HomeMy WebLinkAboutZMA200400024 Stormwater Management Plan 2006-01-11m
LEGEND
DRAINAGE AREAS
FOR STORMWATER DETENTION BASINS
DRAINAGE AREAS
MENEM FOR BIO-FILTER FACIU71ES
STORMWATER DETENTION
BASINS
CONSERVATION I PRESERVATION
AREAS
----- ADDITIONAL IMPACTS ON
STREAM BUFFER AREAS
ISTING IMPACTED STREAM
BUFFER AREAS
STORMWATER LINE AND DIRECTION
- - - - - OF FLOW
EXISTING TREELINE
TREES IMPACTED BY GRADING
DRAINAGE AREA TO DETEN71ON BASIN
DRAINAGE AREA TO DETENTION
BIO-FILTERAREA
t CD
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STORMWATER DETENTION PLAN (2 YEAR)
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DRAINAGE AREA
DESCRIPTION
DEVELOPMENT
AREA (ac)
PRE4)EVELOPMENT"C*
VALUE
TIME OF
CONCENTRAMON (min.)
PRE-DEVELOPMENT
FLOW (efs)
POST-DEVELOPMENT
AREA (ac)
POST-DEVELOPMENT"C'
VALUE
POST-DEVELOPMENT
ROUTED F-I
SVVM Pond 93
23.87
03D
19
21.48
27.88
0.70
19.30
SWM Pond #2
122.4
0.30
45
110.50
144.50
0.70
96.69
SWM Pond #1
100.9
0.30
45
83.30
153.10
0.70
53.40
Bio4fter#1
9.53
0.30
16
9.15
2.78
0.70
O.OD
Bio-Ifter #2
11.4
0.3D
15
11.07
12.20
0.70
7.84
MG41ter#3
5.8
0.30
14
630
6.8
030
6.20
Bb4fter #4
3.4
0.30
a
4.60
5.6
0.70
4.4D
BkAfter #5
2.9
0.3D
9
335
5.8
0.70
3.30
Bio-ifter#6
5.5
0.30
9
7.10
5.5
0.70
6.50
Bio-Ifter #7
2.7
0.30
8
165
5.5
0.70
3.22
STORMWATER DETENTION PLAN (10 YEAR)
DRAINAGE AREA
DESCRIPTION
PRE-
DEVELOPMENT
AREA (ar)
PRE-DEVELOPMENT"C'
VALUE
TIME OF
OONCENTR0k7ION (min.)
PRE-DEVELOPMENT
FLOW (pfs)
POST-DEVELOPMENT
AREA (ac)
POST-DEVELOPMI
VALUE
POST-DEVELOPMENT
ROUrED FLOW (clis)
SWM Pond #3
23.87
0.30
19
29.36
27.88
0.70
27.28
SV%A Pond #2
122.4
0.30
45
169.6D
144.50
0.70
135.37
SWM Pond #1
100.9
0.30
45
ils.m
153.10
0.70
66.03
Bic4iter#1
9.53
0.30
16
12.58
2.78
0.50
0.00
Bio-ilter #2
11.4
0.30
15
14.70
12.20
0.70
14.20
Bio4fter #3
5.8
0.30
14
815
5.8
0.70
8-38
Bia4fter#4
3.4
0.30
8
5.90
&6
030
5.66
Bio-liter #5
2.9
0.30
9
4.90
5.8
0.70
4.78
Bio-fifter #6
5.5
0.30
9
9.25
5.5
0.70
8.92
jBio-lifter#7
1 2.7
0.30
8
4.70
1 5.5
0.70
4.31
STORMWATER DETENTION PLAN (100 YEAR)
DRAINAGE AREA
DESCRIPTION
PRE-
DEVELOPMENT
AREA (ac)
PRE-DEVELOPMENT"C"
VALUE
TIME OF
OONCENTRAnON (min.)
PRE-DEVELOPMENT
FLOW (pfs)
POST-DEVELOPMENT
AREA (ac)
POST-DEVELOPMENTC'
VALUE
POST-DEVELOPMENT
ROUTED FLOW
SVVM Pond #3
23.87
0.30
19
42.54
27.88
0.70
49.71
SWM Pond #2
122.4
0.30
45
255.40
144.50
0.70
217,56
SWM Pond #1
100.9
0.30
45
303.20
153.10
0.m
110.10
Bio-Ifter#1
9.53
0.30
16
18.24
2.78
0.50
1.04
Bio-fifter#2
11.4
0.30
is
21.40
12.20
0.70
20.80
Bio-lifter#3
5.8
0.30
14
11.50
5.8
0.70
10.95
Blo-fifter#4
3.4
0.30
8
7.80
5.6
0.m
7.45
ffio-fifter#5
2.9
0.30
9
6.40
5.8
0.70
6.35
Bio-lilter#6
5.5
0.30
9
12.10
5.5
0.70
11.98
jBio-11ter#7
1 2.7
0.30
8
6.20 1
5.6
0.70
6.11
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UPPER BALLARD FIELD POND #1 - STORMWATER MANAGEMENT ANALYSIS
ULTIMATE CONTRIBUTING IMPERVIOUS AREAS TO EXISTING M„
RETENTION BASIN II ON UPPER BALLARD FIELD 70P OF DAW ° °" ° \� °-i
PRE - DEVELOPMENT IMPERVIOUSNESS:
EXIST. AREA
100.9 ac.
EXIST. Cw
0.30
PROPOSED AREA
55.1 ac.
EXISTING Cw
030
IMPERVIOUS AREA:
(156.0 *0.30) = 46.8 ac.
POST -- DEVELOPMENT IMPERVIOUSNESS
EXIST. AREA
100.9 ac.
EXIST. C
0.30
PROPOSED AREA
55.1 ac.
PROPOSED C
0.80
IMPERVIOUS AREA: (100.9 *0.30) +(55.1 *0.80) = 84.44 ac-
SUMMARY--
REMOVAL REQUIRED. 589
REMOVAL PROVIDED: RETENT /ON BASIN /I = 5OX (REMAINDER OF
REMOVAL RATE ACHIEVED IMTH CONTRIBUTION TO PRO -RATA SHARE)
WA TER QUALITY VOLUME REQUIRED: (5,660 Cy * 4) = 22,640 cy
WATER QUALITY VOLUME PROVIDED:
POND AREA ® 672.6 = 163,786 SQ FT
POND AREA ® 668 = 136,192 SO FT
(((163,786 + 136,192)12) *4.6)127 = 25,554 CY
25,554 CY > 22,640 CY
679.00
far Water Surface - EL. = VIV. UY
20' - Crest of D
-"Clay Liner to be applied to the entire face of dam
Ibis liner shat( consist of 2' CH (Cloy) moterid
with Liquid LJmIt > 50, Plasticity > 25 &
Permeability = 7 x 10 -6 cm /s ar tower
Clay liner shall be benched and compacted
in accordance with VDOT Specifications.
6' of Topsoif sholl be applied over the
Goy liner and seeded.
Type_ Master Network Summary
Page 1.01
Name.... Watershed
MASTER DESIGN STORM SUMMARY
Default Network Design Storm Fie. 10
Albemarle Cam
Rainfall
Return Event Type iDF ID
Dev 2 - - -- 1 -D-F Curve 2 Yr
Dev, 10 I -D -F Curve 10 Yr
Devi 00 I -D -F Curve 100 Yr
MASTER NETWORK SUMMARY
Modified Rational Method Network
(*Node- Outfoll; +Node- Diversion;)
(Trun- HYG Truncation: Blank -None; L =Left;
R-Rt; LR- Left&Rt)
Max
Return HYG Vol
Qpeak
Qpeak
Max WSEL Pond Storage
Node ID Type Event ac -ft Trun
hrs
cfs
ft ac-ft
EX AREA TO POND AREA 2 5.163
.7500
83.29
EX AREA TO POND AREA 10 7.171
.7500
115.69
EX AREA TO POND AREA 100 12907
.7500
208.23
*EX OUTFALL JCT 2 5.280
1.3100
20.11
*EX OUTFALL JCT 10 7.625
1.2900
32.35
*EX OUTFALL JCT 100 14.234
1.2400
71.17
EXISTING PONDIN POND 2 6.165
.7500
83.29
EXISTING PONDIN POND 10 8.534
7500
115.69
EXISTING PONDIN POND 100 15.180
.7500
208.23
EXISTING PONDOUT POND 2 5.280
1.3100
20.11
673685 5.076
EXISTING PONDOUT POND 10 7.625
1.2900
3235
674.23 6.728
EXISTING PONDOUT POND 100 14.234
1.2400
71.17
675.18 11.083
NEW AREA TO POND AREA 2 1.002
2273
53.35
NEW AREA TO POND AREA 10 1.363
.2373
66.03
NEW AREA TO POND AREA 100 2272
.2373
110.06
Type.... Mod. Rational Graph Page 3.04
Name.... EX AREA TO POND Tog: Dev100 Event: 100 yr
Storm... 100 Yr Tag: Dev100
MODIFIED RA71ONAL METHOD
- - -- Graphical Summary for Maximum Required Storage - - --
Method
Q = CiA * Units Conversion; Where Conversion = 43560 / (12 * 3600)
# # # # # #i #111#1 #tt # # #t ## iii # « ###t #t #iiiiiriiiiir ► # #i # #ii
* RETURN FREQUENCY 100 yr { Allowable Outflow: 206.46 cfe
'C' Adjustment: 1.000 Required Storage: .089 ac -ft
* STORM DURATI Tc for Max.Storage
*------------------------------------------- ----- rt-------------- - - - - -*
* Peak Inflow: 208.23 cfe
* .HYG F1 9: Dev100
ssss##s s#s#sss#s# ss ss ssss s#ss#s sss* ssssssss#sssssssss##ss#s *ssssss
Q {
(
{ Tc= .7500 hrs
{ I - 4.5000 in/hr Area = 131.120 acres
• .• Q = 20&23 cis Weighted C = .350
Adjusted C = .350
{
{ Required Storage
{ .----- - - - - -- .089 ac -ft
I •O O O Q = 206.46 cfe
o {. (Allow.Outflow)
o o NOT TO SCALE
{ O
I----------------------- {------------------------
.7564 hrs T
EXISTING POND FTIR DETAIL
(NOT TO SCALE)
- Edge of Shoulder to C/L
675.0
L7.
