SW6230902_Design Calculations_20230913

Bowman
N O R T H C A R O L I N A
Erwin Road Residential
1504 Erwin Road
Proposed Residential Development and Associated Infrastructure
Dunn, North Carolina
COORDINATES: 35°18'55.1"N, 78°38'22.2"W
Project No.: 220124-01-004
Stormwater Management Report
Prepared By:
Bowman
NO R T H CAROL IN A
4006 Barrett Drive, Suite 104 CA�V r ��
Raleigh, NC 27609 tiQ�tisS/LJ
PREPARED FOR: 4` BEAL
ai gnat�a��titi
Stout Land Development, LLC
1786 Metromedical Drive Matt Lowder, PE
Fayetteville, NC 28304 NC License No. 24434
Ben Stout [phone]
[phone] [e-mail]
[e-mail]
AUGUST 18, 2023
TABLE OF CONTENTS
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Stormwater Management Narrative PAGE
• Project Data 3
• Site History 3
• Project Description 4
• Design Requirements 5
• Methodology 5
• System Summary 6
• Conclusion 6
Appendix A: Figures 10
• Soil Report
• Topography Map
• FEMA Flood Map No. 3720150600J
• Surface Water Classification Maps
• Hydrologic Unit Code (HUC)
• NOAA Point Precipitation Depth Estimates
• NOAA Point Precipitation Intensity Estimates
• Pre-Development Drainage Basin Map
• Post-Development Drainage Basin Map
• Wetlands Inventory Map
Appendix B: Stormwater Wet Pond Calculations 12
• CN Values
• Time of Concentration Calculations
• Wet Pond — Design, Details, and Hydrographs
• Grass Channels
• Spread Calculations
Appendix C: Storm Drainage System Calculations 13
• 100-System
Appendix D: Erosion and Sediment Control Calculations 14
• Rip Rap Calculations
• Skimmer Basin
• Riser
• Temporary Diversion Ditches
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STORMWATER MANAGEMENT NARRATIVE
This report documents the hydraulic and hydrological analysis performed by Bowman Consulting
for the proposed Erwin Road Residential site expansion in Dunn, North Carolina. The report
consists of a review of available hydrologic data, methods analysis, development of existing and
proposed hydraulic models, and presentation of the impacts of the proposed development in the
project.
PROJECT DATA
Table 1:Site Information
Project Name Erwin Road Residential
Parcel Identification Number (PIN) 1506795869
Parcel Address 1504 Erwin Road
River Basin Cape Fear
Total Parcel Area 9.04 acres (± 393,826 SF)
EXISTING
0 acres (±0 SF)
Impervious Area
PROPOSED
1.88 acres (±82,050 SF)
Area of Land Disturbance 8.90 acres (± 387,684 SF)
TMDLs None
Watershed Protection Overlay None
SITE HISTORY
The proposed site is located in Dunn, North Carolina and is within City of Dunn limits. The site is
located South of US HWY 421, West of Downton Dunn, and North of Erwin Road. The site is
currently undeveloped wooded and open space area.
Soils located within the project site as defined by NRCS (National Resources Conservation
Service) are described in Table 2.
Table 2:Hydrologic Soil Groups
Group Description
Bb Bibb soils, frequently flooded
NoB Norfolk loamy sand, 2 to 6 percent slopes
NoC Norfolk loamy sand, 6 to 10 percent slopes
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The hydrologic soil group (HSG) designations for these soils are groups B, C, and D, respectively.
Group B soils are described as coarse and having a moderate infiltration rate when thoroughly
wet. This consists of moderately deep or deep and moderately well to well drained soils that have
a moderate rate water transmission. Group C soils are defined as having a slow infiltration rate
when thoroughly wet.These soils are fine and have a layer that impedes the downward movement
of water. Group D soils are best described as having a very slow infiltration rate and high runoff
potential when thoroughly wet. A Web Soil Survey Map for the site is included in Appendix A.
For the purposes of design, the same hydrologic group was utilized for both Pre- and Post-
Development conditions.
PROJECT DESCRIPTION
Stout Land Development, LLC is proposing to develop±8.90 acres of disturbed area within the
9.04-acre parcel. The proposed development consists of 27 houses each with a footprint of
1,230 SF, stormwater control measures, and associated pavement, including parking areas,
driveways, and curbs.
Watershed Protection Overlay
Based on Harnett County GIS, the site is not located within a watershed protection area.
Floodplains
A portion of the Erwin Road parcel is located within Zone 'X' and 'AE', per the FEMA Panel
3720150600J located in Appendix A. No proposed fill will be placed in the floodplains. Because
the post-developed conditions will not result in a net increase in runoff from the site, no adverse
downstream impacts are expected to occur.
DESIGN REQUIRMENTS
Stormwater design was based on the standards presented in the North Carolina Department of
Environmental Quality (NCDEQ) Stormwater Design Manual.
Post-development rates for the site were designed to not exceed pre-development discharge
rates for the 1-year, 2-year, 10-year, and 100-year twenty-four (24)-hour duration storm events.
Stormwater quantity control will be provided by the use of a new wet pond and two grass channels
as part of the development.
Water Quality and Water Quantity
Since the project site is located in the Cape Fear River Basin, the following criteria below was
considered for the design of SCMs in regard to water quality and quantity:
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1. 100% of all impervious and built-upon-area (BUA) will be treated by a stormwater control
measure.
2. High density developments must manage and attenuate the first inch of runoff for water
quality in an approved Stormwater Control Measure(s) (SCM). The peak flow rate of the
first inch water quality volume from the SCM must also be shown to be less than the
predeveloped peak rate for the 1 year-24-hour storm event.
3. The increase in the 1-inch design volume shall be released over a 2-to-5-day period.
METHODOLOGY
Hydrology and storm water modeling calculations were performed using the latest version of
Hydraflow modeling software. Simulations were set up based on information provided within the
North Carolina Department of Environmental Quality Stormwater Design Manual.
The Soil Conservation Service (NRCS TR-55) hydrologic method was utilized for the estimation of
stormwater runoff peak rates and the generation of hydrographs for the routing of stormwater
flows. Input and results can be found summarized in tables throughout this report and in the
appendices.
SYSTEM SUMMARY
The post developed design of the site has been laid out in such a way to provide a drainage area
that will require stormwater management.The stormwater system is comprised of a singular SCM.
The primary SCM is a stormwater wet pond that is fully sized for the design storm that utilizes a
storm drain pipe network to collect runoff from impervious surfaces on the site. The SCM will also
comprise of two grass channels that will collect any runoff from the green areas of the proposed
site.
CONCLUSION
Stormwater design was based on the standards presented in the North Carolina Department of
Environmental Quality (NCDEQ) Stormwater Design Manual.
Post-development discharge rates for the site were designed to not exceed pre-development
discharge rates for the 1-year, 2-year, 10-year.and 100-year,twenty-four(24)-hour duration storm
events. Stormwater quantity control will be provided by the implementation of a new wet pond
and two grass channels as part of the development.
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Peak Runoff Analysis
• Pre-Development Conditions
The existing site is currently undeveloped wooded and open space area. There is one drainage
area analyzed in this report with its own study point, composite runoff curve number and single
point of analysis.
SCM Pre-Developed Area covers a portion of the parcel at 8.74 acres (±380,520 SF) including the
20' easement for the existing sanitary sewer pipe. This area slopes generally from Southeast to
Northwest, with average slopes in the range of 2-10% and consists of pervious area.
The characteristics for the pre-development basin are shown below and the drainage maps can
be found in Appendix A. Additional calculations for the basin can also be found in Appendix B.
Table 5:Pre-Development Summaries
Area
Composite Time of
Basin ID [acres] Curve Concentration
Number (CN) (Tc) [min.]
Pre-Developed Area 8.74 53.3 14.85
• Post-Development Conditions
The post-development condition contains a single drainage area directed to the stormwater wet
pond and one bypass drainage area from the pre-development condition.
SCM Post-Developed Area consists of 5.05 acres (+220,108 SF) of the proposed residential houses,
road, and other infrastructure required. The wet pond collects runoff with catch basins and
drainage pipes that connect to the stormwater wet pond.
The characteristics for the post-development drainage areas are shown below and calculations
can be found in Appendix B. A drainage map identifying the basin can be found in Appendix A.
Table 6:Post Development Area Summaries
Area Composite Time of
Basin ID Curve Concentration
[acres] Number (CN) (Tc) [min.]
SCM Post-Developed Area 5.05 73.8 5
Table 7:Post Development By-Pass Area Summaries
Area Composite Time of
Basin ID [acres] Curve Concentration
Number (CN) (Tc) [min.]
SCM Post-Developed Bypass Area 3.68 54.8 10
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• Comparison of Peak Discharges
The pre- and post- development peak discharges are shown below. Full calculations and
hydrographs can be found on Appendix B.
Table 8: Total Site Downstream Impact
Wet Pond SCM
Pre-Dev. Total Site Peak Flow Post-Dev. Total Site Peak Flow
Storm Event (cfs) (cfs)
1-yr 24-hr 0.396 0.381
2-yr 24-hr 1.968 1.534
10-yr 24-hr 11.08 9.777
1 00- r 24-hr 1 33.28 1 33.04
Site Stabilization
During construction phase, the permanent stormwater wetlands will be utilized as temporary
sediment basins. Skimmers will be used in the temporary sediment basins to dewater the basin
from the surface. After final grading is completed, permanent vegetation shall be applied in
accordance with the seeding requirements from the NCDEQ and the landscape plan for this site.
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APPENDIX A
Figures
Hydrological Soil Report
Topography Map
FEMA Flood Map No. 3720150600J
Surface Water Classification Maps
Hydrologic Unit Code (HUC)
Wetlands Inventory Map
NOAA Point Precipitation Depth Estimates
NOAA Point Precipitation Intensity Estimates
Pre-Development Drainage Basin Map
Post-Development Drainage Basin Map
Erwin Road Residential—Dunn, NC 8 P a g e

3 Hydrologic Soil Group—Harnett County,North Carolina 3
m
mN mm
M M
714420 714470 714520 714570 714620 714670 714720
35°19 2"N 35°19'2"N
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35°18'48"N 35°18'48"N
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3 3
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m Map Scale:1:2,150 W printed on A portrait(8.5"x 11")sheet
" Meters
N 0 30 60 120 180
Fe
0 100 200 400 600et
Map projection:Web Mercabor Comer coordinates:WGS84 Edge tics:UTM Zone 17N WGS84
U}DA Natural Resources Web Soil Survey 5/15/2023
Conservation Service National Cooperative Soil Survey Page 1 of 4

Hydrologic Soil Group—Harnett County,North Carolina
MAP LEGEND MAP INFORMATION
Area of Interest(AOI) p C The soil surveys that comprise your AOI were mapped at
Area of Interest(A01) 0 C/D 1:24,000.
Soils D Warning:Soil Map may not be valid at this scale.
Soil Rating Polygons �
A p Not rated or not available Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
0 A/D Water Features line placement.The maps do not show the small areas of
Streams and Canals contrasting soils that could have been shown at a more detailed
0 B scale.
Transportation
0 B/D
Rails Please rely on the bar scale on each map sheet for map
0 C measurements.
'.,,r Interstate Highways
0 C/D US Routes Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
0 D Major Roads Coordinate System: Web Mercator(EPSG:3857)
Not rated or not available Local Roads
Maps from the Web Soil Survey are based on the Web Mercator
Soil Rating Lines Background projection,which preserves direction and shape but distorts
q distance and area.A projection that preserves area,such as the
® Aerial Photography Albers equal-area conic projection,should be used if more
• A/D accurate calculations of distance or area are required.
+'* B This product is generated from the USDA-NRCS certified data as
B/D of the version date(s)listed below.
x C Soil Survey Area: Harnett County, North Carolina
Survey Area Data: Version 20,Sep 8,2022
0 C/D
Soil map units are labeled(as space allows)for map scales
r D 1:50,000 or larger.
r Not rated or not available Date(s)aerial images were photographed: Apr 24,2022—May
Soil Rating Points 9,2022
p A The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
p A/D imagery displayed on these maps.As a result,some minor
B shifting of map unit boundaries may be evident.
B/D
UU� Natural Resources Web Soil Survey 5/15/2023
� Conservation Service National Cooperative Soil Survey Page 2 of 4

Hydrologic Soil Group—Harnett County, North Carolina
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
Bb Bibb soils,frequently A/D 3.7 21.2%
flooded
NoB Norfolk loamy sand,2 to A 9.1 52.6%
6 percent slopes
NoC Norfolk loamy sand,6 to A 4.6 26.2%
10 percent slopes
Totals for Area of Interest 17.4 100.0%
Description
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 C/D), 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 5/15/2023
Conservation Service National Cooperative Soil Survey Page 3 of 4

