SW6230902_Design Calculations_20240103

Bowman
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
NORTH CAROLINA
4006 Barrett Drive, Suite 104
Raleigh, NC 27609 • k�1'et+roZ,,�
PREPARED FOR: t�`j�� ` �QV
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Stout Land Development, LLC
1786 Metromedical Drive Matt Lowder, P
Fayetteville, NC 28304 NC License No. 24434
Ben Stout [phone]
[phone] [e-mail]
[e-mail]
JANUARY 2, 2024
Erwin Road Residential—Dunn, NC Wage

Bowman
NORTH CAROLINA
TABLE OF CONTENTS
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
Erwin Road Residential—Dunn, NC 2 I P a g e

Bowman
NORTH CAROLINA
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.
The offsite drainage to the SCM is 22,179 sf (0.51 ac). A portion of this is the residential lot that
resides between proposed lots 2 and 3 but not on the development parcel. The remainder of this
offsite drainage area is a portion of Erwin Road. The reason a portion of Erwin Road is being
collected is because the city is requiring curb and gutter along the entire frontage which will
require drainage pipes and structures. Unfortunately, there are no drainage ditches on the north
side of Erwin Road to discharge into without going several hundred feet west on Erwin Road. This
being the case, one of the drainage structures will need to be routed through the pond. To
minimize current and future impervious being sent to the SCM, a concrete flume is being
proposed at the southeast corner of the parcel along Erwin Road near lot 1, which bypasses the
SCM. In the calculations and design, this entire offsite drainage area is being considered
impervious.
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 ONSITE
1.90 acres (±82,814 SF)
Area of Land Disturbance 8.90 acres (± 387,684 SF)
TMDLs None
Watershed Protection Overlay None
Erwin Road Residential—Dunn, NC 3 I P a g e

Bowman
NORTH CAROLINA
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
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.
Erwin Road Residential—Dunn, NC 4 I P a g e

Bowman
NORTH CAROLINA
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:
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.
Erwin Road Residential—Dunn, NC 5 I P a g e

Bowman
NORTH CAROLINA
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.
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 14.9
• 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 5.38 acres (+234,269 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.
Erwin Road Residential—Dunn, NC Wage

Bowman
NORTH CAROLINA
Table 6:Post Development Area Summaries
Area Composite Time of
Basin ID [acres] Curve Concentration
Number (CN) (Tc) [min.]
SCM Post-Developed Area 5.38 74.3 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 3.56 53.6 10
• 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 0.265
2-yr 24-hr 1.968 1.271
10-yr 24-hr 11.08 10.13
100-yr 24-hr 33.28 32.26
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.
Erwin Road Residential—Dunn, NC 7

Bowman
NORTH CAROLINA
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 Wage

a Hydrologic Soil Group—Harnett County,North Carolina
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USDA 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(AOI) 1:24,000.
0 C/D
Soils • D Warning:Soil Map may not be valid at this scale.
Soil Rating Polygons
l 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
n 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
n B scale.
Transportation
Q B/D
r4-1. Rails Please rely on the bar scale on each map sheet for map
n C measurements.
ti Interstate Highways
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)
n 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
• • A distance and area.A projection that preserves area,such as the
1111 Aerial Photography Albers equal-area conic projection,should be used if more
• • A/D accurate calculations of distance or area are required.
^r B This product is generated from the USDA-NRCS certified data as
,. B/D of the version date(s)listed below.
• r C Soil Survey Area: Harnett County, North Carolina
Survey Area Data: Version 20,Sep 8,2022
• • C/D
Soil map units are labeled(as space allows)for map scales
• • D 1:50,000 or larger.
• w 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
O A/D imagery displayed on these maps.As a result,some minor
• B shifting of map unit boundaries may be evident.
• B/D
USDA 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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5/25/23,7:56 AM Precipitation Frequency Data Server
NOAA Atlas 14,Volume 2,Version 3
° Location name: Dunn, North Carolina, USA* '�� '��
p Latitude:35.3165°,Longitude: -78.6409° none
5 Elevation: 164 ft** 1
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**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 1 2 I 5 10 25 50 100 200 I 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) (1.06-1.28) (1.14-1.38) (1.21-1.47) (1.27-1.56) (1.35-1.66) (1.40-1.74)
15-min 0.872 1.03 1 1.20 1.34 1.49 I 1.60 1.70 1.80 1.91 2.00
(0.797-0.959) (0.945-1.14) (1.10-1.32) (1.22-1.46) (1.35-1.63) (1.45-1.75) (1.53-1.86) (1.61-1.96) I (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 I 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 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) I (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 I 3.64 4.11 4.59 5.09 5.78 6.36
(1.58-1.95) (1.92-2.36) (2.38-2.93) (2.76-3.41) (3.25-4.04) (3.66-4.57) (4.06-5.10) (4.48-5.65) (5.03-6.40) (5.49-7.06)
3-hr 1.86 2.24 2.81 3.30 3.95 4.51 5.09 5.72 6.59 7.35
(1.68-2.08) (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 5.68 6.54 7.46 8.46 9.90 11.2
(2.36-2.91) I (2.85-3.51) (3.58-4.42) (4.21-5.22) (5.06-6.30) (5.79-7.25) (6.54-8.25) (7.33-9.35) (8.44-10.9) (9.38-12.3)
24-hr 3.05 3.71 4.75 5.59 6.77 7.74 8.76 9.85 11.4 12.7
(2.78-3.36) (3.38-4.08) (4.31-5.22) (5.07-6.14) (6.11-7.44) (6.96-8.52) (7.86-9.64) (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 8.12 9.22 10.4 11.6 13.3 14.7
(3.50-4.14) (4.22-5.00) (5.32-6.30) (6.19-7.34) (7.39-8.82) (8.36-10.0) (9.36-11.3) (10.4-12.6) (11.9-14.6)I (13.0-16.1)
4-day 4.04 4.87 6.11 7.10 8.48 9.60 10.8 12.0 13.8 15.2
(3.73-4.37) (4.49-5.27) (5.62-6.61) (6.52-7.67) (7.75-9.17) (8.74-10.4) (9.76-11.7) (10.8-13.0) (12.3-15.0) (13.5-16.5)
7-day 4.67 5.61 6.96 8.03 9.52 10.7 11.9 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 1 7.79 I 8.89 10.4 11.6 12.8 I 14.0 15.7 17.1
(4.98-5.73) (5.95-6.86) (7.24-8.37) (8.24-9.54) (9.59-11.1) (10.6-12.4) (11.7-13.7) (12.8-15.1) (14.3-17.0) (15.5-18.5)
20-day 7.19 I 8.54 10.3 11.6 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) r(13.7-16.0) (15.0-17.5) (16.3-19.2) 1 (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 I 24.0
(8.35-9.64) (9.88-11.4) (11.6-13.4) (13.0-15.0) (14.7-17.1) (16.1-18.7) (17.4-20.3) (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) (12.6-14.3) (14.6-16.6) (16.1-18.4) (18.1-20.7) (19.6-22.5) (21.0-24.2) (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) i (19.0-21.6) (21.2-24.1) I (22.8-26.0) (24.4-27.9) I (25.9-29.7) (27.9-32.2) (29.4-34.0)
1 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
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5/25/23,7:56 AM Precipitation Frequency Data Server
PDS-based depth-duration-frequency (DDF) curves
Latitude: 35.3165°, Longitude: -78.6409°
Average recurrence
30 - interval
(years)
c 25 - — 1
L / — 2
a20 - — / — 6
c �� — 10
G 15 - . — 25
y — 50
a 10 - — 100
i ,PIM — 200
500
5 - �-_ — 1000
0
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." ." - L L r r t ro ro ro ro ro ro ro ro ro
i p A ns th A ,r -O -O-O -o -9 7 7 7 17
V1 O m tD Duration N N N O N m v O
30 —
25 —
'� ■di Duration
L
a 20 —
a, — 5-nun — 2-day
v
c 1111111 — t0-mn — 3-day
.o▪ 15 —_� J_��= - 15-rnrn — 4-day
ro �--_
a — 30 min — 7-day
10 - -- _ -____-- — 60-nun — 10-day
a _ _ �� — 2-hr — 20-day
5 —� — 3-hr — 30-day
_ — 6-hr — 45-day
0 J -- - — 12-hr — 60-day
1 I I i - I i I — 24-hr
1 2 5 10 25 50 100 200 500 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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5/25/23,7:56 AM Precipitation Frequency Data Server
inston-Salem
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•
Raleigh
• Greenville
North •
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Charlotte
Fayetteville
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100km WI lmi nQtor
umb 60mi
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National Water Center
1325 East West Highway
Silver Spring,MD 20910
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Disclaimer
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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* '�� '��
p Latitude:35.3165°,Longitude: -78.6409° none
% Elevation: 164 ft** 1
'o, ,Es o, *source:ESRI Maps w�M^M ilia)
**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
1 2 5 10 25 50 100 - 200 500 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) (5.64-6.78) (6.52-7.84) (7.22-8.69) (8.02-9.67) (8.62-10.4) (9.16-11.1) (9.65-11.8) (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) (4.51-5.42) (5.22-6.27) (5.78-6.95) i (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 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)J (2.66-3.21) I (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) (1.19-1.47) (1.38-1.70) (1.63-2.02) (1.83-2.28) (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) (1.34-1.67) (1.50-1.89) (1.67-2.12) (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) (1.01-1.28) (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 ' 0.232 0.268 0.297
(0.068-0.081) (0.082-0.098) (0.104-0.124) (0.122-0.146) (0.146-0.176)1(0.166-0.200) (0.186-0.227)1(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 I 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)1(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)1(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) (0.013-0.014) (0.014-0.016) (0.015-0.018) (0.016-0.019) (0.017-0.020) (0.019-0.022) (0.020-0.023)1
1 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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5/25/23,7:57 AM Precipitation Frequency Data Server
PDS-based intensity-duration-frequency (IDF) curves
Latitude: 35.3165°, Longitude: -78.6409°
Average recurrence
101 . . interval
(years)
�\ : �
\�� — 1
72
10° - \\ — 5
cuci \ — 10
— 25
`o — 50
l0-1 - \ — 100
a — 200
d — 500
o_
_- � — 1000
10-2 -
r . . 1 I . . I 1 I I 1 1 1 1 I I 1
c_ c_ c_ C
C_ L >, >.rt >, a, > >, t,>.
E E E E E ri A kb N v v vv 7 -o v v 77
i
.�-� m I".
14'$ Duration NiNio N m v V)
101 - — -
L_
L
C
Duration
10°
c — 5-nun — 2-day
a
— 10-min — 3-day
c 15-nin — 4-day
0
— 30-nin — 7-day
;° 10-1 — 60-min — 10-day
a
w — 2-hr — 20-day
o` — 3-hr — 30-day
— 6fir — 45-day
10-2 — 12-hr — 60-day
I I i 1 I i i — 24fir
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval (years)
NOAA Atlas 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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5/25/23,7:57 AM Precipitation Frequency Data Server
inston-Salem
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•
Raleigh
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Charlotte
Fayetteville
111 Jacksor
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umb 60mi
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GRAPHIC SCALE DATE DESCRIPTION
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( INFEET) J0B No. 220124-01-004
1 inch= 50 ft.
DATE , 2023
FILE No.
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Cad file name:V:\220124-Ben Stout Construction\220124-01-004(ENG)-Erwin Rood,Dunn,NC\Engineering\Engineering Plans\Canstmctioe D000ments\220124-01-004-DDO.dwg

