HomeMy WebLinkAboutDrainage Analysis July 2008-
COPPER FALLS EXECUTIVE SUITES
DRAINAGE ANALYSIS
July 2008
Prepared for:
1999 PROPERTIES GP, LLC
51 1 UNIVERSITY DRIVE EAST, SUITE 204
COLLEGE STATION, TX 77840
(979)260-6963
Submitted to
ITV F LLEGE TA I N
11. e hea,.t of tlu Rmarch Valley
By
MITCHELL
MM
MORGAN
ENGINEERS & CONSTRUCTORS
511 UNIVERSITY DRIVE, SUITE 204
COLLEGE STATION, TX 77840
OFFI CE (979) 260-6963
FAX (979) 260-3564
CERTIFICATION
This report for the drainage design for the new Copper Falls Executive Suites development
was prepared under my supervision in accordance with provisions of the Bryan/College
Station Unified Drainage Design Guidelines for the owners of the property. All licenses and
permits required by any and all state and federal regulatory agencies for the proposed
drainage improvements have been issued .
,,., ........ ,,,,,,,,
--=-"':"'\E. OF/~\\\ .: '\I>-. . . . . . . . . . :..t-Jf •• , .i' .,/".) ....... ~· .. ..:_..,IS' ,,
~* ... ~ ... -tr~ ~ ...... ·: ......................... :\.~.~
fl! ... ~f30NIC,i, J.B. MORGAN ~ ~ ~:.. ········7·:;5·8-r; .. ····-:.:;rfJ
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;/ ~ · . ., /STE",.· ~ .::" 7/ 1A Do '1•\f ~10NAl.·€.~~-==-,,,,,,, ..........
Veronica J.B. Morgan, P.E., C.F.M .
Registered Professional Engineer
State of Texas No. 77689
Copper Falls Executive Suites Drainage Analysis
Introduction
The purpose of this drainage report is to present an analysis of the necessary dra inage
infrastructure for the proposed new Copper Falls Executive Suites development. The new
development site will be located in south College Station, along State Highway 6
Southbound Frontage Road and Deacon exit. The drainage report provides analysis for the
infrastructure required to faci litate attenuation and removal of both onsite flow and flow
contributions from offsite drainage areas, including AllSize Storage and areas east of
Southbound Frontage Road that drain to the tributary of Bee Creek that travels through the
project site.
GENERAL LOCATION & DESCRIPTION
The Copper Falls Executive Suites will be located in College Station, Texas, south of Mile
Drive, north of Texas Avenue and west of State Hwy 6 Southbound Frontage Road. The
1.62 ac site is currently undeveloped, adjacent to residential and commercial developments.
The development is situated within the bottom third of the Bee Creek Drainage Basin,
containing a tributary to Bee Creek. The site w ill gain access from the SH6 west frontage,
which is east and adjacent to the project site. The proposed development includes an office
building intended for business/commercial use. Additionally, the development will include
the construction of one berm that will provide detention storage along with a sma ll amount
of stormsewer system. Development will be confined in the southern area of the site,
leaving the majority of the site undeveloped. Please see Exhibit 1 for the General Location
Map.
DRAINAGE DESIGN CRITERIA
All drainage design is in accordance with the 2008 Bryan/College Station Unified
Stormwater Guidelines. As such:
• Design rainstorm events consist of the 5-, 10-, 25-, 50-and 100-year, 24 hour
duration hypothetical frequency storm events in order to analyze the effectiveness
of the detention facilities as well as capture conservative peak flow values.
• Flow calculations are based on the Soil Conservation Service Curve Number Loss
Method. Curve Numbers are based on soil type and land use in the subbasins and
impervious cover data was used to calculate percent impervious cover data.
• The target peak runoff rate for the post-development condition is that of the pre-
development peak flow rate at the study confluence .
The analysis confluence for the study is identified as a tributary of Bee Creek located on the
West property line (STP2). The effects of the proposed development at the study confluence
will be considered in the determining whether the design objectives were satisfied.
PRIMARY DRAINAGE BASIN DESCRIPTION
The proposed project site is located within the Bee Creek Drainage Basin. As demonstrated
in Exhibit 2, no portion of the property lies within the regulatory 100-year floodplain per
the Federal Emergency Management Agency (FEMA) Flood Insurance Rate Map (FIRM)
panel 0182(, with an effective data of July 2, 1992.
Two major offsite drainage sources will supply runoff to the site . These drainage sources
contribute flow to the site at locations on the south and east property lines. Drainage areas
Copper Falls Executive Suites
Drainage Report
east of the site drain to a culvert contributing to the tributary of Bee Creek on the east
property line. These drainage areas will be the main runoff source to the tributary located
on the property. The AllSize Storage Development located south of the site uses detention
facilities and releases onto the site along the south property line. These two drainage areas
will be included, along with the onsite drainage areas to define the total, 40.3 acre
drainage basin used in hydraulic modeling, as shown in Exhibit 3. 1 Drainage Area Map.
The majority of the onsite drainage areas drain through the tributary within the property
lines to the outfall point. Subbasin EA-B drains through a natural earth ditch to the outfall
point. Therefore, the outflow point will contain two contributing drainage flows. The site
has one outfall point located where the tributary to Bee Creek and the natural earth ditch
connect. The site consists of grasslands and approximately 90% tree cover. Percent
impervious for the site will differentiate the pre-development from the post-development
conditions. The project drainage basin consisted of type D soil and had a curve number 75
for Antecedent Moisture Condition (AMC) II.
STORMWATER RUNOFF ANALYSIS
General Information
For the purpose of this analysis, frequency storms were generated for all studied rainfall
events using the depth-duration data taken from the National Weather Service TP-40. The
storms generated were used for both the pre-and post-development analyses. Pre-and
Post-development hydraulic modeling was performed for all specified rainfall events and
included the required 5-through 100-year rainfall events specified by Bryan/College Station
USDG . Results can be found in Exhibits 8.2-8.6. Runoff losses due to infiltration and initial
abstractions were calculated using the SCS (NRCS) Curve Number Loss Method. These
parameters were calculated using the Curve Number, established from soil type in the
Brazos County Soil Survey, and percentage of impervious cover in the basins. Direct runoff
hydrographs were generated using the calculated runoff depths and the SCS dimensionless
unit hydrograph. See Exhibit 8.1A for basin parameters used in hydraulic modeling.
Pre-Development Drainage Basin
The pre-development analysis for Copper Falls Executive Suites included a total of nine
drainage subbasins, six of which accounted entirely for offsite runoff. As mentioned above,
two offsite drainage sources contributed flow to the project site. One drainage source will
have a previously defined drainage area and outworks structure per AllSize Storage
Development Drainage Analysis . The remaining drainage source will be compiled of five
drainage subbasins, DA-D1 -DA-D5. All subbasins east of the property were defined based
on drainage paths and drain to a common point, STP1 . Each drainage area east of the
property drains to a culvert that travels from east of the northbound SH6 Frontage Road to
the west side of southbound SH6 Frontage Road, requiring routing for both areas. Offsite
drainage will accounts for the majority of the runoff present on the property. As indicated
in Exhibit 3. 1, subbasins EA-A, EA-B, and EA-C account for the project site in its entirety.
See Exhibit 4 for rational method ca lculations of each subbasin. Total peak runoff from the
basin outfall point was 118 cfs for the 10-year rainfall event and 203.6 cfs for the 100-year
rainfall event.
Post-Development Drainage Basin
The development of the suites will result in the addition of 0.476 ac of impervious cover to
the site, resulting in a gradual increase in peak runoff rate. The post-development analysis
of this development included eleven drainage subbasins as seen in Exhibit 3. 1. As
previously mentioned, the SCS curve numbers remained the same while the percentage of
Copper Falls Executive Suites
Drainage Report
2
impervious cover increased for the project site for approximately two of the subbasins, one
of which contains 91 % impervious cover. As a result of the development design, runoff
from the building and parking lot areas will drain through a proposed stormsewer system to
the tributary within the property as shown in Exhibit 3.2. Inlet capacity calculations (Exhibit
6) were performed to size the proposed curb inlet. Pipe sizing calculations were performed
based on rational method and the 10-year design storm. See Exhibit 5 for design storm
flows, pipe sizing, and pipe slopes. Hydraulic grade lines were calculated for the
stormsewer line based on tailwater elevations (Exhibit 7). The tailwater elevation was
determined from the water surface elevation in the pond for the 10-and 100-year storm
events. A proposed trapezoidal weir will be used in the tributary to Bee Creek to attenuate
the increased flow through the channel. For hydraulic modeling, the trapezoidal weir was
defined by elevation-discharge calculations, as seen in Exhibit 9. Sizing the detention pond
for hydraulic analysis was based on elevation-area calculations (Exhibit 8. 18). The increased
runoff from the development will ultimately affect the amount of flow in the tributary
creek. The natural earth ditch, mentioned earlier, will have no effects from the
development. The peak flow through the tributary will moderately change from the
development. Total post-detention peak runoff from the basin outfall point was 116.1 cfs
for the 10-year rainfall event and 197 .9 cfs for the 100-year rainfall event.
Table 1: Hydraulic Model Results
STP2 Existing Proposed Difference
5-YR 97.5 96.7 -0.8
10-YR 118 116.1 -1 .9
25-YR 139.8 136.3 -3.5
50-YR 164 159 -5
100-YR 203.6 197.9 -5.7
* Flows in units of cfs.
CONCLUSIONS
Although the development of the new Copper Falls Executive Suites development will
nominally increase volume of runoff from the site, the proposed on-site detention facility
was designed to mitigate the effects of development of this tract (see Table 1). The changes
in the drainage patterns that occur as the result of developing the tract will have a no
impact on the properties surrounding the Copper Falls Executive Suites site.
