Baucom's Nursery Phase 3 - 180414.300 Stormwater Calculations

Storm wa ter Calculations
For
Baucom's Nursery Phase 3
3200 Flowes Store Road East
Concord, NC 28025
CESI PROJECT NO. 180414.300
Owner: Baucom's Nursery Company
Owner Representative: Gary Baucom, President
P.O. Box 560008
Charlotte, NC 28256
P.704.506.7349
gcb(d)baucomnursery.com
Preparer's Name: Kate Underwood, PE
CESI
NCBELS Corporate License Number C-0263
PO Box 268
Concord, NC 28026-0268
P.704.786.5404
F.704.786.7454
M.980.234.7500
kateunderwood@)cesicgs.com
AR
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033470 =
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05/06/2019

STORMWATER TABLE OF CONTENTS
1. Summary of Results
2. Pre -Development Calculations
2.1 Pre Development Nodal Diagram
2.2 Pre -Development Drainage Areas
3. Post -Development Calculations
3.1 Post -Development Nodal Diagram
3.2 Post -Development Drainage Areas
3.3 Wet Detention Pond Design Calculations
4. Routing Results
5. Riprap Calculations
6. Appendix
Ftzz, ', y
033470
05/06/2019

Baucom's Nursery Phase 3
CESI Job No. 180414.300
Stormwater Calculations
Existing Conditions:
The project is located in Cabarrus County, North Carolina at the southeast corner of the intersection of
Flowes Store Road East and John White Road. The soils on site are a mixture of enon sandy loam,
hydrologic soil group C, iredell loam, hydrologic soil group D, chewacla sandy loam, hydrologic soil group
D, and Mecklenburg loam, hydrologic soil group C. The site is located in the Yadkin river basin and drains
to Anderson Creek, Stream index 13-17-13, classification C. There is a jurisdictionally important
intermittent stream on site.
The project consists of the construction of a series of open planting areas, gravel roads, and a wet pond
stormwater control measure (SCM). Stormwater conveyance will be provided by a storm drain system.
The SCM is designed to treat both phase 3A and 3B of development. The proposed SCM will then outfall
to the intermittent stream on the site. The current owner of the SCM, Baucom's Nursery Company will
retain ownership of the SCM and maintenance responsibility.

SUMMARY OF RESULTS
PRE -DEVELOPMENT DRAINAGE AREA SUMMARY
DRAINAGE I.D. AREA (AC.)
A 115.94
POST DEVELOPMENT DRAINAGE AREA SUMMARY
DRAINAGE I.D.
AREA (AC.)
1 (POND)
80.06
2
35.89
PRE -DEVELOPMENT RUNOFF RESULTS
PRE -DEVELOPMENT
IYR/24HR
IOYR/24HR
100YR/24HR
A
64.42
220.74
428.28
POST -DEVELOPMENT RUNOFF RESULTS
POST -DEVELOPMENT
IYR/24HR
IOYR/24HR
100YR/24HR
1
89.29
232.37
406.10
2
16.97
61.02
120.20
WET POND - 1
4.52
48.86
111.57
OUTFALL 99-S
17.59
95.48
225.11
POST DEVELOPMENT PEAK -STAGE RESULTS
IYR/24HR
IOYR/24HR
100YR/24HR
WP1 (TOD = 582.5)
1 579.44
580.37
581.57

