SWA000099_200658.000 2. Stormwater Calculations Report_20210407

Storm wa ter Calculations
For
Old Charlotte Arrow Disposal
1750 Old Charlotte Road
Concord, NC 28027
CESI PROJECT NO. 200658.000
Client: Arrow Disposal Properties, Inc.
Client Representative: Jerry Frakes
P.O. Box 472
Harrisburg, NC 28075
P.704-467-3876
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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.704.902.6169
kateunderwood(a)cesicas.com
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03/30/2021

1. Narrative and Summary of Results
2. Impervious Area Summary
3. Pre -Development Calculations
4.1 Pre Development Nodal Diagram
4.2 Pre -Development Drainage Areas
4. Post -Development Calculations
5.1 Post -Development Nodal Diagram
5.2 Post -Development Drainage Areas
5.3 Sand Filter Calculations
5. Hydraflow Results
6. Riprap Calculations
7. Appendix
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Arrow Disposal Old Charlotte Rd
CESI Job No. 200658.000
Stormwater Calculations
Existing Conditions:
The project is located in Cabarrus County, North Carolina northwest from the intersection of Stough Rd
and NC 49. The soil on site is cecil sandy clay loam, hydrologic soil group B. The site is located in the Yadkin
river basin and drains to Coddle Creek, Stream index 13-17-6-8, classification C. There are no
jurisdictionally important intermittent streams on site.
The project consists of the construction of a series of open planting areas, gravel roads, and a sand filter
stormwater control measure (SCM). Stormwater conveyance will be provided by a storm drain system.
The SCM is designed to treat both all phases of development. The proposed SCM will then outfall to the
intermittent stream on the site. The current owner of the SCM, Arrow Disposal Properties INC, will retain
ownership of the SCM and maintenance responsibility.

SUMMARY OF RESULTS
PRE -DEVELOPMENT DRAINAGE AREA SUMMARY
DRAINAGE AREA
AREA (ACRES)
TC
CN
Pre DA-A
3.106
10.00
56.0
Pre DA-B
0.128
10.00
56.0
Pre DA-C
0.810
10.00
56.0
Total
4.044
POST DEVELOPMENT DRAINAGE AREA SUMMARY
DRAINAGE AREA
AREA (ACRES)
TC
CN
Post DA-A
3.635
10.00
78.2
Post DA-B
0.265
10.00
61.0
Post DA-C
0.150
10.00
61.0
Total
4.050
PRE -DEVELOPMENT RUNOFF RESULTS (CFS)
DRAINAGE AREA
1 YR/24 HR
10 YR/24 HR
100 YR/24 HR
Pre DA-A
0.26
4.34
11.46
Pre DA-B
0.01
0.18
0.47
Pre DA-C
0.07
1.13
2.99
Outfall NW
0.26
4.34
11.46
Outfall NE
Outfall SE
0.01
0.18
0.47
0.07
1.13
2.99
POST -DEVELOPMENT RUNOFF RESULTS (CFS)
DRAINAGE AREA
1 YR/24 HR
10 YR/24 HR
100 YR/24 HR
Post DA-A
5.52
14.77
26.17
Post DA-B
0.08
0.52
1.19
Post DA-C
0.08
0.29
0.67
Sand Filter
0.09
2.88
21.20
Outfall NW
0.12
3.08
22.85
POST DEVELOPMENT PEAK -STAGE RESULTS
1 YR/24 HR
10 YR/24 HR
100 YR/24 HR
WP1 T.O.B. = 585.00
583.08
583.91
584.80
Freeboard
1.92
1.09
0.20

Impervious Area Summary
Pre -Development
Total Existing On -Site inpervious area - SQ FT
Post -Development
Total on -site impervious area' 113,140 SQ FT
On -site area required to be treated by SCMZ 113,140 SQ FT
Total area treated by SCM 158,347 SQ FT
'Does not include impervious area within proposed ROW
2Equal to the post -development impervious area minus the Pre -development

Pre Development Nodal Diagram
PRE DA-A
OUTFALL
NW

Pre -Development Drainage Area A
Land use
Condition
Hydrologic
Area (SF)
Area (Acres)
Cn
Weighted Cn
Soil Group
Brush ( 50% to 75% ground cover)
N/A
I B
1 135,295
1 3.106
1 56
56.0
135,295 3.106 56.0
perimeter
tc Calculation
L
up
down
slope
n
pipe size (in)
area (sf)
(ft)
Sheet Flow
100
636.00
617.47
18.53%
0.13
Range: Natural
Shallow Concentrated
410.09
617.47
593.00
5.97%
Un-Paved
CALCULATED TC = 5.20 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
TC USED IN CALCULATION = 10.00 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

