HomeMy WebLinkAboutCOLLEGE & TRILBY MULTIFAMILY COMMUNITY - PDP220009 - SUBMITTAL DOCUMENTS - ROUND 3 - DRAINAGE REPORTPRELIMINARY DRAINAGE REPORT
FOR
COLLEGE & TRILBY MULTI-FAMILY
COMMUNITY
Prepared For:
ZOCAL COMMUNITY DEVELOPMENT
455 SHERMAN STREET, SUITE 250
COLORADO, DENVER 80020
KOLBY O’HERRON
(303) 820-8611
November 15th 2023
Project No. 39823.00
Prepared By:
JR Engineering, LLC
2900 South College Avenue, Suite 3D
Fort Collins, CO 80525
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TABLE OF CONTENTS
TABLE OF CONTENTS ......................................................................................................................... ii
APPENDIX ..................................................................................................................................... iii
Engineer’s Certification Block ........................................................................................................... iv
GENERAL DESCRIPTION AND LOCATION ............................................................................................ 1
LOCATION ..................................................................................................................................... 1
DESCRIPTION OF PROPERTY .......................................................................................................... 1
MASTER DRAINAGE BASIN DESCRIPTION ....................................................................................... 2
FLOODPLAIN SUBMITTAL REQUIREMENTS ..................................................................................... 3
DRAINAGE BASINS AND SUB-BASINS ................................................................................................. 3
MAJOR BASINS AND SUB-BASINS ................................................................................................... 3
EXISTING SUB-BASIN DESCRIPTION ................................................................................................ 4
EXISTING OFFSITE DRAINAGE BASINS ............................................................................................ 5
PROPOSED SUB-BASINS DESCRIPTIONS ......................................................................................... 5
ONSITE SWMM SUB-BASINS DESCRIPTIONS .................................................................................. 9
OFFSITE SWMM SUB-BASINS DESCRIPTIONS ............................................................................... 10
PROJECT DESCRIPTION .................................................................................................................... 14
PROJECT DESCRIPTION ................................................................................................................ 14
PROPOSED DRAINAGE FACILITIES .................................................................................................... 14
GENERAL CONCEPT ..................................................................................................................... 14
WATER QUALITY/ DETENTION FACILITIES .................................................................................... 14
LOW IMPACT DEVELOPMENT ...................................................................................................... 14
DRAINAGE DESIGN CRITERIA ........................................................................................................... 15
REGULATIONS ............................................................................................................................. 15
FOUR-STEP PROCESS TO PROTECT RECEIVING WATERS ............................................................... 15
DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS ........................................................... 17
HYDROLOGIC CRITERIA ................................................................................................................ 18
HYDRAULIC CRITERIA ................................................................................................................... 18
FLOODPLAIN REGULATIONS COMPLIANCE ................................................................................... 19
MODIFICATIONS OF CRITERIA ...................................................................................................... 19
EROSION CONTROL ..................................................................................................................... 19
CONCLUSIONS ................................................................................................................................. 19
COMPLIANCE WITH STANDARDS ................................................................................................. 19
DRAINAGE CONCEPT ................................................................................................................... 19
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APPENDIX
Appendix A – Figures
Appendix B – Hydrologic Calculations
Appendix C – Hydraulic Calculations
Appendix D – Water Quality Calculations
Appendix E – Reference
Appendix F – Maps
Appendix G – LID Exhibit
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Engineer’s Certification Block
I hereby attest that this report for the final drainage design for the College & Trilby Multi-Family
Community was prepared by me or under my direct supervision, in accordance with the provisions of the
Fort Collins Stormwater Criteria Manual. I understand that the City of Fort Collins does not and will not
assume liability for drainage facilities designed by others.
Joseph M. Frank, PE
Registered Professional Engineer
State of Colorado No. 53399
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GENERAL DESCRIPTION AND LOCATION
LOCATION
The site is located in The Southeast Quarter of Section 11, Township 6 North, Range 69 West of the 6th
P.M. in the City of Fort Collins, Larimer County, Colorado. More specifically, the site is a 39.1803 acre
property that is currently undeveloped. The site borders College Ave to the East, to the South, the Site
Borders Trilby Road, South Gate Church, and a right in and right out with access to Ziggy's Coffee. To
the west, the site borders a detention pond that controls runoff for the First Free Will Baptist Church,
the Skyview South Fist Filing Subdivision, and a social services organization owned by Foothills Gateway
Inc. To the north, the site borders Hazel Self Storage, two current vacant parcels of land, and a portion
of Skyview Drive.
DESCRIPTION OF PROPERTY
The site generally drains west to east at a 10% to 4% slope. The majority of the site is undeveloped and
has several existing farm buildings scattered throughout the site. There are two existing culverts crossings
under College Avenue along the eastern boundary of the subject property. The Two existing culverts
drain from the site east under College Avenue. The two crossings are identified as south and north. The
north crossing is a 48" pipe that gets downsized to a 30" pipe downstream. The south crossing is a 24"
pipe. College Avenue creates two inadvertent detention ponds on the subject property due to
attenuation/ponding of storm runoff. The inverts of the culverts are such that standing water remains after
rainfall events, creating wetland areas on the site. The site is located in the Fossil Creek Basin, specifically
within the Stone Creek sub-Basin. The Stone Creek master drainage plans identify these two inadvertent
detention areas and specify that these be preserved with the future development of the site. The North
Loudon Ditch and Reservoir Company has a 30” gravity irrigation line that goes through the site adjacent
and along the northern boundary of the site. The site currently has a small shed and gravel access road;
the majority of the site is primarily vacant with native grass. The Natural Resources Conservation Service
(NRCS) soil survey shows that approximately half of the soils on site are composed of type B soils, which
have a mild infiltration and runoff rate. The remaining site is made up of Type C and D soils, which are
characterized by a lower infiltration rate and corresponding higher runoff rates. For additional information,
refer to the NRCS soil map within Appendix A of this report.
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MASTER DRAINAGE BASIN DESCRIPTION
The site is located in the Fossil Creek Basin, specifically within the Stone Creek sub-Basin. The Stone
Creek Basin - Selected Plan of Improvements", Icon, September 2018 calls out two areas for onsite water
quality and detention. The Stone Creek master plan specifies that a smaller pond be built near the existing
right in and right out by Ziggy's Coffee and College Ave. Currently, that site drains through a 24" RCP
and outfalls across College Ave. The smaller pond will have a riprap-lined overflow channel that will outfall
north into the larger pond. The City of Fort Collins has two options for detaining runoff on the site.
Option A – construct an overflow channel between the two detention ponds and upsize the northern
30" pipe downstream of the 48" outfall to a 48" pipe. This option significantly increases the allowed release
rate onsite and lowers the required detention volume.Option B –the onsite overflow channel is not
built/ or built, and the existing 30" RCP storm pipe is not upsized. With each option, the proposed project
will need to be in continuity with the City's Stone Creek SWMM model, and the peak release rate for
either option is to not be exceeded. Wilson and Company is currently working on the capital
improvements for the College and Trilby intersection, the City's Stone Creek SWMM model, and is
working on modifying the design recommendations called out in the 2018 Strone Creek Master Plan by
Icon Engineering to treat and detain storm water for the College and Trilby intersection improvements.
JR Engineering has incorporated the drainage improvement from College and Trilby into the site by
following the general recommendations from the Wilson and Company's design and the 2018 Stone Creek
Master Plan. JR Engineering is proposing that the smaller pond will be a water quality pond, an overflow
channel will be built, and the runoff will be detained in the larger pond, but the 30" RCP will not be upsized
to a 48" RCP. Currently, the site is zoned as general commercial, but the site will be re-purposed as a
medium-density mixed-use neighborhood district. The North Loudon Ditch that goes along the northern
portion of the site is not anticipated to influence the drainage on site since it is currently piped in a 30”
RCP gravity line throughout the site.
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FLOODPLAIN SUBMITTAL REQUIREMENTS
The site is on FEMA FIRM panels 08069C1200F and 08069C1000F. The flood map for this location has a
status of "not printed". This means that the entire area of the panel is in a single flood zone, so FEMA
chose to economize and not create a printable image for this location. The site lies within FEMA Zone X,
areas which are determined to be outside the 0.2% annual chance floodplain. The site is not located within
a FEMA regulated floodplain, as shown in Appendix A in the FEMA attachments. The site is also not located
in the City of Fort Collins Floodplain, as shown in Appendix A in the City of Fort Collins Flood map.
DRAINAGE BASINS AND SUB-BASINS
MAJOR BASINS AND SUB-BASINS
The College and Trilby site is 39.1803 acres; the site will be developed into a multi-family residential
community with a recreation facility and will include onsite and offsite detention. The site is located in the
Fossil Creek basin. The Fossil Creek drainage basin extends along the south end of Fort Collins, from the
foothills across Interstate 25 past CR 5. It encompasses 32 square miles in the City of Fort Collins and
Larimer County. More specifically, the site is in the Stone Creek sub-basin of the Fossil Creek Tributary.
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EXISTING SUB-BASIN DESCRIPTION
The existing site’s hydrology was modeled within the 2018 Stone Creek basin master plan. EPA
SWMM was used to model the hydrology of the site. Currently, the City has accepted an updated
hydrologic model for the Stone Creek master plan after some inaccuracies were found when
Wilson and Company modeled the College and Trilby Capital Improvements for the site. The
site is anticipated to be constructed after capital improvements for the College and Trilby
Intersection have been made. JR Engineering is currently referencing the InterimSC_100Yearprop
SWMM model. The following is a list of modifications JR Engineering made to the April 2022
Proposed College and Trilby CIP SWMM Model SC_100YearPROP in EPA SWMM 5.1.015.
1.)Made basin B910 to be 20% impervious to represent the true interim condition as
modeled in the 2022 Stone ___Creek existing corrected effective SWMM model i.e.
SC_100YearCE.
2.)Made the orifice of P366-WQCVOrifice orifice smaller to drain the WQCV in approx.
40 hr for the interim …..undeveloped condition.
3.)Updated the interim stage storage for P366 and lowered the pond half a foot from 5019.50
to 5019.00 from __Wilson and Company proposed grading.
4.)Raised the stage of the weir P366-EOS by 0.50 ft since the pond invert was lowered half
a foot.
5.)Lowered junction J910 by 0.50 ft to 5017.00.
6.)Modified the grading / stage storage of P366 to fit and accommodate access to the
Development at Trilby and College so that right of way can be dedicated for the right in,
right out with access to the site.
7.)Deleted Element L366_SF3 as requested by Wilson and Company.
This model includes the proposed drainage and storm system improvements, basin modifications,
and increased imperviousness due to the College and Trilby intersection improvements, which
are anticipated to be in place while the College & Trilby Multi-Family Community is developed.
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EXISTING OFFSITE DRAINAGE BASINS
Currently, the site collects offsite runoff from three locations: Runoff from the southern portion
of West Trilby Road drains onto the site via a CMP FES that crosses Trilby Road and drains
directly onto the site. Runoff from the Northern portion of Trilby Road drains onto the site via
a grass swale in confluence with upstream runoff, as shown in the offsite SWMM Map by Wilson
and Company within Appendix E. An existing drainage pan goes south to north in the backyards
of Skyview South First Filing as shown in the Trilby College Ex-Drainage Exhibit in Appendix G.
The runoff then goes offsite to an adjacent swale along Gateway Center Drive. In the 100-year
event, it’s anticipated that the runoff will overflow within the back of the yards. The estimated
capacity of the existing drainage pan has been modeled in SWMM, and the capacity is shown in
Appendix C of this report.
PROPOSED SUB-BASINS DESCRIPTIONS
Basin A1, 1.90 acres and 15.6 % impervious, is composed of open space, a proposed walk, and a
swale where runoff will be conveyed to design point 1a, where it will drain onto Rover Way via
a chase drain.
Basin A2, 1.76 acres and 51.6% impervious, is composed of multi-family residential units and an
alley. The runoff from this basin will be conveyed to an inlet at design point 2a.
Basin A3, 0.31 acres and 72.3% impervious, is composed of multi-family residential units, onsite
parking, and alley access. The runoff from this basin will be conveyed to a sump inlet at design
point 3a.
Basin A4, 1.65 acres and 47.4% impervious, is composed of multi-family duplex residential units,
paved walks and paved driveways, and a residential local street Rover Way. The runoff from this
basin goes to design point 4a at an on-grade inlet.
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Basin A5, 0.42 acres and 59.3% impervious, is composed of a local residential street, paved walk,
and paved driveways. The runoff from this basin goes to design point 5a at an on-grade inlet.
Basin A6, 0.75 acres and 69.4% impervious. This basin is composed of a collector Street Mars,
paved walk, and multi-family residential units. The runoff from this basin goes to an on-grade inlet
at design point 6a.
Basin A7, 0.44 acres and 78.2% impervious, is composed of a collector street Mars, paved walk.
The runoff from this basin goes to an on-grade inlet at design point 7a.
Basin A8, 1.23 acres and 62% impervious, is composed of a collector street Mars, paved walk,
and multi-family residential units. The runoff from this basin goes to an on-grade inlet at design
point 8a.
Basin A9, 0.30 acres and 65.6% impervious this basin is composed of a collector street Mars,
paved walk, and paved driveways. The runoff from this basin goes to an on-grade inlet at design
point 9a.
Basin A10, 0.18 acres and 63.2% impervious, is composed of a collector street Mars, paved walk.
The runoff from this basin goes to an on-grade inlet at design point 10a.
Basin B1, 0.63 acres and 77.5% impervious, comprises a residential alley, multi-family residential
units, and paved driveways. The runoff from this basin drains to design point 1b at a sump inlet.
Basin B2, 1.17 acres and 9.1% impervious, comprises open space and a side swale that runs
adjacent to the property line. The runoff from this basin drain into a type D sump inlet at design
point 2b in confluence with upstream runoff from the capital improvements of Trilby College.
Basin C1.1, 3.84 acres and 47% impervious, comprised of residential duplex units, paved walks
and paved driveways, and a local residential street. The runoff from this basin drains into an on-
grade inlet at design point 1.1C.
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Basin C1.2, 0.72 acres and 37.8% impervious, comprised of residential multi-family units, paved
walks and paved driveways, and a local residential street. The runoff from this basin drains into
an on-grade inlet at design point 1.2C.
Basin C1.3, 0.18 acres and 68.1% impervious, comprised of residential duplex units, paved walks
and paved driveways, and a local residential street. The runoff from this basin drains into an on-
grade inlet at design point 1.3C.
Basin C2, 1.12 acres and 57% impervious, is composed of paved walk and paved and a local
residential street. The runoff from this basin drains into an on-grade inlet at design point 2C.
Basin C3, 1.81 acres and 76.1% impervious is composed of paved driveways, a paved local
residential alley, onsite park spaces, and multi-family residential units. The runoff from this basin
drains into an on-grade inlet at design point 3a.
Basin C4, 2.55 acres and 58% impervious, is composed of residential multi-family units, walks, and
a local collector, Mars Drive. Runoff from this basin drains to a sump inlet at design point 4c.
Basin C5, 1.34 acres and 64% impervious, is composed of residential multi-family units, walk, and
a local collector Mars Drive. Runoff from this basin drains to a sump inlet at design point 5c.
Basin D1, 0.29 acres and 82.5% impervious, is composed of a local residential street and paved
walk. The runoff from this basin drains to a sump inlet at design point d1.
Basin D2, 0.50 acres and 67% impervious is comprised of a local residential street and paved walk.
The runoff from this basin drains to a sump inlet at design point d2.
Basin E1, 0.42 acres and 81.3% impervious is comprised of a local residential alley, and multi-
family residential units. The runoff for this basin will be treated for water quality in pond P366.
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Basin E2, 0.75 acres and 77.3% impervious is comprised of a road (Lunar Court) and a residential
Cul-de-Sac. Runoff from this basin will drain into a sump inlet and will be treated for water quality
in Pond 366.
Basin E3, 0.23 acres and 78.1% impervious is comprised of a private parking lot. The runoff from
this basin drains to design point 3e.
