HomeMy WebLinkAboutDrainage Reports - 06/28/2018 (2)I
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City of Fort Co~~Approved a
Approved by: /-rvJ+vL
Date: Iv /.2.t; lfg ~ , FINAL
DRAINAGE, WATER QUALITY AND
EROSION CONTROL REPORT
FOR THE
POUDRE RIVER WHITEWATER PARK PROJECT
PREPARED FOR:
City of Fort Collins
Park Planning & Development
215 North Mason Street
Fort Collins, CO 80524
PREPARED BY:
Anderson Consulting Engineers, Inc.
375 East Horsetooth Road, Building 5
Fort Collins, CO 80525
(ACE Project No. COFC18.1)
February 5, 2018
ANdERSON CoNsuhiNG ENqiNEERS, INC.
Civil • Water Resources • Environmental
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, FINAL
DRAINAGE1 WATER QUALITY AND
EROSION CONTROL REPORT
FOR THE
POUDRE RIVER WHITEWATER PARK PROJECT
PREPARED FOR :
City of Fort Collins
Park Planning & Development
215 North Mason Street
Fort Collins, CO 80524
PREPARED BY:
Anderson Consulting Engineers, Inc.
375 East Horsetooth Road, Building 5
Fort Collins, CO 80525
(ACE Project No. COFC18.1}
February 5, 2018
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I.
II.
Ill.
IV.
V.
TABLE OF CONTENTS
INTRODUCTION ............................................................................................................................... 1
PROJECT LOCATION AND INFORMATION ........................................................................................ 2
2.1 Project Location .................................................................................................................. 2
2.2 Topographic Mapping ......................................................................................................... 2
2 .3 Proposed Project Improvements ........................................................................................ 2
EXISTING DRAINAGE BASIN AND STORMWATER FACILITIES ........................................................... 4
3.1 Existing Basin Characteristics .............................................................................................. 4
3.2 Existing Stormwater Facilities ............................................................................................. 6
DRAINAGE DESIGN CRITERIA ........................................................................................................... 7
4.1
4 .2
4.3
4.4
4.5
Hydrologic Criteria .............................................................................................................. 7
Hydraulic Criteria ................................................................................................................ 7
Directly Connected Impervious Area (DCIA)/Stormwater Quality Management ............... 8
Low Impact Development (LID) Criteria ............................................................................. 9
Floodplain Regulations Compliance .................................................................................. 10
DRAINAGE FACILITY DESIGN .......................................................................................................... 11
5.1 Proposed Project Conditions ............................................................................................ 11
5.2 Fully Developed Project Conditions .................................................................................. 14
VI . SEDIMENT/EROSION CONTROL ..................................................................................................... 16
VII.
VIII.
CONCLUSIONS ................................................................................................................................ 17
REFERENCES ................................................................................................................................... 18
Figure 2.1
Figure 3.1
Appendix A:
Appendix B:
Appendix C:
LIST OF FIGURES
Site Map for the Poudre River Whitewater Project ............................................................ 3
Effective FIRM Panel with Project Area .............................................................................. 5
LIST OF APPENDICES
Hydrologic and Hydraulic Documentation
Proposed Project Conditions Information and SWMM Results
Fully Developed with Project Conditi ons Information and SWMM Results
COFC18 .1 Drain age Report (February S 2018).docx ANdrnsoN CoNsuhiNG ENqiNEERs, INc.
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I. INTRODUCTION
In October 2014, the City of Fort Collins completed the Poudre River Downtown Masterplan,
which covered approximately three miles of the Cache la Poudre River corridor from Shields Street to
Mulberry Street. The mission statement for this masterplan was "to plan and design integrated, and to
the extent possible, mutually supportive improvements related to habitat, recreation, and flood
mitigation." The Poudre River Whitewater Park Project encompasses the vision that was set forth in Reach
3 (Museum of Discovery to BNSF Railroad) of the Downtown Masterplan. Improvements associated with
the project include: flood mitigation, wildlife habitat and ecological restoration including fish passage,
pedestrian access to and over the Cache la Poudre River, and outdoor recreational activities that include
whitewater river features for kayaking . The following report documents the procedures, assumptions,
and data utilized in preparing the drainage, erosion control, and water quality design for the Poudre River
Whitewater Park Project.
COFC18.l Drainage Report (February 5 2018).docx 1 ANdrnsoN CoNsuhiNG ENqiNEERS, INC.
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II. PROJECT LOCATION AND INFORMATION
2.1 Project Location
A site map for the project area has been provided as Figure 2.1. The project area is located in
Sections 11 and 12, ofTownship 7N, Range 69W of Larimer County, Colorado and is located entirely within
the limits of the City of Fort Collins . As illustrated on Figure 2.1, the project area is generally bounded by
Vine Drive on the north, the Union Pacific Railroad on the west, the Cache la Poudre River on the south,
and the Burlington Northern and Santa Fe {BNSF) Railroad on the east. The project area encompasses
approximately 13.3 acres of land that is currently, or w i ll soon be owned, by the City of Fort Collins. Xcel
Energy owns a natural gas regulation station just north of the river and west of the BNSF Railroad that is
excluded from the project area .
2.2 Topographic Mapping
All data utilized for this project is vertically referenced to the North American Vertical Datum of
1988 {NAV88). Detai led ground survey of the project area was collected by King Surveyors in 2015 and
2016. Outside of the project area, the ground survey information was supplemented with 1-foot
topographic mapping developed from LiDAR data that was collected by Ayres Associates in May 2013 for
the City of Fort Collins and Larimer County. The nearest City of Fort Collins benchmark to the project area
is Benchmark 1-00, which is located on a catch basin at the southeast corner of Vi ne Drive and College
Avenue .
2.3 Proposed Project Improvements
The proposed project consists of the following improvements:
• Cache la Poudre River Channel Improvements -Whitewater and grade control features will
be added upon removal of the Coy Ditch d iversion dam and boat chute to provide flood
mitigation, fish passage, and increase recreational opportunities.
• Pedestrian Access -trails and a new pedestrian bridge will be added to connect the project
to surrounding areas and provide access to the river.
• Vine Drive -street improvements, i ncluding vertical curb, gutter, parallel parking, and storm
drainage facilities will be added on the south side of Vine Drive.
• Park i ng Lots - A 35 space parking lot w i ll be constructed during Phase 1. An additional 27
park i ng spaces will be added as part of a second phase based on parking needs and funding .
• Stormwater Outfall and Water Quality Treatment -A storm sewer system and outfall to the
river will be added to provide water quality treatment and conveyance of rainfall -generated
runoff to the river.
CO FC18.l Drainage Report (February S 2018).docx 2 ANdrnsoN CoNsuhiNq ENqiNEERs, IN C.
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Figure 2.1 Site Map for the Poudre River Whitewater Project.
COFC18 .l Dra inage Report (February 5 2018).docx 3
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Ill. EXISTING DRAINAGE BASIN AND STORMWATER FACILITIES
The project site li es with i n the Cache la Poudre River Bas i n . The Cache la Poudre River has its
origi ns in the Rocky Mounta i ns, i n both Roosevelt National Forest and Rocky Mounta i n Nat iona l Park ,
located west of the City of Fort Coll i ns, Colorado . The rive r conveys flows from the mouth of the Poudre
Canyon , southeast t o its confluence w ith the South Platte River east of Greeley, Colorado. The Cache la
Poudre River is regu lated by the Federal Emergency Management Agency (FEMA) as part of the National
Flood Insurance Program (NFIP). The Effective Flood Insurance Rate Map (FIRM) for the project is
#08069C0977G , dated June 17, 2008 . As il lustrated on Figu r e 3.1 , the majority of the project area is
situated w ith i n the effective 1-percent annua l chance (100-year) floodplain (Zone AE) and the
southwestern portion of the project site located within the floodway.
3 .1 Existing Basin Characteristics
The proposed proj ect area includes the western portion of the Gustav Swanson Natural Area and
approximately 970 li near feet of the Poudre River . The site consists of res idential/commercial property
along Vine Dr ive , with open space between these properties and the river. The abandoned Coy Ditch runs
through the m iddle of the property and previously fi lled t he two man -made ponds, which are referred to
as the Eastern and Western Coy Ponds throughout this report. An existing stormwater retent ion pond is
the located i n northeastern corner of the proj ect site and reta i ns stormwater runoff from the
l nverness/l nnosphere deve lopment properties located on the north side of Vine Drive .
In general, the site is relat ively level with an approx i mate 1.0%-0.50% slope towards the Cache la
Poudre River. Ex isting vegetat ion of the site consists of upland herbaceous, sub-canopy, r i par ian forest,
and deve loped land . Addit iona ll y, there are four wetland areas located along the Coy Ditch/Ponds . The
vegetat ion of the site and wetland ar eas were classified as part of the eco logical characterization study
(ECS) that was conducted by Biohabitats and subm itted to the City as part of the development review
process for th is proj ect . Due to the extens ive rive r work and small impact to ex ist i ng wetland areas, the
procu r eme nt of a 404-pe r m it from the U.S. Army Corps of Eng i neers (ACOE) w i ll be requ i red prior to
construct ion . It is noted that an i n it ial 404-permit appl icat ion was submitted to the ACOE on November
2, 2016, w ith a revised submittal applicat ion provided on Apr il 4, 2017 . Reference is made to the 404-
perm it applicat ion and supplemental i nformat ion p repared by Eco logy and Env i ronment, Inc .
Ex ist i ng so il s genera l consist of a th i n laye r of top so il that overlays silty/clayey sands and gravels .
Depth to groundwater var ies throughout the site, w ith general depths of 5-10 feet . Due to the prox imity
to the r iver and coarse so il material, groundwater depths fluctuate seasonally. Depth to bedrock also
varies throughout the site, but is generally located at depths of 15-20 feet. Reference is made to the soils
report for the project deve loped by Earth Engineering Consultants (EEC) Inc called "Subsurface Exploration
Report, proposed City of Fort Collins' -Poud re River Whitewater Park and Vine Drive Roadway
Improvements" December 8, 2016 .
COFC 18 .l Dra i nag e Report (Fe bruary 5 201 8).docx 4 ANdmsoN CoNsuhiNG ENqiNE ERS, IN C.
-n 0 ,, n ...... !"' ...... 0 al 3· QI (IQ ro ;;o ro 'O 0 ;:i ,, ro g-c QI < V, "' 0 ...... ~ 0.. 0 n X l/1 :i> :z c... .., ~ :z Q :z V, C: 5:-:z .r-, m :z -Q. :z .., .., .0 :z 0 - --•J00111 E ---Project Area - -- - --ZONEX H=t~-OCt<. ____ SJREET Divers,on Dam CCNlFER Poutfre Rirer STRECT ZONE X X 1,.\RIMF.R COl'\TV U:',Jl•TORPORA TETI ARLAS 1110101 -•94000m E OWNSHIP 7 NORTH, RANGE 69 WEST ANO TOWNSHIP 8 NORTH, RANGE 69 WEST. --~ ~ % Figure 3.1 Effective FIRM Panel with Project Area. -- - --,----160 260 [[ • MAP SCALE 1" = 500' 0 500 l I 0 160 PANEL 0977G FIRM 1~EET METER 300 FLOOD INSURANCE RATE MAP LARIMER COUNTY, COLORADO AND INCORPORATED AREAS PANEL 977 OF 1420 (SEE MAP INDEX FOR FIRM PANEL LAYOUT) i:;.QNTAIJ:,!S_ CP.MMUNIJX IAAOAFR C'.OIJf\TV Fnfr CCV. lt1S, GITY oi=-l'j\J.MllJ;,8 P.11N._U §.!,JffJX OOC:•10 1 :977 oaow2 09n " G Notice to UsN· The Map Numl>ef' shown below shOUd be used~ ph1cing m"P order.s, tm, Corrmun;ty Number ~O\'m above Gohoud be Ufi8d on msur.anc:a .1~c-..at1one. for lhFI ~1bt9d romrmnlty MAP NUMBER 08069C0977G MAP REVISED JUNE 17, 2008 Frdel'III F.mcrgenry \'111n11grmf11I Agfnfy -
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3.2 Existing Stormwater Facilities
Existing site drainage generally consists of overland flow from north to south. Off-site drainage
enters the project site from properties north of Vine Drive. The majority of rainfall-generated runoff in
this basin is conveyed as overland flow and is captured by the Coy Ditch, or the adjacent man-made ponds
(Eastern and Western Coy Ponds). A small storm sewer system, consisting of four single valley grate inlets
and a 12-inch pipe, collects runoff from the western portion of Vine Drive and conveys it to the Western
Coy Pond. When the capacity of this system is exceeded, flow overtops Vi ne Drive west of Jerome Street
and is conveyed overland into the Western Coy Pond. It is presumed that most of the rainfall-generated
runoff that reaches the Coy Ditch or Coy Ponds infiltrates into the groundwater table . Flow that does not
infiltrate is conveyed off site via the Coy Ditch through a culvert underneath the BNSF railroad .