Pre -Development Drainage Area B
Land use
Condition
Hydrologic
Area (SF)
Area (Acres)
Cn
Weighted Cn
Soil Group
Brush ( 50% to 75% ground cover)
N/A
B
5,580
0.128
56
56.0
5,580 0.128 56.0
Perimeter
tc Calculation
L
up
down
slope
n
pipe size (in)
area (sf)
(ft)
Sheet Flow
24.22
636.00
623.60
51.20%
0.13
Range: Natural
CALCULATED TC = 0.70 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
TC USED IN CALCULATION = 10.00 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

Pre -Development Drainage Area C
Hydrologic
Land use
Condition
Soil Group
Area (SF)
Area (Acres)
Cn
Weighted Cn
Brush 50% to 75% ground cover
N/A
I B
1 35,282
1 0.810
56
56.0
35,282 0.810 56.0
perimeter
tc Calculation
L
up
down
slope
n
pipe size (in)
area (sf)
(ft)
Sheet Flow
100
633.16
626.36
6.80%
0.13
Range: Natural
Shallow Concentrated
103.96
626.36
620.00
6.12%
Un-Paved
CALCULATED TC = 5.60 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
TC USED IN CALCULATION = 10.00 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

Post Development Nodal Diagram

Post -Development Drainage Area A
Land use
Condition
Hydrologic
Area (SF)
Area (Acres)
Cn
Weighted Cn
Soil Group
Meadow
N/A
B
-
-
58
0.0
Open Space
good
B
44,915
1.031
61
17.3
Impervious:
N/A
B
304.55
0.007
98
0.2
Curbs & Strom Sewers
Impervious:
N/A
B
113,127
2.597
85
60.7
Gravel
158,347 3.635 78.2
tc Calculation
L
up
down
slope
n
pipe size (in)
area (sf)
Perimeter
(ft)
Sheet Flow
100
631.00
620.00
11.00%
0.01
Smooth Surfaces
Shallow Concentrated
502.30
620.00
585.00
6.97%
0.01
Smooth Surfaces
Pipe
33.29
585.00
581.00
12.01%
0.01
15 1.23 3.93
CALCULATED TC = 2.10 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
TC USED IN CALCULATION = 10.00 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

Post -Development Drainage Area B
Land use
Condition
Hydrologic
Soil Group
Area (SF)
Area (Acres)
Cn
Weighted Cn
Open Space
Good
I B
11,537
0.265
61
61.0
11,537 0.265 61.0
perimeter
tc Calculation
L
up
down
slope
n
pipe size (in)
area (sf)
(ft)
Sheet Flow
100
631.00
620.00
11.00%
0.13
Ran e: Natural
CALCULATED TC = 2.10 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
TC USED IN CALCULATION = 10.00 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

Post -Development Drainage Area C
Land use
Condition
Hydrologic
Soil Group
Area (SF)
Area (Acres)
Cn
Weighted Cn
Open Space
good
B
6,547
0.150
61
61.0
Meadow
N/A
B
-
-
58
0.0
6,547 0.150 61.0
Perimeter
tc Calculation
L
up
down
slope
n
pipe size (in)
area (sf)
(ft)
Sheet Flow
61.98
631.00
620.00
17.75%
0.01
Smooth Surfaces
CALCULATED TC = 0.30 MIN SEE HYDRAFLOW TR-55 TC CALCULATION SHEET
TC USED IN CALCULATION = 10.00 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

Sand Filter 1 Calculations
Discrete NRCS Curve Number Method for Runoff Depth
S = 1000 _ 10
CN
Where: S = Maximum retention after rainfall begins (in)
CN = Curve number (unitless)
Attenuation Requirements: 1-year, 24 hour
10-year, 24 hour
(P + D.85} WhereQ' Runoff depth [in)
Emergency Spillway Requirement: 100-year, 24 hour
: =
P = Rainfall depth (in) Minimum Required Freeboard:
a Me BZy/-1
P
1 Inch
Non -coastal county
CN
98.0
DCIA - Impervious
A
113,127 sf
Impervious Drainage Area in SF
S
0.20 Inches
Maximum retention after rainfall begins
Q*
0.79 Inches
Runoff Depth
Q*
7,456 cfs
Runoff Volume
For Remainder:
P
1 Inch
Non -coastal county
CN
58.0
CN for Remainder of the Drainage Area
A
0 sf
Remainder of Drainage Area in SF
S
7.24 Inches
Maximum retention after rainfall begins
Q*
0.03 Inches
Runoff Depth
Q*
0 cfs
Runoff Volume
Total Design Volume
7,456 cf
Discounted Design Volume
5,592 cf
For Sand Filters apply 0.75 design volume
discount
Design Ponding Depth
11
21
31
41
51
6
Surface Area Reauired
1 5.5921
2.7961
1.8641
1.3981
1.1181
932
Top of Sand Filter Elevation
581.00
Top of Design Treatment Volume
583.00
Design Ponding Depth
2.00
(= Design Treatment Volume Elevation -
Bottom of Sand Filter)
Design Treatment Volume
12,788
Total Volume of sand filter ponding depth
Sand Filter Surface Area
5,039
Surface Area of sand filter Provided
Minimum Surface Area Required
2,796
(= Discounted Design Volume divided by
Design Ponding Depth)
Minimum Design Draw Down
2 in/hr
Design Ponding Depth
24.00 in
Draw Down Time
12 hours
Minimum Flow
0.129 cfs
(= Dicounted Design Volume divided by Draw
Down Time in seconds)
Capacity of 6" underdrain at 0.5%
0.470 cfs
Therefore meets required capacity

