HomeMy WebLinkAboutDrainage Reports - 04/16/2018FINAL DRAINAGE REPORT
Boardwalk Office Building
City of Fort Col 'ns Approved Plans
Approved by: liZ
Date:
Prepared for:
r4 Architects
226 Remington Street, Unit #3
Fort Collins, CO 80528
(970)224-0630
Prepared by:
Interwest Consulting Group
1218 West Ash, Suite A
Windsor, Colorado 80550
(970)674-3300
February 23, 2018
Job Number 1326-069-00
INTERWEST M CONSULTING G R O U P
February 23, 2018
Ms. Heather McDowell
City of Fort Collins Stormwater
700 Wood Street
Fort Collins, CO 8052 2-0580
' RE: Final Drainage Report for Boardwalk Office Building
Dear Heather,
1 am pleased to submit for your review and approval, this Final Drainage Report for the
' Boardwalk Office Building development. I certify that this report for the drainage design was
prepared in accordance with the criteria in the City of Fort Collins Storm Drainage Manual. City
review comments dated February 13, 2018 have been addressed in this report.
I appreciate your time and consideration in reviewing this submittal. Please call if you have any
questions.
' Sincerely, Reviewed By:
' Erika Schneider, P.E. Michael Oberlander, P.E., LEED AP
Colorado Professional Colorado Professional
Engineer No. 41777 Engineer No. 34288
'AO �41K-W
288�0�
�Ilts/0►uni EN�\�
1218 WEST ASH, SUITE C WINDSOR, COLORADO 80550
Lei. 970.67e.3300 • FAX. 970.674.3303
TABLE OF CONTENTS
TABLEOF CONTENTS............................................................................................................ iii
1. GENERAL LOCATION AND DESCRIPTION................................................................ 1
1.1
Location...........................................................................................................................1
1.2
Description of Property................................................................................................. 1
1.3
Floodplain Submittal Requirements............................................................................. 1
2. DRAINAGE BASINS AND SUB-BASINS.......................................................................... 2
2.1
Major Basin Description................................................................................................ 2
2.2
Sub -basin Description.................................................................................................... 2
3. DRAINAGE DESIGN CRITERIA...................................................................................... 2
3.1
Regulations......................................................................................................................2
3.2
Directly Connected Impervious Area (DCIA) Discussion .......................................... 2
3.3
Development Criteria Reference and Constraints...................................................... 4
3.4
Hydrological Criteria..................................................................................................... 5
3.5
Hydraulic Criteria.......................................................................................................... 5
3.6
Floodplain Regulations Compliance............................................................................. 5
3.7
Modifications of Criteria............................................................................................... 5
4. DRAINAGE FACILITY DESIGN....................................................................................... 5
' 4.1 General Concept............................................................................................................. 5
4.2 Specific Details................................................................................................................ 6
' 5. CONCLUSIONS....................................................................................................................7
5.1 Compliance with Standards.......................................................................................... 7
5.2 Drainage Concept........................................................................................................... 7
' 6. REFERENCES...................................................................................................................... 8
' APPENDIX
VICINITY MAP AND DRAINAGE PLAN.............................................................................. A
HYDROLOGIC COMPUTATIONS..........................................................................................B
' HYDRAULIC COMPUTATIONS.............................................................................................. C
WATER QUALITY AND LID INFORMATION.................................................................... D
SOILS INFO, FEMA INFO, AND REFERENCE MATERIAL..............................................E
' 1. GENERAL LOCATION AND DESCRIPTION
' 1.1 Location
' The Boardwalk Office Building development is located in Fort Collins. It is located in
the Northwest Quarter of Section 36, Township 7 North, Range 69 West of the Sixth
Principal Meridian, in the City of Fort Collins, Larimer County, Colorado. Please refer to
Ithe vicinity map in Appendix A.
The project site is located at the northeast corner of JFK Parkway and Boardwalk Drive.
JFK Parkway bounds the property on the west, Boardwalk Drive on the south, Tract 9,
Block 1 of Landings Office Park PUD on the east and Landings Bay FDP on the north.
The development consists of Tracts 8 and 10, Block 2 of Landings Office Park PUD.
' 1.2 Description of Property
The property consists of 0.55 acres of land. The project will include construction of a
new building, sidewalks and new parking with drive aisles. The proposed development
is very similar to the original approved 1995 design of the property.
The site generally slopes in a southerly direction at approximately 5% to 7%. The land is
' currently vacant. There is no offsite flow contributing to the site. Soils on site consist of
Tassel sandy loam, 3 to 25 percent slopes classified as Type D hydrologic soil group.
According to FEMA Panel 08069CO987G (effective 05/02/2012) there are no mapped
' FEMA Floodways on this property.
Please refer to Appendix E for hydrologic soil and FEMA information.
1.3 Floodplain Submittal Requirements
Because the project is not within any FEMA or City of Fort Collins mapped floodway, a
' Floodplain Submittal is not required and a "City of Fort Collins Floodplain Review
Checklist for 50% Submittals" has not been included with this report.
2. DRAINAGE BASINS AND SUB -BASINS
2.1 Major Basin Description
The proposed development lies within the Mail Creek Master Drainage Plan. Outfall for
this site is the Larimer County Canal No. 2.
The site was previously studied in the "Final Drainage Report for Landings Office Park
P.U.D." by Northern Engineering Services, Inc., dated October 27, 1995 (Landings PUD)
and is a portion of sub -basins D3, D5 and D7. Please refer to Appendix E for reference
material.
2.2 Sub -basin Description
Today, the entire site sheet flows onto JFK Parkway and Boardwalk Drive where the curb
and gutter conveys the flow to either the East Detention Pond of ShopKo or Detention
Pond D1 of the Landings PUD located at the northwest corner of Boardwalk Drive and
Landings Drive.
3. DRAINAGE DESIGN CRITERIA
3.1 Regulations
' This report was prepared to meet or exceed the "City of Fort Collins Storm Drainage
Design Criteria Manual' specifications. Where applicable, the criteria established in the
' "Urban Storm Drainage Criteria Manual' (UDFCD), developed by the Denver Regional
Council of Governments, has been used.
' 3.2 Directly Connected Impervious Area (DCIA) Discussion
' Urban Drainage and Flood Control District (UDFCD) recommends a Four Step Process
for receiving water protection that focuses on reducing runoff volumes, treating the water
quality capture volume (WQCV), stabilizing drainageways and implementing long-term
source controls. The Four Step Process applies to the management of smaller, frequently
occurring events.
