HomeMy WebLinkAboutMULBERRY & LEMAY CROSSING, LOT 2, CENTENNIAL BANK - MAJOR AMENDMENT - 36-96N - SUBMITTAL DOCUMENTS - ROUND 1 - DRAINAGE REPORTRunoff Calculations using Rational Method
Project: First Main Street Bank, Mulberry Calculations By: J. MILLER
Project No.: MBJ DMW Civil Engineers, Inc.
Condition: Developed
NRCS Soil Type = B A, B, C, or D Date: 05/24/05
Design Storm Return Period, Tr = 100 years - 2, 10, or 100
Velocity Equation
V = C S1n
= 0.395(1.1-05)L112 / S1/3
Tt= L / 60V
Tc= Ti + Tt (5 minute min.)
Tc= (L/180) + 10 (For the first design point in a series if Tc= Ti + Tt yields a larger value)
Overland Flow
Reach
Design
Basins
Area
Runoff
Upstream
Length
Slope
Flow
Length
Slope
NCRS
Point
Coe1f.
Time
Time
Convey.
A
C
Tu
C5
L
S
Ti
L
S
Cv
(acres
(min.)
(R)
("t)
(min.)
(ft)
(fVft)
1
1
1 0.41
1 1.00
1 0.0 1
0.15
1 40
10.020
8.7
220
0.0051
20
MBJ-D100.x1s, Runoff 1 of 1
Type of land Surface
CV
Heavy meadow
2.5
Tilla e / field
5
Short pasture and lawns
7
Nearly bare ground
10
rassed waterway15
Paved areas and shallow paved swales
20
Reach 2
elociry
Reach
Length
Slope
NCRS
Veloc t
Time
Convey.
V
T1
L
S
CV
V
(f
min.
IN
(ft>Yt
(fps)
1.4
2.6
0
0.000
0
0.0
Time Time Intensity Flow
T2 I To I I I O
Composite Runoff Coefficient Calculations
Project: First Main Street Bank, Mulberry Calculations By: J. MILLER
Project No.: MBJ DMW Civil Engineers, Inc.
Condition: Developed
NRCS Soil Type = B A, B, C, or D Date: 05/24/05
Storm Return Period, Tr = 100 years - 2, 10, or 100
Adjustment Factor, Cf = 1.25
Runoff Coefficients are taken from Table 3-3 of the
Fort Collins Storm Drainage Design Criteria and Construction Standards
Surface Characteristics
Runoff
Coefficient
Streets & Parking:
Paved
0.95
Gravel
0.50
Drives & Walks
0.95
FEE:0.95
Lawn & Landscape
0.20
Design
Basins
Area
Area of
Area of
Area of
Area of
Area of
Weighted
Adjusted
Point
Paving
Gravel
Concrete
Roofs
Lawns
Coefficient
Coefficient
A
C
C
(acres)
(acres)
acres
acres
(acres)
(acres)
1
1
0.41
0.14
0.00
0.08
0.10
1 0.08
0.80
1.00
MBJ-D100.xls, Coefficient 1 of 1
Runoff Calculations using Rational Method
Project: First Main Street Bank, Mulberry
Project No.: MBJ
Condition: Developed
NRCS Soil Type = B A, B, C, or D
Design Storm Return Period, Tr = 10 years - 2, 10, or 100
Initial Overland Flow Time
Ti = 0.395(1.1-05)L1/2 / S'13
Tt= L / 60V
Tc= Ti + Tt (5 minute min.)
Tc= (L/180) + 10 (For the first design point in a series if Tc= Ti + Tt yields a larger value)
Overland Flow
Reach 1
Design
Basins
Area
Runoff
Upstream
Length
Slope I
Flow
Length
Slope
NCRS
Point
Coeff.
Tima
'lime
Convey.
A
C
Tu
CS
L
S
I I
Ti
L
S
CY
(acres)
(min.)
