HomeMy WebLinkAbout09-00500138- 00074760Drainage Report
for
Aggieland Business Park II
College Station, Texas
September, 2009
Developer:
60-Jones, LLC
6161 Imperial Lop, Suite 101
College Station, Texas 77840
(979) 571-4341
Engineer:
Civil Development, Ltd.
2033 Harvey Mitchell Parkway South
College Station, Texas 77840
(979) 764-7743
,6P-/F I 2`lj 40
a
Executive Summary Report
Aggieland Business Park II
College Station, Texas
September, 2009
ENGINEER Civil Development, Ltd. - Kent Laza, P.E. (klaza@cdlbcs.com)
P.O. Box 11929
College Station, Texas 77842
Phone: (979) 764-7743 Fax: (979) 764-7759
OWNER/DEVELOPER 60-Jones, LLC
6161 Imperial Loop, Suite 101
College Station, Texas 77840
Phone: (979) 571-4341
GENERAL This project is located on the northeast corner of Jones Road and FM 60 and is part
of the Aggieland Business Park II development project. The site is anticipated to
be developed as a convenience store although no formal plans have been
developed at this time. The general stormwater plan consists of improving a
natural drainage channel that runs through the upper portion of the lot, and the
installation of 3-42" storm pipes to carry water through the middle portion of the
site where the future buildings and driveways will be located.
HYDROLOGIC CHARACTERISTICS & EXISTING CONDITIONS
The site has recently been cleared, but the previous land cover was dense brush
and trees. The soil is classified as a sandy loam (Soil Group B) by the USGS Soil
Maps of Brazos County. The drainage basin that encompasses this property
includes a total of about 126 acres as shown in Exhibit A. Runoff from this basin
flows in a southerly direction, and enters the property through an existing drainage
channel. Immediately downstream of the site is FM 60, which has two box culverts
in close proximity to each other to carry the runoff under the roadway. One is a
5'x 5' culvert and the other is a 4'x 2' culvert. A second drainage basin
encompassing approximately 64 acres and located immediately adjacent to the first
basin also drains to the same crossing point along the TxDOT right-of-way and
contributes to the flow under FM 60. A third basin located west of Jones Road and
encompassing about 25 acres flows to these culverts along the TxDOT right-of-
way as well.
Calculations indicate that the two culverts under FM 60 were not designed to pass
runoff from these three basins during a 100-yr rainfall event. As a result, water
pools upstream of FM 60 and builds up until it flows over the roadway. The
roadway serves as a dam and the resulting pool functions as a detention pond
upstream of the roadway where the proposed site is located.
Under the anticipated development plan, the existing channel through the site will
be improved for a length of approximately 160 feet, then be directed into 3-42"
storm pipes to pass water through the site. The anticipated development plan will
require that the site be raised sufficiently to prevent it from being inundated during
heavy rainfall events, but some storage will still be maintained along the channel
and immediately adjacent to the TxDOT right-of-way.
The analysis that follows takes into account the storage provided by the FM 60
roadway in both the pre- and post-development scenarios. Detention calculations
for the post-development scenario were made using assumptions regarding the
final grading along the stream and the front of the site. No additional detention
facility is planned.
Applicable Exhibits: Exhibit A - Drainage Area Map (pre-development conditions)
Exhibit B - Drainage Area Map (post-development conditions)
CHANNEL DESIGN INFORMATION
Design Software Hydraflow Express Extension for Autocad 2010
Manning's n Value: 0.035 (dense grass)
Slope:
0.6%
Bottom Width:
2 ft
Top Width:
30 ft
Depth:
3.5 ft
Side Slopes:
4:1
Summarv of Channel Designn Analvsis:
100 year flow rate: 192.2 cfs
Velocity: 4.47 ft/s
Depth: 3.06 ft
Top Width: 26.48 ft
* The flowrate used for the channel design is taken from 100 year pre-development peak flowrate for
Drainage Area 150 in HEC-HMS. This value can be found in Exhibit A.
Applicable Exhibits: Exhibit C - Hydraflow Channel Design Report
STORM SEWER DESIGN INFORMATION
Design Software: Hydraflow Storm Sewer Extension for Autocad 2010
Pipe Size: 42 inch, HPDE
Manning's n-value: 0.012
Pipe Length: 285 ft
Slope: 0.5%
Summary of Storm Sewer Design Analysis.
Pipe Capacity: 231.6 cfs
100 year flow rate: 192.2 cfs
Velocity: 7.22 ft/s
Applicable Exhibits: Exhibit D - Hydraflow Pipe Design Report
CONCLUSIONS
From the HEC-HMS analysis shown above, we conclude that the FM 60 roadway
provides a level of detention resulting from the culvert sizes that were installed
when the facility was built. These culverts were not designed to pass the 100-yr
event, so we presume that TxDOT anticipated the pooling of runoff upstream of
the roadway during large rainfall events. When analyzed under both pre- and post-
development scenarios, this detention provides a reduction in runoff from the mid-
range storm events, but allows slightly higher peak flows during the 2-yr and 100-
yr events.
The slightly higher peak flowrate for the 100-yr event represents about a 1%
increase from the pre-development scenario, which computes to be 0.01 feet (about
1/8t' of an inch) increase in the water surface elevation over the FM 60 roadway.
This is a negligible amount of increase that will have no noticeable impact on
downstream properties. As a result, we conclude that additional detention facilities
are not necessary for the development of this site.
