HomeMy WebLinkAboutRAM'S CROSSING K2 APARTMENTS - BDR - BDR110004 - REPORTS - DRAINAGE REPORTb
LEGEND
CN O
c°xciRriM.s�loui
IP O
°srlRiooew
O
NOTES:
1. vFE VNOSCA!£fiAN FOftxEVEGEfAiIOM YET1100SAIOOETAL6IXIIiNGCCIyyTRGlpl.WY571LORTli®EO/JIONOE
UIGExxACTNECONSIMR.TICN9W1ffsEEEIED.WO YIALl1m RAOYPIEF 11 OiTKCrtYK FCRI cOLLNSSfIXiM
ORIYUGECOe6'1RUCTgN 5T410IRp5.
2. TNECONIRAG WRLBERESPONSIBLEFORALLMS RBEMGFPINOI UISST.TBYI2EOINACCOROANC£WRNTXE
S RMWATERMMY MEWRANANDSTATESTORMWATEROISCNAROEPERMIT.
a
zWg.
Y y <O N°
N SC jN6N
`5y 0 z p 9
W OWO�
x QUx�O¢
x=LL
C.
COLORAOOSTATE
UNIVERSITY
P -
•rtt i
COL ORAOOS ATE
UNIVERSITY
_
—
x`naal�Bl
r,
9/J
.LANE
IL
E3
EEf
r --,
'°_�
('
J
z- weaLc �6
z
O
O
z
�
F
ui
Oy
Z
- -
0
O
\
x°2 xSxNl RiEil x.BAG .ROVE .xp
I�
2
RAxo� iw
W
O
R
I 1
�1
IX/577NG BU/LO/NG
r—xb
1TIR'
_ Jlei a
1-
W
CALL UMITY NOYFIU
E[HrER C COLORAW
811
DeLL x-wsl<ss o.rs N .o..IaT
®fG 11[ u 0.11[,IO YUXOWOiIXYO
iLHx VxUMi.
PRELIMINARY m gggE
NOT FOR CONSTRUCTION n 0
OTY CF roBr CaUMS. C«IX ADO
U1LITY PLAN APPROVAL
AwRoceu
ary 04@
aE"ED S.:
..R....sR..R, �..�.
OIE"ED SY:
irPu,.R. u1Vle
OIEIXED BY
Mea r Yw,oi
O MD BY:
n.mc tw,[t.
C E"ED BY:
v<axo.,ui
PROJ. M. I IYOYOI I
a
Calculation Results Summary
Scenario: Base
»» Info: Subsurface Network Rooted by: 0-1
»» Info: Subsurface Analysis iterations: 1
»» Info: Convergence was achieved.
CALCULATION SUMMARY FOR SURFACE NETWORKS
( Label
I Inlet
I Inlet
I Total
I Total
I
I Type I
I Intercepted
I Bypassed
I
I I
I Flow
I Flow
I
I I
I (cfs)
I (cfs)
I-------I---------------t----------------------I-------------I---------
I I-3
1 Generic Inlet I
Generic Default 100%
I 0.00
I 0.00
11-2
1 Generic Inlet I
Generic Default 100%
1 0.00
1 0.00
I I-1
-----------------------------------------------------------------------
I Generic Inlet I
Generic Default 100%
1 0.00
1 0.00
CALCULATION SUMMARY FOR SUBSURFACENETWORK WITH ROOT: 0-1
Capture
I Gutter
I Gutter I
Efficiency
I Spread
I Depth I
M
I (ft)
I
I (ft) I
I I
-----------
100.0
I --------
1 0.00
I -------- I
1 0.00 1
100.0
1 0.00
1 0.00 1
100.0
------------------------------
1 0.00
1 0.00 1
I Label I
Number I
Section
I Section I
Length
I Total
I Average
I Hydraulic I
Hydraulic I
I I
of I
Size
I Shape I
(ft)
I System
I Velocity
I Grade I
Grade I
I I
Sections I
I
I
I Flow
I (ft/s)
I Upstream I
Downstream I
I I
I
---------I----------I--------I--------
I
I
I (cfs)
I
----------
I (ft) I
-----------
(ft) I
------------I
I - ------I----------
I P-1 1
I
1 1
12 inch
I Circular 1
7.50
1 4.80
I
1 6.11
I I
1 20.57 1
20.44 I
I P-2 1
1 1
12 inch
I Circular 1
22.10
1 4.80
1 6.11
1 21.10 1
20.86 1
I P-3 1
1 1
12 inch
I Circular 1
38.70
1 4.80
1 6.11
1 21.80 1
21.39 1
I P-4 1
1 1
12 inch
I Circular 1
42.50
