HomeMy WebLinkAbout12 Development Permit 302 H&M Wholesale Inc,'
Figure XII
Development Permit
City of College Station, Texas
Site Legal Description : L er I) i L O C~ l 7} ~ 0 U{kl 'KJQO Q V{rl-L~ ) 'Seer t ---'B
Site Owner: t-\-f ~~ WA-oL-b;A L~ Address: _________ _
Telephone: ------------
Architect/ I ~~M'-'-+-.. _L ~· !'-----'-~ A-"---'-M--"-'-l M-+--,0-'"-'-N .,..__7 _
Date Application Filed: 2/Ldc? {"
I
Address :
------------~
Telephone No : __________ _
lication is hereby made for the following development specific waterway alterations :
~ ; ' \)
0 Application Fee
0 Signed Certifications
0 Drainage and erosion control plan, with supporting Drainage Report two (2) copies each.
0 Site and Construction Plans, with supporting Drainage Report two (2) copies each .
0 Other:
-----------------------------~
ACKNOWLEDGMENTS :
ormat n and conclusions contained in the above plans and supporting documents comply
with the current requirements of the City of College Station, Texas City Code, Chapter 13 and its
associated Drainage Policy and Design Standards.
As a condition of approval of this permit application, I agree to construct the improvements
proposed in this application according to these documents and the requirements of Chapter 13 of
the ollege Station City Code.
Contractor
Figure XII
Development Permit
City of College Station, Texas
Site Legal Description : LO-C I J i LOc.t:'.'-l(J ~00(\JWQQQ VMt--~ J 'Sec(. + ---B
Site Owner : t\-f ~\. vl-AoUSALb Address : _________ _
Architect/ I ~-M'-'-+--. ~_L _. l~-t A---'--'-M__..__,_l M-.0--'--4-N -r---7 _
Date Application Filed : 2/L~/q {"
I
Telephone: ___________ _
Address :
~------------Te 1 e phone No : __________ _
lication is hereby made for the following development specific waterway alterations: . ' ~ v
0 Application Fee
0 Signed Certifications
0 Drainage and erosion control plan , with supporting Drainage Report two (2) copies each .
0 Site and Construction Plans, with supporting Drainage Report two (2) copies each .
0 Other:
~-----------------------------
ACKNOWLEDGMENTS:
n and conclusions contained in the above plans and supporting documents comply
with the current requirements of the City of College Station, Texas City Code, Chapter 13 and its
associated Drainage Policy and Design Standards.
As a condition of approval of this permit application, I agree to construct the improvements
proposed in this application according to these documents and the requirements of Chapter 13 of
the College Station City Co d e.
~w~o; ~ _C_o_n-tr-ac_t_o_r ___________ _
, ' .
I
STORMWATER DRAINAGE ANALYSIS
FOR :
RETAIL FACILITY
DEACON STREET @TEXAS AVENUE
COLLEGE STATION, TEXAS
H & M WHOLESALE, INC.
1214 SOUTH COLLEGE AVENUE
BRYAN, TEXAS
BY :
M. L. HAMMONS, P.E.
1700 KYLE SOUTH
COLLEGE STATION, TEXAS
STORMWATER DRAINAGE ANALYSIS
RETAIL FACILITY
3300 TEXAS AVENUE
COLLEGE STATION, TEXAS
I, M. L. Hammons, P.E., as Engineer for site grading
and drainage of this development site , by seal and
signature, certify that this analysis and the resultant
facilities design, to the best of my knowledge and
intent, are in compliance with the City of College Station
or stormwater management.
Date /,
?>(7--'f t 'l r-· -
-,,·
:--
ANALYSIS I I I
SITE DESCRIPTION
The proposed development site for this project is the southwest corner of the Texas
Avenue/Deacon Street intersection (See Appendix #I, "vicinity map"). The tract is Lot 1,
Block 17, of the Southwood Valley Subdivision, Section 4-B. The street address is 3300
Texas Avenue .
The site is bounded to the north by Deacon Road, to the South by Lot 2 of the same
subdivision, to the east by the west access road of Texas Avenue and to the west by a
subdivision alley.
The tract is currently vacant and is vegetated with grass only . There are no trees or
shrubs .
The proposed development usage is for a convenience store with gasoline sales .
EXISTING SITE DRAINAGE
The site is not located in, or eminently near, the 100 year flood plain as identified by
FIRM map #48041C0205C, of 712192 (See Appendix #2, "Flood Plain Map").
According to Figure II - 1 of the Stormwater Management Plan for the City of College
Station as presented by the "Drainage Policy and Design Standards", this site is located
in the Bee Creek Tributary "A" drainage area (See Appendix #3, "Drainage Area Map").
Current surface drainage is sheet drainage and is generally in a northerly direction with
discharge onto Deacon Street, and Texas Avenue (See Appendix #4, "Site Plan" with
existing Topo), then via street curb and gutter to the drainage ditches at Texas Avenue
and/or Longmire Drive. There are no streams originating on or passing through the tract.
PROPOSED SITE DRAINAGE
In order to comply with City of College Station stormwater management criteria, the post
development stormwater runoff rate will be attenuated to a rate no greater than the pre-
development runoff rate . Control will be accomplished by on-site detention ponding,
including a controlled flow discharge structure. Ponding will be in two areas, the lower
being located along the east end of the site and th~,~r between the two driveways
along Deacon Street. Site discharge will be via I~" ~CP pipe from the discharge
structure, under Texas Avenue access road, into e ·sti open ditch drainage .
1
4-IS'/\. ~ l ~ ~ ~ \4-.' iS~~\M.~ t>~ ,u
DRAINAGE DESIGN CRITERIA
The 25 year storm event is used as the design storm, with discharge rate design
adjustment to control the 1 O year and the 100 year event. The "Rational Method" of
calculation is used.
With the "Rational Method" calculation, the following values have been established for the
C, I and A formula components :
Direct discharge C = .47
Detention discharge C = .82
(See Appendix #5)
110 = 8.63
125 = 9.86
1100= 11.64 (See Appendix #6)
TOTAL DRAINAGE AREA = 37,000 SF = .849 acres
Direct discharge area = 9,000 SF = .206 acres
Detention discharge area = 28,000 SF = .643 acres
Drainage diagram is shown by Appendix # 8 .
STORMWATER RUNOFF CALCULATIONS
(See Appendix #7)
Based on the C, I, and A factors established herein , stormwater runoff is calculated thus:
PRE DEVELOPMENT RUNOFF
0 =CIA
0100 =0.35 x 11 .64 x .849 = 3.46
025 =0 .35 x 9.86 x .849 = 2 .93
010 =0 .35 x 8 .63 x .849 = 2 .56
POST DEVELOPMENT RUNOFF
Direct Discharge
0100 =0.472 x 11 .64 x .207 = 1.14
025 =0.472 x 9 .86 x .207 = 0 .96
010 =0.472 x 8 .63 x .207 = 0 .84
Detention Collection
2
0100 =0.82 x 11.64 x .643 = 6.14
025 =0.82 x 9 .86 x .643 = 5.20
010 =0 .82 x 8.63 x .643 = 4.55
STORMWATER DISCHARGE RATE CONTROL
As indicated by the diagram of Appendix #8, part of the post development drainage will
be discharged from the tract directly to the adjacent street or right of way . The direct
drainage is quantified by the calculations as shown on page 2 herein . By deducting the
direct discharge runoff flow rate from the pre-development runoff flow rate, the allowable
detention pond discharge flow rate is established as follows :
Q100 = 3.46 cfs (pre-dev) - 1.14 cfs (direct discharge) = 2 .32 cfs
0 25 = 2 .93 cfs (pre-dev) -0.96 cfs (direct discharge) = 1.97 cfs
0 10 = 2.56 cfs (pre-dev) -0.84 cfs (direct discharge) = 1.72 cfs
Pond volume and discharge flow rate determinations are based on these all~wables .
The attenuated stormwater discharge , from this site , is via a discharge outlet structure
(See Appendix #10, "Flow-Control Discharge Structure Sketch) in the lower of two
interconnected detention ponds. There is no flow constriction between the upper and
lower pond, thereby rendering the pond storage and flow characteristics as one . With the
discharge structure openings as shown by the Appendix# 10 drawing , discharge -liquid
elevation relationships are thus:
STORM ATTENUATED LIQUID
EVENT DISCHARGE ELEVATION
100 YR . 2.24 cfs (Appendix #12) 100.0
25 YR. 1.98 cfs (Appendix #12) 99.9
10 YR . 1.70 cfs (Appendix #12) 99 .8
Discharge rates have been determined using the "Haested Methods" software program
to establish flow from the 6" round opening, combined with manual flow calculations for
the rectangulars · weir at the top of the structure . The rectangular weir calculation is
shown by Appendix #12 and the Haested data is shown by Appendix #11 .
STORMWATER DETENTION
The Stormwater detention system, as previously identified herein, is a two pond system
connected by a 12" storm drain pipe . The lower pond, located near Texas Avenue , will
contain about 53% of the maximum storm detained run-off while the upper pond and the
transfer pipe contain the remainder. Detention requirements are calculated according to
3
the "simplified hydrograph" method as presented by the City "Drainage Policy and Design
Standards" manual, page 75 . (See Appendix #9, "Detention Volume Requirements"). The
calculated storage volume is 4150 cubic feet. The elevation low point of the detention
system is 97 .3, at the discharge orifice . The overflow level, (which exceeds the 100 year
event requirements), is at elevation 100.2 .
