HomeMy WebLinkAboutMONTAVA PUD - ODP180002 - MONTAVA SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE REPORTMONTAVA
Master Drainage Study
Fort Collins, Colorado
Martin/Martin, Inc. Project No.: 17.0946
December 5, 2018
Prepared For: Max Moss
HF2M
430 North College Avenue, Suite 240
Fort Collins, Colorado 80524
Prepared By: Martin/Martin, Inc.
12499 West Colfax Avenue
Lakewood, Colorado 80215
303.431.6100
Principal-in-Charge: Matt Schlageter, P.E.
Project Manager: Peter Buckley, P.E.
Project Engineer: Ryan Byrne, P.E., CFM
TABLE OF CONTENTS
SECTION 1 - INTRODUCTION ......................................................................................................................... 1
1.1 Background and Objectives .............................................................................................................. 1
1.2 General Location ............................................................................................................................... 1
1.3 Existing Site information ................................................................................................................... 2
SECTION 2 - MAJOR DRAINAGE BASIN .......................................................................................................... 2
2.1 Overall Basin Description .................................................................................................................. 2
2.2 Existing Drainage Facilities ................................................................................................................ 4
2.3 Previous Studies and Hydrologic Models .......................................................................................... 5
SECTION 3 - HYDROLOGY .............................................................................................................................. 5
3.1 Rainfall .............................................................................................................................................. 5
3.2 Sub-basin Properties ......................................................................................................................... 7
3.3 Conveyance Element Properties ....................................................................................................... 7
3.4 Detention Basin Properties ............................................................................................................... 7
SECTION 4 - EFFECTIVE FLOODPLAIN ............................................................................................................ 7
SECTION 5 - PROJECT DESCRIPTION .............................................................................................................. 7
SECTION 6 - PROPOSED DRAINAGE FACILITIES ............................................................................................. 8
6.1 2017 Cooper Slough Master Planned Improvements. ...................................................................... 8
6.2 Impacts from Montava Development to Cooper Slough (ICON) .................................................... 10
6.3 Development Master Plan .............................................................................................................. 11
6.4 Stormwater, Light Imprint Design, Water Quality Treatment and Low Impact Develoment ......... 13
SECTION 7 - CONCLUSION ........................................................................................................................... 18
7.1 Master Plan Conformance .............................................................................................................. 18
7.2 Criteria Compliance ......................................................................................................................... 18
REFERENCES ............................................................................................................................................. 19
APPENDICES
Appendix A ................................................................................................................. Supporting Documents
Appendix B ................................................. Relevant Portions of 2017 Cooper Slough Alternatives Analysis
Appendix C ........................ Impacts from Montava Development to Cooper Slough (Draft Memo by ICON)
Appendix D ................................................................................................ Master Plan Hydrologic Modeling
Appendix E .............................................................................................. Master Plan Hydraulic Calculations
Appendix F .................................................................................................. Montava Natural Areas Concept
Appendix G .................................................................................................... Master Plan Routing Schematic
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SECTION 1 - INTRODUCTION
1.1 Background and Objectives
The Montava Master Plan (hereby referred to as “The Development”) is the result of an unprecedented
collaborative effort over the past several months. The developer, HF2M has been working with
Anhueser-Busch to redevelop the nearly 850-acre parcel west of the current brewery. HF2M is taking
this opportunity to plan a true Traditional Neighborhood Development (TND) community with an
integrated mix of uses including housing, employment, schools, parks, natural areas and agriculture.
As with any development, stormwater management infrastructure creates the backbone of the master
plan to ensure that both on and off-site runoff can be conveyed through the property, in a manner
which does not cause adverse impacts to the proposed infrastructure, insurable structures, as well as
adjacent properties, considering both the quantity and quality of stormwater.
The Development lies within the downstream portion of the Cooper Slough Watershed, which yields
significant surface runoff upstream and through the property during minor and major storm events. The
existing Cooper Slough drainageway is ill-defined, and constructed irrigation ditches have taken over as
primary conveyance elements. The purpose of this study is to identify necessary stormwater
management improvements within the development to support full-buildout conditions, taking into
consideration existing off-site conditions. Improvements are anticipated to include stormwater
conveyance elements, both open and closed conduit systems, on-site and regional detention, irrigation
diversions to maintain decreed flows, outfall structures, and water quality enhancements through the
implementation of green, low-impact development approaches.
1.2 General Location
The Development is located in the northwest quarter and a portion of the southwest and northeast
quarters of Section 4, Township 7 North, Range 68 West of the 6th Principal Meridian, as well as a
portion of the southwest quarter and east half of Section 32, and a portion of the west half of Section
33, Township 8 North, Range 68 West of the 6th Principal Meridian, Larimer County, City of Fort Collins,
Colorado. The property is bordered by farm land and Richards Lake Rd. (E Co Rd 52) to the north,
Mountain Vista Dr. (E Co Rd 50), farm land, City of Fort Collins property, the Larimer and Weld Canal,
and Trail Head and Waterglen Subdivisions to the south, the Colorado & Southern Railroad, the
Anheuser Busch brewery, and I-25 to the east, and farm land, the No. 8 Ditch, Storybook Subdivision,
Forbes Minor Subdivision, and Maple Hill Subdivision to the west. A vicinity map is provided in Figure 1.
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Figure 1: Montava Vicinity Map
1.3 Existing Site information
The existing site use is 100% agricultural, with a variety of crops, some of which support the existing
Anheuser Busch brewery to the east. A handful of residential structures are located along North
Giddings Rd., which runs in the north/south direction and divides the site from east to west. The existing
Anheuser Busch greenhouse facility and an existing electrical sub-station are located adjacent to the
northeast quadrant of the property and will remain post re-development. The property generally drains
via shallow sheet flow and roadside ditches in the southeasterly direction towards the Larimer and Weld
Canal at an average slope of approximately 3.8%. The existing Anheuser Busch stormwater outfall
discharges through a culvert at Mountain Vista Dr., which discharges to an open channel through The
Development to the Larimer and Weld Canal.
SECTION 2 - MAJOR DRAINAGE BASIN
2.1 Overall Basin Description
The Development is located within the lower portion of the Cooper Slough Watershed. The Cooper
Slough drainage basin resides in northeast Fort Collins and unincorporated Larimer County, Colorado. It
is a long and slender watershed, flowing from north to south, comprising 28 square miles which are
tributary to Box Elder Creek and the Cache la Poudre River. The watershed begins at the confluence
with Box Elder Creek (about one-half mile south of Mulberry Street and slightly west of I-25) and
proceeds north for 20-miles to Larimer County Road 80 at a location northwest of the Town of
Wellington. The basin has a maximum width of 3.9-miles at a location just south of Wellington.
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Predominant land uses are characterized by farmland and open space, with development occurring
mainly in the southern portion of the watershed, near northeast Fort Collins.
The Cooper Slough watershed can be divided into upper and lower portions by the Larimer & Weld
Canal (L&W Canal) which transects the basin from west to east and intercepts natural and man-made
drainages. Upper Cooper Slough is significantly larger than the Lower Cooper basin, at 26.4 sq.-miles and
2.3 sq.-miles respectively. There are three primary drainage paths in Upper Copper Slough, which flow
from north to south. The western most flow path is the Number 8 Outlet Ditch (No. 8 Ditch) which
carries both storm and irrigation flows. It has been noted in previous studies that the capacity of this
ditch is “severely limited” (ACE 2006) and is in need of improvements, which will be implemented for
the reach of the No. 8 Ditch through The Development. In addition to the irrigation and drainage
ditches, four (4) significant irrigation reservoirs exist in the upper watershed. These include the North
Poudre Reservoirs Nos. 2, 5, and 6 and the Windsor Reservoir No. 8.
Since the L&W Canal captures flows from the entire upper watershed there are multiple locations, in
multiple watersheds, where storm flows will spill from the canal. In the Cooper Slough basin, the most
notable spill is in the Waterglen development area at the upper end of the historic Cooper Slough
channel. This side spill is located at the primary outfall location from The Development. A vicinity map of
the Cooper Slough watershed is provided in Figure 2.
Figure 2: Cooper Slough Watershed Vicinity Map
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2.2 Existing Drainage Facilities
2.2.1 No. 8 Outlet Ditch Diversion and Sod Farm Detention
The existing No. 8 Outlet Ditch side spills during major storm events along its left bank into the Sod
Farm, north of Richards Lake Rd. The diversion initiates incidental detention in a low-lying area of the
farm. Modeling indicates that the majority of the 100-year storm flows within the ditch are diverted and
retained in the existing depression.
2.2.2 No. 8 Outlet Ditch
After side spilling to the Sod Farm, the No. 8 Ditch continues south along the west boundary of The
Development. The ditch conveys tributary storm runoff from the existing agriculture, as well as the
Maple Hill and Storybook subdivisions, prior to discharging from The Development at Mountain Vista Dr.
From this point, the ditch continues south and intercepts the L&W Canal, approximately half of a mile
south of The Development. In addition to stormwater runoff, the ditch caries the decreed irrigation flow
of 125 cfs. The No. 8 Ditch Company has offered to shut down the irrigation flows during large storm
events, with the potential to reduce flows discharging into the L&W Canal, and ultimately reduce the
spill out of the L&W into Cooper Slough.
2.2.3 C&S Railroad Diversion at Anheuser Busch (AB)
An existing side spill from the Cooper Slough floodplain existing along the easterly property boundary,
over the C&S Railroad, and into the AB property. According to modeling, the side spill occurs
approximately half of a mile south of Richards Lake Road. The spill diverts approximately 459 cfs to the
AB property during a 100-year event.
2.2.4 AB Detention Pond #425
Pond 425 is located south of the main AB facility adjacent to the L&W Canal. With the introduction of
Pond 429, the revised detention facility accepts 907 cfs from the AB property during a 100-year storm
event and attenuates discharges to approximately 839 cfs, of which 418 cfs discharges into the L&W
Canal, and the remaining 421 cfs discharges over the L&W Canal to Cooper Slough. The resulting stored
100-year volume is approximately 47 ac-ft The model provided by ICON represents Pond 425 based on
the same stage-storage-discharge curves as the 2006 Master Plan, prepared by Anderson Consulting
Engineers. Note that Martin/Martin has verified that the modeled stage-storage-discharge relationships
do not represent current conditions, due to a discontinuous berm elevation along the L&W Canal.
2.2.5 C&S/Crumb Detention Basin #426
Where the Cooper Slough floodplain intercepts the L&W Canal, runoff is retained behind the existing
C&S Railroad embankment creating incidental detention. The incidental detention makes up the existing
C&S/Crumb Pond, also known as Pond 426. During a 100-year event, the peak of approximately 1,306
cfs is conveyed to this location, and the incidental detention attenuates this flow to approximately 661
cfs prior to discharging to the L&W Canal over the railroad embankment. The resulting stored volume is
approximately 240 ac-ft.
2.2.6 L&W Canal Waterglen Spill
Currently, major storm flows spill at locations where the canal capacity is limited, most notably at the
defined spillway directly upstream of the Waterglen Subdivision and the FEMA regulatory mapped
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portion of Cooper Slough. The spill is located where Ponds 425 and 426 discharge into the canal, and
represents the primary outfall from the proposed Development.
2.3 Previous Studies and Hydrologic Models
The original hydrologic model for the Cooper Slough Basin was produced by Anderson Consulting
Engineers, Inc. (ACE) of Fort Collins, CO between 2002 and 2006. The model was developed using the
ModSWMM hydrology model and included the 2-, 5-, 10-, 25-, 50-, and 100-year flood frequency events.
This model has since been converted to EPA SWMM in 2014 by ICON Engineering, Inc. (ICON). The ICON
model represents the baseline model for the proposed development and is based on current existing
conditions. The model was developed for the 100-year flood frequency condition only.
The following list presents major studies of the Cooper Slough watershed; these study references are
per the City of Fort Collins Cooper Slough Alternatives Analysis Update, by ICON Engineering, Inc.,
October 2017.
• “Cooper Slough, Boxelder Creek Master Drainageway Planning Study”; SLA, August 1981;
• “Hydrology Report, Anheuser Busch Company, Inc.”; Ayres Associates, January 2000;
• “Technical Documentation for the Hydrologic Modeling of the Boxelder Creek/ Cooper Slough
Basin”; Anderson Consulting Engineers, Inc., January 2002;
• “Technical Documentation for the Alternatives Feasibility Analysis of the Boxelder Creek/ Cooper
Slough Basin”; Anderson Consulting Engineers, Inc., December 2002;
• “Selected Plan of Improvements for the Boxelder Creek/ Cooper Slough Basin”; Anderson
Consulting Engineers, Inc., April 2004;
• “Upper Cooper Slough Basin Selected Plan of Improvements”; Anderson Consulting Engineers,
Inc., June 2006;
• “Box Elder Creek / Cooper Slough Hydrology Update”; ICON Engineering, Inc., April 2014;
• “Conditional Letter of Map Revision (CLOMR) for East Side Detention Facility (ESDF), Larimer &
Weld Canal Crossing Structure (LWCCS), Opening Of I-25 Boxes, Siphon Of Lake Canal, Prospect
Road Bridge Replacement, Boxelder Creek Overflow. Also Known As (Boxelder 6)”; Ayres
Associates, February 2015.
• “City of Fort Collins Cooper Slough Alternatives Analysis Update”, ICON Engineering, Inc., October
2017.
SECTION 3 - HYDROLOGY
3.1 Rainfall
Rainfall hyetographs used for the 2014 Existing Conditions hydrology study are based on the City’s 2-
hours rainfall distribution presented in the Fort Collins Stormwater Criteria Manual (City of Fort Collins,
November 2017). As described in the 2014 ICON update and subsequent revisions, rainfall within the
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Cooper Slough watershed north of County Road 54 in the Cooper Slough watershed was reduced by a
factor of 7%; rainfall depths within the Box Elder Creek watershed north of County Road 54 (including
the SCS Pond watersheds) were reduced by a factor of 25%; and rainfall hyetographs for all areas south
of County Road 54 remained unmodified from the City’s criteria. Additionally, rainfall hyetographs for
the Montava match the City’s criteria.
Table 1: Rainfall Hyetographs
Rainfall Hyetographs (100-year)
Time
(min)
Rainfall Intensity (in/hr)
100% Event
(no reduction)
93% Event
(7% reduction)
75% Event
(25% reduction)
6:00 0.00 0.00 0.00
6:05 1.00 0.93 0.75
6:10 1.14 1.06 0.86
6:15 1.33 1.24 1.00
6:20 2.23 2.07 1.67
6:25 2.84 2.64 2.13
6:30 5.49 5.11 4.12
6:35 9.95 9.25 7.46
6:40 4.12 3.83 3.09
6:45 2.48 2.31 1.86
6:50 1.46 1.36 1.10
6:55 1.22 1.13 0.92
7:00 1.06 0.99 0.80
7:05 1.00 0.93 0.75
7:10 0.95 0.88 0.71
7:15 0.91 0.85 0.68
7:20 0.87 0.81 0.65
7:25 0.84 0.78 0.63
7:30 0.81 0.75 0.61
7:35 0.78 0.73 0.59
7:40 0.75 0.70 0.56
7:45 0.73 0.68 0.55
7:50 0.71 0.66 0.53
7:55 0.69 0.64 0.52
8:00 0.67 0.62 0.50
Consistent with previous studies, the rainfall hyetographs are delayed by 6-hours to allow time for a
base flow to build up in the No. 8 Outfall Ditch and the Larimer & Weld Canal.
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3.2 Sub-basin Properties
Sub-basin delineation and parameters remain consistent with the 2014 Existing Conditions Hydrology
model expect as described in Section 6 of this report. General sub-basin parameters were defined as
follows:
• Impervious Depression Storage – 0.1 inches
• Pervious Depression Storage – 0.3 inches
• Maximum Infiltration Rate – 0.51 inch/hour to 2.0 inch/hour
• Minimum Infiltration Rate – 0.50 inch/hour
• Horton’s Decay Rate – 0.0018 inch/second (6.48 inch/hour)
• Areas of Zero Detention Depth – 1%
• Pervious Area Manning’s ‘n’ – 0.25
• Impervious Area Manning’s ‘n’ – 0.016
The maximum 0.51 inch/hour infiltration rate shown above was only used in sub-basins south of County
Road 54 and within the Montava Development. Similar to the 2006 Master Plan, areas north of CR54
used a higher infiltration rate of 2.0 inch/hour. The minimum infiltration rate for these areas did not
change.
3.3 Conveyance Element Properties
Conveyance elements remain consistent with the 2014 Existing Conditions Hydrology model except as
described in Section 6 of this report.
3.4 Detention Basin Properties
Detention basin parameters remain consistent with the 2014 Existing Conditions Hydrology model
except as described in Section 6 of this report. Sub-basin delineation and conveyance elements routing
scheme for the portion of the Cooper Slough through and adjacent to the Montava development are
presented on the master plan routing schematic included in Appendix D.
SECTION 4 - EFFECTIVE FLOODPLAIN
Cooper Slough through The Development, upstream of the Larimer and Weld Canal, has not been
mapped by FEMA per FIRM 08069C0982F, effective December 19, 2006. Detailed study data begins just
downstream of the L&W Canal through the Waterglen Subdivision. It is not anticipated that the
CLOMR/LOMR process will be required for the proposed drainage infrastructure improvements.
SECTION 5 - PROJECT DESCRIPTION
Montava will be a true mixed-use community encompassing every form of housing, mixed-used
community services retail, schools, employment, parks, natural areas, agriculture, and light industrial
use. The Development has been planned in a comprehensive way with early engagement of city staff,
utility providers, adjacent landowners, and subject experts. The process included a neighborhood
meeting with nearly 100 attendees, and a week-long design charette including multiple topic meetings,
three public presentations, seven interim plans and a final master plan. The design team includes
national and international experts in Traditional Neighborhood Design, agri-urban developments,
transportation planning and affordable housing design and construction. These experts have teamed
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together with local design and engineering consultants, market experts, and technology leaders to
create a comprehensive planning approach.
Montava is intended to be developed as a true TND community. Building a true walkable community
based on traditional neighborhood forms. The architecture is intended to be a mixture, but calling on
the history of what has made Colorado special. If you were to look at the architectural inspiration, look
no further than traditional downtown Fort Collins historical architecture. It will also be inspired by the
history of agriculture in the area, while incorporating a working 40-acre vegetable farm as part of that
overall development.
The goal with Montava is to serve as an extension of the heart of Fort Collins. The residential
community will be compatible with all the areas to the West/SW/S. The town center will service the
entire NE sub area with services including grocery and others. The transportation plan will tie into the
entire community including downtown Fort Collins. Any employment that is enabled by this
development will provide opportunity for anyone in the surrounding areas. As the current land use is
farming, the natural features of the area will certainly change. However, the intent is to incorporate
agriculture, Nature in the City, and Natural areas, throughout the entire project.
SECTION 6 - PROPOSED DRAINAGE FACILITIES
6.1 2017 Cooper Slough Master Planned Improvements.
The following outlines the City’s selected plan improvements and they were incorporated into the
Montava master drainage plan.
6.1.1 Anheuser Busch Property – Developed Condition Hydrology
The 2017 study assumed fully developed land use for the Anheuser-Busch (AB) property based on the
City’s Mountain Vista Subarea Plan (City of Fort Collins, 2009). This area represents the Montava
Development. Per direction from the City, the Montava Development was modeled including conceptual
100yr (developed) to 2yr (historic) detention basins; whereas and AB areas east of the CSRR were
proposed to drain to an improved regional pond (AB Detention Pond 425) with a specified 100-year
release rate (392-cfs) based on the previous master plan.
6.1.2 Poudre Reservoir No. 6 - Outlet Sill Modification
The stage-discharge curve for the Poudre Reservoir No. 6 was modified to account for a proposed 8-inch
iron weir plate on the reservoir outlet; this improvement is consistent with the 2006 Master Plan. These
improvements have not been incorporated into the Montava Master Plan.
6.1.3 No. 8 Outlet Ditch Diversion at Sod Farm
The 2017 master plan incorporated a formalized flow split (flow limiting diversion structure) on the No.
8 Outlet Ditch at the Sod Farm location. This improvement is consistent with the 2006 Master Plan.
These improvements have not been incorporated into the Montava Master Plan. Although, it is
anticipated that the benefits of the existing incidental detention will be realized in its current condition.
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6.1.4 Sod Farm Detention
The 2017 master plan formalized and improved an existing detention area at the Sod Farm location. All
flows from the Sod Farm Diversion are detained and returned to the No. 8 Outlet ditch through a
proposed pipe. This improvement is consistent with the 2006 Master Plan. These improvements have
not been incorporated into the Montava Master Plan. Although, it is anticipated that the benefits of the
existing incidental detention will be realized without implementing the Sod Farm outfall pipe.
6.1.5 No. 8 Outlet Ditch Diversion near Mountain Vista Drive
The 2017 master plan incorporated a formalized flow split (flow limiting diversion structure) on the No.
8 Outlet Ditch at or near Mountain Vista Drive. Flows in excess of the decreed 125-cfs will be diverted
from the No. 8 and proceed to the proposed C&S/ Crumb detention basin. This improvement is
consistent with the 2006 Master Plan – “Selected Plan Optional Component”. The master planned No. 8
Ditch diversion will be implemented with the Montava Master Plan infrastructure improvements.
Although, the diversion is being planned further north to optimize proposed conveyance improvements
through the development.
6.1.6 C&S Railroad Diversion
The existing flow split at the C&S railroad tracks in the AB area was removed from the hydrology model.
