SW4130801_Calculations_20130725

Storm Water & Erosion Control
Design Calculations
July ZS, 2013
Dollar General Development
W. Greesboro Chapel Hill Road
Snow Camp
Alamance County, NC
Prepared for:
Glandon Forest Equity, LLC
3900 Merton Drive, Suite 210
Raleigh, NC -27609
[phone]
Prepared by:
Triangle Site Design, PLLC
4006 Barrett Drive, Suite 203
Raleigh, NC 27609
[phone]
NC License#P-0619
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TABLE OF CONTENTS
OVERVIEW
STORMWATER NARRATIVE
FIGURES
SOILS SURVEY & SOIL INFORMATION
SHWT DETERMINATION
USGS TOPOGRAPHIC MAP
FEMA FIRM MAP
DRAINAGE AREA MAPS
WATER QUANTITY/QUALITY
BIO-RETENTION POND
NCDENR SUPPLEMENT
POND DESIGN CALCULATIONS
POND SUMMARY
CURVE NUMBERS
POND OUTLET/STRUCTURE SUMMARY
PRE -DEVELOPMENT HYDROGRAPHS
POST -DEVELOPMENT HYDROGRAPHS
ELEVATION -VOLUME -FLOW SUMMARY
EROSION CONTROL CALCULATIONS
RIP -RAP APRONS
SKIMMER BASIN
TEMPORARY GRASS CHANNEL

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Background
This report contains the storm water and erosion control calculations for the proposed Dollar
General retail site. The project site is located on W. Greensboro Chapel Hill Road in the
community of Snow Camp. The project consists of 3.16 acres and will be developed as a
Dollar General retail store with the associated parking & loading areas. Approximately 1.7
acres will be disturbed as part of this project for the construction of the site improvements.
The proposed storm water management facility (bio-retention pond) outlined in this report
have been designed to treat 1.2 acres of the site. The overall impervious area for the
proposed Dollar General parcel is 20.6% when on -site areas not draining towards the
proposed ponds are accounted for. The storm water management ponds are designed to
treat a 1.0" design storm and 85% TSS. The stormwater management ponds also provide
peak flow attenuation for the 1-Year & 10-Year storm events.
There will be no wetland or stream disturbance due the development of this property.
Erosion Control
Erosion control measures have been designed in accordance with the NCDENR erosion
control standards and regulations to minimize sediment laden runoff from exiting the site,
Silt fence will be installed along the low sides of the site prior to construction. The
construction entrance will be installed prior to construction commencing. Inlet protection
will be installed around all existing inlets and will be utilized for the proposed curb inlets and
drop inlets. A skimmer basin will be used to treat stormwater runoff prior to leaving the site.
Accumulated sediment within the project site will need to be removed and the pond
constructed to final design conditions prior to final acceptance of the project.
Soils
The Alamance County Soils Survey & site Geotechnical report indicate that Georgeville soils
are present on the site.
Site Stabilization
After final grading is completed, permanent vegetation shall be applied in accordance with
the seeding requirements and landscape plan for this site.

Stormwater Analysis
Storm water runoff from the developed areas of the site will be treated within a bio-retention
pond. The pond has been designed to treat a drainage area of 1.2 acres. The site grading
and storm drainage pipe systems are used to divert storm water runoff from the site to the
bio-retention pond. The storm water management pond is designed to treat runoff from the
impervious areas of the site. Open areas of the site not draining to the ponds will be
landscaped and open space. The site is not within SA waters, therefore the storm water
management pond is designed to treat a 1.0" design storm and 85% TSS.
Water Quantity
Post -development peak flows from the site will not exceed pre -development flows for the 1-
year, 10-year, or the 1" storms. The site is designed for the 1.0" storm and 85% TSS. The
bio-retention pond will utilize a weir structure to by-pass storm events greater than the 1-
Year storm event. Please reference the Water Quantity section of this report for details
regarding drainage areas and stormwater routing.
Methods
The stormwater conveyance system was analyzed using "Hydraflow Storm Sewers" and
"Hydraflow Hydrographs" computer software program.

FIGURES

Hydrologic Soil C1oup—Alamance County, North Carolina
Q
in
35' 53' 45"
35' 53' 35"'
IV 091V�IV {sV 1p 111 041/W [Y1 Vl3V
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5,9
641550 641580 641610 641640 641670 64170o
Map SCaie. 1.1,490 if pnntea on A size t8.5" x I ) sneel.
N
0 10 20 40 60
Feet
0 50 100 200 300
USDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
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35' 53' 46'
35' 53' 36'
v
6/25/2013
Page 1 of 4

Hydrologic Sail Group—Alamance County, North Carolina
MAP LEGEND MAP INFORMATION
Area of Interest (A01)
Map Scale: 1:1,490 if printed on A size (8.5 x 11") sheet.
Area of Interest (AOq
The soil surveys that comprise your A01 were mapped at 1:20,000.
Soils
Soil Map Units
Warning: Soil Map may not be valid at this scale.
Soil Ratings
Enlargement of maps beyond the scale of mapping can cause
0
A
misunderstanding of the detail of mapping and accuracy of soil line
placement. The maps do not show the small areas of contrasting
(]
AID
soils that could have been shown at a more detailed scale.
0
B
Please rely on the bar scale on each map sheet for accurate map
0
BID
measurements.
C
Source of Map: Natural Resources Conservation Service
CID
Web Soil Survey URL: http:llwebsoilsurvey.nres.usda.gov
Coordinate System: UTM Zone 17N NAD83
b
This product is generated from the USDA-NRCS certified data as of
Not rated or not available
the version date(s) listed below.
Political Features
Soil Survey Area: Alamance County, North Carolina
0
Cities
Survey Area Data: Version 8, Jun 15, 2012
Water Features
Date(s) aerial images were photographed: 611612006
Streams and Canals
The orthophoto or other base map on which the soil lines were
Transportation
compiled and digitized probably differs from the background
Rails
imagery displayed on these maps. As a result, some minor shifting
u
of map unit boundaries may be evident.
.�
Interstate Highways
,.�
US Routes
.M
Major Roads
Local Roads
USDA Natural Resources Web Soil Survey 6/25/2013
ZiiiiiiiiConservation Service National Cooperative Soil Survey Page 2 of 4