4
1 Step 1: Employ Runoff Reduction Practices
To reduce runoff peaks, volumes, and pollutant loads from urbanizing areas, implement
Low Impact Development (LID) strategies, including Minimizing Directly Connected
Impervious Areas (MDCIA).
Runoff for the eastern portion of the site will be routed through vegetated areas through
sheet flow thereby reducing runoff from impervious surfaces over permeable areas to
slow runoff and increase the time of concentration and promote infiltration. Runoff from
the parking lot and the eastern portion of the building shall drain directly into a pervious
paver system thereby slowing runoff and also promoting infiltration. Runoff from the
western portion of the building roof shall drain directly to a storm system that will release
to a swale that will slow runoff and increase the time of concentration and promote
infiltration.
Step 2: Implement BMPs that Provide a Water Quality Capture Volume with Slow
Release
Once runoff has been minimized, the remaining runoff shall be treated through the
pervious paver system that allows for settlement of sediments.
Step 3: Stabilize Drainageways
Natural Drainageways are subject to bed and bank erosion due to increases in frequency,
duration, rate and volume of runoff during and following development. Because the site
will drain to an existing detention pond, bank stabilization is unnecessary with this
project.
Step 4: Implement Site Specific and Other Source Control BMPs
The proposed development will provide the pervious paver system feature which will
' eliminate pollution that had previously been exposed during weathering and runoff
processes. The proposed project will proactively control pollutants at their source by
' preventing pollution rather than removing contaminants once they have entered the
stormwater system as compared to historic conditions.
1 3
' 3.3 Development Criteria Reference and Constraints
' The runoff from this site has been routed to conform to the requirements of the City
Stormwater Department. Because water quality capture volume from this site is not
' included in the development's detention pond, water quality facilities are required for the
new construction proposed on the site. The site's water quality will be met through the
use of a pervious paver system that includes 12" of storage in the voids below the pavers.
Please note that a portion of the site (Basin D) drains directly to JFK and Boardwalk as
' shown on the previously approved Landings PUD. This design matches the previously
approved condition.
' The site has been designed to maximize water quality treatment but the handicap ramp
area to Boardwalk and the west and south side of the site cannot drain to the pervious
' paver system. The entire site's required water quality capture volume is 0.01 ac-ft and
will be contained in the 12" of storage in the voids below the pavers. Please refer to
Appendix D for supporting information regarding water quality.
If the pervious paver system is completely saturated or overwhelmed, water will overtop
into the Single Curb inlet then be conveyed east to the existing Detention Pond D1 of the
Landings PUD.
Runoff reduction practices (LID techniques) are also required. No less than fifty percent
of any newly added impervious area must be treated using one or a combination of LID
techniques. New impervious area is 16,449 sf. Basins A and B contain the porous paver
' system. Using this LID technique, 15,560 sf of new impervious area (95%) will be
treated which exceeds the 50% requirement.
No less than twenty five percent of any newly added pavement areas must be treated
using a permeable pavement technology. The project adds 10,434 sf of new pavement
' area. This project will incorporate 3,790sf of porous pavers which is 36% of the newly
added pavement which exceeds the required 25%.
' The pervious paver system is oversized and provides full water quality volume for the
site.
Please refer to Appendix D for LID calculations and information.
' 4
4.
3.4 Hydrologic Criteria
Runoff computations were prepared for the 2-year and 10-year minor and 100-year major
storm frequency utilizing the rational method.
All hydrologic calculations associated with the basins are included in Appendix B of this
report. Standard Form 8 (SF-8) provides time of concentration calculations for all sub -
basins. Standard Form 9 (SF-9) provides a summary of the design flows for all Sub -
basins and Design Points associated with this site.
A variance to use the pervious paver system for the water quality capture volume is
included in Appendix D.
3.5 Hydraulic Criteria
All hydraulic calculations will be presented in the final drainage report and prepared in
accordance with the City of Fort Collins Drainage Criteria.
3.6 Floodplain Regulations Compliance
The project is not within any FEMA or City of Fort Collins mapped floodway; therefore,
Floodplain Regulations Compliance is not required.
3.7 Modifications of Criteria
There are no Modifications of Criteria for this development.
DRAINAGE FACILITY DESIGN
4.1 General Concept
The majority of the proposed development will be collected and conveyed to the
proposed storm drain system where it will be treated for water quality via a pervious
paver system before being released into the proposed system that conveys water east to
the existing Pond D1 of the Landings PUD.
61
4.2 Specific Details
A summary of the drainage patterns within each basin is provided in the following
paragraphs. Please refer to Appendix A for the drainage plan.
Basin A is 0.09 acres and contains the north drive aisle and parking. This basin is
calculated to have a 10-year discharge of 0.4 cfs and a 100-year discharge of 0.9 cfs.
Flows from Basin A are captured by the porous paver system and will discharge to the 8-
inch storm pipe around the north and east sides of the site. This system releases the
treated water into the Single Curb inlet and 12-inch storm pipe located at design point B.
Basin B is 0.26 acres, contains about 60 percent the roof (east portion) and the east drive
aisle and parking. This basin is calculated to have a 10-year discharge of 1.0 cfs and a
100-year discharge of 2.5 cfs. Flows from Basin B are captured by the pervious paver
system. The treated water is released into the Single Curb inlet and 12-inch storm pipe
located at design point B.
Basin C is 0.04 acres and contains the remainder of the roof (about 40%). The basin is
calculated to have a 10-year discharge of 0.2 cfs and a 100-year discharge of 0.4 cfs.
Flows from this basin will be conveyed to the 6-inch perimeter drain that wraps around
the west and south of the building. This drain will release flow to the sidewalk chase
located on the southeast side of the building. This chase will direct the flow to Basin B's
pervious paver system for treatment.
The treated water is released into the same Single Curb inlet located at design point B and
is then released to an outfall swale that conveys flow to the existing pond.
100 percent of the roof is treated in the pervious paver system.
Basin D is 0.13 acres and is calculated to have a 10-year discharge of 0.2 cfs and a 100-
year discharge of 0.4 cfs. This basin consists of the west and south landscape area
adjacent to the building. Flows from this basin will continue current conditions and sheet
flow onto JFK Parkway and will remain untreated as was planned in the Landings PUD
approved drainage plan.
