HomeMy WebLinkAboutTRAFFIC OPERATIONS FACILITY PDP - 30 91E - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTI
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W�SEAR.BRO�WN
November 20, 2001
Mr. Basil Hamdan
City of Ft. Collins
Stormwater Utility Department
700 Wood Street
Ft. Collins, Colorado 80521
ARCHITECTURE
ENGINEr:RING
PLANNING
CONSTRUCTION
209 South Meldrum
Fort Collins„ CO 80521
970.482.5922 phone
970.482.6368 fax
www.searbrown.com
RE: Final Drainage & Erosion Control for the East Vine Streets Lot 5A Traffic
Operations Facility, Ft. Collins, Colorado
Dear Basil:
We are pleased to submit for your review and approval this Drainage and Erosion
Control Report for the East Vine Street Lot 5A Traffic Operations Facility. All
computations within this report have been completed in accordance with the City of
Ft. Collins Storm Drainage Design Criteria Manual.
We appreciate your time and consideration in reviewing this submittal. Feel free to
call if you have questions regarding the analysis performed or findings of this study.
Respectfully,
The Sear -Brown Group
Prepared by:
Stanley E. Dunn, P.E.
Project Engineer
cc: File 183-050
Vaught -Fry
I
' Section 4
Water Quality & Erosion Control
4.1 Water Quality
' Water quality for Lot 5A will be provided via existing Water Quality Ponds A and B,
located on the east side of Lot 1. Lot 5A surface runoff will be discharged to these
ponds in accordance with the Phase One Final Report (Sear Brown, 1993). In
accordance with that study and the existing ponds, first flush of debris, oils and
highway snow removal chemicals. The water quality ponds will have a 40-hour
' release period into respective detention ponds effectively providing filtration via
natural vegetative and absorbtion factors.
4.2 Erosion Control
This development lies within the Moderate Rainfall Erodibility and Moderate Wind
Erodibility Zones per City meteorologic zone map. The Erosion Control Performance
(PS) and Effectiveness (EFF) during construction were computed to be 80 percent
' and 95 percent, respectively. Post -Construction PS and EFF were estimated to be 94
percent and 99 percent, respectively.
' Post overlot grading conditions will require that all disturbed areas not in a roadway,
paved area or greenbelt will have temporary vegetation seed applied. Applied seed
' will be covered with hay or straw mulch at a rate of 2 ton/acre, and mulch will be
adequately tacked or cripped into the soil.
' Areas to be paved must have a 1-inch layer of gravel mulch, applied at a rate of 135
tons/acre immediately after overlot grading is complete. Pavement should be applied
as soon as possible and after Site utilities have been installed. Disturbed areas
_ _(including the south parking area) will not to be built on within one year must have
permanent seed applied at 2 tons/acre and adequately mixed with'topsoil material
' All construction activities must comply with State of Colorado permitting process for
Stormwater Discharge Associated with Construction Activity. If at any time during
t construction, groundwater is encountered, a Colorado Department of Health NPDES
permit will be required, and must be secured by the Contractor.
' M:VOBSXI93-05OWacsTinal 6
Drainage Report_I 12001 doc SEAR •BROW N
' Section 5
Conclusions
' 5.1 Compliance with Standards
' Computations included in this Final Drainage & Erosion Control Report are in
compliance with the City of Ft. Collins Erosion Control Manual for Construction
' Sites and Storm Drainage Criteria Manual. Surface runoff discharged from Lot 5A is
in conformance with previous studies. The Site is not situated within any floodplains
or drainageway that might impact on -site or off -site facilities, or result in damages as
' a result of stormwater inundation.
5.2 Site Development
The Site will be operated and maintained as a facility that serves City traffic
operations. The City will maintain landscaping and storm drainage facilities. Under
' the proposed development plan, the Site will be occupied on the west by the main
office structure, the north by a garage structure and on the south by parking area.
.5.3 Drainage Concept
' The proposed drainage plan is in conformance with City criteria, and will adequately
convey storm runoff from Lot 5A to existing outfall points (Water Quality and
Detention Ponds A & B). Discharge rates to these outfall points will be in
conformance with previous studies. Both 2-Year and 100-year runoff will be
conveyed via open -channel and storm sewer systems. No adverse impact to existing
properties or connecting storm conveyance systems is anticipated.
5.4 Stormwater Quality Concept
__Water quality for Lot 5A will be provided via existing Water-Quality-Ponds-A-and.B,_-- --
located east of the subject property (Lot 1). Stormwater pollutants will be filtered
' prior to discharge into respective detention ponds, also located east of the Site (Lot 1).
5.5 Erosion Control Concept
Proposed erosion control measures will mitigate erosion due to wind or rainfall.
' Erosion control measures will be installed and maintained from start of construction
to final landscaping. Performance and Effective Standards meet City requirements.
' M:VOBS\18J-O50\dm\Final N 7
Drainage R"°rt_I 12001 doc SEAR BROW
1
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' MAJOBS\IgJ-OSO�docs�Final
Drainage Repori_112001.dac
1
References
1. Final Drainage & Erosion Control Study, East Vine Streets Facility P.U.D.,
Major Amended Final, Phase Two Final, Ft. Collins, Colorado, Sear -Brown,
August 1999.
2. Final Report, Hydrologic Model Update for the Lower Dry Creek Basin
Master Drainage Plan, Lidstone & Anderson, September 10, 1997.
3. Flood Insurance Rate Map Panel No. 080102-0002B, FEMA, February 1984.
4. Final Drainage & Erosion Control Study for the East Vine Streets Facility
P.U.D., Phase One Final, RBD, March 1993.
5. Storm Drainage Design Criteria & Construction Standards, City of Ft. Collins,
May 2984 (Rev. 1/97).
6. Erosion Control Reference Manual for Construction Sites, City of Ft. Collins,
January 1991.
II SEAR•BROWN
0
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CHARTS, TABLES & FIGURES
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DRAINAGE CRITERIA MANUAL
50
30
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P-
RUNOFF
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.2 .3 .5 1 1 1:5 2 3 5 10 20
VELOCITY IN FEET PER SECOND
Figure 3-3 ESTIMATE OF AVERAGE FLOW VELOCITY FOR
USE WITH THE RATIONAL FORMULA.
MOST FREQUENTLY OCCURRING °UNDEVELOPED°
LAND SURFACES IN THE DENVER REGION.
REFERENCE:: Urban Hydrology For Small Watersheds'
Technical Release No. 55, USDA, SCS Jan. 1975.
5-1-84
URBAN DRAINAGE & FLOOD CONTROL DISTRICT
Table 3-3
'
RATIONAL METHOD rMNOFF COEFFICIENTS FOR COMPOSITE ANALYSIS
Character of Surface Runoff Coefficient
'
Asphalt.. ..0.95
Streets, Parking Lots,Drives:..•.••.....
Concrete.. . ..• 0.95
Gravel ....................................... 0.50
'
Roofs .......................................... 0.95
Lawns, Sandy Soil:
Flat<28..0.1
Average 2 to 7$. 0.15
...................................
Steep >78. 0.20
'
Lawns, Heavy Soil -
Flat <2%. 0.20
Average 2 to 7%............................ . 0.25
Steep>78..................................... 0.35
'
3.1.7 Time of Concentration
In order to use the Rainfall Intensity Duration Curve, the time of
concentration must be known. The time of concentration, T,, represents the
time for water to flow from the most remote part of the drainage basin under
consideration to the design point under consideration. The time of
concentration can be represented by the following equation.
Tc = too + t,
Where:
T, = Time of Concentration, minutes
t„ = overland flow time, minutes
t, = travel time in the gutter, swale, or storm sewer, minutes
The overland flow time, t,,, ,can be determined either by the following equation
or the "Overland Time of Flow Curves" from the Urban Storm Drainage Criteria
Manual, included in this report (See Figure 3-2).
'
L87(7.1-CCf)D112
TOV Sl/3
'�—
- Where: T„ = Overland _Flow Time of Concentration, minutes
S = Slope, 8 - -
C = Rational Method Runoff Coefficient
'
D = Length of Overland Flow, feet'(500' maximum)
CL = Frequency Adjustment Factor
The travel time, tt, in the gutter, Swale, or storm sewer can be estimated with
'
the help of Figure 3-3.
3.1.8 Adjustment for Infrequent Storms
The preceding variables are based on the initial storm, that is, the two to ten
year storms. For storms with higher intensities an adjustment of the runoff
coefficient is required because of the lessening amount of infiltration,
depression retention, and other losses that have a proportionally smaller
' effect on storm runoff.
These frequency adjustment factors are found in Table 3-4.