Forebay Chamber
Elevation
Pond Area
Depth
Total Incremental
Volume
Total Cumulative
Volume
581.00
2,435
N/A
N/A
N/A
582.00
3,042
1.0
2,739
2,739
583.00
3,711
1.0
3,377
6,115
Sand Filter Chamber
Elevation
Pond Area
Depth
Total Incremental
Volume
Total Cumulative
Volume
581.00
2,604
N/A
N/A
N/A
582.00
3,319
1.0
2,962
2,962
583.00
4,103
1.0
3,711
6,673
Total Combined Treatment Storage
Elevation
Pond Area
Depth
Total Incremental
Volume
Total Cumulative
Volume
581.00
5,039
N/A
N/A
N/A
582.00
6,361
1.0
5,700
5,700
583.00
7,814
1.0
7,088
12,788
584.00
5,502
1.0
6,658
19,446
585.00
6,534
1.0
6,018
25,464

PONDING ELEVATIONS
FREEBOARD
100 YEAR/ 24 HOUR ELEVATION 584.80 0.20
10 YEAR/ 24 HOUR ELEVATION 583.91 1.09
1 YEAR/ 24 HOUR ELEVATION 583.08 1.92
WATER QUALITY/PONDING ELEVATION 583.00
OUTLET STRUCTURE DETAILS
RIM ELEVATION 584.00
SLOT WEIR ELEVATION (D) 583.00
SLOT WEIR WIDTH (D) 1.00
OUTLET STRUCTURE SIZE 2.00' X 3.00'
STRUCTURE FOOTING DETAILS (K)
FOOTING LENGTH 6.00
FOOTING WIDTH 6.00
FOOTING DEPTH 1.25
SAND FILTER DETAILS
TOP
OF
BANK ELEVATION
585.00
TOP
OF
RIP RAP WEIR ELEVATION
584.50
TOP
OF
GRAVEL/GRASS
581.00
TOP
OF
SAND FILTER MEDIA
580.50
MINIMUM
BOTTOM OF SAND FILTER MEDIA
578.50

WP DS1 CESI Land Development Services
JOB NO.: 200658.000BY: INBIL
P.O. Box 268
DATE: 3/16/2021 P.M: Concord, NC 28026
REVISED: I FLOATATION CALCULATIONS
Calculations Given Data
Standard Footing Assumptions
Density of Concrete
160 Ibs/ft^3
1. Footing base to be 1 ft. wider than structure
on all sides.
Density of Water
62.4 Ibs/ft^3
Safety Factor S.F.
2
Outlet Structure Weight, W(s) = (w+2(^2*h-w^2*(h-t) x D(c)
Displaced Water Weight, W(w) = (w + 2t)^2 x D(w) x h
Required Base Weight, W(b) = (W(w) x S.F.) - W(s)
Required Footing Volume, V(0 = W(b) / Dc-Dw
where, w = outlet box inside dimension, ft.
t = structure wall thickness, ft.
h = height of structure, ft.
D(c)= density of concrete, 1bs/ft^3
D(w)= density of water, /bs/ft^3
S.F.= safety factor
WDP 1 Outlet Structure
Structure Dimensions
Object Weights
Elevation at bottom of structure =
681.00
Elevation at top of structure =
686.00
Height of structure, h =
4.00 ft.
Outlet Structure Weight, W(s) =
4069 Ibs
Structure wall thickness, t =
6 in.
Displaced Water Weight, W(w) =
3068 Ibs
Average outlet box inside dimension, w =
2.6 ft.
Re 'd Base Weight, W(b) =
2046 Ibs
Required Footing Volume, V(fr) =
23 cf
Standard Footing Length, L =
6.00 ft.
Provided Footing Volume, V(fp) =
46 cf
Standard Footing Width, W =
6.00 ft.
Footing Check
okay
Minimum Footing Depth, D =
1.00 ft.
Footing Size to be used.
Length =
Width =
Depth =
6.00 ft.
6.00 ft.
1.25 ft.