Hydrologic Soil Group—Harnett County, North Carolina
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff.-None Specified
Tie-break Rule: Higher
uSDA Natural Resources Web Soil Survey 5/15/2023
Conservation Service National Cooperative Soil Survey Page 4 of 4

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This map is not a legal document.Boundaries may be 9°13 1000 500 0 METERS 1000 2000 Ramp 4WD 00
164 MILS
generalized for this map scale.Private lands within government 1°20" �1 0.5 1 r`Y
reservations may not be shown.Obtain permission before 24 MILS MILES •Interstate Route US Route O State Route
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Roads......................................... U.S. Census Bureau, 2016 UTM GRID AND 2019 MAGNETIC NORTH o
Names............................................................................GNIS,1980-2019 1 L1llington
DECLINATION AT CENTER OF SHEET M(1)Hydrography...............................National Hydrography Dataset, 1899 - 2018 1 2 3 2 Coats �
Contours.................... CONTOUR INTERVAL 10 FEET
...... ........National Elevation Dataset, 20 U.S.National Grid NORTH 3 Benson
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National Flood Hazard Layer FIRMette FEMA Legend
78o38'40"W 35o19'9"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
[ - WiAVBA99 Flood Elevation(BFE)
Zone
SPECIAL FLOOD With BFE or Depth zone AE,AO,AH,vE,AR
HAZARD AREAS Regulatory Floodway
0.2%Annual Chance Flood Hazard,Areas
of 1%annual chance flood with average
depth less than one foot or with drainage
areas of less than one square mile zone x
5y _ Future Conditions 1%Annual
Chance Flood Hazard zonex
Area with Reduced Flood Risk due to
OTHER AREAS OF Levee.See Notes.zone x
FLOOD HAZARD ��� Area with Flood Risk due to Leveezone D
x. r Z
NO SCREEN Area of Minimal Flood Hazard zonex
Effective LOMRs
'! +•,44-.IT•, ;:;a OTHER AREAS Area of Undetermined Flood Hazard zone n
L i
LOBE E
4 �• GENERAL ---- Channel,Culvert,or Storm Sewer
STRUCTURES IIIIIII Levee,Dike,or Floodwall
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17•5 Water Surface Elevation
SIT+ F DUI
a- - - Coastal Transect
PA4] �?� *•^^-5f5— Base Flood Elevation Line(BFE)
'C _F Limit of Study
R F MINIM L L �� RD —--- Jurisdiction Boundary C Baseline
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FEATURES Hydrographic Feature
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y * 11 was exported on 6/15/2023 at 11:18 AM and does not
R 3� reflect changes or amendments subsequent to this date and
t time.The NFHL and effective information may change or
become superseded by new data over time.
This map image is void if the one or more of the following map
elements do not appear:basemap imagery,flood zone labels,
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78°38'3"W 35°SS'40"N FIRM panel number,and FIRM effective date.Map images for
Feet 1-6 000 unmapped and unmodernized areas cannot be used for
0 250 500 1,000 1,500 2,000 regulatory purposes.
Basemap Imagery Source:USGS National Map 2023

Surface Water Classifications: a X �
a�
Stroam Indcx. 18-68-12 1 +
k Stream Name: Black River(Little Black River)
(Popes Lake,Rhodes Fond)
Description- From source to South River
Classification- C;Sw
Date of Class_-. August 31, 1974
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5/25/23,7:56 AM Precipitation Frequency Data Server
NOAA Atlas 14,Volume 2,Version 3
' Location name: Dunn,North Carolina,USA*
Latitude:35.3165*,Longitude: -78.6409°
Elevation: 164 ft**
*source:ESRI Maps y�
source:USGS
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
Average recurrence interval(years)
Duration��� 10 25 50 100 200 500 1000
5-min 0.437 0.514 0.594 0.660 0.736 0.793 0.847 0.898 0.960 1.01
(0.399-0.480) (0.470-0.565) (0.543-0.653) (0.602-0.724) (0.668-0.806) (0.718-0.868) (0.763-0.926) (0.804-0.982) (0.851-1.05) (0.890-1.11)
10-min 0.698 0.822 0.951 1.06 1.17 1.26 1.35 1.42 1.52 1.59
(0.637-0.767) (0.752-0.903) (0.870-1.04) (0.963-1.16) 1 (1.06-1.28) 1 (1.14-1.38) 1 (1.21-1.47) 1 (1.27-1.56) (1.35-1.66) (1.40-1.74)
15-min 0.872 1.03 1.20 1.34 1.49 1.60 1.70 1.80 1.91 2.00
(0.797-0.959) (0.945-1.14) 1 (1.10-1.32) 1 (1.22-1.46) 1 (1.35-1.63) 11 (1.45-1.75) 1 (1.53-1.86) 1 (1.61-1.96) (1.69-2.09) (1.76-2.19)
30-min 1.20 1.43 1.71 1.94 2.20 2.41 2.61 2.80 3.04 3.24
(1.09-1.31) (1.30-1.57) (1.56-1.88) (1.77-2.12) (2.00-2.41) (2.18-2.64) (2.35-2.85) (2.50-3.06) (2.70-3.32) (2.85-3.55)
60-min 1.49 1.79 2.19 2.52 2.93 F 3.26 3.59 3.92 4.36 IF 4.73
(1.36-1.64) (1.64-1.97) (2.00-2.41) (2.30-2.76) (2.66-3.21) (2.96-3.57) (3.23-3.92) (3.51-4.29) (3.87-4.77) (4.16-5.18)
2-hr 1.75 2.12 2.63 3.07 3.64 4.11F 4.59 5.09 F 5.78 6.36
(1.58-1.95) 11 (1.92-2.36) (2.38-2.93) (2.76-3.41) (3.25-4.04) 1 (4.06-5.10) (4.48-5.65) 1(5.03-6.40) (5.49-7.06)
3-hr 1.86 2.24 2.81 3.30 F 3. 55 4.51 5.09 5.72 6.59 7.35
(1.68-2.08) 1 (2.04-2.51) (2.54-3.14) (2.97-3.68) (3.54-4.40) (4.01-5.03) (4.50-5.67) (5.01-6.36) (5.71-7.33) (6.30-8.19)
6-hr 2.22 2.68 3.35 3.94 4.75 5.44 6.16 6.94 8.04 9.00
(2.02-2.47) (2.44-2.98) (3.04-3.72) (3.56-4.37) (4.26-5.25) (4.85-6.01) (5.44-6.80) (6.07-7.65) (6.94-8.87) (7.68-9.94)
12-hr 2.61 3.15 3.96 4.68 F 5.68 6.54 7.46 8.46 9.90 11.2
(2.36-2.91) 11 (2.85-3.51) (3.58-4.42) 1 (4.21-5.22) 1 (5.06-6.30) 1 (5.79-7.25) 1 (6.54-8.25) 1 (7.33-9.35) (8.44-10.9) (9.38-12.3)
24-hr 3.05 3.71 4.75 5.59 F 6. 77 7.74 8.76 9.85 11.4 12.7
(2.78-3.36) (3.38-4.08) (4.31-5.22) 1 (5.07-6.14) 1 (6.11-7.44) (6.96-8.52) (7.86-9.64) 11 (8.79-10.8) (10.1-12.6) (11.2-14.0)
2-day 3.57 4.32 5.49 6.43 7.75 8.83 9.97 11.2 12.9 14.3
(3.27-3.90) (3.96-4.72) (5.01-5.99) (5.86-7.02) (7.03-8.46) (7.97-9.65) (8.95-10.9) (9.98-12.2) (11.4-14.2) (12.6-15.8)
3-day 3.80 4.59 5.80 6.76 F 8.12 9.22 10.4 11.6 13.3 14.7
(3.50-4.14) 11 (4.22-5.00) 1 (5.32-6.30) 1 (6.19-7.34) 1 (7.39-8.82) 1 (8.36-10.0) 1 (9.36-11.3) 1 (10.4-12.6) (11.9-14.6) (13.0-16.1)
4-day 4.04 4.87 6.11 7.10 F 8.48 9.60 10.8 IF 12.0 13.8 15.2
(3.73-4.37) 11 (4.49-5.27) (5.62-6.61) (6.52-7.67) (7.75-9.17) 1 (8.74-10.4) 1 (9.76-11.7) 1 (10.8-13.0) (12.3-15.0) (13.5-16.5)
1E77-day 4.67 5.61 6.96 8.03 9.52 10.7
.7day1.9 13.2 15.0 16.5
(4.31-5.08) (5.17-6.10) (6.40-7.57) (7.36-8.72) (8.69-10.3) (9.75-11.6) (10.8-13.0) (11.9-14.4) (13.4-16.4) (14.7-18.0)
10-day 5.34 6.38 7.79 8.89 F 10.4 11.6 12.8 14.0 iF 15.7 1 F-17.1
(4.98-5.73) 11 (5.95-6.86) 1 (7.24-8.37) (8.24-9.54) 1 (9.59-11.1) 1 (10.6-12.4) 1 (11.7-13.7 1 (12.8-15.1) (14.3-17.0) (15.5-18.5)
20-day 7.19 8.54 10.3 F 11.6 F 13.4 14.9 16.3 17.8 19.8 21.4 )
(6.69-7.73) (7.95-9.19) (9.53-11.0) (10.8-12.5) (12.4-14.4) (13.7-16.0) (15.0-17.5) (16.3-19.2) (18.1-21.4) (19.4-23.1
30-day 8.96 10.6 12.5 14.0 15.9 17.4 18.9 20.4 22.4 24.0
(8.35-9.64) 11 (9.88-11.4) 1 (13.0-15.0) 1 (14.7-17.1) (16.1-18.7) (17.4-20.3) 1 (18.8-22.0) (20.5-24.2) (21.9-25.9)
45-day 11.4 13.4 15.6 17.2 19.4 21.0 22.6 24.2 26.4 28.0
(10.7-12.2) 11 (12.6-14.3) 1 (14.6-16.6) 1 (18.1-20.7) 1 (19.6-22.5) 1 (21.0-24.2) 1 (22.5-26.0) (24.3-28.3) (25.8-30.1)
60-day 13.6 16.0 18.4 20.2 22.6 24.4 26.1 27.8 30.1 31.8
(12.8-14.5) (15.0-17.0) (17.3-19.6) (19.0-21.6) (21.2-24.1) (22.8-26.0) (24.4-27.9) (25.9-29.7) (27.9-32.2) (29.4-34.0)
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 NOAAAtlas 14 document for more information.
Back to Top
PF graphical
https:Hhdsc.nws.noaa.gov/pfds/pfds_printpage.html?lat=35.3165&Ion=-78.6409&data=depth&units=english&series=pds 114

5/25/23,7:56 AM Precipitation Frequency Data Server
PDS-based depth-duration-frequency (DDF) curves
Latitude: 35.31651, Longitude: -73-64091
Average recurrence
30 inlenral
{yeara�
25 — 1
2
a 20 — 5
15 — 25
9 — 50
� 10
— 100
E — 200
IL
— soo
5
1000
0
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30
€ 25
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15 15-min — 4-day
— 30-min — 7-day
10 — 60-min — 10-eay
a — 2-nr — 20-day
5 — 3-hr — 30-day
6-hr — 4-day
0 — 12-hr — 6o-eay
— 24-hr
1 2 5 10 25 50 100 20D 500 1000
Average recurrence interval (years)
NOAA Atlas 14,volume 2,Version 3 Created(GMT):Thu May 25 11:56:22 2023
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5/25/23,7:56 AM Precipitation Frequency Data Server
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https://hdsc.nws.noaa.gov/pfds/pfds_printpage.html?lat=35.3165&Ion=-78.6409&data=depth&units=english&series=pds 3/4

