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Project Development
Drainage and Erosion Control Report
Center for AdvancedTechnologies 22nd Filing
"Community Horticultural Center"
January 2003
Prepared for:
City of Fort Collins
Prepared by:
EDAW Inc.
240 East Mountain Avenue
Fort Collins, CO 80524
(970)484-6073
Job No. 717082.20
; Ana! ApprovPA Report
EDAW INC
240 EAST MOUNTAIN AVENUE January 10, 2003
FORT COLLINS COLORADO
Mr. Basil Hamdan
80524 City of Fort Collins
Stormwater Utility
700 Wood Street
TEL 970 484 6073 - Fort Collins, CO 80524
FAX 970 4E4 8518 Re: Project Development Drainage and Erosion Control Report for
W W W.eaaw.'com Center for Advanced Technologies 22nd Filing
"Community Horticultural Center"
Dear Basil:
We are pleased to submit for your review and approval this Project
Development Drainage and Erosion Control Report for the CAT 22nd Filing
"Community Horticultural Center."
We appreciate your consideration in reviewing this submittal. Please call if
you have questions.
Best
Encl. zF COI
UNITED STATES
EUROPE
�i
AUSTRALIA
ASIA DESIGN, PLANNING AND ENVIRONMENTS WORLDWIDE
TABLE OF CONTENTS
Page No.
INTRODUCTION..................................................................... 1
PROPOSED DEVELOPMENT ................................................ 2
HISTORIC OFF -SITE DRAINAGE ......................................... 2
PROPOSED OFF -SITE DRAINAGE ....................................... 2
HISTORIC ON -SITE DRAINAGE .......................................... 2
PROPOSED ON -SITE DRAINAGE ........................................ 2
DRAINAGE DESIGN CRITERIA ........................................... 3
BEST MANAGEMENT PRACTICE FOR WATER
QUALITY.................................................................................. 3
EROSION CONTROL DESIGN .............................................. 3
EROSION CONTROL SECURITY ......................................... 4
CONCLUSION.......................................................................... 4
APPENDIX
DRAINAGE CALCULATIONS
EROSION CONTROL CALCULATIONS
WATER QUALITY BMP CALCULATIONS
ROLLAND MORE DRIVE CULVERT
WINDTRAIL TOWNHOMES ADDENDUM
RIPRAP CALCULATIONS
1
Introduction
This report is submitted as a Project Development Drainage and Erosion Control
Report for the Fort Collins Community Horticultural Center, a parcel in a portion
of Tract C. Windtrail Townhomes PUD 0 Replat, and in the NE '/ of Section 23,
T7N, R 69 W, Fort Collins, Colorado. The parcel is 18.7 acres, bounded on the
east by Center Avenue, on the south by the proposed extension of Rolland Moore
Drive, on the west by Hill Pond and on the north by Spring Creek. This north
property line defines a 100-foot wide buffer strip on the north bank of Spring
Creek. Drainage elements on site interact with Spring Creek, Hill Pond, the
Sherwood Ditch Lateral and CSURF property south of the proposed Rolland
Moore Drive. The site is located within the Spring Creek Drainage Basin and
floodplain, and no detention is required
The northern portion of the site currently drains at less than 1 % to the south,
directly into Spring Creek, while the southern portion is interrupted by the
Sherwood Ditch Lateral. An existing suspended 12-inch CMP currently appears
to convey runoff from CSURF property to the south, across this ditch and towards
Spring Creek. The project proposes to maintain these drainage patterns by
replacing the suspended CMP with RCP culverts under the Sherwood Ditch.
Portions of the project lie within the 100-year floodplain of Spring Creek. An
evaluation of the site was performed to identify the 100-year floodplain on the site
at a fully developed condition prior to improvement. It is entitled, Hydraulic
Evaluation of the Community Horticultural Center Fort Collins, Colorado (Based
on the City of Fort Collins Fully Developed Condition Hydrology), dated
December 29, 2000 (revised April 27, 2001), by Anderson Consulting Engineers
Incorporated. Minor regrading of the site has increased the flood storage of the
Spring Creek channel. An evaluation of the revised site grading is contained in
the Hydraulic Evaluation of the Community Horticultural Center Fort Collins,
Colorado (Prepared in Support of a Conditional Letter of Revision for the
Community Horticultural Center Project), dated December 21, 2000 (Revised
April 2, 2001), by Anderson Consulting Engineers, Incorporated. The conditional
letter of map revision has been approved. Additional hydraulic analysis and
hydraulic design of the Horticultural Center Outfall Channel, by Anderson
Consulting Engineers, Incorporated (September 4, 2002), has subsequently been
undertaken and is an Addendum to this report.
As part of this project, the intermediate route of the Sherwood Lateral will be
shifted to the north, although the endpoints at Spring Creek and at Centre Avenue
will remain in their present location.
Although no detention is required on the site, BMP's will address stormwater
quality. They will consist of porous landscape, a wetlands basin and a grassed
swale that will treat low flow, while allowing high flow events to bypass into
Spring Creek.
An erosion control plan and report will address erosion potential during
construction.
Proposed Development - A horticulture garden will be constructed on the
site and will include a main building/conservatory in its first phase of
construction. This building is being built outside of the floodplain. There will
also be minor site furnishings including, three bike racks (not in the floodplain),
one bike rack and two benches (in the flooplain). These site furnishings will be
installed as part of the first phase of construction; these improvements will be
secured to the ground so they will not be allowed to move during a flood. They
will be surface mounted using expansion bolts in concrete and vandal proof bolts
to resist theft and tampering.
Historic Off -Site Drainage — Historic off -site drainage comes from
11.52 acres of CSURF property to the south, as well as from 0.7 acre immediately
west of the property. Although a suspended 12-inch CMP appears to convey
some amount of water across the Sherwood Lateral and thence to Spring Creek,
the Addendum to the Final Drainage Report of the Windtrail PUD Townhomes
Site, Lidstone & Anderson, 1995, indicates that off -site flows are diverted to
Sherwood Lateral by a berm designed with that report.
Proposed Off -Site Drainage - From Spring Creek Basin Master Drainage
Plan, Baseline Hydrology, (Anderson Consulting Engineers, Incorporated,
November 2001), the subject property is located in SWMM Subbasin 130, which
encompasses 90.3 acres. The fully developed percent impervious assumed for the
subbasin is 50. The Master Plan SWMM model assumes no on -site detention for
the subbasin. Runoff from the subbasin enters Spring Creek via conveyance
element 130. From the Master Plan SWMM model, Q100/CE130 = 453 cfs. This
implies the unit runoff from the subbasin is 5.0 cfs/ac. The 100-year runoff from
the contributing 11.52 acres is estimated to be 57.6 cfs. Q100/t, ', = 64.3 cfs
(Anderson Consulting Engineers, Incorporated, September 2002). Those flows,
which include those from the west between the Windtrail berm and the west
property line of the Horticultural Center, will be routed through a grassed swale
and thence to Spring Creek via culverts under the proposed Sherwood Lateral.
Historic On -Site Drainage — The northern portion of the site currently
drains at less than 1 % to the north, directly into Spring Creek, while the southern
portion is interrupted by the Sherwood Ditch Lateral. An existing suspended
12-inch CMP currently conveys runoff across this ditch and towards Spring
Creek.
Proposed On -Site Drainage — Development of the property will cause an
increase of discharge into Spring Creek. Approximately 10% of the site will be
2
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W impervious, with the remaining portion developed as playgrounds and gardens.