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GRAPHIC SCALE DATE DESCRIPTION
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C`7 SCALE H.
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1 inch= 50 ft.
DATE Dec 11, 2023
FILE No.
SHEET
Cad file name:V:\220124-Ben Stout Construction\220124-01-004(ENG)-Erwin Rood,Dunn,NC\Engineering\Engineering Plons\Construction Documents\220124-01-004-0DP.dwg

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_/_/23
GRAPHIC SCALE DATE DESCRIPTION
ML RG XXX
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- J DESIGN H 50RAWN CHKD
9II ll
SCALE V.
IMI
( INFEET) JOB No. 220124-01-006
1 inch= 50 ft.
DATE Dec 11, 2023
FILE No.
SHEET
Cad file name:N\220124-Ben Stout Construction\220124-01-004(ENG)-Erwin Rood,Dunn,NC\Engineering\Engineering Plans\Construction Documents\220124-01-004-DDP.dwg

1LV I•N'1IJ11JYN
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July1 0, 2023 This map is for general reference only.The US Fish and Wildlife
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 n Other
Estuarine and Marine Wetland I Freshwater Pond n Riverine
I
National Wetlands Inventory(NWI)
This page was produced by the NWI mapper

Bowman
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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 I P a g e

Bowman North Carolina, Ltd.
Curve Number Calculation (CN)
Pre-Developed Conditions(Overall Site)
Drainage Area(acres): 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 52 5.9
Open Space-Good A 0.35 55 2.2
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); 5.38
Existing Soil Groups:
Soil Group Map Symbol Soil Description Acres Percent of DA
A/D Bb Bibb soils 0.74 14%
A NoB Norfolk loamy sand 3.66 68%
A NoC Norfolk loamy sand 0.98 18%
Proposed Land Uses:
Land Use Description Existing Soil Group Acres Curve# Weighted CN
Impervious A 2.41 98 43.9
Open Space-Good A 2.97 55 30.4
Cumulative Curve#= 74.3

Bowman North Carolina, Ltd.
Curve Number Calculation (CN)
Post-Developed Bypass Conditions(Wet Pond)
Drainage Area(acres): 3.56
Existing Soil Groups:
Soil Group Map Symbol Soil Description Acres Percent of DA
A/D Bb Bibb soils 0.45 13%
A NoB Norfolk loamy sand 1.69 47%
A NoC Norfolk loamy sand 1.42 40%
Proposed Land Uses:
Land Use Description Existing Soil Group Acres Curve# Weighted CN
Open Space-Good A 1.08 55 16.7
Wooded -Good A 2.48 53 36.9
Cumulative Curve#= 53.6

IMPERVIOUS SUMMARY TABLE
ON-SITE AREA = 393,826 SF (9.04 ACRES)
LOTS 49,410 SF 1.13 ACRE(S) 12.55% OF AREA
PAVEMENT 24,984 SF 0.58 ACRE(S) 6.34% OF AREA
SIDEWALK 8,420 SF 0.19 ACRE(S) 2.14% OF AREA
EXISTING IMPERVIOUS AREA 0 SF 0 ACRE(S) 0% OF AREA
TOTAL IMPERVIOUS AREA 82,814 SF 1.90 ACRE(S) 21.03% OF AREA
GREEN/OPEN SPACE 311,012 SF 7.14 ACRE(S) 78.97% OF AREA
INCREASE IN IMPERVIOUS AREA 82,814 SF 1.90 ACRE(S) 21.03% OF AREA