May 1984 Design Criteria
Revised January 1997
' 3-5
4
Table 3-4
r
7
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11
RATIONAL METHOD FREQUENCY ADJUSTMENT FACTORS
Storm Return Period Frequency Factor
(years) Cr
2 to 10 1.00
11 to 25 1.10
26 to 50 1.20
51 to 100 1.25
Note: The product of C times CL shall not exceed 1.00
3.2 Analysis Methodology
The methods presented in this section for use in the determination of runoff at
specific design points in the drainage system are currently under review by the
Stormwater Utility. Until detailed criteria for hydrologic modeling are developed, the
accepted methods for hydrologic analysis are (1) the Rational Method and (2) UDSWM2-
PC. The Stormwater Utility shall determine circumstances requiring computer modeling
with UDSWM2-PC. Early contact with the Stormwater Utility is encouraged for the
determination of the appropriate method. Where applicable, drainage systems proposed
for construction should provide the minimum protection as determined by the methodology
so mentioned above.
3.2.1 Rational Method
The Rational Method is recommended only for sites less than 5 acres. The runoff
may be calculated by the Rational Method, which is essentially the following
equation:
IQ = C=CIA
Where Q - Flow Quantity, cfs
' A = Total Area of Basin, acres
C;= Storm Frequency Adjustment Factor (See Section 3.1.8)
C = Runoff Coefficient (See Section 3.1.6)
I = Rainfall Intensity, inches per hour (See Section 3.1.4)
3.2.2 UDSWM2-PC
For circumstances requiring computer modeling, the design storm hydrographs
shall be determined using UDSWM2-PC. Basin and conveyance element parameters
shall be developed from the physical characteristics of the development. Refer
to the UDSWM2-PC User's Manual' for modeling methodology and development.
..`Urban Drainage and Flood Control District, March 1985
' 3.2.2.1 Surface Storage and Infiltration
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Table 3-5 gives those values for surface storage for pervious and
impervious surfaces. Table 3-6 gives the infiltration rates to be used
with UDSWM2-PC.
Table 3-5
VALUES FOR SURFACE STORAGE
(A11 Values in Inches)
(For Use with UDSWM2-PC)
Impervious Areas .................. .100
PerviousAreas .................... .300
May 1984
Revised January 1997
Design Criteria
00I
3-6
I, Stanley E. Dunn, a registered professional engineer in the State of Colorado, hereby
certify that the information presented in this report was prepared by me or was
prepared under my direct supervision for the Owner(s) thereof.
Stanley E. Dunn, Colorado P.E. 33827
SEAR• BROWN
Project: . r- SAProject No. it3-05--o
'By: Checked:
Date: 11/1 // Sheet of
Prgect Traffic ONrmloneSUaet FaCIIIN
P.Igmt Na: ttl-050
Rumps weuMHaN
2 Yw storm C (PANNius) • 0.25
2 Year Storm C tlmo iguez) • 0.95
Cl 1
SUB-6VIN
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INITLWOVERLANO
TIME ILI
TRAVEL TIME
ILI
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II IRR4N.,Pn R461NR1
Total
I.
FINAL
I.
DESIG:
1
Twel Ar
(ac)
2
Impervious
pa)
3
Compeelte
Cr
4
LENGTH
(feet)
5
SLOPE
(in)
a
4
Iminl
)
LENGTH
(leetl
e
SLOPE
1%)
9
Y
VELOCITY
0P•I
10
I.
(min)
11
TOTAL LENGTH
(INI)
12
G•IU1601.10
(min)
10
(min)
14
(min)
is
REMARKS
IuN)
to
G-11
0.15 1
0w
ow
is
0218
15
18
1010
18
So
Tot" 4ft. 199E Repo"
0.21
0.21 1
0Go
0.25
20
0175
2.7
20
1011
27
So
Total I. from 1999 Report
0.31
0.53 1
0.00
0.25
14
0071
3.1
1247
0.50%
1.09
19.1
1251
11,01
222
1).0
T0te,4 tram 199E Report
O
0.13 1
000
0.25
330
0004
386
3w
11,83
30.E
11.8
To1al40onimlieport
G.51
Ott 1
0.00
025
275
0005
27.9
275
11.5J
27.9
11.5
TOtal40om1699Repprl
G-ol
Ott I
ow
0.25
285
0000
351
20
11.58
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11A
T0tal40am1999Rsporl
A-11
I IS 1
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7.1
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7.3
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1.40
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0.50%
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t2.G0
19.0
12.0
ipt"41rom 1999 Report
H-2
0.S6
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41
210
G.SG%
1.04
2A
240
1133
6J
6i
Total 41rom 1999 ReportH-3
048
048
002)0
O50%
1,U
34
2i0
11.w
34
50
Total 4 eam 199E Report
02i
011
0.5434
42
280
050%
1.]4
32
295
t1"
2.4
T4
Total 41rom INS Report
Iv5
1.5)
16T
0.as10i5
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1A0
128
10i5
159)
12.8
128
Total 48om 19B9 Report
ftme
0a
0.00
025014
15.1
140
O50%
I'M
2.1
200
11.55
16.6
11.6
Total 41rom 1999 Repoli
IN YNr Storm C 1Pervioual • 0.31
IN Yw stme t C llmp r'dou•l • 1.00
1 1.25
U&BASIN
DATA
INITIAUOVERLAND
TIME 141
TRAVEL TIME
ILI
I, CHECK
IIIRR4NMFn R4RINRt
Total
4
FINAL
Ik
OESIG:
1
Toilet AIN
(KI
2
Impendaw
IKI
3
C9mpasite
Crm
4
LENGTH
IINq
5
SLOPE
O/R
6
G
Iminl
)
LENGTH
Ifeal)
e
SLOPE
1%)
9
VELOCITY
Owl
10
G
(min)
11
TOTALLENGTH
(feet)
12
4•IUINIMI0
(mini
13
(mini
14
Iminl
15
REMARKS
IuN)
16
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0,15
0.05
0.63
18
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1.2
18
10.10
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0.2
0.21
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0.175
2.5
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10.11
2.5
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Tale! 4 ran, INS Ri l
0.3
0.54
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0.31
14
0.0714
2.9
1247
0.50%
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1907
1251
17.01
21.9
17.0
Tol" G noun 1999 ftW
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O.5
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0.11
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0.31
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330
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330
275
li.w
11,53
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25.9
It's
115
Twel 4 more 1999 Report
Total I, from INS NW
0.5
0,11
0.00
0.31
285
0. W35
]5.3
285
11.58
35,3
116
Total I, mon, INS Repp0
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1 BS
1.)1
1.13
7.1
From Muller EW R
A-2
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6.1
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10 19
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5.0
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200%
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Lot 48
462
1.55
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250
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495
12.75
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5.3
Lot 48
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180
1.30
370
12.0E
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5.0
Lot 48
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-0.255--'-'0.T9'
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Lot SA-1
1.22
0.40e6a657
0.60
200
0.5
sA
1N
O.Bo%
IN
2.91
320
12.17
6.5
Lot SA-2-�-'��-�
1.54
Song
0.00
300
0.5
6,5
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0.40%
430
12.30
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6.9
Lot SAa
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140
30
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139ffi220o
1.2
1.3d
1.34
274
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no
240
1200
11.33
11
38
12a
5o
Told tc"m 1990 Re0an
Tot"40amlowilaw
048
048
1.110
TU
3.36
2i0
11.w
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Tote, 4 ham INS Raw"I
02i
0113432
1U
323
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11.84
84
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Tote, t.Irom 1999 RiNn
15i
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1.81
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1.W
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155
140
IN
12.SO
2.14
1075
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t2.0
11.6
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11.6
Totalpfrom 199E Mpon
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SUMMARY OF HYROLOGIC PARAMETERS
Existing Conditions
Basin
ID
Area
(acres)
C
2yr
C
100yr
5X-1
0.51
0.60
0.75
5X-2
1.22
0.48
0.60
5X-3
1.54
0.26
0.33
PEAK DISCHARGE SUMMARY TABLE
Existing Conditions
Basin
ID
Area
(acres)
Q2rR
(cfs)
Q100YR
(cfs)
5X-1
0.51
0.9
3.8
DP1
-
0.9
3.8
5X-2
1.22
1.5
6.7
DP2
1.5
6.7
5X-3
1.54
0.9
4.5
DP3
2.4
11.2
I
I
1
1
1
1
PROPOSED CONDITIONS
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I
I
1
SEAR•BROWN
Oe
Project: Lor-
S�
By :�
Date:
1
Project No. i83-oSo
Checked: -
Sheet — of=
-p% Z A/o 2T✓1
A
e
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nP
A
si!'Z
o�•r'rltnu�
SF .I
G.alJ
ar
SA-3
77T3
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�2[0°
/iJt rf
D6
<4-
SUMMARY OF HYROLOGIC PARAMETERS
Proposed Development
Basin
ID
Area
(acres)
c
2yr
C
100yr
5A-1
0.79
0.62
0.78
5A-2
0.24
0.51
0.64
5A-3
0.91
0.27
0.33
5A-4
1.39
0.48
0.60
PEAK DISCHARGE SUMMARY TABLE
Proposed Development
Basin
ID
Area
(acres)
02YR
(cfs)
4100YR
(cfs)
5A-1
0.79
1.3
5.8
DPI
1.3
5.8
5A-2
0.24
0.3
1.4
DP2
0.3
1 1.4
5A-3
0.91
1 0.7
1 3.0
DP3
1 0.7
3.0
5A-4
1.39
1.7
7.6
DP4
3.6
16.0
IJ
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1J
praie Tissa. Ol«rntlocuStleet Facllth,
Prolact No: 1a 50
RuncN Calculntlone
2 Ywr Stom1 C IPnrviouel - 015
2 Year Stamm C 11mPrviotsl - 0.25
1
SuBEIASIN
INITIALIOVE11I
TRAVEL TIME
t, CHECK
Total
FINAL
NATA
TIME ILI I
ILI
IIIRRANI]FH RAYINR,
4
4
DESIO: Twl Arw Vnperviwa Co ,"W
LENGTH SLOPE L
LENGTH SLOPE VELOCITY L
TOTALLENOTH 4-plaol•to
0.EMARK3
Ind lacl Co
I1«tl Pnl Iminl
Itwtl I%1 11pn1 Iminl
Ifwtl (min)
Iminl
Iminl
luwl
1 2 3 4
5 e T
e 9 10 11
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'
Table of Contents
Tableof Contents.........................................................................................i
Section 1
General Location and Description................................................................1
1.1 Location..............................................................................................1
1.2 General Project & Property Description.............................................1
1.3 Site Soils Information.........................................................................1
1.4 Groundwater......................................................................................2
Section 2
'
Drainage Design Criteria..............................................................................3
2.1 Regulations........................................................................................3
2.2 Hydrologic Design Criteria.................................................................3
'
2.3 Hydraulic Design Criteria...................................................................3
2.4 On -Site Detention..............................................................................3
2.5 Variances From Criteria.....................................................................3
Section 3
Drainage Basins & Proposed Design...........................................................4
3.1 Major Basin Description.....................................................................4
3.2 Existing Sub -basin Description..........................................................4
'
3.3 Proposed Sub -basin Descrption & Design.........................................4
Section 4
Water Quality & Erosion Control...................................................................6
'
4.1 Water Quality.....................................................................................6
4.2 Erosion Control..................................................................................6
-Section-5— - -
Conclusions..................................................................................................7
5.1 Compliance with Standards...............................................................7
5.2 Site Development..............................................................................7
5.3 Drainage Concept..............................................................................7
'
5.4 Stormwater Quality Concept..............................................................7
5.5 Erosion Control Concept
....................................................................7
'
References...................................................................................................8
'
ANOWI87-0501dooTinal
Drainage Report_I 12001 dm
W S E A R. B ROW N
]
S.aL.,.tK
iKur rI
JWYv n
I
7
1
Sul
d
1
1
1
1
1
INLET & STORM DRAIN SYSTEM
SEAR•BROWN
O SJGznvc":.