1 3.20
1 4.07
1 22.30 1
22.09 1
I P-5 1
-----------------------------------------------------------------------------------------------
1 1
12 inch
I Circular 1
42.50 1
1.60
1 2.04
1 22.48 1
22.43 1
I Label
I Total
I Ground
I Hydraulic
I Hydraulic I
I
I System
I Elevation
I Grade
I Grade I
I
I Flow 1
(ft)
I Line In
I Line Out I
I
I (cfs)
I
-----------
I (ft)
-----------
I (ft) I
-----------
I - ------I--------
1 0-1
I 4.80
I
1 23.30
I
1 19.53
I I
1 19.53 1
I J-1
I 4.80
1 23.20
1 20.86
1 20.57 1
I J-2
1 4.80 1
23.00
1 21.39
1 21.10 1
11-1
1 4.80
1 22.70
1 22.09
1 21.80 1
11-2 1
3.20 1
22.70 1
22.43
1 22.30 1
I-3 1
------------------------------------------------------
1.60 1
22.70 1
22.51
1 22.48 1
Completed: 11/02/2011 12:28:29 PM -
Title: RAM K2 - Minor Storm Sewer I Project Engineer. Interwest Consulting Group
x1 -AdrainageNdesignVam k2 stonn.stm Interwest Consulting Group StormCAD v5.5 (5.5005]
11/02/11 12:29:01 PM 0 Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1
Label: 1-3
Rim: 22.70 ft
Sump: 20.30 ft
Profile
Scenario: Base
Profile: Profile - 1
Label: 1-2
Rim: 22.70 ft
Sump: 20.08 ft
Label: P-5
Up. Invert: 20.30 ft
Dn. Invert: 20.08 ft
L: 42.50 ft
Size: 12 inch
S:0.005176ft/ft
Scenario: Base
Label: 1-1
Rim: 22.70 ft
Sump: 19.87 It
Label: PA
Up. Invert: 20.08 It
Dn. Invert: 19.87 ft
L: 42.50 It
Size: 12 inch
S: 0.004941 fUft
Label: J-2 Label: J-1
Rim: 23.00 ftRim: 23.20 ft
Sump: 19.67Wmp: 19.56 trabel. 0-1
Rim: 23.30 It
�} 100 9x- Sump: 19.53 ft
Label: P-1
Up. Invert: 19.56 ft
Label: P-3 Label: P-2 Dn. Invert: 19.53 It
Up. Invert: 19.87 ft Up. Invert: 19.67 fL: 7.50 ft
Dn. Invert: 19.67 ft Dn. Invert: 19.56 (Size: 12 inch
L: 38.70 ft L: 22.10 ft S: 0.004000 Wit
Size: 12 inch Size: 12 inch
S: 0.005168 ft/ft S: 0.004977 fUft
25.00
20.00 Elevation (ft)
15.00
0+00 1+00 2+00
Station (ft)
Title: RA MK2 - Minor Storm Sewer Project Engineer: Interest Consulting Group
x:\...\dral ngye\deslgn\ram k2 storm.stm Intsrweet Consulting Group StormCAD v5.5 IS 50051
11/02/11 2:27:38 PM m Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA +1-203-755-1666 Page 1 of 1
Scenario; Base
J-P-1 0-1
v
1-3 P_ 5 1-2 P-4 Zx. 1 P-3
Title: RAM K2 - Minor Storm Sewer Project Engineer: Interwest Consulting Group
x:\...\drainage\design\ram k2 storrn.stm Interwest Consulting Group Storm CAD v5.5 (5.5005)
11/02/11 12:27:51 PM ®Haestad Methods, Inc. 37 Brookside Road Waterbury, CT oe708 USA +1-203-755-1666 Page 1 of 1
Interwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
RATIONAL METHOD PEAK RUNOFF
(100-YEAR)
LOCATION:
RAM CROSSING K2
PROJECT NO:
1144-069-01
COMPUTATIONS BY:
MPO
DATE:
11 /2/2011
100-yr storm, CI = 1.25
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Des.