TIME OF CONCENTRATION
Existing Conditions
SCS Methodology
OPEN CHANNEL
SHALLOW CONC FLOW: FLOW: TOTAL
SHEET FLOW: SEGMENT 1 SEGMENT 1
Manning's Equation:
Tc=(0.007(nL)^0.8)/(P2^0.5)(s^0.4) 2-year/24-hr Tc=L/60'V V=1.49Rv'aS'n/n
Basin Comments Length Elevt Elev2 Slope Rainfall Depth Manning's T, Length Elev2 Elev3 Slope Condition Vavg Teo Cross Sectional Wetted Perimeter Hydraulic Radius Length Elev3 Elev4 Slope Manning's V Tv TcTOTeL Tc(minimum) Tlag Basin
(ft) (fl/ft) TP-40(in) "n" (min) (fl) (fUB) TR-55 Fig.3-1 (ft/sec) (min) Flow Area(fl^2) (ft) (ft) (ft) (ft/ft) "n" (fps) ((nin) (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
7/720234:00 PM G:WYORO5rojects\TlmeConapunn Erwin Rd.Ss

Proposed Wet Pond
Project Information
Project Name: Erwin Road Residential
Project#:
Designed by: RG Date: 8/18/2023
Revised by: RG Date: 12/18/2023
Checked by: Date:
Site Information
Sub Area Location: Drainage To Proposed Wet Pond
Drainage Area (DA) = 5.38 Acres 234,269 sf
Impervious Area (IA) = 2.41 Acres 104,993 sf
Percent Impervious (I) = % 44.82 °A)
Required Surface Area
Permament Pool Depth: 3.92 ft Non-Coastal County
SA/DA= 1.39
Min Req'd Surface Area = 3,258 sf(at Permanent Pool)
Required WQv Storage Volume
Design Storm = 1 inch Non-Coastal County
Determine Rv Value = 0.05 + .009 (I) = 0.453 in/in
Storage Volume Required = 8,854 cf(above Permanent Pool)
Elevations
Top of Pond Elevation = 174.60 ft
Temporary Pool Elevation = 172.20 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 = 4,370 sf
Volume of Temporary Storage = 17,138 cf
Is Permenant Pool Surface Area Sufficient(yes/no)? Yes ( 4370 > 3258 ) sf
Volume of Storage for Design Storm = 17,138 Yes ( 17138 > 8854 ) 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
Revised by: RG Date: 1/2/2024
Water Quality Orifice
Incremental Determination of Water Quality Volume Drawdown Time
I
Zone 3 Q3=0.0437 CD*D2(Z-D/24-Ei)^(112)
Jr
Zone 2 Z 0 Q2=0.372 CD*D*(Z-Ei)^)3/2)
I
Zone 1 Q1=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 172.2
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
171.00 7960 3,077 0.40 3.00 0.041 1,258
172.00 9520 8,740 1.00 3.00 0.060 2,420
172.20 9780 1,930 0.20 3.00 0.063 508
Total -- 17,138 -- -- -- 6,096
Drawdown Time=Incremental Volume/Q/60sec/min
Summary
Total Volume= 17,138 cf
Total Time= 6,096 min
Total Time= 4.23 days Between 2&5
1/2/2024 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: RG Date: 1/2/2024
Checked by: Date:
Site Information
Sub Area Location: Drainage to Proposed Pond
Drainage Area (DA) = 5.38 Acres
Impervious Area (IA) = 2.41 Acres
Percent Impervious (I) = 44.82 % (Drainage Area)
Orifice Sizing
Orifice Size = 1.30 in (Diameter)
Drawdown Time = 4.23 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 lbs
Factor of Safety 1.20
WT Req'd of Anti-Flotation Device: 11,981 lbs
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
0.9 171.0 7960 3077 6468
1.9 172.0 9520 8740 15208
2.1 172.2 9780 1930 17138(WQV)
2.9 173.0 10835 8246 25384
3.9 174.0 12210 11523 36907
4.5 174.6 13060 7581 44488
iSTORMWATER 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: 35.314454N, -78.6398901N
POND DESIGN SUMMARY
DRAINAGE AREA TO POND: 5.38 ACRES
SITE IMPERVIOUS AREA TO POND: 1.90 ACRES
OFF-SITE DESIGN IMPERVIOUS AREA TO POND: 0.51 ACRES
TOTAL DESIGN IMPERVIOUS AREA TO POND: 2.41 ACRES
PRE-DEVELOPED POST-DEVELOPED POST DEVELOPED POST DEVELOPED POST DEVELOPED
TO POND TO POND THROUGH POND BYPASS COMBINED
DRAINAGE AREA: 8.74 AC 5.38 AC 3.56 AC
CURVE NUMBER: 53.3 74.3 53.6
TIME OF CONCENTRATION: 14.9 MIN 5 MIN 10 MIN
1.0" STORM EVENT: 0.055 CFS 0.005 CFS
1-YEAR STORM EVENT: 0.396 CFS 8.720 CFS 0.060 CFS 0.205 CFS 0.265 CFS
2-YEAR STORM EVENT: 1.968 CFS 12.88 CFS 0.267 CFS 1.004 CFS 1.271 CFS
10-YEAR STORM EVENT: 11.08 CFS 26.01 CFS 4.735 CFS 5.399 CFS 10.13 CFS
�100-YEAR STORM EVENT: 33.28 CFS 50.22 CFS 16.38 CFS 15.88 CFS 32.26 CFS j

1
`�\\ \ \S$B�RIe`RA� j6J '
— \ �AY iGEiR \ \
RIP-RAP APRON## \ y \\ Toe OE#18AN RIP-RAT2---
REFER TO DETAIL ON / \\\ •`-\ \ �V=1�4,6REFER ON
SHEET C6.1 fOR / \\\ \ \ 5 1EN(NCESHEETCONSTRUCTION // �� - \�\ �� \\ ——— ——-� CONSTREQUIREMENTS / // // 1 ; \\\ \\\ �� EQUI
/ // // / / 1 i�A y \�9' 1\ TROL
iiir . \STR T REN REFER TO
5
_17 / // ��1 / /�,// ::.:..,••�\\\ 7 3,�\ \� ��QILS 1FH�,S�HEET
INLET PIPE WITH I T-4 • ire..- � � 2:..\.�- \a•` \.%ii; \sue s /,—
RIP-RAP APRON �� A�,y,:.zis{yy-9? \ '6 _ \ ---
RIP-RAP ri s.� \ 6 1 \ _ _ Or
---4„.*Ac .... A\--,_. ... ...--- , . 0 i
it. ,..._ \ .:0 . " . ,
,, . , ,!/ e:„„.irsiif ---
Al
_ v__ . ..___ ......,..
_ ......
_, \, ...„ _ ,c,'Iii, si. .$,\,,.. ,
tio.,„„,.._ \ ‘ , .0, , , `,,,,--\
,t. i, ,,,
_ _ _ .,. -
/ N
�/ %� L.:�j\ °':: °: N. o,/ / i/\ 1Re OUTLET PIPE 1
. REFER p \ \ i
____ .
,,,,,
. i
� \17. 173 �� � ..- o°j/ /' � GRADING PLAN \ t \% N�
•
1 ., . S0� AREA AdpVE \ t \1
-al .. . `� NORMAL POOL \
-` 411101rA �� I ELE TION ' 1 ! V
LITORAL SHELF AREA `m,,, 1 v 1
` ? (SHALLOW WATER)=730 SF, � LITORA.SHELF AREA : ro
(TEMPOR•:Y INUNDATION)=796 , " \ I\
REFER TO DETAIL ON THIS ; 1 A
MAIN POND SF, REFER DETAIL ON THIS
\SHEET FOR PLANTINGS N SHEET FOR P •NTINGS v 1 1 til; 1\ i1 \ 1 1 1
\ I I I t•1
/' 2 , \ ' I
PLAN VIEW
GRAPHIC SCALE
30 0 15 30 60 120
( IN FEET )
1 inch = 30 ft.

