20080067 Ver 6_Modifications_20120709

WITHERS &— RAVENEL
ENGINEERS I PLANNERS I SURVEYORS
1410 COMMONWEALTH DRIVE SUITE 101
WILMINGTON NORTH CAROLINA 28403
[phone]
FAX [phone]
TO NC Division of Water Quality — 401 Wetlands Unit
1650 Mail Service Center
Raleigh NC 27699
WE ARE SENDING YOU
❑ Shop Drawings
❑ Copy of Letter
LETTER Oo MANS- MMAL
DATE 7/6/12
108 NO 02130018 00
ATrENTION Ms Annette Lucas
PHONE #
RE Alston Pond Buffer Authorization
Notification of Modification of BMP #2
® Attached ❑ Under separate cover via the following items
❑ Prints ❑ Plans ❑ Samples ❑ Specifications
❑ Change order ❑ Diskette ❑
COPIES DATE NO I DESCRIPTION
3 7/6/12 02110018 0o I Notification of Modification of Outfall Structures of BMP #2
THESE ARE TRANSMITTED as checked below
® For approval ❑ Approved as submitted
❑ For your use ❑ Approved as noted
❑ As requested ❑ Returned for corrections
❑ For review and comment ❑
❑ FOR BIDS DUE 20 ❑ PRINTS RETURNED AFTER LOAN TO US
❑ Resubmit
❑ Submit
❑ Return
copies for approval
copies for distribution
corrected prints
REMARKS
COPY TO File
SIGNED Troy Beasley
If enclosures are not as noted kindly notify us at once

WITHERS & RAVENEL
ENGINEERS I PLANNERS I SURVEYORS
July 6, 2012
NC Division of Water Quality
Attn Ms Annette Lucas
1650 Mail Service Center
Raleigh, NC 27699 1650
Re Alston Pond Subdivision
Notification of Modification of Design of BMP #2
DWQ# o8 oo67 Ver -ks
W &R Project Number — 0211oo18 o0
Dear Ms Lucas
Jul _ L t1
QUALii�
This letter is to notify you of a proposed modification of the design of the outfalls for
BMP #2 for the Alston Pond Subdivision
The subject property is approximately 148 acres in size and is located on the east
and west side of Hwy 55 south of the intersection of Old Adams Road and Hwy 55 in
Fuquay Varina, Wake County, North Carolina at Latitude 35 6262765 N and
Longitude 78 8132158 W The site contains unnamed tributaries to Basal Creek and
is located in the Neuse River Basin The Water Quality Classification for these
features is B, NSW, the Cataloging Unit for this site is 030202o1, and the Stream
Index number Is 27 43 15 3
DWQ issued a 401 WQC /Buffer Authorization (DWQ Project # o8 oo67, Ver 4) for the
Alston Pond Subdivision on January 13 2012
Proposed Modification
The design approved in the previous 401 WQC /Buffer Authorization had the 42 high
flow bypass pipe located to the north and the 4' water quality outfall located to the
south The contractors made a mistake In the Installation of the outlet function box
resulting in the outfalls being flipped so that the 42' bypass will be to the south and
the 4 outfall will be to the north
This results in a switch of the locations of the level spreader and filter strip for the 4
water quality outfall and the bypass channel for the 42 high flow bypass This will
simply result in a change in location only, as the buffer impacts for the bypass
channel will be the same as previously approved but in a different location I have
enclosed a copy of the previously approved design for BMP #2 as well as the
proposed revision to the outfall locations I have also included the updated BMP
iii MacKenan Drive I Cary NC 275111 tel [phone] fax [phone] I www withersravenel com
1410 Commonwealth Drive I Suite 1o1 I Wilmington NC 284031 tel [phone] fax [phone]
416 D Gallimore Dairy Road I Greensboro NC 27409 1 tel [phone] fax [phone]
N C Engineering Board No C 0832