Hydrologic Soil Group—Alamance County, North Carolina
Hydrologic Soil Group
fl� �; airy{d olog�c Sail�Group�<;Summary�by„Map�E�nit �Alama�ce;C�oumy,�,No�h^rol�in�a�(NC044)5�
a 111 39@'dAij"kC�%AP�tF6Y1£4
Map,unitsymbaf
R7ap=unit�4namel1;?,ii'RatingrAcres'En
A01
'Percent�ofiA01,
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Cf I
Colfax silt loam, 2'to 6 percent slopes I D
0.6
5.9%
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GaB2
Georgeville silt loam, 2 to 6 percent W'I BW�
7.5
70.8%
slopes, eroded
GaC2
Georgeville silt loam, 6 to 10 percent
B _
!� 2.2
i 21.2%
slopes, eroded
Ij
I
HdC2
_
Herndon silt loam, 6 to 10 percent B �i
0.2
_
1.8% 1
slopes, eroded
I_
—
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Herndon silt loam, 10 to 15 percent B I 0.0
I 0.3°h
slopes (Nanford)
Totals for Area of Interest Y I i0.6
100.0%
USDA Natural Resources Web Soil Survey 612512013
Conservation Service National Cooperative Soil Survey Page 3 of 4

I
PO Box 1387
Richlands, AC 28574
Phone; 910-330-2784
pitimansoil 0a yahoo. con?
.tune 25„2013
Mr. George Venters
Vanguard Property Group
3900 Merton Drive
Suite 210
Raleigh, NC 27609
Ref: Snow Camp Site
Dear Mr. Venters:
The following is a summary of the soil profiles taken at the proposed ]Dollar General site located
in the Snow Camp area of Alaiilance County NC. The purpose of the evaluation was to
determine the estimated Seasonal High WaterTahle (SHWT) and to determine the infiltration
rate of the soil- A hand auger was used to obtain the soil profiles and to determine the SHWT.
Field techniques outlined in the A'orth Carolina Laws and Rulesfor &ivage I realment and
Disposal','j,stem - were used to determine soil texture, structure, consistency and soil wetness
condition.
Findings Dollar General Site
BORING 1
SHVVT>60"
DEPTH TEXTURE
STRUCTURE
MINERALOGY
MATRIX
0-4" Sit.
S8K
SS. SE
10YR 4/4
4-15` SiL
SBK
SS. SE
10YR 5t6
15.89' c
SBK
SS'SP
2.5YR418
MOTTLES MOTTLES KSAT"HR,
.1 •.5"
BORING 2 SHWT ?60"
DEPTH TEXTURE STRUCTURE MINERALOGY MATRIX MOTTLES MOTTLES KSAT "HR,
0.10" Sit. SBK SS, SP 2.5Y 4133 A -A..
10-48" c SBK SS. SE 2.5YR 41a .05•.A"

Additional borings on the property revealed areas of rock at 26" and 2" below the surface.
Saprolite was also encountered at 48" below the surface as shown on the attached map.
SHWT was determined by the indication of colors of chroma 2 or less utilizing a Munsell Soil
color Chart at >2% of soil voluble in mottles or.matrix of a horizon or horizon subdivision,
If you have any questions, please feel free to contact me at [phone]. Thank you.
Respectful ly.
R. /,y,,,.d Pittman, L,S

Now
■ Complete items 1, 2, and 3. Also complete
sign r
item 4 if Restricted Delivery is desired.
X
❑ Agent
■ Print your name and address on the reverse
❑ Addressee
so that we can return the card to you.
B. ived by (Prinfed Name)
C. e o] live
■ Attach this card to the back of the mailpiece,
5 V
5
or on the front if space permits.
1. Article Addressed to:
D. Is delivery. address �different from item 1? 0 As
/ r-' ✓.
If YES, enter delivery address'batouv No
_ _ r
Mr. George T Barnes, !r.
TM
Glandon Forest Equity, LLC
IAN 3 0 2UN
3900 MerCor3 Drive, juiLc 210'
t Rsleigh, NC 27609
3. Servlce Type /4-1,1".;
0 ertlfied Mail®o Q Pridrity Mall Express"'
Registered— O Return Receipt for Merchandise s
© Insured Mail 17 Collect on Delivery S
Z Q-3
4. Restricted Delivery? (Extra Fee) p Yes
�1`�
7013 1710 0002 1771 5 414
NA'L�'
P5 Form 3811, July 2013 Domestic Return Rece$P AAv,anre-i

DOLLAR GENERAL SNOW CAMP, NC
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6Asr`n