Applicable Exhibits: Exhibit E - HEC-HMS Analysis Report (pre-development conditions)
Exhibit F - HEC-HMS Analysis Report (post-development conditions)
X
o~
1
'-Iil
fig Q_
i o\
IN, 1
151
\ 64. 8 \
26.6
150
126.6
ACREAGE i
LEGEND
DRAINAGE AREA LABEL
~'"ate
°a'B'r AGGIELAND BUSINESS PARK, II R
a
A PRE DEVELOPMENT 2U33 M~rve MM1OM1etl P_,wy &wM
ColMpe 81~Ibn, Tap new
P.C. Sm 11no, Cdw" &m-. T~p. "M
DRAINAGE AREA MAP (979)TW-7743 Fp:(9M? -no
l
og~\
251
a
I
LEGEND
DRAINAGE AREA LABEL
150
126.6
ACREAGE
r
s r ~ i
ow \
Ap \
l` f19
~ I
i
I
I
I
1
250A
117.64
Al\
r~
EXHIBIT
AGGIELAND BUSINESS PARK, II mwm K~
B POST DEVELOPMENT ]p3 C,14g, Stot MbTno,. TahwySONA °
Colbp~ n 77B10
DRAINAGE AREA MAP °~~7~»:~`~:~N 1 7717
EXHIBIT C
Aggieland Business Park II
Hydraflow Channel Report
Channel Desien
Bottom Width =
2
Side Slopes =
4:1
Total Depth =
3.5 ft
Slope =
0.60%
n-value =
0.035
Storm Return
Period
Flow*
(cfs)
Depth
(ft)
Veloc
(ft/s)
Top Width
(ft)
Energy
(ft)
100-year
192.2
3.06
4.47
26.48
3.37
50-year
161.0
2.85
4.28
24.80
3.13
25-year
125.5
2.58
4.01
22.64
2.83
10-year
100.9
2.36
3.80
20.88
2.58
2-year
37.1
1.56
2.96
14.48
1.70
* The flowrates in the column labeled "Flow" were taken from the
values calculated in HEC-HMS
EXHIBIT D
Aggieland Business Park II
Hydraflow Pipe Report
Pipe Design
Size = 3 - 42 inch HDPE
Pipe Length = 285 ft
Slope = 0.50%
n-value = 0.012
Capacity (full)= 231.6 cfs
Storm Return
Period
Flow*
(cfs)
Avg Veloc
(ft/s)
Depth Up
(ft)
Depth Dn
(ft)
HGL Up
(ft)
HGL Down
(ft)
100-year
192.2
7.22
2.87
3.50
290.34
289.54
50-year
161.0
6.43
2.57
3.50
290.04
289.54
25-year
125.5
5.32
2.34
3.50
289.81
289.54
10-year
100.9
4.42
2.23
3.50
289.70
289.54
2-year
37.1
1.72
2.09
3.50
289.56
289.54
* The flowrates in the column labeled "Flow" were taken from the values
calculated in HEC-HMS
Exhibit E
HEC-HMS Pre-Development Analysis Report
Project: Aggieland II Simulation Run: Pre 2 yr
Start of Run: 01Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 2 yr
Compute Time: 26Aug2009, 15:39:03 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
37.1
01 Jan2007, 14:10
1.311
151
0.10059
14.3
01 Jan2007, 14:00
0.973
152
0.03922
69.8
01 Jan2007, 12:15
4.357
Existing Topo
0.33761
68.9
01 Jan2007, 12:20
1.563
Outfall
0.33761
68.9
01 Jan2007, 12:20
1.563
Project: Aggieland II Simulation Run: Pre 10 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 10 yr
Compute Time: 26Aug2009, 15:38:58 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
100.9
01 Jan2007, 14:05
3.354
151
0.10059
46.0
01 Jan2007, 13:50
2.787
152
0.03922
115.7
01 Jan2007, 12:15
7.244
Existing Topo
0.33761
156.5
01 Jan2007, 14:00
3.633
Outfall
0.33761
156.5
01 Jan2007, 14:00
3.633
Project: Aggieland II Simulation Run: Pre 25 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 25 yr
Compute Time: 26Aug2009, 15:39:00 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
125.5
01 Jan2007, 14:00
4.142
151
0.10059
58.7
01 Jan2007, 13:45
3.512
152
0.03922
131.5
01 Jan2007, 12:15
8.241
Existing Topo
0.33761
190.2
01 Jan2007, 14:10
4.425
Outfall
0.33761
190.2
01 Jan2007, 14:10
4.425
Project: Aggieland II Simulation Run: Pre 50 yr
Start of Run: 01Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 50 yr
Compute Time: 08Sep2009, 10:18:25 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
161.0
01 Jan2007, 14:00
5.290
151
0.10059
77.5
01 Jan2007, 13:45
4.584
152
0.03922
153.6
01 Jan2007, 12:15
9.636
Existing Topo
0.33761
236.1
01 Jan2007, 14:20
5.578
Outfall
0.33761
236.1
01 Jan2007, 14:20
5.578
Project: Aggieland II Simulation Run: Pre 100 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 26Aug2009, 15:38:55 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
192.2
01 Jan2007, 14:00
6.307
151
0.10059
94.2
01 Jan2007, 13:45
5.544
152
0.03922
172.5
01 Jan2007, 12:15
10.833
Existing Topo
0.33761
285.8
01 Jan2007, 14:15
6.597
Outfall
0.33761
285.8
01 Jan2007, 14:15
6.597
Project: Aggieland II
Simulation Run: Pre 100 yr Reservoir: Existing Topo
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 26Aug2009, 15:38:55 Control Specifications: 24 hr duration
Volume Units: IN
Computed Results
Peak Inflow :
300.9 (CFS)
Peak Outflow :
285.8 (CFS)
Total Inflow :
6.605 (IN)
Total Outflow :
6.597 (IN)
Date/Time of Peak Inflow :
Date/Time of Peak Outflow
Peak Storage :
Peak Elevation
01 Jan2007, 13:50
01 Jan2007, 14:15
5.6 (AC-FT)
292.05 (FT)
Exhibit F
HEC-HMS Post-Development Analysis Report
Project: Aggieland II Simulation Run: Post 2 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 2 yr
