SW4200501_2020-05-28-Signed Supplemental_5/28/2020

SUPPLEMENT-EZ COVER PAGE
FORMS LOADED
PROJECT INFORMATION
Lewisville Middle School
1
Project Name
2
Project Area ac
64.93
3
Coastal Wetland Area ac
0
4
Surface Water Area ac
1.28
5
Is this project High or Low Density?
High
6
IDoes this project use an off -site SCM?
No
COMPLIANCE WITH 02H .1003(4)
7
Width of vegetated setbacks provided feet
30
8
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
Bioretention Cell
0
12
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 Spreader -Filter Strip LS-FS
0
20
Disconnected Impervious Surface (DIS)
0
21
Treatment Swale
0
22
Da 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
CLH Design PA
28
Organization:
29
Street address:
400 Regency Forest Drive, Suite 120
30
City, State, Zip.:
Cary, NC
31
Phone numbers :
919-319-6716
32
Email:
27518
Corlificalion 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.
. Q,
SEAL —
23953
r'e•�f �'+1 i A iiyVV�'``''k�.
Signature of Designer
Date

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
DRAINAGE AREA INFORMATION
Entire Site
1
2
4
Type of SCM
N/A
WET POND
WETLAND
5
Total BUA in project (sq ft)
393224 sf
352819 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
362334 sf
329655 sf
32679 sf
8
Offsite - total area (sq ft
0
19602 sf
0
9
Offsite BUA (sq ft)
0
19602 sf
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
36466 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
13
Exisitng BUA that will remain (not subject to
ermitting) (sq 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
14.2%
45.4%
36.8%
17
Design storm inches
N/A
1 in
1 in
18
Design volume of SCM cu ft
N/A
30991 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
1drainage area(s):
"Other" BUA includes gravel fire lane and 'rock dust' track; in -lieu of
aquiring an agreement with offsite parcels for future BUA, we have allotted
100% of the offsite (0.45 ac - 19602 sf) to be impervious, this area has been
added to the "future" BUA section of the wet pond.

WET POND
area number
Design volume of SCM (cu ft)
AL MDC FROM 02H .1050
31
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
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?
Yes
9
What is the method for dewatering the SCM for maintenance?
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)?
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
161
Does the SCM follow the device specific MDC?
Yes
17
Was the SCM designed by an NC licensed professional?
Yes
IWET 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)
827.31
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 It
29
Average depth equation used
Equation 3
30
If using equation 3, main pool perimeter (feet)
796.0 It
31
If using equation 3, width of submerged veg. shelf (feet)
3.0 It
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)
30991 cf
36
Is the outlet an orifice or a weir?
Orifice
37
If orifice, orifice diameter (inches)
2.5
38
If weir, weir height (inches)
N/A
39
If weir, weir length (inches)
N/A
40
Drawdown time for the temporary pool (days)
4.5
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 flow path?
No
43
Depth of forebay at entrance (inches)
66 in
44
Depth of forebay at exit (inches)
60 in
45
Does water flow out of the forebay in a non -erosive manner?
Yes
46
Width of the vegetated shelf (feet)
6 It
47
Slope of vegetated shelf (H:V)
6:1
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.)
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 turf grass?
Yes
53
Species of turf that will be used on the dam and embankment
No Mow Seed Mix
b4l
Has a planting plan been provided or the vegetate shelf?
es
ADDITIONAL INFORMATION
55
Please use this space to provide any additional information about
the wet pond(s):
Wet Pond 3 2:24 PM 5/28/2020

STORMWATER WETLAND
1 1Drainage area number 2
2 IDesign volume of SCM (cuff) 2822 cf
GENERAL MDC FROM 02H .1050 - -
3 jIstheSCMsized to treat the SW from all surfaces at build -out? Yes
4 Ils the SCM located away from contaminated soils? Yes
5 1 What are the side slopes of the SCM (H:V)? 3:1
Does the SCM have retaininq walls, gabion walls or other engineered side
6
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?
Yes
9
What is the method for dewatering the SCM for maintenance?)
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)?
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
fie JGM aeSlgneo Dy an NU iicensea pri
TER 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
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)
814.13
Elevation, temporary pool (top of the temporary inundation zone) (fmsl)
812.71
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)
809.00
Elevation, bottom of forebay deep pool at shallowest point (at forebay exit)
(fmsl)
1 809.50
Elevation, bottom of non-forebay deep pool at deepest point (fmsl)
809.50
Plantina Zones
30
Area, total surface area of the SW wetland at temporary pool elev. (sq ft)
4,274.00
31
Area, temporary inundation zone at temporary pool elev. (sq ft)
1,681.00
32
Area, shallow water zone at temporary pool elev. (sq ft)
1,624.00
33
Area, foreba at temporary ool elev. (sq ft
494.00
34
Area, non-forebay deep pool at temporary ool elev .(sq ft
475.00
35
Percent area provided, temporary inundation zone should be 30-45%
39%
36
Percent area provided, shallow water zone should be 35-45 %
38%
37
Percent areaprovided, deeppool (forebay)should be 10-15 %
12%
38
Percent area provided, deep pool(non-forebay) should be 5-15 %
11 %
Depths and Outlet
39
40
41
42
43
44
45
46
47
48
Peak attenuation depth above temporary inundation zone (inches)
17.04
iTemporary inundation zone depth (temporary ool to permanentpool) inches
8.52
Shallow water zone depth(permanent pool to bottom of wetland inches
6 in
Depth, forebay at entrance (permanent pool to bottom of forebay entrance)
inches
36in
Depth, forebay at exit(permanent pool to bottom of forebay exit inches
30 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)
2.6
Soil and Plants
49
Soil amendment depth (inches)
12 in
50
Has a soil amendment specification been provided?
Yes
51
Has a landscaping plan that meets SW Wetland MDC (12) been provided?
Yes
52
Number of plants per 200 square feet (#) in the shallow water zone:
gn
53
Does the temporary inundation zone planting comply with SW Wetland MDC
(14)?
Yes
54
Are the dam structure and temporary fill slopes planted in non -clumping
turfgrass?
Yes
55
lWill cattails bepane in thewe an
o
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
56 stormwater wetland(s):
Line 52, 50 plants for 200 SF in shallow water zone (line 52 will not let user
type anything)
Wetland 4 2:24 PM 5/28/2020