' Basin E is 0.03 acres and is calculated to have a 10-year discharge of 0.1 cfs and a 100-
' year discharge of 0.2 cfs. This basin consists of the handicap ramp adjacent to the north
side of the building. Flows from this basin will drain to a sump inlet and the 8-inch storm
pipe around the north and east sides of the site. This system releases the untreated water
into the Single Curb inlet and 12-inch storm pipe located at design point B.
The percent impervious weighted average of the entire site is 58% which is below the
70% imperviousness that was assumed in the approved Landings PUD; therefore,
' detention is not required. Basins A, B, C and E correlate to 100% of sub -basin D7 and
about 67% of sub -basin D5 of the approved Landings PUD. The minor storm runoff of
basins A, B, C and E is 0.9 cfs which is less than the assumed minor storm runoff of 1.1
cfs from the Landings PUD. The major storm runoff of basins A, B, C and E is 4.0 cfs
which is less than the assumed major storm runoff of 4.2 cfs from the Landings PUD.
Please refer to Appendix E for excerpts from this drainage report.
5. CONCLUSIONS
' 5.1 Compliance with Standards
All computations that have been completed within this report are in compliance with the
City of Fort Collins Storm Drainage Design Criteria Manual.
5.2 Drainage Concept
The proposed drainage concepts presented in this report and on the construction plans
' adequately provides for stormwater quantity and quality treatment of proposed
impervious areas. Conveyance elements have been designed to pass required flows and
' to minimize future maintenance.
If, at the time of construction, groundwater is encountered, a Colorado Department of
Health Construction Dewatering Permit will be required.
1 7
6. REFERENCES
1. City of Fort Collins, "Fort Collins Stormwater Criteria Manual Amendments to
the Urban Drainage and Flood Control District Criteria Manual", adopted
December 2011.
2. Urban Drainage and Flood Control District, "Urban Storm Drainage Criteria
Manual", Volumes 1 and 2, dated June 2001, and Volume 3 dated November
2010.
3. Northern Engineering Services, Inc., "Final Drainage Report for Landings Office
Park P.U.D.", dated October 27, 1995.
8
L�l
I
1
1
1
1
1
1
APPENDIX A
VICINITY MAP AND DRAINAGE PLAN
A
w
a
w
0
w
J
J
O
U
OM
LE
DO
BOARDWALK OFFICE BUILDING
VICINITY MAP
SCALE: 1 "=500'
,r
I1
/
I
/
I
1
1
1
I
I
I
I
1
I
1
I
I1
/11
1
APPRDp( LIMITS OF &AWWT� !I
24' WAOPLAST OUT �`�
W/ STANDARD 0RATE�
I ,
1 '
I '
I '
I /
I '
I ' /
I ' i
1 '
I I f
I
• Ilk LAND/NGSBAYFOP
TRACT 13, BLOCK 2
(UIXIM LRAwACE
'i"AAO ALYXSS EA"ENT)
I A,
ii _�;
�LI
`�rApl, OFF '�-
ImaN T ODEi_
ss
I I B
Buxom TRAM
AMT
1>.Tr 1
I
aw D.
Il—iJl 0.2e an
I
'
1
I
,
PROPOSED
D
BUILDING
0.13 a
FF=5055.35
I
I 1
PERMORUS
PAVE
SYSTEM
SIN
l �
D
STEPS
7'C
PRELIMINARY
NOT FOR CONSTRUCTION
PERIMETER: GRAN
ROOF DRAINAGE TO THIS PPE
I /
it LAND/NGSOFF/CE
PARKPUD
774.4CT9, BLOCK 1
(ACaSC UTWTY
AWD DWAAVACE EASEW71(r)
I
II
I_-
r� ` 5- PERFORATED PALER l
uwERDRAN To MET
I
SINGLE
CURB MET
I I
I
\ & I J
L I
\ I I
\ tY fris R \ S -- 1 I
STG3' SCOUR STOP � �
,1 I
\ \ 1 I
` \\
\
DRAINAGE SUMMARY TABLE
M.N.
IbYA
TdMla,,
WRWp
Area
bdnW
Gil"
Cltaq
klloj
k(I"I
.%
gaNN
,IN
Godow
m
g1aEKm
IBIAIagI
A
A
GAa
081
1a0
50
So
02
Oa
09
PERVIOUS PAVER SYSTEM
B
&
021
an
age
50
50
a6
1D
25
PERVIOUS PAVER SYSTEM
C
C
OW
an
1.00
50
&0
a1
02
0.4
TOV ROOF DRAM SYSTEMTOPERVIODS PAVER SYSTEM
D
D
010
ate
oat
So
so
01
02
04
FLOWS TO NK AND BOARDWALK - PART OF LANDINGS DI
E
E
am
O50
an
5.7
50
00
01
02
TO 2V ADS AREA INLET
E
ME
O.tt
OTa
ON
50
5.0
Da
04
It
TO r PERIMETER MAIN
e
B,C
Oast
an
OW
50
5D
DT
I1
2R
T01&-PPEANDTOPOIO
20 10
0 20 40
SCALE. 1"= 20'
NOTES
I. ANYp GEDCURB.GUTTERMOSIDEWALKE%ISTINGMR MCONSTRUCTION,AS LAS
STREETS. SIOEWAI-NS. CURBS AND GUTTERS. DESTROYED. DA1 AGED OR REMOJEO DUE TO
CONSTRUCTION OF TNIS PROJECT. SHALL BE REPLACED OR RESTORED TO CITY OF FORT COtI INEI
STANDMOS AT THE DEVELOPER'S EXPENSE PRIOR TO THE ACCEPTANCE OF COMPLETED
IMPROVEMENTS MD/OR PRIOR TO ME ISSUANCE OF THE FIRST CE RDFICATE OF OCCUPANCY.
LEGEND
EXISTING MI NOR CONTOUR
,,,, G MAJORCONTOUR
�w.awT PROPOSED MINOR CONTWR
PROPOSED MANOR CON TOLIt
PROPOSED DIRECTION OF WFIIAND FLOW
N PROPOSED DRAUNAGE
BASIN DMDE LNI7
A PROPOSEp DRAINAGE BASIN
MINOR STORM RUNOFF COEFFICIENT
DRAINAGE BARN MFA ACRES
QDESIGN RNM
UD Table
SO%Or Slte Trevirriert bV LID Re rem rit
Newlm IvinuSAma
16449
if
Required %4ni u IMPINNIOUS Area to be Treated
8.225
sf
Treabnent 41- PMiwS Pavers lBlRn Ai
Treatlrlent el- kriperious Area Treated lRninA
SL9
3,%B
at
of
resttoentll- Run-on REM 3:1&ts.
