SW6231002_Supplement-EZ Form_20240906

SUPPLEMENT-EZ COVER PAGE
FORMS LOADED
PROJECT INFORMATION
1 'Project Name Serenity-Phases 8&9
2 Project Area(ac) 155.11
3 Coastal Wetland Area(ac) 0
4 Surface Water Area(ac) 1.61
5 Is this project High or Low Density? Both High and Low Density
6 Does this project use an off-site SCM? No
COMPLIANCE WITH 02H.1003(4)
7 Width of vegetated setbacks provided(feet) _ 30(intermittent streams)&100(perennial streams)
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)? _ N/A
10 Is streambank stabilization proposed on this project? No
NUMBER AND TYPE OF SCMs:
11 !Infiltration System
12 Bioretention Cell
13 Wet Pond 6
14 Stormwater Wetland
15 Permeable Pavement
16 Sand Filter
17 Rainwater Harvesting(RWH)
18 Green Roof
19 Level Spreader-Filter Strip(LS-FS)
20 Disconnected Impervious Surface(DIS)
21 Treatment Swale
22 Dry Pond
23 StormFilter
24 Silva Cell
25 Bayfilter
26 Filterra 2
FORMS LOADED
DESIGNER CERTIFICATION
27 'Name and Title: Brandon Miller,PE-Project Manager
28 Organization: WithersRavenel,Inc.
29 Street address: 115 MacKenan Drive
30 City,State,Zip: Cary,NC 27511
31 Phone number(s): 919.469.3340
32 Email: [e-mail]
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.
Signed by:
Designer
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9/4/2024

Serenity-Phases 8 9
DRAINAGE AREAS
1 Is this a high density project? Yes
2 If so,number of drainage areas/SCMs 8
3 Does this project have low density areas? Yes
4 If so,number of low density drainage areas 1
Is all/part of this project subject to previous rule
5 versions? No
FORMS LOADED
DRAINAGE AREA INFORMATION Entire Site 1 2 3
4 Type of SCM Wet Pond(SCM 6) Wet Pond(SCM 7) Wet Pond(SCM 8)
5 Total drainage area(sq ft) 6,686,642 515,017 _ 1,098,629 388,130
6 Onsite drainage area(sq ft) 6,686,642 515,017 1,098,629 388,130
7 Offsite drainage area(sq ft) 0 0 0 0
8 Total BUA in project(sq ft) 2,350,384 271,228 550,820 191,558
New BUA on subdivided lots(subject to permitting)
9 (sq ft) 1,470,050 171,200 347,983 129,425
New BUA not on subdivided lots(subject to
10 permitting)(sf) 880,334 100,028 202,837 62,133
11 Offsite BUA(sq ft)
12 Breakdown of new BUA not on subdivided lots:
-Parking(sq ft)
-Sidewalk(sq ft) 164,472 19,090 40,794 8,891
-Roof(sq ft)
-Roadway(sq ft) 543,724 60,938 132,043 28,242
-Future(sq ft)
-Other,please specify in the comment box
below(sq ft) 172,137 20,000 30,000 25,000
New infiltrating permeable pavement on
13 subdivided lots(sq ft)
New infiltrating permeable pavement not on
14 subdivided lots(sq ft)
Existing BUA that will remain(not subject to
15 permitting)(sq ft)
16 Existing BUA that is already permitted(sq ft)
17 Existing BUA that will be removed(sq ft)
18 Percent BUA 35% 53% 50% 49%
19 Design storm(inches) 1.0 in 1.0 in 1.0 in
20 Design volume of SCM(cu ft) 35894 cf 76772 cf 23863 cf
21 Calculation method for design volume Simple Simple Simple
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
22 drainage area(s):
OTHER'BUA ALLOTED TO PARKS/AMENITIES.AN ADDITIONAL 3,637-SF
OF BUA IS ALLOTTED TO THE PUMP STATION IN THE SCM 11
DRAINAGE AREA'OTHER'
Drainage Areas 9/4/2024

