HomeMy WebLinkAboutDrainage Reports - 06/07/1995March 27, 1995
Project No: 1473-01-95
Basil Hamdan, Civil Engineer
City of Fort Collins Stormwater Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Qff�, RI ; I,
Re: DRAINAGE AND EROSION CONTROL REPORT
Lot 1, Block 1, Fourth Fairview Subdivision; Fort Collins, Colorado
1320 Southridge Drive P.U.D.
Dear Basil,
1320 Southridge Drive P.U.D. is Lot 1, Block 4, Fourth Fairview Subdivision located in the SE
1/4 of Section 15, T7N, R69W of the 6th P.M., City of Fort Collins, Colorado. The P.U.D. will
consist of a 672 square foot addition to an existing residence. The addition will consist of a two
car garage with a one (1) bedroom living unit above. The site is more specifically located at the
northeast corner of the intersection of Southridge Drive and Fairview Drive. The corner lot is
109' wide by 80' deep (8,557 square feet; 0.20 acre), and is located within the Canal Importation
Basin as delineated on the City's Stormwater Basin map. There is an existing 1,374 square foot
(0.027 acre) residence. The garage/apartment unit will be an attached addition to the existing
residence. There will be a certain amount of concrete flatwork removal to facilitate construction
of the addition. There will be a new concrete drive and sidewalk adjacent to the proposed
garage. The garage faces south to Fairview Drive.
DRAINAGE:
Re -development of this site would have absolutely no effect on the overall drainage impact
within the Canal Importation Basin. A detention pond is not required. Our calculations indicate
that there will be a very minor increase in runoff due to the construction of the addition for the
immediate site. Refer to the table below.
LAND USE SUIVEUARY:
ROOF CONCRETE LAWN
C= 0.95 0.95 0.20h n
acres acres acres
HISTORIC 0.031 0.008 0.157
DEVELOPED 0.020 --�.� 0,046 0.130
Refer to page 1 in the ca�lculatio�ns for the determination of the
RUNOFF CALCULATIONS:
AREA Goo INTENSITY Q100
(acres) (iph) (cfs)
------------------------------------------
HISTORIC 0.20 0.44 9.10 0.80
DEVELOPED 0.20 0.56 9.16 1.02
W)wO'C's
composite runoff coefficient.
The intensity is based on a time of concentration of five (Y) minutes.
4836 S. College, Suite 12 Fort Collins, CO 80525 (303)226-5334
Page 2
March 27, 1995
Project No: 1473-01-95
Lot 1, Block 1, Fourth Fairview Subdivision; Fort Collins, Colorado
1320 Southridge Drive P.U.D.
EROSION CONTROL:
The required control security deposit will be $ 1,000.00. Erosion control security requirement
calculations are found on the attached estimate.
If. you have any questions concerning this minor P.U.D. development, please call at 226-5334.
SZW.Shear,
BE.
Shear Engineering Corporation
BWS / mb
cc: Wendell and Jeani Marsee
SHEAR ENGINEERING CORPORATION
RUNOFF COEFFICENTS FOR
Lot 1, Block 1, Fourth Fairview Sundivision
1320 Southridge Drive P.U.D.
PAGE 1
PROJECT :1320 SOUTHRIDGB DRIVE P.U.D.
PROJ.NO. :1473-01-95 DATE: 03/27/95
LOCATION :FORT COLLINS BY: MHO
PILE :MARSEE
NOTES :CANAL IMPORTATION BASIN
EXISTING CONDITIONS
RUNOFF
SURFACE
COEP.
CHARACTERISTICS
AREA
C.
C*A
(acres)
--------
-------
-------
-----------------
STREETS
ASPHALT
0.000
0.950
0.000
CONCRETE
0.008
0.950
0.008
GRAVEL
0.000
0.500
0.000
ROOFS
0.031
0.950
0.029
LAWNS SANDY SOIL
PLAT < 2%
0.000
0.100
0.000
AVERAGE 2 - 71t
0.000
0.150
0.000
STEEP > 7%
0.000
0.200
0.000
LAWNS HEAVY SOIL
DEVELOPED CONDITIONS
RUNOFF
SURFACE
COEF.
CHARACTERISTICS
AREA
C.