No detention is required on the site. However, a combination of culvert and
overland flow will convey the developed runoff to Spring Creek. Other that an
area immediately adjacent to Sherwood Lateral, no runoff will enter the lateral
except during a 100-year event. At such time, the 100-year ponding elevation of
4,997.2 feet will inundate the lateral and the proposed culverts, conveying the
developed 100-year runoff into Spring Creek. Although the culverts will be
inundated during a 100-year event, they are designed to convey that flow for such
time as there is a hydraulic gradient towards Spring Creek. At the time of peak
runoff along the Horticultural Center outfall, the peak flow is not occurring along
Spring Creek. The 100-year discharge on Spring Creek in the vicinity of the
outfall is 3,611 cfs (Conveyance Element 327 from the Master Plan SWMM
Model (Anderson Consulting Engineers, Incorporated, November 2001). The
peak occurs at time 1:22 from the beginning of the storm. At time 0:37, the time
of the peak for the outfall, the 100-year discharge on Spring Creek is 1,108 cfs.
At time 1:22, the time of the peak flow on Spring Creek, the 100-year discharge
for Conveyance Element 130 is 81 cfs. The associated discharge for the outfall is
17.0 cfs (Anderson Consulting Engineers, Incorporated, September 2002)
During extended periods of low flow events the channel will be kept silt free by
the facility maintenance staff to avoid problems during larger events. Care will be
taken to perform this channel maintenance on a regular basis at 6 month intervals.
Drainage Design Criteria — Drainage criteria are based on the City of Fort
Collins Storm Drainage Design Criteria, and calculations use the rational method.
Best Management Practice for Water Quality — Best management
practices are employed per the criteria of the Denver Urban Storm Drainage
Criteria Manual, Vol. 3. On -site and off -site runoff is treated by several methods.
The parking lot runoff is conveyed by an adjacent grassed Swale to a porous
landscape pond underlain by a perforated pipe. Flows in excess of the WQCV will
continue down the swale to a wetlands basin. The basin has a permanent pool,
but provides freeboard to accept the designated WQCV and a perforated orifice to
control the rate of discharge to Spring Creek. Two other basins are also treated
with porous landscape ponds. In addition, off -site runoff from CSURF is
conveyed to storm drainage culverts via a grassed swale.
Erosion Control Design — The Community Horticultural Center site lies
within moderate rainfall and wind erodability zones per City of Fort Collins zone
maps. Potential for erosion exists as construction commences and until paving
and landscaping are completed. The site is required to meet a rainfall erosion
performance standard of 79.8 during construction, and a performance standard of
91.8 after construction. Wind erosion is mitigated by the same cover methods that
IPaddress rainfall erosion.
3
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Overlot grading will begin in the winter of 2001. The northern portion will be
reseeded and straw -mulched. Parking lot paving will not be installed until spring
of 2002, but the site will over -winter with a combination of covers and sediment
traps to control erosion. These include straw mulch, hydromulch and disking, as
well as silt fences, straw bale dikes and sediment traps.
Prior to construction, silt fencing will be installed around the entire site. Basins
A3a, A3b and A3c will drain to inlets interior to the site. Basin Al will drain to a
water quality pond, which will function as a sediment trap during construction.
These facilities will be installed within approximately 8 weeks. During
construction, straw bale dikes will protect these inlets. At completion of
construction, the entire site will be hard surfaces or landscaped.
Erosion Control Security
Temporary erosion control measures:
Measure Unit Qty. Unit Cost Total
Sediment trap
EA
3
200
$600
Straw mulch
MSF
624
13.00
$8110
Silt fence
LF
3,985
0.75
$2989
Hydromulch
SY
1,600
0.75
$1200
Straw bale dike
EA
20
$180
Total
$135079
Security = $13,079 x 1.5 = $19,618
Conclusion — All design and computations will be completed in compliance
with the City of Fort Collins Storm Drainage Design Criteria. The site does not
substantially change existing drainage patterns. All site drainage will be directed
to Spring Creek through existing and new conveyances.
Erosion control measures will protect Spring Creek from excessive wind and
water -born sediment. The project will also be scheduled to minimize the time
bare ground is exposed to the elements.
4
Drainage Calculations
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16
Erosion Control Calculations
I.
Water Quality BMP Calculations
S
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t
Rolland Moore Drive Culvert
Windtrail Townhomes Addendum
F
■
4
Riprap Calculations
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Attachment B
r
Interpretive Plan Historical Inaccuracies: Will Bagley
Historical Errors and Suggested Corrections
Handcarts played a relatively minor role in emigration on the Mormon Trail but
had nothing to do with the California Trail. A few crazies set out from the Missouri
with wheelbarrows, but only one of them might have made it across the Rockies.
Many "Californians" cut down wagons into carts but used draft animals to haul
them. A very important mode of travel— "packing," or using pack trains, almost
always employing mules. There are great stories about the difficulties of packing
and managing mules, who truly played a colorful and important role in the trail's
history.
Correction: Scrap the handcart, get a mule and pack frame.
Correction: Sierra Nevada Mountains is redundant. It's Sierra Nevada, singular,.
PERIOD.
Correction: "The era of the transcontinental train began in the 1870s, and ended the
mass migration over the California Trail." Try: "The transcontinental railroad was
completed at Promontory Summit in 1869 and basically ended mass migration over the
California Trail."
Correction: The "Stevens Party" is usually called the "Stephens -Murphy -Townsend
Party." Note correct spelling of "Stephens"
Correction: The Lavinia Porter diary quote is repeated in "Jumping Off' and "The
Great Basin."
Correction: "Do you empty the wagons and put your belongings on a raft?" Never
happened. Bridges also began appearing in 1850.
Correction: "Oak trees, cottonwoods, foxglove, wild pea, lupine." Except on islands,
there were practically no trees (and absolutely not a single oak) on the Platte River
east of Fort Laramie, hence the use of buffalo chips. One 1847 traveler said he saw
no timber between Green River and the Sierra.
Correction: "The time in camp was the time for cooking and leisure, like playing music
and games for the children." There was damn little "leisure" on the trail. There are many
accounts of music and dancing, but I don't recall ever seeing a reference to children
playing games. They did chores. Rosemary Gudmundson Palmer's Children's Voices
from the Trail: Narratives of the Platte River Road (Spokane: The Arthur H. Clark Co.,
2002) has no entry for "games" in its index, but dozens for "chores."
Correction: "The travelers met the tribes that made their homes on the plains: the Caw,
Kansa, Pawnee, Shawnee, Delaware, Crow, Cheyenne, Lakota, and Arapaho." The Caw
and Kansa are the same tribe. You really have two cultural groups here: On the frontier,
nations such as the Shawnee, Delaware, Saux, Fox, and Pottawattamie were known as
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"civilized tribes." They often lived near missions, farmed, and ran ferries and bridges.
Pawnee lived between the civilized tribes and the Plains Indians and were continually at
war with them. The Crow, Cheyenne, Lakota, and Arapaho were Plains Indians
sometimes encountered on the Platte River hunting buffalo or congregated at Fort
Laramie.
Correction: "Cathedral Rocks." Use the modern name (for the NPS site), City of Rocks.
Correction: Guides were occasionally available at Fort Hall for the next leg of the
journey.
Correction: Ice Slough (/Ice Spring) was a flat swamp, not a very striking landscape.
Correction: Cut "How do you cross the Humboldt River?" When it flooded, people did
drown in the Humboldt, but it was easy to ford.
Correction: Virginia Reed writes in 1847: "Don't take no cut-offs and get where you're
going as fast as you can." No she didn't. She wrote," never take no cutofs and hurt' along
as fast as you can."
Correction: "California and El Dorado." California is El Dorado.
Vocabulary
Most American Indians now avoid the confusing term "Native Americans."
Avoid terms like "undisturbed" and "wilderness." Indians had been transforming the
West for about 12,000 years.
Will Bagley
Attachment A
i
Existing and suggested AInterpretive Exhibit Outline@
Organization
This section shows the original structure of the Alnterpretive Exhibit Outline, @ starting on Page 52 of the
ASchematic Design of the California National Historic Trail Interpretive Center@ and ending on Page 63.
The second section, ASuggested Interpretive Center Exhibits Reorganization@ shows a simplified and
resequenced outline. CWill Bagley
Existing
INTERPRETIVE exhibit outline.................................................................................................................
2
OUTSIDEEXHIBITS ....................... :.......................................................................................................
