SW4131203_401 Certification Application_20140109

Permit Number:
(to be provided by DWO)
Myy� 020E W AI Fq�G
�' �� NCDENR
STORMWATER MANAGEMENT PERMIT APPLICATION FORM
401 CERTIFICATION APPLICATION FORM
BIORETENTION CELL SUPPLEMENT
This form must be filled out, printed and submitted.
The Required Items Checklist (Pad 111) must be printed, filled out and submitted along with all of the required information.
I` PROJECT INFORMATION+
Project name Dollar General # 15122
Contact name
Phone number
Date
Drainage area number
Matt Lowder, PE
919-333-5729
December 12, 2013
Bio-Retention Pond
Site Characteristics
Drainage area
45,740 ff'�//
Impervious area
32,148, ftz
Percent impervious
70.3% %
/
Design rainfall depth
1.0 inch
✓
Peak Flow Calculations
1w
Is pre/post control of the 1-yr, 24-hr peak flow required?
Y - (Y or N)
/
f al
1-yr, 24-hr runoff depth
2.87 in
l
1-yr, 24-hr intensity
4.72 in/hr
Pre -development 1-yr, 24-hr peak flow
1.350 ft'/sec
Post -development 1-yr, 24-hr peak flow
3,670 ff'/sec
Pre/Post 1-yr, 24-hr peak control
2.320 ff'/sec
Storage Volume: Non -SA Waters
rtrrr(rr2js'
Minimum volume required
2,608.0.ft'
,ems
°`" pt kS CAJ79 4
Volume provided
2,885.0ff'
OK
$
Storage Volume: SA Waters
�
_ 9�C� - c
1.5" runoff volume
It'
= SEAL
Pre -development 1-yr, 24-hr runoff
it
71 2443 A .13
Post -development 1-yr, 24-hr runoff
Minimum volume required
ft'
0
Volume provided
ft'
ft'
Cell Dimensions
%if ; i It
Pending depth of water
12' inches
K
ny . /
Pending depth of water
1,00 it
(!� IqV/l
Surface area of the top of the bioretention cell
2,885.0 ff2
OK
Length:
52 It
OK
/
Width:
55 If
OK
-or- Radius
It
Media and Soils Summary
Drawdown time, ponded volume
6 hr
OK
Drawdown time, to 24 inches below surface
12! hr
OK
/
Drawdown time, total:
18 hr
In -situ soil.
✓//
Soil permeability
0.10'. in/hr
Insufficient. Increase infiltration rate or include
eFdrains,
Planting media soil:
Soil permeability
2.00 in/hr
OK
yQs
Soil composition
% Sand (by volume)
87%
OK
% Fines (by volume)
8%
OK .
% Organic (by volume)
5%
OK
Total: 100%
Phosphorus Index (P-Index) of media
10(unitless)
OK
Form SW401-Bioretention-Rev.8
June 25, 2010
Parts I and II. Design Summary,
Page 1 of 2