Hydraflow Results

Watershed Model Schematic Hydraflow Hydrographs Extension forAutodesk® Civil 3D® by Autodesk, Inc. v2021
8
Project: 200658.000 Stormwater Calcs.gpw Friday, 03 / 26 / 2021

Hydrograph Return Period Recap d raflow Hydrographs Extension for Autodesk@ Civil 3D@ by Autodesk, Inc. v2021
Hyd.
Hydrograph
Inflow
Peak Outflow (cfs)
Hydrograph
No.
type
hyd(s)
Description
(origin)
1 -yr
2 -yr
3-yr
6-yr
10-yr
26-yr
60-yr
100-yr
1
SCS Runoff
------
0.256
-------
-------
-------
4.341
-------
9.021
11.46
Pre DA-A (Pre Offsite NW)
2
SCS Runoff
------
0.011
-------
-------
-------
0.179
-------
0.372
0.472
Pre DA-B (Pre Offsite NE)
3
SCS Runoff
------
0.067
-------
-------
-------
1.132
-------
2.353
2.990
Pre DA-C (Pre Offsite SE)
4
SCS Runoff
------
5.517
-------
-------
-------
14.77
-------
22.49
26.17
Post DA-A
5
SCS Runoff
------
0.075
-------
-------
-------
0.519
-------
0.964
1.190
Post DA-B
6
SCS Runoff
------
0.043
-------
-------
-------
0.294
-------
0.545
0.674
Post DA-C
7
Reservoir
4
0.085
-------
-------
-------
2.875
-------
14.67
21.20
Post DA-A > SF-1
8
Combine
5,6,7
0.118
-------
-------
-------
3.078
-------
15.64
22.85
Post Offsite NW
Proj. file: 200658.000 Stormwater Calcs.gpw
Friday, 03 26 / 2021

Hydrograph Summary Report HydraflowHydrographsExtension for AutodeskOCivil 3DObyAutodesk,Inc. v2021
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
0.256
2
726
2,226
------
------
------
Pre DA-A (Pre Offsite NW)
2
SCS Runoff
0.011
2
726
92
------
------
------
Pre DA-B (Pre Offsite NE)
3
SCS Runoff
0.067
2
726
580
------
------
------
Pre DA-C (Pre Offsite SE)
4
SCS Runoff
5.517
2
722
14,554
------
------
------
Post DA-A
5
SCS Runoff
0.075
2
724
325
------
------
------
Post DA-B
6
SCS Runoff
0.043
2
724
184
------
------
------
Post DA-C
7
Reservoir
0.085
2
1440
1,760
4
583.08
13,328
Post DA-A > SF-1
8
Combine
0.118
2
724
2,270
5, 6, 7
------
------
Post Offsite NW
200658.000 Stormwater Calcs.gpw
Return Period: 1 Year
Friday, 03 / 26 / 2021

4
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 1
Pre DA-A (Pre Offsite NW)
Hydrograph type =
SCS Runoff
Peak discharge
= 0.256 cfs
Storm frequency =
1 yrs
Time to peak
= 726 min
Time interval =
2 min
Hyd. volume
= 2,226 cuft
Drainage area =
3.106 ac
Curve number
= 56
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 10.00 min
Total precip. =
2.90 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
Pre DA-A (Pre Offsite NW)
Hyd. No. 1 -- 1 Year
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

5
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 2
Pre DA-B (Pre Offsite NE)
Hydrograph type =
SCS Runoff
Peak discharge
= 0.011 cfs
Storm frequency =
1 yrs
Time to peak
= 726 min
Time interval =
2 min
Hyd. volume
= 92 cuft
Drainage area =
0.128 ac
Curve number
= 56
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 10.00 min
Total precip. =
2.90 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Q (cfs)
0.10
0.09
in e:
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
0
Pre DA-B (Pre Offsite NE)
Hyd. No. 2 -- 1 Year
Q (cfs)
0.10
0.09
e:
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
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® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 3
Pre DA-C (Pre Offsite SE)
Hydrograph type =
SCS Runoff
Peak discharge
= 0.067 cfs
Storm frequency =
1 yrs
Time to peak
= 726 min
Time interval =
2 min
Hyd. volume
= 580 cuft
Drainage area =
0.810 ac
Curve number
= 56
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 10.00 min
Total precip. =
2.90 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Q (cfs)
0.10
0.09
in e:
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
0
Pre DA-C (Pre Offsite SE)
Hyd. No. 3 -- 1 Year
Q (cfs)
0.10
0.09
e:
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 3 Time (min)