R)
f q)
(min.)
(ft)
(f ift)
1
1
0.41
1 0.80
1 0.0
0.15
1 40
10.0201
8.7
220
10.0051
20
MBJ-D010.xis, Runoff 1 of 1
Calculations By: J. MILLER
DMW Civil Engineers, Inc.
Date: 05/24/05
Velocity Equation
V = C„S72
Type of land Surface
Cv
Heavy meadow
2.5
Tillage / field
5
Short pasture and lawns
7
Nearly bare ground
10
Grassed waterway15
Paved areas and shallow paved swales
20
Reach 2
Reach
Length
Slope
NCRS
Velocil
Time
Convey.
;.4]
T1
L
S
CV
V
min.)
(n
wa)
(fps)
2.6
0
0.000
a
0.0
Time
Time
Intensity
Flow
T2
Tc
Q
:min.)
(min.)
(in/hr)
(cfs)
0.0
11.3
3.59
1.2
Composite Runoff Coefficient Calculations
Project: First Main Street Bank, Mulberry Calculations By: J. MILLER
Project No.: MBJ DMW Civil Engineers, Inc.
Condition: Developed
NRCS Soil Type = B A, B, C, or D Date: 05/24/05
Storm Return Period, Tr = 10 years - 2, 10, or 100
Adjustment Factor, Cf = 1.00
Runoff Coefficients are taken from Table 3-3 of the
Fort Collins Storm Drainage Design Criteria and Construction Standards
Surface Characteristics
Runoff
Coefficient
Streets & Parking:
Paved
0.95
Gravel
0.50
Drives & Walks
0.95
Roofs
0.95
Lawn & Landscape
0.20
Design
Basins
Area
Area of
Area of
Area of
Area of
Area of
Weighted
Adjusted
Point
Paving
Gravel
Concrete
Roofs
Lawns
Coefficient
Coefficient
A
C
C
(acres)
acres
acres
acres
acres
acres
1
1
0.41
0.14
0.00
0.08
0.10
1 0.08
0.80
0.80
MBJ-D010.xls, Coefficient 1 of 1
OMIA ,
CIVIL ENGINEERS
May 25, 2005
City of Fort Collins Stormwater
700 Wood Street
Ft. Collins, CO 80504
435 WEST 29TH STREET
LOVELAND, CO 60538
(970) 461-2661
FAX (970) 461-2665
WWW. DMWCIVILENGINEERS.COM
Project: Utility Plans for Centennial Bank of the West, Mulberry Street
Part of Lot 2, Mulberry and Lemay Crossing, Filing 2
DMW Project No. MBJ
I have reviewed the Final Drainage Report and Erosion Control Report for The Home
Depot at Mulberry and Lemay Crossings, Filing 2. This report provided allowed for future
development on this subject portion of Lot 2. The original report indicates that detention
for Lot 2 has been provided for in a pond at the corner of Mulberry and Lemay. Individual
lot owners are not required to provide detention on their properties.
The proposed Bank site will drain overland generally to the south onto the existing parking
lot. Flows from this existing parking lot flow overland to the south where they enter the
detention pond. The Final Drainage Report established the runoff coefficients for this
portion of Lot 2 to be 0-year and the 100-year storms to be 0.95 and 1.19, respectively.
The calculated runoff coefficients for the 10-year and the 100-year storms for this portion
of Lot 2, are 0.80 and 1.00 respectively. The 10-year and 100-year peak runoff rates were
calculated to be 1.20 cfs and 3.00 cfs respectively. Therefore, no detention will be required
for this Part of Lot 2. The grading plan is adequate for the conveyance of the stormwater
runoff to the adjacent parking lot.
Please do not hesitate to contact me if you have any questions or concerns regarding the
drainage issues for this site.
Sincerely,
DMW CIVIL ENGINEERS, INC.
Jade P. Miller, P.E. (CO #33885)
Project Engineer