5'
EMBANKMENT WIDTH
6'TOPSOIL FOR AU.
AREAS ABOVE THE TRASH RACK
NORMAL POND ELEVATION REFER TO DETAIL
THIS SHEET
Q
5 , >VXV////
8'HDPE WITH WATER TIGHT SEAL
IPE TO BE BEDDED TOP OF EMBANKMENT ELEVA110N=174.6
ER DIRECTION OF 6'TOPSOIL ABOVENGINEER 3 6"CLAY LINER REFER TO DETAIL 100 YEAR STORM ELEVATION=174.52
6'CLAY SOIL ON LITTORAL SHELF INFOR
CREMENTAL
1 LINER ON INSIDE 3 HEI
FACE OF 10 YEAR STORM ELEVATION=17294
EMBANKMENT - 1
6
CON PRECAST IS a
6FT LITTORAL 1 f CONCRETE RISER 2 YEAR STORM ELEVATION=172.33
SHELF _ (INSTALL STEPS
AS NECESSARY) 1 YEAR STORM ELEVATION=171.98
NV.1699 r 1.0-IRON STORM ELEVATION=170.17
�� fJ 0 NORMAL POND ELEVATION=170.1
'' . y L- PVC ELBOW
3'MIN !. ,.:•.• SEE DETAIL
\1 ELEV=167.9 2 NOTE: PUMPS SHALL BE USED TO DRAIN
- 1 THE POND WHEN NECESSARY. REFER TO DETAIL
1 L. -- w _ THIS SHEET FOR DEWATERING REQUIREMENTS.
-°
4'NIN. I ASTM C-923 SEAL —
KEY BETWEEN BARREL&RISER.
CUTOFF TRENCH RISER BASE TO BE FILLED BOTTOM OF POND(TOP OF SEDIMENT STORAGE)=164.6
PATH CONC.TO INVERT OF )
APPROXIMATE SIZE BARREL CONCRETE SHALL BE PLACED IN RISER AFTER
EXCAVATE AND BACKFILL 8'BASE.PRONDEG ANGLE(A7T.REQUIRED) RISER AND ANGLES ARE SECURED —I N`I� (BOTTOM OF SEDIMENT STORAGE)=163.6
IWTH COMPACTEDTO BASE AND RISER. ..1.....4.12....
-- -- -- -- -- -
STRUCTURAL FILL AS 2-A307 'J'HOOKS 3/4"DIA.X 12'LONG FROM ANGLE TO BASE a` ./
ANGLE TO BE FIELD COATED NTH ZINC RICH PAINT AFTER - -- -- -- -- /
DIRECTED BY GEOTECHNICAL CONSTRUCTION.'J'HOOKS TO BE PLACED UNDER LONER REINFORCING
ENGINEER STEEL 6'CLAY SOIL
e'xrx1.5 CONC.BASE REINFORCE WITH/4 BARS AT 12'O.C.TOP UNER
AND BOTTOM OF EACH DIRECTION PROVIDE 3'MIN.CLEARANCE MAIN P00L
_ 62'-18'HDPE 0 0.655 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 BERM 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
EXISTING GRADE=175.Of ON LITTORAL SHELF -/�1/��'''' ' SEDIMENT STORAGEOP THIS SHEET FOR DEWATERING REQUIREMENTS.THE FOREBAY MEN NECESSARY. REFER DETAIL ,
6FT LITTORAL 6:1 / -I '��,, FOREBELEV BOTTOM 6 3 //�i
SHELF / I ''� NORMAL POND ELEVATION //
2
-- /A., -I ,1� BOTTOM LITTORAL SHELF ELEV.
tl ASS B RIP-RAP OVER FILTER
_ FABRIC MIN.4'FOREBAY
- WEIR AT ELEV=169.0
-4111*4k11#'-" lirr,'
- 711 .
6"TOPSOIL FOIL ALL
FOREBAY ENTRANCE SHALL BE AREAS ABOVE DIE
DEEPER THAN FOREBAY EXIT NORMAL POND ELEVATION
L BOTTOM OF SEDIMENT
STORAGE/EXIT BOTTOM OF SEDIMENT
ELEV=167.1 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=172.8
INTERMEDIATE WEIR INII ■
ELEV=172.2
12"MIN. EXTEND 4"
PVC
THROUGH hiik.
RISER
STRUCTURE
4"x4"PVC TEE
PERM.POND ELEV.170.1 7fINSTALL 4"PVC SCREW
CAP AT END OF TE
4"OPENING CORED INTO AND DRILL 1.3'DIA.
SIDE OF PRECAST HOLE INTO PVC CAPE
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 8t7R` (REMOVABLE TRASH RACK)
/1?B
Spop.
MFDIq
KFIR`1722
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 8.720 2 718 17,503 BMP Post-Developed
3 Reservoir 0.060 2 1444 14,146 2 171.98 15,058 Post Through Pond
4 SCS Runoff 0.205 2 728 2,323 Post Developed-Pond Bypass
6 SCS Runoff 0.055 2 360 462 BMP Post-Developed
7 Reservoir 0.005 2 366 357 6 170.17 441 1.0-in Storm Thru Pond
Wet Pond-Dunn Erwin.gpw Return Period: 1 Year Tuesday, 01 /2/2024

2
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
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
■
I
0.25 0.25
0.20 0.20
0.15 0.15
0.10 0.10
111.111111
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 Tuesday,01 /2/2024
Hyd. No. 2
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 8.720 cfs
Storm frequency = 1 yrs Time to peak = 718 min
Time interval = 2 min Hyd. volume = 17,503 cuft
Drainage area = 5.380 ac Curve number = 74.3
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)
10.00 - 10.00
8.00 8.00
6.00 I 6.00
4.00 - 4.00
2.00 I 2.00
I .
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 Tuesday,01 /2/2024
Hyd. No. 3
Post Through Pond
Hydrograph type = Reservoir Peak discharge = 0.060 cfs
Storm frequency = 1 yrs Time to peak = 1444 min
Time interval = 2 min Hyd. volume = 14,146 cuft
Inflow hyd. No. = 2 - BMP Post-Developed Max. Elevation = 171.98 ft
Reservoir name = BMP Pond Max. Storage = 15,058 cuft
Storage Indication method used.
Post Through Pond
Q (cfs) Hyd. No. 3 -- 1 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 —. Ilt - 0.00
0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Time (min)
Hyd No. 3 Hyd No. 2 111111111 Total storage used = 15,058 cuft