7
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 4
Post DA-A
Hydrograph type
= SCS Runoff
Peak discharge
= 5.517 cfs
Storm frequency
= 1 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 14,554 cuft
Drainage area
= 3.635 ac
Curve number
= 78.2
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 2.90 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
6.00
5.00
4.00
3.00
2.00
1.00
Post DA-A
Hyd. No. 4 -- 1 Year
Q (cfs)
6.00
5.00
4.00
3.00
2.00
1.00
0.00 ' 1J ' ' ' ' ' 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
— Hyd No. 4 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 5
Post DA-B
Hydrograph type
= SCS Runoff
Peak discharge
= 0.075 cfs
Storm frequency
= 1 yrs
Time to peak
= 724 min
Time interval
= 2 min
Hyd. volume
= 325 cuft
Drainage area
= 0.265 ac
Curve number
= 61
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 2.90 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
0.10
0.09
in e:
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
0
Post DA-B
Hyd. No. 5 -- 1 Year
Q (cfs)
0.10
0.09
e:
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 5 Time (min)

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 6
Post DA-C
Hydrograph type
= SCS Runoff
Peak discharge
= 0.043 cfs
Storm frequency
= 1 yrs
Time to peak
= 724 min
Time interval
= 2 min
Hyd. volume
= 184 cuft
Drainage area
= 0.150 ac
Curve number
= 61
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 2.90 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
0.10
0.09
in e:
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
0
Post DA-C
Hyd. No. 6 -- 1 Year
Q (cfs)
0.10
0.09
e:
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 6 Time (min)

10
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 7
Post DA-A > SF-1
Hydrograph type
= Reservoir
Peak discharge
= 0.085 cfs
Storm frequency
= 1 yrs
Time to peak
= 1440 min
Time interval
= 2 min
Hyd. volume
= 1,760 cuft
Inflow hyd. No.
= 4 - Post DA-A
Max. Elevation
= 583.08 ft
Reservoir name
= Sand Filter - 1
Max. Storage
= 13,328 cuft
Storage Indication method used.
Post DA-A > SF-1
Q (cfs) Hyd. No. 7 -- 1 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
0 240 480 720 960 1200 1440 1680 1920
Time (min)
— Hyd No. 7 Hyd No. 4 Total storage used = 13,328 cult

Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 8
Post Offsite NW
Hydrograph type
= Combine
Peak discharge
= 0.118 cfs
Storm frequency
= 1 yrs
Time to peak
= 724 min
Time interval
= 2 min
Hyd. volume
= 2,270 cuft
Inflow hyds.
= 5, 6, 7
Contrib. drain. area
= 0.415 ac
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
e
240 480 720
Hyd No. 8 Hyd No. 5
960 1200
Hyd No. 6
1440 1680
Hyd No. 7
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
1920v vv
Time (min)

Hydrograph Summary Report
12
Hydraflow Hydrographs Extension for Autodesk0 Civil 3DO by Autodesk, Inc. v2021
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
4.341
2
722
12,715
------
------
------
Pre DA-A (Pre Offsite NW)
2
SCS Runoff
0.179
2
722
524
------
------
------
Pre DA-B (Pre Offsite NE)
3
SCS Runoff
1.132
2
722
3,316
------
------
------
Pre DA-C (Pre Offsite SE)
4
SCS Runoff
14.77
2
720
38,304
------
------
------
Post DA-A
5
SCS Runoff
0.519
2
722
1,418
------
------
------
Post DA-B
6
SCS Runoff
0.294
2
722
803
------
------
------
Post DA-C
7
Reservoir
2.875
2
736
25,510
4
583.91
18,825
Post DA-A > SF-1
8
Combine
3.078
2
734
27,731
5, 6, 7
------
------
Post Offsite NW
200658.000 Stormwater Calcs.gpw
Return Period: 10 Year
Friday, 03 / 26 / 2021

Hydrograph
Report
13
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 1
Pre DA-A (Pre Offsite
NW)
Hydrograph type
= SCS Runoff
Peak discharge
= 4.341 cfs
Storm frequency
= 10 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 12,715 cuft
Drainage area
= 3.106 ac
Curve number
= 56
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 5.10 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Pre DA-A (Pre Offsite NW)
Q (cfs) Hyd. No. 1 -- 10 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
— Hyd No. 1 Time (min)