This improvement will eliminate flow spills over the railroad and contain the water on the west side of
the tracks. This improvement is consistent with the 2006 Master Plan. The Montava drainage
infrastructure improvements will eliminate this diversion, with an open channel conveyance element
being planned along the easterly property boundary.
6.1.7 AB Pond No. 425
The 2017 master plan incorporated the proposed storage and outlet improvements from the 2006
master plan for the AB detention Pond No. 425. These improvements slightly increase the existing pond
storage. However, the master plan proposes to leave Pond 425 outflows connected to the L&W Canal –
this is a departure from the 2006 Master Plan, where the outflows were bypassed under the canal. The
Montava drainage infrastructure improvements are proposing to improve Pond 425 and will utilize an
updated spillway to the L&W Canal, as well as create an overflow discharge over the L&W Canal to the
Cooper Slough drainageway through the Waterglen Subdivision.
6.1.8 C&S/ Crumb Pond No. 426
The proposed C&S/ Crumb pond no. 426 and outlet structure were re-evaluated, based upon the
updated hydrology, to provide results consistent with the 2006 Master Plan outflow rate of 550-cfs. The
pond outflows were bypassed under the L&W Canal and reconnected to the lower Cooper Slough
channel. The Montava development is proposing to discharge Pond 426 below the existing C&S railroad
corridor to Pond 425, with an overflow discharge to a southerly pond, which will drain directly to the
L&W Canal.
6.1.9 Update to the L&W Canal Hydraulics Model
The L&W Canal unsteady HEC-RAS model from the ESDF CLOMR was updated with the Alternatives
Analysis hydrology including disconnection of the C&S/ Crumb Pond 426. The resulting canal spill flows
were imported into the Lower Cooper Slough portion of the EPA-SWMM hydrology model.
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6.1.10 Crossing Structure Improvements at Vine Drive, Mulberry Street and Mountain Vista Drive
Proposed culvert improvements were evaluated at the E. Vine Drive and E. Mulberry Street crossings
using hydraulic modeling in HEC-RAS. The ESDF CLOMR and Master Plan Project hydraulic models were
used. The Proposed culvert improvements were evaluated at Mountain Vista Drive at two locations.
The Federal Highway Administration HY-8 program was used to evaluate the crossings. The Master Plan
Project EPA SWMM model was used to determine the peak flows at the crossing.
6.2 Impacts from Montava Development to Cooper Slough (ICON)
ICON developed a draft memorandum, titled Impacts from Montava Development to Cooper Slough
[Draft Memo], dated September 13, 2018. The memorandum was intended to verify the development
Master Plan modeling prepared by Martin/Martin, Inc., and give recommendations based on allowable
minor and major release rates to the L&W Canal and Cooper Slough.
First, it was suggested that the detention effects on the immediate development be reviewed. Due to
the significant sizes of the proposed regional ponds and outlets, it is feasible that effective detention is
not being generated for the on-site runoff and generating higher discharges downstream. This may also
be more prevalent for low flow events, which would essentially pass through the detention ponds.
Second, it was suggested that the pond outlet configurations be adjusted to further delay the peak
outflows from the proposed ponds. Specifically, adjustments could potentially be made to the outlet of
the C&S Pond 426 and the C&S Overflow Pond. Sensitivity runs showed that by changing the C&S outlet
to a staged configuration, consisting of a 36-inch culvert placed at the invert of the pond with dual 3’(H)
x 8’(W) CBC’s located approximately 3-feet above, the hydrograph out of the pond would be delayed
such that flows in Cooper Slough would no longer be increased. In addition to the staged outlet
structure, more water can be conveyed to the Overflow Pond reducing the peak flow going to the AB
Pond 425 and in turn Cooper Slough.
It is recommended that the proposed improvements be fine-tuned during preliminary and final design
to ensure that flows into Cooper Slough remain similar to existing conditions during higher frequency
runoff events such as the 2- through 10-year events.
The memorandum goes on to discuss the impacts of the Future Selected Plan Improvements upstream
of the development and how these improvements could reduce the required volumes of the proposed
Montava Development Master Plan. Specifically, the North Poudre Reservoir No. 6 Spillway and the Sod
Farm Pond Detention improvements. Additionally, the memorandum discusses the implementation of
the No. 8 Ditch flow restriction during storm events, which was found to have minimal impacts on
required detention volumes. But, regardless, restricting the irrigation flows in the No. 8 Ditch during
flood events would be good practice and should be pursued. Should, it be feasible, a similar
management approach along the L&W Canal could also be considered. The removal of irrigation flows
from the L&W Canal during storm events, would have a near direct benefit to the reduction in spills out
of the canal.
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6.3 Development Master Plan
6.3.1 Montava Property – Developed Condition Hydrology
On-site basin delineations have been updated based on the most current development master plan and
incorporated into the 2014 Existing Conditions SWMM model provided by ICON. Again, sub-basin
properties remain similar. East of the No. 8 Ditch, storm runoff collection and conveyance systems will
include street section curb and gutter and inlets connected to closed conduit storm sewer, which will
daylight to open grass lined channels through the property and discharge into proposed Cooper Slough
channel improvements along the east property boundary. Storm infrastructure east of the No. 8 Ditch
will provide conveyance for fully developed 100-year runoff, with on-line regional detention being
provided along the Cooper Slough improvement corridor prior to discharging to the L&W Canal and the
Waterglen Subdivision. West of the No. 8 Ditch, development will provide on-site detention to reduce
on-site 100-year developed runoff to pre-developed 2-year rates. Existing and proposed development
west of the No. 8 Ditch will discharge directly into the No. 8 Ditch, with resulting release rates below
existing conditions. Development west of the No. 8 Ditch makes up approximately 15% of the project
and is anticipated to be the first phase of improvements.
6.3.2 No. 8 Outlet Ditch Diversion at Sod Farm
As discussed, the No. 8 Ditch side spill to the Sod Farm will not be formalized as part of the
development. Martin/Martin has verified the 2014 Existing Conditions model diversion rating, which
yields 617 cfs to the Sod Farm, with 384 cfs remaining in the No. 8 Ditch. The resulting stored volume in
the Sod Farm depressing is approximately 112 ac-ft, being 100% retained.
6.3.3 No. 8 Outlet Ditch Diversion to Montava
The master planned diversion from the No. 8 Ditch to The Development has been shifted north to Maple
Hill Dr. The relocation of the diversion allows discharge to Montava to enter proposed grass lined
Channel No. 2 to be conveyed through The Development to the proposed Cooper Slough improvement
corridor. Note that the ICON memorandum suggests that the location of the diversion be modified more
consistent with the master plan, or that the developer demonstrate the ditch’s abilities to convey the
additional flows to the L&W Canal, and that the flows be managed in this manner successfully. The
proposed improvements to the No. 8 Ditch have been sized to convey the 125 cfs downstream of the
diversion plus the Maple Hill Subdivision outfall, the OS-1 passthrough, and the Montava historic 2-year
discharges. The existing flow in the No. 8 Ditch downstream of Montava is approximately 512 cfs, with a
proposed discharge of 249 cfs.
6.3.4 Montava In-Line Regional Pond A
Regional Pond A is being proposed at the northeastern most corner of the property, where Cooper
Slough enters The Development. The detention facility will be implemented to control flow through the
Cooper Slough conveyance improvements corridor, as well as to take some of the burden off Ponds 425
and 426. Approximately 1,807 cfs enters The Development at Pond A during a 100-year event and
releases approximately 1,042 cfs with a resulting maximum stored volume of approximately 123 ac-ft.
Pond A will discharge to the downstream Cooper Slough channel improvements through an at-grade
weir.
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6.3.5 C&S Railroad Diversion
The Cooper Slough drainageway through Montava will be improved to convey the resulting on- and off-
site 100-year discharges along the easterly property boundary of The Development. Again, the Cooper
Slough drainageway improvements will accept developed 100-year discharges from Montava. Additional
capacity will be implemented, which will eliminate the existing C&S Railroad diversion to Anheuser
Busch. The proposed channel will include a low-flow and bank full section with floodplain terraces to
mimic natural channel conditions along the corridor. The channelization approach will be to create an
amenity for the future community that benefits users as well as the surrounding properties.
6.3.6 AB Pond No. 425
A hydraulic connection is being proposed between Ponds 425 and 426 to create attenuation facilities in
series that can utilize the existing 425 spillway into the L&W Canal, as well as to take advantage of the
existing formalized overflow spillway from the L&W Canal to Cooper Slough through the Waterglen
Subdivision. To achieve the required minor and major release rates into the L&W and Cooper Slough
drainageways, Pond 425 will require improvements to the existing berm adjacent to the L&W Canal to
allow for a resulting maximum stored volume of approximately 47 ac-ft during the 100-year event. The
approximate inflow to Pond 425 is 883 cfs, with an attenuated discharge of 819 cfs. Of the 819 cfs, 384
discharges to the L&W Canal and 435 cfs will be diverted to Cooper Slough through the Waterglen
Subdivision.
6.3.7 C&S/ Crumb Pond No. 426
Per the 2017 master plan, Pond 426 will be improved to provide regional detention for the existing
offsite Cooper Slough watershed, as well as fully developed 100-year runoff from Montava. The Pond
will attenuate tributary runoff to the allowable release rates identified in the 2017 master plan. To
achieve this, Pond 426 will work together in conjunction with Pond 425 and an overflow pond south of
the existing east/west utility corridor. An overflow weir set approximately 3-feet above the bottom of
Pond 426 will allow backwater to discharge to the overflow pond, while not impacting the existing
Anheuser Busch water main. The overflow pond will have an invert elevation below Pond 426, which will
be constructed with a culvert connection to the L&W Canal to allow the pond to drain within 72 hours.
The Pond 426 outfall connection to Pond 425 will consist of a staged configuration consisting of a 36-
inch culvert placed at the invert of the pond with dual 3’(H) x 8’(W) CBC’s located approximately 3-feet
above. A siphon configuration may be required depending on the depths of the existing AB water and
sanitary main. The approximate inflow to Pond 426 is 1,322 cfs, with an attenuated discharge of 760 cfs.
Of the 760 cfs, 167 cfs discharges to the overflow pond and 593 cfs discharges to Pond 425. The
maximum volume stored is approximately 307 ac-ft. The attenuated release from the overflow pond is
approximately 138 cfs, with a maximum volume stored of approximately 59 ac-ft.
6.3.8 C&S/Crumb Detention Basin No. 429
As a condition of the development, the Anheuser Busch property is proposed to provide detention for
developed Basin 29 to attenuate runoff to pre-developed peak 100-year discharges. AB Pond 429, with a
100-year inflow of 1,000 cfs and a historic 100-year release rate of 390 cfs, will require approximately 14
ac-ft of storage. The pond will alleviate storage capacity needs for AB Pond 425.
P a g e 13 | 18
6.3.9 Development Master Plan vs Existing Discharges
The following table outlines the comparison between The Development and existing conditions
discharge at the No. 8 Ditch, L&W Canal, and Cooper Slough drainageway at the Waterglen Subdivision.
Table 2: Discharge Comparison
Location Design Point
100-Year Release (cfs)
Existing Proposed
No. 8 Ditch D/S of Montava 822 512 249
L&W Canal 907 565 385
Cooper Slough @ Waterglen 909 734 729
Overall, the projects associated with the proposed development are providing 586 ac-ft of detention
storage. In comparison, the Selected Plan proposes 449 ac-ft through regional and on-site detention.
6.4 Stormwater, Light Imprint Design, Water Quality Treatment & Low Impact Development
6.4.1 Light Imprint Design
Light imprint (LI) is a design methodology developed to complement new urbanist (NU) and traditional
neighborhood design (TND) designs. It was developed to make TND designs more environmentally
friendly, but not at the expense of aesthetics. LI design treat stormwater whilst at the same time
promoting walkability, compact development, connectivity and mixed-use applications which are key
components to NU and TND.
Light Imprint’s fundamental principal is to respect the sites terrain. Existing swales and drainageways
should remain as well as existing hills. From an engineering point of view this makes common sense,
where urban design and site planning is guided and respects the natural terrain of the existing site.
Furthermore, LI designs recognized the importance of civic spaces and connectivity with developing new
communities.
The Light Imprint Handbook, version 1.3 by DPZ Charlotte was used as the reference for LI. LI tools for
treating stormwater. The tools are categorized by paving, channelizing, storage and infiltration
groupings. A key goal for LI treatments is to be aesthetically pleasing and complementary to new
urbanist and TND planning. Each LI treatment’s benefit to stormwater treatment is qualitative in nature
and is difficult to calculate and quantify the benefit. For this reason, LI is used in the initial site planning
stage and final designs and detailing at the construction document level will incorporate LID elements
that can be quantified to City of Fort Collins stormwater criteria requirements.
6.4.2 Stormwater Water Quality Treatment
As a conservative measure at the preliminary master planning stage and to allow for the most flexibility
with each phase of development, space has been allocated within each onsite drainage basin to
accommodate a water quality pond sized to treat 50% of the required water quality capture volume
(WQCV). In doing so, it allows the future phases to develop in accordance with the City of Fort Collins
LID Option 1 or LID Option 2 as described in more detail later.
P a g e 14 | 18
Some of the onsite ponds have additional storage for 100-year detention to minimize downstream
culvert and channel sizes.
Designing, constructing and landscaping the onsite ponds to be functional, maintainable, beautiful and
in keeping with their surroundings are goals of the design team.
The City of Fort Collins Landscape Design Standards and Guidelines for Stormwater Detention Facilities
will be used for final pond designs. The onsite ponds on the east side of the project near or adjacent to
the regional ponds will have a natural character and structure to complement the City of Fort Collins
Natural Area’s vision. As you move to the west, the onsite ponds will begin to take on more architectural
character to relate to the more formal suburban and urban areas. The City of Fort Collins Natural Area’s
concept package for the regional ponds along the east edge of Montava are included for reference at
the end of this appendix.
The following characteristics will be incorporated into the onsite pond designs:
• Variation in landform and pond side slopes,
• Meandering drainage channel,
• Naturalized soft pond bottom to encourage infiltration,
• Undulating bottom, and
• Use of native and adapted plants.
The project Geotechnical Report states that there is predominately 5-6 feet of clay soils on top of Type B
soil. When the channels and ponds are excavated, the Type B soil will be the top layer which will support
infiltration and pond designs without excessive concrete trickle channels or underdrain pipe systems.
Where appropriate and complementary to the adjacent land use, ponds will be designed as multi-use
basins incorporating passive recreation, trails and or sports fields.
P a g e 15 | 18
Table 3– Onsite Water Quality Pond Summary
Basin
Area
(AC)
Imperviousness
(%)
WQCV
depth
WQCV
(AF)
1/2 WQCV
(AF)
100YR SWMM
DET VOL (AF)
TOTAL
POND
VOL
(AF)*
B 16.7 50% 0.206 0.34 0.17 4 4.17
C1 26.9 50% 0.206 0.55 0.28 6 6.28
C2 81.8 50% 0.206 1.69 0.84 0 0.84
H 45.5 10% 0.067 0.31 0.15 0 0.15
J1 20.4 50% 0.206 0.42 0.21 0 0.21
J2 22.2 50% 0.206 0.46 0.23 0 0.23
J3 44.5 50% 0.206 0.92 0.46 0 0.46
A1 10.3 80% 0.328 0.34 0.17 3 3.17
A2 13.4 80% 0.328 0.44 0.22 4 4.22
D 48.5 60% 0.236 1.15 0.57 10 10.57
E 81.3 35% 0.166 1.35 0.68 3 3.68
F 46.9 60% 0.236 1.11 0.55 10 10.55
G1 79.0 80% 0.328 2.60 1.30 0 1.30
G2 9.5 80% 0.328 0.31 0.16 0 0.16
K1 22.6 60% 0.236 0.53 0.27 0 0.27
K2 57.9 60% 0.236 1.37 0.68 0 0.68
L 108.0 60% 0.236 2.55 1.28 0 1.28
N 81.0 80% 0.328 2.66 1.33 0 1.33
*Note: For flexibility with each phase of development, the onsite water quality ponds have been master planned to allow for a
pond sized to 1/2xWQCV for each drainage basin.
6.4.3 Low Impact Development and Fort Collins Criteria
According to the Fort Collins Stormwater Criteria Manual, implementation of LID systems into the
drainage design is required for all development and must meet one of the following options:
LID Compliance Option 1:
50% site treated with “standard” water quality +
50% of the newly added or modified impervious area must be treated by LID techniques (and
25% of new paved vehicle use areas must be pervious)
= 100% of Site treated
LID Compliance Option 2:
50% site treated with “standard” water quality +
75% of all newly added or modified impervious area must be treated by LID techniques.
= 100% of Site treated
The approach with the Montava PUD master plan is to provide space allocation for half of the required
water quality capture volume (WQCV) of the entire development in water quality ponds dispersed
throughout the neighborhoods and provide LID treatment in the drainage conveyance channels used to
convey stormwater from the development sites to the Water Quality Ponds. The remaining WQCV will
be provided via on-site LID elements.
P a g e 16 | 18
There are seven options listed in the Criteria that are acceptable LID treatment methods including:
1. Permeable pavement;
2. Bioretention;
3. Sand filters;
4. Linear bioretention;
5. Underground filtration;
6. Vegetated buffers, and
7. Constructed wetland channels/ponds.
Each phase of Montava will utilize one or more of these seven treatment options that are best suited for
the developed area.
6.4.4 Concept of Disconnected Impervious Area (DCIA)
As each development site is designed; the design team will look for opportunities to keep runoff from
new impervious areas disconnected and dispersed. The site will be purposely broken up into multiple
discharge points in order to disconnect impervious areas which lengthens runoff time of concentration
and allows for multiple localized areas for water quality treatment. Ultimately runoff will be reduced,
infiltration increased, and storm sewer minimized.
6.4.5 Stormwater and the Concept of Treatment Train
The concept of treatment train for stormwater relates to the treatment of stormwater at multiple stages
from the upstream end where runoff first occurs; to conveyance, where the stormwater is conveyed
from the site to the downstream end of the treatment train where the stormwater is treated in a water
quality pond.
The treatment train concept provides redundancy in stormwater treatment as there are multiple
treatment elements or systems in series. For the Montava project the first and most upstream “car” in
the treatment train is the onsite LID treatments. The second “car” in the treatment train is the
treatment of stormwater in the open conveyance elements from the sites to the water quality ponds.
These elements may be LID wetland channels or linear bioretention features. The final and most
downstream “car” in the treatment train is the water quality pond dispersed through the neighborhoods
at the downstream end of each drainage basin.
P a g e 17 | 18
6.4.6 Quantifying Stormwater Quality and Low Impact Development Goals are met
To quantify the water quality and LID goals are met it is proposed to quantify the benefit of each
stormwater treatment element in terms of water quality capture volume (WQCV) treated.
Example WQCV / LID Calculation
For an example and using Table F-1 presented previously as a reference tool. Basin F is located in the
center of the Montava development and will be one of the first phases to develop. Basin F is 46.9 acres
and is estimated to develop to and imperviousness of 60%.
LID Compliance Option 1
The total water quality capture volume that must be treated for Basin F is 1.11 acre-feet. If at the time
of final design, it is decided Option 1 of the LID regulations will be used for compliance (i.e. porous paver
will be used to treat 25% of new paved areas), Pond F will be sized to treat 0.55 acre-feet of WQCV.
That leaves 0.55 acre-feet of WQCV to be treat by onsite LID elements (including porous pavers) and
conveyance LID elements used to convey the stormwater from the individual sites to Pond F.
Assuming Channel 3 is used to collect and convey stormwater in Basin F and assuming Channel 3 is
constructed as a linear bioretention channel. The WQCV treated is calculated as 1’ of water depth across
the assumed 5’ channel width of the channel by 1,000lf of channel length in Basin F. The treated WQCV
is 0.11 acre-feet.
That leaves 0.44 acre-feet of WQCV to be treated by LID elements on the individual sites and must
include porous pavers treating 25% of new paved areas.
P a g e 18 | 18
LID Compliance Option 2
The total water quality capture volume that must be treated for Basin F is 1.11 acre-feet. If at the time
of final design, it is decided Option 2 of the LID regulations will be used for compliance (i.e. 25% WQCV
treatment in Pond F and 75% LID treatment, but does not need to include porous pavers), Pond F will be
sized to treat 0.28 acre-feet of WQCV.
That leaves 0.83 acre-feet of WQCV to be treat by onsite LID elements and conveyance LID elements
used to convey the stormwater from the individual sites to Pond F.
Assuming Channel 3 is used to collect and convey stormwater in Basin F and assuming Channel 3 is
constructed as a linear bioretention channel. The WQCV treated is calculated as 1’ of water depth across
the assumed 5’ channel width of the channel by 1,000lf of channel length in Basin F. The treated WQCV
is 0.11 acre-feet.
That leaves 0.72 acre-feet of WQCV to be treated by LID elements on the individual sites and does not
require porous pavers be installed.
SECTION 7 - CONCLUSION
7.1 Master Plan Conformance
The drainage master plan for the Montava development has been prepared in accordance with the
Cooper Slough Alternatives Analysis, prepared by ICON Engineering, Inc., October 2017. The proposed
stormwater conveyance and flood control infrastructure concept has been closely coordinated with
both the City of Fort Collins and ICON. The master plan objective is to provide a comprehensive
stormwater management approach to accommodate the proposed development while not adversely
impacting adjacent or downstream properties. The proposed infrastructure will provide local and
regional benefits within the City of Fort Collins from both a stormwater quantity and quality perspective.