Pond storage volumes provided and pond storage volumes required at various levels are :·
(See Appendix #13)
ELEVATION
97 .3
98.0
99.0
99.8
99.9
100 .0
100.2
POND VOLUME
0
145 ft3
1,070 ft3
2,550 ft3
2.900 ft3
3,400 ft 3
4,150 ft 3
POND REQUIRED
2,550 ft3
2.900 ft 3
3,400 ft3
Detention storage volumes are calculated as shown by Appendix #12 .
PHYSICAL CHARACTERISTICS
With stormwater detention as described herein and as indicated on site grading and site
landscaping plans, the detention ponds are an integral part of the landscaping areas . In
order to achieve the required liquid storage volumes, vertical walls are used along
portions of the pond perimeters . The walls are to be hand finished concrete . The
greatest differential elevation between the wall top and the adjacent pond floor is 4.0 feet
at the Texas Avenue frontage . The wall top elevation along Texas Avenue is slightly (0 .3
to O. 7 feet) higher than the top of the street curb, thus allowing city landscape
requirements to prevail. The pond wall characteristics along Deacon Street are
essentially the same except the maximum wall height is approximately 2 feet.
CONCLUSIONS
Peak run -off due to development will be attenuated adequately to provide no increased
runoff rate through the 100 year rainfall event.
No run-off is routed to other channels or tributaries .
No negative downstream impact is anticipated .
4
APPENDICES I I
APPENDIX #1
APPENDIX #2
APPENDIX #3
APPENDIX #4
APPENDIX #5
APPENDIX #6
APPENDIX #7
APPENDIX #8
APPENDIX #9
APPENDIX #10
APPENDIX #11
APPENDIX #12
APPENDIX #13
VICINITY MAP
FLOOD PLAIN MAP
DRAINAGE AREA MAP
SITE PLAN w/topo
"C" -FACTOR DETERMINATION
1-D-F CURVE
SITE DRAINAGE AREA DETERMINATION
SITE DRAINAGE DIAGRAM
DETENTION VOLUME REQUIREMENTS
FLOW CONTROL DISCHARGE STRUCTURE
6" ROUND OPENING OUTFLOW RATES
RECTANGULAR WEIR OUTFLOW RATES
CHART -VOLUME/ELEVATION/STORM EVENT
5
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City of College Sta,
480083
APPENDIX#2
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Figure XII
Development Permit
City of College Station, Texas
Site Legal Description : LO-C I) i LOC-~ l(} ~O!J{IJ\IJQ()'Q v~) <Sec..-r t ~
Site Owner: ttf ~~ vl.8-o k€-SAL~
Architect/ I ~-M~. ~-L-· l'--L-t A-"----'-M-"-'-l M-+-.O~N -;L--7 _
Contractor: -------------
Date Application Filed: gjdq {"
I
Telephone : ___________ _
Address :
------------~
Telephone No : __________ _
Approved: ___________ _
lication is hereby made for the following development specific waterway alterations :
~ ; ' . \)
0 Application Fee
0 Signed Certifications
0 Drainage and erosion control plan, with supporting Drainage Report two (2) copies each .
0 Site and Construction Plans, with supporting Drainage Report two (2) copies each .
0 Other:
-----------------------------~
ACKNOWLEDGMENTS :
format1 n and conclusions contained in the above plans and supporting documents comply
with the current requirements of the City of College Station, Texas City Code, Chapter 13 and its
associated Drainage Policy and Design Standards.
As a condition of approval of this permit application, I agree to construct the improvements
proposed in this application according to these documents and the requirements of Chapter 13 of
the ollege Station City Code .
Contractor
Figure XII
Development Permit
City of College Station, Texas
Site Legal Description : LO-C I) i LOG(-l(} ~OD {IJ\IJQQQ v{rLL~) <Seer + -"'B
Site Owner: l-\-f ~l. vlAol&SALb:
Contractor : -------------
Date Application Filed : gjdq {"
I
Telephone: ___________ _
Address :
------------~
Telephone No : __________ _
Approved : ___________ _
lication is hereby made for the following_develor.ment specific waterway alterations : . v
0 Applicati o n Fee
0 Signed Certifications
0 Drainage and erosion control plan, with supporting Drainage Report two (2) copies each.
0 Site and Construction Plans , with supporting Drainage Report two (2) copies each .
0 Other: ------------------------------
ACKNOWLEDGMENTS :
n and conclusions contained in the above plans and supporting documents comply
with the current requirements of the City of College Station, Texas City Code, Chapter 13 and its
associated Drainage Policy and Design Standards .
As a condition of approval of this permit application, I agree to construct the improvements
proposed in this application according to these documents and the requirements of Chapter 13 of
the College Station City Co d e .
~w~4; ~ -C-o-nt-r-ac_t_or ___________ _
, ..
I
STORMWATER DRAINAGE ANALYSIS
FOR :
RETAIL FACILITY
DEACON STREET@ TEXAS AVENUE
COLLEGE STATION, TEXAS
H & M WHOLESALE, INC.
1214 SOUTH COLLEGE AVENUE
BRYAN, TEXAS
BY :
M. L. HAMMONS, P.E.
1700 KYLE SOUTH
COLLEGE STATION, TEXAS
: ;
STORMWATER DRAINAGE ANALYSIS
RETAIL FACILITY
3300 TEXAS AVENUE
COLLEGE STATION, TEXAS
I, M. L. Hammons, P.E., as Engineer for site grad ing
and drainage of this development site, by seal and
signature, certify that this analysis and the resultant
facilities design, to the best of my knowledge and
intent, are in compliance with the City of College Station
or stormwater management.
Date /, '(;-(7-'f ( q_ :;----
5: ·-· . ~
.. __ _
ANALYSIS I I
SITE DESCRIPTION
The proposed development site for this project is the southwest corner of the Texas
Avenue/Deacon Street intersection (See Appendix #I , "vicinity map"). The tract is Lot 1,
Block 17, of the Southwood Valley Subdivision, Section 4-B. The street address is 3300
Texas Avenue .
The site is bounded to the north by Deacon Road, to the South by Lot 2 of the same
subdivision , to the east by the west access road of Texas Avenue and to the west by a
subdivision alley .
The tract is currently vacant and is vegetated with grass only . There are no trees or
shrubs .
The proposed development usage is for a convenience store with gasoline sales .
EXISTING SITE DRAINAGE
The site is not located in, or eminently near, the 100 year flood plain as identified by
FIRM map #48041 C0205C, of 7/2/92 (See Appendix #2 , "Flood Plain Map").
According to Figure II - 1 of the Stormwater Management Plan for the City of College
Station as presented by the "Drainage Policy and Design Standards", this site is located
in the Bee Creek Tributary "A" drainage area (See Appendix #3, "Drainage Area Map ").
Current surface drainage is sheet drainage and is generally in a northerly direction with
discharge onto Deacon Street , and Texas Avenue (See Appendix #4, "Site Plan" with
existing Topo), then via street curb and gutter to the drainage ditches at Texas Avenue
and/or Longmire Drive . There are no streams originating on or passing through the tract.
PROPOSED SITE DRAINAGE
In order to comply with City of College Station stormwater management criteria , the post
development stormwater runoff rate will be attenuated to a rate no greater than the pre-
development runoff rate. Control will be accomplished by on-site detention ponding ,
including a controlled flow discharge structure . Ponding will be in two areas , the lower
being located along the east end of the site and th~i/-er between the two driveways
along Deacon Street. Site discharge will be via 15" C P pipe from the discharge
structure, under Texas Avenue access road, into e ·sti open ditch drainage .
I ()V\. rlJtLU.s ~ ~ ~ ,,
l.y 'tS 'ib ~ ~ fo QM. \'O
1
DRAINAGE DESIGN CRITERIA
The 25 year storm event is used as the design storm, with discharge rate design
adjustment to control the 1 O year and the 100 year event. The "Rational Method" of
calculation is used.
With the "Rational Method" calculation, the following values have been established for the
C, I and A formula components:
Direct discharge C = .47
Detention discharge C = .82
(See Appendix #5)
110 = 8.63
125 = 9.86
1100= 11.64 (See Appendix #6)
TOTAL DRAINAGE AREA = 37,000 SF = .849 acres
Direct discharge area = 9,000 SF = .206 acres
Detention discharge area = 28,000 SF = .643 acres
Drainage diagram is shown by Appendix # 8.
STORMWATER RUNOFF CALCULATIONS
(See Appendix #7)
Based on the C, I, and A factors established herein , stormwater runoff is calculated thus :
PRE DEVELOPMENT RUNOFF
0 =CIA
0100 =0 .35 x 11 .64 x .849 = 3.46
025 =0.35 x 9 .86 x .849 = 2.93
010 =0.35 x 8 .63 x .849 = 2.56
POST DEVELOPMENT RUNOFF
Direct Discharge
0100 =0.472 x 11.64 x .207 = 1.14
025 =0.472 x 9 .86 x .207 = 0.96
Q10 =0.472 x 8.63 x .207 = 0 .84
Detention Collection
2
0100 =0.82 x 11 .64 x .643 = 6.14
025 =0.82 x 9 .86 x .643 = 5.20
010 =0 .82 x 8.63 x .643 = 4 .55
STORMWATER DISCHARGE RATE CONTROL
As indicated by the diagram of Appendix #8, part of the post development drainage will
be discharged from the tract directly to the adjacent street or right of way . The direct
drainage is quantified by the calculations as shown on page 2 herein . By deducting the
direct discharge runoff flow rate from the pre-development runoff flow rate, the allowable
detention pond discharge flow rate is established as follows :
Q100 = 3.46 cfs (pre-dev) -1.14 cfs (direct discharge)= 2 .32 cfs
Q25 = 2 .93 cfs (pre-dev) -0.96 cfs (direct discharge) = 1.97 cfs
Q10 = 2.56 cfs (pre-dev) -0.84 cfs (direct discharge) = 1.72 cfs
Pond volume and discharge flow rate determinations are based on these all~wables .