WATER QUALITY/QUANTITY

Permit Number:
(to be provided by DWQ)
ATRAFA
oaQF WA7ERQ�
y
7 y
NCDENK °
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 (Part Ill) must be printed, filled out and submitted along with all of the required information.
Project name
Contact name
Phone number
Date
Drainage area number
Site Characteristics
Drainage area
Impervious area
Percent impervious
Design rainfall depth
Peak Flow Calculations
Is prelpost control of the i-yr, 24-hr peak flow required?
1-yr, 24-hr runoff depth
1-yr, 24-hr intensity
Pre -development 1-yr, 24-hr peak flow
Post -development 1-yr, 24-hr peak flow
Pre/Post 1-yr, 24-hr peak control
Storage Volume: Non -SA Waters
Minimum volume required
Volume provided
Storage Volume: $A Waters
1.5" runoff volume
Pre -development 1-yr, 24-hr runoff
Post -development 1-yr, 24-hr runoff
Minimum volume required
Volume provided
Cell Dimensions
Pending depth of water
Ponding depth of water
Surface area of the top of the bioretention cell
Length:
Width:
-or- Radius
Media and Soils Summary
Drawdown time, ponded volume
Drawdown time, to 24 inches below surface
Drawdown time, total:
In -situ soil:
Soil permeability
Planting media soil:
Soil permeability
Soil composition
Sand (by volume)
Fines (by volume)
Organic (by volume)
Dotlar: General -Sr
Jul 25, 2013:
.52;275 ft2
28,415 {�
54.4% %
1.0 inch
(YorN)
2.92 in
4'.82 inIbr
UK ft'/sec
3:760 ft3/sec
2.370 ft'Isec
2,341.0
Z530:0 ft
`
its
it
it
0 ft3
it1
12 inches
,,_1:0�jt
-
30 it
ft
OK
OK
OK
OK
OK
ss, 5 hr OK
12 hr OK
18 hr
0.20 in/hr
2.00 in/hr
87%
8%
5%
Total: 100%
ri4ti�y�llrl111/���'
lead' OFIQ°°$
•Q SEAL
_ • •
24 3
t3 r
f+�rr111111
Insufficient. Increase infiltration rate or include underdrains.
OK
OK
OK
OK
Phosphorus Index (P-Index) of media 10 (unitless) OK
Form SW401-Bioretention-Rev.8
June 25, 2010
Parts I and 11. Design Summary, Page 1 of 2

Permit Number:
• 0o be provided by DWQ)
Basin Eievations
Temporary pool elevation
596.00 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 treesishrubs?
N (Y or N)
Planting elevation (top of the mulch or grass sod layer)
595 fmsl
Depth of mulch
0 inches Insufficient mulch depth, unless installing grassed cell.
Bottom of the planting media soil
593 fmsl
Planting media depth
2 It
Depth of washed sand below planting media soil
0.3 ft
Are underdrains being installed?
y (Y or N)
Flow many clean out pipes are being installed?
3
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
591.7 fmsl
SHWT elevation
589 fmsl
Distance from bottom to SHWT
2.7 ft
OK
Internal Water Storage Zone (IWS)
Does the design include IWS
N
(Y or N)
Elevation of the top of the upturned elbow
fmsl
Separation of IWS and Surface
595 fl
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 of 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?
ft
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
"
Y1-
(Y or N)
OK
to a public Right of Way (ROW)?
Inlet velocity (from treatment system)
2 fVsec
Insufficient inlet velocity unless energy dissipating devices are
being used.
Is the area surrounding the cell likely to undergo development in
IN
(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
(8inches gravel followed by 3-5 ft of grass)
X
Grassed swale
OK
Forebay
Other
Form SW401-Bioretention-Rev.8
June 25. 2010 Parts I and II. Design Summary, Page 2 of 2

PermR No,
(to be assigned by DWQ)
III itR QUIRMJTEM,:S1CHE0}(6I$�.„ �; �� K ;
"K
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.
Inf[.
✓
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.
11fZ�
C`7�
2. Plan details (1" = 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 (1" = 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)
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
P-index.
5. A detailed planting plan (1" = 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 wafering requirements to establish vegetation.
to
6. A construction sequence that shows how the bioretention cell will be protected from sediment until the
entire drainage area is stabilized.
VWL
446,
7. The supporting calculations (including underdrain calculations, if applicable).
8 A copy of the signed and notarized inspection and mainlenance (AM) agreement
ESL
9. A copy of the deed restriction.
Form SW401-Bioretention-Rev.7 Part III, Page 1 of 1

Bio-Retention Design
Site information
Sub Area Location: Drainage To Bio-Retention Area
Drainage Area (DA) = 1,2 Acres
Impervious Area (IA) = 0.65 Acres
Percent Impervious Q= 54.2 %
Required Water Quality Volume
Design Storm =
1 inch
Determine Rv Value =
0.05 + .009 (1) = 0.54 in/in
Water Quality Volume =
0.054 ac-ft
Water Quality Volume =
2,341 cf
Water Quality Volume =
0.538 inches of runoff
NQAA 1- ear, 24-hour event = 2,92 inches
Pre -Development Peak Flow (1-year, 24-hour storm):
Drainage Area = 1.2 Acres
Pre -Development Runoff Coefficient "C"= 0.3
Intensify "I" = 3.860
Pre -Development Peak Flow = 1.39 cfs
Post -Development Peak Flow (1-year, 24-hour storm):
Drainage Area = 1.2 Acres
Post -Development Runoff Coefficient "C"= _-0:65
Intensity "I" = 4.820
Post -Development Peak Flow = �__3.76 cfs
Discharge for Ponded Area
Maximum Ponding Depth =
12 in
Filter Bed Surface Area Used =
2,530 sf i
Top of Filter Media Elevation =
595.0
Media Infiltration Rate =
2.00 in/hr ..--
Media Infiltration Time =
6.0 hr
Discharge for Bioretention Filter Media
Filter Bed Depth =
2.33 A
Maximum Ponding Depth =
12 in
Filter Bed Surface Area Used =
2,530 sf
Top of Filter Media Elevation =
595.0 -
Media Infiltration Rate =
2.00 in/hr
Media Infiltration Time =
14.0 hr
Size Underdrain System
Water Quality Volume =
0.054 ac-ft
Water Quality Volume =
2,820 cf -
Drawdown =
0.016 cfs
Underdrain Pipe Size =
6 in
Number of Pipe Rows =
3 10ft on center (typ)
Length of Pipe Row =
30 If
Number of Perforations =
696
50% of Perforations =
348
Capacity of one perforation =
0.0062 cis
Total Capacity =
2.16 cfs
Is Total Capacity > Drawdown?
Yes
Underdrain pipe capacity
Slope =
0,005 %
Underdrain Area =
0.1963 sf
Underdrain Perimeter =
1.5705 If
Capacity of pipe =
0.40 cfs
Capacity of pipe (50% clogged) =
0.20 cfs
Is Total Capacity > Drawdown?
Yes