Copper Falls Executive Suites
Drainage Report
3
-
ATIACHMENTS
EXHIBIT 1:
EXHIBIT 2:
EXHIBIT 3.1:
EXHIBIT 3.2:
EXHIBIT 4:
EXHIBIT 5:
EXHIBIT 6:
EXHIBIT 7:
EXHIBIT 8.1 A:
EXHIBIT 8.1 B:
EXHIBIT 8.2A:
EXHIBIT 8.2B
EXHIBIT 8.3A:
EXHIBIT 8.3B
EXHIBIT 8.4A:
EXHIBIT 8.4B
EXHIBIT 8.5A:
EXHIBIT 8.5B
EXHIBIT 8.6A:
EXHIBIT 8.6B
EXHIBIT 9:
APPENDIX A:
General Location Map
Firmette -FEMA Map Panel 0182C (Effective July 1992)
Drainage Area Map
Stormsewer Sub-Drainage Areas
Rational Formula Drainage Area Calculations
Pipe Capacity Calculations
Inlet Capacity Calculations
HGL Calculations -10-Year Storm &100-Year Storm
HEC-HMS Subbasin Parameters
HEC-HMS Detention Pond Storage Calculations
HEC-HMS 5-year Existing Conditions Output
HEC-HMS 5-year Proposed Conditions Output
HEC-HMS 10-year Existing Conditions Output
HEC-HMS 10-year Proposed Conditions Output
HEC-HMS 25-year Existing Conditions Output
HEC-HMS 25-year Proposed Conditions Output
HEC-HMS 50-year Existing Conditions Output
HEC-HMS 50-year Proposed Conditions Output
HEC-HMS 100-year Existing Conditions Output
HEC-HMS 100-year Proposed Conditions Output
Proposed Weir Elevation-Discharge Calculations
Construction Drawings
Copper Falls Executive Suites
Drainage Report
4
A
1
B
ZONEX
City of College
Station
480083
0
LIMI
,A._ ~
APPROXIMATE SCALE
60c::O=--=--=-~~o ______ .....::.;600 FEET E"3 E3 E3 I
IATIOIAL FLOOD IHHAICE PIDHAll
FLOOD INSURANCE RATE MAP
BRAZOS COUNTY,
TEXAS AND
INCORPORATED AREAS
(SEE MAP' IND'X P"O .. ,AN ELS NOT PAINTED)
!!!!!!II! Ml. lm
COLLEGE STATION, CITY OF -'80083 0201 0
UNINCORPORATED AREAS 481195 0201 0
MU NUMBER
48041C0201 D
MAP REVISED:
FEBRUARY 9, 2000
Thi• is an official copy of a portion of the ab<Ne referenced ftood m111p. It
was extracted using F-MIT On-Une. This map doee not reflect changes
or amendments which may haw been made aubaequent to the date on the
title block. For the latest product Information about National Flood Insurance
Program ~ood maps check the FEMA Flood Map Store at www.mec.fema.gov
C\J
t--co -:I: >< w
•
D
N
1 inch equals 50 feet
Prepared for the City
of College Station
Planning and
Development
Department
JUNE 2008
Designed By: BEH
Drawn By: BEH
Checked By: V JBM
MITCHELL
MM
MORGAN
Civil Engineering;
Hydraultcs; Hydrology;
Utility Planning & Design;
Site Planning & Design;
Street Design;
Subdivision Planning & Design
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NO. AC. 0.45 0.95 ft. ft ft
EA-A 0.48 0.48 0.00 0.22 300.0 7.8 24.4
EA-B ~ 0.37 ~0.37' 000 0.17 300.0 10.0' 3.8 -EA-C 0.78 0.78 0.00 0.35 300.0 11 .5 79.7
28.95: -1882.8 EA-D1 .l223 6.72 16.39 300.0 1.0
EA-D2 4.49 2.77 1.73 2.89 300.0 23.0 392.4
EA-D3 0.76 -'0.49 0.28 0.48 1.0 -1.0 1.0 -EA-D4 3.19 2.71 0.48 1.67 300.0 10.0 520.9
EA-DS -,~ -~ 0.88 300.0 3.0 223.8 1.39 0.89 0.50
ALLSIZE 4.30 1.57 2.73 3.30 1.0 1.0 1.0
DA-A 0.48 0.48 ~0.00 0.22 300.0 7.8 24.4
DA-B 0.31 0.31 0.00 0.14 190.6 2.0 0.0 -~ ~ ·-DA-C 0.43 0.10 0.32 0.35 1.0 1.0 1.0
DA-D 0.43 0.27 0.16 0.27 300.0 11 .8 40.7
DA-E1 28.95 2 2.23 '3J.2 16.39 300.0 1 .o 1882.8
DA-E2 4.49 2.77 1.73 2.89 300.0 23.0 392.4 --i~ -DA-E3 0.76 0.49 0.28 0.48 1.0 1.0 1.0
DA-E4 3.19 2.71 0.48 1.67 300.0 10.0 520.9
DA-ES 0.36 '0.23 0.13 0.23 300.0 4.8 16.7
DA-E6 1.00 0.63 0.37 0.64 300.0 4.5 159.2
ALLSIZ;_ 4.30 ~ 1.57-2.73 3.30 1.0 1.0 1.0
DA-C1 0.43 0.04 0.39 0.39 1.0 1.0 1.0
DA-D1 0.09 0.00 0.09-0.09 1.0 1.0 1.0
:i: 0 ..J 11.
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(.!) ~
ft
0.2
0.1
0.5
23.5
8.5
1.0
8.5 -11 .5
1.0
0.2
0.0
1.0
0.3
23.5
8.5
f o
8.5
0.2
9.5
1.0
1.0
1.0-
EXHIBIT 4
Rational Formula Drainage Area Calculations
MITCHELL & MORGAN BUILDING
~ i3 CJ CJ I-0 I-
..J u w w iii Cf) N "' > u :::> !::! 0 !!! 0
ft/s min min In/Hr cfs In/Hr cfs
1.2 4.6 10.0 6.33 1.4 7.7 1.7
,__ 1.3 3.9 10.0--6.33 -1.0 7.7 -1.3
1.4 4.5 10.0 6.33 2.2 7.7 2.7 ,_ _,_
1.4 ,_26.4 26.4 3.75 61.4 4.7 76.5
2.4 4.8 10.0 6.33 18.3 7.7 22.2
10.4 -o-:0-10.0 6.33 _ 3.0 7.7 -3.7
1.9 7.3 10.0 6.33 10.6 7.7 12.9
1.1 7.9 10.0 6.33 5.5 ~7_7 ~ 6.7
10.4 0.0 10.0 6.33 20.9 7.7 25.4
1.2 4.6 10.0 6.33 1.4 7.7 1.7 -,__
0.7 4.4 10.0 6.33 0.9 7.7 1.1
10.4 -0.0 10.0 6.33 2.2 7.7 2.7
1.4 4.0 10.0 6.33 1.7 7.7 2.1
1.4 t:.AA 26.4 3.75 --4.7 76.5 61 .5
2.4 4.8 10.0 6.33 18.3 7.7 22.2
10.4 0.0 10.0 6.33 3.0 7.7 3 .7
1.9 7.3 10.0 6.33 10.6 7.7 12.9 -.____ ---7.7 1.7 0.9 -5.7 10.0 6.33 1.4
1.2 6.3 10.0 6.33 4.0 7.7 4.9
10.4 _M.. 10.0 nL ~ 20.9 7.7 25.4
10.4 0.0 10.0 6.33 2.4 7.7 3.0
10.4 0.0 10.0 -0.6 7.7 ..... 0.7 6.33
0 0 "' 0 0 0 0 & "' N 0 "' 0 ..... ..... !::! 0 !!! 0 !: 0
In/Hr cfs In/Hr cfs In/Hr cfs In/Hr cfs
8.6 1.9 9.9 2.1 11.1 2.4 12.5 2.7
-8.6 1.4 9.9 1.6 11 .1 1.8 12.5 2.1
8.6 3.0 9.9 3.4 11.1 3.9 12.5 4.4 --128.8 5.3 87.1 6.1 100.0 6.9 113.7 7.9
8.6 24.9 9.9 28.5 11 .1 32.2 12.5 36.1
-8.6 4.2 9.9 4.7 11 .1 5.4 12.5 6.0
8.6 14.4 9.9 16.5 11 .1 18.6 12.5 20.9
8.6 7.6 9.9 8.6 11 .1 9.8 12.5 11.0
8.6 28.5 9.9 32.5 11 .1 36.8 12.5 41.3
8.6 1.9 9.9 2.1 11 .1 2.4 12.5 2.7
8.6 1.2 9.9 1.4 11.1 1.5 12.5 1.7
8.6 3.0 9.9 3.5 11.1 3.9 12.5 4.4
8.6 2.4 9.9 2.7 11.1 3.0 12.5 3.4 -5.3 87.1 6.1 100.1 6.9 113.8 7.9 128.8
8.6 24.9 9.9 28.5 11.1 32.2 12.5 36.1 -8.6 4.2 9.9 4.7 11.1 5.4 12.5 6.0
8.6 14.4 9.9 16.5 11 .1 18.6 12.5 20.9
8.6 2.0 9.9 2.2 11 .1 2.5 12.5 2.8
8.6 5.5 9.9 6.3 11 .1 7.1 12.5 8.0
8.6 28.5 9.9 32.5 11 .1 36.8 12.5 41 .3
8.6 3.3 9.9 3.8 11 .1 4.3 12.5 4.8
8.6 0.8 9.9 0.9 11 .1 1.0 12.5 1.1
EXHIBIT 4
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•INLETNO.
•TOINLET
~TOTALCA
~Tc ::I
~ Design Storm
9' Unadjusted
Design Flow
Adjusted
9' De ign Flow
•No. of Pipes
9' Flow Per Pipe
~Friction Slope
~Pipe Slope
•SIZE
i'VEL.
9-Capacity
-LENGTH
~Travel Time
~Tc (ii) End
s::
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Note*
EXHIBIT6
Copper Falls Executive Suites
INLET CAPACITY
SUMP CURB:
Q = 3.0*L*y"1 .5
L= Q/(3.0*y"1 .5)
SUMP CURB
CB1
Q=
clog=
Q clogged=
y=
L=I
SUMP CURB
CB1
Q=
clog=
Q clogged=
Chosen L=
Flowline
y=I
WSE=
(10 Year Storm)
3.30 cfs
10%
3.63 cfs
0.83 ft
1.solft
(100 Year Storm)
4.80 cfs
10%
5.28 cfs
5.00 ft
99.78 ft
o.o4lft
99.78
Recessed inlets curb opening =
Height of curb +depression
y = 6"+4"=equal 1 O"
EXHIBIT6
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01'-'--cOJ ~ j""
CD CD CD Fl Pipe
~ 0101 Upstream (ft) °' ~ '--l 00""
Fl Pipe
CDICDICD Downstream ~ ~ 01 (ft) 0, ex,~
0000
""01 w Length (ft)
1':> CD .....
:...... (o °'
00 0 Slope (ft/ft) ~~ ~
00 0 00 0
.......... ..... Diameter (in) 01 01 01
Flow in Pipe
~~ ~ (cfs)
00 00 °'
00 c::> Friction Slope 06 0 (ft/ft) 00 0 01 01 01 01 01 01
00 0 Manning's
-"W ..... Headloss (ft) """" --.J _.. CD ~ """"" 00
Normal Depth
00 0 (ft) °' °' °' 00 0
HGL by
CD CD CD Manning's °' °' °' Upstream (ft) ow 01
""01 w
HGL by
CD CD CD Manning's
01 °' °' Downstream (o 0 w (ft) 01':> 01
HGL by Normal
CD CD CD Depth
01 °' "' Upstream (ft) Oi ;.,,, 01 00 "" HGL by Normal
CD CD CD Depth
01 01 °' Downstream w Cn ;.,,, (ft) 000 0
HGLat
CD CD CD Upstream Pipe °' °' °' 6 w 0, (ft)
1':>01W
I HGL at
CDICDICD Downstream
01 °' °' Pipe (ft) (o6 w 01'>01
.....
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...............
01 01 01
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w °' °'
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CD CD CD
01 01 °' t..J u, :......
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01 01 °' N~o oww
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01 °' °' ~o w W W01
CD CD CD
01 01 °' N~o ..... w w
CD CD CD ~~ 9'> ~ow w w 01
CD CD CD
01 01 °' N~o ow w
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~ ~ .,
~ Pipe Segment
Fl Pipe
Upstream (ft)
Fl Pipe
Downstream
(ft)
Length (ft)
Slope (ft/ft)
Diameter (in)
Flow in Pipe
(cfs)
Friction Slope
(ft/ft)
Manning's
Headloss (ft)
Normal Depth
(ft)
HGL by
Manning's
Upstream (ft)
HGL by
Manning's
Downstream
(ft)
HGL by Normal
Depth
Upstream (ft)
HGL by Normal
Depth
Downstream
(ft)
HGL at
Upstream Pipe
(ft)
HGLat
Downstream
Pipe (ft)
.....
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)>
' (") c: ~ 0 z (/l
C" en -ns c: Cl) ... en < ns .c iii -.c .... :::J 0 ·-"' ..._ E EA-A 0.000747 EA-B 0.000575 EA-C 0.001211 EA-01 0.045234 EA-02 0.00702 EA-03 0.001194 EA-04 0.00498 EA-05 0.00217 ALLSIZE 0.006719 C" en -ns c: Cl) ·u; ... < ns .c iii -.c .... :::J 0 ·-"' ..._ E EA-A 1.000747 OA-B 0.000477 OA-C 0.000664 OA-0 0.000672 OA-E1 0.045234 OA-E2 0.00702 OA-E3 0.001194 OA-E4 0.004981 OA-E5 0.000559 OA-E6 0.001563 -EXHIBIT 8.1A HMS SUBBASIN PARAMETERS COPPER FALLS EXECUTIVE SUITES EXISTING CONDITIONS ... Cl) .c = en E Cl) .~ :r ...!... ... Cl) "C :::J z CJ c.. ~z < >. :; £ Oc .c: Cl) iii .... ns ... 0:.. .21 c:: ... C> 0 "' ... '(5 Cl) :::J "C c: 0 ~ 0 >. Cl) ..... 0 .... "' 3: 0 :::c ..J _ ..... 0.48 0 75 324.4 3.33 0.37 0 75 303.8 3.33 0.78 0 75 379.7 3.33 28.95 0 80.34 2182.8 2.45 4.49 0 84.03 692.4 1.90 0.76 0 84.5 -1.83 3.19 0 78.5 820.9 2.74 1.39 0 83.3 523.8 2.00 4.30 0 89.6 -1.16 PROPOSED CONDITIONS ... Cl) .c = en E Cl) -~ :r ...!... ... Cl) "C :::J z CJ c.. ~z < >. :; £ Oc .... .c: Cl) ns ... a:.:.. iii .21 c:: ... C> "C c: 0 "' ... '(5 Cl) :::J 0 ~ 0 >. Cl) ..... 0 .... "' 3: 0 :::c ..J _ ..... 640.48 0 75 324.4 3.33 0.31 0 75 190.6 3.33 0.42 0 90.4 -1.06 0.43 0 83.55 340.7 1.97 28.95 0 80.34 2182.8 2.45 4.49 0 84.03 692.4 1.90 0.76 0 84.5 -1.83 3.19 0 78.5 820.9 2.74 0.36 0 83.3 316.7 2.00 1.00 0 83.51 459.2 1.97 EXHIBIT 8.1 Cl) E ~ -C> ~~ ns -..J I!? ns Cl> ... c.. "' :::J Cl) 0 0 0 >-< "' "' :. 2.4 0.17 3.32 0.17 3.2 0.17 1.12 0.44 4.54 0.17 -0.17 2.25 0.17 2.76 0.17 -0.17 Cl) E ~ Cl)~ C> C>~ ns -ns Cl> ..J I!? ... c.. "' :::J Cl) 0 0 0 >-< "' "' :. 3.4 0.17 1.05 0.17 -0.17 3.55 0.17 1.12 0.44 4.54 0.17 -0.17 2.25 0.17 1.57 0.17 3.05 0.17
500
450
400 ~ 350 ~ 300
0 250 + 15 200
(ii 150 N 100
50
0
0
Elevation Area
(ft.) (sf.)
