SW5220801_Design Calculations_20221220

Storm Water & Erosion Control
Design Calculations
December 20, 2022
Dollar General
___ White Cross Rd/NC HWY 54 W
Orange County
Prepared for:
Glandon Forest Equity, LLC
3825 Barrett Drive, Suite 100
Raleigh, NC 27609
Prepared by:
Bowman North Carolina, Ltd.
4006 Barrett Drive, Suite 104
Raleigh, NC 27609
[phone]
FIRM# F-1445
Bowman

TABLE OF CONTENTS
OVERVIEW
STORMWATER NARRATIVE
FIGURES
SOILS SURVEY & SOIL INFORMATION
USGS TOPOGRAPHIC MAP
FEMA FIRM MAP
SURFACE WATER CLASSIFICATIONS
HUC
NOAA POINT PRECIPITATION FREOUENCY ESTIMATES
DRAINAGE AREA MAPS
WATER QUANTITY/QUALITY
NUTRIENT CALCULATIONS
STORMWATER WETLAND CALCULATIONS
CN VALUES
PRE -DEVELOPMENT HYDROGRAPHS
POST -DEVELOPMENT HYDROGRAPHS
TIME VS. VOLUME (STORAGE)
TIME VS. ELEVATION (STAGE)
ELEVATION -VOLUME -FLOW SUMMARY
POND OUTLET/STRUCTURE SUMMARY
TIME OF CONCENTRATION
DRAINAGE DESIGN
EROSION CONTROL CALCULATIONS
RIP -RAP APRON
SKIMMER BASIN
ANTI -FLOTATION CALCULATIONS
TEMPORARY DIVERSION DITCH

OVERVIEW
This report contains the storm water management and erosion control calculations for the
proposed Dollar General Store site. The project site is located at the intersection of White
Cross Road and NC HWY 54 in Chapel Hill, Orange County and is a residential property.
The proposed project site consists of 4.83 acres and approximately 2.97 acres will be
disturbed as part of this project for the construction of the site improvements.
The development of the site will result in an impervious area of 36,178sf (0.83ac -
17.18% impervious).
The proposed Dollar General site is not located within a FEMA designated flood zone as
shown on FEMA FIRM Panel 3710974900K with an effective date of November 17, 2017.
Flood zones are subject to change by FEMA.
There are no existing stream or wetland features on the proposed property.
The proposed site is within the Cape Fear River Basin and is within the Jordan Lake
water supply watershed.
There is a proposed storm water management facility (stormwater wetland pond) on site.
The SCM outlined in this report has been designed for post —development peak attenuation
and water quality. The SCM is designed to capture a drainage area of 1.09 ac with an
impervious area of 0.82 ac. The site grading and storm drainage systems are designed
to convey stormwater runoff from the impervious areas of the site to the stormwater
wetland pond. The site is not located within a coastal county, therefore the design storm
for water quality is a 1,0" storm event,
Erosion Control
Erosion control measures have been designed in accordance with NCDEQ 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. 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 County Soils Survey indicates that Appling Sandy Loam 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.

FIGURES

Hydrologic Soil Group —Orange County, North Carolina
35° 55 21' N
35° S5' lY N
OM360 66M 66342D 653450 663460
3
Map Sole: 1:1,240 if printed on A portrait (8.5' x 11") sheet
s
N Meyer
15 30 60 9D
Feet
0 50 100 20D 300
Map projection: Web Mamhor C Tw000rdinates: WGS84 Edge tics: UrM Zone 17N WGS84
LJSDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
6a351 D
663510
35° 55 21" N
I
35° 5512' N
663540
3
4/7/2022
Page 1 of 4

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Hydrologic Soil Group —Orange County, North Carolina
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
ApB Appling sandy loam, 2 to B 5.7 1 97.0%
6 percent slopes
Cp
Congaree fine sandy C
loam, 0 to 2 percent
slopes, frequently
flooded
Totals for Area of Interest
Description
0.21 3.0%
5.91 100.0% 1
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long -duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential) when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential) when
thoroughly wet. These consist chiefly of clays that have a high shrink -swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or VD), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
USDA Natural Resources Web Soil Survey 4/7/2022
aiiiiiiiiiiiii Conservation Service National Cooperative Soil Survey Page 3 of 4

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NOAA Atlas 14, Volume 2, Version 3
' Location name: Chapel Hill, North Carolina, USA'
Latitude: 35.9206°, Longitude:-79.1886° ~f
Elevation: ft
source: ESRI *"
SRI Maps
source: t1SGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. Parzybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF tabular I PF graphical I Maps &aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)1
Duration
Average
recurrence interval (years)
1 J1
2�
10
25
50
100
200
500
1000
0.409
0.561
0.615
0.674
0.712
0.747
0.775
0.805
0.827
5-min
(0.374-0.44$}
(0.513-0.613
0.561-0.672}
(0.612-0.735)
(0.645-0.777
(0.673-0.815 )
( 0.695-0.847)
0.715-0.880 ]
0.728-0.904 )
10-min
(0.598-0.715
mi(O.821-0.982)1(0-898-1.07)
0.975-1.17
1.03 1324
(1.07-11930)
(1.10--21334)
1. 3-21739
(1. 5--31042)
7407
15-min
(0.747--0 894)
(0 99
(1.04-11424
1. 4 1.36
(1.24-31648
1.30�57
(1.3551064
(1.39--1.69
(1.42-61075
1.44--61379)
30-min
1. 2-1223
1. 3--31547) .
1. 8-61.76
1. 5-81097
(1. 3-2.20
1.96 2636
2.07 2051
2. 6 2.64
2.26 2579
2. 3-62 89
1.40
1.69
2.07
2.35
2.68
2.93
3.17
3.39
3.66
3.86
60-min
(1.28-1.53
(1.55-1.85)
(1.89-2.26)
(2.14-2.56
(2.44-2.93)
2.65-3.20)
(2.85-3.45
(3.03-3.70
(3.254.00) 11
(3.40-4.22
2-hr
1.67
1.52-1.83
2.02
1.85-2.22)
2.50
(2.28-2.74)
2.86
(2.60-3.13)
3.31
1 (2.99-3.62)
3.65
(3.29-3.99)
3.98
(3.56-4.36
4.31
(3.834.72)
4.73
1 (4.16-5.18)
5.06
1 (4.40-5.55)
3-hr
1.63 1.95
1.98 2.36
(2.44 2?93
2. 00736
(3.24 3891
3. 8 4834
3.91 4?77
4. 25620
(4.63?5.77
{4. 4 6923
6-hr
2.14
2.59
3.21
3.70
4.35
4.86
5.38
5.91
6.62
7.19
1.97-2.34 )
(2.38-2.83 )
(2.94-3.51 )
3.38-4.04 )
(3.944.73 )
( 4.38-5.29 )
( 4.61-5.85
(5.22-6.42)
(5.77-7.19)
(6.19-7.83
12-hr
.
23 2376)
(2 81-3.34)
(3. 0 4116)
(4.04 4Z83
(4.765570)
(5. 3 6?42)
5. 8--7-15
6. 5 7392)
(7-2 9.01)
1 (7.79 9.90
2.95
3.56
4.44
5.13
6.07
6.80
7.55
8.32
9.38
10.2
24-hr
2.76-3.15)
(3.34-3.81)
1 (4.16-4.74)
1 (4.80-5.48)
1 (5.65-6.48)
1 (6.32-7.27)
(6.99-$.0$
7.68-8.94
8.61-10.1
9.33-11.0
3.45
4.16
5.14
5.91
6.92
1 7.72
8.53
9.36
10.5
11.4
2-day
3,24-3.69
(3.904.45) 11
(4.82-5,51) [1
5.526.32
(6A5-7.41)
1 (7.17-8.27)
8.62-10.1
9.61-11.3
(10.4-12.3
3.65
4.39
5.41
6.21
7.27
8.11
8.97
9.84
11.0
12.0
3-day
.
3.43-3.91)
(4.124.69)
(5 .07-5.79
5.80-6.64)
(6.77-7.79)
7.53-8.70)
(8.29-9;63)
(9.06-10.6)
(.10.1-11.9)
(10.9-13.0).
3.86
4.62
5.68
6.57
7.62
8.50
9.40
10.3
11.6
12.6
4-day
3.624.12
(4,344.94
(5,32-6.07)
6.08-6.96)
(7.10-8.17
7.89-9.12)
(8.69.10.1)
(9.51-11.1)
(10.6-12.5)
(11.5-13.7) _
7-day
4.17i1�71
4.97- 62
8.:03 $a82)
6862�77
7.9 =99071
8.8310.1
9,71--1.2
10.6- 2.3
11 8 13-8
(12-7.5.0) ,
10-day
20-day
5.02
(4,74-5,34)
77
8.97
(5.63-8.35]
7.16
6.75.7.82)
8.10
{7,62-$.62
9.36
($.78-9.97}.
10.3
{9.S$-11.0] ,
11.4
(10.6.12.1)
12.4
1 (.11.5-13.3:)
13.8
12.7-14.8
14.8
13.6-18.0)
(6.3 11
7 50-8,38
S.84-9 89)
[9.90 1.1
(11 3 12.8
12 4 4.1
73.5.-15.4]
14 75 6.8]
162-1 B.7
17-3-20.2)
8.34
9.82
11.4
12.6
14.3
15.5
16.7
18.0
19.7
20.9
30-day
(7.92-8.82)
(9.30-10.4)
10.8-12,0
11.9-13.3
(13.4-15.1)
14.6-16.4
15.7-17.8
(16.8-19.1)
[18.3-20.9)
(19,4-22.4)
11 8-13.1
13.5- 4.9
14.8- 6.4)
(16i5-18.3
17.16- 9.8
1921021.3
203- 2,8
21?9- 4,8
232426,3.
60-day
12.8
14.9
16.6
18.2
20.1
21.5
22.9
24.2
26.0
27.3
(12.2-13.4)
(14.2-15.6)
(16.0-1T6
17.4-19.1)
(19.2-21A)
20.5-22.6)
(21.7-24.1)
(210-25.5
(24.5-27.4)
{25.7-28.9
Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90% confidence interval. The probability that precipitation frequency estimates (for a
given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5%. Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and may be higher than currently valid PMP values.
Please refer to NOAA Atlas 14 document for more information.
Back to Top
PF graphical