b
EXISTING POND CROSS ,SUCTION
(NOT TO SCALE)
Type.... Mod. Rational Graph Page 3.02
Name.... EX AREA TO POND Tag: Dev 2 Event: 2 yr
Storm... 2 Yr Tag: Dev, 2
MODIFIED RATIONAL METHOD
- - -- Graphical Summary for Maximum Required Storage - - --
Method 1
Q = CIA * Units Conversion; Where Conversion = 43560 / (12 * 3600)
##st# ### # ##s #s##s#« *###sss# #s ####mss# # ####*#+#s###s ###s #s#*s
• RETURN FREQUENCY 2 yr ( Allowable Outflow: 8258 cfs
• 'C' Adjustment: 1.000 { Required Storage: .042 ac-ft
* STORM DURATION = Tc for Max.Storage
- - - -- ---------------------- - - - - -* -------------- - - - - -
• Peak Inflow: 83.29 *
• .HYG File: Dev 2 #
Q{
Tc- .7500 hre
1 = 1.8000 in/hr Area = 131.120 acres
{ Q s 83.29 cfs Weighted C - .350
{ .. Adjusted C = .350
{ - Required Storage
-
{ . - -- - - .042 ac-ft
.• •0a o Q = 82.58 cfe
{ o {. (Allow.Outflow)
0 0 (•. NOT TO SCALE
o
'---------------------------------------- - - - - --
.7564 hrs
T
Type.... Mod. Rational Graph Page 3.06
Name.... NEW AREA TO POND Tog: Dev 2 Event: 2 yr
Storm... 2 Yr Tog: Dev, 2
MODIFIED RATIONAL METHOD
- - -- Graphical Summary for Maximum Required Storage - - --
Method I
Q = CiA * Units Conversion; Where Conversion - 43560 / (12 * 3600)
tt# t #t # «it#t #ttirtt##tttirtttt #ttt# #1#111 #1111 #ti#tttirti #t#
• RETURN FREQUENCY: 2 yr { Allowable Outflow: 50.02 efs
• 'C' Adjustment: 1.000 ( Required Storage: .063 ac-ft
* STORM DURATION - Te for Max.Storage
----------------------- ------------------------------------------
* Peak Inflow. 53.36 efs
* .HYG File. Dev 2
ss t###ssss#s ssss ssss as#ss sssss#s sssssssssss#sssssssss*ssss#sss#
Q
Tc= .2273 hrs
I = 3.6360 in/hr Area = 1 &900 acres
{ Q = 53.36 cfe Weighted C = .770
{ .. Adjusted C - .770
{
{ Required Storage
{ - - - -- - -- .063 ac -ft
{ •000 Q - 50.02 cfs
o (. (Allow.Outflow)
{ •• O {
{ o { NOT TO SCALE
O
'° --------------------- 1------------------ - - - - --
.2415 hrs T
STD. CG -6
2 G UTTER RB &
-•i 25 F----
GROUND
POINT OF
FINISHED GRADE
EL - 679.67
OLD TRAIL DRIYB
a"
2
2.5 "-
Type.... To Calcs Pogo 201
Name.... EX AREA TO POND Tag: POST
TIME OF CONCENTRATION• CALCULATOR ..............................
Segment 11: Tc: User Defined
Segment #1 Time: .7500 hre
Total Ta .7500 hrs
Type.... Tc Calcs Page Z03
Name.... NEW AREA TO POND Tag: POST
::...:......... ............................... ...
TIME OF CONCENTRATION CALCULATOR
Segment #1: Tc: User Defined
----------------------- - - - - -- Segment - Time: _ - -_-- hrs --------------------
2
ssssssssssssssssassssssss
Total Ta .2273 hre
_ ssssssssssssaasssassssss _
Type.... Mod. Rational Graph Page 3.03
Name.... EX AREA TO POND Tag: Dev 10 Event: 10 yr
Storm... 10 Yr Tag: Dev 10
MODIFIED RATIONAL METHOD
- - -- Graphical Summary for Maximum Required Storage - - --
Method i
Q - CiA * Units Conversion; Where Conversion - 43560 / (12 * 3600)
• RETURN FREQUENCY: 10 yr { Allowable Outflow: 114.70 cfs
• 'C' Adjustment: 1.000 { Required Storage. .058 oc -ft
* STORM DURATION - To for Max.Storage
* --- - ------------------------ - - - - -- * -------------- - - - - -
Peck Inflow: *
* .HYG File: Dev 10
Q
{ Tc- .7500 hrs
{ 1 = 2.5000 in/hr Area = 131.120 acres
• .• Q - 115.69 efs Weighted C = .350
Adjusted C = .350
{
Required Storage
{ - - - - - -- - - .058 ac -ft
000 Q- 114.70 efs
• . • 0 1. (Allow.Outflow)
0
•, o i .• NOT TO SCALE
O sssassssssss
i O --1 -
------------------
.7564 hre T
Type.... Mod. Rational Graph Page 3.07
Name.... NEW AREA TO POND Tag: Dev, 10 Event: 10 yr
Storm... 10 Yr Tog: Dev 10
MODIFIED RATIONAL METHOD
- - -- Graphical Summary for Maximum Required Storage - - --
Method 1
Q = CIA * Units Conversion: Where Conversion = 43560 / (12 * 3600)
# ssssssss ##s##ssss#####ssi###s##Ri#�uk# W t# #s##ss###s#####s###
* RETURN FREQUENCY 10 yr { Allowable Outflow: 65.82 cfs
* 'C' Adjustment 1.000 { Required Storage: .066 ac -ft
#------------------------------------------ .-- ------------------- - - - - -#
* Peak Inflow: 66.03 cfe
* .HYG File: Dev, 10
Q ( Td - .2500 hro { Return Freq: 10 yr
- - - - - -- Approx. Duration for Max. Storage ------ / C adlfactor.1.000
Tc-- .2273 hre {
I = 4.7360 In/hr { Area = 18.900 acres
{ Q = 69.50 efs { Weighted C - .770
Adjusted C = .770
{ { . Required Storage { {
-- .066 ac -ft { Td= .2500 hre
j { {• { 1 = 4.5000 in /hr
{
x x x x x x xxxxxxxxxx Q= 66.03cfe
{ x { x
o Q - 65.82 cfs
{ . • x o {x (Allow.Outflow)
{ x 0 {
{ x o NOT TO SCALE { x
{ X O sssssasssass {
O ( X
`-------------------- ---- ----------------- ----------- {------ - - - - --
hrs
Type.... Mod. Rational Graph Page 108
Name.... NEW AREA TO POND Tog: Dev100 Event: 100 yr
Storm... 100 Yr Tag: DwA OO
MODIFIED RATIONAL METHOD
- - -- Graphical Summary for Maximum Required Storage - - --
Method I
Q - CIA * Units Conversion; Where Conversion - 43560 / (12 * 3600)
* RETURN FREQUENCY: 100 yr { Allowable Outflow: 107.94 efs
* 'C' Adjustment- 1.000 ( Required Storage: .145 ac-ft
* : --- efs
------------------------ - - - - -- * -------------- - - - - -
Peak Inflow *
* .HYG FIle: Dev100
ifs ## its# ii#* t## i# s## s# s## s## #s#sssissii # #ssssssss #tt#asss##
Q { Td - .2500 hrs { Return Freq: 100 yr
- - - - -- Approx. Duration for Max. Storage ------ / C adJ factor:1.000
Tc= .2273 hrs {
I - 7.7720 in/hr { Area - 18.900 acres
{ Q = 114.05 cfe ( Weighted C s .770
. {. { Adjusted C - .770
.. { • . Required Storage { {
{ -- .145 ac-ft j Td= .2500 hre
{ ( { { I = 7.5000 in/hr
{ xxxxxxx{xxxxxxxxxxx Q =I10.06cfe
{ {
x x a Q = 107.94 cfs
x o {x (Allow.Outflow)
(
X O {
x O NOT TO SCALE { x
{.x o ____________ {
10 -- { - X
'------------------------------------------------- {------
.2544 hra - - - - --
^ TH
O SCOTT R. C UM=
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POND J2 SUMMARY
MASTER NETWORK SUMMARY
Modified Rational Method Network
(*Node = Outfall; +Node = Diversion;)
(Trun= HYG Truncation: Blank--None; L =Left; R =Rt, LR =Left&Rt)
POND CALCULA TONS SUMMA RY.•
i
Max
Return HYG Vol Qpeak Qpeak Max WSEL Pond Storage
Node ID
Type Event ac -ft Trun
hrs
cfs ft
ac-ft
*EARTH
JCT 2 .000
.0500
.00
Q100=21 56 CFS
100=
*EARTH
JCT 10 .000
.0500
.00
WIER ELEV. =689.90'
*EARTH
JCT 100 1.303
1.0500
.48
TOP OF DAM= 693.50'
POND
IN POND 2 3.596
.4500
96.69 .
LENGTH OF WIER = 10.00'
POND
IN POND 10 5.035
.4500
135.37
DRAINAGE AREA =144.53 AC.
POND
IN POND 100 10.189
A500
217.56
CW =0.27
POND
OUT POND 2 .000
.0500
.00
689.36 3.596
POND
OUT POND 10 .000
.0500
.00
689.54 5.034
POND
OUT POND 100 1.303
1.0500 .48
690.18 10.181
STORM
AREA 2 3.596
.4500
96.69
SLOPE =3.50%
STORM
AREA 10 5.035
A500
135.37
STORM
AREA 100 10.189
.4500
217.56
Q2 =20.20 CFS
POND CALCULA TONS SUMMA RY.•
i
I MS -19 CALCULA TONS SUMMARY
Q2 =96.69 CFS
CROSS SECTION A:
Q2=20.20 CFS
CROSS SECTION
02 =20.20 CFS
Q10 =135.37 CFS
8
V2=3.96 FPS
2 =3
STA 2 +00:
V2 = 3. .50 FPS
Q100=21 56 CFS
100=
WAYM I ]
KEEWAY .I I�
Q10 =26.94 CFS
_
010 =26.94 CFS
WIER ELEV. =689.90'
JWT DETAIL I
D10 -0.45 FT.
