SW4190901_Stormwater Report - Auto Table(with Appendix) 01-08-2020 Small_1/20/2020

ANDERSON ►1 ENGINEERING
EMPLOYEE OWNED
Stormwater Management & Drainage Report
O'Reilly Auto Parts
Old U.S. 52
Lexington, NC
FOR
O'Reilly Automotive Stores, Inc.
233 S. Patterson
Springfield MO 65802
Phone: [phone]
REVISED
January 8,2020
Report Prepared By:
ANDERSON ENGINEERING, INC
2045 W. Woodland
Springfield, Missouri 65807
Phone: [phone]
P.N. 18SP10289
Anc',eG son.Engineeri.iginc.coro-i
2045 W. Woodland, Springfield, Missouri 64807 - Phone: [phone]• E-mail: [e-mail]

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ar
Table of Contents
I. Project Description and General Information............................................................................................1
A. PROJECT DESCRIPTION.........................................................................................................................1
ExistingSite Description........................................................................................................................1
DevelopedSite Description...................................................................................................................1
Table 1, 2 and 3: Pre -Developed Rates.....................................................................................................2
Table 4, 5, 6, 7 : Post -Developed Rates..................................................................................................2-3
Table 7: Release from Water Quality Basin..............................................................................................3
Table 8: Release from Detention Basin..................................................................................................... 3
Conclusion................................................................................................................................................. 4
Appendix
GEOTECHNICAL ENGINEERING REPORT
SOIL DATA
DRAINAGE MAPS
HYDRAFLOW OUTPUT
SEDIMENT BASIN CALCULATIONS
RIP -RAP CALCULATION

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Project Description and Purpose
The purpose of this report is to analyze the stormwater impact of the proposed new O'Reilly Auto Parts
store in Lexington, NC. The total area of the property is 1.26 acres. The disturbed area is proposed to
be 1.25 acres.
Existing Site
The O'Reilly Auto Parts site is part of larger development. The master development has two phases.
Phase 1 of the development was a Family Dollar commercial retail store at the northwest corner of
Welcome Arcadia Rd. and Old U.S. Hwy 52. The Family Dollar site consists of 1.33 acres. The Family
Dollar site was preceded by a vacant building, home and parking lot that totaled 0.52 acres of
impervious. The Family Dollar site is currently built with a total impervious area of 0.87 acres. The
Family Dollar site has an existing State Stormwater Permit. Their pond is located on Phase II of this
development which will become the O'Reilly Auto Parts Site.
Phase II of the project is the O'Reilly Auto Parts proposed store and parking lot. The existing site is
completely vacant except for the stormwater pond that is currently used by the Family Dollar. There is
no assumed existing impervious area for the O'Reilly Auto Parts site.
Developed Site
Phase 1 and Phase 2 of this project will now be joined for the stormwater design. Water Quality and
Detention is part of the new proposed design. The Family Dollar site drains onto the proposed O'Reilly
Auto Parts site via stormwater piping. The current impervious area for the Family Dollar site is 0.87
acres with a total site area of 1.33 acres.
The Phase 2 portion of the site is the proposed O'Reilly Auto Parts site. The total project area is 1.29
acres and a disturbed area of 1.25 acres. The proposed impervious area for Phase 2 is 0.62 acres. The
O'Reilly project is split into two drainage areas. The first is the parking lot east of the proposed building
and the second includes the building and western parking lot.
Both Phase 1 and Phase 2 will be treated via an underground sand filter and sedimentation basin.
Storms larger than the water quality volume will bypass the system and flow into the proposed
underground detention system. Both underground systems are manufactured products by StormTrap.
The design sheets for the underground system are located on the Civil design sheets.
All storm events up to the 100-year storm will be reduced to below existing conditions. A detention
outlet structure in the underground detention basin will control the storm events. The development will
discharge to northwest corner of the property which is similar to existing drainage patterns.

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Water Quality Information
The total area for Phase 1 and Phase 2 of this project is 2.62 acres with a total impervious area of 1.48
acres. The required WQv for the 1-inch storm is 5,392 cu.ft. This was calculated used the Simple
Method which takes into account the entire area and the proposed impervious surface. A 25%
reduction is included per the NCDEQ design manual for sand filters resulting in a required WQv of 4,044
cu.ft.
The Water Quality volume shall be captured in the underground Sand and Sedimentation basin and
discharged into the underground detention system.
Table 1: Pre -Developed Rates from O'Reilly Auto Site (Hydrograph #1)
Pre -developed 1 0.96
30 min
Site Release
Rate 10 2.84 30 min
A A 100
Table 2: Pre -Developed Rates from Family Dollar Site (Hydrograph #2)
Storm Event
(Year)
Wime of Concentration
Pre -developed
Site Release
Rate00
10.64
10 min
Table 3: Pre -Developed Rates from Combined Developments (Hydrograph #6)
atvrm went
(Year)
Time of Concentration
Pre -developed •
Site Release 2 4.62
Rate
00 13.97
Table 4: Post -Developed Rates DA #1 in O'Reilly Auto (Hydrograph #3)
- 1 ime yr wncentrativn
Post -developed
Site Release
Rate
00
2

Table 5: Post -Developed Rates DA #2 in O'Reilly Auto (Hydrograph #4)
MNW(Year)
���MWme
of Concentration
Post-developed
Site Release
Rate 10
5.24
5 min
00
Table 6: Post -Developed Rates from Family Dollar Site (Hydrograph #5)
torm Eve
WME
of Concentration MMW (Year)
Post -developed 1 4.65
Site Release
Rate 10 8.97
11
Table 7: Post -Developed Rates Combined (Hvdroeraph #7)
torm Event
(Year)
Time of Concentration
A�
� evelo
•Release
Li
Rate
. .
A..
•.
5 min
Table 8: Release from Sand / Sedimentation Basin (Hydrograph #8)
1
1.23
8,693
859.47
2
6.53
9,693
860.07
10
15.61
10,852
860.78
100
24.73
11,795
861.35
Table 9: Release from Underground Detention
1
0.76
3.29
1,265
854.72
2
2.30
4.62
2,802
855.35
10
5.66
8.22
8,323
857.62
100
12.38
13.97
15.532
860.59
3

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Conclusion
The proposed O'Reilly Auto Parts project is part of a two-phase development and combined stormwater
pond. Phase 1 and Phase 2 of this project will now be joined for the stormwater design.
The Water Quality volume for the site was calculated using the Simple Method as outlined in the NCDEQ
handbook. The first 1-inch storm produces a volume of 5,392 cu.ft. and with an allowed reduction of
25%, the adjusted Water Quality volume is 4,044 cu.ft. Water Quality is provided on the proposed
project via an underground sand filter and sedimentation basin. The Water Quality basin discharges into
an underground detention basin.
Detention is proposed on the O'Reilly Auto Parts project via underground concrete chambers. The
detention system is downstream of the underground sand filter. The detention volume is controlled by
a weir wall inside of the underground storage chamber. A 7" and 11" orifice control storm events to
rates less than the existing conditions. The 100-year storm event is proposed to store to an elevation of
860.59'. Larger storms will exist the system and continue downstream.
The final outfall of the project is a pipe and rip -rap pad. The site discharges to the northwest corner of
the property which is the general location of existing stormwater flows.
4

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APPENDIX

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DRAINAGE AREA MAPS

.w
D
-� ---------------
I
J I y11 i I^
O REILLY AUT
,-____ACRES = 1.29
-- _CN=76
Tc=30 MIN
=_.100 YEAR, FLO
J
COW
S \ i IL
� I• )'
\ I \
E \
1
16 CFS �'►, I =,
FAMILY DOLLAR
ACRES = 1.33
CN=83
Tc=10 MIN
1'00 YEAR F06TU = 10.64 CFS it
it
CONST.
N N
1 EXISTING DRAINAGE MAP 30 0 30 60 90
SCALE: 7' = 30'-O'
(81 GRAPHIC SCALE - FEET
� I
I
II
I
I
IrLie_