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WATER QUALITY/QUANTITY

SUPPLEMENT-EZ COVER PAGE
FORMS LOADED
PROJECT INFORMATION
1
Project Name
Dollar General
2
Project Area ac
4.83
3
Coastal Wetland Area ac
-
4
Surface Water Area ac
-
5
Is this ro'ect Hi h 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 ve etated?
Yes
9
If BUA is ro osed in the setback, does it meet NCAC 02H.1003 4 c-d ?
No
10
Is streambank stabilization proposed on this project?
No
NUMBER AND TYPE OF SCMs:
11
Infiltration System
0
12
Bioretention Cell
0
13
Wet Pond
0
14
Stormwater Wetland
1
15
Permeable Pavement
0
16
Sand Filter
0
17
lRainwater Harvesting (RWH)
0
18
lGreen 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 1
Bayfilter
0
26
Filterra
0
FORMS LOADED
DESIGNER CERTIFICATION
27
Name and Title:
Organization:
Street address:
Matt Lowder, PE
28
Bowman North Carolina, Ltd.
29
4006 Barrett Drive, Suite 104
30
City, State, Zip:
Raleigh, NC 27609
31
Phone numbers :
919-553-6570
32 1
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.
r q ••
Sea!
*"d,e
i6ignaUke of Designe9r
Il L Z�
Date

DRAINAGE AREAS
1
Is this a hi h densi ro'ecl?
Yes
2
If so number of drainage areas/SCMs
1
3
Does this project have low ensity areas?
No
4
If so -number of low density drainage areas
0
5
Is all/part of this project subject to previous rule
versions?
No
FORMS LOADED
DRAINAGE AREA INFORMATION
Entire Site
1
4
Type of SCM
Wetland
5
Total drainage area (sq ft
210577 sf
47553
6
Onsite drainage area (sq ft
210577 sf
47553
7
Offsite drains a area (sq ft
8
Total BUA in project s ft
36178 if
35697 sf
9
New BUA on subdivided lots (subject to
j permitting)s ft
10permitting)
New BUA not on subdivided lots (subject to
s
11
Offs ite BUA (sq fl
12
Breakdown of new BUA not on subdivided lots:
- Parking (sq ft
23017 sf
22536 sf
- Sidewalk (sq ft
2521 sf
2521 sf
- Roof (sq ft
10640 if
10640 sf
- Roadway s ft
Future (sS 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 not on
subdivided lots (sq ft
15permitting)_
Existing BUA that will remain (not subject to
s ft
16
ExisVn . BUA that IsMready parmItted (sq ft
17
Existing BUA that will be removed (sq ft
1191 sf
1191 sf
18
Percent BUA
17.18%
75.07%
19
Design storm inches
1.0 in
20
Design volume of SCM cu ft
3554 cf
21
Calculation method for design volume
Simple Method
ADDITIONAL INFORMATION
Please use this space to provide any additional Information about the
drainage area(s):
_22
There is 481 sf (impervious bypass) of the driveway that will not be treated
by the SCM.

STORMWATER WETLAND
31
Area, total surface area of the SW wetland at Temporary pool elev.
Area
5,580.00
32
Area, temporary Inundation zone at temporary pool elev. (sq ft)
1.800.00
33
Area, shallow water zone at temporary ool elev. (sq ft)
2.020.00
34
Area. forebay at temporary I elev. (sq ft
625.00
35
Area. non-forebay deep pool at temporary I elev .(s il)
360.00
36
Percent area provided, temporary inundation zone (should be 30-
45%
32%
37
Peroenf area provided, shallow water zone should be 35-45 %
36%
38
Percent area provided. deep of foreba should be 10-15 %
11%
39
Percent area provided, deep pool (non-forebay) (should be 5-15%)
7%
Wetland 1 10:22 AM 12/20/2022

STORMWATER WETLAND
Warldpiftntr
501 Soil amendment depth (Inches) 12 In
51
Has a soil amendments cificalion beenprovided?
yes
52
Hasa landscaping plan that meets SW Wetland MDC (12) been
Yes
rovide&
53
Number of plants per 200 square feet (#) in the shallow water zone:
54
Does the temporary inundation zone planting comply with SW
Yes
Wetland MUC.(14)7
55
Ara lha dam sWcture and temporary fill slopes planted in non-
Yes
Glum turf rass?
56
WII} rEttdlls be Uanted In the wetland?
No
ADDITIONAL
INFORMAMN
Please use Ih�s space la nroajde any additional information about
57
the stormwaler wetland(s):
TN spreadahacI wouldnY let me enter values for#53, the plaid numbers.
We added 507 plants (50 plants per Met). Llne 24 - The peak
atlentuation for Orange County Is for the I year, 24hr storm evant
Wetland 1 10:22 AM 12/20/2022

Proiect Information
Project Name:
Submission Date:
Dollar General
12/20/2022
210,577 ft2
Project Area (ft):
Disturbed Area (ft2):
129,583 ft 2
Commercial
Development Land Use Type:
Development Activity Type:
Designated Downtown Area?
Development - New
no
NC Hwy 54
Project Location/Address:
County:
Orange
Local Jurisdiction:
Orange County
Project Latitude Coordinates:
35.923097 N
Project Longitude Coordinates:
-79.177172 W
Precipitation Station:
Chapel Hill
Physiographic Region:
Piedmont
Nutrient Management Watershed:
Jordan Lake
Subwatershed:
Jordan - Upper New Hope
Phosphorus Delivery Zone:
Jordan - 050060
Jordan - 050060
Nitrogen Delivery Zone:
Project Designer and Contact Phone
Number / Email:
Matt Lowder, PE Bowman North Carolina, Ltd. 919-
Part of Common Development Plan?
no
Project Owner Type:
Private
Project Description:
Dollar General Retail Store

Proiect Area Land Cover Characteristics
PROJECT AREA LAND COVERS
Roof
Roadway
TN
EMC
(mg/L)
1.18
1.64
TP
EMC
(mg/L)
0.11
0.34
Pre-
Project
Area (ft)
Post -
Project
Area (ft)
10,640
Parking/Driveway/Sidewalk
1.42
0.18
1,191
25,538
Protected Forest
0.97
0.03
Other Pervious/Landscaping
2.48
1.07
209,386
166,449
CUSTOM LAND COVER 1
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKEN UP BY SCM
1.18
0.11
7,950
LAND COVER AREA CHECK
Net Change of Land Covers (ftZ): 42,937
Total Project Area Entered (ft): 210,577
Total Pre -Project Calculated Area (ft): 210,577
Total Post -Project Calculated Area (ft): 210,577
Equations Used and ProiectArea Calculations
SIMPLE METHOD Stormwater Runoff Volume Generated, V
Runoff Coefficient R v V = P1 * Rv * (P/12) * A
R = 0.05 + (0.009 *1) where A = drainage area (ft)
where I = percent impervious (%) Pj = fraction of rain events with runoff
Average Annual Pollutant Load L P = average annual rainfall depth (in)
L=(Pj*R *(P/12))*(C*A*2.72)
where C = event mean concentration (mg/L)
Pre -Project:
Post -Project:
A = 4.8342
ac
A = 4.8342
ac
P = 47.31
in.
P = 47.31
in.
V = 41162
ft 3
V = 179689
ft3
1 = 1%
1 = 21%
R„ = 0.06
R = 0.24
Pi = 0.9
PI = 0.9
CTN = 2.38
mg/L
CTN = 1.51
ME
CTP = 0.98
mg/L
CTP = 0.30
ml
LTN = 6.11
Ib/yr
LTN = 16.93
IbJ
CTP = 2.53
Ib/yr
CTP = 3.38
lb/