Serenity-Phases 8 9
DRAINAGE AREAS
1 Is this a high density project? Yes
2 If so,number of drainage areas/SCMs 8
3 Does this project have low density areas? Yes
4 If so,number of low density drainage areas 1
Is all/part of this project subject to previous rule
5 versions? No
FORMS LOADED
DRAINAGE AREA INFORMATION Entire Site 4 5 6
Wet Pond(SCM
4 Type of SCM Wet Pond(SCM 9) Wet Pond SCM 10) 11)
5 Total drainage area(sq ft) 6,686,642 681,171 805,662 511,235
6 Onsite drainage area(sq ft) 6,686,642 681,171 805,662 511,235
7 Offsite drainage area(sq ft) 0 0 0 0
8 Total BUA in project(sq ft) 2,350,384 354,051 434,718 284,790
New BUA on subdivided lots(subject to permitting)
9 (sq ft) 1,470,050 216,875 255,475 145,400
New BUA not on subdivided lots(subject to
10 permitting)(sf) 880,334 137,176 179,243 139,390
11 Offsite BUA(sq ft)
12 Breakdown of new BUA not on subdivided lots:
-Parking(sq ft)
-Sidewalk(sq ft) 164,472 26,731 31,630 24,337
-Roof(sq ft)
-Roadway(sq ft) 543,724 90,444 102,613 82,916
-Future(sq ft)
-Other,please specify in the comment box
below(sq ft) 172,137 20,000 45,000 32,137
New infiltrating permeable pavement on
13 subdivided lots(sq ft)
New infiltrating permeable pavement not on
14 subdivided lots(sq ft)
Existing BUA that will remain(not subject to
15 permitting)(sq ft)
16 Existing BUA that is already permitted(sq ft)
17 Existing BUA that will be removed(sq ft)
18 Percent BUA 35% 52% 54% 56%
19 Design storm(inches) 1.0 in 1.0 in 1.0 in
20 Design volume of SCM(cu ft) 42145 cf 44087 cf 25214 cf
21 Calculation method for design volume Simple Simple Simple
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
22 drainage area(s):
OTHER'BUA ALLOTED TO PARKS/AMENITIES.AN ADDITIONAL 3,637-SF
OF BUA IS ALLOTTED TO THE PUMP STATION IN THE SCM 11
DRAINAGE AREA'OTHER'
Drainage Areas 9/4/2024

Serenity-Phases 8 9
DRAINAGE AREAS
1 Is this a high density project? Yes
2 If so,number of drainage areas/SCMs 8
3 Does this project have low density areas? Yes
4 If so,number of low density drainage areas 1
Is all/part of this project subject to previous rule
5 versions? No
FORMS LOADED
DRAINAGE AREA INFORMATION Entire Site 7 8 LD 1
4 Type of SCM Filterra(SCM 12) Filterra(SCM 13) Low Density
5 Total drainage area(sq ft) 6,686,642 61,892 63008 2561898.003
6 Onsite drainage area(sq ft) 6,686,642 61,892 63,008 2561898.003
7 Offsite drainage area(sq ft) 0 0 0 0
8 Total BUA in project(sq ft) 2,350,384 40,541 40521 sf 182157 sf
New BUA on subdivided lots(subject to permitting)
9 (sq ft) 1,470,050 14,550 9333 sf 179808 sf
New BUA not on subdivided lots(subject to
10 permitting)(sf) 880,334 25,991 31,188 2,349
11 Offsite BUA(sq ft)
12 Breakdown of new BUA not on subdivided lots:
-Parking(sq ft)
-Sidewalk(sq ft) 164,472 5,935 6270 sf 795 sf
-Roof(sq ft)
-Roadway(sq ft) 543,724 20,057 24918 sf 1553 sf
-Future(sq ft)
-Other,please specify in the comment box
below(sq ft) 172,137
New infiltrating permeable pavement on
13 subdivided lots(sq ft)
New infiltrating permeable pavement not on
14 subdivided lots(sq ft)
Existing BUA that will remain(not subject to
15 permitting)(sq ft)
16 Existing BUA that is already permitted(sq ft)
17 Existing BUA that will be removed(sq ft)
18 Percent BUA 35% 66% 64% 7%
19 Design storm(inches) 1.0 in 1.0 in N/A
20 Design volume of SCM(cu ft) N/A N/A N/A
21 Calculation method for design volume Simple Simple N/A
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
22 drainage area(s):
OTHER'BUA ALLOTED TO PARKS/AMENITIES.AN ADDITIONAL 3,637-SF
OF BUA IS ALLOTTED TO THE PUMP STATION IN THE SCM 11
DRAINAGE AREA'OTHER'
Drainage Areas 9/4/2024