7.2 Criteria Compliance
In addition to compliance with the drainageway masterplan, the Montava Development drainage master
plan has been prepared in accordance with the Fort Collins Stormwater Criteria Manual, November
2017. Again, the proposed stormwater infrastructure concept has been closely coordinated with the City
of Fort Collins and adheres to the principals and policies set forth by the jurisdiction. The proposed
development will promote the health, safety, welfare, and property of the City of Fort Collins and
citizens through the proper control and treatment of stormwater.
REFERENCES
1. “Cooper Slough, Boxelder Creek Master Drainageway Planning Study”; SLA, August 1981;
2. “Hydrology Report, Anheuser Busch Company, Inc.”; Ayres Associates, January 2000;
3. “Technical Documentation for the Hydrologic Modeling of the Boxelder Creek/ Cooper Slough
Basin”; Anderson Consulting Engineers, Inc., January 2002;
4. “Technical Documentation for the Alternatives Feasibility Analysis of the Boxelder Creek/
Cooper Slough Basin”; Anderson Consulting Engineers, Inc., December 2002;
5. “Selected Plan of Improvements for the Boxelder Creek/ Cooper Slough Basin”; Anderson
Consulting Engineers, Inc., April 2004;
6. “Upper Cooper Slough Basin Selected Plan of Improvements”; Anderson Consulting Engineers,
Inc., June 2006;
7. “Box Elder Creek / Cooper Slough Hydrology Update”; ICON Engineering, Inc., April 2014;
8. “Conditional Letter of Map Revision (CLOMR) for East Side Detention Facility (ESDF), Larimer &
Weld Canal Crossing Structure (LWCCS), Opening Of I-25 Boxes, Siphon Of Lake Canal, Prospect
Road Bridge Replacement, Boxelder Creek Overflow. Also Known As (Boxelder 6)”; Ayres
Associates, February 2015.
9. “City of Fort Collins Cooper Slough Alternatives Analysis Update”, ICON Engineering, Inc.,
October 2017.
10. “Impacts from Montava Development to Cooper Slough [Draft Memo]”, ICON Engineering, Inc.,
September 13, 2018.
APPENDIX A
SUPPORTING DOCUMENTS
MONTAVA
Utilities
electric · stormwater · wastewater · water
700 Wood Street
PO Box 580
Fort Collins, CO 80522
970.221.6700
970.221.6619 – fax
970.224.6003 – TDD
utilities@fcgov.com
fcgov.com/utilities
April 25, 2018
HF2M Colorado
Max Moss
430 North College Avenue, Suite 410
Fort Collins, CO 80524
RE: Montava Stormwater Communications Summary
Dear Mr. Moss,
I am new to the position as Water Engineering and Field Services Operations Manager and want
to take this opportunity to present a summary of communications regarding the stormwater
system at the Montava Development. This letter is an attempt to document the information,
guidance and coordination that has occurred between HF2M (representing the Montava
development) and the City of Fort Collins Utilities (City) regarding stormwater to date. This
letter has been prepared to recapture and summarize some of the previously-provided comments
from the Conceptual Review process and from various other email exchanges and meetings.
This letter is not intended as a separate formal review document and does not constitute formal
review comments from the City’s Development review and Stormwater Master Planning staff,
and is intended to increase efficiency of Montava’s formal review process.
The City understands the Montava project to be located on several parcels of land west and south
of the Anheuser-Busch, InBev facility. The parcels make up approximately 850 acres and will
comprise of a master planned community that includes single family and multi-family
residenceial, commercial areas, a school parcel and open spaces threaded throughout. The land
uses and site planning are still underway by the development team. The entire development is
located with the Upper Cooper Slough Master Drainage Basin.
Master Planning Efforts and Regional Stormwater Requirements
1. Master Plan: Anderson Consulting Engineers prepared the “Upper Cooper Slough
Selected Plan of Improvements” in 2006. This plan was recently updated by ICON
Engineers in 2017 and is still in draft form awaiting potential modifications to
accommodate the Montava Development.
DocuSign Envelope ID: 9CBD9275-509D-42CE-9AC6-97B319997DCA
2 | P a g e
2. Detention Configuration: The City currently has ICON under contract to evaluate various
detention alternatives for moving the CS&R Crumb pond to an upstream location and
still meet the 100-year target discharge through the Waterglen Subdivision that was
discussed in the Upper Cooper Slough Master Plan. In addition, the City understands that
the developer is still looking at various land use configurations that may include moving
the future school site to another location further south in the development. Therefore, the
City will want to ensure that land use configurations include an understanding of existing
conditions (i.e. existing flow paths and inadvertent detention) for all stakeholders.
3. Upstream: The Montava development will be required to safely convey all existing flows
up to and including the 100-year runoff through the site from all upstream offsite areas.
These flow rates have been quantified in the updated master plan prepared by ICON and
provided to HF2M in the Cooper Slough Selected Plan (2017) Existing Conditions Flow
exhibit (attached for reference). These upstream offsite flows will be required to be
properly conveyed through and around the Montava site in a manner that meets the
master planning goals and that meets City criteria for stormwater conveyance and
infrastructure.
As an alternative, HF2M can work with upstream land owners and developers to build
the master plan improvements (e.g., Sod Farm pond) to reduce peak flows through the
Montava development. It should be noted that building an embankment in this area may
create a levee, in which case FEMA criteria would need to be met.
4. Downstream: The Montava development will be required to evaluate impacts to the
downstream properties and infrastructure so that it does not adversely impact these
existing facilities such as the existing culverts under Mulberry Street and further
downstream into the Lake Canal. Stormwater runoff from the project cannot show an
increase in risk in terms of discharge or frequency for the range of flood frequencies from
the 2-year to the 100-year event. Currently, City staff have not received draft plans that
address this and will require downstream design analysis before final approval. This topic
may require further discussion between the City and the development team.
Floodplain Impacts
The City does not have a mapped floodplain for the area north of the Larimer and Weld
Canal, but wants to ensure that HF2M is aware that even without official floodplain
mapping, there is flooding potential (as can be seen on the floodplain maps south of the
Larimer and Weld Canal) along the Upper Cooper Slough through the Montava site.
Although the floodplain is not mapped in this area, the design team will need to provide a
comparison of 100-year flood elevations to the ground elevations for any potential
floodplain storage.
DocuSign Envelope ID: 9CBD9275-509D-42CE-9AC6-97B319997DCA
3 | P a g e
Overall Onsite Stormwater Requirements
1. The standard stormwater detention requirement includes onsite stormwater detention and
is required for the runoff volume difference between the 100-year onsite developed
inflow rate and the 2-year historic release rate. Detention requirements for onsite
development may be met in the same space or footprint of the regional detention
requirements if adequate space is provided for both. The details of any detention
configuration will need to be reviewed and approved by stormwater master planning and
development review staff.
2. Modified stormwater detention may be required for release into the No. 8 Ditch. HF2M
will be responsible for contacting representatives from the No. 8 Ditch and completing an
agreement that includes release rates with the ditch company. The City will ultimately
seek No. 8 Ditch company approval on the plans prior to approval and drainage report.
3. Standard water quality and LID systems will be required for this development, as
stipulated in the Conceptual Review comments dated December 20, 2017.
4. Complete drainage analysis and construction drawings will be required to be designed by
a Professional Engineer registered in Colorado, as stipulated in the Conceptual Review
comments dated December 20, 2017.
Stormwater Fees
There are two components to the stormwater development fees:
1) The plant investment fee (PIF) is $8,217/acre of new impervious area over 350
square feet of the total platted area. The expected impervious area is multiplied by
this rate.
2) The review fee is $1,045/acre multiplied by the rate factor (based on new
impervious area) multiplied by the total platted area. (Please note that the
comment regarding fees provided at Conceptual Review was stated incorrectly for
the “review fee” portion. The way this fee is regulated and collected by the City is
based upon a rate factor based on the designed impervious percentage of the
project area and not the overall project area.)
Revenues from these fees are used by the City for capital costs of community Stormwater
improvements (PIF) and direct costs of the City to review, comment and approve formal
plans (review fee).
DocuSign Envelope ID: 9CBD9275-509D-42CE-9AC6-97B319997DCA
4 | P a g e
Large development sites such as Montava, it is not uncommon for the site to develop in
phases - platting, subdividing and building on portions of the overall development at a
time, while reserving large tracts of land for future platting and building. In this case,
those portions are platted and would be required to pay the stormwater fees prior to the
first building permit being issued within the platted area. An example of calculating fees
is below:
Example: 40-acre platted site with various imperviousness. Calculated fees will vary based on
actual % imperviousness and site acreage being platted.
Imperviousness
Rate
Factor Acres PIF Review Fee
Total
Stormwater Fee
30% 0.25 40 $98,604 $10,450 $109,054
50% 0.40 40 $164,340 $16,720 $181,060
60% 0.60 40 $197,208 $25,080 $222,288
Please note, monthly stormwater service fees will be due for each building starting when
the building permit is issued.
Developer / City Participation
City Participation/Contribution: The City recognizes that there may be certain
improvements that need to be completed due to the risks and existing runoff. However,
the overall selected plan of improvements that address the existing and proposed
conditions for the master drainage basin will need to be prioritized against other projects
across the City. The City anticipates that cost sharing discussions will need to take place
with HF2M and that the City’s level of contribution to the improvements will need to be
negotiated based on other City-wide priorities.
Water and Sewer Infrastructure
As the Montava development is within the ELCO Water and Boxelder Sanitation
Districts, Utilities Development Review staff are not involved with specific review of
onsite requirements at this time.
Should you have any questions or to discuss this further, please feel free to contact me by email
tconnor@fcgov.com or by phone 970-221-6671.
Sincerely,
Theresa A. Connor, P.E.
Water Engineering and Field Services Operations Manager
DocuSign Envelope ID: 9CBD9275-509D-42CE-9AC6-97B319997DCA
5 | P a g e
Attachments:
Exhibit - Cooper Slough Selected Plan (2017) Existing Conditions Flow
Cc:
Kevin Gertig, Director of Utilities
Laurie Kadrich, Director of Planning, Development and Transportation
Ken Sampley, P.E., Stormwater Engineering and Development Review Manager
Matt Fater, Water Engineering Field Operations Manager, Interim
Dan Evans, Stormwater Master Planning
Heather McDowell, Utilities Development Review
Shane Boyle, Utilities Development Review
Lucas Mouttet, Customer Accounts Manager
Philip Tucker, Key Accounts Representative
Lance Smith, Utilities Finance Director
DocuSign Envelope ID: 9CBD9275-509D-42CE-9AC6-97B319997DCA
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APPENDIX B
RELEVANT PORTIONS OF 2017 COOPER SLOUGH ALTERNATIVES ANALYSIS
CITY OF FORT COLLINS
COOPER SLOUGH
ALTERNATIVES ANALYSIS UPDATE
October 2017
Prepared for:
Department of Utilities
700 Wood Street
Fort Collins, CO 80522
(970) 221-6589
Prepared by:
7000 S. Yosemite Street, Suite 120
Centennial CO 80112
(303) 221-0802
www.iconeng.com
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Larimer & Weld Canal
No. 8 Outlet Ditch
Sod Farm Pond
COOPER SLOUGH WATERSHED
BOXELDER WATERSHED
INTERSTATE HWY 25
COOPER SLOUGH
Larimer & Weld Canal
No. 8 Outlet Ditch
Land Use Revised AB for Property Future Conditions Boundary
Only Inside of AB Area.
Sod Farm Pond
COOPER SLOUGH WATERSHED
BOXELDER WATERSHED
INTERSTATE HWY 25
C&S/ Crumb Pond
AB Pond 425
Note: AB areas were updated for
future land use (imperviousness).
All other areas remained Existing
Condition land use.
C&S Railroad
ANHEUSER BUSCH (AB)
PLANT
CR 48
CR 50
CR 52
*!SB38
290.AC 6 5%
*!SB29
268.AC 8 67%
*!SB36
317.AC 8 6%
*!SB35
307.AC 3 6%
*!SB32
213.AC 3 80%
*!SB31
184.AC 5 86%
*!SB13
197.AC 1 8%
*!SB102
308.AC 0 5%
*!SB25
129.AC 1 58%
*!SB34
128.AC 5 90%
*!SB18
115.AC 5 5% *!SB26
112.AC 1 80%
*!SB106
344.AC 9 5%
*!SB11
147.AC 3 6%
*!SB19
82.AC 0 5%
*!SB97
109.AC 8 5%
*!SB28
125.AC 9 9%
*!SB40
110.AC 7 53%
*!SB15.4
62.AC 4 35.8%
*!SB20
161.AC 5 20%
2016 Cooper Slough Alternatives Update ‐ ICON Engineering
Landuse Values (Imperviousness) for AB Areas
Area
(ac) Historic Ex. Condition Future (2006 Master Plan) Future (MV Subarea Plan)
1
SB201 Employment 14.8 5% 5% 80% 80%
SB22 Park 10.6 5% 5% 5% 10%
SB25 Employment
2
129.1 5% 5% 70% 80%
SB26 Employment 112.1 5% 5% 50% 80%
SB26_B Park 40.4 5% 5% 10%
SB27 Park 58.4 5% 5% 52% 10%
SB27_B Employment 14.4 5% 5% 80%
SB29 75% Indust./ 25% Empl.
2
268.8 5% 29% 80% 88%
SB30 Industrial
2
33.5 5% 49% 80% 90%
SB31 60% Indust. / 40% Empl 184.5 5% 7% 82% 86%
SB32 Employment 213.3 5% 6% 55% 80%
SB34 Industrial 128.5 5% 9% 82% 90%
1
The 2016 Alt. Analysis % Imp. is based on the Mountain Vista Subarea Plan Land Use
Land Use Imperviousness AB Subbasin Revised % Impervious
Industrial 90% SB25 58%
Employment 80% SB29 67%
Park 10% SB30 75%
From Fort Collins Amendments to the 2007 UDFCD Drainage Manual, Table RO‐14
Other Subasins Revised ‐ Outside of AB Areas
SB17 Park (Detention) 36.5 5% 10%
SB17_B Undeveloped (outside AB) 28.3 5% 5%
Revised AB‐East Subbasins
2
2
AB Areas east of the CSRR drain to the AB Pond 425. Future impervious
values for these basins were revised to reduce the AB-425 Pond outflow
rates to the 2006 Master Plan values
% Impervious
Subbasin Land Use (MV Sub Area Plan)
2016 Cooper Slough Alternatives Update ‐ ICON Engineering
AB Areas ‐ Conceptual Detention Basins ‐ Target Parameters
Area
(ac) Historic (2yr) Future (100yr) Future 100 -> 2-yr Pond Outlet Ex. Cond. (2yr) Future (100yr)
SB201 Employment 14.8 2.2 141.1 3.0 0.06 4.08
SB22 Park 10.6 1.6 37.6 Park ‐ No Pond 0.06 1.96 No conceptual ponds on the parks subbasins per City
SB25 Employment
2
129.1 18.3 668.6 Goes to AB 425 Pond 0.49 30.32 East of RR tracks, trib to AB Pond 425. 100-yr controls at pond 425
SB26 Employment 112.1 16.3 926.7 16.8 0.46 30.81
SB26_B Park 40.4 5.7 55.1 Park ‐ No Pond 0.15 4.36 No conceptual ponds on the parks subbasins per City
SB27 Park 58.4 8.5 139.4 Park ‐ No Pond 0.25 9.85 No conceptual ponds on the parks subbasins per City
SB27_B Employment 14.4 2.1 113.5 3.0 0.06 3.84
SB29 75% Indust./ 25% Empl.
2
268.8 38.7 1786.2 Goes to AB 425 Pond 1.07 68.62 East of RR tracks, trib to AB Pond 425. 100-yr controls at pond 425
SB30 Industrial
2
33.5 4.9 294.8 Goes to AB 425 Pond 0.15 9.05 East of RR tracks, trib to AB Pond 425. 100-yr controls at pond 425
SB31 60% Indust. / 40% Empl 184.5 26.6 1437.8 26.4 0.74 51.96
SB32 Employment 213.3 30.6 1508.5 30.7 0.83 58.28
SB34 Industrial 128.5 18.4 946.9 18.8 0.49 36.77
Notes
Subbasin Discharge (cfs) Subbasin Flow Volume (AF)
Subbasin Land Use (MV Sub Area Plan)
INTERSTATE HWY 25
C&S/ Crumb Pond
AB Pond 425
ANHEUSER PLANT BUSCH (AB)
Sod DiveFrsairomn
COOPER SLOUGH
SB29
67%
SB32 80%
SB31 86%
SB36 6%
SB35 6%
SB38 5%
SB25 58%
SB34 90%
SB18 5%
SB26 80%
SB27 10%
SB102 5%
SB15.35.8% 4
SB17 10%
SB70 30%
SB30 75%
SB37 23%
SB200 5%
SB26_10% B
SB19 5%
SB97 5%
SB21 5%
SB106 5%
SB61 30%
SB99 5%
SB17_5% B
SB15.44.5% 3
SB67 37%
SB28 9%
SB72 5%
SB20 20%
SB201 80%
SB62 22%
SB63 24%
SB22 10%
SB23 5%
SB33.53% 3
SB68 31%
SB27_80% B
SB33.58% 2
SB15.30% 1
SB66 43%
SB40 53%
SB69 43%
SB16 7%
Cooper Mountain Slough Vista Subarea Alternatives Plan Comparison Analysis with (2016) Subbasins
0 80F0eet $
Legend
Anheuser Busch Property
Cooper Slough
SWMM Subbasin (% Impervious)
Legend from Mountain Vista Subarea Plan
This theand hydrology figure presents model subbasins the 2009 Mountain for the Alternatives Vista Subarea Analysis. Plan Framework Map
E. VINE DR
I-25
Prop. CS & Crumb Regional Detention Basin
S = 230 AF (Total); 220 AF (100yr)
D = 12.5' Depth.
Invert = 4968.5
100 yr WSE = 4980.7
Spillway Elev= 4981
Excavated Below Existing Grades.
Q100 (Pr.) = 180 cfs
Outlet Pipe Bypass Larimer & Weld Canal
Q100 = 548 cfs
Prop. Pond Outlet Pipe
2 - 8'x3' RCBC
1513 LF
Spillway Set by Existing Ridge.
Elev = 4981
Q100 = 0 cfs (Spillway)
Spillway Flows Discharge to L&W Canal
Top of Bank Elev 4983
Colo. & Southern RR
Elev. 4984
Colo. & Southern RR
Elev. 4988
COOPER SLOUGH
Larimer & Weld Canal
1.2%
1%
Q100 (Pr.) = 1527 cfs
Proposed Proposed Flow C&Patterns S & Crumb Exhibit Regional Stormwater Detention
0 80F0eet $
Legend
Pr. CS & Crumb Detention Basin
Pr. Detention Outlet Pipe
Irrigation Canal
Ex. Canal Spill Location
Ex. Flow Path (Routing Elements)
Ex.Subbasin Topo Drainage
2'
10'
"
"
"
" "
"
"
"
"
"
"
E. VINE DR
I-25
Existing Detention (Inadvertent)
240 AF
100 yr WSE = 4989.4
Q100 (Ex.) = 49 cfs
Outflows Spill Over CSRR Tracks
Into L&W Canal
Q100 = 661 cfs
Existing Ridge. Elev = 4981
L&W Canal Bank Elev 4983
Colo. & Southern RR
Elev. 4984
Colo. & Southern RR
Elev. 4988
COOPER SLOUGH
Larimer & Weld Canal
Existing Spill From L&W Canal
Into Cooper Slough
Existing High Point. Elev = 4991
Prevents Flows From Continuing SW
Existing Sump
Q100 (Ex.) = 1381 cfs
Existing Proposed Flow C&Patterns S & Crumb Exhibit Regional Stormwater Detention
0 740Feet $
Legend
Exist. Overflow Path
Ex. Flow Path
" Ex. Detention
Drainage Subbasin
Irrigation Canal
Ex.Location Topo Ex. Canal Spill
1'
5'
COOPER SLOUGH
NORTH
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7000 S. Yosemite Street I Suite 120 I Centennial CO 80112
Phone (303) 221-0802 / Fax (303) 221-4019
ENGINEERING, ICON INC.