5/25/23,7:56 AM Precipitation Frequency Data Server
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Greenville
NOFth
Fayettevffle
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National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring,MD 20910
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5/25/23,7:57 AM Precipitation Frequency Data Server
NOAA Atlas 14,Volume 2,Version 3
' Location name: Dunn,North Carolina,USA*
Latitude:35.3165*,Longitude: -78.6409°
Elevation: 164 ft**
*source:ESRI Maps y�
source:USGS
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/hour)1
Average recurrence interval(years)
Duration� 2 10 25 F 500 1000
5-min 5.24 6.17 7.13 7.92 8.83 9.52 10.2 10.8 11.5 12.1
(4.79-5.76) 1 (5.64-6.78) (6.52-7.84) (7.22-8.69) (8.02-9.67) (8.62-10.4) 1 (9.16-11.1) 1 (9.65-11.8) 1 (10.2-12.6) (10.7-13.3)
10-min 4.19 4.93 5.71 6.34 7.04 7.58 8.08 8.54 9.11 9.56
(3.82-4.60) 1 (4.51-5.42) (5.22-6.27) (5.78-6.95) (6.39-7.70) (6.86-8.29) (7.27-8.83) (7.64-9.34) (8.08-9.96) (8.41-10.5)
15-min 3.49 4.13 4.81 5.34 5.95 6.40 6.81 7.18 7.64 8.00
(3.19-3.84) (3.78-4.54) (4.40-5.29) (4.87-5.86) (5.40-6.51) (5.79-7.00) (6.12-7.44) (6.43-7.85) (6.78-8.36) (7.04-8.76)
30-min 2.39 2.85 3.42 3.87 4.40 4.82 5.21 F 5.59 6.08 6.48
(2.18-2.63) (2.61-3.14) (3.13-3.76) (3.53-4.25) (4.00-4.82) (4.36-5.27) (4.69-5.70) (5.00-6.11) (5.39-6.65) (5.70-7.09)
60-min 1.49 1.79 2.19 2.52 2.93 3.26 3.59 3.92 4.36 4.73
(1.36-1.64) (1.64-1.97) (2.00-2.41) (2.30-2.76) (2.66-3.21) (2.96-3.57) (3.23-3.92) (3.51-4.29) (3.87-4.77) (4.16-5.18)
2-hr 0.875 1.06 1.32 1.53 1.82 2.06 2.29 2.54 2.89 3.18
(0.791-0.977) (0.957-1.18) 1 (1.19-1.47) 1 (1.63-2.02) (1.83-2.28) 1 (2.03-2.55) (2.24-2.82) (2.52-3.20) (2.74-3.53)
3-hr 0.618 0.747 0.934 1.10 1.32 1.50 1.70 1.90 2.20 2.45
(0.560-0.692) (0.677-0.835) (0.845-1.04) (0.989-1.22) (1.18-1.46) 1 (1.34-1.67) 1 (1.50-1.89) 1 (1.67-2.12) 1 (1.90-2.44) (2.10-2.73)
6-hr 0.370 0.447 0.559 0.658 0.792 0.907 1.03 1.16 1.34 1.50
(0.336-0.411) (0.406-0.496) (0.507-0.621) (0.595-0.730) (0.711-0.876) (0.809-1.00) (0.908-1.14) 1 (1.01-1.28) 1 (1.16-1.48) (1.28-1.66)
12-hr 0.216 0.261 0.328 0.388 0.471 0.543 0.618 0.701 0.821 0.926
(0.195-0.241) (0.236-0.291) (0.297-0.366) (0.349-0.433) (0.420-0.523) (0.480-0.601) (0.542-0.684) (0.608-0.776) (0.700-0.908) (0.778-1.02)
24-hr 0.127 0.154 0.197 0.232 0.282 0.322 0.365 0.410 0.475 0.527
(0.115-0.139) (0.140-0.169) (0.179-0.217) (0.211-0.255) (0.254-0.310) (0.290-0.354) (0.327-0.401) (0.366-0.452) (0.420-0.524) (0.464-0.583)
2-day 0.074 0.090 0.114 0.133 0.161 0.183 0.207 o.232 0.268 0.297
(0.068-0.081) (0.082-0.098) (0.104-0.124) (0.122-0.146) (0.146-0.176) (0.166-0.200) (0.186-0.227) (0.207-0.255) (0.238-0.294) (0.262-0.328)
3-day 0.052 0.063 0.080 0.093 0.112 0.128 0.144 0.161 0.185 0.204
(0.048-0.057) (0.058-0.069) (0.073-0.087) (0.085-0.101) (0.102-0.122) (0.116-0.139) (0.129-0.156) (0.144-0.175) (0.164-0.202) (0.181-0.224)
4-day 0.042 0.050 0.063 0.073 0.088 0.100 0.112 0.125 0.143 0.158
(0.038-0.045) (0.046-0.054) (0.058-0.068) (0.067-0.079) (0.080-0.095) (0.091-0.108) (0.101-0.121) (0.112-0.135) (0.128-0.155) (0.140-0.172)
7-day 0.027 0.033 0.041 0.047 ) 0.056 0.063 0.071 0.078 0.089 0.098
(0.025-0.030) (0.030-0.036) (0.038-0.045) (0.043-0.051 (0.051-0.061) (0.058-0.069) (0.064-0.077) (0.071-0.085) (0.080-0.097) (0.087-0.107)
10-day 0.022 0.026 0.032 0.037 0.043 0.048 0.053 0.058 0.065 0.071
(0.020-0.023) (0.024-0.028) (0.030-0.034) (0.034-0.039) (0.039-0.046) (0.044-0.051) (0.048-0.057) (0.053-0.062) (0.059-0.070) (0.064-0.077)
20-day 0.014 0.017 0.021 0.024 0.027 0.030 0.033 0.037 0.041 0.044
(0.013-0.016) (0.016-0.019) (0.019-0.022) (0.022-0.025) (0.025-0.030) (0.028-0.033) (0.031-0.036) (0.033-0.039) (0.037-0.044) (0.040-0.048)
30-day 0.012 0.014 0.017 0.019 0.022 0.024 0.026 0.028 0.031 0.033
(0.011-0.013) (0.013-0.015) (0.016-0.018) (0.018-0.020) (0.020-0.023) (0.022-0.025) (0.024-0.028) (0.026-0.030) (0.028-0.033) (0.030-0.035)
45-day 0.010 0.012 0.014 0.015 0.017 0.019 0.020 0.022 0.024 0.025
(0.009-0.011) (0.011-0.013) (0.013-0.015) (0.014-0.017) (0.016-0.019) (0.018-0.020) (0.019-0.022) (0.020-0.024) (0.022-0.026) (0.023-0.027)
60-day 0.009 0.011 0.012 0.014 0.015 0.016 0.018 0.019 0.020 0.022
(0.008-0.010) (0.010-0.011) (0.012-0.013) (0.013-0.o14) (0.014-0.016) (0.015-0.018) (0.016-0.019) (0.017-0.020) (0.019-0.022)I(0.020-0.023)
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
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5/25/23,7:57 AM Precipitation Frequency Data Server
PDS-based intensity-duration-frequency (IDF) curves
Latitude: 35.31651, Longitude: -73-64091
Average recurrence
10 L inlenral
{yeara�
r
c — 1
ILO — 6
c
— 25
e
O — 50
_ 10-1
— 200
— 1000
10-�
c_ c_ c_ c_ c_
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101
r
c
Duration
100
Lh c — "in — 2-clay
n
� — 70-min — 3-day
15-min — 4-day
— 30-min — 7-day
10-1 — 6 D-min — 1 d-day
a
L — 2-nr — 20-day
— 3-hr — 3OL--day
6-hr — 4-day
10-2 — 12-hr — 60-day
— 24-hr
1 2 5 10 25 50 100 20D 500 1000
Average recurrence interval (years)
NOAAAtIas 14,volume 2,Version 3 Created(GMT):Thu May 25 11:57:01 2023
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5/25/23,7:57 AM Precipitation Frequency Data Server
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https://hdsc.nws.noaa.gov/pfds/pfds_printpage.html?lat=35.3165&Ion=-78.6409&data=intensity&units=engiish&series=pds 3/4

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Greenville
NOFth
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700km
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National Water Center
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Silver Spring,MD 20910
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SCALE H: 1" = 50'
V:
( IN FEET )
OB No. 220124-01-004
1 inch = 50 ft.
DATE 2023
FILE No.
SHEET
Cad file name: V:\220124 - Ben Stout Construction\220124-01-004 (ENG) - Erwin Road, Dunn, NC\Engineering\Engineering Plans\Construction Documents\220124-01-004-DDX.dwg

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SCALE H: 1" = 50'
V:
( IN FEET )
OB No. 220124-01-004
1 inch = 50 ft.
DATE 2023
FILE No.
SHEET
Cad file name: V:\220124 - Ben Stout Construction\220124-01-004 (ENG) - Erwin Road, Dunn, NC\Engineering\Engineering Plans\Construction Documents\220124-01-004-DDP.dwg

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1 DESIGN DRAWN CHKD
SCALE H: 1" = 50'
V:
( IN FEET )
OB No. 220124-01-004
0
In
1 inch = 50 ft.
DATE 2023
FILE No.
SHEET
Cad file name: V:\220124 - Ben Stout Construction\220124-01-004 (ENG) - Erwin Road, Dunn, NC\Engineering\Engineering Plans\Construction Documents\220124-01-004-DDP.dwg

U.S. Fish and Wildlife Service
National Wetlands Inventory Wetlands Inventory Map
N
• I' 4 � .41 1 � - -
f n- r ` k.- 1
t
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1:3,670
0 0.03 0.06 0.12 mi
r
i U.S.Fish and Wildlif2Service,National Standards and Support Team,
0 0.05 0.1 0.2 km wetlands [e-mail] ,.in/t`-
July 1 0, 2023 This map is for general reference only.The US Fish and Wildlife
y Service is not responsible for the accuracy or currentness of the
Wetlands base data shown on this map.All wetlands related data should
Freshwater Emergent Wetland Lake be used in accordance with the layer metadata found on the
Wetlands Mapper web site.
Estuarine and Marine Deepwater ❑ Freshwater Forested/Shrub Wetland ❑ Other
Estuarine and Marine Wetland ❑ Freshwater Pond ❑ Riverine
National Wetlands Inventory(NWI)
This page was produced by the NWI mapper

Bowman
NORTH CAROLINA
APPENDIX B
Stormwater Wetlands Calculations
CN Values
Time of Concentration Calculations
Wet Pond Design, Hydrographs, and Details
Grass Channels
Spread Calculations
Erwin Road Residential—Dunn, NC 9 1 P a g e

Bowman North Carolina, Ltd.
Curve Number Calculation (CN)
Pre-Developed Conditions(Overall Site)
Drainage Area(acresZ 8.74
Existing Soil Groups:
Soil Group Map Symbol Soil Description Acres Percent of DA
A/D Bb Bibb soils 1.18 14%
A NoB Norfolk loamy sand 5.16 59%
A NoC Norfolk loamy sand 2.40 27%
Existing Land Uses:
Land Use Description Existing Soil Group Acres Curve# Weighted CN
Open Space- Fair A 1.00 57 6.5
Open Space-Good A 0.35 59 2.4
Wooded -Good A 7.32 53 44.4
Impervious A 0.07 98 0.8
Cumulative Curve#= 53.3

Bowman North Carolina, Ltd.
Curve Number Calculation (CN)
Post-Developed Conditions(Wet Pond)
Drainage Area(acres) 5.05
Existing Soil Groups:
Soil Group Map Symbol Soil Description Acres Percent of DA
A/D Bb Bibb soils 0.68 13%
A NoB Norfolk loamy sand 3.48 69%
A NoC Norfolk loamy sand 0.89 18%
Proposed Land Uses:
Land Use Description Existing Soil Group Acres Curve# Weighted CN
Impervious A 1.95 98 37.8
Open Space- Good A 2.92 59 34.1
Wooded -Good A 0.18 53 1.9
Cumulative Curve#= 73.8

Bowman North Carolina, Ltd.
Curve Number Calculation (CN)
Post-Developed Bypass Conditions(Wet Pond)
Drainage Area(acresZ 3.68
Existing Soil Groups:
Soil Group Map Symbol Soil Description Acres Percent of DA
A/D Bb Bibb soils 0.39 11%
A NoB Norfolk loamy sand 1.17 32%
A NoC Norfolk loamy sand 1.21 33%
Proposed Land Uses:
Land Use Description Existing Soil Group Acres Curve# Weighted CN
Open Space-Good A 1.10 59 17.6
Wooded -Good A 2.59 53 37.3
Cumulative Curve#= 54.8

IMPERVIOUS SUMMARY TABLE
ON - SiTE AREA _ 393 ) 826 SF ( 9 . 04 ACRES )
BULDNGS 33 , 21 0 SF 0 . 76 ACRE ( S ) 8 , 41 % OF ;-`, RED.
PAVEMENT 41 ) 092 SF 0 . 94 ACRE ( S ) 10 . 40 % OF ARE ;
SUEWALK 48 SF 0 . 18 ACRE ( S ) 1 . 99 % OF AREA
EkSThG WPERVIOUS AREA 0 SF 0 ACRE ( S ) 0 % OF AREA
TOTAL WPERVIOUS AREA 82 ) 050 SF 1 . 88 ACRE ( S ) 20 . 80 % OF AREA,
GREEN /OPEN SPACE 311 ) 776 SF 7 . 16 ACRE ( S ) 79 , 20 % OF AREA.
INCREASE IN WPERVhOUS AREA 82 ) 050 SF 1 . 88 ACRE ( S ) 20 . 80 % OF AREA

