HomeMy WebLinkAboutDrainage Reports - 04/07/2009n
1
1
I
1
11
1
0
I
I
1
11
t
1
1
S.A. MYERS, LLC
Paul Bennett, PE Cky of Ft. COMM PIO1.is
1318 Tarryton Drive ApprpvW
Fort Collins, CO 80525 Hate 4- %- D q
(970)-219-1357 (ph) — - S)).6l
V%OPERTY OF
!'ORS' COLUNS UTD-I US
FINAL DRAINAGE AND EROSION CONTROL REPORT FOR
OAKRIDGE CORPORATE CENTER
MINOR AMMENDMENT FOR PARKING LOT EXPANSION
LOT 1 OAKRIDGE BUSINESS PARK
SECOND FILING, P.U.D. and
A PORTION OF TRACT C OAKRIDGE
VILLAGE NINTH FILING
CITY OF FORT COLLINS, CO 80525
PREPARED FOR:
Bhavikatti Architecture LLC
18947 E Baker Place
Aurora CO 80013
DATE:
MARCH 3JWHt 2009
PREPARED BY:
PAUL BENNETf, PE
1
1
I
t
1
I
I
I
I
I hereby certify that this report for the preliminary drainage design of OAKRIDGE
BUSINESS PARK PARKING LOT EXPANSION was prepared by me (or under my direct
supervision) for the owners thereof and it meets or exceeds the criteria in the Larimer
County Stormwater Design Standards.
Paul James Bennett, PE
Registered Professional Engineer
State of Colorado No. 40178
2
i
I
1
I
I
r
i
11
11
TABLE OF CONTENTS
Property Location.............................................................................4
• Section, Township, Range
• Local Streets
• Major open channels
• Surrounding Developments
PropertyDescription.........................................................................4
• Area
• Ground Cover
• General project description
DrainageBasins and Sub-Basins........................................................4-5
• Major basin drainage characteristics
• Nearby irrigation facilities
• Floodplain considerations
• Historic drainage pattern on subject property
• Off site drainage patterns and their impact
• Individual on site basin descriptions & runoff calculations
DrainageDesign..................................................................................6
• Previous drainage studies
• Drainage impact on existing infrastructure
• Runoff method
• Design rainfall & recurrence intervals
• Detention storage (calculations, outlet, overflow)
• Water quality
Conclusions.........................................................................................7
References..........................................................................................7
Appendices..........................................................................................8
A- Major and minor storm runoff computations for historic and developed conditions
B- Detention pond sizing, outlet sizing, overflow weir sizing
C- Water quality calculations
D- Original Drainage Report
Exhibits...............................................................................................
FEMA FIRM Map
Developed Drainage map
3
t
I
I
7
r
Property Location
The subject parcel of land is located in the City of Fort Collins City Limits. There are two parcels
which are undergoing changes with this Minor Amendment. The two parcels are: "Lot 1 Oakridge
Business Park, Second Filing, P.U.D." and the second parcel is "A portion of Tract C Oakridge Village
P.U.D. Ninth Filing". The first parcel is 4.00 acres in size and the second parcel is 0.21 acres. The
parcels are located in the NW quarter of Section 6, Township 6N, Range 68 West, 6"' P.M., City of Fort
Collins, Colorado. Wheaton Drive (80' ROW paved road) abuts the property on the west. The adjacent
parcels to the south are developed single family home sites. The parcels to the north are developing with
single family home sites. To the east of this parcel are also developed single family home sites.
Property Description
Being that this parcel is currently developed the ground cover on this lot consists mostly of
asphalt paving with landscape islands. This parcel slopes from south to north at an average slope of
1.5%. This parcel and the neighboring parcels are served by a regional detention facility. There is more
discussion of this regional facility in the Detention portion of this report. The property owner wishes to
add more parking to better serve his tenants. This increase in parking results in about 9600sf of
additional impervious area on these two parcels. The NRCE soil type in this area is SCS type `C'. The
property is located in the Fossil Creek Basin.
Drainage Basins and Sub -Basins
The existing drainage pattern on this site is from south to north at a slope of around 1.5%.
There is an existing open channel on the north boundary of this site which sits in a drainage easement.
This open channel is known as the Lower McClellands Creek (herein after referred to as the Creek).
There are no irrigation facilities on this site. There are offsite drainage considerations for this site that
are discussed in more detail below. In general there are offsite flows from the south that will continue to
flow in the existing manner and they will continue to flow into the Creek where they are routed the
regional detention facility. Both offsite and onsite flows flow overland via curb and gutter and concrete
pans where they are directed into the Creek.
According to FEMA FIRM Map 08069C1000F this property is located in floodplain area'X', areas
determined to be outside the 0.2% annual chance floodplain. There are no floodplain areas that show up
on or near this property on the City of Fort Collins Floodplain Maps. Please see attached FIRMette map
at the end of this report.
Basin 1
This basin is 1.16 acres and consists of some offsite developed land to the south (Single Family)
which flows overland into the subject parcel and it includes half of the building roof and some parking
area. Existing Conditions runoff calculations for this basin are based upon the development as it is today.
The Developed Conditions runoff calculations for this basin are based upon the proposed parking
expansion.
The existing 2yr, 10yr, and 100 year flows are 1.25, 2.13 and 6.02cfs respectively. The developed 2yr,
10yr, and 100 year flows are 1.41, 2.41 and 6.42cfs respectively. This basin will continue to flow in its
existing manor even with the proposed site improvements. The newly developed flows due to the
proposed improvements will be detained and treated for water quality as described below. The additional
proposed impervious coverage in this basin is very minimal.
Please see Appendix A for runoff calculations.
G1
r
I
I
I
d
I
r
1
1
Ll
I
11
Basin 1A
This basin is 0.25 acres and is a sub -basin of Basin 1. This basin consists of the onsite area of
Basin 1 that will be developed. Existing Conditions runoff calculations for this basin are based upon the
development as it is today. The Developed Conditions runoff calculations for this basin are based upon
the proposed parking expansion. There is discussion in the detention pond portion of this report that
explains why this basin was derived.
The existing 2yr, 10yr, and 100 year flows are 0.24, 0.41 and 1.27cfs respectively. The developed 2yr,
10yr, and 100 year flows are 0.36, 0.61 and 1.49 cfs respectively. This basin will continue to flow in its
existing manor even with the proposed site improvements. The newly developed flows due to the
proposed improvements will be detained and treated for water quality as described below.
Please see Appendix A for runoff calculations.
Basin 2
This basin is 0.26 acres and consists of parking and landscape area. This basin will receive the
majority of the proposed impervious coverage. Existing Conditions runoff calculations for this basin are
based upon the development as it is today. The Developed Conditions runoff calculations for this basin
are based upon the proposed parking expansion.
The existing 2yr, 10yr, and 100 year flows are 0.21, 0.35 and 0.96cfs respectively. The developed 2yr,
10yr, and 100 year flows are 0.41,0.70 and 1.27cfs respectively. This basin will continue to flow in its
existing manor even with the proposed site improvements, although the slopes and travel times will be
less. The newly developed flows due to the proposed improvements will be detained and treated for
water quality as described below.
Please see Appendix A for runoff calculations.
Basin 3
This basin is 0.28 acres and consists entirely of rooftop area. This basin will not receive any new
development. This basin was originally calculated only to determine the rooftop flows for the purpose of
sizing an underground roof drain pipe size. After discussion with the City this roof drain system will not
be installed and these flows will flow overland across the parking lot.
The existing and developed 2yr, 10yr, and 100 year flows are 0.47, 0.81 and 1.43cfs respectively. The
flows from this basin will continue to flow in an existing manor and will continue to be detained and
treated at the regional facility.