Pond Report 5
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
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(cuft) Total storage(cuft)
0.00 170.10 6,140 0 0
0.50 170.60 7,425 3,391 3,391
0.90 171.00 7,960 3,077 6,468
1.90 172.00 9,520 8,740 15,208
2.10 172.20 9,780 1,930 17,138
2.90 173.00 10,835 8,246 25,384
3.90 174.00 12,210 11,522 36,907
4.50 174.60 13,060 7,581 44,488
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) = 1.30 14.70 0.00 0.00
Span(in) = 18.00 1.30 0.00 0.00 Crest El.(ft) = 172.20 172.80 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
4.00 ....0"....°7 174.10
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 Tuesday,01 /2/2024
Hyd. No. 4
Post Developed - Pond Bypass
Hydrograph type = SCS Runoff Peak discharge = 0.205 cfs
Storm frequency = 1 yrs Time to peak = 728 min
Time interval = 2 min Hyd. volume = 2,323 cuft
Drainage area = 3.560 ac Curve number = 53.6
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 1 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 Tuesday,01 /2/2024
Hyd. No. 6
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 0.055 cfs
Storm frequency = 1 yrs Time to peak = 360 min
Time interval = 2 min Hyd. volume = 462 cuft
Drainage area = 5.380 ac Curve number = 74.3
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 1 - 0.06
0.05 0.05
0.04 0.04
0.03 0.03
0.02 0.02
0.01 0.01
0.00 — I ,— 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 Tuesday,01 /2/2024
Hyd. No. 7
1.0-in Storm Thru Pond
Hydrograph type = Reservoir Peak discharge = 0.005 cfs
Storm frequency = 1 yrs Time to peak = 366 min
Time interval = 2 min Hyd. volume = 357 cuft
Inflow hyd. No. = 6 - BMP Post-Developed Max. Elevation = 170.17 ft
Reservoir name = BMP Pond Max. Storage = 441 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
— Z
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 2880
Time (min)
Hyd No. 7 Hyd No. 6 111111111 Total storage used =441 cuft

Pond Report 9
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
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(cuft) Total storage(cuft)
0.00 170.10 6,140 0 0
0.50 170.60 7,425 3,391 3,391
0.90 171.00 7,960 3,077 6,468
1.90 172.00 9,520 8,740 15,208
2.10 172.20 9,780 1,930 17,138
2.90 173.00 10,835 8,246 25,384
3.90 174.00 12,210 11,522 36,907
4.50 174.60 13,060 7,581 44,488
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) = 1.30 14.70 0.00 0.00
Span(in) = 18.00 1.30 0.00 0.00 Crest El.(ft) = 172.20 172.80 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
4.00 ....0"....°7 174.10
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 12.88 2 718 25,750 BMP Post-Developed
3 Reservoir 0.267 2 1014 21,068 2 172.33 18,441 Post Through Pond
4 SCS Runoff 1.004 2 724 4,906 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 Tuesday, 01 /2/2024

11
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
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 Tuesday,01 /2/2024
Hyd. No. 2
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 12.88 cfs
Storm frequency = 2 yrs Time to peak = 718 min
Time interval = 2 min Hyd. volume = 25,750 cuft
Drainage area = 5.380 ac Curve number = 74.3
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)
14.00 14.00
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 Tuesday,01 /2/2024
Hyd. No. 3
Post Through Pond
Hydrograph type = Reservoir Peak discharge = 0.267 cfs
Storm frequency = 2 yrs Time to peak = 1014 min
Time interval = 2 min Hyd. volume = 21,068 cuft
Inflow hyd. No. = 2 - BMP Post-Developed Max. Elevation = 172.33 ft
Reservoir name = BMP Pond Max. Storage = 18,441 cuft
Storage Indication method used.
Post Through Pond
Q (cfs) Hyd. No. 3 -- 2 Year Q (cfs)
14.00 - 14.00
12.00 I 12.00
10.00 10.00
8.00 8.00
6.00 6.00
4.00 4.00
2.00 2.00
J16.-""'
0.00 - 0.00
0 600 1200 1800 2400 3000 3600 4200 4800 5400 6000
Time (min)
Hyd No. 3 Hyd No. 2 I Total storage used = 18,441 cuft

14
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
Hyd. No. 4
Post Developed - Pond Bypass
Hydrograph type = SCS Runoff Peak discharge = 1.004 cfs
Storm frequency = 2 yrs Time to peak = 724 min
Time interval = 2 min Hyd. volume = 4,906 cuft
Drainage area = 3.560 ac Curve number = 53.6
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 - I , 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 Tuesday,01 /2/2024
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 = 5.380 ac Curve number = 74.3
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 Tuesday,01 /2/2024
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 I I 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 26.01 2 716 52,563 BMP Post-Developed
3 Reservoir 4.735 2 726 47,791 2 172.94 24,719 Post Through Pond
4 SCS Runoff 5.399 2 722 15,854 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 Tuesday, 01 /2/2024

18
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
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 - i 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 Tuesday,01 /2/2024
Hyd. No. 2
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 26.01 cfs
Storm frequency = 10 yrs Time to peak = 716 min
Time interval = 2 min Hyd. volume = 52,563 cuft
Drainage area = 5.380 ac Curve number = 74.3
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
J '
0.00 — 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440
Hyd No. 2 Time (min)

20
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
Hyd. No. 3
Post Through Pond
Hydrograph type = Reservoir Peak discharge = 4.735 cfs
Storm frequency = 10 yrs Time to peak = 726 min
Time interval = 2 min Hyd. volume = 47,791 cuft
Inflow hyd. No. = 2 - BMP Post-Developed Max. Elevation = 172.94 ft
Reservoir name = BMP Pond Max. Storage = 24,719 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 - J� � - •- 0.00
0 360 720 1080 1440 1800 2160 2520 2880 3240 3600 3960 4320
Time (min)
Hyd No. 3 Hyd No. 2 II II Total storage used = 24,719 cuft

21
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
Hyd. No. 4
Post Developed - Pond Bypass
Hydrograph type = SCS Runoff Peak discharge = 5.399 cfs
Storm frequency = 10 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 15,854 cuft
Drainage area = 3.560 ac Curve number = 53.6
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)
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 Tuesday,01 /2/2024
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 = 5.380 ac Curve number = 74.3
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 Tuesday,01 /2/2024
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 I I 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 50.22 2 716 103,393 BMP Post-Developed
3 Reservoir 16.38 2 724 98,548 2 174.52 43,526 Post Through Pond
4 SCS Runoff 15.88 2 722 41,973 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 Tuesday, 01 /2/2024

25
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
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
I
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 Tuesday,01 /2/2024
Hyd. No. 2
BMP Post-Developed
Hydrograph type = SCS Runoff Peak discharge = 50.22 cfs
Storm frequency = 100 yrs Time to peak = 716 min
Time interval = 2 min Hyd. volume = 103,393 cuft
Drainage area = 5.380 ac Curve number = 74.3
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)
60.00 60.00
50.00 50.00
40.00 40.00
_ 1
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 Tuesday,01 /2/2024
Hyd. No. 3
Post Through Pond
Hydrograph type = Reservoir Peak discharge = 16.38 cfs
Storm frequency = 100 yrs Time to peak = 724 min
Time interval = 2 min Hyd. volume = 98,548 cuft
Inflow hyd. No. = 2 - BMP Post-Developed Max. Elevation = 174.52 ft
Reservoir name = BMP Pond Max. Storage = 43,526 cuft
Storage Indication method used.
Post Through Pond
Q (cfs) Hyd. No. 3-- 100 Year Q (cfs)
60.00 60.00
50.00 50.00
40.00 40.00
30.00 30.00
20.00 20.00
10.00 10.00
0.00IIII 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
Hyd No. 3 Hyd No. 2 111111111 Total storage used =43,526 cuft