Triangle Site Design, PLLC
Curve Number Calculation (CN)
Pre -Developed Conditions (Bio-Retention)
Drainage Area (acres):
1.2
Existing 56d Groups:
56il Grouo
Map Symbol
Soil Description
Acres
Percent of DA
B
GaB2
Georgeville
1.2
100%
Existing Land Uses
Land Use Description
Existing Soil Group
Acres Curve #
Weighted CN
Impervious
B
0 98
0.0
Open Space
B
1.2 61
61.0
Cumulative Curve # =
61.0
Rational
Runoff Coefficient "C'r
1.2
Land Use Description
Acres % Site
Runoff "C"
"C"
Roofs
0 0%
0.95
U0
Asphalt/Concrete Pavement
0 0%
0.95
0.00
Lawn
1.2 100%
0.3
0.30
Wooded
0%
0.2
0.00
Cumulative "C" = 0.30

Triangle Site Design, PLLC
Curve Number Calculation (CN)
Post -Developed Conditions (Bio-Retention Pond)
1.2
Soil Group Map Symbol
B GaB2
Proposed Land Uses:
Land Use Description
Open Space - Good Condition
Impervious Area - Parking/Bldg
Soil Description
Georgeville
Existing Soil Group Acres
B 0.55
B 0.65
Acres Percent of DA
1.2 100%
Curve # _Weighted CN
61 28.0
98 53.1
Cumulative Curve # = 81.0
Rational
Runoff Coefficient "C"
Drainage Area (acres, 1.2
Proposed Land Uses.,
Land Use Description
Acres % Site
Runoff "C"
"C"
Roofs
0.21 18%
0.95
0.17
Asphalt/Concrete Pavement
0.44 37%
0.95
0.35
Lawn
0.55 46%
0.3
0.14
Wooded
0 0%
0.15
0.00
Cumulative "C" = 0.65

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1

Pond Report a
Hydraflow Hydrographs Extension for AutoCAD® Civil 3130 2009 by Autodesk, Inc. v6.066
Thursday, Jul 25, 2013
Pond No. 1 - BMP Pond
Pond Data
Contours - User -defined contour areas. Conic method used for
volume calculation. Begining
Elevation = 595.00 ft
Stage 1 Storage Table
Stage (ft) Elevation (ft)
Contour area (sgft)
tncr. Storage (cult)
Total storage (cult)
0.00 595,00
2,530
0
0
0.50 595.50
2.870
1,349
1,349
1.00 596.00
3,225
1,523
2,872
1.50 596,50
3,595
1,704
4,576
2.00 597,00
3,975
1,892
6,467
Culvert 1 Orifice Structures
Weir Structures
[A]
[B]
[C]
[PrfRsr]
[A]
[B]
[C]
[D]
Rise (in)
= 0.00
0.00
0.00
0,00
Crest Len (ft)
= 1,25
0.00
0,00
0.00
Span (in)
= 0.00
0.00
0.00
0.00
Crest El. (ft)
= 596.00
0.00
0.00
0.00
No. Barrels
= 0
0
0
0
Weir Coeff.
= 3.33
3.33
3.33
3.33
Invert El. (ft)
= 589.30
0.00
0.00
0.00
Weir Type
= Rect
---
---
---
Length (ft)
= 0,00
0.00
0.00
0.00
Multi -Stage
= No
No
No
No
Slope (%)
= 0.00
0.00
0.00
nla
N-Value
= .013
.013
.013
nla
Orifice Coeff.
= 0.60
0.60
0.60
0.60
Exfil.(inlhr)
= 2.000 (by
Contour)
Multi -Stage
= nla
No
No
No
TW Elev. (ft)
= 0.00
Stage (ft)
2.00
1.80
1.60
1.40
1.20
1.00
0.80
0.60
0.40
0.20
0 QO
Note. Culvert/Orifice outflows are analyzed under inlet tic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s)
Stage 1 Discharge
Elev (ft)
597.00
596.80
596.60
596.40
596.20
596.00
595.80
595.60
595.40
595.20
59500
0.00 0.50 1.00 1.50 2.00 2.50 3.00 3.50 4,00 4.50 5.00
Total Q Discharge (cfs)

r
Hydrograph Report
1
Hydraflow Hydrographs Extension for AutoCADO Civil 3M 2009 by Autodesk, Inc. v6.066
Hyd. No. 1
BMP Pre -Developed
Hydrograph type =
SCS Runoff
Storm frequency =
1 yrs
Time interval =
1 min
Drainage area =
1.200 ac
Basin Slope =
0.0 %
Tc method =
USER
Total precip. =
2.92 in
Storm duration =
24 hrs
Thursday, Jul 25. 2013
Peak discharge = 0.419 cfs
Time to peak =
722 min
Hyd. volume =
1,460 cuft
Curve number =
61
Hydraulic length =
0 ft
Time of conc. (Tc) =
10.00 min
Distribution =
Type II
Shape factor =
484
BMP Pre -Developed
Q (cfs) Hyd. No. 1 -- 1 Year Q (cfs)
0.50 0.50
0.45 0.45
0,40 0.40
0.35 0.35
0.30 0.30
0,25 0.25
0.20 0,20
0.15 0.15
0.10 0.10
0.05 0.05
000 000
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
Hyd No. 1