WITHERS &' RAVENEL
ENGINEERS I PLANNERS I SURVEYORS
Supplement Forms for BMP #2
We believe that this will be a minor modification to the 401 Buffer Authorization for
which this notification will be sufficient and submittal of a new PCN or issuance of a
revised Buffer Authorization will not be required
Please feel free to contact me if you have any questions or require additional
information to complete your review of the application
Sincerely,
Troy Beasley
Environmental Scientist
WITHERS & RAVENEL INC
Attachments —
1) 401 WQC/ Buffer Authorization for Alston Pond
2) Previously Approved BMP #2 Design
3) Proposed Revision for BMP #2 Outfalls
4) BMP Supplement Forms
iii MacKenan Drive I Cary NC 275111 tel [phone] fax [phone] I www withersravenel com
1410 Commonwealth Drive I Suite 1o1 I Wilmington NC 284031 tel [phone] fax [phone]
416 D Gallimore Dairy Road I Greensboro NC 274091 tel [phone] fax [phone]
N C Engineering Board No C 0832

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A �
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER VEGETATED FILTER STRIP (LS VFS) SUPPLEMENT
This form must be completely filled out printed initialed and submitted
t Y7
�V
i
n
1 PROJECT 1NF0RMATI0N
cis
Project name
Alston Pond
Contact name
Troy Beasley
Phone number
919-469 3340
Date
aG /r,(- /y
Drainage area number
BMP #2
II DESIGN INFORMATION
The purpose of the LS VFS
Buffer Ru a Diffuse Flow
Stormwater enters LS-VFS from
A BMP
Type of VFS
Protected riparian buffer (slope < 5°/ )
Explanation of any Other' responses above
If Stormwater Enters the LS VFS from the Drainage Area
Drainage area
Impervious surface area
Percent Impervious
Rational C coefficient
Peak flow from the 1 inlhr stone
Time of concentration
Rainfall intensity 10•yr storm
Peak flow from the 10 yr storm
Design storm
Maximum amount of flow directed to the LS-VFS
Is a How bypass system going to be used?
Explanation of any Other' responses above
It Stormwater Enters the LS VFS from a BMP
Type of BMP
Peak discharge from the BMP during the design storm
Peak discharge from the BMP during the 110-year storm
Maximum capacity of a 100 -foot long LS-VFS
Peak flow directed to the LS VFS
Is a Flow bypass system going to be used?
Explanation of any Other" responses above
LS VFS Design
fe
ft
cis
min
rnthr
cis
ih (It a N 1 l 1 1 r r (r
Do i o c nf1 I e t r i r rr
hl 1h F r r r) r
nl 11 Ice I F r
of (,0111P a L`( 1 ( r r
Of Cf I f.1
t t M lh
Pick one
cis I n i t y)i a f I I
(Y or N) D a c 11or tc thr r t ( of 1 it
Wet detentlon pond
086
cis
086
cfs
2
cfs
086
cis
Y—
(Y or N)
Forebay surface area sq ft
Depth of forebay at stormwater entry point in
Depth of forebay at stormwater exit point in
Feet of level lip needed per cis 50 fNcfa
Computed minimum length of the level lip needed ft
Length of level lip provided It
Form SW401 LS VFS 29No 2010 Rev 8 page 1 of 3

Width of VFS
Elevation at downsiope base of level lip
Elevation at the and of the VFS that is farthest from the LS
Slope (from level lip to the and of the VFS)
Are any draws present in the VFS?
Is there a collector sxale at the end of the VFS?
Bypass System Design (d applicable)
Is a bypass system provided?
Is there an engineered flow splitting device?
Dimensions of the channel (see dlagram below)
M
B
W
y (flow depth for 10 year storm)
freeboard (during the 10 year storm)
Peak velocity in the channel during the 10 yr storm
Channel lining material
Does the bypass discharge through a wetland?
Does the channel enter the stream at an angle?
Explanation of any Other" responses above
4. —
ft
fm I
fill I
(f or N)
(Y or N)
Y {f N)
Y ( or N) °lelse b ? e vla 1 lei d i,f fl'o s AI all a sa f rhncl
200
it
400
ft
1200
ft
085
n
1 15
ft
384
rvsec
Pi k one ,qip
W Gt rinl�>�
N
(Y or N)
Y
(Y or N)
W
III REQUIRED ITEMS CHECKLIST i l s
EDIT Please Indicate the page or plan sheet numbers where the supporting documentation can be found An Incomplete submittal package will result in
a request for additional Information This will delay final review and approval of the project Initial in the space provided to indicate the following
design requirements have been met. If the applicant has designated an agent, the agent may initial below If a requirement has not been met attach
justification
Requrled Rem
1 Plans (1 50' or larger) of the entire site showing
Design at ultimate build -out
Off -site drainage (if applicable)
Delineated drainage basins (include Rational C coefficient per basin)
Forebay (ff applicable)
High flow bypass system
Maintenance access
Proposed drainage easement and public right of way (ROAN) and
Boundaries of drainage easement
Initials Page or plan sheet number and any notes
ML-4-
S1-�;I ) 2z 22, Z-q
601 L) r7' L Iii vJ ir _ 7
Form SW401 LS VFS 29Nov2o10 Rev a page 2 of 3