28
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk®Civil 3D®by Autodesk, Inc.v2022 Tuesday,01 /2/2024
Hyd. No. 4
Post Developed - Pond Bypass
Hydrograph type = SCS Runoff Peak discharge = 15.88 cfs
Storm frequency = 100 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 41,973 cuft
Drainage area = 3.560 ac Curve number = 53.6
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 Tuesday,01 /2/2024
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 = 5.380 ac Curve number = 74.3
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 Tuesday,01 /2/2024
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 I I Total storage used = 0 cuft

NORTH North American Green
AMERICAN 5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
>>>Grass Channel#1
Name Grass Channel#1
Discharge 13.4
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 Good 65-79%
Soil Type Sandy Loam(GM)
Unreinforced Vegetation
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Mannings N Remarks
Depth Shear Stress Shear Stress Factor Pattern
Unreinforced Straight 13.4 cfs 2.15 ft/s 1.17 ft 0.061 4 Ibs/ft2 0.81 Ibs/ft2 4.94 STABLE --
Vegetation
Underlying Straight 13.4 cfs 2.15 ft/s 1.17 ft 0.061 4 Ibs/ft2 0.53 Ibs/ft2 7.62 STABLE --
Substrate
DS75
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Remarks
Depth Mannings N Shear Stress Shear Stress Factor Pattern
DS75 Straight 13.4 cfs 3.28 ft/s 0.86 ft 0.034 1.6 Ibs/ft2 0.6 lbs/ft2 2.67 STABLE D
Unvegetated
Underlying Straight 13.4 cfs 3.28 ft/s 0.86 ft 0.034 1.51 lbs/ft2 0.41 Ibs/ft2 3.67 STABLE D
Substrate

741 NORTH North American Green
AMERICAN 5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
>>>Grass Channel#2
Name Grass Channel#2
Discharge 3.11
Channel Slope 0.005
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)
C125
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Remarks
Depth Mannings N Shear Stress Shear Stress Factor Pattern
C125 Straight 3.11 cfs 1.71 ft/s 0.46 ft 0.031 2.3 lbs/ft2 0.14 lbs/ft2 15.92 STABLE D
Unvegetated
Underlying Straight 3.11 cfs 1.71 ft/s 0.46 ft 0.031 2.18 lbs/ft2 0.11 Ibs/ft2 19.47 STABLE D
Substrate
Unreinforced Vegetation
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Mannings N Remarks
Depth Shear Stress Shear Stress Factor Pattern
Unreinforced Straight 3.11 cfs 0.79 ft/s 0.84 ft 0.093 4 lbs/ft2 0.26 lbs/ft2 15.25 STABLE --
Vegetation
Underlying Straight 3.11 cfs 0.79 ft/s 0.84 ft 0.093 4 lbs/ft2 0.18 lbs/ft2 22.02 STABLE --
Substrate

NORTH North American Green
AMERICAN 5401 St. Wendel-Cynthiana Rd.
Poseyville, Indiana 47633
GREEN Tel. [phone]
>Fax [phone]
www.nagreen.com
ECMDS v7.0
CHANNEL ANALYSIS
> > > Grass Channel #3
Name Grass Channel #3
Discharge 8.68
Channel Slope 0.0316
Channel Bottom Width 1
Left Side Slope 2
Right Side Slope 2
Low Flow Liner
Retardence Class C 6-12 in
Vegetation Type Sod Former
Vegetation Density Good 65-79%
Soil Type Sandy Loam (GM)
Unreinforced Vegetation
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Mannings N Remarks
Depth Shear Stress Shear Stress Factor Pattern
Unreinforced Straight 8.68 cfs 3.51 ft/s 0.89 ft 0.047 4 lbs/ft2 1.76 lbs/ft2 2.28 STABLE --
Vegetation
Underlying Straight 8.68 cfs 3.51 ft/s 0.89 ft 0.047 4 lbs/ft2 0.98 lbs/ft2 4.08 STABLE --
Substrate
DS75
Normal Permissible Calculated Safety Staple
Phase Reach Discharge Velocity Mannings N Remarks
Depth Shear Stress Shear Stress Factor Pattern
DS75 Straight 8.68 cfs 4.83 ft/s 0.73 ft 0.031 1.6 lbs/ft2 1.44 Ibs/ft2 1.11 STABLE D
Unvegetated
Underlying Straight 8.68 cfs 4.83 ft/s 0.73 ft 0.031 1.51 lbs/ft2 0.83 lbs/ft2 1.82 STABLE D
Substrate

Bowman North Carolina,Ltd.
Erwin Road Residential Dunn,NC-Storm Drain"C"calculations
Rational Runoff Coefficient"C"
Grass Channel#1
Drainage Area(acres): 4.29
Proposed Land Uses:
Land Use Description Acres %Site Runoff"C" "C"
Roofs 0.86 20% 0.95 0.19
Asphalt/Concrete Pavement 0.00 0% 0.95 0.00
Lawn 1.95 45% 0.3 0.14
Wooded 1.49 35% 0.2 0.07
Total Area= 4.29 Cumulative"C"= 0.39
i i o= 7.92
Qi o= 13.43
Grass Channel#2
Drainage Area(acres): 0.82
Proposed Land Uses:
Land Use Description Acres %Site Runoff"C" "C"
Roofs 0.23 28% 0.95 0.26
Asphalt/Concrete Pavement 0.00 0% 0.95 0.00
Lawn 0.59 72% 0.3 0.22
Wooded 0.00 0% 0.2 0.00
Total Area= 0.82 Cumulative"C"= 0.48
iio= 7.92
Qio= 3.11
Grass Channel#3
Drainage Area(acres): 1.86
Proposed Land Uses:
Land Use Description Acres %Site Runoff"C"
Roofs 0.83 44% 0.95 0.42
Asphalt/Concrete Pavement 0.00 0% 0.95 0.00
Lawn 1.03 56% 0.3 0.17
Wooded 0.00 0% 0.2 0.00
Total Area= 1.86 Cumulative"C"= 0.59
i i o= 7.92
Qi o= 8.68

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-108 0.18 0.88 1.25 0.00 1.25 0.021 0.034 23 1.16 4.90 0.09 CB-106
CB-106 0.22 0.46 0.80 0.09 0.90 0.017 0.02 26 0.81 6.26 0.08 CB-105
-
CB-105 1.49 0.44 5.19 0.08 5.27 0.013 0.022 6.94 0.76 12.06 4.51 CB-104
-
CB-104 0.19 0.82 1.25 4.51 5.77 0.0102 0.022 6.94 0.87 13.05 4.90 CB-103
-
CB-103 0.63 0.53 2.64 4.90 7.54 0.0102 0.022 6.94 1.03 14.44 6.52 CB-102
-
CB-102 0.13 0.82 0.84 6.52 7.36 0.015 0.022 6.94 0.90 13.31 6.47 CB-101
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
CB-101 0.15 0.62 0.74 9.77 10.50 0.015 0.022 6.94 1.12 15.20 9.38