WWW.ICONENG.COM
300'
HORIZ. SCALE: 1" = 300'
0 150'
Alignment - PP Outfall Pipe PROFILE
HORIZ. SCALE: 1" = 150'
VERT. SCALE: 1" = 15'
4955
4960
4965
4970
4975
4980
4985
4990
4995
0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50 4+00 4+50 5+00 5+50 6+00 6+50 7+00 7+50 8+00 8+50 9+00 9+50 10+00 10+50 11+00 11+50 12+00 12+50 13+00 13+50 14+00 14+50 15+00 15+50 16+00 16+50
17+00 17+50 18+00 18+50 19+00 19+50 20+00 20+50 21+00 21+50 22+00 22+50 23+00
EG=4962.0
FG=
0+50
EG=4962.6
FG=
1+00
EG=4962.9
FG=
1+50
EG=4963.0
FG=
2+00
EG=4965.7
FG=
2+50
EG=4965.9
FG=
3+00
EG=4965.8
FG=
3+50
EG=4966.5
FG=
4+00
EG=4967.1
FG=
4+50
EG=4968.8
FG=
5+00
EG=4971.3
FG=
5+50
EG=4973.0
FG=
6+00
EG=4973.0
FG=
6+50
EG=4974.9
FG=
7+00
EG=4974.4
FG=
7+50
EG=4971.2
Alignment - CS-Crumb Spillway PROFILE
HORIZ. SCALE: 1" = 200'
VERT. SCALE: 1" = 20'
4960
4965
4970
4975
4980
4985
4990
4995
5000
0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50 4+00 4+50 5+00 5+50 6+00 6+50 7+00 7+50 8+00 8+50 9+00 9+50 10+00 10+50 11+00 11+50 12+00 12+50 13+00 13+50 14+00 14+50 15+00 15+50 16+00 16+50
17+00 17+50 18+00 18+50 19+00 19+50 20+00 20+50 21+00 21+50 22+00 22+50 23+00 23+50 24+00 24+50 25+00 25+50 26+26+00 05
EG=4982.0
FG=4969.25
0+50
EG=4981.4
FG=4969.50
1+00
EG=4981.2
FG=4969.75
1+50
EG=4981.7
FG=4970.00
2+00
EG=4984.4
FG=4970.25
2+50
EG=4990.0
FG=4970.50
3+00
EG=4991.2
FG=4970.75
3+50
EG=4991.0
FG=4971.00
4+00
EG=4988.7
FG=4971.26
4+50
EG=4984.2
FG=4971.53
5+00
EG=4979.9
FG=4971.79
5+50
EG=4975.5
FG=4972.00
6+00
EG=4974.6
FG=4972.28
6+50
EG=4975.3
FG=4972.56
7+00
EG=4975.7
FG=4972.84
7+50
EG=4976.2
Alignment - CS_Crumb_SouthEmb_XS PROFILE
HORIZ. SCALE: 1" = 150'
VERT. SCALE: 1" = 15'
4965
4970
4975
4980
4985
4990
4995
5000
0+00 0+50 1+00 1+50 2+00 2+50 3+00 3+50 4+004+18
NORTH
P:\P\16010UCS\Dwg\06_EXHIBITS\UCS_PR_DETENTION-CS&CRUMB_REV1_PROFILE.dwg; Msimpson; Page Setup:----; !CON-HALF-SIZE.ctb; 10/20/2016 4:26 PM
7000 S. Yosemite Street I Suite 120 I Centennial CO 80112
Phone (303) 221-0802 / Fax (303) 221-4019
ENGINEERING, ICON INC.
WWW.ICONENG.COM
150'
HORIZ. SCALE: 1" = 150'
PROFILE 3 0 75'
POND EMBANKMENT SECTION 1
Upper Cooper Slough - Alternatives Hydrology Update - 2016
Larimer & Weld Canal
Spill Locations Summary
APPENDIX C
IMPACTS FROM MONTAVA DEVELOPMENT TO COOPER SLOUGH [DRAFT MEMO]
ICONENGINEERING, INC.
Memorandum
7000 S. Yosemite Street, Suite 120, Centennial, CO 80112
p 303.221.0802 | f 303.221.4019
www.iconeng.com
TO: Dan Evans, City of Fort Collins
FROM: Craig Jacobson, Jaclyn Michaelsen, ICON Engineering, Inc.
DATE: June 27, 2018, Revised September 13, 2018
RE: Impacts from Montava Development to Cooper Slough [Draft Memo]
The purpose of this memo is to summarize the improvements and initial results and
recommendations from the proposed Montava Development Stormwater Improvements,
specifically relating to discharges along Cooper Slough and inflows and spills from the Larimer
and Weld Canal (LWC).
Description of Project:
The Montava development is generally located north of the Larimer and Weld Canal (LWC),
west of the Colorado and Southern Railroad (CSRR), south of Richards Lake Road, and east of
the Number 8 Outlet ditch. There is also a small piece of the development that is located at the
northwest corner of Mountain Vista and Timberline Road, west of the Number 8 Outlet ditch.
The project site is located in and around several Selected Plan improvements for the Cooper
Slough Basin. The development has been required by the City of Fort Collins to incorporate the
following Selected Plan improvements into their development:
1) Remove existing spill at CSRR: The spill currently spills 460-cfs over the railroad and
through the Anheuser Bush (AB) property. By removing this spill 1794-cfs will continue
south through the proposed development.
2) Create a diversion off of the Number 8 Outlet Ditch: The main purpose of the diversion
off the Number 8 Outlet Ditch is to remove the storm flows in the ditch, leaving only the
decreed flow of 125-cfs. The Selected Plan spill was proposed downstream of the last
inflow from surrounding developments.
3) Construction of the Colorado and Southern (C&S)/Crumb Regional detention pond: In
the Selected Plan the regional pond is designed to detain the flow diverted from the
Number 8 Outlet ditch, detain the flow that was previously being spilled over the CSRR,
and to formalize the inadvertent detention at the proposed C&S pond location. The pond
is necessary to maintain the downstream flows at or below existing conditions.
The proposed Montava development incorporated these improvements into the design of their
development. The impact of the proposed design is discussed below. Figure 1 shows the
location of the proposed improvements.
ICONENGINEERING, INC. Page 2 of 8
F:\Icon Projects\Upper Cooper Slough\Montava\Upper Cooper Slough - Montave Draft Memo - updated 9-13-18.docx
Number 8 Outlet Ditch:
The portion of the proposed development located west of the Number 8 Outlet Ditch is currently
proposed to discharge directly into the Number 8 Outlet Ditch. The development discharges at
the pre-developed 2-year release rate. Offsite basins that travel through the site are currently
proposed to pass through the site undetained to the ditch. The total peak flow proposed out of
the development is 191-cfs, this includes the offsite flow that is being routed through the
development.
Compared to the baseline hydrology model, inflows to the Number 8 Outlet Ditch are higher with
the proposed development than under existing conditions. This is primarily attributed to the fact
that the existing conditions hydrology model also identified the presence of inadvertent storage
west of the ditch, thus detaining flows to 116-cfs. We suggest that the City consider
additional compensatory storage to meet development regulation requirements, if
applicable.
Downstream of the development, flows on the Number 8 Outlet Ditch are also increased above
those recommended by the Selected Plan (324-cfs versus 125-cfs). Differences here are that
the proposed development has situated the proposed diversion from the Number 8 further
upstream from the development, versus downstream, to regulate the flows. We suggest that
the location of the diversion be modified more consistent with the master plan, or that
the developer demonstrate the ditch’s abilities to convey the additional proposed flows
to the LWC, and that the flows can be managed in this manner successfully. It should be
noted that with the on-site detention and diversion as currently proposed, the flows along the
Number 8 decrease to 324-fcs from the existing conditions flow of 505-cfs.
Impacts of Development
The proposed development east of the Number 8 Outlet ditch contains four (4) regional
detention ponds. The first pond is located at the southwest corner of the CSRR and Richards
Lake Road. This pond is approximately 190 ac-ft and discharges into the C&S regional
detention pond through a drainage swale. The proposed C&S regional pond is approximately
222 ac-ft and overtops to an overflow pond located to the south while also discharging to the
existing AB pond via dual 3ftx9ft RCBCs. The AB pond is proposed to discharge into the LWC
as it currently does today. A new flume structure has been proposed above the LWC to
discharge directly into the Cooper Slough channel downstream as well. Simultaneously, the
overflow pond south of the main C&S pond includes a 24-inch outlet pipe that discharges
directly into the LWC.
ICONENGINEERING, INC. Page 3 of 8
F:\Icon Projects\Upper Cooper Slough\Montava\Upper Cooper Slough - Montave Draft Memo - updated 9-13-18.docx
The following table summarizes the proposed development detention ponds:
Table 1: Detention Pond Summary Comparison
Location Proposed
Discharge
Location
Proposed
Pond
Volume
Proposed
Pond
Release
Selected
Plan
Discharge
Location
Selected
Plan
Volume
Selected
Plan
Release
Montava A C&S Pond 190 ac-ft 756-cfs NA NA NA
Onsite
Development
Detention
Detention is being provided in the
regional detention ponds.
C&S Pond 170 ac-ft 100-cfs
C&S Pond
(pond 426)
AB Pond 222 ac-ft 719-cfs Cooper
Slough
216 ac-ft 546-cfs
AB Pond
(pond 425)
Cooper
Slough
55 ac-ft 540-cfs LWC 63 ac-ft 377-cfs
LWC 392-cfs
C&S Overflow
Pond
LWC 77 ac-ft 37-cfs NA NA NA
Overall, the projects associated with the proposed development are providing 543 ac-ft of
detention storage. In comparison, the Selected Plan proposes 449 ac-ft through regional and
on-site detention. However, due to the configuration proposed, the timing of the over flows out
of the AB pond and into Cooper Sough are changed for the 100-ear event from what was
modeled for existing conditions. Downstream of the LWC, on Cooper Slough, the existing
conditions flow is 743-cfs, Selected Plan is 654-cfs, and proposed development is 973-cfs.
Also, Cooper Slough, downstream of the LWC, has two main sources of flow in the Selected
Plan – the spill from the LWC and outflow from the proposed C&S regional pond. The
development, as proposed, only connects with Cooper Slough via a spill from the LWC.
Figure 1 shows the flow hydrographs into Cooper Slough with the Selected Plan improvements
constructed as proposed:
ICONENGINEERING, INC. Page 4 of 8
F:\Icon Projects\Upper Cooper Slough\Montava\Upper Cooper Slough - Montave Draft Memo - updated 9-13-18.docx
Figure 1: Flow Hydrographs to Cooper Slough from Selected Plan
As shown in Figure 2, the total flow into the Cooper Slough has increased with the proposed
development and improvements. The peak out of the C&S pond is occurring sooner than
assumed by the Selected Plan.
Figure 2: Flow Hydrographs to Cooper Slough from Proposed Development
0
100
200
300
400
500
600
700
0.00 10.00 20.00 30.00 40.00 50.00 60.00
Flow (-cfs)
time (min)
Selected Plan Regional Detention Ponds
C&S
Ditch spill to Cooper Slough
Total flow to Cooper Slough
AB
0
200
400
600
800
1000
1200
0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00
Flow (-cfs)
Time (min)
Proposed Developement
Pond Outflow to Cooper Slough
Ditch Spill into Cooper Slough
PondOutflow into ditch
Total Flow into Cooper Slough
654-cfs
973-cfs
ICONENGINEERING, INC. Page 5 of 8
F:\Icon Projects\Upper Cooper Slough\Montava\Upper Cooper Slough - Montave Draft Memo - updated 9-13-18.docx
Recommended Modifications to the Design
As part of this review, ICON performed a sensitivity analysis on the current improvement plan,
proposed by Montava, to determine drivers regarding modifications to reduce the discharge to
Cooper Slough.
First, it is suggested that the detention effects on the immediate development be reviewed. Due
to the significant sizes of the proposed regional ponds and outlets, it is feasible that effective
detention is not being generated for the on-site runoff and generating higher discharges
downstream. This may also be more prevalent for low flow events, which would essentially
pass through the detention ponds.
Second, it is suggested that the pond outlet configurations be adjusted to further delay the peak
outflows from the proposed ponds. Specifically, adjustments could potentially be made to the
outlet of the C&S pond and the C&S overflow pond. Our sensitivity run showed that by
changing the C&S outlet to a staged outlet structure, consisting of a 36-in culvert placed at the
invert of the pond with dual 3ft x 7ft RCBC located approximately 3ft above (sizes to be verified
during final design), the hydrograph out of the pond will be delayed such that flows in Cooper
Slough would no longer be increased. In addition to the staged outlet structure, more water can
be conveyed to the Overflow Pond reducing the peak flow going to the AB pond and in turn
Cooper Slough.
Low Flow Impacts
The Montava improvements propose to discharge the AB pond into the Cooper Slough.
Currently, the only inflows from the Cooper Slough are a spill from the LWC which generally
does not release into Cooper Slough until after the AB pond begins to overtop. As proposed,
the AB pond will not overtop in the minor events (up to just below the 10-year event).
Therefore, as long as the spill out of the LWC remains below existing conditions spills,
durational impacts from base lows downstream on Cooper Slough would not be anticipated.
Table 2 compares the peak flow from a range of storm events in the Cooper Slough,
downstream of the LWC, between existing conditions and the proposed project.
Table 2: Comparison of Peak flow in the Cooper Slough, downstream of the Larimer and
Weld Canal
2-year 5-year 10-year 25-year 50-year 100-year
Existing
Conditions
0-cfs 0-cfs 20-cfs 193-cfs 341-cfs 743-cfs
Proposed
Project
0-cfs Not
analyzed
36-cfs Not
analyzed
Not
analyzed
740-cfs
It is recommended that the proposed improvements be fine-tuned during preliminary and
final design to ensure that flows into Cooper Slough remain similar to existing conditions
during higher frequency runoff events such as the 2- through 10- year events. With the
data presented in this memo, it is believed that this can be adequately achieved.
ICONENGINEERING, INC. Page 6 of 8
F:\Icon Projects\Upper Cooper Slough\Montava\Upper Cooper Slough - Montave Draft Memo - updated 9-13-18.docx
Impacts to the Larimer and Weld Canal
The flow out of the LWC during a 100-year event is reduced along the length of the canal with
the recommended adjustments to the Montava development. Table 3 indicates the reduction in
spills resulting from the proposed improvements from the Montava development:
Table 3: Spill out of the Larimer and Weld
Spill
Location
At Cooper
Slough
Upstream I-25 Upstream of the
Boxelder Spill
At the Boxelder
Spill
Existing
Conditions
743-cfs 0-cfs 1.4-cfs 2547-cfs
Proposed
Project
565-cfs* 0-cfs 3.9-cfs 2442-cfs
* Peak flow in the Cooper Slough downstream of the LWC Spill has a peak flow of 740-cfs when considering the
proposed overflow structure above the LWC from the AB Pond.
Impacts of Future Selected Plan Improvements Upstream of Proposed
Development
Other drainage improvements upstream of the Montava development have been proposed as
part of the 2017 Selected Plan of Improvements. These upstream improvements, including the
North Poudre Reservoir No. 6 Spillway and Sod Farm Pond detention improvements, have the
potential to affect the stormwater volume requirements for the Montava development.
The impact from each of these improvements on the peak outflow and volumes at Montava is
discussed below. In general, this evaluation assumes that Montava will develop prior to the
implementation of these other improvements.
North Poudre Reservoir No. 6 Spillway Improvements:
The Selected Plan identifies the placement of an 8-in high iron weir plate on the existing
spillway of the North Poudre Reservoir No. 6. This improvement would allow incoming
stormwater to be stored above the existing spillway elevation, thus significantly reducing
downstream flow and volumes within the eastern portion of the basin. This improvement would
add approximately 307 ac-ft of flood storage on top of the existing irrigation reservoir. The
peak outflows from the reservoir would be reduced by 207-cfs.
This improvement was added into the EPA SWMM model to determine what the impacts would
have on the development. The base model used was the development model with the
recommended revisions to the design, as described above.
ICONENGINEERING, INC. Page 7 of 8
F:\Icon Projects\Upper Cooper Slough\Montava\Upper Cooper Slough - Montave Draft Memo - updated 9-13-18.docx
After implementation, the analysis showed that the No. 6 spillway improvements would generate
only a negligible (2-cfs) reduction in peak discharge at Cooper Slough, immediately downstream
of the LWC. However, reductions in overall pond volume was noted at both Montava A and the
C&S ponds, where the volume was reduced by 51 ac-ft and 68 ac-ft, respectively. The volume
in the AB Pond and overflow discharge into Cooper Slough did not change. Spills from the
LWC also did not significantly change.
With consideration of the North Poudre Reservoir No. 6 improvements, adjustments could be
made to the Montava drainage improvements. Specifically, with the No. 6 improvements in-
place, the site pond volumes could be reduced, or the outlet structure from the C&S pond to the
AB pond could also be reduced in size. The ability to make these adjustments would be
dependent on the timing of construction of the No.6 improvements compared to Montava. The
following scenario goals could be considered.
1) Goal 1 - Reduce C&S Pond Outlet: This option would continue to use the full volume of
the Montava A and C&S ponds, as currently proposed, 222 ac-ft and 190 ac-ft,
respectively. Outlet structures from both ponds would be modified to minimize the
infrastructure needed to cross the railroad at the C&S Pond. For this option to work
effectively, the North Poudre Reservoir No. 6 improvements would need to be
constructed prior to the Montava development or the development is phased to match
the lesser outflow from the C&S Pond until the No. 6 improvements are made.
2) Goal 2 – Reduce Pond Volumes. With the construction of the North Poudre Reservoir
No. 6 improvements, pond volume requirements for the C&S and Montava A Ponds
could be reduced. Montava could consider developing creative phasing and grading
plans which would modify the ponds in the future to remove excess storage and possibly
increase development, or other uses within these areas.
Sod Farm Pond Detention:
The Selected Plan identified the construction of an improvement that will allow all stormwater
flows in excess of the 125-cfs irrigation flow to be diverted from the No. 8 Outlet Ditch into an
improved Sod Farm Detention Pond. The Sod Farm Detention Pond would increase detention
from 112 ac-ft to 174 ac-ft, with a 55-cfs release back into the No. 8 Ditch.
This improvement was added into the EPA SWMM model to determine what the impact it would
have on the development. The base model used was the development model with the
recommended revisions to the design (as described above).
With only a minor volumetric change, the Sod Farm improvements alone provided very little
impact to Montava, or the peak flow rate out of the LWC. The Sod Farm improvements also did
not significantly reduce the peak flow into Cooper Slough downstream of the LWC.
ICONENGINEERING, INC. Page 8 of 8
F:\Icon Projects\Upper Cooper Slough\Montava\Upper Cooper Slough - Montave Draft Memo - updated 9-13-18.docx
North Poudre Reservoir No. 6 Spillway Improvements & Sod Farm Pond
Detention Combined:
Combining both the North Poudre Reservoir No. 6 Spillway improvements with the Sod Farm
improvements, the Montava development was impacted beyond that for only the No. 6 Spillway
improvements. The additional selected plan detention considering both improvements
upstream provided overall detention reductions at the Montava A and the C&S ponds of 51 ac-ft
and 101 ac-ft, respectively.
Restriction of Irrigation Flow in the No. 8 Outlet Ditch during storm events:
As discussed with the Montava development group, the No. 8 Irrigation Ditch Company has
offered to shut down the irrigation flows in the No. 8 Outlet Ditch during large storm events.
This potentially could reduce the flow discharging into the LWC, and ultimately reduce the spill
out of the LWC and into Cooper Slough.
This improvement was added into the EPA SWMM model, as well as the unsteady LWC HEC-
RAS model, to determine what the impacts of removing the irrigation flows completely would
have on the LWC. The base model used was the development model with the recommended
revisions to the design, as described above.
It was determined that the elimination of the irrigation flow provided very little impact to the peak
spills from the LWC. The spill out of the LWC at Cooper Slough were reduced by only
approximately 20-cfs. Regardless, restricting the irrigation flows in the No. 8 Ditch during
flood events would be good practice and should be pursued.
Should, it be feasible, a similar management approach along the LWC could also be
considered. The removal of irrigation flows from the LWC would have a near direct benefit to
the reduction in spills out of the LCW.