TIME OF CONCENTRATION
Existinq Conditions
SCS Methodology
OPEN CHANNEL
SHALLOW CONC FLOW: FLOW: TOTAL
SHEET FLOW: SEGMENTI SEGMENT1
Manninq's Equation:
Tc=(0.007(nL)^0.8)/(P2^0.5)(s"0.4) 2-year/24-hr To=L/60'V V=1.49Rv3S"/n
Basin Comments Length Elevt Elev2 Slope Rainfall Depth Manning's Tyr Length Elev2 Elev3 Slope Condition Vavg T�2 Cross Sectional Wetted Perimeter Hydraulic Radius Length Elev3 Elev4 Slope Manning's V T. T­ Tc(minimum) Tlag Basin
(ft) (ft/ft) TP-40(in) "n" (min) (ft) (ft/ft) TR-55 Fig.3-1 Wesel (min) Flow Area(tt^2) (ft) (tt) (tt) (ft/ft) "n" (fps) (min) (min) (10 min) 0.6'Tc(hrs)
1 Stream 100 189.19 186.18 0.030 3.71 0.24 11.25 637 186.2 164.95 0.03333 Unpaved 2.95 3.60 14.85 14.85 0.15 1
1IW=234:06 PM G:WYDR01p.jecls\Tl..0—Dunn Erwin Rd.ds

Proposed Wet Pond
Project Information
Project Name: Erwin Road Residential
Project#:
Designed by: RG Date: 8/18/2023
Revised by: Date:
Checked by: Date:
Site Information
Sub Area Location: Drainage To Proposed Wet Pond
Drainage Area (DA) = 5.05 Acres 220,108 sf
Impervious Area (IA) = 1.95 Acres 85,120 sf
Percent Impervious (1) = % 38.67 %
Required Surface Area
Permament Pool Depth: 3.92 ft Non-Coastal County
SA/DA= 1.22
Min Req'd Surface Area = 2,684 sf(at Permanent Pool)
Required WQv Storage Volume
Design Storm = 1 inch Non-Coastal County
Determine Rv Value = 0.05 + .009 (1) = 0.398 in/in
Storage Volume Required = 7,297 cf(above Permanent Pool)
Elevations
Top of Pond Elevation = 174.60 ft
Temporary Pool Elevation = 172.10 ft
Permanent Pool Elevation = 170.10 ft
Shelf Begining Elevation = 169.60 ft
Forebay Weir= 169.00 ft
Shelf Ending Elevation = 170.60 ft
Bottom Elevation = 164.60 ft
Permanent Pool Area
Area @ Top of Permanent Pool = 4,375 sf
Volume of Temporary Storage = 16,105 cf
Is Permenant Pool Surface Area Sufficient (yes/no)? Yes ( 4375 > 2684 ) sf
Volume of Storage for Design Storm = 16,105 Yes ( 16105 > 7297 ) cf

Incremental Drawdown Time
STORMWATER POND
INCREMENTAL DRAWDOWN METHOD-Water Quality Volume
Project Information
Project Name: Erwin Road Residential
Project#:
Designed by: RG Date: 8/18/2023
Checked by: Date:
Water Quality Orifice
Incremental Determination of Water Quality Volume Drawdown Time
Zone 3 Q3=0.0437 Cp`D2(Z-D/24-Ei)A(112)
1
Zone 2 O Q2=0.372 CD'D'(Z-Ei)A)3i2)
Zone 1 Q,=0
1
Orifice Diameter(D)= 1.3 in
Cd= 0.6
Ei= 170.1 Orifice Inv.
Zone 1 Range= 0.00 to 170.1
Zone 2 Range= 170.1 to 170.2
Zone 3 Range= 170.2 to 172.1
Incremental Drawdown Method
Contour Incremental Drawdown
Countour Area Volume Stage,Z Zone Q Time
sq ft cu ft ft cfs min
170.10 6,140 0 0.00 2.00 0.000
170.60 7425 3,391 0.50 3.00 0.030 1,910
171.60 8770 8,098 1.00 3.00 0.053 2,533
172.00 9520 3,658 0.40 3.00 0.060 1,013
172.10 9645 958 0.10 3.00 0.062 258
Total 16,105 5,714
Drawdown Time=Incremental Volume/Q/60sec/min
Summary
Total Volume= 16,105 cf
Total Time= 5,714 min
Total Time= 3.97 days Between 2&5
8/18/2023 Wet Pond-new design-Dunn Erwin.xls 1 of 1

Project: Pond #1 Date: 8/18/2023
Main-Pond Contours-Volumes
Elevation Main-Pond Incremental Vol. Accumulated Vol. Description
170.1 4,370 1,995 14,336 A2 (Perm—Pool)
169.6 3,610 2,079 12,341 Al (Bottom_Shelf)
169 3,320 3,078 10,262
168 2,835 2,615 7,184
167 2,395 2,185 4,569
166 1,975 1,780 2,384
165 1,585 604 604
164.6 1,435 0 0 A3 (Bottom_Pond)
Forebay Contours-Volumes
Elevation FB1 FB2 FB3 Total-Areas Incremental Vol. Accumulated Vol.
170.1 1,620 1,620 724 2,411
169.6 1,275 1,275 718 1,687
169 1,120 1,120 401 969
168.6 885 885 568 568
167.6 250 250 0 0
Forebay Volume 16.8% *Between 15% &20%
Average Depth (Option 1) 3.42 *At least 3' average depth
Average Depth Calculation (Option 2)
Vpp 14,336
permeter of shelf 267 Length of PPE at main pond only
width of shelf 3
Al (Bottom—Shelf): 3,610
Average Depth = 3.92

Proposed Wet Pond #1
Project Information
Project Name: Erwin Road Residential
Project#:
Designed by: RG Date: 8/8/2023
Revised by: Date:
Checked by: Date:
Site Information
Sub Area Location: Drainage to Proposed Pond
Drainage Area (DA) = 5.05 Acres
Impervious Area (IA) = 1.95 Acres
Percent Impervious (1) = 38.67 % (Drainage Area)
Orifice Sizing
Orifice Size = 1.30 in (Diameter)
Drawdown Time = 3.97 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: 160.0 cf (Water Displaced -Top of Pond to Bottom of Pond)
Weight: 9984 Ibs
Factor of Safety 1.20
WT Req'd of Anti-Flotation Device: 11,981 Ibs
Volume of Concrete Req'd: 79.9 cf (Unit WT of Concrete = 150 pcf)
Volume Provided: 86.0 cf (4'x4' riser x 2' =32cf, 6'x6'footing x 1.5' =54cf)

STAGE/STORAGE TABLE
STAGE (FT) ELEVATION (FT) CONTOUR AREA INCREMENTAL TOTAL STORAGE
(SF) STORAGE (CF) (CF)
0.0 170.1 6140 0 0
0.5 170.6 7425 3391 3391
1.5 171.6 8770 8098 11489
1.9 172.0 9520 3658 15147
2.0 172.1 9645 958 16105 (WQV)
2.9 173.0 10835 9216 25321
3.9 174.0 12210 11523 36844
4.5 174.6 13060 7581 44425
(STORMWATER MANAGEMENT DESIGN WET DETENTION POND;
RIVER BASIN: CAPE FEAR
RECEIVING STREAM: BLACK RIVER
STREAM INDEX: 18-68-12-1
STREAM CLASS: C;Sw
HUC: 0303000601
PROJECT COORDINATES: 35.314454'N, -78.639890V
POND DESIGN SUMMARY
DRAINAGE AREA TO POND: 5.05 ACRES
SITE IMPERVIOUS AREA TO POND: 1.88 ACRES
OFF-SITE DESIGN IMPERVIOUS AREA TO POND: 0.07 ACRES
TOTAL DESIGN IMPERVIOUS AREA TO POND: 1.95 ACRES
PRE-DEVELOPED POST-DEVELOPED POST DEVELOPED POST DEVELOPED POST DEVELOPED
TO POND TO POND THROUGH POND BYPASS COMBINED
DRAINAGE AREA: 8.74 AC 5.05 AC 3.68 AC
CURVE NUMBER: 53.3 73.8 54.8
TIME OF CONCENTRATION: 14.9 MIN 5 MIN 10 MIN
1.0" STORM EVENT: 0.048 CFS 0.004 CFS
1-YEAR STORM EVENT: 0.396 CFS 7.947 CFS 0.058 CFS 0.323 CFS 0.381 CFS
2-YEAR STORM EVENT: 1.968 CFS 11.81 CFS 0.242 CFS 1.292 CFS 1.534 CFS
10-YEAR STORM EVENT: 11.08 CFS 24.03 CFS 3.668 CFS 6.109 CFS 9.777 CFS
100-YEAR STORM EVENT: 33.28 CFS 46.70 CFS 15.82 CFS 17.22 CFS 33.04 CFS

\ � 1
\ 1
1 1
1 I \ 1 IN
1
It \
It 1
PLAN VIEW
GRAPHIC SCALE
50 0 25 50 100 200
( IN FEET )
1 inch = 50 ft.

5'
EMBANKMENT WIDTH
6'TOPSOIL FOR ALL
AREAS ABOVE THE TRASH RACK
NORMAL POND ELEVATION REFER TO DETAIL
THIS SHEET
18'HOPE WITH WATER TIGHT SEAL
PIPE TO BE BEDDED TOP OF EMBANKMENT ELEVATION=174.6
PER DIRECTION OF GEOTECHNICAL 6'TOPSOIL ABOVE
ENGINEER 2 6'CLAY LINER REFER TO DETAIL 100 YEAR STORM ELEVATION=174.28
ON LITTORAL SHELF FOR INCREMENTAL
I 6'CLAY SOIL 3 WEIR
LINER ON INSIDE
FACE OF = 1 10 YEAR STORM ELEVATION=172.74
EMBANKMENT
—I 6 �
4'x4'PRECAST <
6FT LITTORAL 1 CONCRETE RISER
SHELF _ (INSTALL STEPS 2 YEAR STORM ELEVATION=172.19
- AS NECESSARY) 1 YEAR STORM ELEVATI0N=171.83
INV-169.9 1.0-INCH STORM ELEVATION=170.15
NORMAL POND ELEVATION=170.1
PYC E1J10N
3'MIN SEE DETAIL
`• I `
1 ELEV=167.9 2 NOTE: PUMPS SHALL USED TO DRAIN
1 I THE POND VA NECESSARY. REFER TO DETAIL
_ THIS SHEET FOR
DEWATERING REQUIREMENTS.
4 IN. ASTM C-923 SEAL
BETWEEN BARREL&RISER.KEY
CUTOFF TRENCH WITH CONC.TOO INVERT OF RISER BASE NV FILLED I I_ BOTTOM OF POND(TOP OF SEDIMENT STORAGE)=164.6
APPROXIMATE SIZE BARREL CONCRETE SHALL BE _
EXCAVATE AND BACKFILL 6'XB'X1'X1Y LONG ANGLE(6 TOT.REWIRED)TO ANCHOR RISER TO ANGLES IAREISEDURED = (BOTTOM OF SEDIMENT STORAGE)=163.6
WITH COMPACTED BASE PROVIDE 2-3/4'A307 BOLTS FROM ANGLE TO RISER AND TO BASE AND RISER. I -----------------ji
STRUCTURAL FILL AS 2-A307 'd'HOOKS 3/4'DIA.X 12'LONG FROM ANGLE TO BASE
ANGLE TO BE FIELD COATED WITH ZINC RICH PAINT NIB --------
DIRECTED BY GEOTECHNICAL CONSTRUCTION.'8 HOOKS TO BE PLACED UNDER LOWER REINFORCING
ENGINEER STEEL 6'CLAY SOIL
85B'10.6'CONC.BASE REINFORCE WITH/4 BARS AT 12'O.C.TO' LINER
AND BOTTOM OF EACH DIRECTION PROVIDE 3'MIN.CLEARANCE MAIN POOL
62'-18'HOPE®0.65% BETWEEN EDGE OF CONC.AND STEEL REINFORCING.
PROFILE OF WET POND DETENTION SYSTEM
SCALE N.T.S.

6'TOPSOIL FOR ALL
AREAS ABOVE THE
NORMAL POND ELEVATION
FOREBAY BER FOREBAY TOP ELEV=171.6
WIDTH AT TOP=2.0 FT
6'TOPSOIL ABOVE
6'CLAY LINER 3:1 NOTE PUMPS SHALL BE USED TO DRAIN
ON LITTORAL SHELF THE FOREBAY WHEN NECESSARY. REFER TO DETAIL
E1WNG GRADE-175.0f = = SEDIMENT STORAGE THIS SHEET FOR DEWATERING REQUIREMENTS.
TOP
6FT LITTORAL - FOREBAY BOTTOM Y�
SHELF 6:1 I ELEV=167.0
NORMAL POND ELEVATION
2 - - - BOTTOM LITTORAL SHELF ELEV.
1 I I-I 11- -
CLASS B RP-RAP OVER FILTER _
FABRIC MIN.4!FOREBAY - I_
WEIR AT ELEV=169.0 -
_I
6'TOPSOIL FOR ALL
FOREBAY ENTRANCE SHALL BE AREAS ABOVE THE
DEEPER THAN FOREBAY SNIT - NORMAL POND ELEVATION
BOTTOM OF SEDIMENT
_ STORAGE/EAT BOTTOM OF SEDIMENT
ELEV=168.6 STORAGE/ENTRANCE
ELEV=166.6
FOREBAY ENTRANCE SHALL BE FOREBAY
DEEPER THAN FOREBAY EXIT

REMOVABLE TRASH RACK
4'PVC SCREW CAP RISER STRUCTURE
EMERGENCY WEIR FOR CLEANING ACCESS
ELEV=173.0
INTERMEDIATE WEIR
ELEV=172.1
H 12'MIN. EXTEND 4'
2.1 FT PVC
THROUGH
RISER
STRUCTURE
4'0'PVC TEE
PERM.POND ELEV.=170.1 INSTALL 4'PVC SCREW
A CAP AT OF TEE
4'OPENING CORED INTO AND DRILLLJ01.DIA.
SIDE OF PRECAST HOLE INTO PVC CAP
STRUCTURE AT ELEV=170.1
INV=170.1
OUTLET PIPE 12'MIN.
INV=169.9
4'DIA.OPENING
SECTION B—B
PVC DRAIN OUTLET
SCALE: N.T.S.
TOP OF STRUCTURE NOT SHOWN FOR CLARITY
Top OF Hf7R` (REMOVABLE TRASH RACK)
1730
l/vo, q7F
OUTLET CONTROL STRUCTURE-INCREMENTAL WEIR
SCALE: N.T.S.