2
EntryRoad...................................................................................................................................
2
PlazaArea....................................................................................................................................3
Pathto Day Use Area/Panels................................................................................................................3
INTERPRETIVE CENTER EXHIBITS...................................................................................................
4
HistoryTheater............................................................................................................................4
WhyGo Video Wall ............................................................... :....................................................5
WagonCross-Section..................................................................................................................
6
Migration Station 1 - Character Cards and Provisioning.......................................................
6
WagonDesign Interactive..........................................................................................................6
JumpingOff.............................................................................................................................................
6
Diariesand Journals....................................................................................................................
6
WallMap - The West in 1841.....................................................................................................
7
Migration Station 2 - Join a Party ..............................................................................................
7
JumpingOff StoriesCCut............................................................................................................
7
Marketingand Maps...................................................................................................................
7
TrailZooms - Jumping Off.........................................................................................................8
PlatteRiver Road.....................................................................................................................................
8
Diariesand Journals....................................................................................................................
8
WallMap - Platte River Road....................................................................................................8
Migration Station 3 - Crossing the River..................................................................................
8
Shoeingan Ox, Moving a Mule.................................................................................................
9
Platte River Road / Campsite Diorama...................................................................................
9
Trail Zooms - Platte River Road................................................................................................
9
RockyMountains....................................................................................................................................
9
Wall Map - Rocky Mountains..................................................................................................10
Migration Station 4 - Cutoffs and Shortcuts..........................................................................10
Fort Hall - Meeting Place for All People................................................................................10
AlienLandscapes......................................................................................................................10
Character Gallery: Explorers..................................................................................................11
Trail Zooms - Rocky Mountains..............................................................................................11
Great Basin and the Humboldt River Road.......................................................................................11
WallMap - The Great Basin.....................................................................................................11
Migration Station 5 - The Great Basin....................................................................................11
Diariesand Journals..................................................................................................................12
Western Shoshones and Northern Paiutes.............................................................................12
r
PeopleWall - The Mormons....................................................................................................12
WaterWall: The Humboldt.....................................................................................................13
DesertDiorama..........................................................................................................................13
Modern Day Connections........................................................................................................13
OutdoorPlaza............................................................................................................................13
Trail Zooms - The Great Basin.................................................................................................14
SierraNevada Mountains....................................................................................................................14
.
Wall Map - Sierra Nevada Mountains....................................................................................14
Migration Station 6 - The Sierra Nevada Mountains............................................................14
Seeingthe Elephant...................................................................................................................14
RoutesTimeline.........................................................................................................................14
Trail Zooms - Sierra Nevada Mountains................................................................................15
California and El Dorado.........................................................................................................15
WallMap B California..............................................................................................................15
Migration Station 7 - California Choices................................................................................15
.
Endof the Trail..........................................................................................................................15
Transformation of California...................................................................................................16
TheGold Rush...........................................................................................................................16
Endof an Era..............................................................................................................................16
TheCalifornia Trail Today .......................................... :............................................................
16
Suggested Interpretive Center Exhibits Reorganization
InterpretiveCenter Exhibits..................................................................................................................
4
History Theater " The West in 1841"?.......................................................................................
4
-The West in 1841
Character Gallery: Explorers...................................................................................................11
Wall Map: Exploration
WhyGo West? Video Wall .........................................................................................................5
JumpingOff.............................................................................................................................................
6
Wall Map - The Missouri Frontier and Indian Country.........................................................
8
Fitting Out at Independence, St. Joseph, Council Bluffs........................................................
7
Migration Station 1 - Character Cards and Provisioning.......................................................
6
WagonCross-Section..................................................................................................................
6
Diariesand Journals....................................................................................................................
6
Migration Station 2 - Join a Party ..............................................................................................
7
Marketing and Maps.,....,. ... .................................................................
aps...................................................................................................................
****7
"Civilized" Indians
TrailZooms - Jumping Off.........................................................................................................
8
PlatteRiver Road.....................................................................................................................................
8
WallMap - Platte River Road....................................................................................................8.
Diariesand Journals....................................................................................................................8
Campsite Diorama / Day on the Trail......................................................................................9
The Plains Indians
Migration Station 3 - Crossing the River..................................................................................8
Shoeing an Ox, Moving a Mule.................................................................................................
9
Trail Zooms - Platte River Road................................................................................................
9
RockyMountains....................................................................................................................................
9
WallMap - Rocky Mountains..................................................................................................10
Diariesand Journals....................................................................................................................8
Migration Station 4 - Cutoffs, Shortcuts, and "Death Routes"
.............................................10
Fort Hall - Crossroads of the West..........................................................................................10
AlienLandscapes.....................:................................................................................................10
TrailZooms - Rocky Mountains..............................................................................................11
Great Basin and the Humboldt River Road.......................................................................................11
WallMap - The Great Basin.....................................................................................................11
Migration Station 5 - The Great Basin....................................................................................11
Diariesand Journals..................................................................................................................12
Western Shoshones and Northern Paiutes.............................................................................12
Lansford Hastings, the Donner Party, and Manifest Destiny
.............................................12
PeopleWall - The Mormons....................................................................................................12
WaterWall: The Humboldt.....................................................................................................13
DesertDiorama..........................................................................................................................13
OutdoorPlaza............................................................................................................................13
Trail Zooms - The Great Basin.................................................................................................14
"A Wall of Granite" The Sierra Nevada.............................................................................................14
Wall Map - Sierra Nevada Passes...........................................................................................14
Migration Station 6 - The Sierra Nevada................................................................................14
Seeingthe Elephant...................................................................................................................14
RoutesTimeline.........................................................................................................................14
Trail Zooms - Sierra Nevada....................................................................................................15
California Gold Rush: The New El Dorado...........................................................................15
Endof the Trail..........................................................................................................................15
The American West Transformed, 1870
Endof an Era..............................................................................................................................16
Modern Day Connections........................................................................................................13
The California Trail Today.......................................................................................................16
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16
Drainage Calculations
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Fort Collins Horticultural Center
Storm Drainage Report
EDAW Job No. 7F082.20
By:
KF
Date:
4/1712001
Revised:
Composite Runoff Coefficients
■
Surface
(Ac)
%
Coefficient Contributing
Basin
Type
Area
Area
"C" "C"
Al
Parking
1.17
0.16
0.95 0.15
Paths
0.62
0.08
0.50 0.04
Vegetated
5.62
0.76
0.25 0.19
Runoff
Sum
7.41
1.00
0.38
Coefficient
Surface
(Ac)
%
Coefficient Contributing
Basin
Type
Area
Area
ICI. T.,
WQA1a
Parking
1.17
0.45
0.95 0.43
Vegetated
1.42
0.55
0.25 0.14
Runoff
Sum
2.59
1.00
0.57
Coefficient
■
Surface
(Ac)
%
Coefficient Contributing
Basin
Type
Area
Area
"C" "C'.
Alb
Vegetated
1.81
1.00
0.25 0.25
Runoff
Sum
1.81
1.00
0.25
Coefficient
Surface
(Ac)
%
Coefficient Contributing
Basin
Type
Area
Area
"C" "C'.
A2
Paths
0.26
0.04
0.50 0.02
Vegetated
6.18
0.96
0.25 0.24
Runoff
■
Sum
6.44
1.00
0.26
Coefficient
Surface
(Ac)
%
Coefficient Contributing
Basin
Type
Area
Area
T.p "C"
A4
Vegetated
2.53
1.00
0.25 0.26
Runoff
Sum
2.53
1.00
0.25
Coefficient
Surface
(Ac)
%
Coefficient Contributing
Basin
Type
Area
Area
ICI. "C"
Ma
Parking
0.21
0.09
0.95 0.08
Paths
0.21
0.09
0.50 0.04
Vegetated
1.93
0.82
0.25 0.21
Runoff
Sum
2.35
1.00
0.33
Coefficient
Surface (Ac) % Coefficient Contributing
Basin
Type
Area
Area
T,. "C..