The attenuated stormwater discharge , from this site, is via a discharge outlet structure
(See Appendix #10, "Flow-Control Discharge Structure Sketch) in the lower of two
interconnected detention ponds . There is no flow constriction between the upper and
lower pond, thereby rendering the pond storage and flow characteristics as one . With the
discharge structure openings as shown by the Appendix# 1 O drawing , discharge -liquid
elevation relationships are thus :
STORM ATTENUATED LIQUID
EVENT DISCHARGE ELEVATION
100 YR . 2 .24 cfs (Appendix #12) 100 .0
25 YR . 1.98 cfs (Appendix #12) 99.9
10 YR. 1.70 cfs (Appendix #12) 99 .8
Discharge rates have been determined using the "Haested Methods" software program
to establish flow from the 6" round opening , combined with manual flow calculations for
the rectangulars · weir at the top of the structure. The rectangular weir calculation is
shown by Appendix #12 and the Haested data is shown by Appendix #11 .
STORMWATER DETENTION
The Stormwater detention system , as previously identified herein, is a two pond system
connected by a 12" storm drain pipe . The lower pond, located near Texas Avenue , will
contain about 53% of the maximum storm detained run-off while the upper pond and the
transfer pipe contain the remainder . Detention requirements are calculated according to
3
the "simplified hydrograph" method as presented by the City "Drainage Policy and Design
Standards" manual, page 75 . (See Appendix #9, "Detention Volume Requirements"). The
calculated storage volume is 4150 cubic feet. The elevation low point of the detention
system is 97 .3, at the discharge orifice . The overflow level, (which exceeds the 100 year
event requirements), is at elevation 100.2 .
Pond storage volumes provided and pond storage volumes required at various levels are:·
(See Appendix #13)
ELEVATION
97 .3
98.0
99.0
99 .8
99 .9
100.0
100.2
POND VOLUME
0
145 ft3
1,070 ft3
2,550 ft3
2.900 ft 3
3,400 ft3
4 ,150 ft3
POND REQUIRED
2,550 ft3
2.900 ft3
3,400 ft 3
Detention storage volumes are calculated as shown by Appendix #12 .
PHYSICAL CHARACTERISTICS
With stormwater detention as described herein and as indicated on site grading and site
landscaping plans, the detention ponds are an integral part of the landscaping areas. In
order to achieve the required liquid storage volumes, vertical walls are used along
portions of the pond perimeters . The walls are to be hand finished concrete. The
greatest differential elevation between the wall top and the adjacent pond floor is 4.0 feet
at the Texas Avenue frontage . The wall top elevation along Texas Avenue is slightly (0 .3
to 0.7 feet) higher than the top of the street curb, thus allowing city landscape
requirements to prevail. The pond wall characteristics along Deacon Street are
essentially the same except the maximum wall height is approximately 2 feet.
CONCLUSIONS
Peak run-off due to development will be attenuated adequately to provide no increased
runoff rate through the 100 year rainfall event.
No run-off is routed to other channels or tributaries .
No negative downstream impact is anticipated .
4
APPENDICES I I I
APPENDIX #1
APPENDIX #2
APPENDIX #3
APPENDIX #4
APPENDIX #5
APPENDIX #6
APPENDIX #7
APPENDIX #8
APPENDIX #9
APPENDIX #10
APPENDIX #11
APPENDIX #12
APPENDIX #13
VICINITY MAP
FLOOD PLAIN MAP
DRAINAGE AREA MAP
SITE PLAN w/topo
"C" -FACTOR DETERMINATION
1-D-F CURVE
SITE DRAINAGE AREA DETERMINATION
SITE DRAINAGE DIAGRAM
DETENTION VOLUME REQUIREMENTS
FLOW CONTROL DISCHARGE STRUCTURE
6" ROUND OPENING OUTFLOW RATES
RECTANGULAR WEIR OUTFLOW RATES
CHART -VOLUME/ELEVATION/STORM EVENT
5
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SITE
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Brazos Co unt y
Unincor p orated Areas
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City of College Sta1
480083
APPENDIX#2
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C-FACTOR DETERMINATION
PRE DEVELOPMENT
Total Drainage Area Considered . . . . . . 37,000 sf*
"C" . . . . . . . . . . . . . . . . 0 .35
POST DEVELOPMENT
Direct Discharge :
South side
West end
Sidewalk & Driveways
Deacon St. PL
Texas Avenue PL
Tota l Direct Discharge
Detention Discharge :
Impervious areas
bldgs
paving
sidewalks, etc.
Landscape areas
Total Detention Discharge
TOTAL P/D DISCHARGE
* See Append ix #7
630 sf
5 , 440 sf
2 ,000 sf
670 sf
260 sf
9,000 sf
23 ,960 sf
4,040 sf
28,000 sf
37,000 sf
10
0 .35
0.35
0 .90
0 .35
0 .35
0.472
0 .90
0.35
0.82
0 .735
APPENDIX #5
~ ~ )> -u -u m z 0 x ~ O> II ::lJ Q :J -Q :J -(9 :J Cll -'< --· -? ....... =r' ~ 14t~ ' : Ill I I I I i I; Ii ! : : .• ·~ .. . ·. . .. . . i I j 11 ·l~H--, I I I -. I I -I . . . . . . . . I I F\-: r--, I i I 1 1 1 : 1 · --I · · · I I -I I I i tt ~ ~ -·_ ~ _ ----. -+ = _ : --_ ··: --_ ~ -: .. r. _: = _ ~ -_ _ 8 ' -t-+-+-+-+-+----1'--f-t-¥'--+---t--t-+-+-+-+-+----1'--f---.+--+-t--t--t-+-+-+-i-l-+-+-+--+--+--+-+--+--l--}-.C.-~-· ---l . -=--~ . ---: ~ -... . ~ ·. --~ ~----... --I --. -6f--7---+-\-l~-f"rf--+'~-t--f"-.;c-R=+-t-+----1-+-+--+-+--+--+--+-+-+-+-+----1-+-+-+-+--+--+--+-+-+-1-4-+-+-+-+--+--J=~+..-4. .• 1-i -: --. --_· :_---_·_-. -. - . ---. -·-· -~-·_ -~:· -~--~ . -·------41-i-t--t--t-r--t---t--t-~~-f'~:t-~~::-t-'f""'~t="t~~~::=t-t--Vt-1-+-+-~+-1-+-t--t-t-1-t-+-t-+-~~-+-i • ,V -·-· --1 -..... . . I -~ I I·--• 2~-t-~~t-~~--+-t-t-t--t-t=f=f=[J~-t-J~i--t-=ff=~~r]?J~~~~~~t:E3E3=l=t=±=t=t=t-~±=I=i I , I ! I ! 1-l i I -· -_ ---~ -···. -· ---I I \' ! I I . .. . . --. . - ---0 I : i ·-I . .. -. . ·--. - ---. 5 'i: 11 1• :1 20 '. 35 50 65 80 95 110 12,~ Time of Concentration . t.. (min.)
4 H-O o \AJ~ri Tiu.c r~ ~s-o '~loo '-::::::
~~o . V-f .. :
..::::; \ ·o-e. wA i....:(_ , • . .. • ? so ' x. 41 1 --
1/R.\W \VA\? (@-~c.co~
--W TA ~ -
?S: o ao ~~ )
Discharge is as follows and as shown by plan in Appendix #8.
Direct discharge to adjacent property along south edge of property 630 sf
Direct discharge to Deacon St. at west end 5,440 sf
Direct discharge to Deacon St. from sidewalk and driveways 2 ,000 sf
Direct discharge to Deacon St. along north PL between sidewalk
and detention wall and/or berm 670 sf
Direct discharge to Texas Avenue along east PL between
detention wall and PL 260 sf
Discharge via detention system 28 ,000 sf
TOTAL DISCHARGE AREA 37,000 sf
12 APPENDIX#?
0
Q~lS/\J (to~ VoL-uM£ IZ:oi£wi12£1'tjB\JU
CM I.I LA -(LotJ /-{ E: [ 11 o 0 -fa;i\-1~ W L-lrll-4'( J711..0 <>-il-11-f-D, P .
@_, Q,.. -01s~A!l4e-ft._<-<>u.1er'J -'f.<fG.LfuJ-/.1f(/ot70ia.) ::-Z.>Z---~~lJ
V~r>cv-Oe-r&1-'(toN. Col.,,_e:-c.rtcN. ::::-1.,.rtcF51(f-1,,)
1c 1,0 A f {i:{'4 0 (\Tg fa,orn. &,.I tf ~ 2., 3 ~
I ~It l ~00 x.. . 5 x. G, I I 'f ::::-'::> S-2-G:.
·-i :? 1 'tvo '/\. , ~ X Z. '3 & ~ --z,o 25'~
·~-~01~ VDw.JfYti!:---~'f78"'Cf.
4eio iio a -sec....