APPENDIX D
MASTER PLAN HYDROLOGIC MODELING
APPENDIX E
MASTER PLAN HYDRAULIC CALCULATIONS
HY-8 Culvert Analysis Report
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 319 cfs
Maximum Flow: 319 cfs
Table 1 - Summary of Culvert Flows at Crossing: DP 427
Headwater Elevation
(ft)
Total Discharge (cfs) 427 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4994.56 0.00 0.00 0.00 1
4995.59 31.90 31.90 0.00 1
4996.19 63.80 63.80 0.00 1
4996.70 95.70 95.70 0.00 1
4997.13 127.60 127.60 0.00 1
4997.55 159.50 159.50 0.00 1
4997.93 191.40 191.40 0.00 1
4998.29 223.30 223.30 0.00 1
4998.64 255.20 255.20 0.00 1
4998.97 287.10 287.10 0.00 1
4999.29 319.00 319.00 0.00 1
5000.33 422.09 422.09 0.00 Overtopping
Rating Curve Plot for Crossing: DP 427
Table 2 - Culvert Summary Table: 427
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4994.56 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
31.90 31.90 4995.59 0.925 1.032 3-M1t 0.727 0.603 0.867 0.867 3.065 1.567
63.80 63.80 4996.19 1.469 1.635 3-M1t 1.152 0.958 1.287 1.287 4.130 1.971
95.70 95.70 4996.70 1.925 2.136 3-M1t 1.522 1.255 1.614 1.614 4.941 2.241
127.60 127.60 4997.13 2.342 2.572 3-M1t 1.863 1.520 1.891 1.891 5.624 2.448
159.50 159.50 4997.55 2.722 2.990 3-M2t 2.186 1.764 2.134 2.134 6.228 2.619
191.40 191.40 4997.93 3.076 3.373 3-M2t 2.498 1.992 2.354 2.354 6.776 2.764
223.30 223.30 4998.29 3.414 3.734 3-M2t 2.800 2.207 2.555 2.555 7.284 2.892
255.20 255.20 4998.64 3.746 4.078 3-M2t 3.095 2.413 2.741 2.741 7.758 3.006
287.10 287.10 4998.97 4.081 4.409 3-M2t 3.385 2.610 2.916 2.916 8.206 3.110
319.00 319.00 4999.29 4.427 4.727 3-M2t 3.670 2.800 3.080 3.080 8.631 3.205
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4994.56 ft, Outlet Elevation (invert): 4994.33 ft
Culvert Length: 120.00 ft, Culvert Slope: 0.0019
********************************************************************************
Culvert Performance Curve Plot: 427
Water Surface Profile Plot for Culvert: 427
Site Data - 427
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4994.56 ft
Outlet Station: 120.00 ft
Outlet Elevation: 4994.33 ft
Number of Barrels: 2
Culvert Data Summary - 427
Barrel Shape: Concrete Box
Barrel Span: 6.00 ft
Barrel Rise: 4.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 3 - Downstream Channel Rating Curve (Crossing: DP 427)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4994.33 0.00 0.00 0.00 0.00
31.90 4995.20 0.87 1.57 0.11 0.32
63.80 4995.62 1.29 1.97 0.16 0.34
95.70 4995.94 1.61 2.24 0.20 0.35
127.60 4996.22 1.89 2.45 0.24 0.35
159.50 4996.46 2.13 2.62 0.27 0.36
191.40 4996.68 2.35 2.76 0.29 0.36
223.30 4996.88 2.55 2.89 0.32 0.37
255.20 4997.07 2.74 3.01 0.34 0.37
287.10 4997.25 2.92 3.11 0.36 0.38
319.00 4997.41 3.08 3.20 0.38 0.38
Tailwater Channel Data - DP 427
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 20.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0020
Channel Manning's n: 0.0350
Channel Invert Elevation: 4994.33 ft
Roadway Data for Crossing: DP 427
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5000.33 ft
Roadway Surface: Paved
Roadway Top Width: 30.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 9 cfs
Maximum Flow: 9 cfs
Table 4 - Summary of Culvert Flows at Crossing: DP 427.2
Headwater Elevation
(ft)
Total Discharge (cfs) 427.2 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4991.41 0.00 0.00 0.00 1
4991.95 0.90 0.90 0.00 1
4992.20 1.80 1.80 0.00 1
4992.39 2.70 2.70 0.00 1
4992.57 3.60 3.60 0.00 1
4992.75 4.50 4.50 0.00 1
4992.92 5.40 5.40 0.00 1
4993.10 6.30 6.30 0.00 1
4993.36 7.20 7.20 0.00 1
4993.65 8.10 8.10 0.00 1
4993.97 9.00 9.00 0.00 1
4996.17 13.94 13.94 0.00 Overtopping
Rating Curve Plot for Crossing: DP 427.2
Table 5 - Culvert Summary Table: 427.2
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4991.41 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
0.90 0.90 4991.95 0.484 0.539 2-M2c 0.433 0.349 0.349 0.300 2.888 0.714
1.80 1.80 4992.20 0.697 0.788 2-M2c 0.627 0.501 0.501 0.434 3.481 0.875
2.70 2.70 4992.39 0.889 0.982 2-M2c 0.794 0.622 0.622 0.535 3.903 0.981
3.60 3.60 4992.57 1.061 1.164 2-M2c 0.957 0.725 0.725 0.619 4.258 1.062
4.50 4.50 4992.75 1.217 1.337 2-M2c 1.144 0.812 0.812 0.692 4.608 1.128
5.40 5.40 4992.92 1.365 1.509 7-M2c 1.500 0.893 0.893 0.756 4.925 1.185
6.30 6.30 4993.10 1.515 1.694 7-M2c 1.500 0.965 0.965 0.815 5.244 1.235
7.20 7.20 4993.36 1.673 1.947 7-M2c 1.500 1.036 1.036 0.869 5.530 1.280
8.10 8.10 4993.65 1.845 2.238 7-M2c 1.500 1.099 1.099 0.919 5.840 1.320
9.00 9.00 4993.97 2.034 2.559 7-M2c 1.500 1.156 1.156 0.966 6.158 1.358
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4991.41 ft, Outlet Elevation (invert): 4991.17 ft
Culvert Length: 120.00 ft, Culvert Slope: 0.0020
********************************************************************************
Culvert Performance Curve Plot: 427.2
Water Surface Profile Plot for Culvert: 427.2
Site Data - 427.2
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4991.41 ft
Outlet Station: 120.00 ft
Outlet Elevation: 4991.17 ft
Number of Barrels: 1
Culvert Data Summary - 427.2
Barrel Shape: Circular
Barrel Diameter: 1.50 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None
Table 6 - Downstream Channel Rating Curve (Crossing: DP 427.2)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4991.17 0.00 0.00 0.00 0.00
0.90 4991.47 0.30 0.71 0.04 0.26
1.80 4991.60 0.43 0.87 0.05 0.27
2.70 4991.71 0.54 0.98 0.07 0.28
3.60 4991.79 0.62 1.06 0.08 0.29
4.50 4991.86 0.69 1.13 0.09 0.29
5.40 4991.93 0.76 1.19 0.09 0.29
6.30 4991.98 0.81 1.24 0.10 0.30
7.20 4992.04 0.87 1.28 0.11 0.30
8.10 4992.09 0.92 1.32 0.11 0.30
9.00 4992.14 0.97 1.36 0.12 0.30
Tailwater Channel Data - DP 427.2
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 3.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0020
Channel Manning's n: 0.0350
Channel Invert Elevation: 4991.17 ft
Roadway Data for Crossing: DP 427.2
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 4996.17 ft
Roadway Surface: Paved
Roadway Top Width: 120.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 338 cfs
Maximum Flow: 338 cfs
Table 7 - Summary of Culvert Flows at Crossing: DP 31.1
Headwater Elevation
(ft)
Total Discharge (cfs) 31.1 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4998.80 0.00 0.00 0.00 1
4999.67 33.80 33.80 0.00 1
5000.20 67.60 67.60 0.00 1
5000.63 101.40 101.40 0.00 1
5001.01 135.20 135.20 0.00 1
5001.36 169.00 169.00 0.00 1
5001.69 202.80 202.80 0.00 1
5002.00 236.60 236.60 0.00 1
5002.29 270.40 270.40 0.00 1
5002.58 304.20 304.20 0.00 1
5002.85 338.00 338.00 0.00 1
5003.53 428.20 428.20 0.00 Overtopping
Rating Curve Plot for Crossing: DP 31.1
Table 8 - Culvert Summary Table: 31.1
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4998.80 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
33.80 33.80 4999.67 0.793 0.875 3-M1t 0.559 0.518 0.841 0.841 2.512 1.720
67.60 67.60 5000.20 1.260 1.396 3-M1t 0.872 0.821 1.249 1.249 3.383 2.165
101.40 101.40 5000.63 1.651 1.829 3-M1t 1.137 1.076 1.567 1.567 4.045 2.464
135.20 135.20 5001.01 1.999 2.214 3-M1t 1.377 1.304 1.836 1.836 4.602 2.693
169.00 169.00 5001.36 2.330 2.565 3-M1t 1.600 1.513 2.073 2.073 5.095 2.881
202.80 202.80 5001.69 2.636 2.892 3-M1t 1.813 1.709 2.287 2.287 5.542 3.042
236.60 236.60 5002.00 2.922 3.200 3-M1t 2.017 1.894 2.483 2.483 5.955 3.183
270.40 270.40 5002.29 3.196 3.494 3-M1t 2.214 2.070 2.665 2.665 6.342 3.309
304.20 304.20 5002.58 3.463 3.775 3-M1t 2.405 2.239 2.835 2.835 6.707 3.424
338.00 338.00 5002.85 3.727 4.047 7-M1t 2.593 2.402 2.995 2.995 7.053 3.528
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4998.80 ft, Outlet Elevation (invert): 4998.53 ft
Culvert Length: 105.00 ft, Culvert Slope: 0.0026
********************************************************************************
Culvert Performance Curve Plot: 31.1
Water Surface Profile Plot for Culvert: 31.1
Site Data - 31.1
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4998.80 ft
Outlet Station: 105.00 ft
Outlet Elevation: 4998.53 ft
Number of Barrels: 2
Culvert Data Summary - 31.1
Barrel Shape: Concrete Box
Barrel Span: 8.00 ft
Barrel Rise: 4.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 9 - Downstream Channel Rating Curve (Crossing: DP 31.1)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4998.53 0.00 0.00 0.00 0.00
33.80 4999.37 0.84 1.72 0.13 0.35
67.60 4999.78 1.25 2.17 0.19 0.37
101.40 5000.10 1.57 2.46 0.24 0.39
135.20 5000.37 1.84 2.69 0.29 0.39
169.00 5000.60 2.07 2.88 0.32 0.40
202.80 5000.82 2.29 3.04 0.36 0.41
236.60 5001.01 2.48 3.18 0.39 0.41
270.40 5001.19 2.66 3.31 0.42 0.41
304.20 5001.36 2.83 3.42 0.44 0.42
338.00 5001.53 3.00 3.53 0.47 0.42
Tailwater Channel Data - DP 31.1
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 20.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0025
Channel Manning's n: 0.0350
Channel Invert Elevation: 4998.53 ft
Roadway Data for Crossing: DP 31.1
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5003.53 ft
Roadway Surface: Paved
Roadway Top Width: 40.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 355 cfs
Maximum Flow: 355 cfs
Table 10 - Summary of Culvert Flows at Crossing: DP 31
Headwater Elevation
(ft)
Total Discharge (cfs) 31 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4995.85 0.00 0.00 0.00 1
4996.83 35.50 35.50 0.00 1
4997.41 71.00 71.00 0.00 1
4997.89 106.50 106.50 0.00 1
4998.32 142.00 142.00 0.00 1
4998.72 177.50 177.50 0.00 1
4999.09 213.00 213.00 0.00 1
4999.44 248.50 248.50 0.00 1
4999.78 284.00 284.00 0.00 1
5000.09 319.50 319.50 0.00 1
5000.40 355.00 355.00 0.00 1
5000.43 357.92 357.92 0.00 Overtopping
Rating Curve Plot for Crossing: DP 31
Table 11 - Culvert Summary Table: 31
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4995.85 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
35.50 35.50 4996.83 0.896 0.981 3-M1t 0.639 0.584 0.865 0.865 2.931 1.749
71.00 71.00 4997.41 1.423 1.558 3-M1t 1.004 0.928 1.284 1.284 3.950 2.200
106.50 106.50 4997.89 1.864 2.042 3-M1t 1.316 1.216 1.610 1.610 4.725 2.502
142.00 142.00 4998.32 2.267 2.474 3-M1t 1.601 1.473 1.886 1.886 5.378 2.733
177.50 177.50 4998.72 2.636 2.872 3-M1t 1.869 1.709 2.129 2.129 5.955 2.924
213.00 213.00 4999.09 2.979 3.243 3-M1t 2.125 1.930 2.348 2.348 6.480 3.086
248.50 248.50 4999.44 3.305 3.594 3-M1t 2.373 2.139 2.549 2.549 6.965 3.229
284.00 284.00 4999.78 3.622 3.928 3-M1t 2.613 2.338 2.735 2.735 7.418 3.357
319.50 319.50 5000.09 3.940 4.245 7-M1t 2.847 2.529 2.909 2.909 7.846 3.472
355.00 355.00 5000.40 4.264 4.555 3-M2t 3.077 2.713 3.073 3.073 8.253 3.578
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4995.85 ft, Outlet Elevation (invert): 4995.43 ft
Culvert Length: 168.00 ft, Culvert Slope: 0.0025
********************************************************************************
Culvert Performance Curve Plot: 31
Water Surface Profile Plot for Culvert: 31
Site Data - 31
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4995.85 ft
Outlet Station: 168.00 ft
Outlet Elevation: 4995.43 ft
Number of Barrels: 2
Culvert Data Summary - 31
Barrel Shape: Concrete Box
Barrel Span: 7.00 ft
Barrel Rise: 4.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 12 - Downstream Channel Rating Curve (Crossing: DP 31)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4995.43 0.00 0.00 0.00 0.00
35.50 4996.30 0.87 1.75 0.13 0.36
71.00 4996.71 1.28 2.20 0.20 0.38
106.50 4997.04 1.61 2.50 0.25 0.39
142.00 4997.32 1.89 2.73 0.29 0.40
177.50 4997.56 2.13 2.92 0.33 0.40
213.00 4997.78 2.35 3.09 0.37 0.41
248.50 4997.98 2.55 3.23 0.40 0.41
284.00 4998.16 2.73 3.36 0.43 0.42
319.50 4998.34 2.91 3.47 0.45 0.42
355.00 4998.50 3.07 3.58 0.48 0.42
Tailwater Channel Data - DP 31
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 20.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0025
Channel Manning's n: 0.0350
Channel Invert Elevation: 4995.43 ft
Roadway Data for Crossing: DP 31
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5000.43 ft
Roadway Surface: Paved
Roadway Top Width: 100.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 385 cfs
Maximum Flow: 385 cfs
Table 13 - Summary of Culvert Flows at Crossing: DP 21
Headwater Elevation
(ft)
Total Discharge (cfs) 21 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4991.28 0.00 0.00 0.00 1
4992.24 38.50 38.50 0.00 1
4992.81 77.00 77.00 0.00 1
4993.29 115.50 115.50 0.00 1
4993.70 154.00 154.00 0.00 1
4994.08 192.50 192.50 0.00 1
4994.44 231.00 231.00 0.00 1
4994.77 269.50 269.50 0.00 1
4995.09 308.00 308.00 0.00 1
4995.40 346.50 346.50 0.00 1
4995.69 385.00 385.00 0.00 1
4996.06 434.78 434.78 0.00 Overtopping
Rating Curve Plot for Crossing: DP 21
Table 14 - Culvert Summary Table: 21
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4991.28 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
38.50 38.50 4992.24 0.865 0.965 3-M1t 0.609 0.564 0.906 0.906 2.655 1.798
77.00 77.00 4992.81 1.374 1.535 3-M1t 0.951 0.896 1.344 1.344 3.581 2.258
115.50 115.50 4993.29 1.800 2.006 3-M1t 1.242 1.174 1.684 1.684 4.287 2.565
154.00 154.00 4993.70 2.187 2.423 3-M1t 1.505 1.422 1.971 1.971 4.883 2.802
192.50 192.50 4994.08 2.545 2.803 3-M1t 1.752 1.650 2.224 2.224 5.410 2.995
231.00 231.00 4994.44 2.876 3.158 3-M1t 1.987 1.864 2.452 2.452 5.889 3.161
269.50 269.50 4994.77 3.189 3.493 3-M1t 2.213 2.065 2.660 2.660 6.332 3.306
308.00 308.00 4995.09 3.493 3.812 3-M1t 2.431 2.258 2.854 2.854 6.746 3.436
346.50 346.50 4995.40 3.794 4.118 7-M1t 2.644 2.442 3.034 3.034 7.138 3.554
385.00 385.00 4995.69 4.098 4.412 7-M1t 2.852 2.620 3.204 3.204 7.510 3.661
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4991.28 ft, Outlet Elevation (invert): 4991.06 ft
Culvert Length: 86.00 ft, Culvert Slope: 0.0026
********************************************************************************
Culvert Performance Curve Plot: 21
Water Surface Profile Plot for Culvert: 21
Site Data - 21
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4991.28 ft
Outlet Station: 86.00 ft
Outlet Elevation: 4991.06 ft
Number of Barrels: 2
Culvert Data Summary - 21
Barrel Shape: Concrete Box
Barrel Span: 8.00 ft
Barrel Rise: 4.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 15 - Downstream Channel Rating Curve (Crossing: DP 21)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4991.06 0.00 0.00 0.00 0.00
38.50 4991.97 0.91 1.80 0.14 0.36
77.00 4992.40 1.34 2.26 0.21 0.38
115.50 4992.74 1.68 2.57 0.26 0.39
154.00 4993.03 1.97 2.80 0.31 0.40
192.50 4993.28 2.22 3.00 0.35 0.40
231.00 4993.51 2.45 3.16 0.38 0.41
269.50 4993.72 2.66 3.31 0.41 0.41
308.00 4993.91 2.85 3.44 0.45 0.42
346.50 4994.09 3.03 3.55 0.47 0.42
385.00 4994.26 3.20 3.66 0.50 0.43
Tailwater Channel Data - DP 21
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 20.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0025
Channel Manning's n: 0.0350
Channel Invert Elevation: 4991.06 ft
Roadway Data for Crossing: DP 21
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 4996.06 ft
Roadway Surface: Paved
Roadway Top Width: 35.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 333 cfs
Maximum Flow: 333 cfs
Table 16 - Summary of Culvert Flows at Crossing: DP 437
Headwater Elevation
(ft)
Total Discharge (cfs) 437 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
5022.16 0.00 0.00 0.00 1
5022.97 33.30 33.30 0.00 1
5023.45 66.60 66.60 0.00 1
5023.87 99.90 99.90 0.00 1
5024.24 133.20 133.20 0.00 1
5024.57 166.50 166.50 0.00 1
5024.89 199.80 199.80 0.00 1
5025.18 233.10 233.10 0.00 1
5025.46 266.40 266.40 0.00 1
5025.83 299.70 299.70 0.00 1
5026.34 333.00 333.00 0.00 1
5026.66 354.97 354.97 0.00 Overtopping
Rating Curve Plot for Crossing: DP 437
Table 17 - Culvert Summary Table: 437
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 5022.16 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
33.30 33.30 5022.97 0.727 0.806 3-M1t 0.564 0.474 0.889 0.889 2.081 1.590
66.60 66.60 5023.45 1.154 1.295 3-M1t 0.885 0.752 1.319 1.319 2.806 1.998
99.90 99.90 5023.87 1.513 1.710 3-M1t 1.162 0.985 1.653 1.653 3.358 2.271
133.20 133.20 5024.24 1.841 2.078 3-M1t 1.414 1.194 1.936 1.936 3.823 2.480
166.50 166.50 5024.57 2.138 2.415 3-M1t 1.651 1.385 2.184 2.184 4.235 2.653
199.80 199.80 5024.89 2.416 2.727 3-M1t 1.878 1.564 2.408 2.408 4.609 2.800
233.10 233.10 5025.18 2.685 3.020 7-M1t 2.098 1.733 2.614 2.614 4.955 2.929
266.40 266.40 5025.46 2.952 3.299 7-M1t 2.311 1.895 2.804 2.804 5.279 3.044
299.70 299.70 5025.83 3.226 3.670 7-M2t 3.000 2.050 2.982 2.982 5.584 3.148
333.00 333.00 5026.34 3.512 4.185 4-FFf 3.000 2.199 3.000 3.149 6.167 3.244
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 5022.16 ft, Outlet Elevation (invert): 5021.66 ft
Culvert Length: 245.00 ft, Culvert Slope: 0.0020
********************************************************************************
Culvert Performance Curve Plot: 437
Water Surface Profile Plot for Culvert: 437
Site Data - 437
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 5022.16 ft
Outlet Station: 245.00 ft
Outlet Elevation: 5021.66 ft
Number of Barrels: 3
Culvert Data Summary - 437
Barrel Shape: Concrete Box
Barrel Span: 6.00 ft
Barrel Rise: 3.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 18 - Downstream Channel Rating Curve (Crossing: DP 437)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 5021.66 0.00 0.00 0.00 0.00
33.30 5022.55 0.89 1.59 0.11 0.32
66.60 5022.98 1.32 2.00 0.16 0.34
99.90 5023.31 1.65 2.27 0.21 0.35
133.20 5023.60 1.94 2.48 0.24 0.36
