SW5240601_Supplement EZ_20240617

SUPPLEMENT-EZ COVER PAGE
FORMS LOADED
PROJECT INFORMATION
1 Project Name _ SBI Headquarters Addition&Renovation
2 Project Area(ac) 14.64
_ 3 Coastal Wetland Area(ac) 0
4 Surface Water Area(ac) 0
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) N/A
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)? Yes
10 Is streambank stabilization proposed on this project? I No
NUMBER AND TYPE OF SCMs:
11 Infiltration System 0
12 Bioretention Cell 0
13 Wet Pond 1
14 Stormwater Wetland 0
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 Dry Pond 0
23 StormFilter 0
24 Silva Cell 0
25 Bayfilter 0
26 Filterra 0
FORMS LOADED
DESIGNER CERTIFICATION
27 Name and Title: Frank Slinsky.P.E.,Senior Project Manager
28 Organization: Timmons Group
29 Street address: 5410 Trinity Road,Suite 102
30 City,State,Zip: Raleigh,NC.27607
31 Phone number(s): I [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
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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 Wet Pond
5 Total drainage area(sq ft) 637,647 _ 526,253
6 Onsite drainage area(sq ft) 637,647 526,253
7 Offsite drainage area(sq ft) 0 0
8 Total BUA in project(sq ft) 391784 sf 315810 sf
New BUA on subdivided lots(subject to
9 permitting)(sq ft)
New BUA not on subdivided lots(subject to
10 permitting)(sf) 340804 sf 296662 sf
11 Offsite BUA(sq ft)
12 Breakdown of new BUA not on subdivided lots:
-Parking(sq ft) 122663 sf 122663 sf
-Sidewalk(sq ft) 34345 sf 23478 sf
-Roof(sq ft) 34259 sf 34259 sf
-Roadway(sq ft) 92554 sf 60845 sf
-Future(sq ft) 55417 sf 55417 sf
-Other,please specify in the comment box
below(sq ft) 1566 sf
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) 49195 sf 19148 sf
16 Existing BUA that is already permitted(sq ft)
17 Existing BUA that will be removed(sq ft) 126000 sf
18 Percent BUA 61% 60%
19 Design storm(inches) 1.0 in
20 Design volume of SCM(cu ft) 25878 cf
21 Calculation method for design volume Simple Method
ADDITIONAL INFORMATION
Please use this space to provide any additional information about the
22 drainage area(s):
Assumed line 17 is existing BUA that was not subject to permitting that will
be removed. Other:is existing BUA that is subject to permitting that is to
remain.

WET POND
I 1 Drainage area number 1 (Pond A)
2 Minimum required treatment volume(cu ft) 25878 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)? 3:1
Does the SCM have retaining walls,gabion walls or other engineered
6 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)? No
If the SCM is on a single family lot,does(will?)the plat comply with
13 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 designed by an NC licensed professional? Yes
WET POND MDC FROM 02H.1053
18 Sizing method used SA/DA
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) 324.50
21 Elevation of the main pool bottom(top of sediment removal)(fmsl) 325.50
22 Elevation of the bottom of the vegetated shelf(fmsl) 329.00
23 Elevation of the permanent pool(fmsl) 329.50
24 Elevation of the top of the vegetated shelf(fmsl) 330.00
25 Elevation of the temporary pool(fmsl) 330.97
26 Surface area of the main permanent pool(square feet) 13149.00
27 Volume of the main permanent pool(cubic feet) 39966 cf
28 Average depth of the main pool(feet) 3.04 ft
29 Average depth equation used Equation 2
30 If using equation 3,main pool perimeter(feet) N/A
31 If using equation 3,width of submerged veg.shelf(feet) N/A
32 Volume of the forebay(cubic feet) 6104 cf
33 Is this 15-20%of the volume in the main pool? Yes
34 Clean-out depth for forebay(inches) 12 in
35 Design volume of SCM(cu ft) 25878 cf
36 Is the outlet an orifice or a weir? Orifice
37 If orifice,orifice diameter(inches) 2.3 in
38 If weir,weir height(inches) N/A
39 If weir,weir length(inches) N/A
40 Drawdown time for the temporary pool(days) 3.3
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) 48 in
44 Depth of forebay at exit(inches) 30 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) 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 Bermuda
54 Has a planting plan been provided for the vegetated shelf? Yes
ADDITIONAL INFORMATION
55 Please use this space to provide any additional information about the
wet pond(s):
This is a state-owned parcel and is exempt from recording drainage easements.
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