~Q-i~ -(),SatA-~A1.-wu.?eO-i.ct1-o/1 ~ ':! }.q 7 ~~ (P-'3)
?~°'~ ~I6lT;0 ,.i CoL-LZqiOt~ ;;. s-, zoc._p-;(f-2)
,,. A--rr~ u ""re fiiovtA. -D.z,o --"' l .C'.1 7
lc10
: ~-i-( .:7~e ~ 4'1~
!1.q· -l 7 7-;
l,o 1 i?o~ll;fltM JQt--U M-e" VI 0 7 f (
:>€C:....
@-[{.D -01ScttMU.c;;-~<.{)e0 z.;(p ~v.'if: 1.1z,cr-s-u --.)
?~rt-~ aret(Tot~ ~fcN -.:: '1-. :;;~ c.vs(f-z)
.f\{(~;JA(<2 filOvV\ Cf-.SS-~ \.1~
(2111Y1f:' CA,~
\S-0 0
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-\ S-'{ '6'
----Z,~f1 -f(1
14 APPENDIX #9
T
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~TA-"l G ti L-A1L l.l) ei 1£.;
(Li "e Ft.0w hrLMLJ
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r
15 APPENDIX #10 I
Outlet Structure File: DEC
POND-2 Version: 5 .15
Date Execu te d:
.STR
S/N: 1295130055
Time Executed:
*********************
DEC OUTFALL STRUCTURE
I.( ..
~ th OtO &~ ~ ~ c
*****t****t**********
***** CO MPOSITE OUT FLOW SU MMARY ****
Elevation (ft) Q (c fs} Contributing Structures
---------------------------------------------
97 .3 0 0 .0 1
97.4 0 0 .0 1
97.5 0 0 .1 1
97.60 0 .2 1
97.7 0 0.3 1
97.8 0 0.4 1
97.9 0 0 .5 1
98.00 0 .6 1
98.1 0 0.7 1
98.20 0.7 1
98.30 0.8 1
98 .4 0 0.9 1
98.5 0 0 .9 1
98 .60 1 .0 l
98.7 0 1 .0 1
98.8 0 1.1 1
98.9 0 1.1 1
99.00 1. 2 1
99.1 0 1.2 1
99.20 1.2 1
99.30 1 .3 1
99.40 1.3 l
9 9 .50 1 .3 1 ?~ 9 9 .60 1 .4 1
99.7 0 1.4 1
99.8 0 1.4 1
99.9 0 1.5 1 0
10 0.00 1.5 1 ; .s-
100 .10 1. 5 ~ 1 ,,
~ (,.
16 APPENDIX #11
Ane-"1 0 11 TerJ \), 5~1+A rL4-6 CA Le-DLA r1 'o (\J
( Ft.-ocu F ll.o""t W &I 1L)
-s L"o ll.-A-u 0 t:-wv . I @o ,o
& I( f 0 ,·5c.-1-+A (L,&G =: ) , S c P .S ( A17 PG N )7 1'x P:-11)
Wf?t Cl. CJ) l ~l+A-t L0 t ::: 0 , 1 l( e,p) . '3 ,, L-'('I ~ S-
-t-; n . z z 1 ,,. ,..,.~ t..-:: I{) , I/ r i ~ , r: I 0 {flL--V 1 'SC.1-I A:~ :-, L . \-/
l(:: !l ~(H ~,i S
ZS YrL ::: 1. (1'i C\-'J
~ f o {lf\:(?'E 2L--~,,-v . -: qq ,q
b"¢ ri 'scH {\flC,? ~ 1,~C(<;. (!\f (l N01·Xfi-10
LQ e:ia V19:t+A-1!6 c:: >O:~s ~· r s-
'\or1t c., V1sc MArko E: = \.CJ \'.'., ~ 0
,-
3
10 ~(l, -: ) I 7 0 C f-? _,
~'ro(l~IS lZ L.0 0. ·:: 9l{. f
to '1<ji \)1 Sc H (\ (L&? :: l. i C fS CAf pe:l'IVt)<'.
41
\ 0
Lth~·\\L y\5G ~All0 t-:.. (). 5 8 Cf-~ \0i
Toftk Q,s~;,~~f> )~:~:~~
17 APPENDIX #12
.:O~--
:S.· r . ------------: -! .
---·: -! ____ ...
------·-· -·-·
. . . ' . --·· ···-----·---------· ----:----..
-·-·-;-------7"°-----:------·-----
i --------·---~--
-··-·-· _ __; __ :.; __ ~---
. . i .. , •. : _L_ ______ _:.. -'--+---
! . ..
• _i _ : ____ !._:~_c; __ ~
'
'--1 .... -L___:__-+-----·-'~-----'--·'f--+---,,..._,.--. ....!-. -~---~------..:_ __ ----~-
........... ..0
__ . -:---· ~------+-_ _:_ __ :--·~ -·-•---
"! ·-:-_, ·------·-----------' i-
i
I I ______ .;....... ----------l---,j-1--------:----~---;·-·-·--:---:--"t------
----,----=~~-~ , __ ,_•~-tr---~---.~.1~:~~-.~-.L~.-·-···: __ =_1,~_~_-: __ -_ :__ (I_~_t _~:=·--:~ __ J_ ____ : ~--_ ·;...4J _
. . ' ~
I -~-~= ~
_ ___ .._ ----·-·· _ __:___~ _____ _i_ ____ -
·---~:;--: -
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: ··-:~~------
-,~---:--
i •I
,--··
i -·-· --'·-i---:
.. __ L ....... -----:-----------------'._ __ -~~; ---------
----------------. . .
' ---, ---.. -1
. ! j -'--'-'-.. ..._! _-..:.~'t----+., ,_·_ •-.,.--· . . : I .. ' . ----r-----·r-. ·-. ' I . ~---·--,--_-;----~-
... : __ ~--·-: i .. __ : __ : __ ;_:_.' __ + .. L-+ L ------
' f----t·-
1 -----· ------~ -~--'-j~~ _ _j _____ ~--~----------
i . i i • [d ••~~ ~-~· -i··---_t:. -------
' I I . . . . l,--·-4.---:._.t-I -----~----t--; __ ,_
i : ~. :~-l•+-_.;_._---, -~~I --~~-
..
·+ i -. --_;---. ----n :·
i I ·-: -~-.
N
l.
--i ___ :_
18 APPENDIX #13
..
STORMWATER DRAINAGE ANALYSIS
FOR :
RETAIL FACILITY
DEACON STREET@ TEXAS AVENUE
COLLEGE STATION, TEXAS
H & M WHOLESALE, INC. • .
1214 SOUTH COLLEGE AVENUE
BRYAN, TEXAS
BY :
M. L. HAMMONS, P.E.
1700 KYLE SOUTH
COLLEGE STATION, TEXAS
. STORMWATER DRAINAGE ANALYSIS
RETAIL FACILITY
3300 TEXAS AVENUE
COLLEGE STATION, TEXAS
I, M. L. Hammons, P.E ., as Engineer for site grading
and drainage of this development site , by seal and
signature, certify that this analysis and the resultant
facilities design, to the best of my knowledge and
intent, are in compliance with the City of College Station
Ordinance # 1728 for stormwater management.
Date
<6'/2f/1~
•' ,, ~ -~~-
:--
...::_ .. -
-~:~ -__,, --:..:,, ....::. ,,.... _.,
....,.... -,..
'"'
ANALYSIS I I I
SITE DESCRIPTION
The proposed development site for this project is the southwest corner of the Texas
Avenue/Deacon Street intersection (See Appendix #1 , "vicinity map"). The tract is Lot 1,
Block 17, of the Southwood Valley Subdivision , Section 4-B . The street address is 3300
Texas Avenue.
The site is bounded to the north by Deacon Road, to the South by Lot 2 of the same
subdiv ision , to the east by the west access road of Texas Avenue and to the west by a
subdivision alley.
The tract is currently vacant and is vegetated with grass only . There are no trees or
shrubs .
The proposed development usage is for a convenience store with gasoline sales .
EXISTING SITE DRAINAGE
The site is not located in, or eminently near, the 100 year flood plain as identified by
FIRM map #48041C0205C , of 712192 (See Appendix #2, "Flood Plain Map").
According to Figure II - 1 of the Stormwater Management Plan for the City of College
Station as presented by the "Drainage Policy and Design Standards", this site is located
in the Bee Creek Tributary "A" drainage area (See Appendix #3 , "Drainage Area Map").
Current surface drainage is sheet drainage and is generally in a northerly direction with
discharge onto Deacon Street , and Texas Avenue (See Appendix #4, "Site Plan" with
existing Topo), then via street curb and gutter to the drainage ditches at Texas Avenue
and/or Longmire Drive . There are no streams originating on or passing through the tract.
PROPOSED SITE DRAINAGE
In order to comply with City of College Station stormwater management criteria, the post
development stormwater runoff rate will be attenuated to a rate no greater than the pre-
development runoff rate. Control will be accomplished by on -site detention ponding ,
including a controlled flow discharge structure . Ponding will be in two areas , the lower
being located along the east end of the site and the f3 ~er between the two driveways
along Deacon Street. Site discharge will be via 5" J~CP pipe from the discharge
structure, under Texas Avenue access road , into ex1 . mg open ditch drainage .
1
DRAINAGE DESIGN CRITERIA
The 25 year storm event is used as the design storm, with discharge rate design
adjustment to control the 1 O year and the 100 year event. The "Rational Method" of
calculation is used .