Basin E4, 0.17 acres and 62.6% impervious is comprised of a recreation facility. Runoff from this
basin drains directly into the adjacent water quality pond P366.
Basin E5, 0.38 acres and 36.2% impervious is comprised of a recreation facility. Runoff from this
basin drains directly into the water quality pond P366.
Basin E6 0.78 acres and 6.7% impervious is comprised of the water quality detention pond P366.
Basin F1, 1.20 acres and 31.9% impervious, is composed of the overflow channel between pond
P366 and pond P363, as shown within section CC on the drainage maps
Basin OF1, 0.52 acres and 34.3% impervious, is composed of an overflow swale that captures
runoff from Skyview South, First Filing. Runoff in the overflow swale is routed to detention pond
P363.
Basin G1, 1.51 acres and 73.7% impervious, is composed of a residential alley, paved walk, paved
driveways, and multi-family residential units. The runoff from this basin drains to an on-grade inlet
within the alley at design point 1g.
Basin G2, 0.62 acres and 83.0% impervious. This basin is composed of a residential alley, paved
driveways, and multi-family residential units. The runoff from this basin drains to an on-grade inlet
at design point 2g.
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Basin G3 has 1.06 acres, and 52.4% is impervious. This basin is composed of walks and residential
units. The runoff from this basin drains to a series of inlets represented by design point 3g.
Basin G4, 0.82 acres and 80.7% impervious is composed of residential alleys, paved driveways,
and multi-family residential units. The runoff from this basin drains to a sump inlet at design point
4g.
Basin H1 has 5.88 acres and is 8.7% impervious. This basin is composed of the detention facility
P363 for the site. Runoff from this basin drains and is released to an outlet structure, where it
goes directly east of the site under College Ave to the Prairie Dog Meadows Natural Area.
ONSITE SWMM SUB-BASINS DESCRIPTIONS
Basin CT-1, 24.44 Acres and 56.2% impervious is composed the College & Trilby Multi-Family
development. Runoff from this basin will be treated for water quality in the ADS isolator rows.
Basin CT-2, 5.31 Acres and 48.3% impervious is composed the College & Trilby Multi-Family
development, recreation center and onsite water quality pond P366. Runoff from this basin will
be treated for water quality in the ADS isolator rows.
Basin CT-3, 1.20 Acres and 31.9% impervious is composed of the overflow channel and adjacent
lots. Runoff from this basin will drain and be treated in pond P366.
Basin CT-4, 5.88 Acres and 8.7% impervious is composed of pond P363.
Basin OF-1, 0.53 Acres and 34.3% impervious is composed of the overflow channel on the
western boundary of the site.
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OFFSITE SWMM SUB-BASINS DESCRIPTIONS
The offsite basins are shown in Appendix E, and some additional offsite basins have been broken
up and are now shown in Appendix F, as shown within the proposed drainage map. The offsite
basins are part of the Stone Creek master plan and have recently been modified to conform to
the Stone Creek basin plan. The offsite basins B930, B840, and B930 have been modified to
conform to the proposed site grading and observed offsite drainage patterns. In addition, since
B910B was part of the Trilby frontage and part of the existing site, this basin was modified, and
basins OS, OS2, OS3, OS4 have been added to the frontage on Trilby Ave. JR Engineering has
added information from the development adjacent to the Trilby Frontage in Appendix E of this
Report. Basins OS5, and OS6 were added to represent the frontage for South College Ave. The
updated basins and delineations are shown in the proposed drainage map in Appendix F of this
report.
Basin OS1, 0.73 acres and 87.4% impervious is composed of the intersection of Mars Drive and
West Trilby Road. Runoff from the intersection drains to an on-grade inlet, where it is piped and
treated in a water-quality pond P366. From then on, the runoff is piped to the detention facility
P363.
Basin OS2, 2.02 acres, 48.6% impervious, is composed of the northern portion of West Trilby
Road. The runoff from this basin drains into a roadside swale. The runoff drains to an inlet and is
piped and treated in a water-quality pond P366. From then on, the runoff goes into a channel
where it outfalls to the detention facility P363.
Basin OS3, 0.32 acres and 71.5% impervious, is composed of the south portion of West Trilby
Road and receives runoff. The runoff drains to a type D inlet from the CIP project and is piped
and treated in a water quality pond P366. From then on, the runoff goes into a channel where it
outfalls to the detention facility P363.
Basin OS4, 0.40 acres and 90.8% impervious this basin is composed of the south side of West
Trilby Road and includes the ROW improvements associated with the College and Trilby project.
The runoff from this basin drains into an on grade inlet built in Ridgewood Hills PUP First Filing.
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Basin OS5, 1.69 acres and 76.3% impervious this basin drains undetained to an existing 10’ type
R inlet on the western portion of South College Ave directly adjacent to the pond outfall for
Pond P366.
Basin OS5, 1.69 acres and 76.3% impervious this basin drains undetained to an existing 10’ type
R inlet on the western portion of South College Ave directly adjacent to the pond outfall for
Pond P366.
Basin OS6, 0.79 acres and 78.6% impervious this basin drains undetained along the southern
portion of South College Ave to a sump Inlet down stream of the site.
Basin B770A, 0.36 acres, and 100.0% impervious, is composed of the southern portion of East
Trilby Road and the College and Trilby intersection. Runoff from this basin drains to an on-grade
type R inlet. Runoff is then piped to the water quality pond P366, and from there on the runoff
is routed in the overflow channel to the detention pond P363.
Basin B770B, 1.52 acres 89.0% impervious, composed of the eastern portion of south College
Ave South of Trilby road. Runoff from this basin drains to an on-grade type R inlet.
Basin B900A, 0.48 acres and 95.0% impervious, is composed of east Trilby Road. Runoff from this
basin drains to an on-grade type R-inlet; runoff is then piped to the water quality pond P366, and
from there on, the runoff is routed in the overflow channel and outlet structure to the detention
pond P363.
Basin B900B, 0.56 acres and 100.0% Impervious. This basin is composed of the eastern portion
of South College Ave north of the College and Trilby intersection. Runoff from this basin drains
to an on-grade type R-Inlet. The runoff is piped to the water quality pond P366, and from there
on, the runoff is routed in the overflow channel and outlet structure to detention pond P363.
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Basin B910C, 1.30 acres and 90.0% impervious, this basin is composed of the northwestern
quadrant of the College and Trilby intersection. Runoff from this basin drains to an on-grade
type-R inlet. The runoff is piped to the water quality pond P366, and from there on the runoff is
routed in the overflow channel and outlet structure to detention pond P363.
Basin B920C, 1.71 acres and 66.0% impervious, is composed of commercial development, the
College and Trilby intersection, and is situated on the southwest quadrant of the College and
Trilby intersection. Runoff from this basin drains to an on-grade type R-Inlet; runoff is piped to
the water quality pond P366, and from there on, the runoff is routed in the overflow channel and
outlet structure to detention pond P363.
Basin B910D, 0.46 acres and 100.0% impervious. This basin is composed of the right in and right
for Ziggy's Coffee. Runoff from this basin drains to an on-grade type R inlet; runoff is then piped
to the water quality pond P366, and from there on, the runoff is routed in the overflow channel
and outlet structure to detention pond P363.
Basin B920A, 3.82 acres and 20.0% impervious. This basin is composed of the southern portion
of West Trilby Road. Runoff from this basin drains within a swale to a sump inlet; runoff is then
piped to the water quality P366, and from there on, the runoff is routed in the overflow channel
and outlet structure to detention pond P363.
Basin B920B, 0.99 acres and 63.0% impervious. This basin is composed of the southern portion
of West Trilby Ave. The runoff from this basin is conveyed within a swale to a sump inlet; runoff
is then piped to the water quality pond P366, and from there on, the runoff is routed in the
overflow channel and outlet structure to detention pond P363.
Basin B910A, 2.99 acres and 74% impervious, is composed of Southgate Church and Ziggy's
Coffee. This basin drains to a detention pond situated near the northwest corner of the basin
and ultimately passes through pond P366 and Pond P363.
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B830, 7.82 acres and 40% impervious; this basin is composed of Skyview South First Filing. The
runoff from this basin drains into a pan along site the eastern portion of the back of lots within
the subdivision. The runoff from this pan will overtop and go into an adjacent swale in the 100-
year event where the runoff will be detained in pond P363. This basin was modified from the
current corrected effective model since offsite runoff from this basin is left untreated and drains
under a culvert as shown in the First Free Will Baptist Church drainage Map in Appendix E.
B840 11.71 acres and 45 % impervious; this basin is composed of Skyview South First Filing. The
runoff from this basin drains into a pan along site the eastern portion of the back of lots within
the subdivision. The runoff from this pan will overtop and go into an adjacent swale, where the
runoff will be detained in detention pond P363.
B930 4.71 acres and 31.2 % impervious; this basin is composed of the First Will Baptist Church
at 320 W Trilby Road. Runoff from this basin is detained in detention pond P930. Runoff from
this basin is released and ultimately is treated for water quality within pond P366 and is detained
within pond 363.
B876 16.97 acres and 60% impervious; this basin is made up of a social services organization
owned by Foothills Gateway Inc. that is composed of buildings and parking lots. The runoff from
this basin drains to an existing swale on the western boundary of the College and Trilby site.
B850 17.24 acres and 10% impervious; this basin border the northern boundary of the site and
is composed of Mars Collector Roadway and a self-storage facility.
For additional information on offsite drainage basins and ponds in series, refer to the Wilson and
Company Stone Creek Proposed Conditions SWMM Schematic area of College and Trilby
Intersection Enhancements Storm System dated 3-25-22 within Appendix E and the Proposed
SWMM map located in Appendix F.
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PROJECT DESCRIPTION
PROJECT DESCRIPTION
College & Trilby is a residential multi-family development that will consist of a recreation center,
alleys, and local and collector roadways. The College & Trilby site will hold detention and water
quality improvements for the College and Trilby in continuity with the Stone Creek Master Plan.
PROPOSED DRAINAGE FACILITIES
GENERAL CONCEPT
The proposed improvements to the Trilby and College site will result in the developed condition
being treated for water quality and detained. Low-impact development best management
practices are proposed to improve the quality of runoff and aid in reducing peak flows. Specifically,
ADS isolator rows are proposed near the central portion of the site to treat and provide water
quality for the majority of the development. The remaining portion of the development will be
treated for water quality in the smaller water quality pond along with the tributary area from the
capital improvements to the Trilby and College intersection.
Runoff from the site is captured in inlets located in the alleys and on grade and sump inlets along
the curb and gutter. Runoff is conveyed in storm sewers, along the curb and gutter, and via surface
flow to the detention facility. Secondly, surface overflow paths will be provided such that the 100-
year storm flows remain at least one foot below the finished floor elevation at the time of the
final drainage report.
WATER QUALITY/ DETENTION FACILITIES
The majority of the water quality is treated within the onsite ADS isolator rows directly adjacent
to pond P363. The remaining water quality within the site will be treated in tangent with water
quality pond P366, which is tributary to the College and Trilby Capital improvements.
LOW IMPACT DEVELOPMENT
A minimum of 75 percent of the new impervious surface area is treated by a Low-Impact
Development (LID) best management practice (BMP) in accordance with City criteria. An
College & Trilby Multi-Family Community
Preliminary Drainage Report
15
illustrative LID/ Surface Map is provided in Appendix G, and the sizing calculations of the LID
method is provided in Appendix D.
DRAINAGE DESIGN CRITERIA
REGULATIONS
This report was prepared to meet or exceed the City of Fort Collins stormwater criteria. The
City of Fort Collins Stormwater Criteria Manual (dated 2018)(FCSCM) and the Urban Drainage
Flood Control District’s (UDFCD) Drainage Criteria Manual (USDCM) Volumes 1, 2 and 3 were
referenced as guidelines for this design.
FOUR-STEP PROCESS TO PROTECT RECEIVING WATERS
The City of Fort Collins requires the Four Step Process to protect receiving waters. The four-
step process incorporates reducing runoff volume, treating water quality capture volume,
stabilizing streams, and implementing long-term source controls. Volume reduction is an
important part of the four-step process and is fundamental to effective stormwater management.
Per City criteria, a minimum of 75 percent of the new impervious surface area must be treated
by a Low-Impact Development (LID) best management practice (BMP). The site incorporates
underground ADS isolator rows, and a water quality pond designed to capture and treat at least
75% of the site’s water quality capture volume. The isolator rows need to be properly cleaned
and maintained to allow for long-term protection of the receiving waters. The proposed LID
BMPs will have the effect of slowing runoff through the site lot and increasing infiltration and
rainfall interception by encouraging infiltration and careful selection of vegetative cover. The dog
park will have a waste station, crusher fines and an underdrain system to provide infiltration so
that in a water quality event, a media of crusher fines with the underdrain system will effectively
improve water quality. The water quality for the dog park will ultimately be treated in the ADS
isolator rows. The improvements will decrease the runoff coefficient from the site and are
expected to have no adverse impact on the timing, quantity, or quality of stormwater runoff. The
majority of the new impervious area is treated by the proposed isolator rows in the mid-eastern
portion of the site. The remainder of the site is treated within water quality pond P366, as
illustrated in the LID/Surface Map provided in Appendix G.
College & Trilby Multi-Family Community
Preliminary Drainage Report
16
Step 1 – Employ Runoff Reduction Practices
All of the developed runoff through the site will be routed through the onsite detention pond at pond
P363. The detention pond will restrict the flow rate of stormwater leaving the site and reduce the impact
on downstream drainage areas. Additionally, the design will allow for greater than 75% of the project’s
added impervious area to be routed through an approved LID water quality treatment train. The onsite
water quality BMPs includes a water quality pond, and underground ADS StormTech isolator rows for
water quality.
Step 2 – Implement BMPS that Provide a Water Quality Capture Volume
The site incorporates underground ADS isolator rows, and a water quality pond designed to capture and
treat at over 90% of the site’s water quality capture volume. The isolator rows need to be properly
cleaned and maintained to allow for long-term protection of the receiving waters. The proposed LID BMPs
will have the effect of slowing runoff through the site lot and increasing infiltration and rainfall interception
by encouraging infiltration and careful selection of vegetative cover.
Step 3 –Stabilize Drainageways
The stormwater improvements at College and Trilby improves the existing condition by eliminating flows
overtopping College Ave at Pond P363 and at Pond P363.
Step 4 – Implement site-specific and other source-control BMPs
The dog park will have a waste station, crusher fines, and an underdrain system to provide infiltration so
that in a water quality event, a media of crusher fines with the underdrain system will effectively improve
water quality before it is ultimately treated in the underground ADS StormTech isolator rows. An erosion
control plan and Stormwater Management Plan will be implemented to prevent erosion and control
sediment on the project site and downstream drainage ways during and after construction.
College & Trilby Multi-Family Community
Preliminary Drainage Report
17
DEVELOPMENT CRITERIA REFERENCE AND CONSTRAINTS
The master drainage report for the Stone Creek Drainage Basin was prepared by ICON Engineering, Inc.
City of Fort Collins Stone Creek Basin Selected Plan of Improvements; Icon Engineering, Inc., October
2018. JR Engineering is following the general recommendations. The City of Fort Collins College and Trilby
intersection improvements plans are directly tributary to the site. The College and Trilby, intersection
improvement plan is being developed, and the Stone Creek basin master plan has been modified in a
memorandum from Wilson and Company data 4/2022 that has been approved by the City of Fort Collins.
JR Engineering has incorporated the drainage improvement from College and Trilby into the site by
incorporating the site into the Wilson and Company’s design and the 2018 Stone Creek Master Plan (the
SC_100Yearprop SWMM model). JR Engineering is proposing that the smaller pond P366 be utilized as a
water quality pond, where an overflow channel will be built, and the runoff will be detained in the larger
pond. The 30” RCP under College Avenue directly adjacent to pond P363 will not be upsized to a 48”
RCP per option B of the Stone Creek basin master plan. The capacity of the existing 30” pipe is 60 cfs. At
the time of the final design, calculations will be added to show what height the restrictor plate for pond
P363 will need to be placed at so that the 30" RCP downstream is not surcharged.