Serenity-Phases 8 9
WET POND
1
_ 2 Minimum requi required treatment volume(Cu ft 22499cf I 45905 cf er SCM SCM 7
I 15992cf SCM I 29399cf SCM I 35962 SCM 10 0
I 23551SCM 1of
GENERAL MDC FROM 02H.1050
3 Is the SCM sized to treat the SW from all surfaces at build-out? Yes Yes Yes Yes Yes Yes
4 Is the SCM located away from contaminated soils? _ Yes Yes Yes Yes Yes Yes
5 What are the side slopes of the SCM(H:V)? 3:1 3:1 3:1 3:1 3:1 3:1
6 Does the SCM have retaining walls,gabion walls or other engineered No No No No No No
side slopes?
7 Are the inlets,outlets,and receiving stream protected from erosion Yes Yes Yes Yes Yes Yes
(10-year storm)? -
8 Is there an overflow or bypass for inflow volume in excess of the Yes Yes Yes Yes Yes Yes
design volume?
-
9 What is the method for dewatering the SCM for maintenance? Drawdown Orifice Drawdown Orifice Drawdown Orifice Drawdown Orifice Drawdown Orifice Drawdown Orifice
10 If applicable,will the SCM be cleaned out after construction? _ _ Yes Yes Yes - Yes Yes Yes
11 Does the maintenance access comply with General MDC(8)? Yes Yes Yes Yes Yes Yes
12 Does the drainage easement comply with General MDC(9)? Yes Yes Yes Yes Yes Yes
13 If the SCM is on a single family lot,does(will?)the plat comply with N/A N/A N/A N/A N/A N/A
General MDC(10)?
14 Is there an O&M Agreement that complies with General MDC(11)? Yes Yes Yes Yes Yes Yes
15 Is there an O&M Plan that complies with General MDC(12)? Yes Yes Yes Yes Yes Yes
16 Does the SCM follow the device specific MDC? Yes Yes Yes Yes Yes Yes
_ 17 Was the SCM designed b an NC licensed rofessional? Yes I Yes Yes Yes Yes Yes
WET POND MDC FROM 02H.10
18 Sizing method used SA/DA I SA/DA SA/DA SA/DA SA/DA SA/DA
19 Has a stage/storage table been provided in the calculations? Yes Yes Yes Yes Yes Yes
20 Elevation of the excavated main pool depth(bottom of sediment 327.00 324.00 348.00 358.00 366.00 372.00
removal)(fmsl)
21 Elevation of the main pool bottom(top of sediment removal)(fmsl) 328.00 325.00 349.00 359.00 367.00 373.00
22 Elevation of the bottom of the vegetated shelf(fmsl) 332.00 328.00 352.00 362.00 _ 370.00 376.00
23 Elevation of the permanent pool(fmsl) 332.50 328.50 352.50 362.50 370.50 375.50
24 Elevation of the top of the vegetated shelf(fmsl) 333.00 329.00 353.00 363.00 371.00 377.00
25 Elevation of the temporary pool(fmsl) _ 335.00 331.00 354.00 364.50 _ 372.25 377.50
26 Surface area of the main permanent pool(square feet) _ 8931 21078 10655 14685 _ 18135 8122
27 Volume of the main permanent pool(cubic feet) 30626 cf 62985 cf 29923 cf 42374 cf 53625 cf 31450 cf
28 Average depth of the main pool(feet) 3.50 ft 3.00 ft 3.00 ft 3.00 ft 3.00 ft 3.00 ft
29 Average depth equation used _ Equation 3 Equation 3 Equation 3 Equation 3 Equation 3 Equation 3
30 If using equation 3,main pool perimeter(feet) _ 420.0 ft 669.0 ft 413.0 ft 520.0 ft _ 600.0 ft 465.0 ft
31 If using equation 3,width of submerged veg.shelf(feet) 3.0 ft 3.0 ft 3.0 ft 3.0 ft 3.0 ft 3.0 ft
32 Volume of the forebay(cubic feet) 6059 cf 9977 cf 5294 cf 8499 cf 9733 cf 4814 cf
33 Is this 15-20%of the volume in the main pool? _ Yes Yes Yes Yes _ Yes Yes
34 Clean-out depth for forebay(inches) _ 12 in 12 in 12 in 12 in _ 12 in 12 in
35 Design volume of SCM(cu ft) 35894 cf 76772 cf 23863 cf 42145 cf 44087 cf 25214 cf
36 Is the outlet an orifice or a weir? Orifice Orifice Orifice Orifice Orifice Orifice
37 If orifice,orifice diameter(inches) _ 2.50 in 2.75 in 2.00 in 3.00 in 3.25 in 2.50 in
38 If weir,weir height(inches) _
39 If weir,weir length(inches)
40 Drawdown time for the temporary pool(days) 2.8 4.9 4.5 2.5 2.4 2.2
41 Are the inlet(s)and outlet located in a manner that avoids short- Yes Yes Yes Yes Yes Yes
circuiting? _
42 Are berms or baffles provided to improve the flow path? No Yes No No No No
43 Depth of forebay at entrance(inches) 60 in 60 in 60 in 60 in 60 in 72 in
44 Depth of forebay at exit(inches) 54 in 54 in 54 in 54 in 54 in 66 in
45 Does water flow out of the forebay in a non-erosive manner? Yes Yes Yes Yes Yes Yes
46 Width of the vegetated shelf(feet) 6 ft 6 ft 6 ft 6 ft 6 ft 6 ft_
47 Slope of vegetated shelf(H:V) 6:1 6:1 6:1 6:1 6:1 6:1
48 Does the orifice drawdown from below the top surface of the Yes Yes Yes Yes Yes Yes
permanent pool?
49 Does the pond minimize impacts to the receiving channel from the 1- Yes Yes Yes Yes Yes Yes
yr,24-hr storm?
50 Are fountains proposed?(If Y,please provide documentation that No No No No No No
MDC(9)is met.)
51 Is a trash rack or other device provided to protect the outlet system? Yes Yes Yes Yes Yes Yes
52 Are the dam and embankment planted in non-clumping turf grass? Yes Yes Yes Yes Yes Yes
53 Species of turf that will be used on the dam and embankment Centipede Centipede Centipede Centipede Centipede Centipede
54 Has a planting plan been provided for the vegetated shelf? Yes Yes Yes Yes Yes Yes
ADDITIONAL INFORMATION
55 Please use this space to provide any additional information about the
wet pond(s):
2

