00071685GALIND O ENGINEERS AND PLANNERS, INC.
3833 South Texas Ave., Suite 213 Bryan, Texas 77802 (979) 846-8868
October 25, 2001
Spencer G. Thompson, Jr.
Development Services
City of College Station
1101 South Texas Avenue
College Station, TX 77840
Subject: Drainage Report
Skypala Fourplexes
College Station, TX
Please find enclosed the referenced report for your review. This analysis covers the
Skypala Fourplexes, a 0.9511-acre tract bound by Wellborn Road, Maple Street and
First Street, in the W. C. Boyett Estate Partition, college Station, TX.
Sincerely,
GALINDO ENGINEERS AND PLANNERS, INC.
a . Galindo, P.E., R.P.L.S.
President
cc: Greg Et Cindy Skypala
2700 West 16th, Apt. 313
Amarillo, TX 79102
0 F 7-4141.
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•C3.' 53425 C'.
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~~'c h ~SC'i L, Lam.
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GALINDO ENGINEERS AND PLANNERS, INC.
3833 South Texas Ave., Suite 213 Bryan, Texas 77802 (979) 846-8868
SKYPALA FOURPLEXES
DRAINAGE REPORT
29-01
1. TRACT DESCRIPTION
This project encompasses six 2-story fourplexes on Lots 1, 2, 3, 18, 19 and 20, Block 15, W. C. Boyett Estate
Partition, for a total of 0.9511 acre.
The attached 24" x 36" Site Plan is part of this report and is herein referred to as Exhibit 1. This exhibit
depicts the proposed improvements and grading plan for the project.
No field work was performed by the undersigned. All surveying data was provided by the Client or obtained
from City of College Station public records.
The adopted Flood Insurance Study does not identify the existence of a 100-year flood plain affecting this
tract (Map # 48041 C 0143 C, July 2, 1992).
2. PURPOSE OF THIS ANALYSIS
The purpose of this report was to estimate the pre and post development runoff and determine the
performance of the proposed grading and of the proposed outlet structure.
3. RESULTS
This tract is relatively flat, currently vacant, clear of ground cover and subjected to considerable amounts
of vehicular traffic. This is reflected on the runoff coefficient of 0.45 given in Exhibit 2. This exhibit shows
the runoff calculations for the 5, 10, 25, 50 and 100-year storms for the only drainage section defined.
The resulting calculated runoff for the 100-yr storm is 4.66 cfs, for Pre Development, and 7.19 cfs for Post
Development conditions, or an increase of 50%.
Exhibit 3 (in 2 pages) depicts the flow characteristics of the proposed outlet structure to be located at the
southeast end of the parking lot. A 2.5' curb cut (in a 0.5' high curb) will allow a flow of 4.66 cfs at a
velocity of 5.24 fps with water rising 0.36'. The same curb cut will allow a flow of 7.19 cfs at a velocity of
6.06 fps with water rising 0.47'. Therefore this outlet will provide a degree of runoff mitigation.
This analysis has been prepared in conformance with the City of College Station standards.
CHRISTIAN A. GALINDO, P.E. # 53425, R.P.L.S. # 4473
October 25, 2000
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EXHIBIT 2
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Rectangular Channel Analysis & Design
Open Channel - Uniform flow
Worksheet Name: SKYPALA FOURPLEXES
Comment: PARKING LOT OUTFALL - Q100 PRE DEVELOPMENT
Solve For Depth
Given Input Data:
Bottom Width.....
Manning's n......
Channel Slope....
Discharge........
Computed Results:
Depth............
Velocity.........
Flow Area........
Flow Top Width...
Wetted Perimeter.
Critical Depth...
Critical Slope...
Froude Number....
2.50 ft
0.014
0.0135 ft/ft
4.66 cfs
0.36
ft
5.24
fps
0.89
sf
2.50
ft
3.21
ft
0.48
ft
0.0056 ft/ft
1.55
(flow is Supercritical)
EXHIBIT 3
Open Channel Flow Module, Version 3.21 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708
Rectangular Channel Analysis & Design
Open Channel - Uniform flow
Worksheet Name: SKYPALA FOURPLEXES
Comment: PARKING LOT OUTFALL - Q100 POST DEVELOPMENT
Solve For Depth
Given Input Data:
Bottom Width.....
Manning's n......
Channel Slope....
Discharge........
2.50 ft
0.014
0.0135 ft/ft
7.19 cfs
Computed Results:
Depth............
Velocity.........
Flow Area........
Flow Top Width...
Wetted Perimeter.
Critical Depth...
Critical Slope...
Froude Number....
0.47
ft
6.06
fps
1.19
sf
2.50
ft
3.45
ft
0.64
ft
0.0058 ft/ft
1.55
(flow is Supercritical)
Open Channel Flow Module, Version 3.21 (c) 1990
Haestad Methods, Inc. * 37 Brookside Rd * Waterbury, Ct 06708