The stormwater improvements at College and Trilby improve the existing condition by eliminating flows
overtopping College Ave at Pond P363 by adding additional volume to the detention pond. Overflow onto
College Avenue from Pond P366 is no longer present. Pond 366 will serve as a water quality pond with
additional attenuation provided up to the overflow weir (approximately 2ft). The overflow channel
between pond 366 and pond 363 element P366_OVERFLOW_CHANNEL, as shown within section CC
in the Drainage Map within Appendix F - receives flow overtopping from the weir in an event between
the 25-year and 50-year. The water quality Pond 366 was sized for onsite and offsite tributary area. To
develop a rating curve in SWMM, the volume used to calculate the WQCV in P366 was done in an MHFD
spreadsheet; the area in the spreadsheet was multiplied by 1.2 to account for sediment accumulation in
accordance with the City of Fort Collins Criteria.
College & Trilby Multi-Family Community
Preliminary Drainage Report
18
Table 1, as shown below, shows the 100-year volume and 100-year WSELV. Table 2 shows the maximum
release rate(s) for the detention for the facilities on site. Table 3 shows the approximate onsite pond drain
times modeled within SWMM.
Table 1: Pond Volumes
Pond ID 100-YR_Vol.
(Acre-Ft)
100-YR
WSELV
PEAK_POND
RELEASE (CFS)
P363 10.07 5005.90 59.95
P366 1.46 5024.62 112.67
Table 2: 100 YR Release Rates
Description Link ID Release
Rate (CFS)
Total overflow from pond P366 and
runoff from channel basin.
P366_OVERFLOW_CHANNEL 63.26
Runoff over Weir in Pond P366 WEIR_P366 61.04
Runoff Through WQ Orifice and
unrestricted 30” outlet pipe.
P366_WQCV_OUTLET 49.41
Total outflow from Pond P363 in 48”
RCP at 60 cfs capacity.
P363_OUTFALL 59.95
Table 3: Approx. Drain Times
Description 5–Year Drain Time (hrs.)100–Year Drain Time (hrs.)
P366 68 85
P363 67 85
College & Trilby Multi-Family Community
Preliminary Drainage Report
18
HYDROLOGIC CRITERIA
Weighted percent imperviousness was calculated for each basin using the Fort Collins Stormwater
Criteria Manual Table 3.2-2 for each basin. EPA SWMM version 5.2 (Build 5.2.1) was used to model the
runoff for the site since the corresponding tributary area of the site is over 20 acres, and there are multiple
detention basins upstream of the site that are in series with one another. The City of Fort Collins area
has rainfall depths associated with the table below, as shown in Chapter 5 of the Fort Collins Stormwater
Criteria Manual. The corresponding site and tributary area were modeled in SWMM for the 2-year storm
and the 100-year storm and are shown in Table 4.1-4 below.
HYDRAULIC CRITERIA
At the time of the Final Plan (FP), StormCAD will be utilized to determine the hydraulic capacity of the
storm sewer system on site with the rational method. Additionally, hydraulic calculations for items such
as street capacity, inlet capacity, swales, channels, and the emergency spillway will be provided within the
Final Drainage Report. The emergency spillway will not see flows overtopping College Avenue unless the
College & Trilby Multi-Family Community
Preliminary Drainage Report
19
outlet structure is clogged. The pond has been graded to attenuate and detain runoff and release into the
30" pipe.
FLOODPLAIN REGULATIONS COMPLIANCE
As previously stated, the site lies within FEMA Zone X, areas which are determined to be outside the
0.2% annual chance floodplain. The site is not located within a FEMA regulated floodplain, as shown in
Appendix A in the FEMA attachments. The site is also not located in the City of Fort Collins Floodplain,
as shown in Appendix A in the City of Fort Collins Flood map.
MODIFICATIONS OF CRITERIA
The site does not treat 100% of modified/ added impervious areas. 94.82% of modified added onsite
impervious area is treated for water quality. 8.68 acres of offsite impervious area is treated with the CIP
improvements in Pond 366. The untreated area of the site includes lots directly facing the overflow
channel, the detention facility, and the portion of the site with the trail in the northwestern bump out of
the site that connects to Skyway Drive. The portion of the site that drains to the detention facility will
drain over a grass buffer. The runoff that drains into the channel between pond 363 and 366 will act as a
grass buffer, since the channel only receives runoff in events above the 25 year. The large grass buffers
provided within the channel and the detention pond will act similarly to a water-quality LID.
EROSION CONTROL
A statement of compliance with Erosion Control Criteria and all Erosion Control Materials will be
provided with the Final Drainage Report.
CONCLUSIONS
COMPLIANCE WITH STANDARDS
The hydrologic and water quality calculations were performed using the required methods as outlined in
the City of Fort Collins Stormwater Criteria Manual. The proposed drainage improvements meet or
exceed the City’s requirements except for the detention requirement and recommendations set forth
within the Stone Creek drainage master plan.
DRAINAGE CONCEPT
The proposed concept for the development of the Trilby College site involves surface flows and piping of
developed condition and offsite flow to the water quality pond, an onsite water quality facility with ADS
College & Trilby Multi-Family Community
Preliminary Drainage Report
20
isolator rows, and the runoff for the site will be treated at detention facility P363 onsite. All the offsite
flows will be conveyed through the site and directly released at a rate of 60 cfs in compliance with the
Stone Creek Master plan. The existing conditions drainage patterns are maintained in the proposed. The
proposed improvements will have no adverse impacts on the flow rate, character, or quality of runoff
leaving the site. The proposed improvements will have no adverse impacts on adjacent properties.
College & Trilby Multi-Family Community
Preliminary Drainage Report
21
REFERENCES
Fort Collins Stormwater Criteria Manual; City of Fort Collins, Colorado, December 2018.
Urban Storm Drainage Criteria Manual (Volumes 1, 2, and 3); Urban Drainage and Flood Control District,
June 2001.
City of Fort Collins Stone Creek Basin Selected Plan of Improvements; Icon Engineering, Inc., October
2018
Stone Creek SWMM Modeling for the College and Trilby Intersection Enhancements Project; Wilson and
Company, April 2022
College & Trilby Multi-Family Community
Preliminary Drainage Report
APPENDIX A – FIGURES
A Westrian Company
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/30/2020
Page 1 of 4
44
8
2
7
0
0
44
8
2
8
0
0
44
8
2
9
0
0
44
8
3
0
0
0
44
8
3
1
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44
8
3
2
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0
44
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3
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8
3
4
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44
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0
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44
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3
5
0
0
493000 493100 493200 493300 493400 493500 493600
493000 493100 493200 493300 493400 493500 493600
40° 30' 9'' N
10
5
°
5
'
0
'
'
W
40° 30' 9'' N
10
5
°
4
'
3
0
'
'
W
40° 29' 38'' N
10
5
°
5
'
0
'
'
W
40° 29' 38'' N
10
5
°
4
'
3
0
'
'
W
N
Map projection: Web Mercator Corner coordinates: WGS84 Edge tics: UTM Zone 13N WGS84
0 200 400 800 1200
Feet
0 50 100 200 300
Meters
Map Scale: 1:4,640 if printed on A portrait (8.5" x 11") sheet.
Soil Map may not be valid at this scale.
MAP LEGEND MAP INFORMATION
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Lines
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Soil Rating Points
A
A/D
B
B/D
C
C/D
D
Not rated or not available
Water Features
Streams and Canals
Transportation
Rails
Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 15, Jun 9, 2020
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Aug 11, 2018—Aug
12, 2018
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/30/2020
Page 2 of 4
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
35 Fort Collins loam, 0 to 3
percent slopes
C 1.6 4.2%
36 Fort Collins loam, 3 to 5
percent slopes
C 0.7 1.7%
54 Kim loam, 3 to 5 percent
slopes
B 11.2 28.8%
56 Kim-Thedalund loams, 3
to 15 percent slopes
B 20.1 51.5%
63 Longmont clay, 0 to 3
percent slopes
D 4.1 10.6%
65 Midway clay loam, 5 to
25 percent slopes
D 1.2 3.0%
119 Wiley silt loam, 3 to 5
percent slopes
B 0.1 0.1%
Totals for Area of Interest 39.0 100.0%
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/30/2020
Page 3 of 4
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff: None Specified
Tie-break Rule: Higher
Hydrologic Soil Group—Larimer County Area, Colorado
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
12/30/2020
Page 4 of 4
9,028
1,504.7
FCMaps
This map is a user generated static output from the City of Fort Collins FCMaps
Internet mapping site and is for reference only. Data layers that appear on this
map may or may not be accurate, current, or otherwise reliable.City of Fort Collins - GIS
1,143.0
1:
WGS_1984_Web_Mercator_Auxiliary_Sphere
Feet1,143.00571.50
Notes
Legend
6,859
FEMA Floodplain
FEMA High Risk - Floodway
FEMA High Risk - 100 Year
FEMA Moderate Risk - 100 / 500 Year
City Floodplains
City High Risk - Floodway
City High Risk - 100 Year
City Moderate Risk - 100 Year
City Limits
College & Trilby Multi-Family Community
Preliminary Drainage Report
APPENDIX B – HYDROLOGIC CALCULATIONS
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.:
Calculated By:ARJ
Checked By:0
Date:10/27/23
A1 1.90 100%0.14 7.5%90%0.14 6.4%2%1.63 1.7%15.6%
A2 1.76 100%0.47 26.9%90%0.46 23.8%2%0.82 0.9%51.6%
A3 0.31 100%0.16 51.9%90%0.07 19.8%2%0.08 0.5%72.3%
A4 1.65 100%0.51 31.1%90%0.28 15.3%2%0.86 1.0%47.4%
A5 0.42 100%0.25 58.4%90%0.00 0.0%2%0.18 0.8%59.3%
A6 0.75 100%0.36 47.4%90%0.18 21.4%2%0.22 0.6%69.4%
A7 0.44 100%0.34 77.8%90%0.00 0.0%2%0.10 0.4%78.2%
A8 1.23 100%0.42 34.3%90%0.37 27.0%2%0.44 0.7%62.0%
A9 0.30 100%0.20 64.9%90%0.00 0.0%2%0.11 0.7%65.6%
A10 0.18 100%0.11 62.5%90%0.00 0.0%2%0.07 0.8%63.2%
B1 0.63 100%0.28 44.0%90%0.23 33.1%2%0.12 0.4%77.5%
B2 1.17 100%0.08 7.2%90%0.00 0.0%2%1.08 1.9%9.1%
C1.1 3.84 100%1.11 29.0%90%0.73 17.0%2%2.00 1.0%47.0%
C1.2 0.72 100%0.17 23.2%90%0.11 13.3%2%0.45 1.2%37.8%
C1.3 0.18 100%0.07 39.6%90%0.06 27.9%2%0.05 0.6%68.1%
C2 1.12 100%0.61 54.3%90%0.00 0.0%2%0.51 0.9%55.2%
C3 1.91 100%0.84 44.1%90%0.67 31.6%2%0.40 0.4%76.1%
C4 2.55 100%0.93 36.6%90%0.58 20.6%2%1.03 0.8%58.0%
C5 1.34 100%0.84 62.8%90%0.00 0.0%2%0.50 0.7%63.6%
D1 0.29 100%0.24 82.1%90%0.00 0.0%2%0.05 0.4%82.5%
D2 0.50 100%0.26 52.7%90%0.08 13.9%2%0.16 0.6%67.2%
E1 0.42 100%0.20 47.0%90%0.16 34.1%2%0.06 0.3%81.3%
E2 0.75 100%0.58 76.9%90%0.00 0.0%2%0.17 0.5%77.3%
E3 0.23 100%0.18 77.6%90%0.00 0.0%2%0.05 0.4%78.1%
E4 0.17 100%0.08 46.6%90%0.03 15.2%2%0.06 0.7%62.6%
E5 0.38 100%0.11 28.0%90%0.03 6.8%2%0.24 1.3%36.2%
E6 0.78 100%0.04 4.8%90%0.00 0.0%2%0.74 1.9%6.7%
OF1 0.53 100%0.17 33.0%90%0.00 0.0%2%0.35 1.3%34.3%
F1 1.20 100%0.08 6.8%90%0.32 23.8%2%0.80 1.3%31.9%
G1 1.51 100%0.73 48.4%90%0.42 24.8%2%0.36 0.5%73.7%
G2 0.62 100%0.29 46.3%90%0.25 36.4%2%0.08 0.3%83.0%
G3 1.06 100%0.17 15.7%90%0.42 35.8%2%0.47 0.9%52.4%
G4 0.82 100%0.50 60.9%90%0.18 19.4%2%0.14 0.3%80.7%
H1 5.88 100%0.29 4.9%90%0.12 1.9%2%5.47 1.9%8.7%
TOTAL 37.54 46.6%
OS1 0.73 100%0.60 82.0%90%0.00 0.0%2%0.13 0.4%82.3%
OS2 2.02 100%0.66 32.5%90%0.33 14.7%2%1.37 1.4%48.6%
OS3 0.32 100%0.23 70.9%90%0.00 0.0%2%0.09 0.6%71.5%
OS4 0.40 100%0.36 90.6%90%0.00 0.0%2%0.04 0.2%90.8%
OS5 1.69 100%1.28 75.8%90%0.00 0.0%2%0.41 0.5%76.3%
OS6 0.79 100%0.62 78.2%90%0.00 0.0%2%0.17 0.4%78.6%
B830 7.82 45.0%
B840 11.71 45.0%
B850 17.23 10.0%
B930 4.71 100%1.02 21.7%90%0.42 8.0%2%3.69 1.6%31.2%
B910A 2.99 74.0%
B910C 1.30 90.0%
B910D 0.46 90.0%
39797.03
Weighted
% Imp.
Basins Total
Weighted %
Imp.Basin ID Total Area (ac)% Imp. Area (ac)
Lawns
% Imp.Area (ac)Weighted
% Imp.
Paved Roads and Walks Roofs
Weighted %
Imp.