3. SCM Characteristics
SCM Characteristics
Catchment ID
SCM 1D
Type of SCM
Predominant hydrologic soil
group at SCM location
SCM Description
Design Storm Size (inches/24hrs)
Percent of full Size
Hydrologic Value - Percent
Annual Effluent
Hydrologic Value - Percent
Annual Overflow
Hydrologic Value - Percent
Annual ET/Infiltrated
SCM Effluent TP EMC (mg/L)
SCM Effluent TN EMC (mg/L)
SCM Land Cover TP EMC (mg/L)
SCM Land Cover TN EMC (mg/L)
Drains to SCM ID
1
101
Stormwater Wetland per
MDC
C
Stormwater Wetland per
MDC
1.00
100%
1
102
1
103
59 %
16%
25%
0.18
1.12
0.11
1.18
0

3. SCM Characteristics
Catchment Routing
(Source Catchment)
Catchment 1
Catchment 2
Catchment 3
Catchment 4
Catchment 5
Catchment 6
Catchments Draining t+
sCM 101
no
SCM ID: 101
SCM Drainage Area Land Covers I
Area Draining Directly to
Roof
Road
Parking/Driveway/Sidewalk
Protected Forest
Other Pervious/Landscaping
CUSTOM LAND COVER 1
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKEN UP BY SCM
TOTAL AREA DRAINING TO SCM
(ft,):
CATCHMENT AREA (ft):
SCM 101(ft2)
10,640
I
25,057
3,906
7,950
47,553
47,553
Catchments Draining to
SCM 102
102
Area Draining Directly to
SCM 102 (ft2)
0
Catchments Draining to
SCM 103
103
Area Draining Directly to
SCM 103 (ft2)
0

3. SCM Characteristics
SCM Characteristics
Catchment ID
SCM ID
Type of SCM
Predominant hydrologic soil
group at SCM location
SCM Description
Design Storm Size (inches/24hrs)
Percent of Full Size
Hydrologic Value - Percent
Annual Effluent
Hydrologic Value - Percent
Annual ❑verflow
Hydrologic Value - Percent
Annual ET/Infiltrated
SCM Effluent TP EMC (mg/L)
SCM Effluent TN EMC (mg/L)
SCM Land Cover TP EMC (mg/L)
SCM Land Cover Thl EMC (mg/L)
Drains to SCM ID

3. SCM Characteristics
Catchment Routing
(Source Catchment)
Catchment 1
Catchment 2
Catchment 3
Catchment 4
Catchment 5
Catchment 6
SCM ID:
SCM Drainage Area Land Covers
Roof 4
ParkingMriveway/Sidewalk
Protected Forest
Other Pervious/Landscaping
CUSTOM LAND COVER 1
CUSTOM LAND COVER 2
CUSTOM LAND COVER 3
LAND TAKEN UP BY SCM
TOTAL AREA DRAINING TO SCM
(ft):
CATCHMENT AREA (ft):
Total Land Use Area
Treated By All SCMs (ft)
10,640
0
0
%906
0
0
0
7',950
47,553
Allowable Total Land Use
Area to be Treated Based
on Post-ft iect Areas (ft')
10,640
0
25,538
0
166,449
0
0
0
7.950
210,577
Post -Project Untreated
Land Area (ftZ)
0
0
481
0
162,543
0
0
0
0
163,024

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Nutrient Management Strategy Watershed - Nutrient Offset Credit Reporting Form
Please complete and submit the following information to the local government permitting your development project
to characterize it and assess the need to purchase nutrient offset credits. Contact and rule implementation
information can be found online at:
htt : de .nc. ov about divisions water -resources lannin non oint-source-mans ement nutrient -offset -
information
PROJECT INFORMATION
Applicant Name: Glandon Forest Equity, LLC
Project Name: Dollar General
Project Address: NC Hwy 54
Date: (mm/dd/yyyy) 12/20/2022
Development Land Use Type:
Commercial
County: Orange
Development Activity Type:
Development - New
Pre -Project Built -Upon Area %:
0.57%
Project Latitude:
35.923097
Post -Project Built -Upon -Area %:
17.18%
Project Longitude:
-79.177172
WATERSHED INFORMATION
Nutrient Management Watershed:
Jordan Lake
N Offsite Threshold Rate (lb/ac/yr):
10.00
Subwatershed:
Jordan - Upper New Hope
P Offske Threshold Rate (lb/ac/yr):
0.65
Nitrogen Delivery Zone:
Jordan - 050060
Nitrogen Delivery Factor:
79%
Phosphorus Delivery Zone:
Jordan - 050060
Phosphorus Delivery Factor:
73%
NUTRIENT OFFSET REQUEST
Nitrogen Load Offset Needs
(A)
(B)
(C)
(D)
(E)
(F)
(G)
(H) (L) (Where
Applicable)
Untreated
Treated
Loading Rate
Reduction
Project Size
Offset
Delivery
State Buy Local Gov't
Loading Rate
Loading Rate
Target
Need
(ac)
Duration (yrs}
Factor (/°)
Down Amount Buy Down
(Ibs/ae/yr)
(Ibs/ac/yr)
(Ibs/ac/yr)
(Ibs/ac/yr)
(Ibs) Amount (Ibs)
B -C
D"E"F`G
3.50
2.62
2.20
0.42
4.8342
30
79%
48.37
Phosphorus Load Offset Needs
(A)
(B)
(C}
(D)
(E)
(F)
(G)
(H) (L) (Where
Applicable)
Untreated
Treated Load
Loading Rate
Reduction
Project Size
Offset
Delivery
State Buy Local Gov't
Load Rate
Rate
Target
Need
(ac)
Duration (yrs)
Factor (%)
Down Amount Buy Down
Ibs/ac/
( r y)
Ibs/ac/
( r y)
(Ibs/aG r
y)
Ibs/aG r
( y)
Ibs Amount Ibs
( ) ( )
B-C
D`E-F*G
0.70
0.65
0.82
-0.17
4.8342
30
73%
0.00
LOCAL GOVERNMENT AUTHORIZATION
Local Government Name: I Orange County
Staff Name: -I Phnna
Staff Email:l 1 Date]
Local Government Authorizing Signature:

Bowman North Carolina, Ltd.
Dollar General - Chapel Hill, NC
Curve Number Calculation (CN)
Pre -Developed Conditions (Overall Site)
Drainaoe Area jacresl: 4.83
Exlsdnp .5011 Groin
50i1 Grout/ Map Symbol Soil Description Acres Percent of DA
C ApB Appling Sandy Loam 4.83 100%
Pr000sed_Land�Jses:
Land Use Description Existing Solt Group Acres Curve # Wert CN
Wooded - Good C 2.85 70 41.2
Impervious Area C 0.03 98 0.6
Open Space - Good C 1.96 78 31.6
Cumulative Curve # = 73.4

Bowman North Carolina, Ltd.
Dollar General - Chapel Hill, NC
Curve Number Calculation (CN)
Post -Developed Conditions (Stormwater Wetland)
Drainage Area (aeresl: 1.09
Existing Sail Group
soil Group Map Symbol Soil Description Acres Percent of DA
C ApB Appling Sandy Loam 1.09 100%
Proposed Land Uses:
Land Use Description Existing Soil Group Acres Curve # Wer�fed CN
Open Space - Good C 0.27 78 19.4
Impervious Area C 0.82 98 73.6
Cumulative Curve # = 93.0

Bowman North Carolina, Ltd.
Dollar General - Chapel Hill, NC
Curve Number Calculation
(CN)
Post -Developed Bypass Conditions
Drainage Area (acres.- 3.74
Existing Soil GrouQs.
Soil Grout/ Map Symbol Soil Description
Acres
Percent of DA
C ApB Appling Sandy Loam
3.74
100%
Proposed Land Uses:
Land Use Description Existing Soil_Group
Acres
Curve #
Weighted CN
Wooded - Good C
1.78
70
33.4
Impervious Area C
0.01
98
0.3
Open Space - Good C
1.95
78
40.6
Cumulative Curve # =
74.2