Please see Appendix A for runoff calculations.
Drainage Design
There was a drainage study done for this property when it developed in 1984. This report is
attached in Appendix D, since this original report there has been a regional drainage study done for this
area which outlines and sizes a regional detention facility. It was determined that it would be more cost
effective and timely to not explore the capacity of this regional detention facility and just detain and treat
the increased flows due to this parking lot expansion on site. Thus there are two small detention and
water quality ponds proposed with this report to accommodate this increase in runoff.
The Rational Method was used to determine the existing and developed runoff from this parcel.
Runoff calculations are attached in Appendix A. Design rainfall and recurrence intervals were obtained
I
i
from the City of Fort Collins Storm Drainage Design Criteria and Construction Standards Manual.
Additionally the Urban Drainage and Flood Control District Volumes I and 2 were used for calculations.
Please see the developed IDF curves in Appendix A.
rThere are two proposed detention ponds for this site. Pond 1 will be in Basin 1 and Pond 2 will
be in Basin 2. The increase in 100-yr flows (developed minus existing) will be detained and released.
A variance is requested so that each pond will pass through and release un-detained the 100-yr
existing flows. The justification for this variance is the fact that these flows are being detained and
treated at a regional pond. Each Pond will detain the 100-yr increase in flows due to development.
For Basin 1 the release rate (100-yr Existing flows) is 6.02cfs.
For Basin 2 the release rate (100-yr Existing flows) is 0.96cfs.
No open channel calculation has been done on the adjacent creek but the flows should not be
increasing due to the proposed detention.
Detention pond calculations have been performed using the mass diagram method. It was found
that by sizing Pond 1 by using the data for the entire Basin 1 this pond was drastically and incorrectly
oversized due to the fact that the large area quantity was used in the calculation. Thus sub -basin lA was
delineated in order to more appropriately determine the pond size. The quantities from the sub -basin
were used solely for the purpose of sizing the pond and the quantities from Basin 1 were used to size the
release structure for the 100-yr existing flows. Furthermore, the detention quantities which were
generated by using the mass -diagram method were increased by 20% at the request of the City of Fort
Collins Stormwater Department.
' Pond 1 has a required volume of 241cf for the 100-yr storm and Pond 2 has a required volume of
479cf for the 100-yr storm. Please see the detention pond specifications and release structure drawings
in Appendix B.
' Water quality has been examined utilizing Volume 3 of the UDFCD manual. Efforts were made to
separate existing flows from developed flows in order to not overwhelm the water quality features since
the features are only sized for the increase in flows. This is the reason for the proposed underground
roof drain. Basin 1 will have a fair amount of additional flow but there was no obvious cost effective way
to separate these flows. Pond 1 has been specified with a Porous Landscape Detention Water Quality
Feature and will perform well in this application. This basin will have a Volume of 74cf. This Water
' Quality Feature will need an under drain as is shown on the attached drawings. Pond 2 has also been
specified with a Porous Landscape Detention Water Quality Feature and will perform well in this
application. This basin will have a Volume of 146cf. This Water Quality Feature will also need an under
drain as is shown on the attached drawings. Please see Appendix C for Water Quality computations and
' design drawings.
The proposed detention ponds will provide their required storage as well as their required water
' quality storage. The ponds will release flows in a historic manner into the adjacent open channels. The
flows will be released via a concrete weir. One foot of freeboard has not been provided for these ponds
and is not required for parking lot detention. However it has been verified and noted on the grading and
drainage plans that the 100-yr WSEL for the ponds is at least one foot below the finish floor elevation of
the building. The 100-yr WSEL is for Pond 1 is 4967.31 and for Pond 2 the 100-yr WSEL is 4967.53.
Please see the detention pond specifications and release structure drawings in Appendix B.
' Additional water quality and erosion control measures are shown on the attached Erosion Control
Plan. These measures consist of both temporary and permanent solutions. Silt fence, Vehicle Tracking
' 6
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
1
Control and Inlet Protection details are used for temporary solutions and Permanent Seeding and Porous
Landscape Detention are used for permanent solutions.
Conclusions
The proposed development of this site will not significantly alter the historic drainage pattern in
this area. The increase of flows due to development will be detained in the proposed detention ponds.
Water quality has been provided. All disturbed areas will need to be re -seeded with a native grass blend.
References
1. City of Fort Collins Storm Drainage Design Criteria and Construction Standards,
April 12, 1999.
2. Urban Drainage and Flood Control District Volumes 1,2,3, June 2001 with
August 2006 revisions.
7
APPENDIX A
1
■
I
.
\\\@q;
?■
[)«
cU
6
=
z22ess
\�
k)�)
/
a
)
E
(
(
)
)
\\!
!
2(\\
�
)
)
{E■mGa
`
«
(efmm>
]
\!§ara
>
®
>±oSe2
Sm
(
§
\<<<„
§
}
§
«
ƒ
\
){
6
y
y
{\
ƒ
\
\
\
\\
\
\
\
}
F
O
C
�
o
o
�a
O
�
�
Q
Q
Q ❑
>
Q
'
7.
<
a
F
�
1
z z z
vvv
5 5 5
E E E
0 0 0
N
V
N
t�V
N
O
V
M
M
M
N
N
N
N
z
Q
4
Z
U
o
c
o
0
3
a
U
uzo,000
o
o
�
o
Q
U
b
r
b
m
U
9199
Qz
Q
Q
lL
°
r
Q
Z
m
R
Z
C-
Q
N
M
0
a
1
7
0
F
G
Z
C
Ci
U
Z
F
h
41
Z
z
Z
a
'
X
F
O
z
Y
C
a
a
'
CL
F
Z
J
Gs7
F
C
O
a
O
O
M
N
W
L
O
m r\
o
—
ao
i
p
a
m
c
uai
�im�
C
>
C
<
�
Z
w
Q
i
'rn
1
G C F
N N N
0 0 o
Z Z Z
E E E
0 0 0
O
LL
M
Q
M
OO
a
U
N
0
0
0
N
b
CO
W
.b
C
nt
M
[ry
M
�z
rz
pQQ„aOi�
oar
Z
U
o
0
0
0
7
C
CL
�Kv%00
a
4.�Nry
N
Q
U
o
0
o
c
Q
Z
a
Q
F
a
c
z
a
m
Z
7-
z
-
Q
N
M
o�
1
z
o
'
u
U
Z
F
N
z
0
N
7
Q
'
X
C
U
7_
1
z
a
'
z
c�
F
Z
c.7
F
a
z
0
a
CC
O
W
N
3
cW7
m
O
G
a o
Y
co
z
Q
a
F
1
1
roa
nr
U
q
N
'L
U
o
L
a
o
c
S
W
F
�
oeiee
G
Q
O
U
0
0
0
0
Q
<-
�
4
I
F
Q
Z
In
Z
F-
�
N
Is
a
z�0000
0
z�W���
w
0}
o 0 0
Qz�
z
Q
a
F
N
�oSS
z
w
O
o 0 0
a
W
O
a
f
O
Y
�
c
w
3
1
C
� -
o
Q
¢rY0
it
Y
�
u
y�M
MAD
U
Z
s
m
y
LL
V
N�
N
a
a
M
b
T
E
�
�viar
V
,.,
Zallor
_j
W
n0000
1
00
v�10O
W
a.
O
^v�000
o
n
O
6
F_
F
Z
�
v
F
❑
z
oot-:o
��UFv+�n
z
W
nnnoo
ono
kki
N
N
N
O
O
O
U
h.an
n
o
cioo
O
Q
0
V
N
<
a
d
F
a
z
z
m
V
z
•-
Q_
N
M
n
a
0]
Q
W
N
Mze
o
m
h
D
O
C <
Q
+
a
L yi
W
G.