Pre Development Nodal Diagram

Pre -Development Drainage Area A
BASIN PRE DA A CURVE NUMBER CALC.
AREA (AC.)
HYDROLOGIC SOILD GROUP
LAND USE
CONDITION
CN
39.30
B/C/D
WOODS/BRUSH
GOOD
67
73.64
B/C/D
PASTURE/MEADOWS
75%GC
73
6.00
B/C/D
]AIPERVIOUS
N/A
98
TOTAL AREA=115.94 AC.
COMPOSITE CN
72
tc Calculation
L
up
down
slope
n
er
pipe size (in) area (sf)
MI
Sheet Flow
100
728.00
723.08
4.92%
040
;perime
Woods: Light Underb
Shallow Concentrated
3415
723.08
569.75
4.49%
Un-Paved
CALCULATI ED TC =
TC USED IN CALCULATION =
31.00 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
31.00 MIN MINIMUM TC OF 10 MINUTES
Roughness Coefficients (Manning's N) for Sheet Flow
Smooth Surfaces (Concrete, asphalt, gravel, or bare soil)
0.011
Fallow (no residue)
0.05
Cultivated Soils, Residue — 20 %
0.06
Cultivated Soils, Residue > 20 %
0.17
Grass: Short Praire
0.15
Grass: Dense Grass
0.24
Grass: Bermuda Grass
0.41
Range: Natural
0.13
Woods: Light Underbrush
0 4
Woods: Dense Underbrush
0.8
Roughness Coefficients (Manning's N) for Channel Flow
Excavated Channels: Short Grass 0.027

TR55 Tc Worksheet
Hyd. No. 1
Pre DA-A
Description
Sheet Flow
Manning's n-value
Flow length (ft)
Two-year 24-hr precip. (in)
Land slope (%)
Travel Time (min)
Shallow Concentrated Flow
Flow length (ft)
Watercourse slope (%)
Surface description
Average velocity (ft/s)
Travel Time (min)
Channel Flow
X sectional flow area (sqft)
Wetted perimeter (ft)
Channel slope (%)
Manning's n-value
Velocity (ft/s)
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
A
B
C
= 0.400
0.011
0.011
= 100.0
0.0
0.0
= 3.50
0.00
0.00
= 4.92
0.00
0.00
= 14.32 +
0.00 +
0.00
= 3415.00
0.00
0.00
= 4.49
0.00
0.00
= Unpaved
Paved
Paved
=3.42
0.00
0.00
= 16.65 +
0.00 +
0.00
= 0.00
0.00
0.00
= 0.00
0.00
0.00
= 0.00
0.00
0.00
= 0.015
0.015
0.015
=0.00
0.00
0.00
Flow length (ft) ({0})0.0 0.0 0.0
Travel Time (min) = 0.00 + 0.00 + 0.00
Total Travel Time, Tc..............................................................................
Totals
= 14.32
= 16.65
= 0.00
31.00 min

Post Development Nodal Diagram

Post -Development Drainage Area 1
BASIN POST DA A-1 CURVE NUMBER CALC.
AREA (AC.)
HYDROLOGIC SOILD GROUP
LAND USE
CONDITION
CN
11.32
B/C/D
WOODS/BRUSH
FAIR
67
37.15
B/C/D
PASTURE/MEADOWS
75%GC
73
24.00
B/C/D
R,4PERVIOUS
N/A
98
TOTAL AREA=80.06 AC.
COMPSITE CN
80
tc Calculation
L
up
down
slope
n
pipe size (in) area (sf) per me er
Sheet Flow
100
728.00
723.08
4.92 %
0.40
Woods: Light Underbrush
Shallow Concentrated
2672
723.08
568.00
5.80%
Un-Paved
CALCULATI ED TC =
TC USED IN CALCULATION =
25.80 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
25.00 MIN MINIMUM TC OF 10 MINUTES
Roughness Coefficients (Manning's N) for Sheet Flow
Smooth Surfaces (Concrete, asphalt, gravel, or bare soil)
0.011
Fallow (no residue)
0.05
Cultivated Soils, Residue — 20 %
0.06
Cultivated Soils, Residue > 20 %
0.17
Grass: Short Praire
0.15
Grass: Dense Grass
0.24
Grass: Bermuda Grass
0.41
Range: Natural
0.13
Woods: Light Underbrush
0 4
Woods: Dense Underbrush
0.8
Roughness Coefficients (Manning's N) for Channel Flow
Excavated Channels: Short Grass
0.027