166.50 5023.84 2.18 2.65 0.27 0.36
199.80 5024.07 2.41 2.80 0.30 0.37
233.10 5024.27 2.61 2.93 0.33 0.37
266.40 5024.46 2.80 3.04 0.35 0.37
299.70 5024.64 2.98 3.15 0.37 0.38
333.00 5024.81 3.15 3.24 0.39 0.38
Tailwater Channel Data - DP 437
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 20.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0020
Channel Manning's n: 0.0350
Channel Invert Elevation: 5021.66 ft
Roadway Data for Crossing: DP 437
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5026.66 ft
Roadway Surface: Paved
Roadway Top Width: 45.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 1781 cfs
Maximum Flow: 1781 cfs
Table 19 - Summary of Culvert Flows at Crossing: DP 834
Headwater Elevation
(ft)
Total Discharge (cfs) 834 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
5019.17 0.00 0.00 0.00 1
5020.61 178.10 178.10 0.00 1
5021.48 356.20 356.20 0.00 1
5022.21 534.30 534.30 0.00 1
5022.86 712.40 712.40 0.00 1
5023.45 890.50 890.50 0.00 1
5024.00 1068.60 1068.60 0.00 1
5024.51 1246.70 1246.70 0.00 1
5025.00 1424.80 1424.80 0.00 1
5025.57 1602.90 1602.90 0.00 1
5026.42 1781.00 1781.00 0.00 1
5026.64 1829.89 1829.89 0.00 Overtopping
Rating Curve Plot for Crossing: DP 834
Table 20 - Culvert Summary Table: 834
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 5019.17 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
178.10 178.10 5020.61 1.305 1.444 3-M1t 0.962 0.851 1.425 1.425 3.125 2.244
356.20 356.20 5021.48 2.072 2.315 3-M1t 1.512 1.350 2.131 2.131 4.179 2.857
534.30 534.30 5022.21 2.723 3.043 3-M1t 1.985 1.770 2.688 2.688 4.970 3.272
712.40 712.40 5022.86 3.308 3.689 3-M1t 2.418 2.144 3.163 3.163 5.630 3.595
890.50 890.50 5023.45 3.841 4.278 3-M1t 2.825 2.488 3.585 3.585 6.210 3.861
1068.60 1068.60 5024.00 4.346 4.826 3-M1t 3.214 2.809 3.968 3.968 6.733 4.088
1246.70 1246.70 5024.51 4.845 5.342 7-M1t 3.591 3.113 4.320 4.320 7.214 4.289
1424.80 1424.80 5025.00 5.353 5.832 7-M1t 3.957 3.403 4.649 4.649 7.662 4.468
1602.90 1602.90 5025.57 5.887 6.396 7-M2t 5.000 3.681 4.957 4.957 8.084 4.631
1781.00 1781.00 5026.42 6.457 7.251 4-FFf 5.000 3.949 5.000 5.248 8.905 4.780
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 5019.17 ft, Outlet Elevation (invert): 5018.64 ft
Culvert Length: 265.00 ft, Culvert Slope: 0.0020
********************************************************************************
Culvert Performance Curve Plot: 834
Water Surface Profile Plot for Culvert: 834
Site Data - 834
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 5019.17 ft
Outlet Station: 265.00 ft
Outlet Elevation: 5018.64 ft
Number of Barrels: 4
Culvert Data Summary - 834
Barrel Shape: Concrete Box
Barrel Span: 10.00 ft
Barrel Rise: 5.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 21 - Downstream Channel Rating Curve (Crossing: DP 834)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 5018.64 0.00 0.00 0.00 0.00
178.10 5020.06 1.42 2.24 0.18 0.35
356.20 5020.77 2.13 2.86 0.27 0.37
534.30 5021.33 2.69 3.27 0.34 0.38
712.40 5021.80 3.16 3.59 0.39 0.39
890.50 5022.23 3.59 3.86 0.45 0.40
1068.60 5022.61 3.97 4.09 0.50 0.40
1246.70 5022.96 4.32 4.29 0.54 0.41
1424.80 5023.29 4.65 4.47 0.58 0.41
1602.90 5023.60 4.96 4.63 0.62 0.42
1781.00 5023.89 5.25 4.78 0.65 0.42
Tailwater Channel Data - DP 834
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 50.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0020
Channel Manning's n: 0.0350
Channel Invert Elevation: 5018.64 ft
Roadway Data for Crossing: DP 834
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5026.64 ft
Roadway Surface: Paved
Roadway Top Width: 45.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 1312 cfs
Maximum Flow: 1312 cfs
Table 22 - Summary of Culvert Flows at Crossing: DP 431
Headwater
Elevation (ft)
Total Discharge
(cfs)
431 - Pedestrian
Discharge (cfs)
431 - 5-Year
Discharge (cfs)
Roadway
Discharge (cfs)
Iterations
4984.48 0.00 0.00 0.00 0.00 0
4987.66 131.20 57.48 73.69 0.00 7
4988.71 262.40 149.04 113.32 0.00 4
4989.57 393.60 243.80 149.78 0.00 3
4990.34 524.80 339.99 184.78 0.00 3
4991.04 656.00 437.05 218.92 0.00 3
4991.70 787.20 534.38 252.79 0.00 3
4992.34 918.40 631.79 286.58 0.00 3
4992.94 1049.60 729.77 319.80 0.00 3
4993.51 1180.80 828.15 352.62 0.00 3
4994.06 1312.00 926.83 385.17 0.00 3
4998.35 2386.98 1717.76 669.23 0.00 Overtopping
Rating Curve Plot for Crossing: DP 431
Table 23 - Culvert Summary Table: 431 - Pedestrian
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4984.48 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
131.20 57.48 4987.66 1.179 0.363 1-S2n 0.730 0.770 0.730 1.191 5.251 2.012
262.40 149.04 4988.71 2.226 1.066 1-S2n 1.335 1.453 1.335 1.786 7.443 2.572
393.60 243.80 4989.57 3.090 1.670 1-S2n 1.836 2.017 1.836 2.257 8.853 2.955
524.80 339.99 4990.34 3.857 2.230 1-S2n 2.286 2.517 2.357 2.660 9.615 3.253
656.00 437.05 4991.04 4.560 2.770 1-S2n 2.702 2.976 2.790 3.019 10.444 3.500
787.20 534.38 4991.70 5.224 3.297 1-S2n 3.097 3.403 3.200 3.346 11.133 3.712
918.40 631.79 4992.34 5.857 3.820 1-S2n 3.473 3.805 3.590 3.647 11.731 3.898
1049.60 729.77 4992.94 6.457 4.346 1-S2n 3.839 4.189 3.967 3.929 12.263 4.066
1180.80 828.15 4993.51 7.029 4.877 1-S2n 4.193 4.558 4.333 4.193 12.741 4.217
1312.00 926.83 4994.06 7.579 5.417 1-S2n 4.540 4.913 4.689 4.443 13.176 4.357
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4986.48 ft, Outlet Elevation (invert): 4986.07 ft
Culvert Length: 125.00 ft, Culvert Slope: 0.0033
********************************************************************************
Culvert Performance Curve Plot: 431 - Pedestrian
Water Surface Profile Plot for Culvert: 431 - Pedestrian
Site Data - 431 - Pedestrian
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4986.48 ft
Outlet Station: 125.00 ft
Outlet Elevation: 4986.07 ft
Number of Barrels: 1
Culvert Data Summary - 431 - Pedestrian
Barrel Shape: Concrete Box
Barrel Span: 15.00 ft
Barrel Rise: 10.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 24 - Culvert Summary Table: 431 - 5-Year
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4984.48 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
131.20 73.69 4987.66 2.895 3.179 2-M2c 2.014 1.890 1.890 1.191 7.800 2.012
262.40 113.32 4988.71 3.857 4.226 2-M2c 2.780 2.517 2.517 1.786 9.003 2.572
393.60 149.78 4989.57 4.645 5.090 2-M2c 3.449 3.032 3.032 2.257 9.881 2.955
524.80 184.78 4990.34 5.344 5.857 2-M2c 4.073 3.487 3.487 2.660 10.597 3.253
656.00 218.92 4991.04 5.983 6.561 2-M2c 4.670 3.905 3.905 3.019 11.213 3.500
787.20 252.79 4991.70 6.607 7.224 2-M2c 5.255 4.298 4.298 3.346 11.764 3.712
918.40 286.58 4992.34 7.195 7.857 2-M2c 5.832 4.673 4.673 3.647 12.266 3.898
1049.60 319.80 4992.94 7.748 8.456 2-M2c 6.396 5.027 5.027 3.929 12.723 4.066
1180.80 352.62 4993.51 8.274 9.029 2-M2c 6.948 5.365 5.365 4.193 13.144 4.217
1312.00 385.17 4994.06 8.778 9.579 2-M2c 7.494 5.691 5.691 4.443 13.537 4.357
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4984.48 ft, Outlet Elevation (invert): 4984.07 ft
Culvert Length: 125.00 ft, Culvert Slope: 0.0033
********************************************************************************
Culvert Performance Curve Plot: 431 - 5-Year
Water Surface Profile Plot for Culvert: 431 - 5-Year
Site Data - 431 - 5-Year
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4984.48 ft
Outlet Station: 125.00 ft
Outlet Elevation: 4984.07 ft
Number of Barrels: 1
Culvert Data Summary - 431 - 5-Year
Barrel Shape: Concrete Box
Barrel Span: 5.00 ft
Barrel Rise: 12.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 25 - Downstream Channel Rating Curve (Crossing: DP 431)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4984.07 0.00 0.00 0.00 0.00
131.20 4985.26 1.19 2.01 0.15 0.34
262.40 4985.86 1.79 2.57 0.22 0.36
393.60 4986.33 2.26 2.95 0.28 0.37
524.80 4986.73 2.66 3.25 0.33 0.38
656.00 4987.09 3.02 3.50 0.38 0.39
787.20 4987.42 3.35 3.71 0.42 0.39
918.40 4987.72 3.65 3.90 0.46 0.40
1049.60 4988.00 3.93 4.07 0.49 0.40
1180.80 4988.26 4.19 4.22 0.52 0.41
1312.00 4988.51 4.44 4.36 0.55 0.41
Tailwater Channel Data - DP 431
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 50.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0020
Channel Manning's n: 0.0350
Channel Invert Elevation: 4984.07 ft
Roadway Data for Crossing: DP 431
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 4998.35 ft
Roadway Surface: Paved
Roadway Top Width: 70.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 396 cfs
Maximum Flow: 396 cfs
Table 26 - Summary of Culvert Flows at Crossing: DP 841
Headwater Elevation
(ft)
Total Discharge (cfs) 841 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
5007.44 0.00 0.00 0.00 1
5008.76 39.60 39.60 0.00 1
5009.54 79.20 79.20 0.00 1
5010.20 118.80 118.80 0.00 1
5010.78 158.40 158.40 0.00 1
5011.32 198.00 198.00 0.00 1
5011.82 237.60 237.60 0.00 1
5012.30 277.20 277.20 0.00 1
5012.76 316.80 316.80 0.00 1
5013.20 356.40 356.40 0.00 1
5013.62 396.00 396.00 0.00 1
5013.94 426.79 426.79 0.00 Overtopping
Rating Curve Plot for Crossing: DP 841
Table 27 - Culvert Summary Table: 841
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 5007.44 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
39.60 39.60 5008.76 1.206 1.322 3-M1t 0.877 0.787 1.067 1.067 3.711 1.926
79.20 79.20 5009.54 1.915 2.101 3-M1t 1.413 1.249 1.563 1.563 5.068 2.385
118.80 118.80 5010.20 2.511 2.756 3-M1t 1.887 1.637 1.941 1.941 6.120 2.688
158.40 158.40 5010.78 3.056 3.336 3-M2t 2.333 1.983 2.257 2.257 7.018 2.920
198.00 198.00 5011.32 3.550 3.880 3-M2t 2.760 2.301 2.533 2.533 7.817 3.111
237.60 237.60 5011.82 4.012 4.385 3-M2t 3.175 2.598 2.779 2.779 8.548 3.273
277.20 277.20 5012.30 4.457 4.863 3-M2t 3.582 2.879 3.004 3.004 9.227 3.415
316.80 316.80 5012.76 4.901 5.319 3-M2t 3.982 3.147 3.211 3.211 9.865 3.543
356.40 356.40 5013.20 5.354 5.757 3-M2t 5.000 3.404 3.405 3.405 10.468 3.658
396.00 396.00 5013.62 5.827 6.180 7-M2c 5.000 3.652 3.652 3.586 10.844 3.764
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 5007.44 ft, Outlet Elevation (invert): 5006.94 ft
Culvert Length: 196.00 ft, Culvert Slope: 0.0026
********************************************************************************
Culvert Performance Curve Plot: 841
Water Surface Profile Plot for Culvert: 841
Site Data - 841
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 5007.44 ft
Outlet Station: 196.00 ft
Outlet Elevation: 5006.94 ft
Number of Barrels: 2
Culvert Data Summary - 841
Barrel Shape: Concrete Box
Barrel Span: 5.00 ft
Barrel Rise: 5.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge (30-75º flare) Wingwall
Inlet Depression: None
Table 28 - Downstream Channel Rating Curve (Crossing: DP 841)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 5006.94 0.00 0.00 0.00 0.00
39.60 5008.01 1.07 1.93 0.17 0.36
79.20 5008.50 1.56 2.39 0.24 0.38
118.80 5008.88 1.94 2.69 0.30 0.39
158.40 5009.20 2.26 2.92 0.35 0.40
198.00 5009.47 2.53 3.11 0.40 0.41
237.60 5009.72 2.78 3.27 0.43 0.41
277.20 5009.94 3.00 3.42 0.47 0.42
316.80 5010.15 3.21 3.54 0.50 0.42
356.40 5010.34 3.40 3.66 0.53 0.42
396.00 5010.53 3.59 3.76 0.56 0.43
Tailwater Channel Data - DP 841
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 15.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0025
Channel Manning's n: 0.0350
Channel Invert Elevation: 5006.94 ft
Roadway Data for Crossing: DP 841
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5013.94 ft
Roadway Surface: Paved
Roadway Top Width: 35.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 138 cfs
Maximum Flow: 138 cfs
Table 29 - Summary of Culvert Flows at Crossing: DP 833
Headwater Elevation
(ft)
Total Discharge (cfs) 833 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
5004.05 0.00 0.00 0.00 1
5005.19 13.80 13.80 0.00 1
5005.70 27.60 27.60 0.00 1
5006.09 41.40 41.40 0.00 1
5006.44 55.20 55.20 0.00 1
5006.75 69.00 69.00 0.00 1
5007.04 82.80 82.80 0.00 1
5007.32 96.60 96.60 0.00 1
5007.59 110.40 110.40 0.00 1
5007.85 124.20 124.20 0.00 1
5008.11 138.00 138.00 0.00 1
5009.80 221.44 221.44 0.00 Overtopping
Rating Curve Plot for Crossing: DP 833
Table 30 - Culvert Summary Table: 833
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 5004.05 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
13.80 13.80 5005.19 1.038 1.144 2-M2c 0.815 0.759 0.759 0.586 4.155 1.359
27.60 27.60 5005.70 1.488 1.646 2-M2c 1.156 1.084 1.084 0.871 5.018 1.714
41.40 41.40 5006.09 1.846 2.044 2-M2c 1.431 1.336 1.336 1.094 5.631 1.953
55.20 55.20 5006.44 2.186 2.389 2-M2c 1.674 1.551 1.551 1.283 6.128 2.137
69.00 69.00 5006.75 2.514 2.701 2-M2c 1.901 1.745 1.745 1.450 6.549 2.288
82.80 82.80 5007.04 2.813 2.994 2-M2c 2.120 1.922 1.922 1.601 6.932 2.417
96.60 96.60 5007.32 3.091 3.272 2-M2c 2.337 2.081 2.081 1.739 7.310 2.530
110.40 110.40 5007.59 3.356 3.542 2-M2c 2.558 2.231 2.231 1.867 7.662 2.631
124.20 124.20 5007.85 3.616 3.804 2-M2c 2.794 2.373 2.373 1.987 7.994 2.723
138.00 138.00 5008.11 3.878 4.064 7-M2c 3.060 2.506 2.506 2.100 8.329 2.807
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 5004.05 ft, Outlet Elevation (invert): 5003.80 ft
Culvert Length: 100.00 ft, Culvert Slope: 0.0025
********************************************************************************
Culvert Performance Curve Plot: 833
Water Surface Profile Plot for Culvert: 833
Site Data - 833
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 5004.05 ft
Outlet Station: 100.00 ft
Outlet Elevation: 5003.80 ft
Number of Barrels: 2
Culvert Data Summary - 833
Barrel Shape: Circular
Barrel Diameter: 4.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None
Table 31 - Downstream Channel Rating Curve (Crossing: DP 833)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 5003.80 0.00 0.00 0.00 0.00
13.80 5004.39 0.59 1.36 0.09 0.33
27.60 5004.67 0.87 1.71 0.14 0.35
41.40 5004.89 1.09 1.95 0.17 0.36
55.20 5005.08 1.28 2.14 0.20 0.37
69.00 5005.25 1.45 2.29 0.23 0.38
82.80 5005.40 1.60 2.42 0.25 0.38
96.60 5005.54 1.74 2.53 0.27 0.39
110.40 5005.67 1.87 2.63 0.29 0.39
124.20 5005.79 1.99 2.72 0.31 0.40
138.00 5005.90 2.10 2.81 0.33 0.40
Tailwater Channel Data - DP 833
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 15.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0025
Channel Manning's n: 0.0350
Channel Invert Elevation: 5003.80 ft
Roadway Data for Crossing: DP 833
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5009.80 ft
Roadway Surface: Paved
Roadway Top Width: 45.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 224 cfs
Maximum Flow: 224 cfs
Table 32 - Summary of Culvert Flows at Crossing: DP 831
Headwater Elevation
(ft)
Total Discharge (cfs) 831 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4997.08 0.00 0.00 0.00 1
4998.27 22.40 22.40 0.00 1
4998.80 44.80 44.80 0.00 1
4999.21 67.20 67.20 0.00 1
4999.57 89.60 89.60 0.00 1
4999.90 112.00 112.00 0.00 1
5000.21 134.40 134.40 0.00 1
5000.51 156.80 156.80 0.00 1
5000.79 179.20 179.20 0.00 1
5001.07 201.60 201.60 0.00 1
5001.35 224.00 224.00 0.00 1
5002.87 334.36 334.36 0.00 Overtopping
Rating Curve Plot for Crossing: DP 831
Table 33 - Culvert Summary Table: 831
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4997.08 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
22.40 22.40 4998.27 1.079 1.192 2-M2c 0.849 0.791 0.791 0.774 4.242 1.600
44.80 44.80 4998.80 1.552 1.716 3-M2t 1.208 1.129 1.143 1.143 5.039 2.002
67.20 67.20 4999.21 1.926 2.132 3-M2t 1.497 1.392 1.429 1.429 5.556 2.270
89.60 89.60 4999.57 2.298 2.494 3-M2t 1.756 1.618 1.670 1.670 6.010 2.475
112.00 112.00 4999.90 2.640 2.823 3-M2t 1.999 1.821 1.881 1.881 6.427 2.643
134.40 134.40 5000.21 2.952 3.132 3-M2t 2.235 2.003 2.072 2.072 6.819 2.786
156.80 156.80 5000.51 3.244 3.428 3-M2t 2.473 2.166 2.245 2.245 7.197 2.912
179.20 179.20 5000.79 3.527 3.714 3-M2t 2.723 2.323 2.406 2.406 7.564 3.024
201.60 201.60 5001.07 3.809 3.995 3-M2t 3.002 2.472 2.556 2.556 7.925 3.126
224.00 224.00 5001.35 4.098 4.273 3-M2t 4.000 2.609 2.698 2.698 8.282 3.220
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4997.08 ft, Outlet Elevation (invert): 4996.87 ft
Culvert Length: 85.00 ft, Culvert Slope: 0.0025
********************************************************************************
Culvert Performance Curve Plot: 831
Water Surface Profile Plot for Culvert: 831
Site Data - 831
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4997.08 ft
Outlet Station: 85.00 ft
Outlet Elevation: 4996.87 ft
Number of Barrels: 3
Culvert Data Summary - 831
Barrel Shape: Circular
Barrel Diameter: 4.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None
Table 34 - Downstream Channel Rating Curve (Crossing: DP 831)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4996.87 0.00 0.00 0.00 0.00
22.40 4997.64 0.77 1.60 0.12 0.35
44.80 4998.01 1.14 2.00 0.18 0.37
67.20 4998.30 1.43 2.27 0.22 0.38
89.60 4998.54 1.67 2.47 0.26 0.39
112.00 4998.75 1.88 2.64 0.29 0.39
134.40 4998.94 2.07 2.79 0.32 0.40
156.80 4999.12 2.25 2.91 0.35 0.40
179.20 4999.28 2.41 3.02 0.38 0.41
201.60 4999.43 2.56 3.13 0.40 0.41
224.00 4999.57 2.70 3.22 0.42 0.41
Tailwater Channel Data - DP 831
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 15.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0025
Channel Manning's n: 0.0350
Channel Invert Elevation: 4996.87 ft
Roadway Data for Crossing: DP 831
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5002.87 ft
Roadway Surface: Paved