U
z
o
FI
Q
co
L
> F
-
F-
3
F
I
U
o
O
F
Q m
N
Cl
z
Q
a
[Fn
1
1
F [- FV-
N
N
N
N
N
N
z
uQ0000
a
ULsj
y�
U
Vl
r
Y1
e
a
N
r
0
0
0
0
Q
�
Q
Q
u
C
F
Q
c
z
v,
m
Q•-•
Q
N
rn
^
�
a
I
1]
1
I
LEI
J
C
?
N
La1 O
V m M
-
'O
C
Q m
z
Y
ma
Z
Q
�
i
1
1
1
1= F
a
o
d
U
N
0
c;
0
Co
(n
M
M
Nl
r
C
�Gj
fs.
O
U
O
O
O
O
z
F
LzU�
CL
U
p
O
p
O
O
0
F�
O6
0
0
N
N
N
c
o
o
d
<
z
Q
Q
Z
h
e
m
m
z
r-
ro
�'
Oa
1
1
z
1
0
z
0
1
U
C
w
a
O
w
w
1
a
z
0
7
a
1
w
F
i
z
Y
C
1
C
w
F
z
w
U
1
F
0
1
Q
U
o
3
�m
m
i
G
O
O
z
a
a
i
N
i
1
i
1
i
1
1
O
O
LL ?
Q
N
O
G �oroo
a
U
¢
W
O
G
N
O
N
O
0
z
z
U
�
�4
ono
'none
eo
f+l
F
%oo
o
c
A
o
r
room
U
o
0
0
0
V
a
�
a
F
A
I
1
I
1
11
1
City of Fort Collins OF data
Time
2- r
10- r
1 00-r
Min
inch/hr
inch/hr
inch/hr
5.00
2.85
4.87
9.95
6.00
2.67
4.56
9.31
7.00
2.52
4.31
8.80
8.00
2.40
4.10
8.38
9.00
2.30
3.93
8.03
10.00
2.21
3.78
7.72
11.00
2.13
3.63
7.42
12.00
2.05
3.50
7.16
13.00
1.98
3.39
6.92
14.00
1.92
3.29
6.71
15.00
1.87
3.19
6.52
16.00
1.81
3.08
6.30
17.00
1.75
2.99
6.10
18.00
1.70
2.90
5.92
19.00
1.65
2.821
5.75
20.00
1.61
2.741
5.60
21.00
1.56
2.671
5.46
22.00
1.53
2.611
5.32
23.00
1.49
2.551
5.20
24.00
1.46
2.491
5.09
25.00
1.43
2.441
4.98
26.00
1.40
2.391
4.87
27.00
1.37
2.341
4.78
28.00
1.34
2.29
4.69
29.00
1.32
2.25
4.60
30.00
1.30
2.21
4.52
31.00
1.27
2.16
4.42
32.00
1.24
2.12
4.33
33.00
1.22
2.08
4.24
34.00
1.19
2.04
4.16
35.00
1.17
2.00
4.08
36.00
1.15
1.96
4.01
37.00
1.13
1.93
3.93
38.00
1.11
1.89
3.87
39.00
1.09
1.861
3.80
40.00
1.07
1.83
3.74
41.00
1.05
1.80
3.68
42.00
1.04
1.77
3.62
43.00
1.02
1.74
3.56
44.00
1.01
1.72
3.51
45.00
0.99
1.69
3.46
46.00
0.981
1.67
3.41
47.00
0.961
1.64
3.36
48.00
0.95
1.62
3.31
49.00
0.94
1.60
3.27
50.00
0.92
1.58
3.23
51.00
0.91
1.56
3.18
52.00
0.90
1.541
3.14
I
11
I
��
I
53.00
0.89
1.52
3.10
54.00
0.88
1.50
3.07
55.00
0.87
1.48
3.03
56.00
0.86
1.47
2.99
57.00
0.85
1.45
2.96
58.00
0.84
1.43
2.92
59.00
0.831
1.42
2.89
-60.001
0.821
1.401
2.86
Ln
O
O
00
cV
Ln
00
L
N
N
lD
.
L
T
O
_T
_T
_T
M
T
O
O
O
O
O
1-4
Ln
^ l0
0000 cn
N
C1
lD Q1
Ln m
O
p
i1 p
O O
II
II
O
11
N
N
ry
O
N N
x
CC
Xcn
i
4
N
o
a
n
O
/I
I
vi
�'
l'
r
r
i
�
O
O
a--1
h'
P
O
O
Vl
O
-
O
I
O
O
O
O
O O
O
O
O
O
O
O
O
O
O
O O
O
O
O
O
O
O
O
Ol
00
I,: t0
t11
4
M
N
r4
O
i--I
1
1
1
1
1
1
1
i
1
1
1
DRAINAGE CRITERIA MANUAL (V. 1)
s0
30
t.- 20
1
RUNOFF
FAN
� . I . �i�/Illt�
1r
m
MENEM
��
NUNN
■
i
I
i
I
Imo'
FAWAWAUFAVM�MMENENNE
.2 .3 .6 1 2 3 5 10 20
VELOCITY IN FEET PER SECOND
Figure RO-1--Estimate of Average Overland Flow Velocity for Use With the Rational Formula
08/2006
Urban Drainage and Flood Control District
RO-13
DRAINAGE CRITERIA MANUAL (V. 1)
RUNOFF
Table 110-6- Runoff Coefficients, C
Percentage
Imperviousness
Type C and D NRCS Hydrobqic Soil Groups
2-
5
10-
25
50-yr
100
0%
0.04
0.15
0.25
0.37
0.44
0.50
5%
0.08
0.18
0.28
0.39
0.46
0.52
10%
0.11
0.21
0.30
0.41
0.47
0.53
15%
0.14
0.24
0.32
0.43
0.49
0.54
20%
0.17
0.26
0.34
0.44
0.50
0.55
25%
0.20
0.28
0.36
0.46
0.51
0.56
300,6
0.22
0.30
0.38 1
0.47
0.52
0.57
35%
0.25
0.33
0.40
0.48
0.53
0.57
4090
0.28
0.35
0.42
0.50
0.58
4546
0.31
0.37
0.44
0.51
0.59
50%
0.34
0.40
0.46
0.53
0.60
55%
0.37
0.43
0.48
0.55
M0.58
0.62
60%
0.41
0.46
0.51
0.57
0.63
65%
0.45
0.49
0.54
0.59
0.65
70%
0.49
0.53
0.57
0.62
0.68
759;
0.54
0.58
0.62
0.66
0.68
0.71
8090
0.60
0.63
0.66
0.70
0.72
0.74
85%
0.66
0.68
0.71
0.75
0.77
0.79
90%
0.73
0.75
0.77
0.80
0.82
0.83
950%
0.80
0.82
0.84
0.87
0.88
0.89
100%
0.89
0.90
0.92 1
0.94
0.95
0.96
TYPE B NRCS HYDROLowc Sons GROUP
0%
0.02
0.08
0.15
0.25
0.30
0.35
5%
0.04
0.10
0.19
0.28
0.33
0.38
10%
0.06
0.14
0.22
0.31
0.36
0.40
1590
0.08
0.17
0.25
0.33
0.38
0.42
20%
0.12
0.20
0.27
0.35
0.40
0.44
25%
0.15
0.22
0.30
0.37
0.41
0.46
30%
0.18
0.25
0.32
1 0.39
0.43
1 0.47
35%
0.20
0.27
0.34
0.41
0.44
0.48
40%
0.23
0.30
0.36
0.42
0.46
0.50
45%
0.26
0.32
0.38
0.44
0.48
0.51
5010
0.29
0.35
0.40
0.46
0.49
0.52
55%
0.33
0.38
0.43
0.48
0.51
0.54
60%
0.37
0.41
0.46
0.51
0.54
0.56
65%
0.41
0.450.94
.54
0.57
0.59
70%
0.45
0.49.58
0.60
0.62
75%
0.51
0.64.62
0.64
0.66
80%
0.57
0.59.66
0.68
0.70
85%
0.63
0.66.72
0.73
0.75
90%
0.71
0.73.78
0.80
0.81
95%
0.79
0.81.85
0.87
0.88
100%
0.89
0.90
0.95
0.96
08/2006
Urban Drainage and Flood Control District
RO-11
DRAINAGE CRITERIA MANUAL (V. 1)
RUNOFF
Table RO-3-41ecommended Percentage bnperAousness Values
Land Use or
Surface Characteristics
Percentage
Impevviousness
Business:
Commercial areas
95
Neighborhood areas
85
Residential:
Single-family
Muni -unit (detached)
60
Mufti -unit (attached)
75
Ha:ff-acre lot or larger
w
Apartments
80
Industrial:
Light areas
80
Heavy areas
90
Parks, cemeteries
5
Playgrounds
10
Schools
50
Railroad yard areas
15
Undeveloped Areas:
Historic flow analysis
2
Greenbelts, agricultural
2
Off -site flow analysis
(when land use not defined)
45
Streets:
Paved
100
Gravel (packed)
40
Drive and walks
90
Roofs
90
Lawns, sandy soil
0
Lawns, clayey soil
0
See Figures RO-3 through RO-5 for percentage imperviousness.