With the "Rational Method" calculation, the following values have been established for the
C, I and A formula components :
Direct discharge C = .47
Detention discharge C = .82
(See Appendix #5)
110 = 8.63
125 = 9.86
1100= 11.64 (See Appendix #6)
TOTAL DRAINAGE AREA = 37,000 SF = .849 acres
Direct discharge area = 9,000 SF = .206 acres
Detention discharge area = 28,000 SF = .643 acres
Drainage diagram is shown by Appendix # 8 .
STORMWATER RUNOFF CALCULATIONS
(See Appendix #7)
Based on the C , I, and A factors established herein , stormwater runoff is calculated thus:
PRE DEVELOPMENT RUNOFF
Q =CIA
0100 =0 .35 x 11.64 x .849 = 3.46
025 =0 .35 x 9.86 x .849 = 2.93
010 =0 .35 x 8 .63 x .849 = 2 .56
POST DEVELOPMENT RUNOFF
Direct Discharge
0100 =0.472 x 11.64 x .207 = 1.14
025 =0.472 x 9.86 x .207 = 0 .96
010 =0.472 x 8 .63 x .207 = 0 .84
Detention Collection
2
~iJt~Jvt)
0100 =0 .82 x 11 .64 x .643 = 6.14 1 (J~~G\ ")~;,,,.>-~~I·~ ."1
025 =0.82 x 9.86 x .643 = 5 .20 ~ ~ ~ ¥~, ~
o,, =0.82 x 8.63 x .643 = 4 .55 ~il :I ...t'-1: ~~ ~ ~
STORMWATER DISCHARGE RATE CONTROL ~ ~; toJ/').I~ ~ ~· .
As indicated by the diagram of Appendix #8, part of the post development drainage will l, 'Pf
be discharged from the tract directly to the adjacent street or right of way . The direct ~
drainage is quantified by the calculations as shown on page 2 herein . By deducting the
detention pond discharge flow rate is established as follows : ~
Q100 = 3.46 cfs (pre-dev) -1.14 cfs (direct discharge) = 2.32 cfs
0 25 = 2.93 cfs (pre-dev) -0.96 cfs (direct discharge) = 1.97 cfs
Q10 = 2 .56 cfs (pre-dev) -0.84 cfs (direct discharge) = 1.72 cfs
Pond volume. and discharge flow .rate determinatiol'ls are based pn these all~wables .
The attenuated stormwater discharge , from this site , is via a discharge outlet structure
(See Append Lr-#10, "Flow-Control Discharge Structure Sketch) in the lower of two
interconnected detention ponds. There is no flow constriction between the upper and
lower pond , thereby rendering the pond storage and flow characteristics as one. With the
discharge structure openings as shown by the Appendix# 1 O drawing , discharge -liquid
eleva ti on relationships are thus :
STORM ATTENUATED LIQUID
EVENT DISCHARGE ELEVATION
100 YR. 2 .24 cfs (Appendix #12) 100.0
25 YR. 1.98 cfs (Appendix #12) 99.9
10 YR. 1.70 cfs (Appendix #12) 99 .8
Discharge rates have been determined us ing the "Haested Methods" software program
to establish flow from the 6" round opening , combined with manual flow calculations for
the rectangulars · weir at the top of the structure . The rectangular weir calculation is
shown by Appendix #12 and the Haested data is shown by Appendix #11 .
STORMWATER DETENTION
The Stormwater detention system , as previously identified herein, is a two pond system
connected by a 12" storm drain pipe . The lower pond, located near Texas Avenue, will
conta in about 53% of the maximum storm detained run-off while the upper pond and the
transf er pipe contain the remainder. Detention requirements are calculated according to
3
the "simplified hydrograph" method as presented by the City "Drainage Policy and Design
Standards" manual , page 75 . (See Appendix #9, "Detention Volume Requirements"). The
calculated storage volume is 4150 cubic feet. The elevation low point of the detention
system is 97 .3, at the discharge orifice . The overflow level, (which exceeds the 100 year
event requirements), is at elevation 100.2.
Pond storage volumes provided and pond storage volumes required at various levels are:·
(See Appendix #13)
ELEVATION
97 .3
98.0
99 .0
99.8
99.9
100 .0
100.2
POND VOLUME
0
145 ft 3
1,070 ft 3
2,550 ft3
2.900 ft 3
3,400 ft 3
4 ,150 ft 3
POND REQUIRED
2 ,550 ft 3
2.900 ft 3
3 ,400 ft 3
Detention storage volumes are calculated as shown by Appendix #12 .
PHYSICAL CHARACTERISTICS
With stormwater detention as described herein and as indicated on site grading and site
landscaping plans, the detention ponds are an integral part of the landscaping areas . In
order to achieve the required liquid storage volumes , vertical walls are used along
portions of the pond perimeters . The walls are to be hand finished concrete . The
greatest differential elevation between the wall top and the adjacent pond floor is 4.0 feet
at the Texas Avenue frontage . The wall top elevation along Texas Avenue is slightly (0 .3
to 0 . 7 feet) higher than the top of the street curb, thus allowing city landscape
requ irements to prevai l. The pond wall characteristics along Deacon Street are
essentially the same except the maximum wall height is approximately 2 feet.
CONCLUSIONS
Peak run -off due to development will be attenuated adequately to provide no increased
runoff rate through the 100 year rainfall event.
No run-off is routed to other channels or tributaries .
No negative downstream impact is anticipated .
4
APPENDICES I I
APPENDIX #1
APPENDIX #2
APPENDIX #3
APPENDIX #4
APPENDIX #5
APPENDIX #6
APPENDIX #7
APPENDIX #8
APPENDIX #9
APPENDIX #10
APPENDIX #11
APPENDIX #12
APPENDIX #13
VICINITY MAP
FLOOD PLAIN MAP
DRAINAGE AREA MAP
SITE PLAN w/topo
"C" -FACTOR DETERMINATION
1-D-F CURVE
SITE DRAINAGE AREA DETERMINATION
SITE DRAINAGE DIAGRAM
DETENTION VOLUME REQUIREMENTS
FLOW CONTROL DISCHARGE STRUCTURE
6 11 ROUND OPENING OUTFLOW RATES
RECTANGULAR WEIR OUTFLOW RATES
CHART -VOLUME/ELEVATION/STORM EVENT
5
I>-\ \ \ \ ~ § SITE < \ / \ \ \ \ .. If ~ --.; ... "" I ·--, s L. T"'s\ N ,. \ \ I \\ ~ _/ 6 I APPENDIX #1 I I
A
51TE
Brazos Co unty
Unin co rp orat e d Areas
481195
7
B
C)
City of College Sta1
480083
APPENDIX #2
CP
)>
"1J
"1J m z
0
x
~ w
B
STATiO"'NI
' '
I
01
-i j
-</ ~
C:/ ~
!1 0 -i fT1 (/)I
I
~ ----\ ~
('\ n@ ..
~ '
\
~ 0 > :; .......
?: ' '~ 0 c
-1 :r
....
.w. PARKWAY
------
CJ) ----
\
\
l
\
G
C)
:tl
0 < l'TJ
C-FACTOR DETERMINATION
PRE DEVELOPMENT
Total Drainage Area Considered . . . . . . 37 ,000 sf*
"C " . . . . . . . . . . . . . . . . 0 .35
POST DEVELOPMENT
Direct Discharge :
South side
West end
Sidewalk & Driveways
Deacon St. PL
Texas Avenue PL
Total Direct Discharge
Detention Discharge :
Impervious areas
bldgs
paving
sidewalks, etc.
Landscape areas
Total Detention Discharge
TOTAL P/D DISCHARGE
* See Appendix #7
630 sf
5, 440 sf
2,000 sf
670 sf
260 sf
9,000 sf
23,960 sf
4 ,040 sf
28,000 sf
37,000 sf
10
0.35
0 .35
0 .90
0 .35
0 .35
0.472
0 .90
0.35
0 .82
0 .735
APPENDIX#5
~ ~ )> ""U ""U rn z 0 x ~ O'> II ::tJ Q ::9 -Q -::J -C9 ::9 Cilt -'< --· -? ..... ::r ~ I __ 1 -----'---'----' ' I I I : -----· -----I II I 1 · -14t-! I: I· I ... ' , , .. .. I ·: . ! i~ ~ I I I I l I . I . • --. j t_j_·· +-+-+-11 12M-o-I 4-·1-H· I~ If I limffi I!~, i-·oo· i·m-·--·--·---j~-· ~~~--r-! _ -_ _ _ . _ T IC .1 C B ~ ' ( U T 0 R VI E ) Jl11 I,, .•. -.. ·· --~ ~ --~ -JJb_1-1r.r11rc: -~ t _ --_ _ ~ ~ J~ _ i-_ -_ -: -----r --_ --. -_ 8 ' -+--t--+-+-t-t-+-+-t--;t"--t::-:-t-+-t-t-+-+--+--+---r-.-+-t-1--+--+-+--+-+-~-t-f--+--+-!--+-+--+--+-++-i;...+--+----· ----·-----t--.·-· 1 I ·-----· · --------------~ --· ---· --6~ -+-'~-t~-r-G-~~+-f"d~-+-+--+--+--+-+-t-t-+-+--+--r--+-+-+-t-t--+-+--+-+--+-+-t-t-+-+-+--+--+--+-.J=.-c..:.;.+~ l --·-------------· ----· -·-. -· ---.. ------·--··----···-· ··------------4t--r--t-+-t--+--+-+-t--t"'-<t-+-f"-.:t:--t-+:"~t-i--.-f"""'+!~-Yz~~~t-t-+-t-;,Lf--t---+-+-t--=-1-+-+-+--+---+-+-+-1c-+-+--!'!!~Y---l-I v -1 -. ----' ---·;· -. I ... 2rt-:-~11-t1--+-i-t-t--f-l-=t=±~~t-~~~-t-f=t=rt=t::P.lf1~::f~~~t:E3:I=±=tJ=±=t=tJc1=±j I , I ' I 1-1 I ---_ ~---~ -_ --. I ~-~--~-0 ·ll1l1 !I I -----: ---5 ',; 11 I' :i 20 . -35 50 65 80 95 110 Time of Concentration • •~ (min.)