A3b
Bldg.
0.13
0.09
0.95 0.09
Paths
0.13
0.09
0.50 0.05
Vegetated
1.13
0.81
0.25 0.20
Runoff
Sum
1.39
1.00
0.34
Coefficient
Surface
(Ac)
%
Coefficient Contributing
Basin
Type
Area
Area
IC" T.,
AU
Road
0.
0.0.06
Field @4%
11
11
0.94 94
0.30 30 0.2828
Runoff
Sum
11.70
1.00
0.34
Coefficient
Surface
(Ac)
%
Coefficient Contributing
Basin
Type
Area
Area
"C" "C..
B
Bldg/Paving
0.29
0.20
0.95 0.19
Vegetated
1.14
0.80
0.25 0.20
Runoff
Sum
1.43
1.00
0.39
Coefficient
Erosion Control Calculations
Horticultural Center
Storm Drainage Report
EDAW Job No. 7F082.20
By: KF
Date: 4/17/2001
Revised:
Rainfall Performance Standard Evaluation
Standard Form A
Developed
Basin
Erodability Asb
Zone (ac)
Lsb
(ft
Ssb
%
Lb
(ft)
Sb
M
PS
A4
mod
2.53
70
0.02
8
0.0024
A3c
mod
1.27
400
0.028
24
0.0017
A3b
mod
1.39
350
0.023
23
0.0015
Ma
mod
2.35
430
0.02
47
0.0022
Al
mod
7.41
1230
0.013
426
0.0045
A2
mod
6.44
1015
0.01
306
0.0030
B
mod
1.43
550
0.002
37
0.0001
Total
21.39
870
0.0154 79.8
EFFECTIVENESS CALCULATIONS
PROJECT: „�} �, l l k 5� Q �✓ STANDARD FORM B
COMPLETED BY:,,, Farcc _ Fps DATE:
Erosion Control C-Factor P-Factor
Method Value Value Comment
(7c �. c o. O -a[ O
E OU4\1 3D�,
t
S{�►-"c".,.�1�u� 0.0Cv L. 0p.0
S-EYA.J �a�G� 1 . O O O.pr
5�1� Face. 1. 00 O.S-a
52.ci.True L-co 0.S0
�d: Vk,4c.L 0.(0 1. CID
r
V a.o� �.00
MAJOR
BASIN
PS
SUB
BASIN
AREA
(t)
(Ac)
CALCULATIONS
A+
11. 7
A 4
2. S3
w"c.4, c = o o (0.
SiOc F =o.so
4
_79-q'
A
f;.(�A3
c
M b
SGz'..yn��'.-�-P P ° •sap
\ / /� l
l+`1A7lo
,t
(0.A0 r 0.50 Y.0. iCD� c (c `c� (G.47 °,�.
a
a�
71. 9
A l
T 4(
w �5►. �m.. d P= 0, 10 e 1. 7q a �
1C.7
O. s Snr�r( o i0,3o1'
�i� e } �a.(o2x 0,01o%x0.1<O = 97 j
A� J c
AZ4
q4
Z.d I
Ste a.,- pa^jawk C : o.o( si
e.IrtS ac- 9-'a......a'"'k G = 0.0&1 COr2�D5
\
tmShZ ` �-rJ��10 ,c c.ol t &x? X o.oto
(D 4y e
P�
t ,4
= o. r o
0.847
o,�-o\)
MARCH 1991 8-15 DESIGN CRITERIA
1'1LT
1 r n CONSTRUCTION SEQUENCE
PROJECT: ✓i Gam. `�� v i^�' STANDARD FORM C
SEQUENCE FOR 299 ONLY COMPLETED BY: Il ZED?i DATE: l� - O
Indicate by use of a bar line or symbols when erosion control measures will be installed.
Major modifications to an approved schedule may require submitting a new schedule for
approval by the City Engineer.
` MONTH
YEAR I$vp104IN 19 I TI FIMI AIK ITIT IA I
tOVERLOT GRADING
WIND EROSION CONTROL
Soil Roughening
Perimeter Barrier
IP Additional Barriers
® Vegetative Methods1\
Soil Sealant
Other
RAINFALL EROSION CONTROL
STRUCTURAL:
Sediment Trap/Basin
Inlet Filters
Straw. Barriers
Silt Fence Barriers
Sand Bags
Bare .Soil Preparation
Contour Furrows
Terracing
Asphalt/Concrete- Paving
Other
VEGETATIVE:
Permanent Seed Planting
Mulching/Sealant
Temporary Seed Planting
Sod Installation
Nettings/Mate/Blankets
Other
-----------------------
S
STRUCTURES: INSTALLED BY COIa-c.A MAINTAINED BY
VEGETATION/MULCHING CONTRACTOR
DATE SUBMITTED
MARCH 1991
APPROVED BY CITY OF FORT COLLINS ON
8-16
DESIGN CRITERIA
Water Quality BMP Calculations
Horticultural Center
Storm Drainage Report
Porous Landscape Detention, Water Quality Pond
EDAW Job No. 7F082.20
By: KF/GAH
Date: 9/19/2002
Revised:
Based On Denver Urban Drainage Criteria Manual, Vol. 3.
(Hr.)
(Ac.) (S.F.) Runoff Coefficient (In.)
(C.F.)
Basin Drain Time
Area Area "C" WQCV
Design Vol.
A3b 12
1.28 55,757 0.4 0.145
674 Storage Vol.
Design Surface Area
(Design Vol./ avg. depth)
(C.F.) (Ft.)
(S.F.)
Design Vol. D(avg)
Design Area
674 0.50
1,347
1,347 Surface Area
(Hr.) (Ac.) (S.F.) Runoff Coefficient (In.) (C.F.)
Basin Drain Time Area Area ..C.. WQCV Design Vol.
Ala 12 2.59 112.820 0.6 0.19 1.786
Design Surface Area (Design Vol./ avg. depth)
(C.F.) (Ft.) (S.F.)
Design Vol. D(avg) Design Area
1,786 0.50 3,573 3,573 Surface Area
(Hr.) (Ac.) (S.F.) Runoff Coefficient (In.) (C.F.)
Basin Drain Time Area Area "C" WQCV Design Vol.
Alb 12 1.81 78.844 0.25 0.11 723 Storage Vol.
Design Surface Area
(Design Vol./ avg. depth)
(C.F.) (Ft.)
(S.F.) .
Design Vol. D(avg)
Design Area
723 0.58
1,246 1
(Hr.) (Ac.) (S.F.) Runoff Coefficient (In.) (C.F.)
Basin Drain Time Area Area C" WQCV Design Vol.
Al 24 4.38 190.793 0.25 0.12 1.908
Design Surface Area (Design Vol./ avg. depth)
(C.F.) (Ft.) (S.F.)
Design Vol. D(avg) Design Area
1,908 0.23 8,295 8,295 Surface Area
Total
10.06 acres
PROJECT: Fort Collins Horticultural Center
Storm Drainage Report - Water Qual
Prepared by: EDAW inc.
Date: ###k###
Manning's Equation, Pipe & Channel
Grassed Swale A3a (Section B-E
Q2 = 7.5 cfs
Quo = 33.7 cfs
CHANNEL AND PIPE DATA
e':.lA(;''ml`i':i;ii<>'1€€€ feet
.......................:........................
...............................................
---§.<;fUft
feet
ADDITIONAL PIPE DATA
Pipe Diann. =
0.00 inches
Prcnt Full =
0 percent
.5 cfs req'd. for Q2-hist
RESULTS - PIPE
Flow [cfs] _ #DIV/01
Flow [gpm] _ #DIV/0!
Vel [fps]_ #DIV/01
CHANNEL AND PIPE DATA
...............................................
................................................