93 .50 0
94 .00 201
95.00 1590
96.00 4596
96.50 4596
0.00 0
0.00 0 -0.00 0 -
0.00 0
Mitchell & Morgan Office
Storage Indication Curve
' I I l ' '
' I I ' ' '
f-
------~ -------·-------. ------... ------~ ------. -----. . . ' ' ' ' ' ' ' ' ' ' --------------·-------·------.. ·------.. ·-----·------. ' ' . ' ' ! I ' ' ------~ ------_,_ ------. ------_._ ------.. ------~ ------I I 0 I I l ' . . . ' .
EXHIBIT 8.1 B
Stage/Storage -Stage/Discharge -Storage Indication Curves
Mitchell & Morgan Office
Area Inc. Volm.
(acres) (ac.-ft.)
0.000 0.000
0.005 0.001
0.037 0.018
0.106 0.068
0.106 0.053 -0.000 0.000
0.000 0.000 -0.000 0.000
0.000 0.000
Volume Outlet 1
(ac.-ft.) Invert Elev. (ft.) 0
Orifice Dia. (in.) or 0
Weir Length (ft.)
Orifice (cfs)
0.000 0.00
0.001 0.00 ---0.019
0.087 -0.140
0.000
0.000
f-0.000
0.000
Mitchell & Morgan Office
Stage-Storage Curve
0.00
0.00
0.00 -~
0.00
0.00
0.00 -0.00
Total
Flow
Outfall
(cfs)
0.00
16.57
86.11
185.29
243.57
0.00
0.00
0.00
0.00
Mitchell & Morgan Office
Stage-Discharge Curve
0.160 -,-----------------. ~------~...._----+9
~ 0.140
~ 0.120 ~ 0.100
§, 0.080
~ 0.060
£ 0.040
(/) 0.020
0.000 +-------------------<
95 97
--------------------------~-75 -
----------------------------------------------------l50 -
----------------------------------------------------~-25--
----------------------------------------------------~-00 -
--------------------------------------------------------75 -
--------------------------------------------------------50 -
--------------------------------------------------------25 -
25 50 75 100 125 150 175 200 96
Elevation (msl)
95.0 96.0
Elevation (msl)
97.0
Discharge (cfs)
EXHIBIT 8.1 B
EXHIBIT 8.2A
5 YEAR EXISTING CONDmONS HMS RESULTS
Hydrologic Drainage Area Peak Discharge llrre of Peak Volurre
Elerrent (MI2) (CFS) (IN)
142"RCP 0.0450000 71.7 16Sep1986, 12:27 3.85
ALLSIZE 0.0067200 21.4 16Sep1986, 12:07 4.96
1ASPOND 0.0067200 11.8 16Sep1986, 12: 17 4.95
!box c 0.0520203 77.9 16Sep1986, 12:27 3.90
box c2 0.0532141 78.9 16Sep1986, 12:28 3.91
box c3 0.0581941 82.8 16Sep1986, 12:28 3.88
1CREEK 0.0623221 86.0 16Sep1986, 12:28 3.87
!EA-A 0.0007470 1.8 16Sepl986, 12:08 3.23
IEA-B I 0.0005750 1.4 16Sep1986, 12:08 3.23
I !EA-C 0.0012110 2.9 16Sep1986, 12:08 3.23
jEA-Dl 0.0450000 84.5 16Sep1986, 12: 18 3.85
IEA-D2 0.0070203 20.0 16Sep1986, 12:07 4.27
!EA-D3 0.0011938 3.4 16Sep1986, 12:07 4.21
I 0.0049800 12.6 16Sep1986, 12:07 3.60 iEA-04
IEA-D5 0.0021700 6.1 16Sep1986, 12:07 4.21
!JOIN 0.0072950 12.7 16Sep1986, 12: 15 4.82
loutl 0.0623221 86.0 16Sep1986, 12:28 3.87
lout2 0.0072950 12.7 16Sep1986, 12: 16 4.81
I pond 0.0450000 71.7 16Sep1986, 12:26 3.85
ISTPl 0.0623221 86.1 16Sep1986, 12:28 3.87
ISTP2 0.0696171 97.5 16Sep1986, 12:28 3.97
ISTP3 0.0450000 71.7 16Sep1986, 12:26 3.85
I 0.0520203 77.9 16Sep1986, 12:26 3.90 \STP4
STP5 0.0532141 78.9 16Sep1986, 12:27 3.91
ISTP6 ! 0.0581941 82.8 16Sep1986, 12:27 3.88
STP7 0.0067200 11.8 16Sep1986, 12: 17 4.95
~IB 0.0072950 12.7 16Sep1986, 12: 16 4.81
EXHIBIT 8. 2A
EXHIBIT 8.2B
5 YEAR PROPOSED CONDmONS HMS RESULTS
Hydro logic Drainage Area Peak Discharge Tirre of Peak Volurre
Elerrent (MI2) (CFS) (IN)
142" RCP 0.0452344 72.1 16Sep1986, 12:27 3.85
ladd 0.0604081 84.8 16Sep1986, 12:28 3.87
ALLSIZE 0.0067200 21.4 16Sep1986, 12:07 4.96
I IASPOND 0.0067200 11.8 16Sep1986, 12:17 4.95
!berm2 ' 0.0610721 85.3 16Sep1986, 12:29 3.89
lbox c 0.0522547 78.3 16Sep1986, 12:27 3.90
box c2 0.0534485 79.3 16Sep1986, 12:28 3.91
lbox c3 ! 0.0584297 83 .2 16Sep1986, 12:28 3.88
!CREEK 0.0604081 84.7 16Sep1986, 12:28 3.87
!DA-B .000477 1.1 16Sep1986, 12:08 3.23
IDA-C .000664 2.4 16Sep1986, 12:07 5.72
!DA-D .000672 1.8 16Sep1986, 12:07 3.80
I DA-El 0.0452344 84.9 16Sep1986, 12: 18 3.85
DA-E2 0.0070203 20.0 16Sep1986, 12:07 4.27
IDA-E3 0.0011938 3.4 16Sep1986, 12:07 4.21
IDA-E4 0.0049812 12.6 16Sep1986, 12:07 3.60
IDA-E5 .000559375 1.6 16Sep1986, 12:07 4.22 !
IDA-E6 0.0015625 4.4 16Sep1986, 12:07 4.25
DRAININPUT 0.0610721 85.4 16Sep1986, 12:28 3.89
IEA-A I .000747 1.8 16Sep1986, 12:08 3.23
\Epond 0.0452344 72.1 16Sep1986, 12:26 3.85
JJOIN 0.0071970 12.5 16Sep1986, 12: 15 4.84
IPOND_OUT ... 0.0610721 85.3 16Sep1986, 12:29 3.89
ISTPl I 0.0589891 83.7 16Sep1986, 12:28 3.88
iSTPlO 0.0071970 12.5 16Sep1986, 12: 16 4.84
ISTP2 0.0682691 96.7 16Sep1986, 12:28 3.99
ISTP3 0.0452344 72.1 16Sep1986, 12:26 3.85
ISTP4 0.0522547 78.3 16Sep1986, 12:26 3.90
STP5 0.0534485 79.3 16Sep1986, 12:27 3.91
ISTP6 0.0584297 83.2 16Sep1986, 12:27 3.88
ISTP7 0.0067200 11.8 16Sep1986, 12: 17 4.95
STP8 .000664 2.4 16Sep1986, 12:07 5.72
ITRIB 0.0071970 12.5 16Sep1986, 12: 16 4.84
ITRIB2 .000664 2.3 16Sep1986, 12:07 5.72
EXHIBIT 8.2B
-
EXHIBIT 8.3A
10 YEAR EXISTING CONDmONS HMS RESULTS
Hydrologic Drainage Area Peak Discharge Time of Peak Volume
Element (MI2) (CFS) (IN)
l42"RCP 0.0450000 79.8 16Sep1986, 12:30 5.16
iALLSIZE 0.0067200 24.8 16Sep1986, 12:07 6.36 ;
IASPOND 0.0067200 14.7 16Sep1986, 12: 17 6.35
!box c 0.0520203 86.9 16Sep1986, 12:27 5.23
lbox c2 0.0532141 88.8 16Sep1986, 12:20 5.23
box c3 0.0581941 96.8 16Sep1986, 12:20 5.20
iCREEK 0.0623221 102.8 16Sep1986, 12:21 5.19
IEA-A 0.0007470 2.2 16Sep1986, 12:07 4.52
EA-B 0.0005750 1. 7 16Sep1986, 12:07 4.52
iEA-C 0.0012110 3.6 16Sep1986, 12:07 4.52
!EA-Dl 0.0450000 103.9 16Sep1986, 12: 18 5.17 !
IEA-02 0.0070203 23 .9 16Sep1986, 12:07 5.63
iEA-03 0.0011938 4.0 16Sep1986, 12:07 5.56
!EA-04 0.0049800 15.5 16Sep1986, 12:07 4.91
IEA-05 0.0021700 7.3 16Sep1986, 12:07 5.56
!JOIN 0.0072950 15.8 16Sep1986, 12: 16 6.21
IOutl 0.0623221 102.8 16Sep1986, 12:21 5.19
IOut2 0.0072950 15.8 16Sep1986, 12: 17 6.21
I pond 0.0450000 79.8 16Sep1986, 12:29 5.17
ISTP1 0.0623221 103.3 16Sep1986, 12:20 5.19 I
iSTP2 0.0696171 118.0 16Sep1986, 12:20 5.30
ISTP3 0.0450000 79.8 16Sep1986, 12:29 5.17
ISTP4 l 0.0520203 86.9 16Sep1986, 12:26 5.23
ISTPS 0.0532141 88.8 16Sep1986, 12: 19 5.23
STP6 0.0581941 96.8 16Sep1986, 12:19 5.20
ISTP7 0.0067200 ; 14.7 16Sep1986, 12: 17 6.35
~IB 0.0072950 15.8 16Sep1986, 12:17 6.21
EXHIBIT 8. 3A
-
EXHIBIT 8.3B
10 YEAR PROPOSED CONDffiONS HMS RESULTS
Hydrologic Drainage Area Peak Discharge lirre of Peak Volurre
Elerrent (MI2) (CFS) (IN)
14211 RCP 0.0452344 80.0 16Sep1986, 12:30 5.16
I
!add 0.0604081 100.3 16Sep1986, 12:20 5.20 i
IALL51ZE 0.0067200 24.8 16Sep1986, 12:07 6.36
IASPOND 0.0067200 14.7 16Sep1986, 12:17 6.35
\berm2 0.0610721 101.1 16Sep1986, 12:21 5.22
ibox c 0.0522547 87.1 16Sep1986, 12:27 5.22
lbox c2 0.0534485 88.9 16Sep1986, 12:20 5.23
Jbox c3 0.0584297 97.2 16Sep1986, 12:20 5.20
!CREEK 0.0604081 99.8 16Sep1986, 12:21 5.20
IDA-B .000477 1.4 16Sep1986, 12:07 4.52
jDA-C .000664 2.7 16Sep1986, 12:07 7.17
iDA-D .000672 2.1 16Sep1986, 12:07 5.12
DA-El 0.0452344 104.5 16Sep1986, 12: 18 5.17
IDA-E2 0.0070203 23.9 16Sep1986, 12:07 5.63
iDA-E3 0.0011938 4.0 16Sep1986, 12:07 5.56
IDA-E4 0.0049812 15.5 16Sep1986, 12:07 4.91
iDA-ES .000559375 1.9 16Sep1986, 12:07 5.57
IDA-E6 0.0015625 5.3 16Sep1986, 12:07 5.60
IDRAININPUT 0.0610721 101.0 16Sep1986, 12:20 5.22
iEA-A .000747 2.2 16Sep1986, 12:07 4.52
iEpond 0.0452344 80.0 16Sep1986, 12:29 5.17
IJOIN I 0.0071970 15.7 16Sepl 986, 12: 16 6.23
IPOND OUT ... 0.0610721 101.1 16Sep1986, 12:21 5.22 ! -
!STP1 0.0589891 98.1 16Sep1986, 12:20 5.21
ISTP10 ! 0.0071970 15.6 16Sep1986, 12:17 6.23
ISTP2 0.0682691 116.1 16Sep1986, 12:21 5.32 !