COMPOSITE % IMPERVIOUS CALCULATIONS
% Imp.Area (ac)
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 1 11/10/2023
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.:
Calculated By:ARJ
Checked By:0
Date:10/27/23
A1 1.90 0.95 0.14 0.07 0.09 0.95 0.14 0.07 0.08 0.15 1.63 0.13 0.16 0.27 0.33
A2 1.76 0.95 0.47 0.26 0.32 0.95 0.46 0.25 0.31 0.15 0.82 0.07 0.09 0.58 0.72
A3 0.31 0.95 0.16 0.49 0.62 0.95 0.07 0.21 0.26 0.15 0.08 0.04 0.05 0.74 0.93
A4 1.65 0.95 0.51 0.30 0.37 0.95 0.28 0.16 0.20 0.15 0.86 0.08 0.10 0.53 0.67
A5 0.42 0.95 0.25 0.56 0.69 0.95 0.00 0.00 0.00 0.15 0.18 0.06 0.08 0.62 0.77
A6 0.75 0.95 0.36 0.45 0.56 0.95 0.18 0.23 0.28 0.15 0.22 0.04 0.05 0.72 0.90
A7 0.44 0.95 0.34 0.74 0.92 0.95 0.00 0.00 0.00 0.15 0.10 0.03 0.04 0.77 0.97
A8 1.23 0.95 0.42 0.33 0.41 0.95 0.37 0.28 0.36 0.15 0.44 0.05 0.07 0.66 0.83
A9 0.30 0.95 0.20 0.62 0.77 0.95 0.00 0.00 0.00 0.15 0.11 0.05 0.07 0.67 0.84
A10 0.18 1.95 0.11 1.22 1.00 0.95 0.00 0.00 0.00 1.15 0.07 0.43 0.54 1.00 1.00
C1.1 3.84 0.95 1.11 0.28 0.34 0.95 0.73 0.18 0.22 0.15 2.00 0.08 0.10 0.53 0.67
C1.2 0.72 1.95 0.17 0.45 0.57 0.95 0.11 0.14 0.18 1.15 0.45 0.71 0.89 1.00 1.00
C1.3 0.18 2.95 0.07 1.17 1.00 0.95 0.06 0.29 0.37 2.15 0.05 0.63 0.79 1.00 1.00
C2 1.12 0.95 0.61 0.52 0.64 0.95 0.00 0.00 0.00 0.15 0.51 0.07 0.09 0.58 0.73
C3 1.91 0.95 0.84 0.42 0.52 0.95 0.67 0.33 0.42 0.15 0.40 0.03 0.04 0.78 0.98
C4 2.55 0.95 0.93 0.35 0.43 0.95 0.58 0.22 0.27 0.15 1.03 0.06 0.08 0.63 0.78
C5 1.34 0.95 0.84 0.60 0.75 0.95 0.00 0.00 0.00 0.15 0.50 0.06 0.07 0.65 0.82
B1 0.63 1.95 0.28 0.86 1.00 1.95 0.23 0.72 0.90 1.15 0.12 0.22 0.28 1.00 1.00
B2 1.17 2.95 0.08 0.21 0.27 2.95 0.00 0.00 0.00 2.15 1.08 1.99 1.00 1.00 1.00
D1 0.29 3.95 0.24 3.24 1.00 3.95 0.00 0.00 0.00 3.15 0.05 0.56 0.70 1.00 1.00
D2 0.50 4.95 0.26 2.61 1.00 4.95 0.08 0.76 0.95 4.15 0.16 1.32 1.00 1.00 1.00
E1 0.42 0.95 0.20 0.45 0.56 0.95 0.16 0.36 0.45 0.15 0.06 0.02 0.03 0.83 1.00
E2 0.75 0.95 0.58 0.73 0.91 0.95 0.00 0.00 0.00 0.15 0.17 0.03 0.04 0.76 0.96
E3 0.23 0.95 0.18 0.74 0.92 0.95 0.00 0.00 0.00 0.15 0.05 0.03 0.04 0.77 0.96
E4 0.17 0.95 0.08 0.44 0.55 0.95 0.03 0.16 0.20 0.15 0.06 0.05 0.07 0.66 0.82
E5 0.38 0.95 0.11 0.27 0.33 0.95 0.03 0.07 0.09 0.15 0.24 0.10 0.12 0.44 0.54
E6 0.78 0.95 0.04 0.05 0.06 0.95 0.00 0.00 0.00 0.15 0.74 0.14 0.18 0.19 0.24
F1 1.20 0.95 0.08 0.06 0.08 0.95 0.32 0.25 0.31 0.15 0.80 0.10 0.13 0.42 0.52
G1 1.51 0.95 0.73 0.46 0.57 0.95 0.42 0.26 0.33 0.15 0.36 0.04 0.05 0.76 0.95
G2 0.62 0.95 0.29 0.44 0.55 0.95 0.25 0.38 0.48 0.15 0.08 0.02 0.02 0.84 1.00
G3 1.06 0.95 0.17 0.15 0.19 0.95 0.42 0.38 0.47 0.15 0.47 0.07 0.08 0.59 0.74
G4 0.82 0.95 0.50 0.58 0.72 0.95 0.18 0.21 0.26 0.15 0.14 0.03 0.03 0.81 1.00
H1 5.88 0.95 0.29 0.05 0.06 0.95 0.12 0.02 0.02 0.15 5.47 0.14 0.17 0.21 0.26
COMP.37.01 0.58 0.69
Basins Total
Weighted 100
YEAR C
Runoff
Coefficient Area (ac)2 - YEAR C 100 - YEAR C
Paved Roads/Ashphalt/Concrete Roofs Lawns
Basins Total
Weighted 2
YEAR C
39797.03
Total Area
(ac)
Runoff
Coefficien
t
COMPOSITE RUNOFF COEFFICIENT CALCULATIONS
Basin ID Area (ac)2 - YEAR C 100 -
YEAR C
Runoff
Coefficient Area (ac)2 - YEAR C 100 - YEAR C
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 1 11/10/2023
Subdivision:Project Name:College and Trilby
Location:Project No.:
Calculated By:ARJ
Checked By:0
Date:10/27/23
FINAL
BASIN D.A.Impervious C5 C100 L S o t i L t S t K VEL.t t COMP.t c TOTAL Urbanized t c t c
ID (ac)(%)(ft)(%)(min)(ft)(%)(ft/s)(min)(min)LENGTH (ft)(min)(min)
A1 1.90 16%0.27 0.33 200 2.0%16.9 403 2.0%15.0 2.1 3.2 20.1 603.0 27.6 20.1
A2 1.76 52%0.58 0.72 40 2.0%4.8 424 1.1%20.0 2.1 3.4 8.1 464.0 21.4 8.1
A3 0.31 72%0.74 0.93 8 2.0%1.5 156 0.7%20.0 1.6 1.6 3.0 164.0 15.4 5.0
A4 1.65 47%0.53 0.67 41.5 2.0%5.2 462 2.4%20.0 3.1 2.5 7.7 503.0 21.1 7.7
A5 0.42 59%0.62 0.77 32.5 2.0%4.0 404 2.8%20.0 3.3 2.0 6.0 436.5 18.3 6.0
A6 0.75 69%0.72 0.90 13 2.0%2.0 374 1.7%20.0 2.6 2.4 4.3 387.4 16.7 5.0
A7 0.44 78%0.77 0.97 13 2.0%1.7 354 1.9%20.0 2.7 2.2 3.9 367.0 14.9 5.0
A8 1.23 62%0.66 0.83 32 2.0%3.5 393 1.9%20.0 2.8 2.4 5.9 425.2 18.1 5.9
A9 0.30 66%0.67 0.84 32 2.0%3.5 183 2.2%20.0 3.0 1.0 4.5 215.0 16.0 5.0
A10 0.18 63%1.00 1.00 32 2.0%0.8 110 1.3%20.0 2.3 0.8 1.6 141.8 16.2 5.0
B1 0.63 77%1.00 0.67 21 8.0%0.4 189 2.8%20.0 3.4 0.9 1.4 210.0 13.8 5.0
B2 1.17 9%1.00 1.00 35 25.0%0.4 364 1.2%20.0 2.2 2.7 3.1 399.0 29.8 5.0
D1 0.29 82%1.00 1.00 13 2.0%0.5 261 2.4%20.0 3.1 1.4 1.9 274.0 13.3 5.0
D2 0.50 67%1.00 0.73 13 2.0%0.5 251 2.5%20.0 3.2 1.3 1.8 264.0 16.0 5.0
C1.1 3.84 47%0.53 0.67 32 2.0%4.6 1046 1.0%20.0 2.0 8.5 13.1 1078.1 29.0 13.1
C1.2 0.72 38%1.00 1.00 44 2.0%1.0 82 3.2%20.0 3.6 0.4 1.3 125.6 20.1 5.0
C1.3 0.18 68%1.00 1.00 46 2.0%1.0 53 3.0%20.0 3.5 0.3 1.2 99.0 14.7 5.0
C2 1.12 55%0.58 0.73 32 2.0%4.2 977 1.1%20.0 2.1 7.7 11.9 1008.7 25.8 11.9
C3 1.91 76%0.78 0.98 8 2.0%1.3 866 0.9%20.0 1.9 7.8 9.1 874.5 21.0 9.1
C4 2.55 58%0.63 0.78 13 2.0%2.5 660 1.5%20.0 2.5 4.5 6.9 672.9 21.4 6.9
C5 1.34 64%0.65 0.82 13 2.0%2.3 745 1.4%20.0 2.4 5.2 7.6 758.1 21.0 7.6
E1 0.42 81%0.83 1.00 55 3.0%2.5 208 1.5%20.0 2.5 1.4 3.9 263.0 13.5 5.0
E2 0.75 77%0.76 0.96 13 2.0%1.7 313 1.8%20.0 2.7 1.9 3.7 326.0 14.8 5.0
E3 0.23 78%0.77 0.96 41 2.0%3.0 88 0.6%20.0 1.5 0.9 4.0 129.2 13.7 5.0
E4 0.17 63%0.66 0.82 10 2.0%2.0 64 6.3%20.0 5.0 0.2 2.2 74.0 15.6 5.0
E5 0.38 36%0.44 0.54 5 25.0%0.9 194 2.1%20.0 2.9 1.1 2.0 199.0 21.4 5.0
E6 0.78 7%0.19 0.24 34 25.0%3.3 114 2.0%20.0 2.8 0.7 4.0 148.0 26.2 5.0
F1 1.20 32%0.42 0.52 30 25.0%2.3 411 2.6%20.0 3.2 2.1 4.5 441.0 23.7 5.0
G1 1.51 74%0.76 0.95 20 3.0%1.9 573 1.7%20.0 2.6 3.7 5.6 593.0 17.3 5.6
G2 0.62 83%0.84 1.00 20 3.0%1.4 336 2.8%20.0 3.4 1.7 3.1 356.3 13.5 5.0
G3 1.06 52%0.59 0.74 50 1.5%5.6 295 2.7%20.0 3.3 1.5 7.1 345.0 18.9 7.1
G4 0.82 81%0.81 1.00 21 3.0%1.7 428 2.2%20.0 2.9 2.4 4.1 449.4 14.7 5.0
H1 5.88 9%0.21 0.26 115 25.0%6.0 434 0.5%20.0 1.4 5.1 11.1 549.0 34.5 11.1
STANDARD FORM SF-2
TIME OF CONCENTRATION
SUB-BASIN tc CHECK
39797.03
(URBANIZED BASINS)DATA
INITIAL/OVERLAND
(Ti)
TRAVEL TIME
(Tt)
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 2 11/10/2023
Subdivision:Project Name:College and Trilby
Location:Project No.:
Calculated By:ARJ
Checked By:0
Date:10/27/23
FINAL
BASIN D.A.Impervious C5 C100 L S o t i L t S t K VEL.t t COMP.t c TOTAL Urbanized t c t c
ID (ac)(%)(ft)(%)(min)(ft)(%)(ft/s)(min)(min)LENGTH (ft)(min)(min)
STANDARD FORM SF-2
TIME OF CONCENTRATION
SUB-BASIN tc CHECK
39797.03
(URBANIZED BASINS)DATA
INITIAL/OVERLAND
(Ti)
TRAVEL TIME
(Tt)
NOTES:
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 2 of 2 11/10/2023
Project Name:College and Trilby
Subdivision:College and Trilby Project No.:
Location:Fort Collins Calculated By:ARJ
Design Storm:Checked By:0
Date:
TRAVEL TIME
STREET
De
s
i
g
n
P
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i
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t
Ba
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i
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I
D
Ar
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a
(
A
c
)
Ru
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f
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C
o
e
f
f
.
tc
(
m
i
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)
C*
A
(
A
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)
I
(
i
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/
h
r
)
Q
(
c
f
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)
tc
(
m
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C*
A
(
a
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)
I
(
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/
h
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)
Q
(
c
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Qst
r
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t
(
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C*
A
(
a
c
)
Sl
o
p
e
(
%
)
Qpi
p
e
(
c
f
s
)
C*
A
(
a
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Sl
o
p
e
(
%
)
Pi
p
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S
i
z
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(
i
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Le
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(
f
t
)
Ve
l
o
c
i
t
y
(
f
p
s
)
tt
(
m
i
n
)
REMARKS
Runoff into chase goes onto Street
1a A1 1.90 0.27 20.0 0.51 1.61 0.8
Runoff from Alley goes to on-grade inlet
2a A2 1.76 0.58 8.0 1.01 2.40 2.4
On-grade inlet
4a A4 1.65 0.53 8.0 0.88 2.40 2.1 20.0 1.39 1.61 2.2 Tributary Runoff from from Basins A4 and A1
Piped runoff
1.2 20.0 1.39 1.61 2.2 Tributary basins A4 and A1
Runoff from Alley goes on grade inlet
3a A3 0.31 0.74 5.0 0.23 2.85 0.7 Tributary Basin A3
Captured by on grade inlet
5A A5 0.42 0.62 6.0 0.26 2.67 0.7 Tributary Basin A5
Piped runoff
1.4 6.0 0.49 2.67 1.3 Tributary basins A3 and A5
Captured by on grade inlet
6a A6 0.75 0.72 5.0 0.54 2.85 1.5 Tributary Basin A6
Captured by on grade inlet
7a A7 0.44 0.77 5.0 0.34 2.85 1.0 Tributary Basin A7
Piped runoff from basins A6 and A7
1.1 5.0 0.88 2.85 2.5
Piped runoff basin A1-A7
1.5 20.0 2.76 1.61 4.4
Captured by on grade inlet Basin A9
9a A9 0.30 0.67 5.0 0.20 2.85 0.6
Piped runoff basin A1-A7 and Basin A9
1.6 20.0 2.96 1.61 4.8
8a A8 1.23 0.66 6.0 0.82 2.67 2.2
10a A10 0.18 1.00 5.0 0.18 2.85 0.5
Piped runoff basin A1-A10
1.7 20.0 3.96 1.61 6.4
4c C4 2.55 0.63 7.0 1.59 2.52 4.0
5c C5 1.34 0.65 8.0 0.88 2.40 2.1
Piped runoff Basins A1-A10 and basin C4 and C5
1.8 20.0 6.43 1.61 10.4
Runoff from basin C1.1 onto on grade inlet
1.1c C1.1 3.84 0.53 13.0 2.05 1.98 4.1
DIRECT RUNOFF TOTAL RUNOFF STREET PIPE
STANDARD FORM SF-3
STORM DRAINAGE SYSTEM DESIGN
(RATIONAL METHOD PROCEDURE)
2-Year
39797.03
10/27/23
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 2 11/10/2023
Project Name:College and Trilby
Subdivision:College and Trilby Project No.:
Location:Fort Collins Calculated By:ARJ
Design Storm:Checked By:0
Date:
TRAVEL TIME
STREET
De
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P
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t
Ba
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Q
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tc
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C*
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(
a
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Sl
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%
)
Qpi
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(
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C*
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(
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Sl
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%
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Pi
p
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Le
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Ve
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(
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tt
(
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)
REMARKS
DIRECT RUNOFF TOTAL RUNOFF STREET PIPE
STANDARD FORM SF-3
STORM DRAINAGE SYSTEM DESIGN
(RATIONAL METHOD PROCEDURE)
2-Year
39797.03
10/27/23
1.2c C1.2 0.72 1.00 5.0 0.72 2.85 2.1
1.3c C1.3 0.18 1.00 5.0 0.18 2.85 0.5
Piped Runoff
2.1 5.0 0.90 2.85 2.6 Tributary Basin C1.2 and C2.2
On grade runoff from basin C2
2C C2 1.12 0.58 12.0 0.66 2.05 1.4
Piped runoff
2.2 13.0 1.56 1.98 3.1 Basin C1.1 -C1.3 and Basin C2
3c C3 1.91 0.78 9.0 1.49 2.30 3.4
Piped runoff basins C1.1-C1.3, C2 and C3
2.3 13.0 3.05 1.98 6.0
Piped runoff basins A1-10 Basin C1.1-C1.3, C4, and C5
2.4 20.0 9.48 1.61 15.3
Runoff Captured by on grade Alley inlet
1g G1 1.51 0.76 6.0 1.14 2.67 3.0 Tributary Basin G1
Piped runoff A1-10 Basin C1.1-C1.3, C4, C5 and G1
3.1 20.0 10.62 1.61 17.1
Runoff from Alley
2g G2 0.62 0.84 5.0 0.53 2.85 1.5
Runoff Captured by a series of nyloplastic inlets
3g G3 1.06 0.59 7.0 0.63 2.52 1.6
Runoff to inlet in alley at Dp 4g
4g G4 0.82 0.81 5.0 0.66 2.85 1.9 5.0 1.19 2.85 3.4
Piped Runoff
3.2 7.0 1.82 2.52 4.6 Tributary basins G2-G4
Piped Runoff
3.3 20.0 12.44 1.61 20.0 Tributary Basins A1-10 Basin C1.1-C1.3, C4, C5 and G1-G5
Runoff from Alley Drains into Chase
1e E1 0.42 0.83 5.0 0.35 2.85 1.0
Runoff from Cu-de-Sac and Runoff from chase
2e E2 0.75 0.76 5.0 0.58 2.85 1.7 5.0 0.93 2.85 2.7 Tributary Runoff basin E1 and E2
Runoff from sump inlet
3e E3 0.23 0.77 5.0 0.18 2.85 0.5
Tributary runoff from basin E1-E3
4.1 5.0 1.11 2.85 3.2
OFFSITE Runoff from Trilby Road
5.1 14.6 Runoff entered in from SWMM MODEL
1b B1 0.63 1.00 5.0 0.63 2.85 1.8
Offsite Runoff
5.2 16.4 Offsite runoff + basin B1
2b B2 1.17 1.00 5.0 1.17 2.85 3.3
5.3 19.7 Offsite runoff + basin B1 and B2
P367 Outfall 0.1 Runoff entered in from SWMM MODEL
2d D2 0.50 1.00 5.0 0.50 2.85 1.4
Offsite runoff from pond P367, Offsite runoff from Trilby Road
6.1 21.3 Onsite basins B1 and B2 and D2
1d D1 0.29 1.00 5.0 0.29 2.85 0.8
Offsite runoff from pond P367, Offsite runoff from Trilby Road
6.2 22.1 Onsite basins B1 and B2 and D2 and D1
Notes:
Street and Pipe C*A values are determined by Q/i using the catchment's intensity value.