3.0
Ttmttarnf0 Predmir Powen Rrinfl
Treavitentl2-I MOus Area Treated Basing & C
11,632
f
Tfeatorent R2- RIn-dn Ratio 3:1 Mail
3.2
TOW ARA-reated
15,ie0
if
Aaual %of Impervious Area On Site Treated by UD
g5
25%Porous Pavement Requiremem
New Pavement Area
m434
f
Required Animum Area of Ptrviwo Pavement
Area 0f PLMOvs Pavers Prodded
2,Epg
3 TBO
if
f
Actual %al Perv�Oas Pavemt It P,Uviaed
36
a8H _0
r�e
3
m
y If)N in
O
F DIAO
O ON
ZU
It x 0 Ui d
IL V �Zm
W Z —
d ¢ 12: 0
to X
N LL 0-
N
O
13
J
m
W
lL
{L
0
J
3
0
m
5
(L
W
Z
9
13
CALL UTKITY NO7FICA71ON
CENTER OF COLORADO
811
w
7
I�
a
ruI 2-BUSINESS DAIS N ADVANCE
z
Z
Y
GRATE. ID EXCAVATE
BEFORE YOU DICMARKING
FOR THE 4ARKING OF UNDERGRpap
n
I�
I
C
D
W
m
MEUBER UMIRES
ra
G
W
W
a
J
w
J
=
to
o
U
U
CITY OF FORT COLLINS, COLORADO
UTILITY PLAN APPROVAL
APPROVED:
�yom.REOYS.!
g�0WE'
On ENGINEER
DALE
[Y�ATy' 90
CHECKED BY:
WATER A WASTEWATER VR 1Y
DATE
P
CHECKED BY:
..........~
STMURATER UTILITY'
DATE
YDNAL
CHECKED BY:
PARKS A RECREATION
DATE
PROJ. NO. 1326O69e0(
CHECKED BY:
111 O ENGINEER
DAIS
C
V
CHECKED BY:
[NNRDNIIENTAI 0..WIER
DATE
APPENDIX B
HYDROLOGIC COMPUTATIONS
12
W
J
r
M�M
i
�
Q
'
m
M
CO)
W
'
Q
Z
a
'
wo
>z
WZ
wz
>
J
aLL
Z)
F-
O¢
Y
Era
w
a
a�
O¢
F
wF-F-<
z
jjim�ma-
wwwozo0
¢¢?Z-¢�-
ww¢¢ww0
»QY¢F-
Z
¢
¢
O
LL
¢
w
¢
¢
aWWOOo
00¢oiCO
wwQQQQ
Er
�
-
a
a
F-
LL
Fwa-Q
F-
Fa
0
p m
O Y
m
O
ci N
a
O
v
O
N
m
N
O
O
N
O
u
O
o
c
o
0
0
0
N
N U
Q
N
O
t0
O
7
O
7
O
O
O
m
O
n
O
0
o c
Y
o
0
0
0
0
0
0
O
E
O
vi
O
ui
O
ui
O
N
m
ui
O
ui
O
ui
c
U
o
m
o
N
m
m
n
O
m
n
n
m
N
N
n
n
U
o
o
c
o
0
0
0
y0 Y
Q m
O
C
N
G
O
G
G
O
G
G
Ci
G
Z �
� b
¢
m
U
O
w
Q
m
F y
C
mp
¢
m
U
0
w
w
m
o n
11
d
N
a
[�
)
)
§§})00
o
�f
;-
};;
,�
E§,;,r§■!§
]§|
§§
!§°°`!!°!!
|§|
§°
°§!°��!°!!
|!
)§|
§\§!!§|§|§
||
0)
!§
\;
Q
}
0
C
m
N
wo
0
r
N
N
w
N
O
N
Z
Z
❑
0
w
z
Z
W
O
O
0r
r
O
¢
¢
N
>
a
a
Y
Q
¢
w
.
0
�3
3
F
w
a
z
a�
y
r
z
w
w�
m W�
a
>
N
N N❑
Z_
0 00
<
¢ r
< ¢
w
w a
>
><ZOM
> m
Y
Q
Ci<LLO
w
a
a LL
l
N
N O
O o
r
Q a
0 0
r r
>>
00m0
O
Q
w%
LL'
00
a
m
w
¢LL
w p
rurrr
0 0
0 0
00
LL IJi
J
0000cloo
N
N N
N N
VI N
� o
n 0
11
E -
+
Ti
m
❑
W Q
W Y N
N
=
N
O +
3
J
LL
SS
0
0 0
O CO?
0 0
N n
0 coo
O m
W
'Y'N
0
O
N O
Cl N
N 0
N N
N N
V M
0 m
N N
b b
b b
b b
O
O Cm O
O
O O
O O
O O
O O
m
O
YiN
VI O
NNNhN
O O
O b
0
NN
N
w
P
O^
^
m
O O^
0
w
c Pn'
Q
J
r
N
Y 10
N 0
0 Y
- 0
o �N
b
of
O O
�ri NHNI'i
O O
b O
vi
O b
N�'i
O
C F e
J
J `
Z.
ai
0
b u�n
N
m
J V
Q
p N
C
00000000
W
r g
4X
A N
m
w
W
m
¢
m U❑
W
OWL)
Q
O+
m
N
a
C
y_z
Q
m Q
0
0 Z
w a
Q
m U❑
W
W m
m m
j Q
❑
Iwo
Z
_O
F
Q
N
N H
Z
W
w Z
00
a U
m LL
a0
~ cW
L
P
�o
0
N
z
z
mo
0
O
¢
¢
a
O
a
a
¢
m Z
Z
m
Z i
w
W Q
a�
W O
a¢
>>¢Y¢�-ZYO
Q
a O
LL a
W a
LL
N
m O
O o
Q a
0 0
H F
00¢
00 O
a
W 6
wwo°o00
3H,m
LL
4 f
LL f
oo33
F f
LL LL
2 �
O
O O
O O
O O
N O
E
4
N
O
N
N O
N O
OO
m
W=
J
6t
♦O N
N N
m WON
m
11
O
N
^ O
N
N O
N
F J
g O
N
u +
3
J
LL`'
J
a E
N
h O
O O
N h
O G�
W
N
V
N N
N N
N N
[V N
N N
d [')
N N
N N
U
O1
N
10 f0
ID f0
10 f0
1D /O
m
C L
x
m c
O
o
O O
0 o
O O
c o
O O
0 0
O O
0 0
w
O
VI
N O
lV fV
O O
fV fV
O N
N fV
O
fV CJ
FWOW
--
-a3-2
a
J
f �
E '=
� h
N
N
o 0
N N
0 o
N N
N o
Cl N
o N
N l7
fi
t 0
J
8�8N�W0^l;�
O
U
.=o--000000
Q
U
6
7
O
J
a W
U m
m
000000000
^n `
p
H
O
N O
O
(00
d
m N
O
O O
O O
O O
10
Zw
Q
m
a
m U
O W
W U
Iwo
+
Z
Z
N Z0
0 t
a
m U
O W
W m
m m
I R
N G
E
U
LL
LL
O E
Z O
7
� N
Y y
W N
a
0 c
O =
F=- UY
W
2 O
J LL
Z O
O
Q U
2
W �
o
f �
�
Z
z
� Z
Z
cr 0
0
Q
QQ
WO
0
0¢
cc
a
cc IL
w Y
Y
0.