Point
Area
Design.
A
(ac)
C Cf
tc
(min)
i
(new)
(in/hr)
O (100)
(cfs)
from
Design
Point
O (100)
(Cfs)
O(100)101
(cfs)
Existing
1.94
0.98
5.0
9.95
19.0
19.0
Existing Site
Proposed Total
1.94
0.95
5.2
1 9.51
17.5
1
17.5
Proposed Total Flow
Proposed Central
0.55
0.88
5.0
9.95
4.8
4.8
Area Draining to Area Inlets and 12" PVC
Q=CiA
Q = peak discharge (cfs)
C = runoff coefficient
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
NOTE: Intensity based on Figure 3-1, 1999 (Regional Analysis)
Flow.xls 0100
Interwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
10-yr storm, Cf =
RAM CROSSING K2
1144-069-01
MPO
1 I /2/201 1
1.00
RATIONAL METHOD PEAK RUNOFF
(10-YEAR)
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design
Point
Tributary
Sub -basin
A
(ac)
C Cf
tc
(min)
i
(new)
(iNhr)
Q (10)
(Cfs)
from
Design
Point
Q (10)
(Cfs)
Q(10)tot
(Cfs)
Existing
1.94
0.79
7.0
4.31
6.6
6.6
Existing Site
Proposed Total
1.94
0.76
1 7.3
4.24
6.2
1
6.2
Proposed Total Flow
Proposed Central
0.55
0.71
5.3
4.87
1.9
1.9
Area Draining to Area Inlets and 12" PVC
Q=CICiA
Q = peak discharge (cfs)
C = runoff coefficient
CI = frequency adjustment factor
I = rainfall intensity (in/hr) from IDF curve
A = drainage area (acres)
NOTE: Intensity based on Figure 3-1, 1999 (Regional Analysis)
Flow.xls - Q10
Interwest Consulting Group
1218 West Ash, Suite C
Windsor. Colorado
LOCATION:
PROJECT NO:
COMPUTATIONS BY
DATE:
2-yr storm, Cl =
RAM CROSSING K2
1144-069-01
MPO
11/2/20I1
1.00
RATIONAL METHOD PEAK RUNOFF
(2-YEAR)
DIRECT RUNOFF
CARRY OVER
TOTAL
REMARKS
Design
Point
Tributary
Sub -basin
A
(ac)
C Cf
tc
(min)
i
(new)
(in/hr)
Q (2)
(cfs)
from
Design
Point
Q (2)
(cfs
Q(2)tot
(cfs)
Existing
1.94
0.79
7.0
2.52
3.8
3.8
Existing Site
Proposed Total
1.94
0.76
7.3
2.54
3.7
3.7
Proposed Total Flow
Proposed Central
0.55
0.71
5.3
2.85
1.1
1.1
Area Draining to Area Inlets and 12" PVC
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)
NOTE: Intensity based on Figure 3-1, 1999 (Regional Analysis)
Flow.xls Q2
Intemest Consulting Group
1218 West Ash, Suite C
Windsor. Colorado
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
100-yr storm
RAM CROSSING K2
1144-069-01
MPO
11/2/2011
C1= 1.25
STANDARD FORM SF-2
TIME OF CONCENTRATION -100 YR
SUB -BASIN
DATA
INITIAL /OVERLAND
TIME (0)
TRAVEL TIME I GUTTER OR CHANNEL FLOW
(R)
tc CHECK
(URBANIZED BASIN)
FINAL
tc
REMARKS
DESIGN
POINT
SUBBASIN(s)
(1)
Area
(ac)
(2)
C
(3)
C'CI
Length
N
(4)
Slope
(%)
(5)
ti
(min)
(6)
Length
(ft)
(7)
Slope
(%)
(8)
n
Manning
rough.
Val.