14
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 2
Pre DA-B (Pre Offsite NE)
Hydrograph type =
SCS Runoff
Peak discharge
= 0.179 cfs
Storm frequency =
10 yrs
Time to peak
= 722 min
Time interval =
2 min
Hyd. volume
= 524 cuft
Drainage area =
0.128 ac
Curve number
= 56
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 10.00 min
Total precip. =
5.10 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
Pre DA-B (Pre Offsite NE)
Hyd. No. 2 -- 10 Year
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)

Hydrograph Report
15
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Hyd. No. 3
Pre DA-C (Pre Offsite SE)
Hydrograph type =
SCS Runoff
Storm frequency =
10 yrs
Time interval =
2 min
Drainage area =
0.810 ac
Basin Slope =
0.0 %
Tc method =
User
Total precip. =
5.10 in
Storm duration =
24 hrs
Q (cfs)
2.00
1.00
M
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Pre DA-C (Pre Offsite SE)
Hyd. No. 3 -- 10 Year
120 240 360 480 600 720 840 960
Hyd No. 3
Friday, 03 / 26 / 2021
= 1.132 cfs
= 722 min
= 3,316 cuft
= 56
= 0 ft
= 10.00 min
= Type II
= 484
Q (cfs)
2.00
1.00
0.00
1080 1200 1320 1440 1560
Time (min)

Hydrograph
Report
16
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 4
Post DA-A
Hydrograph type
= SCS Runoff
Peak discharge
= 14.77 cfs
Storm frequency
= 10 yrs
Time to peak
= 720 min
Time interval
= 2 min
Hyd. volume
= 38,304 cuft
Drainage area
= 3.635 ac
Curve number
= 78.2
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 5.10 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Post DA-A
Q (cfs) Hyd. No. 4 -- 10 Year Q (cfs)
15.00 15.00
12.00 12.00
9.00 9.00
6.00 6.00
3.00 3.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
— Hyd No. 4 Time (min)

17
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 5
Post DA-B
Hydrograph type
= SCS Runoff
Peak discharge
= 0.519 cfs
Storm frequency
= 10 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 1,418 cuft
Drainage area
= 0.265 ac
Curve number
= 61
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 5.10 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
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
Post DA-B
Hyd. No. 5 -- 10 Year
Q (cfs)
1.00
0.90
I :1
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. 5 Time (min)

18
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 6
Post DA-C
Hydrograph type
= SCS Runoff
Peak discharge
= 0.294 cfs
Storm frequency
= 10 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 803 cuft
Drainage area
= 0.150 ac
Curve number
= 61
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 5.10 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
Post DA-C
Hyd. No. 6 -- 10 Year
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 6 Time (min)

Hydrograph
Report
19
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 7
Post DA-A > SF-1
Hydrograph type
= Reservoir
Peak discharge
= 2.875 cfs
Storm frequency
= 10 yrs
Time to peak
= 736 min
Time interval
= 2 min
Hyd. volume
= 25,510 cuft
Inflow hyd. No.
= 4 - Post DA-A
Max. Elevation
= 583.91 ft
Reservoir name
= Sand Filter - 1
Max. Storage
= 18,825 cuft
Storage Indication method used
Post DA-A > SF-1
Q (cfs) Hyd. No. 7 -- 10 Year Q (cfs)
15.00 15.00
12.00 12.00
9.00 9.00
6.00 6.00
3.00 3.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680
Time (min)
— Hyd No. 7 — Hyd No. 4 Total storage used = 18,825 cult

Hydrograph
Report
20
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 8
Post Offsite NW
Hydrograph type
= Combine
Peak discharge
= 3.078 cfs
Storm frequency
= 10 yrs
Time to peak
= 734 min
Time interval
= 2 min
Hyd. volume
= 27,731 cuft
Inflow hyds.
= 5, 6, 7
Contrib. drain. area
= 0.415 ac
Q (cfs)
4.00
3.00
2.00
1.00
Post Offsite NW
Hyd. No. 8 -- 10 Year
Q (cfs)
4.00
3.00
2.00
1.00
0.00 ' �l--...---` 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560 1680
Time (min)
— Hyd No. 8 — Hyd No. 5 Hyd No. 6 Hyd No. 7

Hydrograph Summary Report
21
Hydraflow Hydrographs Extension for Autodesk0 Civil 3DO by Autodesk, Inc. v2021
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
9.021
2
722
24,291
------
------
------
Pre DA-A (Pre Offsite NW)
2
SCS Runoff
0.372
2
722
1,001
------
------
------
Pre DA-B (Pre Offsite NE)
3
SCS Runoff
2.353
2
722
6,335
------
------
------
Pre DA-C (Pre Offsite SE)
4
SCS Runoff
22.49
2
720
58,720
------
------
------
Post DA-A
5
SCS Runoff
0.964
2
722
2,538
------
------
------
Post DA-B
6
SCS Runoff
0.545
2
722
1,437
------
------
------
Post DA-C
7
Reservoir
14.67
2
728
45,927
4
584.62
23,157
Post DA-A > SF-1
8
Combine
15.64
2
728
49,901
5, 6, 7
------
------
Post Offsite NW
200658.000 Stormwater Calcs.gpw
Return Period: 50 Year
Friday, 03 / 26 / 2021