Compute Time: 08Sep2009, 10:32:05 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
34.5
01 Jan2007, 14:10
1.305
250B
0.00759
7.1
01 Jan2007, 12:15
1.891
250C
0.00641
13.9
01 Jan2007, 12:05
4.144
251
0.10059
14.3
01 Jan2007, 14:00
0.973
252
0.03922
69.8
01 Jan2007, 12:15
4.357
Det Pond
0.33761
83.4
01 Jan2007, 12:20
1.621
Jct 1
0.18380
34.5
01 Jan2007, 14:10
1.305
Jct 2
0.19139
35.2
01 Jan2007, 14:20
1.324
Outfall
0.33761
83.4
01 Jan2007, 12:20
1.621
Reach 1
0.18380
34.5
01 Jan2007, 14:20
1.300
Project: Aggieland II Simulation Run: Post 10 yr
Start of Run: 01Jan2007, 00:00 Basin Model:
End of Run: 02Jan2007, 00:05 Meteorologic Model:
Compute Time: 08Sep2009, 10:32:01 Control Specifications
Volume Units: IN
Post Dev
10 yr
24 hr duration
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
94.1
01 Jan2007, 14:00
3.345
250B
0.00759
16.5
01 Jan2007, 12:10
4.274
250C
0.00641
23.4
01 Jan2007, 12:05
7.010
251
0.10059
46.0
01 Jan2007, 13:50
2.787
252
0.03922
115.7
01 Jan2007, 12:15
7.244
Det Pond
0.33761
156.1
01 Jan2007, 12:20
3.703
Jct 1
0.18380
94.1
01 Jan2007, 14:00
3.345
Jct 2
0.19139
95.6
01 Jan2007, 14:10
3.372
Outfall
0.33761
156.1
01 Jan2007, 12:20
3.703
Reach 1
0.18380
94.1
01 Jan2007, 14:10
3.335
Project: Aggieland II Simulation Run: Post 25 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 25 yr
Compute Time: 08Sep2009, 10:32:03 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
117.0
01 Jan2007, 14:00
4.132
250B
0.00759
19.9
01 Jan2007, 12:10
5.156
250C
0.00641
26.7
01 Jan2007, 12:05
8.003
251
0.10059
58.7
01 Jan2007, 13:45
3.512
252
0.03922
131.5
01 Jan2007, 12:15
8.241
Det Pond
0.33761
186.5
01 Jan2007, 14:10
4.497
Jct 1
0.18380
117.0
01 Jan2007, 14:00
4.132
Jct 2
0.19139
118.8
01 Jan2007, 14:10
4.162
Outfall
0.33761
186.5
01 Jan2007, 14:10
4.497
Reach l
0.18380
117.0
01 Jan2007, 14:10
4.120
Project: Aggieland II Simulation Run: Post 50 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 50 yr
Compute Time: 08Sep2009, 10:32:07 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
150.2
01 Jan2007, 14:00
5.280
250B
0.00759
24.7
01 Jan2007, 12:10
6.422
250C
0.00641
31.3
01 Jan2007, 12:05
9.395
251
0.10059
77.5
01 Jan2007, 13:45
4.584
252
0.03922
153.6
01 Jan2007, 12:15
9.636
Det Pond
0.33761
236.0
01 Jan2007, 14:15
5.653
Jct 1
0.18380
150.2
01 Jan2007, 14:00
5.280
Jct 2
0.19139
152.2
01 Jan2007, 14:10
5.311
Outfall
0.33761
236.0
01 Jan2007, 14:15
5.653
Reach 1
0.18380
150.1
01 Jan2007, 14:10
5.266
Project: Aggieland II Simulation Run: Post 100 yr
Start of Run: 01Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 08Sep2009, 10:31:58 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
179.3
01 Jan2007, 14:00
6.295
250B
0.00759
28.9
01 Jan2007, 12:10
7.528
250C
0.00641
35.2
01 Jan2007, 12:05
10.590
251
0.10059
94.2
01 Jan2007, 13:45
5.544
252
0.03922
172.5
01 Jan2007, 12:15
10.833
Det Pond
0.33761
289.2
01 Jan2007, 14:05
6.676
Jct 1
0.18380
179.3
01 Jan2007, 14:00
6.295
Jct 2
0.19139
181.8
01 Jan2007, 14:05
6.329
Outfall
0.33761
289.2
01 Jan2007, 14:05
6.676
Reach 1
0.18380
179.2
01 Jan2007, 14:05
6.279
Project: Aggieland II
Simulation Run: Post 100 yr Reservoir: Det Pond
Start of Run: 01 Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 08Sep2009, 10:31:58 Control Specifications: 24 hr duration
Volume Units: IN
Computed Results
Peak Inflow :
290.6 (CFS)
Peak Outflow :
289.2 (CFS)
Total Inflow :
6.699 (IN)
Total Outflow :
6.676 (IN)
Date/Time of Peak Inflow :
Date/Time of Peak Outflow
Peak Storage :
Peak Elevation
01Jan2007, 13:55
01 Jan2007, 14:05
3.9 (AC-FT)
292.06 (FT)
Executive Summary Report
Aggieland Business Park II
College Station, Texas
September, 2009
ENGINEER Civil Development, Ltd. - Kent Laza, P.E. (klaza@cdlbcs.com)
P.O. Box 11929
College Station, Texas 77842
Phone: (979) 764-7743 Fax: (979) 764-7759
OWNER/DEVELOPER 60-Jones, LLC
6161 Imperial Loop, Suite 101
College Station, Texas 77840
Phone: (979) 571-4341
GENERAL This project is located on the northeast corner of Jones Road and FM 60 and is part
of the Aggieland Business Park II development project. The site is anticipated to
be developed as a convenience store although no formal plans have been
developed at this time. The general stormwater plan consists of improving a
natural drainage channel that runs through the upper portion of the lot, and the
installation of 3-42" storm pipes to carry water through the middle portion of the
site where the future buildings and driveways will be located.
