft
E) Area at Design Depth (Top Surface Area) ATop = 3616 sq ft
F) Rain Garden Total Volume VT= 2,432 cu ft
(VT= ((ATop + AActual) / 2) * Depth)
3. Growing Media
4. Underdrain System
A) Are underdrains provided? 1
B) Underdrain system orifice diameter for 12 hour drain time
i) Distance From Lowest Elevation of the Storage y = 1.5 ft
Volume to the Center of the Orifice
ii) Volume to Drain in 12 Hours Vol12 = 191 cu ft
iii) Orifice Diameter, 3/8" Minimum DO = 5/16 in LESS THAN MINIMUM. USE DIAMETER OF 3/8"
Design Procedure Form: Rain Garden (RG)
Mary B. Wohnrade, P.E.
Wohnrade Civil Engineers, Inc.
August 26, 2020
Timberline-International - Rain Garden No. 2
Fort Collins, Colorado
UD-BMP (Version 3.07, March 2018)
Choose One
Choose One
18" Rain Garden Growing Media
Other (Explain):
YES
NO
UD-BMP_v3.07-Rain_Garden_No_2.xlsm, RG 8/26/2020, 10:50 AM
Sheet 2 of 2
Designer:
Company:
Date:
Project:
Location:
5. Impermeable Geomembrane Liner and Geotextile Separator Fabric
A) Is an impermeable liner provided due to proximity
of structures or groundwater contamination?
6. Inlet / Outlet Control
A) Inlet Control
7. Vegetation
8. Irrigation
A) Will the rain garden be irrigated?
Notes:
Design Procedure Form: Rain Garden (RG)
Mary B. Wohnrade, P.E.
Wohnrade Civil Engineers, Inc.
August 26, 2020
Timberline-International - Rain Garden No. 2
Fort Collins, Colorado
Choose One
Choose One
Choose One
Sheet Flow- No Energy Dissipation Required
Concentrated Flow- Energy Dissipation Provided
Plantings
Seed (Plan for frequent weed control)
Sand Grown or Other High Infiltration Sod
Choose One
YES
NO
YES
NO
UD-BMP_v3.07-Rain_Garden_No_2.xlsm, RG 8/26/2020, 10:50 AM
Appendix D
Culvert Report
Hydraflow Express Extension for Autodesk® AutoCAD® Civil 3D® by Autodesk, Inc. Tuesday, Aug 7 2018
Future Storm Sewer Line
Invert Elev Dn (ft) = 4923.48
Pipe Length (ft) = 392.47
Slope (%) = 0.40
Invert Elev Up (ft) = 4925.05
Rise (in) = 30.0
Shape = Circular
Span (in) = 30.0
No. Barrels = 1
n-Value = 0.013
Culvert Type = Circular Concrete
Culvert Entrance = Square edge w/headwall (C)
Coeff. K,M,c,Y,k = 0.0098, 2, 0.0398, 0.67, 0.5
Embankment
Top Elevation (ft) = 4941.89
Top Width (ft) = 24.00
Crest Width (ft) = 100.00
Calculations
Qmin (cfs) = 0.00
Qmax (cfs) = 23.00
Tailwater Elev (ft) = Normal
Highlighted
Qtotal (cfs) = 23.00
Qpipe (cfs) = 23.00
Qovertop (cfs) = 0.00
Veloc Dn (ft/s) = 5.97
Veloc Up (ft/s) = 6.78
HGL Dn (ft) = 4925.31
HGL Up (ft) = 4926.68
Hw Elev (ft) = 4927.61
Hw/D (ft) = 1.02
Flow Regime = Inlet Control
Project:
Date:
Sheets
11582 Colony Row
Broomfield, Colorado 80021
Phone: (720)259-0965
Fax: (720)259-1519
No. Revisions: By: Date:
WOHNRADE CIVIL ENGINEERS, INC.
24
8/14/2020
TIM: 1805.00
Scale:
Designed By:
Reviewed By:
15 Sheet
MBW
JDM
1"=20'
CALL UTILITY NOTIFICATION CENTER OF
COLORADO
Know what'sbelow.
Call before you dig.