!STP3 0.0452344 80.0 16Sep1986, 12:29 5.17
!STP4 0.0522547 87.1 16Sep1986, 12:26 5.23
!STPS 0.0534485 88.9 16Sep1986, 12: 19 5.23 i
!STP6 0.0584297 97.2 16Sep1986, 12:19 5.20
ISTP7 ! 0.0067200 14.7 16Sep1986, 12:17 6.35
jSTP8 .000664 2.7 16Sep1986, 12:07 7.17
~IB 0.0071970 15.6 16Sep1986, 12: 17 6.23
ITRIB2 .000664 2.7 16Sep1986, 12:07 7.17
EXHIBIT 8. 3 B
-
EXHIBIT 8.4A
25 YEAR EXISTING CONDmONS HMS RESULTS
Hydrologic Drainage Area Peak Discharge llme of Peak Volume
Element (MI2) (CFS) (IN)
i42"RCP I 0.0450000 90.3 16Sep1986, 12:32 6.07
JALLSIZE 0.0067200 29.2 16Sep1986, 12:07 7.30
jASPOND 0.0067200 18.4 16Sep1986, 12: 16 7.29
ibex c 0.0520203 98.3 16Sep1986, 12:30 6.13
Ibex c2 0.0532141 99.7 16Sep1986, 12:30 6.14
!box c3 0.0581941 110.5 16Sep1986, 12: 16 6.11
jCREEK 0.0623221 120.1 16Sep1986, 12: 16 6.10
I JEA-A 0.0007470 2.7 16Sep1986, 12:07 5.40
!EA-B 0.0005750 2.1 16Sep1986, 12:07 5.40
IEA-C I 0.0012110 4.4 16Sep1986, 12:07 5.40
IEA-Dl 0.0450000 125.9 16Sep1986, 12: 18 6.08
IEA-02 I 0.0070203 28.5 16Sep1986, 12:07 6.55
IEA-03 0.0011938 4.8 16Sep1986, 12:07 6.47
IEA-04 0.0049800 18.8 16Sep1986, 12:07 5.80 I
!EA-05 0.0021700 8.8 16Sep1986, 12:07 6.47
!JOIN 0.0072950 19.8 16Sep1986, 12: 15 7.14
loutl 0.0623221 120.1 16Sep1986, 12: 16 6.10
lout2 0.0072950 19.8 16Sep1986, 12: 16 7.14
!pond 0.0450000 90.3 16Sep1986, 12:31 6.07
I 0.0623221 120.7 16Sep1986, 12: 16 6.10 ISTPl !
iSTP2 0.0696171 139.8 16Sep1986, 12: 16 6.21
ISTP3 0.0450000 90.3 16Sep1986, 12:31 6.07
iSTP4 0.0520203 98.3 16Sep1986, 12:29 6.14 I
ISTP5 0.0532141 99.7 16Sep1986, 12:29 6.14
jSTP6 0.0581941 110.5 16Sep1986, 12: 15 6.11
JSTP7 0.0067200 18.4 16Sep1986, 12:16 7.29
iTRIB I 0.0072950 19.8 16Sep1986, 12: 16 7.14
EXHIBIT 8.4A
-
EXHIBIT 8.4B
25 YEAR PROPOSED CONDmONS HMS RESULTS
Hydrologic Drainage Area Peak Discharge Time of Peak Volume
Element (MI2) (CFS) (IN)
142" RCP 0.0452344 90.6 16Sep1986, 12:32 6.07
ladd ! 0.0604081 115.5 16Sep1986, 12: 16 6.10
!AU.SIZE 0.0067200 29.2 16Sep1986, 12:07 7.30
!AS POND 0.0067200 18.4 16Sep1986, 12: 16 7.29
iberm2 ! 0.0610721 116.8 16Sep1986, 12:17 6.13
lbox c 0.0522547 98.6 16Sep1986, 12:30 6.13
I !box c2 0.0534485 100.0 16Sep1986, 12:31 6.14
lbox c3 0.0584297 110.6 16Sep1986, 12: 16 6.11
!CREEK 0.0604081 115.1 16Sep1986, 12: 16 6.10
IDA-B .000477 1. 7 16Sep1986, 12:07 5.40
IDA-C .000664 3.1 16Sep1986, 12:07 8.14
jDA-D .000672 2.6 16Sep1986, 12:07 6.02
I IDA-El 0.0452344 126.6 16Sep1986, 12: 18 6.08
IDA-E2 0.0070203 I 28.5 16Sep1986, 12:07 6.55
!DA-E3 0.0011938 4.8 16Sep1986, 12:07 6.47
IDA-E4 0.0049812 18.8 16Sep1986, 12:07 5.80
iDA-E5 .000559375 2.3 16Sep1986, 12:07 6.48
IDA-E6 0.0015625 6.3 16Sep1986, 12:07 6.51
IDRAININPUT I 0.0610721 117.0 16Sep1986, 12: 16 6.13
IEA-A .000747 2.7 16Sep1986, 12:07 5.40 I
iEpond 0.0452344 90.6 16Sep1986, 12:31 6.07
!JOIN 0.0071970 19.5 16Sep1986, 12: 15 7.17
IPOND OUT ... 0.0610721 I -116.8 16Sep1986, 12:17 6.13
ISTPl 0.0589891 112.1 16Sep1986, 12: 16 6.11
ISTPlO I 0.0071970 19.5 16Sep1986, 12: 16 7.17
iSTP2 0.0682691 136.3 16Sep1986, 12:17 6.24
iSTP3 I 0.0452344 90.6 16Sep1986, 12:31 6.07
!STP4 ! 0.0522547 98.6 16Sep1986, 12:29 6.14
!STP5 I 0.0534485 100.0 16Sep1986, 12:30 6.14
jSTP6 0.0584297 110.6 16Sep1986, 12: 15 6.11
ISTP7 I 0.0067200 18.4 16Sep1986, 12: 16 7.29
ISTP8 .000664 3.1 16Sep1986, 12:07 8.14
rmIB 0.0071970 19.5 16Sep1986, 12: 16 7.17
~IB2 .000664 3.1 16Sep1986, 12:07 8.14
EXHIBIT 8.4B
-
EXHIBIT 8.SA
SO YEAR EXISTING CONDmONS HMS RESULTS
Hydrologic Drainage Area Peak Discharge lirre of Peak Volurre
Element (MI2) (CFS) (IN)
i42"RCP 0.04SOOOO 99.2 16Sep1986, 12:33 7.33
!AU.SIZE 0.0067200 32.0 16Sep1986, 12:07 8.61
IASPOND 0.0067200 29.6 16Sep1986, 12: 12 8.60
box c O.OS20203 108.0 16Sep1986, 12:31 7.40
box c2 O.OS32141 109.6 16Sep1986, 12:32 7.40
ibex c3 O.OS81941 122.4 16Sep1986, 12: 13 7.37
CREEK 0.0623221 13S.8 16Sep1986, 12: 13 7.36
EA-A 0.0007470 3.1 16Sep1986, 12:07 6.63
EA-B O.OOOS7SO 2.4 16Sep1986, 12:07 6.63
I !EA-C 0.0012110 s.o 16Sep1986, 12:07 6.63
IEA-Dl 0.04SOOOO 142.9 16Sepl986, 12: 18 7.34
iEA-D2 0.0070203 31.7 16Sep1986, 12:07 7.83
!EA-D3 0.0011938 S.4 16Sep1986, 12:07 7.7S
IEA-04 0.0049800 21.2 16Sep1986, 12:07 7.0S
!EA-DS 0.0021700 9.7 16Sep1986, 12:07 7.7S
!JOIN 0.00729SO 31.S 16Sep1986, 12: 12 8.4S
loutl 0.0623221 13S.8 16Sep1986, 12: 13 7.36
IOut2 0.00729SO 28.3 16Sep1986, 12: 13 8.44
jpond 0.04SOOOO 99.2 16Sep1986, 12:32 7.33
ISTPl 0.0623221 136.l 16Sep1986, 12: 13 7.36 I
STP2 0.0696171 164.0 16Sep1986, 12: 13 7.47
STP3 0.04SOOOO 99.2 16Sep1986, 12:32 7.33
ISTP4 O.OS20203 108.0 16Sep1986, 12:30 7.40
iSTPS O.OS32141 109.6 16Sep1986, 12:31 7.40
STP6 0.0581941 122.4 16Sep1986, 12: 12 7.37
ISTP7 0.0067200 29.6 16Sep1986, 12: 12 8.60 I
~IB 0.00729SO 28.3 16Sep1986, 12: 13 8.44
EXHIBIT 8. SA
-
EXHIBIT 8. SB
SO YEAR PROPOSED CONDmONS HMS RESULTS
Hydro logic Drainage Area Peak Discharge Tirre of Peak Volurre
Elerrent (MI2) (CFS) (IN)
142" RCP 0.04S2344 99.6 16Sep1986, 12:33 7.33
add 0.0604081 129.4 16Sep1986, 12: 13 7.36
1AU.SIZE 0.0067200 32.0 16Sep1986, 12:07 8.61
I !ASPOND 0.0067200 29.6 16Sep1986, 12: 12 8.60
jberm2 0.0610721 131.2 16Sep1986, 12: 14 7.39
lbox c O.OS22547 108.4 16Sep1986, 12:31 7.40
jbox c2 0.053448S 109.9 16Sep1986, 12:32 7.40
!box c3 O.OS84297 122.8 16Sep1986, 12: 13 7.37
!CREEK 0.0604081 129.0 16Sep1986, 12: 13 7.36
IDA-B .000477 2.0 16Sep1986, 12:07 6.63
DA-C .000664 3.4 16Sep1986, 12:07 9.48
IDA-D .000672 2.9 16Sep1986, 12:07 7.28
I DA-El 0.04S2344 143.6 16Sep1986, 12: 18 7.34
DA-E2 0.0070203 31.7 16Sep1986, 12:07 7.83
IDA-E3 0.0011938 5.4 16Sep1986, 12:07 7.7S
DA-E4 0.0049812 21.2 16Sep1986, 12:07 7.0S
JDA-E5 .OOOSS937S 2.5 16Sep1986, 12:07 7.76
IDA-E6 0.0015625 7.0 16Sep1986, 12:07 7.79
!DRAININPUT 0.0610721 131.6 16Sep1986, 12: 13 7.39
IEA-A .000747 ; 3.1 16Sep1986, 12:07 6.63
IEpond 0.04S2344 99.6 16Sep1986, 12:32 7.33
!JOIN 0.0071970 31.2 16Sep1986, 12: 12 8.47
!POND_OUT ... 0.0610721 131.2 16Sep1986, 12:14 7.39
iSTPl 0.0589891 124.7 16Sep1986, 12:13 7.37
ISTP10 I 0.0071970 28.0 16Sep1986, 12: 13 8.47
!STP2 0.0682691 159.0 16Sep1986, 12: 13 7.50 I
!STP3 0.04S2344 99.6 16Sep1986, 12:32 7.33
ISTP4 I 0.0522547 108.4 16Sep1986, 12:30 7.40
JSTP5 0.0534485 109.9 16Sep1986, 12:31 7.40
ISTP6 0.0584297 122.8 16Sep1986, 12: 12 7.37
STP7 0.0067200 29.6 16Sep1986, 12: 12 8.60
ISTP8 .000664 3.4 16Sep1986, 12:07 9.48
ITRIB 0.0071970 28.0 16Sep1986, 12: 13 8.47
lfRIB2 .000664 3.3 16Sep1986, 12:07 9.48
EXHIBIT 8. SB
-
EXHIBIT 8. 6A
100 YEAR EXISTING CONDmONS HMS RESULTS
Hydrologic Drainage Area Peak Discharge nrre of Peak Volurre
Elerrent (MI2) (CFS) (IN)
!42"RCP 0.0450000 155.4 16Sep1986, 12:23 8.51
I
IALLSIZE 0.0067200 35.8 16Sep1986, 12:07 9.82
IASPOND 0.0067200 42.6 16Sep1986, 12:09 9.82 !