1
Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®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) (cuft) (ft) (cuft)
1 SCS Runoff 0.396 2 732 5,177 ------ ------ ------ BMP Pre-Developed
2 SCS Runoff 7.947 2 718 15,976 ------ ------ ------ BMP Post-Developed
3 Reservoir 0.058 2 1444 13,283 2 171.83 13,630 Post Through Pond
4 SCS Runoff 0.323 2 726 2,789 ------ ------ ------ Post Developed-Pond Bypass
6 SCS Runoff 0.048 2 360 376 ------ ------ ------ BMP Post-Developed
7 Reservoir 0.004 2 366 271 6 170.15 362 1.0-in Storm Thru Pond
Wet Pond-Dunn Erwin.gpw Return Period: 1 Year Friday, 08/ 18/2023

2
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 1
BMP Pre-Developed
Hydrograph type = SCS Runoff Peak discharge = 0.396 cfs
Storm frequency = 1 yrs Time to peak = 732 min
Time interval = 2 min Hyd. volume = 5,177 cuft
Drainage area = 8.740 ac Curve number = 53.3
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.90 min
Total precip. = 3.05 in Distribution = Type II
Storm duration = 24 hrs 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
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

3
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 2
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 7.947 cfs
Storm frequency = 1 yrs Time to peak = 718 min
Time interval = 2 min Hyd. volume = 15,976 cuft
Drainage area = 5.050 ac Curve number = 73.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 5.00 min
Total precip. = 3.05 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
BMP Post-Developed
Q (cfs) Hyd. No. 2 -- 1 Year Q (cfs)
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 1320 1440 1560
Hyd No. 2 Time (min)

4
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 3
Post Through Pond
Hydrograph type = Reservoir Peak discharge = 0.058 cfs
Storm frequency = 1 yrs Time to peak = 1444 min
Time interval = 2 min Hyd. volume = 13,283 cuft
Inflow hyd. No. = 2 - BMP Post-Developed Max. Elevation = 171.83 ft
Reservoir name = BMP Pond Max. Storage = 13,630 cuft
Storage Indication method used.
Post Through Pond
Q (cfs) Hyd. No. 3 -- 1 Year Q (cfs)
8.00 8.00
6.00 6.00
4.00 4.00
2.00 2.00
0.00 0.00
0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Time (min)
Hyd No. 3 Hyd No. 2 0 Total storage used = 13,630 cuft

Pond Report 5
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Pond No. 1 - BMP Pond
Pond Data
Contours-User-defined contour areas.Average end area method used for volume calculation. Begining Elevation= 170.10 ft
Stage/Storage Table
Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cult) Total storage(cult)
0.00 170.10 6,140 0 0
0.50 170.60 7,425 3,391 3,391
1.50 171.60 8,770 8,098 11,489
1.90 172.00 9,520 3,658 15,147
2.00 172.10 9,645 958 16,105
2.90 173.00 10,835 9,216 25,321
3.90 174.00 12,210 11,523 36,844
4.50 174.60 13,060 7,581 44,425
Culvert/Orifice Structures Weir Structures
[A] [B] [C] [PrfRsr] [A] [B] [C] [D]
Rise(in) = 18.00 1.30 0.00 0.00 Crest Len(ft) = 2.10 13.90 0.00 0.00
Span(in) = 18.00 1.30 0.00 0.00 Crest El.(ft) = 172.10 173.00 0.00 0.00
No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 2.60 3.33 3.33
Invert El.(ft) = 169.90 170.10 0.00 0.00 Weir Type = Rect Broad --- ---
Length(ft) = 62.00 0.50 0.00 0.00 Multi-Stage = Yes Yes No No
Slope(%) = 0.65 1.00 0.00 n/a
N-Value = .013 .013 .013 n/a
Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000(by Contour)
Multi-Stage = n/a Yes No No TW Elev.(ft) = 0.00
Note:Culvert/Orifice outflows are analyzed under inlet(ic)and outlet(oc)control. Weir risers checked for orifice conditions(ic)and submergence(s).
Stage(ft) Stage/ Discharge Elev(ft)
5.00 175.10
OOF
4.00 174.10
.100
3.00 173.10
2.00 172.10
1.00 171.10
0.00 170.10
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00
Total Q Discharge(cfs)

6
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 4
Post Developed - Pond Bypass
Hydrograph type = SCS Runoff Peak discharge = 0.323 cfs
Storm frequency = 1 yrs Time to peak = 726 min
Time interval = 2 min Hyd. volume = 2,789 cuft
Drainage area = 3.680 ac Curve number = 54.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 3.05 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post Developed - Pond Bypass
Q (cfs) Hyd. No. 4 -- 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
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

7
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 6
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 0.048 cfs
Storm frequency = 1 yrs Time to peak = 360 min
Time interval = 2 min Hyd. volume = 376 cuft
Drainage area = 5.050 ac Curve number = 73.8
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
BMP Post-Developed
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
0.00 0.00
0 60 120 180 240 300 360 420
Hyd No. 6 Time (min)

8
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 7
1.0-in Storm Thru Pond
Hydrograph type = Reservoir Peak discharge = 0.004 cfs
Storm frequency = 1 yrs Time to peak = 366 min
Time interval = 2 min Hyd. volume = 271 cuft
Inflow hyd. No. = 6 - BMP Post-Developed Max. Elevation = 170.15 ft
Reservoir name = BMP Pond Max. Storage = 362 cuft
Storage Indication method used.
1.0-in Storm Thru Pond
Q (cfs) Hyd. No. 7 -- 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
0.00 0.00
0 240 480 720 960 1200 1440 1680 1920 2160 2400 2640
Time (min)
Hyd No. 7 Hyd No. 6 0 Total storage used = 362 cuft

Pond Report 9
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Pond No. 1 - BMP Pond
Pond Data
Contours-User-defined contour areas.Average end area method used for volume calculation. Begining Elevation= 170.10 ft
Stage/Storage Table
Stage(ft) Elevation(ft) Contour area(sqft) Incr.Storage(cult) Total storage(cult)
0.00 170.10 6,140 0 0
0.50 170.60 7,425 3,391 3,391
1.50 171.60 8,770 8,098 11,489
1.90 172.00 9,520 3,658 15,147
2.00 172.10 9,645 958 16,105
2.90 173.00 10,835 9,216 25,321
3.90 174.00 12,210 11,523 36,844
4.50 174.60 13,060 7,581 44,425
Culvert/Orifice Structures Weir Structures
[A] [B] [C] [PrfRsr] [A] [B] [C] [D]
Rise(in) = 18.00 1.30 0.00 0.00 Crest Len(ft) = 2.10 13.90 0.00 0.00
Span(in) = 18.00 1.30 0.00 0.00 Crest El.(ft) = 172.10 173.00 0.00 0.00
No.Barrels = 1 1 0 0 Weir Coeff. = 3.33 2.60 3.33 3.33
Invert El.(ft) = 169.90 170.10 0.00 0.00 Weir Type = Rect Broad --- ---
Length(ft) = 62.00 0.50 0.00 0.00 Multi-Stage = Yes Yes No No
Slope(%) = 0.65 1.00 0.00 n/a
N-Value = .013 .013 .013 n/a
Orifice Coeff. = 0.60 0.60 0.60 0.60 Exfil.(in/hr) = 0.000(by Contour)
Multi-Stage = n/a Yes No No TW Elev.(ft) = 0.00
Note:Culvert/Orifice outflows are analyzed under inlet(ic)and outlet(oc)control. Weir risers checked for orifice conditions(ic)and submergence(s).
Stage(ft) Stage/ Discharge Elev(ft)
5.00 175.10
OOF
4.00 174.10
.100
3.00 173.10
2.00 172.10
1.00 171.10
0.00 170.10
0.00 2.00 4.00 6.00 8.00 10.00 12.00 14.00 16.00 18.00
Total Q Discharge(cfs)

10
Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®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) (cuft) (ft) (cuft)
1 SCS Runoff 1.968 2 726 11,059 ------ ------ ------ BMP Pre-Developed
2 SCS Runoff 11.81 2 718 23,613 ------ ------ ------ BMP Post-Developed
3 Reservoir 0.242 2 1026 19,593 2 172.19 16,979 Post Through Pond
4 SCS Runoff 1.292 2 724 5,669 ------ ------ ------ Post Developed-Pond Bypass
6 SCS Runoff 0.000 2 n/a 0 ------ ------ ------ BMP Post-Developed
7 Reservoir 0.000 2 n/a 0 6 170.10 0.000 1.0-in Storm Thru Pond
Wet Pond-Dunn Erwin.gpw Return Period: 2 Year Friday, 08/ 18/2023

11
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 1
BMP Pre-Developed
Hydrograph type = SCS Runoff Peak discharge = 1.968 cfs
Storm frequency = 2 yrs Time to peak = 726 min
Time interval = 2 min Hyd. volume = 11,059 cuft
Drainage area = 8.740 ac Curve number = 53.3
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.90 min
Total precip. = 3.71 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
BMP Pre-Developed
Q (cfs) Hyd. No. 1 -- 2 Year Q (cfs)
2.00 2.00
1.00 1.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

12
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 2
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 11.81 cfs
Storm frequency = 2 yrs Time to peak = 718 min
Time interval = 2 min Hyd. volume = 23,613 cuft
Drainage area = 5.050 ac Curve number = 73.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 5.00 min
Total precip. = 3.71 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
BMP Post-Developed
Q (cfs) Hyd. No. 2 -- 2 Year Q (cfs)
12.00 12.00
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 1320 1440 1560
Hyd No. 2 Time (min)

13
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 3
Post Through Pond
Hydrograph type = Reservoir Peak discharge = 0.242 cfs
Storm frequency = 2 yrs Time to peak = 1026 min
Time interval = 2 min Hyd. volume = 19,593 cuft
Inflow hyd. No. = 2 - BMP Post-Developed Max. Elevation = 172.19 ft
Reservoir name = BMP Pond Max. Storage = 16,979 cuft
Storage Indication method used.
Post Through Pond
Q (cfs) Hyd. No. 3 -- 2 Year Q (cfs)
12.00 12.00
10.00 10.00
8.00 8.00
6.00 6.00
4.00 4.00
2.00 2.00
0.00 0.00
0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Time (min)
Hyd No. 3 Hyd No. 2 0 Total storage used = 16,979 cuft

14
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 4
Post Developed - Pond Bypass
Hydrograph type = SCS Runoff Peak discharge = 1.292 cfs
Storm frequency = 2 yrs Time to peak = 724 min
Time interval = 2 min Hyd. volume = 5,669 cuft
Drainage area = 3.680 ac Curve number = 54.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 3.71 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post Developed - Pond Bypass
Q (cfs) Hyd. No. 4 -- 2 Year Q (cfs)
2.00 2.00
1.00 1.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

15
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 6
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 0.000 cfs
Storm frequency = 2 yrs Time to peak = n/a
Time interval = 2 min Hyd. volume = 0 cuft
Drainage area = 5.050 ac Curve number = 73.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 5.00 min
Total precip. = 0.00 in Distribution = SCS 6-Hr
Storm duration = 6.00 hrs Shape factor = 484
BMP Post-Developed
Q (cfs) Hyd. No. 6 -- 2 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
0.00 0.00
0 20 40 60 80 100 120
Hyd No. 6 Time (min)

16
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 7
1.0-in Storm Thru Pond
Hydrograph type = Reservoir Peak discharge = 0.000 cfs
Storm frequency = 2 yrs Time to peak = n/a
Time interval = 2 min Hyd. volume = 0 cuft
Inflow hyd. No. = 6 - BMP Post-Developed Max. Elevation = 170.10 ft
Reservoir name = BMP Pond Max. Storage = 0 cuft
Storage Indication method used.
1.0-in Storm Thru Pond
Q (cfs) Hyd. No. 7 -- 2 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
0.00 0.00
0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Time (min)
Hyd No. 7 Hyd No. 6 0 Total storage used = 0 cuft