z
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3136 2009 by Autodesk, Inc. v6.066
Hyd. No. 2
BMP Post -Developed
Hydrograph type = SCS Runoff
Storm frequency = 1 yrs
Time interval
= 1 min
Drainage area
= 1.200 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 2.92 in
Storm duration
= 24 hrs
Q (cfs)
3.00
2.00
1.00
BMP Post -Developed
Hyd. No. 2 -- 1 Year
120 240 360 480 600 720 840 960
r---- Hyd No. 2
Thursday. Jul 25, 2013
Peak discharge = 2.801 cfs
Time to peak
= 718 min
Hyd. volume
= 5,626 cult
Curve number
= 81
Hydraulic length
= 0 ft
Time of conc. (Tc)
= 5.00 min
Distribution
= Type II
Shape factor
= 484
0 (cfs)
3.00
2.00
1.00
'a 0.00
1080 1200 1320 1440 1560
Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for AutoCADS Civil 3DO 2009 by Autodesk, Inc. v6.066
Hyd. No. 3
Post Through Bio-Ret
Hydrograph type = Reservoir
Storm frequency = 1 yrs
Time interval = 1 min
Inflow hyd. No. = 2 - BMP Post -Developed
Reservoir name = BMP Pond
Storage Indication method used. Exfiltration extracted from Outflow.
Post Through Bio-Ret
Peak discharge
Time to peak
Hyd. volume
Max. Elevation
Max. Storage
3
Thursday, Jul 25, 2013
= 0.000 cfs
= 1168 min
= 0 cuft
= 595.97 ft
= 2,770 cuff
0 (cfs) Hyd. No. 3 -- 1 Year 0 (cfs)
3.00 3.00
2.00 2.00
1.00 - 1.00
0.00 0.00
0 180 360 540 720 900 1080 1260 1440 1620 1800 1980 2160
Time (min)
Hyd No. 3 Hyd No. 2 7-- Total storage used = 2,770 cuff

5
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3130 2009 by Autodesk, Inc. v6.066
Thursday, Jul 25, 2013
Hyd. No. 5
BMP Post -Developed
Hydrograph type =
SCS Runoff
Peak discharge
= 0.059 cfs
Storm frequency =
1 yrs
Time to peak
= 153 min
Time interval =
1 min
Hyd. volume
= 440 cult
Drainage area =
1.200 ac
Curve number
= 81
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
USER
Time of conc. (Tc)
= 5.00 min
Total precip. =
1.00 in
Distribution
= SCS 6-Hr
Storm duration =
6.00 hrs
Shape factor
= 484
Q (cfs)
0.10
0.09
0.08
0.07
0.06
0.05
0.04
0.03
0.02
0.01
000
BMP Post -Developed
Hyd. No. 5 -- 1 Year
0 60 120 180 240 300 360 420 v V v
Hyd No, 5 Time (min)

Hydrograph Report
0
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066
Hyd. No. 6
1 in Route Thru Bio-Ret
Hydrograph type = Reservoir
Storm frequency = 1 yrs
Time interval = 1 min
Inflow hyd. No. = 5 - BMP Post -Developed
Reservoir name = BMP Pond
Storage Indication method used. EAltration extracted from Outflow.
Thursday, Jul 25, 2013
Peak discharge = 0.000 cfs
Time to peak
= 267 min
Hyd. volume
= 0 cult
Max. Elevation
= 595.09 ft
Max. Storage
= 235 cuft
I in Route Thru Bio-Ret
Q (cfs) Hyd. No. 6 -- 1 Year Q (cfs)
0.10 0.10
0.09 - 0.09
0.08 0.08
0.07 0.07
0.06 0.06
0.05 0.05
0.04 0.04
0.03 0.03
0.02 0.02
0.01 0.01
000 000
0 60 120 180 240 300 360 420 480 540 600 660 720 780 840
Time (min)
Hyd No. 6 _Ilii, Hyd No. 5 l�,a;' Total storage used = 235 cult

8
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066
Thursday, Jul 25, 2013
Hyd. No. 1
BMP Pre -Developed
Hydrograph type =
SCS Runoff
Peak discharge =
0.921 cfs
Storm frequency =
2 yrs
Time to peak =
721 min
Time interval =
1 min
Hyd. volume =
2,534 cuft
Drainage area =
1.200 ac
Curve number =
61
Basin Slope =
0.0 %
Hydraulic length =
Oft
Tc method =
USER
Time of cone. (Tc) =
10.00 min
Total precip. =
3.52 in
Distribution =
Type II
Storm duration =
24 hrs
Shape factor =
484
BMP Pre -Developed
Q (cfs) Hyd. No. 1 -- 2 Year Q (cfs)
1.00 1.00
0.90 0.90
0.80 0,80
0.70 0.70
0.60 - 0.60
0.50 0.50
0.40 0.40
0.30 0.30
0.20 0.20
0.10 0.10
000 n0a
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066
Hyd. No. 2
BMP Post -Developed
Hydrograph type =
SCS Runoff
Storm frequency =
2 yrs
Time interval =
1 min
Drainage area =
1.200 ac
Basin Slope =
0.0 %
Tc method =
USER
Total precip. =
3.52 in
Storm duration =
24 hrs
Q (cfs)
4.00
3.00
2.00
1.00
0.00 ' 1'
0 120 240
Hyd No. 2
BMP Post -Developed
Hyd. No. 2 -- 2 Year
360 480 600 720
Thursday, Jul 25, 2013
Peak discharge = 3.840 cfs
Time to peak =
718 min
Hyd. volume =
7,748 cuft
Curve number =
81
Hydraulic length =
0 ft
Time of conc. (Tc) =
5.00 min
Distribution =
Type II
Shape factor =
484
Q (cfs)
4.00
3.00
2.00
'I 1 0.00
840 960 1080 1200 1320 1440 1560
Time (min)

Hydrograph Report
10
Hydraflow Hydrographs Extension for AutoCAQ® Civil 3130 2009 by Autodesk, Inc. v6.066
Hyd. No. 3
Post Through Bio-Ret
Hydrograph type = Reservoir
Storm frequency = 2 yrs
Time interval = 1 min
Inflow hyd. No. = 2 - BMP Post -Developed
Reservoir name = BMP Pond
Storage Indication method used. Exfiltration extracted from Outflow.
Q (cfs)
4.00
3.00
2.00
1.00
120
Hyd No. 3
Post Through Bio-Ret
Hyd. No. 3 -- 2 Year
240 360
Hyd No. 2
Peak discharge
Time to peak
Hyd. volume
Max. Elevation
Max. Storage
Thursday, Jul 25, 2013
= 0.320 cfs
= 737 min
= 1,200 cuft
= 596.18 ft
= 3,485 cuft
480 600 720 840
Total storage used = 3,485 tuft
Q (cfs)
4.00
3.00
2.00
1,00
0.00
960
Time (min)