TR55 Tc Worksheet
Hyd. No. 2
Post DA-1
Description
Sheet Flow
Manning's n-value
Flow length (ft)
Two-year 24-hr precip. (in)
Land slope (%)
Travel Time (min)
Shallow Concentrated Flow
Flow length (ft)
Watercourse slope (%)
Surface description
Average velocity (ft/s)
Travel Time (min)
Channel Flow
X sectional flow area (sqft)
Wetted perimeter (ft)
Channel slope (%)
Manning's n-value
Velocity (ft/s)
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® 2019 by Autodesk, Inc. v2020
A
B
C
= 0.400
0.011
0.011
= 100.0
0.0
0.0
= 3.50
0.00
0.00
= 4.92
0.00
0.00
= 14.32 +
0.00 +
0.00
= 2672.00
0.00
0.00
= 5.80
0.00
0.00
= Unpaved
Paved
Paved
=3.89
0.00
0.00
= 11.46 +
0.00 +
0.00
= 0.00
0.00
0.00
= 0.00
0.00
0.00
= 0.00
0.00
0.00
= 0.015
0.015
0.015
=0.00
0.00
0.00
Flow length (ft) ({0})0.0 0.0 0.0
Travel Time (min) = 0.00 + 0.00 + 0.00
Total Travel Time, Tc..............................................................................
Totals
= 14.32
= 11.46
= 0.00
25.79 min

Drainage Area
Impervious Area
Impervious
Estimated Avg. Depth
SA/DA Ratio
SA Required
SA Required
SA Provided
SA Provided
Pool Depth Provided
Rv=0.05+0.9*IA
WQv = 3630 * RD * Rv * A
Rv
WQv
Pond Calculations
80.06 ac Double Interpolated SA/DA Ratio
24.00 ac
30%
3 ft
1.17
0.94 ac
40803 sf
221,110.00 sf
5.08 ac
4.50 ft
Imp %
Pool Depth (ft)
3.00
3.50
4.00
20%
0.84
0.77
0.69
30%
1.17
1.06
0.94
30%
1.51
1.38
1.24
Table Custom
SIMPLE METHOD PER NCDENR BMP MANUAL SECTION 3.3.1
Runoff coefficient [storm runoff (in)/storm rainfall (in)],
Rv = unitless
Impervious fraction [impervious portion of drainage area
IA = (ac)/drainage area (ac)], unitless
Volume of runoff that must be controlled for the design storm
**V = (ft)
Rp = Design storm rainfall depth (in) (Typically, 1.0" or 1.5")
A = Watershed area (ac)
0.32 (1 inch)
92,939 (1 inch)
Permament Pool
VPP 811687.75 cf Depth Shelf 1 ft
Vshelf 3457.50 cf Perm PP 2305 ft
A BS 212651.00 sf Width Self si 3 ft
Depth= 4.50 ft
Calc Avg. Depth 3.80 Must be greater than Estimated
Water Quality Elevation
Permanent Pool Elevation
Orifice Size
579.00
578.50
Treatment Vol
92,939
CF
92,939
Draw Down Time
2
DAYS
5
Draw Down Time
172,800
sec
432,000
Flow (Q)
0.538
CFS
0.215
Cd
0.6
0.6
H/3
0.167
ft
0.167
Area of orifice
0.274
sf
0.109
Dia.
7.08
in
4.48
Draw Down Time:
Draw Down Rate:
2.05 days
0.53 cfs
Orifice: 7
<--------- Plate Hole: 7
Center Offset: 0