Project: Ale, f e GlOT
By: Cic
Date •
r 7
ato., � / �/CrfS
Project No. l i3 - a 5 o
Checked:
Sheet of
Vt /= �o n y� (� T�c-PT< �ia-�-G'r/ �.c77ev✓ j'ortTr�
«S
/"n.u�C.zrr is
Worksheet
Worksheet for Trapezoidal Channel
Project Description
Worksheet
North Swale
Flow Element
Trapezoidal Channe
Method
Manning's Formula
Solve For
Channel Depth
Input Data
Mannings Coefficient
0.030
Slope
0.005000 ft/ft
Left Side Slope
6.00 H : V
Right Side Slope
6.00 H : V
Bottom Width
4.00 ft
Discharge
1.40 ds C Q i o0
Results
Depth
0.23 ft
Flow Area
1.2 ft'
Wetted Perimeter
6.81 ft
Top Width
6.77 ft
Critical Depth
0.14 ft
Critical Slope
0.026532 ft/ft
Velocity
1.13 ft/s
Velocity Head
0.02 ft
Specific Energy
0.25 ft
Froude Number
0.46
Flow Type
Subcritical
1
1
untitled.fm2
11/19/01 02:51:26 PM
S' I$ S-,& - -I—
Project Engineer: Stanley Dunn
The Sear -Brown Group FlowMaster v6.1 [6141<]
0 Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA (203) 755-1666 Page 1 of 1
Worksheet
Worksheet for Trapezoidal Channel
Project Description
Worksheet
North Swale
Flow Element
Trapezoidal Channe
Method
Manning's Formula
Solve For
Discharge
Input Data
Mannings Coefficient 0.030
Slope
0.005000 ft/ft
Depth
2.50 ft
Left Side Slope
6.00 H : V
Right Side Slope
6.00 H : V
Bottom Width
4.00 ft
Results
Discharge
206.23 cfs
Flow Area
47.5 ft'
Wetted Perimeter
34.41 ft
Top Width
34.00 ft
Critical Depth
2.06 ft
Critical Slope
0.012638 ft/ft
Velocity
4.34 ft/s
Velocity Head
0.29 ft
Specific Energy
2.79 ft
Froude Number
0.65
Flow Type
Subcritical
Project Engineer: Stanley Dunn
unlitled.fm2 The Sear -Brown Group FlowMaster v6.1 [614k]
11/19/01 02:51:54 PM C Haestad Methods, Inc. 37 Brookside Road Waterbury, CT 06708 USA (203) 755-1666 Page 1 of 1
I
1
1
0.7
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0
a 0.3
w
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0
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EXAMPLE
T
0.0 2 I 3 4
0 1
FLOW INTO INLET PER SO. FT. OF OPEN AREA (CFS/FT2)
Figure 5-3 . __
CAPACITY OF GRATED INLET IN SUMP
(From: Wright -McLaughlin Engineers, 1969)
MAY 19134
5-11
DESIGN CRITERIA
II ;III II,: III
sllqit
'
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1
I
L
STORM SEWER SYSTEM DESIGN USING UDSEWER MODEL
Developed by Civil Eng. Dept, U. of Colorado at Denver
Metro Denver Cities/Counties 8 UDFCD Pool Fund Study
-----=-----------------------------------------------------------
USER:RDB-Fort Collins -Colorado ...............................................
ON DATA 06-28-1999 AT TIME 15:15:37 VERSION=01-17-1997
*** PROJECT TITLE :Fort Collins Streets Facility - Storm Sewer
*** RETURN PERIOD OF FLOOD IS 2 YEARS - The 1993 phase of design used the 2-year event to size the storm
sewer. The same methodology is continued in this analysis of the
entire storm sewer system.
(Design flow hydrology not calculated using UDSEWER)
*** SUMMARY OF HYDRAULICS AT MANHOLES
------------------------------------- ....
MANHOLE CNTRBTING RAINFALL RAINFALL DESIGN GROUND WATER COMMENTS
ID NUMBER AREA * C DURATION INTENSITY PEAK FLOW ELEVATION ELEVATION
MINUTES INCH/HR CFS FEET FEET
-------------------------------------------------------------------------------
10.00 19.40 50.00 47.00 OK
20.00 19.00 50.50 48.08 OK
30.00 19.00 51.50 48.47 OK
40.00 17.90 52.15 49.50 OK
50.00 14.40 52.53 50.22 OK
60.00 12.90 52.50 50.55 OK
70.00 12.90 52.50 50.57 OK
80.00 8.46 54.00 50.84 OK - Q2 is less than 1993 report.
90.00 � 6.39 55.15 51.43 OK
95.00 1.45 50.54 51.44 NO
55.00 3.50 51.50 50.78 OK
56.00 3.50 51.50 50.94 OK
45.00 3.50 51.70 49.91 OK
46.00 3.50 51.70 50.08 OK
35.00 1.30 48.32 48.94 NO
36.00 1.30 48.32 48.95 NO
OK MEANS WATER ELEVATION IS LOWER THAN GROUND ELEVATION
*** SUMMARY OF SEWER HYDRAULICS
'
NOTE:
SEWER
THE GIVEN
MAMHOLE
FLOW DEPTH_TO_SEWER SIZE RATIO= 1
NUMBER SEWER REQUIRED SUGGESTED
EXISTING
ID NUMBER
UPSTREAM
DNSTREAM
SHAPE
DIA(RISE)
DIA(RISE)
DIA(RISE)
WIDTH
ID NO.
ID NO.
(IN) (FT)
(IN) (FT)
(IN) (FT)
(FT)
------ -1---00 ------2
.8
20.00 ---------1--.0.00
R------R OUND -----_----
2'-9.3--------
--
30.00--------
300--..00---------
0-.00--
2.00
30.00
20.00
ROUND
29.38
30.00
30.00
0.00
3.00
35.00
30.00
ROUND
11.12
15.00
12.00
0.00
4.00
40.00
30.00
ROUND
28.73
30.00
30.00
0.00
5.00
45.00
40.00
ROUND
14.16
• 15.00
15.00
0.00
6.00
50.00
40.00
ROUND
26.48
27.00
30.00
0.00
7.00
55.00
50.00
ROUND
14.16
15.00
15.00
0.00
8.00
60.00
50.00
ROUND
25.41
27.00
30.00
0.00
1
9.00
10.00
70.00
80.00
60.00
70.00
ROUND
ROUND
25.41
21.69
27.00
24.00
30.00
24.00
0.00
0.00
11.00
90.00
80.00
ROUND
19.53
21.00
24.00
0.00
12.00
95.00
90.00
ROUND
11.20
15.00
15.00
0.00
13.00
36.00
35.00
ROUND
11.12
15.00
12.00
0.00
'
14.00
46.00
45.00
ROUND
14.16
15.00
15.00
0.00
15.00
56.00
55.00
ROUND
14.16
15.00
15.00
0.00
DIMENSION UNITS FOR ROUND AND ARCH SEWER ARE IN INCHES
DIMENSION UNITS FOR BOX SEWER ARE IN FEET
REQUIRED DIAMETER WAS DETERMINED BY SEWER HYDRAULIC CAPACITY.