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 2 of 2 11/10/2023
Project Name:College and Trilby
Subdivision:College and Trilby Project No.:
Location:Fort Collins Calculated By:ARJ
Design Storm:Checked By:0
Date:
TRAVEL TIME
STREET
De
s
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n
P
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Ba
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C*
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Q
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tc
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C*
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a
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(
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Qst
r
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e
t
(
c
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C*
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(
a
c
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Sl
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(
%
)
Qpi
p
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(
c
f
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C*
A
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Sl
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%
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Pi
p
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Le
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Ve
l
o
c
i
t
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(
f
p
s
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tt
(
m
i
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)
REMARKS
Runoff into chase goes onto Street
1a A1 1.90 0.33 20.0 0.64 5.60 3.6
Runoff from Alley goes to on-grade inlet
2a A2 1.76 0.72 8.0 1.27 8.38 10.6
On-grade inlet
4a A4 1.65 0.67 8.0 1.11 8.38 9.3 20.0 1.75 5.60 9.8 Tributary Runoff from from Basins A4 and A1
Piped runoff
1.2 20.0 1.75 5.60 9.8 Tributary basins A4 and A1
Runoff from Alley goes on grade inlet
3a A3 0.31 0.93 5.0 0.29 9.95 2.9 Tributary Basin A3
Captured by on grade inlet
5A A5 0.42 0.77 6.0 0.33 9.31 3.1 Tributary Basin A5
Piped runoff
1.4 6.0 0.62 9.31 5.8 Tributary basins A3 and A5
Captured by on grade inlet
6a A6 0.75 0.90 5.0 0.68 9.95 6.8 Tributary Basin A6
Captured by on grade inlet
7a A7 0.44 0.97 5.0 0.42 9.95 4.2 Tributary Basin A7
Piped runoff from basins A6 and A7
1.1 5.0 1.10 9.95 10.9
Piped runoff basin A1-A7
1.5 20.0 3.47 5.60 19.4
Captured by on grade inlet Basin A9
9a A9 0.30 0.84 5.0 0.25 9.95 2.5
Piped runoff basin A1-A7 and Basin A9
1.6 20.0 3.72 5.60 20.8
8a A8 1.23 0.83 6.0 1.02 9.31 9.5
10a A10 0.18 1.00 5.0 0.18 9.95 1.8
Piped runoff basin A1-A10
1.7 20.0 4.92 5.60 27.6
4c C4 2.55 0.78 7.0 1.99 8.80 17.5
STORM DRAINAGE SYSTEM DESIGN
STANDARD FORM SF-3
(RATIONAL METHOD PROCEDURE)
39797.03
PIPE
100-Year
DIRECT RUNOFF TOTAL RUNOFF
10/27/23
STREET
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 3 11/10/2023
Project Name:College and Trilby
Subdivision:College and Trilby Project No.:
Location:Fort Collins Calculated By:ARJ
Design Storm:Checked By:0
Date:
TRAVEL TIME
STREET
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REMARKS
STORM DRAINAGE SYSTEM DESIGN
STANDARD FORM SF-3
(RATIONAL METHOD PROCEDURE)
39797.03
PIPE
100-Year
DIRECT RUNOFF TOTAL RUNOFF
10/27/23
STREET
5c C5 1.34 0.82 8.0 1.10 8.38 9.2
Piped runoff Basins A1-A10 and basin C4 and C5
1.8 20.0 8.01 5.60 44.9
Runoff from basin C1.1 onto on grade inlet
1.1c C1.1 3.84 0.67 13.0 2.56 6.92 17.7
1.2c C1.2 0.72 1.00 5.0 0.72 9.95 7.2
1.3c C1.3 0.18 1.00 5.0 0.18 9.95 1.8
Piped Runoff
2.1 5.0 0.90 9.95 9.0 Tributary Basin C1.2 and C2.2
On grade runoff from basin C2
2C C2 1.12 0.73 12.0 0.82 7.16 5.9
Piped runoff
2.2 13.0 1.72 6.92 11.9 Basin C1.1 -C1.3 and Basin C2
3c C3 1.91 0.98 9.0 1.87 8.03 15.0
Piped runoff basins C1.1-C1.3, C2 and C3
2.3 13.0 3.59 6.92 24.8
Piped runoff basins A1-10 Basin C1.1-C1.3, C4, and C5
2.4 20.0 11.60 5.60 65.0
Runoff Captured by on grade Alley inlet
1g G1 1.51 0.95 6.0 1.43 9.31 13.3 Tributary Basin G1
Piped runoff A1-10 Basin C1.1-C1.3, C4, C5 and G1
3.1 20.0 13.03 5.60 73.0
Runoff from Alley
2g G2 0.62 1.00 5.0 0.62 9.95 6.2
Runoff Captured by a series of nyloplastic inlets
3g G3 1.06 0.74 7.0 0.79 8.80 7.0
Runoff to inlet in alley at Dp 4g
4g G4 0.82 1.00 5.0 0.82 9.95 8.2 5.0 1.44 9.95 14.3
Piped Runoff
3.2 7.0 2.23 8.80 19.6 Tributary basins G2-G4
Piped Runoff
3.3 20.0 15.26 5.60 85.5 Tributary Basins A1-10 Basin C1.1-C1.3, C4, C5 and G1-G5
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 2 of 3 11/10/2023
Project Name:College and Trilby
Subdivision:College and Trilby Project No.:
Location:Fort Collins Calculated By:ARJ
Design Storm:Checked By:0
Date:
TRAVEL TIME
STREET
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REMARKS
STORM DRAINAGE SYSTEM DESIGN
STANDARD FORM SF-3
(RATIONAL METHOD PROCEDURE)
39797.03
PIPE
100-Year
DIRECT RUNOFF TOTAL RUNOFF
10/27/23
STREET
Runoff from Alley Drains into Chase
1e E1 0.42 1.00 5.0 0.42 9.95 4.2
Runoff from Cu-de-Sac and Runoff from chase
2e E2 0.75 0.96 5.0 0.72 9.95 7.2 5.0 1.14 9.95 11.3 Tributary Runoff basin E1 and E2
Runoff from sump inlet
3e E3 0.23 0.96 5.0 0.22 9.95 2.2
Tributary runoff from basin E1-E3
4.1 5.0 1.36 9.95 13.5
OFFSITE Runoff from Trilby Road
5.1 61.7 Runoff entered in from SWMM MODEL
1b B1 0.63 0.67 5.0 0.42 9.95 4.2
Offsite Runoff
5.2 65.9 Offsite runoff + basin B1
2b B2 1.17 1.00 5.0 1.17 9.95 11.6
5.3 77.5 Offsite runoff + basin B1 and B2
P367 Outfall 0.2 Runoff entered in from SWMM MODEL
2d D2 0.50 0.73 5.0 0.36 9.95 3.6
Offsite runoff from pond P367, Offsite runoff from Trilby Road
6.1 81.3 Onsite basins B1 and B2 and D2
1d D1 0.29 1.00 5.0 0.29 9.95 2.9
Offsite runoff from pond P367, Offsite runoff from Trilby Road
6.2 84.2 Onsite basins B1 and B2 and D2 and D1
Notes:
Street and Pipe C*A values are determined by Q/i using the catchment's intensity value.
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 3 of 3 11/10/2023
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.:
Calculated By:ARJ
Checked By:0
Date:10/27/23
Tributary Area Length Width Slope % Imperv N-Imperv N-Perv Store Imperv.Dstore perv.Zero % imperv.Storage (max)Storage (min)Decay Rate
Sub-basin
B820 26.52 500.09 2310.00 3.90%5.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B910 15.78 339.28 2026.00 3.00%20.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B840 11.06 300.17 1605.00 3.00%45.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B830 7.04 473.45 648.00 3.90%45.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B930 7.06 399.91 769.00 3.00%45.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B910A 3.06 533.17 250.00 2.00%74.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B910C 1.34 83.39 700.00 2.30%90.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B910D 0.46 160.30 125.00 1.50%90.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B850 16.94 419.98 1757.00 4.10%10.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B876 17.03 420.06 1766.00 4.10%60.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
Tributary Area Length Width Slope % Imperv N-Imperv N-Perv Store Imperv.Dstore perv.Zero % imperv.Storage (max)Storage (min)Decay Rate
Sub-basin
CT-1 24.44 659.00 1615.23 1.52%56.2%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
CT-2 5.31 313.20 738.93 1.82%48.3%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
CT-3 1.20 441.70 118.74 2.40%31.9%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
CT-4 5.88 353.00 725.69 0.50%8.7%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
OF1 0.53 156.40 147.25 0.50%34.3%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
OS1 0.73 186.30 171.75 0.50%82.3%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
OS2 2.02 403.00 218.65 3.97%48.6%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
OS3 0.32 115.00 121.16 3.94%71.5%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
OS4 0.40 129.00 134.97 3.73%90.8%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
OS5 1.69 484.00 152.40 2.09%76.3%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
OS6 0.79 231.00 148.62 3.73%78.3%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B840 11.71 300.17 1699.44 3.00%45.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B830 7.82 473.45 719.30 3.90%45.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B930 4.71 399.91 512.81 3.00%31.2%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B910A 2.99 533.17 244.35 2.00%74.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B910C 1.30 83.39 681.60 2.30%90.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B910D 0.46 160.30 126.16 1.50%90.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B850 17.24 419.98 1787.73 4.10%10.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
B876 16.97 420.06 1759.42 4.10%60.0%0.016 0.25 0.1 0.3 1 0.51 0.5 6.48
* Updated Offsite Basins
SWMM INPUTS
39797.03
PROPOSED - SWMM INPUTS
Basin inputs City of Fort Collins Default Inputs City of Fort Collins Horton inputs
INTERIM - SWMM INPUTS
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 1 11/13/2023
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.:39797.03
By:ARJ
Volume=1/3 x Depth x (A+B+(A*B)^0.5)Checked By:0
A - Upper Surface Date:10/27/23
B - Lower Surface
Stage Stage Elevation Stage Surface Area Stage Volume Cumulative Volume Cumulative Volume
(square feet)(cubic feet)(cubic feet)(acre feet)
0.00 4998.60 0 0 0 0.00
0.40 4999.00 207 28 28 0.00
1.40 5000.00 20,791 7,691 7,719 0.18
2.40 5001.00 54,621 36,370 44,089 1.01
3.40 5002.00 69,423 61,874 105,963 2.43
4.40 5003.00 77,422 73,386 179,349 4.12
5.40 5004.00 84,528 80,949 260,298 5.98
6.40 5005.00 91,786 88,132 348,430 8.00
7.40 5006.00 99,265 95,501 443,931 10.19
8.40 5007.00 107,023 103,119 547,050 12.56
9.40 5008.00 115,553 111,261 658,311 15.11
10.40 5009.00 122,656 119,087 777,398 17.85
POND VOLUME CALCULATIONS
POND P363
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 2 11/10/2023
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.39797.03
By:ARJ
Checked By:0
Date:10/27/23
POND VOLUME CALCULATIONS
4998.00
5000.00
5002.00
5004.00
5006.00
5008.00
5010.00
-2.00 0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00 20.00
El
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Pond Volume (ac-ft)
Pond Stage-Storage
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 2 of 2 11/10/2023
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.:39797.03
By:ARJ
Volume=1/3 x Depth x (A+B+(A*B)^0.5)Checked By:0
A - Upper Surface Date:10/27/23
B - Lower Surface
Stage Stage Elevation Stage Surface Area Stage Volume Cumulative Volume Cumulative Volume
(square feet)(cubic feet)(cubic feet)(acre feet)
0.00 5019.00 0 0 0 0.00
0.50 5019.50 540 90 90 0.00
1.00 5020.00 3,204 843 933 0.02
2.00 5021.00 9,840 6,220 7,153 0.16
3.00 5022.00 13,392 11,571 18,724 0.43
4.00 5023.00 15,949 14,652 33,376 0.77
5.00 5024.00 18,716 17,314 50,690 1.16
6.00 5025.00 21,770 20,224 70,914 1.63
7.00 5026.00 25,261 23,494 94,408 2.17
POND VOLUME CALCULATIONS
POND P366
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 2 11/10/2023
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.39797.03
By:ARJ
Checked By:0
Date:10/27/23
POND VOLUME CALCULATIONS
5018.00
5019.00
5020.00
5021.00
5022.00
5023.00
5024.00
5025.00
5026.00
5027.00
-0.50 0.00 0.50 1.00 1.50 2.00 2.50
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Pond Volume (ac-ft)
Pond Stage-Storage
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 2 of 2 11/10/2023
5 Year Drain Time - SWMM
Pond 366 Drain Time
5 Year Drain Time - SWMM
Pond P363 Drain Time
100 Year Drain Time - SWMM
Pond 366 Drain Time
100 Year Drain Time - SWMM
Pond P363 Drain Time
College & Trilby Multi-Family Community
Preliminary Drainage Report
APPENDIX C – HYDRAULIC CALCULATIONS
6'-0
9 16/"Ø
1
2/
1'
-
1
1
1'
-
1
1
1
2/
1'-95 8/3'-01 2/1'-95 8/
6'-713 16/
72'' ROUND TOP-MOUNT TRASH RACK
LDR-72
01 1
101 IRONWOOD ROAD
MIDDLESBORO, KY 40965
PH: (606) 248-5560
FAX: (606) 248-6308
JRHOE.COM
MADE IN THE U.S.A.
AVAILABLE MATERIALS:
MILD STEEL (NO FINISH) - WGT:
MILD STEEL (GALVANIZED) - WGT:
STAINLESS STEEL - WGT:
ALUMINUM - WGT:
CUSTOM SIZES AVAILABLE
AVAILABLE UPON REQUEST WITH:
496.7 lbs.
496.7 lbs.
496.7 lbs.
167.8 lbs.
ACCESS PORT
ANTI-VORTEX PLATE
TITLE:
SIZE DWG. NO.REV.
SHEET /A 118839
Subdivision:Core Spaces - Trilby College
Location:West Trilby and South College
Project Name:College and Trilby
Project Number:39793.03
Calculated By:ARJ
Checked By:
Date:11/10/2023
Design Point - J829 and J828 (6 ft. Dia Manhole w/ Trash Rack)
Design flow 105.7 and 22 cfs
Orifice Flow Calculation
Q = C*A* square root (2gH)
C = 0.6 A = 28.274 sq ft g = 32.2
Head (ft)CA (2GH)Sqrt (2GH)Capacity
1 16.9644 64.40 8.025 136.1
2 16.9644 128.80 11.349 192.5
3 16.9644 193.20 13.900 235.8
4 16.9644 257.60 16.050 272.3
5 16.9644 322.00 17.944 304.4
6 16.9644 386.40 19.657 333.5
College & Trilby Multi-Family Community
Preliminary Drainage Report
APPENDIX D – WATER QUALITY CALCULATIONS
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.:39797.03
Calculated By:ARJ
Checked By:0
Date:10/27/23
Basin
Area
(ac)% Imp.