(IVs)
(9)
it
(min)
(10)
tc =
ti+a
(11)
Total
111)
(12)
IC.(l/180)+10
(min)
(13)
(min)
(14)
Existing
1.94
0.79
0.98
40
1.0
1.3
510
1.50
0.016
2.5
3.5
4.8
5501
13.1
5.0
Existing Site
Proposed Total
1.94
0.76
0.95
40
1.0
1.7
510
1.50
0.016
2.5
3.5
5.2
550
13.1
5.2
Pro osed Total Flow
Proposed Central
1 0.55
0.71
0.88
40
1.0
2.5
1401
2.20
0.016
3.0
0.8
3.3
180
11.0
5.0
Area Draining to Area Inlets and 12- PVC
EQUATIONS:
tc=ti+it
ti=11.87(1.1- CC, )Lo.$)/Sv3
It = L/Vel.
Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + If and urbanized basin check
min. tc = 5 min. due to limits of IDF curves
Flow.xls TOG-100
Interest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
LOCATION:
PROJECT NO:
COMPUTATIONS BY:
DATE:
10-yrstorm
RAM CROSSING K2
1144-069-01
MPO
11/2/2011
C1= 1.00
STANDARD FORM SF-2
TIME OF CONCENTRATION - 10 YEAR
SUB -BASIN
DATA
INITIAL /OVERLAND
TIME(13)
TRAVEL TIME / GUTTER OR CHANNEL FLOW
(tt)
to CHECK
(URBANIZED BASIN)
FINAL
to
REMARKS
DESIGN
POINT
SUBBASIN(s)
(1)
Area
(ac)
(2)
C
(3)
Length
(11)
(4)
Slope
(%)
(5)
ti
(min)
(6)
Length
(Itl
(71
Slope
(%)
(8)
n
Manning
rough.
Vel.
(fi
(9)
tl
(min)
(10)
to -
ti+It
(11
Total L
(11)
(12)
to-(V180)+10
(min)
(13)
(min)
(14)
Existing
1.94
0.79
40
1.0
3.6
510
1.50
0.016
2.5
3.51
7.0
550
13.1
7.0
Existing Site
Proposed Total
1.94
0.76
40
1.0
3.9
510
1.50
0.016
2.5
3.5
7.3
550
13.1
7.3
Proposed Total Flow
Proposed Central
0.55
0.71
401
1.01
4.5
140
2.20
0.016
3.0
0.8
5.3
180
11.0
5.3
Area Draining to Area Inlets and 12" PVC
EQUATIONS:
tc=ti+tt
ti=[1.87(1.1-CC,)L0.5)/S"3
tt = UVel.
Velocity from Manning's Equation with R=0.1 (corresponds to Figure 3-3 of City of Fort Collins Design Manual)
final tc = minimum of ti + It and urbanized basin check
min. tc = 5 min. due to limits of OF curves
Flow.xls TOC-10
Interwest Consulting Group
1218 West Ash, Suite C
Windsor, Colorado
RUNOFF COEFFICIENTS & % IMPERVIOUS
LOCATION: RAM CROSSING K2
PROJECT NO: 1144-069-01
COMPUTATIONS BY: MPO
DATE: 1 1 /2/201 1
Recommended Runoff Coefficients from Table 33 of City of Fort Collins Design Criteria
Recommended % Impervious from Urban Storm Drainage Criteria Manual
Streets, parking lots (asphalt):
Concrete:
Roofs:
Gravel:
Lawns (flat <2%, heavy soil):
Runoff
coefficient
C
%,
Impervious
0.95
100
0.95
96
0.95
90
0.50
40
0.20
0
NOTE - All impervious was lumped into this category.
SUBBASIN
DESIGNATION
TOTAL
AREA
(ac.)
TOTAL
AREA
(sq.ft)
PAVED
AREA
(sq.ft)
CONCRETE
AREA
(sq.ft)
ROOF
AREA
(sq.10
GRAVEL
AREA
(sq.ft)
LANDSCAPE
AREA
(sq.ft)
RUNOFF
COEFF.