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 channelization of flow? Yes
3 Has the use of piping been minimized per.1003(2)(c)? Yes
4 Side slopes of the vegetated conveyances(H:V) 3
5 Maximum velocity in the vegetated conveyances during the 10-year storm?
6 Are curb outlet swales proposed? No
7 Maximum longitudinal slope of curb outlet swale(s)(%)
8 Bottom width of curb outlet swale(s)(feet)
9 Maximum side slope of curb outlet swale(s)(H:V)
10 Minimum length of curb outlet swale(s)(feet)
11 Are treatment swales used instead of curb outlet swales? No
12 Is stormwater released at the edge of the setback as dispersed flow? Yes
13 Have stormwater outlets been designed to prevent downslope erosion? Yes
14 Are variations to rule.1003 proposed? No
ADDITIONAL INFORMATION
15 Please use this space to provide any additional information about this low density project:
Drainage Pervious
Swale Area BUA area C Q Slope V,iiow V., Flow depth
(ac) (ac) (acl (cfs) (%) (fps) (fps) (ft)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
2

FILTERRA BIORETENTION
1 Drainage area number SCM 12 I SCM 13
2 Minimum required treatment volume(cu ft) _ 1828 2448
GENERAL MDC FROM 02H.1050
3 Is the SCM sized to treat the SW from all surfaces at build-out? Yes Yes
4 Is the SCM located away from contaminated soils? No No
5 What are the side slopes of the SCM(H:V)? N/A N/A
6 Does the SCM have retaining walls,gabion walls or other N/A N/A
engineered side slopes?
7 Are the inlets,outlets,and receiving stream protected from erosion Yes Yes
(10-year storm)?
8 Is there an overflow or bypass for inflow volume in excess of the Yes Yes
design volume?
9 What is the method for dewatering the SCM for maintenance? Pump Pump
10 If applicable,will the SCM be cleaned out after construction? _ Yes Yes
11 Does the maintenance access comply with General MDC(8)? Yes Yes
12 Does the drainage easement comply with General MDC(9)? Yes Yes
If the SCM is on a single family lot,does(will?)the plat comply with
13 N/A N/A
General MDC(10)?
14 Is there an O&M Agreement that complies with General MDC(11)? Yes Yes
15 Is there an O&M Plan that complies with General MDC(12)? Yes Yes
16 Does the SCM follow the device specific MDC? Yes Yes
17 Was the SCM designed by an NC licensed professional? Yes Yes
FILTERRA BIORETENTION MDC FROM THE STORMWATER DESIGN MANUAL
18 Type of pretreatment that will be used Dissipater Dissipater
19 Depth of storage above the filter media surface(in) 9 in 9 in
20 Surface area of the Filterra Bioretention system(sq ft) 96 sf 96 sf
21 Method of flow distribution over the media Dispersed Dispersed
22 Infiltration rate of engineered media(inch/hour) 140 in/hr 140 in/hr
23 Diameter of the underdrain pipes(if applicable) 6 in 6 in
24 Does the design include Internal Water Storage(IWS)? No No
25 if so,elevation of the top of the IWS(fmsl) N/A N/A
26 Elevation of the planting surface(fmsl) 380.25 318.75
27 Species of tree(s)that will be planted None None
28 Media depth(inches) 21 in 21 in
29 Number of clean out pipes 1 1
30 Will maintenance be performed per the Filterra Operations and Yes Yes
Maintenance Manual?
ADDITIONAL INFORMATION
Please use this space to provide any additional information about
31 the Filterra Unit(s):
SCM 12 and 13 are made up of(2)8x12 FTBSVIB Bioscape Vaults. Rows
18-30 indicate the criteria for each of the Bioscape Vaults.
2