As part of the Inverness Innovation Park (lnnosphere) development, a storm sewer system was
installed on Vine Drive, east of Jerome Street, to collect and convey runoff generated from a 100-year
rainfall event into a retention pond located on the south side of Vine Drive. The pond was sized to retain
and infiltrate the entire 100-year runoff volume from both the currently developed lnnosphere site and
future development located to the east of the lnnosphere site. It is noted that the future development
property located to the east of the existing lnnosphere building currently drains to an existing 18-inch
storm drain pipe underneath Vine Drive that discharges to an open channel swale. This swale drains to
the Coy Ditch through an existing culvert underneath the BNSF railroad. However, the three 24-inch storm
drainage pipes that cross Vine Drive and drain into the retention pond, which were installed as part ofthe
Inverness development, are intended to convey runoff from the future development of the property
located to the east of the lnnosphere building.
COFC18 .l Drainage Report (February 5 2018).docx 6 ANdrnsoN CoNsuhiNG ENqiNEERS, IN C.
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IV. DRAINAGE DESIGN CRITERIA
The City of Fort Collins Stormwater Criteria Manual and Construction Standards were utilized to
develop the design for this project. Due to the abandonment of the Coy Ditch as a conveyance system for
irrigation water, it was learned early in the design phase of this project that the City Stormwater
Department was investigating the potential of plugging the Coy Ditch culvert at the BNSF railroad to
reduce potential flooding of downstream properties caused by the ditch capturing excess
stormwater/Poudre River flood flows west of the BNSF. It was realized that the design of the Poudre River
Whitewater Park project could help alleviate potential local drainage issues that would be created by the
plugging of the Coy Ditch culvert. Therefore, in partnership with the City Stormwater Department, it was
decided that the EPA SWMM 5.0 model would be utilized to develop a small Stormwater Masterplan for
the localized drainage basin.
4.1 Hydrologic Criteria
For this study, the project area was delineated into 15 drainage basins for determining flow rates
at specific design locations . The rainfall intensity-duration-frequency curves provided in Table RA-9 from
the City Stormwater Criteria Manual were utilized in the EPA-SWMM 5.0 model to generate basin runoff.
Percent imperviousness was calculated based on aerial i magery and proposed site improvements . Basin
slopes were calculated based on topographic information. Hydrologic input parameters for the project
are summarized and provided in Appendix A.
4.2 Hydraulic Criteria
The proposed hydraulic design for this study follows the Stormwater Criteria Manual and
Construction Standards for all improvements. The EPA SWMM 5.0 model was utilized to generate and
route basin runoff through the project site. Proposed conveyance element sizes and slopes were
developed based on an iterative process to meet criteria. Detention element areas/volumes were
obtained from topographic mapping. Per criteria, Urban Drainage's UDlnlet was utilized to determine the
capacity of existing inlets and to size proposed inlets. UDBMP was also util ized to determine the water
quality capture volume for the proposed retrofit of the Inverness retention pond to a traditional extended
detention water quality pond . Hydraulic documentation and spreadsheet calculations are provided in
Appendix A.
COFC18 .l Dra inage Report (February 5 2018).docx 7
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4.3 Directly Connected Impervious Area (DCIA)/Stormwater Quality Management
The Urban Drainage and Flood Control District (UDFCD) recommends a Four-Step Process for
reducing the impacts of urban runoff and effectively designing stormwater quality BMPs. This section
describes the UDFCD Four-Step Process and how it was applied to the current project.
Step 1: Employ Runoff Reduction Practices
To reduce runoff peaks, volumes, and pollutant loads from urbanized areas, implement Low
Impact Development (LID) strategies, including measures to "minimize directly connected impervious
areas" (MDC/A). These practices reduce unnecessary impervious areas and route runoff from impervious
surfaces over permeable areas to slow runoff (increase time of concentration) and promote onsite storage
and infiltration (Urban Storm Drainage Criteria Manual, Volume 3 -Best Management Practices, UDFCD,
2010}.
Increased impervious area within the project site has been minimized to the extent possible, being
limited to the proposed parking lot near the northeast corner of the site, widening of the south side of
Vine Drive, the sidewalk along Vine Drive, and several concrete trails. All runoff emanating from the
parking lot, Vine Drive and the sidewalk along Vine Drive, as well as many of the trails, will be pre-treated
with Snout Hood BMPs in stormwater inlets and/or conveyed through grass-lined swales and non-
regulatory wetland areas prior to being released to the Poudre River. Utilizing new drainage swales,
enhanced wetland areas of the Coy Ponds, and an enhanced wetland corridor along the abandoned Coy
Ditch will reduce runoff volumes, peak flow rates, and pollutant loads entering the Poudre River.
Step 2: Implement BMPs that Provide a Water Quality Capture Volume (WQCV) with Slow Release
After runoff has been reduced, the remaining runoff must be treated through capture and slow
release of the WQCV. WQCV facilities may provide both water quality and runoff reduction benefits,
depending on the BMP selected (Urban Storm Drainage Criteria Manual, Volume 3 -Best Management
Practices, UDFCD, 2010).
The existing retention pond near the northeast corner of the project site is being reconfigured to
provide a WQCV with a metered release which has been designed to accommodate street runoff and the
parking lot expansion which will be constructed during Phase 2 of this project . In addition, runoff directed
into existing wetland areas associated with the Coy Ponds will slow runoff, promote infiltration, and
provide water quality treatment.
Step 3: Stabilize Drainageways
During and following urban development, natural drainageways are often subject to bed and bank
erosion due to increases in the frequency, rate, duration, and volume of runoff Although Steps 1 and 2
help to minimize these effects, some degree of drainageway stabilization is required (Urban Storm
Drainage Criteria Manual, Volume 3 -Best Management Practices, UDFCD, 2010).
COFC18.1 Drainage Report (February 5 2018).docx 8 ANdrnsoN CoNsulriNG ENqiNEERs, INC.
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All drainage swa les with i n the proj ect area have been designed such that stabil ization can be
provided by vegetative cover, which will be beneficial i n terms of maximizing the effect iveness in
disconnecting i mperv ious surfaces . Stabilizat ion will be provided i n the form of buried rock riprap at the
outlets of culverts, as well as along the sill of the emergency sp i l lway serv i ng the water qua l ity pond .
Step 4: Implement Site Specific and Other Source Control BMPs
Frequently, site-specific needs or operations require source control BMPs . This refers to
implementation of both structural and procedural BMPs (Urban Storm Drainage Criteria Manual, Volume
3 -Best Management Practices, UDFCD, 2010}.
In add ition to the LID and BMP strateg ies identified above that w i ll be implemented throughout
the project area, source pollution will be controlled using the following methods. All proposed inlets will
be constructed with recessed floors to trap sediment generated from Vi ne Drive and the proposed parking
lot. These inlets wil l also be fitted w ith Snout Hoods to min im ize the potential for trash and other debr is,
as well as greases and oils, from passing downstream i nto the vegetated swa les and wetlands . It is
anticipated that these i nlets will be ma i nta i ned by City Stormwater maintenance crews . It is noted that
the contractor w i ll be responsible for the imp lementation and ma i ntenance of BMPs during construct ion.
4.4 Low Impact Development (LID) Criteria
Per City of Fort Collins development cr iteria, 50% of newly added or modified impervious area
must be treated by LID techn i ques and 25% of new paved areas must be pervious or 75% of all newly added
or modified impervious area must be treated by LID techniques . Since this project is not proposing to
instal l pervious pavement, 75% of all newly added or modified impervious area will be treated by LID
techniques. LID/water qua lity treatment requ irements w i l l be met through the use of a new water qual ity
pond and enhancements to wet land areas associated with the Coy Ditch and Ponds . Per previous
discussion with City Stormwater and Environmental Planning staff, the proposed enhancement of the
existing wet land areas associated w ith the Coy Ditch and Coy Ponds wil l meet the City's LID requirements
for th is project.
The p r oject proposes to add 69,550 square feet (sf) of new i mpervious area that is associated w ith
the concrete tra i ls , walks, and parking lot (both Phase 1 and 2). Runoff from the entire Phase 2 park ing
lot , 10,515 sf, wi ll be pre-treated w ith a Snout Hood BMP , prior to be i ng d ischarged into the proposed
water quality pond for additional treatment. Water released from the water qual ity pond will receive
even further treatment as it is conveyed along the wetland channel of the Coy Ditch and into the wetlands
of the Eastern Coy Pond that w i ll be enhanced as part of th is project. Runoff from the entire Phase 1
parking lot, 22,855 sf, w i ll also be pre-treated with a Snout Hood BMP prior to being discharged into the
enhanced wetlands of the Coy Ditch and Eastern Coy Pond , and ultimately released to the river . In
addition, runoff from 26,110 sf of concrete trail and walk will be pre-treated with natural grass buffers
and swa les , prior to be ing conveyed into the enhanced wetlands of the Coy Ponds .
CO FC18 .1 Drai nage Re port (Fe bruary 5 2018).docx 9 ANdrnsoN CoNsuhiNG ENqiN EERs , IN c.
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In total, 56,225 sf (81%) of the new or modified impervious area proposed by the project will be
treated with a water quality pond and/or enhancement to existing wetland areas along the Coy Ditch and
Coy Ponds. Thus, meeting the City development criteria for LID techniques .
4.5 Floodplain Regulations Compliance
As illustrated on Figure 3.1 (FRIM Panel #08069C0997G), the majority of the project area is
situated within the effective 1-percent annual chance (100-year) floodplain (Zone AE) and the
southwestern portion of the project site located within the floodway. Due to the project's proposed
improvements within the floodplain and floodway, the procurement of a Conditional Letter of Map
Revision (CLOMR) from FEMA and a floodplain use permit from the City will be required prior to the
initiation of construction. It is noted that information necessary to support the CLOMR and Floodplain
Use Permit w ill be submitted as part of a separate report entitled "Hydraulic Analysis of the Cache la
Poudre River Between Linden Street and the Lake Canal Diversion Dam (Prepared in Support of a
Conditional Letter of Map Revision for the Poudre River Whitewater Park)". The CLOMR submittal was
provided to FEMA for their review on October 24, 2017. Approval ofthe CLOMR is anticipated to occur in
Spring 2018.
In addition to federal floodplain regulations, the project will be required to meet the requirements
and regulations set forth in Chapter 10 of the City Code . A completed "City of Fort Collins Floodplain
Review Checklist for 50% Submittals" has been included in Appendix B. Floatable project infrastructure
(trash cans, benches, park equipment, bike racks, etc ... ) located within the floodplain will be anchored per
an approved plan as part of the floodplain use permit. After construction of the project has been
completed and as-built survey has been collected, a Letter of Map Revision (LOMR) will be prepared and
submitted to the City and FEMA for review and approval.
COFC18.1 Drainage Report (February 5 2018).docx 10 ANdERSON CoNsulriNG ENGiNEERS, INC.
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V. DRAINAGE FACILITY DESIGN
In general, the concept of the drainage facility design for this project was to create an outfall for
the drainage basin that would be capable of safely conveying runoff generated from a 100-year rainfall
event on the basin to the Poudre River with no adverse impact to existing or proposed facilities. The
proposed design will utilize the existing infrastructure to the fullest extent possible to convey and detain
stormwater flows. New inlets, storm sewer pipes, and open channels are proposed to collect and convey
water from the Vine Drive street improvements. In addition, the project proposes modifications to the
existing lnnosphere retention pond to maintain water quality treatment while providing room for a future
parking lot and proposes a new storm sewer outfall to the Poudre River .
5.1 Proposed Project Conditions
A half-size copy of the final Utility Plans has been provided in Appendix B. A figure depicting the
proposed project condition subbasin and conveyance elements is provided as Sheet 1 in Appendix B.
Tabular results from the proposed project condition EPA SWMM model have also been provided in
Appendix B. Electronic copies of the proposed project condition EPA SWMM models are provided as
digital data on the disk included with this report. A description of proposed project improvements is
provided below:
• Vine Drive Storm Sewer Improvements: The capacity of the existing storm sewer system
west of Jerome Street was estimated at approximately 4 cfs (1 cfs per inlet). Therefore,
rainfall events that generate flows in excess of 4 cfs will pond along the street and overtop
Vine Drive at its low point, located to the west of Jerome Street. Based on the results of the
SWMM model this will occur for events less than the 2-year, which violates street drainage
criteria. Proposed project improvements associated with Vine Drive include the construction
of vertical curb and gutter along the south side of the road. In order for the proposed
improvements to meet criteria, new inlets and a storm sewer system will be installed. Due to
the widening of the street cross section as part of the project, the existing inlet on the south
side of the road will be removed, relocated and replaced with a standard 5-foot Type R inlet.