Hydrograph
Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3136 2009 by Autodesk. Inc. v6.066
Hyd. No. 1
BMP Pre -Developed
Hydrograph type
= SCS Runoff
Storm frequency
= 10 yrs
Time interval
= 1 min
Drainage area
= 1.200 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 5.07 in
Storm duration
= 24 hrs
Q (cfs)
3.00
2.00
1.00
0.00 "
0
BMP Pre -Developed
Hyd. No. 1 -- 10 Year
120 240 360 480 600 720 840 960
Hyd No. 1
13
Thursday, Jul 25, 2013
Peak discharge = 2.621 cfs
Time to peak =
720 min
Hyd. volume =
6,148 cult
Curve number =
61
Hydraulic length
= 0 ft
Time of cone. (Tc)
= 10.00 min
Distribution
= Type II
Shape factor
= 484
Q (cfs)
3.00
2.00
1.00
' 1 11- ` 0.00
1080 1200 1320 1440 1560
Time (min)

14
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066
Hyd. No. 2
BMP Post -Developed
Hydrograph type
= SCS Runoff
Storm frequency
= 10 yrs
Time interval
= 1 min
Drainage area
= 1.200 ac
Basin Slope
= 0.0
Tc method
= USER
Total precip.
= 5.07 in
Storm duration
= 24 hrs
Q (cfs)
7.00
AM
5.00
4.00
3.00
1.00
0.00
0 120 240
Hyd No. 2
BMP Post -Developed
Hyd. No. 2 -- 10 Year
360 480 600 720
Thursday, Jul 25. 2013
Peak discharge = 6.650 cfs
Time to peak =
717 min
Hyd. volume =
13,689 cuft
Curve number =
81
Hydraulic length
= 0 ft
Time of conc. (Tc)
= 5.00 min
Distribution
= Type 11
Shape factor
= 484
Q (cts)
7.00
M
5.00
4,00
3,00
2.00
1.00
- &00
840 960 1080 1200 1320 1440
Time (min)

Hydrograph Report i5
Hydraflow Hydrographs Extension for AutoCADV Civil 3D® 2009 by Autodesk, Inc. v6.066
Thursday, Jul 25, 2013
Hyd. No. 3
Post Through Bio-Ret
Hydrograph type =
Reservoir
Peak discharge
= 2.567 cfs
Storm frequency =
10 yrs
Time to peak
= 724 min
Time interval =
1 min
Hyd. volume
= 5,576 cuft
Inflow hyd. No. =
2 - BMP Post -Developed
Max. Elevation
= 596.73 ft
Reservoir name =
BMP Pond
Max. Storage
= 5,425 cuft
Storage Indication method used. Exfiltration extracted from Outflow
Q (cfs)
7.00
6.00
5.00
4.00
3.00
2.00
1.00
000
0 120
Hyd No. 3
Post Through Bio-Ret
Hyd. No. 3 -- 10 Year
240 360
Hyd No. 2
480 600 720 840
Total storage used = 5,425 cult
960vvv
Time (ruin)

r ' J
Hydrograph
Report
Hydraflow Hydrographs Extension for AutoCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066
Hyd. No. 1
BMP Pre -Developed
Hydrograph type
= SCS Runoff
Storm frequency
= 25 yrs
Time interval
= 1 min
Drainage area
= 1.200 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 5.99 in
Storm duration
= 24 hrs
Q (cfs)
4,00
i old
2.00
1.00
0.00 1 1
0 120 240
Hyd No, 1
BMP Pre -Developed
Hyd. No. 1 -- 25 Year
360 480 600 720 840
18
Thursday, Jul 25, 2013
Peak discharge = 3.798 cfs
Time to peak =
720 min
Hyd. volume =
8,707 cult
Curve number =
61
Hydraulic length =
0 ft
Time of cone. (Tc) =
10.00 min
Distribution =
Type II
Shape factor =
484
Q (cfs)
4.00
3.00
2.00
1.00
' 0.00
960 1080 1200 1320 1440 1560
Time (min)

19
Hydrograph Report
Hydraflow Hydrographs Extension for AUIOCAD® Civil 3D® 2009 by Autodesk, Inc. v6.066
Hyd. No. 2
BMP Post -Developed
Hydrograph type = SCS Runoff
Storm frequency = 25 yrs
Time interval
= 1 min
Drainage area
= 1.200 ac
Basin Slope
= 0.0 %
Tc method
= USER
Total precip.
= 5.99 in
Storm duration
= 24 hrs
Q (cfs)
10.00
M
AM
4.00
► 61611
0.00
0 120 240
Hyd No. 2
BMP Post -Developed
Hyd. No. 2 -- 25 Year
Thursday, Jul 25, 2013
Peak discharge = 8.374 cfs
Time to peak =
717 min
Hyd. volume =
17,405 cuft
Curve number =
81
Hydraulic length
= 0 ft
Time of conc. (Tc)
= 5.00 min
Distribution =
Type 11
Shape factor =
484
360 480 600 720 840 960
Q (cfs)
10.00
M
M
2.00
0.00
1080 1200 1320
Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for AutoCADO Civil 3DO 2009 by Autodesk, Inc. v6.066
Hyd. No. 3
Post Through Bio-Ret
Hydrograph type = Reservoir
Storm frequency = 25 yrs
Time interval = 1 min
Inflow hyd. No. = 2 - BMP Post -Developed
Reservoir name = BMP Pond
Storage Indication method used. Excltration extracted from Outflow.
Q (cfs)
10.00
011011111
4.00
2.00
0.00
0 120
Hyd No. 3
Post Through Bio-Ret
Hyd. No. 3 -- 25 Year
240 360
Hyd No. 2
Peak discharge
Time to peak
Hyd. volume
Max. Elevation
Max. Storage
20
Thursday, Jul 25, 2013
= 4.114 cfs
= 723 min
= 8,490 cuft
596.99 ft
= 6,438 cuft
17777
480 600 720 840
Total storage used = 6,438 cuft
Q (cfs)
10.00
4.00
2.00
- 0.00
960
Time (min)