SUGGESTED DIAMETER WAS DETERMINED BY COMMERCIALLY AVAILABLE SIZE.
FOR A NEW SEWER, FLOW WAS ANALYZED BY THE SUGGESTED SEWER SIZE; OTHERWISE,
' EXISITNG SIZE WAS USED
I
1
--------------------------------------------------------•----------------------
SEWER DESIGN
FLOW
NORMAL
NORAML CRITIC CRITIC
FULL
FROUDE COMMENT
ID FLOW
0
FULL 0
DEPTH
VLCITY
DEPTH VLCITY
VLCITY
NO.
NUMBER
CFS
CFS
FEET
FPS
FEET
FPS
FPS
t
-____-_-_-------••-----------•----•__''---•----•-•--•---------•---•--
1.0
19.0
20.1
1.93
4.67
1.47
6.31
3.87
0.59 V-OK
2.0
19.0
20.1
1.93
4.67
1.47
6.31
3.87
0.59 V-OK
3.0
1.3
1.6
0.69
2.27
0.50
3.34
1.66
0.51 V-LOW
4.0
17.9
20.1
1.83
4.64
1.43
6.16
3.65
0.62 V-OK
'
5.0
3.5
4.1
0.89
3.75
0.75
4.53
2.85
0.73 V-OK
6.0
14.4
20.1
1.56
4.46
1.30
5.59
2.93
0.68 V•OK
7.0
3.5
4.1
0.89
3.75
0.75
4.53
2.85
0.73 V-OK
8.0
12.9
20.1
1.45
4.36
1.24
5.29
2.63
0.70 V-OK
'
9.0
12.9
20.1
1.45
4.36
1.24
5.29
2.63
0.70 V-OK
10.0
8.5
11.1
1.31
3.89
1.05
5.07
2.69
0.64 V-OK
11.0
6.4
11.1
1.09
3.66
0.90
4.65
2.03
0.69 V-OK
12.0
1.5
3.2
0.59
2.53
0.50
3.19
1.18
0.66 V-LOW
'
13.0
1.3
1.6
0.69
2.27
0.50
3.34
1.66
0.51 V-LOW
14.0
3.5
4.1
0.89
3.75
0.75
4.53
2.85
0.73 V-OK
15.0
3.5
4.1
0.89
3.75
0.75
4.53
2.85
0.73 V-OK
'
FROUDE NUMBER=O
INDICATES
THAT A
PRESSURED
FLOW OCCURS
SEWER
SLOPE
INVERT ELEVATION
BURIED
DEPTH
COMMENTS
ID NUMBER
UPSTREAM
DNSTREAM UPSTREAM
DNSTREAM
'
%
(FT)
(FT)
(FT)
(FT)
1.00
0.24
--------------•-----•---------------
46.27
46.00
1.73
1.50
OK
2.00
0.24
46.57
46.30
2.43
1.70
OK
3.00
0.20
46.72
46.60
0.60
3.90
NO
'
4.00
0.24
47.42
46.60
2.23
2.40
OK
5.00
0.40
47.51
47.45
2.94
3.45
OK
6.00
0.24
48.41
47.45
1.62
2.20
OK
7.00
0.40
48.73
48.45
1.52
2.83
OK
8.00
0.24
48.84
48.45
1.16
1.58
OK
9.00
0.24
48.90
48.88
1.10
1.12
OK
10.00
0.24
49.40
48.95
2.60
1.55
OK
11.00
0.24
50.34
49.55
2.81
2.45
OK
12.CO
0.24
50.54
50.49
-1.25
3.41
NO
'
13.00
0.20
46.72
46.72
0.60
0.60
NO
14.00
0.40
47.51
47.51
2.94
2.94
OK
15.00
0.40
48.73
48.73
1.52
1.52
OK
'
OK MEANS BURIED
DEPTH IS
GREATER
THAN REQUIRED SOIL
COVER OF 1
FEET
*** SUMMARY OF
HYDRAULIC
GRADIENT
LINE ALONG SEWERS
------•----••---------------------- -•• ------
SEWER SEWER SURCHARGED CROWN ELEVATION WATER ELEVATION FLOW
ID NUMBER LENGTH LENGTH UPSTREAM DNSTREAM UPSTREAM DNSTREAM CONDITION
FEET FEET FEET FEET FEET FEET
------------------------------------------------------------------------------
1.00 112.00 0.00 48.77 48.50 48.08 47.00 SUBCR
2.00 114.00 0.00 49.07 48.80 48.47 48.08 SUBCR
3.00 60.00 60.00 47.72 47.60 48.94 48.47 PRSS'ED
4.00 340.00 0.00 49.92 49.10 49.50 48.47 SUBCR
5.00 15.00 15.00 48.76 48.70 49.91 49.50 PRSS'ED
6.00 400.00 0.00 50.91 49.95 50.22 49.50 SUBCR'
7.00 71.00 71.00 49.98 49.70 50.78 50.22 PRSS'ED
8.00 161.00 0.00 51.34 50.95 50.55 50.22 SUBCR
9.00 8.00 0.00 51.40 51.38 50.57 50.55 SUBCR
10.00 187.00 0.00 51.40 50.95 50.84 50.57 SUBCR
11.00 329.21 0.00 52.34 51.55 51.43 50.84 SUBCR
12.00 20.00 0.00 51.79 51.74 51.44 51.43 SUBCR
13.00 0.10 0.10 47.72 47.72 48.95 48.94 PRSS'ED
14.00 0.10 0.10 48.76 48.76 50.08 49.91 PRSS'ED
15.00 0.10 0.10 49.98 49.98 50.94 50.78 PRSS'ED
' PRSS'ED=PRESSURED FLOW; JUMP=POSSIBLE HYDRAULIC JUMP; SUBCR=SUBCRITICAL FLOW
Table of Contents
Appendices
VicinityMap..............................:......................................:...:............Al
Charts, Tables & Figures..................................................................A2
ExistingConditions...........................................................................A3
Proposed Conditions........................................................................A4
ErosionControl.................................................................................A5
' Mainage cpom_112001 m
Drainage Report � dms\Fa« SEAR -BROWN
ff
1
' *** SUMMARY OF ENERGY GRADIENT LINE ALONG SEVERS
UPST MANHOLE SEWER
JUNCTURE
LOSSES
DOWNST MANHOLE
'
SEWER
MANHOLE
ENERGY FRCTION
BEND
BEND LATERAL
LATERAL
MANHOLE
ENERGY
ID NO
ID NO. ELEV FT
FT
K COEF LOSS FT K
COEF LOSS FT
ID
FT
-------------------------------------------------------------------------------
1.0
20.00
48.45
1.45
1.00
0.00
0.00
0.00
10.00
47.00
'
2.0
30.00
48.84
0.30
0.38
0.09
0.00
0.00
20.00
48.45
3.0
35.00
48.98
0.08
1.33
0.06
0.00
0.00
30.00
48.84
4.0
40.00
49.83
0.75
0.25
0.05
0.25
0.18
30.00
48.84
5.0
45.00
50.04
0.04
1.33
0.17
0.00
0.00
40.00
49.83
6.0
50.00
50.53
0.49
0.25
0.03
0.25
0.17
40.00
49.83
'
7.0
55.00
50.90
0.21
1.33
0.17
0.00
0.00
50.00
50.53
8.0
60.00
50.80
0.14.
0.25
0.03
0.25
0.11
50.00
50.53
9.0
70.00
50.80
0.00
0.05
0.01
0.00
0.00
60.00
50.80
10.0
80.00
51.03
0.23
0.05
0.01
0.00
0.00
70.00
50.80
'
11.0
90.00
51.64
0.61
0.05
0.00
0.00
0.00
80.00
51.03
12.0
95.00
51.48
0.00
0.05
0.00
0.00
0.00
90.00
51.64
13.0
36.00
48.99
0.00
0.25
0.01
0.00
0.00
35.00
48.98
14.0
46.00
50.21
0.00
1.33
0.17
0.00
0.00
45.00
50.04
15.0
56.00
51.07
0.00
1.33
0.17
0.00
0.00
55.00
50.90
BEND
LOSS =BEND
K* FLOWING FULL
VHEAD
IN SEWER.
LATERAL LOSS=
OUTFLOW
FULL VHEAD-JCT
LOSS K*INFLOW FULL
VHEAD
FRICTION
LOSS=O MEANS
IT IS NEGLIGIBLE
OR POSSIBLE ERROR
DUE
TO JUMP.