Bowman
NORTH C AROL 1 N A
APPENDIX C
Storm Drainage System Calculations
100-System
Erwin Road Residential—Dunn, NC 10

C
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PRELIMINARY
DO NOT
USE FOR
CONSTRUCTION
PLAN STATUS
_/_/23
DATE DESCRIPTION
ML RG XXX
DESIGN DRAWN CHKD
SCALE H:1 50'
V:
GRAPHIC SCALEJOB No. 220124-01-006
so xs so PW DATE Dec 11, 2023
FILE No.
( IN FEET)
1 inch= 50 ft. SHEET ####
Cad file name:N\220124-Ben Stout Construction\220124-01-004(ENG)-Erwin Rood,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
Drainage 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 Cumulative"C"= 0.62
i i o= 7.92
Qio= 0.75
Catch Basin #102
Drainage 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 Cumulative"C"= 0.82
i i o= 7.92
Qio= 0.86
Catch Basin #103
Drainage 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
Qio= 2.62
Catch Basin #104
Drainage 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 Cumulative"C"= 0.82
i i o= 7.92
Qio= 1.25

Catch Basin #105
Drainage 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
i 1 o= 7.92
Qio= 5.26
Catch Basin #106
Drainage Area(acres): 0.215
Proposed Land Uses:
Land Use Description Acres %Site Runoff"C"
Roofs 0.03 13% 0.95 0.13
Asphalt/Concrete Pavement 0.03 12% 0.95 0.12
Lawn 0.15 70% 0.3 0.21
Wooded 0.01 5% 0.2 0.01
Total Area= 0.21 Cumulative"C"= 0.46
iio= 7.92
Q1o= 0.78
Catch Basin #107
Drainage 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 Cumulative"C"= 0.56
iio= 7.92
Q1o= 3.86
Catch Basin #108
Drainage Area(acres): 0.180
Proposed Land Uses:
Land Use Description Acres %Site Runoff"C" "C"
Roofs 0.00 0% 0.95 0.00
Asphalt/Concrete Pavement 0.16 90% 0.95 0.85
Lawn 0.02 10% 0.3 0.03
Wooded 0.00 0% 0.2 0.00
Total Area= 0.18 Cumulative"C"= 0.88
iio= 7.92
Q1o= 1.26

Hydraflow Storm Sewers Extension for Autodesk® Civil 3D® Plan
CB#107
OUTFALL , 7
46 CB#101
2v
CB#102 8
45 CB#103
3
CB#104 43 CB#105
5'b
CB#106
-6
CB#108
Project File: 100 System-V2.0.stm Number of lines:8 Date: 11/20/2023
Storm Sewers v2022.00

Storm Sewer Inventory Report Pagel
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) (%) (ft) (in) (n) (K) (ft)
1 End 50.844 25.602 Genr 0.75 0.00 0.00 0.0 169.50 0.59 169.80 24 Cir 0.012 1.50 176.51 46
2 1 120.664 84.626 Genr 0.86 0.00 0.00 0.0 170.00 0.58 170.70 I 24 Cir 0.012 1.50 175.60 42
3 2 200.183 -1.274 Genr 1.25 I 0.00 0.00 0.0 170.80 0.55 171.90 18 Cir 0.012 1.50 176.23 44
4 3 29.723 -86.632 Genr 5.26 0.00 0.00 0.0 172.60 1.01 172.90 15 Cir 0.012 1.47 176.30 43
5 4 175.129 77.338 Genr 0.78 0.00 0.00 0.0 173.10 0.57 174.10 15 Cir 0.012 0.50 179.68 85
6 5 96.092 -14.489 Genr 1.26 0.00 0.00 0.0 176.20 1.04 177.20 15 Cir 0.012 1.00 181.15 197
7 1 86.290 -95.385 Genr 3.86 0.00 0.00 0.0 172.50 0.58 173.00 15 Cir 0.012 1.00 175.70 48
8 2 29.014 -88.216 Genr 2.62 0.00 0.00 0.0 171.60 0.69 171.80 15 Cir 0.012 1.00 175.59 45
Project File: 100 System-V2.0.stm I Number of lines:8 Date: 11/20/2023
Storm Sewers v2022.00

Storm Sewer Summary Report Pagel
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) (%) (ft) (ft) (ft) (ft) No.
1 46 16.64 24 Cir 50.844 169.50 169.80 0.590 170.96 171.27 1.06 171.27 End Generic
2 42 12.03 24 Cir 120.664 170.00 170.70 0.580 171.27 171.95 n/a 171.95 j 1 Generic
3 44 8.55 18 Cir 200.183 170.80 171.90 0.549 172.05 173.15 0.69 173.84 2 Generic
4 43 7.30 15 Cir 29.723 172.60 172.90 1.009 173.84 173.98 n/a 173.98 3 Generic
5 85 2.04 15 Cir 175.129 173.10 174.10 0.571 173.98 174.67 n/a 174.67 j 4 Generic
6 197 1.26 15 Cir 96.092 176.20 177.20 1.041 176.56 177.64 n/a 177.64 5 Generic
7 48 3.86 15 Cir 86.290 172.50 173.00 0.579 173.29 173.79 n/a 173.79 1 Generic
8 45 2.62 15 Cir 29.014 171.60 171.80 0.689 172.19 172.45 n/a 172.45 2 Generic
Project File: 100 System-V2.0.stm Number of lines:8 Run Date: 11/20/2023
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 (I) 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) (ft/s) (in) (%) (ft) (ft) (ft) (ft) (ft) (ft)
1 End 50.844 0.00 0.00 0.00 0.00 0.00 0.0 4.6 0.0 16.64 18.82 6.74 24 0.59 169.50 169.80 170.96 171.27 171.68 176.51 46
2 1 120.664 0.00 0.00 0.00 0.00 0.00 0.0 4.1 0.0 12.03 18.66 5.79 24 0.58 170.00 170.70 171.27 171.95 176.51 175.60 42
3 2 200.183 0.00 0.00 0.00 0.00 0.00 0.0 3.4 0.0 8.55 8.43 5.44 18 0.55 170.80 171.90 172.05 173.15 175.60 176.23 44
4 3 29.723 0.00 0.00 0.00 0.00 0.00 0.0 3.3 0.0 7.30 7.03 6.22 15 1.01 172.60 172.90 173.84 173.98 176.23 176.30 43
5 4 175.129 0.00 0.00 0.00 0.00 0.00 0.0 1.6 0.0 2.04 5.29 2.99 15 0.57 173.10 174.10 173.98 174.67 176.30 179.68 85
6 5 96.092 0.00 0.00 0.00 0.00 0.00 0.0 0.0 0.0 1.26 7.14 3.81 15 1.04 176.20 177.20 176.56 177.64 179.68 181.15 197
7 1 86.290 0.00 0.00 0.00 0.00 0.00 0.0 0.0 0.0 3.86 5.33 4.71 15 0.58 172.50 173.00 173.29 173.79 176.51 175.70 48
8 2 29.014 0.00 0.00 0.00 0.00 0.00 0.0 0.0 0.0 2.62 5.81 4.34 15 0.69 171.60 171.80 172.19 172.45 175.60 175.59 45
Project File: 100 System-V2.0.stm Number of lines:8 Run Date: 11/20/2023
NOTES:Intensity=88.24/(Inlet time+15.50)A 0.83; Return period=Yrs. 10 ; c=cir e=ellip b=box
Storm Sewers v2022.00