EROSION CONTROL CALCULATIONS

EROSION CONTROL CALCS (RIP -RAP CALCULATIONS)
Project Information
Project Name:
Project #:
Designed by:
Revised by:
Checked by:
Rip -Rap Apron#1
All units are in feet
"" Dissipator pad designed for full flow of pipe
Dollar General
Date:
Date:
Date:
Pipe Diameter
d=
15
Pipe Slope
s=
0.5 %
Manning's number
n=
0.013
Flow
Q=
6 cfs
Velocity
V =
3.00 f /s
Dissipator Dimensions
Zone =
Stone Filling Class =
Entry Width ( 3 X Do) _
Length ( 6 X Do) =
Width (La + Do) _
Min. Thickness =
Min. Stone Diameter-
B
2
20.0 ft
7.5 ft
20.0 ft
22 inches
6 inches
RIP-RAP.xls
7/25/2013
Pagel of 2

Rip -Rap A1ron#2
Pipe Diameter
d=
15 in
Pipe Slope
s=
8.4 %
Manning's number
n=
0.013
Flow
Q=
3 of$
Velocity
V =
4.00 ft/s
Dissipator Dimensions *
Zone =
Stone Filling Glass =
Entry Width ( 3 X Do) _
Length (6XDo)=
Width (La + Do) =
Min. Thickness =
Min. Stone Diameter=
2
B
3.8 ft
7.5 ft
8.8 ft
22 inches
6 inches
All units are in feet
" Dissipator pad designed for full flow of pipe
RIP-RAP.xls
7/25/2013
Page 2 of 2

r P
EROSION CONTROL CALCS (SKIMMER BASINS)
Project Information
Project Name:
Project #:
Designed by:
Revised by:
Checked by:
Skimmor Basin
Drainage Area
10-year Runoff (010)
Surface Area Required
Volume Required
Sediment Trap Dimensions
Dollar General
Date
Date
Date'
Total, AT=
1.6 Ac
Disturbed, Ao=
1.6 AC
C =
0.50
T. =
5.00 min
110 =
7.20 infhr
Qla =
5.9 cfs
SA =
325sf x Qta
SA =
1,872 sf
VR =
1800 cUAc x AD
VR =
2,880 of
L =
75 tt (Spillway Length)
W =
25 ft (Spillway Width)
D =
2.0 tt (Depth of Storage)
Side Slopes =
2 :1
I-m =
L,. 83 ft
L-= 57 R W. W,„
WW= 33 ft Lb„=
W� = 17 ft
LAN Ratio= 3.0 :1 (must be 2:1 to 6:1 )
Elevations oescnV00n
Eleysixin
Top of Berm
591,00 (allow 1ft freeboard above spillway now height)
Emergency Spillway
589,50
Sediment Storage
589,00
Cleanoul Mark
588,00 (half of storage height)
Bottom
587.00
Provided SAP=
1,876 st > 1.872
VP=
3,014.0 of n 2,880
Emergency Spkllway - 10 Year Storm 110 =
7.20
Q10 =
5.76 cis
h =
0.5 fl
Cw =
3
Lw=
6 fill
a

Calculate Skimmer Size
Basin Volume in Cubic Feet 3 Cu. Ft Skimmer Size Inch
Days to Drain* `3 Days Orifice Radius .,,'0.,6,;1nch[es]
Orifice Diameter . 21 Inch[es]
In NC assume 3 days to drain
Estimate Volume of Basin Length Width
Top of water surface in feet T'i
-,;''75 T2 5] Feet et VOLUME 4 30% Cu. Ft.
Bottom dimensions in feet —'267 :7,17]Feet
Depth in feet Feet

4 a,
�,*wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww**wwwww*wwwwww*****+****
NORTH AMERICAN GREEN EROSION CONTROL MATERIALS DESIGN SOFTWARE VERSION 4.3
NORTH AMERICAN GREEN CHANNEL PROTECTION - ENGLISH/S.I.
USER SPECIFIED CHANNEL LINING BACK-UP COMPUTATIONS
wwwwwwwwwwwwwwwwwww***www*wwwwwwwwwwww****wwwwwwwwwwwww***wwwwwwwwwwwwwwww*ww
PROJECT NAME:
COMPUTED BY:
FROM STATION/REACH:
DRAINAGE AREA:
PROJECT NO.:
DATE: 7/25/2013
TO STATION/REACH:
DESIGN FREQUENCY:
wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww
INPUT PARAMETERS
wwwwwwwwwww*wwwwwwwwwwwwwwwwwwwwwwwwwwwwww*wwwwwwwww*wwwwwwwwwwwwwwww*wwwwwww
Channel Discharge
Peak Flow Period : f
Channel Slope : 0.
Channel Bottom Width
Left Side Slope .2.
Right Side Slope : 2
3.0 cfs (.08 m^3/s)
i hours
01 fuft (0.01 m/m)
: 2.0 ft (.61 m)
Channel Lining : DS75 Staple D
Permi. Shear(Tp) :1.55 psf (74.2 Pa)
Phase = 0
wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww
CALCULATIONS
www*wwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwwww
Initial Depth Estimate = 0.16 w (3.0 /(0.010^0.5))^0.375 = 0.57 ft (.17 m)
Final Channel Depth (after 6 iterations) _ .6 ft (0.18 m)
Flow Area = (2.0 w 0.6)+(0.5 w0.60112 w (2.0+2.0)) = 1.9 sq.ft (0.2 m^2)
Wet Per. =2.0 +(0.6w(((2.0^2)+1)A.5 +((2.OA2)+1)A.5)) = 4.7 ft (1.4 m)
Hydraulic Radius = (1.9 / 4.7) = 0A ft (0.1 m)
Channel Velocity=(1.486/0.053)w(0.4"0.667)w(0.010^.5) = 1.6 fps (0.5 m/s)
Channel Effective Manning's Roughness = 0.053
Calculated Shear (Td) = 62.4 w 0.60 w 0.010 = 0.38 psf (18.0 Pa)
Safety Factor = (Tp[Td) _ (1.55 /0.38) = 4A3