...............................................................................................
feet
...............................................
ftfft
%uul€s i<i?3
feet
ADDITIONAL PIPE DATA
Pipe Diam. =
0.00 inches
Prcnt Full =
0 percent
33.7cfs req'd for Q100-hist
Rolland Moore Drive Culvert
rn Cl uO
c W N
'L r ui
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tq p
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w a
0
RUNOFF COEFFICIENTS & % IMPERVIOUS
LOCATION: Rolland Moore Drive
PROJECT NO: 9023.30
COMPUTATIONS BY: A. Reed (modified OS-1 by D. Mattson)
DATE: 912012002
Recommended Runoff Coefficients from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Streets, parking lots (asphalt)
Sidewalks (concrete)
Roofs
Lawns (flat <2%, sandy soil)
Runoff
%
coefficient
Impervious
C
0.95
100
0.95
96
0.95
90
0.20
1 0
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 8525
SUBBASIN
DESIGNATION
TOTAL
AREA
(ac.)
TOTAL
AREA
(sq.ft)
ROOF
AREA
(sq.ft)
PAVED
AREA
(sq.ft)
SIDEWALK
AREA
(sq.ft)
LANDSCAPE
AREA
(sq.ft)
RUNOFF
COEFF.
(C)
%
Impervious
101
1.35
58,685
0
16,417
4,665
35,603
0.49
39.01
102
0.72
31,305
0
16,985
4,496
7.821
0.76
74.44
0S-1'
8.93
388,961
90,000
125,000
35,000
138,961
0.68
61.60
OS-2
0.70
30,385
0
0
0
30,385
0.20
1 0.00
i nio w vaacu �Nvn uno vamp ucniy ucv ciuNcu.
Equations
- Calculated C coefficients & % Impervious are area weighted
C=E(Ci Ai) /At
Ci = runoff coefficient for specific area, Ai
Ai = areas of surface with runoff coefficient of Ci
n = number of different surfaces to consider
At = total area over which C is applicable; the sum of all Ai's
flow-ftcoll ins -revised
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JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 8525
2-YEAR HISTORIC FLOWS
LOCATION: Rolland Moore Drive
PROJECT NO: 9023.30
COMPUTATIONS BY: A. Reed (modified OS-1 by D. Mattson)
DATE: 9/20/2002
Recommended Runoff Coefficient from Table 3-3 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Runoff
coefficient Impervious
C
Lawns (flat <2%, sandy soil): 0.10 0
Lawns (average, 2-7%, sandy soil): 0.15 0
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
----------
Equations
- Calculated C coefficients & % Impervious are area weighted
C=E(Ci Ai) /At
Ci = runoff coefficient for specific area, Ai
Ai = areas of surface with runoff coefficient of Ci
n = number of different surfaces to consider
At = total area over which C is applicable; the sum of all Ai's
Q=CfCIA
Q = peak discharge (cfs)
C = runoff coefficient
Cf = frequency adjustment factor
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
ti=[1.87(1.1-CCf)L051/S1/3
I = 261(10+ ti)0 "
flow-ftcol Tins -revised
2
. JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
RATIONAL METHOD PEAK RUNOFF
(City of Fort Collins, 2-Yr Storm)
Rolland Moore Drive
9023.30
A. Reed (modified OS-1 .by D. Mattson)
09/20/02
2 yr storm, Cf = 1.00
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design
Point
Tributary
Sub -basin
A
(ac)
C Cf
tc
(min)
i
(in/hr)
Q (2)
(cfs)
from
Design
Point
Q (2)
(cfs)
Q(2)tot
(cfs)
1
101
1.35
0.49
9.6
2.27
1.51
1.51
2
102
0.72
0.76
7.4
2.49
1.36
1.36
OS-1•
8.93
0.68
13.1
1.98
12.07
12.07
Developed Condtions
OS-2
0.70
0.20
12.0
2.07
0.29
0.29
Q=CfCiA
Q = peak discharge (CIS)
C = runoff coefficient
Cf = frequency adjustment factor
i = rainfall intensity (in/hr) from City of Fort Collins OF curve (4/16/99)
A = drainage area (acres) i = 24.221 / (10+ tc)0'96e
flow-ftcol Tins -revised
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
RATIONAL METHOD PEAK RUNOFF
(City of Fort Collins, 10-Yr Storm)
Rolland Moore Drive
9023.30
A. Reed (modified OS-1 by D. Mattson)
09/20/02
10 yr storm, Cf = 1.00
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design
Point
Tributary
Sub -basin
A
(ac)
C Cf
tc
(min)
i
(inthr)
Q (10)
(cfs)
from
Design
Point
Q (10)
(cfs)
Q(10)tot
(cfs)
1
101
1.35
0.49
9.6
3.87
2.58
2.58
2
102
0.72
0.76
7.4
4.25
2.33
2.33
OS-1
8.93
0.68
13.1
3.38
20.62
20.62
Developed Condtions
OS-2
0.70
0.20
12.0
3.53
0.49
0.49
Q=CfCiA
Q = peak discharge (cfs)
C = runoff coefficient
Cr = frequency adjustment factor
i = rainfall intensity (in/hr) from City of Fort Collins OF curve (4/16/99)
A = drainage area (acres) i = 41.44 f (10+ tc)o.reu
flow-ftcollins-revised
JR Engineering
2620 E. Prospect Rd., Ste. 190
Fort Collins, CO 80525
RATIONAL METHOD PEAK RUNOFF
(City of Fort Collins, 100-Yr Storm)
LOCATION: Rolland Moore Drive
PROJECT NO: 9023.30
COMPUTATIONS BY: A. Reed (modified OS-1 by D. Mattson)
DATE: 09/20/02
100 yr storm, Cf = 1.25
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Des.
Point
Area
Design.
A
(ac)
C Cf
tc
(min)
i
(in/hr)
Q (100)
(cfs)
from
Design
Point
Q (100)
(cfs)
Q(100)tot
(cfs)
1
101
1.35
0.62
8.5
8.25
6.87
6.9
2
102
0.72
0.95
5.8
9.36
6.41
6.4
OS-1•
8.93
0.85
10.7
7.57
5T60
57.6
Developed Condtions
OS-2
0.70
0.25
11.61
T32
1.28
1.3
Q=CiA
Q = peak discharge (cfs)
C = runoff coefficient
i = rainfall intensity (in/hr) from City of Fort Collins OF curve (4/16/99)
A = drainage area (acres) i = 84.682 / (10+tc)0,797S
c
flow-Rcollins-revised
r
------------------------------------------------------------ .----------------
UDINLET: INLET HYDARULICS AND SIZING
DEVELOPED BY
CIVIL ENG DEPT. U OF COLORADO AT DENVER
SUPPORTED BY METRO DENVER CITIES/COUNTIES AND UD&FCD
ER:JR ENGINEERS-DENVER CO .................................................
ON DATE 01-17-2003 AT TIME 10:03:41
** PROJECT TITLE: ROLLAND MOORE
*** COMBINATION INLET: GRATE INLET AND CURB OPENING:
*** GRATE INLET HYDRAULICS AND SIZING:
INLET ID NUMBER: 1
s
INLET HYDRAULICS: IN A SUMP.
GIVEN INLET DESIGN INFORMATION:
INLET GRATE WIDTH (ft)= 1.87
INLET GRATE LENGTH (ft)= 3.25
INLET GRATE TYPE =Type 16 Grate Inlet
NUMBER OF GRATES = 1.00 _
SUMP DEPTH ON GRATE (ft)= 0.17
GRATE OPENING AREA RATIO M = 0.60
IS THE INLET GRATE NEXT TO A CURB ?-- YES
Note: Sump is the additional depth to flow depth.
m STREET GEOMETRIES:
STREET
LONGITUDINAL
SLOPE (°s) =
0.80
STREET
CROSS SLOPE
(%) =
2.00
STREET
MANNING N
=
0.016
GUTTER
DEPRESSION
(inch)=
2.00
GUTTER
WIDTH
(ft) =
2.00
STREET FLOW HYDRAULICS:
WATER SPREAD ON STREET
(ft) =
14.50
GUTTER FLOW DEPTH
(ft) =
0.46
FLOW VELOCITY ON STREET
(fps)=
3.02
FLOW CROSS SECTION AREA
(sq ft)=
2.27
GRATE CLOGGING FACTOR
(%)=
50.00
CURB OPENNING CLOGGING
FACTOR(%)=
20.00
INLET INTERCEPTION CAPACITY:
FOR 1 GRATE INLETS:
DESIGN DISCHARGE (cfs)= 6.90
IDEAL GRATE INLET CAPACITY (cfs)= 10.40
BY FAA HEC-12 METHOD:
FLOW INTERCEPTED (cfs)= 5.20
BY DENVER UDFCD METHOD:
FLOW INTERCEPTED (cfs)= 5.20
*** CURB OPENING INLET HYDRAULICS AND SIZING:
CINLET ID NUMBER: 1
i
M
r
16
INLET HYDRAULICS: IN A SUMP.