CA = KA + (L31i3-1.44i2 + 1.135i - 0.12) for CA-2: 0, otherwise CA = 0
CCo = KC"
+ (0.858i3 — 0.786i 2 + 0.774i + 0.04)
Cg = (C A + Ccn )12
082006
Urban Drainage and Flood Control District
(RO-6)
(Rai)
Ras
APPENDIX B
' Cumulative Runoff Method for Sizing Detention Ponds -POND 1
1
I
I
u
.1
i
.1
-_ 1
Design Storm
Release Rate
Area
Runoff Coefficient
Initial Time
Time Increment
100-
cfs I00-yr release
acres Legend
input variable
minutes calculation
minutes fixed input
1.27
0.25
0.78
5.00
1.00
Inflow Inflow Release Storage Storage
Time Intensity Rate Volume Volume Volume Volume
min i h cfs cf cf cf ac-ft
5.00
9.95
1.94
582
381
201
0.00
6.00
9.31
1.82
654
457
196
0.00
7.00
8.80
1.72
721
533
187
0.00
8.00
8.38
1.63
784
610
175
0.00
9.00
8.03
1.57
846
686
160
0.00
10.00
7.72
1.51
903
762
141
0.00
11.00
7.42
1.45
955
838
117
0.00
12.00
7.16
1.40
1005
914
91
0.00
13.00
6.92
1.35
1053
991
62
0.00
14.00
6.71
1.31
1099
1067
32
0.00
15.00
6.52
1.27
1144
1143
1
0.00
16.00
6.30
1.23
1179
1219
40
0.00
17.00
6.10
1.19
1213
1295
-82
0.00
18.00
5.92
1.15
1247
1372
-125
0.00
19.00
5.75
1.12
1278
1448
-170
0.00
20.00
5.60
1.09
1310
1524
-214
0.00
21.00
5.46
1.06
1342
1600
-259
-0.01
22.00
5.32
1.04
1369
1676
-307
-0.01
23.00
5.20
1.01
1399
1753
-353
-0.01
24.00
5.09
0.99
1429
1829
-400
-0.01
25.00
4.98
0.97
1457
1905
448
-0.01
26.00
4.87
0.95
1481
1981
-500
A -1
27.00
4.78
0.93
1510
2057
-547
-0.01
28.00
4.69
0.91
1536
2134
-597
-0.01
29.00
4.60
0.90
1561
2210
-649
-0.01
30.00
4.52
0.88
1587
2286
-699
-0.02
31.00
4.42
0.86
1603
2362
-759
-0.02
32.00
4.33
0.84
1621
2438
-817
-0.02
33.00
4.24
0.83
1637
2515
-878
-0.02
34.00
4.16
0.81
1655
2591
-936
-0.02
35.00
4.08
0.80
1671
2667
-996
-0.02
36.00
4.01
0.78
1689
2743
-1054
-0.02
37.00
3.93
0.77
1701
2819
-1118
-0.03
38.00
3.87
0.75
1721
2896
-1175
-0.03
39.00
3.80
0.74
1734
2972
-1238
-0.03
40.00
3.74
0.73
1750
3048
-1298
-0.03
41.00
3.68
0.72
1765
3124
-1359
-0.03
42.00
3.62
0.71
1779
3200
-1422
-0.03
43.00
3.56
0.69
1791
3277
-1486
-0.03
44.00
3.511
0.68
1807
3353
-1546
-0.04
Page 1 of 2
45.00
3.46
0.67
1822
3429
-1607
-0.04
46.00
3.41
0.66
1835
3505
-1670
-0.04
47.00
3.36
0.66
1848
3581
-1734
-0.04
48.00
3.31
0.65
1859
3658
-1799
-0.04
49.00
3.27
0.64
1875
3734
-1859
-0.04
50.00
3.23
0.63
1890
3810
-1920
-0.04
51.00
3.18
0.62
1898
3886
-1989
-0.05
52.00
3.14
0.61
.1910
3962
-2052
-0.05
53.00
3.10
0.60
.1922
4039
-2116
-0.05
54.00
3.07
0.60
1940
4115
-2175
-0.05
55.00
3.03
0.59
1950
4191
-2241
-0.05
56.00
2.99
0.58
1959
4267
-2308
-0.05
57.00
2.96
0.58
1974
4343
-2369
-0.05
58.00
2.92
0.57
1982
4420
-2438
-0.06
59.00
2.89
0.56
1995
4496
-2501
-0.06
F60.Obl
2.86
0.56
2008
4572
-2564
-0.06
LVI CI
0.00lac-ft
?A - r- L i d-
Page 2 of 2
' Cumulative Runoff Method for Sizing Detention Ponds- POND 2
fl
11
11
t
1
Design Storm
Release Rate
Area
Runoff Coefficient
Initial Time
Time Increment
100- r
cfs 100-yr release
acres Legend
input variable
minutes calculation
minutes fixed input
0.96
0.26
0.81
5.00
1.00
Inflow Inflow Release Storage Storage
Time Intensity Rate Volume Volume Volume Volume
min i h cfs cf cf cf ac-ft
5.00
9.95
2.10
629
288
341
0.01
6.00
9.31
1.96
706
346
360
0.01
7.00
8.80
1.85
778
403
375
0.01
8.00
8.38
1.76
847
461
386
0.01
9.00
8.03
1.69
913
518
395
0.01
10.00
7.72
1.63
975
576
399
0.01
11.00
7.42
1.56
1031
634
398
0.01
12.00
7.16
1.51
1086
691
394
0.01
13.00
6.92
1.46
1137
749
388
0.01
14.00
6.71
1.41
1187
806
381
0.01
15.00
6.52
1.37
1236
864
372
0.01
16.00
6.30
1.33
1274
922
352
0.01
17.00
.6.10
1.28
1310
979
331
0.01
18.00
5.92
1.25
1346
1037
310
0.01
19.00
5.75
1.21
1380
1094
286
0.01
20.00
5.60
1.18
1415
1152
263
0.01
21.00
5.46
1.15
1449
1210
239
0.01
22.00
5.32
1.12
1479
1267
212
0.00
23.00
5.20
1.10
1511
1325
186
0.00
24.00
5.09
1.07
1544
1382
161
0.00
25.00
4.98
1.05
1573
1440
133
0.00
26.00
4.87
1.03
1600
1498
102
0.00
27.00
4.78
1.01
1631
1555
76
0.00
28.00
4.69
0.99
1659
1613
47
0.00
29.00
4.60
0.97
1686
1670
15
0.00
30.00
4.52
0.95
1713
1728
-15
0.00
31.00
4.42
0.93
1731
1786
-54
0.00
32.00
4.33
0.91
1751
1843
-92
0.00
33.00
4.24
0.89
1768
1901
-133
0.00
34.00
4.16
0.88
1787
1958
-171
0.00
.35.00
4.08
0.86
1804
2016
-212
0.00
36.00
4.01
0.84
1824
2074
-249
-0.01
37.00
3.93
0.83
1837
2131
-294
-0.01
38.00
3.87
0.82
1858
2189
-331
-0.01
39.00
3.80
0.80
1873
2246
-374
