SW3180905_Supplement-EZ Form_20210712

IurrLr_iv1r_iv I - L L UVMrs r►yur—
)AD SUPPLEMENT FORMS
IOJECT INFORMATION
1 Project Name Twin Lakes
2
Project Area (ac)
105.5
3
Coastal Wetland Area (ac)
0
4
Surface Water Area ac
11.15
5
Is this proiect High or Low Density?
Low
g
1 Does this project use an off -site SCM?
No
IMPLIANCE WITH 02H .1003(4)
7
Width of vegetated setbacks provided (feet)
30
8
Will the vegetated setback remain vegetated?
Yes
9
If BUA is proposed in the setback, does it meet NCAC 02H.1003(4)(c-d)?
Yes
0
Is stream bank stabilization proposed on this project?
No
I. BER
AND TYPE OF SCMs:
Infiltration System
11
12
Bioretention Cell
13
Wet Pond
1
14
Stormwater Wetland
15
Permeable Pavement
16
Sand Filter
17
Rainwater Harvesting RWH)
18
Green Roof
19
Level Spreader -Filter Strip LS-FS
?0
Disconnected Impervious Surface (DIS
?1
Treatment Swale
?2
DryPond
t3
Storm Filter
?4
Silva Cell
?5
Ba ilter
>8
Filterra
LOAD SUPPLEMENT FORMS
:SIGNER CERTIFICATION
?7
Name and Title:
Date Stewart, Partner
?8
Organization:
LandDesi n, Inc.
?9
Street address:
223 N Graham Street
30
City, State, Zip:
Charlotte, INC 28202
31
Phone number(s):
704-333-0325
32
Email:
I dstewart0landdesign.com
Certification Statement:
I certify, under penalty of law that this Supplement-EZ form and all supporting information were prepared under my direction or supervision; that
the information provided in the form is, to the best of my knowledge and belief, true, accurate, and complete; and that the engineering plans,
specifications, operation and maintenance agreements and other supporting information are consistent with the information provided here.
69$�
Z
41,E ST01 Ilk"k,% iff C({12
Date

IKAINAUh AHhAS
f N this a high density project?
2 If so, number of drainage areas/SCMs
No
0
3
Does this project have low density areas?
Yes
4
If so, number of low density drainage areas
2
5
Is all/part of this project subject to previous rule
versions?
No
FORMS LOADED
IAINAGE AREA INFORMATION
Entire Site
LD 1
LD 2
4
Type of SCM
Grass Swales
Wet Pond
5
Total drainage area (sq ft)
6407676
6098400
309276
6
Onsite drainage area (sq ft)
4112685
3803409
309276
7
Offsite drainage area �sq ft
2294991
2294991
0
8
Total BUA in project (sq ft
986634
903870 sf
82764 sf
9permitting)
New BUA on subdivided lots (subject to
s ft
659100
604650 sf
54450 sf
4permitting)
New BUA not on subdivided lots (subject to
sf
327571
299257 sf
28314 sf
1
Offsite BUA (sq ft
69696
69696 sf
2
Breakdown of new BUA not on subdivided lots:
0
Parkin (sq ft)
0
Sidewalk (sq It
72767
66792 sf
5975 sf
Roof (sq ft)
D
Roadway s ft
254972
232387 sf
22585 sf
Future (sq ft
0
Other, please specify in the comment box
below (sq ft
0
3
New infiltrating permeable pavement on
subdivided lots (sq ft
0
4
New infiltrating permeable pavement not on
subdivided lots (sq ft
0
5permitting)
Existing BUA that will remain (not subject to
s ft
0
6
Existing BUA that is already permitted (sq ft
o
7
Existing BUA that will be removed (sq ft
0
8
Percent BUA
24% NEW BUA
24% NEW BUA
24% NEW BUA
9
Design storm inches
1.0 in
0
Design volume of SCM cu ft
7442 cf
1
1DITIONAL
2
Calculation method for design volume
INFORMATION
Please use this space to provide any additional information about the
drainage area(s):
SA/DA
e drainage areas above do not reflect the limits of the project area.
case see Sheet C205 for breakdown of proposed BUA for permitting and
eel C414 for breakdown of drainage areas used in hydraulic analysis.