B1 0.63 77.5%
B2 1.17 9.1%
D1 0.29 82.5%
D2 0.50 67.2%
E1 0.42 81.3%
E2 0.75 77.3%
E3 0.23 78.1%
E4 0.17 62.6%
E5 0.38 36.2%
E6 0.78 6.7%
OS1 0.73 82.3%OFFSITE AREA TREATED
OS2 2.02 48.6%
OS3 0.32 71.5%
B770A 0.36 100.0%
B770B 1.52 89.0%
B900A 0.48 95.0%
B900B 0.56 100.0%
B910C 1.30 90.0%
B920C 1.71 66.0%
B910D 0.46 90.0%
B920A 3.82 20.0%
B920B 0.99 63.0%
Total 19.59 57.2%
WQCV Drain Time (hr):40
Coefficient, a (Figure 3.2):1.0
WQCV (in):0.23
WQCV (ac-ft):0.45
WQ Pond Tributary Areas
POND 366
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 1 of 3 11/13/2023
Subdivision:College and Trilby Project Name:College and Trilby
Location:Fort Collins Project No.:39797.03
Calculated By:ARJ
Checked By:0
Date:10/27/23
Basin
Area
(ac)
2-Year C-
Value % Imp.
A1 1.90 0.27 15.6%
A2 1.76 0.58 51.6%
A3 0.31 0.74 72.3%
A4 1.65 0.53 47.4%
A5 0.42 0.62 59.3%
A6 0.75 0.72 69.4%
A7 0.44 0.77 78.2%
A8 1.23 0.66 62.0%
A9 0.30 0.67 65.6%
C1.1 3.84 0.53 47.0%
C1.2 0.72 1.00 37.8%
C1.3 0.18 1.00 68.1%
C2 1.12 0.58 55.2%
C3 1.91 0.78 76.1%
C4 2.55 0.63 58.0%
C5 1.34 0.65 63.6%
G1 1.51 0.76 73.7%
G2 0.62 0.84 83.0%
G3 1.06 0.59 52.4%
G4 0.82 0.81 80.7%
Total 24.44 0.63 56.2%
WQCV Drain Time (hr):12
Coefficient, a (Figure 3.2):1.0
WQCV (in):0.22
WQCV (ac-ft):0.55
WQ Pond Tributary Areas
ADS Isolator Rows
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 2 of 3 11/13/2023
X:\3970000.all\3979303\Excel\Drainage\3979303 Drainage_Calcs_Template_v2.07.xlsm Page 3 of 3 11/13/2023
Project:
Basin ID:
Depth Increment =1.00 ft
Watershed Information Top of Micropool --0.00 ------0 0.000
Selected BMP Type =EDB 5019.5 --0.50 ------540 0.012 135 0.003
Watershed Area =23.51 acres 5020 --1.00 ------3,204 0.074 1,071 0.025
Watershed Length =1,677 ft 5021 --2.00 ------9,840 0.226 7,593 0.174
Watershed Length to Centroid =1,006 ft 5022 --3.00 ------13,392 0.307 19,209 0.441
Watershed Slope =0.029 ft/ft 5023 --4.00 ------15,949 0.366 33,879 0.778
Watershed Imperviousness =57.30%percent 5024 --5.00 ------18,716 0.430 51,212 1.176
Percentage Hydrologic Soil Group A =0.0%percent 5025 --6.00 ------21,770 0.500 71,455 1.640
Percentage Hydrologic Soil Group B =0.0%percent 5026 --7.00 ------25,261 0.580 94,970 2.180
Percentage Hydrologic Soil Groups C/D =100.0%percent --------
Target WQCV Drain Time =40.0 hours --------
Location for 1-hr Rainfall Depths = Denver - Capitol Building --------
--------
--------
Optional User Overrides --------
Water Quality Capture Volume (WQCV) =0.446 acre-feet acre-feet --------
Excess Urban Runoff Volume (EURV) =1.288 acre-feet acre-feet --------
2-yr Runoff Volume (P1 = 0.82 in.) =0.843 acre-feet 0.82 inches --------
5-yr Runoff Volume (P1 = 1.09 in.) =1.245 acre-feet inches --------
10-yr Runoff Volume (P1 = 1.4 in.) =1.813 acre-feet 1.40 inches --------
25-yr Runoff Volume (P1 = 1.69 in.) =2.461 acre-feet inches --------
50-yr Runoff Volume (P1 = 1.99 in.) =3.062 acre-feet inches --------
100-yr Runoff Volume (P1 = 2.86 in.) =4.917 acre-feet 2.86 inches --------
500-yr Runoff Volume (P1 = 3.14 in.) =5.499 acre-feet inches --------
Approximate 2-yr Detention Volume =0.789 acre-feet --------
Approximate 5-yr Detention Volume =1.207 acre-feet --------
Approximate 10-yr Detention Volume =1.516 acre-feet --------
Approximate 25-yr Detention Volume =1.718 acre-feet --------
Approximate 50-yr Detention Volume =1.857 acre-feet --------
Approximate 100-yr Detention Volume =2.655 acre-feet --------
--------
Define Zones and Basin Geometry --------
Zone 1 Volume (WQCV) =0.446 acre-feet --------
Zone 2 Volume (User Defined - Zone 1) =0.000 acre-feet --------
Zone 3 Volume (User Defined - Zones 1 & 2) =0.000 acre-feet --------
Total Detention Basin Volume =0.446 acre-feet --------
Initial Surcharge Volume (ISV) =user ft 3 --------
Initial Surcharge Depth (ISD) =user ft --------
Total Available Detention Depth (Htotal) =user ft --------
Depth of Trickle Channel (HTC) =user ft --------
Slope of Trickle Channel (STC) =user ft/ft --------
Slopes of Main Basin Sides (Smain) =user H:V --------
Basin Length-to-Width Ratio (RL/W) =user --------
--------
Initial Surcharge Area (AISV) =user ft 2 --------
Surcharge Volume Length (LISV) =user ft --------
Surcharge Volume Width (WISV) =user ft --------
Depth of Basin Floor (HFLOOR) =user ft --------
Length of Basin Floor (LFLOOR) =user ft --------
Width of Basin Floor (WFLOOR) =user ft --------
Area of Basin Floor (AFLOOR) =user ft 2 --------
Volume of Basin Floor (VFLOOR) =user ft 3 --------
Depth of Main Basin (HMAIN) =user ft --------
Length of Main Basin (LMAIN) =user ft --------
Width of Main Basin (WMAIN) =user ft --------
Area of Main Basin (AMAIN) =user ft 2 --------
Volume of Main Basin (VMAIN) =user ft 3 --------
Calculated Total Basin Volume (Vtotal) =user acre-feet --------
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DETENTION BASIN STAGE-STORAGE TABLE BUILDER
Optional
Override
Area (ft 2)
Length
(ft)
Optional
Override
Stage (ft)
Stage
(ft)
Stage - Storage
Description
Area
(ft 2)
Width
(ft)
College and Trilby WQ Pond 366. AREA MULTI BY A FACTOR OF 1.2 TO ACCOUNT FOR SEDIMENT
Pond 366
MHFD-Detention, Version 4.06 (July 2022)
Volume
(ft 3)
Volume
(ac-ft)
Area
(acre)
Total detention
volume is less than
100-year volume.
After providing required inputs above including 1-hour rainfall
depths, click 'Run CUHP' to generate runoff hydrographs using
the embedded Colorado Urban Hydrograph Procedure.
ExampleZone Configuration (Retention Pond)
Pond 366 MHFD-Detention_v4-06.xlsm, Basin 11/13/2023, 10:38 AM
1 User Defined Stage-Area Booleans for Message
1 Equal Stage-Area Inputs Watershed L:W
1 CountA Watershed Lc:L
Watershed Slope
0 Calc_S_TC Booleans for CUHP
1 CUHP Inputs Complete
H_FLOOR 1 CUHP Results Calculated
L_FLOOR_OTHER
0.00 ISV 0.00 ISV
0.00 Floor 0.00 Floor
3.02 Zone 1 (WQCV)3.02 Zone 1 (WQCV)
3.02 Zone 2 (User)3.02 Zone 1 (WQCV)
3.02 Zone 3 (User)3.02 Zone 1 (WQCV)
DETENTION BASIN STAGE-STORAGE TABLE BUILDER
MHFD-Detention, Version 4.06 (July 2022)
0.000
0.550
1.100
1.650
2.200
0.000
0.145
0.290
0.435
0.580
0.00 2.00 4.00 6.00 8.00
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Stage (ft.)
Area (acres)Volume (ac-ft)
0
6400
12800
19200
25600
0
5
10
15
20
0.00 2.00 4.00 6.00 8.00
Ar
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Stage (ft)
Length (ft)Width (ft)Area (sq.ft.)
Pond 366 MHFD-Detention_v4-06.xlsm, Basin 11/13/2023, 10:38 AM
Project:
Basin ID:
Estimated Estimated
Stage (ft)Volume (ac-ft)Outlet Type
Zone 1 (WQCV)3.02 0.446 Orifice Plate
Zone 2 (User)3.02 0.000 Weir&Pipe (Restrict)
Zone 3 (User)3.02 0.000 Weir&Pipe (Restrict)
Total (all zones)0.446
User Input: Orifice at Underdrain Outlet (typically used to drain WQCV in a Filtration BMP)Calculated Parameters for Underdrain
Underdrain Orifice Invert Depth =N/A ft (distance below the filtration media surface)Underdrain Orifice Area =N/A ft2
Underdrain Orifice Diameter =N/A inches Underdrain Orifice Centroid =N/A feet
User Input: Orifice Plate with one or more orifices or Elliptical Slot Weir (typically used to drain WQCV and/or EURV in a sedimentation BMP)Calculated Parameters for Plate
Centroid of Lowest Orifice =0.00 ft (relative to basin bottom at Stage = 0 ft)WQ Orifice Area per Row =1.132E-02 ft2
Depth at top of Zone using Orifice Plate =3.02 ft (relative to basin bottom at Stage = 0 ft)Elliptical Half-Width =N/A feet
Orifice Plate: Orifice Vertical Spacing =12.10 inches Elliptical Slot Centroid =N/A feet
Orifice Plate: Orifice Area per Row =1.63 sq. inches (diameter = 1-7/16 inches)Elliptical Slot Area =N/A ft2
User Input: Stage and Total Area of Each Orifice Row (numbered from lowest to highest)
Row 1 (required)Row 2 (optional)Row 3 (optional)Row 4 (optional)Row 5 (optional)Row 6 (optional)Row 7 (optional)Row 8 (optional)
Stage of Orifice Centroid (ft)0.00 1.01 2.01
Orifice Area (sq. inches)1.63 1.63 1.63
Row 9 (optional)Row 10 (optional)Row 11 (optional)Row 12 (optional)Row 13 (optional)Row 14 (optional)Row 15 (optional)Row 16 (optional)
Stage of Orifice Centroid (ft)
Orifice Area (sq. inches)
User Input: Vertical Orifice (Circular or Rectangular)Calculated Parameters for Vertical Orifice
Not Selected Not Selected Not Selected Not Selected
Invert of Vertical Orifice =N/A N/A ft (relative to basin bottom at Stage = 0 ft)Vertical Orifice Area =N/A N/A
Depth at top of Zone using Vertical Orifice =N/A N/A ft (relative to basin bottom at Stage = 0 ft)Vertical Orifice Centroid =N/A N/A
Vertical Orifice Diameter =N/A N/A inches
User Input: Overflow Weir (Dropbox with Flat or Sloped Grate and Outlet Pipe OR Rectangular/Trapezoidal Weir and No Outlet Pipe)Calculated Parameters for Overflow Weir
grate Zone 2 Weir Zone 3 Weir Zone 2 Weir Zone 3 Weir
Overflow Weir Front Edge Height, Ho =3.02 3.02 ft (relative to basin bottom at Stage = 0 ft)Height of Grate Upper Edge, Ht =3.02
Overflow Weir Front Edge Length =5.00 feet Overflow Weir Slope Length =6.00
Overflow Weir Grate Slope =0.00 H:V Grate Open Area / 100-yr Orifice Area =4.83
Horiz. Length of Weir Sides =6.00 feet Overflow Grate Open Area w/o Debris =23.73
Overflow Grate Type = Close Mesh Grate Overflow Grate Open Area w/ Debris =23.73
Debris Clogging % =0%%
User Input: Outlet Pipe w/ Flow Restriction Plate (Circular Orifice, Restrictor Plate, or Rectangular Orifice)Calculated Parameters for Outlet Pipe w/ Flow Restriction Plate
Zone 2 Restrictor Zone 3 Restrictor Zone 2 Restrictor Zone 3 Restrictor
Depth to Invert of Outlet Pipe =0.00 ft (distance below basin bottom at Stage = 0 ft)Outlet Orifice Area =4.91
Outlet Pipe Diameter =30.00 inches Outlet Orifice Centroid =1.25
Restrictor Plate Height Above Pipe Invert =30.00 inches Half-Central Angle of Restrictor Plate on Pipe =3.14
User Input: Emergency Spillway (Rectangular or Trapezoidal)Calculated Parameters for Spillway
Spillway Invert Stage=ft (relative to basin bottom at Stage = 0 ft)Spillway Design Flow Depth=feet
Spillway Crest Length =feet Stage at Top of Freeboard =feet
Spillway End Slopes =H:V Basin Area at Top of Freeboard =acres
Freeboard above Max Water Surface =feet Basin Volume at Top of Freeboard =acre-ft
Max Ponding Depth of Target Storage Volume =#N/A feet Discharge at Top of Freeboard =cfs
Routed Hydrograph Results
Design Storm Return Period =WQCV EURV 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year
One-Hour Rainfall Depth (in) =N/A N/A 0.82 1.09 1.40 1.69 1.99 2.86
CUHP Runoff Volume (acre-ft) =0.446 1.288 0.843 1.245 1.813 2.461 3.062 4.917
Inflow Hydrograph Volume (acre-ft) =N/A N/A 0.843 1.245 1.813 2.461 3.062 4.917
CUHP Predevelopment Peak Q (cfs) =N/A N/A 0.2 1.8 6.5 13.8 19.0 35.9
OPTIONAL Override Predevelopment Peak Q (cfs) =N/A N/A
Predevelopment Unit Peak Flow, q (cfs/acre) =N/A N/A 0.01 0.08 0.27 0.59 0.81 1.53
Peak Inflow Q (cfs) =N/A N/A 12.2 18.2 26.8 37.6 47.0 75.2
Peak Outflow Q (cfs) =0.2 45.1 5.2 11.2 20.4 34.5 38.4 48.6
Ratio Peak Outflow to Predevelopment Q =N/A N/A N/A 6.1 3.2 2.5 2.0 1.4
Structure Controlling Flow =Overflow Weir 1 Outlet Plate 1 Overflow Weir 1 Overflow Weir 1 Overflow Weir 1 Overflow Weir 1 Outlet Plate 1 Outlet Plate 1
Max Velocity through Grate 1 (fps) =N/A 1.98 0.22 0.5 0.8 1.4 1.6 2.0
Max Velocity through Grate 2 (fps) =N/A N/A N/A N/A N/A N/A N/A N/A
Time to Drain 97% of Inflow Volume (hours) =38 34 38 36 33 31 29 23
Time to Drain 99% of Inflow Volume (hours) =40 39 42 41 40 38 37 34
Maximum Ponding Depth (ft) =3.02 5.26 3.19 3.30 3.44 3.62 3.89 5.48
Area at Maximum Ponding Depth (acres) =0.31 0.45 0.32 0.33 0.33 0.34 0.36 0.46
Maximum Volume Stored (acre-ft) =0.447 1.290 0.497 0.536 0.582 0.643 0.738 1.390
The user can override the default CUHP hydrographs and runoff volumes by entering new values in the Inflow Hydrographs table (Columns W through AF).