GIVEN INLET DESIGN INFORMATION:
GIVEN CURB OPENING LENGTH (ft)=
HEIGHT OF CURB OPENING (in)=
INCLINED THROAT ANGLE (degree)=
LATERAL WIDTH OF DEPRESSION (ft)=
SUMP DEPTH (ft)=
Note: The sump depth is additional
INLET INTERCEPTION CAPACITY:
3.30
6.00
0.00
2.00
0.17
depth to flow depth.
IDEAL INTERCEPTION CAPACITY (cfs)= 7.87
BY FAA HEC-12 METHOD: DESIGN FLOW (cfs)= 1.70
FLOW INTERCEPTED (cfs)= 1.70
CARRY-OVER FLOW (cfs)= 0.00
BY DENVER UDFCD METHOD: DESIGN FLOW (cfs)= 1.70
FLOW INTERCEPTED (cfs)= 1.70
CARRY-OVER FLOW (cfs)= 0.00
*** SUMMARY FOR THE COMBINATION INLET:
THE TOTAL DESIGN PEAK FLOW RATE (cfs)= 6.90 = QtefD
BY FAA HEC-12 METHOD:
FLOW INTERCEPTED BY GRATE INLET
(cfs)=
5.20
FLOW INTERCEPTED BY CURB OPENING(cfs)=
1.70
TOTAL FLOW INTERCEPTED
(cfs)=
6.90
CARRYOVER FLOW
(cfs)=
.00
BY DENVER UDFCD METHOD:
FLOW INTERCEPTED BY GRATE INLET
(cfs)=
5.20
FLOW INTERCEPTED BY CURB OPENING
(cfs)=
1.70
TOTAL FLOW INTERCEPTED
(cfs)=
6.90
CARRYOVER FLOW
(cfs)=�
r
. ----------------------------------------------------------------------------
UDINLET: INLET HYDARULICS AND SIZING
DEVELOPED BY
CIVIL ENG DEPT. U OF COLORADO AT DENVER
SUPPORTED BY METRO DENVER CITIES/COUNTIES AND UD&FCD
----------------------------------------------------------------------------
ER:JR ENGINEERS-DENVER CO ...................... ........... :..................
ON DATE 01-17-2003 AT TIME 10:04:38
** PROJECT TITLE: ROLLAND MOORE
*** COMBINATION INLET: GRATE INLET AND CURB OPENING:
*** GRATE INLET HYDRAULICS AND SIZING:
INLET ID NUMBER: 2
INLET HYDRAULICS: IN A SUMP.
rGIVEN
INLET DESIGN INFORMATION:
0
INLET GRATE WIDTH (ft)=
1.87
INLET GRATE LENGTH (ft)=
3.25
INLET GRATE TYPE
=Tyne 16 Grate Inlet
NUMBER OF GRATES
=
1.00
SUMP DEPTH ON GRATE (ft)=
0.17
GRATE OPENING AREA RATIO (%)
=
0.60
IS THE INLET GRATE NEXT TO A CURB
?-- YES
Note: Sump is the additional depth
to
flow depth.
STREET GEOMETRIES:
STREET LONGITUDINAL SLOPE (%) =
0.80
STREET CROSS SLOPE (%) =
2.00
STREET MANNING N =
0.016
GUTTER DEPRESSION (inch)=
2.00
GUTTER WIDTH (ft) =
2.00
STREET FLOW HYDRAULICS:
WATER SPREAD ON STREET (ft) =
14.13
GUTTER FLOW DEPTH (ft) =
0.45
FLOW VELOCITY ON STREET (fps)=
2.98
FLOW CROSS SECTION AREA (sq ft)=
2.16
GRATE CLOGGING FACTOR (%)=
50.00
CURB OPENNING CLOGGING FACTOR(%)=
20.00
INLET INTERCEPTION CAPACITY:
FOR 1 GRATE INLETS:
DESIGN DISCHARGE (cfs)=
6.40
IDEAL GRATE INLET CAPACITY (cfs)=
10.22
IP
BY FAA HEC-12 METHOD:
FLOW INTERCEPTED (cfs)=
5.11
BY DENVER UDFCD METHOD:
LFLOW
INTERCEPTED (cfs)=
5.11
*** CURB OPENING INLET HYDRAULICS AND SIZING:
INLET ID NUMBER: 2
r
INLET HYDRAULICS: IN A SUMP.
GIVEN INLET DESIGN INFORMATION:
GIVEN CURB OPENING LENGTH (ft)=
3.30
HEIGHT OF CURB OPENING (in)=
6.00
INCLINED THROAT ANGLE (degree)=
0.00
LATERAL WIDTH OF DEPRESSION (ft)=
2.00
SUMP DEPTH (ft)=
0.17
Note: The sump depth is additional
depth to
flow depth.
INLET INTERCEPTION CAPACITY:
IDEAL INTERCEPTION CAPACITY (cfs)=
7.73
BY FAA HEC-12 METHOD: DESIGN FLOW
(cfs)=
1.29
FLOW INTERCEPTED (cfs)=
1.29
CARRY-OVER FLOW (cfs)=
0.00
BY DENVER UDFCD METHOD: DESIGN FLOW
(cfs)=
1.29
FLOW INTERCEPTED (cfs)=
1.29
CARRY-OVER FLOW (cfs)=
0.00
*** SUMMARY FOR THE COMBINATION INLET:
THE TOTAL DESIGN PEAK FLOW RATE
(cfs)=
6.40= coo
BY FAA HEC-12 METHOD:
FLOW INTERCEPTED BY GRATE INLET
(cfs)=
5.11
FLOW INTERCEPTED BY CURB OPENING(cfs)=
1.29
TOTAL FLOW INTERCEPTED
(cfs)=
6.40
CARRYOVER FLOW
(cfs)=
.00
BY DENVER UDFCD METHOD:
FLOW INTERCEPTED BY GRATE INLET
(cfs)=
5.11
FLOW INTERCEPTED BY CURB OPENING
(cfs)=
1.29
TOTAL FLOW INTERCEPTED
(cfs)=
6.40
CARRYOVER FLOW
(cfs)=
r
■
L
DRAINAGE ASSUMPTIONS/NOTES
LOCATION: Rolland Moore Drive
PROJECT NO: 9023.30
COMPUTATIONS BY: A. Reed (modified OS-1 by D. Mattson)
DATE: 912012002
1. Due to negotiations with CSU assume land from the south (Basin OS-1) will be
fully developed and therefore, pipes under Roland Moore must be capable of
carrying fully developed flows.
2. Basin flows and inlet sizing was done assuming that the road was completely
constructed (i.e. Final Conditions).
