SW4191201_17-116 - SuppEZ-2018_2nd Submittal_1/31/2020

SUPPLEMENT-EZ COVER PAGE
f•ORMSLOADE❑
PROJECT INFORMATION
1
jProject Name
Lewisville Middle School
i 66.21
2
lProiect Area ac
3
Coastal Wetland Area ac
0
1.28
4
Surface Water AreaLac)
5
Is this project H' h or Low Density?
Hi h
6
Does this project use an off -site SCM?
No
COMPLIANCE WIT..'02H .1 _ S 4}.
f ve etated setbacks rovided feet
30
T7d
ve etated setback remain ve etated?
Yes
otherthat as listed in ,1003 4 c-d out of the setback?
Yes
mbank stabilization proposed on this project?
Yes
NUMBER
AND TYPE OF SCMs:
11
Infiltration S stem
0
12
Bioretention Cell
0
13
Wet Pond
1
14
Stormwater Wetland
1
15
Permeable Pavement
0
16
Sand Filter
_
0
17
Rainwater Harvesting RWH
0
18
Green Roof
0
19
Level S reader -Filter Stri LS-FS
0
20
Disconnected Impervious Surface DIS
0
21
Treatment Swale
0
22
IDry Pond
_
0
23
StormFilter
0
24
Silva Cell
0
25
Bayfilter
0
26
Filterra
0
FORMS LOADED
DESIGNER CERTIFICATION
27
Name and Title:
Kenneth Lorin - Principal
28
Organization:
CLH Design PA
29
Street address:
400 Regency Forest Drive. Suite 120
30
City, State, Zip:
Cary, NC
31
Phone numbers :
919-319-6716
32
Email:
27518
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.
'fes IL
N r.
SEAL
23953 -
P
nature of Designer
Date
/z- 3 49

DRAINAGE AREAS
1
Is this a high density project?
Yes
2
If so, number of drainage areas/SCMs
2
3
Is all/part of this project subject to previous rule
versions?
No
FORMS LOADED
DRAIN A AREA INFORMATIONl
4 T pe of SCM
Entire Site
N/A
1
WET POND
2
WETLAND
5
Total BUA in promect (sq ft
382098 sf
349119 sf
32979 sf
6permitting)
New BUA on subdivided lots (subject to
s ft
N/A
N/A
N/A
7permitting)
New BUA outside of subdivided lots (subject to
sf
376078 sf
349119 sf
32979 sf
8
Offsite - total area (sq ft
0
19602 sf
0
9
Offsite BUA (sq ft
0
0
0
10
Breakdown of new BUA outside subdivided lots:
Parking (sq ft
105490 sf
105490 sf
0
Sidewalk (sq ft
25206 sf
23189 sf
2017 sf
Roof (sq ft
62264 sf
62264 sf
0
Roadway s ft
121582 sf
93234 sf
28348 sf
Future (sq ft
11326 sf
8712 sf
2614 sf
Other, please specify in the comment box
below (sq ft
50210 sf
56230 sf
0
11
New infiltrating permeable pavement on
subdivided lots (sq ft
0
0
0
12
New infiltrating permeable pavement outside of
subdivided lots (sq ft
0
0
0
13permitting)
Exisitng BUA that will remain (not subject to
s ft
6020 sf
sf
0
14
Existina BUA that is already permitted (sq ft
0
0
0
15
Existing BUA that will be removed (sq ft
24870 sf
23164 sf
300 sf
16
Percent BUA
14°/
43°/
37°/
17
Design storm inches
N/A
1 in
1 in
18
Design volume of SCM cu ft
N/A
29521 cf
2822 cf
19
Calculation method for design volume
N/A
HRT
SIMPLE
ADDITIONAL INFORMATION
20
Please use this space to provide any additional information about the
drainage area(s):
"Other" BUA includes gravel fire lane and "rock dust" track

WET POND
1 Drainage area number
2 Design volume of SCM (cu ft)
GENERAL MDC FROM 02H .1050 116
31 Is the SCM sized to treat the SW from all surfaces at build -out?
1
29521 cf
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?
No
7
Are the inlets, outlets, and receiving stream protected from erosion
(10-year storm)?
Yes
8
Is there an overflow or bypass for inflow volume in excess of the
design volume?
What is the method for dewatering the SCM for maintenance?
Yes
9
Drawdown Orifice
10
If applicable, will the SCM be cleaned out after construction?
Yes
111
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)?
Is there an O&M Agreement that complies with General MDC (11)?
No
141
Yes
15
Is there an O&M Plan that complies with General MDC (12)?
Yes
16
Does the SCM follow the device specific MDC?
Yes
17
Was the SCM designed by an NC licensed professional?
Yes
WET POND MDC FROM 02H .1053
18
Method used
HRT
19
Has a stage/storage table been provided in the calculations?
Yes
20
Elevation of the excavated main pool depth (bottom of sediment
removal) (fmsl)
822.50
21
Elevation of the main pool bottom -(top of sediment removal) (fmsl)
823.00
22
Elevation of the bottom of the vegetated shelf (fmsl)
826.00
23
Elevation of the permanent pool (fmsl)
826.50
24J
Elevation of the top of the vegetated shelf (fmsl)
827.00
25
Elevation of the temporary pool (fmsl)
828.50
26
Surface area of the main permanent pool (square feet)
30040:1
27
Volume of the main permanent pool (cubic feet)
87015 cf
28
Average depth of the main pool (feet)
3.13 ft
29
Average depth equation used
Equation 3
30
If using equation 3, main pool perimeter (feet)
796.0 ft
31
If using equation 3, width of submerged veg. shelf (feet)
3.0 ft
32
Volume of the forebay (cubic feet)
14313 cf
33
Is this 15-20% of the volume in the main pool?
Yes
34
Clean -out depth for forebay (inches)
6 in
35
Design volume of SCM (cu ft)
29521 cf
36
Is the outlet an orifice or a weir?
Orifice
37
If orifice, orifice diameter (inches)
If weir, weir height (inches)
If weir, weir length (inches)
Drawdown time for the temporary pool (days)
Are the inlet(s) and outlet located in a manner that avoids short-
circuiting?
3 in
38
N/A
39
N/A
40
3.8
41
Yes
et PUjAre
berms or baffles provided to improve the flow patW
No
9:11 AM 1/31/2020