17
Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®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) (cuft) (ft) (cuft)
1 SCS Runoff 11.08 2 724 36,153 ------ ------ ------ BMP Pre-Developed
2 SCS Runoff 24.03 2 716 48,548 ------ ------ ------ BMP Post-Developed
3 Reservoir 3.668 2 728 44,444 2 172.74 22,686 Post Through Pond
4 SCS Runoff 6.109 2 722 17,548 ------ ------ ------ Post Developed-Pond Bypass
6 SCS Runoff 0.000 2 n/a 0 ------ ------ ------ BMP Post-Developed
7 Reservoir 0.000 2 n/a 0 6 170.10 0.000 1.0-in Storm Thru Pond
Wet Pond-Dunn Erwin.gpw Return Period: 10 Year Friday, 08/ 18/2023

18
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 1
BMP Pre-Developed
Hydrograph type = SCS Runoff Peak discharge = 11.08 cfs
Storm frequency = 10 yrs Time to peak = 724 min
Time interval = 2 min Hyd. volume = 36,153 cuft
Drainage area = 8.740 ac Curve number = 53.3
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.90 min
Total precip. = 5.59 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
BMP Pre-Developed
Q (cfs) Hyd. No. 1 -- 10 Year Q (cfs)
12.00 12.00
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 1320 1440 1560
Hyd No. 1 Time (min)

19
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 2
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 24.03 cfs
Storm frequency = 10 yrs Time to peak = 716 min
Time interval = 2 min Hyd. volume = 48,548 cuft
Drainage area = 5.050 ac Curve number = 73.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 5.00 min
Total precip. = 5.59 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
BMP Post-Developed
Q (cfs) Hyd. No. 2 -- 10 Year Q (cfs)
28.00 28.00
24.00 24.00
20.00 20.00
16.00 16.00
12.00 12.00
8.00 8.00
4.00 4.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)

20
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 3
Post Through Pond
Hydrograph type = Reservoir Peak discharge = 3.668 cfs
Storm frequency = 10 yrs Time to peak = 728 min
Time interval = 2 min Hyd. volume = 44,444 cuft
Inflow hyd. No. = 2 - BMP Post-Developed Max. Elevation = 172.74 ft
Reservoir name = BMP Pond Max. Storage = 22,686 cuft
Storage Indication method used.
Post Through Pond
Q (cfs) Hyd. No. 3 -- 10 Year Q (cfs)
28.00 28.00
24.00 24.00
20.00 20.00
16.00 16.00
12.00 12.00
8.00 8.00
4.00 4.00
0.00 0.00
0 480 960 1440 1920 2400 2880 3360 3840 4320 4800 5280
Time (min)
Hyd No. 3 Hyd No. 2 0 Total storage used = 22,686 cuft

21
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 4
Post Developed - Pond Bypass
Hydrograph type = SCS Runoff Peak discharge = 6.109 cfs
Storm frequency = 10 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 17,548 cuft
Drainage area = 3.680 ac Curve number = 54.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 5.59 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post Developed - Pond Bypass
Q (cfs) Hyd. No. 4 -- 10 Year Q (cfs)
7.00 7.00
6.00 6.00
5.00 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 1320 1440 1560
Hyd No. 4 Time (min)

22
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 6
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 0.000 cfs
Storm frequency = 10 yrs Time to peak = n/a
Time interval = 2 min Hyd. volume = 0 cuft
Drainage area = 5.050 ac Curve number = 73.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 5.00 min
Total precip. = 0.00 in Distribution = SCS 6-Hr
Storm duration = 6.00 hrs Shape factor = 484
BMP Post-Developed
Q (cfs) Hyd. No. 6 -- 10 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
0.00 0.00
0 20 40 60 80 100 120
Hyd No. 6 Time (min)

23
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 7
1.0-in Storm Thru Pond
Hydrograph type = Reservoir Peak discharge = 0.000 cfs
Storm frequency = 10 yrs Time to peak = n/a
Time interval = 2 min Hyd. volume = 0 cuft
Inflow hyd. No. = 6 - BMP Post-Developed Max. Elevation = 170.10 ft
Reservoir name = BMP Pond Max. Storage = 0 cuft
Storage Indication method used.
1.0-in Storm Thru Pond
Q (cfs) Hyd. No. 7 -- 10 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
0.00 0.00
0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Time (min)
Hyd No. 7 Hyd No. 6 0 Total storage used = 0 cuft

24
Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk®Civil 3D®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) (cuft) (ft) (cuft)
1 SCS Runoff 33.28 2 724 96,328 ------ ------ ------ BMP Pre-Developed
2 SCS Runoff 46.70 2 716 96,005 ------ ------ ------ BMP Post-Developed
3 Reservoir 15.82 2 724 91,854 2 174.28 40,415 Post Through Pond
4 SCS Runoff 17.22 2 722 45,347 ------ ------ ------ Post Developed-Pond Bypass
6 SCS Runoff 0.000 2 n/a 0 ------ ------ ------ BMP Post-Developed
7 Reservoir 0.000 2 n/a 0 6 170.10 0.000 1.0-in Storm Thru Pond
Wet Pond-Dunn Erwin.gpw Return Period: 100 Year Friday, 08/ 18/2023

25
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 1
BMP Pre-Developed
Hydrograph type = SCS Runoff Peak discharge = 33.28 cfs
Storm frequency = 100 yrs Time to peak = 724 min
Time interval = 2 min Hyd. volume = 96,328 cuft
Drainage area = 8.740 ac Curve number = 53.3
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.90 min
Total precip. = 8.76 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
BMP Pre-Developed
Q (cfs) Hyd. No. 1 -- 100 Year Q (cfs)
35.00 35.00
30.00 30.00
25.00 25.00
20.00 20.00
15.00 15.00
10.00 10.00
5.00 5.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

26
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 2
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 46.70 cfs
Storm frequency = 100 yrs Time to peak = 716 min
Time interval = 2 min Hyd. volume = 96,005 cuft
Drainage area = 5.050 ac Curve number = 73.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 5.00 min
Total precip. = 8.76 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
BMP Post-Developed
Q (cfs) Hyd. No. 2 -- 100 Year Q (cfs)
50.00 50.00
40.00 40.00
30.00 30.00
20.00 20.00
10.00 10.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320
Hyd No. 2 Time (min)

27
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 3
Post Through Pond
Hydrograph type = Reservoir Peak discharge = 15.82 cfs
Storm frequency = 100 yrs Time to peak = 724 min
Time interval = 2 min Hyd. volume = 91,854 cuft
Inflow hyd. No. = 2 - BMP Post-Developed Max. Elevation = 174.28 ft
Reservoir name = BMP Pond Max. Storage = 40,415 cuft
Storage Indication method used.
Post Through Pond
Q (cfs) Hyd. No. 3 -- 100 Year Q (cfs)
50.00 50.00
40.00 40.00
30.00 30.00
20.00 20.00
10.00 10.00
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 0 Total storage used =40,415 cuft

28
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 4
Post Developed - Pond Bypass
Hydrograph type = SCS Runoff Peak discharge = 17.22 cfs
Storm frequency = 100 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 45,347 cuft
Drainage area = 3.680 ac Curve number = 54.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 10.00 min
Total precip. = 8.76 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
Post Developed - Pond Bypass
Q (cfs) Hyd. No. 4 -- 100 Year Q (cfs)
18.00 18.00
15.00 15.00
12.00 12.00
9.00 9.00
6.00 6.00
3.00 3.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

29
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 6
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 0.000 cfs
Storm frequency = 100 yrs Time to peak = n/a
Time interval = 2 min Hyd. volume = 0 cuft
Drainage area = 5.050 ac Curve number = 73.8
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 5.00 min
Total precip. = 0.00 in Distribution = SCS 6-Hr
Storm duration = 6.00 hrs Shape factor = 484
BMP Post-Developed
Q (cfs) Hyd. No. 6-- 100 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
0.00 0.00
0 20 40 60 80 100 120
Hyd No. 6 Time (min)

30
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Friday,08/18/2023
Hyd. No. 7
1.0-in Storm Thru Pond
Hydrograph type = Reservoir Peak discharge = 0.000 cfs
Storm frequency = 100 yrs Time to peak = n/a
Time interval = 2 min Hyd. volume = 0 cuft
Inflow hyd. No. = 6 - BMP Post-Developed Max. Elevation = 170.10 ft
Reservoir name = BMP Pond Max. Storage = 0 cuft
Storage Indication method used.
1.0-in Storm Thru Pond
Q (cfs) Hyd. No. 7-- 100 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
0.00 0.00
0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Time (min)
Hyd No. 7 Hyd No. 6 0 Total storage used = 0 cuft

NORTH North American Green
MRICN 5401 St. Wendel-Cynthiana Rd.
1� Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
>>>Grass Channel
Name Grass Channel
Discharge 4.75
Channel Slope 0.0111
Channel Bottom Width 3
Left Side Slope 2
Right Side Slope 2
Low Flow Liner
Retardence Class C 6-12 in
Vegetation Type Mix(Sod and Bunch)
Vegetation Density Very Good 80-95%
Soil Type Sandy Loam(GM)
Unreinforced Vegetation
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Depth Mannings N Shear Stress Shear Stress Remarks Factor Pattern
Unreinforced Straight 4.75 cfs 1.44 ft/s 0.74 ft 0.07 4 Ibs/ft2 0.51 Ibs/ft2 7.86 STABLE -
Vegetation
Underlying Straight 4.75 cfs 1.44 ft/s 0.74 ft 0.07 4 Ibs/ft2 0.36 Ibs/ft2 11.05 STABLE -
Substrate
DS75
Phase Reach Discharge Velocity
Normal Mannings N Permissible Calculated Safety Staple
Depth Shear Stress Shear Stress Remarks Factor Pattern
DS75 Straight 4.75 cfs 2.33 ft/s 0.51 ft 0.036 1.6 Ibs/ft2 0.35 Ibs/ft2 4.55 STABLE D
Unvegetated
Underlying Straight 4.75 cfs 2.33 ft/s 0.51 ft 0.036 1.51 Ibs/ft2 0.27 Ibs/ft2 5.65 STABLE D
Substrate

Bowman North Carolina,Ltd.
Erwin Road Residential Dunn,NC-Storm Drain"C"calculations
Rational Runoff Coefficient"C"
Grass Channe1#1
Drainage Area(acres): 2.43
Proposed Land Uses:
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.03 1% 0.95 0.01
Asphalt/Concrete Pavement 0.00 0% 0.95 0.00
Lawn 0.92 38% 0.3 0.11
Wooded 1.49 61% 0.2 0.12
Total Area= 2.43 Cumulative"C= 0.25
ii0= 7.92
Q10= 4.75
Grass Channel#2
Drainage Area(acres): 1275.38
Proposed Land Uses.,
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.00 0% 0.95 0.00
Asphalt/Concrete Pavement 0.01 0% 0.95 0.00
Lawn 1275.37 100% 0.3 0.30
Wooded 0.00 0% 0.2 0.00
Total Area= 1275.38 Cumulative"C"= 0.30
ii0= 7.92
Q1 0= 3030.36

Erwin Road Residential Spread Calculations Bowman North Carolina, Ltd.
919-553-6570
Inlet Capacity Chart
Rainfall Intensity = 7.92 in/hr Single Sump (Type E grate, P = 6.94ft)
Maximum Spread = 7 feet Double Sump (Type E grate, P = 9.92ft)
Inlet # Inlet Q Surface Q Slope K or P Inlet Qcap Spread Bypass Remarks
Drainage Area C Sub. Bypass Total Long. Trans. Q To Inlet #
CB-106 0.22 0.52 0.91 0.00 0.91 0.015 0.02 24 0.79 6.44 0.12 CB-105 bypass
CB-105 1.49 0.44 5.19 0.12 5,31 0.015 0.02 6.94 0.69 12.50 4.62 CB-104 sag
CB-104 0.19 0.82 1.23 4.62 5.86 0.015 0.02 6.94 0.73 12.96 5.12 CB-103 sa
CB-103 0.63 0.53 2.64 5.12 7,77 0.015 0.02 6.94 0.87 14.41 6.90 CB-102 sag
CB-102 0.13 0.82 0.84 6.90 7,74 0.015 0.02 6.94 0.87 14.39 6.87 CB-101 sag
CB-107 0.88 0.56 3.90 0.00 3.90 0.015 0.022 6.94 0.60 10.49 3.30 CB-101 sag
CB-101 0.15 0.62 0.74 10.17 10.91 0.015 0.02 6.94 1.08 16.37 9.83 sag