Project Information
Proposed Stormwater Wetland
Project Name: DG - Chapel Hill
Project #:
Designed by: CEP Date: 12/19/2022
Revised by: Date:
Checked by: Date:
Site Information
Sub Area Location: Drainage To Proposed Stormwater Wetland
Drainage Area (DA) = 1.09 Acres 47553 sf
Impervious Area (IA) = 0.82 Acres 35697 sf
Percent Impervious (1) = 75.07 %
Required WQv Storage Volume
Design Storm = 1 inch (Non -Coastal county)
Determine Rv Value = 0.05 + .009 (1) = 0.726 in/in
Storage Volume Required = 2,875 cf (above Permanent Pool)
Surface Area Requirements:
Storage Volume Required =
2,875
cf (above Permanent Pool)
Maximum ponding depth =
0.7
ft
Surface Area Required=
4,108
sf
Surface Area Provided=
5580
sf at temporary ool elev.
Breakdown of Surface Area:
Forebay
625.00
sf
11.2%
of Wetland Surface Area (10% to 15%)
Non-Forebay Deep Pools
380.00
sf
6.8%
of Wetland Surface Area (5% to 15%)
Shallow Water Zone
2020.00
sf
36.2%
of Wetland Surface Area (35% to 45%
Temporary Inundation Zone
1800.00
sf
32.3%
of Wetland Surface Area (30% to 45%
Total
4,825
sf
86.5%
of Wetland Surface Area

Incremental Drawdown Time
STORMWATER WETLAND
INCREMENTAL DRAWDOWN METHOD -Water Quality Volume
Project Information
Project Nar DG - Chapel Hill
Project #:
esigned by: CEP Date: 12/19/2022
iecked by: Date:
Water Quality Orifice
* Incremental Determination of Water Quality Volume Drawdown Time
Zone 2
Orifice Diameter (D) =
Cd =
Ei =
Zone 1 Range =
Zone 2 Range =
Zone 3 Range =
Q3 = 0.0437 Cp * D2 (Z-D/24-Ei)n11n1
Q2 = 0.372 CD * D*(Z-Ei)^(3/2)
Q,=0
0.9 in
0.6
354
Orifice Inv
0.00
to 354
354
to 354.1
354.1
to 355
Incremental Drawdown Method
Countour
Contour
Area
Incremental
Volume
Stage, Z
Zone
Q
Drawdown
Time
Sq ft
cu ft
ft
cfs
min
354.00
4.575
0
0.00
2.00
0.000
—
354.70
5580
3,554
0.70
3.00
0.010
5,935
Total
1
3,564
-
5,935
Drawdown Time = Incremental Volume / Q / 60sec/min
Summary
Total Volume = 3,654 cf
Total Time = 6,935 min
Total Time = 4.12 days
12/20/2022 Prop Wet Land -new design-ChapelHill.xls 1 of 1

Proposed Stormwater Wetland
Project Information
Project Name: DG - Chapel Hil
Project #:
Designed by: CEP
Revised by:
Checked by:
Site Information
Date:
Date:
Date:
12/19/2022
Sub Area Location: Drainage to Proposed Stormwater Wetland
Drainage Area (DA) _ _ 1.09 Acres
Impervious Area (IA) _ _ 0.82 Acres
Percent Impervious (1) = 75.07 % (Drainage Area)
Orifice Sizing
Orifice Size =
in
(Diameter)
Drawdown Time =
days
(Incremental Draw Down Method)
less than 5 days (yes/no) ?
yes
greater than 2 day (yes/no) ?
yes
Anti -Flotation Device
4' x 4' Outlet Structure
Area:
16.0
sf
Volume:
cf
(Water Displaced - Top of Pond to Bottom of Pond)
Weight:
2496
Ibs
Factor of Safety
1.20
WT Req'd of Anti -Flotation Device:
Ibs
Volume of Concrete Req'd:
cf
(Unit WT of Concrete = 150 pcf)
Volume Provided:
77.5
cf
(4'x4' riser x 2.5' = 40cf, 5'x5' footing x 1.5' = 37.5cf)

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STAGE/STORAGE TABLE
STAGE (FT)
ELEVATION (FT)
CONTOUR AREA
(SF)
INCREMENTAL
STORAGE (CF)
TOTAL STORAGE
(CF)
0.0
354.0
4575
0
0
0.7
354.7
5580
3554
3554 (WQV)
1.0
355.0
5980
1734
5288
2.0
356.0
7290
1 6635
1 11923
2.5
356.5
7940
1 3808
1 15731
STORMWATER MANAGEMENT DESIGN STORMWATER WETLAND:
RIVER BASIN:
RECEIVING STREAM:
STREAM INDEX:
STREAM CLASS:
HUC:
PROJECT COORDINATES:
POND DESIGN SUMMARY
CAPE FEAR
COLLINS CREEK
16-30-(0.5)
WS-V; NSW
0303000205
35.923097'N,-79.177172'W
DRAINAGE AREA TO POND: 1.09 ACRES
SITE IMPERVIOUS AREA TO POND: 0.82 ACRES
OFF -SITE DESIGN IMPERVIOUS AREA TO POND: 0.0 ACRES
TOTAL DESIGN IMPERVIOUS AREA TO POND: 0.82 ACRES
PRE -DEVELOPED POST -DEVELOPED POST DEVELOPED POST DEVELOPED POST DEVELOPED
TO POND TO POND THROUGH POND BYPASS COMBINED
DRAINAGE AREA: 4.83 AC 1.09 AC 3.74 AC
CURVE NUMBER: 73.4 93.0 74.2
TIME OF CONCENTRATION: 15.8 MIN 5 MIN 10 MIN
1.0" STORM EVENT:
0.413 CFS
0.011 CFS
1-YEAR STORM EVENT:
4.844 CFS
3.856 CFS
0.178 CFS
4.596 CFS
4.774 CFS
2-YEAR STORM EVENT:
7.335 CFS
4.810 CFS
0.342 CFS
6.859 CFS
7.201 CFS
10-YEAR STORM EVENT:
14.68 CFS
7.241 CFS
0.934 CFS
13.40 CFS
14.33 CFS
25-YEAR STORM EVENT:
19.42 CFS
8.683 CFS
1.385 CFS
17.62 CFS
19.01 CFS
100-YEAR STORM EVENT:
27.14 CFS
10.94 CFS
5.266 CFS
24.48 CFS
29.75 CFS

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Pond Report s
Hydraf low Hydrographs Extension for Autodesk(D Civil 3DO by Autodesk, Inc. v2022 Tuesday, 12 / 20 / 2022
Pond No. 1 - Stormwater Wetland Pond
Pond Data
Contours -User-defined contour areas. Average end area method used for volume calculation. Begining Elevation = 354.00 ft
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cult) Total storage (cult)
0.00 354.00 4,575 0 0
0.70 35470 5,580 3,554 3,554
1.00 355.00 5,980 1,734 5.288
2.00 356.00 7,290 6,635 11,923
2.50 35650 7,940 3,808 15,731
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[PrfRsr]
[A]
[B]
[C]
[D]
Rise (in)
= 15.00
0.90
Inactive
Inactive
Crest Len (ft)
= 0.33
15.67
Inactive
Inactive
Span (in)
= 15.00
0.90
0.00
0.00
Crest El. (ft)
= 354.70
355.90
0.00
0.00
No. Barrels
= 1
1
0
0
Weir Coeff.
= 3.33
2.60
3.33
3.33
Invert El. (ft)
= 354.00
354.00
0.00
0.00
Weir Type
= Rect
Broad
---
---
Length (ft)
= 15.00
1.00
0.00
0.00
Multi -Stage
= Yes
Yes
No
No
Slope (%)
= 3.33
0.50
0.00
n/a
N-Value
= .013
.013
.013
n/a
Orifice Coeff.
= 0.60
0.60
0.60
0.60
Exfl.(in/hr)
= 0.000 (by
Contour)
Multi -Stage
= n/a
Yes
No
No
TW Elev. (ft)
= 0.00
Stage (ft)
3.00
2.00
1.00
0.00 '-
0.00 1.00
Total 0
Note: CulverUOrifice oulflows are analyzed under inlet (ic) and outlet (oc) control. Weir risers checked for orifice conditions (ic) and submergence (s)
2.00
3.00
Stage / Discharge
4.00
5.00
6.00
700
8.00
Elev (ft)
357.00
356.00
355.00
1 354.00
9.00
Discharge (cfs)