Hydrograph Report
22
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Hyd. No. 1
Pre DA-A (Pre Offsite NW)
Hydrograph type =
SCS Runoff
Storm frequency =
50 yrs
Time interval =
2 min
Drainage area =
3.106 ac
Basin Slope =
0.0 %
Tc method =
User
Total precip. =
6.80 in
Storm duration =
24 hrs
Q (cfs)
10.00
N. We
. OM
4.00
2.00
M
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Pre DA-A (Pre Offsite NW)
Hyd. No. 1 -- 50 Year
120 240 360 480 600 720 840
Hyd No. 1
Friday, 03 / 26 / 2021
= 9.021 cfs
= 722 min
= 24,291 cuft
= 56
= 0 ft
= 10.00 min
= Type II
= 484
Q (cfs)
10.00
N. We
4.00
w of
0.00
960 1080 1200 1320 1440 1560
Time (min)

23
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 2
Pre DA-B (Pre Offsite NE)
Hydrograph type =
SCS Runoff
Peak discharge
= 0.372 cfs
Storm frequency =
50 yrs
Time to peak
= 722 min
Time interval =
2 min
Hyd. volume
= 1,001 cuft
Drainage area =
0.128 ac
Curve number
= 56
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 10.00 min
Total precip. =
6.80 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
Pre DA-B (Pre Offsite NE)
Hyd. No. 2 -- 50 Year
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)

Hydrograph
Report
24
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 3
Pre DA-C (Pre Offsite
SE)
Hydrograph type
= SCS Runoff
Peak discharge
= 2.353 cfs
Storm frequency
= 50 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 6,335 cuft
Drainage area
= 0.810 ac
Curve number
= 56
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 6.80 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Pre DA-C (Pre Offsite SE)
Q (cfs) Hyd. No. 3 -- 50 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. 3 Time (min)

25
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 4
Post DA-A
Hydrograph type
= SCS Runoff
Peak discharge
= 22.49 cfs
Storm frequency
= 50 yrs
Time to peak
= 720 min
Time interval
= 2 min
Hyd. volume
= 58,720 cuft
Drainage area
= 3.635 ac
Curve number
= 78.2
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 6.80 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
24.00
20.00
16.00
12.00
: M
4.00
Post DA-A
Hyd. No. 4 -- 50 Year
Q (cfs)
24.00
20.00
16.00
12.00
M
4.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
— Hyd No. 4 Time (min)

26
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 5
Post DA-B
Hydrograph type
= SCS Runoff
Peak discharge
= 0.964 cfs
Storm frequency
= 50 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 2,538 cuft
Drainage area
= 0.265 ac
Curve number
= 61
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 6.80 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
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
Post DA-B
Hyd. No. 5 -- 50 Year
Q (cfs)
1.00
0.90
I :1
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. 5 Time (min)

27
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 6
Post DA-C
Hydrograph type
= SCS Runoff
Peak discharge
= 0.545 cfs
Storm frequency
= 50 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 1,437 cuft
Drainage area
= 0.150 ac
Curve number
= 61
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 6.80 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
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
Post DA-C
Hyd. No. 6 -- 50 Year
Q (cfs)
1.00
0.90
I :1
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. 6 Time (min)

28
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 7
Post DA-A > SF-1
Hydrograph type
= Reservoir
Peak discharge
= 14.67 cfs
Storm frequency
= 50 yrs
Time to peak
= 728 min
Time interval
= 2 min
Hyd. volume
= 45,927 cuft
Inflow hyd. No.
= 4 - Post DA-A
Max. Elevation
= 584.62 ft
Reservoir name
= Sand Filter - 1
Max. Storage
= 23,157 cuft
Storage Indication method used.
Q (cfs)
24.00
20.00
16.00
12.00
Um
4.00
Post DA-A > SF-1
Hyd. No. 7 -- 50 Year
Q (cfs)
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. 7 — Hyd No. 4 Total storage used = 23,157 cult