CONST.
N N
2 SITE DRAINAGE MAPS 30 0 30 60 90
SCALE: I'm 30'•0' (81 GRAPHIC SCALE' FEET

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SOIL DATA

3:
-
Hydrologic Soil Group —Davidson County, North Carolina
v
In
In
35o 54' 41" N
567130 567140 567150 567160 567170 567180 567190 567200 567210 567220 567230 567240 567250 567260
567270 567280 567290 567300
35o 54' 41" N
+
o
o
��L7
O a
QQ
i
N
Soil MaN may not he valiel at this scale.
35o 54' 37" N
I I I I I I
I
35o 54' 37" N
567130 567140 567150 567160 567170 567180 567190 567200 567210 567220 567230 567240 567250 567260
567270 567280 567290 567300
-
Map Scale: 1:826 if printed on A landscape (11" x 8.5") sheet.
v
Myers
..
$
N 0 10 20 40 60
$
Feet
0 40 80 160 240
Map projection: Web Mercator Conermordinates: WGS84 Edge tics: lfrM Zone 17N WGS84
USDA
Natural Resources Web Soil Survey
4/30/2018
aIiiiiiiiIIIIIIII
Conservation Service National Cooperative Soil Survey
Pagel of 4

Hydrologic Soil Group —Davidson County, North Carolina
MAP LEGEND
Area of Interest (AOI)
0
Area of Interest (AOI)
Soils
Soil Rating
Polygons
0
A
0
A/D
0
B
0
B/D
0
C
0
C/D
0
D
0
Not rated or not available
Soil Rating
Lines
r 0
A
r 0
A/D
B
r
B/D
N 0
C
r 0
C/D
r 0
D
r 0
Not rated or not available
Soil Rating
Points
0
A
0
A/D
0
B
0
B/D
❑ C
0 C/D
0 D
❑ Not rated or not available
Water Features
Streams and Canals
Transportation
— Rails
­0 Interstate Highways
US Routes
Major Roads
Local Roads
Background
Aerial Photography
MAP INFORMATION
The soil surveys that comprise your AOI were mapped at
1:24,000.
Warning: Soil Map may not be valid at this scale.
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
line placement. The maps do not show the small areas of
contrasting soils that could have been shown at a more detailed
scale.
Please rely on the bar scale on each map sheet for map
measurements.
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Coordinate System: Web Mercator (EPSG:3857)
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
This product is generated from the USDA-NRCS certified data as
of the version date(s) listed below.
Soil Survey Area: Davidson County, North Carolina
Survey Area Data: Version 18, Sep 26, 2017
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Jun 14, 2015—Mar
15, 2017
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
USDA Natural Resources Web Soil Survey 4/30/2018
Conservation Service National Cooperative Soil Survey Page 2 of 4

Hydrologic Soil Group —Davidson County, North Carolina
Hydrologic Soil Group
Map unit symbol
Map unit name
Rating
Acres in AOI
Percent of AOI
CfB
Cecil -Urban land
complex, 2 to 8
percent slopes
B
0.4
27.7%
VaD
Vance sandy loam, 8 to
15 percent slopes
C
0.9
72.3%
Totals for Area of Interest
1.3
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 4/30/2018
Conservation Service National Cooperative Soil Survey Page 3 of 4

Hydrologic Soil Group —Davidson County, North Carolina
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff.- None Specified
Tie -break Rule: Higher
USDA Natural Resources Web Soil Survey 4/30/2018
Conservation Service National Cooperative Soil Survey Page 4 of 4

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HYDRAFLOW

Hydraflow Table of Contents
Lexington NC 7-22-19.gpw
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Watershed Model Schematic...................................................................................... 1
Hydrograph Return Period Recap............................................................................. 2
1 - Year
SummaryReport.........................................................................................................................
3
HydrographReports
...................................................................................................................
4
Hydrograph No.
1, SCS Runoff, O'Reilly Pre-Development.....................................................
4
Hydrograph No.
2, SCS Runoff, Family Dollar Pre -developed .................................................
5
Hydrograph No.
3, SCS Runoff, O'Reilly DA#1.......................................................................
6
Hydrograph No.
4, SCS Runoff, O'Reilly DA#2.......................................................................
7
Hydrograph No.
5, SCS Runoff, Family Dollar Developed.......................................................
8
Hydrograph No.
6, Combine, Combined PreDeveloped..........................................................
9
Hydrograph No.
7, Combine, Combined to Rear Ponds ........................................................
10
Hydrograph No.
8, Reservoir, Routed Sand Filter..................................................................
11
PondReport
- Sed Sand....................................................................................................
12
Hydrograph No.
9, Reservoir, Routed Rear Pond..................................................................
13
PondReport
- <New Pond>...............................................................................................
14
2 - Year
SummaryReport
.......................................................................................................................
15
HydrographReports.................................................................................................................
16
Hydrograph No.
1, SCS Runoff, O'Reilly Pre-Development...................................................
16
Hydrograph No.
2, SCS Runoff, Family Dollar Pre -developed ...............................................
17
Hydrograph No.
3, SCS Runoff, O'Reilly DA#1.....................................................................
18
Hydrograph No.
4, SCS Runoff, O'Reilly DA#2.....................................................................
19
Hydrograph No.
5, SCS Runoff, Family Dollar Developed.....................................................
20
Hydrograph No.
6, Combine, Combined PreDeveloped........................................................
21
Hydrograph No.
7, Combine, Combined to Rear Ponds ........................................................
22
Hydrograph No.
8, Reservoir, Routed Sand Filter..................................................................
23
Hydrograph No.
9, Reservoir, Routed Rear Pond..................................................................
24
10 - Year
SummaryReport
.......................................................................................................................
25
HydrographReports.................................................................................................................
26
Hydrograph No.
1, SCS Runoff, O'Reilly Pre-Development...................................................
26
Hydrograph No.
2, SCS Runoff, Family Dollar Pre -developed ...............................................
27
Hydrograph No.
3, SCS Runoff, O'Reilly DA#1.....................................................................
28
Hydrograph No.
4, SCS Runoff, O'Reilly DA#2.....................................................................
29
Hydrograph No.
5, SCS Runoff, Family Dollar Developed.....................................................
30
Hydrograph No.
6, Combine, Combined PreDeveloped........................................................
31
Hydrograph No.
7, Combine, Combined to Rear Ponds ........................................................
32
Hydrograph No.
8, Reservoir, Routed Sand Filter..................................................................
33
Hydrograph No.
9, Reservoir, Routed Rear Pond..................................................................
34
100 -Year
SummaryReport....................................................................................................................... 35
HydrographReports................................................................................................................. 36

Contents continued...
Lexington NC 7-22-19.gpw
Hydrograph No
Hydrograph No
Hydrograph No
Hydrograph No
Hydrograph No
Hydrograph No
Hydrograph No
Hydrograph No
Hydrograph No
1, SCS Runoff, O'Reilly Pre-Development...................................................
36
2, SCS Runoff, Family Dollar Pre -developed ...............................................
37
3, SCS Runoff, O'Reilly DA#1.....................................................................
38
4, SCS Runoff, O'Reilly DA#2.....................................................................
39
5, SCS Runoff, Family Dollar Developed.....................................................
40
6, Combine, Combined PreDeveloped........................................................
41
7, Combine, Combined to Rear Ponds ........................................................
42
8, Reservoir, Routed Sand Filter..................................................................
43
9, Reservoir, Routed Rear Pond..................................................................
44
OFReport.................................................................................................................. 45

1
Watershed Model Schematic Hydraflow Hydrographs Extension forAutodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
3 4 5
CD COD
k6
7
Legend
Hvd. Origin Description
1 SCS Runoff O'Reilly Pre -Development
2 SCS Runoff Family Dollar Pre -developed
3 SCS Runoff O'Reilly DA #1
4 SCS Runoff O'Reilly DA #2
5 SCS Runoff Family Dollar Developed
6 Combine Combined Pre Developed
7 Combine Combined to Rear Ponds
8 Reservoir Routed Sand Filter
9 Reservoir Routed Rear Pond
Project: Lexington NC 7-22-19.gpw Thursday, 07 / 25 / 2019

Hydrograph Return Period Recan
Hydra w Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd.
Hydrograph
Inflow
Peak Outflow (cfs)
Hydrograph
No.
type
hyd(s)
Description
(origin)
1-yr
2-yr
3-yr
5-yr
10-yr
25-yr
50-yr
100-yr
1
SCS Runoff
------
0.962
1.455
-------
-------
2.842
-------
-------
5.160
O'Reilly Pre -Development
2
SCS Runoff
------
2.747
3.767
-------
-------
6.450
-------
-------
10.64
Family Dollar Pre -developed
3
SCS Runoff
------
1.248
1.591
-------
-------
2.452
-------
-------
3.753
O'Reilly DA #1
4
SCS Runoff
------
2.312
3.120
-------
-------
5.237
-------
-------
8.529
O'Reilly DA #2
5
SCS Runoff
------
4.651
5.882
-------
-------
8.965
-------
-------
13.62
Family Dollar Developed
6
Combine
1, 2,
3.286
4.622
-------
-------
8.220
-------
-------
13.97
Combined Pre Developed
7
Combine
3, 4, 5,
8.193
10.58
-------
-------
16.65
-------
-------
25.90
Combined to Rear Ponds
8
Reservoir
7
1.889
7.330
-------
-------
15.70
-------
-------
24.73
Routed Sand Filter
9
Reservoir
8
0.900
2.480
-------
-------
5.678
-------
-------
10.88
Routed Rear Pond
Proj. file: Lexington NC 7-22-19.gpw
Thursday, 07 / 25 / 2019

Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
0.962
1
732
4,134
------
------
------
O'Reilly Pre -Development
2
SCS Runoff
2.747
1
720
6,215
------
------
------
Family Dollar Pre -developed
3
SCS Runoff
1.248
1
717
2,612
------
------
------
O'Reilly DA #1
4
SCS Runoff
2.312
1
718
4,661
------
------
------
O'Reilly DA #2
5
SCS Runoff
4.651
1
717
9,822
------
------
------
Family Dollar Developed
6
Combine
3.286
1
720
10,349
1, 2,
------
------
Combined Pre Developed
7
Combine
8.193
1
717
17,095
3, 4, 5,
------
------
Combined to Rear Ponds
8
Reservoir
1.889
1
726
8,848
7
859.59
8,889
Routed Sand Filter
9
Reservoir
0.900
1
745
8,847
8
854.57
895
Routed Rear Pond
Lexington NC 7-22-19.gpw
Return Period: 1 Year
Thursday, 07 / 25 / 2019

4
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 1
O'Reilly Pre -Development
Hydrograph type =
SCS Runoff
Peak discharge
= 0.962 cfs
Storm frequency =
1 yrs
Time to peak
= 732 min
Time interval =
1 min
Hyd. volume
= 4,134 cuft
Drainage area =
1.290 ac
Curve number
= 76*
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 30.00 min
Total precip. =
2.80 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.900 x 74) + (0.350 x 80)] / 1.290
Q (cfs)
1.00
0.90
in We
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0
O'Reilly Pre -Development
Hyd. No. 1 -- 1 Year
Q (cfs)
1.00
0.90
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

Hydrograph
Report
5
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 2
Family Dollar Pre -developed
Hydrograph type
= SCS Runoff
Peak discharge
= 2.747 cfs
Storm frequency
= 1 yrs
Time to peak
= 720 min
Time interval
= 1 min
Hyd. volume
= 6,215 cuft
Drainage area
= 1.330 ac
Curve number
= 83*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 2.80 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) _ [(0.520 x 98) + (0.810 x 74)] / 1.330
Family Dollar Pre -developed
Q (cfs) Hyd. No. 2 -- 1 Year Q (cfs)
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. 2 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd. No. 3
O'Reilly DA #1
Hydrograph type
= SCS Runoff
Peak discharge
Storm frequency
= 1 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Drainage area
= 0.370 ac
Curve number
Basin Slope
= 0.0 %
Hydraulic length
Tc method
= User
Time of conc. (Tc)
Total precip.
= 2.80 in
Distribution
Storm duration
= 24 hrs
Shape factor
Composite (Area/CN) = [(0.230 x 98) + (0.140 x 80)] / 0.370
Q (cfs)
2.00
1.00
e
120
Hyd No. 3
O'Reilly DA #1
Hyd. No. 3 -- 1 Year
Thursday, 07 / 25 / 2019
= 1.248 cfs
= 717 min
= 2,612 cuft
= 91*
= 0 ft
= 5.00 min
= Type II
= 484
240 360 480 600 720 840 960 1080 1200
Q (cfs)
2.00
1.00
0.00
1320
Time (min)

Hydrograph
Report
7
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 4
O'Reilly DA #2
Hydrograph type
= SCS Runoff
Peak discharge
= 2.312 cfs
Storm frequency
= 1 yrs
Time to peak
= 718 min
Time interval
= 1 min
Hyd. volume
= 4,661 cuft
Drainage area
= 0.920 ac
Curve number
= 84*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 2.80 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) _ [(0.390 x 98) + (0.530 x 74)] / 0.920
O'Reilly DA #2
Q (cfs) Hyd. No. 4 -- 1 Year Q (cfs)
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)

8
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 5
Family Dollar Developed
Hydrograph type
= SCS Runoff
Peak discharge
= 4.651 cfs
Storm frequency
= 1 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 9,822 cuft
Drainage area
= 1.330 ac
Curve number
= 92*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 2.80 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.870 x 98) + (0.460 x 80)] / 1.330
Q (cfs)
5.00
4.00
3.00
2.00
1.00
Family Dollar Developed
Hyd. No. 5 -- 1 Year
Q (cfs)
5.00
4.00
3.00
2.00
1.00
0.00 ' ' ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320
— Hyd No. 5 Time (min)

9
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 6
Combined PreDeveloped
Hydrograph type = Combine Peak discharge = 3.286 cfs
Storm frequency = 1 yrs Time to peak = 720 min
Time interval = 1 min Hyd. volume = 10,349 cuft
Inflow hyds. = 1, 2 Contrib. drain. area = 2.620 ac
Combined PreDeveloped
Q (cfs) Hyd. No. 6 -- 1 Year Q (cfs)
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
Time (min)
— Hyd No. 6 — Hyd No. 1 Hyd No. 2

Hydrograph
Report
10
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 7
Combined to Rear Ponds
Hydrograph type
= Combine
Peak discharge
= 8.193 cfs
Storm frequency
= 1 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 17,095 cuft
Inflow hyds.
= 3, 4, 5
Contrib. drain. area
= 2.620 ac
Q (cfs)
10.00
N. We
. UX
4.00
2.00
M
Combined to Rear Ponds
Hyd. No. 7 -- 1 Year
120 240 360 480 600 720 840
Hyd No. 7 Hyd No. 3 Hyd No. 4
Q (cfs)
10.00
ItX
Me
4.00
2.00
0.00
960 1080 1200 1320
Hyd No. 5 Time (min)

Hydrograph
Report
11
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 8
Routed Sand Filter
Hydrograph type
= Reservoir
Peak discharge
= 1.889 cfs
Storm frequency
= 1 yrs
Time to peak
= 726 min
Time interval
= 1 min
Hyd. volume
= 8,848 cuft
Inflow hyd. No.
= 7 - Combined to Rear Ponds
Max. Elevation
= 859.59 ft
Reservoir name
= Sed Sand
Max. Storage
= 8,889 cuft
Storage Indication method used
Q (cfs)
10.00
N. We
. UX
4.00
2.00
Routed Sand Filter
Hyd. No. 8 -- 1 Year
120 240 360 480 600 720
Hyd No. 8 Hyd No. 7
Q (cfs)
10.00
OR
Me
4.00
2.00
0.00
840 960 1080 1200 1320 1440 1560
Time (min)
Total storage used = 8,889 cuff

Pond Report 12
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Pond No. 2 - Sed Sand
Pond Data
UG Chambers -Invert elev. = 854.20 ft, Rise x Span = 8.33 x 26.50 ft, Barrel Len = 62.25 ft, No. Barrels = 1, Slope = 0.00%, Headers = No
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)
0.00
854.20
n/a
0
0
0.83
855.03
n/a
1,374
1,374
1.67
855.87
n/a
1,374
2,749
2.50
856.70
n/a
1,374
4,123
3.33
857.53
n/a
1,374
5,498
4.17
858.36
n/a
1,374
6,872
5.00
859.20
n/a
1,374
8,246
5.83
860.03
n/a
1,374
9,621
6.66
860.86
n/a
1,374
10,995
7.50
861.70
n/a
1,374
12,370
8.33
862.53
n/a
1,374
13,744
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[PrFRSr]
[A]
[B]
[C]
[D]
Rise (in)
= 1.50
0.00
0.00
0.00
Crest Len (ft)
= 3.00
0.00
0.00
0.00
Span (in)
= 1.50
0.00
0.00
0.00
Crest El. (ft)
= 859.20
0.00
0.00
0.00
No. Barrels
= 1
0
0
0
Weir Coeff.
= 2.60
3.33
3.33
3.33
Invert El. (ft)
= 854.20
0.00
0.00
0.00
Weir Type
= Broad
---
---
---
Length (ft)
= 0.50
0.00
0.00
0.00
Multi -Stage
= No
No
No
No
Slope (%)
= 0.01
0.00
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
Wet area)
Multi -Stage
= n/a
No
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 /
Storage / Discharge Table
Stage
Storage
Elevation
Clv A
Clv B
Clv C
PrfRsr
Wr A
Wr B
Wr C
Wr D
Exfil
User
Total
ft
cuft
ft
cfs
cfs
cfs
cfs
cfs
cfs
cfs
cfs
cfs
cfs
cfs
0.00
0
854.20
0.00
---
---
---
0.00
---
---
---
---
---
0.000
0.83
1,374
855.03
0.05 is
---
---
---
0.00
---
---
---
---
---
0.052
1.67
2,749
855.87
0.07 is
---
---
---
0.00
---
---
---
---
---
0.075
2.50
4,123
856.70
0.09 is
---
---
---
0.00
---
---
---
---
---
0.092
3.33
5,498
857.53
0.11 is
---
---
---
0.00
---
---
---
---
---
0.107
4.17
6,872
858.36
0.12 is
---
---
---
0.00
---
---
---
---
---
0.120
5.00
8,246
859.20
0.13 is
---
---
---
0.00
---
---
---
---
---
0.131
5.83
9,621
860.03
0.14 is
---
---
---
5.91
---
---
---
---
---
6.051
6.66
10,995
860.86
0.15 is
---
---
---
16.74
---
---
---
---
---
16.89
7.50
12,370
861.70
0.16 is
---
---
---
30.78
---
---
---
---
---
30.94
8.33
13,744
862.53
0.17 is
---
---
---
47.40
---
---
---
---
---
47.57