HYDROLOGIC CHARACTERISTICS & EXISTING CONDITIONS
The site has recently been cleared, but the previous land cover was dense brush
and trees. The soil is classified as a sandy loam (Soil Group B) by the USGS Soil
Maps of Brazos County. The drainage basin that encompasses this property
includes a total of about 126 acres as shown in Exhibit A. Runoff from this basin
flows in a southerly direction, and enters the property through an existing drainage
channel. Immediately downstream of the site is FM 60, which has two box culverts
in close proximity to each other to carry the runoff under the roadway. One is a
5'x 5' culvert and the other is a 4'x 2' culvert. A second drainage basin
encompassing approximately 64 acres and located immediately adjacent to the first
basin also drains to the same crossing point along the TxDOT right-of-way and
contributes to the flow under FM 60. A third basin located west of Jones Road and
encompassing about 25 acres flows to these culverts along the TxDOT right-of-
way as well.
Calculations indicate that the two culverts under FM 60 were not designed to pass
runoff from these three basins during a 100-yr rainfall event. As a result, water
pools upstream of FM 60 and builds up until it flows over the roadway. The
roadway serves as a dam and the resulting pool functions as a detention pond
upstream of the roadway where the proposed site is located.
Under the anticipated development plan, the existing channel through the site will
be improved for a length of approximately 160 feet, then be directed into 3-42"
storm pipes to pass water through the site. The anticipated development plan will
require that the site be raised sufficiently to prevent it from being inundated during
heavy rainfall events, but some storage will still be maintained along the channel
and immediately adjacent to the TxDOT right-of-way.
12
The analysis that follows takes into account the storage provided by the FM 60
roadway in both the pre- and post-development scenarios. Detention calculations
for the post-development scenario were made using assumptions regarding the
final grading along the stream and the front of the site. No additional detention
facility is planned.
Applicable Exhibits: Exhibit A - Drainage Area Map (pre-development conditions)
Exhibit B - Drainage Area Map (post-development conditions)
CHANNEL DESIGN INFORMATION
Design Software
Hydraflow Express Extension for Autocad 2010
Manning's n Value:
0.035 (dense grass)
Slope:
0.6%
Bottom Width:
2 ft
Top Width:
30 ft
Depth:
3.5 ft
Side Slopes:
4:1
Summary of Channel Design Analysis:
100 year flow rate: 192.2 cfs
Velocity: 4.47 ft/s
Depth: 3.06 ft
Top Width: 26.48 ft
* The flowrate used for the channel design is taken from 100 year pre-development peak flowrate for
Drainage Area 150 in HEC-HMS. This value can be found in Exhibit A.
Applicable Exhibits: Exhibit C - Hydraflow Channel Design Report
STORM SEWER DESIGN INFORMATION
Design Software: Hydraflow Storm Sewer Extension for Autocad 2010
Pipe Size: 42 inch, HPDE
Manning's n-value: 0.012
Pipe Length: 285 ft
Slope: 0.5%
Summary of Storm Sewer Design Anal
Pipe Capacity: 231.6 cfs
100 year flow rate: 192.2 cfs
Velocity: 7.22 ft/s
Applicable Exhibits: Exhibit D - Hydraflow Pipe Design Report
DETENTION ANALYSIS
Design Software:
Methodology:
Design Storms:
HEC-HMS Version 3.3
SCS Unit Hydrograph
2, 10, 25, 50, 100-year storms
Input Data
Pre-Develeopment Conditions
Lag
Drainage ge
Area CN
o
Time
Imperv
(min.'
150
126.60
65.7
0.0
109
151
64.38
60.0
0.0
94
152
25.10
92.0
85.0
13
Post-Develeopment Conditions
Lag
Drainage
Length
Area
i
CN
%
Time
Area
-
Imperv
(feet)
(acres)
min.
250A
117.64
.
.
.
66.1
0.0
108
250B
.
.
.
.
.
.
.
.
.
4.86
,
73.2
0.0
.
10
.
250C
,
4.10
87.4
85.0
e
5
251
.
64.4
60.0
0.0
94
.
252
.
25.1
92.0
_
85.0
13
*Reach 1
.
.
158
.
84.0
.
5
.
.
.
.
*Reach 2
285
99.0
4
* Reaches I and 2 were combined in HEC-HMS into a single reach with a total lag
time of 9 minutes.
HEC-HMS Analysis Summary
The pre- and post-development flowrates were analyzed immediately downstream
of the FM 60 culverts. This point is referred to as the Outfall in the HEC-HMS
model. The following table shows the peak flowrates at the Outfall point.
C
di
i
2 r
10 r
25 r
50 r
100 r
on
t
on
cfs
cfs
cfs
cfs
cfs
Pre Dev
68.9
156.5
190.2
236.1
285.8
Post Dev
83.4
156.1
186.5
236.0
289.2
Change in
Flowrate
14.5
-0.4
-3.7
-0.1
3.4
Change in Water
Surface Elev.
0.13
0.00
0.00
0.00
0.01**
The results for the change in water surface elevations for the 100 year storm can be
found in Exhibit F.
CONCLUSIONS
From the HEC-HMS analysis shown above, we conclude that the FM 60 roadway
provides a level of detention resulting from the culvert sizes that were installed
when the facility was built. These culverts were not designed to pass the 100-yr
event, so we presume that TxDOT anticipated the pooling of runoff upstream of
the roadway during large rainfall events. When analyzed under both pre- and post-
development scenarios, this detention provides a reduction in runoff from the mid-
range storm events, but allows slightly higher peak flows during the 2-yr and 100-
yr events.
The slightly higher peak flowrate for the 100-yr event represents about a 1%
increase from the pre-development scenario, which computes to be 0.01 feet (about
1/8`h of an inch) increase in the water surface elevation over the FM 60 roadway.
This is a negligible amount of increase that will have no noticeable impact on
downstream properties. As a result, we conclude that additional detention facilities
are not necessary for the development of this site.
Applicable Exhibits: Exhibit E - HEC-HMS Analysis Report (pre-development conditions)
Exhibit F - HEC-HMS Analysis Report (post-development conditions)
l
151
64.
