SW4191201_17-116 - SuppEZ_combined_3/26/2020

SUPPLEMENT-EZ COVER PAGE
FORMSLOADED
(PROJECT
INFORMATION
1
'Project Name
Project Area ac
Lewisville Middle School
2
66.21
3
Coastal Wetland Area (ac)
0
4
Surface Water Area ac
1.P8
5
Is this project High or Low Density?
Hi h
6
Does this project use an off -site SCM?
No
COMPLIANCE WITH 02H .1003(4)
7
'Width of vegetated setbacks provided (feet)
30
-B
'Will the vegetated setback remain vegetated?
Yes
9
Is BUA other that as listed in .1 0034 c-d) out of the setback?
Yes
10
Is streambank stabilization proposed on this project?
Yes
NUMBER AND TYPE OF SCMs:
11
Infiltration System
0
0
1
12
Bioretention Cell
13
'Wet Pond
14
;Stormwater Wetland
1
15
(Permeable Pavement
0
16
Sand Filter
0
17
Rainwater Harvesting RWH
0
18
Green Roof
0
19
LevBl $ ender -Filter Strip (IS-FS
0
20
Disconnected Impervious Surface (DIS
0
21
Treatment Swale
0
22
Dry Pond
0
23
:Storm Fi (ter
0
24
;Silva Cell
0
25
lBayfilter
0
26
Filterra
0
FEMMS LQADED
DESIGNER
CERTIFICATION
27
Name and Title:
Kenneth Lorin - Principal
28
ar anization:
CLH Desi n PA
29
.Street address:
400 Regency Forest Drive. Smle 120
30
City, State, Zip:
Cary, INC
31
(Phone numbers :
919-319-6716
32
Email;
27518
canillaalron slalienlcilt,
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.
SCAB.
23953
Seal
hd ure of Designer���
s -ZIj,,- 14M o
Date

DRAINAGE AREAS
1
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
DRAINA FORMATION
Entire Site
1
2
4
Type of SCM
N/A
WET POND
WETLAND
5
Total BUA in project (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
351208 sf
325955 sf
32679 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
58398 sf
58564 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
29206 sf
36766 sf
-300 sf
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
30890 sf
23164 sf
300 sf
14
Existing BUA that is already permitted (sq ft
0
0
0
15
Existing BUA that will be removed (sq ft
0
0
0
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
SIMPLE
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

STORMWATER WETLAND
1 Drainage area number
2 Design volume of SCM (cu ft)
GENERAL MDC FROM 02H .1050
2 I 2822 cf
3
Is the SCM sized to treat the SW from all surfaces at build -out?
Is the SCM located away from contaminated soils?
Yes
4
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?
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?
No
7
Yes
Yes
Drawdown Orifice
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
ISTORMWATER 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
1 Does the orifice drawdown from below the top surface of the permanent pool?
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
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
810.50
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
Plantina 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 . s 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 1 Percent area
area
forebay) (should be 10-15%)
non-forebay) (shouldl be 5-15%
15%
13%
5:04 PM 3/23/2020

STORMWATER WETLAND
I Depths and Outlet
39
40
Peak attenuation depth above temporary inundation zone (inches)
Temporary inundation zone depth (temporary pool to permanent pool) (inches)
Shallow water zone depth (permanent pool to bottom of wetland inches
11 in
12 in
41
6 in
42
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
43
24 in
44
1 Depth, non-forebay deep pools(permanent pool to deep pool bottom inches
24 in
45
If there is an orifice, diameter inches
1 in
46
If there is a weir, weir height inches
12 in
47
If there is a weir, weir length inches
12 in
48
Drawdown time for the temporary pool (days)
2.2
ill and Plants
49 Soil amendment depth (inches)
50 Has a soil amendment specification been provided?
51 Hasa landscaping plan that meets SW Wetland MDC (12) been provided?
52 1 Number of plants per 200 square feet (#) in the shallow water zone:
Does the temporary inundation zone planting comply with SW Wetland MC
53 (14)?
Are the dam structure and temporary fill slopes planted in non -clumping
54 turfgrass?
55 Will cattails be planted in the wetland?
DDITIONAL INFORMATION
Please use this space to provide any additional information about the
56 stormwater wetland(s):
Wetland 2 5:04 PM 3/23/2020

WET POND
Drainage area number
volume of SCM (cu ft)
H_..
GERAL MDC FROM 02H .1050
3 Is the SCM sized to treat the SW from all surfaces at build -out?
1Design
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
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)?
Is there an O&M Agreement that complies with General MDC (11)?
No
14
Yes
Yes
Yes
15
Is there an O&M Plan that complies with General MDC (12)?
16
Does the SCM follow the device specific MDC?
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
24
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)
54 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?
Are berms or baffles provided to improve the flow path?
3 in
38
N/A
39
N/A
40
3.8
41
Yes
et
No
5:04 PM 3/23/2020

WET POND
43
Depth of forebay at entrance (inches)
54 in
44
Depth of forebay at exit (inches)
48 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
INFORMATION
Please use this space to provide any additional information about the
wet pond(s):
ADDITIONAL
55
Wet Pond 2 5:04 PM 3/23/2020