The existing 12-inch pipe that conveys flow from the existing inlet to the Western Coy Pond
will be filled and abandoned in place. The existing 12-inch pipe under Vine Drive will be
extended to the new inlet and a new 18-inch storm sewer pipe will be installed to convey flow
from the inlet eastward to the proposed storm water conveyance channel/grass-lined and
vegetated swale. A new inlet and 18-inch storm sewer pipe will also be installed at the
proposed sump location in Vine Drive to capture and convey flow to the conveyance channel.
The bottom of the new inlets will be suppressed, and a Snout Hood BMP will be installed to
provide initial water quality treatment with respect to floatable debris and sediment. Based
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on the results of the SWMM model, the proposed design will capture and convey the 100-
year event that is tributary to these inlets from the south side of the road. It is noted that
excess flows from the north of the road will continue overtop Vine Drive. Flows exceeding
the capacity of the system will overtop the curb/sidewalk and be discharged into the storm
water swale. It is further noted that drainage improvements to the north side of Vine Drive
were outside the scope of this project . However, as discussed in Section 5.2 of this report,
the proposed drainage facilities were designed to accommodate peak flow rates associated
with future fully developed conditions .
• Poudre River Trail Culverts: Flow captured by the Vine Drive Storm Sewer system will be
conveyed to the Western Coy Pond via an open stormwater channel. The channel will be
vegetated with plantings that will further promote water quality treatment and the removal
of pollutants. Prior to discharging into the Western Coy Pond, the channel will be piped
underneath the proposed Poudre River trail. To elim i nate trail overtopping, the culverts were
designed to pass the 100-year event, which required two 24-inch culverts to accommodate
cover constraints. Flows in excess of the 100-year will overtop the trail and be conveyed into
the Western Coy Pond .
• lnnosphere Retention Pond Modifications: As previously mentioned, the pond associated
with the Inverness development was sized to retain the 100-year volume from the two
development properties located on the north side of Vine Drive. Due to the proposed project
improvements, an adequate outfall can now be constructed for the pond . Consequently, the
project is proposing to modify the existing pond from a full retention pond to a water quality
pond with overflow spillway to allow the western half of the existing pond to be filled and
reserved for a future parking lot. Based on an agreement between the Inverness developers
and the City Stormwater Department, the City will take over ownership and maintenance
obligations for the pond . In exchange for the pond property, City Stormwater Staff designed
a storm sewer system to convey stormwater from the future development site east of
lnnosphere to the existing three 24-inch storm drainage pipes that cross Vine Drive and drain
into the retention pond . Since the pond was originally sized to retain and infiltrate the entire
100-year runoff volume from both the currently developed lnnosphere site and future
development located to the east of the lnnosphere site, the storm sewer was designed to
convey the 100-year runoff without detention on the future deve lopment site .
Construction and installation of this storm sewer system was conducted by City Stormwater
Maintenance Crews in the fall of 2017 . Once the City has taken ownership of the pond parcel,
Stormwater Staff has agreed that conversion of the retention pond to a water quality pond
would be acceptable as part of this project. Therefore, documentation utilized to size the
water quality capture volume of the proposed modified pond is provided in Appendix A.
Other identified improvements to the existing pond include the rerouting of flow from the
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adjacent stormwater swale into the pond so that stormwater flows can be diverted from the
Coy Ditch and the cu lvert underneath the BNSF railroad can be plugged .
• Parking Lot: The proposed parking lot will be constructed in two phases. The first phase, a
35-space parking lot, will be constructed as part of the initial project. A 5-foot Type R inlet
and 18-inch storm sewer is proposed to collect runoff from the Phase 1 parking lot and convey
it to the existing Coy Ditch/Eastern Coy Pond. The bottom of the new inlet will be suppressed,
and a Snout Hood BMP will be installed to provide initial water quality treatment with respect
to floatable debris and sediment. The system was designed to convey the 100-year rainfall
runoff from the parking lot. Flows in excess of the 100-year will overtop the curb/sidewalk
and be discharged into the exist i ng Coy Ditch/Eastern Coy Pond.
The second phase, a 27-space parking lot located to the east of the first phase, will be
constructed at a future date based on parking needs and funding. Similar to the first phase
parking lot, a 5-foot Type R inlet and 18-inch storm sewer pipe is proposed to collect runoff
from the Phase 2 park i ng lot and convey it to the proposed water quality pond. The existing
15-inch ADS storm sewer that collects water from an inlet on Vine Drive and discharges into
the retention pond will be extended and connected into the proposed in let box . The bottom
of the new inlet will be suppressed, and a Snout Hood BMP will be installed to prov ide initial
water quality treatment with respect to floatable debris and sediment. The system was
designed to convey the 100-year rainfall runoff from the parking lot.
• Outfall to River: Proposed project improvements include the installation of a 27-inch and 18-
inch storm sewer pipe to convey flow from the Western and Eastern Coy Ponds, respectively,
to the river. To limit impacts to the river and reduce construction costs, a junction box is
proposed to combine the two pond outlet pipes into a single 36-inch pipe that will outfall to
the northern river bank . The outfall system was designed to convey the 100-year event
assuming no ta il water i mpacts due to river levels. To prevent the surcharging and flooding of
the outfall system due to high river levels, flap gates are proposed to be installed on the
downstream ends of the 27-inch and 18-in ch storm sewer pipes inside the junction box . It is
antic i pated that these flap gates will reduce the capacity of the dra i nage system as river levels
rise until a level is reached where the flap gates w ill no longer be operational. For this scenar io
and for flow events that exceed the capacity ofthe system, overtopping of both the Western
and Eastern Coy Pond will occur . Overtopping flows will not be concentrated and w ill
generally flow overland and return to the river where the northern bank wil l be lowered
adjacent to the Xcel regulation station. It is anticipated that the river will overtop its banks
and completely inundate the ent ire drainage system for flow events in excess of the 10-year
discharge (approximately 5,800 cfs).
• Future Restroom: Due to funding constraints and floodplain regulations, a permanent
restroom will not be installed as part of this project. However, a fill pad will be constructed
in the northwestern corner of the site to elevate the ex isting ground above the proposed post-
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project base flood elevation of 4964.6 ft, NAVD88. When the LOMR for the project has been
approved, the fill pad will be located above/outside the 100-year floodplain and will eliminate
future floodplain permitting and regulations associated with the construction of the
permanent restroom.
• Poudre River Pedestrian Bridge: As part of the City's masterplan for the Poudre River Trail
system, the trail will eventually be relocated to the northern side of the river between Linden
Street and the BNSF Railroad when improvements to the Linden Street Bridge are
implemented. In order to reconnect Poudre River trail users with the current trail as it passes
underneath College Avenue , and to provide a pedestrian connection across the river for
residents and businesses in northern Fort Collins, a new pedestrian bridge will be installed
across the Poudre River as part of the project. The bridge will be 185-feet long and 12-feet
wide . As identified on the Floodplain Plan provided as part of the Utility Plan drawings, the
low chord elevat ion of the bridge (4964.0 ft , NAVD88) will be located approximately 0.2-feet
above the proposed/post-project base flood elevation of 4963.8 ft, NAVD88. Due to the 1%
camber ofthe bridge, the freeboard over the centerline of the river will be a minimum of 1.0-
foot. The bridge will also span the proposed/post-project floodway limits and a minimum 8-
foot clearance will be provided between the low chord and proposed trails beneath the
bridge. Since the bridge will be located above the base flood elevation, it will be designed as
a non-breakaway bridge and will be incorporated into the hydraulic modeling conducted for
the CLOMR/LOMR as part of th is project.
5.2 Fully Developed Project Conditions
Based on coordination with City stormwater staff, it was decided that a fully developed condition
scenario would be developed to evaluate the sizing of proposed project infrastructure to accommodate
fully developed conditions, as well as generate a conceptual drainage plan for future improvements. A
figure depicting the fully developed project condition conveyance elements is provided as Sheet 2 in
Appendix C. Tabular results from the fully developed project cond ition EPA SWMM model are also
provided in Append ix C. Electronic copies of the fully developed project conditions EPA SWMM models
are provided as digital data on the disk included with this report. A description of the fully developed
proposed project condition is provided below :
• Fully Deve loped Basins and Conceptual Detention Ponds: Subbasins 9, 11, 13, and 14 were
assumed to be fully developed with increased impervious areas. Per the direction of City
Stormwater staff, conceptual detention ponds were assumed for the three privately owned
properties located north of Vine Drive (Subbasins 9, 11, and 14) to detain and release fully
developed 100-year flows to a 2-year historic rate. It is noted that the conceptual detention
ponds were simulated with a two-point rating curve. Conceptual detention for Subbasin 13
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was not assumed per the development agreement between the City and the developer for
this property. Fully developed flows from this basin will be conveyed underneath Vine Drive
and into the water quality pond via the existing storm sewer system that was recently
installed by the City of Fort Collins. It is noted that additional improvements will be required
as part of the site development to capture and convey surface flow into the storm sewer
system constructed by the City of Fort Collins.
• Conceptual Future Vine Drive Improvements: In order to meet stormwater criteria, a 5-foot
Type R inlet was conceptually assumed in the sump area on the north side of Vine Drive. Flow
collected by this inlet, along with the detained released from Subbasins 9 and 11 is
conceptually conveyed underneath Vine Drive in an 18-inch pipe. This pipe conceptually
connects to the inlet on the south side of the street and into the storm drainage system
proposed by the project. The installation of the inlet on the north side of the street will reduce
the frequency of road overtopping for events less than the SO-year .
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VI. SEDIMENT/EROSION CONTROL
Permanent BMP Snout Hoods will be installed inside all stormwater inlets that are proposed for
the project. The Snout Hoods will capture the majority of sediment that could potentiality enter the site
from the western portion of Vine Drive and the proposed parking lot. The existing Inverness retention
pond located in the northeastern corner of the site will be modified to provide water quality treatment
and will act as a sediment basin for sediment entering the site from the lnverness/lnnosphere
development properties and the future parking lot. It is noted that the Snout Hoods and water quality
pond will provide pre-treatment of almost all offsite runoff from impervious surfaces. The use of the
existing Coy Ditch and associated ponds for stormwater conveyance w i ll provide an opportunity for
further water quality treatment prior to runoff being discharged to the river.
During construction, erosion control measures will be implemented in accordance with the
Colorado Department of Public Health Stormwater Discharge Permit and City of Fort Collins construction
standards . It is noted that construction of the project will be conducted as part of the Construction
Manager/General Contractor (CMGC) delivery method. A separate report entitled "Stormwater
Management Plan, Poudre Whitewater Park, Fort Collins, CO" December 2017 provides detailed
information with respect to the development and implementation of a stormwater management plan for
the project. This report was developed as part of a joint effort between Anderson Consulting Engineers
and ECI, the selected general contractor for the project.
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VII. CONCLUSIONS
Based on the hydrologic and hydraulic analysis documented in this report, the proposed
stormwater drainage design conforms to the City of Fort Collins stormwater criteria manual and Standard
Construction Specifications . The proposed stormwater drainage system will safely convey runoff
generated from a 100-year rainfall event on the basin to the Poudre River with no adverse impact to
existing or proposed facilities . The proposed inlet Snout Hoods and water quality pond will capture
sediment from off-site flows and provide initial water quality treatment. The use and enhancement of
the wetlands associated with the existing Coy Ditch and Coy Ponds for stormwater conveyance will
provide an opportunity for infiltration and additional water quality treatment prior to runoff being
discharged to the river.
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VIII. REFERENCES
Anderson Consulting Engineers, Hydraulic Analysis for the Cache la Poudre River Between Linden Street
and the Lake Canal Diversion Dam (Prepared in Support of a Conditional Letter of Map Revis ion
for the Poudre River Wh itewater Park). October 5, 2017 .
Biohabitats, Ecological Characterization Study of Poudre River Whitewater Park. November 2016.
Bio habitats, Poudre River Whitewater Park Ecological Characterization Study: Addendum for 101 East Vine
Drive (the Krush Property). January 2017 .
City of Fort Collins, Stormwater Criteria Manual (Amendments to the Urban Drainage and Flood Control
District Manual). December 2011.
City of Fort Collins Stormwater Construction Standards and Details
Earth Engineer i ng Consultants, Inc., Subsurface Exploration Report. Proposed City of Fort Collins' -Poudre
River Whitewater Park and Vine Drive Roadway Improvements, December 2016
ECI and Anderson Consulting Engineers, Stormwater Management Plan, Poudre Whitewater Park. Fort
Collins. CO. December 2017 .
Ecology and Environment, Inc ., Application for Department of the Army Pert (33 CFR 25) Poudre River
Whitewater Park. Fort Collins. Colorado: Supplement to Engineering Form 4345, Final Draft. April
4, 2017
United States Environmental Protection Agency, National Risk Management and Research Laboratory,
Storm Water Management Model, Version 5.1.010, 2015 .
