HomeMy WebLinkAbout11-00500021- 00076700Drainage Report
for
Saddle Creek Subdivision, Phase 713
Brazos County, Texas
February, 2011
Engineer. -
Schultz Engineering, LLC
TBPE Firm No. 12327
P.O. Box 11995
College Station, TX 77842
2730 Longmire Drive, Suite A
College Station, Texas 77845
(979) 764 -3900
Developer.
Saddle Creek Partners, Ltd.
4440 Bentwood Drive
College Station, Texas 77845
Phone: (979) 690 -2642
Saddle Creek Subdivision, Phase 713
' Drainage Report
' ENGINEER
SCHULTZ ENGINEERING, LLC.
P.O. Box 11995
' College Station, Texas 77842
Phone: (979) 764 -3900
Fax: (979) 764
OWNERMEVELOPER
Saddle Creek Partners, Ltd.
4440 Bentwood Drive
College Station, Texas 77845
Phone: (979) 690 -2642
GENERAL DESCRIPTION AND LOCATION
Location: Saddle Creek Subdivision, Phase 7B, is located on the south east side of FM 2154, off of
Stousland Rd.
Description:
• Area:
• Proposed Land Use:
■ # of Lots:
■ Existing Land Use:
■ Land Description:
Primary Drainage Facility:
Flood Hazard Information:
FEMA FIRM
Floodplain:
30.458 acres
Single Family Residential
19 lots
Vacant
The terrain slopes in 2 directions southwest and south east
Boggy Creek
# 48041 C200 -C & # 48041 C215 -C (July 2, 1992)
Un- shaded Zone X
HYDROLOGIC CHARACTERISTICS
The existing site is predominately wooded. The elevations range from 256 to 283, sloping generally in a westerly
direction except for the area along Saddle Creek Drive which slopes to the southeast. The runnoff enters tributaries of
Boggy Creek.
GENERAL STORMWATER PLAN
The drainage plan for this development will involve the construction of ditches and the installation of culverts.
DRAINAGE DESIGN
General Information: Stormwater runoff from Phase 7B of the subdivision will be collected in the ditches and
will discharge into Channel No. 1 and eventually into the tributaries of Boggy Creek.
Page 1 of 2
■ CONCLUSION The culverts and the roadside ditches for this subdivision were designed in accordance with
appropriate engineering standards.
CERTIFICATION
I, Joseph P. Schultz, Licensed Professional Engineer No. 65889, State of Texas, certify that this report for the drainage design
for Saddle Creek Subdivision, Phase 7B, was prepared by me in accordance with the requirements of the Brazos County Road
and Bridge Department.
OF
Al ..................... A. Jose P. hultz, P.E.
' .JOSEPH P. SCHULTZ .
65889
ST0011- 14
ONAL Page 2 of 2
F -12327
SCHULTZ ENGINEERING, LLC.
T, Methodology:
TR 55
T, Minimum
10 minutes
Design Storm Event:
25 -year & 100 -year - residential street & culvert
Pipe Materials:
Corrugated HDPE w /smooth interior
Manning's n Value:
0.012
Runoff Coefficient:
0.45
'
Design Results
Culvert No. 1 Culvert No. 2
Top of Road = 268.91 Top of Road = 269.86
Q,o 24.79 Q10=22.57
'
HW,o 267.05 HW,o= 268.02
Q,op 29.54 Q,00 =26.92
H W,00= 267.25 HW100= 268.17
Culvert No. 3 Culvert No. 4
Top of Road = 269.00 Top of Road = 276.80
Q10=14.70 Q10=7.13
HW, 266.89 HW, 274.18
i
Q,00 =17.52 Q, oo =8.49
N
HW, 267.19 HW,00= 274.40
ob.
The data presented above and in the Appendices indicates the culvert sizes are in
accordance with the requirements. The head water elevation for each of the culverts is less
than the top of road elevation for the 100 -yr storm runoff. The velocities in the channel are
low enough that grass -lined channels are appropriate.
Applicable Exhibits:
Exhibit A — Drainage Area Map
Appendix A — Drainage Area Summary
Appendix B — Culvert No. 1, 2, 3, 4 and Channel No. 1 & Channel No. 2 Design
Summaries
■ CONCLUSION The culverts and the roadside ditches for this subdivision were designed in accordance with
appropriate engineering standards.
CERTIFICATION
I, Joseph P. Schultz, Licensed Professional Engineer No. 65889, State of Texas, certify that this report for the drainage design
for Saddle Creek Subdivision, Phase 7B, was prepared by me in accordance with the requirements of the Brazos County Road
and Bridge Department.
OF
Al ..................... A. Jose P. hultz, P.E.
' .JOSEPH P. SCHULTZ .
65889
ST0011- 14
ONAL Page 2 of 2
F -12327
SCHULTZ ENGINEERING, LLC.
Saddle Creek Subdivision - Phase 7B
Appendix A Drainage Area Summary
Area #
Area, A
(acres)
C
k
(min)
25 year storm
100 year storm
1 10
(in /hr)
Q10
(Cfs)
1 100
(in/hr)
Q
(cfs)
201
0.380
0.45
25.3
6.261
1.07
7.429
1.27
202
10.430
0.45
39.5
4.809
22.57
5.736
26.92
203
6.610
0.45
37.8
4.942
14.70
5.891
17.52
204
0.070
0.45
10.0
9.861
0.31
11.639
0.37
205
0.420
0.45
10.0
9.861
1.86
11.639
2.20
206
0.370
0.45
10.0
9.861
1.64
11.639
1.94
207
3.053
0.45
34.8
5.191
7.13
6.182
8.49
0.469
0.45
10.0
9.861
2.08
11.639
2.46
F� 208
209
8.188
0.45
51.1
4.084
15.05
4.889
18.01
210
0.500
0.45
10.0
8.861
2.22
11.638
2.62
211
0.330
0.45
10
9.861
1.46
11.639
1.73
The Rational Method:
Q = CIA
I = b / (t c +d) e
Q = Flow (cfs)
t = Time of concentration (min)
A = Area (acres)
C = Runoff Coeff.
I = Rainfall Intensity (in /hr)
Brazos County.
25 year storm 100 year storm
b = 89 b = 96
d = 8.5 d = 8.0
e = 0.754 e = 0.730
t� = L /(V - 60)
L = Length (ft
V = Velocity (ft/sec)
t
1
1
Saddle Creek Subdivision - Phase 7B
Appendix B
Pipe Design Summary
Pipe
No.
Pipe
Size
(in)
Length
ft
Slope
N
Contributing
Drainage
Areas
Contributing
Pipes
Qa
(cfs)
VM
f
a,m
cfs
V1.
(fps)
1
2-24
67
0.85
1.00
- 1.00 --
201, 202, 210, 211
P2
24.79
1.00
202, 210
7.27
29.54
7.60
3.17
32.54
2
2-24
58
202
209
22.57
7.42
26.92
7.76
` -
280
1.00
15.05
2.70
18.01
3
24
60
- 203
14.70
7.95
17.52
8.33
4
24
68
1.8 T
207
7.13
8.41
8.49
8.84
Appendix B
Channel Design Summary
Channel
No.
Length
I
Sbpe
Contributing
Drainage Areas
Contributing
Pipes
a,.
(cfs)
V 1 .
(fps)
Depth,.
(ft)
aim
(cfs)
V,..
(fps
Depth,,
(ft
201, 202, 210, 211
P 1, P2
27.32
1.00
3.37
1.05
240
_- _ 0.9
3.17
32.54
2
209
0.71
0.78
280
1.00
15.05
2.70
18.01
2.84