-0.01
40.00
3.74
0.79
1890
2304
-414
-0.01
41.00
3.68
0.78
1907
2362
455
-0.01
42.00
3.62
0.76
1921
2419
498
-0.01
43.00
3.56
0.75
1934
2477
-542
-0.01
44.00
3.511
0.74
1952
2534
-583
-0.01
I
Page 1 of 2
45.00
3.46
0.73
1967
2592
-625
-0.01
46.00
3.41
0.72
1982
2650
-668
-0.02
47.00
3.36
0.71
1995
2707
-712
-0.02
48.00
3.31
0.70
2008
2765
-757
-0.02
49.00
3.27
0.69
2025
2822
-798
-0.02
50.00
3.23
0.68
2041
2880
-839
-0.02
51.00
3.18
0.67
2049
2938
-888
-0.02
52.00
3.14
0.66
2063
2995
-932
-0.02
53.00
3.10
0.65
2076
3053
-977
-0.02
54.00
3.07
0.65
2095
3110
-1016
-0.02
55.00
3.03
0.64
2106
3168
-1062
-0.02
56.00
2.99
0.63
2116
3226
-1110
-0.03
57.00
2.96
0.62
2132
3283
-1151
-0.03
58.00
2.92
0.61
2140
3341
-1201
-0.03
59.00
2.89
0.61
2155
3398
-1244
-0.03
60.00
2.86
0.60
2168
3456
-1288
-0.03
S`JN Ict
0.01lac-ft
J
Page 2 of 2
Calculations for Outflow
Project: Calculations By:
Project No.: 2008-148
Pond ID: Pond 1
Oakridge Buisness Park Date: 02/02/09
Type of Outlet•: Circular Or' ice
Type of Outlet: Weir
Diameter =M
inches
Length = 2.01
Invert=ft
Height = 1.00
Centroid Elevation =ft
100-yr Runoff- 6.02
100-yr WSEL=ft
Head=ft
Orifice Coefficient =
Weir Coefficient = 3
Orifice Area =sf
Max. Discharge = 0.00
cfs
Max. Discharge = 6.03
0
Calculations for Outflow
Project: Calculations By:
Project No.: 2008-148
Pond ID: Pond 2
Oakridge Buisness Park Date: 02/02/09
Type of Outlet: Circ far Orifice
Type of Outlet: Weir
Diameter =
inches
Length = 0.91
Invert=
ft
Height = 0.50
Centroid Elevation \-.
ft
100-yr Runoff-- 0.96
100-yr WSEL=
ft
Head= 0. 0
ft
Orifice Coefficient = /0.6
Weir Coefficient = 3
Orifice Area = 0.00
sf
Max. Discharge = 0.00
cfs
Max. Discharge = 0.96
I
I
1
N
j
J
1
Q
.
�
z
1
o
�-
1
w
=
w
1
U
�
�
-U
1
�z
O
z
00
U
O
1
�
L
�
W z
o D p
v I
Qo
D v v p
a D '
/r
\`
T
Ll )
pa
a p
o c Q
v p '
d a p a
p
1
0
W o
c p D
o p. a
c p Q
W
W 9
v 8 p V.
Q a' o
'_ D a
,A�r'
1..�
LLik
ry
D
- o
e O a � o
D 8
a p Da
W
v p a
v D a
Wa
1
�
r�
r
1
1
i
1
1
1
1
1
1
1
1
1
1
1
1
1
1
z
O
Z
LU
0
LLI
O0-
Z U
w U)
0-0
Oz
U<1
wU)
C)o
�o
IRTn
I
z
0
U
W
(n
Wcn
n-�,--
Dz
U
w
Q
APPENDIX C
t
1
1
1
1
Design Procedure Form: Porous Landscape Detention (PLD)
Designer: Paul Bennett, PE
Company: SA Myers, LLC
Date: February 2, 2009
Project: Lot 1 Oakridge Buisness Park, Second Filing, P.U.D, Parking Lot Expansion Basin 1
Location: Fort Collins
1. Basin Storage Volume
( I, = 100% if all paved and roofed areas u/s of PLD)
I, = 72.00 %
A) Tributary Area's Imperviousness Ratio (i = la / 100)
1 = 0.72
B) Contributing Watershed Area Including the PLD (Area)
Area = 3,920 square feet i AG(`CaSei
C) Water Quality Capture Volume (WQCV)
/iuYrcr-t/IQ1��
WQCV = 0.23 watershed inches
tWQCV=0.8' f0.91 "13-1.19"Iz+0.78.01
D) Design Volume: VolpLD = (WQCV / 12) `Area
Vol = 74 cubic feet
2. PLD Surface Area (APLD) and Average Depth (da,.)
APLD = 100 square feet
(from 74.31 square feet to 148.63 square feet)
(day.: = (Vol / APLD), Min=0.5% Max=1.0')
da,. = 0.74 feet
3. Draining of PLD (Check A, or 8, or C. answer D)
Infiltration to Subgrade with Permeable
Based on answers to 3A through 3D, check the appropriate method
Membrane: 3(C) checked and 3(E) = no
A) Check box if subgrade is heavy or expansive clay
.. Underdrain with Impermeable
B) Check box if subgrade is silty or clayey sand X
Liner. 3(A) checked or 3(E) = yes
C) Check box if subgrade is well -draining soil
`X ` Underdrain with Non -Woven Geotextile Fabric:
D) Check box if underdrains are not desirable or
3(B) checked and 3(E) = no
if underdreins are not feasible at this site.
16-Mil. Impermeable Membrane with No Underdrain:
E) Does tributary catchment contain land uses that may have
3(D) checked - Evapotranspiration only
petroleum products, greases, or other chemicals
present, such as gas station, esnoOther:
hardware store, restaurant, etc.? IL_J
4. Sand/Peat Mix and Gravel Subbase (See Figure PLD-1)
A) Heavy or Expansive Clay (NRCS Group D Soils) Present;
18" Minimum Depth Sand -Peat Mix with 8" Gravel Layer. 16-Mil.
Perforated HDPE Underdrain Used.
Impermeable Liner and a 3" to 4" Perforated HOPE Underdrain.
B) Silty or Clayey Sand (NRCS Group C Soils) Present;
Perforated HOPE Underdrain Used.
X 18" Minimum Depth Sand -Peat Mir with 8" Gravel Layer and a
3" to 4" Perforated HDPE Underdrain w/ Non -Woven Pemeable Membrane.