R
YES
NO
Choose One
YES
NO
Choose One
YES
NO
Choose One
YES
NO
Linear Construction in Urbanized Area
Choose One
YES
NO
TIM_UD-BMP_v3.07_SELECTION_TOOL.xlsm, BMP Selection Tool 9/10/2020, 6:03 PM
5YR IN
5YR OUT
2YR IN
2YR OUT
EURV IN
EURV OUT
WQCV IN
WQCV OUT
0
0.5
1
1.5
2
2.5
3
3.5
0.1 1 10 100
PONDING DEPTH [ft]
DRAIN TIME [hr]
500YR
100YR
50YR
25YR
10YR
5YR
2YR
EURV
WQCV
0.00
0.01
0.01
0.02
0.02
0.03
0.03
0
5,000
10,000
15,000
20,000
25,000
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4.00 4.50
OUTFLOW [cfs]
AREA [ft^2], VOLUME [ft^3]
PONDING DEPTH [ft]
User Area [ft^2]
Interpolated Area [ft^2]
Summary Area [ft^2]
Volume [ft^3]
Summary Volume [ft^3]
Outflow [cfs]
Summary Outflow [cfs]
Predevelopment Peak Q (cfs) = 0.0 0.0 0.0 0.0 0.2 0.7 1.1 1.6 2.9
Peak Inflow Q (cfs) = 0.3 0.8 0.5 0.7 1.1 1.9 2.5 3.4 5.7
Peak Outflow Q (cfs) = 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0
Ratio Peak Outflow to Predevelopment Q = N/A N/A N/A 0.7 0.1 0.0 0.0 0.0 0.0
Structure Controlling Flow = Plate Plate Plate Plate Plate Plate Plate Plate Plate
Max Velocity through Grate 1 (fps) = N/A N/A N/A N/A N/A N/A N/A N/A N/A
Max Velocity through Grate 2 (fps) = N/A N/A N/A N/A N/A N/A N/A N/A N/A
Time to Drain 97% of Inflow Volume (hours) = 38 63 48 58 72 99 >120 >120 >120
Time to Drain 99% of Inflow Volume (hours) = 40 69 52 63 79 >120 >120 >120 >120
Maximum Ponding Depth (ft) = 0.68 1.19 0.90 1.09 1.37 1.93 2.28 2.61 3.24
Area at Maximum Ponding Depth (acres) = 0.04 0.06 0.05 0.06 0.07 0.08 0.11 0.15 0.24
Maximum Volume Stored (acre-ft) = 0.014 0.041 0.023 0.034 0.053 0.095 0.127 0.173 0.294
Detention Basin Outlet Structure Design
UD-Detention, Version 3.07 (February 2017)
142 Timberline
Detention Pond 1 - Interim Condition - Includes Basins 1, 2, and O1
Example Zone Configuration (Retention Pond)
-- -- -- --
Length of Basin Floor (LFLOOR) = user ft
-- -- -- --
Width of Basin Floor (WFLOOR) = user ft
-- -- -- --
Area of Basin Floor (AFLOOR) = user ft^2 -- -- -- --
Volume of Basin Floor (VFLOOR) = user ft^3 -- -- -- --
Depth of Main Basin (HMAIN) = user ft -- -- -- --
Length of Main Basin (LMAIN) = user ft -- -- -- --
Width of Main Basin (WMAIN) = user ft -- -- -- --
Area of Main Basin (AMAIN) = user ft^2 -- -- -- --
Volume of Main Basin (VMAIN) = user ft^3 -- -- -- --
Calculated Total Basin Volume (Vtotal) = user acre-feet -- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
-- -- -- --
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