'
FRICTION
LOSS
INCLUDES
SEWER INVERT
DROP AT MANHOLE
NOTICE:
VHEAD
DENOTES
THE VELOCITY HEAD OF FULL
FLOW CONDITION.
A MINIMUM
JUCTION
LOSS
OF 0.05
FT WOULD
BE INTRODUCED
UNLESS
LATERAL K=O.
FRICTION
LOSS
WAS ESTIMATED
BY
BACKWATER
CURVE COMPUTATIONS.
'
I
I
L
WATER QUALITY & STORMWATER
DETENTION
' (From Previous Studies)
Fort Collins Streets Facility
Comoosite Rational Method Runoff Coefficient for Detention Pond
Designer: SLG
183-047
(Fort Collins)
Basin lArea ac
C
Area • C
Notes
From 1993 Report:
C 2.27
0.95
2.16
'
D 1.23
0.95
1.17
E 2.49
0.95
2.37
'
F 1.48
0.79
1.17
'
G 0.83
0.48
0.40
'
From Current Report:
0-2 0.21
0.25
0.05
*'
0-3 0.54
0.25
0.14
0-4 0.13
0.25
0.03
0-5 0.11
0.25
0.03
0-6 0.11
0.25
0.03
'*
A-1 1.85
0.90
1.67
From Muller Engineering Report
'
A-2 0.79
0.45
0.36
From Muller Engineering Report
A-3 0.13
0.35
0.05
From Muller Engineering Report
A-5 1.31
0.20
0.26
From Muller Engineering Report
4B-1 1.23
0.95
1.17
4B-2 1.24
0.95
1.18
"
4B-3 0.69
0.95
0.66
"*
H-1 0.93
0.41
0.38
"
H-2 0.66
0.75
0.49
"
H-3 0.48
0.95
0.46
"
H-4 0.27
0.54
0.14
H-5 1.87
0.95
1.78
"
Ponds 8.62
0.25
2.16
This includes 0.18 ac from original 1993 H Basin
Total: 29.47
18.27
0.62
Composite C for Basin (100-yr)• 0.77
'From 1993 Preliminary Drainage, Erosion, and Storm Water Quality
Study for the East Vine Streets Facility P.U.D. Report.
"Basins A, B, 0-2, and H from the 1993 Preliminary Drainage, Erosion, and
Storm Water Quality Study were divided further for development design.
DETENTION
POND SIZING BY FAA METHOD
Developed
by
Civil Eng.
Dept., U.
of Colorado
'
Supported by Denver Metro Cities/Counties Pool Fund Study
Denver Urban Drainage
and Flood Control District, Colorado
-------------------------
USER=Kevin Gingery,____---
.... ......
'
EXECUTED ON 06-28-1999 AT
TIME 13:51:09
PROJECT TITLE: Fort Collins Streets Facility
- Overall Site Detention Pond
DRAINAGE BASIN DESCRIPTION
BASIN ID NUMBER =
1.00
BASIN AREA (acre)= 29.47 -
Comprised of the following contributing basins (exhibit on page 4):
'
Basins from 1993 Report: C. D, E. F. G
Basins from Current Report: 0-2, 0-3, 0-4, 0-5, 0-6. A-1. A-2. A-3,
A-5. 48-1. 48-2. 4B-3. H-1. H-2. H-3.
H-4. H-5. Ponds
'
RUNOFF COEF
- 0.77 -
From previous page
***** DESIGN RAINFALL STATISTICS
DESIGN RETURN PERIOD (YEARS) = 100.00
INTENSITY( iN/HR)-DURATION(MIN)
TABLE IS GIVEN
'
DURATION 5 10 20 30
40 50
60 80 100 120 150 180
INTENSITY 9.0 7.3 5.2 4.2
3.5 3.0
2.6 2.1 1.7 1.5 1.2 1.0
POND OUTFLOW CHARACTERISTICS:
MAXIMUM ALLOWABLE RELEASE
RATE =
10.5 CFS - Historic 02 for Basin E1 (See page 3 for exhibit and
OUTFLOW ADJUSTMENT FACTOR
=
1 page 27 for calculation.
AVERAGE RELEASE RATE
=
10.5 CFS
AVERAGE RELEASE RATE =
MAXIMUM RELEASE RATE * ADJUSTMENT FACTOR.
***** COMPUTATION OF POND SIZE
RAINFALL RAINFALL INFLOW
OUTFLOW
REQUIRED
DURATION INTENSITY VOLUME
VOLUME
STORAGE
MINUTE INCH/HR ACRE -FT
ACRE -FT
ACRE -FT
'
0.00 0.00 0.00
---------------
0.00
0.00
5.00 9.00 1.42
0.07
1.35
10.00 7.30 2.30
0.14
2.16
15.00 6.25 2.95
0.22
2.74
20.00 5.20 3.28
0.29
2.99
25.00 4.70 3.70
0.36
3.34
30.00 4.20 3.97
0.43
3.54
35.00 3.85 4.25
0.51
3.74
40.00 3.50 4.41
0.58
3.83
'
45.00 3.25 4.61
0.65
3.96
50.00 3.00 4.73
0.72
4.00
55.00 2.80 4.85
0.80
4.06
60.00 2.60 4.92
0.87
4.05
65.00 2.47 5.07
0.94
4.13
70.00 2.35 5.18
1.01
4.17
75.00 2.22 5.26
1.08
4.17
80.00 2.10 5.29
1.16
4.14
85.00 2.00 5.36
1.23
4.13
'
90.00 1.90 5.39
1.30
4.09
95.00 1.80 5.39
1.37
4.02
100.00 1.70 5.36
1.45
3.91
'
105.00 1.65 5.46
--------------------------•------•---------
1.52
3.94
THE REQUIRED POND SIZE = 4.17461 ACRE -FT
THE RAINFALL DURATION FOR THE
ABOVE POND
STORAGE= 75 MINUTES
'
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I
Fort Collins Streets Facility
Composite Rational Method Runoff Coefficient for Water Quality Pond A
Designer. SLG
183-047
(Fort Collins)
Basin - I Area (ac) I C
Area' C
Notes
From 1993 Report:
C 2.27
0.95
2.16
D 1.23
0.95
1.17
E 2.49
0.95
2.37
F 1.48
0.79
1.17
G 0.83
0.48
0.40
From Current Report:
A-1 1.85
.0.90
1.67
From Muller Engineering Report
A-2 0.79
6.45
0.36
From Muller Engineering Report
A-5 1.31
6.20
0.26
s7ipm Muller Engineering' '
Report
413-2 1.81
0.95
1.721::
4B-3 0.79
0.95
0.75
Total: 14.851
12.01
Composite C for Basin: 0.81
'From 1993 Preliminary Drainage, Erosion, and Storm Water Quality
Study for the East Vine Streets Facility P.U.D. Report.
"Basins A, B, 0-2, and H from the 1993 Preliminary Drainage, Erosion, and
Storm Water Quality Study were divided further for development design.
�J
DETENTION
POND SIZING BY
FAA METHOD
Developed by
Civil Eng. Dept., U. of
Colorado
'
Supported by Denver Metro Cities/Counties Pool Fund Study
Denver Urban Drainage
and Flood Control District, Colorado
'
------------------------
USER=Kevin Gingery* ...
EXECUTED ON 06-28-1999 AT
TIME 13:54:07
PROJECT TITLE: Fort Collins Streets Facility
- Water Quality Pond A
**** DRAINAGE BASIN DESCRIPTION
BASIN ID NUMBER
= 1.00
BASIN AREA (acre)= 14.85 - Changed from 1993 report due to new delineation of sub -basin
'
RUNOFF COEF
0.81 drainage in Basins A and B. Runoff coefficient calculation on
previous page.
***** DESIGN RAINFALL STATISTICS
'
DESIGN RETURN PERIOD (YEARS) = 2.00
TABLE IS GIVEN
INTENSITY(IN/HR)-DURATION(MIN)
DURATION 5 10 20 30
40 50 60
80 100 120 150 180
'
INTENSITY 3.2 2.5 1.8 1.5
1.2 1.0 0.9
0.8 0.6 0.5 0.4 0.4
***** POND OUTFLOW CHARACTERISTICS:
MAXIMUM ALLOWABLE RELEASE
RATE _ .1
CFS - Considered small enough to provide for approximately
'
OUTFLOW ADJUSTMENT FACTOR = 1
40-hour detention time and conservative pond size.
AVERAGE RELEASE RATE
_ .1
CFS
AVERAGE RELEASE RATE =
MAXIMUM RELEASE
RATE * ADJUSTMENT FACTOR.