1
Hydrograph Summary
Report
Hydraflow Hydrographs Extension for AutodeskO Civil 3DO by Autodesk, Inc. v2022
Hyd.
Hydrograph
Peak
Time
Time to
Hyd.
Inflow
Maximum
Total
Hydrograph
No.
type
flow
interval
Peak
volume
hyd(s)
elevation
strge used
Description
(origin)
(cfs)
(min)
(min)
(cult)
(ft)
(cuft)
1
SCS Runoff
4.844
2
724
14,471
--
------
Pre -Developed -Overall Site
2
SCS Runoff
3.856
2
716
8,184
------
Post Developed to Pond
3
Reservoir
0.178
2
782
7,488
2
354.98
5,149
Post Through Pond
4
SCS Runoff
4.596
2
722
12,416
- --
- -
Post Developed Bypass
6
SCS Runoff
0.413
2
144
1,671
-
- -
------
SCM Post -Developed
7
Reservoir
0.011
2
366
1,579
6
354.30
1,548
1.0-in Storm Thru Pond
Wetland_ChapelHill.gpw Return Period: 1 Year Tuesday, 12 / 20 / 2022

Hydrograph Report
2
Hydraflow Hydrographs Extension for Autodesk® Civil 31D® by Autodesk, Inc. v2022
Hyd. No. 1
Pre -Developed -Overall Site
Hydrograph type =
SCS Runoff
Storm frequency =
1 yrs
Time interval =
2 min
Drainage area =
4.830 ac
Basin Slope =
0.0 %
Tc method =
User
Total precip. =
2.95 in
Storm duration =
24 hrs
Q (cfs)
5.00
4.00
3.00
2.00
1.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Pre -Developed -Overall Site
Hyd. No. 1 -- 1 Year
Tuesday, 12 / 20 / 2022
= 4.844 cfs
= 724 min
= 14,471 cult
= 73.4
= 0 ft
= 15.80 min
= Type II
= 484
Q (cfs)
5.00
4.00
3.00
2.00
1.00
1 1 1 1 1 I I I I 1 I% . 0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph Report
3
Hydraflow Hydrographs Extension for Autodesk® Civil 3130 by Autodesk, Inc. v2022
Hyd. No. 2
Post Developed to Pond
Hydrograph type
= SCS Runoff
Storm frequency
= 1 yrs
Time interval
= 2 min
Drainage area
= 1.090 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 2.95 in
Storm duration
= 24 hrs
Q (cfs)
4.00
3.00
2.00
1.00
0.00
0 120
- Hyd No. 2
Tuesday, 12 / 20 / 2022
Peak discharge
= 3.856 cfs
Time to peak
= 716 min
Hyd. volume
= 8,184 cuft
Curve number
= 93
Hydraulic length
= 0 ft
Time of conc. (Tc)
= 5.00 min
Distribution
= Type II
Shape factor
= 484
Post Developed to Pond
Hyd. No. 2 -- 1 Year
240 360 480 600 720 840 960
Q (cfs)
4.00
3.00
2.00
1.00
0.00
1080 1200
Time (min)

Hydrograph Report
4
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 3
Post Through Pond
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 1 yrs
Time to peak
Time interval
= 2 min
Hyd. volume
Inflow hyd. No.
= 2 - Post Developed to Pond
Max. Elevation
Reservoir name
= Stormwater Wetland Pond
Max. Storage
Storage Indication method used.
Q (cfs)
4.00
3.00
2.00
1.00
Post Through Pond
Hyd. No. 3 -- 1 Year
Tuesday, 12 / 20 / 2022
= 0.178 cfs
= 782 min
= 7,488 cuft
= 354.98 ft
= 5,149 cult
600 1200 1800 2400 3000 3600 4200 4800 5400
Total storage used = 5,149 cult
Hyd No. 3 — Hyd No. 2
Q (cfs
4.00
3.00
W OM
1.00
0.00
6000
Time (min)

Hydrograph Report
6
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 4
Post Developed Bypass
Hydrograph type
= SCS Runoff
Storm frequency
= 1 yrs
Time interval
= 2 min
Drainage area
= 3.740 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 2.95 in
Storm duration
= 24 hrs
Q (cfs
5.00
4.00
3.00
2.00
1.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Post Developed Bypass
Hyd. No. 4 -- 1 Year
0.00 - -
0
Tuesday, 12 / 20 / 2022
= 4.596 cfs
= 722 min
12,416 cuft
74.2
= 0 ft
= 10.00 min
= Type II
= 484
120 240
Hyd No. 4
Q (cfs)
5.00
4.00
3.00
2.00
1.00
Wawa A"
360 480 600 720 840 960 1080 1200 1320 1440 1560v Vv
Time (min)

Hydrograph Report
7
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 6
SCM Post -Developed
Hydrograph type
- SCS Runoff
Storm frequency
= 1 yrs
Time interval
= 2 min
Drainage area
= 1.090 ac
Basin Slope
= 0.0 %
Tc method
- User
Total precip.
= 1.00 in
Storm duration
= 6.00 hrs
Tuesday, 12 / 20 / 2022
Peak discharge
= 0.413 cfs
Time to peak
= 144 min
Hyd. volume
= 1,671 cuft
Curve number
= 93
Hydraulic length
= 0 ft
Time of conc. (Tc)
= 5.00 min
Distribution
= SCS 6-Hr
Shape factor
= 484
SCM Post -Developed
Q (cfs) Hyd. No. 6 -- 1 Year
0.50
i
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0 00
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0 00
0 60 120 180 240 300 360 420
Hyd No. 6 Time (min)

Hydrograph Report
8
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 7
1.0-in Storm Thru Pond
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 1 yrs
Time to peak
Time interval
= 2 min
Hyd. volume
Inflow hyd. No.
= 6 - SCM Post -Developed
Max. Elevation
Reservoir name
= Stormwater Wetland Pond
Max. Storage
Storage Indication method used.
1.0-in Storm Thru Pond
Tuesday, 12 / 20 / 2022
= 0.011 cfs
= 366 min
= 1,579 cuft
= 354.30 ft
= 1,548 cuft
Q (cfs) Hyd. No. 7 -- 1 Year Q (cfs)
0.50 - 0.50
i
I
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
0.00 - J 0.00
0 480 960 1440 1920 2400 2880 3360 3840 4320 4800 5280
Time (min)
Hyd No. 7 Hyd No. 6 Total storage used = 1,548 cult

Hydrograph Summary Report
10
Hydraflow Hydrographs Extension for Autodesk® Civil 3DO by Autodesk, Inc. v2022
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cult)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
------
Hydrograph
Description
1
SCS Runoff
7.335
2
724
21,274
-
— -
Pre -Developed -Overall Site
2
SCS Runoff
4.810
2
716
10,360
-
------
------
Post Developed to Pond
3
Reservoir
0.342
2
750
9,649
2
355.14
6,219
Post Through Pond
4
SCS Runoff
6.859
2
722
18,116
---
------
Post Developed Bypass
6
SCS Runoff
0.000
2
n/a
0
----
------
----
SCM Post -Developed
7
Reservoir
0.000
2
n/a
0
6
354.00
0.000
1.0-in Storm Thru Pond
Wetland_ChapelHill.gpw
Return Period: 2 Year
Tuesday, 12 / 20 / 2022

Hydrograph Report
11
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 1
Pre -Developed -Overall Site
Hydrograph type =
SCS Runoff
Storm frequency =
2 yrs
Time interval =
2 min
Drainage area =
4.830 ac
Basin Slope =
0.0 %
Tc method =
User
Total precip. =
3.56 in
Storm duration =
24 hrs
Q (cfs)
8.00
. 10
4.00
2.00
120 240
Hyd No. 1
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Pre -Developed -Overall Site
Hyd. No. 1 -- 2 Year
360 480 600 720 840 960
Tuesday, 12 / 20 / 2022
= 7.335 cfs
= 724 min
= 21,274 tuft
= 73.4
= 0 ft
= 15.80 min
= Type II
= 484
Q (cfs)
8.00
M
4.00
2.00
— 0.00
1080 1200 1320 1440 1560
Time (min)

Hydrograph Report
12
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 2
Post Developed to Pond
Hydrograph type
= SCS Runoff
Storm frequency
= 2 yrs
Time interval
= 2 min
Drainage area
= 1.090 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 3.56 in
Storm duration
= 24 hrs
Tuesday, 12 / 20 / 2022
Peak discharge
= 4.810 cfs
Time to peak
T 716 min
Hyd. volume
= 10,360 cuft
Curve number
= 93
Hydraulic length
= 0 ft
Time of conc. (Tc)
= 5.00 min
Distribution
Type II
Shape factor
= 484
Post Developed to Pond
Q (cfs) Hyd. No. 2 -- 2 Year Q (cfs)
5.00 I 5.00
4.00 - 4.00
3.00 3.00
2.00 2.00
1.00 1.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200
-- Hyd No. 2 Time (min)