C) No Potential For Contamination And Well -Draining
18" Minimum Depth Sand -Peat Mix with Non -Woven
(NRCS Group A or B Soils) Are Present; Underdrains Elliminated.
Pemeable Membrane and No Underdrain (Direct Infiltration).
D) Underdrains Are Not Desirable Or Are Not Feasible At This Site.
18" Minimum Depth Sand -Peal Mix with An Additional 18"
Minimum Layer Sand -Peat Mix or Sand-Class'A' Compost Bottom
Layer (Total Sand -Peat Depth of 36"). 16-Mil. Impermeable Liner Used.
E) Other:
Other:
notes:
WQBASINI, PLD
2/2/2009, 10:44 AM
i
1
1
1
t
1
1
1
1
1
.1
1
A
1
1
1
1
Design Procedure Form:. Porous Landscape Detention (PLD)
Designer: Paul Bennett, PE
Company: SA Myers, LLC
Date: February 2, 2009
Project: Lot 1 Oakridge Buisness Park, Second Filing, P.U.D, Parking Lot Expansion Basin 2
Location: Fort Collins _
1. Basin Storage Volume
( I, = 100% if all paved and roofed areas uls of PLO)
I, = 81.00 %
A) Tributary Area's Imperviousness Ratio (i = 1.1100 )
i = 0.81
B) Contributing Watershed Area Including the PLO (Area)
Area = 6,534 square feet //lLt"Lax +�--
C) Water Quality Capture Volume (WQCV)
WQCV = 0.27 watershed inches
(WQCV =0.8'(0.91'13-1.19-I'+0.78-M
D) Design Volume: Volpw = (WQCV / 12)' Area
Vol = 146 cubic feet
2. PLO Surface Area (APO) and Average Depth (dg,)
APtD = 200 square feel
(from 145.77 square feet to 291.55 square feet)
(dw: = (Vol / APLD), Min=0.5', Max=1.0')
dam, = 0.73 feet
3. Draining of PLO (Check A. or B, or C, answer D)
Infiltration to Subgrade with Permeable
Based on answers to 3A through 3D, check the appropriate method
Membrane: 3(C) checked and 3(E) = no
A) Check box if subgrade is heavy or expansive Gay
Underdrain with Impermeable
B) Check box if subgrade is silty or clayey sand
Liner: 3(A) checked or 3(E) = Yes
C) Check box if subgrade is well -draining soil
. X - Underdrain with Non -Woven Geotextile Fabric:
D) Check box if underdrains are not desirable or 0
3(B) checked and 3(E) = no
if underdrains are not feasible at this site.
16-Mil. Impermeable Membrane with No Underdrain:
E) Does tributary catchment contain land uses that may have
3(D) checked - Evapotranspiration only
petroleum products, greases, or other chemicals
-
present, such as gas station,
Other.
r--yes —ono
hardware store, restaurant, etc.?
4. SandlPeat Mix and Gravel Subbase (See Figure PLD-1)
A) Heavy or Expansive Clay (NRCS Group D Soils) Present;
18" Minimum Depth Sand -Peat Mix with 8" Gravel Layer. 16-Mil.
Perforated HDPE Underdrain Used.
Impermeable Liner and a 3" to 4" Perforated HOPE Underdrain.
B) Silty or Clayey Sand (NRCS Group C Soils) Present;
Perforated HOPE Underdrain Used.
X 18" Minimum Depth Sand -Peat Mix with 8" Gravel Layer and a
3" to 4" Perforated HDPE Underdrain w/ Non -Woven Pemeable Membrane.
C) No Potential For Contamination And Well -Draining
18" Minimum Depth Sand -Peat Mix with Non -Woven
(NRCS Group A or B Soils) Are Present; Underdrains Elliminated.
Pemeable Membrane and No Underdrain (Direct Infiltration).
0) Underdrains Are Not Desirable Or Are Not Feasible At This Site.
18" Minimum Depth Sand -Peat Mix with An Additional 18"
Minimum Layer Sand -Peat Mix or Sand-Class'A' Compost Bottom
Layer (Total Sand -Peat Depth of 36"). 16-Mil. Impermeable Liner Used.
E) Other:
Other:
Notes:
WQBASIN2, PLO
2/2/2009, 10:45 AM
. o `° 3 m -0
0
0 _>1 _ 0) o a E
U E y N C >. m T E a)
o E
'mC',cLi ami d c cd cc
coQa
O S+C Q C C O p CO
cc CL
e
' �' 0 U c• E c) co m CO U °'
CL
cc N O d ,., N :� cc a) = t C cc r_
4) m 0 0
'or moy ) ya co a taU)3
u, > �$ 3 c 3 o v E 3 m o c
°- ,e F- au)) _ m o o -
w w. v
Nc Owcmi Q� U oN 3m yyE c
0 Z �) o �? o m ami m 0
Fo�pa d 'ov -- n: a) c
N o co # N y M O 0 a m
yr c m
Oo 0o o m m o A co w vm c m m J.o w v
CL
O y rn m w I j�`` > r� LD aXi (A a d y 0) n v@
t m c E n m ! o :��:_, , U v o— T'o a) >, a) u)
a) : o m LU 0 0 c n a) F c 'o I- v co m
c a) I'G i t: _j H a) a) d 0 m e c � c
>Z a)1 Co�Ja) Lam!
UQ) U rn > c
> `� GrHAJ— U Q Q o= N L L C Q'CN
CO m `-_I p::JaJ co >
U � > >i f0
Z Q Q
0 [ J
' m m o U t� 1 c o
mE ,G U
CO } C d m'C J— U x.'0
O:? U
a , .� . m ... a) `C O)
O p p a1 �.1Trt Ci`!:=p 'O C 'O L •O C T
III ' Q O BJ.=,N f0 �a) ET
caNrm
1-0 °mCoca)Ev
(D Z m
0) 3
0-0Q (Ca to C
C 0
C C x o a) L -
zw OJ UR' amp SCo c
7 W lL zw a) U) E O y Mn O O 0) :�..... i
Q t d E d~ m mo SD
`J
o a co`r°_joo:3CL
o
m
Q
Q.
I
APPENDIX D
i
I
1
1
1
1
1
1
1
1
4;�' ``,;.�,�,�
STORM DRAINAGE REPORT
l5 `� FOR
LEMAY-HARMONY SPECIAL IMPROVEMENT DISTRICT #78
(OAK RIDGE PORTION)bwf
February 27, 1984
TO
CITY OF FORT COLLINS
FROM
JAMES H. STEWART AND ASSOCIATES, IN,C.
CONSULTING ENGINEERS
I
STORM DRAINAGE REPORT
FOR
LEMAY-HARMONY SPECIAL IMPROVEMENT DISTRICT #78
(OAK RIDGE PORTION)
INTRODUCTION:
That portion of the proposed Oak Ridge Subdivision which is to be included
in the Lemay-Harmony Special Improvement District (S.I.D:) #78 is located
in the'West half of the Northwest 1/4 of Section 6, Township 6 North, Range
68 West of the Sixth P.M. in the City of Fort Collins, Colorado. The site
is zoned mostly Business, with some Residential. A primary reference is'.
the McClelland and Mail Creek Major Drainageway Plan, December 1.980.. In
this report, this study will be referred to as the McClelland Drainage
Study.
EXISTING DRAINAGE:
.The McClelland Thalweg moves through the rth 1/4 of the proposed area in
a Southeasterly.direction (See Exhibit #11. Drainage.moves toward the
McClelland Thalweg South from Harmony and North from a mild ridge running.
