SW6130203_Supplement-EZ Form_20240116

SUPPLEMENT—EZ COVER PAGE
FORMS LOAD
PROJECT INFORMATION •
1 Project Name O'Reilly Auto Parts Area Infiltration Basin
2 Project Area(ac) 8.98_
3 1Coastal Wetland Area(ac)
4 Surface Water Area(ac)
5 Is this project High or Low Density? High
6 Does 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 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 1
12 Bioretention Cell
13 Wet Pond
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(DISC
21 Treatment Swale
22 Dry Pond
23 StormFilter
24 Silva Cell _25 Bayfilter
26 I Filterra
FORMS LOADED
DESIGNER CERTIFICATION y �
27 Name and Title: Jarrod E. Hilliard,PE,CFM
28 lOrganization:• Hilliard Engineering,PLLC
29 Street address: 3417 Winterwind Circle
30 City,State,Zip: Sanford,NC 27330
31 Phone number(s): 919-352-2834
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.
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Seal Date

DRAINAGE AREAS
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? No
4 If so,number of low density drainage areas 0
Is all/part of this project subject to previous rule
5 versions? No
FORMS LOADED
DRAINAGE AREA INFORMATION Entire Site 1
4 Type of SCM Infiltration Basin Infiltration Basin
5 Total drainage area(sq ft) 621,679 374616
6 Onsite drainage area(sq ft) 374,616 374616
7 Offsite drainage area(sq ft) 247063 0
8 Total BUA in project(sq ft) 318424 sf 318424 sf
New BUA on subdivided lots(subject to permitting)
9 (sq ft) , 273166 sf 273166 sf
New BUA not on subdivided lots(subject to
10 permitting)(sf)
11 Offsite BUA(sq ft)
12 Breakdown of new BUA not on subdivided lots:
-Parking(sq ft)
-Sidewalk(sq ft)
-Roof(sq ft)
-Roadway(sq ft)
-Future(sq ft)
-Other,please specify in the comment box
below(sq ft)
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) 45258 sf 45258 sf
17 Existing BUA that will be removed(sq ft)
18 Percent BUA 51% 85%
19 Design storm(inches) 1.0 in
20 Design volume of SCM(cu ft) _ _ 25403 cf
21 Calculation method for design volume simple
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
22 (drainage area(s):

INFILTRATION SYSTEM
1 'Drainage area number 1
2 IMinimum required treatment volume(cu ft) 25443 cf
GENERAL MDC FROM 02H.1050
3 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 or enter"Vertical"for
trenches)? 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? 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
General MDC(10)? N/A
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 designedMh,
by an NC licensed professional?_,. Yes
:INFILTRATION SYSTEM MDC FROM 02H.1051
18 Proposed slope of the subgrade surface(%) 0%
19 Are terraces or baffles provided? No
20 Type of pretreatment: Forebay
Soils Data
21 Was the soil investigated in the footprint and at the elevation of the
infiltration system? Yes
22 SHWT elevation(fmsl) 414.00
23 Depth to SHWT per soils report(in) 124.00
_
24 Ground elevation at boring in soils report(fmsl) 424.30
25 Is a detailed hydrogeologic study attached if the separation is
between 1 and 2 feet? N/A
26 •Soil infiltration rate(in/hr) 0.91
27 Factor of safety(FS) (2 is recommended): 2.00
Elevations
29 .Bottom elevation(fmsl) 416 ft
30 Storage elevation(fmsl) 422.ft
31 B •ass elevation(fmsl) 423 ft
For Basins Only
32 Bottom surface area(ft2) 9320 ft I
33 Storage elevation surface area(ft2) - 17615.ft
For Trenches Only
34 I Length(ft)
35 Width(ft)
36 Perforated pipe diameter,if applicable(inches)
37 Number of laterals
38 Total length of perforated piping
39 'Stone type,if applicable
40 Stone porosity(%)
41 Is stone free of fines?
42 Is the stone wrapped in geotextile fabric?
43 Has at least one inspection port been provided?
Volumes/Drawdown
44 Design volume of SCM(cu ft) 25443 cf
45 Time to draw down(hours) 72 hrs
ADDITIONAL INFORMATION
46 Please use this space to provide any additional information about the
infiltration system(s):
Pretreatment is achieved via a combination of gravel verges and sumps in the drop
inlets. Roof drains will tie to the storm system with the sumps.
Infiltration 1 9:58 AM 5/15/2023