Hydrograph
Report
13
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc.
v2020
Thursday, 07 / 25 / 2019
Hyd. No. 9
Routed Rear Pond
Hydrograph type
= Reservoir
Peak discharge
= 0.900 cfs
Storm frequency
= 1 yrs
Time to peak
= 745 min
Time interval
= 1 min
Hyd. volume
= 8,847 cuft
Inflow hyd. No.
= 8 - Routed Sand Filter
Max. Elevation
= 854.57 ft
Reservoir name
= <New Pond>
Max. Storage
= 895 cuft
Storage Indication method used
Q (cfs)
2.00
1.00
Routed Rear Pond
Hyd. No. 9 -- 1 Year
120 240 360 480 600 720
Hyd No. 9 Hyd No. 8
Q (cfs)
2.00
1.00
0.00
840 960 1080 1200 1320 1440 1560
Time (min)
Total storage used = 895 cuff

Pond Report 14
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Pond No. 1 - <New Pond>
Pond Data
UG Chambers -Invert elev. = 854.20 ft, Rise x Span = 6.50 x 30.00 ft, Barrel Len = 81.00 ft, No. Barrels = 1, Slope = 0.00%, Headers = No
Stage / Storage Table
Stage (ft) Elevation (ft) Contour area (sqft) Incr. Storage (cuft) Total storage (cuft)
0.00
854.20
n/a
0
0
0.65
854.85
n/a
1,580
1,580
1.30
855.50
n/a
1,580
3,160
1.95
856.15
n/a
1,580
4,739
2.60
856.80
n/a
1,580
6,319
3.25
857.45
n/a
1,580
7,899
3.90
858.10
n/a
1,580
9,479
4.55
858.75
n/a
1,580
11,059
5.20
859.40
n/a
1,580
12,639
5.85
860.05
n/a
1,580
14,218
6.50
860.70
n/a
1,580
15,798
Culvert / Orifice Structures
Weir Structures
[A]
[B]
[C]
[PrFRSr]
[A]
[B]
[C]
[D]
Rise (in)
= 24.00
11.00
7.00
0.00
Crest Len (ft)
= 6.00
0.00
0.00
0.00
Span (in)
= 24.00
11.00
7.00
0.00
Crest El. (ft)
= 860.30
0.00
0.00
0.00
No. Barrels
= 1
1
1
0
Weir Coeff.
= 3.33
3.33
3.33
3.33
Invert El. (ft)
= 854.20
854.21
857.00
0.00
Weir Type
= 1
---
---
---
Length (ft)
= 33.00
0.50
0.50
0.00
Multi -Stage
= Yes
No
No
No
Slope (%)
= 5.00
0.50
0.05
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
Wet area)
Multi -Stage
= n/a
Yes
Yes
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 /
Storage / Discharge Table
Stage
Storage
Elevation
Clv A
Clv B
Clv C
PrfRsr
Wr A
Wr B
Wr C
Wr D
Exfil
User
Total
ft
cuft
ft
cfs
cfs
cfs
cfs
cfs
cfs
cfs
cfs
cfs
cfs
cfs
0.00
0
854.20
0.00
0.00
0.00
---
0.00
---
---
---
---
---
0.000
0.65
1,580
854.85
1.13 is
1.12 is
0.00
---
0.00
---
---
---
---
---
1.124
1.30
3,160
855.50
2.59 is
2.54 is
0.00
---
0.00
---
---
---
---
---
2.539
1.95
4,739
856.15
3.52 is
3.43 is
0.00
---
0.00
---
---
---
---
---
3.434
2.60
6,319
856.80
4.18 is
4.18 is
0.00
---
0.00
---
---
---
---
---
4.184
3.25
7,899
857.45
5.31 is
4.78 is
0.51 is
---
0.00
---
---
---
---
---
5.290
3.90
9,479
858.10
6.53 is
5.31 is
1.16 is
---
0.00
---
---
---
---
---
6.464
4.55
11,059
858.75
7.37 is
5.81 is
1.55 is
---
0.00
---
---
---
---
---
7.367
5.20
12,639
859.40
8.16 is
6.29 is
1.87 is
---
0.00
---
---
---
---
---
8.161
5.85
14,218
860.05
8.91 is
6.75 is
2.14 is
---
0.00
---
---
---
---
---
8.885
6.50
15,798
860.70
14.26 is
6.83 is
2.38 is
---
5.06
---
---
---
---
---
14.26

15
Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
1.455
1
732
6,022
------
------
------
O'Reilly Pre -Development
2
SCS Runoff
3.767
1
719
8,528
------
------
------
Family Dollar Pre -developed
3
SCS Runoff
1.591
1
717
3,376
------
------
------
O'Reilly DA #1
4
SCS Runoff
3.120
1
718
6,346
------
------
------
O'Reilly DA #2
5
SCS Runoff
5.882
1
717
12,604
------
------
------
Family Dollar Developed
6
Combine
4.622
1
720
14,550
1, 2,
------
------
Combined Pre Developed
7
Combine
10.58
1
717
22,326
3, 4, 5,
------
------
Combined to Rear Ponds
8
Reservoir
7.330
1
721
14,079
7
860.17
9,832
Routed Sand Filter
9
Reservoir
2.480
1
730
14,078
8
855.26
2,578
Routed Rear Pond
Lexington NC 7-22-19.gpw
Return Period: 2 Year
Thursday, 07 / 25 / 2019

Hydrograph Report
16
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd. No. 1
O'Reilly Pre -Development
Hydrograph type =
SCS Runoff
Peak discharge
Storm frequency =
2 yrs
Time to peak
Time interval =
1 min
Hyd. volume
Drainage area =
1.290 ac
Curve number
Basin Slope =
0.0 %
Hydraulic length
Tc method =
User
Time of conc. (Tc)
Total precip. =
3.39 in
Distribution
Storm duration =
24 hrs
Shape factor
Composite (Area/CN) = [(0.900 x 74) + (0.350 x 80)] / 1.290
Q (cfs)
2.00
1.00
M
O'Reilly Pre -Development
Hyd. No. 1 -- 2 Year
120 240 360 480 600 720 840 960
Hyd No. 1
Thursday, 07 / 25 / 2019
= 1.455 cfs
= 732 min
= 6,022 cuft
= 76*
= 0 ft
= 30.00 min
= Type II
= 484
Q (cfs)
2.00
1.00
0.00
1080 1200 1320 1440 1560
Time (min)

Hydrograph
Report
17
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 2
Family Dollar Pre -developed
Hydrograph type
= SCS Runoff
Peak discharge
= 3.767 cfs
Storm frequency
= 2 yrs
Time to peak
= 719 min
Time interval
= 1 min
Hyd. volume
= 8,528 cuft
Drainage area
= 1.330 ac
Curve number
= 83*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 3.39 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) _ [(0.520 x 98) + (0.810 x 74)] / 1.330
Family Dollar Pre -developed
Q (cfs) Hyd. No. 2 -- 2 Year Q (cfs)
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. 2 Time (min)

