SW4240202_Supplement-EZ Form_20240617

DRAINAGE AREAS
r 1 Is this a high density project? Yes
2 If so,number of drainage areas/SCMs 1
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 LD 1
4 Type of SCM SAND FILTER
5 Total drainage area(sq ft) 183312 72189 111123
6 Onsite drainage area(sq ft) 183312 72189 111123
7 Offsite drainage area(sq ft) 0 0 0
8 Total BUA in project(sq ft) 75399 sf 72189 sf 3210 sf
New BUA on subdivided lots(subject to permitting)
9 (sq ft) Sf sf sf
New BUA not on subdivided lots(subject to
10 permitting)(sf) sf sf sf
11 Offsite BUA(sq ft) sf sf sf
12 Breakdown of new BUA not on subdivided lots:
-Parking(sq ft) _ 51292 Sf 48082 sf 3210 Sf
-Sidewalk(sq ft) 487 sf 487 sf sf
-Roof(sq ft) 23620 Sf 23620 sf sf
-Roadway(sq ft) 20235 sf sf sf
-Future(sq ft) Sf sf Sf
-Other,please specify in the comment box
below(sq ft) sf sf sf
New infiltrating permeable pavement on
13 subdivided lots(sq ft) Sf sf Sf
New infiltrating permeable pavement not on
14 subdivided lots(sq ft) sf sf sf
Existing BUA that will remain(not subject to
15 permitting)(sq ft) 15538 Sf sf 15538 Sf
16 Existing BUA that is already permitted(sq ft) sf sf sf
17 Existing BUA that will be removed(sq ft) Sf sf Sf
18 Percent BUA 41% 100% 3%
19 Design storm(inches) 1.0 in
20 Design volume of SCM(cu ft) 5725 cf
21 Calculation method for design volume SHULER
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
22 drainage area(s):
HD area contains Buildings,Parking,and Sidwalk directed into the Sand
Filter.The LD area is directed around the site.The parcel overlaps existing
roads and drives.These areas are Existing BUA that will remain and is not
subject to permiting.Except for small parking entrance area.

SUPPLEMENT-EZ COVER PAGE
FORMS LOADED
PROJECT INFORMATION
1 Project Name Twin Oaks Landscaping
2 Project Area(ac) 4.208
3 Coastal Wetland Area(ac) 0
4 Surface Water Area(ac) 0
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) N/A
8 Will the vegetated setback remain vegetated? N/A
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
14 Stormwater Wetland
15 Permeable Pavement
16 Sand Filter 1
17 Rainwater Harvesting(RWH)
18 Green Roof
19 Level Spreader-Filter Strip(LS-FS)
20 Disconnected Impervious Surface(DIS)
121 Treatment Swale
22 Dry Pond
23 StormFilter
24 Silva Cell
25 Bayfilter
26 Filterra
FORMS LOADED
DESIGNER CERTIFICATION
27 Name and Title: Max Prestwood III,PE-Project Engineer
28 Organization: BREC,PA
29 Street address: 1520 Meadowview Drive
30 City,State,Zip: Wilkesboro,NC 28697
31 Phone number(s): [phone]
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.
Designer
Signature of Designer
Sea/ Date

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) 3:1
5 Maximum velocity in the vegetated conveyances during the 10-year storm? 2.94
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?
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:
Even though exsithing BUA is not subject to permiting,it was used for the following flow calculations
Drainage Pervious
Swale Area BUA area C Q Slope Vanaw V, Flow depth
# (ac) (ac) (ac) (cfs) (%) (fps) (fps) (ft)
1 0.73 1153.00 30692.60 0.20 0.84 1.29% 4.50 1.77 0.21
2 0.26 0.00 11468.90 I 0.20 0.35 1.26% 4.50 1.35 0.14
3 0.26 0.00 11468.90 0.20 0.35 4.79% 4.50 2.41 0.12
4 0.49 0.00 21487.10 0.20 0.50 1.27% 4.50 1.81 0.24
5 1.01 8357.00 35624.80 0.45 1.10 2.41% 4.50 2.94 0.31
6 1.42 15547.00 46433.80 0.39 2.54 0.79% 4.50 1.99 0.39
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SAND FILTER
r 1 Drainage area number 1
2 Minimum required treatment volume(cu ft 4293 sf
GENERAL MDC FROM 02H.1050
3 Is the SCM sized to treat the SW from all surfaces at build-out? Ye&
4 Is the SCM located away from contaminated soils? Yes
5 What are the side slopes of the SCM(H:V)? N/A _
6 Does the SCM have retaining walls,gabion walls or other engineered Yes
side slopes?
7 Are the inlets,outlets,and receiving stream protected from erosion Yes
(10-year storm)?
8 Is there an overflow or bypass for inflow volume in excess of the Yes
design volume? _
9 What is the method for dewatering the SCM for maintenance? Pump(preferred)_
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 N/A
General MDC(10)?
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 desi ned b an NC licensed rofessional? Yes
SAND FILTER MDC FROM 02H.1056
18 SHWT elevation(fmsl) _ 3065.00
19 Type of sand filter(open or closed) _ Closed
20 If closed,will the filter will be pre-cast or pour-in-place? _ Pre Cast
21 If closed,top of grate elevation(fmsl) 3079.97
22 Is this sand filter designed to attenuate peak flows? T No
Sediment Chamber
23 Volume that can be retained in the sediment chamber(cubic feet) 2928 cf
24 Will there be a permanent pool in the sediment chamber? Yes
25 Bottom of the sediment chamber(fmsl) 3069.53 _
26 Area of the sediment chamber(square feet) 800 sf _
27 Physical depth of the sediment chamber(inches) 49 in
28 Ponding depth in the sediment chamber,above any permanent pool 44 in
(inches)
29 Elevation of top of weir between chambers(fmsl) 3069.95
Sand Chamber
30 Volume that can be retained in the sand chamber(cubic feet) 1925 cf
31 Bottom of the sand chamber(fmsl) 3067.95
32 Area of the sand chamber(square feet) 770 sf _
33 Physical depth of the sand chamber(inches) 68 in
34 Ponding depth in the sand chamber,above the sand surface 30 in
(inches)
35 Elevation of the bypass device(fmsl) _ 3072.7 _
36 Type of bypass device _ WEIR _
37 Mechanism for distributing flow over the sand surface LEVEL
SPREADER
38 Sand specification for sand chamber ASTM C33 _
39 Depth above underdrain pipe(inches) 18 in _
40 Will the media be maintained to drain at least two inches per hour at Yes
the sand surface?
41 Is at least one clean-out pipe provided at the low point of each Yes
underdrain line?
42 Will clean-out pipes be capped? Yes
ADDITIONAL INFORMATION
43 Please use this space to provide any additional information about the
sand filter(s):
Design is a below ground solution.The sediment chamber is composed of 4
precast tanks and the sand chamber of 4 separate precast tanks.All of the
sand chambers are below ground(closed bottom).
Sand Filter 4 10:39 AM 6/14/2024