Roadway Top Width: 35.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 249 cfs
Maximum Flow: 249 cfs
Table 35 - Summary of Culvert Flows at Crossing: DP 822
Headwater Elevation
(ft)
Total Discharge (cfs) 822 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4995.19 0.00 0.00 0.00 1
4996.45 24.90 24.90 0.00 1
4997.01 49.80 49.80 0.00 1
4997.45 74.70 74.70 0.00 1
4997.84 99.60 99.60 0.00 1
4998.19 124.50 124.50 0.00 1
4998.52 149.40 149.40 0.00 1
4998.84 174.30 174.30 0.00 1
4999.16 199.20 199.20 0.00 1
4999.47 224.10 224.10 0.00 1
4999.79 249.00 249.00 0.00 1
5001.83 371.52 371.52 0.00 Overtopping
Rating Curve Plot for Crossing: DP 822
Table 36 - Culvert Summary Table: 822
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4995.19 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
24.90 24.90 4996.45 1.141 1.261 2-M2c 0.886 0.835 0.835 0.822 4.362 1.658
49.80 49.80 4997.01 1.641 1.818 3-M2t 1.263 1.193 1.212 1.212 5.162 2.070
74.70 74.70 4997.45 2.047 2.260 3-M2t 1.569 1.472 1.514 1.514 5.713 2.343
99.60 99.60 4997.84 2.455 2.646 3-M2t 1.844 1.710 1.768 1.768 6.199 2.553
124.50 124.50 4998.19 2.817 2.999 3-M2t 2.105 1.925 1.990 1.990 6.648 2.725
149.40 149.40 4998.52 3.149 3.331 3-M2t 2.362 2.114 2.190 2.190 7.074 2.872
174.30 174.30 4998.84 3.465 3.654 3-M2t 2.628 2.290 2.372 2.372 7.485 3.001
199.20 199.20 4999.16 3.779 3.970 3-M2t 2.918 2.457 2.541 2.541 7.887 3.116
224.10 224.10 4999.47 4.099 4.285 3-M2t 4.000 2.610 2.698 2.698 8.283 3.220
249.00 249.00 4999.79 4.435 4.604 3-M2t 4.000 2.758 2.846 2.846 8.678 3.316
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4995.19 ft, Outlet Elevation (invert): 4994.83 ft
Culvert Length: 140.00 ft, Culvert Slope: 0.0026
********************************************************************************
Culvert Performance Curve Plot: 822
Water Surface Profile Plot for Culvert: 822
Site Data - 822
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4995.19 ft
Outlet Station: 140.00 ft
Outlet Elevation: 4994.83 ft
Number of Barrels: 3
Culvert Data Summary - 822
Barrel Shape: Circular
Barrel Diameter: 4.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None
Table 37 - Downstream Channel Rating Curve (Crossing: DP 822)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4994.83 0.00 0.00 0.00 0.00
24.90 4995.65 0.82 1.66 0.13 0.35
49.80 4996.04 1.21 2.07 0.19 0.37
74.70 4996.34 1.51 2.34 0.24 0.38
99.60 4996.60 1.77 2.55 0.28 0.39
124.50 4996.82 1.99 2.73 0.31 0.40
149.40 4997.02 2.19 2.87 0.34 0.40
174.30 4997.20 2.37 3.00 0.37 0.40
199.20 4997.37 2.54 3.12 0.40 0.41
224.10 4997.53 2.70 3.22 0.42 0.41
249.00 4997.68 2.85 3.32 0.44 0.41
Tailwater Channel Data - DP 822
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 15.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0025
Channel Manning's n: 0.0350
Channel Invert Elevation: 4994.83 ft
Roadway Data for Crossing: DP 822
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5001.83 ft
Roadway Surface: Paved
Roadway Top Width: 85.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 138 cfs
Maximum Flow: 138 cfs
Table 38 - Summary of Culvert Flows at Crossing: DP 904
Headwater Elevation
(ft)
Total Discharge (cfs) 904 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4986.00 0.00 0.00 0.00 1
4986.01 13.80 13.80 0.00 1
4986.05 27.60 27.60 0.00 1
4986.12 41.40 41.40 0.00 1
4986.21 55.20 55.20 0.00 1
4986.33 69.00 69.00 0.00 1
4986.47 82.80 82.80 0.00 1
4986.64 96.60 96.60 0.00 1
4986.84 110.40 110.40 0.00 1
4987.06 124.20 124.20 0.00 1
4987.31 138.00 138.00 0.00 1
4989.00 208.43 208.43 0.00 Overtopping
Rating Curve Plot for Crossing: DP 904
Table 39 - Culvert Summary Table: 904
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4986.00 0.000 11.000 0-NF 0.000 0.000 5.500 12.390 0.000 0.000
13.80 13.80 4986.01 1.349 11.013 4-FFf 0.900 0.990 5.500 12.390 0.581 0.000
27.60 27.60 4986.05 1.935 11.053 4-FFf 1.271 1.412 5.500 12.390 1.162 0.000
41.40 41.40 4986.12 2.398 11.118 4-FFf 1.562 1.744 5.500 12.390 1.743 0.000
55.20 55.20 4986.21 2.809 11.210 4-FFf 1.814 2.024 5.500 12.390 2.323 0.000
69.00 69.00 4986.33 3.237 11.329 4-FFf 2.043 2.274 5.500 12.390 2.904 0.000
82.80 82.80 4986.47 3.626 11.473 4-FFf 2.258 2.504 5.500 12.390 3.485 0.000
96.60 96.60 4986.64 3.985 11.644 4-FFf 2.462 2.714 5.500 12.390 4.066 0.000
110.40 110.40 4986.84 4.325 11.841 4-FFf 2.660 2.906 5.500 12.390 4.647 0.000
124.20 124.20 4987.06 4.652 12.065 4-FFf 2.854 3.091 5.500 12.390 5.228 0.000
138.00 138.00 4987.31 4.975 12.315 4-FFf 3.046 3.267 5.500 12.390 5.808 0.000
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4975.00 ft, Outlet Elevation (invert): 4973.61 ft
Culvert Length: 315.00 ft, Culvert Slope: 0.0044
********************************************************************************
Culvert Performance Curve Plot: 904
Water Surface Profile Plot for Culvert: 904
Site Data - 904
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4975.00 ft
Outlet Station: 315.00 ft
Outlet Elevation: 4973.61 ft
Number of Barrels: 1
Culvert Data Summary - 904
Barrel Shape: Circular
Barrel Diameter: 5.50 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None
Table 40 - Downstream Channel Rating Curve (Crossing: DP 904)
Flow (cfs) Water Surface Elev (ft) Depth (ft)
0.00 4986.00 12.39
13.80 4986.00 12.39
27.60 4986.00 12.39
41.40 4986.00 12.39
55.20 4986.00 12.39
69.00 4986.00 12.39
82.80 4986.00 12.39
96.60 4986.00 12.39
110.40 4986.00 12.39
124.20 4986.00 12.39
138.00 4986.00 12.39
Tailwater Channel Data - DP 904
Tailwater Channel Option: Enter Constant Tailwater Elevation
Constant Tailwater Elevation: 4986.00 ft
Roadway Data for Crossing: DP 904
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 4989.00 ft
Roadway Surface: Paved
Roadway Top Width: 155.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 6 cfs
Maximum Flow: 6 cfs
Table 41 - Summary of Culvert Flows at Crossing: DP 427.1
Headwater Elevation
(ft)
Total Discharge (cfs) 427.1 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4991.41 0.00 0.00 0.00 1
4991.85 0.60 0.60 0.00 1
4992.04 1.20 1.20 0.00 1
4992.20 1.80 1.80 0.00 1
4992.33 2.40 2.40 0.00 1
4992.46 3.00 3.00 0.00 1
4992.57 3.60 3.60 0.00 1
4992.69 4.20 4.20 0.00 1
4992.80 4.80 4.80 0.00 1
4992.92 5.40 5.40 0.00 1
4993.04 6.00 6.00 0.00 1
4996.17 13.94 13.94 0.00 Overtopping
Rating Curve Plot for Crossing: DP 427.1
Table 42 - Culvert Summary Table: 427.1
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4991.41 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
0.60 0.60 4991.85 0.391 0.436 2-M2c 0.352 0.284 0.284 0.240 2.574 0.630
1.20 1.20 4992.04 0.561 0.627 2-M2c 0.503 0.406 0.406 0.351 3.102 0.777
1.80 1.80 4992.20 0.697 0.788 2-M2c 0.627 0.501 0.501 0.434 3.481 0.875
2.40 2.40 4992.33 0.825 0.918 2-M2c 0.739 0.582 0.582 0.504 3.783 0.949
3.00 3.00 4992.46 0.949 1.046 2-M2c 0.848 0.658 0.658 0.565 4.022 1.010
3.60 3.60 4992.57 1.061 1.164 2-M2c 0.957 0.725 0.725 0.619 4.258 1.062
4.20 4.20 4992.69 1.166 1.279 2-M2c 1.076 0.784 0.784 0.668 4.492 1.108
4.80 4.80 4992.80 1.267 1.394 2-M2c 1.500 0.839 0.839 0.714 4.724 1.148
5.40 5.40 4992.92 1.365 1.509 7-M2c 1.500 0.893 0.893 0.756 4.925 1.185
6.00 6.00 4993.04 1.464 1.630 7-M2c 1.500 0.942 0.942 0.796 5.138 1.219
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4991.41 ft, Outlet Elevation (invert): 4991.17 ft
Culvert Length: 120.00 ft, Culvert Slope: 0.0020
********************************************************************************
Culvert Performance Curve Plot: 427.1
Water Surface Profile Plot for Culvert: 427.1
Site Data - 427.1
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4991.41 ft
Outlet Station: 120.00 ft
Outlet Elevation: 4991.17 ft
Number of Barrels: 1
Culvert Data Summary - 427.1
Barrel Shape: Circular
Barrel Diameter: 1.50 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None
Table 43 - Downstream Channel Rating Curve (Crossing: DP 427.1)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4991.17 0.00 0.00 0.00 0.00
0.60 4991.41 0.24 0.63 0.03 0.25
1.20 4991.52 0.35 0.78 0.04 0.27
1.80 4991.60 0.43 0.87 0.05 0.27
2.40 4991.67 0.50 0.95 0.06 0.28
3.00 4991.73 0.56 1.01 0.07 0.28
3.60 4991.79 0.62 1.06 0.08 0.29
4.20 4991.84 0.67 1.11 0.08 0.29
4.80 4991.88 0.71 1.15 0.09 0.29
5.40 4991.93 0.76 1.19 0.09 0.29
6.00 4991.97 0.80 1.22 0.10 0.30
Tailwater Channel Data - DP 427.1
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 3.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0020
Channel Manning's n: 0.0350
Channel Invert Elevation: 4991.17 ft
Roadway Data for Crossing: DP 427.1
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 4996.17 ft
Roadway Surface: Paved
Roadway Top Width: 120.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 277 cfs
Maximum Flow: 277 cfs
Table 44 - Summary of Culvert Flows at Crossing: DP 31.2
Headwater Elevation
(ft)
Total Discharge (cfs) 31.2 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
4998.80 0.00 0.00 0.00 1
4999.95 27.70 27.70 0.00 1
5000.45 55.40 55.40 0.00 1
5000.85 83.10 83.10 0.00 1
5001.20 110.80 110.80 0.00 1
5001.51 138.50 138.50 0.00 1
5001.80 166.20 166.20 0.00 1
5002.08 193.90 193.90 0.00 1
5002.35 221.60 221.60 0.00 1
5002.61 249.30 249.30 0.00 1
5002.87 277.00 277.00 0.00 1
5003.53 345.85 345.85 0.00 Overtopping
Rating Curve Plot for Crossing: DP 31.2
Table 45 - Culvert Summary Table: 31.2
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 4998.80 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
27.70 27.70 4999.95 1.040 1.147 2-M2c 0.810 0.761 0.761 0.750 4.159 1.607
55.40 55.40 5000.45 1.491 1.651 3-M2t 1.150 1.086 1.116 1.116 4.834 2.030
83.10 83.10 5000.85 1.850 2.049 3-M2t 1.423 1.338 1.402 1.402 5.287 2.314
110.80 110.80 5001.20 2.191 2.395 3-M2t 1.664 1.554 1.646 1.646 5.684 2.533
138.50 138.50 5001.51 2.520 2.709 3-M2t 1.889 1.749 1.860 1.860 6.048 2.713
166.20 166.20 5001.80 2.819 3.001 3-M2t 2.106 1.926 2.054 2.054 6.391 2.867
193.90 193.90 5002.08 3.097 3.279 3-M2t 2.321 2.085 2.233 2.233 6.722 3.002
221.60 221.60 5002.35 3.363 3.550 3-M2t 2.540 2.235 2.398 2.398 7.044 3.123
249.30 249.30 5002.61 3.625 3.814 3-M2t 2.770 2.378 2.553 2.553 7.361 3.232
277.00 277.00 5002.87 3.887 4.075 3-M2t 3.030 2.510 2.699 2.699 7.676 3.332
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 4998.80 ft, Outlet Elevation (invert): 4998.53 ft
Culvert Length: 105.00 ft, Culvert Slope: 0.0026
********************************************************************************
Culvert Performance Curve Plot: 31.2
Water Surface Profile Plot for Culvert: 31.2
Site Data - 31.2
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 4998.80 ft
Outlet Station: 105.00 ft
Outlet Elevation: 4998.53 ft
Number of Barrels: 4
Culvert Data Summary - 31.2
Barrel Shape: Circular
Barrel Diameter: 4.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None
Table 46 - Downstream Channel Rating Curve (Crossing: DP 31.2)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 4998.53 0.00 0.00 0.00 0.00
27.70 4999.28 0.75 1.61 0.12 0.35
55.40 4999.65 1.12 2.03 0.17 0.37
83.10 4999.93 1.40 2.31 0.22 0.38
110.80 5000.18 1.65 2.53 0.26 0.39
138.50 5000.39 1.86 2.71 0.29 0.40
166.20 5000.58 2.05 2.87 0.32 0.40
193.90 5000.76 2.23 3.00 0.35 0.41
221.60 5000.93 2.40 3.12 0.37 0.41
249.30 5001.08 2.55 3.23 0.40 0.41
277.00 5001.23 2.70 3.33 0.42 0.42
Tailwater Channel Data - DP 31.2
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 20.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0025
Channel Manning's n: 0.0350
Channel Invert Elevation: 4998.53 ft
Roadway Data for Crossing: DP 31.2
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5003.53 ft
Roadway Surface: Paved
Roadway Top Width: 40.00 ft
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 0 cfs
Design Flow: 7 cfs
Maximum Flow: 7 cfs
Table 47 - Summary of Culvert Flows at Crossing: DP 434
Headwater Elevation
(ft)
Total Discharge (cfs) 434 Discharge (cfs) Roadway Discharge
(cfs)
Iterations
5021.90 0.00 0.00 0.00 1
5022.37 0.70 0.70 0.00 1
5022.58 1.40 1.40 0.00 1
5022.75 2.10 2.10 0.00 1
5022.91 2.80 2.80 0.00 1
5023.04 3.50 3.50 0.00 1
5023.18 4.20 4.20 0.00 1
5023.31 4.90 4.90 0.00 1
5023.45 5.60 5.60 0.00 1
5023.59 6.30 6.30 0.00 1
5023.77 7.00 7.00 0.00 1
5026.66 13.94 13.94 0.00 Overtopping
Rating Curve Plot for Crossing: DP 434
Table 48 - Culvert Summary Table: 434
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation (ft)
Inlet Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet Depth
(ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(ft/s)
0.00 0.00 5021.90 0.000 0.000 0-NF 0.000 0.000 0.000 0.000 0.000 0.000
0.70 0.70 5022.37 0.425 0.472 2-M2c 0.381 0.308 0.308 0.262 2.675 0.661
1.40 1.40 5022.58 0.609 0.681 2-M2c 0.546 0.441 0.441 0.381 3.229 0.814
2.10 2.10 5022.75 0.758 0.851 2-M2c 0.684 0.544 0.544 0.471 3.626 0.914
2.80 2.80 5022.91 0.909 1.005 2-M2c 0.812 0.634 0.634 0.545 3.943 0.991
3.50 3.50 5023.04 1.043 1.145 2-M2c 0.939 0.714 0.714 0.610 4.219 1.054
4.20 4.20 5023.18 1.166 1.279 2-M2c 1.076 0.784 0.784 0.668 4.492 1.108
4.90 4.90 5023.31 1.283 1.413 2-M2c 1.500 0.847 0.847 0.721 4.763 1.155
5.60 5.60 5023.45 1.398 1.549 7-M2c 1.500 0.909 0.909 0.770 4.996 1.197
6.30 6.30 5023.59 1.515 1.694 7-M2c 1.500 0.965 0.965 0.815 5.244 1.235
7.00 7.00 5023.77 1.637 1.869 7-M2c 1.500 1.021 1.021 0.857 5.461 1.270
********************************************************************************
Straight Culvert
Inlet Elevation (invert): 5021.90 ft, Outlet Elevation (invert): 5021.66 ft
Culvert Length: 120.00 ft, Culvert Slope: 0.0020
********************************************************************************
Culvert Performance Curve Plot: 434
Water Surface Profile Plot for Culvert: 434
Site Data - 434
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 5021.90 ft
Outlet Station: 120.00 ft
Outlet Elevation: 5021.66 ft
Number of Barrels: 1
Culvert Data Summary - 434
Barrel Shape: Circular
Barrel Diameter: 1.50 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0130
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None
Table 49 - Downstream Channel Rating Curve (Crossing: DP 434)
Flow (cfs) Water Surface
Elev (ft)
Depth (ft) Velocity (ft/s) Shear (psf) Froude Number
0.00 5021.66 0.00 0.00 0.00 0.00
0.70 5021.92 0.26 0.66 0.03 0.26
1.40 5022.04 0.38 0.81 0.05 0.27
2.10 5022.13 0.47 0.91 0.06 0.28
2.80 5022.21 0.55 0.99 0.07 0.28
3.50 5022.27 0.61 1.05 0.08 0.29
4.20 5022.33 0.67 1.11 0.08 0.29
4.90 5022.38 0.72 1.15 0.09 0.29
5.60 5022.43 0.77 1.20 0.10 0.30
6.30 5022.47 0.81 1.24 0.10 0.30
7.00 5022.52 0.86 1.27 0.11 0.30
Tailwater Channel Data - DP 434
Tailwater Channel Option: Trapezoidal Channel
Bottom Width: 3.00 ft
Side Slope (H:V): 4.00 (_:1)
Channel Slope: 0.0020
Channel Manning's n: 0.0350
Channel Invert Elevation: 5021.66 ft
Roadway Data for Crossing: DP 434
Roadway Profile Shape: Constant Roadway Elevation
Crest Length: 100.00 ft
Crest Elevation: 5026.66 ft
Roadway Surface: Paved
Roadway Top Width: 120.00 ft
APPENDIX F
MONTAVA NATURAL AREAS CONCEPT
MONTAVA
CONTEXT MAP
CONSERVATION EASEMENTS
• City-owned and City as contributor
E. County Road 58
E. County Road 56
E. Douglas Rd.
Richards Lake Rd.
N. Timberline Rd.
Turnberry Rd.
Giddings Rd.
Mountain Vista Dr.
E. Vine Dr.
EXISTING PARKS
THORNTON PARCEL
• Potential purchase by Natural Areas
CITY STORMWATER PARCEL
• Continuation of proposed natural area
WATER’S EDGE EAST
MONTAVA
POTENTIAL NATURAL AREA
NATURAL AREA PROPOSED TRAILS
PARKS MASTER PLAN TRAILS
POTENTIAL TRAIL EXTENSION
N
.
C
ou
n
t
y
R
d
.
11
NO. 8 DITCH
• Possible continuous trail connection
North 0 1.5K 3K 6K Feet
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MONTAVA
NATURAL AREA DESIGN GUIDELINES
UNDULATING, NATURALIZED TOPOGRAPHY
• No sharp angles (no trapezoids or orthogonal geometries); slopes 4:1 preferred
• Smooth transitions (e.g. rounded toe of slope and top of berm)
• Diversity of forms and elevations to: 1) create opportunities to establish a variety of plant communities;
2) create a more dynamic environment for wildlife and people
INTEGRATION OF HABITAT-ENHANCING FEATURES
• Include natural elements that provide diverse cover, forage and nesting materials for pollinators and other
wildlife (e.g. snags, pockets of bare ground for ground-nesting bees, fruit-bearing shrubs, +)
DIVERSE VEGETATION THAT SUPPORTS A RANGE OF HABITAT TYPES + EXPERIENCES
• Feature ecotypic plant communities that correspond to their topographic conditions (e.g. mesic at lowest
levels of detention basin, upland/foothills on sloping terrain), and are self-sustaining (low H2O + maintenance)
• Develop rich, multi-layered structural communities with naturalistic qualities (e.g. meandering clumps of
ground, mid-story and canopy species within a seeded matrix)
+
+
+
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+ +
INTEGRATION OF PLACES FOR RESPITE, GATHERING, AND EDUCATION
• Where appropriate, offer opportunities for outdoor environmental learning that connect community to place,
(e.g. interpretive signage explaining the link between native pollinators and the farm or the benefits of
naturalized stormwater management; an outdoor classrom tied to the new PSD school)
• Provide diverse seating options that accommodate both solitary respite and family gathering
CONNECTED CORRIDORS
• Provide contiguous habitat across the site that supports movement corridors for wildlife
• Provide a range of trail options that allow the community to customize their experience with nature, (e.g.