ID)
%
Impervious
REMARKS
Existing
1.94
84,460
66,100
0
0
0
18,360
0.79
78
Existing Site
Proposed Total
1.94
84,460
63,000
0
0
0
21,460
0.76
75
Proposed Total Flow
Proposed Central
0.55
24.000
16.200
0
0
0
7,800
0.71
68
Area Draining to Area Inlets and 12" PVC
EDuations
- Calculated C coefficients & % Impervious are area weighted
C=£(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.xls Cval
■ /�/rw�iiiwriwwsivisow�ij_w�%/%�
�imns� �nm�
n
No Text
Mr. Wes Lamarque
November 3, 2011
Page 2 of 2
there is not an opportunity to install an underdrain, but smaller storms will be slowed and
allowed to infiltrate in this area. Once the filter area is overwhelmed, the stormwater will
overtop the sump and flow to the northeast as it does today.
The existing and proposed imperviousness of the lot was compared as a part of this study.
Exhibits are attached which show that the existing imperviousness is 78% while the proposed
improvements will lower the imperviousness to 75%. This is mostly due to the required 5' offset
on the north and east from the property line to the proposed parking. Because the impervious
area will decrease with this project, detention is not required. Attached is a summary of the
flows for the existing and the proposed site. With the reduction of impervious area by 3%, the
100-year flow off the site is reduced by 8%.
The proposed 12" PVC storm system is the only hydraulic system on the project. Our
calculations show a 100 year flow to this system of 4.8 cfs. The systems is a series of small
sumps and overtops to the east and west prior to reaching the existing or proposed building
finished floors. We have verified that the system can convey the 100-year flow, with the
safeguard the overtopping occurs below the finished floors.
This area has previously been studied in a master drainage plan for the CSU campus by Ayers
Associates and is included in the Braiden Hall Basin. All possible measures have been taken to
provide water quality for the site through the proposed grass swale and sand filter and the
lengthening of flow paths from existing conditions. The proposed expansions and improvements
have been designed with provisions for safe and efficient control of stormwater runoff in a
manner that will not adversely affect the downstream detention system and will improve water
quality for the Ram Crossing K2 project. Overall, it is evident that the proposed revisions will
have a positive impact on the proposed stormwater management system.
We appreciate your time and consideration in reviewing this submittal. If you have any
questions or need additional information please feel free to call at any time (970) 674-3300 Ext.
102.
Sincerely,
Michael Oberlander, P.E.
Colorado Professional Engineer 34288
Interwest Consulting Group
Attachments
INTERWEST IM C O N 5 U L T I N G G R O U P
November 3, 2011
Mr. Wes Lamarque
City of Fort Collins
Stormwater Utility
700 Wood Street
Fort Collins, CO 80522
Re: Ram Crossing K2 — Storm Drainage Report
Dear Wes,
We are pleased to submit for your review and approval this drainage letter showing the drainage
impacts from the proposed expansion and improvements to the Ram Crossing K2.
The project is located at 914 West Lake Street and is a part of Lots 12 and 13 of College Heights
Addition. The site currently has an existing apartment complex and large asphalt parking lot on
the site. The project will expand the building, reconfigure and significantly reduce the parking
area, and provide for stormwater quality improvements. The area of the site that will be
improved is approximately one acre.
The site is surrounded by Colorado State University campus and is bounded on the south by
Lake Street. There are no offsite flows entering the site. Today, the entire site sheet flows north
and east.to the northeast comer of the site. With the building addition and reconfiguration, all
water will still flow to the north and east, but around the new building in swales and in a small
storm pipe system (lengthening several of the existing flow paths). Please refer to the attached
erosion control plan.
The site is required to provide water quality treatment, but there is no adjacent storm sewer
available near the site and it must flow overland in the northeast corner. Because of the lack of
an adjacent, below grade outfall, it is not feasible to install a standard water quality pond.
Today, there is no treatment as stormwater leaves the asphalt parking and the site (the asphalt is
on the existing property lines). In an effort to improve the stormwater quality, swales have been
added on the west and north sides of the site. The swale on the west is at slightly more than 2%
and the swale on the north is consistently at 1 %. We propose that neither Swale have a trickle
pan in an effort to encourage infiltration. The swale on the north is easily maintained and over
20 feet from the proposed building, so we are not concerned about encouraging infiltration here.
At the northeast corner of the site, we propose a modified "sand filter" with a 10'x20' area being
lowered approximately 6" below the existing grade with 12" of cobble on 24" of sand. Again,
1218 WEST ASH, SUITE C WINDSOR, COLORADO 80550
TES. 970.674.3300 id%. 970.674.3303