20200579 Ver 1_Whirligig-SuppEZ-2018_20200511

ID#* 20200579 Version* 1
Select Reviewer:*
Katie Merritt
Initial Review Completed Date 05/12/2020
Mitigation Project Submittal - 5/11/2020
Is this a Prospectus, Technical Proposal or a New Site?* O Yes a No
Type of Mitigation Project:*
r Stream r Wetlands G Buffer q Nutrient Offset
(Select all that apply)
Project Contact Information
Contact Name:*
Rebecca Stubbs, PE
Project Information
...................................................................................
ID#:* 20200579
Existing IW
Project Type:
Project Name:
County:
F DMS r Mitigation Bank
Whirligig Station
Wilson
Document Information
Email Address:*
[e-mail]
Version: * 1
Existing Version
Mitigation Document Type:*
Mitigation Information
File Upload: Whirligig-SuppEZ-2018.pdf 513.4KB
Rease upload only one R7F of the corrplete file that needs to be submtted...
Signature
Print Name:* Heather Dew, PE
Signature:*

31Ur,rI—CMr_iYI—CL. 40VVr_M C'HVC
FORMS LOADED
OOP] IANCE VWTH 02H .1003 4
7 Wrdtb of vegetated setbacks,prov(ded, (feet NIA
8 Will the vecietated setback remain vegetated? No
9 Is BUA other that as listed in _1003�4)(c-d) out e. the setback'? Yes
10 is streambank stabilization proposed on this project? No —_.--
UMBER
11
AND TYPE OF SCMs:
lnfiHraiiori S�rstem
Bt3ioretenti in Cell
_ 0
0
_ 0 _
1
13
Wet Pond
14
Stormwater Wetland
0
15
Permeable Pavement
b
16
Sand Filter
1
17
Rainwater Flares RWH
0
18
Green Roof
0
19
Level S)reader-Filter §tfo
Disconnected lmpervious Surface(DIS)
0
20
0
21
Treatment Swale
0
22
Dry Pond
D
23
5tormFilter
0
24
Silva Cell
0
25
BayW
f 0 ,
26
jFilteaa
FQ] R S LOADED
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 (lest 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.
= SEAS.
49073.2�?
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ll� s r� `��ii�ealtit�!
Date
CaA w' 1CA;tidms O"t 1)

DRAINAGE AREAS
1 Is this a high density project?Yes
2 If so, number of drainage areas/SCMs 1
3
Is all/part of this project subject to previous rule
versions?No
FORMS LOADED
Entire Site 1
4 Type of SCM Sand Filter Sand Filter
5 Total BUA in project (sq ft)377194 sf 375066 sf
6
New BUA on subdivided lots (subject to permitting)
(sq ft)0 0
7
New BUA outside of subdivided lots (subject to
permitting) (sf)0 0
8 Offsite - total area (sq ft)0 0
9 Offsite BUA (sq ft)0 0
10 Breakdown of new BUA outside subdivided lots:
- Parking (sq ft)200594 sf 198466 sf
- Sidewalk (sq ft)
- Roof (sq ft)101282 sf 101282 sf
- Roadway (sq ft)75318 sf 75318 sf
- Future (sq ft)
- Other, please specify in the comment box
below (sq ft)
11
New infiltrating permeable pavement on
subdivided lots (sq ft)
12
New infiltrating permeable pavement outside of
subdivided lots (sq ft)
13
Exisitng BUA that will remain (not subject to
permitting) (sq ft)377194 sf 375066 sf
14 Existing BUA that is already permitted (sq ft)377194 sf 375066 sf
15 Existing BUA that will be removed (sq ft)0 0
16 Percent BUA 100%100%
17 Design storm (inches)1 in 1 in
18 Design volume of SCM (cu ft)22270 cf 22270 cf
19 Calculation method for design volume WQV=P*R*A/12 WQV=P*R*A/12
20
Entire Site 1
4 Type of SCM N/A
5 Total BUA from project (sq ft)
6 1995 rules
SL 2006-246
2008 rules
2017 rules
7
New BUA on subdivided lots (subject to
permitting) (sq ft)
1995 rules
SL 2006-246
2008 rules
2017 rules
8
New BUA outside of subdivided lots (subject to
permitting) (sf)
1995 rules
SL 2006-246
2008 rules
2017 rules
9 Offsite - total area (sq ft)
1995 rules
SL 2006-246
2008 rules
2017 rules
10 Offsite BUA (sq ft)
1995 rules
SL 2006-246
DRAINAGE AREA INFORMATION
DRAINAGE AREA INFORMATION
ADDITIONAL INFORMATION
"Parking" includes driveway and sidewalk.
Please use this space to provide any additional information about the
drainage area(s):
2008 rules
2017 rules
11 Design storm (inches)
1995 rules
SL 2006-246
2008 rules
2017 rules
12 Breakdown of new BUA:
- 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)
13
New infiltrating permeable pavement on
subdivided lots (sq ft)
14
New infiltrating permeable pavement outside of
subdivided lots (sq ft)
15
Exisitng BUA that will remain (not subject to
permitting) (sq ft)
16 Existing BUA that is already permitted (sq ft)
17 Existing BUA that will be removed (sq ft)
18 Percent BUA
19 Design volume of SCM (cu ft)
20 Calculation method for design volume
21
Please use this space to provide any additional
information about the drainage area(s):
ADDITIONAL INFORMATION
SAND FILTER
1 Drainage area number 1
2 Design volume of SCM (cu ft)22270 sf
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)?N/A
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
16 Does the SCM follow the device specific MDC?Yes
17 Was the SCM designed by an NC licensed professional?Yes
18 SHWT elevation (fmsl) 130'-133'
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)135.33
22 Is this sand filter designed to attenuate peak flows?Yes
23 Volume that can be retained in the sediment chamber (cubic feet)4919 cf
24 Will there be a permanent pool in the sediment chamber?Yes
25 Bottom of the sediment chamber (fmsl)127.00
26 Area of the sediment chamber (square feet)2460 sf
27 Physical depth of the sediment chamber (inches)24 in
28
Ponding depth in the sediment chamber, above any permanent pool
(inches) 30 in
29 Elevation of top of weir between chambers (fmsl)129
30 Volume that can be retained in the sand chamber (cubic feet)29027 cf
31 Bottom of the sand chamber (fmsl)127.00
32 Area of the sand chamber (square feet)6451 sf
33 Physical depth of the sand chamber (inches)54 in
34
Ponding depth in the sand chamber, above any permanent pool
(inches) 30 in
35 Elevation of the bypass device (fmsl)131.5
36 Type of bypass device Weir
37 Mechanism for distributing flow over the sand surface Weir
38 Sand specification for sand chamber
39 Depth above underdrain pipe (inches)24 in
40
Will the media be maintained to drain at least two inches per hour at the
sand surface? Yes
41
Is at least one clean-out pipe provided at the low point of each
underdrain line? Yes
42 Will clean-out pipes be capped?Yes
43
Please use this space to provide any additional information about the
Sand Filter(s):
SAND FILTER MDC FROM 02H .1056
GENERAL MDC FROM 02H .1050
Sand Chamber
Sediment Chamber
ADDITIONAL INFORMATION
Sand Filter 4 6:04 PM 4/8/2020