IHydrograph Report
13
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 3
Post Through Pond
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 2 yrs
Time to peak
Time interval
= 2 min
Hyd. volume
Inflow hyd. No.
= 2 - Post Developed to Pond
Max. Elevation
Reservoir name
= Stormwater Wetland Pond
Max. Storage
Storage Indication method used.
Q (cfs)
5.00
4.00
3.00
2.00
1.00
Post Through Pond
Hyd. No. 3 -- 2 Year
600 1200 1800 2400
Hyd No. 3 Hyd No. 2
Tuesday, 12 / 20 / 2022
= 0.342 cfs
= 750 min
= 9,649 cuft
= 355.14 ft
= 6,219 cult
3000 3600 4200 4800
___ Total storage used = 6,219 cuft
Q (cfs
5.00
4.00 1
3.00
2.00
1.00
�J- 0.00
5400 6000
Time (min)

Hydrograph Report
14
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc v2022
Hyd. No. 4
Post Developed Bypass
Hydrograph type
= SCS Runoff
Storm frequency
= 2 yrs
Time interval
= 2 min
Drainage area
= 3.740 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 3.56 in
Storm duration
= 24 hrs
Q (cfs)
7.00
. M
5.00
4.00
3.00
2.00
1.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Post Developed Bypass
Hyd. No. 4 -- 2 Year
Tuesday, 12 / 20 / 2022
= 6.859 cfs
= 722 min
= 18,116 cuft
= 74.2
= 0 ft
= 10.00 min
= Type II
= 484
Q (cfs)
7.00
. 1M
5.00
4.00
3.00
2.00
1.00
0.00 ' r r - 1 I I I 1 1 n ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

Hydrograph Summary Report
17
Hydraf low Hydrographs Extension for AutodeskO Civil 3DO by Autodesk, Inc. v2022
Hyd.
No.
Hydrograph
type
(origin)
(Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cult)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
14.68
2
722
41,316
------
--
------
Pre -Developed -Overall Site
2
SCS Runoff
7.241
2
716
16,045
-
--
-
Post Developed to Pond
3
Reservoir
0.934
2
728
15,311
2
355.58
9,154
Post Through Pond
4
SCS Runoff
13.40
2
720
34,800
-
--
--
Post Developed Bypass
6
SCS Runoff
0.000
2
n/a
0
-
------
-
SCM Post -Developed
7
Reservoir
0.000
2
n/a
0
6
354.00
0.000
1.0-in Storm Thru Pond
Wetland_ChapelHill.gpw
Return Period:
10 Year
Tuesday, 12
/ 20 / 2022

Hydrograph Report
18
Hydraflow Hydrographs Extension for Autodesk® Civil 31D® by Autodesk, Inc. v2022
Hyd. No. 1
Pre -Developed -Overall Site
Hydrograph type =
SCS Runoff
Storm frequency =
10 yrs
Time interval =
2 min
Drainage area =
4.830 ac
Basin Slope =
0.0 %
Tc method =
User
Total precip. =
5.13 in
Storm duration =
24 hrs
12.00
• R
. ��
3.00
M
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Pre -Developed -Overall Site
Hyd. No. 1 -- 10 Year
120 240 360 480 600 720 840
Hyd No. 1
Tuesday, 12 / 20 / 2022
= 14.68 cfs
= 722 min
= 41,316 cuft
= 73.4
= 0 ft
= 15.80 min
= Type II
= 484
Q (cfs)
15.00
12.00
M
.W
3.00
0.00
960 1080 1200 1320 1440 1560
Time (min)

Hydrograph Report
19
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 2
Post Developed to Pond
Hydrograph type
= SCS Runoff
Storm frequency
= 10 yrs
Time interval
= 2 min
Drainage area
= 1.090 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 5.13 in
Storm duration
= 24 hrs
M
4.00
2.00
0.00
0 120
Hyd No. 2
Tuesday, 12 / 20 12022
Peak discharge
= 7.241 cfs
Time to peak
= 716 min
Hyd. volume
= 16,045 cuft
Curve number
- 93
Hydraulic length
= 0 ft
Time of conc. (Tc)
= 5.00 min
Distribution
= Type II
Shape factor
- 484
Post Developed to Pond
Hyd. No. 2 -- 10 Year
240 360 480 600 720 840 960
Q (cfs)
8.00
. M
4.00
2.00
0.00
1080 1200
Time (min)

Hydrograph Report
20
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 3
Post Through Pond
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 10 yrs
Time to peak
Time interval
= 2 min
Hyd. volume
Inflow hyd. No.
= 2 - Post Developed to Pond
Max. Elevation
Reservoir name
= Stormwater Wetland Pond
Max. Storage
Storage Indication method used.
Q (cfs)
8.00
M
4.00
2.00
Post Through Pond
Hyd. No. 3 -- 10 Year
480 960 1440 1920 2400 2880
Hyd No. 3 Hyd No. 2
Tuesday, 12 / 20 / 2022
= 0.934 cfs
= 728 min
= 15,311 cuft
= 355.58 ft
= 9,154 cuft
Q (cfs)
8.00
4.00
2.00
0.00
3360 3840 4320 4800 5280
Time (min)
Total storage used = 9,154 cult

Hydrograph Report
21
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 4
Post Developed Bypass
Hydrograph type
= SCS Runoff
Storm frequency
= 10 yrs
Time interval
= 2 min
Drainage area
= 3.740 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 5.13 in
Storm duration
= 24 hrs
Q (cfs
14.00
12.00
10.00
:M$
Me M
4.00
2.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Post Developed Bypass
Hyd. No. 4 -- 10 Year
0.00
0
Tuesday, 12 / 20 / 2022
= 13.40 cfs
= 720 min
= 34,800 cult
= 74.2
0 ft
10.00 min
= Type II
= 484
Q (cfs)
14.00
12.00
10.00
4.00
2.00
�1t
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

Hydrograph Summary Report
24
Hydraflow Hydrographs Extension for AutodeskO Civil 3DO by Autodesk, Inc. v2022
Hyd.
No.
Hydrograph
type
(origin)
SCS Runoff
Peak
flow
(cfs)
19.42
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cult)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
- -
Hydrograph
Description
1
2
722
54,455
------
Pre -Developed -Overall Site
2
SCS Runoff
8.683
2
716
19,481
- --
---
----
Post Developed to Pond
3
Reservoir
1.385
2
726
18,736
2
355.85
10,947
Post Through Pond
4
SCS Runoff
17.62
2
720
45,688
------
--
-
Post Developed Bypass
6
SCS Runoff
0.000
2
n/a
0
-------
------
------
SCM Post -Developed
7
Reservoir
0.000
2
n/a
0
6
354.00
0.000
1.0-in Storm Thru Pond
Wetland_ChapelHill.gpw
Return Period: 25 Year
Tuesday, 12 / 20 / 2022

Hydrograph Report
25
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 1
Pre -Developed -Overall Site
Hydrograph type =
SCS Runoff
Storm frequency =
25 yrs
Time interval =
2 min
Drainage area =
4.830 ac
Basin Slope =
0.0 %
Tc method =
User
Total precip. =
6.07 in
Storm duration =
24 hrs
18.00
15.00
12.00
M
3.00
M
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Pre -Developed -Overall Site
Hyd. No. 1 -- 25 Year
Tuesday, 12 / 20 / 2022
= 19.42 cfs
= 722 min
= 54,455 cuft
= 73.4
= 0 ft
= 15.80 min
= Type II
= 484
Q (cfs)
21.00
18.00
15.00
12.00
• ee
NOR
3.00
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph report
26
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 2
Post Developed to Pond
Hydrograph type
= SCS Runoff
Storm frequency
= 25 yrs
Time interval
= 2 min
Drainage area
= 1.090 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 6.07 in
Storm duration
= 24 hrs
Tuesday, 12 / 20 / 2022
Peak discharge
= 8.683 cfs
Time to peak
= 716 min
Hyd. volume
= 19,481 cuft
Curve number
= 93
Hydraulic length
= 0 ft
Time of conc. (Tc)
= 5.00 min
Distribution
= Type II
Shape factor
= 484
Post Developed to Pond
Q (cfs) Hyd. No. 2 -- 25 Year Q (cfs)
10.00 10.00
8.00 8.00
6.00 6.00
4.00 4.00
2.00 2.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200
Hyd No. 2 Time (min)