Urban Drainage and Flood Control District, Urban Storm Drainage Criteria Manual. Volumes 1 and 2,
Updated January 2016, Volume 3 Updated November 2015.
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I APPENDIX A
I HYDROLOGIC AND HYDRAULIC
DOCUMENTATION
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(12)
4.1
Duration
(min)
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95
100
105
110
115
120
A new Section 4.1 is added, to read as follows:
lntensitv -Duration-Freguenc_y Curves for SWMM :
The hyetograph input option must be selected when creating SWMM input files.
Hyetographs for the 2-, 5-, 10-, 25-, 50-, and 100-year City of Fort Collins rainfall events
are provided in Table RA-9.
Table RA-9-City of Fort Collins
Rainfall Intensity-Duration-Frequency Table
for Use with SWMM
2-Year 5-Year 10-Year 25-Year SO -Year 100 -Year
Intensity Intensity Intensity Intensity Intensity Intensity
(in/hr) (in/hr) (in/hr) (in/hr) (in/hr) (in/hr)
0.29 0.40 0.49 0.63 0.79 1.00
0.33 0.45 0.56 0.72 0.90 1.14
0.38 0.53 0.65 0.84 1.05 1.33
0 .64 0.89 1.09 1.41 l.77 2.23
0.81 1.13 1.39 1.80 2.25 2.84
1.57 2.19 2.69 3.48 4.36 5.49
2.85 3.97 4.87 6.30 7.90 9.95
1.18 l.64 2.02 2.61 3.27 4.12
0.71 0.99 1.21 1.57 1.97 2.48
0.42 0.58 0.71 0.92 1.16 1.46
0.35 0.49 0.60 0.77 0.97 1.22
0.30 0.42 0.52 0.67 0.84 1.06
0.20 0.28 0.39 0.62 0.79 1.00
0.19 0.27 0.37 0.59 0.75 0.95
0.18 0.25 0.35 0.56 0.72 0.91
0.17 0.24 0.34 0.54 0.69 0.87
0.17 0.23 0.32 0.52 0.66 0.84
0.16 0.22 0.31 0.50 0.64 0.81
0.15 0.21 0.30 0.48 0.62 0.78
0.15 0.20 0.29 0.47 0.60 0.75
0.14 0.19 0.28 0.45 0.58 0.73
0.14 0.19 0.27 0 .44 0.56 0.71
0.13 0.18 0.26 0.42 0.54 0.69
0.13 0.18 0.25 0.41 0.53 0.67
- - - - -- ---- ----- --- -SWMM MODEL INPUT PARAMETERS Width % Impervious % Impervious Basin Name Area (ac) OFL (ft) %Slope (Proposed Description for Fully Developed Condition (ft)* Conditions) (Fully Developed) B-1 2.78 1211 100 2.00 60 60 Assumes 100% impervious for ponded area B-2 3.34 1455 100 3.00 50 50 Assumes 100% impervious for ponded area B-3 0.56 76 320 1.20 90 90 B-4 0.35 152 100 0.50 90 90 B-5 0.80 290 120 2.00 75 75 B-6 0.33 287 50 2.00 75 75 B-7 1.38 194 310 1.00 50 50 Assumes 100% impervious for ponded area B-8 0.74 101 320 1.20 90 90 B-9 4.68 371 550 1.00 45 85 Assumes property is fully developed B-10 1.50 163 400 0.90 90 90 B-11 0.89 194 200 0.50 45 85 Assumes property is fully developed B-12 2.50 573 190 4.40 85 85 B-13 2.16 553 170 1.00 25 85 Assumes property is fully developed B-14 2.25 446 220 0.50 25 85 Assumes property is fully developed B-15 0.88** 95** 0.50** 85** 85** *Width is calculated from area and Overland Flow Length (OFL) **Based on Information Provided by COFC Stormwater From Their Vine Drive Storm Sewer Improvement Project
-------------------PROPOSED CONDITION DETENTION NODE STORAGE CURVES Detention Node #1 (Western Coy Pond) Detention Node #2 (Eastern Coy Pond) Stage AutoCAD AutoCAD Unit Total Total Stage AutoCAD AutoCAD Unit Total Total (NAVD 88) Area Area Depth Volume Volume (NAVD 88) Area Area Depth Volume Volume (ft) (ft2) (acre) (ft) (ft3) (acre-ft) (ft) (ft2) (acre) (ft) (ft3) (acre-ft) 4955.5 9407 0.22 0.0 NIA NIA 4953 0 0.00 0.0 NIA NIA 4956 14280 0.33 0.5 5880 0.13 4954 2450 0.06 1.0 817 0.02 4957 23013 0.53 1.5 23567 0.54 4955 13074 0.30 2.0 7878 0.18 4958 33813 0.78 2.5 51807 1.19 4956 26934 0.62 3.0 27469 0.63 4958.5 40100 0.92 3.0 68929 1.58 4957 39506 0.91 4.0 60489 1.39 Spill will occur over trail at southeast corner at El. = 4958.5 4958 65918 1.51 5.0 112641 2.59 4958.5 79822 l.83 5.5 149020 3.42 Spill will occur south towards river at El. = 4958.5 Detention Node #3 (Modified Ionosphere Pond) Stage AutoCAD AutoCAD Unit Total Total (NAVO 88) Area Area Depth Volume Volume {ft) (ft2) (acre) (ft) (ft3) (acre-ft) 4955.2 0 0.00 0.0 NIA NIA 4956 3422 0.08 0.8 913 0.02 4957 5120 0.12 1.8 5155 0.12 4958 6570 0.15 2.8 10985 0.25 4959 9153 0.21 3.8 18811 0.43 4960 11700 0.27 4.8 29211 0.67 Weir for WQCV set at El. = 4958.0
ANdERSON CoNsul1iNG ENqiNEERS, INC
Civil • Water Resources • Environmental
Project Number
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I Design Procedure Form : Extended Detenti on Basi n (EDB )
Sheet 1 of 4
I Designer:
Company :
Date:
Brian Smith
An derson Consulting Engineers, Inc
November 18, 2016
Project: Poudre River Whitwater Park Project
I Location : Modiflded lnnosphere Pond
1. Basin Storage Volume
I A) Effective Imperviousness of Tributary Area , 1. la= 76.0 %
B) Tributary Area's Imperviousness Ratio (i = I,/ 100 ) i= 0.760
C) Contributin g Watershed Area Area= 6.980 ac
I D) For Watershed s Outside of the Denver Region , Depth of Average do= 0.60 In
Runoff Producing Storm
Ch<X>se One
E) Design Concept
()Naw Quality C.pb.Jre Volume (W<:P/) (Select EURV when also designing for flood control)
I ~ ... Urban Runotr Volume (EURV)
•
F) Design Volume (WQCV) Based on 40-hour Drain Time Voes1GN= 0.177 ac-rt
CV0Es1aN = (1 .0 • (0 .91 • i3 -1 .19 • i2 + 0.78 • i) / 12 ' Area)
I G) For Watersheds Outside of the Denver Region , VoESIGN OTHER = 0.247 ac-rt
Water Quality Capture Volume (WQCV) Design Volume
(VwocvonreR = (d,,"CVoEs!G>I0.43))
I
I
H) User Input of Water Quality Capture Volume (WQCV) Design Volume V DESIGN USER= ac-rt
(Only ~ a different WQCV Design Volume 1s desired )
LI .-I) Predominant Watershed NRCS Soll Group
I
D
J) Excess Urban Runoff Volume (EURV) Design Volume
For HSG A: EURV• = 1.68' i1"' EURV = ac-f t
For HSG B: EURV6 = 1.36 • i11'"
I For HSG C/D : EURVCIO = 1.20' i1 °"
2 Basin Shape : Length to Width Ratio L :W = ·1
(A basin length to width ratio of at least 2.1 will Improve TSS reduction )
I 3 Basin Side Slo pes
A) Basin Maximum Side Slop es Z= rt/rt
I (Holizontal di stance per unit vertical , 4'1 or flatter preferred)
4 Inlet
I
A) Describe mean s of providing energy dissipation at concentrated
inflow locations
" .. ·-'"" ~
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I lnnosph ere Pond WQCV Ca lcu lation .xlsm, EDS 12/6/2016, 8:09 AM
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0/0/LVI/ www.E:!Crnos.com,pnn11ana1ys1s11Lw1011Lwto
NORTH
AMERICAN
GREEN '
Discharge
Peak Flow Period
Channel Slope
Channel Bottom Width
Left Side Slope
Right Side Slope
Low Flow Liner
Retardance Class
Vegtation Type
Vegetation Density
Soil Type
44
I
0 .05
10
C
sion Control Materials Design Software
Version 5.0
Project Name: Poudre River Whitewater Park
Project Number: 120075
Project Location: Fort Collins, CO
Spillway Name: Ionosphere Water Quality Pond
Bunch Type
Fair 50 -75%
Clay
Unreinforced Vegetation -Class C -Bunch Type -Fair 50-75%
North American Green
5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
Tel. 800. 772.2040
Fax 812.867.0247
www.nagreen.com
Phase Reach Discharge !Velocity Normal Manningi Permissible Shear Calculated Shear Safety Remarks Staple
Depth N Stress Stress Factor Pattern
Unreinforced Straight 44 cfs 5.33 0.83 ft 0.05 4.2 lbs/ft2 2.58 lbs /ft2 1.63 STABLE --
Vegetation ft/s
Underlying Straight 44 cfs 5.33 0.83 ft --0.07 lbs/ft2 0.153 lbs/ft2 0.46 UNSTABLE --
Substrate ft/s
I http://www .ecmds.com/print/analysis/120075/120076 1/1
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L./L./L.UHj
NORTH
AMERICAN
CiREEN
SPILLWAY ANALYSIS
> > > lnnosphere Water Qua lity Pond
Name lnnosphere Water Quality
Po nd
Disc ha rge
Peak Flow Period
Channel Slope
43
1
0 .05
Channel Bottom Width 10
Low Flow Lin er
Retardence Class
Vegetation Type
Vegetation Density
Soil Type
C 6-12 in
Bunch Type
Fa ir 50-75%
Clay
SC250 -Class C -Bunch Type -Fair 50-75 %
Phase Reach Discharge Velocity
SC250 Stra ight 43 cfs 6.4 ft/s
Un vegetated
SC250 Straight 43 ds 5 .26 ft/s
Reinforced
Vegetation
Underlying Straight 43 cfs 5 . 26 ft/s
Substrate
Normal Depth
0 .67 ft
0.82 ft
0 .82 ft
I https ://ecmd s .com/project/120075/spillway-analysis/120076/show
t:GIVIU::i O.U (.p l(o
North American Green
5401 St. Wende l -Cynth i ana Rd.
Poseyville, Indiana 47633
Tel. 800.772.2040
>Fax 812.867.0247
www.nagreen.com
ECMDS v6.0
Mannings N Permissable Shear Calculated Shear Safety Remar Staple
Stress Stress Factor Pattern
0 .04 3 lbs/ft2 2.1 lbs /ft2 1.43 ft STABLE E
0 .05 10 lbs/ft2 2 .55 lbs/ft2 3.92 ft STABLE E
0 0 .8 lbs/ft2 0.71 lbs/ft2 1.13 ft STABLE
1/1
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Volume], Chapter 6 -Streets/Inlets/Storm Sewers
Users' Guidance:
If a UDFCD Section number in this chapter is skipped:
It was adopted as is; plea e refer to that Section in the corresponding UDFCD Manual, Volume ,
Chapter and Section.
If a UDFCD Section number in this chapter is amended or a new COFC Section in this
Chapter is added :
It is listed below; please refer to it in this document.
If a UDFCD Section in this chapter is deleted then it was not adopted by the City of Fort Collins;
The deleted UDFCD Section number will be identified as deleted in the text below.
(l ) 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
Loc al (includes places , courts, and alleys)
Collector and Arterial (Without Median)
Arterial (with Median)
Maximum Encroachment* **
No curb-topping. Flow may spread to crown of
street.
No curb-topping. Maximum si x (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
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.
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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
Local
Collector
Arterial
the median 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.
** Thes e criteria apply only to City streets where no floodplain has been designated . For areas
with des ignated floodplains, pl ease refer to Chapter 10 of the City Code for funher guidance.
( e) Table ST-4 sets forth the allowable cross-street flow for the Minor (2-Year) and the
Major (100-Year) Storm events.
Street Cl a ssification
Tabl e ST-4
A ll owable Cross -Stre et F low
Minor (2 -Ye ar) Storm F lo w
Six ( 6) inches of depth in
cross pan .
Where cross pans are allowed,
depth of flow should not
exceed six ( 6) inches in cross
pan
None.
Major (100-Year) Sto rm Flow
Eighteen ( 18) inches of depth above
gutter flow line.