Hydrograph Report
18
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd. No. 3
O'Reilly DA #1
Hydrograph type
= SCS Runoff
Peak discharge
Storm frequency
= 2 yrs
Time to peak
Time interval
= 1 min
Hyd. volume
Drainage area
= 0.370 ac
Curve number
Basin Slope
= 0.0 %
Hydraulic length
Tc method
= User
Time of conc. (Tc)
Total precip.
= 3.39 in
Distribution
Storm duration
= 24 hrs
Shape factor
Composite (Area/CN) = [(0.230 x 98) + (0.140 x 80)] / 0.370
Q (cfs)
2.00
1.00
e
120
Hyd No. 3
O'Reilly DA #1
Hyd. No. 3 -- 2 Year
Thursday, 07 / 25 / 2019
= 1.591 cfs
= 717 min
= 3,376 cuft
= 91*
= 0 ft
= 5.00 min
= Type II
= 484
240 360 480 600 720 840 960 1080 1200
Q (cfs)
2.00
1.00
0.00
1320
Time (min)

Hydrograph
Report
19
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd. No. 4
O'Reilly DA #2
Hydrograph type = SCS Runoff Peak discharge
Storm frequency = 2 yrs Time to peak
Time interval = 1 min Hyd. volume
Drainage area = 0.920 ac Curve number
Basin Slope = 0.0 % Hydraulic length
Tc method = User Time of conc. (Tc)
Total precip. = 3.39 in Distribution
Storm duration = 24 hrs Shape factor
Thursday, 07 / 25
= 3.120 cfs
= 718 min
= 6,346 cuft
= 84*
= 0 ft
= 5.00 min
= Type II
= 484
/ 2019
Composite (Area/CN) _ [(0.390 x 98) + (0.530 x 74)] / 0.920
O'Reilly DA #2
Q (cfs) Hyd. No. 4 -- 2 Year
4.00
Q (cfs)
4.00
3.00
3.00
2.00
2.00
1.00
1.00
0.00
0 120
— Hyd No.
240 360 480 600 720 840 960 1080
4
0.00
1200 1320 1440
Time (min)

20
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 5
Family Dollar Developed
Hydrograph type
= SCS Runoff
Peak discharge
= 5.882 cfs
Storm frequency
= 2 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 12,604 cuft
Drainage area
= 1.330 ac
Curve number
= 92*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 3.39 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) _ [(0.870 x 98) + (0.460 x 80)] / 1.330
Family Dollar Developed
Q (cfs) Hyd. No. 5 -- 2 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
— Hyd No. 5 Time (min)

21
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 6
Combined PreDeveloped
Hydrograph type = Combine Peak discharge = 4.622 cfs
Storm frequency = 2 yrs Time to peak = 720 min
Time interval = 1 min Hyd. volume = 14,550 cuft
Inflow hyds. = 1, 2 Contrib. drain. area = 2.620 ac
Combined PreDeveloped
Q (cfs) Hyd. No. 6 -- 2 Year Q (cfs)
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
Time (min)
— Hyd No. 6 — Hyd No. 1 Hyd No. 2

Hydrograph
Report
22
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 7
Combined to Rear Ponds
Hydrograph type
= Combine
Peak discharge
= 10.58 cfs
Storm frequency
= 2 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 22,326 cuft
Inflow hyds.
= 3, 4, 5
Contrib. drain. area
= 2.620 ac
Combined to Rear Ponds
Q (cfs) Hyd. No. 7 -- 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
Time (min)
Hyd No. 7 Hyd No. 3 Hyd No. 4 Hyd No. 5

23
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 8
Routed Sand Filter
Hydrograph type
= Reservoir
Peak discharge
= 7.330 cfs
Storm frequency
= 2 yrs
Time to peak
= 721 min
Time interval
= 1 min
Hyd. volume
= 14,079 cuft
Inflow hyd. No.
= 7 - Combined to Rear Ponds
Max. Elevation
= 860.17 ft
Reservoir name
= Sed Sand
Max. Storage
= 9,832 cuft
Storage Indication method used.
Q (cfs)
12.00
10.00
M
M
4.00
2.00
Routed Sand Filter
Hyd. No. 8 -- 2 Year
Q (cfs)
12.00
10.00
M.
. ��
4.00
2.00
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
Hyd No. 8 Hyd No. 7 Total storage used = 9,832 cuff

Hydrograph
Report
24
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc.
v2020
Thursday, 07 / 25 / 2019
Hyd. No. 9
Routed Rear Pond
Hydrograph type
= Reservoir
Peak discharge
= 2.480 cfs
Storm frequency
= 2 yrs
Time to peak
= 730 min
Time interval
= 1 min
Hyd. volume
= 14,078 cuft
Inflow hyd. No.
= 8 - Routed Sand Filter
Max. Elevation
= 855.26 ft
Reservoir name
= <New Pond>
Max. Storage
= 2,578 cuft
Storage Indication method used
Routed Rear Pond
Q (cfs) Hyd. No. 9 -- 2 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
Time (min)
— Hyd No. 9 - Hyd No. 8 Total storage used = 2,578 cuff

25
Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
2.842
1
731
11,412
------
------
------
O'Reilly Pre -Development
2
SCS Runoff
6.450
1
719
14,801
------
------
------
Family Dollar Pre -developed
3
SCS Runoff
2.452
1
717
5,354
------
------
------
O'Reilly DA #1
4
SCS Runoff
5.237
1
717
10,886
------
------
------
O'Reilly DA #2
5
SCS Runoff
8.965
1
717
19,776
------
------
------
Family Dollar Developed
6
Combine
8.220
1
720
26,213
1, 2,
------
------
Combined Pre Developed
7
Combine
16.65
1
717
36,016
3, 4, 5,
------
------
Combined to Rear Ponds
8
Reservoir
15.70
1
719
27,769
7
860.80
10,880
Routed Sand Filter
9
Reservoir
5.678
1
727
27,768
8
857.54
8,117
Routed Rear Pond
Lexington NC 7-22-19.gpw
Return Period: 10 Year
Thursday, 07 / 25 / 2019

Hydrograph
Report
26
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 1
O'Reilly Pre -Development
Hydrograph type
= SCS Runoff
Peak discharge
= 2.842 cfs
Storm frequency
= 10 yrs
Time to peak
= 731 min
Time interval
= 1 min
Hyd. volume
= 11,412 cuft
Drainage area
= 1.290 ac
Curve number
= 76*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 30.00 min
Total precip.
= 4.88 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) _ [(0.900 x 74) + (0.350 x 80)] / 1.290
O'Reilly Pre -Development
Q (cfs) Hyd. No. 1 -- 10 Year Q (cfs)
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. 1 Time (min)

27
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 2
Family Dollar Pre -developed
Hydrograph type =
SCS Runoff
Peak discharge
= 6.450 cfs
Storm frequency =
10 yrs
Time to peak
= 719 min
Time interval =
1 min
Hyd. volume
= 14,801 cuft
Drainage area =
1.330 ac
Curve number
= 83*
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 10.00 min
Total precip. =
4.88 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.520 x 98) + (0.810 x 74)] / 1.330
Q (cfs)
7.00
• Me
5.00
4.00
3.00
2.00
1.00
Q (cfs)
7.00
9.1 ••
5.00
4.00
3.00
2.00
1.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
— Hyd No. 2 Time (min)

28
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 3
O'Reilly DA #1
Hydrograph type
= SCS Runoff
Peak discharge
= 2.452 cfs
Storm frequency
= 10 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 5,354 cuft
Drainage area
= 0.370 ac
Curve number
= 91 *
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 4.88 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.230 x 98) + (0.140 x 80)] / 0.370
Q (cfs)
3.00
2.00
1.00
e
O'Reilly DA #1
Hyd. No. 3 -- 10 Year
120 240 360 480 600 720 840 960
Hyd No. 3
Q (cfs)
3.00
2.00
1.00
T� 0.00
1080 1200
Time (min)

29
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 4
O'Reilly DA #2
Hydrograph type
= SCS Runoff
Peak discharge
= 5.237 cfs
Storm frequency
= 10 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 10,886 cuft
Drainage area
= 0.920 ac
Curve number
= 84*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 4.88 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.390 x 98) + (0.530 x 74)] / 0.920
Q (cfs)
6.00
5.00
4.00
3.00
2.00
1.00
O'Reilly DA #2
Hyd. No. 4 -- 10 Year
Q (cfs)
6.00
5.00
4.00
3.00
2.00
1.00
0.00 ' ' ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320
— Hyd No. 4 Time (min)