a primary paved trail with secondary side paths for exploration and the creation of a quieter experience)
USE OF TOPOGRAPHY TO FRAME, SHIELD AND ENHANCE
• Frame scenic views to clustered planting zones, the farm or mountains beyond
• Buffer wildlife from light and sound pollution with strategic berm placement
• Screen infrastructure and housing to enhance the feeling of being surrounded by nature
APPENDIX G
MASTER PLAN ROUTING SCHEMATIC
842
438
POND A2
426
POND E
POND A1
424
430
436 435
OVERFLOW
429
231
34
26
31.3
237
31.1
31
242
74.1
74
77
73
21
36
29 35 35
730
30
229
25
426
426_OVER
75
72
28
POND B
POND D
26.1
POND F
426
MAPLE HILL
SUBDIVISION
STORYBOOK
SUBDIVISION
SOD
FARM
ANHEUSER
BUSCH
WATERGLEN
SUBDIVISION
TRAIL HEAD
SUBDIVISION
L&W CANAL
NO. 8 DITCH
L&W CANAL
N. GIDDINGS RD.
C&S RAILROAD
I-25
RICHARDS LAKE RD. (CR 52)
MOUNTAIN VISTA DR. (CR 50)
MARTIN/MARTIN
C O N S U L T I N G E N G I N E E R S
12499 WEST COLFAX AVENUE, LAKEWOOD, COLORADO 80215
303.431.6100 MARTINMARTIN.COM
NOT FOR CONSTRUCTION
MONTAVA
MASTER DRAINAGE PLAN
DEVELOPED ROUTING SCHEMATIC
D2
DIVERSION SUMMARY
SWMM
ELEMENT
Q100 INFLOW
(CFS)
Q100 DIVERTED
(CFS)
Q100
REMAINING
(CFS)
833.1 408 279 125
842 1000 617 384
OUTFALL SUMMARY
SWMM
ELEMENT Q100 (CFS)
904 138
907 385
909 729
POND SUMMARY
SWMM ELEMENT Q100 IN (CFS) Q100 OUT (CFS) VOLUME (AC-FT)
425 883 819 47
426 1322 760 307
429 1000 390 13.6
430 231 29 5.5
435 468 415 30
436 1562 1548 25
438 732 0 88
426 OVERFLOW 167 138 59
POND A 1807 1042 123
POND A1 76 12 2.8
POND A2 78 3.5 3.0
POND B 62 7.2 2.3
POND C 107 7.1 4.6
POND D 172 8.6 9.0
POND E 174 91 3.2
POND F 166 6.4 11.4
BASIN SUMMARY
BASIN ID AREA (AC) % IMP Q2 (CFS) Q100 (CFS)
A1 12.1 80 11 70
A2 13.3 80 12 78
B 16.6 50 10 62
C1 27.6 50 17 107
C2 82.0 50 38 246
D 47.3 60 26 172
E 83.9 25 25 159
F 46.9 60 25 166
G1 80.4 80 36 249
G2 10.0 80 9 59
H 45.6 10 10 53
I1 58.2 10 8 49
I2 34.8 2 2 11
J1 20.5 50 9 58
J2 22.2 50 18 101
J3 44.5 50 25 158
K1 22.8 60 11 73
K2 60.0 60 27 180
L 110.5 60 55 361
M 42.0 2 2 14
N 86.6 80 61 400
O 60.8 10 12 65
P 30.2 2 2 12
OS-1 45.0 20 11 71
24 33.7 45 44 280
29 268.8 29 192 1000
30 33.5 49 44 231
37 34.6 23 22 148
38 290.7 5 42 469
200 33.6 5 5 46
DESIGN POINT SUMMARY
SWMM ELEMENT Q100 (CFS)
16 15
21 385
31 355
31.1 338
31.2 277
427 319
427.1 6
427.2 9
431 1312
434 7
437 333
439 1043
442 53
725 513
729 415
730 28
822 249
829 513
831 224
833 138
834 1781
841 396
891 418
CONVEYANCE ELEMENT SUMMARY
SWMM
ELEMENT Q100 (CFS)
21 385
24 7
25 512
26 239
26.1 6
26.2 9
27 1780
28 45
29 413
30 27
31 353
31.1 338
31.2 276
31.3 271
34 1043
35 468
72 224
73 139
74 125
74.1 396
75 391
77 1000
229 513
231 1310
237 310
242 493
426 760
426_OVERFLOW 167
CULVERT SIZE BY DESIGN POINT
SWMM
ELEMENT BARRELS-SIZE Q100 (CFS)
HEADWATER DEPTH
(FT)
21 2-8x4 385 4.4
31 2-7x4 355 4.6
31.1 2-8x4 338 4.1
31.2 4-48"D 277 4.1
427 2-6x4 319 4.7
427.1 1-18"D 6 1.6
427.2 1-18"D 9 2.6
431 1-15x10 & 1-5x12 1312 7.6
434 1-18"D 7 1.9
437 3-6x3 333 4.2
822 3-48"D 249 4.6
831 3-48"D 224 4.3
833 2-48"D 138 4.1
834 4-10X5 1781 7.3
841 2-5X5 396 6.2
904 1-60"D 138 13.0
26.2
907
909
904
21
31.1
833
435
729
431 829
730
725
841
831
16
891
437
439
427.2 31
427.1
822
427
POND C
31.2
833.1
31.2
434 834
27
24
442
POND A
425
MARTIN/MARTIN
C O N S U L T I N G E N G I N E E R S
12499 WEST COLFAX AVENUE, LAKEWOOD, COLORADO 80215
303.431.6100 MARTINMARTIN.COM
NOT FOR CONSTRUCTION
MONTAVA
MASTER DRAINAGE PLAN
DEVELOPED ROUTING SCHEMATIC
D1
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MONTAVA
NATURAL AREA
CONCEPTUAL PLAN
GOALS
Create a natural area that:
• provides diverse, functional habitat for
wildlife
• increases opportunities for surrounding
neighborhoods to connect with nature
• enhances connectivity by securing a
movement corridor for people and wildlife
• supports ecological stormwater
management objectives
FUTURE
PSD SCHOOL
FUTURE
NATIVE HILL
FARM
UNDULATING, NATURALIZED
TOPOGRAPHY
North 0 500 1K 2K Feet
USE OF TOPOGRAPHY TO FRAME,
SHIELD AND ENHANCE
DIVERSE VEGETATION
CONNECTED CORRIDORS
• primary circulation path (paved, minimum
10’ wide) with secondary and tertiary
natural surface trails
PLACES FOR RESPITE,
GATHERING AND EDUCATION
• e.g. an outdoor classroom
HABITAT-ENHANCING FEATURES
Mountain Vista Dr.
Larimer Weld Canal
Giddings Rd.
Richards Lake Rd.
FG=4973.00
8+00
EG=4976.7
FG=4973.33
8+50
EG=4976.8
FG=4973.67
9+00
EG=4976.7
FG=4973.94
9+50
EG=4977.1
FG=4974.00
10+00
EG=4977.4
FG=4974.25
10+50
EG=4977.9
FG=4974.50
11+00
EG=4978.2
FG=4974.75
11+50
EG=4978.3
FG=4975.00
12+00
EG=4978.6
FG=4975.25
12+50
EG=4979.3
FG=4975.50
13+00
EG=4979.4
FG=4975.75
13+50
EG=4979.9
FG=4976.00
14+00
EG=4979.7
FG=4976.25
14+50
EG=4980.2
FG=4976.44
15+00
EG=4980.3
FG=4976.67
15+50
EG=4980.5
FG=4976.90
16+00
EG=4981.2
FG=
16+50
EG=4981.3
FG=
17+00
EG=4981.6
FG=
17+50
EG=4980.6
FG=
18+00
EG=4979.8
FG=
18+50
EG=4979.2
FG=
19+00
EG=4978.7
FG=
19+50
EG=4978.3
FG=
20+00
EG=4978.1
FG=
20+50
EG=4978.0
FG=
21+00
EG=4978.0
FG=
21+50
EG=4977.8
FG=
22+00
EG=4977.9
FG=
22+50
EG=4977.7
FG=
23+00
EG=4977.7
FG=
23+50
EG=4977.8
FG=
24+00
EG=4977.9
FG=
24+50
EG=4983.6
FG=
25+00
EG=4973.4
FG=
25+50
EG=4982.9
FG=
26+00
NORTH
P:\P\16010UCS\Dwg\06_EXHIBITS\UCS_PR_DETENTION-CS&CRUMB_REV1_PROFILE.dwg; Msimpson; Page Setup:----; !CON-HALF-SIZE.ctb; 10/20/2016 4:30 PM
7000 S. Yosemite Street I Suite 120 I Centennial CO 80112
Phone (303) 221-0802 / Fax (303) 221-4019
ENGINEERING, ICON INC.
WWW.ICONENG.COM
200'
HORIZ. SCALE: 1" = 200'
PROFILE 2 0 100'
POND SPILLWAY PATH
FG=
8+00
EG=4971.2
FG=
8+50
EG=4971.2
FG=
9+00
EG=4972.0
FG=
9+50
EG=4974.9
FG=
10+00
EG=4975.3
FG=
10+50
EG=4975.3
FG=
11+00
EG=4975.0
FG=
11+50
EG=4975.6
FG=
12+00
EG=4977.9
FG=
12+50
EG=4981.3
FG=
13+00
EG=4973.7
FG=
13+50
EG=4981.1
FG=
14+00
EG=4981.4
FG=
14+50
EG=4981.6
FG=
15+00
EG=4989.4
FG=
15+50
EG=4983.5
FG=
16+00
EG=4984.0
FG=
16+50
EG=4984.0
FG=4972.29
17+00
EG=4984.6
FG=4969.18
17+50
EG=4984.8
FG=4969.44
18+00
EG=4985.0
FG=4969.69
18+50
EG=4985.2
FG=4969.94
19+00
EG=4985.3
FG=4970.18
19+50
EG=4985.5
FG=4970.44
20+00
EG=4985.7
FG=4970.69
20+50
EG=4986.0
FG=4970.94
21+00
EG=4986.2
FG=4971.19
21+50
EG=4986.2
FG=4971.44
22+00
EG=4986.1
FG=4971.69
22+50
EG=4986.4
23+00
NORTH
P:\P\16010UCS\Dwg\06_EXHIBITS\UCS_PR_DETENTION-CS&CRUMB_REV1_PROFILE.dwg; Msimpson; Page Setup:----; !CON-HALF-SIZE.ctb; 10/20/2016 4:26 PM
7000 S. Yosemite Street I Suite 120 I Centennial CO 80112
Phone (303) 221-0802 / Fax (303) 221-4019
ENGINEERING, ICON INC.
WWW.ICONENG.COM
150'
HORIZ. SCALE: 1" = 150'
PROFILE 1 0 75'
POND INLET AND OUTLET PIPE
For revisedwere this based study, the on future land uses land (% uses impervious) shown in inside the Mountain of the AB Vista property Subarea area Plan.
Land use for areas outside of AB remained the existing condition.
Note: 425Pond target the AB flows areas from east previous of the studies. C&S RR See were the further report revised for more to information. meet the AB
*!SB99
108.AC 2 5%
*!SB33.3
84.AC 0 53%
*!SB27
58.AC 4 10%
*!SB70
48.AC 8 30%
*!SB26_B
40.AC 4 10%
*!SB33.2
38.AC 0 58%
*!SB17
36.AC 5 10%
*!SB37
34.AC 6 23%
*!SB94
149.AC 6 5%
*!SB200
33.AC 7 5%
*!SB30
33.AC 5 75%
*!SB10
87.AC 3 5%
*!SB23
31.AC 3 5%
*!SB17_B
28.AC 3 5%
*!SB15.3
27.AC 9 44.5%
*!SB21
22.AC 4 5%
*!SB61
20.AC 9 30%
*!SB44
77.AC 4 7%
*!SB42
53.AC 9 5%
*!SB33.4
41.AC 7 53%
*!SB201
14.AC 8 80%
*!SB27_B
*!SB24 14.AC 4 80%
33.AC 7 45%
*!SB45
54.AC 2 5%
*!SB67
17.AC 1 37%
*!SB39
17.AC 1 5%
*!SB72
*!SB15.1 16.AC 1 5%
12.AC 3 30%*!SB62
11.AC 9 22%
*!SB63
*!SB16 11.AC 8 24%
11.AC 5 7%
*!SB22
10.AC 6 10%
*!SB68
10.AC 0 31%
*!SB66
7.AC 7 43%
*!SB69
6.AC 6 43%
*!SB64
6.AC 2 37%
*!SB65
5.AC 0 52%
*!SB71
3.AC 7 10%
*!SB15.2
3.AC 7 14.1%
*!SB98
25.AC 7 5%
E
VINE DR
INTERSTATE 25 SB
GIDDINGS RD
RICHARDS LAKE RD
MOUNTAIN VISTA DR
N TIMBERLINE RD
COUNTRY CLUB RD
Subbasin Cooper Slough Map Alternatives Analysis (2016)
0 1,100 Feet $
Legend
Cooper Slough Basin Boundary
Anheuser Busch Property
SWMM Model Routing
Cooper Slough Channel
Irrigation Canal
Subbasin Boundary
Future Imperviousness
5 - 20 %
20 - 40 %
40 - 60 %
60 - 80 %
80 - 100 %
!*
Subbasin Label
Subbasin
Name
Area
(Ac)
%
Impv.
C&S/ Crumb Pond
AB Pond 425
C&S Railroad
ANHEUSER BUSCH (AB)
PLANT
BOXELDER CREEK
Canal Spill to
Dry Creek Watershed
Mountain Vista
Diversion
Sod Farm
Diversion
DRY CREEK
WATERSHED
SB36
SB38
SB35 SB106
SB29 SB102
SB32
SB13
SB5
SB31
SB7SB90
SB95
SB11
SB94
SB25
SB34
SB101
SB18
SB26
SB97
SB99
SB105
SB40
SB28
SB10 SB93
SB20
SB19
SB6
SB3
SB96
SB89
SB33.3
SB27
SB44
SB70
SB15.4
SB88
SB8
SB42
SB4
SB17
SB45
SB87
SB37
SB30
SB23
SB33.2
SB200
SB9
SB26_B
SB12
SB24
SB98
SB33.4
SB21
SB15.3
SB61
SB17_B SB67
SB39
SB72
SB86.3
SB201
SB63
SB16
SB104
SB22
SB68
SB27_B
SB15.1
SB69
70
67
62
61
64
65
66
68
71
10
12
98
31
32
28
18
36
38
37
42
45
427
432
431
437
940
905
877
875 874
869
879
860
861
863
873
540
909
912
716
713
707
704
811
906
866
935
813
814
936
929930
808
809
807
817818
939 938
795
560
530
529
790
915
544
543
542
536
533
539
537538
541
535
534
933
932
918
559
799
547
548
730
726
826
941
723
727
823
831
830
822
857
819
856
729
735
725
829
834
744
845
844843
839
841
833
7436
15.2
7435
7437
74327430
7431
7416
72107417
7295
7101
7294
7293
7102
7244
7240
633
634
812
928
610
618
617
615
616
613
608
828
855
842
937
602
601
7424
999
419
408
411
421
917
916
914
913
902
903
901
907
472
473
474
471
470
433
440
415
416
413
406
436
435
426
430
424
428
425
438
415.4
66
6
29
35
36
244
41
7
74
186
32
77
89
65
31
75
26
102
5
28
16
73
295
20
34
106
235
305
94
302
231
247
234
248
95
71
567
90
212
240
301
38
211
72
70
242
237
96
941
279
44
99
97
88
15.2
210
42
12
24
101
218
297
10
225
306
27
4
30
13
25
232
223
8
105
37
216
601D
227
299
229
293
23
290
228
214
45
236
602D
289
18
277
270
294
278
93
263
812D
264
76
262
213
268
438_OUT
819
261
617L
615D
272
935L
100
610D
266
273
618L
869L
78
265
286
249
616L
427_OUT
415.4_OUT
215
217
601L
938
602L
433_OUT
610L
432_OUT
INTERSTATE 25 SB
E VINE DR
GIDDINGS RD
E MULBERRY ST
RICHARDS LAKE RD
MOUNTAIN VISTA DR
N TIMBERLINE RD
E COUNTY ROAD 50
E COUNTY ROAD 48
S TIMBERLINE RD
E LINCOLN AVE
SWMM Cooper Model Slough Routing Alternatives Map Analysis (2016)
0 0.2M5iles $
Legend
Cooper Slough Basin Boundary
Boxelder Watershed
Anheuser Busch Property
Cooper Slough
Boxelder Creek
Irrigation Canal
SWMM Subbasin
SWMM Routing
SWMM Junction
X SWMM Flow Divider
#*
SWMM Outfall
" SWMM Detention
C
O
O
P
E
R
S
L
O
U
G
H
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INTERSTATE HWY 25
ANHEUSER BUSCH (AB)
PLANT
BOXELDER CREEK
Sod Farm Diversion
Q diverted = 875 cfs
Proposed Sod Farm Pond
S = 174 AF
Max WSE = 5033.4
Proposed Sod Farm Pond Berm
Elev. = 5037.0
Sod Farm Pond Outlet Pipe
Proposed 36" RCP
Q = 55 cfs
Mountain Vista Diversion
2 Location Options
Qcfs = 125 cfs Q = 304
Q = 179 cfs
Assume Full Development of
AB Lands with 100yr -> 2yr
Detention (On-Site)
Mountain Vista Diversion
May Be Conveyed In
Open Channel or Pipe
New Bridge for
Open Channel Option
Proposed C&S/ Crumb
Detention Pond (426)
S = 220 AF
(Prop. Grading = 230 AF)
Max WSE = 4980.7
Qin = 1,574 cfs
Proposed C&S/ Crumb
Outlet Pipe - Under L&W Canal
2 - 8' x 3' RCBC, 1,531-LF
Q = 548 cfs (550 cfs Target)
Improved AB 425 Pond Outlet
Remains Connected to L&W Canal
Q = 392.5 cfs
Existing AB Pond 425
Regrade to Provide
S = 65 AF
Max WSE = 4982.8
Remove Existing Flow Spill At CSRR
Provide Open Channel to Convey
Flows on West Side of RR
Q = 1504 cfs
Combined Outlow From
C&S/ Crumb and L&W Canal Spill
Q = 654 cfs
Proposed E. Vine Dr. Culverts
(3) 8' x 4' RCBC
Q = 702 cfs
(Sized for 772 cfs - ESDF CLOMR)
Proposed E. Mulberry St. Culverts
(3) 10' x 4' RCBC
Q = 961 cfs
C
OO
P
E
R
SL
O
U
G
H
Canal Spill to Dry Creek
Q = 0 cfs
Canal Spill
Q = 2 cfs
Q = 1,527 cfs
Q = 1,285 cfs
Q = 180 cfs
Q = 217 cfs
Q = 1,000 cfs
Q = 125 cfs
NO. 8 OUTLET DITCH
LARIMER & WELD CANAL
COLORADO & SOUTHERN RAILROAD
BOXELDER WATERSHED
DRY CREEK WATERSHED
COOPER SLOUGH WATERSHED
MOORE AREA IMPROVEMENTS
FROM 2006 MASTER PLAN NOT
INCLUDED IN 2014 UPDATE
BLACK HOLLOW OUTFALL CHANNEL
IMPROVEMENTS FROM 2006 MASTER
PLAN NOT INCLUDED IN 2014 UPDATE
Q = 125 cfs
N. Poudre Reservoir No. 6
Add 8-inch Iron Sill Plate to Spillway
Q = 547 cfs
S = 679 AF
Max WSE = 5163.2'
Canal Spill (F)
Q = 423 cfs
Additional Channel and Canal
Improvements Needed Downstream
SH-14
INTERSTATE 25 SB
E VINE DR
GIDDINGS RD
E MULBERRY ST
RICHARDS LAKE RD
MOUNTAIN VISTA DR
E COUNTY ROAD 50
E COUNTY ROAD 48
S TIMBERLINE RD
E COUNTY ROAD 52
COUNTRY CLUB RD
E LINCOLN AVE
Cooper Alternatives Slough Analysis Alternatives Summary Map Analysis (2016)
0 0.2M5iles $
Legend
Cooper Slough Basin Boundary
C&S/ Crumb Pond
Sod Farm Pond
AB Pond 425
Cooper Slough
Boxelder Creek
Irrigation Canal
! ! ! ! ! ! Drainage Paths
!
! !
!
!
Anheuser Busch Property
! !
! ! !!
! ! ! ! !
! !
!
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! ! ! ! !
!!
! ! ! ! !! !
! !! !! ! ! ! !
! ! !
! ! !
ANHEUSER BUSCH (AB)
PLANT
BOXELDER CREEK
QIN: Sod Farm Pond
100yr = 856cfs
10yr = 90cfs
2yr = 43cfs
QOUT: 0cfs
No6 Outlet Ditch
(Decreed = 125cfs)
100yr = 408cfs
10yr = 257cfs
2yr = 177cfs
No8 Outlet Ditch
(Decreed = 125cfs)
100yr = 522cfs
10yr = 258cfs
2yr = 177cfs
QIN/OUT: C&S/ CrumbPond (426)
Connected to L&W Canal
100yr = 1306/661cfs
10yr = 183/91cfs
2yr = 74/19cfs
QIN/OUT: Existing AB Pond 425
Connected to L&W Canal
100yr = 920/565cfs
10yr = 243/76cfs
2yr = 106/24cfs
Existing Flow Spill At CSRR
100yr = 1794cfs
10yr = 228cfs
2yr = 83cfs
Cooper Slough at E. Vine Dr.
100yr = 590cfs
10yr = 28cfs
2yr = 9cfs
Cooper Slough at E. Mulberry St.
QIN/QOUT
100yr = 960/520cfs
10yr = 632/110cfs
2yr = 174/84cfs
C
O
O
PE
R
S
L
O
U
G
H
Canal Spill to Dry Creek
Q = 0 cfs
NO. 8 OUTLET DITCH
LARIMER & WELD CANAL
COLORADO & SOUTHERN RAILROAD
BOXELDER WATERSHED
DRY CREEK WATERSHED
COOPER SLOUGH WATERSHED
QIN/OUT: N. Poudre Reservoir
No. 6
100yr = 6534/754cfs
10yr = 2477/178cfs
2yr = 1320/80 cfs
Canal Spill (F)
100yr = 558cfs
10yr = 12cfs
2yr = 0cfs
Cooper Slough
100yr = 178cfs
10yr = 98cfs
2yr = 74cfs
SH-14
Overtopping Flow
100yr = 342cfs
10yr = 12cfs
2yr = 10cfs
Mt. Vista Crossing
100yr = 901cfs
10yr = 234cfs
Mt.110cfs Vista Crossing 2yr =
100yr = 1390cfs
10yr = 228cfs
2yr = 82cfs
Cooper Slough at RR
100yr = 802cfs
10yr = 160cfs
2yr = 80cfs
Existing Flow Spill At CSRR
100yr = 459cfs
10yr = 0cfs
Existing Flow Spill At CSRR
100yr = 1335cfs
10yr = 228cfs
2yr = 82cfs
100yr = 47cfs
10yr = 13cfs
2yr = 5cfs
Existing Flow
100yr = 1264cfs
10yr = 568cfs
2yr = 294cfs
INTERSTATE 25 SB
E VINE DR
E MULBERRY ST
GIDDINGS RD
TURNBERRY RD
RICHARDS LAKE RD
MOUNTAIN VISTA DR
N TIMBERLINE RD
S TIMBERLINE RD
E COUNTY ROAD 48
E COUNTY ROAD 52
COUNTRY CLUB RD
E LINCOLN AVE
¦¨§25
¦¨§25
Cooper Slough Selected Plan (2017)
Existing Conditions Flow
0 0.25 $
Miles
Legend
Cooper Slough Basin Boundary
Cooper Slough
Boxelder Creek
Irrigation Canal
!! !! !! Drainage Paths
!
!!
!
!
Anheuser Busch Property
DocuSign Envelope ID: 9CBD9275-509D-42CE-9AC6-97B319997DCA