DETENTION BASIN OUTLET STRUCTURE DESIGN
MHFD-Detention, Version 4.06 (July 2022)
College and Trilby WQ Pond 366. AREA MULTI BY A FACTOR OF 1.2 TO ACCOUNT FOR SEDIMENT
Pond 366
Example Zone Configuration (Retention Pond)
Pond 366 MHFD-Detention_v4-06.xlsm, Outlet Structure 11/13/2023, 10:36 AM
Summary Stage-Area-Volume-Discharge Relationships
The user can create a summary S-A-V-D by entering the desired stage increments and the remainder of the table will populate automatically.
The user should graphically compare the summary S-A-V-D table to the full S-A-V-D table in the chart to confirm it captures all key transition points.
Stage Area Area Volume Volume Total
Outflow
[ft][ft 2][acres][ft 3][ac-ft][cfs]
0.00 0 0.000 0 0.000 0.00
0.25 270 0.006 34 0.001 0.03
0.50 540 0.012 135 0.003 0.04
0.75 1,872 0.043 436 0.010 0.05
1.00 3,204 0.074 1,071 0.025 0.05
1.25 4,863 0.112 2,079 0.048 0.09
1.50 6,522 0.150 3,502 0.080 0.10
1.75 8,181 0.188 5,340 0.123 0.12
2.00 9,840 0.226 7,593 0.174 0.13
2.25 10,728 0.246 10,164 0.233 0.17
2.50 11,616 0.267 12,957 0.297 0.19
2.75 12,504 0.287 15,972 0.367 0.21
3.00 13,392 0.307 19,209 0.441 0.23
3.02 13,443 0.309 19,477 0.447 0.23
3.25 14,031 0.322 22,637 0.520 8.30
3.50 14,670 0.337 26,225 0.602 24.56
3.75 15,310 0.351 29,972 0.688 37.37
4.00 15,949 0.366 33,879 0.778 39.19
4.25 16,641 0.382 37,953 0.871 40.94
4.50 17,332 0.398 42,200 0.969 42.61
4.75 18,024 0.414 46,619 1.070 44.22
5.00 18,716 0.430 51,212 1.176 45.77
5.25 19,479 0.447 55,986 1.285 47.27
5.50 20,243 0.465 60,952 1.399 48.73
5.75 21,006 0.482 66,108 1.518 50.14
6.00 21,770 0.500 71,455 1.640 51.51
6.25 22,643 0.520 77,006 1.768 52.85
6.50 23,515 0.540 82,776 1.900 54.16
6.75 24,388 0.560 88,764 2.038 55.43
7.00 25,261 0.580 94,970 2.180 56.68
MHFD-Detention, Version 4.06 (July 2022)
5022.02 WQ - Overflow Weir
DETENTION BASIN OUTLET STRUCTURE DESIGN
Stage - Storage
Description
5019
5024 -OVERFLOW SPILLWAY
For best results, include the
stages of all grade slope
changes (e.g. ISV and Floor)
from the S-A-V table on
Sheet 'Basin'.
Also include the inverts of all
outlets (e.g. vertical orifice,
overflow grate, and spillway,
where applicable).
Pond 366 MHFD-Detention_v4-06.xlsm, Outlet Structure 11/13/2023, 10:36 AM
A B C D E F G H I J K L M N
VAULT ID
TOTAL
REQUIRED
WQCV
(CF)
WQ FLOW
(CFS)CHAMBER TYPE
RELEASE RATE/
CHAMBER
(CFS)
CHAMBER
VOLUME
(CF)
CHAMBER
VOLUME +
AGGREGATE
(CF)
NUMBER OF
CHAMBERS
COMBINED
RELEASE RATE
WQCV
METHOD
(CFS)
FAA
REQUIRED
STORAGE
VOLUME
(CF)
NUMBER OF
CHAMBERS
(FAA)
TOTAL
VOLUME
(CHAMBERS
ONLY)
(CF)
COMBINED
RELEASE
RATE FAA
METHOD
(CFS)
TOTAL
NUMBER OF
CHAMBERS
REQUIRED
TOTAL
SYSTEM
VOLUME
(CF)
WQ A 23958 10 MC-4500 0.026 106.5 162.6 148 3.87 13678.3 129 13739 3.37 148 24064.8
CONFIRM CONFIRM
A MHFD Extended Detention Basin Spreadsheet WQCV
B 1/2 of the 2-year developed flow rate for the basin being sized
C Chamber type based on site constraints
D Flwo rate thru the bottom of the isolator row chamber which is equal to the area of the bottom of the chamber multiplied by the flow rate per unit area (see calculations below)
E Volume within chamber only, not accounting for void spaces in surrounding aggregate (standard spec)
F Volume includes chamber and void space (40%) in surrounding aggregate , per chamber unit. (standard spec)
G Number of chambers required to provide full WQCV within total installed system, include aggregate = A / F
H Release rate per chamber times number of chambers = D * G
I FAA calc based on Flow, WQ and Total Release Rate
J Number of chambers required to provide required FAA staorage volume stored within the chamber only (no aggregate stone) = I / E
K Volume provided in chambers only (no aggregate storage). This must meet or excheed the required FAA storage volume. Greater of G or J * E
L Release rate per chamber times number of chambers = D * J
M Total number of chambers (Greater of J or G)
N Total system volume. Includes number of chambers plus aggregate. This must meet or exceed required WQCV
MC-7200 MC-4500 MC-3500 SC-740 SC-310 SC-160LP
60.0 60.0 45.0 30.0 16.0 12.0
100.0 100.0 77.0 51.0 34.0 25.0
79.1 48.3 86.0 85.4 85.4 85.4
54.9 33.5 46.0 30.2 20.2 14.8
175.9 106.5 109.9 45.9 14.7 6.9
267.3 162.6 175.0 74.9 31.0 15.0
CHAMBER FLOW RATE CONVERSION (GPM/SF TO CFS)
0.35 GPM/SF
1 CF =7.48052 GAL
1 GALLON =0.133681 CF
1 GPM =0.002228 CFS
*FLOW RATE BASED ON 1/2 OF NOV 07 QMAX IN FIGURE 17 OF UNH TESTING REPORT
MC-7200 MC-4500 MC-3500 SC-740 SC-310 SC-160LP
0.043 0.026 0.036 0.024 0.016 0.012 (COLUMN D)FLOW RATE / CHAMBER (CFS)
STORMTECH CHAMBER VOLUME AND RELEASE RATE CALCULATIONS
FLOOR AREA (SF)
CHAMBER VOLUME (CF)
CHAMBER/AGGREGATE VOLUME (CF)
FLOW RATE*
CHAMBER FLOW RATE
CHAMBER DIMENSIONS
WIDTH (IN)
INSTALLED LENGTH (IN)
HEIGHT (IN)
STORMTECH CHAMBER DATA
Subdivision:Core Spaces at Trilby College Project Name:Core Spaces at Trilby College
Location:Fort Collins Project No.:39793.03
Calculated By:ARJ
Checked By:
Date:10/27/23
Area (acres)24.44 Area of Catchment tributary to storage facility (Acres)
2yr Runoff Coefficient 'C'0.63 the runoff coefficient
Release Rate (cfs)3.770 the allowable maximum release rate from the detention facility
Time of Concentration (min)20.0
ft3 acre-ft.
13,678.3 0.314
Time
(min)C * A
WQ
Intensity
(in/hr)
Inflow
Rate (cfs)
Inflow
Volume
(ft3)
Outflow
Adjustme
nt factor
(m)
Average
Outflow
Rate (cfs)
Outflow
Volume
(ft3)
Detentio
n Volume
(ft3)
Detentio
n Volume
(acre-ft)
5 15.40 1.43 21.94 6582.30 1.00 3.77 1131.00 5451.30 0.1251
10 15.40 1.11 17.01 10208.34 1.00 3.77 2262.00 7946.34 0.1824
15 15.40 0.94 14.40 12956.74 1.00 3.77 3393.00 9563.74 0.2196
20 15.40 0.81 12.39 14873.70 1.00 3.77 4524.00 10349.70 0.2376
25 15.40 0.72 11.01 16513.50 0.90 3.39 5089.50 11424.00 0.2623
30 15.40 0.65 10.01 18014.72 0.83 3.14 5655.00 12359.72 0.2837
35 15.40 0.59 9.01 18915.46 0.79 2.96 6220.50 12694.96 0.2914
40 15.40 0.54 8.24 19770.00 0.75 2.83 6786.00 12984.00 0.2981
45 15.40 0.50 7.62 20578.36 0.72 2.72 7351.50 13226.86 0.3036
50 15.40 0.46 7.08 21248.14 0.70 2.64 7917.00 13331.14 0.3060
55 15.40 0.44 6.70 22102.68 0.68 2.57 8482.50 13620.18 0.3127
60 15.40 0.41 6.31 22726.27 0.67 2.51 9048.00 13678.27 0.3140
65 15.40 0.39 5.93 23118.90 0.65 2.47 9613.50 13505.40 0.3100
70 15.40 0.37 5.62 23603.91 0.64 2.42 10179.00 13424.91 0.3082
75 15.40 0.35 5.31 23904.15 0.63 2.39 10744.50 13159.65 0.3021
80 15.40 0.33 5.08 24389.16 0.63 2.36 11310.00 13079.16 0.3003
85 15.40 0.32 4.85 24735.60 0.62 2.33 11875.50 12860.10 0.2952
90 15.40 0.31 4.70 25359.19 0.61 2.30 12441.00 12918.19 0.2966
95 15.40 0.29 4.47 25451.57 0.61 2.28 13006.50 12445.07 0.2857
100 15.40 0.28 4.31 25867.30 0.60 2.26 13572.00 12295.30 0.2823
105 15.40 0.27 4.16 26190.64 0.60 2.24 14137.50 12053.14 0.2767
110 15.40 0.26 4.00 26421.60 0.59 2.23 14703.00 11718.60 0.2690
115 15.40 0.26 3.93 27091.37 0.59 2.21 15268.50 11822.87 0.2714
120 15.40 0.25 3.77 27160.66 0.58 2.20 15834.00 11326.66 0.2600
Required detention
WQ Pond Sizing FAA Methoud for ADS StormTech Chambers
SC-160 25 84.4 12 14.65 6.9 15 0.35 0.0007798 0.011
SC-310 34 85.4 16 20.16 14.7 31 0.35 0.0007798 0.016
SC-740 51 85.4 30 30.25 45.9 74 0.35 0.0007798 0.024
DC-780 51 85.4 30 30.25 46.2 78.4 0.35 0.0007798 0.024
MC-3500 77 90 45 48.13 109.9 46.9 0.35 0.0007798 0.038
MC-4500 100 48.3 60 33.54 106.5 162.6 0.35 0.0007798 0.026
* Flow Rate given by City of Fort Collins based on UNH Testing Report
Using Highlighted row
Chamber & Aggregate Volume (cf)Flow Rate*
(gpm/sf)
Flow Rate
(cfs/sf)
Flow Rate per Chamber
(cfs)Chamber Type Width
(in)
Length
(in)
Height
(in)
Floor Area
(sf)Chamber Volume (cf)
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College & Trilby Multi-Family Community
Preliminary Drainage Report
APPENDIX E – REFERENCES
LEGEND
EFFECTIVE SWMM DRAINAGE
BASIN DIVIDE LINE
DIRECTION OF FLOW
SUBBASIN
CONVEYANCE ELEMENT - PIPE
DETENTION POND
NODE
CONVEYANCE ELEMENT - SURFACE FLOW
CONVEYANCE ELEMENT - ORIFICE
CONVEYANCE ELEMENT
PORTION OF THE STONE CREEK
EFFECTIVE SWMM SCHEMATIC
3-25-22
LEGEND
PROPOSED SWMM DRAINAGE
BASIN DIVIDE LINE
SUBBASIN
CONVEYANCE ELEMENT - PIPE
DETENTION POND
NODE
CONVEYANCE ELEMENT - SURFACE FLOW
CONVEYANCE ELEMENT - ORIFICE
PROPOSED CONVEYANCE ELEMENT
EFFECTIVE SWMM DRAINAGE
BASIN DIVIDE LINE
(WITH DIRECTION OF FLOW)
CONVEYANCE ELEMENT
PROPOSED SUBBASIN
PROPOSED CONVEYANCE ELEMENT - PIPE
PROPOSED CONVEYANCE ELEMENT - SURFACE FLOW
PROPOSED CONVEYANCE ELEMENT - ORIFICE
PROPOSED NODE
PROPOSED DETENTION POND
STONE CREEK
PROPOSED CONDTIONS SWMM SCHEMATIC
3-25-22
(WITH DIRECTION OF FLOW)
LEGEND
CORRECTED EFFECTIVE SWMM DRAINAGE
BASIN DIVIDE LINE
(WITH DIRECTION OF FLOW)
SUBBASIN
CONVEYANCE ELEMENT - PIPE
DETENTION POND
NODE
CONVEYANCE ELEMENT - SURFACE FLOW
CONVEYANCE ELEMENT - ORIFICE
CORRECTED CONVEYANCE ELEMENT
EFFECTIVE SWMM DRAINAGE
BASIN DIVIDE LINE
CONVEYANCE ELEMENT
CORRECTED EFFECTIVE SUBBASIN
CORRECTED CONVEYANCE ELEMENT - PIPE
CORRECTED CONVEYANCE ELEMENT - SURFACE FLOW
CORRECTED CONVEYANCE ELEMENT - ORIFICE
CORRECTED EFFECTIVE NODE
CORRECTED EFFECTIVE DETENTION POND
STONE CREEK
CORRECTED EFFECTIVE SWMM SCHEMATIC
3-25-22
(WITH DIRECTION OF FLOW)
PROPOSED SWMM DRAINAGE
BASIN DIVIDE LINE
PROPOSED DIRECTION OF FLOW
SUBBASIN
CONVEYANCE ELEMENT - PIPE
DETENTION POND
NODE
CONVEYANCE ELEMENT - SURFACE FLOW
CONVEYANCE ELEMENT - ORIFICE
PROPOSED CONVEYANCE ELEMENT
EFFECTIVE SWMM DRAINAGE
BASIN DIVIDE LINE
DIRECTION OF FLOW
CONVEYANCE ELEMENT
PROPOSED SUBBASIN
PROPOSED CONVEYANCE ELEMENT - PIPE
PROPOSED CONVEYANCE ELEMENT - SURFACE FLOW
PROPOSED CONVEYANCE ELEMENT - ORIFICE
PROPOSED NODE
LEGEND
PROPOSED DETENTION POND
STONE CREEK
PROPOSED CONDTIONS SWMM SCHEMATIC
AREA OF COLLEGE AND TRILBY
INTERSECTION ENHANCEMENTS STORM SYSTEM
3-25-22
T
T
S
T
M
S
T
M
A1
A2
A3
A4 A5 A6
A7
A8 A9
B1 B2 B3
acres
A1
0.83
1.00 0.09
acres
A2
0.71
0.89 0.39
acres
A3
0.29
0.37 0.52
acres
A4
0.81
1.00 0.24
acres
A5
0.86
1.00 0.48
acres
A6
0.64
0.80 0.86
acres
A7
0.83
1.00 0.18
acres
A8
0.95
1.00 0.34 acres
A9
0.95
1.00 0.34
acres
B1
0.37
0.46 0.14
acres
B3
0.62
0.78 0.01
acres
B2
0.30
0.38 0.20
acres
OS1
0.25
0.31 1.55
-
-
-
-
-
-
-
-
-
-
-
-
-
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STAMP
Date:
Drawn By:
Project No:
Checked By:
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09.09.2020
GNK000008
JEP
DBC
CAUTION - NOTICE TO CONTRACTOR
1.ALL UTILITY LOCATIONS SHOWN ARE BASED ON MAPS
PROVIDED BY THE APPROPRIATE UTILITY COMPANY AND
FIELD SURFACE EVIDENCE AT THE TIME OF SURVEY AND IS TO
BE CONSIDERED AN APPROXIMATE LOCATION ONLY. IT IS THE
CONTRACTOR'S RESPONSIBILITY TO FIELD VERIFY THE FIELD
LOCATION OF ALL UTILITIES, PUBLIC OR PRIVATE, WHETHER
SHOWN ON THE PLANS OR NOT, PRIOR TO CONSTRUCTION.