2 Plan details (t 30' or Larger) for dt level spreader shoring
Forebay (if apphcaole)
High ffav bypass system
one foot topu Imes between the level lip and top of stream bank
Proposed drainage easement and
Design at ut8mate bwkf out
3 Section new of the level spreader (t 217 or larger) showing.
Undefdraat system (it appkcabto)
Level lip
Upstope diannel and
Downslope filter fabric
4 Plan details of the flow splifiing device and stipportmg calculations (d applicable)
4
G
J
�z L�
5 A construction sequence MI shawl how ft level spreader will be protected from
sediment until the entire drainage area is slaWed
I
6 If a non- engmeered VFS Is being used then provide a photograph of the VFS showing
that no draws are present
7 The Supportingcalablions
8 A copy of the signed and notarized operation and mamtenance (O&M) agreement
- 1- .iL- -1
Fa n SW401 LS-VFS 29Nnv20t0 Revs page 3 of 7

Project Description
Friction Method
Solve For
input Data
Roughness Coefficient
Channel Slope
Left Side Slope
Right Side Slope
Bottom Width
Discharge
Results
Normal Depth
Flow Area
Wetted Perimeter
Top Width
Cnbcal Depth
Critical Slope
Velocity
Velocity Head
Specific Energy
Froude Number
Flow Type
GVF Input Data
Downstream Depth
Length
Number Of Steps
GVF Output Data
Upstream Depth
Profile Description
Profile Headloss
Downstream Velocity
Upstream Velocity
Normal Depth
Cnbcal Depth
Channel Slope
Critical Slope
1/28/201 t 9 08 13 AM
BMP #2 HIGH FLOW BYPASS
Manning Formula
Normal Depth
Subcnticai
0 069
006000 ft/ft
200 ft/ft (H V)
200 ivft (H V)
400 R
1860 ft' /s
085 ft
485 ftz
780 ft
740 ft
077 ft
008793 ft/ft
384 ft/s
023 ft
108 ft
D 84
000 It
000 ft
0
000 ft
000
It
Infinity
ft/s
Infinity
ft/s
085
ft
077
ft
006000
Nft
008793
Rift
Bentley Systems Inc Hassled Methods SohMon Center Bentley FlowMaster f08.0107iA01
27 Siemons Company Drive Suite 200 W Watertown CT 06795 USA +1 203.7554668 Page 1 of 1