July 15, 2013
NCDENR
Winston-Salem Regional Office
585 Waughtown Street
Winston-Salem, NC 27107-2241
To Whom It May Concern:
Glandon Forest Equity, LLC is authorized to submit a property rezoning, a sanitary sewer septic system
review, a well permit review, a building permit review, a driveway permit review, a land disturbance
permit review and a stormwater management system review for a proposed Dollar General
Development on the property owned by Caroline A. Hinshaw. The specific property is found on
Greensboro Chapel Hill Road in Alamance County and has a Parcel ID# 102839 as described in the
Alamance County records.
Yours Truly,
a4a4la--,
Carolina A. Hinshaw
a Notary Public for the State of
do hereby certify that
)ersonally appeared before me this day of
QDA3 , and acknowledge the due execution of thisa
uthorizationto submit a
land disturbance permit application. Witness my hand and official seal,
�_. A,_, �
SEAL
My commission expires 0 �J�J� � d-U k�

I Bio-retention Cells and Rain Gardens I
Project: SW4130801 Dollar General in Snow Camp Alamance County, Jordan Lake Water Shed
Latitude 35.8942 ✓ \
Long:-79.4308 ✓ _`�
'Permitting Authority: S
Acres-(Site)::F'
Acres (Drainage Area): 52,27
Acres (BUA):_28,415 sf_or�0.65
%BUA: 20.6overall.,'4 4 far t
Design Storm: 1 inch
vVetla nds:No
Regulatory Credits
or 1.2 ac' ✓�
draiange are" a (note could be treated as low density)
✓ Pollutant-Removal.without Internal Water Storage IWS
85% Total Suspended Solids'
35% Total Nitrogen
45% Total Phosphorus_.'
NA Pollutant Removal -- with Internal Water Storage (IWS) (Coastal Plain & Sand Hills)
85% Total S SIOded Solids
60% Total Nitrogen
60%Total P,hosphor1us
NA Pollutant Removal —with Internal
85% Total SAperid-ed Solids
40% Tota I Nitrogen
45% Total Phosphorus
Requirements
IWS) (Piedmont & Mountains Count)
60
1.✓"�ide slopes stabilized with vegetation shall be no steeper than 3:1.
W"�Either a bypass or an internal overflow is required for bypassing storm flows in excess of the design flow for
bioretention cells.
✓A vegetated filter strip is not required for overflows, bypass flows, or discharges from a bioretention cell (except for
_ within % mile of and draining to SA waters or unnamed tributaries of to SA waters).
V✓ The design shall be located a minimum of 30 feet from su.rface_waters, and 50 feet from Class SA waters. ✓
1� w
✓— The design shall be located a minimum of 100 feet from"ater supply wells
�✓ Bioretention facilities shall not be used where slopes greater than 20%
✓✓l Inflow must be sheet flow (1 ft/sec for mulch cells, 3 ft/sec for grass cells) or utilize energy dissipating devices.
SHWT /
SH WT: 589 ^✓ '
Bottom of BMP: 591.7
✓ Bioretention shall not be used where the seasonally high water table is less than 2 feet below bottom of the BMP.

Bio-retention Cells and Rain Gardens
Water Quality Treatment Volume
Water Quality Treatment Volume = 3630qRd*& * Ac 3630 * 1
Where Ac=[sf of Drainage Area]/43,560 sf/ac -� 1.2
Rd = Design Storm (I inch?
I = Impervious Portion / Drainage Area = 0.544
Rv = 0.05 + 0.9 * I = 0.05 + 0.9 *0.544 = .53
Volume Required 2347 cf
Volume Provided: 2530 cf
10/10/10 Rule (Dimensions, Ponding Depth and Surface Area)
* 0.539 *�? 2347.8 cf
✓ No dimension is less than 10 feet (width, length, or radius)
✓ Ponding depth approximately 10 inches (must be 12 inches or less, 9 inches or less is preferred)
✓ Surface area = 10% of the BUA
Cells at or below 5,000 square feet tend to function more effectively than large bio-retention cells, therefore; the
surface area of bioretention BMPs should be at or below 5,000 square feet.
Dimensions: 75 x 30 111;;�
Ponding Depth: 12 inches --
Surface Area Required: 0 10*28,415=(2,841-sfk-'
Surface Area Provided: 7755 *_30 = 2250 sf *-may be a little low ✓
Soil Mix/Media
✓ 85-88 percent by volume sand (87% provided)
✓ 8 to 12 percent fines (silt and clay) (8% provided)
✓ 3 tc`5 percent organic matter (such+ eat moss) (5% provided)
✓ P-Index between 10 and 30 provided)
✓ Permeability between 1 and 6 inches per hour, and 1-2 inches per hour is preferred (under drains provided)
✓ 2 feet minimum media depth for grassed cells, 3 feet for shrub/tree cells or when using IWS. (2 feet w sod)
Under Drains
✓ Where the infiltration rate is less than 2 in/hr
✓ Clean -out pipes must be provided (minimum one per every 1,000 square feet of surface area). ­
✓ Clean out pipes must be capped. L---"
Drainage Considerations
✓ Ponded water shall completely drain into the soil within 12 hours
✓ Ponded water shall completely drain to a level of 24 inches below the soil surface within 48 hours.