I f
1-.AN D O \~ ~fl--Tll!.C. :-~ ~SD x:_ l 00 -::::::: \
~~o. \A/-:
~\O ~ WAL-\L ,, .. ., • ?so ''>( '1-' --
f,;R .lW\VA\? (@-~~~
--W TA-4 -
Discharge is as follows and as shown by plan in Appendix #8.
Direct discharge to adjacent property along south edge of property 630 sf
Direct discharge to Deacon St. at west end 5,440 sf
Direct discharge to Deacon St. from sidewalk and driveways 2,000 sf
Direct discharge to Deacon St. along north PL between sidewalk
and detention wall and/or berm 670 sf
Direct discharge to Texas Avenue along east PL between
detention wall and PL 260 sf
Discharge via detention system 28,000 sf
TOTAL DISCHARGE AREA 37,000 sf
12 APPENDIX#?
0
Q~'f£./\J (tow VoLuM£ \Z;c£_~i1Z-t1"'/Ei'1Q
CM IJ LI\ f tot\l r.{ E: ( 1-j 0 0 -fa;11:1•w 1../.-IZ-~'(J7 /l..O G.a.-a-p-D. p .
Cl Q ' A .(p-~) ~ 1"0 -O,s~A-tl4~ ft1.--c..ow er-; -~. <fG..{fu) -l.1 f (((){r O;a,) :::-i . > z.__c r-s
VtS-PtlL-De-r<S--1-'(toN. Coi...LiE-C..(tcN.. ::=-t,.t'fcF-5 J(f-"Z.)
1c 1
1
o 4 r Ti:{" u A-\g PMrn. LR .1 ~ ~ 2-, 3 z,,
_fu i t l g""oo x.. .5 X l., 1 'f :::. '-::> ~Z,(p
:z,, 7 J 'lvo X. , ~ X Z. '3 & -== --z,o g--?
·~ ~~1~ Jow.Jme---"3f~g>'Cf .
4oo iioo
":)e C-
@-Q,~ -01.ScitAftkG<-~<.VeO z..~t,, ~v.'if-: i.1z..as-U -~)
?~rt-I:'-\1-r::i.qf 01-1 ~fDI\\ "'-4 . :;;-;-c,vs (f-z)
~:((~JJA r <2 ftlOvV\ er.SS-~ \ ,1 i,
f06\ s-
-\ S-l{ cgr
----~~+1 f ()
\SOO
14 APPENDIX #9 ·I
T
~Tf-t1,1Gti L-A1L L-t)ei jl.,;
( u "e:-Fi...0w hrLMJJ
CJ .v'·~-\ ::~,L-1
r
15 APPENDIX #10 I
Outlet Structure File: DEC
POND-2 Versi on: 5.15
Date Executed;
.STR
S/N: 1295130055
Time Executed:
*********************
DEC OUTFALL STRUCTURE
***** COMPOSITE OUTFLO W SUMMARY ****
Elevation (ft) Q (c fs ) Contributing Structures
---------------------------------------------
97.30 0.0 1
97.4 0 0.0 1
97 .5 0 0.1 1
97 .60 0.2 1
97.7 0 0.3 1
97 .80 0.4 1
97.9 0 0.5 1
98.00 0 .6 1
98.1 0 0.7 1
98.2 0 0.7 1
98.3 0 0.8 1
98 .40 0.9 1
98 .50 0.9 l
98 .60 1.0 1
98.7 0 1.0 l
98.80 1.1 1
98 .90 1.1 1
99 .00 1. 2 1
99.1 0 1 .2 1
99.2 0 1.2 1
99 .30 1.3 1
99.40 1.3 1
99.5 0 1.3 1 ?~ 99.60 1 .4 l
99.7 0 1.4 1
99.8 0 1 .4 1
9 9.90 1 .5 1 CJ
10 0.00 1.5 1 ; .s-
100.1 0 1. 5 ~ 1 ,,
~ <";..
16 APPENDIX #11
A-rre"1 DA TerJ '71s~1-1 -A ~8 CA LC DcATJ,o<\J
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17 I APPENDIX #12 I
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18 APPENDIX #13
'
August 29 , 1995
CITY OF COLLEGE STATION
Post Offic e Box 9960 1 10 1 Texas Avenue
College Station, Texas 77842-9960
(409) 764-3500
Texas Department of Transportation
1300 N. Texas Ave .
Bryan, TX 77803-2760
Attn : Jay Pag e
RE: H&M Wholesale located at the southwest corner of the Deacon/Bus. 6
frontage road
Dear Jay :
It is my understanding that Roy Hammons has been in contact with you regard ing the
above referenced project. I've attached the drawings as well as the permit application .
The City has made redline comments which the applicant has not addressed because of
coordination th at may be needed between the three of us . We would appreciate it if you
would review this at your earliest convenience and if necessary contact me or th e appl icant
for additional information . Because this area is one that we may maintain throu g h our
maintenance agre ement, we would like to enforce our 18" minimum pipe size . It is
difficult for us to clean anything small er .
If you'll note, I have not signed the permit and will withhold signature while we work
tog ether to get Mr. Hammons a complete set of comments/concerns .
attachments
cc : Shirley Volk, Development Coordinator
Steve Homeyer, Graduate Engineer
Samantha Smith, E ng ineering Asst.
Roy Hammons
file
H o me o f Texas A&M University
Notice of Proposed Installation
Utility Line on Non-Controlled Access Highway
Form 1023 (Rev . 9 ·93)
(Pre vious version(s) are obsolete.)
To the Texas Transportation Commission
clo District Engineer
Texas Department of Transportation
-------------, Texas
Date August 14 1 995
Formal notice is hereby given that __ H~-&~M~l_fu_o--=l_e_s_a_l_e ______________________ _
Company proposes to place a s tom drain culvert
line within the right-of-way of Hwy 6 (Texas Ave)
Texas as follows: (give location, length, general design, etc .)
in College Station. Brazos County,
I n t e rsect i on -Texas Avenue @ Deacon Stre e t , Colleg e Station
Pla c ement -Across West Access Lanes (to drain SW quadrant to ditch)
Leng th -50 +/-fro~ property line to d i scharge
Const r uction -Road bore, 15" pipe
The line will be constructed and maintained on the highway right-o f-way as s hown on the a t tached drawing and in
accordance with the rules, regulations and policies of the Texas Departme nt of Transportation (TxDOT), and all
governing laws , including but not limited to the "Federal Clean Water Act," the "Federal Endangered Species Act," a n d
the "Federal Historic Preservation Act ." Upon request by TxDOT, proof of compliance with all governing laws , rules, a n d
regulations will be submitted to TxDOT before commencement of construction.
Our firm will use Best Management Practices to minimize erosion and sed im entation resulting from t he propo sed
installation, and we will revegetate the project area as indicated under "Revegetation Special Provisions ."
Our firm will insure that traffic control measures complying with applicable portions of the Texas Manual of Uniform
Traffi c Control Devices will be installed and maintained for the duration of this installation.
The location and description of the proposed line and appurtenances is more fully shown by __ O_n~e-~<-1~) __ complete
sets of drawings attached to this notice .
Construction of this line will begin on or after the 1st day of ___ S~· e~p~t_em_b_e_r ___ ,19 9 5
By signing below, I certify that I am authorized to represent the Firm listed below, and that the Firm agrees to the
cond itions/pro vi sions included in this permit.
F irm H & M Wholesale
Si gnature --~#-/+,l~/.,M<fl{'1-'"'----'~IL'-'Cl.l.ll'~v~vv::__-~'-l. 1L:Ar--'':£=. _______ _
By (Print) _1_M ,~-tfJ-f-i-J:a--r-mm-+----+-.-. _. ~--./---
T it le ------=E=-~n=~>-=i:..::nc::_e=e-=r-,.;.·--------------
Address ___ 1_7_0_0 __ K.:_y_l _e_S_o_u_t"-h _ __::_S...:..u .c::.::i -=t -=e'---2_4_0 ___ _
Phone No.
~n ... -....ci-1
W " .. -·
Coll eg e Station, Texas
696 :-1 444
Printed by Samantha Smith
From: veronica Horgan
To: Kathryn Anthony
Subject: maintenance responsibility?
===NOTE===============8/28/95==9:26am==
CC:
Kent Laza, Samantha Smith, Steve
Homeyer
do we have the maintenance
responsibility for storm drains
constructed under the bus. 6 frontage
roads? in particular i am talking about
those near deacon and in front of
walmart???? h&H wholesale is going to
be building at the corner of deacon and
bus.6 frontage (across from where the
new wings&more is going up). they have
to put a new storm drain under the
frontage road to drain their detention
pond into the roadside ditch between
the frontage road and mainlanes. our
drainage ordinance calls for an 18"
minirm.rn pipe size and they want to put
in a 15 11 • they tell us that the state
will allow the 15" Ci'm checking on
that now). i'm standing firm on the 18 11
min. because from what i understand it
is our maintenance responsibility and
we have a hard time cleaning anything
less than an 18 11 pipe.please let me
know what you think.