OQ
~ >J
>a>
3:
go
og
FW-FN0I-ZOO
a~i
(n co`"o
z o
Oocn
¢¢?z-r
¢
zi
w w¢¢
W w
o¢¢
>>
W Y
H
Z Y
O
w
0
U
U U
0
0
a 0
0
7 7
F
F
x
00¢cnaCL
C/)w
ob
i�
L
o
o
0 0
0 0
0
a
i
r
N u
O -
o 0
0 0
0 0
0 0
0
O
r
N_
O �
0
m
E PIE
m
= o a
U
Q u
o 0
0 0
0 o
a o
0
i
m m
m m
n m
m uNi
m
c o
0 0
m o
o-
d
U
m n
m N
vdi n
n n
�
U
o 0
0 0
0 o
a o
0
Q A
o O
V
C O
O O
O O
O
LL
0
O
C
w
Q m
U O
w♦
a
S
a
U
w
0
c
o
o a
Q m
U O
W W
m m
m
a
0
0
0
a
c
N
C
O
U
N
2m
C
m
C
LL
LL
Z 0
D O
2 to
Q !
W
IL
in N
0
F
O
W C.)
M r
Q LL
Z O
O
Q U
w ❑
❑
F m
(n
V) Z
z
cr ❑
LLI
CL
UO
0
OCc
¢
a
¢i
way
03
3
�ujLU❑
❑uj
LLJU)
w01-�00�
yy>m�¢am>
Cl)
mm`o❑z❑0❑(n
ccQ3z—¢Fz2
wwaaWw❑«
>>
Q Y¢
F
z Y
0
as❑MQwa'N
U
m000cc
F❑
S
00
F
F
7
00¢34a
7
>
>
6
..
o3�
—
m
w
w
0�000��
¢
d
LL
F LL
F F
F LL
LL
J
`g
O^ x
d
O
N C41,
F
O
O
O V
d
O
>
c
E w c
¢
o 0
U
U
O
0
0 0
0 0
0
-
n
6
n
6
n n
6 6
o n
6 e
n o
d d
n
a
V L
E
O
N
O
m
O O
N O
O
O
U
H
9, n
{i n�
O
U
c
c
c o
c c
d
d
a
6NB6"d
6066660,60
LL
o
E C
W
G
9.9
¢
m
U O
W Q
F
w
H N
Q
0
c
a
n
O
a
D
0
C7
c
c
N
0
O
U
N
d
N
LL
0E
Z 0
Y >
W 0
a
C
0 .__
cW U
L
J LL
Q
Z O
0 T
F r
Q U
w
0
0
U)
U)
U
C7
Z
C7
Z
LL
C
O
w
Z
Z
Q
J
Q
LL
LL
LL
UO
0
OC
C
a
a
w
Y
J
Y
J
O
Q
Q
ww�a
Zz¢w
y}>m�DEaO.mi
COW
oz000(n
Ir(L
Z
Z
-
�F
Z
2
u1
w
Q
Q
w
w
0
Q
C
LL
Z
O
0
0
0
LL
Q2Q-,cn
w
LL
a_
0-
c)u)00U)
N
»OF'QwLLrr
x
O_Ooccn_
a_
cn.
Q
7
_
�
<O
�
It-
m
a:
w
ccw
w
0�
0
0
0��
¢
LL
LL
F
LL
F-
H
H
LL
LL
0
0
0 "-
O
m
N
v
v
N
m
in
o
H
¢
N
0
¢
o 0
U
0
Q
_ t
�
m
ai
m
ai
m
of
m
ai
m
ai
m
of
m
ai
o
ai
m
m
V
- E
O
vi
O
vi
O
vi
O
vi
O
vi
O
vi
O
vi
IA
�ri
O
vi
'.
U
O
b
o
O
N
o
M
0
C'I
01010101
n
n
t0
Q
O
O
O
O
O
O
O
O
O
LL
LL
z
W
z
=
m '�
¢
n'I
U
❑
ul
¢7
a
¢+
m
O
m
F
U
❑
+
0
m _o
O a
Q
m
U❑
W
w
¢1
m
m
p � Q)
a 0
L
N
3 L L
p �
O LO
pCZ
L p U
m 0 V
N -0 C
C (�
U
II
0
APPENDIX C
HYDRAULIC CALCULATIONS
C
Interwest Consulting Group
1218 W. Ash, Suite C
Windsor, CO 80550
Inlet Flow Calculation for Single Curb Inlet
Project: Boardwalk Office Building
Job Number: 1326-069-00
Calculations by: es
Date : 2/6/2018
Objective: to find the number of grates required for area inlets in grassy areas
WSEL
Geometry at inlet:
Grate Open Area and information:
Square Feet Open (A): 1.8056 sf 35% F, OA includes Grate and Curb Opening. If overflow does
Reduction Factor (F): 35% < occur with completely clogged condition, it will safely flow over
the curb and into the swale.
Grate Flow:
DP B
Use the orifice equation Q, = C*A*SQRT(2*g*H) to find the ideal inlet capacity.*
'See Hydraulic Design Handbook by McGraw-Hill for verificaiton of equation use and C value
C = Orifice discharge coefficient= 0.67
A = Orifice area (ft) - open area of grate
g = gravitational constant = 32.2 ft/s2
H = head on grate centroid, ponding depth (feet)
Then multiply by the reduction factor for the allowable capacity.