ibox c 0.0520203 170.2 16Sep1986, 12:24 8.58
box c2 0.0532141 172.6 16Sep1986, 12:25 8.58
box c3 0.0581941 181.6 16Sep1986, 12:26 8.55
!CREEK 0.0623221 185.2 16Sep1986, 12:27 8.54
IEA-A 0.0007470 3.5 16Sep1986, 12:07 7.80
I
IEA-B 0.0005750 2.7 16Sep1986, 12:07 7.80
IEA-C ! 0.0012110 5.7 16Sep1986, 12:07 7.80
IEA-01 ! 0.0450000 162.0 16Sep1986, 12: 18 8.52
jEA-02 0.0070203 35.7 16Sep1986, 12:07 9.02
JEA-03 0.0011938 6.0 16Sep1986, 12:07 8.95
I !EA-04 0.0049800 24.1 16Sep1986, 12:07 8.23
iEA-05 0.0021700 11.0 16Sep1986, 12:07 8.95
!JOIN 0.0072950 45.2 16Sep1986, 12:09 9.66
iouu 0.0623221 I 185.2 16Sep1986, 12:27 8.54
!Out2 0.0072950 39.6 16Sep1986, 12: 10 9.66
I pond 0.0450000 155.4 16Sep1986, 12:22 8.51
ISTP1 0.0623221 188.8 16Sep1986, 12:26 8.54
ISTP2 0.0696171 203.6 16Sep1986, 12:27 8.66
STP3 0.0450000 155.4 16Sep1986, 12:22 8.51
ISTP4 I 0.0520203 170.2 16Sep1986, 12:23 8.58
ISTP5 ! 0.0532141 172.6 16Sep1986, 12:24 8.59
ISTP6 0.0581941 181.6 16Sep1986, 12:25 8.55
STP7 0.0067200 42.6 16Sep1986, 12:09 9.82
jTRIB 0.0072950 39.6 16Sep1986, 12: 10 9.66
EXHIBIT 8. 6A
-
EXHIBIT 8.68
100 YEAR PROPOSED CONDillONS HMS RESULTS
Hydrologic Drainage Area Peak Discharge Time of Peak Volume
Element (MI2) (CFS) (IN)
142" RCP 0.0452344 179.3 16Sep1986, 12:23 8.51
Jadd 0.0604081 209.0 16Sep1986, 12:26 8.55
!All.SIZE 0.0067200 35.8 16Sep1986, 12:07 9.82
jASPOND 0.0067200 42.6 16Sep1986, 12:09 9.82
iberm2 0.0610721 180.1 16Sep1986, 12:28 8.57
ibox c 0.0522547 194.2 16Sep1986, 12:24 8.58
lbox c2 0.0534485 196.6 16Sep1986, 12:25 8.58
!
lbox c3 0.0584297 205.6 16Sep1986, 12:26 8.55
IC REEK 0.0604081 187.4 16Sep1986, 12:26 8.54
IDA-8 .000477 2.3 16Sep1986, 12:07 7.80
DA-C .000664 3.7 16Sep1986, 12:07 10.72
IDA-D .000672 3.3 16Sep1986, 12:07 8.46
JDA-El 0.0452344 162.9 16Sep1986, 12: 18 8.52
DA-E2 0.0070203 35.7 16Sep1986, 12:07 9.02
IDA-E3 0.0011938 6.0 16Sep1986, 12:07 8.95
IDA-E4 I 0.0049812 24.1 16Sep1986, 12:07 8.23
IDA-ES .000559375 2.8 16Sep1986, 12:07 8.96
\DA-E6 0.0015625 7.9 16Sep1986, 12:07 8.99
\DRAININPUT 0.0610721 188.7 16Sep1986, 12:26 8.57
iEA-A .000747 I 3.5 16Sep1986, 12:07 7.80
!Epond 0.0452344 179.3 16Sep1986, 12:22 8.51
!JOIN 0.0071970 44.7 16Sep1986, 12:09 9.68
JPOND_OUT ... 0.0610721 180.1 16Sep1986, 12:28 8.57
S1Pl 0.0589891 206.6 16Sep1986, 12:26 8.56
S1P10 0.0071970 38.8 16Sep1986, 12: 10 9.68
lsw2 0.0682691 I 197.9 16Sep1986, 12:28 8.69
lsw3 0.0452344 179.3 16Sep1986, 12:22 8.51
i51P4 0.0522547 194.2 16Sep1986, 12:23 8.58
lsw5 0.0534485 196.6 16Sep1986, 12:24 8.59 I
lsw6 ! 0.0584297 205.6 16Sep1986, 12:25 8.55
i51P7 0.0067200 42.6 16Sep1986, 12:09 9.82 I
lsw8 .000664 3.7 16Sep1986, 12:07 10.72
jTRIB 0.0071970 38.8 16Sep1986, 12:10 9.68
jTRI82 .000664 3.7 16Sep1986, 12:07 10.72
EXHIBIT 8. 68
EXHIBIT 9
TRAPEZOIDAL WEIR ELEVATION-DISCHARGE CALCULATIONS
Q=3.367*L *h312
I LENGTH OF WEIR BASE
ELEVATION (ft) HEIGHT (ft) FLOW (cfs)
93.5 0 0
93.75 0.25 5.89
94 0.5 16.67
94.25 0.75 30.62
94.5 1 47.14
94.75 1.25 65.88
95 1.5 86.60
95.25 1.75 109.13
95.5 2 133.33
95 .75 2.25 159.09
96 2.5 186.33
EXHIBIT 9 -
-
Executive Summary
The Copper Falls Executive Suites will be located in College Station, Texas, south of Mile
Drive, north of Texas Avenue and west of State Hwy 6 Southbound Frontage Road. The
1.62 ac site is currently undeveloped, adjacent to residential and commercial developments.
The current zoning is Administrative/Professional (A-P). No zoning change requests are
required for this property as the proposed use is in compliance with City of College Station
zoning regulations.
The development is situated within the bottom third of the Bee Creek Drainage Basin,
containing a tributary to Bee Creek. Due to property location in Bee Creek Watershed,
detention for flood control is not required . Although a detention pond is not required, the
proposed development will have detention to attenuate flow through the property.
Detention is suggested due to residential developments located along the small creek that
will be affected by the site development. The entire property is located within the Bee
Creek Watershed and is completely within College Station city limits. No portion of the
property lies within the regulatory 100-year floodplain per the Federal Emergency
Management Agency (FEMA) Flood Insurance Rate Map (FIRM) panel 0182(, with an
effective data of July 2, 1992.
Existing site conditions consist of undeveloped land with trees present throughout the
property. Runoff currently sheets to a small creek tributary that flows to Bee Creek main
watercourse. The majority of site will remain undisturbed with the south part of the
property being developed.
The site will gain access from the SH6 west frontage, which is east and adjacent to the
project site . The proposed development includes an office building intended for
business/commercial use . Additionally, the development will include the construction of one
berm that will provide detention storage along with a small amount of stormsewer system .
Development will be confined in the southern area of the site, leaving the majority of the
site undeveloped.
Post construction will maintain the same discharge pattern, collecting the stormwater from
the development is a storm sewer system and dispensing into the small creek. Less than
100 feet of storm sewer pipe will be used and all pipe sizes will be fifteen (15") inches. Due
to the slight increase in runoff, the small creek will be bermed near the west property line.
The small creek will detain runoff and a trapezoidal weir will be used to mitigate the runoff
off the property.
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
The Cities of Bryan and College Station both require storm drainage design to follow these
Unified Stormwater Design Guidelines. Paragraph C2 of Section Ill (Administration) requires
submittal of a drainage report in support of the drainage plan (stormwater management plan)
proposed in connection with land development projects, both site projects and subdivisions.
That report may be submitted as a traditional prose report, complete with applicable maps,
graphs, tables and drawings, or it may take the form of a "Technical Design Summary". The
format and content for such a summary report shall be in substantial conformance with the
description in this Appendix to those Guidelines. In either format the report must answer the
questions (affirmative or negative) and provide, at minimum, the information prescribed in the
"Technical Design Summary" in this Appendix.
The Stormwater Management Technical Design Summary Report shall include several parts
as listed below. The information called for in each part must be provided as applicable. In
addition to the requirements for the Executive Summary, this Appendix includes several
pages detailing the requirements for a Technical Design Summary Report as forms to be
completed. These are provided so that they may be copied and completed or scanned and
digitized. In addition, electronic versions of the report forms may be obtained from the City.
Requirements for the means (medium) of submittal are the same as for a conventional report
as detailed in Section Ill of these Guidelines.
Note: Part 1 -Executive Summary must accompany any drainage report
required to be provided in connection with any land development project,
regardless of the format chosen for said report.
Note: Parts 2 through 6 are to be provided via the forms provided in this
Appendix. Brief statements should be included in the forms as requested,
but additional information should be attached as necessary.
Part 1 -Executive Summary Report
Part 2 -Project Administration
Part 3 -Project Characteristics
Part 4 -Drainage Concept and Design Parameters
Part 5 -Plans and Specifications
Part 6 -Conclusions and Attestation
STORMWATER MANAGEMENT TECHNICAL DESIGN SUMMARY REPORT
Part 1 -Executive Summary
This is to be a brief prose report that must address each of the seven areas listed below.
Ideally it will include one or more paragraphs about each item.
1. Name, address, and contact information of the engineer submitting the report, and
of the land owner and developer (or applicant if not the owner or developer). The
date of submittal should also be included .
2. Identification of the size and general nature of the proposed project, including any
proposed project phases. This paragraph should also include reference to
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 1 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
applications that are in process with either City: plat(s), site plans, zoning requests ,
or clearing/grading permits, as well as reference to any application numbers or
codes assigned by the City to such request.
3. The location of the project should be described. This should identify the Named
Regulatory Watershed(s) in which it is located , how the entire project area is
situated therein, whether the property straddles a watershed or basin divide, the
approximate acreage in each basin, and whether its position in the Watershed
dictates use of detention design. The approximate proportion of the property in the
city limits and within the ET J is to be identified, including whether the property
straddles city jurisdictional lines. If any portion of the property is in floodplains as
described in Flood Insurance Rate Maps published by FEMA that should be
disclosed.
4. The hydrologic characteristics of the property are to be described in broad terms:
existing land cover; how and where stormwater drains to and from neighboring
properties; ponds or wetland areas that tend to detain or store stormwater; existing
creeks, channels, and swales crossing or serving the property; all existing drainage
easements (or ROW) on the property, or on neighboring properties if they service
runoff to or from the property.
5. The general plan for managing stormwater in the entire project area must be
outlined to include the approximate size , and extent of use, of any of the following
features: storm drains coupled with streets; detention I retention facilities; buried
conveyance conduit independent of streets; swales or channels; bridges or culverts;
outfalls to principal watercourses or their tributaries; and treatment(s) of existing
watercourses. Also, any plans for reclaiming land within floodplain areas must be
outlined.
6. Coordination and permitting of stormwater matters must be addressed. Th is is to
include any specialized coordination that has occurred or is planned with other
entities (local, state, or federal). This may include agencies such as Brazos County
government, the Brazos River Authority, the Texas A&M University System, the
Texas Department of Transportation, the Texas Commission for Environmental
Quality, the US Army Corps of Engineers, the US Environmental Protection Agency,
et al. Mention must be made of any permits , agreements, or understandings that
pertain to the project.
7. Reference is to be made to the full drainage report (or the Technical Design
Summary Report) which the executive summary represents. The principal
elements of the main report (and its length), including any maps, drawings or
construction documents, should be itemized. An example statement might be:
"One -page drainage report dated , one set of
construction drawings ( sheets) dated , and a
___ -page specifications document dated comprise
the drainage report for this project."