Bowman
[Von7H .AR0 LIMA
APPENDIX C
Storm Drainage System Calculations
100-System
Erwin Road Residential—Dunn, NC 10 1 P a g e

61
9.4
N 18" DIP IE' 161.07
N _ PIN #1506_
'�- ` OUT 18" DIP IE: 161.02 79-1980
� 1 R#A06-79_1792 '�-_ � BRENT S C
p DA �' _ �s� DB 629, P CRANE TORE
I CKE __
DB 388I C 9R -_�--_\���\ ��\\ ZONING R#10 AND R- ANNUALONS
CHANCE CHANCE FLOOD \
I ZONING #160 _ 20 HAZARD ( \
R'10 AND � �_ FLOOD HAZARD (GIs)
1511 -_ R-20 ��\S � _ (GIS) �\ PAN R 1 WE
5
SMH # 1 �- \ �'
RIM: 176.96 \� _ DB 3
P1N _ \�`� s\�\ \SL10 ER
y CARY #1508_79- ��_ `. _ �/ Zo
�= MAC KCST 261 _ I I \ 09'39'19' E-611.63' TOTAL 381.63'
SMH #1564 I 2 - \ \ `
RIM: 176,48 I OB 146HEIM & CARRIE S�# _ \\ \ \ EASEMENT
PVC IE: 170.02 b D' PG 418 E2 LIN _�'- ` � 15' SANITARY SEWER PROJECT:
(A) IN 8" i y� 0 20NING R#�D00 210.00' \ \ PER CITY OF DUNN -
B IN 6" DIP IE: 171.01 1 \ �Id LINE \� \ 451 10
( ) 169.90 �- AND R,20 � \ \ \`` � E-451-03 AND E-PG 719
OUT 8"PVC IE: (B) ' __ V \ DB 687,
�- Z IRS (#5) I \ \\ \ \
6 DI� P1 N #150 7 __ �x ON LINE SMH #1351 \
I a DONALD 6 9'2558
NANCY I• JOHNSON & ` \\ \ s��� RN 18" DIP IE: 161.07 N 89'21'51"
W J i '
DB 927 OHNSON �� �� OUT 18" DIP IE: 161.07 E
3508 FG 622 \ _
PIN #1506-79- � #1510 �� � � � � �— � � 352.56 TOTAL
JOHNSON I
DONALD ►• ' ZONING R_10 � \ //^��� � � �
44, PG 739 ` s -� —
ZONING R-10 I w01 ——
i 69 `-�_ _s — \ SMH #
��c__ 1325
" I I pop RIM: 169.69
\ C top = —1�F--- �- (A) IN 8" PVC IE: 162.
0 • 7. \ _ s��-;� g IN18" DIPIE: 161.
d F \ IRS \ — �- — — _ s\ \--- OUT 18" DIP IE: 161.51
1003 \� / \ _W -_ SSAs _
SMH # °/ \ \ _ L14
RIM: 178.75 \ �� _ __ _
J J
CB-1 04 / ��s-. _ - - -- -
IN 8" PVC IE.. 171.17 $ \ 1 \ \s '-- -- -- -_ - cfl c
171.14 \ 18"�pIP N M E o
R PVC IE.. o H
OUT 8" \ \ / CB-102 _� `� �(��5 -- _1� DI � o � z
#132E \ \ \ Z co T 3 0
Z
- — . 1 169.91 ��\ \ 15' o J o
RK mi \ C B 101 ——— \ IN 18 DIP IE. 1.51, \ \ \ \ \ EA
J J \ \\ r)UT 18" DIP IE: ' \ SL m a 0
co
I o \ \
AT CAB
° \ \ SLIDE 127
SMH p052
RIM: 182.51 i \
" PVC IE: 175.06 \ ' CB-103
IN 8 I ° 5
OUT IE:175.01 / S � ) � \
$" PVC `�\ m CB-106
I V(#) \\ \ 1 CB-107
\ \ \
\ \ m \ 5.43 43 143.67' \\ I
5448 \ � \
45 \ A INE s1& RALPH9D. LUCAS \ I \ \ \ N ��'' Z
PG 373 as \ 1 \ ' 5 ~
9� O �DB 4084, \
m
- I .
I� \ ZONING R-1� c — O O
\67�cg21\ F-
F-
\
\ � l
o
IRS (#5) JJ \\ `\ h--1 Q z
0 I N _ _\ / \ I \ L3, ""I O Cc
_ (#3) / Q
14 ^ IRS / / I ` \\ I I I L
- \ I / — — — 1 � / I � — ' 1 � � PIN #1506-79-5869 \ I� CONC
#1074 �
R�64 \ ° / J2M2 HOLDINGS, LLC
I I — — DB 4184, PG 339 a� r ' \ wll
- 4� m / \ I I ROAD
AND R-20 / " h--i W
PIN #1506-79 5 _ — — _ I \ 1 \ ZONING R / S 52'20'04 E
QARE, LLCM \ 1 _ 9.04 ACRES
� � AREA: � / � ' 51.28' TIE � Z
DB 4084, PG 373 • / \ I ` ,
ZONING R-10 �� m l — — — — — J \ / ~
i �
� z
(FULL OF DEBRIS) I I ( — — �. • \ `�.`�g 3 "
CB #1152 / \ — — — — — 1 z \\ I �\ / PIN #1507-70-80TA PIN #
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PRELIMINARY
DO NOT
USE FOR
CONSTRUCTION
PLAN STATUS
DATE DESCRIPTION
XXX XXX XXX
DESIGN DRAWN CHKD
SCALE H: 1„ =XXX;
V. 1 = XXX
GRAPHIC SCALE OB No. 220124-01-004
50 0 25 50 100 200 DATE _ 2023
FILE No.
( IN FEET )
1 inch = 50 ft. ����
SHEET
Cad file name: V:\220124 - Ben Stout Construction\220124-01-004 (ENG) - Erwin Road, Dunn, NC\Engineering\Engineering Plans\Construction Documents\220124-01-004-DDP (Inlets).dwg

Bowman North Carolina,Ltd.
Erwin Road Residential Dunn,NC-Storm Drain"C"calculations
Rational Runoff Coefficient"C"
Catch Basin #101
Drainaoe Area(acres): 0.151
Proposed Land Uses:
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.03 19% 0.95 0.18
Asphalt/Concrete Pavement 0.05 31% 0.95 0.30
Lawn 0.08 50% 0.3 0.15
Wooded 0.00 0% 0.2 0.00
Total Area= 0.15 1 Cumulative"C"= 0.62
iio= 7.92
Q10= 0.75
Catch Basin #102
Drainaoe Area(acres): 0.133
Proposed Land Uses:
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.00 0% 0.95 0.00
Asphalt/Concrete Pavement 0.11 80% 0.95 0.76
Lawn 0.03 20% 0.3 0.06
Wooded 0.00 0% 0.2 0.00
Total Area= 0.13 1 Cumulative"C"= 0.82
iio= 7.92
Q10= 0.86
Catch Basin #103
Drainaoe Area(acres): 0.629
Proposed Land Uses:
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.11 18% 0.95 0.17
Asphalt/Concrete Pavement 0.11 17% 0.95 0.16
Lawn 0.41 65% 0.3 0.20
Wooded 0.00 0% 0.2 0.00
Total Area= 0.63 Cumulative"C= 0.53
iio= 7.92
Q1o= 2.62
Catch Basin #104
Drainaoe Area(acres): 0.193
Proposed Land Uses:
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.00 0% 0.95 0.00
Asphalt/Concrete Pavement 0.15 80% 0.95 0.76
Lawn 0.04 20% 0.3 0.06
Wooded 0.00 0% 0.2 0.00
Total Area= 0.19 1 Cumulative"C= 0.82
iio= 7.92
Q1o= 1.25

Catch Basin #105
Drainaoe Area(acres): 1.493
Proposed Land Uses:
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.20 14% 0.95 0.13
Asphalt/Concrete Pavement 0.16 10% 0.95 0.10
Lawn 0.97 65% 0.3 0.19
Wooded 0.17 11% 0.2 0.02
Total Area= 1.49 Cumulative"C"= 0.44
H o= 7.92
Q10= 5.26
Catch Basin #106
Drainage Area(acres): 0.224
Proposed Land Uses:
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.03 13% 0.95 0.12
Asphalt/Concrete Pavement 0.05 22% 0.95 0.21
Lawn 0.13 60% 0.3 0.18
Wooded 0.01 5% 0.2 0.01
Total Area= 0.22 1 Cumulative"C"= 0.52
H O= 7.92
Q10= 0.93
Catch Basin #107
Drainaoe Area(acres): 0.879
Proposed Land Uses:
Land Use Description Acres %site Runoff"C" "C"
Roofs 0.17 19% 0.95 0.18
Asphalt/Concrete Pavement 0.18 20% 0.95 0.19
Lawn 0.53 61% 0.3 0.18
Wooded 0.00 0% 0.2 0.00
Total Area= 0.88 1 Cumulative"C"= 0.56
H O= 7.92
Q10= 3.86

Hydraflow Storm Sewers Extension for Autodesk® Civil 3D® Plan
CB#107
Outfall
7 v
1
46
CB#101
2 ,NO
CB#102 6
4g CB#103
3 ;
4
CB#104 43 CB#105
h
5'A
CB#106
Project File: 100 System.stm Number of lines:7 Date:7/19/2023
Storm Sewers v2022.00

Storm Sewer Inventory Report Page
Line Alignment Flow Data Physical Data Line ID
No.
Dnstr Line Defl Junc Known Drng Runoff Inlet Invert Line Invert Line Line N J-Loss Inlet/
Line Length angle Type Q Area Coeff Time El Dn Slope El Up Size Shape Value Coeff Rim El
No. (ft) (deg) (cfs) (ac) (C) (min) (ft) M (ft) (in) (n) (K) (ft)
1 End 50.844 25.602 Comb 0.00 0.15 0.62 5.0 169.50 0.59 169.80 24 Cir 0.012 1.50 175.91 46
2 1 120.664 84.626 Comb 0.00 0.13 0.82 5.0 170.00 0.58 170.70 24 Cir 0.012 1.50 175.00 42
3 2 200.183 -1.274 Comb 0.00 0.63 0.53 5.0 170.80 0.55 171.90 18 Cir 0.012 1.50 175.52 44
4 3 29.723 -86.632 Comb 0.00 0.19 0.82 5.0 172.60 1.01 172.90 15 Cir 0.012 1.47 175.55 43
5 4 175.129 77.338 Comb 0.00 1.49 0.44 5.0 173.10 0.57 174.10 15 Cir 0.012 1.00 178.24 85
6 2 29.014 -88.216 Comb 0.00 0.22 0.52 5.0 171.60 0.69 171.80 15 Cir 0.012 1.00 175.00 45
7 1 86.290 -95.385 Comb 0.00 0.88 0.56 5.0 172.50 0.58 173.00 15 Cir 0.012 1.00 176.00 48
Project File: 100 System.stm Number of lines:7 Date: 7/19/2023
Storm Sewers v2022.00

Storm Sewer Summary Report Page
Line Line ID Flow Line Line Line Invert Invert Line HGL HGL Minor HGL Dns Junction
No. rate Size shape length EL Dn EL Up Slope Down Up loss Junct Line Type
(cfs) (in) (ft) (ft) (ft) M (ft) (ft) (ft) (ft) No.
1 46 12.93 24 Cir 50.844 169.50 169.80 0.590 170.72 171.09 n/a 171.09 End Combination
2 42 9.29 24 Cir 120.664 170.00 170.70 0.580 171.09 171.79 n/a 171.79 j 1 Combination
3 44 8.01 18 Cir 200.183 170.80 171.90 0.549 171.97 173.07 0.69 173.75 2 Combination
4 43 5.70 15 Cir 29.723 172.60 172.90 1.009 173.75 173.87 n/a 173.87 j 3 Combination
5 85 4.75 15 Cir 175.129 173.10 174.10 0.571 174.03 175.02 0.37 175.39 4 Combination
6 45 0.83 15 Cir 29.014 171.60 171.80 0.689 171.92 172.16 0.13 172.16 2 Combination
7 48 3.56 15 Cir 86.290 172.50 173.00 0.579 173.25 173.76 n/a 173.76 1 Combination
Project File: 100 System.stm Number of lines:7 Run Date: 7/19/2023
NOTES: Return period= 10 Yrs. ;j-Line contains hyd.jump.
Storm Sewers v2022.00