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Permit No.
(to be provided by DWQ)
III. REQUIRED ITEMS CHECKLIST
Please indicate the page or plan sheet numbers where the supporting documentation can be found. An incomplete submittal package will
result in a request for additional information. This will delay final review and approval of the project. Initial in the space provided to
indicate the following design requirements have been met. If the applicant has designated an agent, the agent may initial below. If a
requirement has not been met, attach justification.
Pagel Plan
nitials. I Sheet No.
%J_ C300, C301,
& C302
1. Plans (1" - 50' or larger) of the entire site showing:
Design at ultimate build -out,
Off -site drainage (if applicable),
Delineated drainage basins (include Rational C coefficient per basin),
Basin dimensions,
Pretreatment system,
High flow bypass system,
Maintenance access,
Proposed drainage easement and public right of way (ROW),
Overflow device, and
Boundaries of drainage easement.
C310 2. Partial plan (1" = 30' or larger) and details for the wet detention basin showing:
Outlet structure with trash rack or similar,
Maintenance access,
Permanent pool dimensions,
Forebay and main pond with hardened emergency spillway,
Basin cross-section,
Vegetation specification for planting shelf, and
Filter strip.
C310 3. Section view of the wet detention basin (1" = 20' or larger) showing:
Side slopes, 3:1 or lower,
Pretreatment and treatment areas, and
Inlet and outlet structures.
C310
4
C001
C�4 INCLUDED
C�,�AS BUILTS
_w N/A
�) `-INCLUDED
IN CALCS
4. If the basin is used for sediment and erosion control during construction, clean out of the basin is specified
on the plans prior to use as a wet detention basin.
5. A table of elevations, areas, incremental volumes & accumulated volumes for overall pond and for forebay,
to verify volume provided.
6. A construction sequence that shows how the wet detention basin will be protected from sediment until the
entire drainage area is stabilized.
7. The supporting calculations.
8. A copy of the signed and notarized operation and maintenance (0&M) agreement.
9. A copy of the deed restrictions (if required).
10. A soils report that is based upon an actual field investigation, soil borings, and infiltration tests. County
soil maps are not an acceptable source of soils information.
Form SW401-Wet Detention Basin-Rev.9-4/18/12 Part Pond Required Items Checklist, Page 9 of 14

User Input Data
Calculated Value
Reference Data
Designed By: SMP Date: 5/2/2019
Checked By: KWU
Company: CESI
Project Name: Baucom's Nursery Ph 3
Project No.: 180414.300
Site Location (City/Town) Concord, NC
Culvert Id. FES-1
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe_ If the tailwater depth is less
than half the outlet pipe diameter. it is classified minimum tailwater condition.
If it is greater than half the pipe diameter. it is classified maximum condition.
Pipes that outlet onto 'wide flat areas with no defined channel are assumed
to have a minimum tailwater condition unless reliable flood stage elevations
shoe otherwise.
Outlet pipe diameter, Do (in.) 42
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 131.10 See 10 year Hydraulic Gradeline Calculation
results
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b. and determine dso 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 Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 1.1
Minimum apron length, La (ft.) 34
Apron width at pipe outlet (ft.) 10.5 10.5
Apron shape Trapezoidal
Apron width at outlet end (ft.) 38 4
Step 4. Deternine the maximum stone diameter:
d.w = 1.5 x dso
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 1.65 0
Step '_55. Determine the apron thickness:
Apron thickness = 1.5 x d,,_, Use class 2 riprap
Apron Thickness(ft.)
Minimum TW Maximum TW
2.475 0
RIP RAP CLASS
MINIMUM
MIDRANGE
MAXIMUM
A
2 IN
0.17 FT
4 IN
0.33 FT
6 IN 0.5 FT
B
5 IN
0.42 FT
8 IN
0.67 FT
12 IN 1 FT
1
5 IN
0.42 FT
10 IN
0.83 FT
17 IN 1.42 FT
2
1 9 IN
0.75 FT
14 IN
1.17 FT
23 IN 1.92 FT
Step 6. Fit the riprap apron to the site by making it level for the minimtun
length, Ld, 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 flow 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). Vv here overfills exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8_