East and West through the Rule property. From this.same ridge, runoff
moves South to an existing thalweg running East and West which is located
approximately 500 feet North of the Oak Ridge South property line. 'Drain- -
-age moves North to this thalweg from Mail Creek Ditch, which is located
South of the Oak Ridge South property line (See Exhibit #1).
PROPOSED SITE DRAINAGE:
1.. Oak Ridge Business Park, First Filing.
The Oak Ridge Business Park, First Filing, is, shown as Phase 1
-on Exhibit #l. Proposed drainage in this area is described in
the Oak Ridge Business Park, First Filing, Storm Drainage Report
and the reader is referred to this report. The inlets as shown
on Exhibit #1 show size of opening in parentheses.
Several changes in the.original report have.been.made. Inlets
A through D have been relabeled as follows: -
Inlet A = SDI-3
Inlet.B = SDI-4 -
Inlet C = SDI-2
Inlet D = SDI-1
(SDI = Storm Drain Inlet).
-1-
The inlets labeled .SDI-1, SDI-2 and SDI-4 each receive a 10-year
design flow of 2.0 cfs. The inlet SDI-4 has been increased to a
' 10-foot-long inlet so that it can receive runoff from the East-
bound lanes of Harmony Road once curb and gutter are placed
along Harmony. This additional flow from Harmony equals 5.0 cfs. .
The total flow entering inlet SDI-3 is 7 cfs.
tThe storm drain between SDI-2 and the outlet into McClelland's
Thalweg was increased from a 21-inch to a 24-inch to handle the
' additional flow from Harmony Road. Everything else is the same
as spelled out in the Oak Ridge Business Park, First Filing,
Storm Drain Report. The reader is referred to this report
for specifics. .
' 2. Improvements to McClelland's Thalweg.
McClelland's Thalweg, as it traverses through the Oak Ridge .
property, is intercepted by two streets, Oak Ridge Drive and
Wheaton Drive. At Oak Ridge, the 10-year developed flow equals
59.0 cfs and is carried under the road by three 36-inch culverts.
The two inlets, SDI-12 and SDI-139 receive runoff from the street.
The two are connected to one another via a 15-inch line. Another
15-inch-line exits SDI-13 and empties into McClelland's Thalweg.
on the downstream side. Inlet SDI-12 receives 3.86 cfs and Inlet
' SDI-13 receives 2.51 cfs. The three 36-inch culverts have enough
capacity to carry the 10-year combined channel and street flow
which will not surcharge the system. All of the 100-year fully -
developed flow, which equals 171 cfs, will be carried under the
road at Oak Ridge (i.e., no overtopping will.occur).
The 10-year developed flow to be carried under Wheaton is 90.0 cfs.
' This will require two 42-inch culverts. Two inlets, SDI-10 and
SDI-11, receive runoff from the street. The two are connected.to
one another via a 15-inch line. Another 15-inch line exits SDI-10
1 and empties into McClelland's Thalweg on.the downstream side. Inlet
SDI-10 receives 3.63 cfs and Inlet SDI-11 receives 4.32 cfs. The
100-year fully -developed flow at Wheaton. Drive equals 367 cfs. Of
this total, 214 cfs will pass throughthe culverts, while.the re-
maining 153 cfs will pass over the top of Wheaton Drive with a depth
at the crown not exceeding six inches.
The channel sections for the improved McClelland Thalweg were.
designed to carry 100-year flows"under fully -developed conditions.
The channel sections vary as the thalweg moves across the Oak
' Ridge property. The locations of varying channel sections are
shown in Exhibit #1 and the section details are shown on Exhibit
#2. These sections are labeled A -A, B-B and C-C..
The off=site, 100-year fully -developed flow from McClelland's
basin, after detention, equals 55 cfs. This flow enters the
I
-2-
I
1 �
proposed Oak Ridge site via an existing 27=inch by 44-inch arch
pipe under Lemay and Harmony. Channel Section A-A,is designed
to handle the off -site flow of 55 cfs.
'
As the thalweg moves from Harmony to Oak Ridge Drive, the on -
site runoff equals 1.1:6 cfs (A = 15.6 acres, C = 0.85 acres).
This flow is added to the 55.0 cfs off -site flow. and equals a .
1
total of 171 cfs. Channel Section B-B is designed to handle
this total flow:
Similarly, the thalweg continues from Oak Ridge.Drive'to
1
Wheaton Drive, accumulating additional runoff from.a total
-area of. 42.0 acres, which includes most of Oak Ridge Business
Park,First Filing. The total flow, which includes the
55.0 cfs off -site flow, equals 367 cfs. Section C-C was
designed to handle this total flow:
3. Storm Drain Design from Rule Drive to. Keenland Drive:
The storm drain system'which carries the runoff from areas
A, B, C, D and E is designed to carry 10-year fully -developed
'
flows which will empty into the existing thalweg, located
just East of the Wheaton - Keenland.intersection. (See
Exhibit #1). Inlet SDI-9,1 ocated on the Northwest.corner
of Wheaton and Rule, has a '24-inch stub -out which receives.a
'
flow of 25.5 cfs and is transported South down Wheaton via a
24-inch storm drain .until it is intercepted by runoff from
Area B.• At this point, the combined 10-year fully -developed
'
flow from Areas A and B equals 48 cfs, and the storm drain in-
creases to a 30-inch pipe, which goes all the way to:the manhole
at the intersection of Wheaton and Keenland.
'
This manhole also receives runoff from half the street of Rule
Drive and Keenland Drive, and that portion ,of Wheaton between
.Rule and Keenland. This 10-year flow equals 5.7 cfs.and empties
'
.into Inlet SDI-8 (See Exhibit #1). A 15-inch line exits SDI-8
and taps directly into the side of the 34-inch by 53-inch oval
_pipe which.carries runoff from Open Channel "A".
'
Additional runoff enters the same manhole via.a 34-inch by 53-inch
elliptical pipe. This is accumulative runoff from Area C and 240
off -site acres West of Lemay Avenue. Three.30-inch.culVerts (de-
'
termined by others) carry. a 10-year existing -condition flow of
53 cfs from off -site under Lemay and empty into Open Channel "A".
Open Channel "A" also.earries 10-year fully -developed runoff from
Area C which, when combined with.the off -site flow, equals a total
'
of 71 cfs. This total flow is conveyed to the manhole at the
intersection of Wheaton and Keenland Drive via the 34-inch by
53-inch elliptical pipe. The combined 10-year flow which exits
this manhole via a 38-inch by 60-inch elliptical pipe.equals
104 cfs. This flow then emptiesinto the existing thalweg East
of the Wheaton-Keenland Drive intersection.
'
-3-
' Inlets SDI-6 and SDI-7, located on the Northeast corner of
Wheaton and Keenland, receive a total flow of 8.4 cfs.(4.2 cfs
each) from Area D for 10-year fully -developed conditions. This
flow is conveyed via a 15-inch and 18-inch..pipe to SDI-71 which
1 is located on the South side of Keenland. Inlet SDI-T receives
4.1 cfs from Area.E for 10=year fully -developed conditions: The
total 10-year fully=developed flow from Areas D and E equals
11.7 cfs and empties into.the existing thalweg East of the
Wheaton-Keenland intersection via an 18-inch pipe. The runoff
for the remainder of land between.Area E and the South property.
1 line of Oak Ridge will find its way overland to.this thalweg.
4.. Major Storm Design from Rule Drive to Keenland Drive..
Open Channel "A" is designed to carry the 100-year off -site
1 existing -condition :flow West of Lemay and. the 100-year fully -
developed flow from half of Area:C. This. total flow equals
125 cfs. See Exhibit #3 for a section detail of Open Channel
"A". The portion of 125 cfs that is not taken 'by the storm
drain system will spill -over the intersection into the existing
-thalweg,'located on the East side of the Wheaton.- Keenland
intersection.