'
***** COMPUTATION OF POND SIZE
-----------------------------------------
RAINFALL RAINFALL INFLOW
•-----------
OUTFLOW REQUIRED
'
DURATION INTENSITY VOLUME
VOLUME STORAGE
MINUTE INCH/HR ACRE -FT
ACRE -FT ACRE -FT
------------------•----•-----------------------------
0.00 0.00 0.00
0.00
0.00
5.00 3.20 0.27
0.00
0.27
10.00 2.50 0.42
0.00
0.42
15.00 2.15 0.54
0.00
0.54
20.00 1.80 0.60
0.00
0.60
25.00-- - 1.65 0.69
-0.00-
0.69
'
30.00 1.50 0.75
0.00
0.75
35.00 1.35 0.79
0.00
0.78
40.00 1.20 0.80
0.01
0.80
45.00 1.10 0.83
0.01
0.82
'
50.00 1.00 0.84
0.01
0.83
55.00 0.95 0.87
0.01
0.87
60.00 0.90 0.90
0.01
0.89
65.00 0.88 0.95
0.01
0.94
70.00 0.85 0.99
0.01
0.98
75.00 0.82 1.03
0.01
1.02
80.00 0.80 1.07
0.01
1.06
85.00 0.75 1.07
0.01
1.05
90.00 0.70 1.05
0.01
1.04
'
95.00 0.65 1.03
0.01
1.02
100.00 0.60 1.00
0.01
0.99
105.00 0.58 1.01
0.01
0.99
'
110.00 0.55 1.01
--------------------------------------------
0.02
1.00
THE REQUIRED POND SIZE = 1.058181 ACRE -FT
THE RAINFALL DURATION FOR THE
ABOVE POND STORAGE= 80 MINUTES
'
Fort Collins Streets Facility
Composite Rational Method Runoff Coefficient for Water Quality Pond B
' Designer: SLG
Basin jArea
ac
C
Area' C
Notes
From Current
Report:
0-2
0.21
0.25
0.05
"
0-3
0.54
0.25
0.14
"
0-4
0.13
0.25
0.03
"
-5
0.11
0.25
0.03
"
-6
0.11
0.25
0.03
"
-3
0.13
0.35
0.05
From Muller Engineering Report
1.23
0.95
1.17H-1
0.93
0.41
0.38H-2
[4B-1
0.66
0.75
0.49H-3
0.48
0.95
0.46H-4
0.27
0.54
0.14H-5
1.87
0.95
1.78ond
B
0.85
0.25
0.21
This includes 0.18 ac from original 1993 H Basin
Total:
7.52
4.95
■
Composite C for Basin: 0.66
"Basins A, B, 0-2, and H from the 1993 Preliminary Drainage, Erosion, and
Storm Water Quality Study were divided further for development design.
1
183-047
(Fort Collins)
DETENTION POND SIZING BY
FAA METHOD
Developed by
'
Civil Eng. Dept., U. of Colorado
Supported by Denver Metro Cities/Counties Pool Fund Study
Denver Urban Drainage and Flood Control District, Colorado
---------------------
USER=Kevin Gingery__ .....
EXECUTED ON 06-23-1999 AT TIME 15:43:53
PROJECT TITLE: Fort Collins Streets Facility -
Water Quality Pond B
***• DRAINAGE BASIN DESCRIPTION
BASIN 1D NUMBER = 1.00
BASIN AREA (acre)= 7.52 - Changed from 1993 report due to inclusion of railroad Swale and
'
RUNOFF COEF 0.66 sub -basins 48-3 and A-3. Runoff coefficient calculation on
previous
page.
•*••* DESIGN RAINFALL STATISTICS
'
DESIGN RETURN PERIOD (YEARS) = 100.00
INTENSITY(IN/HR)-DURATION(MIN) TABLE IS GIVEN
DURATION 5 10 20 30 40 50 60
80 100 120 150 180
INTENSITY 3.2 2.5 1.8 1.5 1.2 1.0 0.9
0.8 0.6 0.5 0.4 0.4
**•** POND OUTFLOW CHARACTERISTICS:
'
MAXIMUM ALLOWABLE RELEASE RATE = .1
CFS - Considered small enough to provide for approximately
OUTFLOW ADJUSTMENT FACTOR = 1
40-hour detention time and conservative pond size.
AVERAGE RELEASE RATE = .1
CFS
'
AVERAGE RELEASE RATE = MAXIMUM RELEASE
RATE * ADJUSTMENT FACTOR.
**•** COMPUTATION OF POND SIZE
-
'---•'-------•-----'-----..'---.-----••----•----
RAINFALL RAINFALL INFLOW OUTFLOW REQUIRED
•'--
DURATION INTENSITY VOLUME VOLUME STORAGE
MINUTE INCH/HR ACRE -FT ACRE -FT ACRE
-FT
----•----•---•----•-----••-----•---------- •----••---
0.00 0.00 0.00 0.00
0.00
'
5.00 3.20 0.11 0.00
0.11
10.00 2.50 0.17 0.00
0.17
15.00 2.15 0.22 0.00
0.22
20.00_ _ _ 1.80 __ 0.25 0.00
0.25
'
25.00 1.65 0.28 0.00
0.28
30.00 1.50 0.31 0.00
0.31
35.00 1.35 0.33 0.00
0.32
'
40.00 1.20 0.33 0.01
45.00 1.10 0.34 0.01
0.33
0.34
50.00 1.00 0.34 0.01
0.34
55.00 0.95 0.36 0.01
0.35
60.00 0.90 0.37 0.01
0.36
65.00 0.88 0.39 0.01
0.38
'
70.00 0.85 0.41 0.01
0.40
75.00 0.82 0.43 0.01
0.42
80.00 0.80 0.44 0.01
0.43
85.00 0.75 0.44 0.01
0.43
90.00 0.70 0.43 0.01
0.42
95.00 0.65 0.43 0.01
0.41
100.00 0.60 0.41 0.01
0.40
105.00 0.58 0.42 0.01
0.40
'
110.00 0.55 0.42 0.02
0.40
----------------- ---... •--------•----------
THE REQUIRED POND SIZE = .4301541 ACRE -FT
'
THE RAINFALL DURATION FOR THE ABOVE POND STORAGE= 80 MINUTES
' Fort Collins Streets Facility
Water Quality Ponds A & B Volume Calculations
' Designer. S. Gentry
I. Water Quality Pond A
Contour Area (ft"2) Volume (ft"3) Volume (ac-ft)
' 46 350.00
18993.49
47 52350.00
' 27070.01
47.5 55950.00
Total: 46063.51 = 1.06
' Needed Volume: 1.06
Surplus 0.00
Water Quality Pond A volume is adequate for the situation.
'
II. Water Quality Pond B
'
Contour
Area (ft^2) Volume (ft"3)
47
1.00
'
48
9184.95
27388.36
14201.45
48.5
29429.68
'
Total: 23386.40
Needed Volume:
Surplus _
Volume (ac-ft)
' Water Quality Pond B volume is adequate for the situation.
1
0.54
0.43
0.11_
183-047
(Fort Collins)
Section 1
General Location and Description
1.1 Location
The Project is located on Lot 5A of the East Vine Traffic Operations Facility,
immediately south of East Vine Street, and approximately 1200 feet east of Linden
' Street in Ft. Collins. The property is situated between Linden Street and the future
Colorado Department of Transportation (CDOT) Region 4 Maintenance Facility on
Lot 4A (currently under construction).
' The site location can also be described as situated in the Northeast 1/4 of Section 12,
Township 7 North, Range 69 West of the 6th P.M., City of Loveland, Larimer
' County, Colorado.
' 1.2 General Project & Site Description
Proposed Project improvements include overlot grading of the Lot 5A that will permit
' construction of the future City Traffic Operations Facility. The Site will include a
single story office structure and garage facility. The Site will also include a parking
area, and vehicles will have access to the Site via a private street off of Linden Street.
1
The subject property of Lot 5A contains approximately 3.25 acres, and is currently
undeveloped. Existing topography generally slopes to the east and west from the
center of the Site at approximately 0.5 percent. Vegetation over existing Lot 5A is
representative of native grasses, and no trees or major bushes are present on Site. An
' asphalt parking area was constructed in the northwest quadrant of the Site to serve as
daily parking for local municipal properties just north of East Vine Street. This
asphalt parking area will be removed as part of the proposed improvements.
Inspection of local floodplain maps (FEMA FIRM & Dry Creek Hydrologic Report)
' and discussions with City Staff (M. Hilmes, July 2001) indicate that the Site is
located outside of the Dry Creek and Cache La Poudre floodplain limits, and no
wetlands have been identified. Drainage improvements will include overlot grading,
curb & gutter, drainage pans, and use of an existing storm inlet that ties into existing
storm facilities associated with adjacent properties.
' 1.3 Site Soils Information
' Review of the SCS Soils Report for Larimer County indicates that the natural soil
composition for Lot 5A is indexed as Caruso Clay, consisting primarily of clay -loam
' M:VOBS1I81-0501dots\Fina1 1
Drainage Report_I12001.doc SEAR • BROW N
Fort Collins Streets Facility 183-047
Detention Pond Volume Calculations (Fort Collins)
Designer: SLG
The survey certification after completion of 1993 construction shows an increase
in contour size from what was planned. Therefore, the volume for the detention pond
was recalculated.