Part 2 -Project Administration I Start (Page 2.1)
Engineering and Design Professionals Information
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 2 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Engineering Firm Name and Address: Jurisdiction
Mitchell and Morgan , LLP City: Bryan
511 Univer sity Dri ve East, Suite 204 x College Station College St ati on, TX 77840
Date of Submittal:
7/21/08
Lead Engineer's Name and Contact lnfo.(phone, e-mail, fax): Other:
Veroni ca Morgan (979-260-6963 ,v@rnitchellandrnorgan .corn)
Supporting Engineering I Consulting Firm(s): Other contacts:
N/A
Developer I Owner I Applicant Information
Developer I Applicant Name and Address: Phone and e-mail:
1999 Properties Group, LLC 979-260-6963
511 University Dr ive East , Suite 204 v@rnitchellandrnorgan.com
Coll ege Station, TX 77840
Property Owner(s) if not Developer I Applicant (&address): Phone and e-mail:
Project Identification
Development Name: copper Fa lls Executi ve Suites
Is subject property a site project, a single-phase subdivision, or part of a multi-phase subdivision?
Site Project If multi-phase, subject property is phase of
Legal description of subject property (phase) or Project Area:
(see Section II, Paragraph B-3a)
Project Area : 1.62 Acres, M Rector Abstr act # 46
If subject property (phase) is second or later phase of a project, describe general status of all
earlier phases. For most recent earlier phase Include submittal and review dates.
General Location of Project Area, or subject property (phase):
Located along St a t e Highway 6 Frontage Road West near Deacon Street Exit
In City Limits? Extraterritorial Jurisdiction (acreage):
Bryan : acres. Bryan: College Station:
College Station: 1 .62 Acres acres. Acreage Outside ET J:
Part 2 -Project Administration I Continued (page 2.2)
Project Identification (continued)
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 3 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Roadways abutting or within Project Area or Abutting tracts, platted land, or bu ilt
subject property: developments:
State Highway 6 Frontage Road West AllSize Storage located south of subject
is located adjacent to property . property, residential subdivision of
Bernadine Estates .
Named Regulatory Watercourse(s) & Watershed(s): Tributary Basin(s):
Bee Creek Watershed
Plat Information For Project or Subject Property (or Phase)
Preliminary Plat File#: Final Plat File #: Date:
Name: Development Plat in Progress Status and Vol/Pg:
If two plats, second name: File #:
Status: Date:
Zoning Information For Project or Subject Property (or Phase)
Zoning Type: A-P Existing or Proposed? Case Code:
Case Date Status:
Zoning Type: Existing or Proposed? Case Code:
Case Date Status:
Stormwater Management Planning For Project or Subject Property (or Phase)
Planning Conference(s) & Date(s): Participants:
Preliminary Report Required? No Submittal Date Review Date
Review Comments Addressed? Yes --No --In Writing? When?
Compliance With Preliminary Drainage Report. Briefly describe (or attach documentation
explaining) any deviation(s) from provisions of Preliminary Drainage Report, if any.
N/A
Part 2 -Project Administration I Continued (page 2.3)
Coordination For Project or Subject Property (or Phase)
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 4 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Note: For any Coordination of stormwater matters indicated below, attach documentation
describing and substantiating any agreements, understandings, contracts, or approvals.
Coordination Dept. Contact: Date: Subject:
With Other
Departments of
Jurisdiction
City (Bryan or
College Station)
Coordination With Summarize need(s) & actions taken (include contacts & dates):
Non-jurisdiction
City Needed?
Yes No x ----
Coordination with Summarize need(s) & actions taken (include contacts & dates):
Brazos County
Needed?
Yes No x ----
Coordination with Summarize need(s) & actions taken (include contacts & dates):
TxDOT Needed?
Yes No x ----
Coordination with Summarize need(s) & actions taken (include contacts & dates):
TAMUS Needed?
Yes No x ----
Permits For Project or Subject Property (or Phase)
As to stormwater management, are permits required for the proposed work from any of the entities
listed below? If so, summarize status of efforts toward that objective in spaces below.
Entity Permitted or Status of Actions (include dates) Approved?
US Army Crops of
Engineers
No x Yes ---
US Environmental
Protection Agency
No x Yes ---
Texas Commission on
Environmental Quality
No x Yes --
Brazos River
Authority
No x Yes ---
Part 3 -Property Characteristics I Start (Page 3.1)
Nature and Scope of Proposed Work
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 5 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Existing: Land proposed for development currently used, including extent of impervious cover?
Site __ Redevelopment of one platted lot, or two or more adjoining platted lots.
Development __ Building on a single platted lot of undeveloped land.
Project __ Building on two or more platted adjoining lots of undeveloped land.
(select all _x_ Building on a single lot, or adjoining lots, where proposed plat will not form applicable) a new street (but may include ROW dedication to existing streets).
__ Other (explain):
Subdivision __ Construction of streets and utilities to serve one or more platted lots.
Development __ Construction of streets and utilities to serve one or more proposed lots on Project lands represented by pending plats.
Site projects: building use(s), approximate floor space, impervious cover ratio.
Describe Subdivisions: number of lots by general type of use, linear feet of streets and
Nature and drainage easements or ROW.
Size of Site Project: Administrative/Professional, 6200 S .F ., 29.4%
Pro(!osed impervious cover ratio.
Project
Is any work planned on land that is not platted If yes, explain:
or on land for which platting is not pending?
x No Yes ----
FEMA Floodplains
Is any part of subject property abutting a Named Regulatory Watercourse I No_x_ Yes __ (Section II , Paragraph B1) or a tributary thereof?
Is any part of subject property in floodplain / No_x_ Yes Rate Map Panel 01a2c area of a FEMA-regulated watercourse? --
Encroachment( s) Encroachment purpose(s): __ Building site(s) __ Road crossing(s) into Floodplain
areas planned? __ Utility crossing(s) __ Other (explain):
No x --
Yes --
If floodplain areas not shown on Rate Maps, has work been done toward amending the FEMA-
approved Flood Study to define allowable encroachments in proposed areas? Explain.
N/A
Part 3 -Property Characteristics I Continued (Page 3.2)
Hydrologic Attributes of Subject Property {or Phase)
Has an earlier hydrologic analysis been done for larger area including subject property?
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 6 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Yes Reference the study (&date) here, and attach copy if not already in City files.
--
Is the stormwater management plan for the property in substantial conformance with the
earlier study? Yes No If not, explain how it differs.
No If subject property is not part of multi-phase project, describe stormwater management
x plan for the property in Part 4.
--If property is part of multi-phase project, provide overview of stormwater management plan
for Project Area here. In Part 4 describe how plan for subject property will comply
therewith.
Do existing topographic features on subject property store or detain runoff? _x_ No --Yes
Describe them (include approximate size, volume, outfall, model, etc).
Yes Any known drainage or flooding problems in areas near subject property? _x_ No --Identify:
Based on location of study property in a watershed, is Type 1 Detention (flood control} needed?
(see Table B-1 in Appendix B)
__ Detention is required. Need must be evaluated. _x_ Detention not required. --
What decision has been reached? By whom?
If the need for
Type 1 Detention How was determination made?
must be evaluated:
Part 3 -Pro12ert~ Characteristics I Continued (Page 3.3)
Hydrologic Attributes of Subject Property (or Phase) (continued)
Does subject property straddle a Watershed or Basin divide? x No Yes If yes, ----describe splits below. In Part 4 describe design concept for handling this.
Watershed or Basin
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 7 of 26
I Larger acreage I Lesser acreage
I I
APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Above-Project Areas(Section II, Paragraph 83-a)
Does Project Area (project or phase) receive runoff from upland areas? No x Yes ----
Size(s) of area(s) in acres: 1) 4 .3 2) 38.76 3) 4)
Flow Characteristics (each instance) (overland sheet, shallow concentrated, recognizable
concentrated section(s), small creek (non-regulatory), regulatory Watercourse or tributary);
Flow characteristics consist of overland sheet,shallow concentrated, and
small creek.
Flow determination: Outline hydrologic methods and assumptions:
The SCS Curve Number Method was used to determine hydrologic characteristics
and analysis was performed with HEC-HMS 3.1.0.
Does storm runoff drain from public easements or ROW onto or across subject property?
No x Yes If yes, describe facilities in easement or ROW: ----
A TXDoT culvert dispenses runoff from areas east of SH 6 Frontage Road East,
areas in between SH 6 and Frontage Roads into small creek located on
subject property.
Are changes in runoff characteristics subject to change in future? Explain
No, the runoff characteristics will not change due to development in the
subject property. However, runoff will be controlled with outlet structure
due to change in land use.
Conveyance Pathways (Section II, Paragraph C2)
Must runoff from study property drain across lower properties before reaching a Regulatory
Watercourse or tributary? No x Yes
Describe length and characteristics of each conveyance pathway(s). Include ownership of
property(ies).
Pathway flows through Bernadine Estates and Pleasant Forest and joins to
Bee Creek Tributary A.
Part 3 -Pro12ert~ Characteristics I Continued (Page 3.4)
Hydrologic Attributes of Subject Property (or Phase) (continued)
Conveyance Pathways (continued)
Do drainage If yes, for what part of length? % Created by? __ plat, or
easements __ instrument. If instrument(s), describe their provisions. exist for any
part of
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 8 of 26 APPENDIX. D: TECH . DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
pathway(s)? See Exhibit 1 for stream and existing drainage easement
locations. x No
Pathway
Areas
Nearby
Yes
Where runoff must cross lower properties, describe characteristics of abutting lower
property(ies). (Existing watercourses? Easement or Consent aquired?)
Existing watercourses, tributaries to Bee Creek are unchanged by
proposed development.
Describe any built or improved drainage facilities existing near the property (culverts,
bridges, lined channels, buried conduit, swales, detention ponds, etc).
A culvert is located in the ROW located east of the subject property
near SH 6 Frontage Road West.
Drainage 1--~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~-----i
Facilities Do any of these have hydrologic or hydraulic influence on proposed stormwater
design? _x_ No __ Yes If yes, explain:
Part 4 -Drainage Conce~t and Design Parameters I Start (Page 4.1)
Stormwater Management Concept
Discharge(s) From Upland Area(s)
If runoff is to be received from upland areas, what design drainage features will be used to
accommodate it and insure it is not blocked by future development? Describe for each area,
flow section, or discharge point.
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 9 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
The 4.3 acre development(AllSize Storage) has detention with outlet structure
to manage runoff onto the subject property. No future devel opment can be made
between these two areas . The 38.76 acre area consists of devel opments on the
east side of SH 6 and areas that i n cl ude SH 6 and Frontage roads . All these
areas drain through the subject property by way of cul vert. Cul v erts have
been placed from the east side of SH 6 Frontage Road East to SH 6 Front age
Road West.
Discharge(s) To Lower Property(ies) (Section II , Paragraph E1)
Does project include drainage features (existing or future) proposed to become public via
platting? x No Yes Separate Instrument? x No Yes ----
Per Guidelines reference above, how will Establishing Easements (Scenario 1) runoff be discharged to neighboring --x Pre-development Release (Scenario 2) property(ies )? --Combination of the two Scenarios --
Scenario 1: If easements are proposed, describe where needed, and provide status of actions
on each. (Attached Exhibit# )
Scenario 2: Provide general description of how release(s) will be managed to pre-development
conditions (detention, sheet flow, partially concentrated, etc.). (Attached Exhibit# 1 )
Detention with ou tlet structure wil l be present to attenuat e runoff to
pre-developmen t conditions . The proposed outlet struct ure wil l be a trapezoidal
weir .
Combination: If combination is proposed, explain how discharge will differ from pre-
development conditions at the property line for each area (or point) of release.
If Scenario 2, or Combination are to be used , has proposed design been coord inated with
owner(s) of receiving property(ies)? x No Yes Explain and provide --
documentation.
Discharge into existing channel and remains unchanged
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.2)
Stormwater Management Concept (continued)
Within Project Area Of Multi-Phase Project
Will project result Identify gaining Basins or Watersheds and acres shifting:
in shifting runoff
between Basins or
between
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 10 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Watersheds?
No
Yes
What design and mitigation is used to compensate for increased runoff
from gaining basin or watershed?