C*A
(acres)
-------
-------
-------
-----------------
STREETS
ASPHALT
0.000
0.950
0.000
CONCRETE
0.020
0.950
0.019
GRAVEL
0.000
0.500
0.000
ROOFS
0.046
0.950
0.044
LAWNS SANDY SOIL
FLAT < 214
0.000
0.100
0.000
AVERAGE 2 - 71,
0.000
0.150
0.000
STEEP > 7t
0.000
0.200
0.000
LAWNS HEAVY SOIL
PLAT < 24
0.157
0.200
0.031
PLAT < 211
0.130
0.200
0.026
AVERAGE 2 -
714
0.000
0.250
0.000
AVERAGE 2 -
7i 0.000
0.250
0.000
STEEP > 7%
0.000
0.350
0.000
STEEP > 74
0.000
0.350
0.000
TOTAL AREA
0.196
0.068
TOTAL AREA
0.196
0.089
C2
C10
C100
C2
C10
C100
COMPOSITE C
--------
VALUE
0.349
-------
0.349
-------
0.437
COMPOSITE C
-------
VALUE 0.453
-------
0.453
-------
0.566
USE
0.35
0.35
0.44
USE
0.45
0.45
0.57
CONCLUDE:
THE
MINOR
INCREASE
IN IMPERVIOUSNESS
WILL RESULT
IN AN SLIGHT INCREASE
IN RUNOFF
ASSUME
Tc =
5.0 MINUTES
HISTORIC
DEVELOPED
I2 -
3.29
iph
Q2 =
0.23
0.29
I10
5.64
iph
Q10 =
0.39
0.50
I100
9.10
iph
Q100 =
0.78
1.02
THESE PLOWS ARE NEGLIBLE
March 27, 1995
Project No. 1473-01-95
Basil Hamdan
City of Fort Collins Stormwater Utility
P.O. Box 580
Ft. Collins, Colorado 80522
Re: Lot 1, Block 1, Fourth Fairview Subdivision; Fort Collins, Colorado
1320 Southridge Drive P.U.D.
Dear Basil,
Attached is the erosion control security deposit estimate for Lot 1, Block 1, Fourth Fairview
Subdivision.
ESTIMATE 1:
65 LF of silt fence at $3.50 per LF $ 227.50
TOTAL ESTIMATED COST: $ 227.50
x 1.50
$ 341.25
ESTIMATE 2:
re -vegetate the disturbed area of 0.01 acres at $1,300.00 per acre $13.00
TOTAL ESTIMATED COST: S 13.00
x 1.50
$ 19.50
The total required erosion control security deposit would be $ 1,000.00.
If you have any questions, please call at 226-5334.
S
Brian W. Shear, P.E.
Shear Engineering Corporation
BW S / mb
cc: Wendell and Jeanni Marsee .
Dave Stringer; City of Fort Collins Engineering
4836 S. College, Suite 12 Fort Collins, CO 80525 (303)226-5334
March 27, 1995
Project No. 1473-01-95
Re: EROSION CONTROL SECURITY DEPOSIT REQUIREMENTS:
Lot 1, Block 1, Fourth Fairview Subdivision; Fort Collins, Colorado
1320 Southridge Drive P.U.D.
A. An erosion control security deposit is required in accordance with City of Fort Collins
policy (Chapter 7, Section C : SECURITY; page 7.23 of the City of Fort Collins
Development Manual). In no instance shall the amount of the security be less than
$1000.00.
1. According to current City of Fort Collins policy, the erosion control security deposit
is figured based on the larger amount of 1.5 times the estimated cost of installing
the approved erosion control measures or 1.5 times the cost to re -vegetate the
anticipated area to be disturbed by construction activity.
a The cost to install the proposed erosion control devices for Lot 1, Block 1,
Fourth Fairview Subdivision is $ 227.50. 1.5 times this estimate is $341.25.
i. unit prices have been provided by Connell Resources.
b. Based on current data provided by the City of Fort Collins Storm Water Utility,
and based on an actual anticipated net affected disturbed area during
construction of the addition to the existing residence on Lot 1, Block 1, Fourth
Fairview Subdivision (approximately 0.01 acres) we estimate that the cost to re -
vegetate the disturbed area will be $13.00 ($1,300.00 per acre x 0.01 acres). 1.5
times the cost to re -vegetate the disturbed area is $ 19.50.
i. The 0.01 acres is the actual disturbed area of Lot 1, Block 1, Fourth
Fairview Subdivision.
ii. The $1,300.00 per acre for re -seeding sites of less than 1 acre was quoted to
us by the City of Fort Collins Storm Water Utility staff.
CONCLUSION:
The erosion control security deposit aniount required for Lot 1, Block 1, Fourth Fairview
Subdivision will be $ 1,000.00.
4836 S. College, Suite 12 Fort Collins, CO 80525 (303)226-5334