3. Assume no flow from Centre Ave is coming on site.
4996 \ \ \
s
4996 / \\ \\ \\\
tr99 SW \ \ I \\ \\
TN
102 \ \\ \\
e 0.72 .76 \ \4) \N, \\\ 'I 50 25 0 50 100
\ \ \ \\ I HORIZONTAL
SCALE: 1" = 50'
'Sfi6p m+ I I 6 \ \ \ \\ 1 VERTICAL
SCA
a9 eA9 \ \ \\\ \ LE: 1" = 5'
O.7° .20499
f \
�005 I \866a oft '
I,11 s imill I
t I It h4
IZI
ncvuwrv�. �rir. 'ULblUNLU UT DRAWN BY: 'AYPRUVLU CY: .I 'SHEET
CITY OF FORT COLLINS, COLORADO JDL JDL mDRAINAGE PLAN 2
SCALE: DATE CHECKED 6Y: DATE: ROLLAND MOORE DRIVE °` 2
' ENGINEERING DIVISION ay .r e.n c.lr..
Windtrail Townhomes Addendum
ADDENDUM TO THE
FINAL DRAINAGE REPORT
FOR THE
WINDTRAEL P.U.D., TOWNHOMES SITE
PREPARED FOR:
City of Fort Collins
Stormwater Utility
235 Mathews
Fort Collins, CO 80524
.PREPARED BY:
Lidstone 8 Anderson, Inc.
736 Whalers Way, F-200
Fort Collins, CO 80525
(LA Project To. COTST18.8)
March 1, 1995
Mr. Glen Schlueter Page Three
March 1. 1995
SWALE ON'ERSIZING
Background
The swale shown on Sheet 2 of the Windtrail Townhomes drainage report [LA, 1994], and
repeated on Sheet 2 of the Windtrail on Spring Creek drainage report [LA, 1994], was designed
to convey the 100-year developed condition runoff from both the townhomes and single-family
sites as well as the 100-year historical runoff from all other areas tributary to the swale. It was
previously assumed that detention would be provided in conjunction with future development in
the area to reduce 100-year developed condition flows to 100-year historical levels. CSURF has
requested that the downstream reach of the Swale, from the southeast to northeast corner of the
Windtrail single-family homes site, be oversized to minimize potential detention requirements.
Hvdrolog-
CSURF's engineer. Mr. Patrick Mulhem of Mulhern MRE, Inc., has provided design discharges
which he believes will. allowdeveloped condition runoff from CSURF's property to be released
undetained to this reach of the swale. A coPe of Mr. Mulhem's letter dated December 1. 1994
is included in Appendix C of this report. It is noted that inclusion of Mr. Mulhern's letter in
this report does not imply concurrence .with his discharges or conclusions. Attempting to
estimate the required channel design discharge in order to allow undetained runoff associated
with developed conditions from a site which has not vet been designed is difficult at best.
However. CSURF (through Mr. Mulhem) has indicated that the discharges cited in his letter
would be acceptable for designing the swale.
To summarize the information in Mr. IvMulhern's letter. the 100-year discharge from the Spring
Creek Trail to the east end of Gilgalad Way would be 216 cfs. The 100-year discharge from
Gilgalad Wav to the southeast corner of the sin.cle-family site would be 188 cfs. In order to
meet City of Fort Collins' freeboard requirements. the Swale was designed to convey an
additional one-third of these values or 288 and 250 cfs. respectively.
Hvdraulic Analysis and Design
The swale grading plan was modified for the reach from DP #8 to DP #5 in order to maximize.
the channel cross section. The lot layout near the east end of Gilgalad Way, as well as Gilgalad
Way itself, were modified in order to accommodate the swale. In addition, the grading plan
now includes construction of a berm along the west side of the Spring Creek Trail in order to
form the east ban} of the Swale along this reach. Atypical cross section of this reach is given
Mr. Glen Schlueter Page Four
March 1. 1995
in schematic form in Figure 1: a summary of swale design parameters are provided in the table
on Sheet 1.
Based on the Mulhern discharge at DP #8, an HY-8 analysis was conducted for the previously -
designed double box culvert; the results of this analysis are included in Appendix D. It was
determined that the previous culvert design will accommodate the increased discharge without
modifying the culvert.
Results of the HY-8 analysis were used to define the starting water surface elevation for .the,
HEC-2.analvsis of the swale. The revised discharge profile (for oversizing) given in Table 1,
which includes Mulhern's discharges in the lower reach and the discharges cited in the previous
section for the upper reaches, was incorporated into the HEC-2 model for the proposed swale.
Complete HEC-2 output for the modeling of this condition are included in Appendix E; the
results are summarized in Table 3. The minimum channel depth for Sections El -El and E2-E2
specified in the table on Sheet 1 is the maximum flow depth within the specified reach associated
with 1.33 times the 100-year discharge for the reach.
If you have any. comments of questions concerning this study or the information provided herein.
please do not hesitate to contact us.
Sincerely.
LIDSTON ANDERSON, INC.
Gregoch. P.E.
Senior Engineer
GJK/tlt
Attachments
PATRICK F. MUL HE RN, RE A/t ■
PRESIDE N- / L
303160-5857 FAX 7WEW
i INVERNESS DRIVE EAS-
E NGLE WOOD. COLORAD(
61711;
December 1, 1994
VIA TELECOPIER - 1-303-223-9115.
AND REGULAR MAIL,
Mr. Steve Human
TST, Inc.
748 Whalers Way
Fort Collins, Colorado M22
Re: CSURF/McCoy Land Swap
Dear Steve:
RECEIVED
DEC p2 A _
-TS7,1NC,.
In follow-up to our recent conversation, I have attached my calculations of drainage
design flows with allowances for the discharge of fully developed flows from the McCoy swap
parcel and portions of CSURF Site J. All my calculations relate to the Overall Drainage Plan
map for Windtrail on Spring Creek PUD and the Final Drainage Report for Windtrai] PUD,
Towmhome Site, both prepared by Lidstone and Anderson.
These calculations provide our best estimates of future fully developed flow conditions
and the required channel width to discharge that flow across the easement at McCoy single family
home sites. We understand that plan approval for the single family home sites will be based
upon the estimated discharges contained herein which may vary with actual development. If the
actual development creates discharges in excess of these numbers, we understand that detention
will be necessary on -site to limit discharges to these peaks.
I hope this information is sufficient to meet your needs. We would appreciate the
opportunity to review the final design for the drainage channel across the single family home
sites.
In addition to this issue, there are a few others that need to be addressed. First, as we
discussed, we need to review the location of the proposed sanitary sewer easement across a
portion of CSURF Site J. We would prefer that this easement be located on the edge of the
drainageway so that the future roadway location is not constrained by this easement. I
understood you. to say that the City. would not allow this alternative, but with. your permission
we would like to pursue this option with the City. Secondly, CSURF has agreed to allow for
additional detention area on Site J to accommodate spill -over drainage from the CSURF swap
Mr. Steve Human
December 1, 1994
Page 2
parcel. We need to sa a document that shows the limits and a plan of the proposed detention,
and documentation which identifies this area as a wetland per City criteria.
' Finally, we have previously discussed that drainage swales will be constructed on the
McCoy swap parcel as part of the requirements for the development of the single family home
sites. We would like to provide specific input as to the location of these swales across the swap
parcel. If you would provide us with a copy of your. design sheet in this area, we will be happy
to locate the alignment that we desire.
?hank you for your assistance in all of these matters. We look forward to hearing from
you at your earliest convenience.
Sincerely,
MULHERN MRE, INC.
Patrick F. Mulhern, P.E.
President
PFM/lhl
Attachment
cc: Ms. Kathleen Byington (Nia telecopier and regular mail)
Mr. John McCoy (via regular mail)
CSURF/McCOY SWAP
DRAINAGE REVIEW
November 30, 1994
ASSUM ONS
1. Drainage basin boundaries are the same as contained in the Overall Drainage Plan Map
for the Windt -ail on Spring Creek .PUD as prepared by Lidstone and Anderson, Inc.,
dated 9/6194.
2. 13 acres on the west side of Basin A is to be detained. This west basin has been renamed
A2. The C value for Basin A2 is 0.20. The remaining portion of Basin A is. renamed
Basin A L
3. Basins A1, F, and G will be developed in the future with no detention. No plan currently
exists. The C value for these basins is assumed at 0.60.