it FUNlu
:::,]Drainage area number 2
21 Minimum required treatment volume cu ft 7442 cf
NERAL MDC FROM 02H .1050
3
Is the SCM sized to treat the SW from all surfaces at build -out?
Yes
4
Is the SCM located away from contaminated soils?
Yes
5
What are the side slopes of the SCM H:V ?
3:1
6
Does the SCM have retaining walls, gabion walls or other
engineered side slopes?
Na
7
Are the inlets, outlets, and receiving stream protected from erosion
10 ear storm)?
Yes
8
Is there an overflow or bypass for inflow volume in excess of the
design volume?
Yes
9
What is the method for clewatering the SCM for maintenance?
Pump referred
10
If applicable, will the SCM be cleaned out after construction?
Yes
11
Does the maintenance access comply with General MDC 8 ?
Yes
12
Does the drainage easement comply with General MDC 9 ?
Yes
13
If the SCM is on a single family lot, does (will?) the plat comply with
General MDC 10 ?
N/A
14
is there an O&M Agreement that complies with General MDC (11)?
Yes
15
Is there an O&M Plan that cam Iles with General MDC 12 ?
Yes
161
Does the SCM follow the devicespecific MDC?
Yes
17
Was the SCM designed by an NC licensedprofessional?
Yes
T POND
MDC FROM 02H .1053
18
Sizing method used
SA/DA
19
Has a stag e/stora a table been provided in the calculations?
Yes
20
Elevation of the excavated main pool depth (bottom of sediment
removal) (imsf
621.00
21
Elevation of the main pool bottom (top of sediment removal fmsl
622.00
22
Elevation of the bottom of the vegetated shelf fmsl
628.00
23
Elevation of the permanent pool fmsl
626.00
24
Elevation of the top of the vegetated shelf fmsl
629.00
25
Elevation of the temporary pool fmsl
629.62
26
Surface area of the main permanent pool (square feet
9038
27
Volume of the main permanent pool cubic feet
26997 cf
28
Average depth of the main pool feet
3.45 It
29
Average depth euation used
Equation 2
30
If using equation 3, main pool perimeter feet
31
If using equation 3, width of submerged veg. shelf feet
32
Volume of the ioreba cubic feet
4372 cf
33
Is this 15.20% of the volume in the mainpool?
Yes
34
Clean -out depth for foreba inches
48 in
35
Design volume of SCM cu ft
7442 cf
36
Is the outlet an orifice or a weir?
Orifice
37
If orifice, orifice diameter (inches)
2 in
38
If weir, weir height inches
39
if weir, weir length inches
40
Drawdown time for the temporary pool (days)
2.8
41
Are the inlet(s) and outlet located in a manner that avoids short-
circuiting?
Yes
42
Are berms or baffles provided to improve the flowpath?
Yes
43
Depth of iorebay at entrance inches
90 in
44
Depth of iorebay at exit inches
84 in
45
Does water flow out of the forebay in a non -erosive manner?
Yes
46
Width of the vegetated shelf feet
6 ft
47
Slope of vegetated shelf H:V
6:1
48
Does the orifice drawdown from below the top surface of the
permanentpool?
Yes
49
Does the pond minimize impacts to the receiving channel from the 1-
r, 24-hr storm?
Yes
50
Are fountains proposed? (If Y, please provide documentation that
MPCL91 is met.
No
51
Is a trash rack or other device provided to protect the outlet system?
Yes
52
Are the dam and embankment planted in non -clumping turfgrass?
Yes
53
Species of turf that will be used on the dam and embankment
FESCUE
54
Hasa lantin Ian been provided for the vegetated shelf?
I N
Yes
i
55
Please use this space to provide any additional information about
the wet pond(s):
a Sheet C416 for more information. Design sheets, Orifice Equation and routing
put can be found in the provided Calc Book.