HCDENR
Permit No
( b ,cm ded 153 DWG)
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
TMs form must be filled out punted and submitted
The Required Items Checklist (Pert III) must be printed filled out and submitted along with oil of the required information
I PROJECT INFORMATION
Project name Aston Pond
Contact person Alwy V Sm th In P E
Phone number 9 9) 4x9.3340
Date OG
Drainage area number 2
+M L
0 DESIGN INFORMATION
Site Characteristics
Drainage area
1589$40 ttv
impervious area post development.
816 750 rye
°/ impervious
5137%
Design rainfall depth
10 in
Storage Volume Non SAWaters
Minimum volume required
Volume provided
Storage Volume SA Waters
15 runoff volume
Pre - development i yr 24-hr runoff
Post- tevelopmenl1 yr 24- hrrunoff
Minmum volume required
Volume provided
Peak Flow Calculations
Is the prelpost control of the 1yr 24hr storm peak flow required?
1 yr 24 hr rainfall depth
Rational C pr"evelopment
Rational C post - development
Rainfall intensity 1 yr 24-hr storm
Pre - development 1 yr 24 hr peak flow
Post- development 1 yr 24 hr peak flow
Pre/Post 1 yr 24 hr peak flow control
Elevations
Temporary pool elevation
Permanent pool elevation
SHWT elevation (approx at the perm pool elevation)
Top of 10ft vegetated shelf elevation
Bottom of 10ft vegetated shelf elevation
Sediment cieanout top elevation (bottom of pond)
Sedimentcleanout bottom elevation
Sediment storage provided
Is there additional volume stored above the state required temp pool?
Elevation of the top of the additional volume
67 881 fP OK
84 332 ft OK volume provided is equal to or in excess of volume required
ft�
ft'
�3
to
ft3
y (Y of N)
30 In
0 30 (uniltess)
0 51 (uniliess)
013lnfhr OK
15 61 Re /sec
1147 itsfsec
.414 ft /sec
367 40 fmsl
365 00 fmsl
fmsl
365 50 fmsl
364 50 fmsl
36000 fmsi
359 00 fmsl
100 ft
n (Y or N)
nisi
F SM( W i D I 1 13 n-Rev 8 9117109 1& II 3 ) 1 9 1 1

Perm It No .-
f or 1 tw -f by r'WW
II DESIGN INFORMATION
Surface Areas
Area temporary pool 39000 fly
Area REQUIRED permanent pool 28142 fe
SAIDA ratio 177 (umtless)
Area PROVIDED permanent pool lb,, 28,282 f? OK
Area bottom of 10ft vegetated shelf 16 dm 23A27 llv
Area sediment cleanout top elevation (bottom of pond) 1 4 13 943 f?
Volumes
Volume temporary pool
Volume permanent pool
Volume forebay (sum of forebays If more than one forebay)
Forebay % of permanent pool volume
SAIDA Table Data
Design TSS removal
Coastal SAIDA Table Used?
WuntainlPiedmont SAIDA Table Used9
SAIDA ratio
Average depth (used in SAIDA table)
Calculation option 1 used9 (See Figure 10 2b)
Volume permanent pool 14.aw
Area provided permanent pool
Average depth calculated
Average depth used in SAIDA 4, (Round to nearest 0 51t)
Calculation option 2 used? (See Figure 10 2b)
Area provided permanent pool P.„ vw
Area bottom of 1011. vegetated shelf p,k w,
Area sediment cleanout top elevation (bottom of pond) &_�w
84 332 fO OK
94 5D0 to
fe
85 A
n (Y or N)
IF (Y or N)
177 (unr0ess)
n (Yor N)
94 500 to
28 282 it
it Need 3 it min
it
y (Y or N)
28 282 fe
23 027 it
13 943 f1
Depth (distance blw bottom of 10ft shelf and top of sediment)
4 50 ft
Average depth calculated
410 ft
Average depth used in SAIDA Q„ (Round to nearest 0 5ft)
40111
Drawdown Calculations
100 ft
Drawdown through ordice?
y (Y or N)
Diameter of onfice (if circular)
4.00 in
Area of onfee (if non -circu ar)
0
Coefficient of discharge (Co)
0.60 (unitless)
Driving head (K)
2 40 it
Drawdown through weft
n (Y or N)
Weir type
(undless)
Coefficient of discharge (Q
(unifless)
Length of weir (L)
it
Driving head (H)
it
Pre -development 1 yr 24 hr peak flow
1561 felsec
Post development 1 yr 24 hr peak flow
1147 fO /sec
Storage volume discharge rate (through discharge onfrce or weir)
D 63 felsec
Storage volume drawdown time
2 00 days
Additional Information
Vegetated side slopes
3 1
Vegetated shelf slope
In 1
Vegetated shelf width
100 ft
Length of flowpath to width ratio
3 1
Length to width ratio
30 1
Trash rack for overflow b orifice?
y (Y or N)
Freeboard provided
0 8 it
Vegetated filter provided9
n (Y or N)
Recorded drainage easement provided?
y (Y or N)
Capures all runoff at ultimate buildout7
y (Y or N)
Drain mechanism for maintenance or emergencies 1s
Gate valve
OK
OK
OK draw down in 2 5 days
OK
OK
OK
OY
OK
OK
insufficient freeboard minimum of 1 it required
fnsuffrcleit Vegetated fitter required
OK
OK
Form SW401 W 10 1 do 8 R 8 9117/09 P h 1 3 11 0 m g 2