Optional
Override
Area (ft^2)
Length
(ft)
Optional
Override
Stage (ft)
Stage
(ft)
Stage - Storage
Description
Area
(ft^2)
Width
(ft)
142 Timberline
Detention Pond 1 - Includes Basins 1, 1a, and 2
UD-Detention, Version 3.07 (February 2017)
Volume
(ft^3)
Volume
(ac-ft)
Area
(acre)
Optional User Override
1-hr Precipitation
Example Zone Configuration (Retention Pond)
UD-Detention_v3.07.xlsm, Basin 8/21/2020, 10:06 AM
0.549
(0.439‑0.677)
0.724
(0.576‑0.895)
0.906
(0.716‑1.12)
1.21
(0.945‑1.62)
1.48
(1.12‑1.99)
1.80
(1.30‑2.47)
2.15
(1.48‑3.02)
2.68
(1.76‑3.85)
3.12
(1.97‑4.48)
30-min 0.603
(0.482‑0.742)
0.711
(0.568‑0.876)
0.938
(0.747‑1.16)
1.17
(0.929‑1.46)
1.57
(1.23‑2.10)
1.93
(1.45‑2.59)
2.34
(1.69‑3.21)
2.80
(1.93‑3.95)
3.49
(2.30‑5.03)
4.07
(2.58‑5.86)
60-min 0.737
(0.590‑0.908)
0.868
(0.694‑1.07)
1.15
(0.917‑1.42)
1.45
(1.15‑1.80)
1.96
(1.54‑2.64)
2.43
(1.84‑3.28)
2.97
(2.15‑4.09)
3.58
(2.47‑5.05)
4.50
(2.96‑6.49)
5.27
(3.33‑7.57)
2-hr 0.872
(0.701‑1.06)
1.03
(0.824‑1.25)
1.37
(1.09‑1.67)
1.73
(1.38‑2.13)
2.36
(1.87‑3.15)
2.94
(2.23‑3.93)
3.60
(2.63‑4.92)
4.36
(3.04‑6.11)
5.50
(3.66‑7.88)
6.46
(4.13‑9.22)
3-hr 0.961
(0.776‑1.17)
1.13
(0.908‑1.37)
1.50
(1.20‑1.82)
1.90
(1.52‑2.33)
2.60
(2.07‑3.47)
3.25
(2.49‑4.34)
4.00
(2.94‑5.45)
4.86
(3.40‑6.78)
6.15
(4.12‑8.78)
7.24
(4.66‑10.3)
6-hr 1.14
(0.924‑1.37)
1.34
(1.08‑1.60)
1.77
(1.43‑2.13)
2.23
(1.79‑2.70)
3.01
(2.40‑3.96)
3.73
(2.87‑4.92)
4.56
(3.37‑6.15)
5.50
(3.89‑7.61)
6.92
(4.68‑9.79)
8.11
(5.27‑11.4)
12-hr 1.37
(1.12‑1.63)
1.60
(1.31‑1.91)
2.09
(1.69‑2.49)
2.58
(2.08‑3.09)
3.38
(2.70‑4.36)
4.11
(3.17‑5.33)
4.93
(3.66‑6.55)
5.85
(4.16‑7.99)
7.22
(4.92‑10.1)
8.36
(5.49‑11.7)
24-hr 1.66
(1.36‑1.95)
1.91
(1.57‑2.25)
2.43
(1.99‑2.87)
2.94
(2.39‑3.49)
3.78
(3.03‑4.80)
4.52
(3.51‑5.79)
5.35
(4.01‑7.03)
6.29
(4.51‑8.49)
7.66
(5.27‑10.6)
8.80
(5.84‑12.2)
2-day 1.88
(1.55‑2.18)
2.23
(1.84‑2.60)
2.88
(2.37‑3.36)
3.47
(2.84‑4.08)
4.38
(3.50‑5.44)
5.15
(4.00‑6.47)
5.98
(4.49‑7.71)
6.88
(4.95‑9.15)
8.16
(5.65‑11.2)
9.21
(6.18‑12.7)
3-day 2.03
(1.68‑2.35)
2.41
(1.99‑2.79)
3.08
(2.54‑3.58)
3.70
(3.03‑4.32)
4.63
(3.71‑5.71)
5.42
(4.23‑6.76)
6.26
(4.72‑8.03)
7.17
(5.19‑9.48)
8.47
(5.90‑11.5)
9.53
(6.43‑13.1)
4-day 2.16
(1.79‑2.49)
2.55
(2.11‑2.94)
3.24
(2.68‑3.75)
3.87
(3.19‑4.50)
4.83
(3.88‑5.92)
5.63
(4.41‑6.99)
6.49
(4.91‑8.29)
7.42
(5.39‑9.77)
8.74
(6.11‑11.9)
9.81
(6.65‑13.5)
7-day 2.46
(2.05‑2.81)
2.91
(2.43‑3.33)
3.70
(3.08‑4.25)
4.40
(3.64‑5.08)
5.43