Hydrograph Report
27
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 3
Post Through Pond
Hydrograph type
= Reservoir
Peak discharge
Storm frequency
= 25 yrs
Time to peak
Time interval
= 2 min
Hyd. volume
Inflow hyd. No.
= 2 - Post Developed to Pond
Max. Elevation
Reservoir name
= Stormwater Wetland Pond
Max. Storage
Storage Indication method used.
Tuesday, 12 / 20 / 2022
= 1.385 cfs
= 726 min
= 18,736 cuft
= 355.85 ft
= 10,947 cult
Post Through Pond
Q (cfs) Hyd. No. 3 -- 25 Year Q (cfs)
10.00 10.00
8.00 8.00
6.00 6.00
4.00 4.00
2.00 2.00
0.00 - - 0.00
0 240 480 720 960 1200 1440 1680 1920 2160 2400 2640 2880 3120
Time (min)
Hyd No. 3 Hyd No. 2 - _ 'I Total storage used = 10,947 cult

Hydrograph Report
28
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 4
Post Developed Bypass
Hydrograph type
= SCS Runoff
Storm frequency
= 25 yrs
Time interval
= 2 min
Drainage area
= 3.740 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 6.07 in
Storm duration
= 24 hrs
15.00
12.00
•M
. ��
3.00
Tuesday, 12 / 20 / 2022
17.62 cfs
= 720 min
= 45,688 cuft
= 74.2
= 0 ft
= 10.00 min
Type II
= 484
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Post Developed Bypass
Hyd. No. 4 -- 25 Year
Q (cfs)
18.00
15.00
12.00
3.00
0.00 -1 . J.. I- I I I— I I I I '- 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

Hydrograph Summary Report
31
Hydraflow Hydrographs Extension for AutodeskO Civil 3DO by Autodesk, Inc. v2022
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow 1 Maximum
hyd(s) elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
27.14
2
722
76,209
--
—
Pre -Developed -Overall Site
2
SCS Runoff
10-94
2
716
24,913
------
------
Post Developed to Pond
3
Reservoir
5.266
2
722
24,157
2
356.10
12,706
Post Through Pond
4
SCS Runoff
24.48
2
720
63,670
-
Post Developed Bypass
6
SCS Runoff
0.000
2
n/a
0
--
----
--
SCM Post -Developed
7
Reservoir
0.000
2
n/a
0
6
354.00
0.000
1.0-in Storm Thru Pond
Wetland_ChapelHill.gpw
Return Period:
100
Year
Tuesday, 12
/ 20 / 2022

Hydrograph Report
32
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 1
Pre -Developed -Overall Site
Hydrograph type =
SCS Runoff
Storm frequency =
100 yrs
Time interval =
2 min
Drainage area =
4.830 ac
Basin Slope =
0.0 %
Tc method =
User
Total precip. =
7.55 in
Storm duration =
24 hrs
Q (cfs
28.00
24.00
20.00
16.00
12.00
:M
4.00
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Pre -Developed -Overall Site
Hyd. No. 1 -- 100 Year
0.00 -
0
Tuesday, 12 / 20 / 2022
= 27.14 cfs
= 722 min
= 76,209 cuft
= 73.4
= 0 ft
= 15.80 min
= Type II
= 484
Q (cfs)
28.00
24.00
20.00
16.00
12.00
1 e.
4.00
RiTil
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

33
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 31D® by Autodesk, Inc. v2022
Tuesday, 12 / 20 / 2022
Hyd. No. 2
Post Developed to Pond
Hydrograph type
= SCS Runoff
Peak discharge
= 10.94 cfs
Storm frequency
= 100 yrs
Time to peak
= 716 min
Time interval
= 2 min
Hyd. volume
= 24,913 cuft
Drainage area
= 1.090 ac
Curve number
= 93
Basin Slope
= 0.0 %
Hydraulic length
= .0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 7.55 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
10.00
M
.W
M OR
2.00
we
Post Developed to Pond
Hyd. No. 2 -- 100 Year
120 240 360 480 600
Hyd No. 2
Q (cfs)
12.00
10.00
.m
4.0.0
2.00
0.00
720 840 960 1080 1200
Time (min)

Hydrograph
Report
34
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Tuesday, 12 / 20 / 2022
Hyd. No. 3
Post Through Pond
Hydrograph type
= Reservoir
Peak discharge
= 5.266 cfs
Storm frequency
= 100 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 24,157 cuft
Inflow hyd. No.
= 2 - Post Developed to Pond
Max. Elevation
= 356.10 ft
Reservoir name
= Stormwater Wetland Pond
Max. Storage
= 12,706 cuft
Storage Indication method used
Q (cfs
12.00
10.00
M
AM
4.00
2.00
Post Through Pond
Hyd. No. 3 -- 100 Year
Q (cfs)
12.00
10.00
EMS
-MU
2.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
Hyd No. 3 - Hyd No. 2 _ _ Total storage used = 12,706 cuft

Hydrograph Report
35
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2022
Hyd. No. 4
Post Developed Bypass
Hydrograph type
= SCS Runoff
Storm frequency
= 100 yrs
Time interval
= 2 min
Drainage area
= 3.740 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 7.55 in
Storm duration
= 24 hrs
Q (cfs)
28.00
24.00
20.00
16.00
12.00
R
MOM
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Post Developed Bypass
Hyd. No. 4 -- 100 Year
Tuesday, 12 / 20 / 2022
= 24.48 cfs
= 720 min
= 63,670 cuft
= 74.2
= 0 ft
= 10.00 min
= Type II
= 484
Q (cfs)
28.00
24.00
20.00
16.00
12.00
M
4.00
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
Hyd No. 4

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Triangle Site Design, PLLC
Dollar General Chapel Hill, NC - Storm Drain "C" calculations
Rational Runoff Coefficient "C"
Catch Basin#101
DmOareArea (acres}: 0.16
p+ovosed Land uses. -
Land Use Desaipdon
Acres
% Site
Runoff "C"
Roofs
0.00
0%
0.95
0.00
Asphalt/Concrete Pavement
0.16
100%
0.95
0.95
Lawn
0.00
0%
0.3
0.00
Wooded
0.00
0%
0.2
0.00
Total Area=
0.16
Cumulative "C° =
OAS
1
iio=
7.38
Q1o=
1.14
Catch Basin#102
Drainaoe Area Iacresl: 0.11
Pipposed Land Uses:
Land Use Description
Acres
° Site
Runoff "C"
"C"
Roofs
0.00
0%
0.95
0.00
Asphalt/Concrete Pavement
0.11
100%
0.95
0.95
Lawn
0.00
0%
0.3
0.00
Wooded
0.00
0%
0.2
0,00
Total Area=
0.11
Cumulative "C" =
0,95
1
ilo=
7.38
Q1o=
0.75
SD. Cleanout#103
d1hVme Area La 0.12
Pressed Land Uses.•
Land
Use Description
Acres
% Site
Runoff "C"
"C"
Roofs
0.12
100%
0.95
0.95
Asphalt/Concrete Pavement
0.00
0%
0.95
0.00
Lawn
0.00
0%
0.3
0.00
Wooded
0.00
0%
0.2
0.00
Total Area=
0.12
Cumulative "C" =
0.95
1
110=
7.38
Q1o=
0.84
SD Cleanout#104
Drainaae Area (acres}: 0.12
Land Use Description
Roofs
Asphalt/Concrete Pavement
Lawn
Wooded
Total Area=
Acres
° Sife
0.12
100%
0.00
0%
0.00
0%
0.00
0%
0.12
cumulatly6'C`=
i1o=
Q10=
Runoff "C"
"C"
0.95
0.95
0.95
0.00
0.3
0.00
0.2
0.00
0.95
7.38
0.84

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EROSION CONTROL CALCULATIONS

EROSION CONTROL CALCS (RIP -RAP CALCULATIONS)
Project Information
Rip -Rao Aaron#1
Project Name:
Chapel Hill (DG)
Project #:
004-229
Designed by:
13N1
Date:
1212012022
Revised by:
Date:
Checked by:
Date:
Pipe Diameter
d=
15
Pipe Slope
s=
3.33 %
Manning's number
n=
0.013
Flow
Q=
0.934 cfs
Velocity
V =
5.73 ft/s
Dissipator Dimensions
Zone =
2
Stone Filling Class =
B
Entry Width ( 3 X Do ) =
3.8 ft
Length (6 X Do) =
7.5 ft
Width (La + Do) =
8.8 ft
Min. Thickness =
22 inches
Min. Stone Diamete—
6 inches
All units are in feet
" Dissipator pad designed for full flow of pipe
i
31
RIP-RAP.xls 12/20/2022 Page 1 of 5

Rio -Ran Aoron#2
Pipe Diameter
d= Flume
in
Pipe Slope
s=
20 %
Manning's number
n=
0.013
Flow
Q=
2 cfs
Velocity
V =
2.00 ft/s
Dissipator Dimensions `
Zone =
2
Stone Filling Class = B
Entry Width ( 3 X Do ) =
5.0 ft
Length ( 6 X Do ) =
6.0 ft
Width (La + Do) =
7.0 ft
Min. Thickness =
22 inches
Min. Stone Diamete—
6 inches
All units are in feet
— Dissipator pad designed for full flow of pipe
RIP-RAP.xls 12/20/2022 Page 2 of 5