QG = Q * (1-F)
O = 4 cfs Q 100
H = 0.5 ft
A= 1.81 ft2
Q;= C*A`SQRT(2*g*H)
6.86 cfs
Qc= Q*F
= 4.46 cfs OK
Pagel
4 TON P-52 SL
ANCHORS FOR SETTING
PLAN VIEW
N. T. S.
FRAME & GRATING NOT SHOWN
GRATING (SEE DETAIL,
THIS DRAWING)
ER IS REQUIRED THE
IS POURED WITH A
-LAP" JOINT.
ISOMETRIC VIEW
N.T.S.
O M
SIZE, SHAPE AND
J VARIES
I
I
I
SECTION A —A
N.T.S.
4 TON P52 SL
ANCHORS
NOTES:
1. EAST JORDON IRON WORKS CURB INLET 7030 (OR EQUAL) TYPE M2
GRATE AND T1 BACK COMBINATION.
OPEN AREA: 260 SO. IN.
WEIGHT: 560 LBS
2. DESIGNED FOR AASHTO HS-20 LOADING
3. DESIGNED ACCORDING TO ASTM C857-87 AND ASTM C858-83
GRATING DETAIL
N. T. S.
LEGEND
VA
SECTION LINE A -A (ARROWS POINT IN
DIRECTION SECTION IS VIEWED)
.c of CITY OF FORT COLLINS UTILITIES
—' ` C""`ins S P.O. BOXTORMWAT 80, FORT COL INS, ER CONSTRUCTIN CO. 80T 2I2 S
(970) 221-6700
GRATING (SEE DETAIL,
THIS DRAWING)
M.A. STEPS 012" O.C.
(NUMBER REQ'D VARIES
WITH HEIGHT)
SECTION B—B
N. T. S.
LIFTING NOTES:
1) 4 TON P-52 SL ANCHORS (8 REO'D)
DESIGN NOTES:
1) DESIGN LOADINGS:
A. AASHTO HS-20-44, W/ IMPACT
B. SOIL WEIGHT = 120 PSF
C. EQUIVALENT FLUID PRESSURE = 45 PCF
D. 80 PSF LATERAL LIVE LOAD SURCHARGE
2) CONCRETE 28 DAY COMPRESSIVE STRENGTH SHALL BE
4500 PSI (MIN.)
3) STEEL REINFORCEMENT:
A. REBAR, ASTM A-615 GRADE 60, MIN. OF 2" CLR.
B. MESH, ASTM A-497 GRADE 80
4) CEMENT: ASTM C-150 SPECIFICATIONS
SINGLE CURB INLET
DRAWN BY: T. COX
DATE DRAWN: 3/3/05
CAD FILE NAME: D43.d
DETAIL
D-43
Inlet Flow Calculation for Area Inlet (24" ADS Inlet)
Project: Boardwalk Office Building
Job Number: 1326-069-00
Calculations by : es
Date : 12/12/2017
Objective: to find the number of grates required for area inlets in grassy areas
WSEL
Geometry at inlet
Grate Open Area and information:
Square Feet Open (A): 1.145 sf
Reduction Factor (F): 50%
Grate Flow:
' DP E
Interwest Consulting Group
1218 W. Ash, Suite C
Windsor, CO 80550
Use the orifice equation Oi = C'A'SQRT(2'g'H) to find the ideal inlet capacity.'
'See Hydraulic Design Handbook by McGraw-Hill for verificaiton of equation use and C value
C = Orifice discharge coefficient= 0.67
A = Orifice area (ft2) - open area of grate
g = gravitational constant = 32.2 ft/sz
H = head on grate centroid, ponding depth (feet)
Then multiply by the reduction factor for the allowable capacity.
QG = QI * (1-F)
Q = 0.2 cfs 0100
H = 0.1 ft
A= 1.15 ftz
Q; = C'A'SQRT(2'g'H)
1.95 cfs
QG = Qi ' F
0.97 cfs OK
Pagel
W
J
Z
m
U
W
J
F-
W
J
H
E
E
7
N
d
1
C
O
II
la
1.
3
n
n
V
n
n
�p
n
V
II
II
II
II
II
II
I I
F
n
W
n
n
a
�J
II
p ••
a
II
J� O
II
d iV 'O
a-H.di w
Ni
x u Q
H m ro W
(7Z
H
3 m
u
(d ro El)u
d C 3
z �C
o
d
d d U a
b N W
n
w w rn
'
II
01 O1
n I
A C
o
7 3 O V]
II o
N W U
z
o
w w w
II 1-I
H H H
U
11 GA
A A
d
A A A
a
'
II y
A A A U
i 1
O O
d
O O
4J
V A w i
o 0
a b i
cc
d ro
00
V d V
L ii W 1
0 0
a
Ell
1
>,
00
u
d C I
o 0
j -Q
a u w
faEwv
U w I
w 1
00
0
o 0
I -I 3
ro M O m l
O o
u ro + w I
O W U 1
E I
[Q 1
1
0 0
d
00
1
U U O W 1
O S1 U I
F d W
4
C I
H 1
i
d W
r-I R?•I
1Ci F
CO w
00
00
H H
41
H H
ro ro
W W
A A
U U
.i ..{
H f-I
v v
C C
0 0
4J a
d v
c �
H H
U u
.H -H
>4 L4
d d
C C
Cd7 Cd7
1
r w r o 1
u ro I
N m o m 1
d ?+ I
m m o 0 1
;3 T3 4J V
roromwl
I
}4 j4 9 " I
>p o
x ca
I
�
N frotl 14 i
wwfonM
4J�
ro�4
>
I
I
I
� i
I
m If1 N N i
ro U\
N M M M
I
i4 O 11
U I
N N N r r
d r W
-H 4J I
s>' m m r 0
>v
0ro0--
eommo�
ro ro 11 I
w w w N N
--- —
-- -- i
La S+ d w I
ro C9 C
E
0 0 0 o
-.a I
rl d 3^ I
H H H
ro 4J. O N I
I
4.1 N rl W I
d' H H H I
----------
O ?I a U 1
E W I
1
U
I
I
-H i~. 1
C m 0 m 0
,C 1
00 0 0 1
f6 f0 d 11 I
v v fn N N
4l .-. I
r m m H I
P it C w I
a
I
— — --
--- --
1
C 1
O N N M 0
o 1
O m mH N
I
ro ro ro ro �
b
O d I
'-I
In N In N In
v rt I
U U U U I
O> w I
U .Li I
it F4 it it 1
}4 d I
vm
UI 1
pH
N I
U U U U I
W 1
oo000
d 3 I
o o ,-I H .-I
d
U U U 1
N I
ro i4JO M
4J
L N
.'I I
H ('. C
N ri W I
C d' rl H HU
•ri
•.iI
-.i -H
H
0 a U I
(v E/IN
E- )
fq
H m m m I
-- -- i
I
i
i
E
N I
ri H 'i ri i
i
W
C
7 H N
4,
v o
A W
O aJ 4
H H
z v I
I
d I
N
I/CJy
mH
I
I
ro I
U H [E1]
----
----
a
Ew00z
W aWEf)H
d
I
a
jj I
H N M C 1
1�
z c e c
Z
ftl I
I I I I I
I
H N N
I.j I
---- ,
a a a a 1
I
I
----------
N
Q m H H N
d
d
c
c
W
0
a`
/
\\
k\
�
IV
—
\jƒ
m
-
e
r
§§ $ %
\2
_
/
7{{�CD
=
j
---
\_
._�\72\$\
0.