Twelve (12) inches of depth above
gutter flow line.
No cross flow. Maximum depth at
upstream gutter on road edge of twelve
(12) inches .
(f) Once an allowable spread (pavement encroachment) has been establi shed 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
acl dressed by assigning a frequency (or recurrence interval) for the Minor Storm for
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ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (M i nor & Maj or Storm)
(Base d on Regul ated Criteria f or Maxi mum Allowable Flow Depth and Spread)
Project: City of Fort Collins Po udre Ri ve r Whitewater Proj ect Inlet 10 ,-------------------'-------..,.N,-o"'d""e"'s,-------'-------------------
t G '<:, !,-....) ~ t ,..\
Gutter Geometrv lEnter data in the blue cellsl
Maximum Allowable Width for Spread Behind Curb
T,
s. -
Side Slope Behind Curb (leave blank for no conveyance credit behind curb)
Manning's Roughness Behind Curb {typically between O 012 and 0.020)
Height of Curb at Gutter Flow Line
Distance from Curb Face to Street Crown
Gutter Width
Street Transverse Slope
Gutter Cross Slope {typically 2 inches over 24 inches or 0.083 Mt)
S~l longitudinal Slope· Enter O for sump condition
Manning 's Roughness for Street Sectlon (typically between 0.012 and O 020)
Max. Allowable Spread for Minor & Major Storm
Ma x. Allowable Depth at Gutter Flowlme for Mmor & Major Storm
Allow Flow Depth at Street Crown (leave blank for no)
MINOR STO RM Allowable Ca pacity ls based on Depth Criterion
MAJOR STORM Allow able Capacity is based o n Depth Criterio n
COFC18 1_1nlet Calcs .xlsm , Existing Vine Drive Sump
STR££T
CROWN
T""""•
S""°'•
naACk ::1
H""'°•
T~OWN=
W=
Sx •
Sw=
So•
nnRUT z=
:::1
a.-•t
8.0 ft
0.020 ft/fl
0.015 I
4.00 inches
22 .0 ft
2.20 fl
0.012 run
0.083 ft/ft
0.000 ft/ft
0.016
Minor Storm Majo r Storm
22 .0 22.0
l ~ches 4.0 40 ----j> 12a•~ O\J..,.~,A> ...
r r check ::s yes
Minor Storm Major Storm
SUM P SUMP jets
12/6/2016, 8·22 AM
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INLET IN A SUMP OR SAG LOCATION
,f---LO(C)-
MINOR MAJOR Design Information (Input}
Type of Inlet
CDOT/Den1oer 13 Valley Grate 3 Type = COOT/Denver 13 Valley Grale
Local Depression (additional to contlnuous gutter depression 'a' from 'Q-Allow')
Number of Untt Inlets (Grate or Curb Opening)
Water Depth at Flowtine (outside of local depression)
Grate Information
Length of a Unit Grate
Width of a Unit Grate
Area Opening Ratio for a Grate (typical values 0. 15-0.90)
Clogging Factor for a Single Grate (typical value 0.50 • 0.70)
Grate Weir Coefficient (typical value 2.15 - 3.60)
Grate Orifice Coefficient (typrcal value 0.60 - 0.80)
Curb Opening Information
Length of a Unit Curb Opening
Height of Vertica l Curb Open ing 1n Inches
Height of Curb Orifice Throat in Inches
Angle of Throat (see USDCM Figure ST-5)
Side Width for Depression Pan (typically the gutter width of 2 feet)
Clogging Factor for a Single Curb Opening (typical value 0. 10)
Curb Opening We ir Coefficient (typical value 2.3-3 .7)
Curb Opening Orifice Coefficient (typica l value 0.60 -0.70)
Low Head Performance Reduction (Calculated)
Depth for Grate Midwidth
Depth for Curb Opening Weir Equation
Combination Inlet Performance Reduction Factor for Long Inlets
Curb Opening Performance Reduction Factor for Long Inlets
Grated Inlet Performance Reduction Factor for Long Inlets
a klc:111=
No=
Ponding Depth =
L.(G) •
Wo=
Ara1k!=
C, (G) =
Cw (G )=
C,(G)=
L. (C) =
H-1 =
H1twmt =
Thetas
Wp=
C1 (C )=
C.,(C)=
C,(C)=
darai.=
deurti, =
RF CombillllhOn=
RF"'""=
RF._=
~Q.=
2 .00 I
I
4 .0 I
MINOR
3 .00
1.73
0 .43
0.50
3.30
0 .60
MINOR
NIA
NIA
NI A
NI A
NIA
NIA
NI A
NIA
MINOR
0.363
NIA
NIA
N/A
0 .63
MINOR
1.0 Total Inlet Interception Capac ity (assumes clogged condition)
WARNING: Inlet C.poclty less than Q P .. k for Minor and Major Stonms 10.0 I r Q _ .. .,,., ... o ....... -....,.,....,..---,1-
r1'1 °')( fla...i [.,..
)
~-":,le. ..I:" 1 ... +-
1L,.._ Ovt... > S" ... p-.. ~ ... ~t.! .. .s
s~ trl O...,< ~'·"' c.., ... ~1.; "-
COFC18 .1_1nlet Calcs .xlsm , Existing Vine Drive Sump
2 00 ,
4 .0
MAJOR
300
1 73
0 43
0.50
3 30
050
MAJOR
,~~
N•A
NIA
N•A
N,A
NIA
l•l'A
IN,
MAJOR
0.363
NI A
NIA
N/A
0.63
MAJOR
1.0
49.9
inches
inches r Oloerride Depths
feet
feet
feet
inches
inches
degrees
feet
ft
ft
cfs
l cfs
'2 -'{,..,. (; 11,~-l-
s .,,, .. '\...~~l
a.. Nw-~
a,, ... ~
12/6/2016 , 8:22 AM
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ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Pr0Ject : __________________ c_1ty.._o_f_F_o_rt_c_o_1_11_ns_P_o..,u.,..d_re.,....Rl,..v_e_r_W_h-'lt-•_w_a""t-•r-'-'P-ro"'J-•ct _________________ _
Inlet ID : Node 5
------i:~=i===:::J;;;;;;;;::====:=;------,'tt":Sp~.O':(',-:::$-:i~~~:-;l-, ,l-;--°""-:~=--,k\..::--::t-:-:-~7 .. ---:-~t" .... -~
Gutter GeometnJ tEnter data In the blue cells\
Maximum Allowable Width for Spread Behind Curb
Side Slo pe Behind Curb (leave blank for no conveyance credrt behind curb)
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)
Height of Curb at Gutter Flow Line
Distance from Curb Face to Street Crown
Gutter Width
Street Transverse Slope
Gutter Cross Slope (typically 2 inches over 24 Inches or 0.083 ft/ft)
Street Longitudinal Slope • Enter O for sump condition
Manning's Roughness for Street Section (typically between 0.012 and 0.020)
Max. Allowable Spread for Minor & Major Storm
Max. Allowabl e Depth at Gutter Flowtine for Minor & Major Storm
Allow Flow Depth at Street Crown (leave blank for no)
STREl:T
CROWN
T°""=I
S..C.•1
ne-=1
Ho.m•
TcROWN •
W=
Sx=
Sw=
So=
0ST,U.ET ic
:::1
8 .0 ft
0.020 l ft/ft
0.015
6.00 inches
28.0 n
2.20 ft
0.0 12 ft/ft
0.083 ft/ft
0.009 fVft
0 .016
Minor Storm Major Storm
22 .0 28.0
l~ches 6.0 12.0
r r check= yes
MINOR STORM Al lowable Capac ity Is based on Spread Criterion Minor Storm Major Storm
MAJOR STORM Allowable Capacity is based on Spread Criterion Oa11ow &~! .,.. __ 9_.0 __ ~ __ 1_6_.l __ Jl cfs
Minor storm max. allowable capacity GOOD -g,..ater than the design flow given on she.et 'Inlet Management'
Major storm max. allowable c:apacity GOOD -a~ter thin the deslan now alven on sheet 'Inlet Ma.na~m•nt'
COFC18.1_1nlet C a lcs.xls m , Basin C 12/6/2016, 8 :16 AM
I
I INLET ON A CONTI NUOUS GRADE
I
r------Lo(C)--------,r
I
I Design Informati on {ln2ut) I COOT T'll)e R Curt> Openlno 3 Type or Inlet Type•
Local Depress ion (additiona l to continuous gutter depression 'a') aux:AL.-=
Tota l Number of Un its ,n the Inlet (Grate or Curt> Opening) No•
I
Length or a Single Un it Inlet (Grate or Curt> Opening) t..·
Width of a Unit Grate (cannot be greater than W, Gutter Width) W,•
Jogg ing Factor for a Single Un it Grate (typical m,n . value• 0.5) C,.G •
actor for a Slnole Unit Curt> Ooenino (tvo ical min. value• 0 .1) c,.c.
Hvdra ulics: OK ~ a < All owable Street Ca ... •,.1rv
I n Discharge for Half of Street (fro m Sheet Inlet Management ) o..•
Spread Width T•
Water Depth at Flowtine (outs ide of loca l depress ion) d•
Water Depth at Street Crown (or at T......,.) de.OWN•
Raho of Gutter Flow to Design Flow E,•
I
Discharge outs ide the Gutte r Section W, earned in Section T, Q,•
Discharge within the Gutter Section W a.•
Discharge Beh ind the Curt> Face OBA.ac =
Flow Area within the Gutter Section W A,,.
Velocity within the Gutter Section W Vw•
I
Water Depth for Design Condition dcOCAL •
G~te Anal~is {ca lculated}
Tota l Length of Inlet Grate Opening
E.o..r~:I Ratio of Grate Flow to Design Flow
Under No-Clogging Cond it ion
I Minimum Vel ocity Where Grate Splash-Over Beg ins Vo =
Interception Rate of Frontal Flow R,=
Interception Rate of Side Flow R,•
Interception Capacity a,•
Under Clogging Condition
I Clogging Coefficient for Multiple-unit Grate In let GrateCoef •
Clogging Factor for Multiple-unit Grate Inlet Grat.Clog•
Ettective (unclogged) Length of Muttlpte-un~ Grate Inlet t..•
Minimum Velocity Where Grate Splash-Over Begins Vo=
Interception Rate of Frontal Flow R,•
I ln·terception Rate of Side Flow R,.
Actual Inter ce ption capacity o.=
Carry-Over Flow • 0.,-Q, (to be applied to curt> opening or next dis Inlet) a.•
Curb or Slotted Inlet . ,nanina Analvala (Calculated}
I
Equivalent Slopes. (based on gra te carry~over)
~:I Required Length Lr to Have 100% Interception
Under No-Clogging Condition
Effective Length of Curt, Open ing or Slotted Inlet (minimum of L, LT) ~=I lntereeption Capacity
Under Clogging Condition
I Clogging Coefficient CurbCoef =
logg ing Fader for Mu ttiplMmit Curb Opening or Slotted Inlet Curt>C log =
Effective (Unclogged) Length L..
Actua l Interception Ca pacity a,•
.Over Flow = Q _,,., .... ..,...Q a.•
I •
Inlet Interception Capa city Q •
In let Carry-Ov er Flow (flow b ypassing In let) a.•
re Pereonbaa • Q,/0., • C.,,,•l
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COFC18 1_1nlet Calcs .xlsm, Basi n C
I
MINOR MAJOR
COOT Type R Curt> Opening
3.0 30
1 t
5.00 SM
NIA N.;
NIA NIA
0.10 0.10
MINOR MAJOR
1.2 5.2
8 .0 17 .4
3.0 4.4
0.0 0.0
0814 0.438
02 2.9
1.0 2.3
0.0 0.0
0 35 0.80
2.8 3.8
6.0 7.4
MINOR MAJOR
NIA
I
NIA
NIA NIA
MINOR MAJOR
NIA NIA
NIA NIA
NI A NIA
NIA NIA
MINOR MAJOR
NIA NIA
NIA NIA
N/A NIA
NIA NIA
N/A NIA
NIA NIA
NIA NIA
NIA NIA
MINOR MAJOR
0.162 I 0.093
4 .91 13.40
MINOR MAJOR
4.91 I 5.00
1.2 3.0
MINOR MAJOR
1.00 1.00
010 0.10
4.50 4 .50
1.2 2.7
0.0 2.5
MINOR MAJOR
1.2 2.7
0.0 I 2.5
99 I 52
inches
ft
ft
er, • ft
Inches
inches
els
els
els
sq ft
fps
Inches
1ft
fps
els
ft
fps
els
els
1~
1:s
tt
els
er,
cl~) leis
I%
( C~t.. 'l -y, ... r
Z,)° '~ c ... 1 o· .. ,
J11.t,J .. -.i Nr-lc ~, ~Q,
12/612016, 8.16 AM
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ALLOWABLE CAPAC ITY FOR ONE-HALF OF STREET (Mi nor & Major St orm)
(Based on Regulated Criteria for Maximum Allowable Flo w Depth and Spread)
Proj ect: City of Fort Collins Poudre River Wh itewater Project In let ID:-----------------__.'-'-.....;;..;...__.. _ _..._,,N,-od-,-e"'4-'--{-"-"'--"""--"""-"'"-----------------
~-""'.__-+-----"'"""--------l \t P rcr(1.SS.. \ ·~., • .r c. i '.j:,... \{ ~" c. ,) r:.., c.