30
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 5
Family Dollar Developed
Hydrograph type
= SCS Runoff
Peak discharge
= 8.965 cfs
Storm frequency
= 10 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 19,776 cuft
Drainage area
= 1.330 ac
Curve number
= 92*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 4.88 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.870 x 98) + (0.460 x 80)] / 1.330
Q (cfs)
10.00
4.00
2.00
e
120 240
Hyd No. 5
Family Dollar Developed
Hyd. No. 5 -- 10 Year
360 480 600 720 840
Q (cfs)
10.00
We
4.00
2.00
0.00
960 1080 1200
Time (min)

Hydrograph Report
31
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 6
Combined PreDeveloped
Hydrograph type = Combine
Peak discharge
= 8.220 cfs
Storm frequency = 10 yrs
Time to peak
= 720 min
Time interval = 1 min
Hyd. volume
= 26,213 cuft
Inflow hyds. = 1, 2
Contrib. drain. area
= 2.620 ac
Combined PreDeveloped
Q (cfs) Hyd. No. 6 -- 10 Year Q (cfs)
10.00 10.00
8.00 8.00
6.00 6.00
4.00 4.00
2.00JtL 2.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
Hyd No. 6 Hyd No. 1 Hyd No. 2

Hydrograph
Report
32
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 7
Combined to Rear Ponds
Hydrograph type
= Combine
Peak discharge
= 16.65 cfs
Storm frequency
= 10 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 36,016 cuft
Inflow hyds.
= 3, 4, 5
Contrib. drain. area
= 2.620 ac
Combined to Rear Ponds
Q (cfs) Hyd. No. 7 -- 10 Year Q (cfs)
18.00 18.00
15.00 15.00
12.00 12.00
9.00 9.00
6.00 6.00
Id
3.00 3.00
0.00 JL0.00
0 120 240 360 480 600 720 840 960 1080 1200
Time (min)
Hyd No. 7 Hyd No. 3 Hyd No. 4 Hyd No. 5

33
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 8
Routed Sand Filter
Hydrograph type
= Reservoir
Peak discharge
= 15.70 cfs
Storm frequency
= 10 yrs
Time to peak
= 719 min
Time interval
= 1 min
Hyd. volume
= 27,769 cuft
Inflow hyd. No.
= 7 - Combined to Rear Ponds
Max. Elevation
= 860.80 ft
Reservoir name
= Sed Sand
Max. Storage
= 10,880 cuft
Storage Indication method used.
Routed Sand Filter
Q (cfs) Hyd. No. 8 -- 10 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
Time (min)
Hyd No. 8 Hyd No. 7 Total storage used = 10,880 cult

34
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 9
Routed Rear Pond
Hydrograph type
= Reservoir
Peak discharge
= 5.678 cfs
Storm frequency
= 10 yrs
Time to peak
= 727 min
Time interval
= 1 min
Hyd. volume
= 27,768 cuft
Inflow hyd. No.
= 8 - Routed Sand Filter
Max. Elevation
= 857.54 ft
Reservoir name
= <New Pond>
Max. Storage
= 8,117 cuft
Storage Indication method used.
Q (cfs)
18.00
15.00
12.00
M
M
3.00
Routed Rear Pond
Hyd. No. 9 -- 10 Year
Q (cfs)
18.00
15.00
12.00
•10
. ��
c10
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
Hyd No. 9 Hyd No. 8 Total storage used = 8,117 cuff

35
Hydrograph Summary Report Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Hyd.
No.
Hydrograph
type
(origin)
Peak
flow
(cfs)
Time
interval
(min)
Time to
Peak
(min)
Hyd.
volume
(cuft)
Inflow
hyd(s)
Maximum
elevation
(ft)
Total
strge used
(cuft)
Hydrograph
Description
1
SCS Runoff
5.160
1
731
20,604
------
------
------
O'Reilly Pre -Development
2
SCS Runoff
10.64
1
719
25,004
------
------
------
Family Dollar Pre -developed
3
SCS Runoff
3.753
1
717
8,444
------
------
------
O'Reilly DA #1
4
SCS Runoff
8.529
1
717
18,226
------
------
------
O'Reilly DA #2
5
SCS Runoff
13.62
1
717
30,932
------
------
------
Family Dollar Developed
6
Combine
13.97
1
720
45,608
1, 2,
------
------
Combined Pre Developed
7
Combine
25.90
1
717
57,601
3, 4, 5,
------
------
Combined to Rear Ponds
8
Reservoir
24.73
1
719
49,354
7
861.37
11,810
Routed Sand Filter
9
Reservoir
10.88
1
725
49,353
8
860.54
15,379
Routed Rear Pond
Lexington NC 7-22-19.gpw
Return Period: 100 Year
Thursday, 07 / 25 / 2019

36
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 1
O'Reilly Pre -Development
Hydrograph type =
SCS Runoff
Peak discharge
= 5.160 cfs
Storm frequency =
100 yrs
Time to peak
= 731 min
Time interval =
1 min
Hyd. volume
= 20,604 cuft
Drainage area =
1.290 ac
Curve number
= 76*
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 30.00 min
Total precip. =
7.16 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.900 x 74) + (0.350 x 80)] / 1.290
Q (cfs)
6.00
5.00
4.00
3.00
2.00
1.00
O'Reilly Pre -Development
Hyd. No. 1 -- 100 Year
Q (cfs)
6.00
5.00
4.00
3.00
2.00
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)

37
Hydrograph
Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019
by Autodesk, Inc. v2020
Thursday, 07 / 25
/ 2019
Hyd. No. 2
Family Dollar Pre -developed
Hydrograph type
= SCS Runoff
Peak discharge
= 10.64 cfs
Storm frequency
= 100 yrs
Time to peak
= 719 min
Time interval
= 1 min
Hyd. volume
= 25,004 cuft
Drainage area
= 1.330 ac
Curve number
= 83*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 7.16 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) _ [(0.520 x 98) + (0.810 x 74)] / 1.330
Family
Dollar Pre -developed
Q (cfs)
Hyd. No. 2 -- 100 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
Hyd No.
2
Time
(min)

38
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 3
O'Reilly DA #1
Hydrograph type
= SCS Runoff
Peak discharge
= 3.753 cfs
Storm frequency
= 100 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 8,444 cuft
Drainage area
= 0.370 ac
Curve number
= 91 *
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 7.16 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) _ [(0.230 x 98) + (0.140 x 80)] / 0.370
O'Reilly DA #1
Q (cfs) Hyd. No. 3 -- 100 Year Q (cfs)
4.00 4.00
3.00 3.00
2.00 2.00
1.00 1.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200
— Hyd No. 3 Time (min)

39
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 4
O'Reilly DA #2
Hydrograph type
= SCS Runoff
Peak discharge
= 8.529 cfs
Storm frequency
= 100 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 18,226 cuft
Drainage area
= 0.920 ac
Curve number
= 84*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 7.16 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.390 x 98) + (0.530 x 74)] / 0.920
Q (cfs)
10.00
4.00
2.00
e
O'Reilly DA #2
Hyd. No. 4 -- 100 Year
Q (cfs)
10.00
We
4.00
2.00
' ' i 0.00
120 240 360 480 600 720 840 960 1080 1200 1320
Hyd No. 4 Time (min)

40
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Hyd. No. 5
Family Dollar Developed
Hydrograph type
= SCS Runoff
Peak discharge
= 13.62 cfs
Storm frequency
= 100 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 30,932 cuft
Drainage area
= 1.330 ac
Curve number
= 92*
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 5.00 min
Total precip.
= 7.16 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Composite (Area/CN) = [(0.870 x 98) + (0.460 x 80)] / 1.330
Q (cfs)
14.00
12.00
10.00
M. 11
4.00
2.00
e
Family Dollar Developed
Hyd. No. 5 -- 100 Year
Q (cfs)
14.00
12.00
10.00
4.00
2.00
1 0.00
120 240 360 480 600 720 840 960 1080 1200
Hyd No. 5 Time (min)

Hydrograph Report
41
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 6
Combined PreDeveloped
Hydrograph type = Combine
Peak discharge
= 13.97 cfs
Storm frequency = 100 yrs
Time to peak
= 720 min
Time interval = 1 min
Hyd. volume
= 45,608 cuft
Inflow hyds. = 1, 2
Contrib. drain. area
= 2.620 ac
Combined PreDeveloped
Q (cfs) Hyd. No. 6 -- 100 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
Time (min)
Hyd No. 6 Hyd No. 1 Hyd No. 2