WET POND
43
Depth of forebay at entrance (inches)
60 in
44
Depth of forebay at exit (inches)
54 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)
10:1
48
Does the orifice drawdown from below the top surface of the
permanent pool?
Yes
49
Does the pond minimize impacts to the receiving channel from the 1-
yr, 24-hr storm?
Yes
50
Are fountains proposed? (If Y, please provide documentation that
MDC(9) is met.)
Is a trash rack or other device provided to protect the outlet system?
No
51
Yes
52
Are the dam and embankment planted in non -clumping turf grass?
Yes
53
Species of turf that will be used on the dam and embankment
No Mow Seed Mix
541
Has a planting plan been provided for the vegetated shelf?
Yes
ADDITIONAL
INFORMATION
Please use this space to provide any additional information about the
55 wet pond(s):
Wet Pond 4 9:11 AM 1/31/2020

STORMWATER WETLAND
VEN
1 Drainage area number
2 Design volume of SCM (cu ft)
ERAL MDC FROM 02H .1050
2
2822 cf
3
1 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?
No
Yes
Yes
Drawdown Orifice
7
Are the inlets, outlets, and receiving stream protected from erosion (10-year
storm)?
Is there an overflow or bypass for inflow volume in excess of the design volume?
8
9
What is the method for dewatering the SCM for maintenance?\
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)?
No
14
Is there an O&M Agreement that complies with General MDC (11)?
Yes
15
Is there an O&M Plan that complies with General MDC (12)?
Yes
16
Does the SCM follow the device specific MDC?
Yes
17
Was the SCM designed by an NC licensed professional?
Yes
STORMWATER WETLAND MDC FROM 02H .1054
18
Are the inlet(s) and outlet located in a manner that avoids short-circuiting?
Yes
19
Are berms or baffles provided to improve the flow path?
Yes
20
IDoes the orifice drawdown from below the top surface of the permanent pool?
I Yes
21
Does the wetland minimize impacts to the receiving channel from the 1-yr, 24-hr
storm?
Yes
22
Is a trash rack or other device provided to protect the outlet system?
Yes
j Elevations
23
24
25
26
27
28
29
Elevation, peak attenuation above temporary pool (if applicable) (fmsl)
Elevation, temporary pool (top of the temporary inundation zone) (fmsl)
813.00
Elevation, permanent pool (top of the shallow water zone) (fmsl)
812.00
Elevation, bottom of shallow water zone (fmsl)
811.50
Elevation, bottom of forebay deep pool at deepest point (at forebay entrance)
(fmsl)
810.00
810.00
Elevation, bottom of forebay deep pool at shallowest point (at forebay exit) (fmsl)
Elevation, bottom of non-forebay deep pool at deepest point (fmsl)
810.00
Planting Zones
30
Area, total surface area of the SW wetland at temporary pool elev. (sq ft)
4,670.00
31
Area, temporary inundation zone at temporary pool elev. (sq ft)
1,710.00
32
Area, shallow water zone at temporary pool elev. (sq ft)
1,690.00
33
Area, forebay at temporary ool elev. (sq ft
680.00
34
Area, non-forebay deep pool at temporary ool elev .(sq ft
590.00
35
Percent area provided, temporary inundation zone (should be 30-45%)
37%
36
Percent area provided, shallow water zone should be 35-45%
36%
37
Percent area provided, deep pool (forebay) (should be 10-15%)
15%
$Bin
ercent area provided, deep pool(non-forebay) should be 5-15%
13% 9:
1 AM 1/31/2020

STORMWATER WETLAND
Depths and Outlet
39
m
m
Peak attenuation depth above temporary inundation zone (inches)
11 in
Temporar iy nundation zone depth (temporary pool to permanent pool) (inches)
Shallow water zone depth (permanent pool to bottom of wetland) (inches)
12 in
6 in
Depth, forebay at entrance (permanent pool to bottom of forebay entrance)
(inches)
Depth, forebay at exit(permanent pool to bottom of forebay exit inches
30 in
24 in
Depth, non-forebay deep pools(permanent pool to deep pool bottom inches
24 in
If there is an orifice, diameter (inches)
1 in
If there is a weir, weir height inches
12 in
If there is a weir, weir length (inches)
12 in
Drawdown time for the temporary pool (days)
2.2
Soil and Plants
49
Soil amendment depth (inches)
4 in
50
Has a soil amendment specification been provided?
Yes
51
Hasa landscaping plan that meets SW Wetland MDC (12) been provided?
Yes
52
1 Number of plants per 200 square feet (#) in the shallow water zone:
Does the temporary inundation zone planting comply with SW Wetland MDC
53
(14)?
Yes
Are the dam structure and temporary fill slopes planted in non -clumping
54
turfgrass?
Yes
55
lWill cattails be planted in the wetland.
No
ADDITIONAL INFORMATION
iPlease use this space to provide any additional information about the
56
stormwater wetland(s):
Wetland 6 9:11 AM 1/31/2020