Hydraulic Grade Line Computations Page 1
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) (sgft) (ft/s) (ft) (ft) (%) (ft) (ft) (ft) (ft) (sgft) (ft/s) (ft) (ft) (%) (%) (ft) (K) (ft)
1 24 16.64 169.50 170.96 1.46 2.46 6.76 0.70 171.67 0.000 50.844 169.80 171.27 1.47** 2.47 6.73 0.70 171.97 0.000 0.000 n/a 1.50 1.06
2 24 12.03 170.00 171.27 1.27 2.06 5.72 0.53 171.80 0.000 120.664170.70 171.95 j 1.25** 2.06 5.85 0.53 172.48 0.000 0.000 n/a 1.50 n/a
3 18 8.55 170.80 172.05 1.25* 1.57 5.44 0.46 172.51 0.549 200.183171.90 173.15 1.25 1.57 5.44 0.46 173.61 0.549 0.549 1.100 1.50 0.69
4 15 7.30 172.60 173.84 1.24 1.12 5.96 0.65 174.49 0.000 29.723 172.90 173.98 1.08** 1.12 6.49 0.65 174.63 0.000 0.000 n/a 1.47 n/a
5 15 2.04 173.10 173.98 0.88 0.54 2.22 0.22 174.20 0.000 175.129174.10 174.67 j 0.57** 0.54 3.76 0.22 174.89 0.000 0.000 n/a 0.50 0.11
6 15 1.26 176.20 176.56 0.36* 0.29 4.38 0.16 176.72 0.000 96.092 177.20 177.64 0.44** 0.39 3.24 0.16 177.81 0.000 0.000 n/a 1.00 n/a
7 15 3.86 172.50 173.29 0.79* 0.82 4.73 0.34 173.63 0.000 86.290 173.00 173.79 0.79** 0.82 4.70 0.34 174.14 0.000 0.000 n/a 1.00 n/a
8 15 2.62 171.60 172.19 0.59* 0.57 4.61 0.26 172.45 0.000 29.014 171.80 172.45 0.65** 0.64 4.08 0.26 172.71 0.000 0.000 n/a 1.00 n/a
Project File: 100 System-V2.0.stm Number of lines:8 Run Date: 11/20/2023
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-V2.0.stm
Q O N 71-
Ln co CO
I—
LL 0 O.— It 0 0 0 0
D eak
O U COCU CU
0 m 0 0
U
N N CO Lo coer
7 C 7 C 7 C 5 C 7 C 7
°0 C J C J C J C J C J C J
O ' 00 ' 000 MOO ' 000 ' 000 ' LoO
0 "') Q �00•0 00 °�O O N CO CI a),- ��N CO 7N
p0 co •
��O • ^00 CO �f`� V ^� • �nti co. Wn
Elev. (ft) 0 w r n II o n ,,
o• � W O WWW WWW M WWW v WWW WWW co EH
:° E > w E » co E » ;g E» co E » asE » :g E >
fn 0fn co cn = in to REEcn Ft c
195.00 195.00
•
•
•
•
189.00 • - - 189.00
•
•
183.00 183.00
•
•
•
•
177.00 K/ ....._....____.
177.00
-
}�5.129Lf-1 E"a0.577%
��00.103Lf 18"Q �
171.00 — — 913.092Lt-15" ch711.&P/°
I
• — 120 664Lf-24"a 0 58% — 28.723Lf 16"@ 1.014!
— &0.044L1-24"@ 0.59%
165.00 165.00
0 50 100 150 200 250 300 350 400 450 500 550 600 650 700
Reach (ft)
Storm Sewers

Storm Sewer Profile Proj. file: 100 System-V2.0.stm
N C')
O O
INT
m m
U U
O E. -J 0
c co. onm v �oo
Elev. (ft) o
O N
O W W W O W W
E > > co E>
184.00 184.00
•
181.00 - . 181.00
•
178.00 178.00
175.00 175.00
172.00 29.014Lf-15"(cil %U.69
172.00
169.00 169.00
0 10 20 30 40 50 60 70 80 90 100
Reach (ft)
Storm Sewers

Storm Sewer Profile Proj. file: 100 System-V2.0.stm
0
o o ti
4.7 o
m
U- 0 U
c N-
c
0 CO
pp C J OE J 0
V oc,co Lo
00
O O O 00� n r^
Elev. (ft) oW ( �, co
o -6 w o www Ww
m E > m E » co E >
0 0 E co ESE co Ft
186.00 186.00
•
182.00 - • - 182.00
178.00 178.00
•
-
174.00 174.00
• ab.t901_1- 15"@ 3.58%
•
50.844Lf-94"©0.59%
170.00 170.00
•
166.00 166.00
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140
Reach (ft)
Storm Sewers

Bowman
[Von7FlCAUL !!VA
APPENDIX D
Erosion and Sediment Control Calculations
Rip-Rap Calculations
Skimmer Basin
Riser
Temporary Diversion Ditches
Erwin Road Residential—Dunn, NC 11

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=
Stone Filling Class= A
Entry Width(2 X Do)= 4.0 ft
Length(4 X Do)= 8.O ft
Width(La+Do)= 10.0 ft
Min.Thickness= 12 inches
Min.Stone Diameter= 3 inches
8.0
1
4.0 10.0
1
*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=� 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
lk
3.0 7.5
Jr
*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,AR= 7.94 Ac
10-year Runoff(Q10) C= 0.50
T�= 5.00 min
110= 7.92 in/hr
Q10= 25.9 cfs
Surface Area Required SA= 325sf x Q10
SA= 8,422 sf
Volume Required VR= 1800 cf/Ac x AD
VR= 11,779 cf
Sediment Trap Dimensions L= 167 ft (Spillway Length)
W= 60 ft (Spillway Width)
D= 2.0 ft (Depth of Storage)
Side Slopes= 2:1
Lroo=
Lrap= 175 ft
Lbor= 159 ft Wrur Wrpr
Wrap= 68 ft Lbor=
Wbor= 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
C,v= 3
Lw= 25 ft

Calculate Skimmer Size
Basin Volume in Cubic Feet 17,721 Cu.Ft Skimmer Size 2.5 Inch
Days to Drain* 3 Days Orifice Radius 1.2 Inch[es]
Orifice Diameter 2.4 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 52 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 lbs
Factor of Safety 1.20
WT Req'd of Anti-Flotation Device: 2,396 lbs
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
AMERICAN 5401 St. Wendel-Cynthiana Rd.
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 0.0073
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 3.16 ft/s 1.53 ft 0.034 1.6 lbs/ft2 0.7 lbs/ft2 2.3 STABLE D
Unvegetated
Underlying Straight 19.6 cfs 3.16 ft/s 1.53 ft 0.034 1.51 lbs/ft2 0.36 lbs/ft2 4.21 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

741 NORTH North American Green
AMERICAN 5401 St. Wendel-Cynthiana Rd.
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 lbs/ft2 0.57 lbs/ft2 2.79 STABLE D
Unvegetated
Underlying Straight 3.5 cfs 2.68 ft/s 0.6 ft 0.035 1.51 lbs/ft2 0.34 lbs/ft2 4.42 STABLE D
Substrate