D -0.99 FT.
10
TOP OF DAM= 693.50'
SLOPE= 1.00%
SLOPE =3.35q
LENGTH OF WIER = 10.00'
DRAINAGE AREA =144.53 AC.
CROSS SECTION B:
02 =20.20 CFS
CROSS SECTION
Q2 =20.20 CFS
CW =0.27
V2 =1.63 FPS
STA 3 +00:
V2 =350 FPS
Tc=27 MIN.
E-
Q10 =26.94 CFS
C
=
Q10 = 26.94 CFS
D10 =0.65 FT.
FACH WAY
D10 =0.96 FT.
2 AND 10 YEAR STORMS CONTAINED
..
SLOPE= 1.00%
SLOPE =3.50%
100 YEAR SPILLWAY DISCHARGE = 0.48
CFS
100 YEAR DISCHARGE TIME= 63 MIN.
CROSS SECTION
Q2 =20.20 CFS
CROSS SECTION
Q2 =20.20 CFS
STA 0 +00:
V =2 67 FPS
STA 4 +50:
V =2 44 FPS
TOP OF DAM
ELEV = 693.50'
-1 20' r
2 2
Q10 =26.94 CFS 010 =26.94 CFS
D10 =0.59 FT. D10 --0.67 FT.
SLOPE= 4.0 07 SLOPE= 2.00'
CROSS SECTION 02 -20.20 CFS NOTE. • ALL MS -19 FLOWS WERE
STA 1+00: V2 =2.54 FPS ANAL YSED FOR THE WORSE
Q -26.94 CFS CASE SCENARIO, DRAINAGE
10 - AREA AT STA 4 +50.
D10 -0.38 FT.
SLOPE= 4.00%
TOP OF DAM
ELEV. = 693.50'
1.50'
120' L-120'-
2.w
WEIR DETAIL
• RAD/t!S 10- ELEV
TW. 9LL CQRlVERS
' BARS O 8'
O1V LEIV7ER
2' cm TYP n 2' CLR TYP
av cEH1ER
= 689.90'
WOT CLASS 1 - ELEV=889.9'
RIPRAP L004710N OF
NOR NOWH
< -� - _ s' caaeEM _
DPAI4VA GE AREA TO
C
x
I
cl
El
DRAIINA GE
AREA =
144.53
p
1
GRAPHIC SCALE
Sao 0 150 300 600 1200
IN FEET )
1 inch = 900 ft
5 BARS ® 12"
ON C NTER EACH WA
t�
x - DOWNSTREAM FACE OF
3' ; Tm
COMPACTED SUBGRADE
ON STONE BASE
AS REQUIRED SECTION B -B
NOT TO SCALE
ROAR 0
BARS O 12'
as
2' x 4' KEY
WAIERSTOP
E 'Ir x 1/2'
JaW SEALANT
EINR7RQNENT
KEYWAY CONS7RUCTION JOINT DETAIL
NOT TO SCALE
i
x4 KEY \
REBAR 15
AIRS ® 12' /
O. C.
AWNT SPAaN&
L MAXIMUM 20' -0' C C
2 MAXIMUM 12' 0' FROV CORNER
3 AT CHANGE'S IN WALL HOGHT
4. l7' OWW MIN. FOR ALL REBAR "WS
DETAILS FOR CONCRETE
NOT TO SCALE
0�
. ''� -- - -..`~ °�: ; ,� c� \t ��� �� � ?✓ / mss, � �4
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STA. 1+00
{ \ \
S 9
S -19 f
ON
A / - 9 O
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N
TH
11
SCOTT R. COUJNS�
No. 35791 �
v °ZONAL
i
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'T E
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..
y
NOT . SCALE
DPAI4VA GE AREA TO
C
x
I
cl
El
DRAIINA GE
AREA =
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p
1
GRAPHIC SCALE
Sao 0 150 300 600 1200
IN FEET )
1 inch = 900 ft
5 BARS ® 12"
ON C NTER EACH WA
t�
x - DOWNSTREAM FACE OF
3' ; Tm
COMPACTED SUBGRADE
ON STONE BASE
AS REQUIRED SECTION B -B
NOT TO SCALE
ROAR 0
BARS O 12'
as
2' x 4' KEY
WAIERSTOP
E 'Ir x 1/2'
JaW SEALANT
EINR7RQNENT
KEYWAY CONS7RUCTION JOINT DETAIL
NOT TO SCALE
i
x4 KEY \
REBAR 15
AIRS ® 12' /
O. C.
AWNT SPAaN&
L MAXIMUM 20' -0' C C
2 MAXIMUM 12' 0' FROV CORNER
3 AT CHANGE'S IN WALL HOGHT
4. l7' OWW MIN. FOR ALL REBAR "WS
DETAILS FOR CONCRETE
NOT TO SCALE
0�
. ''� -- - -..`~ °�: ; ,� c� \t ��� �� � ?✓ / mss, � �4
LT
Q
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\ X- SECTTCSN X- SSECTIO
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{ \ \
S 9
S -19 f
ON
A / - 9 O
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i
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N
TH
11
SCOTT R. COUJNS�
No. 35791 �
v °ZONAL
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DATE
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LEVEL
POOL ROUTING SUMMARY (2 Year)
No Infiltration
= 56.49 cfs at .1700
INITIAL CONDITIONS
Peak Outflow
Starting WS Elev =
651.75 ft
Starting Volume =
2.493 ac -ft
Starting Outflow =
.00 cfs
Starting Infiltr. _
.00 cfs
Starting Total Qout=
.00 cfs
Time Increment =
.0100 hrs
INFLOW /OUTFLOW HYDROGRAPH SUMMARY
651.75 ft
Peak Inflow
= 56.49 cfs at .1700
hrs
Peak Outflow
= 19.30 cfs at .2800
hrs
Peak Elevation
= 652.85 ft
.00 cfs
Peak Storage =
3.056 ac -ft
_00 cfs
MASS BALANCE
(ac_ ft)
= .0100 hrs
• Initial Vol =
----- - -_ - --
2.493
= 57.63 - 0
• HYG Vol IN -
.794
.1700 hrs
- Infiltration =
.000
.2700 hrs
- HYG Vol OUT
= 793
Td =10.3
- Retained Vol =
2.494
J
.1667
Unrouted Vol =
- -- -_
-.000 ac -ft (.001% of Inflow
Volume)
2.493
LEVEL POOL ROUTING SUMMARY
(10 Year)
No Infiltration
INITIAL CONDITIONS
Starting WS Elev =
651.75 ft
100 Year
Starting Volume
= 2.493 ac -ft
a= 244.82 Appendix 5A for
Starting Outflow =
.00 cfs
b= 20.81 Albemarle County
Starting Infiltr. _
.00 cfs
3.333000
Starting Total Qout=
_00 cfs
10 Year
Time Increment
= .0100 hrs
= Qpre - Qbypassed
INFLOW /OUTFLOW HYDROGRAPH SUMMARY
= 57.63 - 0
Peak Inflow =
74.40 cfs at
.1700 hrs
Peak Outflow =
27.28 cfs at
.2700 hrs
Peak Elevation =
653.14 ft
Td =10.3
Peak Storage =
3.211 ac -ft
.1667
MASS BALANCE (ac -ft)
.00 cfs
• Initial Vol =
2.493
.124
• HYG Vol IN -
1.046
1.045
- Infiltration =
.000
2.141
- HYG Vol OUT =
1.045
1.4072
- Retained Vol =
2.494
1.703
Unrouted Vol =
-.000 ac -ft (.002% of
Inflow Volume)
2.616
LEVEL POOL ROUTING SUMMARY
(100 Year)
No Infiltration
2
.793
INITIAL CONDITIONS
19.30
1.9123
Starting WS Elev =
651.75 ft
Starting Volume
- 2.493 ac -ft
1.045
Starting Outflow =
.00 cfs
Starting Infiltr. _
.00 cfs
Starting Total Qout=
.00 cfs
1.703
Time Increment
= .0100 hrs
INFLOW /OUTFLOW HYDROGRAPH SUMMARY
_
Peak Inflow =
---
121.24 cfs at
-� -_ --
.1700 hrs
___--
Peak Outflow
49.71_ cfs
e-
2700 hrs
----
Peak Elevation =
-_ -at -_
653.82 ft
RETENTION
Peak Storage �_T -
- - -- 3.597 ac_ft---- -
- - - --
MASS BALANCE (ac -ft)
.1700
74.40
+ Initial Vol =
2.493
RETENTION
+ HYG Vol IN =
1.704
100
- Infiltration =
.000
121.24
- HYG Vol OUT =
1.703
RETENTION
- Retained Vol =
2.494
2
Unrouted Vol =
-.000 ac -ft (.000% of
Inflow Volume)