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Rev.1193 8.06.3

User Input Data
Calculated Value
Reference Data
Designed By: SMP Date: 5/2/2019
Checked By: KWU
Company: CESI
Project Name: Baucom's Nursery Ph 3
Project No.: 180414.300
Site Location (City/Town) Concord, NC
Culvert Id. FES-2
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe_ If the tailwater depth is less
than half the outlet pipe diameter. it is classified minimum tailwater condition.
If it is greater than half the pipe diameter. it is classified maximum condition.
Pipes that outlet onto 'wide flat areas with no defined channel are assumed
to have a minimum tailwater condition unless reliable flood stage elevations
shoe otherwise.
Outlet pipe diameter, Do (in.) 36
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 65.11 See 10 year Hydraulic Gradeline Calculation
results
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b. and determine dso 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 Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 0.7
Minimum apron length, La (ft.) 23
Apron width at pipe outlet (ft.) 9 9
Apron shape Trapezoidal
Apron width at outlet end (ft.) 26 3
Step 4. Deternine the maximum stone diameter:
d.w = 1.5 x dso
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 1.05 0
Step '_55. Determine the apron thickness:
Apron thickness = 1.5 x d,,_, Use class 1 riprap
Apron Thickness(ft.)
Minimum TW Maximum TW
1.575 0
RIP RAP CLASS
MINIMUM
MIDRANGE
MAXIMUM
A
2 IN
0.17 FT
4 IN
0.33 FT
6 IN 0.5 FT
B
5 IN
0.42 FT
8 IN
0.67 FT
12 IN 1 FT
1
5 IN
0.42 FT
10 IN
0.83 FT
17 IN 1.42 FT
2
1 9 IN
0.75 FT
14 IN
1.17 FT
23 IN 1.92 FT
Step 6. Fit the riprap apron to the site by making it level for the minimtun
length, Ld, 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 flow 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). Vv here overfills exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8_

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Rev.1193 8.06.3

User Input Data
Calculated Value
Reference Data
Designed By: SMP Date: 5/2/2019
Checked By: KWU
Company: CESI
Project Name: Baucom's Nursery Ph 3
Project No.: 180414.300
Site Location (City/Town) Concord, NC
Culvert Id. FES-4
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe_ If the tailwater depth is less
than half the outlet pipe diameter. it is classified minimum tailwater condition.
If it is greater than half the pipe diameter. it is classified maximum condition.
Pipes that outlet onto 'wide flat areas with no defined channel are assumed
to have a minimum tailwater condition unless reliable flood stage elevations
shoe otherwise.
Outlet pipe diameter, Do (in.) 36
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 44.46 See 10 year Hydraulic Gradeline Calculation
results
Step 2. Based on the tailwater conditions determined in step 1. enter Figure
8.06a or Figure 8.06b. and determine dso 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 Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 0.6
Minimum apron length, La (ft.) 20
Apron width at pipe outlet (ft.) 9 9
Apron shape Trapezoidal
Apron width at outlet end (ft.) 23 3
Step 4. Deternine the maximum stone diameter:
d.w = 1.5 x dso
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 0.9 0
Step '_55. Determine the apron thickness:
Apron thickness = 1.5 x d,,_, Use class B riprap
Apron Thickness(ft.)
Minimum TW Maximum TW
1.35 0
RIP RAP CLASS
MINIMUM
MIDRANGE
MAXIMUM
A
2 IN
0.17 FT
4 IN
0.33 FT
6 IN 0.5 FT
B
5 IN
0.42 FT
8 IN
0.67 FT
12 IN 1 FT
1
5 IN
0.42 FT
10 IN
0.83 FT
17 IN 1.42 FT
2
1 9 IN
0.75 FT
14 IN
1.17 FT
23 IN 1.92 FT
Step 6. Fit the riprap apron to the site by making it level for the minimtun
length, Ld, 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 flow 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). Vv here overfills exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8_