T. T_,.
T,
s. -
ng 's Roughness Behind Curil (typicall y between 0.012 and O 020)
treet Transverse Slope
utter Cross Slope (typically 2 inches over 24 inches or 0.083 ft/ft)
tree! Longitudinal Slope -Enter O for sump condition
nning's Roughness for Street Section (typically between 0.012 and O 020)
ax . Allowable Spread for Minor & Major Storm
Allowable Depth at Gutter Flowline for Minor & Major Storm
llow Flow Depth at Street Crown (leave blank for no)
INOR STORM All owable Capacity Is based on Depth Criteri on
AJOR STORM Allowable Capacity Is base d on Depth Criteri on
COFC18 .1_1nl et Calcs .xlsm, Basin A
STREET
CROWN
T,,_= 8.0 ft
$,,_ =1---0"'02""0--ftlft
""""= 0.015 ,._ ____ __,
Ha...e=
TCRowN =
W=
Sx=
Sw =
So=
"sTREET =
t::j
o -=1
6.00
28.0
2.20
0.026
0.083
0.000
0.0,6
Minor Storm
22 .0
6.0
r
Minor Storm
SUMP
I nches
ft
ft
f
ft/ft
lift
ft/ft
MaJorStorm
28 .0
7,7
r
Major Storm
SUMP
,~~
checic = yes
lets
5/31/2017, 9 :49 PM
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INLET IN A SUMP OR SAG LOCATION
,r----Lo(C)-->(
Design lnfonnation ,lns;!ut} I COOT T';pe R Curb Opening ..:.I Type of Inlet Type•
Local Depression (additional to conHnuous gutter depression 'a' from 'Q-Allow') -· Number of Unit Inlets (Grate or Curb Opening) No•
Water Depth at Flowline (outs ide of local depression) Ponding Depth •
Grate Information
Length of a Unit Grate L.,(G)•
Width of a Unit Grate W,=
Area Opening Ratio for a Grate (typical values O 1~.90) A,..,.
Clogging Factor for a Single Grate (typical value 0.50 • 0.70) C,(G)•
Grate Weir Coefficient (typical value 2. 15 • 3.60) C.. (G)•
Grate Orifice Coefficient (typical value 0.60 • 0.80) C,(G)•
Curb Openl ng Information
Length of a Unit Curb Opening L.,(C)•
Height of Vertical Curb Opening in Inches ~·
Height of Curb Orifice Throat In Inches Hu-•
Angle of Throat (sae USOCM Figure ST-5) Theta•
Side Width for Depression Pan (typically the gutter width of 2 feet) WP=
Clogging Factor for a Single Curb Opening (typ,cal value 0.10) C1 (C)•
Curb Opening Weir Coefficient (typical value 2 J.3.7) Cw(C)•
Curb Opening Orifice Coefficient (typical value 0.60 • 0.70) C,(C)•
Grate Flow Anafvols /Cafcuiatedl
Clogg ing Coefficient for Multiple Units Coef •1
..,togging Factor for Multiple Units Clog•
Grate Capacity as a We ir (based on Modifie d HEC22 Method)
nterceptiOn without Clogging ~=, nterceptlon with Clogging
,rate Capacity as a Orifice (based on Mod ified HEC22 Method)
nterceptlon without Clogging ~=I ntercepbon with Clogging
,rate Capacity u Mixed Flow
nterceptlon without Clogging a..•
nterceptlon wi1h Clogg ing a..•1
esulti na Grate Capacttv (assumes cloaaed condition) Co ra1.1:1
:urn 1n.nlna Flow Analvsls CCalculatedl
logging Coefficient for Multiple Units Coef •1
logging Factor for Multiple Units Clog•
urb Opening as a Weir (based on Mod lfled HEC22 Method)
nterceptlon without Clogging ~=, nterceptlon with Clogging
~urb Opening as an Orifice (based on Modified HEC22 Method )
nterception without Clogging ~.::I nterception with Clogging
urb Opening C11paclty as Mixed Flow
nterception without Clogging a~·•
nterception with Clogging a..•
ltlna Curt, Open lna Capacity {assumes clooood condition! Cc ......
Street Condttlons
Inlet Length L •I
Resultant Street Flow Spread (based on sheet 0-Al/ow geometry) T •I
Resultant FloW Depth at Street Crown de.ow •••
low Head Perf2rman~1 B!d!.:!gl2n ,~!1£!.!l!l!s!l
Depth for Grete Mldwldth do .... •
Depth for Curb Opening Weir Equalion de..,,•
Combination Inlet Performance Reduction Factor for Long Inlets RF"°""""""•
Curb Opening Performance Reduction Factor for Long Inlets RF"""'•
Grated Inlet Performance Reduction Factor for Long Inlets RFa,."' =
Total Inlet Interception Capacity (a ssumes clogged condition) a. =1
Inlet Capacitv IS GOOD for Minor and Major Stonns(>Q PEAK) a,..,..REOUfa'o'I
COFC18.1_1nlet Calcs.xlsm, Basin A
MINOR MAJOR
COOT Type R Curb Opening
3.00 I
1 I
6.0 I
MINO R
N/A
N/A
N/A
NIA
N/A
NIA
MINOR
5.00
6.00
6.00
6340
2.20
010
3.60
0.67
MINOR
N/A I N/A
MINOR
N/A I N/A
MINOR
N/A I N/A
MINOR
NIA
N/A I
N/A I
MINOR
1.00
0.10
MINOR
5.8
5.2
MINOR
9.B
B.8
MINOR
7.0 I
6.3 I
5.2 I
MINOR
5.00 I
14.4 I
0.0 I
MINOR
NIA
0.32
0.77
1.00
N/A
MINOR
5.2
0.8 I
inches
7.7 Inches
MAJOR r OIIOrride Depths
J feet
raet
NIA
MAJOR
feet
inches ~-· inches
degrees
feet
0.10
MAJOR
N/A I N/A
MAJOR
N/A 1: N/A
MAJOR
N/A 1: N/A
MAJOR
N/A l cfs
N/A l cfs
NIA lets
MAJOR
1.00 I 0.10
MAJOR
10.0 1:: 9.0
MAJOR
11 .0 1:: 9.9
MAJOR
98 lets
8.8 Ids
8.8 l cfs
MAJOR
500 lfeet
199 1ft
0.0 l inches
MAJOR
NIA ft
0.46 ft
0.99
1.00
N/A
MAJOR
8.8 cfs
r 5.9 ) cfs --i i~ Co..'°' c"// • ._J
I 01t•{,,,...,. ;2.-.o.Pt '-,_..
'-)....r\;)b-.,s·.~ ~ °" ~
'r. S c..Cs Cf:>-r"/ O"''" !,__..
v'-p &\.t •O->M )A l._+ 5/31/2017, 9:49 PM
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~
ALLOWABLE CAPACITY FOR ONE-HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Project: City of Fort Collins Poudre River Whitewater Project
Inlet 10 ,-------------------'-----,P"'h_a_s-e"'1""P"'a-,..,.k""l n-'"Lo-t,-----'--------------------
T,
Slope Behind Curb (leave blank for no conveyance credit behind curb)
Manning's Roughness Behind Curb (typicelly between O 012 and 0.020)
Height of Curb at Gutter Flow Line
Distance from Curb Face to Street Crown
Gutter Width
Street Transverse Slope
Gutter Cross Slope (typically 2 inch es over 24 inches or 0.083 ft/ft)
Street Long itudinal Slope~ Enter O for sump condition
Manning's Roughness for Street Section (typ ically between 0.012 and 0 .020)
Max . Allawable Spread for Minor & Major Storm
Max . Allowable Depth at Gutter Flowtine for Minor & Major Storm
Allow Flow Depth at Street Crown (leave blank for no)
MI NOR STORM Allowable Capacity Is based on Depth Crite ri on
MAJOR STORM Allowable Capac ity is based on Oepth Criterion
COFC1B .1_1nlet Calcs.xlsm . Pa rking Lot
STREET
CROWN
TIIW:Kc 7.0 fl
s"""" .1---o-.o-2-o--1fVfl
nltACKc 0.015 .._ ____ .....
HCUIUI• 6.00
40.0
2.00
0.017
0.083
i nches
tt
tt
TCROWN =
W•
Sx•
Sw=
So •
nsnu!eT =
0.000
0 .016
fVfl
fVfl
fVfl
Minor Storm Major Storm
S r~e "'"' k O""' ~o('{'..,)
T...x= 40.0 40. ft
dw..x .1---,e'".o'--+-~e-7_"'7=-,--1 ,nches
r r check = yes
Minor Storm Major Storm
O,uow =._l __ s_u_M_P_ ..... ._ __ su_M_P _ _.!cfs
1/31/2017, 10:30 PM
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INLET IN A SUMP OR SAG LOCATION
Desion Information flnouO
Type of Inlet
,r-Lo(C)-----.j"
COOT Type R Curb Opening
Local Depression (additional to continuous gutter depression 'a' from 'Q.Allow'}
Number of Unit Inlets (Grate or Curb Opening)
Water Depth at Flowhne (outside of local depression)
Grate Information
Length of a Unit Grate
Width of a Unit Grate
Area Opening Ratio for a Grate (typical values 0.15-0.90)
Clogging Factor for a Single Grate (typical value 0.50. 0.70)
Grate WeirCoeffic,ent (typical value 2.15. 3.60)
Grate Orifice Coofficiont (typical value a 60 • a 80)
Curb Opening Information
Length of a Unit Curb Opening
Height of Vertical Curb Opening in Inches
Height of Curb Orifice Throat in Inches
Angle of Throat (see USDCM Figure ST-5)
Side Width for Depression Pan (typically tho gutter width of 2 feet)
Clogging Factor for a Single Curb Opening (typical value 0.10)
Curb Opening Weir Coefficient (typical value 2.3-3 .7)
Curb Opening Orifice Coefficient (typical value O 60 • O 70)
Low Head Performance Reduction {Calculated)
Depth for Grate Midwidth
Depth for Curb Opening Weir Equation
Combination Inlet Performance Reduction Factor for long Inlets
Curb Opening Performance Reduction Factor for Long Inlets
Grated lnlet Performance Reduction Factor for long Inlets
Tota l Inlet Interception Capacity (assumes c logged condition )
Inlet Capacity IS GOOO for Mloor and Maier Stonns(>Q PEAK)
.:J
/
MINOR MAJOR
Type ·1-_c _oo __ T_T""yp'""e_R"T""C_u_rb_O-'pe-n1_n"-g --t
a...., = 3.00 I 3.Q/ inches
No=l---,,t;,,----41---::,',,...--t
Ponding Depth= 8.0 I 7.7 inches
MINOR MAJOR r Override Depths
L. (G) • ..---,N-,,/A-,---r---,N.,-'""A-""""feet
W0 "" NIA NIA feet
A,,,, .1---,,Nt"'A---t----,N-11."'"A---t
C, (G) .1---N/-A---t---N-/-A--,t
C,. (G) • NIA NoA
C
0
(G) .1---N-/A----+---N-.-,.--
MINOR MAJOR
L. (C) ·1-__ s_.oo _______ s_oo ___ ~feet
H-,,.. 6.00 6 OC inches
H...., .1---6-.00-,---1---,0,-0C,.,----linches
Theta"" 63.40 f3 M> degrees
w, • 2.00 2 00 feet
C. (C) • 0.10 0.10
c~ (C) .1---,J'"'.e""o--1---,J'"'s"o---1
c. (C) ·1=-.. o ... s .. 1 __ bm_ .. 0_5 .. 1-""""
MINOR MAJOR
~-· :1---'-'N/"-A'----+---'N•/'-'A----lftft
""""' 0.33 0.48
RF--., ·1-__ o_._11"'---+---'0-.99-----1
RF,-·1---1"'.'"oo'---+---,1'".oo;.;.._-1
RF.,.,. •---N-IA __ ~ __ N_I_A __
MINOR MAJOR
5 .4 a.a cfs
1.7 I 7 7 cfs
\,
r..,, .... rc r:,_.. i,. s:... s-<J:"1 .. L ('....... C ,stl .. .,L
a... la~~te-l_.,_+
COFC1S.1_lnlet Calcs .xlsm , Parking Lot 12/6/2016, 8 :22 AM
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ALLOWABLE CAPACITY FOR ONE -HALF OF STREET (Minor & Major Storm)