Wet Pond
3.056
RETENTION
Source: Virginia Stormwater Management
Handbook, Volume II
10
Equation 5 -5 of Chapter 5, page 21
Td= I f2 x CA x a x (b- Tc /4)1 11x2 - b
qo
C = 0.50
A = 27.88
2 Year
10 Year
100 Year
a= 106.02
a= 161.6
a= 244.82 Appendix 5A for
b= 15.51
b= 18.73
b= 20.81 Albemarle County
Tc = 10
Weir Coeff. =
3.333000
qo = Maximum Allowable Peak Outflow To Meet Minimum MS -19 Standards
2 Year
10 Year
100 Year
= Qpre - Qbypassed
= Qpre - Qbypassed
= Qpre - Qbypassed
= 57.63 - 0
= 75.90 - 0
= 123.69 - 0
= 57.63
= 75.90
= 123.69
2 Year (min.)
10 Year (min.)
100 Year (min.)
Td =10.3
Td =12.3
Td =11.0
MASTER NETWORK SUMMARY
Modified Rational Method Network
( *Node= Outfoll; +Node = Diversion; )
(Trun= HYG Truncation: Blank =None; L =Left; R =Rt; LR= Left &Rt)
*************** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * **
OUTLET CONNECTIVITY
- - -> Forward Flow Only (UpStream to DnStream)
< - -- Reverse Flow Only (DnStream to UpStream)
< - - -> Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
Weir - Rectangular WR - - -> TW 651.750 656.000
TW SETUP, DS Channel
OUTLET STRUCTURE INPUT DATA
Structure ID =
WR
Structure Type =
Weir - Rectangular
# of Openings -
1
Crest Elev. =
651.75 ft
Max
5.00 ft
Weir Coeff. =
3.333000
Return
HYG Vol
Qpeak
Qpeak
Max WSEL
Pond Storage
Node ID -
- -- -Type
Event
ac -ft Trun
hrs
- cfs -
--
ac -ft
DRAINAGE
.01 ft
AREA
2
.794
.1667
57.63
.00 cfs
Max. Q tolerance =
DRAINAGE
.124
AREA
10
1.045
.1667
75.90
2.141
651.75 - - - --
DRAINAGE
1.4072
AREA
100
1.703
.1667
123.69
.123
2.616
*OUTFALL
.5893
JCT
2
.793
.2800
19.30
1.9123
1.275
*OUTFALL
JCT
10
1.045
.2700
27.28
*OUTFALL
JCT
100
1.703
.2700
49.71
RETENTION
IN
POND
2
.794
.1700
56.49
RETENTION
IN
POND
10
1.046
.1700
74.40
RETENTION
IN
POND
100
1.704
.1700
121.24
RETENTION
OUT
POND
2
.793
2800
19.30
652.85
3.056
RETENTION
OUT
POND
10
1.045
.2700
27.28
653.14
3.211
RETENTION
OUT
POND
100
1.703
.2700
49.71
653.82
3.597
*************** * * * * * * * * * * * * * * * * * * * * * * * * * * * * * **
OUTLET CONNECTIVITY
- - -> Forward Flow Only (UpStream to DnStream)
< - -- Reverse Flow Only (DnStream to UpStream)
< - - -> Forward and Reverse Both Allowed
Structure No. Outfall E1, ft E2, ft
Weir - Rectangular WR - - -> TW 651.750 656.000
TW SETUP, DS Channel
OUTLET STRUCTURE INPUT DATA
Structure ID =
WR
Structure Type =
Weir - Rectangular
# of Openings -
1
Crest Elev. =
651.75 ft
Weir Length =
5.00 ft
Weir Coeff. =
3.333000
Weir TW effects
(Use adjustment equation)
Structure ID =
TW
Structure Type =
TW SETUP, DS Channel
FREE OUTFALL CONDITIONS
SPECIFIED
CONVERGENCE TOLERANCES...
.326
Maximum Iterations=
40
Min. TW tolerance =
.01 ft
Max. TW tolerance =
.01 ft
Min. HW tolerance =
.01 ft
Max. HW tolerance =
.01 ft
Min. Q tolerance =
.00 cfs
Max. Q tolerance =
.00 cfs
(TOP OF DAM= 656.00) 100 YEAR
10 YEAR W. S.E= W. S E. = 653.82
653.14'
2 YEAR W.SE= -------- .- .- -� - - -- --
652.85'
_ VDOT STD. EC -1 CL. ll
5' PRINCIPLE SPILLWAY RIP -RAP LINED EMERGENCY
ELEVA T70N= 651.75 SPILLWAY WITH GEO- TEX77LE
UNDERLA YMENT
PRINCIPLE SPILLWAY
TIME OF CONCENTRATION CALCULATOR
Segment #1: Tc: User Defined
Segment #1 Time: .1667 hrs
-----------------------------------------------------------
Total Tc: .1667 hrs
7
TOP OF FOREBA Y---�
DAM KID TH =1.5'
(ELEV. = 650.50
MEAN W.S.E.=
651.75
RATIONAL C COEFFICIENT DATA
Area C x Area
Soil /Surface Description C acres acres
Post - Development Drainage to Retent .5000 27.880 13.940
WEIGHTED C & TOTAL AREA - - -> .5000 27.880 13.940
TOP OF
DAM ND 7H OF
ELEV.= TOP OF DAM = 8'
100 YEAR 656.00
W. S E. = 653.82 PRINICPLE SPILL WAY
10 YEAR ELEV. = 651.75
W. S E. = 653.14 6" MIN. 2.18' OF FREEBOARD
2 YEAR TOPSOIL 5.75' DECORATIVE ROCK WEIR OVER
CONCRETE OUTFALL CHANN.
W. S E. =652.85 WD TH- 5' DEPTH OF CONC.E 0.5'
4.25'
4.25' OF
PONDING
�-' DEP H A I
BOTTOM OF�
FOREBAY =643.00'
TOP OF FOREBA Y
ROCK WEIR
ELEV. = 650.25
Elevation Planimeter
Area Al +A2 +sgr(Al *A2)
Volume Volume Sum
(ft) (sq.in)
(acres)
(acres) (ac
-ft) (ac -ft)
643.00 - - - --
.0939
.0000
.000
.000
644.00 - - - --
.1263
.3290
.110
.110
646.00 - - - --
.2026
.4888
.326
.436
648.00 - - - --
.2945
.7414
.494
.930
650.00 - - - --
.4020
1.0407
.694
1.624
650.25 - - - --
.5994
1.4923
.124
1.748
651.00 - - - --
.4526
1.5729
.393
2.141
651.75 - - - --
.4857
1.4072
.352
2.493
652.00 - - - --
.4969
1.4738
.123
2.616
654.00 - - - --
.5893
1.6272
1.085
3.701
656.00 - - - --
.6868
1.9123
1.275
4.975
POND VOLUME EQUATIONS
* Incremental volume computed by the Conic Method for Reservoir Volumes.
Volume = (1/3) * (EL2 -EL1) * (Areal + Area2 + sq. rt. (Areal *Area 2))
where: EL1, EL2 = Lower and upper elevations of the increment
Areal,Area2 = Areas computed for EL1, EL2, respectively
Volume = Incremental volume between EL1 and EL2
2.18' OF
FREEBOARD
4.50'
FOREBA Y TOP OF DAM
WIDTH= 3' AT AN
ELEVA 770N= 650.50
(TOP OF DAM= 656.00)
10 YEAR W. S E=
653.14' 100 YEAR
10 YEAR W. S.E= W. S. E. = 653.82
652.85'
- - - - - .- . -7 ------ - - .
- .
BOTTOM OFD 1' SCARIFIED
POND =643.00' KEY FOR SOIL
COHESION
W ENERGY DI SSI PATOR
VOOT STD. EC -1 CLASS II DRY
L =42', W =5') D =2'
W/ GEO- FABRIC UNDERLAYMENT
{ CONSTRUCTION
GRADE FILL
(COMPACTED TO 95 %)
CLAY /IMPERVIOUS CORE &
CUTOFF TRENCHED DAM KEYED
INTO THE EXISTING GROUND
PROVIDED FOREBAY VOLUME= 26,454 CF PROVIDED WATER QUALITY VOLUME= 108,592 CF
REQUIRED FOREBAY VOLUME FOR THE REQUIRED WATER QUALITY VOLUME FOR THE
ULTIMATE DEVELOPMENT= 12,651 CF ULTIMATE DEVELOPMENT= 101,204 CF
t.
VDOT STD. EC -1 CL. 11
FOREBAY SPILLWAY RIP -RAP LINED EMERGENCY
ELEVATION 650.25 SPILLWAY WITH GEO- TEXTILE
UNDERLA YMENT
FOREBAYSPILLWAY
NOTE
THE ULTIMATE DEVELOPMENT SHALL BE DESIGNED FOR A 'C' VALUE OF 0.50 DRAINING TO THE PROPOSED DETENTION BASIN. A 'C' VALUE OF 0.50
ON A DRAINAGE AREA OF 27.88ac WILL PRODUCE ROUGHLY 13.94ac. OF IMPERVIOUS AREA. THIS IMPERVIOUS AREA INCLUDES THE MASTER PLAN
DEVELOPMENT OF THE BLOCKS WITHIN THE DRAIANGE AREA AS SHOWN ON THE STORMWATER MANAGEMENT SHEET PLAN SHEET 1. THIS RETENTION
POND SHALL BE DESIGNED TO TREAT 50q OF THE IMPERVIOUS AREA. THEREFORE, THE WATER QUALITY VOLUME OF THE POND SHALL BE 101,204cf.
THE WATER QUALITY VOLUME PROVIDED IS 103,364cf.
0.25" OF RUNOFF PER 1 ACRE OF IMPERVIOUS DRAINAGE AREA GENERATES A WATER QUALITY VOLUME OF 12,651 cf FOR 13.94ac OF IMPERVIOUS
AREA FOR THE FOREBAY. THE FOREBAY VOLUME CONTAINS 26,454cf.
THE SOIL AROUND THE SPILLWAY IS TO BE VERIFIED THAT IT IS COMPACTED AT A 957. COMPACTION WITH AN IMPERVIOUS CORE. THE SPILLWAY AND
DOWNSTREAM OF THE SPILLWAY WILL BE LINED WITH VDOT STD. EC -1 CLASS lI RIPRAP. THE VEGETATIVE COVER ON THE DAMS AND AROUND THE
POND BANKS WILL BE SOD- FORMING GRASS.
THE DESIGN PEAK RELEASE RATE FROM THE POND EQUALS THE 100 YEAR DESIGN PEAK RATE OF INFLOW TO THE SPILLWAY, WHICH IS 49.71 cfs. A
PERMISSIBLE VELOCITY OF 5.0 FPS WAS UTILIZED DUE TO AN EROSION RESISTANT LINING AND SOD - FORMING GRASS IMMEDIATELY DOWNSTREAM OF
THE SPILLWAY.
HYDRAULIC DIMENSIONS AND COEFFICIENTS FOR THE WEIR /SPILLWAY ARE 5' WIDE AND 4.25' DEEP FOR THE PRINCIPAL SPILLWAY. THE WEIR
COEFFICIENT FOR EACH OF THE SPILLWAYS IS 3.333.