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NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
LEVEL SPREADER VEGETATED FILTER STRIP (LS VFS) SUPPLEMENT
This form must be completely filled out printed initialed and submitted
Y3 �
�V
1
n
1 PROJECT INFORMATION
Project name Alston Pond
Contact name Troy Beasley
Phone number 9'[9 469 3340
Date 0& /4- 7/y,
Drainage area number BMP #2 —
11 DESIGN INFORMATION
The purpose of the LS VFS Buffer Rule Diffuse Flow
Stormwater enters LS-VFS from A BMP
Type of VFS Protected riparian buffer (slope < 59' )
Explanation of any Other' responses above
If Stormwater Enters the LS VFS from the Drainage Area
Drainage area
Impervious surface area
Percent impervious
Rational C coefficient
Peak flow from the 1 inthr storm
Time of concentration
Rainfall intensity 10-yr storm
Peak flow from the 10 yr storm
Design storm
Maximum amount of flow directed to the LS VFS
Is a flour bypass system going to be used?
Explanation of any Other° responses above
If Stormwater Enters the LS VFS from a BMP
Type of BMP
Peak discharge from the BMP during the design storm
Peak discharge from the BMP during the 10 -year storm
Maximum capacity of a 100 foot long LS VFS
Peak flow directed to the LS VFS
Is a flaw bypass system going to be used?
Explanation of any Other' responses above
LS VFS Design
fe U rt r (I I t If ri r
fe Do I c c nil I c t r l a
1 )v t 1 FI Ih r i t
it I i icn
cis i) (Unp If Ct i t
min > of cofi ri 1 i 7
iruhr J t I rl 01 y t
cis 1 r ° 4t ci Ih
Pick one
cfs I n i t '1171 . n t I r
(Y or N) D r r1f tc Iii I t of 1
Wet detention pond
086
cis
086
cis
2
cis
086
cfs
Y
(Y or N)
Forebay surface area sq ft
Depth of forebay at stormwater entry point in
Depth of forebay at stormwater exit point rn
Feet of level lip needed per cis 50 tvcfs
Computed minimum length of the level lip needed ft
Length of level lip provided ft
Farm SW401 LS VFS 29Nov2010 Rev 8 paqe 1 of 3

Width of VFS
Elevation at downslope base of level lip
Elevation at the end of the VFS that is farthest from the LS
Slope (from level lip to the end of the VFS)
Are any draws present in the VFS?
Is there a collector smale at the end of the VFS?
Bypass System Design (d applicable)
Is a bypass system provided?
is there an engineered flow splitting device?
Dimensions of the channel (see diagram below)
M
B
W
y (flow depth for 10 -year storm)
freeboard (during the 10 year storm)
Peak velocity to the channel during the 10 yr storm
Channel lining material
Does the bypass discharge through a wefland?
Does the channel enter the stream at an angle?
Explanation of any Other" responses above
4, —
it
f1r 1
4P 1
(forlll
(Y or N)
Y {f a N)
Y (Y 3 FJ) °I be pf% c V18 1 1eletl Uf ftLw sal i r 8 sapt 111(x1 C -3IGs
200
f1
400
ft
1200
ft
085
ft
1 15
It
384
fV PC
Pi k Cie
" Ad�O Gl 4AIr.L-c-
N
(Y or N)
Y
(Y or N)
A
—_. ,t
y L j
III REQUIRED ITEMS CHECKLIST 1 d
EDIT Please indicate the page or plan sheet numbers where the supporting documentation can be found M Incomplete submittal package will result in
a request for additional information This will delay final review and approval of the project Initial In the space provided W Indicate the following
design requirements have been met. If the applicant has designated an agent, the agent may initial below If a requirement has not been met attach
justification
Requrled Item
1 Plans (1 50 or larger) of the entire site showug
Design at ultimate buBd -out,
Off -site drainage (0 applicable)
Delineated drainage basins (Include Rational C coefficient per basin)
Forebay (6 applicable)
High flow bypass system
Maintenance access
Proposed drainage easement and public right of way (ROW) and
Boundaries of drainage easement
Initials Page or plan sheet number and any notes
ML-
jpr ^L 15 0 J
Form SW401 LS VFS Mov2010 Rev a page 2 of 3