Storm Sewer Tabulation Pagel
Station Len Drng Area Rnoff Area x C Tc Rain Total Cap Vel Pipe Invert Elev HGL Elev Grnd/Rim Elev Line ID
coeff (1) flow full
Line To Incr Total Incr Total Inlet Syst Size Slope Dn Up Dn Up Dn Up
Line
(ft) (ac) (ac) (C) (min) (min) (in/hr) (cfs) (cfs) (fUs) (in) M (ft) (ft) (ft) (ft) (ft) (ft)
1 End 50.844 0.15 3.69 0.62 0.09 1.95 5.0 7.3 6.6 12.93 18.82 6.24 24 0.59 169.50 169.80 170.72 171.09 0.00 175.91 46
2 1 120.664 0.13 2.66 0.82 0.11 1.37 5.0 6.6 6.8 9.29 18.66 5.30 24 0.58 170.00 170.70 171.09 171.79 175.91 175.00 42
3 2 200.183 0.63 2.31 0.53 0.33 1.15 5.0 5.9 7.0 8.01 8.43 5.43 18 0.55 170.80 171.90 171.97 173.07 175.00 175.52 44
4 3 29.723 0.19 1.68 0.82 0.16 0.81 5.0 5.8 7.0 5.70 7.03 5.21 15 1.01 172.60 172.90 173.75 173.87 175.52 175.55 43
5 4 175.129 1.49 1.49 0.44 0.66 0.66 5.0 5.0 7.2 4.75 5.29 4.87 15 0.57 173.10 174.10 174.03 175.02 175.55 178.24 85
6 2 29.014 0.22 0.22 0.52 0.11 0.11 5.0 5.0 7.2 0.83 5.81 3.11 15 0.69 171.60 171.80 171.92 172.16 175.00 175.00 45
7 1 86.290 0.88 0.88 0.56 0.49 0.49 5.0 5.0 7.2 3.56 5.32 4.60 15 0.58 172.50 173.00 173.25 173.76 175.91 176.00 48
Project File: 100 System.stm Number of lines:7 Run Date: 7/19/2023
NOTES:Intensity=88.24/(Inlet time+ 15.50)^0.83; Return period=Yrs. 10 c=cir e=ellip b=box
Storm Sewers v2022.00

Hydraulic Grade Line Computations Page
Line Size Q Downstream Len Upstream Check JL Minor
coeff loss
Invert HGL Depth Area Vel Vel EGL Sf Invert HGL Depth Area Vel Vel EGL Sf Ave Enrgy
elev elev head elev elev elev head elev Sf loss
(in) (cfs) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) M (ft) (ft) (ft) (ft) (sqft) (ft/s) (ft) (ft) M M (ft) (K) (ft)
1 24 12.93 169.50 170.72 1.22 2.00 6.45 0.56 171.28 0.000 50.844 169.80 171.09 1.29"" 2.15 6.02 0.56 171.66 0.000 0.000 n/a 1.50 n/a
2 24 9.29 170.00 171.09 1.09 1.75 5.29 0.44 171.53 0.000 120.66 1170.70 171.79 j 1.09"" 1.75 5.32 0.44 172.23 0.000 0.000 n/a 1.50 n/a
3 18 8.01 170.80 171.97 1.17" 1.48 5.43 0.46 172.43 0.549 200.18 171.90 173.07 1.17 1.47 5.43 0.46 173.53 0.550 0.550 1.100 1.50 0.69
4 15 5.70 172.60 173.75 1.15 1.02 4.81 0.49 174.24 0.000 29.723 172.90 173.87 j 0.97" 1.02 5.60 0.49 174.35 0.000 0.000 n/a 1.47 0.72
5 15 4.75 173.10 174.03 0.93" 0.97 4.87 0.37 174.39 0.571 175.12 174.10 175.02 0.92 0.97 4.88 0.37 175.39 0.572 0.571 1.001 1.00 0.37
6 15 0.83 171.60 171.92 0.32" 0.25 3.35 0.13 172.05 0.000 29.014 171.80 172.16 0.36"" 0.29 2.87 0.13 172.28 0.000 0.000 n/a 1.00 0.13
7 15 3.56 172.50 173.25 0.75" 0.77 4.65 0.32 173.57 0.000 86.290 173.00 173.76 0.76"" 0.78 4.55 0.32 174.08 0.000 0.000 n/a 1.00 n/a
Project File: 100 System.stm Number of lines:7 Run Date: 7/19/2023
Notes:" depth assumed;""Critical depth.;j-Line contains hyd.jump c=cir e=ellip b=box
Storm Sewers v2022.00

Storm Sewer Profile Proj. file: 100 System.stm
w
C � C 7 C � C 7 C= 7
O p C J Os J O C J O C J C J
O ' N ' 10 '
�' p000 W pF.00 MCA CO t170) M N�
o CO n�o moo m ��I v h�� Iq CO
Elev. (ft) p w � 6 P r r
+p -6W O WWW r WWW CM WWW 7 WWW LO W
Ba W
Ca E > E > ; M E » 'N E » }o E » B E �
rnC� U) D c U) WE U) W U) WE r4 WE
191.00 191.00
186.00 186.00
181.00 181.00
176.00 176.00
- -- -- - - - - - - 0.57%
------------ 2
171.00 ° 171.00
12 -
FBT
0
166.00 166.00
0 50 100 150 200 250 300 350 400 450 500 550 600
HGL EGL Reach (ft)
Storm Sewers

Storm Sewer Profile Proj. file: 100 System.stm
oS _j o
oIZW oCO
opo o �P
Elev. (ft) g r � N
+oWww o ww
caE > > B E >
184.00 184.00
181.00 181.00
178.00 178.00
175.00 175.00
172.00 "' ---------- - - - - - - - - ----- - — - - - 172.00
169.00 169.00
0 10 20 30 40 50 60 70 80 90 100
HGL EGL Reach (ft)
Storm Sewers

Storm Sewer Profile Proj. file: 100 System.stm
o= J o
0
COL o0
O 6N N (6M
Elev. (ft) o `� (6 ``
oWww o ww
m E > > @ E >
65EaS U) ES
185.00 185.00
182.00 182.00
179.00 179.00
176.00 176.00
-------------- ------------------- -------------------------------------- ------
173.00 173.00
If 86.290, @ 0.68
170.00 i L 170.00
0 10 20 30 40 50 60 70 80 90 100
HGL EGL Reach (ft)
Storm Sewers

Bowman
[Von7H .AR0 LIMA
APPENDIX D
Erosion and Sediment Control Calculations
Rip-Rap Calculations
Skimmer Basin
Riser
Temporary Diversion Ditches
Erwin Road Residential—Dunn, NC 11 1 P a g e

EROSION CONTROL CALCS (RIP-RAP CALCULATIONS)
Project Information
Project Name: Erwin Rd Dunn, NC
Project#: 220124-01-004
Designed by: JA Date: 7/3/2023
Revised by: Date:
Checked by: Date:
Rip-Rap Apron#1
Pipe Diameter d= 24
Pipe Slope s= 0.59 %
Manning's number n= 0.013
Flow Q= 12.93 cfs
Velocity V= 4 ft/s
Dissipator Dimensions Zone= 1
Stone Filling Class= A
Entry Width(2 X Do)= 4.0 ft
Length(4 X Do)= 8.0 ft
Width(La+Do)= 10.0 ft
Min.Thickness= 12 inches
Min.Stone Diameter= 3 inches
~ 8.0
1
4.0 10.0
L J�
*All units are in feet
**Dissipator pad designed for full flow of pipe
RIP-RAP_ErwinRd.xlsx 7/19/2023 Page 1 of 5

Rip-Rap Apron#2
Pipe Diameter d= 18 in
Pipe Slope s= 0.62 %
Manning's number n= 0.013
Flow Q=If 4.601 cfs
Velocity V= 2 ft/s
Dissipator Dimensions Zone= 1
Stone Filling Class= A
Entry Width(2 X Do)= 3.0 ft
Length(4 X Do)= 6.0 ft
Width(La+Do)= 7.5 ft
Min.Thickness= 12 inches
Min.Stone Diameter= 3 inches
6.0�
1
3.0 7.5
1
*All units are in feet
**Dissipator pad designed for full flow of pipe
RIP-RAP_ErwinRd.xlsx 7/19/2023 Page 2 of 5

EROSION CONTROL CALCULATIONS(Skimmer Basin)
Project Information
Project Name: Erwin Rd Dunn,NC
Project#: 220124-01-004
Designed by: JA Date: 7/3/2023
Revised by: Date:
Checked by: Date:
Skimmer Basin#1
Drainage Area Total,AT= 6.54 Ac
Disturbed,Ao= 7.94 Ac
10-year Runoff(Q10) C= 0.50
Tp= 5.00 min
110= 7.92 in/hr
010= 25.9 cfs
Surface Area Required SA= 325sf x Q10
SA= 8,422 sf
Volume Required VR= 1800 cf/Ac x Ao
VR= 11,779 cf
Sediment Trap Dimensions L.= 167 ft (Spillway Length)
W= 60 ft (Spillway Width)
D= 2.0 It (Depth of Storage)
Side Slopes= 2:1
Ltop=
Lpp= 175 ft
L.= 159 ft Wt., Wb.
W.w= 68 ft Lhp=
WW= 52 ft
L/W Ratio= 2.8:1(must be 2:1 to 6:1)
Elevations Description Elevation
Top of Berm 174.00 (allow 1ft freeboard above spillway flow height)
Emergency Spillway 172.50
Sediment Storage 172.00
Cleanout Mark 171.00 (half of storage height)
Bottom 170.00
Provided SAP= 10,020 sf > 8,422
VP= 18,288.0 cf > 11,779
Emergency Spillway-10 Year Storm 110= in/hr
Q10= 25.91 cfs
h= 0.5ft
CW= 3
Lw= 25 ft

Calculate Skimmer Size
Basin Volume in Cubic Feet 18,288 Cu.Ft Skimmer Size 2.5 Inch
Days to Drain* 3 Days Orifice Radius 1.2 Inch[es]
Orifice Diameter 2.5 Inch[es]
*In NC assume 3 days to drain
Estimate Volume of Basin Length Width
Top of water surface in feet 167 60 Feet VOLUME 18288 Cu.Ft.
Bottom dimensions in feet 159 521 Feet
Depth in feet 2 Feet

EROSION CONTROL CALCS(SKIMMER BASINS)
Project Information
Project Name: Erwin Rd Dunn,NC
Project#: 220124-01-004
Designed by: JA Date: 7/3/2023
Revised by: Date:
Checked by: Date:
Anti-Flotation Device(Skimmer Basin#1)
4'x 4' Outlet Structure
Area: 16.0 sf
Top of Basin Elev.: 172.0
Bottom of Basin Elev.: 170.0
Volume: 32.0 cf (Water Displaced-Top of Pond to Bottom of Pond)
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 (Unit WT of Concrete=150 pcf)
Volume Provided: 69.5 cf (4'x4'riser x 2.0'=32cf,5'x5'footing x 1.5'=37.5cf)

EROSION CONTROL CALCS (TEMPORARY DITCH #1)
Project Information
Project Name: Erwin Rd Dunn, NC
Project#: 220124-01-004
Designed by: JA Date: 7/3/2023
Revised by: Date:
Checked by: Date:
Temporary Ditch#1
Drainage Area Total,AT= 4.96 Ac
25-year Runoff(Q25) C= 0.50
Tc= 5.00 min
125= 7.92 in/hr
Q25= 19.6 cfs

NORTH North American Green
5401 St. Wendel-Cynthiana Rd.
A1w1ER�` N L l N Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
>>>Temporary Ditch#1
Name Temporary Ditch#1
Discharge 19.6
Channel Slope 0.0127
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
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Mannings N Remarks
Depth Shear Stress Shear Stress Factor Pattern
DS75 Straight 19.6 cfs 4.06 ft/s 1.32 ft 0.032 1.6 Ibs/ft2 1.05 Ibs/ft2 1.53 STABLE D
Unvegetated
Underlying Straight 19.6 cfs 4.06 ft/s 1.32 ft 0.032 1.51 Ibs/ft2 0.55 Ibs/ft2 2.74 STABLE D
Substrate

EROSION CONTROL CALCS (TEMPORARY DITCH #2)
Project Information
Project Name: Erwin Rd Dunn, NC
Project#: 220124-01-004
Designed by: JA Date: 7/3/2023
Revised by: Date:
Checked by: Date:
Temporary Ditch#2
Drainage Area Total,AT= 0.88 Ac
25-year Runoff(Q25) C= 0.50
Tc= 5.00 min
125= 7.92 in/hr
Q25= 3.5 cfs

NORTH North American Green
5401 St. Wendel-Cynthiana Rd.
A1w1ER�` N L l N Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
>>>Temporary Ditch#2
Name Temporary Ditch#2
Discharge 3.5
Channel Slope 0.0154
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
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Mannings N Remarks
Depth Shear Stress Shear Stress Factor Pattern
DS75 Straight 3.5 cfs 2.68 ft/s 0.6 ft 0.035 1.6 Ibs/ft2 0.57 Ibs/ft2 2.79 STABLE D
Unvegetated
Underlying Straight 3.5 cfs 2.68 ft/s 0.6 ft 0.035 1.51 Ibs/ft2 0.34 Ibs/ft2 4.42 STABLE D
Substrate