WET POND
(NOT TO SCALE
WATER QUALITY VOLUME:
ti MIN. REQ D. VOLUME= 101,204 C.F.
PROPOSED VOLUME = 103,364 C.F. ~
X01
SCOTT R. COLLINSZ"
No. 35791
ZONAL 1
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Biofilter
Source: Virginia Stormwater Management Handbook, Volume 11
MASTER NETWORK SUMMARY
0
Modified Rational Method Network
0% U)
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(*Node=Outfall; +Node=Diversion;)
C)
I E':
10 E
Equation 5-5 of Chapter 5, page 21
(Trun= HYG Truncation: Blank=None; L=Left;
R=Rt; LR=Left&Rt)
--- --- --- - BIOFILTER MIX
FROM "LUCK STONE"
11 UJ
OR EQUIVALENT
C-4
<
BIOFILTER CHARACTERISTICS
Max
Ju>
Td=
12 x CA x a x (b-Tc/4)]
"2 - b
Return HYG Vol
Qpeak
Opeak
Max WSEL
Pond Storage
Elevation
Planimeter
Area Al+A2+sqr(A1 *A2) Volume Volume Sum
Z; i1j, Wa 5 FIRM zgff
N F
NO. 57 STONE COMPACTED
Node ID
Type Event oc-ft Trun
hrs
cfs
ft
ac-ft
(ft)
(sq.in)
(acres) (acres) (ac-ft) (ac -ft)
qo
- - - - - - - -
- - - - - - - - - - - - - - - - - - -
- - -- -Type - - - -
- - - - - -
- - - - -
- - - - - -
- - - - - - -
- - - - - - -
- - - - - -
- - -
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
BIOFILTER
IN POND 2 .063
.1000
5.64
•
631.00
-----
.0998 .0000 .000 .000
BIOFILTER
IN POND 10 .082
.1000
7.33
632.00
.1182 .3266 .109 1109
C = 0.50
BIOFILTER
IN POND 100 .132
.1000
11.89
633.00
-----
.1380 .3838 .128 .237
NTS
634.00
-----
.1546 .4386 .146 .383
A = 2.78
BIOFILTER
OUT POND 2 .000
.0500
.00
631.60
.063
BIOFILTER
OUT POND 10 .000
.0500
.00
631.76
.081
2 Year 10 Year 100 Year
BIOFILTER
OUT POND 100 .022
.2500
1.04
632.16
.128
POND VOLUME EQUATIONS
a= 106.02 a= 161.6 a= 244.82
Appendix 5A for
DRAINAGE
AREA 2 .064
.1165
6.58
FREEBOARD
Incremental volume computed by the Conic Method for Reservoir Volumes.
b= 15.51 b-- 18.73 b-- 20.81
Albemarle County
DRAINAGE
AREA 10 .083
.1165
8.53
DRAINAGE
AREA 100 .135
.1165
13.85
Volume = (1/3) * (EL2-EL1) * (Areal + Areo2 + sq.rt.(Areo1 *Area2))
Tc = 7
*OUITFALL
JCT 2 .000
.0500
.00
where:
ELI, EL2
= Lower and upper elevations of the increment
*OUITFALL
JCT 10 .000
.0500
.00
Areal,Area2
= Areas computed for EL1, EL2, respectively
*OUITFALL
JCT 100 .022
.2500
1.04
MA
Volume
= Incremental volume between ELl and EL2
q,= Maximum Allowable Peak Outflow To Meet Minimum MS-19 Standards
2 Year 10 Year 100 Year
= Qpre - Qby passed = Qpre - Qby passed = Qpre - Qby passed
= 6.58 - 0 = 8.53 - 0 = 13.85 - 0 OUTLET CONNECTIVITY
= 6.58 = 8.53 = 13.85
2 Year (min.) 10 Year (min.) 100 Year (min.) > Forward Flow Only (UpStream to DnStream) < - -- Reverse now Only (DnStream to UpStream)
Td = 9.3 Td = 11.2 Td = 9.8 < - - -> Forward and Reverse Both Allowed
Structure No. Outfall El, ft E2, ft
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
LEVEL POOL ROUTING SUMMARY (2 Year) LEVEL POOL ROUTING SUMMARY (100 Year) Weir-Rectangular WR - - -> TW 632.000 634.000 TW SETUP, DS Channel
Infiltration - .1250 in/hr Infiltration = .1250 in/hr
INITIAL CONDITIONS INITIAL CONDITIONS Structure ID Type = WR
---------------------------------- ---------------------------------- -
Starting WS Elev 631.00 ft Starting WS Elev 631.00 ft ----- Structure ---------Weir- Rectangular
----------
Starting Volume = .000 ac-ft Starting Volume = .000 ac-ft RATIONAL C COEFFICIENT DATA # of Openings 1
Starting Outflow .00 cfs Starting Outflow .00 cfs
Starting Infiltr. .00 cfs Starting Infiltr. .00 cfs Area C x Area Crest Elev. 632.00 ft
Starting Total Qout- .00 cfs Starting Total Qout= .00 cfs Soil/Surface Description C acres acres Weir Length 5.00 ft
Time Increment = .0500 hrs Time Increment = .0500 hrs -------------------------- - - - - -- - - - - - - - - - - - - - - - - - - Weir Coeff. = 3.333000
Post-Development Drainage to Biofllter .5000 2.780 1.390 Weir TW effects (Use adjustment equation)
INFLOW/OUTFLOW HYDROGRAPH SUMMARY INFLOW/OUTFLOW HYDROGRAPH SUMMARY
= -------- WEIGHTED C & TOTAL AREA .5000 2.780 1.390 Structure ID = TW
Peak Inflow = 5.64 cfs at .1000 hrs Peak Inflow = 11.89 cfs at .1000 hrs Structure Type --= -TW SETUP, DS Channel
--- -----------------
Peak Outflow = .00 cfs at .0500 hrs; Peak Outflow = 1.04 cfs at .2500 hrs FREE OUTFALL CONDITIONS SPECIFIED
Peak Infiltration = .01 cfs at .2500 hrs Peak Infiltration .02 cfs at .2500 hrs
------------------------------------ -------------------------------------
Peak Elevation = 631.60 ft Peak Elevation CONVERGENCE TOLERANCES... 632.16 ft Maximum Iterations= 40
Peak Storage .063 ac-ft Peak Storage .128 ac-ft Min. TW tolerance .01 ft
Max. TW tolerance .01 ft
Min. HW tolerance = .01 ft
.
MASS BALANCE (ac-ft) MASS BALANCE (ac-ft) Max. HW tolerance 01 ft Min. Q tolerance .00 cfs
-------------------------- -------------------------- .
• Initial Vol .000 + Initial Vol .000 Max. Q tolerance 00 cfs
• HYG Vol IN = .063 + HYG Vol IN = .132
- Infiltration = .062 - Infiltration = .110
- HYG Vol OUT = .000 - HYG Vol OUT = .022
- Retained Vol .001 - Retained Vol = .001
---------- ----------
Unrouted Vol = -.000 ac-ft (.006% of Inflow Volume) Unrouted Vol = -.000 ac-ft (.003% of Inflow Volume)
LEVEL POOL ROUTING SUMMARY (10 Year)
Infiltration = .1250 in/hr TOP OF
DAM TH OF
--
INITIAL CONDITIONS ELEV= TOP OF DAM 8'
-------------------------------- 6J4.00
Starting WS Elev = 631.00 ft 100 YEAR CLEAN-OUT W/
Starting Volume = .000 ac-ft WS.E.=6J2.16 J" OF PEA GRAVEL WA TER TIGH T WEIR ELEV.= 6J2.00
Starting Outflow .00 cfs SHALL BE PLACED CAP (TYP.)
Starting Infiltr. .00 cfs BETWEEN 77-IE FILTER
Starting Total Qout= .00 cfs 10 YEAR MEDIA AND 774E 2' DECORA T1 VE ROCK WEIR OVER
Time Increment .0500 hrs G 0
WS.E.=631.76 UNDERDRAIN MEDIA C/0
W. CONCRETE OUTFALL CHANNEL.
�D
E
'632.00' WIDTH=5'. DEPTH OF CONC. =0.5'
0 0
P
INFLOW/OUTFLOW HYDROGRAPH SUMMARY 2 YEAR (Typ.) ry
OPE
-------- W.S.E.=6J1.60 _7
Peak Inflow 7.33 cfs at .1000 hrs ENERGY DISSIPATOR
Peak Outflow .00 cfs at .0500 hrs 1. COO' 1. 00' OF
+ VDOT STD. EC -1 CLASS 11 DRY RIPRAP
ELEV. * 1_ PONDING
Peak Infiltration .01 cfs at .2500 hrs + + I + +1+ + + +
L=8 W=5, D=2
A.,
C
----------------------------------- -- 6JI.00'
Peak Elevation 631.76 ft 2.5' DEPTH
Peak Storage 081 ac-ft
M W1 GEO-FABRIC UNDERLAYMENT
.
------------ A41N.
1.5'
F.
MASS BALANCE (ac -ft) -------------------------- MIN.
ROCK WEIR
• Initial Vol .000 ELEV. =632.00 10.0' MIN.
• HYG Vol IN .082 BOTTOM OF B /OFIL7FR 60 LF @ 1.009
Infiltration .080 HYG Vol OUT 000
627.00' 6" PERFORATED SCHEDULE UD 'INV. ELEV.= INV OUT= 626.60
.
Retained Vol .001 UNDERDRAIN GRAVEL 40 PVC PIPE OR EQUIVALENT 627.20 MIN. 4' WIDE & 4' DEEP IMPERVIOUS
---------- (AASHT0 M43 MIN. AAA2. 1.07. SLOPE (MIN.) TO LUCK BIO-FILTER MIX OR TESTED CORE & CUTOFF TRENCH (TOP ELEV.=
Unrouted Vol -.000 ac-ft (.005% of Inflow Volume) 1 0 ABOVE & BELOW CULVERT PROWDED ACROSS AND APPROVED EQUIVALENT TOP 634.0, BOTTOM ELEV.=627.0) WITH 1:1
UNDERDRAIN PIPE) EN77RE WIDTH 0 20' O.C. ELEV. = 631.00 (TYP.) DEPTH= SIDE SLOPES
2.5' MIN- SLOPE= 0.009
_BIOFILTER
T
(NOT TO SCALE)
NOTE.