Hydrograph
Report
42
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 7
Combined to Rear Ponds
Hydrograph type
= Combine
Peak discharge
= 25.90 cfs
Storm frequency
= 100 yrs
Time to peak
= 717 min
Time interval
= 1 min
Hyd. volume
= 57,601 cuft
Inflow hyds.
= 3, 4, 5
Contrib. drain. area
= 2.620 ac
Combined to Rear Ponds
Q (cfs) Hyd. No. 7 -- 100 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
Time (min)
— Hyd No. 7 — Hyd No. 3 Hyd No. 4 Hyd No. 5

43
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 8
Routed Sand Filter
Hydrograph type
= Reservoir
Peak discharge
= 24.73 cfs
Storm frequency
= 100 yrs
Time to peak
= 719 min
Time interval
= 1 min
Hyd. volume
= 49,354 cuft
Inflow hyd. No.
= 7 - Combined to Rear Ponds
Max. Elevation
= 861.37 ft
Reservoir name
= Sed Sand
Max. Storage
= 11,810 cuft
Storage Indication method used.
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
Routed Sand Filter
Hyd. No. 8 -- 100 Year
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
0.00 10.00
0 120 240 360 480 600 720 840 960 1080 1200 1320
Time (min)
— Hyd No. 8 Hyd No. 7 Total storage used = 11,810 cult

44
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
Thursday, 07 / 25 / 2019
Hyd. No. 9
Routed Rear Pond
Hydrograph type
= Reservoir
Peak discharge
= 10.88 cfs
Storm frequency
= 100 yrs
Time to peak
= 725 min
Time interval
= 1 min
Hyd. volume
= 49,353 cuft
Inflow hyd. No.
= 8 - Routed Sand Filter
Max. Elevation
= 860.54 ft
Reservoir name
= <New Pond>
Max. Storage
= 15,379 cuft
Storage Indication method used.
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
Routed Rear Pond
Hyd. No. 9 -- 100 Year
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
— Hyd No. 9 — Hyd No. 8 Total storage used = 15,379 cult

45
Hydraflow Rainfall Report
Hydraflow Hydrographs Extension for Autodesk0 Civil 3DO 2019 by Autodesk, Inc. v2020 Thursday, 07 / 25 / 2019
Return
Period
Intensity -Duration -Frequency Equation Coefficients (FHA)
(Yrs)
B
D
E
(N/A)
1
0.0000
0.0000
0.0000
--------
2
67.0277
12.7000
0.8729
--------
3
0.0000
0.0000
0.0000
--------
5
68.0041
12.5000
0.8280
--------
10
69.9702
12.5000
0.8066
--------
25
0.0000
0.0000
0.0000
--------
50
0.0000
0.0000
0.0000
--------
100
47.1993
9.1000
0.6554
--------
File name: Lexington NC.IDF
Intensity = B / (Tc + D)^E
Return
Period
Intensity Values (in/hr)
(Yrs)
6 min
10
16
20
26
30
36
40
46
60
66
60
1
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
2
5.46
4.39
3.69
3.19
2.82
2.53
2.30
2.11
1.95
1.81
1.69
1.59
3
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
5
6.36
5.16
4.37
3.81
3.38
3.05
2.78
2.56
2.37
2.22
2.08
1.96
10
6.95
5.68
4.83
4.22
3.76
3.40
3.11
2.87
2.66
2.49
2.34
2.21
25
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
50
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
100
8.33
6.83
5.86
5.18
4.67
4.27
3.95
3.68
3.45
3.26
3.09
2.94
Tc = time in minutes. Values may exceed 60.
Precip. file name: Sample.pcp
Storm
Rainfall Precipitation Table (in)
Distribution
1-yr
2-yr
3-yr
6-yr
10-yr
26-yr
60-yr
100-yr
SCS 24-hour
2.80
3.39
0.00
3.30
4.88
5.77
6.80
7.16
SCS 6-Hr
0.00
1.80
0.00
0.00
2.60
0.00
0.00
4.00
Huff-1 st
0.00
1.55
0.00
2.75
4.00
5.38
6.50
8.00
Huff-2nd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-3rd
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-4th
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Huff-Indy
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
Custom
0.00
1.75
0.00
2.80
3.90
5.25
6.00
7.10

M t A lhL
,im
SEDIMENT BASIN
CALCULATIONS

This structure is intended for less than 3 years of use. Structures intended
for more than 3 years of use should be desinged as permanent structures.
User Input Data
Calculated Value
Reference Data
Designed By:
Checked By:
Company:
Project Name:
Project No.:
Dylan Gideon Date: 1/6/2020
Aaron Hargrave Date: 1 /6/2020
MO Anderson Engineering, Inc.
O'Reilly Auto Lexington NC
DAVID-2020-015
Site Location (City/Town) Lexington, NC
Sediment Basin Id. 101
Total Drainage Area (acres) 2.62
- rv-1, 1. p mk flow, (D,a, for the basin drainage arr. i,-3ppe�adiz S.O=
Q 10 (cfs)
Step 2. Determine any site limitations for the sediment pool elevation, emergency
spillway or top of the dam.
Minimum pool elevation (ft)
Maximum pool elevation (ft)
13.5 Assume Family Dollar
Releases at Pre-Dev Rate
, We

Step 3. Determine basin volumes:
• Compute minimum volume required (1800 ft3/acre disturbed)_
• Specify sediment cleanout level to be marked on riser (one-half the design
volume referenced to the top of the riser) and sediment storage area to be
cleared after the dam is built.
Disturbed acreage (ac)
Min Volume (ft)
Sediment cleanout elevation (ft)
Sediment Storage Area
Step 4_ Detenume area and shape of basin:
• Check length/Width ratio (should be 2:1 to 6:1)_
3, 000 sqft
• Compute the basin surface area at principal spillway elevation_
• Check the ratio of basin surface area to peak inflow rate (should be greater
than or equal to 435 ft�/cfs)_ Employ diversions with additional traps and
basins to reduce area drained_
Determine barrel capacity required for site conditions (minimum capacity for Op
is the ?-year peak runoff, a2.
Length/width ratio
Is length/width ratio between 2-6?
Basin surface area @ principal spillway (ft)
Ratio: basin surface area/Q10
Is ratio >= 435 ft2/cfs?
0
YES, PROCEED
YES
oil
6000 Both Ponds
444.4444444

Step 5. Determine the principal spillway discharge capacity_
• The combined capacities of the principal and emergency spillways must be
at least the 10-_year peak flow for the entire watershed of the basin.
• The principal spillway is analyzed for three possible limiting flow qWs:
NVeir flow, Orifice flow. and Pipe flow. The principal spillway discharge
capacity is the smallest of these three flow rates. Discharges through a
skimmer should be disregarded during this computation. Weir, orifice and
pipe flow may be determined by the following equations:
1. Weir Flow: Q = CLHt.5
where:
Q = discharge in cubic feet per second (cfs)
C = weir coefficient. use 3.1 for corrugated metal pipe risers.
L = circumference of the riser in feet
H = head above riser crest in feet
Weir coefficient, C
Riser circumference, L (ft)
Head above riser crest, H (ft)
QW (cfs)
2. Orifice Flow: Q = CA (2gHr-3
where:
Q = discharge in cubic feet per second (cfs)
C = orifice coefficient, use C = 0.6 for corrugated metal pipe risers.
A = cross -sectional area of the riser pipe in square feet
g = acceleration due to gravity, 32.2 ft'sec-'
H = head above riser crest in feet
3
4
0.5
4.242640687
CcMP=3.1
Orifice coefficient, Co 0.6 Ccmp=0•6

Riser cross -sectional area, A (ft2)
Accleration due to gravity, g (ft/s2)
Head above riser crest, H (ft)
Discharge, Qo (cfs)
7gh 0.5
3. Pipe Flow: C.1 = a L 1 + Km + Kp L
0.083
32.2
1
0.399643061
where:
Q = discharge in cubic feet per second (cfs)
a = cross -sectional area of the barrel in square feet
g = acceleration due to gravity, 32.2 fl/ser'
h = head above the centerline of the outlet end of the barrel
Km = coefficient of minor losses, can be assumed to be 1.0 for
most principal spillway systems
L = barrel length in feet
Kp = pipe friction coefficient:
_ 50 8 a r K, values for
di4J3 common size-o ipe_)
n = Manning's coefficient of roughness, use n = 0.025 for
corrugated metal pipe
n = 0.015 for reinforced concrete pipe
di = inside diameter of the barrel in inches
Select riser and barrel dimensions so that the riser has a cross -sectional area
at least 1.5 times that of the barrel. Spillway hydraulics are improved by
maximizing weir flow and minimizing orifice flow_ See Table 8.07b for
recommended riser/barrel proportions.
Barrel diameter (ft) 2
Barrel cross -sectional area, a (ft2) 3.1