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Rev.11'93 8.06.3

User Input Data
Calculated Value
Reference Data
Designed By: SMP Date: 5/2/2019
Checked By: KWU
Company: CESI
Project Name: Baucom's Nursery Ph 3
Project No.: 180414.300
Site Location (City/Town) Concord, NC
Culvert Id. HW 3
Step 1. Determine the tailwater depth from channel characteristics below the
pipe outlet for the design capacity of the pipe_ If the tailwater depth is less
than half the outlet pipe diameter. it is classified minimum tailwater condition.
If it is greater than half the pipe diameter. it is classified maximum condition.
Pipes that outlet onto wide flat areas with no defined channel are assumed
to have a minimum tailwater condition unless reliable flood stage elevations
shoe otherwise.
Outlet pipe diameter, Do (in.) 24 (THREE 24" PIPES)
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 48.86 See 10 year Stormwater routing
Step ?. Based on the tailwater conditions determined in step 1_ enter Figure
8.06a or Figure 8.06b, and determine d50 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 Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 1.2
Minimum apron length, La (ft.) 39
Apron width at pipe outlet (ft.) 6 6
Apron shape Trapezoidal
Apron width at outlet end (ft.) 41 2
Step 4. Deternine the maximum stone diameter:
d.w = 1.5 x dso
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 1.8 0
Step '_55. Determine the apron thickness:
Apron thickness = 1.5 x d,,_, Use class 2 riprap
Apron Thickness(ft.)
Minimum TW Maximum TW
2.7 0
RIP RAP CLASS
MINIMUM
MIDRANGE
MAXIMUM
A
2 IN
0.17 FT
4 IN
0.33 FT
6 IN 0.5 FT
B
5 IN
0.42 FT
8 IN
0.67 FT
12 IN 1 FT
1
5 IN
0.42 FT
10 IN
0.83 FT
17 IN 1.42 FT
2
1 9 IN
0.75 FT
14 IN
1.17 FT
23 IN 1.92 FT
Step 6. Fit the riprap apron to the site by making it level for the minimtun
length, Ld, 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 flow 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). Vv here overfills exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8_

3),
Outlet IW ■ Do + La
Ripe i
diameter (Do)
La �a
i Nater c 0.5Do
�n�t�`y� I r 51 �41.
50 100
Discharge (ft3/sec)
48.86 cfs
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full, minimum tailwater condition (Tw < 0.5 diameter).
Rev.1193 8.06.3

Appendix

CHARLOTTE-MECKLENBURG STORM WATER DESIGN MANUAL
Table 2-12
Runoff Curve Numbers'
description
Cover type and hydrologic condition
Fully developed urban areas (vegetation established)
Open space (lawns, parks, golf courses, cemeteries, etc.) 3L
Poor condition (grass cover < 50%)............................
Fair condition (grass cover 50%to 75%)....................
Good condition (grass cover > 75%)...........................
Impervious areas:
Paved parking lots, roofs, driveways, etc.
(excluding right-of-way) .....................................
Streets and roads:
Paved; curbs and storm sewers (excluding
right -of -way) .......................................................
Paved; open ditches (including right-of-way) ....
Gravel (including right-of-way) ..........................
Dirt (including right-of-way) ..............................
Urban districts:
Commercial and business ............................................
Industrial.....................................................................
Residential districts by average lot size:
1/8 acre or less (town houses) .....................................
1/4 acre........................................................................
1/3 acre........................................................................
1/2 acre........................................................................
1 acre...........................................................................
2 acres.........................................................................
Agricultural Lands
Pasture, grassland or range (continuous for age for grazing)4
Poor hydrologic condition ...........................................
Fair hydrologic condition ............................................
Good hydrologic condition .........................................
Woods
Poor hydrologic condition ...........................................
Fair hydrologic condition ............................................
Good hydrologic conditi
Developing urban areas
Newly graded areas
(pervious areas only, no vegetation) ..........
Curve numbers for
-----hydrologic soil group-----
Averagepercent
impervious area zi A Lj 'C D
68
79
86
89
49
69
79
84
39
61
74
80
98
98
98
98
98
98
98
98
83
89
92
93
76
85
89
91
72
82
87
89
85
89
92
94
95
72
81
88
91
93
65
77
85
90
92
38
61
75
83
87
30
57
72
81
86
25
54
70
80
85
20
51
68
79
84
12
46
65
77
82
68
79
86
89
49
69
79
84
39
61
74
80
45 66 77 83
36 60 a 7-3 79
30
77 - - 24
Average runoff condition, and Ia = 0.2S.
The average percent impervious area shown was used to develop the composite CN's. Other assumptions are as follows: impervious areas
area directly connected to the drainage system, impervious areas have a CN of 98, and pervious areas are considered equivalent to open
space in good hydrologic condition.
CN's shown are equivalent to those of pasture. Composite CN's may be computed for other combinations of open space cover type.
Poor: Forest litter, small trees, and brush are destroyed by heavy grazing or regular burning.
Fair: Woods are grazed but not burned, and some forest litter covers the soil.
Good: Woods are protected from grazing, and litter and brush adequately cover the soil.
Source: 210-VI-M-55, Second Edition, June 1986
2-18