Rip -Rap Apron#3
Pipe Diameter
d= Flume
in
Pipe Slope
s=
20 %
Manning's number
n=
0.013
Flow
IV Q= 4
2 cfs 1 4
Velocity
V =
2.00 ft/s
Dissipator Dimensions *
Zone =
2
Stone Filling Class = B
Entry Width ( 3 X AO ) =
5.0 ft
Length (6XAO) =
6.0ft
Width (La + AO) =
7.0 ft
Min. Thickness =
22 inches
Min. Stone Diameter--
6 inches
6.0
50 7.0
* All units are in feet
- Dissipator pad designed for full flow of pipe
4
RIP-RAP.xIs 12/20/2022 Page 3 of 5

Rio -Rao Aoron#4
Pipe Diameter
d=
15 in
Pipe Slope
s=
1 %
Manning's number
n=
0.013
Flow
4 Q= 4
3.57 cfs
Velocity
V =
5.39 ft/s
Dissipator Dimensions
Zone = 4
2
Stone Filling Class =
B
Entry Width ( 3 X AO ) =
3.8 ft
Length (6 X AO) =
7.5 ft
Width (La + AO) =
8.8 ft
Min. Thickness =
22 inches
Min. Stone Diamete—
6 inches
■ 7.5 ►
All units are in feet
" Dissipator pad designed for full flow of pipe
RIP-RAP.xIs 12/20/2022 Page 4 of 5

Rio -Rao Aoron#5
Pipe Diameter
d=
15 in
Pipe Slope
s=
0.6 %
Manning's number
n=
0.013
Flow
14 Q= 4
2 cfs
Velocity
V =
2.00 fds
Dissipator Dimensions *
Zone = 4
2
Stone Filling Class =
B
Entry Width ( 3 X AO ) =
3.8 ft
Length (6 X AO) =
7.5 It
Width (La + AO) =
8.8 ft
Min. Thickness =
22 inches
Min. Stone Diameter—
6 inches
All units are in feet
— Dissipator pad designed for full flow of pipe
RIP-RAP.xls 12/20/2022 Page 5 of 5

EROSION CONTROL CALCS (SKIMMER BASINS)
Project Information
Project Name:
DG-Chappl bill
Project M
004-229
Designed by:
8M
Dale: 5123f2022
Revised by:
Date:
Checked by:
Date:
Skimmer Basin 111,11
Drainage Area
Total, AT=
2.8 Ac
Disturbed, An=
2.8 Ac
10-year Runoff (Q10)
C =
0.50
T. =
5.00 min
I,o =
7.38 in/hr
070 =
10.3 cfs
Surface Area Required
SA =
325sf x Q,e
SA =
3,358 sf
Volume Required
VR =
1800 cf/Ac x Ao
Va =
5,040 cf
Sediment Trap Dimensions
L =
120 ft (Spillway Length)
W =
32 ft (Spillway Width)
D =
2.0 ft (Depth of Storage)
Side Slopes =
2 1
L.. _
Lr. =
128 it
Lam,=
112 11 Wi.,
W10
W,.=
40 f1
Lz:=
Ws,=
24 ft
UW Ratio=
3.8 :1 (must be 2:1 to 6:1)
Elevations
Descni)Uon
Elevation
Top of Berm
555.00 (allow 1ft freeboard above spillway flow height)
Emergency Spillway
553.50
Sediment Storage
553.00
Cleanout Mark
552.00 (half of storage height)
Bottom
551.00
Provided
SAP=
3,840 sf > 3,358
Vp =
6,528.0 cf > 5,040
Emergency Spillway -10 Year Storm
I,p =
7.38 in/hr
also
10.33 cfs
h =
0.5 ft
C„ =
3
Lw=
10 ft

Calculate Skimmer Size
Basin Volume in Cubic Feet 6,528 CuFt Skimmer Size 2.0 Inch
Days to Drain' 3 Days Orifice Radius 0.8 Inch[es]
Orifice Diameter 1.6 Inch[es]
In NC assume 3 days to drain
Estimate Volume of Basin Length width
Top of water surface in feet 120 32 Feet VOLUME 6528 Cu. Ft.
Bottom dimensions in feet 112 24 Feet
Depth in feet 2 Feet

EROSION CONTROL CALCS (SKIMMER BASINS)
Project Information
Project Name:
Project #:
Designed by: Date: _
Revised by: Date: _
Checked by: Date:
Anti -Flotation Device
4' x 4' Outlet Structure
Area:
16.0
sf
Top of Basin Elev.:
553.0
Bottom of Basin Elev.:
551.0
Volume:
32.0
cf
Weight:
1997
Ibs
Factor of Safety
1.20
WT Req'd of Anti -Flotation Device:
2,396
Ibs
Volume of Concrete Req'd:
16.0
cf
Volume Provided:
69.5
cf
(Water Displaced - Top of Pond to Bottom of Pond)
(Unit WT of Concrete = 150 pcf)
(4'x4' riser x 2.0' = 32cf, 5'x5' footing x 1.5'=37.5cf)

5/23/22, 1:53 PM
NORTH
AMERICAN
GREEN
CHANNEL ANALYSIS
> > > Temporary Dit h 1
Name
Temporary Ditch #1
Discharge
10.3
Channel Slope
0.0037
Channel Bottom Width
1
Left Side Slope
2
Right Side Slope
2
Low Flow Liner
Retardence Class
C 6-12 in
Vegetation Type
None
Vegetation Density
None
Soil Type
Sandy Loam (GM)
DS75
ECMDS 7.0
North American Green
5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Depth Mannings N Shear Stress Shear Stress Factor Remarks Pattern
DS75 Straight 10.3 cfs 1.94 ft/s 1.4 ft 0.038 1.6 Ibs/ft2 0,32 Ibs/ft2 4.95 STABLE D
Unvegetated
Underlying Straight 10.3 cfs 1.94 ft/s 1.4 ft 0.038 1.51 Ibs/ft2 0.17 Ibs/ft2 8.96 STABLE D
Substrate
https://ecmds.com/project/139235/channel-analysis/208780/show 1/1

5/23/22. 1:58 PM
NORTH
AMERICAN
GREEN
CHANNEL ANALYSIS
> > > Temporary Dit h 2
Name
Temporary Ditch #2
Discharge
10.3
Channel Slope
0.033
Channel Bottom Width
1
Left Side Slope
2
Right Side Slope
2
Low Flow Liner
Retardence Class
C 6-12 in
Vegetation Type
None
Vegetation Density
None
Soil Type
Sandy Loam (GM)
DS150
ECMDS 7.0
North American Green
5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
Tel. [phone]
> Fax [phone]
www.nagreen.com
ECMDS v7.0
Phase
Reach
Discharge
Velocity
Normal
Mannings N
Permissible
Calculated
Safety Remarks
Staple
Depth
Shear Stress
Shear Stress
Factor
Pattern
uS15u Straight 10.3 cfs 4.62 ft/s
Unvegetated
Underlying Straight 10.3 cfs 4.62 ft/s
Substrate
0.83 ft 0.035 1.8 Ibs/ft2
0.83 ft 0.035 1.7 Ibs/ft2
1.72lbs/ft2 1.05 STABLE D
0.97lbs/ft2 1.76 STABLE D
https://eemds.com/projecVl39235/channel-analysis/208780/show 1 /1

5/23/22, 2:00 PM
NORTH
AMERICAN
GREEN'
CHANNEL ANALYSIS
> > > Temporary Dit h
Name
Temporary Ditch #3
Discharge
10.3
Channel Slope
0.005
Channel Bottom Width
1
Left Side Slope
2
Right Side Slope
2
Low Flow Liner
Retardence Class
C 6-12 in
Vegetation Type
None
Vegetation Density
None
Soil Type
Sandy Loam (GM)
DS75
ECMDS 7.0
North American Green
5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
Tel. [phone]
> Fax [phone]
www.nagreen.com
ECMDS v7.0
Normal Permissible Calculated Safety Remarks Staple
Phase Reach Discharge Velocity Depth Mannings N Shear Stress I Shear Stress Factor Pattern
DS75 Straight 10.3 cfs 2.22 ft/s 1.29 ft 0.037 1.6 Ibs/ft2 0.4 Ibs/ft2 3.96 STABLE D
Unvegetated
Underlying Straight 10.3 cfs 2.22 ft/s 1.29 ft 0.037 1.51 Ibs/ft2 0.21 Ibs/ft2 7.1 STABLE D
Substrate
https://ecmds.Gom/project/139235/channel-analysis/208780/show 1 /1