LO cl
k
�E¥
)
)
f
}§�=G
25t///
$
—2/��.
,
j72%/\
/
/
§
3
CLo
.
f2
�
df
O
0;
_
7
•!
k!
/\/\\§
ƒ
�\
j//§\\
�
{q$
\
/
.
_
\CN
CN
/§E
/ _$
�\
§
`
o
3$\$\LO
aEm
§}
/
$
£«3 u/wo
m
k
\\E
'
uEm
@
L
{
\k/
LO
kE:
k
uE$
;
j0
k\\
k)
�k!
®
6fR
rxo
Worksheet for V SW Chase
Project Description
Flow Element:
Rectangular Channel
Friction Method:
Manning Formula
Solve For:
Discharge
Input Data
Roughness Coefficient:
0.013
Channel Slope:
0.02000
ft/ft
Normal Depth:
0.50
ft
Bottom Width:
1.00
ft
Results
Discharge:
F 3.21
Capacity of one
ft3/S
Flow Area:
0.50 chase
ft'
Wetted Perimeter:
2.00
ft
Top Width:
1.00
ft
Critical Depth:
0.68
ft
Critical Slope:
0.00882
ft/ft
Velocity:
6.41
ft/s
Velocity Head:
0.64
ft
Specific Energy:
1.14
ft
Froude Number:
1.60
Flow Type:
Supercritical
GVF Input Data
Downstream Depth:
0.00
ft
Length:
0.00
ft
Number Of Steps:
0
GVF Output Data
Upstream Depth:
0.00
ft
Profile Description:
N/A
Profile Headloss:
0.00
ft
Downstream Velocity:
0.00
ft/s
Upstream Velocity:
0.00
ft/s
Normal Depth:
0.50
ft
Critical Depth:
0.68
ft
Channel Slope:
0.02000
ft/ft
Critical Slope:
0.00882
ft/ft
Cross Section for V SW Chase
Project Description
Flow Element:
Rectangular Channel
Friction Method:
Manning Formula
Solve For:
Discharge
Section Data
Roughness Coefficient:
0.013
Channel Slope:
0.02000
ft/ft
Normal Depth:
0.50
ft
Bottom Width:
1.00
ft
Discharge:
3.21
ft3/s
0.50 R
—1.00 n
V. 2 L
H: 1
I
0ww1011/:1611
WATER QUALITY
AND
LID INFORMATION
1
0
' Design Procedure Form: Extended Detention Basin (EDB) - Sedimentation Facility
Project Name: Boardwalk Office Building
'
Project Number: 1326-069-00
Company: INTERW EST CONSULTING GROUP
Designer: ES
Date: 10/17/2017
1. Basin Storage Volume
'
A) Tributary Area's Imperviousness Ratio (i=la/100)
B) Contributing Watershed Area (Area)
C) Water Quality Capture Volume (WOCV)
(WOCV=1.0-(0.91'i3-1.19'i2+0.78i))
'
D) Design Volume: Vol = WOCV/12' Area' 1.2
la = 58 %
i = 0.58
A = 0.55 acres
WQCV = 0.229636 watershed inches
Vol. = 0.013 ac-ft
LID Table
50% On -Site Treatment by LID Requirement
New Impervious Area
16,449
sf
Required Minimum Impervious Area to be Treated
8,225
sf
Treatment #1- Pervious Pavers (Basin A)
989
sf
Treatment #1- Impervious Area Treated (Basin A)
3,928
sf
Treatment #1- Run-on Ratio (3:1 Max)
3.0
Treatment #2 - Pervious Pavers (Basin B)
2,801
sf
Treatment #2 - Impervious Area Treated (Basin B & C)
11,632
sf
Treatment #2 - Run-on Ratio (3:1 Max)
3.2
Total Area Treated
15,560
sf
Actual % of Impervious Area On -Site Treated by LID
95 %
25% Porous Pavement Requirement
New Pavement Area
10,434
sf
Required Minimum Area of Pervious Pavement
2,609
sf
Area of Pervious Pavers Provided
3,790
sf
Actual % of Pervious Pavement Provided
36 %
APPENDIX E
EXCERPTS FROM REFERENCE REPORTS
E
r
Aft d"NOMPANE
3 Hydrologic Soil Group—Larimer County Area, Colorado 3
(Boardwalk Office Building)
40° 31'5FN
40- 3157 N
493710 493M AIMM 493740 49i7575D
3
H
Map Scale: 1:458 E printed on A pm0at (8.5' x 11') sheet
N Metes
0 5 10 20 30
Feet
0 27 40 80 120
Map pigemon: web Monitor Comer madmites: WCSB4 Edge tics: UfM Zore 13N WGS84
usDAA Natural Resources Web Soil Survey
211111111111 Conservation Service National Cooperative Soil Survey
0
40° 33'SB'N
40- 31' S4 N
49'. M 4MM
3
P
V
8/17/2017
Page 1 of 4
Hydrologic Soil Group—Laflmer County Area. Colorado
(Boardwalk Office Building)
MAP LEGEND
Ana of keanat (AOR
Area of Interest(AO1)
sods
Soil Rating Polygons
O
A
Q
AID
B
Q
BID
o
D
0
Cm
Q
D
Q
Not rated or not available
Sol] Rating
Lines
. e
A
N
AID
N
B
BID
M
C
N
CID
. i
D
. .