4. Design point evaluated are DP(5) and DP(8) Aocated upstream of contributions from
Basin J.
Since Basin A2 is detained, it seems that the critical time of concentration would be for
Basin B, plus channel flow to the design point.
DP(5): tc (Basin B) = 17.9 minutes
(per Lidstone-Anderson)
tc (channel to DP(5)) = 9.2
minutes (1,050 feet at 1.9 fps per
Lidstone Anderson Design)
tc (total to DP5) = 27 minutes
i (27.2 minutes) = 4.4 in/hi
C Factor:
Basin Area
C
A] 9.5
0.60
A2 11.0
0.20
B 12.3
0.60
C 4.5
0.60
D 2.0
0.71
E 5.6
0.56
F 8.2
0.60.
G ]
0.60
Total 65.6
Total Weighted
0.52
Q100 = 1.25 (0.52) (65.6) (4.4)
= 187.6
Qt0o + Freeboard = 1.3 x 187.6 = 243.9 cfs
Estimate Channel Width from Section E-E in Lidstone Anderson
Report
Normal Depth = 1.98 ft
Ave Velocity = 2.19 fps
Flow Per Foot of Width = 4.33 cfs .
Additional Flow = 243.9 - 185..9
= 58.0
Additional Width = 58.0/4.33 = 13.4'
DPS: tc = tc (DP(5)) + tc (channel)
tc (channel) = 2.65 minutes
(350 feet at 2.2 fps)
tc = 27.1 + 2.65 = 29.7 minutes
i (29.7 minutes) = 4.2 in./hi
C Factor:
Basin Area
C
A-6 65.6
0.52
H 3.6
0.30
1 _ 4 7
0.50
TOTAL 73.9
TOTAL WEIGBTED
0.5]
Q100 = 1.25 (.51) (773.9) (4.2) = 197.9
Q t oo + Freeboard = 197.9 x 1.3 = 257.3 cfs
Estimate Channel, Width from Section E-E (same as above)
Additional Flow = 257.3 - 185.9
= 71.4
Additional Width = 71.4 • 4.33 = 16.5 feet
-2-
Basin J then enters channel upstream of the bike trail culvert:
tc = 29.7 minutes
i (29.7 minutes) _. 4.2 in/hr
C Factor:
Basin Area C
A -I 73.9 0.51
J �,$ 0.50
TOTAL 80.7
TOTAL WEIGHTED 0.51
Q100 = 1.25 (0.51) (80.7) (4.2)
= 216.1 cfs
.3-
PXrR K F. MUIMEPN. P.E.
PRESDENr
90E/61G-0BS FAY 7V- 6M
AFG 5, 1995
Mr. Bash Hamden
City of Fort Collins
Storhi water Utility
P_0. Box 580
Fort Conics. Colorado 80522
Re: Windtrail Park P.U.D.
Dear Mr. H2imde is
2 INVERNESS DRIVE
ENGVWODQ CMIM
I have reviewed the plan for draivage channeLc acrou the undeveloped parcels
dov,Tetre. m of the Windu2il Park project on behalf of the Colorado State University Research
Foundation ("CSURFj. I am satisfied that .the channel locations sboam on the "Revised Grading
End Drainage Plan, Addendum to the Dutfal<. Swale for the Wtndtrail P.U.D." with revision date
of 3/. S19' a< prepared by Lidstone and Anderson lnc. accommodate future developmem in this
arty Therefore.: we are in agreement with construction of the chEnnels in these locations.
If you hrvc any queWont regarding thif letm, please do not hesitate to contact me.
Sincerely,
MUUMN MRFi, INC.
Patrick F. uihern, P E.
President
TS
cr Ms. Kathleen Byingtaml, CSURF
f
Rip Rap Calculations
r
n"
240 EAST MOUNTAIN AVE;
FORT COLLINS, CO 80524
TEL 970 484 6073 .
FAX 970 484 8518
PROJECT NO. I7FDB2 ZO
DATE:
2-272 o//iris f • J ,P-
-
:
I------
L771It
t
6 I 4 _It t_
. 1 r-.��S r3},�-. 1 ��n �` ~.r�-- ,;� 1'b n=vi r r -� . r �!O�m- I / •iJ fr! =>�- :�.>� 1- - . :
1 1 1
I
i
-- _
_ _
1. 1
i
GC.9s. Ea
I I �
_ 1
P.,
Id
DESIGN, PLANNING AND ENVIRONMENTS WORLDWIDE
F
_ f
I � i
I
I � T
1 1 �
I 1
/ 1
Al
i I
2.4 AC
(2) 18"x6' CONCRETE 00 '
BOX CULVERT
-'- HILL POND 1
------------
A II
/ II
— WATER QUALITY >
' GRASSED SWALE II
NI —CITY 100 YEAR ,I
\ FLOODPLAIN V
/ BOUNDARY
CITY F FOOT —/ A2 \ !.
rEMA 100 YEAR FLOODPLAIN
AND 1 FOOT FLOODWAY LINE
Al
7.31 AC
1 \I`
P KING- LOT
11 1 B i BUILDING
\1\.43 AC _ I RESTROOM BUILbMG
• "ND
y
A3C (3y 24" RCP
POROUS LANDSCAPE
\� T WATER QUALITY POND A3b
\� \ Ak ` )V/ GRATED INLET
11.52 AC
j:,T
�r
-7 /
_7 7—
A3b O /1/
28 AC
,ram ��°\\— -•..
1 \�
I
1
I I
8" CEMENT
LINED DIP
I. I WETLANDS BASIN Al
4" CEMENT LINED DIP
POROUS LANDSCAPE
1 WATER QUALITY POND Alb
1 �1
lI I %l
A/../
I �sPOROUS LANDSCAPE
WATER QUALITY POND Ala
10'X3"BOX \
CULVERT IN,REFER SHS
—
1` SI THROUGH S5 ` \
1 Mild,.
�ql/
DRAINAGE SUMMARY TABLE
DESIGN COEFFICIENT COEFFICIENT (AC) lch) )ch)
POINT BASINS ..C.. "Cr AREA 02 Q100
Al
Al
0....40
2.....6
11.....15
A2
0.28
25
393
10
43
A3a
03
125
08
36
A3b
A3b
035
1111.....25
25
28
07
3
A3
A3
030
25
171..31
52
56
576
A3
A3bA3c
,
7 2
SC2
T4
0
125
2
.7
75
cugh A4
NOTE 2
0,25
1.25
1.43
1.0
45
NOTES:
1. The A3c CONDITION IS TAKEN FOR ACE "HYDRAULIC ANALYSIS OF THE HORTTCUL"
CENTER OUTFALL CHANNEL, SEPT 2002"
2. SEE HYDRAULIC EVALUATION OF THE COMMUNITY HORTICULTURAL CENTER, FOF
COLLINS, CO. DECEMBER 2000, BY ANDERSON CONSULTING FOR THE ANALYSIS
OF THE ENTIRE PROJECT.
FEMA 100 YEAR FLOODPLAIN
AND 1 FOOT FLOODWAY LINE
— — — CITY 100 YEAR FLOODPLAIN
BOUNDARY
------ CITY HALF FOOT FLOODWAY
BOUNDARY
----- DRAINAGE BASIN BOUNDARY
LINE
SNDNUOp WCH C04PW
�► D7=ft
240 EAST MOUNTAIN AVENUE
FORT COLLINS, COLORADO
ON24
TEL 970 484 $073
FAX 970 484 BIBS
City of Fort Collins
Center for
Advanced
Technologies
22nd
Filing
Community
Horticultural
Center"
PDP, #53-85AV
SEAL -
DATE JANUARY 10, 2003
JOB NO.- 71GS2.20
DRAWN BY. CR, DS, DT
CHECKED BY. GAH
DRAWING TITLE,
STORM
DRAINAGE PLAN
SHEET NO..
4 OF 22
0 MAW INC. ALL RIGHTS RESERVED