C)
LEGEND
DRAINAGE AREA LABEL
150
126.6
ACREAGE
. V
r
\ t
t ( !
j 1
r
\
~~w \
A \
e~
26.6
r1 ; a
D0i11"T AGGIELAND BUSINESS PARK, fl A(,i°a//ePSQrimvrj,w(A ,E w~ orax ,,,E
0
A 3033 N•rvaY MXO.e1 ..M 3pM
PRE DEVELOPMENT Co1MpeS~•~p^*~-nW
v O. Bm 11M CdWp SWw Tm••nW
DRAINAGE AREA MAP "79"°`.7713 F°'$N" 77 °
t
`i
l
` I
i
J/ P
0
I
~i
jt f
oy, \
I
1
250A
117.64
u
l
r ~
r F
251
64
LEGEND
DRAINAGE AREA LABEL
150
126.6
ACREAGE
,wow
EXHIBIT AGGIELAND BUSINESS PARK, II valJsvswo Hmas4L x°. lint
B POST DEVELOPMENT ]03C'lwo. MMO~~II-"77 SOUM °
Col- Station, T „!10
DRAINAGE AREA MAP °rveoc is n13"-(eni 1841,N
EXHIBIT C
Aggieland Business Park II
Hydraflow Channel Report
Channel Design
Bottom Width =
2
Side Slopes =
4:1
Total Depth =
3.5 ft
Slope =
0.60%
n-value =
0.035
Storm Return
Period
Flow*
(cfs)
Depth
(ft)
Veloc
(ft/s)
Top Width
(ft)
Energy
(ft)
100-year
192.2
3.06
4.47
26.48
3.37
50-year
161.0
2.85
4.28
24.80
3.13
25-year
125.5
2.58
4.01
22.64
2.83
10-year
100.9
2.36
3.80
20.88
2.58
2- ear
37.1
1.56
2.96
14.48
1.70
* The flowrates in the column labeled "Flow" were taken from the
values calculated in HEC-HMS
EXHIBIT D
Aggieland Business Park II
Hydraflow Pipe Report
Pine Design
Size = 3 - 42 inch HDPE
Pipe Length = 285 ft
Slope= 0.50%
n-value = 0.012
Capacity (full)= 231.6 cfs
Storm Return
Period
Flow*
(cfs)
Avg Veloc
(ft/s)
Depth Up
(ft)
Depth Dn
(ft)
HGL Up
(ft)
HGL Down
(ft)
100-year
.......192:2......
~..2
.........2:87........
. 3.50
290.34
289.54
50-year
161.0
6.43
2.57
3.50
290.04
289.54
25-year
.......125 :5......
5 :32...........
:34.........
3.5.........
....289; 81.....
.......289:54.......
10-year
100.9
4.42
2.23
3.50
289.70
289.54
2-year
37.1
1.72
2.09
3.50
289.56
289.54
* The flowrates in the column labeled "Flow" were taken from the values
calculated in HEC-HMS
Exhibit E
HEC-HMS Pre-Development Analysis Report
Project: Aggieland II Simulation Run: Pre 2 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 2 yr
Compute Time: 26Aug2009, 15:39:03 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
37.1
01 Jan2007, 14:10
1.31
151
0.10059
14.3
01 Jan2007, 14:00
0.97
152
0.03922
69.8
01 Jan2007, 12:15
4.36
Existing Topo
0.33761
68.9
01 Jan2007, 12:20
1.56
Outfall
0.33761
68.9
01 Jan2007, 12:20
1.56
Project: Aggieland II Simulation Run: Pre 10 yr
Start of Run: 01Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 10 yr
Compute Time: 26Aug2009, 15:38:58 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
100.9
01 Jan2007, 14:05
3.35
151
0.10059
46.0
01 Jan2007, 13:50
2.79
152
0.03922
115.7
01 Jan2007, 12:15
7.24
Existing Topo
0.33761
156.5
01 Jan2007, 14:00
3.63
Outfall
0.33761
156.5
01 Jan2007, 14:00
3.63
Project: Aggieland II Simulation Run: Pre 25 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 25 yr
Compute Time: 26Aug2009, 15:39:00 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
125.5
01 Jan2007, 14:00
4.14
151
0.10059
58.7
01 Jan2007, 13:45
3.51
152
0.03922
131.5
01 Jan2007, 12:15
8.24
Existing Topo
0.33761
190.2
01 Jan2007, 14:10
4.43
Outfall
0.33761
190.2
01 Jan2007, 14:10
4.43
Project: Aggieland II Simulation Run: Pre 50 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 50 yr
Compute Time: 26Aug2009, 15:39:06 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
161.0
01 Jan2007, 14:00
5.29
151
0.10059
77.5
01 Jan2007, 13:45
4.58
152
0.03922
153.6
01 Jan2007, 12:15
9.64
Existing Topo
0.33761
236.1
01 Jan2007, 14:20
5.58
Outfall
0.33761
236.1
01 Jan2007, 14:20
5.58
Project: Aggieland II Simulation Run: Pre 100 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 26Aug2009, 15:38:55 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
192.2
01 Jan2007, 14:00
6.31
151
0.10059
94.2
01 Jan2007, 13:45
5.54
152
0.03922
172.5
01 Jan2007, 12:15
10.83
Existing Topo
0.33761
285.8
01 Jan2007, 14:15
6.60
Outfall
0.33761
285.8
01 Jan2007, 14:15
6.60
Exhibit F
HEC-HMS Post-Development Analysis Report
Project: Aggieland II Simulation Run: Post 2 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 2 yr
Compute Time: 08Sep2009, 10:32:05 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
34.5
01 Jan2007, 14:10
1.30
250B
0.00759
7.1
01 Jan2007, 12:15
1.89
250C
0.00641
13.9
01 Jan2007, 12:05
4.14
251
0.10059
14.3
01 Jan2007, 14:00
0.97
252
0.03922
69.8
01 Jan2007, 12:15
4.36
Det Pond
0.33761
83.4
01 Jan2007, 12:20
1.62
Jct 1
0.18380
34.5
01 Jan2007, 14:10
1.30
Jct 2
0.19139
35.2
01 Jan2007, 14:20
1.32
Outfall
0.33761
83.4
01 Jan2007, 12:20
1.62
Reach 1
0.18380
34.5
01 Jan2007, 14:20
1.30
Project: Aggieland II Simulation Run: Post 10 yr
Start of Run: 01Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 10 yr