Contour Area (ft^2) Volume (f A3)
44 9585.12
28575.40
45 53496.61
85167.48
46 121413.10
Total:
113742.88 =
Volume (ac-ft)
2.61
Top of pond is 4947 feet. The emergency overflow weir is set at 4946 feet.
Setting the maximum water surface elevation for the 100-year storm
at 4946 feet allows for one (1) foot of freeboard.
Volume Available for Detention:
Pond Volume (ac-ft)
Water Quality Pond A 1.06
Water Quality Pond B 0.54
Detention Pond 2.61
Total: 4.21
Volume needed for detention is: 4.18 ac-ft
Volume available for detention is: 4.21 ac-ft
Surplus of 0.03 ac-ft
Current detention pond volume is adequate for the situation.
0
1
E
I
I
I
0
I
EROSION CONTROL
I
M M M M M M M M M M. M
M
i
Project:. Traffic OperationFacility
Project No: 183-050 1!
Erosion Control
Rainfall Performance Standard Evaluation
Developed
Basin
Erodibility
Zone
Asb
ac
Lsb
ft)
Ssb
%
Lb
(ft
Sb PS
%)
5A-1
Moderate
0.79
415
1.0
5A-2
Moderate
0.24
370
1.4
5A-3
Moderate
0.91
225
2.0
5A-4
IModerate
1
1.39
450
2.0
Total
1
1
3.331
1 1871
0.884685 80.3
Lb = Sum(AsbLsb)/Sum(Asb)
(1.13x290+..+0.46x302)/3.16
Sb = Sum(AsbSsb)/Sum(Asb)= (1.13x2.0+..+0.46x2.0)/3.16
PS(during construction) =
80.3 Table 5.1 City E/C Manual
PS (post construction) =
94.5 (PS/0.85
Project:. Traffic OperationsStreet Facility
Project: 183-050
Project No: Runoff Calculations
Erosion Control
Effectiveness Calculations
(During Construction)
Measures
C-Factor
P-Factor Comment
Bare Soil
1.00
1.00 Smooth Condition
Roughened Soil
1.00
0.90 Table 5.2
Asphalt/Paved
0.01
1.00 All Basins
Gravel Mulch
0.05
1.00 All Basins
Gravel Filters
1.00
0.80 Basins 5A2-4
Straw Bales
1.00
0.80 All Basins
Silt Fence
1.00
0.50 All Basins
Hay Mulch
0.06
1.00 Spr Wheat
Sod Grass
0.01
1.00 Basin 5A-1
Major
Basin
PS
(%)
Subbasin
ID
Area
(acre)
Calculations
Measure C CA P PA Efficiency
Lot 5A
80%
5A-1
0.79
Gravel Mulch
0.05
0.040
1.00
0.79
957/6
5A-2
0.24
Gravel Mulch
0.05
0.012
1.00
0.24
95%
5A-3
0.91
Gravel Mulch
0.05
0.046
1.00
0.91
95%
5A-4
1.39
Gravel Mulch
0.05
0.070
1.00
1.39
95%
Total
i
3.331
Effnet
95%
c;omment:
Effectiveness 95%
Performance Standard 80%
Adequacy Adequate)
Project: Traffic OperationsStreet Facility
Project: 183-050
Project No: Runoff Calculations
Erosion Control
Effectiveness Calculations
(Post Construction)
Measures
C-Factor
P-Factor Comment
Bare Soil
1.00
1.00 Smooth Condition
Roughened Soil
1.00
0.90 Table 5.2
Asphalt/Paved
0.01
1.00 All Basins
Gravel Mulch
0.05
1.00 All Basins
Gravel Filters
1.00
0.80 Basins 5A2-4
Straw Bales
1.00
0.80 All Basins
Silt Fence
1.00
0.50 All Basins
Hay Mulch
0.06
1.00 Spr Wheat
Sod Grass
0.01
1.00 Basin 5A-1
Major
Basin
PS
(%)
Subbasin
ID
Area
(acre)
Calculations
Measure C CA P PA Efficiency
Lot 5A
947/.
5A-1
0.79
Asphalt/Paved/Grass
0.01
0.008
1.00
0.79
99%
5A-2
0.24
As h'alUPaved/Grass
0.01
0.002
1.00
0.24
99%
5A-3
0.91
As h'alt/Paved/Grass
0.01
0.009
1.00
0.91
99%
5A-4
1.39
As h'alt/Paved/Grass
0.01
0.014
0.80
1.112
99%
Total
3.331
1
Effnet
99%
uomment:
Effectiveness 99% (EFF)
Performance Standard 94% (PS)
Adequacy Adequate Measures
P!
to
A
RAINFALL
LENGTHI
(FT) 0.5 1.0 1.5 2.0 2.5 3I.0 3.5
TABLE 8-A
STANDARDS FOR FORT COLLINS, COLORADO
SLOPE (%)-
4.0 4.5 5.0 6.0 7.0 8.0 9.0 10.0 20.0 30.0 40.0 50.0
100
70.9
74.6
76.8
78.4
79.5
80.3
81.1
81.6
82.1
82.5
83.0
83.4
83.6
83.8
84.0
84.7
84.8 84.9 84.9
200
72.0
76.3
78.2
79.5
80.5
81.2
82.1
82.5
82.8
83.2
83.6
83.9
84.0
84.2
84.3
84.8
84.9 84.9 84.9
300
72.4
77.0
78.8
80.0
80.9
81.6
82.5
82.8
83.1
83.5
83.8
84.1
84.2
84.3
84.4
84.8
84.9 84.9 85.0
400
72.6
77.4
79.1
80.3
81.2
81.8
82.7
83.0
83.3
83.7
84.0
84.2
84.3
84.4
84.5
84.8
84.9 84.9 85.0
500
72.7
77.7
79.4.80.5
81.3
01.9
82.8
83.1
83.4
83.8
84.1
84.3
84..4
84.5
84.6
84.9
84.9 85.0 85.0
600
72.8
77.9
79.5
80.6
81.4
82.0
83.0
83.2
83.5
83.9
84.1
84.3
84.4
84.5
84.6
84.9-84.9
85.0
700
72.8
78.0
79.7
80.8
81.5
82.1
83.0
83.3
83.5
84.0
84.2
84.4
84.5
84.5
84.6
84.9
84.9 85.0
800
72.7
78.1
79.7
80.8
81.6
82.2
83.1
83.4
83.6
84.0
84.2
84.4
84.5
84.6
84.6
84.9
84.9 85.0
900
72.7
78.2
79.8
80.9
81.7
82.2
83.2
83.4
83.6
84.1
84.3
84.4
84.5
84.6
84.7
84.9
84.9 85.0
1000
72.7
78.3
79.9
81.0
81.7
82.3
83.2
83.5
83.7
84.1
84.3
84.4
84.5
84.6
84.7
84.9
84.9 85.0
1100
72.6
78.3
79.9
81.0
81.7
82.3
83.3
83.5
83.7
84.1
84.3
84.5
84.6
84.6
84.7
84.9
84.9
1200
72.6
78.4
80.0
81.0
81.8
82.3
83.3
83.5
83.7
84.2
84.3
84.5
84.6
84.6
84.7
84.9
84.9
1300
72.6
78.4
80.0.
81.1
81.8
82.4
83.3
83.6
83.8
84.2
84.4
84.5
84.6
84.6
84.7
84.9
85.0
1400
72.5
78.5
80.1
81.1
81.8
82.4
83.4
83.6
83.8
84.2
84.4
84.5
84.6
84.7
84.7
84.9
85.0
1500
72.4
78.5
80.1
81.1
81.9
82.4
83.4
83.6
83.8
84.2
84.4
84.5
84.6
84.7
84.7
84.9
85.0
1600
72.4
78.5
80.1
81.1
81.9
82.4
83.4
83.6
83.8
84.2
84.4
84.5
84.6
84.7
84.7
84.9
1700
72.3
78.5
80.1
91.2
81.9
82.4
83.4
83.6
83.8
84.3
84.4
84.5
84.6
84.7
84.7
84.9
1800
72.3
78.6
80.1
81.2
81.9
82.4
83.4
83.7
83.8
84.3
84.4
84.5
84.6
84.7
84.7
84.9
1900
72.2
78.6
80.2
81.2
81.9
82.5
83.5
83.7
83.9
84.3
84.4
84.5
84.6
84.7
84.7
84.9
2000
72.2
78.6
80.2
81.2
81.0
82.5
83.5
83.7
83.9
84.3
84.4
84.6
84.6
84.7
84.7
84.9
2500
71.9
78.6
80.2
81.3
82.0
82.5
83.5
83.7
83.9
84.3
84.5
84.6
84.7
84.7
84.8
3000
71.6
78.7
80.3
81.3
82.0
82.5
83.6
83.8
84.0
84.4
84.5
84.6
84.7
84.7
84.8
3500
71.4
78.7
80.3
81.3
82.0
82.6
83.6
83.8
84.0
84.4
84.5
84.6
84.7.84.7
84.8
4000
71.1
78.6
80.3
81.3
82.0
82.6
83.6
83.8
84.0
84.4
84.5
84.6
84.7
84.8
84.8
4500
70.9
78.6
80.3
81.3
82.0
82.6
83.7
83.9
84.0
84.4
84.6
84.6
84.7
84.8
84.8
5000
70.6
78.6
80.3
81.3
82.0
82.6
83.7
83.9
84.0
84.4
84.6
84.7
84.7
84.8
84.8
I
'
Table 8B C-Factors and P-Factors for Evaluating EFF Values.