Runoff from Areas A, B and.half of C under 100-year fully
developed conditions finds -its way down Wheaton Drive, where it
is carried to and through the intersection of Wheaton and Keenland
into the existing thalweg East of this intersection. The 100-
year runoff for fully -developed conditions.from Area D spills
over the intersection after the storm drain system reaches its
capacity. The 100-year total flow at the entrance to the exist-
ing thalweg just East of the Wheaton - Keenland intersection is
300 cfs. of this total, 116 cfs will pass through the culvert,
' while the remaining 184 cfs will overtap the Wheaton - Keenland
intersection with a depth at the crown not exceeding six inches.
1 Designed by .Guy F. McCabe °-
' Written by Don J. McClelland
1 .-
-4-
[l
1
L
l c.�Oi iPUTATIONSCa1STiEW
' lames H. Stewart & Associates, Inc. 214 N. Howes St. Ft. Collins, CO 805?1 13WIJ •;>33$
3y:Date 'O/3 Client: FVeri ><!- En ie; prise ( Sheet No. : of LL
'.hkd By: Date Project: Oalr if 15051 "es s pint'r 2-n Job No.
1 r .. ffrrlt......1\\\
Subject
Lv�- ..1 o. F . : O«_ _ •;L id.. e_! 13 vs v keSS csL�—t2� �;✓i1_Td r44
lhk
a:-.n_
y
.I �, i � i�Vafvr�t� cirrG� an
1
;: 'de:✓,2.t,`.aPr�ff:du. R esSS_e�
1
w i. :.',p...:...r:�d_o4-1
_
I
-f�, - .--
'
e 41 res moo':..: r.b.. (},A'rinCi^+5 :u
_ _. o •i s �fv c '.:, �ns+ir(i f'c.-I& 7:An
O�
40'4 Jo
1 - �,.�-.�Z f , t : i Tom• LT(t 1 � �-.` i • : 1
¢i9-}�,1
cFrc
. f.
f, I -;1 -� --�-; z
---
) uo.•."_ ti
[ 1, u Ire - o
7`,_i..s_.wL�
1
' i 1
I
11
11
I
/
/
/
/
/
IXIETINO it RYINS
LINN"
:L1IXTlF9fEEIIl1®®
m1mmoglow
�. .
(
I
� I
I I
' APPROXIMATE LOCATION
IIJJIIIII,,��aa{jI�j1j1jj OF ADJACENT STORM
� FACILIRES (TYP) — — — —
xx I
(Umeat m nine TA
IN4.U'
\\ \D�arc tit,\ \\
1 \
\
got
GIDEWALK HASE�
ROOF GRAIN 1
SWALE l
\ 3' CONCRETE P
\\ SIOEWAtK CHASE
`
PAN
LOT 1,
CAKRIDGE BUSINESS %RK
SECOND FILING, P.U. D`
4800 WHEATON DRIVE
2 STORY CONCRETE
BUIIfI G
\ E.F=4S74.18
LEGEND
BASIN SIZE
(ACRES)
m0 YR
FLOW (CFS)
DESIGN POINT
FmFaNss
—
RywP,ragml
Ryan Ellx
iIDe ECave1' (itl,M
PO
Gamma P2B53P
STORM PPE
(680) e000350
APPLICANT
`
BnsriMem auNRlun uc
10947 E Better Place
`
Auva CO 50013
♦
J
J
\ LOCATION
Win
OF ADJACENTNKTIE
OF POJACENT STORM
♦\
_
(TIP)
0 w w 120
o9
J Ql E
�FACIUTIES
♦
N C O u
CONCRETE PAN �'� \
�\ 4' CONCRETE PAN
�NR
*40
N.
\ \\ W BENCWARK /
\ RECOI£RED p113ELED'%' IN O NCRETE PAN
New 29brea4.leaJ E-Vr
\
1 1 \ \
1 / PART OF TRACT ., \
yy OAKRIDGE MULAGE P.U.O. \
NINTH FILINGSWALE ell,
\
4
\
(DRAINAGE, UTILITY AND \
4' CONCRETE PAN LANDSCAPE EASEMENT \
PAN FOR
ROOF DRAIN
ROOF GRAN
//WADC/2C/y NECKED
l'Wo
NECKED
.......•-'�\W HECKED
HECKED
UTILITY PLAN
City Engineer
BY
Winter a Wgatewnter utility
BY
StormwOter Utility
BY
Pert h Recreemn
BY:
Traffic Engineer
w
w
U�
Oz
=
J
Q
Z
d
w
K�
UQ
U0
ZQ
Z
K
Y
U
O
�a
Q
O
JI%
THE EXISTING FINISH FLOOR ELEVATIONS SHOWN ARE A
MINIMUM OF 1' ABOVE THE 100—YEAR WATER SURFACE
ELEVATIONS FOR THE PROPOSED PONDS.
anum
I
� I
I I
I I
APPROkkCENT LOCATION
Es ADJACENT STORN
Tjj — FACILITIES (iYP) — — _... _
I�IW�CI'I I
400
♦ 0 AItPROXWTE
STORM
EX. HASL FACILITIES (TIP) TION
IX. SIDEWCE ♦
IX. 3' CONCRETE PAN ♦
NEW 2' SIDEWALK CHASE
DETENTION POND 1 ♦♦
\ REOD 100—YR VOLUME-241CF
REOD WOCV=24CF
` PWMDO-315CF
TOTAL VOLUME
100—YR WSEL-4967.31
WO WSEL=4966.31
POROUS LINCSCAPE DETENTION
(SEE DETAIL SHEET T)
2' CURB C
LEGEND
WIN SIZE
(ACRES)
too YR
FLOW ICES)
DESIGN POINT
1770!NPPE
IX. 4CONCRETE PAN }w-�
(LOWER Matl:tLM03 CI®f) \
NEW 2 CHASE ' 101 \
-V. UNITS OF 100-YR PONDING AREA /
\ \ ARE SHADED GYP)
x' case cur ♦
L DETENTION PONO2
REOD 100—YR VOLUME=479CF
REOD WOLV=146CF
i TOTAL VOLUME PRWDED=656CF
\ 100—YR WSEL=4967.53 `
^ / WO WSEL-4967.0
POROUS WIDSCAPE DETENTION \ \
W/ UNDERDRNN
(SEE DETAIL SHEET ))
4' 2'WIN x 6" TALL CURB CUT \
NEW Y' pM3E
IX. 4' CONCRETE PANU. PAN
\ `
ROOF DRAINR TRACT C, ` \
/\ �OAKRIDGE VILLAGE P.U.D., /
EX. ROOF DRMN • NINTH FILING City 0 Fort Collins, Colorado
(DRAINAGE. UTILITY AND UTILITY PLAN APPROVAL
LANDSCAPE EASEMENT APPROVED:
City En9Tneer DAI
NECKED BY: r DAl
Water h Wastewater Utility
6xnoB trcF4
�o�.wes •.,.,ram NECKED BY'
scormwater uunv DAl
{(CHECKED BY*
Parke x Reareman DA-
`�> NECKED BY: _
ONAL EN TraKc Engineer DA
�U�oS Hrrvrn Try
mm
N
N
m
E
O
n
O
N
N L
E n
y
=
m A
�
>
gQ
W
O
t
has
2
~
1—
aN
N
way
cis
0
as
n
of
1-
Tn
w0
0
Lu
a
Oa
O
LU
a
L)
a:0
wz_
09
LU
UT
y
W
0
Ya
o
0