Compute Time: 08Sep2009, 10:32:01 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
94.1
01 Jan2007, 14:00
3.34
250B
0.00759
16.5
01 Jan2007, 12:10
4.27
250C
0.00641
23.4
01 Jan2007, 12:05
7.01
251
0.10059
46.0
01 Jan2007, 13:50
2.79
252
0.03922
115.7
01 Jan2007, 12:15
7.24
Det Pond
0.33761
156.1
01 Jan2007, 12:20
3.70
Jct 1
0.18380
94.1
01 Jan2007, 14:00
3.34
Jct 2
0.19139
95.6
01 Jan2007, 14:10
3.37
Outfall
0.33761
156.1
01 Jan2007, 12:20
3.70
Reach 1
0.18380
94.1
01 Jan2007, 14:10
3.33
Project: Aggieland II Simulation Run: Post 25 yr
Start of Run: 01Jan2007, 00:00 Basin Model:
End of Run: 02Jan2007, 00:05 Meteorologic Model:
Compute Time: 08Sep2009, 10:32:03 Control Specifications
Volume Units: IN
Post Dev
25 yr
24 hr duration
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
117.0
01 Jan2007, 14:00
4.13
250B
0.00759
19.9
01 Jan2007, 12:10
5.16
250C
0.00641
26.7
01 Jan2007, 12:05
8.00
251
0.10059
58.7
01 Jan2007, 13:45
3.51
252
0.03922
131.5
01 Jan2007, 12:15
8.24
Det Pond
0.33761
186.5
01 Jan2007, 14:10
4.50
Jct 1
0.18380
117.0
01 Jan2007, 14:00
4.13
Jct 2
0.19139
118.8
01 Jan2007, 14:10
4.16
Outfall
0.33761
186.5
01 Jan2007, 14:10
4.50
Reach 1
0.18380
117.0
01 Jan2007, 14:10
4.12
NI Project: Aggieland II Simulation Run: Post 50 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 50 yr
Compute Time: 08Sep2009, 10:32:07 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
150.2
01 Jan2007, 14:00
5.28
250B
0.00759
24.7
01 Jan2007, 12:10
6.42
250C
0.00641
31.3
01 Jan2007, 12:05
9.39
251
0.10059
77.5
01 Jan2007, 13:45
4.58
252
0.03922
153.6
01 Jan2007, 12:15
9.64
Det Pond
0.33761
236.0
01 Jan2007, 14:15
5.65
Jct 1
0.18380
150.2
01 Jan2007, 14:00
5.28
Jct 2
0.19139
152.2
01 Jan2007, 14:10
5.31
Outfall
0.33761
236.0
01 Jan2007, 14:15
5.65
Reach l
0.18380
150.1
01 Jan2007, 14:10
5.27
1
Project: Aggieland II Simulation Run: Post 100 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 08Sep2009, 10:31:58 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
179.3
01 Jan2007, 14:00
6.30
250B
0.00759
28.9
01 Jan2007, 12:10
7.53
250C
0.00641
35.2
01 Jan2007, 12:05
10.59
251
0.10059
94.2
01 Jan2007, 13:45
5.54
252
0.03922
172.5
01 Jan2007, 12:15
10.83
Det Pond
0.33761
289.2
01 Jan2007, 14:05
6.68
Jct 1
0.18380
179.3
01 Jan2007, 14:00
6.30
Jct 2
0.19139
181.8
01 Jan2007, 14:05
6.33
Outfall
0.33761
289.2
01 Jan2007, 14:05
6.68
Reach 1
0.18380
179.2
01 Jan2007, 14:05
6.28
Project: Aggieland II
Simulation Run: Pre 100 yr Reservoir: Existing Topo
Start of Run: 01Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 26Aug2009, 15:38:55 Control Specifications: 24 hr duration
Volume Units: IN
Computed Results
Peak Inflow :
300.92 (CFS)
Date/Time of Peak Inflow :
01Jan2007, 13:50
Peak Outflow :
285.82 (CFS)
Date/Time of Peak Outflow :
01Jan2007, 14:15
Total Inflow :
6.605 (IN)
Peak Storage :
5.6 (AC-FT)
Total Outflow :
6.597 (IN)
Peak Elevation :
292.05 (FT)
Project: Aggieland II
Simulation Run: Post 100 yr Reservoir: Det Pond
Start of Run: 01Jan2007, 00:00 Basin Model:
End of Run: 02Jan2007, 00:05 Meteorologic Model:
Compute Time: 08Sep2009, 10:31:58 Control Specifications:
Volume Units: IN
Computed Results
Peak Inflow :
290.56 (CFS)
Peak Outflow :
289.19 (CFS)
Total Inflow :
6.699 (IN)
Total Outflow :
6.676 (IN)
Date/Time of Peak Inflow :
Date/Time of Peak Outflow
Peak Storage :
Peak Elevation
Post Dev
100 yr
24 hr duration
01Jan2007, 13:55
01 Jan2007, 14:05
3.9 (AC-FT)
292.06 (FT)
Drainage Report
for
Aggieland Business Park II
College Station, Texas
September, 2009
Developer:
60-Jones, LLC
6161 Imperial Lop, Suite 101
College Station, Texas 77840
(979) 571-4341
Engineer:
Civil Development, Ltd.
2033 Harvey Mitchell Parkway South
College Station, Texas 77840
(979) 764-7743
,6P-/F I 2`lj 40
a
Executive Summary Report
Aggieland Business Park II
College Station, Texas
September, 2009
ENGINEER Civil Development, Ltd. - Kent Laza, P.E. (klaza@cdlbcs.com)
P.O. Box 11929
College Station, Texas 77842
Phone: (979) 764-7743 Fax: (979) 764-7759
OWNER/DEVELOPER 60-Jones, LLC
6161 Imperial Loop, Suite 101
College Station, Texas 77840
Phone: (979) 571-4341
GENERAL This project is located on the northeast corner of Jones Road and FM 60 and is part
of the Aggieland Business Park II development project. The site is anticipated to
be developed as a convenience store although no formal plans have been
developed at this time. The general stormwater plan consists of improving a
natural drainage channel that runs through the upper portion of the lot, and the
installation of 3-42" storm pipes to carry water through the middle portion of the
site where the future buildings and driveways will be located.