Accleration due to gravity, g (ft/s2)
Head above outlet end of barrel, h (ft)
Minor loss coefficieint, Km
Barrel length, L (ft)
Mannings coeffienct of roughness, n
Inside diameter of barrel, d; (in)
Pipe friction coefficient, Kp
Discharge, Qo (cfs)
RISER
Select trail riser and barrel dimensions. Use the weir. orifice and pipe flow
equations to determine if the 2-year peak discharge is passed without activating
the emergency spillway. Determine riser size from Figure 8.07b. Check the
head and stage requirements. If the design stage is too high_ choose larger
dimensions and recalculate. As a minimum. set the elevation of the riser at the
same elevation as the top of the sediment pool. A riser height 2 to 5 times the
barrel diameter is recommended. Select the type of trash guard.
Select a dewatering device. If a skimmer is used. refer to the manufacturers
dewatering data, or Table 6.64.b.
Step 6. Design antiseep collar_
Ensure that antiseep collars are no closer than 2 ft from a pipe joint. Collar
must project at least 1.5 ft from the pipe. Indicate watertight connections.
Step 7. Design antiflotation block.
Determine the weight of water displaced by the empty riser, and design a
block with buoyant weight 1.1 times the weight of water displaced.
Weight of water displaced by the empty riser
Buoyant weight
Step S. Design outlet.
Determine discharge velocity from the barrel. Design outlet protection to
32.2
1
1.0 Km=1.0 (typical)
34
0.025 ncmp=0.025
48
0.01823 Table 8.07a
15.57646473 17.8269813
2000
2200
Table 8.07b
nRCP=0.015

assure stable conditions. Riprap placement is usually necessary (Appendix
8.06).
Discharge velocity, V (ft/s)
See Appendix 8.06 for riprap sizing, if necessary
Step 9. Design emergency spillway.
• Determine the required capacity for the emergency spillway as
Qe = Q10 — QF (Qp 2 02)
• Fr $ o le 8 80 or Table 8.07f. select the width and depth of the outlet.
dep o o conditions. In general. the wider bottom widths and
lower slopes are preferred to minim exit elocities at supercritical
flow-
• An acceptable alternative is the use of the weir equation
Q = CLHI.5
Where this option is used. the maximum value of C should be 2.8, L
is the bottom width of the spillway at the crest, and H is the depth of
flow above the spillway crest in feet. Note: Manning's channel equation
should not be used to size the spillway crest. However. it should be used
to design the outlet channel below- the spillway crest.
• The total of the emergency and principle spillway capacities must equal
or exceed the required 10-year peak discharge.
• Set the elevation of the crest of the emergency spillway a minimum of 1
foot above the crest of the riser -
OPTION 1
Q10
Qp
Emergency spillway capacity, Qe (cfs)
4.958142714 5.67450438
13.5
0.399643061
13.10035694
Qp + Qe 13.5
Table 8.07c
Table 8.07d
Weir coefficient, C
Bottom width of spillway cress
Depth of flow above spillway i
Emergency spillway capacity,

Does (Qp + Qe) equal or exceed Q10?
YES, PROCEED
Step 10. Spillway appsoach ;ectron_
Adjust the spillway alignment so that the control section and outlet section
are straight. The entrance width should be 1.5 times the width of the control
section with a smooth transition to the width of the control section. Approach
chansteI should slope toward the reservoir no less than 2%-
Width of control section (ft)
Width of entrance (ft)
Slope of approach channel (%)
Is width of the entrance section 1.5xcontrol section
width? YES, PROCEED
Is approach channel >/= 2%? YES, PROCEED
Step 11. Spillway control section
• Locate the control section in the spillway near where it intersects the
extension of the centerline of the dam.
• Keep a level area to extend at least 20 ft upstream from the outlet end off'
the control section. to ensure a straight alignment.
• Side slopes should be 3:1.
Step 12. Design spillway exit section.
• Spillway exit should align with the control section and have the same
bottom width and side slopes.
• Slope should be sufficient to maintain supercritical flow, but make sure it
does not create erosive velocities for site conditions. (Stay within slope
ranges in appropriate design tables.)
• Extend the exrt channel to a point where the water may be released without
A--_ --
10
4
45

aamage.
Step 13. Size the embankment.
• Set the design elevation of the top of the dam a minimum of 1 ft above the
water surface for the design flow in the emergency- spillway.
• Constructed height should be 10' o greater than the design to allow for
settlement.
• Base top width on the design height.
• Set side slopes 2.5:1 or flatter.
• Determine depth of cutoff trench from site borings. It should extend to a
stable. tight soil layer (a minimum of ? ft deep).
• Select borrow site -the emergency spillway cut will provide a significant
amount of fill_
Step 14. Erosion control
• Locate and design diversions to protect embankment and spillway
(Practice Standards and Specifications: 6.20, Temporary Diversions)_
• Select surface protection measures to control erosion (Practice Standards
and Specifications: 6.10, Temporary Seeding; 6.14, Mulching; and 6.15,
Riprap).
• Select groundcover for emergency spillway to provide protection for
design flow velocity and site conditions_ Ripmp stone over geotextile
fabric may be required in erodible soils or when the spillway is not in
undisturbed soils.
Step 15. Safely.

• Constiuct a fence and install warning siggns as needed.

Calculate Skimmer Size for FairCloth Skimmer®
Basin Volume in Cubic Feet 8,080 Cu. Ft
Days to Drain* 2 Days
Skimmer Size 2.5 Inch
Orifice Radius 1.0 Inch[es]
Orifice Diameter 2.0 Inch[es]
n NC assume 3 days to drain If no results maximum flow rate for a single skimmer is exceeded. More than one skimmer may be
Estimate Volume of Basin Length Width
Top of water surface in feet Feet VOLUME 0 Cu. Ft.
Bottom dimensions in feet Feet
Depth in feet 3 Feet
Updated 5/1/19

M t A lhL
,im
RIP -RAP CALCULATIONS

User Input Data
Calculated Value
Reference Data
Designed By:
Checked By:
Company:
Project Name:
Project No.:
Dylan Gideon Date:
Aaron Hargrave Date:
MO Anderson Engineering, Inc.
O'Reilly Auto Lexington NC
SW4190901
Site Location (City/Town) Lexington
Culvert Id. 1
Total Drainage Area (acres) 2.62
Step 1. Determine the tallwater depth from channel characteristics below the
pipe outlet for the desiut capacity of the pipe. If the tailwater depth is less
than half the outlet pipe diameter, it is classified niit-itnum tailwater condition.
If it is greater than half the pipe diameter. it is classified maximum condition.
Pipes that outlet onto wide fiat areas with no defined channel are assumed
to have a mitlsnnun tailwater condition unless reliable flood stage elevations
shoo- othenviw.
Outlet pipe diameter, Do (in.) 24
Tailwater depth (in.) 6
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 6 Discharge from
1 /6/2020 1

Velocity (ft./s)
2.5 Detention Outflow
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b, and determine d5o riprap size and minimum apron length
(L). The d., size is the median stone size in a well -graded riprap apron.
Step 3. Determine apron width at the pipe outlet, the apron shape, and the
apron width at the outlet end from the same figure used in Step 2 _
Minimum TW
Figure 8.06a
Riprap d50, (ft.)
Minimum apron length, La (ft.)
Apron width at pipe outlet (ft.) 6
Apron shape Parallelagram
Apron width at outlet end (ft.) 12
step 4. De rernune the maximtun stone diameter:
drrQU = 1.5 x dso
Minimum TW
Max Stone Diameter, dmax (ft.) 1.5
Step 5. Determne the apron thickness:
Apron thickness =1.5 x d,;,.
Maximum TW
Figure 8.06b
1 1
10 10
6
Parallelagram
6
Maximum TW
1.5
Minimum TW Maximum TW
Apron Thickness(ft.) 2.25 2.25
Step 6. Fit the riprap apron to the site by making it level for the nnnimtun
length, La, from Figure 8.06a or Figure 8.06b. Extend the apron farther
downstream and along channel banks until stability is assured_ Keep the

apron as straight as possible and align it with the floe of the receiving stream_
Make any necessary alignment bends near the pipe outlet so that the entrance
into the receiving stream is straight.
Some locations may require lining of the entire channel cross section to assure
stability_
It may be necessary to increase the size of riprap where protection of the
channel side slopes is necessary (Appendix 8.05). Where overfalls exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8.