THE ULTIMATE DEVELOPMENT SHALL BE DESIGNED FOR A 'C' VALUE OF 0.50 DRAINING TO THE PROPOSED BIOFILTER. A 'C' VALUE OF 0.50 ON A DRAINAGE AREA OF 2.78ac WILL PRODUCE
ROUGHLY 1.39ac. OF IMPERVIOUS AREA. THIS 810-FILTER SHALL BE DESIGNED TO TREAT 50% OF THE IMPERVIOUS AREA. THEREFORE, THE BOTTOM OF THE 810-FILTER SHALL BE SIZED TO
2.5% OF THE IMPERVIOUS AREA. 2.5% OF 2.8ac. EQUALS 3,027 sf. THE BIOFILTER FLOOR AREA EQUALS 4,346 sf.
0.25" OF RUNOFF PER 1 ACRE OF IMPERVIOUS DRAINAGE AREA GENERATES A WATER QUALITY VOLUME OF 1,249 cf FOR ROUGHLY 1.39 ac. OF IMPERVIOUS AREA. THE FOREBAY VOLUME
CONTAINS 1,253 cf.
THE SOIL AROUND THE SPILLWAY IS TO BE AT 95% COMPACTION WITH AN IMPERVIOUS CORE AND CUT-OFF TRENCH. THE SPILLWAY AND DOWNSTREAM OF THE SPILLWAY WILL BE LINED WITH
VOOT STD. EC -1 CLASS I/ RIPRAP. THE VEGETATIVE COVER ON THE DAMS AND AROUND THE POND BANKS WILL BE SOD-FORMING GRASS.
THE DESIGN PEAK RELEASE RATE FROM THE BIO-FILTER EQUALS THE 100 YEAR DESIGN PEAK RATE OF INFLOW TO THE SPILLWAY, WHICH IS 1.04 CFS. A PERMISSIBLE VELOCITY OF 5.00 FPS
WAS UTILIZED DUE TO AN EROSION RESISTANT LINING AND SOD-FORMING GRASS IMMEDIATELY DOWNSTREAM OF THE SPILLWAY.. A UNIT DISCHARGE, q, OF 0.5 cfs /ft IS USED. THE UNIT
DISCHARAGE WAS DETERMINED FROM TABLE 5-13C WITH A RETARDANCE CLASSIFICATION OF C, A SLOPE OF LESS THAN 17., AND A PEAK MAXIMUM PERMISSIBLE VELOCITY WITHIN OUR RANGE.
THE PROPOSED BOTTOM WIDTH OF THE SPILLWAY IS GREATER THAN OR EQUAL TO 1.04 cfs / 0.5 cfs /ft OR 2.08 FEET. THE PROPOSED BOTTOM WIDTH IS 5 FEET. THE DEPTH OF FLOW,
Hp, IS EQUAL TO 0.16 FEET. AS A RESULT, THE FINAL STAGE ELEVATION OF 632.16' FOR A DEPTH OF FLOW OF 0.16" ABOVE THE SPILLWAY CREST ELEVATION OF 632.00 HAS A FLOW OF
1.04 CFS.
HYDRAULIC DIMENSIONS AND COEFFICIENTS FOR THE WEIR /SPILLWAY ARE 5' WIDE BY 0.5' DEEP FOR THE FOREBAY AND 5' WIDE AND 2.00' DEEP FOR THE PRINCIPAL SPILLWAY. THE WEIR
COEFFICIENT FOR EACH OF THE SPILLWAYS IS 3.333.
TOP OF DAM WIDTH= 8'
AT AN ELEVA 770N= 634.00
PRINCIPLE SPILL WAY
ELEV477ON= 632.00
SH OFD
SCOTT R. COLLINS�
No. 35791 i2�
100 YEAR WS.E.=63216 VDOT SID. EC-1 CL. ll W ZJ6 14)
TOP OF FOREBA Y DAM
WIDTH= 3.0' AT AN
ELEVA 770N= 632.50
FOREBAY SPILL WAY
ELEVATION= 6J2.00
ti
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RIP-RAP LINED EMERGENCY ui
SPILL WA Y W1 TH GEO- TEXTILE
UNDERLA YMEN T
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PRINCIPAL SPHJj WA Y DATE
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--- --- --- - BIOFILTER MIX
FROM "LUCK STONE"
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NO. 78 STONE COMPACTED
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100 YEAR WS.E.=63216 VDOT SID. EC-1 CL. ll W ZJ6 14)
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WIDTH= 3.0' AT AN
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FOREBAY SPILL WAY
ELEVATION= 6J2.00
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2 Year Post - Development
C o.600
Area (acres)12.2oo
IDFfile: a2
time of concentration (min) 16.00
receding factor 1.670
time increment 1.00
time limit (min) 36o.00
fudge factor 1.00
storm: specified duration
volume (cy) 1578.41
peak flow (cfs) 11.210
intensity (in /hr) 1.531
time to peak (min) 16.000
duration of peak (min) 42.00
routed true
Siofilter
Source: Virginia Stormwater Management Handbook, Volume 11
Equation 5 -5 of Chapter 5, page 21
Td= 112 x CA x a x (b- Tc /4)j 1112 - b
qo
C = 0.60
A = 12.20
2 Year
a= 106.02
b= 15.51
Tc = 7
10 Year 100 Year
a= 161.6 a= 244.82 Appendix 5A for
b= 18.73 b= 20.81 1 Albemarle County
qo = Maximum Allowable Peak Outflow To Meet Minimum MS -19 Standards
2 Year
10 Year
100 Year
= Qpre - Qby passed
= Qpre - Qbypassed
= Qpre - Qby passed
11.07 -0
= 14.68 -0
= 21.4 -0
= 11.07
= 14.68
= 21.4
2 Year (min.)
10 Year (min.)
100 Year (min.)
Td =28.4
Td =33.6
Td =35.7
ROUT17VG CALCULATIONS
INFLOWAT CRITICAL DURATION
10 Year Post - Development
C o.600
Area (acres) -12,200
1DFfile: aso
time of concentration (min) 16.00
receding factor 3..670
time increment 1.00
time limit (min) 36o.00
fudge factor i.00
storm: specified duration
volume (cy) 2090.38
peak flow (cfs)18.315
intensity (in /hr) 2.502
time to peak (min) 16.000
duration of peak (min) 30.00
routed true
loo Year Post - Development
C o.600
Area (acres) 12.200
1 D file: aloo
time of concentration (min) 16.00
receding factor 1.670
time increment 1.00
time limit (min) 36o.00
fudge factor 1.25
storm: specified duration
volume (cy) 3317.41
peak flow (cfs) 37.928
intensity (in /hr) 4.145
time to peak (min) 16.000
duration of peak (min)18.00
routed true
ROUTED OUnWWAT CRITICAL DURATION
2 Year Hydrograph
Routing Summary of Peaks: 2 Year Post- Development
inflow (cfs) 11.210 at 16.00 (min)
discharge (cfs) 7.839 at 66.00 (min)
water level (ft) 652.155 at 66.00 (min)
storage (cy) 1126.526
so Year Hydrograph
Routing Summary of Peaks: to Year Post - Development
inflow (cfs) 18.315 at 16.00 (min)
discharge (cfs) 14.137 at 52.00 (min)
water level (ft) 652.399 at 52.00 (min)
storage (cy) 1297.416
loo Year Hydrograph
Routing Summary of Peaks: loo Year Post - Development
inflow (cfs) 37.928 at 16.00 (min)
discharge (cfs) 32.115 at 38.00 (min)
water level (ft) 652.867 at 38.00 (min)
storage (cy) 1636.211
1 =30'
100 YEAR-
W. S. E. = 652.8 7
10 YEAR
W.S.E.= 652.40
2 YEAR------,,,
WS .E=652.16
PRINCIPLE SPILL WAY
ELEVA PON= 651.50
100 YEAR
W.S.E. =65287
10 YEAR
W.S.E.= 65240
2 YEAR
W. S.E. = 652.16
2.5'
1.15' 3„
NOTE:
AFTER THE CONSTRUCTION OF THIS DEVELOPMENT, THE IMPERVIOUS AREA CONTRIBUTING TO THE BIORETENTION FILTER IS ESTIMATED TO BE
318,859sf. THE BIORETENTION FILTER SHALL BE DESIGNED TO TREAT 509 OF THE IMPERVIOUS AREA. THEREFORE, THE BOTTOM OF THE
BIORETENTION FILTER SHALL BE SIZED TO 2.59 OF THE IMPERVIOUS AREA. 2.590 OF 318,859sf EQUALS 7,971sf. THE BIORETENTION FILTER FLOOR
AREA EQUALS 17,009sf. THE BIORETENTION FILTER FLOOR AREA IS SUFFICIENTLY SIZED TO HANDLE THIS, AS ARE THE FOREBAYS. THE ADDITIONAL
REMOVAL SHALL BE ACHIEVED THROUGH THE LICKINGHOLE BASIN AND THROUGH A PRO -RATA SHARE - CONTRIBUTION. ADDITIONALLY, THE PROPOSED
BIORETENTION FILTER AND FOREBAYS ARE SIZED TO HANDLE A MINIMUM OF AN ADDITIONAL 81,450sf OF FUTURE IMPERVIOUS AREA FOR A WATER
QUALITY REMOVAL EFFICIENCY OF 507..
FOR THIS DEVELOPMENT, 0.25" OF RUNOFF PER 1 ACRE OF IMPERVIOUS DRAINAGE AREA GENERATES A WATER QUALITY VOLUME OF 6, 643cf. THE
FOREBAY VOLUME PROVIDED IS 8,345cf.