How will runoff from Project
Area be mitigated to pre-
development conditions?
Select any or all of 1, 2,
and/or 3, and explain below.
1. __ With facility(ies) involving other development projects.
2. __ Establishing features to serve overall Project Area .
3. __ On phase (or site) project basis within Project Area.
1. Shared facility (type & location of facility; design drainage area served; relationship to size of
Project Area): (Attached Exhibit# )
2. For Overall Project Area (type & location of facilities): (Attached Exhibit # )
3. By phase (or site) project: Describe planned mitigation measures for phases (or sites) in
subsequent questions of this Part.
C'-·
-0
Are aquatic echosystems proposed? __ No
project( s )?
__ Yes In which phase(s) or
Cl> Ill c Cl> ~ >-Are other Best Management Practices for reducing stormwater pollutants proposed?
C: __ No __ Yes Summarize type of BMP and extent of use:
Ill c
OJ ·;n
Cl> 0 Oz
Iii 1~1
Cl> -d:
If design of any runoff-handling facilities deviate from provisions of B-CS Technical
Specifications, check type facility(ies) and explain in later questions.
__ Detention elements __ Conduit elements __ Channel features
__ Swales __ Ditches __ Inlets __ Valley gutters __ Outfalls
__ Culvert features __ Bridges Other
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.3)
Stormwater Management Concept (continued)
Within Project Area Of Multi-Phase Project (continued)
Will Project Area include bridge(s) or culvert(s)? __ No __ Yes Identify type and
general size and In which phase(s).
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 11 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
If detention/retention serves (will serve) overall Project Area , describe how it relates to subject
phase or site project (physical location, conveyance pathway(s), construction sequence):
Within Or Serving Subject Property (Phase, or Site)
If property part of larger Project Area, is design in substantial conformance with earlier anal ysis
and report for larger area? __ Yes No, then summarize the difference(s):
Identify whether each of the types of drainage features listed below are included, extent of use,
and general characteristics.
Typical shape? I Surfaces?
C"· Triangul ar Grass "O Q) (/) Steepest side slopes: Usual front slopes: Usual back slopes: (/)
::i Q) (/) >-4:1 Existing Exist i ng
i ~I Flow line slopes: least Typical distance from travelway:
typical 1% greatest (Attached Exh ibit# )
Q) 0 :2 (/) z
"O I ro 0 Are longitudinal culvert ends in compliance with B-CS Standard Specifications? .....
Q) x Yes No, then explain: ..... <{
(/) At intersections or otherwise, do valley gutters cross arterial or collector streets? ..c Q) No Yes If yes explain: :J C"· >---(.) "O I ..r:::. Q) -(/) ·-::i :;:: ..... Are valley gutters proposed to cross any street away from an intersection? (/) Q) -:t::: Q) ::i 0 No Yes Explain : (number of locations?) ~ ciz -- --i ~~ -"O I
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.4)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
fe Ci; Gutter line slopes: Least Usual Greatest
::i :t::: C"· Are inlets recessed on arterial and collector streets? Yes No If "no", (.) ::i "O ----.c Cl Q) identify where and why . .,.. "O (/) ~ c ::i
N/A ro
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 12 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Will inlets capture 10-year design stormflow to prevent flooding of intersections (arterial
with arterial or collector)? --Yes --No If no, explain where and why not.
Will inlet size and placement prevent exceeding allowable water spread for 10-year
design storm throughout site (or phase)? --Yes --No If no, explain.
Sag curves: Are inlets placed at low points? --Yes --No Are inlets and
conduit sized to prevent 100-year stormflow from ponding at greater than 24 inches?
--Yes --No Explain "no" answers.
Will 100-yr stormflow be contained in combination of ROW and buried conduit on
whole length of all streets? --Yes --No If no, describe where and why.
Do designs for curb, gutter, and inlets comply with B-CS Technical Specifications?
Yes --No If not, describe difference(s) and attach justification.
Are any 12-inch laterals used? _x_ No --Yes Identify length(s) and where
used.
C'· "O Pipe runs between system I Typical 30 Q) (/) Longest 56 (/) Q) access points (feet): :J >-E ~~1 Are junction boxes used at each bend? Yes x No If not, explain where --and why.
(/) Storm drain system has clean outs located at all (2 ) bends . c:: ·-0 ~z "O
I E .....
0 Are downstream soffits at or below upstream soffits? Least amount that hydraulic ....... (/) grade line is below gutter line (/) Yes x No __ If not, explain where and why:
(system-wide):
10 yr storm event : 3.43ft
Part 4 -Drainage Conce12t and Design Parameters I Continued (Page 4.5)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
Q) Q) Describe watercourse(s), or system(s) receiving system discharge(s) below
:J-ro:2-~ (include design discharge velocity, and angle between converging flow lines). IJ ..... > J 2 ro o s g-a..! ~ 1) Watercourse (or system), velocity, and angle? :: (/) ID ....... :J 3 c:: Q) 0 Unnamed tributary of Bee Creek, 5 .65 fps, o degree angle ..... 0 ..c:: ( -(/) c
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 13 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
2) Watercourse (or system), velocity, and angle?
3) Watercourse (or system), velocity, and angle?
For each outfall above, what measures are taken to prevent erosion or scour of
receiving and all facilities at juncture?
1)Rock rip-rap on downstream & upstream face of weir and just
downstream i n receivi ng creek.
2)
3)
Are swale(s) situated along property lines between properties? __ No --Yes
Number of instances: For each instance answer the following questions.
Surface treatments (including low-flow flumes if any):
C'-· Ul Qi
~ Ul
-Q) Flow line slopes (minimum and maximum): Ul >-c ~ I
~o
Ul z Outfall characteristics for each (velocity, convergent angle, & end treatment). ~
~x i
Ul
Q) .__ Will 100-year design storm runoff be contained within easement(s) or platted drainage <(
ROW in all instances? --Yes --No If "no" explain:
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.6)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
t2 Are roadside ditches used? No _x _ Yes If so, provide the following: Ul
Ul Q) Is 25-year flow contained with 6 inches of freeboard throughout? __ Yes No ro Q) ..c --
~ ,g Are top of banks separated from road shoulders 2 feet or more? __ Yes --No
~ 0 Are all ditch sections trapezoidal and at least 1.5 feet deep? Yes No ----
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 14 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
For any "no" answers provide location(s) and explain:
We did not modify t he existing TXDoT ditch, except i nst a l ling driveway
cul vert .
If conduit is beneath a swale, provide the following information (each instance).
Instance 1 Describe general location, approximate length:
(/) cu >-I~ Is 100-year design flow contained in conduit/swale combination? --Yes --No
If "no" explain:
c
0 ro z in Space for 100-year storm flow? ROW Easement Width ~1~ Swale Surface type, minimum Conduit Type and size, minimum and maximum
0 and maximum slopes: slopes, design storm:
~ C'· '6 (/) 'O a; ro c >-Inlets Describe how conduit is loaded (from streets/storm drains, inlets by type): c ro c
..c. ro
(.) .....
c .E cu c
0. 0 0 ~ Access Describe how maintenance access is provided (to swale, into conduit): -ro 0 E :::J .....
.~ .E c c cu 'O E Instance 2 Describe general location, approximate length: cu ro (/) (/) :::J
(/) cu
c 'O
0 ·:;: Is 100-year design flow contained in conduit/swale combination? Yes No ~ 0 ----..... If "no" explain: c 0.
..0 -cu E cu
0 ..c. Space for 100-year storm flow? ROW Easement Width (.) (/)
:!: cu Swale Surface type, minimum Conduit Type and size, minimum and maximum :::J iii 'O ..... and maximum slopes: slopes, design storm: c ro 0 0.
(.) cu --(/) cu Inlets Describe how conduit is loaded (from streets/storm drains, inlets by type): ro c
~ ~
(/)
cu ..... <( Access Describe how maintenance access is provided (to swale, into conduit):
Part 4 -Drainage ConceQt and Design Parameters \ Continued (Page 4. 7)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
'O If "yes" provide the following information for each instance: (/) cu cu ·-Instance 1 Describe general location, approximate length, surfacing: ro :s :!: ~ .0 "t (/) :J I = 0' ;; :§
~
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 15 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Is 100-year design flow contained in swale? --Yes --No Is swale wholly
within drainage ROW? --Yes --No Explain "no" answers:
Access Describe how maintenance access is provide:
Instance 2 Describe general location, approximate length, surfacing:
Is 100-year design flow contained in swale? --Yes --No Is swale wholly
within drainage ROW? __ Yes --No Explain "no" answers:
Access Describe how maintenance access is provided:
Instance 3, 4, etc. If swales are used in more than two instances, attach sheet
providing all above information for each instance.
"New" channels: Will any area(s) of concentrated flow be channelized (deepened,
widened, or straightened) or otherwise altered? x No Yes If only slightly --
C'· shaped , see "Swales" in this Part. If creating side banks, provide information below.
-0 c Q) Will design replicate natural channel? Yes No If "no". for each instance (/) ro ----0 -
a_ ~ describe section shape & area, flow line slope (min. & max.), surfaces, and 100-year e w design flow, and amount of freeboard: a_
(/) (/) Instance 1: ..... Q) c >-Q)
E
I Q) > 0 Instance 2: '-a_ E o ·-z
1~1 Instance 3:
(.)
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.8)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
Existing channels (small creeks): Are these used? No x Yes
(/) --
C:::: If "yes " provide the information below.
Q) Q) Will small creeks and their floodplains remain undisturbed? __ Yes x No How c E --c Q) ro > . ..c 0
many disturbance instances? 1 Identify each planned location:
(.) a. E , -
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 16 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
For each location, describe length and general type of proposed improvement
(including floodplain changes):
Small creek will be used for detention storage. Grad ing was modified to
create a pond . A trapezoidal weir was p l aced in t he small creek t o
control discharge f rom the proposed pond.
For each location, describe section shape & area , flow line slope (min. & max.),
surfaces, and 100-year design flow.
The modified section area has a pond s hape with approximately
0 .087 ac-ft. The design flow f or the secti on was 203 .6 cfs and the
f inal flow was 197.9 cfs.
Watercourses (and tributaries): Aside from fringe changes, are Regulatory
Watercourses proposed to be altered? _x_ No --Yes Explain below.
Submit full report describing proposed changes to Regulatory Watercourses. Address
existing and proposed section size and shape, surfaces, alignment, flow line changes,
length affected, and capacity, and provide full documentation of analysis procedures
and data. Is full report submitted? Yes --No If "no" explain:
All Proposed Channel Work: For all proposed channel work, provide information
requested in next three boxes .
If design is to replicate natural channel, identify location and length here, and describe
design in Special Design section of this Part of Report.
N/A
.,~ :. ,..~· ~
."'_,,,..
Will 100-year flow be contained with one foot of freeboard? Yes x No If --not, identify location and explain:
Pond f r e edboard was 0 .1 ' per Dr a i nage Rep ort a nd does not meet t he . 5 '
r equired f reeboar d f rom Unified Stormwater Dr ainage Gu idel ines . This
was don e t o have less d i s tur bance and removal o f t r ees .
Are ROW I easements sized to contain channel and required maintenance space?
--Yes _x_ No If not, identify location(s) and explain:
No easemen ts have been provi ded and i t will be pri vat el y owned and
maintain ed.
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.9)
Stormwater Management Concept (continued)
Within Or Serving Subject Property {Phase, or Site) (continued)
How many facilities for subject property project? 1 For each provide info. below.
c For each dry-type facilitiy: Facility 1 Facility 2 0 ~en c Q) Acres served & design volume + 10% 1. 62 x Q) :;:::; C" Q) ;::
100-yr volume: free flow & plugged 197.9 cfs x 0 ~
QJ LL L... Design discharge (10 yr & 25 yr) 116 .1 cf s 136 . 3 c f s <l:: c
c Spillway crest at 100-yr WSE? __ yes x no __ yes no ----
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 17 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Berms 6 inches above plugged WSE? j __ yes --no j __ yes --no
Explain any "no" answers:
On l y we ir, so no "plugged" WSE . Spillway crest is the top of weir.
For each facility what is 25-yr design Q, and design of outlet structure?
Facility 1: 136.3 cfs, outlet structure design will be trapezoidal weir.
Facility 2:
Do outlets and spillways discharge into a public facility in easement or ROW?
Facility 1: __ Yes x No Facility 2: Yes No -- ----
If "no" explain:
Adjacent properties were p l atted with out an easement covering existing
channel .