Not rated or not avadab]e
Soil Rating
Points
O
A
�
aD
�
B
BD
I,aA Natural Resources
-01111111 Conservation Service
C
® C/o
13 D
o Not rated or not available
Water Features
Streams and Canals
Transportation
iyy Rails
ti Interstate Highways
US Routes
Major Roads
Local Roads
Background
0 Aerial Photography
Web Soil Survey
National Cooperative Soil Survey
MAP INFORMATION
The soil surveys that compose your AOI were mapped at
1:24,0D0.
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 centfied data as
of the version date(s) listed below.
Soil Survey Area: Larimer County Area, Colorado
Survey Area Data: Version 11, Sep 23, 2016
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Cate(s) aerial images were photographed: Mar 20, 2015-0ct
15, 2016
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
shilling of map unit boundaries may be evident.
8/17/2017
Page 2 of 4
' Hydrologic Soil Group—Larimer County Area, Colorado
Boardwalk Office Building
Hydrologic Soil Group
Hydrologic Soil Group— Summary by Map Unit— Larimer County Area, Colorado (CO644)
Map unit symbol
Map unit name
Rating
Acres in AOI
Percent of AOI
106
Tassel sandy loam, 3 to
25 percent slopes
D
0.6
100.0%
Totals for Area of Interest
0.6
100.0%
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
Natural Resources
Conservation Service
Web Soil Survey
National Cooperative Soil Survey
8/17/2017
Page 3 of 4
Hydrologic Soil Group—Larimer County Area, Colorado
Boardwalk Office Building
Tie -break Rule: Higher
LISDn Natural Resources
q—
� Conservation Service
Web Soil Survey
National Cooperative Soil Survey
sn nzui i
Page 4 of 4
u
Final ApprolOd
! r�::.l1.1%�
Final Drainage Report
for
Landings Office Park P.U.D.
City of Fort Collins, Colorado
October 27, 1995
Prepared For:
Lagunitas Company
Prepared By:
Northern Engineering Services, Inc:
420 South Howes, Suite 202
Fort Collins, Colorado 80521
(970)221-4158
Fax (970)221-4159
Project Number. 9516.00
Fourth Final Submittal
,an'd BIN10.1 H04H
qIi a
, tri
DEVELOPED DRAINAGE
LANDINGS OFFICE PARK P.U.D., Fort Collins, CO.
File Number: DSNPNTD5.WQ1 15-Mac-95 Ca1cs Bv: MBW
DESIGN POINT D5: (Includes Basin 135)
TOTAL AREA = A (ac)= 0.45
RUNOFF COEFFICIENTS: (From Table 3-3)
Area of Roofs (ac)= 0.1720 C for Roofs = 0.95
Area of Concrete & Asphah(ac)= 0.1610 C for Concrete = 0.95
Area of Gravel Parking (ac)= 0.0000 C for Gravel = 0.50
Area of Lawn (ac)= 0.1170 C for Lawn = 0.25
COMPOSITE RUNOFF COEFFICIENT:
C = 0.95(0.172+0.161ac)+0.25(0.117) = 0.77
0.45
Cf = 1.00 (Frequency Adjustment Factor; Storm Return Period of 2 & I0 - Years)
Cf = 1.25 (Frequency Adjustment Factor. Storm Return Period of 100- Years)
OVERLAND FLOW: (Across Parking Lot)
Total Overland flow length = 131' TZ& T10 1.87 (1.1 - CCf) SQRT(L) = 2.0 min
L (ft)= 131 CUBRT(S)
S (%) = 54.0 - 48.84 = 3.94 T100 = 1.97 (1.1 - CCf) SORT(L) = 1.4 min
131 CUBRT(S)
C = 0.95
GUTTER FLOW:
L (ft)=
19
S (30) =
48 84 - 4&54 =
19
V(fps) =
2-50
SWALE FLOW: (From
L (fl)=
u17
S(°k)=
48.54-42.0=
]07
V(fps) =
3.70
2 & 10 -YEAR TIME OF CONCENTRATION: _
100-YEAR TIME OF CONCENTRATION; Tc100 =
RAINFALL INTENSITY:
FROM FIGURE 3-1:
i2(in/hr)=
QI0(cfs) = CCf x i2 x A=
20
Q2(cfs) = CCf x i2 x A =
1.1
Q100(cfs)= CCf xil00xA=
3.9
Tt = L = 0.1
1.58 60(V)
(From Figure 3-2)
TI = L = 0.5 min
6.11 60(V)
(From Figure 3-2)
2.6 min (Use 5-minutc minimum)
2.0 min (Use 5-minutc minimum)
3.29 i100(in/hr)= 9.0 i10(in/hr)= 5.7
l'
DEVELOPED DRAINAGE
LANDINGS OFFICE PARK P.U.D., Fort Collins, CO.
File Number: DSNPNTD7.WQ1
DESIGN POINT 137: (Includes Basin
TOTAL AREA = A (ac)= 0.185
Area of Roofs (ac)= 0.0000
Area of Concrete & Asphalt(ac) 0.1310
Area of Gravel Parlang (ac)= 0.0000
Area of Lawn (ac)= 0.0540
COMPOSITE RUNOFF COEFFICIENT:
RUNOFF COEFFICIENTS: (From Table
C for Roofs =
0.95
C for Concrete =
0.95
C for Gravel =
0.50
C for Lawn =
0.25
C = 0.95(0.131ac)+0.25(0.054) = 0.75
0.185
Cf = 1.00 (Frequency Adjustment Factor; Storm Return Period of 2- Years)
Cf = 1.25 (Frequency Adjustment Factor-, Storm Return Period of 100- Years)
OVERLAND FLOW:
Calcs Bv: MBW
Total Overland flow length = 13.5' 72 = 1.87 (1.1 - CC() SORT(L) = 4.6 min
L (ft)= 13.5 CUBRT(S)
S (%) = 54.57 - 54-3 = 2.00 TI00 = 1.87 (1.1 - CCf) SORT(L) = 4.3 min
13.5 CUBRT(S)
C = 0.25
OVERLAND FLOW:
Total Overland flow length = 104'
L (ft)=
104
S (%) =
54.3 - 49.3 =
104
C =
0.95
RAINFALL INTENSITY:
FROM FIGURE 3-1:
U(inft)= 3.00
02(cfs) = CCf x i2 z A nO4Q100(cfs)=CCfxi]OOzA
T2 = 1.97 (I.1 - CCf) SQRT(L) = 1.7 min
CUBRT(S)
4.81 T100 = 1.87 (L1 - CCf) SQRT(L) = 1.1 min
CUBRT(S)
i100(inRtr)- 9.00