THE SOIL AROUND THE SPILLWAY IS TO BE AT 959 COMPACTION WITH AN IMPERVIOUS CORE AND CUT -OFF TRENCH. THE SPILLWAY AND
DOWNSTREAM OF THE SPILLWAY WILL BE LINED WITH VDOT STD. EC -1 CLASS II RIPRAP. THE VEGETATIVE COVER ON THE DAMS AND AROUND THE
POND BANKS WILL BE SOD- FORMING GRASS.
THE DESIGN PEAK RELEASE RATE FOR THE SPILLWAY IS EQUAL 4.5cfs. A PERMISSIBLE VELOCITY OF 4.0 ft /s WAS UTILIZED DUE TO AN EROSION
RESISTANT LINING AND SOD- FORMING GRASS IMMEDIATELY DOWNSTREAM OF THE SPILLWAY. A UNIT DISCHARGE, q, OF 1.5 cfs /ft WAS USED. THE
UNIT DISCHARGE WAS DETERMINED FROM TABLE 5 -13C WITH A RETARDANT CLASSIFICATION OF C, A PEAK MAXIMUM PERMISSIBLE VELOCITY WITHIN
OUR RANGE, AND SLOPE BETWEEN 1 & 127.. ' THE PROPOSED BOTTOM WIDTH OF THE SPILLWAY IS GREATER THAN OR EQUAL TO 4.5cfs / 1.5
cfs /ft OR 3.0 FEET. THE PROPOSED BOTTOM WIDTH IS 3.0 FEET
THE DEPTH OF FLOW, Hp, IS EQUAL TO 0.66 FEET DURING THE 2 YEAR CRITICAL DURATION STORM, WHICH FEATURES A FLOW OF 7.84cfs. AS A
RESULT, THE FINAL STAGE ELEVATION OF 652.16' FOR A DEPTH OF FLOW OF 0.66' ABOVE THE SPILLWAY CREST ELEVATION OF 651.50' HAS A
FLOW OF 7.84cfs.
FOR CONTOUR AREAS, ELEVATIONS, STORAGE VOLUMES,
HYDRAULIC DIMENSIONS AND COEFFICIENTS FOR THE WEIR /SPILLWAY ARE 5' WIDE BY 2' DEEP FOR THE FOREBAY AND 3' WIDE BY 2.50' DEEP FOR
THE PRINCIPLE SPILLWAY. THE WEIR COEFFICIENT FOR EACH OF THE SPILLWAYS IS 3.3.
TOP OF DAM WIDTH= 10.0'
AT AN ELEVATION= 654.0
1.13' OF FREE BOARD
- - - -- 7---- - - - - --
3.0' VDOT STD. EC -1 CL. It DRY
RIP -RAP LINED SPILLWAY
WITH GEO- TEX77LE
UNDERLAYMENT
PRINCIPLE SPILLWAYS
3' WIDE FOREBA Y TOP 100 YEAR
OF DAM ELEV.= 653 W.S.E. =65287
CLEAN -OUT W/ 10 YEAR
3" OF PEA GRAVEL WA TER 77 �y S.E. = 652.40
SHALL BE PLACED CAP 50' D. C.
BETWEEN THE FILTER ELEV. = 651.50' 2 YEAR
MEDIA AND THE (TYP.) W. S E. = 652.16
UNDERDRAIN MEDIA In
s0 �p1 N
BOTTOM OF FOREBAY� 5
648.06 n MIN.
5' WIDE ROCK WEIR
ELEV. = 651.00
BOTTOM OF BIORETENTION-"
BASIN 6470 MIN.
UNDERDRAIN GRA VEL-
(AASHTO M43 MIN.
1 ABOVE & BELOW
UNDERDRAIN PIPE)
31MISTAIMIENE-01
111,11010101klv�
10' WIDE TOP OF DAM
ELEV. = 654.00
TOP OF FOREBA Y DAM 10 YEAR
WIDTH= 3.0' AT AN W.S.E.= 652.40
ELEVA 770N= 653 2 YEAR
W.S. E.= 652.16
100 YEAR ---------- - - - --- - - !� Z 0'
W.S.E. =65287
5.0' VDOT STD. EC -1 CL. ll DRY
FOREBAY SPILLWAY RIP -RAP LINED EMERGENCY
ELEVATION= 651.0 SPILLWAY WITH GEO- TEXTILE
UNDERLAYMENT
FOI"AYSPILLWAY
,/WEIR ELEV.= 651.50'
/ 8' MAX. EMBANKMENT HT
1' DECORA77VE ROCK WEIR OVER
CONCRETE OUTFALL CHANNEL.
/ W =3, D =2, L =225'
-� 0.50' OF
ENERGY DISSIPATOR
PONDING VDOT STD. EC -1 CLASS
DEPTH 11 DRY RIPRAP
\ \ W/ GEO- FABRIC
UNDERLAYMENT
(3'Wx 16.5'Lx2'D)
I-ELEV = 651'
10.0' MIN. -
40LF�3.09
6 PERFORATED SCHEDULE 40 UD INV ELEV.= INV. OUT= 646.0'
PVC PIPE OR EQUIVALENT AAA2. 647.20' MIN. 4' WIDE & 4' DEEP
1.09 SLOPE (MIN.) TO OUTFALL STATE APPROVED MIX. TOP ELEV. = IMPERVIOUS CORE &
PIPE PROVIDED ACROSS EN77RE 651.00 (TYP.) DEPTH= 25' MIN, CUTOFF TRENCH WITH 1:1
WIDTH ® 20' 0. C, SLOPE= 0.009 SIDE SLOPES. SEE DETAIL
BIORETENTION FILTER ON THIS SHEET.
(NOT TO SCALE
TH p
O SCOTT R. COLLINS%
0 No. 35791 Ltbl
�'9I0NAL ECG,'
Aa
i`2 '
0' TOP OF DAM
ELEV.- 654.0
loo Year Post - Development
C o.600
Area (acres) 12.200
1 D file: aloo
time of concentration (min) 16.00
receding factor 1.670
time increment 1.00
time limit (min) 36o.00
fudge factor 1.25
storm: specified duration
volume (cy) 3317.41
peak flow (cfs) 37.928
intensity (in /hr) 4.145
time to peak (min) 16.000
duration of peak (min)18.00
routed true
ROUTED OUnWWAT CRITICAL DURATION
2 Year Hydrograph
Routing Summary of Peaks: 2 Year Post- Development
inflow (cfs) 11.210 at 16.00 (min)
discharge (cfs) 7.839 at 66.00 (min)
water level (ft) 652.155 at 66.00 (min)
storage (cy) 1126.526
so Year Hydrograph
Routing Summary of Peaks: to Year Post - Development
inflow (cfs) 18.315 at 16.00 (min)
discharge (cfs) 14.137 at 52.00 (min)
water level (ft) 652.399 at 52.00 (min)
storage (cy) 1297.416
loo Year Hydrograph
Routing Summary of Peaks: loo Year Post - Development
inflow (cfs) 37.928 at 16.00 (min)
discharge (cfs) 32.115 at 38.00 (min)
water level (ft) 652.867 at 38.00 (min)
storage (cy) 1636.211
1 =30'
100 YEAR-
W. S. E. = 652.8 7
10 YEAR
W.S.E.= 652.40
2 YEAR------,,,
WS .E=652.16
PRINCIPLE SPILL WAY
ELEVA PON= 651.50
100 YEAR
W.S.E. =65287
10 YEAR
W.S.E.= 65240
2 YEAR
W. S.E. = 652.16
2.5'
1.15' 3„
NOTE:
AFTER THE CONSTRUCTION OF THIS DEVELOPMENT, THE IMPERVIOUS AREA CONTRIBUTING TO THE BIORETENTION FILTER IS ESTIMATED TO BE
318,859sf. THE BIORETENTION FILTER SHALL BE DESIGNED TO TREAT 509 OF THE IMPERVIOUS AREA. THEREFORE, THE BOTTOM OF THE
BIORETENTION FILTER SHALL BE SIZED TO 2.59 OF THE IMPERVIOUS AREA. 2.590 OF 318,859sf EQUALS 7,971sf. THE BIORETENTION FILTER FLOOR
AREA EQUALS 17,009sf. THE BIORETENTION FILTER FLOOR AREA IS SUFFICIENTLY SIZED TO HANDLE THIS, AS ARE THE FOREBAYS. THE ADDITIONAL
REMOVAL SHALL BE ACHIEVED THROUGH THE LICKINGHOLE BASIN AND THROUGH A PRO -RATA SHARE - CONTRIBUTION. ADDITIONALLY, THE PROPOSED
BIORETENTION FILTER AND FOREBAYS ARE SIZED TO HANDLE A MINIMUM OF AN ADDITIONAL 81,450sf OF FUTURE IMPERVIOUS AREA FOR A WATER
QUALITY REMOVAL EFFICIENCY OF 507..
FOR THIS DEVELOPMENT, 0.25" OF RUNOFF PER 1 ACRE OF IMPERVIOUS DRAINAGE AREA GENERATES A WATER QUALITY VOLUME OF 6, 643cf. THE
FOREBAY VOLUME PROVIDED IS 8,345cf.
THE SOIL AROUND THE SPILLWAY IS TO BE AT 959 COMPACTION WITH AN IMPERVIOUS CORE AND CUT -OFF TRENCH. THE SPILLWAY AND
DOWNSTREAM OF THE SPILLWAY WILL BE LINED WITH VDOT STD. EC -1 CLASS II RIPRAP. THE VEGETATIVE COVER ON THE DAMS AND AROUND THE
POND BANKS WILL BE SOD- FORMING GRASS.