REPORT ANY DISCREPANCIES TO THE ENGINEERED PRIOR TO
CONSTRUCTION.
2.WHERE A PROPOSED UTILITY CROSSES AN EXISTING UTILITY,
IT IS THE CONTRACTOR'S RESPONSIBILITY TO FIELD VERIFY
THE HORIZONTAL AND VERTICAL LOCATION OF SUCH
EXISTING UTILITY, EITHER THROUGH POTHOLING OR
ALTERNATIVE METHOD. REPORT INFORMATION TO THE
ENGINEER PRIOR TO CONSTRUCTION.
3.CONTRACTOR RESPONSIBLE FOR AS-BUILT DRAWINGS,
TESTS, REPORTS AND/OR ANY OTHER CERTIFICATES OR
INFORMATION AS REQUIRED FOR ACCEPTANCE OF WORK
FROM CITY, UTILITY DISTRICTS OR ANY OTHER GOVERNING
AGENCY.
4.CONTRACTOR SHALL PROTECT ALL EXISTING SURVEY
MONUMENTATION. CONTRACTOR SHALL HAVE LICENSED
SURVEYOR REPLACE ANY DAMAGED OR DISTURBED
MONUMENTATION AT THEIR COST.
Know what's
before you dig.
DRAINAGE PLAN
C8.0
SCALE: 1"=30'
0 15 30
LEGEND:
PROPOSED STORM SEWER
EXISTING STORM SEWER
PROPOSED STORM INLET
PROPOSED LOTLINE
EASEMENT LINE
EXISTING MINOR CONTOUR
EXISTING MAJOR CONTOUR
PROPOSED MINOR CONTOUR
PROPOSED MAJOR CONTOUR
PROPERTY BOUNDARY
EXISTING MANHOLE
DRAINAGE SYMBOLS:
DESIGN POINT
MAJOR BASIN BOUNDARY (i.e., C-STORE)
SUB-BASIN BOUNDARY (i.e., RATIONAL METHOD)
OVERLAND FLOW DIRECTION
(I.E., LANDSCAPING)
DIRECT FLOW DIRECTION
(I.E., PAVEMENT, CURB AND
GUTTER)
BASIN ID
MINOR (2YEAR) RUNOFF
COEFFICIENT
MAJOR (100YEAR) RUNOFF
COEFFICIENT
BASIN AREA
(ACRES)
acres
A1
0.23
0.45
1.00
A1
TRILBY ROAD TRILBY ROAD
CO
L
L
E
G
E
A
V
E
N
U
E
LE
M
A
Y
A
V
E
N
U
E
SKYWAY DRIVE
CO
L
B
Y
S
T
E
E
T
C
B
A
D
NORTH TRIBUTARY
MIDDL
E
H
U
N
T
I
N
G
T
O
N
H
I
L
L
S
T
R
I
B
U
T
A
R
Y
SOUTH TRIBUTARY
E
TRIBUTARY
C1: PROPOSED STORM
SEWER SYSTEM
ST
O
N
E
C
R
E
E
K
STO
N
E
C
R
E
E
K
CO
L
L
E
G
E
A
V
E
N
U
E
D1: FLOODPLAIN REGULATIONS
D2: CROWN RIDGE LANE
CULVERT IMPROVEMENTS
(10'W X 3'H BOX CULVERT)
CROWN RIDGE LANE
PROVINCETOWNE
DEVELOPMENT
RICK DRIVE
A1: FLOODPLAIN DEVELOPMENT
REGULATIONS
A2: OVERFLOW CHANNEL TO POND
363 (RIPRAP LINED CHANNEL)
E1: Ditch Crossing Structure
B1: FLOODPLAIN
DEVELOPMENT REGULATIONS
B2: INCREASED CAPACITY
UNDER COLLEGE AVE
LEMAY AVENUE
CROSSING
IMPROVEMENTS
A
PROBLEM IDENTIFICATION
AREA LOCATIONS
COLLEGE AVENUE APPROXIMATELY
600-FEET NORTH OF TRILBY ROAD
B
COLLEGE AVENUE AT SKYWAY DRIVEC
D
E
SPILL FLOW TO PROVINCETOWNE
LOUDEN DITCH CROSSING
COLLEGE AVENUE 1,500-FEET
NORTH OF TRILBY ROAD
NORTH
0
SCALE : 1" = 300
300 600
F:
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6
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A
M
SELECTED PLAN IMPROVEMENTS
PROJECT NO: 17-049-SCBAPPR.REVISIONSNo. DATE
ICON
ENGINEERING, INC.
PREPARED BY:
Know what's below.
Call before you dig.1-1
VERIFY SCALE
0 1"
BAR IS ONE INCH
ON ORIGINAL
DRAWINGS
SEPT 2018
PREPARED FOR:
500
0
50
0
0
5
0
1
0
50
0
0
50
0
5
0+00
1+00
2+00
3+00
4+00 5+00 6+00 7+00
EXISTING 30" RCP TO BE
REPLACED WITH 48" RCP
PROPOSED
MANHOLE
CO
L
L
E
G
E
A
V
E
N
U
E
EXISTING 48" RCP
EXTEND EXISTING 48" RCP
TO COLLEGE AVE LIMITS
NORTH
F:
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1
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2
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1
8
1
0
:
2
8
A
M
LOCATION A: OVERFLOW CHANNEL FROM POND 366 TO POND 363
PROJECT NO: 17-049-SCBAPPR.REVISIONSNo. DATE
ICON
ENGINEERING, INC.
PREPARED BY:
Know what's below.
Call before you dig.1 OF 1
VERIFY SCALE
0 1"
BAR IS ONE INCH
ON ORIGINAL
DRAWINGS
SEPT 2018
PREPARED FOR:
NOT FOR CONSTRUCTION
ST ST
SO
U
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H
C
O
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L
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A
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M
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4
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1
)
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A
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+
0
2
.
0
0
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M
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5
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0
3
.
4
7
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V
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O
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9
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.
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(
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)
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4
4
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A
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2
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1
8
.
0
0
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=
5
0
0
6
.
5
0
'
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V
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(
4
8
"
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P
)
=
4
9
9
6
.
8
7
(
W
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V
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4
8
"
R
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9
9
6
.
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7
'
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E
)
ST
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M
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4
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A
:
6
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0
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=
4
9
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7
.
5
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'
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V
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4
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"
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4
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8
3
.
0
0
(
W
)
'
EXISTING
GROUND
4960
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+508+74
F:
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P
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LOCATION B: INCREASED CAPACITY UNDER COLLEGE AVENUE
PROJECT NO: 17-049-SCBAPPR.REVISIONSNo. DATE
ICON
ENGINEERING, INC.
PREPARED BY:
Know what's below.
Call before you dig.
PREPARED FOR:
1 OF 1
VERIFY SCALE
0 1"
BAR IS ONE INCH
ON ORIGINAL
DRAWINGS
SEPT 2018
PLAN AND PROFILE
NOTES:
NORTH
0
SCALE : 1" = 100'
100 200
TRILBY ROAD TRILBY ROAD
CO
L
L
E
G
E
A
V
E
N
U
E
LE
M
A
Y
A
V
E
N
U
E
SKYWAY DRIVE
CO
L
B
Y
S
T
E
E
T
C
B
A
D
NORTH TRIBUTARY
MIDDL
E
H
U
N
T
I
N
G
T
O
N
H
I
L
L
S
T
R
I
B
U
T
A
R
Y
SOUTH TRIBUTARY
E
TRIBUTARY
C1: PROPOSED STORM
SEWER SYSTEM
ST
O
N
E
C
R
E
E
K
STO
N
E
C
R
E
E
K
CO
L
L
E
G
E
A
V
E
N
U
E
D1: FLOODPLAIN REGULATIONS
D2: CROWN RIDGE LANE
CULVERT IMPROVEMENTS
(10'W X 3'H BOX CULVERT)
CROWN RIDGE LANE
PROVINCETOWNE
DEVELOPMENT
RICK DRIVE
A1: FLOODPLAIN DEVELOPMENT
REGULATIONS
A2: OVERFLOW CHANNEL TO POND
363 (RIPRAP LINED CHANNEL)
E1: Ditch Crossing Structure
B1: FLOODPLAIN
DEVELOPMENT REGULATIONS
B2: INCREASED CAPACITY
UNDER COLLEGE AVE
LEMAY AVENUE
CROSSING
IMPROVEMENTS
A
PROBLEM IDENTIFICATION
AREA LOCATIONS
COLLEGE AVENUE APPROXIMATELY
600-FEET NORTH OF TRILBY ROAD
B
COLLEGE AVENUE AT SKYWAY DRIVEC
D
E
SPILL FLOW TO PROVINCETOWNE
LOUDEN DITCH CROSSING
COLLEGE AVENUE 1,500-FEET
NORTH OF TRILBY ROAD
NORTH
0
SCALE : 1" = 300
300 600
F:
\
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n
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;
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t
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;
1
0
/
2
/
2
0
1
8
6
:
4
9
A
M
SELECTED PLAN IMPROVEMENTS
PROJECT NO: 17-049-SCBAPPR.REVISIONSNo. DATE
ICON
ENGINEERING, INC.
PREPARED BY:
Know what's below.
Call before you dig.1-1
VERIFY SCALE
0 1"
BAR IS ONE INCH
ON ORIGINAL
DRAWINGS
SEPT 2018
PREPARED FOR:
College & Trilby Multi-Family Community
Preliminary Drainage Report
APPENDIX F – MAPS
A
W
e
s
t
r
i
a
n
C
o
m
p
a
n
y
WEST TRILBY ROAD
SO
U
T
H
C
O
L
L
E
G
E
A
V
E
N
U
E
SO
L
A
R
C
O
U
R
T
Know what's below.
before you dig.Call
R
WEST TRILBY ROAD
SO
U
T
H
C
O
L
L
E
G
E
A
V
E
N
U
E
SO
L
A
R
C
O
U
R
T
LEGEND
EFFECTIVE SWMM DRAINAGE
BASIN DIVIDE LINE
(WITH DIRECTION OF FLOW)
CONVEYANCE ELEMENT
PROPOSED SWMM DRAINAGE
BASIN DIVIDE LINE
CIP PROPOSED CONVEYANCE ELEMENT
(WITH DIRECTION OF FLOW)
SUBBASIN
CIP SUBBASIN
CONVEYANCE ELEMENT - PIPE
CIP PROPOSED CONVEYANCE ELEMENT - PIPE
CONVEYANCE ELEMENT - SURFACE FLOW
CIP PROPOSED CONVEYANCE ELEMENT - SURFACE FLOW
CONVEYANCE ELEMENT - ORIFICE
CIP PROPOSED CONVEYANCE ELEMENT - ORIFICE
DETENTION POND
CIP PROPOSED DETENTION POND
NODE
CIP PROPOSED NODE
A
W
e
s
t
r
i
a
n
C
o
m
p
a
n
y
WEST TRILBY ROAD
SO
U
T
H
C
O
L
L
E
G
E
A
V
E
N
U
E
SO
L
A
R
C
O
U
R
T
Know what's below.
before you dig.Call
R
LEGEND
EFFECTIVE SWMM DRAINAGE
BASIN DIVIDE LINE
(WITH DIRECTION OF FLOW)
CONVEYANCE ELEMENT
PROPOSED SWMM DRAINAGE
BASIN DIVIDE LINE
CIP PROPOSED CONVEYANCE ELEMENT
(WITH DIRECTION OF FLOW)
SUBBASIN
CIP SUBBASIN
CONVEYANCE ELEMENT - PIPE
CIP PROPOSED CONVEYANCE ELEMENT - PIPE
CONVEYANCE ELEMENT - SURFACE FLOW
CIP PROPOSED CONVEYANCE ELEMENT - SURFACE FLOW
CONVEYANCE ELEMENT - ORIFICE
CIP PROPOSED CONVEYANCE ELEMENT - ORIFICE
DETENTION POND
CIP PROPOSED DETENTION POND
NODE
CIP PROPOSED NODE
A
W
e
s
t
r
i
a
n
C
o
m
p
a
n
y
WEST TRILBY ROAD
SO
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H
C
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E
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E
A
V
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N
U
E
SO
L
A
R
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R
T
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before you dig.Call
R
M
A
R
S
D
R
I
V
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NO
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A
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A
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G
A
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A
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a
n
C
o
m
p
a
n
y
WEST TRILBY ROAD
SO
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A
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N
U
E
SO
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A
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NO
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ST
A
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N
E
STELLAR DRIVE
LUNAR COURTBB
C C
A Westrian Company
COLLEGE & TRILBY MULTI-FAMILY COMMUNITY
#
#
#
PROPOSED SWMM MAP
Altitud
e
:
0
.
0
0
0
0
_
_
_
_
_
_
_
_
_
Name: C
o
l
l
e
g
e
_
T
r
i
l
b
y
_
G
E
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
Longitu
d
e
:
-
1
0
5
.
0
7
6
8
6
9
7
9
0
8
1
2
0
0
Latitud
e
:
4
0
.
4
9
4
5
6
2
4
2
7
4
7
3
3
3
_
_
LEGEND
(WITH DIRECTION OF FLOW)
CONVEYANCE ELEMENT
CIP SWMM DRAINAGE
BASIN DIVIDE LINE
CIP PROPOSED CONVEYANCE ELEMENT
(WITH DIRECTION OF FLOW)
SUBBASIN
CIP SUBBASIN
CONVEYANCE ELEMENT - PIPE
CONVEYANCE ELEMENT - SURFACE FLOW
CIP PROPOSED CONVEYANCE ELEMENT - SURFACE FLOW
CONVEYANCE ELEMENT - ORIFICE
CIP PROPOSED CONVEYANCE ELEMENT - ORIFICE
DETENTION POND
CIP PROPOSED DETENTION POND
NODE
CIP PROPOSED NODE
JR MODIFIED BASIN
BASIN DIVIDE LINE
JR PROPOSED NODE
JR MODIFIED SWMM DRAINAGE
JR PROPOSED DETENTION / WQ POND
JR PROPOSED CONVEYANCE ELEMENT - ORIFICE
JR PROPOSED RATING CURVE
JR PROPOSED CONVEYANCE ELEMENT
(WITH DIRECTION OF FLOW)
CIP PROPOSED CONVEYANCE ELEMENT - PIPE
A Westrian Company
TRILBY / COLLEGE
EX-DRAINAGE EXHIBT
College & Trilby Multi-Family Community
Preliminary Drainage Report
APPENDIX G –LID EXHIBIT
WEST TRILBY ROAD
SO
U
T
H
C
O
L
L
E
G
E
A
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E
N
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SO
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m
p
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n
y
Know what's below.
before you dig.Call
R
VA
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MA
R
S
D
R
I
V
E
MA
R
S
D
R
I
V
E
MO
O
N
B
E
A
M
W
A
Y
NO
V
A
L
A
N
E
NO
V
A
L
A
N
E
ST
A
R
D
U
S
T
L
A
N
E
STELLAR DRIVE
LUNAR COURTBB
C C
A
W
e
s
t
r
i
a
n
C
o
m
p
a
n
y
Know what's below.
before you dig.Call
R
Altitud
e
:
0
.
0
0
0
0
_
_
_
_
_
_
_
_
_
Name: C
o
l
l
e
g
e
_
T
r
i
l
b
y
_
G
E
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
_
Long
i
t
u
d
e
:
-
1
0
5
.
0
7
6
8
6
9
7
9
0
8
1
2
0
0
Latitud
e
:
4
0
.
4
9
4
5
6
2
4
2
7
4
7
3
3
3
_
_
VA
U
L
T
VA
U
L
T
VA
U
L
T
VA
U
L
T
VA
U
L
T
VA
U
L
T
VAULT
VAULT
VA
U
L
T
MA
R
S
D
R
I
V
E