For each, what is velocity of 25-yr design discharge at outlet? & at sgillway?
Facility 1: 5 .24 fps & N/A Facility 2: &
Are energy dissipation measures used? x No Yes Describe type and ----location:
For each, is spillway surface treatment other than concrete? Yes or no, and describe:
Facility 1: Rock rip-rap at downstream and upstream face of weir.
Facility 2:
For each, what measures are taken to prevent erosion or scour at receiving facility?
Facility 1: Rock rip-rap at downstream and upstream face of weir.
Facility 2:
If berms are used give heights, slopes and surface treatments of sides.
Facility 1: 2.5 ft height, 4:1 slopes, rock rip-rap and concrete
Facility 2:
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.10)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
Do structures comply with B-CS Specifications? Yes or no, and explain if "no":
(/) a.> Facility 1; yes :;:; ;.: :0 {)a.> ro :::i LL c
c~ Facility 2: 0 c :;:; 0 c {) a.>-m
0
For additional facilities provide all same information on a separate sheet.
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 18 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Are parking areas to be used for detention? _x_ No --Yes What is
maximum depth due to required design storm?
Roadside Ditches: Will culverts serve access driveways at roadside ditches?
No x Yes If "yes", provide information in next two boxes. -- --
Will 25-yr. flow pass without flowing over driveway in all cases? x Yes No ----
Without causing flowing or standing water on public roadway? x Yes No ----
Designs & materials comply with 8-CS Technical Specifications? _x_ Yes --No
Explain any "no" answers:
C'-· rn
O> c
rn rn Are culverts parallel to public roadway alignment? x Yes No Explain: 0 ----L... rn () a.> 2 >-!~1 Creeks at Private Drives: Do private driveways, drives, or streets cross drainage
co ways that serve Above-Project areas or are in public easements/ ROW?
"O 0 No x Yes If "yes" provide information below. a.> z -- --rn
I
:::I How many instances? 1 Describe location and provide information below. rn t a.> Location 1: Drainage area, south of subject property including areas ~
:::I on east and west sides of Frontage Road. ()
a.> Location 2: L... <
Location 3:
For each location enter value for: 1 2 3
Design year passing without toping travelway? 100
Water depth on travelway at 25-year flow? 0 ft
Water depth on travelway at 100-year flow? 0 ft
For more instances describe location and same information on separate sheet.
Part 4 -Drainage Conce12t and Design Parameters I Continued (Page 4.11)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
0 Named Regulato!)l Watercourses {&Tributaries}: Are culverts proposed on these
rn = facilities? x No __ Yes, then provide full report documenting assumptions, t .0 --a.> :::I i > 0.. criteria, analysis, computer programs, and study findings that support proposed
"S ...... i design(s). Is report provided? __ Yes No If "no", explain: ()CO I --
~-g. < rn :::I
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 19 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Arterial or Major Collector Streets: Will culverts serve these types of roadways?
--No --Yes How many instances? For each identify the
location and provide the information below.
Instance 1:
Instance 2:
Instance 3:
Yes or No for the 100-year design flow: 1 2 3
Headwater WSE 1 foot below lowest curb top?
Spread of headwater within ROW or easement?
Is velocity limited per conditions (Table C-11 )?
Explain any "no" answer(s):
Minor Collector or Local Streets: Will culverts serve these types of streets?
--No --Yes How many instances? for each identify the
location and provide the information below:
Instance 1:
Instance 2:
Instance 3:
For each instance enter value, or "yes" I "no" for: 1 2 3
Design yr. headwater WSE 1 ft. below curb top?
100-yr. max. depth at street crown 2 feet or less?
Product of velocity (fps) & depth at crown (ft)=?
Is velocity limited per conditions (Table C-11 )?
Limit of down stream analysis (feet)?
Explain any "no" answers:
Part 4 -Drainage Conce12t and Design Parameters I Continued (Page 4.12)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
All Proposed Culverts: For all proposed culvert facilities (except driveway/roadside
~ ditch intersects) provide information requested in next eight boxes.
en -o Do culverts and travelways intersect at 90 degrees? Yes No If not, t:::: Q)
Q) E ----
> ·-identify location(s) and intersect angle(s), and justify the design(s): --::Jc (.) 0 ~
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 20 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Does drainage way alignment change within or near limits of culvert and surfaced
approaches thereto? __ No __ Yes If "yes" identify location(s), describe
change( s ), and justification:
Are flumes or conduit to discharge into culvert barrel(s)? __ No __ Yes If yes,
identify location(s) and provide justification:
Are flumes or conduit to discharge into or near surfaced approaches to culvert ends?
__ No __ Yes If "yes" identify location(s), describe outfall design treatment(s):
Is scour/erosion protection provided to ensure long term stability of culvert structural
components, and surfacing at culvert ends? __ Yes __ No If "no" Identify
locations and provide justification(s):
Will 100-yr flow and spread of backwater be fully contained in street ROW, and/or
drainage easements/ ROW? __ Yes __ No if not, why not?
Do appreciable hydraulic effects of any culvert extend downstream or upstream to
neighboring land(s) not encompassed in subject property? __ No __ Yes If
"yes" describe location(s) and mitigation measures:
Are all culvert designs and materials in compliance with B-CS Tech. Specifications?
__ Yes __ No If not, explain in Special Design Section of this Part.
Part 4 -Drainage Conce~t and Design Parameters \ Continued (Page 4.13)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
Is a bridge included in plans for subject property project? --No --Yes
If "yes" provide the following information.
Name(s) and functional classification of the roadway(s)?
(/) ar O>
"O ·;:: co
What drainage way(s) is to be crossed?
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 21 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
A full report supporting all aspects of the proposed bridge(s) (structural, geotechnical,
hydrologic, and hydraulic factors) must accompany this summary report. Is the report
provided? --Yes --No If "no" explain:
Is a Stormwater Provide a general description of planned techniques:
.~ Pollution Prevention ro Plan (SW3P) :J a established for ,_ project construction? CV ~ --No --Yes
Special Designs -Non-Traditional Methods
Are any non-traditional methods (aquatic echosystems, wetland-type detention, natural stream
replication, BMPs for water quality, etc.) proposed for any aspect of subject property project?
x No Yes If "yes" list general type and location below. ----
Provide full report about the proposed special design(s) including rationale for use and
expected benefits. Report must substantiate that stormwater management objectives will not
be compromised, and that maintenance cost will not exceed those of traditional design
solution ( s). Is report provided? x Yes No If "no" explain: --
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.14)
Stormwater Management Concept (continued)
Within Or Serving Subject Property (Phase, or Site) (continued)
Special Designs -Deviation From B-CS Technical Specifications
If any design(s) or material(s) of traditional runoff-handling facilities deviate from provisions of
B-CS Technical Specifications, check type facility(ies) and explain by specific detail element.
--Detention elements __ Drain system elements --Channel features
Culvert features Swales Ditches Inlets Outfalls ----------
__ Valley gutters __ Bridges (explain in bridge report)
In table below briefly identify specific element, justification for deviation(s).
Specific Detail Element
STORMWATER DESIGN GUIDELINES
Effective February 2007
I Justification for Deviation (attach additional sheets if needed)
Page 22 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
1)
2)
3)
4)
5)
Have elements been coordinated with the City Engineer or her/his designee? For each item
above provide "yes" or "no", action date, and staff name:
1)
2)
3)
4)
5)
Design Parameters
Hydrology
Is a map(s) showing all Design Drainage Areas provided? x Yes --No
Briefly summarize the range of applications made of the Rational Formula:
Drainage areas boundaries were defined and then area characteristics were
determined. Area, impervious cover, curve number, hydraulic longest path,
overland flow, shallow concentrated flow, time of concentration, and lag time
were the characteristics defined for each drainage area. Rational formula was
"""'" t-" siz<" st-"rms<"w<"r ;inn i nl <"t~s f"\nl v
What is the size and location of largest Design Drainage Area to which the Rational Formula
has been applied? 28.954 acres Location (or identifier): Located east of Frontage Road
East.
Part 4 -Drainage Conce~t and Design Parameters j Continued (Page 4.15)
Design Parameters (continued)
Hydrology (continued)
In making determinations for time of concentration, was segment analysis used?
No x Yes In approximately what percent of Design Drainage Areas? 100 %
As to intensity-duration-frequency and rain depth criteria for determining runoff flows, were any
criteria other than those provided in these Guidelines used? _x_ No --Yes If "yes"
identify type of data, source(s), and where applied:
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 23 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised February 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
For each of the stormwater management features listed below identify the storm return
frequencies (year) analyzed (or checked), and that used as the basis for design.
Feature Analysis Year(s) Design Year
Storm drain system for arterial and collector streets
Storm drain system for local streets
Open channels
Swale/buried conduit combination in lieu of channel
Swales
Roadside ditches and culverts serving them
Detention facilities: spillway crest and its outfall 5 , 1 0, 25, 50, 100 100
Detention facilities: outlet and conveyance structure(s) 5 , 10, 25, 50 , 10( 100
Detention facilities: volume when outlet plugged
Culverts serving private drives or streets 1 0, 100 10
Culverts serving public roadways
Bridges: provide in bridge report.
Hydraulics
What is the range of design flow velocities as outlined below?
Design flow velocities; Gutters Conduit Culverts Swales Channels
Highest (feet per second) 5.3 6 .0
Lowest (feet per second) 5 .3 6 .0
Streets and Storm Drain Systems Provide the summary information outlined below:
Roughness coefficients used: For street gutters:
For conduit type(s) PVC -~ Coefficients: 0.013
~
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.16)
Design Parameters (continued)
Hydraulics (continued)
Street and Storm Drain Systems (continued)
For the following, are assumptions other than allowable per Guidelines?
Inlet coefficients? x No Yes Head and friction losses x No Yes ------ --
Explain any "yes" answer:
In conduit is velocity generally increased in the downstream direction? x Yes No ----
Are elevation drops provided at inlets, manholes, and junction boxes? x Yes No ----
Explain any "no" answers:
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 24 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Are hydraulic grade lines calculated and shown for design storm? x Yes No ----
For 100-year flow conditions? x Yes No Explain any "no" answers: ----
What tailwater conditions were assumed at outfall point(s) of the storm drain system? Identify
each location and explain:
Tailwater conditions were based on the elevation of water being stored in
the detention pond. The pond elevation for specified storm events were the
tailwater elevation used in calculations.
Open Channels If a HEC analysis is utilized, does it follow Sec Vl.F.5.a? __ Yes __ No
Outside of straight sections, is flow regime within limits of sub-critical flow? __ Yes __ No
If "no" list locations and explain:
Culverts If plan sheets do not provide the following for each culvert, describe it here.
For each design discharge, will operation be outlet (barrel) control or inlet control?
Inlet
Entrance, friction and exit losses:
0.5, 0.013, 1. 0
Bridges Provide all in bridge report
Part 4 -Drainage Conce~t and Design Parameters I Continued (Page 4.17)
Design Parameters (continued)
Computer Software
What computer software has been used in the analysis and assessment of stormwater
management needs and/or the development of facility designs proposed for subject property
project? List them below, being sure to identify the software name and version, the date of the
version, any applicable patches and the publisher
1. HEC-HMS 3.1.0
2. Microsoft Excel
Part 5 -Plans and S~ecifications
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 25 of 26 APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008
-
SECTION IX
APPENDIX D -TECHNICAL DESIGN SUMMARY
Requirements for submittal of construction drawings and specifications do not differ due to use of a
Technical Design Summary Report. See Section 111, Paragraph C3.
Part 6 -Conclusions and Attestation
Conclusions
Add any concluding information here:
Attestation
Provide attestation to the accuracy and completeness of the foregoing 6 Parts of this Technical
Design Summary Drainage Report by signing and sealing below.
''This report (plan) for the drainage design of the development named in Part B was prepared
by me (or under my supervision) in accordance with provisions of the Bryan/College Station
Unified Drainage Design Guidelines for the owners of the property. All licenses and permits
required by any and all state and federal regulatory agencies for the proposed drainage
improvements have been issued or fall under applicable general permits."
Licensed Professional Engineer
State of Texas PE No.
STORMWATER DESIGN GUIDELINES
Effective February 2007
Page 26 of 26
(Affix Seal)
APPENDIX. D: TECH. DESIGN SUMMARY
As Revised Februarv 2008