HYDROLOGIC CHARACTERISTICS & EXISTING CONDITIONS
The site has recently been cleared, but the previous land cover was dense brush
and trees. The soil is classified as a sandy loam (Soil Group B) by the USGS Soil
Maps of Brazos County. The drainage basin that encompasses this property
includes a total of about 126 acres as shown in Exhibit A. Runoff from this basin
flows in a southerly direction, and enters the property through an existing drainage
channel. Immediately downstream of the site is FM 60, which has two box culverts
in close proximity to each other to carry the runoff under the roadway. One is a
5'x 5' culvert and the other is a 4'x 2' culvert. A second drainage basin
encompassing approximately 64 acres and located immediately adjacent to the first
basin also drains to the same crossing point along the TxDOT right-of-way and
contributes to the flow under FM 60. A third basin located west of Jones Road and
encompassing about 25 acres flows to these culverts along the TxDOT right-of-
way as well.
Calculations indicate that the two culverts under FM 60 were not designed to pass
runoff from these three basins during a 100-yr rainfall event. As a result, water
pools upstream of FM 60 and builds up until it flows over the roadway. The
roadway serves as a dam and the resulting pool functions as a detention pond
upstream of the roadway where the proposed site is located.
Under the anticipated development plan, the existing channel through the site will
be improved for a length of approximately 160 feet, then be directed into 3-42"
storm pipes to pass water through the site. The anticipated development plan will
require that the site be raised sufficiently to prevent it from being inundated during
heavy rainfall events, but some storage will still be maintained along the channel
and immediately adjacent to the TxDOT right-of-way.
The analysis that follows takes into account the storage provided by the FM 60
roadway in both the pre- and post-development scenarios. Detention calculations
for the post-development scenario were made using assumptions regarding the
final grading along the stream and the front of the site. No additional detention
facility is planned.
Applicable Exhibits: Exhibit A - Drainage Area Map (pre-development conditions)
Exhibit B - Drainage Area Map (post-development conditions)
CHANNEL DESIGN INFORMATION
Design Software Hydraflow Express Extension for Autocad 2010
Manning's n Value: 0.035 (dense grass)
Slope:
0.6%
Bottom Width:
2 ft
Top Width:
30 ft
Depth:
3.5 ft
Side Slopes:
4:1
Summarv of Channel Designn Analvsis:
100 year flow rate: 192.2 cfs
Velocity: 4.47 ft/s
Depth: 3.06 ft
Top Width: 26.48 ft
* The flowrate used for the channel design is taken from 100 year pre-development peak flowrate for
Drainage Area 150 in HEC-HMS. This value can be found in Exhibit A.
Applicable Exhibits: Exhibit C - Hydraflow Channel Design Report
STORM SEWER DESIGN INFORMATION
Design Software: Hydraflow Storm Sewer Extension for Autocad 2010
Pipe Size: 42 inch, HPDE
Manning's n-value: 0.012
Pipe Length: 285 ft
Slope: 0.5%
Summary of Storm Sewer Design Analysis.
Pipe Capacity: 231.6 cfs
100 year flow rate: 192.2 cfs
Velocity: 7.22 ft/s
Applicable Exhibits: Exhibit D - Hydraflow Pipe Design Report
CONCLUSIONS
From the HEC-HMS analysis shown above, we conclude that the FM 60 roadway
provides a level of detention resulting from the culvert sizes that were installed
when the facility was built. These culverts were not designed to pass the 100-yr
event, so we presume that TxDOT anticipated the pooling of runoff upstream of
the roadway during large rainfall events. When analyzed under both pre- and post-
development scenarios, this detention provides a reduction in runoff from the mid-
range storm events, but allows slightly higher peak flows during the 2-yr and 100-
yr events.
The slightly higher peak flowrate for the 100-yr event represents about a 1%
increase from the pre-development scenario, which computes to be 0.01 feet (about
1/8t' of an inch) increase in the water surface elevation over the FM 60 roadway.
This is a negligible amount of increase that will have no noticeable impact on
downstream properties. As a result, we conclude that additional detention facilities
are not necessary for the development of this site.