2 Plan details (1 W t„ ftger) for the level spreader showing
Forebay (if applicable)
Hugh flaw bypass system
one foot topo lines between the level lip and top of stream bank
Proposed drainage easement, and
Owign at ultimate bwld ad.
3 Section new of the level spreader (i 28' or larger) shaving
Underdmin system (d applicable)
Level lip
Upstope dlarfnK and
Dwislope Qler fabric
4 Plan delalls of the flaw so" dents and stipporhng cafufabons (d applicable)
5 A construction sequence that shows haw the I&M spreader will be protected from
sediment urd the entire drainage area is slabiRiized
6 If a non- engmeered VFS Is being used then provide a photograph of the VFS shot"
Ural no dress are present
7 The supporting calculations
8 A copy of the signed and iwtattzed operation and mamtenance (O&M) agreement
i
Y
nd
L
I
I
ZZ L"3
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Foi n SW401 LS VFS 29Nov2010 Rrri 8 paw 3 of 3

Project Description
Friction Method
Solve For
Inptjt Data
Roughness Coefficient
Channel Slope
Left Side Slope
Right Side Slope
Bottom Width
Discharge
Results
Normal Depth
Flow Area
Wetted Perimeter
Top Width
Critical Depth
Critical Slope
Velocity
Velocity Head
Specific Energy
Froude Number
Flow Type
GVF Input Data
Downstream Depth
Length
Number Of Steps
GVF Output Data
Upstream Depth
Profile Description
Profile Headloss
Downstream Velocity
Upstream Velocity
Normal Depth
Critical Depth
Channel Slope
Critical Slope
1 /26/2011 9 08 13 AM
BMP #2 HIGH FLOW BYPASS
Manning Formula
Normal Depth
Subcnhcal
0 069
006000 ft/ft
200 ft/ft (H V)
200 ft/ft (H V)
400 ft
1860 fN /s
085 ft
485 ftz
780 It
740 it
077 ft
008793 ft/ft
384 Ws
023 ft
108 ft
084
000 ft
000 it
0
000 ft
000
it
Infinity
ft/s
Infinity
ft/s
085
ft
077
It
006000
ft/ft
008793
ft/ft
Bentley Systems Inc Haestad Methods Solution Center Bentley FtowMaster [06.01 07140]
27 Slemone Company Drive Suite 200 W Watertown CT 06795 USA [phone] Page 1 of 1

Perm t No
(m b aro ded 151 DWG)
ACa
LE)J L
NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM -
401 CERTIFICATION APPLICATION FORM
WET DETENTION BASIN SUPPLEMENT
This form must be filled out pmded and submitted
The Requited Items Checklist (Pert 111) must be printed filled out and submitted along with all of the required informalton
I PROJECT INFORMATION
Project name
Aston Pond
Contact person
Alwy V mdh III P E
Phone number
9 9) 40-3340
Date
OG /'.-
Drainage area number
2
III DESIGN INFORMATION
Site Characteristics
Drainage area
1589$40 fe
Impervious area postdevelopment
816750 fl4
% impervious
5137%
Desgn rainfall depth
10 In
Storage Volume Non SAWaters
Minimum volume required
Volume provided
Storage Volume SA Waters
15 runoff volume
Pre - development 1 yr 24-hr runoff
post-development 1 yr 24-hr runoff
Mmenum volume required
Volume provided
Peak Flow Calculations
Is the prelpost control of the 1yr 24hr storm peak flow required?
1 yr 24 hr rainfall depth
Rational C pre-development
Rational C post - development
Rainfall Intensity, 1 yr 24-hr storm
Pre-development 1 yr 24 hr peak flow
PosWevelopmentI yr 24 hr peak flow
Pre/Post 1 yr 24 hr peak flow control
Elevations
Temporary pool elevation
Permanent pool elevation
SHWT elevation (approx at the perm pool elevation)
Top of IOft vegetated shelf elev-tron
Bottom of I Oft vegetated shelf elevation
Sediment cleanout, top elevation (bottom of pond)
Sediment cleanout bottom elevation
Sediment storage provided
Is there additional volume stored above the state - required temp pool?
Elevation of the top of the additional volume
67 881 if3 OK
84 332 iP OK volume provided is equal to or In excess of volume required
tt3
to
f3
tt3
to
It (Y or N)
30 In
0 30 (unfiless)
0 51 (undkss)
013 Mr OK
15 61 Osec
11 A7 fft isec
.414 ft /sec
367 40 fmsi
365 00 fmsl
fmsi
365 50 frost
364 50 fmsl
36000 fmsi
359 00 fmst
100 It
n (Y or N)
msl
F S WW W t 0 1 1 e n-R 6 9 17109 -1 & 0 3 t 9 1