9/18/2018 NC Surface Water Classifications
NC Surface Water Classifications _lick a stream for more information '?
F
.,Parr.h OtrPam Name nr I n o
Water Classifications:
Stream Index:
13-17-13
Stream Name:
Anderson Creek
Description:
From source to Rocky River
Classification:
C
Date of Class.:
June 30, 1973
River Basin:
Yadkin Pee -Dee
What does this Class. mean?
More info
Zoom to
County cf Cabarrus, �Stat
-80.535 35.309 Degrees
https://ncdenr. maps.arcgis.com/apps/webappviewer/index.html?id=6el 25ad7628f494694e259c80dd64265 1 /1

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Hydrologic Soil Group—Cabarrus County, North Carolina
Baucom's Nursery Phase 3
Hydrologic Soil Group
Map unit symbol
Map unit name
Rating
Acres in AOI
Percent of AOI
CcB2
Cecil sandy clay loam, 2
B
15.7
7.3%
to 8 percent slopes,
moderately eroded
CcD2
Cecil sandy clay loam, 8
B
15.5
7.3%
to 15 percent slopes,
moderately eroded
ChA
Chewacla sandy loam, 0
B/D
3.3
1.6%
to 2 percent slopes,
frequently flooded
CuB2
Cullen clay loam, 2 to 8
B
12.6
5.9%
percent slopes,
moderately eroded
EnB
Enon sandy loam, 2 to 8
C
31.6
14.8%
percent slopes
EnD
Enon sandy loam, 8 to
C
5.2
2.4%
15 percent slopes
IdB
Iredell loam, 2 to 6
C/D
55.6
26.1 %
percent slopes
MeB
Mecklenburg loam, 2 to
C
39.5
18.5%
8 percent slopes
SfB
Sedgefield sandy loam,
C/D
32.2
15.1 %
2 to 8 percent slopes
TaB
Tarrus silt loam, 2 to 8
B
1.8
0.8%
percent slopes
TaD
Tarrus silt loam, 8 to 15
B
0.3
0.1 %
percent slopes
Totals for Area of Interest
213.2
100.0%
USDA Natural Resources Web Soil Survey 1/9/2019
Conservation Service National Cooperative Soil Survey Page 3 of 4

Hydrologic Soil Group—Cabarrus County, North Carolina
Baucom's Nursery Phase 3
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.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff.- None Specified
Tie -break Rule: Higher
USDA Natural Resources Web Soil Survey 1/9/2019
Conservation Service National Cooperative Soil Survey Page 4 of 4