(4.38‑6.58)
6.28
(4.94‑7.71)
7.17
(5.46‑9.06)
8.13
(5.94‑10.6)
9.46
(6.66‑12.7)
10.5
(7.20‑14.3)
10-day 2.73
(2.29‑3.10)
3.23
(2.70‑3.68)
4.09
(3.41‑4.66)
4.84
(4.01‑5.54)
5.91
(4.77‑7.09)
6.78
(5.35‑8.27)
7.69
(5.87‑9.65)
8.65
(6.34‑11.2)
9.97
(7.05‑13.3)
11.0
(7.58‑15.0)
20-day 3.53
(2.97‑3.97)
4.10
(3.45‑4.61)
5.05
(4.23‑5.69)
5.85
(4.88‑6.63)
6.98
(5.65‑8.24)
7.87
(6.24‑9.46)
8.78
(6.74‑10.9)
9.72
(7.19‑12.4)
11.0
(7.84‑14.6)
12.0
(8.34‑16.2)
30-day 4.16
(3.52‑4.64)
4.79
(4.04‑5.35)
5.82
(4.89‑6.52)
6.68
(5.59‑7.53)
7.86
(6.38‑9.20)
8.78
(6.98‑10.5)
9.70
(7.48‑11.9)
10.6
(7.90‑13.5)
11.9
(8.53‑15.6)
12.8
(8.99‑17.2)
45-day 4.90
(4.16‑5.44)
5.64
(4.78‑6.26)
6.83
(5.76‑7.61)
7.79
(6.55‑8.73)
9.09
(7.39‑10.5)
10.1
(8.04‑11.9)
11.0
(8.54‑13.5)
12.0
(8.95‑15.1)
13.2
(9.54‑17.3)
14.2
(9.98‑18.9)
60-day 5.49
(4.67‑6.06)
6.35
(5.39‑7.02)
7.72
(6.53‑8.56)
8.81
(7.42‑9.83)
10.3
(8.34‑11.8)
11.3
(9.04‑13.3)
12.3
(9.56‑14.9)
13.3
(9.96‑16.7)
14.6
(10.5‑18.9)
15.5
(11.0‑20.6)
1 Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency
estimates (for a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at
upper bounds are not checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
Back to Top
TIM-DevQ.xlsx Page 3 of 3 Wohnrade Civil Engineers, Inc.
TIM-DevQ.xlsx Page 2 of 3 Wohnrade Civil Engineers, Inc.
TIM-DevQ.xlsx Page 1 of 3 Wohnrade Civil Engineers, Inc.
Timberline
Road
and
International
Boulevard.
We
are
pursuing
a
small
mixed-‐use
commercial
development
on
our
property.
In
our
initial
conversations
with
the
City
of
Fort
Collins,
we
were
asked
to
construct
and
pay
for
a
comprehensive
master-‐planned
storm
drainage
system
along
Timberline
Road
which
would
run
not
only
along
our
eastern
frontage,
but
further
south
several
hundred
yards,
well
beyond
our
property
boundary.
This
request
is
obviously
cost
prohibitive.
As
an
alternative,
City
staff
proposed
a
storm
water
outfall
agreement
with
Lake
Canal.
Staff
mentioned
that
other
projects
in
the
area
have
made
similar
arrangements
with
Lake
Canal.
Enclosed
is
a
preliminary
design
for
our
project
including
an
outfall
structure
into
the
canal
as
well
as
a
flow
calculation
from
our
site
based
on
a
100-‐year
event.
We
are
requesting
approval
from
Lake
Canal
for
this
discharge,
and
understand
there
will
be
an
annual
fee
associated
with
the
same.
Please
contact
me
directly
with
any
questions.
Thank
you,
Devin
Ferrey
President,
FR
Holdings,
Ltd.
devin@fr-‐corp.com
970-‐691-‐1234