Applicable Exhibits: Exhibit E - HEC-HMS Analysis Report (pre-development conditions)
Exhibit F - HEC-HMS Analysis Report (post-development conditions)
X
o~
1
'-Iil
fig Q_
i o\
IN, 1
151
\ 64. 8 \
26.6
150
126.6
ACREAGE i
LEGEND
DRAINAGE AREA LABEL
~'"ate
°a'B'r AGGIELAND BUSINESS PARK, II R
a
A PRE DEVELOPMENT 2U33 M~rve MM1OM1etl P_,wy &wM
ColMpe 81~Ibn, Tap new
P.C. Sm 11no, Cdw" &m-. T~p. "M
DRAINAGE AREA MAP (979)TW-7743 Fp:(9M? -no
l
og~\
251
a
I
LEGEND
DRAINAGE AREA LABEL
150
126.6
ACREAGE
r
s r ~ i
ow \
Ap \
l` f19
~ I
i
I
I
I
1
250A
117.64
Al\
r~
EXHIBIT
AGGIELAND BUSINESS PARK, II mwm K~
B POST DEVELOPMENT ]p3 C,14g, Stot MbTno,. TahwySONA °
Colbp~ n 77B10
DRAINAGE AREA MAP °~~7~»:~`~:~N 1 7717
EXHIBIT C
Aggieland Business Park II
Hydraflow Channel Report
Channel Desien
Bottom Width =
2
Side Slopes =
4:1
Total Depth =
3.5 ft
Slope =
0.60%
n-value =
0.035
Storm Return
Period
Flow*
(cfs)
Depth
(ft)
Veloc
(ft/s)
Top Width
(ft)
Energy
(ft)
100-year
192.2
3.06
4.47
26.48
3.37
50-year
161.0
2.85
4.28
24.80
3.13
25-year
125.5
2.58
4.01
22.64
2.83
10-year
100.9
2.36
3.80
20.88
2.58
2-year
37.1
1.56
2.96
14.48
1.70
* The flowrates in the column labeled "Flow" were taken from the
values calculated in HEC-HMS
EXHIBIT D
Aggieland Business Park II
Hydraflow Pipe Report
Pipe Design
Size = 3 - 42 inch HDPE
Pipe Length = 285 ft
Slope = 0.50%
n-value = 0.012
Capacity (full)= 231.6 cfs
Storm Return
Period
Flow*
(cfs)
Avg Veloc
(ft/s)
Depth Up
(ft)
Depth Dn
(ft)
HGL Up
(ft)
HGL Down
(ft)
100-year
192.2
7.22
2.87
3.50
290.34
289.54
50-year
161.0
6.43
2.57
3.50
290.04
289.54
25-year
125.5
5.32
2.34
3.50
289.81
289.54
10-year
100.9
4.42
2.23
3.50
289.70
289.54
2-year
37.1
1.72
2.09
3.50
289.56
289.54
* The flowrates in the column labeled "Flow" were taken from the values
calculated in HEC-HMS
Exhibit E
HEC-HMS Pre-Development Analysis Report
Project: Aggieland II Simulation Run: Pre 2 yr
Start of Run: 01Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 2 yr
Compute Time: 26Aug2009, 15:39:03 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
37.1
01 Jan2007, 14:10
1.311
151
0.10059
14.3
01 Jan2007, 14:00
0.973
152
0.03922
69.8
01 Jan2007, 12:15
4.357
Existing Topo
0.33761
68.9
01 Jan2007, 12:20
1.563
Outfall
0.33761
68.9
01 Jan2007, 12:20
1.563
Project: Aggieland II Simulation Run: Pre 10 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 10 yr
Compute Time: 26Aug2009, 15:38:58 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
100.9
01 Jan2007, 14:05
3.354
151
0.10059
46.0
01 Jan2007, 13:50
2.787
152
0.03922
115.7
01 Jan2007, 12:15
7.244
Existing Topo
0.33761
156.5
01 Jan2007, 14:00
3.633
Outfall
0.33761
156.5
01 Jan2007, 14:00
3.633
Project: Aggieland II Simulation Run: Pre 25 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 25 yr
Compute Time: 26Aug2009, 15:39:00 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
125.5
01 Jan2007, 14:00
4.142
151
0.10059
58.7
01 Jan2007, 13:45
3.512
152
0.03922
131.5
01 Jan2007, 12:15
8.241
Existing Topo
0.33761
190.2
01 Jan2007, 14:10
4.425
Outfall
0.33761
190.2
01 Jan2007, 14:10
4.425
Project: Aggieland II Simulation Run: Pre 50 yr
Start of Run: 01Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 50 yr
Compute Time: 08Sep2009, 10:18:25 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
161.0
01 Jan2007, 14:00
5.290
151
0.10059
77.5
01 Jan2007, 13:45
4.584
152
0.03922
153.6
01 Jan2007, 12:15
9.636
Existing Topo
0.33761
236.1
01 Jan2007, 14:20
5.578
Outfall
0.33761
236.1
01 Jan2007, 14:20
5.578
Project: Aggieland II Simulation Run: Pre 100 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 26Aug2009, 15:38:55 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
150
0.19780
192.2
01 Jan2007, 14:00
6.307
151
0.10059
94.2
01 Jan2007, 13:45
5.544
152
0.03922
172.5
01 Jan2007, 12:15
10.833
Existing Topo
0.33761
285.8
01 Jan2007, 14:15
6.597
Outfall
0.33761
285.8
01 Jan2007, 14:15
6.597
Project: Aggieland II
Simulation Run: Pre 100 yr Reservoir: Existing Topo
Start of Run: 01 Jan2007, 00:00 Basin Model: Pre Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 100 yr
Compute Time: 26Aug2009, 15:38:55 Control Specifications: 24 hr duration
Volume Units: IN
Computed Results
Peak Inflow :
300.9 (CFS)
Peak Outflow :
285.8 (CFS)
Total Inflow :
6.605 (IN)
Total Outflow :
6.597 (IN)
Date/Time of Peak Inflow :
Date/Time of Peak Outflow
Peak Storage :
Peak Elevation
01 Jan2007, 13:50
01 Jan2007, 14:15
5.6 (AC-FT)
292.05 (FT)
Exhibit F
HEC-HMS Post-Development Analysis Report
Project: Aggieland II Simulation Run: Post 2 yr
Start of Run: 01 Jan2007, 00:00 Basin Model: Post Dev
End of Run: 02Jan2007, 00:05 Meteorologic Model: 2 yr
Compute Time: 08Sep2009, 10:32:05 Control Specifications: 24 hr duration
Volume Units: IN
Hydrologic
Element
Drainage Area
(M12)
Peak Discharge
(CFS)
Time of Peak
Volume
(IN)
250A
0.18380
34.5
01 Jan2007, 14:10
1.305
250B
0.00759
7.1
01 Jan2007, 12:15
1.891
250C
0.00641
13.9
01 Jan2007, 12:05
4.144
251
0.10059
14.3
01 Jan2007, 14:00
0.973
252
0.03922
69.8
01 Jan2007, 12:15
4.357
Det Pond
0.33761
83.4
01 Jan2007, 12:20
1.621
Jct 1
0.18380
34.5
01 Jan2007, 14:10
1.305
Jct 2
0.19139
35.2
01 Jan2007, 14:20
1.324
Outfall
0.33761
83.4
01 Jan2007, 12:20
1.621
Reach 1
0.18380
34.5
01 Jan2007, 14:20
1.300