THE DESIGN PEAK RELEASE RATE FOR THE SPILLWAY IS EQUAL 4.5cfs. A PERMISSIBLE VELOCITY OF 4.0 ft /s WAS UTILIZED DUE TO AN EROSION
RESISTANT LINING AND SOD- FORMING GRASS IMMEDIATELY DOWNSTREAM OF THE SPILLWAY. A UNIT DISCHARGE, q, OF 1.5 cfs /ft WAS USED. THE
UNIT DISCHARGE WAS DETERMINED FROM TABLE 5 -13C WITH A RETARDANT CLASSIFICATION OF C, A PEAK MAXIMUM PERMISSIBLE VELOCITY WITHIN
OUR RANGE, AND SLOPE BETWEEN 1 & 127.. ' THE PROPOSED BOTTOM WIDTH OF THE SPILLWAY IS GREATER THAN OR EQUAL TO 4.5cfs / 1.5
cfs /ft OR 3.0 FEET. THE PROPOSED BOTTOM WIDTH IS 3.0 FEET
THE DEPTH OF FLOW, Hp, IS EQUAL TO 0.66 FEET DURING THE 2 YEAR CRITICAL DURATION STORM, WHICH FEATURES A FLOW OF 7.84cfs. AS A
RESULT, THE FINAL STAGE ELEVATION OF 652.16' FOR A DEPTH OF FLOW OF 0.66' ABOVE THE SPILLWAY CREST ELEVATION OF 651.50' HAS A
FLOW OF 7.84cfs.
FOR CONTOUR AREAS, ELEVATIONS, STORAGE VOLUMES,
HYDRAULIC DIMENSIONS AND COEFFICIENTS FOR THE WEIR /SPILLWAY ARE 5' WIDE BY 2' DEEP FOR THE FOREBAY AND 3' WIDE BY 2.50' DEEP FOR
THE PRINCIPLE SPILLWAY. THE WEIR COEFFICIENT FOR EACH OF THE SPILLWAYS IS 3.3.
TOP OF DAM WIDTH= 10.0'
AT AN ELEVATION= 654.0
1.13' OF FREE BOARD
- - - -- 7---- - - - - --
3.0' VDOT STD. EC -1 CL. It DRY
RIP -RAP LINED SPILLWAY
WITH GEO- TEX77LE
UNDERLAYMENT
PRINCIPLE SPILLWAYS
3' WIDE FOREBA Y TOP 100 YEAR
OF DAM ELEV.= 653 W.S.E. =65287
CLEAN -OUT W/ 10 YEAR
3" OF PEA GRAVEL WA TER 77 �y S.E. = 652.40
SHALL BE PLACED CAP 50' D. C.
BETWEEN THE FILTER ELEV. = 651.50' 2 YEAR
MEDIA AND THE (TYP.) W. S E. = 652.16
UNDERDRAIN MEDIA In
s0 �p1 N
BOTTOM OF FOREBAY� 5
648.06 n MIN.
5' WIDE ROCK WEIR
ELEV. = 651.00
BOTTOM OF BIORETENTION-"
BASIN 6470 MIN.
UNDERDRAIN GRA VEL-
(AASHTO M43 MIN.
1 ABOVE & BELOW
UNDERDRAIN PIPE)
31MISTAIMIENE-01
111,11010101klv�
10' WIDE TOP OF DAM
ELEV. = 654.00
TOP OF FOREBA Y DAM 10 YEAR
WIDTH= 3.0' AT AN W.S.E.= 652.40
ELEVA 770N= 653 2 YEAR
W.S. E.= 652.16
100 YEAR ---------- - - - --- - - !� Z 0'
W.S.E. =65287
5.0' VDOT STD. EC -1 CL. ll DRY
FOREBAY SPILLWAY RIP -RAP LINED EMERGENCY
ELEVATION= 651.0 SPILLWAY WITH GEO- TEXTILE
UNDERLAYMENT
FOI"AYSPILLWAY
,/WEIR ELEV.= 651.50'
/ 8' MAX. EMBANKMENT HT
1' DECORA77VE ROCK WEIR OVER
CONCRETE OUTFALL CHANNEL.
/ W =3, D =2, L =225'
-� 0.50' OF
ENERGY DISSIPATOR
PONDING VDOT STD. EC -1 CLASS
DEPTH 11 DRY RIPRAP
\ \ W/ GEO- FABRIC
UNDERLAYMENT
(3'Wx 16.5'Lx2'D)
I-ELEV = 651'
10.0' MIN. -
40LF�3.09
6 PERFORATED SCHEDULE 40 UD INV ELEV.= INV. OUT= 646.0'
PVC PIPE OR EQUIVALENT AAA2. 647.20' MIN. 4' WIDE & 4' DEEP
1.09 SLOPE (MIN.) TO OUTFALL STATE APPROVED MIX. TOP ELEV. = IMPERVIOUS CORE &
PIPE PROVIDED ACROSS EN77RE 651.00 (TYP.) DEPTH= 25' MIN, CUTOFF TRENCH WITH 1:1
WIDTH ® 20' 0. C, SLOPE= 0.009 SIDE SLOPES. SEE DETAIL
BIORETENTION FILTER ON THIS SHEET.
(NOT TO SCALE
TH p
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0 No. 35791 Ltbl
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MASTER PLAN DEVELOPMENT OF THE BLOCKS WITHIN THE DRAIANGE AREA AS SHOWN ON THE STORMWATER MANAGEMENT SHEET PLAN SHEET 1.
THE BIO- FILTERS SHALL BE DESIGNED TO TREAT 507. OF THE IMPERVIOUS AREA.
THE SOIL AROUND THE SPILLWAY IS TO BE VERIFIED THAT IT IS COMPACTED AT A 957. COMPACTION WITH AN IMPERVIOUS CORE. THE SPILLWAY AND
DOWNSTREAM OF THE SPILLWAY WILL BE LINED WITH VDOT STD. EC -1 CLASS 11 RIPRAP. THE VEGETATIVE COVER ON THE DAMS AND AROUND THE
POND BANKS WILL BE SOD - FORMING GRASS.
THE DESIGN PEAK RELEASE RATE FROM THE POND EQUALS THE 100 YE4R DESIGN PEAK RATE OF INFLOW TO THE SPILLWAY. A PERMISSIBLE
VELOCITY OF 5.0 FPS WAS UTILIZED DUE TO AN EROSION RESISTANT LINING AND SOD- FORMING GRASS IMMEDIATELY DOWNSTREAM OF THE SPILLWAY.
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WID TH OF
1
DAM
TOP OF DAM = 8'
100 YEAR
CLEAN -OUT W/
t" u
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3" OF PEA GRAVEL
WA TER 77GHT
WEIR
SHALL BE PLACED
CAP (TYP.)
BETWEEN THE FILTER
2' DECORA77VE ROCK WEIR OVER
10 YEAR MEDIA AND THE
UNDERDRAIN MEDIA
CONCRETE OUTFALL CHANNEL.
0.0 0
2 YEAR SLOPE
g
1.00
1.00' OF ENERGY DISSIPATOR
g —
-' PONDING
2.5'
> � D EP TH
M /N.
MIN.
ROCK WEIR
10.0' MlN
BOTTOM OF BIOF /L 1ER
MIN. 4' WIDE & 4' DEEP IMPERVIOUS
6" PERFORATED SCHEDULE
CORE & CUTOFF TRENCH WITH 1:1 SIDE
UNDERDRAIN GRAVEL 40 PVC PIPE OR EQUIVALENT
SLOPES
(AASHTO M43 MIN. AAA2
1.07 SLOPE (MIN.) TO LUCK BIO-
FILTER MIX OR TESTED
1 ABOVE & BELOW CULVERT PROVIDED ACROSS AND APPROVED EQUIVALENT.
UNDERDRAIN PIPE) EN77RE
W1D77-1 ® 20' 0. C,
BIOFILTER
(NOT TO SCALE)
ROUTING CALCULATIONS
INFLOWAT CRITICAL DURATION
2 Year Post - Development
xo Year Post - Development
zoo Year Post - Development
C 0.600
C o.600
C o.600
Area (acres) 5.800
Area (acres) 5.800
Area (acres) 5.800
IDF file: az
IDF file: aso
IDF file: a3oo
time of concentration (min) 3o.o time
of concentration (min) 3o.00
time of concentration (min) xo.00
receding factor 3.670
receding factor 3.670
receding factor x.670
time increment 3.00
time increment'.00
time increment'.00
time limit (min) 36o.00
time limit (min) 360 -00
time limit (min) 36o.00
fudge factor 3.00
fudge factor 3.00
fudge factor 3.35
storm: specified duration
storm: specified duration
storm: specified duration
volume (cy) 1-235.2
volume (cy) mS07.33
volume (Cy) 2307.33
peak flow (cfs) S.23o
peak flow (cfs) 8.782
peak flow (cfs) 31.2_77
intensity (in /hr) 3.53'
intensity (in /hr)'.83o
intensity (in /hr) 2.542
time to peak (min) -x6.000
time to peak (min) 16.000
time to peak (min) 3.6.000
duration of peak (min) 42.00
duration of peak (min) 30.00
duration of peak (min) 38.00
routed true
routed true
routed true
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THE ULTIMATE DEVELOPMENT SHALL BE DESIGNED FOR A 'C' VALUE OF 0.50 DRAINING TO THE BIO- FILTERS. THIS IMPERVIOUS AREA INCLUDES THE
MASTER PLAN DEVELOPMENT OF THE BLOCKS WITHIN THE DRAIANGE AREA AS SHOWN ON THE STORMWATER MANAGEMENT SHEET PLAN SHEET 1.
THE BIO- FILTERS SHALL BE DESIGNED TO TREAT 507. OF THE IMPERVIOUS AREA.
THE SOIL AROUND THE SPILLWAY IS TO BE VERIFIED THAT IT IS COMPACTED AT A 957. COMPACTION WITH AN IMPERVIOUS CORE. THE SPILLWAY AND
DOWNSTREAM OF THE SPILLWAY WILL BE LINED WITH VDOT STD. EC -1 CLASS 11 RIPRAP. THE VEGETATIVE COVER ON THE DAMS AND AROUND THE
POND BANKS WILL BE SOD - FORMING GRASS.
THE DESIGN PEAK RELEASE RATE FROM THE POND EQUALS THE 100 YE4R DESIGN PEAK RATE OF INFLOW TO THE SPILLWAY. A PERMISSIBLE
VELOCITY OF 5.0 FPS WAS UTILIZED DUE TO AN EROSION RESISTANT LINING AND SOD- FORMING GRASS IMMEDIATELY DOWNSTREAM OF THE SPILLWAY.
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