Permit Number:
(to be provided by DWQ)
Basin Elevations
/
Temporary pool elevation
483.40 fmsl
Type of bioretention cell (answer "Y' to only one of the two
following questions):
Is this a grassed cell?
Y (Y or N)
OK
Is this a cell with trees/shrubs?
N (Y or N)
Planting elevation (top of the mulch or grass sod layer)
482.4 first
Depth of mulch
inches
Bottom of the planting media soil
480.4 fmsl
/
Planting media depth
2 ft
✓
Depth of washed sand below planting media soil
0.3 fit
Are underdrains being installed? y (Y or N)
�r
How many clean out pipes are being installed? 4 OK
What factor of safety is used for sizing the underdrains? (See 2 OK
BMP Manual Section 12.3.6)
Additional distance between the bottom of the planting media and 1 ft
the bottom of the cell to account for underdrains
Bottom of the cell required 479.1 fmsl
SHWT elevation 472 first
Distance from bottom to SHWT 7.1 ft OK
Internal Water Storage Zone (IWS)
Does the design include IWS
N (Y or N)
Elevation of the top of the upturned elbow
imsl
Separation of IWS and Surface
482.4 ft
Planting Plan
Number of tree species
0
Number of shrub species
0
Number of herbaceous groundcover species
0 Recommend more species.
Additional Information
Does volume in excess of the design volume bypass the
Y (Y or N) OK
bioretention cell?
Does volume in excess of the design volume flow evenly distributed
Y (Y or N) OK
through a vegetated filter?
What is the length of the vegetated filter?
It
Does the design use a level spreader to evenly distribute flow?
N
(Y or N)
Show how flow is evenly distributed.
Is the BMP located at least 30 feet from surface waters (50 feet if
Y
(Y or N)
OK
SA waters)?
Is the BMP located at least 100 feet from water supply wells?
Y
(Y or N)
OK
Are the vegetated side slopes equal to or less than 3:1?
Y
(Y or N)
OK
Is the BMP located in a proposed drainage easement with access
Y
(Y or N)
OK
to a public Right of Way (ROW)?
Inlet velocity (from treatment system)
2''. fYsec
Insufficient inlet velocity unless energy dissipating devices are
being used.
Is the area surrounding the cell likely to undergo development in
N
(Y or N)
OK
the future?
Are the slopes draining to the bioretention cell greater than 20%?
N
(Y or N)
OK
Is the drainage area permanently stabilized? Y (Y or N) OK
Pretreatment Used
(Indicate Type Used with an "X' in the shaded cell)
Gravel and grass
x
(8inches gravel followed by 3-5 ft of grass)
Grassed swale OK
Forebay
Other
Form SW401-bioretention-Rev.8
June 25, 2010 Parts I and 11. Design Summary, Page 2 of 2

(to be assigned by DWQ)
III. REQUIRED ITEMS CHECKLIST
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package
will result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided
to indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a
requirement has not been met, attach justification.
Pagel Plan
Initials Sheet No.
/liG C C /D
1. Plans (1 - 50' or larger) of the entire site showing:
- Design at ultimate build -out,
- Off -site drainage (if applicable),
- Delineated drainage basins (include Rational C coefficient per basin),
- Cell dimensions,
- Pretreatment system,
- High Flow bypass system,
- Maintenance access,
- Recorded drainage easement and public right of way (ROW),
- Clean out pipe locations,
- Overflow device, and
- Boundaries of drainage easement.
2 Plan details IV = 30' or larger) for the bioretention cell showing:
- Cell dimensions
- Pretreatment system,
- High flow bypass system,
- Maintenance access,
- Recorded drainage easement and public right of way (ROW),
- Design at ultimate build -out,
- Off -site drainage (if applicable),
- Clean out pipe locations,
- Overflow device, and
- Boundaries of drainage easement.
- Indicate the P-Index between 10 and 30
3. Section view of the bioretention cell (V = 20' or larger) showing:
- Side slopes, 3:1 or lower
- Underdrain system (if applicable), and
- Bioretention cell layers [ground level and slope, pre-treatment, ponding depth, mulch depth, fill media
depth, washed sand, filter fabric (or choking stone if applicable), #57 stone, underdrains (if applicable),
SHWT level(s), and overflow structure]
/1
'C L.N[5
4. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. The
results of the soils report must be verified in the field by DWQ, by completing & submitting the soils
investigation request form. County soil maps are not an acceptable source of soils information. All
elevations shall be in feet mean sea level (fmsl). Results of soils tests of both the planting soil and the in
situ soil must include:
- Soil permeability,
- Soil composition (% sand, % fines, % organic), and
GY/t L C-/0, C•//
P-index.
5. A detailed planting plan IV = 20' or larger) prepared by a qualified individual showing:
- A variety of suitable species,
- Sizes, spacing and locations of plantings,
- Total quantity of each type of plant specified,
- A planting detail,
- The source nursery for the plants, and
- Fertilizer and watering requirements to establish vegetation,
6. A construction sequence that shows how the bioretention cell will be protected from sediment until the
entire drainage area is stabilized.
`OR 61/4 S
7. The supporting calculations (including underdrain calculations, if applicable).
// e
/hfl L 544411IV744 8. A copy of the signed and notarized inspection and maintenance (I&M) agreement.
1"Ze— �
9. A copy of the deed restriction.
Form SW401-Bioretention-Rev.7 Part III, Page 1 of 1