(Based on Regulated Criteria for Maximum Allowable Flow Depth and Spread)
Project : __________________ c.;..1 .. ty~o-f.c..F.;..ort'-'-c .. o .. 11..,1n,,,s'--P"'-o..,ud,.,r:::'e-R.,.1,..v.;.e_r:'-Wh~lt;.;•..;.w .. •cat•;;.;r..;P .. ro..,_/• .. ct..;._ ________________ _
Inlet ID : _______________________ -'P_h __ •--s.;.•--2 .. P_• .. rk=ln....._L;;.o .. 1 ________________________ _
T,
ide Slope Behind Curb {leave blank for no conveyance credit behmd curb)
Manning's Roughness Behind Curb (typically between 0.012 and 0.020)
utter Cross Slope {typically 2 inches over 2• inches or O 083 ft/ft)
treet Longitudinal Slope -Enter O for sump condition
anning's Roughness for Street Section (typically between 0.012 and 0.020)
Max. Allowable Spread for Minor & Major Storm
Max. Allowable Depth at Gutter Flowtine for Minor & Major Stom,
low Flow Depth at Street Crown (leave blank for no)
MIN OR STORM Allowable Capacit y Is based on Depth Criterion
MAJOR STORM Allowable Capacity 11 based on Depth Crit erion
COFC 1 B 1 _Inlet Calcs.xl sm, Phase 2 Parking Lot
c•OWN
r IIACIC ·1---'1"'.o __ -4fl
s"""" • 0 .020 fl/fl
n..,""= 0.0 15 ._ ____ __,
HCURe s
TatowN:
nSTReET C
:::1
0-=1
6.00
40.0
2.00
0.017
0.083
0 .000
0.0 16
Minor Storm
40.0
6 .0
r
Minor Storm
SUMP
i nches
ft
fl
fl/fl
fl/fl
fVfl
Major Storm
40.0
7.7
r
Major Storm
SUMP
1:ches
check= yes
!cf•
1/31/2017, 10:23 PM
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INLET IN A SUMP OR SAG LOCATION
.f--LO (C)----,r
COOT T:,pe R Curt, Opening
Clogging Factor for a Single Grate (typical value 0.50 -0.70)
Grate Weir Coefficient (typical value 2 .15 -3.60)
Grate Orifice Coefficient (typical value 0.60 -O 80)
urb Opening lnfonnation
ength of a Unit Curt, Opening
Height of Vertical Curb Opening in Inches
Height of Curb Orifice Throat in Inches
gle of Throat (see USDCM Figure ST-5)
dth for Depression Pan (typically the gutter width of 2 feel)
logging Factor for a Single Curt, Opening (typical value 0. 10)
urb Opening Weir Coefficient (typical value 2 .3-3 .7)
urt, Opening Orifice Coefficient (typical value 0 .60 -0. 70)
epth for Curb Opening Weir Equation
ombination Inlet Performance Reduction Fador for Long Inlets
urb Opening Performance Reduction Factor for Long Inlets
rated Inlet Performance Reduction Factor for Long Inlets
COFC1B .1_lnlet Calcs .xlsm , Phase 2 Parking Lot
Type= ·-· No=
Ponding Depth =
L. (G) =
Wo=
A..,,=
C,(G) •
C,. (G) =
C,(G)=
L. (C) =
Hw11=
H,,_•
Theta=
w,=
C,(C) =
C,. (C) =
C,(C)=
do-•
dQirti=
RF"""""'""'=
RFc111t1 =
RFa,.i.=
MINOR MAJOR
COOT Type R Curt, Opening
3.00 ' 1 I
6 .0 I
MINOR
NIA
NIA
NIA
NIA
N/A
N/A
MINOR
5.00
6.00
6 .00
63.40
2.00
0.10
3.60
0.67
M INOR
N/A
0 .33
o.n
1.00
NIA
3 00
1
77
MAJOR
N,A
NIA
N·A
NIA
I, A
N.'A
MAJOR
5.00
6.00
600
63 40
200
0.10
360
0 67
MAJOR
NIA
0 48
0.99
1.00
NIA
i nches
i nches r Override Depths
feet
feet
I
i
feet
nches
nches
degrees
feet
ft
ft
MINOR MAJOR
"'l."\(C-1-(P'\ Ct:,lf,~./.
0. 1<10-1~-,..i ..... +
1/31/2017, 10:30 PM
I
Poudre Rive r Whitewater Pa r k Project: 36" RCP Outfall to River
I Input Parameters from SWMM Model Results -
Q"" 40 cfs SWMM Node= P-1 Definiti ons -·-V 5 ft/s Assumed S ft/sec based on vegetated soil t,. Length of Protection (ft) .. 8.0 ft .. Required Area of Flow at Allowable Veloclty (fr)
I WorO 3 ft v, Taitwat er Depth (ft) ·-
Vt 1 ft Assumed 1 ft for tailwater on river WorO Diameter or Circular Conduits (ft)
Yt/0 0 .33 e Expansion ana le of the culvert flow -Fr=Q/02.s 2.6 V Allowable Non-Eroding Velocity in the Downstrea m Channel (ft/s)
I Q Design Discharge (cfs)
EF Expansion Factor
Rock Size (Section 3.2.3 from Urban Dra inase) T Width of Protection (ft)
Definitions Fr froude Number
Q Desig n discharge (ds) Equations
De Di ameter of Ci rcular Conduit .. •Q/V
EF =1/(2tan(8)) Determined Usina Figure 9-3S
Check: e =tan ·1 t 1/( 2expa nsionf actor))
Q/Dcu 2.6 z<6.0 Use Fi1ure 9--38 From USOCM Volume 2 t,. =IEF)(AJV,-W) 30<1,,<100 -T = 2(t,.tan9)+W --·-· I
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Q/01.S 7.7
YJO 0.33
9 • EapanalOfl Ano• ---e -
-/ I/ --
I-60 --/ 7 -/ --
I--~ / / / / V ~/t.4-.+ / ----I! ::J ~/ "/ f-~ <Cl ;:J~ «"v., ,. ./ --S , I I -~ / ---
I-0 "'# ./ 'I"'"~ _.,. ---f <:I I~' // / -"VV _.,.v<'~ ----~ 1 / ---4 ----7 .u o' / -.,? V ~ :.----,..... ,-yPE
1
\.. --I I ' J / ,. t,l
-___.. --~ 'I V; / // / -././ --U) I z ) / -_,::::._ ='""1 I I .. I I --! 2 -00 .2 .4 • & .. 1.0 ~ -"' ), vh ~--./ -v 110 --~, ..
---I FA ~ ..... -UH 0 0 msteod of O whenever flow ._ supercritical fn the bof rel. ------•• UN Typ• L for o d latoncti of 30 d o wnS1recrn -
I -0 J .2 .3 .4 5 .6 .T .e
-:Fip:n t..J.L Ripnp ft"OSicaa protttOO• ac drndalr N>adut oath-t (nlid for QlDu:!; 6.0) -TA ILWATER DEPTH / CONDUIT HEIGHT. Y1 /D
I I I
Riprap Size: I I
dSO •(0 .023Q)/(Yt '-'oc'·') Equation 9-16
YJ D 0.33
,-
I ---Q/Dc · ·-d50: 0.66 ft 2.6
7.9 Inches EF 3.8 Per chart
e 0.13 ·-
Per Ficure 9-38: Use Type l
I T 8 ft Width of Protection at Furthest Downstream Point
I Per COFC Code Uoslze to Tvoe M
I Extent of Protection NOTE , I I
3W or 30 9 Lp should be a min imum of 3W or 30 if Fr<8 ,---hf'tNl)fl'lf'tloJ'l'CI L, Lp should be a ma,dmum of 3W or 30 if Fr<6 --HtGM'IOf'"lll!Pf;°!'\ 19.0 ----- -,,_ t,. 19 ft If Fr>8 t hen L,..,•3D+{0/4(Fr-8)) ---
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If Fr>6 then L,....•10D+{0/4(Fr-61! ---J · -·-
---1---'-Selected Riprap Size Type M (12") --1\,J ,-J. " ,,,..,,,J .... -r--.L l l :...,' ,._.2elected Riprap Width 8 ft --,-1:C~ ~\t. ~ ~--
t--y, 1/f1?~~~ -Selected Riprap Length 19 f!!---
I --oo -*Note : Riprap bank protection along river will serve as -
-/ l · erosion protection for culvert -
~ -
>-----,._ ---~~~ ~ ~~anew --MIOIIV!tlto~ -r---"""""--.fl.6ILlllEIII ---·-,-~ --... -
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---~---·-----('W"M10t'IIMI.UOIIHtAOIW.I.. (Stt;:ct,r,U) -·--
-
t{ ' .. j ---->::1 ~<1 A ---
----_ ... ,,... ...... ,.
--lttsrMNfS (.l) :;,ntLID ,_ ---c-·
,---~ -------Iipn f-3,..L Ripnp ..,... .'tllil forc..tnrts ia-JhM. lridl tb,p <kaati
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Poudre River Whitewater Park Project: Dual 24" Trail Culverts
I Input Parameters from SWMM Model Results
Q,., 25 cfs SWMM Node = P-4 (divided by 2 for two p ipes) Definitions
V S ft/s Assumed 5 ft/sec based on veg etated soil ... Length of Protection (ft) ---... s.o ft ... Requ ired Area of Flow at Allowable Velocity ( t')
I - -
WorO 2ft v, Tailwater Depth (ft) --Yt 1.6 ft Based on depth of Western Coy Pond WorO Diameter of Circular Conduits (ft)
Yt/0 0.80 8 Expan sion an1le of the culvert flow -
~2.S 4.4 -V Allowable Non-Eroding Velodty in the Downstream Channel (ft/s ) -
I Q Design Olscha r1e (ds)
EF Expan sion Factor
Rock Size (Section 3.2.3 from Urban Oralnas•) T Width of Protection (ft) -
Definitions Fr Froude Number - --
Q Oesl11:n discharge (cfs) Equations ----I De Diameter of Ci rcular Conduit ... •0/V -EF =1/(2tan(8)) Determ ined Usina Figure 9-35
Check: 8 sta n ·111/( 2e xpa nsionfactor))
Q/Dc'·· 4,4 •<6.0 Use Fleure 9-38 From USDCM Volume 2 ... =(EF)(A,/1',-W) 3Dst,slOD
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T • 2IL,tan8)+W t-0/Dl.S 8.8 -YJ D 0.80
8 • Eaponai.on AngN --8
I-/ / -
-60 -7 -/ / -
--/ / / / I/ -~/.4# / --I! ::, ~/ '/ 1-n ,,.:::, _ «qt-v,, ./ -S , J I --~ ·-V -.____
0 ,;; / /-{"<~~~ ..... 5
f cf ( _, V/ // -~ -.
-., vv J /:;-"~ v--, --~ l ----4
/ I~ ~ o' ,,.,, -I-;f
I--,,? V ~ :.---~ -J / . _,,,! -__.... ,-yPE
1
I.. -~ 1; VJ // // ,-
I--"' ..& ~ ---I z -, .. I I -: 2
I-00 .z -~ .6 .8 1.0 -><
I ), vh ~ /.-,, w
I-Yt /D -/ --~ ~ -UH D0 insteod of O whenever flow " superc::r ili~I ~ the botr•I. ·--
-•• UN Ttpe L f or o d tstonce of !O d o wn S'reo,n -
I --0 .I .2 .5 -~ .5 .6 .7 .8
-IiP" 9 -lS. RJ.prap •. rouoa p rotKdon •• d~r t"On.dair euth-t (,·•lid for Q /D.uS ,.O)._ -TA I LWAT!:R DEPTH / CON DUIT HEIGHT , Y 1 /D
I I I -Rlprap Size I I -
dSO =(0.023QJ/(Yt'·'o,.,) Equation 9-16 -f----
YJO 0.80 -I Q/Dcu d so: 0.27 ft 6.0
3.2 Inches EF 3.8 Per chart ·-
8 0 .13
Per Fl1ure 9-38: Use Type L
T • ft Width of Protection at Furthest Downstream Point --
I Per COFC Code U2slze to T~e M -j I EKtent of Protection NOTE : -3Wor30 6 lp should be a minimum of 3W or 30 if Fr<S --t:xn;HO ,id>lll,l,P ?Cl ... Lp should be a ma,cimum of 3W or 30 if Fr<6 ---HCGM'l'Clr~Oll\ 4.3 --"""""' ---,._ L, 6 ft If Fr>8 then l,,m.,•3D+(D /4(Fr•8)J ---
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tt Fr>6 then ~=l0D+ID/4(Fr-6)J -f'. -------.... ..,., ., _ Selected Riprap Size Type M (12") -.,... / .,.. ! l. ·'. 1 ~~~ "i" '..I -r~J Selected Riprap Width 4 ft -r7 (~");$,~
1---.. 11~--~-Selected Riprap Length 6 ~ --...:,, ., ,. I I --'"'<,I,. j, ·, < r, .1 oo-----"Note: Riprap width will be doubled at a minimum --~o dual culverts -----
--/ ------
I -----,._ ---• 1R' ll80ifl:ll'IPC -"""' ..... "' ·-~-IICSf"llila) •• m.ow
----_ ...... ,.._ --.fl.llL1ll.El!