LOW DENSITY
DESIGN REQUIREMENTS FOR LOW DENSITY PROJECTS FROM 02H .1003
1
Is project below density thresholds set forth in the applicable stormwater rule?
Yes
2
Does project maximize dispersed flow and minimize channelizaticn of flaw?
Yes
3
Has the use of piping been minimized per .1003(2)(c)?
Yes
4
Side slopes of the vegetated conveyances (H:V)
3 sf
5
Maximum velocity in the vegetated conveyances during the 10-year storm?
5
6
Are curb outlet swales proposed?
Yes
7
Maximum longitudinal slope of curb outlet swale(s) (%)
5%
8
Bottom width of curb outlet swale(s) (feet)
2 ft
9
Maximum side slope of curb outlet swale(s) (H:V)
3:1
10
Minimum length of curb outlet swale(s) (feet)
100 ft
11
Are treatment swales used instead of curb outlet swales?
No
12
Is stormwater released at the edge of the setback as dispersed flaw?
Yes
13
Have stormwater outlets been designed to prevent downslope erosion?
Yes
14
Are variations to rule .1003 proposed?
No
ADDITIONAL INFORMATION
15 1 Please use this space to provide any additional information about this low density project:
Curb Cuts provided where feasible. Where not ideas, minimal piping used 10 outfall into drainage swales.
®�0=41%r

�O
00
6�
'✓e
A
W
N
r
CD,D
00
r]
O�
U
A
W
N
ry.�
p
�1
CD
z
a
m
r;i
tri
m
in
tri
�
m
m
M
ram„
m
m
rn
to
t�
t
cn
�n
rn
rn
vz
cn
rn
�n
r�
N
N
N~~
ON
W
Oo
W
00
00
�D
w
00 �
Q�
U
Qi
U
Ch
U
W
N
O
D1
w
W
.-•
00
B
A
A
NM
d
w
m
i-r
00
T
O
tD
C1
V
C\
W
A
T
N
oa
A
N
U
W
00
Vl
O,
D\
10
W
A
N
A
�D
D,
O
W
�o
�'
00
�o
G
Pl
n
`6
�aaaaaaaoccN0000o.-N
C
O
O
Ln
Ln
N
N
O
Q,
U
C.
U
w
N
N
O
�l
t-'
-r,
w
O
to
w
N
@
P}
n
G'l
a
A
�D
tD
W
LA
N
U
N
0,
LAO
�-+
U
w
.A
�1
N
w
�D
C�
W
C,
w
N
O•
0,
@
PC
4l
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
Vl
CA
CA
CA
V.
[.!l
CA
CA
CA
CA
Vl
Vl
lA
Vl
CJl
Gl
LA
VI
Vl
Vl
N
�l
D7
A
'O
w
v
�o
+]
Cam+
rn
N
O
A
U
�O
00
U
oo
M
N
�D
A
00
O0
N
U
W
U
W
U
O
O
O
C
G
w
�1
O
O
O
C
a
0
vl
N
a
a
=0
a
s
@
aa0000�oca000au
oLA
o
ut
cn
vl
�n
u,
V.
vl
�A
vl
U
vl
ul
U
cn
U
U
ur
U
ul
U
_
C
W
N
N
A
N
W
A
A
�O
U
A
W
N
LD
W
O
U
O
O
CS
M
Ln
�D
�J
O
�.1
C1
U
00
W?
N
rE
�
00
LA
00
A
U
w
w
U
N
""'
fA
c0
G
LA
00
LA
w
?
�o
?
00
L„
w
-]
-
o0
W
.p.
W
CA
—
f A
Io
W
a
A
W
@
0,
o
a
o
o
4
�
'.y