Perm t No
r d b rvvc,l
II DESIGN INFORMATION
Surface Areas
Area temporary pool 39 090 fl
Area REQUIRED permanent pool 28142 tt7
SAIDA ratio 177 (umiless)
Area PROVIDED permanent pool 28,282 tr OK
Area bottom of 1011 vegetated shelf /6 „e1 23027 le
Area sediment cleanouL top elevation (bottom of pond) ,, 13$43 ft`
Volumes
Volume temporary pool 84 332 ft° OK
Volume permanent pool 1d,, , 94 50D fe
Volume forebay (sum of forebays if more than one forebay) fe
Forebay % of permanent pool volume %
SAIDA Table Data
Design TSS removal
Coastal SAIDA Table Used
fdountemlPiedmont SAIDA Table Used')
SAIDA ratio
Average depth (used in SAIDA table)
Celculadon option 1 used9 (See Figure 10 2b)
Volume permanent pool
Area provided permanent pool A..-Pd
Average depth calcul tad
Average depth used in MA 4. (Round to nearest 0 511)
Calculation option 2 used? (See Figure 10 2b)
Area provided permanent pool "
Area bottom of 10ft vegetated shelf U,w
Area sediment cleanout top elevation (bottom of pond) ,
85 /
n (Y or N)
y (Y or K)
177 (unifless)
n (Y or N)
94 500 it
28 28211`
it Need 311 min
it
y (Y or N)
28 28211`
23 027 fe
13 943 fe
Depth (distance b!w bottom of 10ft shelf and top of sediment)
4 50 ft
Average depth calculated
410 ft
Average depth used in SAIDA (k (Round to nearest D 511!
4 0 ft
Drawdown Calculations
Drawdown through orifice?
y (Y or N)
Diameter of onfice (if circular)
4A0In
Area of orifice (if non -circu ar)
in?
Coefficient of discharge (Co)
010 (unidess)
Owing head (h j
2 40 it
Drawdown through welr7
n
(Y or N)
Weir type
(undless)
Coefficient of discharge (Cv)
(unitless)
Length of weir (L)
ft
Driving head (H)
it
Pre -development 1 yr 24 hr peak flow
1 .)61 ft' /sec
Post development 1 yr 24 hr peak flow
1147 Wipe
Storage volume discharge rate (through discharge orifice orwen)
063 ft' /sec
Storage volume drawdown time
2 00 days
Additional Information
Vegetated side slopes
3 1
Vegetated shelf slope
10 1
Vegetated shelf width
1000
Length of flowpath to width ratio
3 1
Length to width ratio
30 1
Trash rack for overflow & orifice?
y
(Y or NJ
Freeboard provided
08 ft
Vegetated filter provided9
n
(Y or N)
Recorded drainage easement provided)
y
(Y or N)
Capures all runoff at ultimate build -outs
_ y
(Y or N)
Drain mechanism for maintenance or emergencies is
Gate valve
OK
OK
OK draws down in 7 5 days
OK
OK
OK
OK
OK
OK
Insufficient freeboard minimum of 1 It required
insufficent Vegetated filler required
OK
OK
F m SW401 W 10 1 0 8 R e 9i17rW P d 1 3 11 0 9 2