"" --
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---~---·---------
--(Wlltl10c:W,IUJOIII~ C'Sttar;w.S) -----
b:.:,-·1 ---->-
--:::i: ~ ::;;;'(;,:;,, -,J --
--·------f--... , :ZO..Wltl ............
!ltsr"""'1HTSU)
,..,_....,.
f------~ ~ --
f-----
--Fl;pA: f.J-4. Ripnp apru clttail for C"llhwa 111.a. ,rill dw d um:a~
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Poudre River Whitewater Park Project: 18" Storm Sewer Outlets
Input Parameters from SWMM Model R_e_s_u_lt_s __ _,_ __ -+---+----+----+---+----+-----+-----1
o,..
1--v
Wore
10.2 cfs SWMM Node :: P-5 (fully developed conditions)
5 ft/s Assumed 5 ft/sec based on vegetated soil
De finition s -+-----+-----'---J_---+----+---1---1---
lp Lenrth of Protection (ft)
2.0 ft ~ Requi red Area of Flow at Allowable Velocity (ft )
1.S ft Y1 Tallwater Depth (ft)
I--
Vt 1.s ft Pipe fully submerged~du_r_in~g_l _O_O·~Y•_•_r_+----+---+-W_o_r_D Diameter of Circu ::l•:...r C::o::;n:=.du::itsc:..,:lft::,l.1-. __ -+-----1----1---I
~Y~t/_D _ _, __ 1_.o_o+----+----+---t---+----+-----'f---+8 __ _,Expansion angle of the culvert flow
~u 1 ___ 3_ . ..,7 f---+----+----+---+----+-----+--V Allowable Non-Eroding Velocity in the Downst rea m Channel (ft/sL
Q Design Discharge (cfs} ---
-1-EF Expansion Factor
Roclt Size (Se ction 3.2.3 from Urban Oralna1e) T Width of Protection (ft)
1_0e_fl _nlt_lo_n~•---~---+----+---+---+----+-----'f---+F_r _t.roud~
Q Design dischar1e (cfs) Equation s I
De _ _,_o_i,_m_et_e_roTf_C_irc_u_la_r ~co_n_d_ul_t _ _,._ __ -+----t---+---~-6
EF
8
•0/V
•l/(2tan(9)) Determined Usina Figu~ --
Check:
0/0c ... ~
Q/0L5
YJD
-
-
-60
t-
~
.._~
~ ..
t-0
~
~
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t-
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3.7 •<6.0 Use Figure 9-38 From USDCM Volume 2
1---
5.6
1.00
/ / _.__
_,.___
/ I/
.. I
.z .. .. .8
Un 0 0 in1feod of O whenever flow 1, 1upercritic:al in the barrel .
•• UN Type L f or o d 1stana of lO downtnr .am
_,.___
-1-_,.___
-<--
·'-
_,.___
1!J -1---
1-
1--Fipn $1-38. Rip"'P ffOSicm prol.N'tioa at rircular Ne.dtdt-det (nJ:W CorQ/Du~6.0)_1--I : 1-Riprap Size J_ .
Equation 9·16
-tan-'( l/(2e,cpa nslonf-a ctor))
_,L •(EF)IA,/Y,·W) 3DSJ.,.S10D
T • 2(J.,.tan8)+W
9 • Eapot,alon Angle e--~------~------~-~
Tl--4--+---+--1---+--+---+--
-1--
YJD
0
/'7 7/1/
2 .3 .4 .!5 .6 .7
TAILWATER DEPTH/ CCf,IOUIT HEIGHT. Y 1/0
_,_
1.00
.e
O.Uft 1--0/0C-Y-3.7
1.5 inches EF 6.8 Per chart
0.07 -~ --
Per Fl1u re !J..38: Use Type l ---~ __ ,_ __ _.
I 2 ft Width of Protection at Furthest Down strea m Po int
Per COFC Cod e Ups lze to Type M I -I
I-t l:t
,~
,-
F,;ure 9-J..l JUpnip aprua dtail for nah'ft't1 Ul...bt lritll tb, rbnari
Exte nt of Protection -~ _l ___J_
--~r 30 __ •_.s+----1-!L,.'-s-ho_u_ld_b_e_a_m_ln_l_m_um_o_f 3_W_or_3_D_if_F_r<_B-l----l
--l----l-'L,. __ ....; __ ._1_.0,1,-__ .,...:L,._s_ho_u_Jd_b_e a maxi mum of 3W or 30 If Fr<6 l-
--l----l-'L,.---l---•-·s,1..ft __ _._1f_Fr>_B _th_•_n -=L,....,.·3D+ID/4(F ~ --
If Fr>6 then J.,....•10D+(D/4(Fr·6)) -
--+----'---~---+----'----I---,_ ---~
_ _._ ___ Se_l_e_ct_e_d_R_i~p_ra_,p'-S,_'z_e,._T_,Y~P_e_M_,(~1_2'...,')'--'----•-~ _ -~
_ _,__.c..Se'-1'-ect--'-e_d Riprap Width 2 ft
Selected Riprap Length 4 .S ft
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_ ~Note : Use this design for all 18" storm sewer pipe outlets
,_
_,.__ 1--l-----1----1
--------1-------~---1---'----1----1 --
--+----t---i----l----1------'f---_,_ --+----l---+----+----+---1----.-----1-----1
--
-
_ _,_ __ __, ___ ,_ ---1----1----1---->----"--'---
--+----+---1----_,_ __ _,_ __ _,_j __ .j__ -~ I--
-,_ I--
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APPEND/XS
PROPOSED PROJECT CONDITIONS
INFORMATION AND SWMM RESULTS
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PROPOSED CONDITION BASIN RUNOFF RESULTS
100-Year Peak
Basin Name Area (ac) 2-Year Peak 10-Year Peak 100-Year Peak Unit
Runoff (cfs) Runoff (cfs) Runoff (cfs) Runoff Rate
(cfs/acre)
B-1 2.78 4.78 10.46 25.64 9 .2
B-2 3.34 4.81 11.13 29 .33 8 .8
B-3 0.56 1.17 2.29 5.20 9.3
B-4 0.35 0.84 1.59 3.43 9.8
B-5 0.80 1.69 3.41 7.71 9.6
B-6 0.33 0.72 1.52 3.25 9.8
B-7 1.38 1.79 3 .55 9.15 6.6
B-8 0.74 1.54 3 .03 6 .87 9.3
B-9 4 .68 4.96 9 .90 25.23 5 .4
B-10 1.50 2 .77 5 .64 13.23 8.8
B-11 0 .8 9 1.07 2 .14 5.65 6.3
B-12 2.50 5.94 11.45 24.63 9 .9
B-13 2.16 1.55 3.63 11.83 5 .5
B-14 2.25 1.57 3 .30 9.89 4.4
B-15 0.88 1.39 2 .91 7 .14 8.1
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PROPOSED CONDITION DISCHARGE RESULTS
SWMM 2-Year Peak 10-Year Peak 100-Year Peak
Element Discharge (cfs) Runoff (cfs) Runoff (cfs)
N-7 1.1 2 .1 5 .7
S-4 0 .8 1.7 4 .7
N-6 10.0 20.1 49 .9
S-3 6 .9 16.9 47 .0
P-7 3.0 3.0 3.0
N-5 4.2 5 .3 7.4
P-6 4.1 5 .2 5.7
S-2 0 .0 0 .0 2.0
N-4 0 .8 1.6 7 .9
P-5 0 .8 1.5 4 .9
N-3 11.8 23 .6 55.2
S-1 11 .1 22.1 50 .2
N-2 11.1 22.1 50 .2
P-4 10.6 21.2 50.3
D-1 14.4 30 .2 73 .8
P-3 7.8 16.4 32 .3
N-12 3.1 6 .9 21.7
S-6 2.5 5 .6 22 .3
N-14 1.4 2.9 7.1
P-13 1.4 2 .9 5.0
N-13 1.4 2.9 5.0
P-12 1.6 3 .0 5.0
N-11 4 .1 8 .6 25 .0
P-11 4 .3 9 .1 23 .6
N-10 4 .3 9 .1 23 .6
P-10 1.4 2.9 23 .6
N-9 1.4 2.9 42 .4
P-9 1.6 3 .0 42 .4
N-8 4 .1 8 .6 42 .4
P-8 4 .3 9.1 42 .3
D-3 4 .3 9 .1 54 .7
S-5 4.4 9 .1 41.0
D-2 9.1 19 .2 70 .3
P-2 9 .1 19.2 12 .2
N-1 9 .1 19 .2 40 .3
P-1 9.0 19.0 40 .3
0-1 11.4 24.0 40.3
Description
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APPENDIXC
FULLY DEVELOPED WITH PROJECT CONDITIONS
INFORMATION AND SWMM RESULTS
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FULLY DEVELOPED CONDITION BASIN RUNOFF RESULTS
100-Year Peak
Basin Name Area {ac)
2-Year Peak 10-Year Peak 100-Year Peak Unit
Runoff {cfs) Runoff {cfs) Runoff {cfs) Runoff Rate
{cfs/acre)
8-1 2 .78 4.8 10 .5 25 .64 9 .2
8-2 3.34 4 .8 11.1 29 .33 8 .8
8-3 0 .56 1.2 2.3 5 .20 9.3
8-4 0.35 0 .8 1.6 3.43 9 .8
8-5 0.80 1.7 3.4 7 .71 9 .6
8 -6 0 .33 0 .7 1.5 3 .25 9 .8
8-7 1.38 1.8 3 .6 9.15 6 .6
8-8 0.74 1.5 3.0 6.87 9 .3
8-9 4.68 7.5 15 .7 38.29 8 .2
8-10 1.50 2 .8 5 .6 13 .23 8 .8
B-11 0 .89 1.8 3.5 8 .14 9.1
8-12 2 .50 5.9 11.5 24 .63 9.9
8-13 2 .16 4.8 9.3 20 .71 9 .6
8 -14 2 .25 4.4 8 .8 20 .34 9 .0
8-15 0 .88 1.4 2.9 7 .14 8.1
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FULLY DEVELOPED CONDITION DISCHARGE RESULTS
SWMM 2-Year Peak 10-Year Peak 100-Year Peak
Element Discharge (cfs) Runoff (cfs) Runoff (cfs)
D-6 1.8 3.5 8.1
P-17 0 .8 0 .9 1.1
N-7 0.8 0.9 1.1
P-16 0 .8 0 .9 1.1
D-5 7.5 15.7 38 .3
P-15 3 .1 3.9 5.0
N-6 1.5 3 .0 7 .3
S-3 0 .0 0 .0 4 .2
N-14 2.8 5.6 16.6
S-4 0 .0 0 .0 7.3
P-14 2.8 5.6 6.7
N-13 5 .3 7 .0 9.4
P-13 5 .3 7 .0 9.4
P-7 1.5 3 .0 3.0
N-5 2 .7 5 .3 7.0
P-6 2 .7 5 .1 5.7
S-2 0 .0 0 .0 1 .0
N-4 6 .0 8 .6 12 .7
P-5 6 .0 8 .6 10 .2
N-3 8 .7 13.7 22.5
S-1 7 .7 12 .3 20 .1
N-2 7 .7 12 .3 20 .1
P-4 7 .5 11.6 18.5
D-1 10.7 20 .9 40.1
P-3 6.8 12 .3 23.2
N-12 4 .8 9 .3 20.7
S-6 3 .9 7 .9 20.6
D-4 4 .4 8 .8 20 .7
P-20 1.1 1.2 1.5
N-17 1.1 1.2 1.5
P-19 1.1 1.2 1.5
N-16 1.4 2 .9 7 .1
P-18 1.4 2 .9 6 .6
N-15 2 .1 3 .5 6 .6
P-12 2.4 3 .6 6.2
N-11 6 .3 11.4 26 .8
P-11 6 .4 11.8 24 .2
N-10 6.4 11.8 24 .2
P-10 6 .5 11.8 24 .2
N-9 11.0 22 .1 43 .8
P-9 11.0 22 .1 43 .8
N-8 11.0 22 .1 ' 43.8
P-8 10.9 21.9 43 .7
D-3 13.2 26 .9 56 .1
S-5 2 .6 12 .1 42 .6
D-2 6 .5 17.5 73 .6
P-2 4 .1 8 .0 11 .4
N-1 9 .6 19.2 32.4
P-1 9 .6 19.2 32.4
0-1 9 .6 19.2 32.4
Description
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