Page: 1
8/29/95 3:18pm
STORMWATER DRAINAGE ANALYSIS
FOR :
BY :
RETAIL FACILITY
DEACON STREET@TEXAS AVENUE
COLLEGE STATION, TEXAS
M. L. HAMMONS, P.E.
1700 KYLE SOUTH
COLLEGE STATION, TEXAS ~~-~=~~~~~~~·~~~~~~===~=J
•
STORMWATER DRAINAGE ANALYSIS
RETAIL FACILITY
3300 TEXAS AVENUE
COLLEGE STATION, TEXAS
I, M. L. Hammons, P.E., as Engineer for site grading
and drainage of this development site, by seal and
signature , certify that this analysis and the resultant
facilities design, to the best of my knowledge and
intent, are in compliance with the City of College Station
Ordinance #1728 for stormwater management.
ANALYSIS I I I
The proposed development site for this project is the s uthwest corner of the Texas
Avenue/Deacon Street intersection (See Appendix #I , "vi 1. ·ty map"). The tract is Lot 1,
Block 17 , of the Southwood Valley Subdivision, Section 4 3 The street address is 3300
Texas Avenue .
The site is bounded to the north by Deacon Road , to the South by Lot 2 of the same
subdivision, to the east by the west access road of Texas Avenue and to the west by a
subdivision alley .
The tract is currently vacant and is vegetated with grass only . There are no trees or
shrubs .
The proposed development usage is for a convenience store with gasoline sales .
EXISTING SITE DRAINAGE
The site is not located in , or eminently near, the 100 year flood plain as identified by
FIRM map #48041C0205C , of 712192 (See Appendix #2, "Flood Plain Map").
According to Figure II - 1 of the Stormwater Management Plan for the City of College
Station as presented by the "Drainage Policy and Design Standards", this site is located
in the Bee Creek Tributary "A" drainage area (See Appendix #3 , "Drainage Area Map ").
Current surface drainage is sheet drainage and is generally in a northerly direction with
discharge onto Deacon Street , and Texas Avenue (See Appendix #4, "Site Plan" with
existing Topo), then via street curb and gutter to the drainage ditches at Texas Avenue
and/or Longmire Drive . There are no streams originating on or passing through the tract.
PROPOSED SITE DRAINAGE
In order to comply with City of College Station stormwater management criteria, the post
development stormwater runoff rate will be attenuated to a rate no greater than the pre-
development runoff rate . Control will be accomplished by on-site detention ponding ,
including a controlled flow discharge structure . Pond · wi be in two areas , the lower
being located along the east ·end of the site and th upper etween the two driveways
along Deacon Street. Site discharge will be vi a 15" R P pipe from the discharge
structure, under Texas Avenue access road , in existin open ditch drain g
~
1
. ' I ,.
I
\ •
,.
DRAINAGE DESIGN CRITERIA
The 25 year storm event is used as the des1 n storm, with dischar rate design
adjustment to control the 1 O year and the 100 ye event. The " ·anal Method" of "~~
calculation is used . \~~
With the "Rational Method" calculation, the following values have been established for the ~D
C, I and A formula components :
Direct discharge C = .47 ./
Detention discharge C =. 82
(See Appendix #5)
110 = 8.63
125 = 9.86
1100= 11.64 (See Appendix #6)
TOTAL DRAINAGE AREA = 37,000 SF = .849 acres
Direct discharge area = 9,000 SF = .206 acres
Detention discharge area = 28,000 SF = .643 acres
Drainage diagram is shown by Appendix # 8 .
STORMWATER RUNOFF CALCULATIONS
(See Appendix #7)
Based on the C , I, and A factors established herein , stormwater runoff is calculated thus :
PRE DEVELOPMENT RUNOFF
0 =CIA
0100 =0.35 x 11 .64 x .849 = 3.46
025 =0 .35 x 9 .86 x .849 = 2.93
010 =0 .35 x 8 .63 x .849 = 2.56
POST DEVELOPMENT RUNOFF
Direct Discharge ~
0100 =0.472 x 11 .64 x .207 = 1.14
0 25 =0.472 x 9 .86 x .207 = 0 .96
010 =0.472 x 8.63 x .207 = 0.84
Detention Collection
0100 =0 .82 x 11 .64 x .643 = 6.14
025 =0 .82 x 9 .86 x .643 = 5 .20
010 =0 .82 x 8.63 x .643 = 4 .55
z
STORMWATER DISCHARGE RATE CONTROL
As indicated by the diagram of Appendix #8, part of the; post development drainage will
be discharged from the tract directly to the adjacent street or right of wa . The direct
drainage is quantified by the calculations as shown ab ve By deduc ion the direct
discharge runoff flow rate from the pre-development runoff flow rate, ttie allowable
detention pond discharge flow rate is established as follows :
0 100 = 3.46 cfs (pre-dev) -1.14 cfs (direct discharge)= 2 .32 cfs
0 25 = 2.93 cfs (pre-dev) -0.96 cfs (direct discharge) = 1.97 cfs
0 10 = 2 .56 cfs (pre-dev) -0.84 cfs (direct discharge) = 1.72 cfs
Pond volume and discharge flow rate determinations are based , these allowables .
The attenuated stormwater discharge, from this site , is vi a discharge outlet structure
(See Appendix #10, "Flow-Control Discharge Struct Sketch) in the lower of two
interconnected detention ponds. There is no ·flow n i tion between the upper and
lower pond, thereby rendering the pond ystem na t ri~ics as one. With the
discharge structure openings as shown by the pp, !m d· drawing , discharge -liquid
elevation relationships are thus :
STORM
EVENT
Discharge rates ave been determined using the "Haested Methods" softwa e progr
from the 6" round opening, combined with manual flo ca culations for
and the Haested data is shown by Appendix #11 .
STORMWATER DETENTION
The Stormwater detention system, as previously identified herein, is a two pond system
connected by a 12" storm drain pipe . The lower pond, located near Texas Avenue, will
contain about 53% of the maximum stefm detained run-off while the upper pond and the
transfer pipe contain the remainder. Detention requ irements are calculated according to
the "simplified hydrograph" method as presented by the City "Drainage Policy and Design
Standards" manual , page 75 . (See Appendix #9, "Detention Volume Requirements"). The
calculated storage volume is 4150 cubic feet. The elevation low point of the detention
system is 97 .3, at the discharge orifice . The overflow level, (which exceeds the 100 year
event requirements), is at elevation 100 .2 .
Pond storag olu es provided and pond storage volumes required at various levels are : t') ELEVATION POND VOLUME POND REQUIRED
97.3
98 .0
99 .0
99.8
99 .9
100 .0
100.2
0
145 ft 3
1,070 ft 3
2 ,550 ·ft 3
2 .900 ft 3
3,400 ft 3
4,150 ft3
2 ,550 ·ft 3
2 .900 ft 3
3 400 ft3
I
Detention storage volumes are calculated as shown by Appendix #12 .
PHYSICAL CHARACTERISTICS
With stormwater detention as described herein and as indicated on site gradin d site
landscaping plans , the detention ponds are an integral part of the landscaping ar as. In
order to achieve the required liquid storage volumes, vertical walls are used long
portions of the pond perimeters . The walls are to be and finished concrete . he
greatest differential elevation between the wall to and the adjacent pond floor is 3.~5 1
feet at the Texas Avenue frontage . -Pta ntm pt anrred fo r t:>oth sides of the wall ,
..M-J.J....--,,,...::s~e ciA~rU1e visual imp.a ct ~frnm he site) of the grade separation . The wall top
elevation along Texas Avenue is slightly (0 .3 to 0.7 feet) higher than the top of the street
curb , thus allowing city landscape requirements to prevail. The pond wall characteristics
along Deacon Street are essentially the same except the maximum wall height is
approximately 2 feet.
CONCLUSIONS
""" Peak run-off due to development will be attenuated adequate t o provide no aee+Hooa! ..
runoff C ough the 100 year rainfall event.
No run-off is routed to other channels or t ributaries .
No negative downstream impact is anticipated .
I I I S3~1CN3dd'1
APPENDIX #1
APPENDIX #2
APPENDIX #3
APPENDIX #4
APPENDIX #5
APPENDIX #6
APPENDIX #7
APPENDIX #8
APPENDIX #9
APPEND IX #10
' \
) \
I\
\
\ ,_,
)
VICINITY MAP
FLOOD PLAIN MAP
DRAINAGE AREA MAP
SITE PLAN w/topo
"C" -FACTOR DETERMINATION
1-D-F CURVE
SITE DRAINAGE AREA DETERMINATION
SITE DRAINAGE DIAGRAM
DETENTION VOLUME EQUIREMENTS
FLOW CONTROL DI CHARGE STRUCTURE
~ \lf ~l
Ou ) ~ l (
v IJ \
J / ( c
-L..;.. •
·. o;(i~!'.-}' ~
.. <.~--:.. §
I(
SITE
< \
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1 --,
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\ N TS \
\
APPENDIX #1
A
51TE
Br azos Co unt y
Unin co rp orat ed Areas
48 11 95
7
B
C)
City of College Sta1
480083
APPENDIX#2
)>
"1J
"1J m z
0
><
::ti: c.v
srATlo"NI
' '
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0 1 -q
-<I
'=I ~,
....; (/)I
I
----\
-------
\
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0
\
C-FACTOR DETERMINATION
PRE DEVELOPMENT
Total Drainage Area Considered . . . . . . 37,000 sf*
"C" . . . . . . . . . . . . . . . . 0.35
POST DEVELOPMENT
Direct Discharge:
South side
West end
Sidewalk & Driveways
Deacon St. PL
Texas Avenue PL
Total Direct Discharge
Detention Discharge :
Impervious areas
bid gs
paving
sidewalks, etc.