Treatment C-Factor
P-Factor
BARE SOIL
Packedand smooth................................................................ 1.00
1.00
Freshlydisked........................................................................ 1.00
1.00
0.90
0.90
'
Rough irregular surface...........................................................
SEDIMENT BASIN/TRAP................................................................. 1.00
0.50111
STRAW BALE BARRIER, GRAVEL FILTER, SAND BAG ........................ 1.00
0.80
SILTFENCE BARRIER..................................................................... 1.00
0.50
ASPHALT/CONCRETE PAVEMENT ................................................... 0.01
1.00
ESTABLISHED DRY LAND (NATIVE) GRASS .......................... See Fig. 8-A
1.00
SODGRASS................................................................................. 0.01
1.00
TEMPORARY VEGETATION/COVER CROPS .................................... 0.4512)
1.00
HYDRAULIC MULCH @ 2 TONS/ACRE........................................... 0.10"'
1.00
SOIL SEALANT....................................................................0.01-0.6014)
1.00
EROSION CONTROL MATSBLANKETS............................................ 0.10
1.00
GRAVEL MULCH
Mulch shall consist of gravel having a diameter of approximately
'
1 /4" to 1 1 /2" and applied at a rate of at least 135 tons/acre.............. 0.05
1.00
HAY OR STRAW DRY MULCH
After alantina arass seed, apply mulch at a rate of 2 tons/acre (minimum) and adequately anchor,
'
tack or crimp material into the soil.
Slope 1%)
1 to 05
1.00
............................................................................0.06
6 to 10 . 0.06
.
1.00
11 to 15............................................................................. 0.07
1.00
16 to 20............................................................................. 0.11
1.00
.0.14
-21-t6 ---25......... -
- - 1:00 - -
1.00
25 to 33.............................................................................0.17
> 33.......................................................................... 0.20
1.00
'
NOTE: Use of other C-Factor or P-Factor values reported in this table must be substantiated by docvment3don.
(1) Must be constructed as the first step in overlot grading.
(2) Assumes planting by dates identified in Table 11-4, thus dry or hydraulic mulches are not required.
(3) Hydraulic mulches shall be used only between March 15 and May 15 unless
irrigated.
(4) Value used must be substantiated by documentation.
H
' MARCH 1991 8-6 DESIGN CRITERIA
to a depth of 25 feet below natural grade. More recently however, soil material has
been stockpiled and graded over the Site as part of City operations. No significant
erosion or sediment transport has been observed as a result of the recent spoil
stockpiling operations.
1.4 Groundwater
The East Vine Street Facility P.U.D. soils report (April 1991) indicates that
groundwater in the vicinity of Lot 5A lies between 5.5 and 7.0 feet below existing
grade. Based on proposed improvements, groundwater is not anticipated to be a
concern. However, in the event that groundwater is encountered during construction,
a Colorado Department of Health Construction Dewatering Permit will be required.
M:VOBS\183-050\d=Tinal IW--�SE�ARBR�OWN�
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Section 2
Drainage Design Criteria
2.1 Regulations
The Project is located within the City of Ft. Collins, and design of On -Site Drainage
systems associated with the development of Lot 5A are in accordance with the City's
Storm Drainage Design Criteria Manual (1997).
2.2 Hydrologic Design Criteria
Based on the size of the Site, and in accordance with previous studies for the Project
area, the Rational Method is used to estimate peak surface runoff. Under City
criteria, the 2-year and 100-year storm events serve as the basis for design of on -site
drainage conveyance facilities. The analysis contained in this report incorporates the
City's updated rainfall.
2.3 Hydraulic Design Criteria
Hydraulic computations within this report have been prepared in accordance with the
City's Storm Drainage Criteria Manual. Estimates for peak runoff are determined
based on the City's equation for estimating time of concentration. Area inlets,
concrete pans and related storm sewers are designed based on City criteria.
2.4 On -Site Detention
The subject property is located within the Dry Creek Basin. Detention is required for
this Site (Sear -Brown, 1993) water quality mitigation and is provided. Lot 5A runoff
will be attenuated to historic rates through facilities located further downstream, and
on -the. east side of the primary Streets Facility offices (Sear -Brown, August 1999)
along with additional drainage received from other properties tributary to these -ponds: - --
Detention facilities used under this plan include Detention Ponds A and B, with both
including a water quality component immediately upstream of each pond (Sear -
Brown, 1993).
2.5 Variances from Criteria
No variances are requested or sought for this proposed Project.
SEAR• BROW N
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Section 3
Drainage Basins & Proposed Design
3.1 Major Basin Description
The subject property lies within the Dry Creek Basin. However, no major
drainageway exists on the Site. The Project is not located within the 100-year
floodplain of either Dry Creek or the Cache La Poudre (Lidstone & Anderson, 1997,
FIRM Panel No. 080102-0002B, February 1984).
' 3.2 Existing Sub -basin Description
Currently, the 3.25 acre subject property is vegetated with low growth, native cover.
' Generally, drainage is split equally over the Site to the east and west, with runoff
ultimately collected and conveyed via an existing swale along the north side of the
access road, and eastward to an existing inlet on Lot 4A (designed by others). The
' inlet is tied to an existing 18-inch stone line that discharges into Water Quality Pond
B (Sear Brown, 1999).
' A minor amount of Site runoff is conveyed northward to the existing swale on the
north side of Lot 5A, which ultimately conveys this and downstream runoff to an
' existing detention facility just east of the main Streets Facility (Sear Brown, 1999).
' Off -site drainage includes the east half of Linden Street, between East Vine Drive and
the private access road leading into the Site. This off -site drainage pattern will be
maintained, and improved conveyance provided via construction of a 6-inch vertical
curb and gutter system that conveys that portion of runoff in conjunction with Lot 5A
drainage to the existing area inlet at the southeast corner of the Site.
3.3 Proposed Sub -basin Description & Design
Based on proposed overlot grading and construction of on -site and off -site facilities,
there will be four on -site sub -basins. These are identified on the proposed drainage
plan included with this report as 5A-1, 5A-2, 5A-3 and 5A-4. Grading of Lot 4A
' (CDOT Site immediately to the west) and installation of a 6-foot wide drainage pan
(between Lots 4A and 5A) will intercept Lot 5A storm runoff and mitigate Site runoff
from entering the CDOT property.
1
Sub -basin 5A-1 (0.79 acres) will drain to the west via overland flow at approximately
' 2.0 percent, to the future improved Linden Street vertical curb and gutter system
along the east side of the road at approximately 0.8 percent. This sub -basin will
' M:U0BS\183-050\dccs\Fina1 4
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include the west half of the future Traffic Operations building, landscaped area and
the east half of Linden Street between East Vine Drive and the access road into the
Street property. Sub -basin 5A-1 storm runoff will be combined (routed) with
additional Site runoff via a gutter and 6-foot pan system to an existing area inlet
located at the southeast comer of the Site. An existing 18-inch RCP storm line
(constructed by others) will convey this and downstream property drainage eastward
where it will be attenuated through existing Water Quality Pond B, then released via
Detention Pond B (reference Sear -Brown, August 1999). Drainage will ultimately be
released to the Cache La Poudre River.
Sub -basin 5A-2 (0.24 acres) will drain to the north at about 1.0 percent as overland
flow to an existing swale that currently conveys this and downstream property
drainage east to Water Quality Pond A (Sear Brown, 1999). This sub -basin will
include areas of asphalt and landscaping, and will also be occupied by approximately
half of the future service garage for Traffic Operations vehicles.
Sub -basin 5A-3 (0.91 acres) will drain at about 2.0 percent as overland flow to the
southeast. Sub -basin 5A-3 runoff will be conveyed to an existing 6-foot concrete pan
(constructed by others), which will conduct Site drainage to the south and to an
existing area inlet (constructed by others). An existing 18-inch RCP storm line
(constructed by others) will convey this and downstream property drainage eastward
where it will be attenuated through existing Water Quality Pond B, then released via
Detention Pond B (reference Sear -Brown, August 1999). Drainage will ultimately be
released to the Cache La Poudre River.
Sub -basin 5A-4 (1.39 acres) will drain at about 2.0 percent as overland flow to the
southeast. Sub -basin 5A-4 runoff will be conveyed to an existing 6-foot concrete pan
along the south side of the property, which will conduct Site drainage to the east and
to an existing area inlet (constructed by others). An existing 18-inch RCP storm line
(constructed by others) will convey this and downstream property drainage eastward
Where it will be attenuated through existing Water Quality Pond B, then released via
Detention Pond B (reference Sear -Brown, August 1999) Drairiage will -ultimately be-------- —
released to the Cache La Poudre River.
SEAR• BROWN
5