Landscape areas
Total Detention Discharge
TOTAL P/D DISCHARGE
* See Appendix #7
\0
630 sf
5, 440 sf
2,000 sf
670 sf
260 sf
9,000 sf
23,960 sf
4 ,040 sf
28,000 sf
37 ,000 sf
0 .35
0 .35
0.90
0 .35
0.35
0.472
0 .90
0.35
0.82
0.735
APPENDIX #5
-_.... )> -u -u m z 0 -x ~ O> :::0 Q :::J -Q -:::J -~ :::J Cll -'< ---:::J ....... ::T' ~ 14 . . . . .. :· · .. ·~· --. :t . l ~.· -. -. :. -. -: -: ~ ~ ~-t _: . .~ .. -. . . -· -. -·--t ---· ----------. . -··-. ---·-·· . ~ ·-81--1'--'l.--+_.___,.._-+-~ ~'--t-t-+-+-+--+--+-+-'~+--:-t-il--l-+-+-+-t--+--t-+-+-+-+-il-+-t-+-1--+-+-+-+-~~l---1--+-+-+:J-1;~~ i -~---~ ----~ -~ -~ - . ---·· --. -I ----6~·+-'\-~-f'.....-f---+'~-t--i""<o~:-1:--t--t-l!-t-t-+-+-+--+--+--t-+-t--t-1'--t-t-+-+-+--+-+-+--t--t---jl-+-t-+-+--4--F:....;..:..;~ --··--··---·-----·-· ----·-·-··----······--------·-· -·---·------. . ·•· -· ··-----. . -- -------t--11---t--+--l.&-4 ~1-+-+-+--4---+-+-+-~!--f---1'"""'d:-+-+~d---+-....:po.~~~f::::;j~..,;::J--+-+-H£f--+-+-4-~1-+-+-+-+-+-+--+-+-4-+-~~-+~ ' .. v -1 ·--1 ·-····· --I . ·, ---2r+:. ~,tttl+1+1t1tti1-tl_~_t __ t __ t .... tttitiTI=HFt:Pfttt_t_i __ iJ:E3J_i±i±±±±±±l I I ----. ---r -·· ... --· -··1 ---\' ! I I . . -----------' ---0 I : l I .. -------. ----. ,___, _ _,___ ... 5 ',i II I' :1 20'.· 35 50 65 80 95 110 IZ~ Time of Concentration • t... (min.}
G.A r-HJ O \~~ri TiZ-A c:--; ~s-o ' ~loo ~
\
~~o. vy# :
~\-Oe'.. WAL-'(_ , . . ., • ?so'>( '1' --
~·lW \VA\? (@-~~~ --
175-rA..,._._~ -
Discharge is as follows and as shown by plan in Appendix #8.
Direct discharge to adjacent property along south edge of property 630 sf
Direct discharge to Deacon St. at west end 5,440 sf
Direct discharge to Deacon St. from sidewalk and driveways 2,000 sf
Direct discharge to Deacon St. along north PL between sidewalk
and detention wall and/or berm 670 sf
Direct discharge to Texas Avenue along east PL between
detention wall and PL 260 sf
Discharge via detention system 28,000 sf
TOTAL DISCHARGE AREA 37,000 sf
APPENDIX #7
U_ssN [tow VoL-uM£ IZ£c£wi1z£1't/8'1Q
r\"
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4-fft?:1~ u I\ re ftLoAA -s:. zo ----> l .ct 7
""--.......-~
( '7kv>te-~
-117-;
iZ.cQil;(U!N) JQ1.,;u r'V\-C ---z_,q 0 7 f(7
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'4 APPENDIX #9 I
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APPENDIX #10 I
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IX. Detention Facilities I /J
A.
B.
General ~ " I The purpose of a detention facility. is to store excess
volumes of stormwater runoff and discharge it at a
predetermined controlled rate. Typically, this is done to
limit post development discharge rates to those that existed in
existing conditions for a range of design storms. The following
sequence of design storms shall be used until the maximum
design storm is reached: 5 year, 10 year, 25 year, 50 year, 100
year.
Detention faci 1 ities may be site or development specific,
their purpose being to protect immediate downstream properties
and drainage systems. An example of this would be a detention
facility in a large parking area to avoid overwhelming adjacent
streets and storm sewers of the secondary drainage system.
Typical methods utilize parking lots, landscaped areas, and
rooftops formed into depressions that drain dry between
rainfall events.
Detention facilities also may be regional, receiving
stormwater from many developments and sites. Here the limiting
capacity is that of the drainage system that traverses an
existing developed area. This type of facility requires a
large land area to develop the required storage and thus is
usually designed for multiple uses compatible with its
stormwater purpose. Typically, these are combined with
greenbelt and recreation areas centered around a permanent
storage area designed to hold water between rainfall events.
Design Parameters
1. Design Storm
All detention facilities located in
drainage system that are site .or deve 1 opment
use a maximum design storm based upon
the secondary
specific shall
the specific
detention requirements. These requirements are based upon
the requirements of the other sect i ans of these standards
70
2.
and the effect the deve 1 opment wil 1 have on the receiving
facilities of the secondary drainage system relative to
performance standards and pathway requirements. In
addition, a design storm having a return period of 100
years shall be evaluated to check emergency overflow
requirements of the detention facility and the effect of
resulting flows on downstream drainage systems.
All detention facilities located in the primary
drainage system (regional) shall use a maximum design storm
having an average return period of 100 years or greater .
Delineation of Drainage Area
The land area contributing
detention facility shall be
runoff to the proposed
determined for the pre-
development existing condition and the post-development
expected condition.
3. Pre-development and Post-development Hydrographs
A pre-development hydrograph shall be determined
representing the drainage area and land cover conditions
that exist prior to the proposed development.
A post-development hydrograph shall be determined
representing the drainage area and land cover conditions
that exist after ultimate development occurs within the
land area that contributes runoff to the detention
facility.
Hydrographs sha 11 be determined using the appropriate
methods from Section III of the guide.
4. Determination of Storage Volume
Storage vo 1 ume sha 11 be determined such that the peak
discharges of the ultimate development hydrographs for the
design storms from the detention facility shall be limited
to values less than the target discharges. The target
d~scharges shall be equal to or less than the peak
discharges of the pre-development hydrographs for the
design storms.
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The required storage volume may be taken as the
difference in area between the pre-and post-development
hydrographs as shown in Figure IX-1. The outlet structure
shall be sized such that the design storage volume will
occur at a depth that corresponds to the target discharge.
This method shall be limited to detention facilities whose
hydrographs may be determined by the rational method. All
other detention facilities shall have the storage volume
determined from Storage-Routing Analysis procedures.
5. Storage-Routing Analysis
The basis of this method is the continuity equation
stated thus:
Iavg -Oavg = dS/dt, where
Iavg = the average inflow over time period t
Oavg = the average outflow over time period t
dS = the change in storage
dt = the designated time period
Substituting subscripts of 1 and 2 for beginning and
end of time period respectively,
yields the final equation.
and re-arranging terms
2s 1
(I 1 + I 2 ) + ( ---
dt
2s 2
- o1 ) = <---+ o2 )
dt
The use of this procedure is based upon severa 1
assumptions:
The inflow hydrograph is known.
The starting conditions of storage volume and
outflow are known at the beginning of the routing.
The discharge rate at the outlet structure(s) is
only a function of the head available.
The relationship between depth and storage are
known.
The time period "dt" shall be taken as less than or equal
to 1/St (time of concentration). c
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J
Outlet Structures
a. The design of outlet structures shall consider the
conditions for all design storms. The outlet structure
/sha 11 limit the peak discharge to less than the peak
discharge that existed under predevelopment conditions
for all design storms.
b. All outlet structures shall be designed to allow the
facility to be drained dry by gravity. This does not
/ include those facilities designed to have a permanent
storage component.
c. An emergency overflow outlet shall be provided with a
capacity to carry the peak discharge from a 100 year
storm for ultimate basin development conditions. This
discharge must be directed and limited to prevent
/damage to adjacent properties and hazards to life. In
addition, this discharge shall be evaluated for its
effect on the downstream receiving drainage systems,
and shall not exceed its capacity to control and
contain the ultimate condition discharge.
d.
J
Analysis
methods
Inlets,
Section
and design of outlet works shall use the
and guidelines in Sections V -Storm Drain
Section VI -Enclosed Storm Drainage Systems,
VII -Open Channel Flow, and Section VIII -
Culverts.
C. Physical Characteristics and Limitations
1. Side and Bottom Slopes
a. Side slopes shall not exceed 4:1 for vegetative cover
and 2:1 for non-vegetative cover.
b. Bottom slopes must be 20: 1 or steeper .directed to the
low flow outlet for facilities designed to drain "dry"
between rainfall events.
c. A low-flow invert shall be provided for all facilities
which have a vegetative cover on the bottom. Design
shall be consistent with Section VII -Open Channel
Flow.
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