Hydrograph
Report
29
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 8
Post Offsite NW
Hydrograph type
= Combine
Peak discharge
= 15.64 cfs
Storm frequency
= 50 yrs
Time to peak
= 728 min
Time interval
= 2 min
Hyd. volume
= 49,901 cuft
Inflow hyds.
= 5, 6, 7
Contrib. drain. area
= 0.415 ac
Q (cfs)
18.00
15.00
12.00
M
M
3.00
M
Post Offsite NW
Hyd. No. 8 -- 50 Year
120 240 360 480 600 720
Hyd No. 8 Hyd No. 5
Q (cfs)
18.00
15.00
12.00
M
. ��
3.00
0.00
840 960 1080 1200 1320 1440 1560
Time (min)
Hyd No. 6 Hyd No. 7

Hydrograph Summary Report
30
Hydraflow Hydrographs Extension for Autodesk0 Civil 3DO by Autodesk, Inc. v2021
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
11.46
2
722
30,432
------
------
------
Pre DA-A (Pre Offsite NW)
2
SCS Runoff
0.472
2
722
1,254
------
------
------
Pre DA-B (Pre Offsite NE)
3
SCS Runoff
2.990
2
722
7,936
------
------
------
Pre DA-C (Pre Offsite SE)
4
SCS Runoff
26.17
2
720
68,653
------
------
------
Post DA-A
5
SCS Runoff
1.190
2
722
3,118
------
------
------
Post DA-B
6
SCS Runoff
0.674
2
722
1,765
------
------
------
Post DA-C
7
Reservoir
21.20
2
726
55,860
4
584.80
24,272
Post DA-A > SF-1
8
Combine
22.85
2
724
60,742
5, 6, 7
------
------
Post Offsite NW
200658.000 Stormwater Calcs.gpw
Return Period: 100 Year
Friday, 03 / 26 / 2021

Hydrograph Report
31
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Hyd. No. 1
Pre DA-A (Pre Offsite NW)
Hydrograph type =
SCS Runoff
Storm frequency =
100 yrs
Time interval =
2 min
Drainage area =
3.106 ac
Basin Slope =
0.0 %
Tc method =
User
Total precip. =
7.60 in
Storm duration =
24 hrs
Q (cfs)
12.00
10.00
M
M
4.00
2.00
M
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Pre DA-A (Pre Offsite NW)
Hyd. No. 1 -- 100 Year
Friday, 03 / 26 / 2021
= 11.46 cfs
= 722 min
= 30,432 cuft
= 56
= 0 ft
= 10.00 min
= Type II
= 484
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
Hyd No. 1 Time (min)

32
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 2
Pre DA-B (Pre Offsite NE)
Hydrograph type =
SCS Runoff
Peak discharge
= 0.472 cfs
Storm frequency =
100 yrs
Time to peak
= 722 min
Time interval =
2 min
Hyd. volume
= 1,254 cuft
Drainage area =
0.128 ac
Curve number
= 56
Basin Slope =
0.0 %
Hydraulic length
= 0 ft
Tc method =
User
Time of conc. (Tc)
= 10.00 min
Total precip. =
7.60 in
Distribution
= Type II
Storm duration =
24 hrs
Shape factor
= 484
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
0
Pre DA-B (Pre Offsite NE)
Hyd. No. 2 -- 100 Year
Q (cfs)
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
0.00
120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)

Hydrograph
Report
33
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 3
Pre DA-C (Pre Offsite
SE)
Hydrograph type
= SCS Runoff
Peak discharge
= 2.990 cfs
Storm frequency
= 100 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 7,936 cuft
Drainage area
= 0.810 ac
Curve number
= 56
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 7.60 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Pre DA-C (Pre Offsite SE)
Q (cfs) Hyd. No. 3 -- 100 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. 3 Time (min)

34
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 4
Post DA-A
Hydrograph type
= SCS Runoff
Peak discharge
= 26.17 cfs
Storm frequency
= 100 yrs
Time to peak
= 720 min
Time interval
= 2 min
Hyd. volume
= 68,653 cuft
Drainage area
= 3.635 ac
Curve number
= 78.2
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 7.60 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
Post DA-A
Hyd. No. 4 -- 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
— Hyd No. 4 Time (min)

Hydrograph Report
35
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Hyd. No. 5
Post DA-B
Hydrograph type
= SCS Runoff
Storm frequency
= 100 yrs
Time interval
= 2 min
Drainage area
= 0.265 ac
Basin Slope
= 0.0 %
Tc method
= User
Total precip.
= 7.60 in
Storm duration
= 24 hrs
Q (cfs)
2.00
1.00
M
Peak discharge
Time to peak
Hyd. volume
Curve number
Hydraulic length
Time of conc. (Tc)
Distribution
Shape factor
Post DA-B
Hyd. No. 5 -- 100 Year
120 240 360 480 600 720 840 960
Hyd No. 5
Friday, 03 / 26 / 2021
= 1.190 cfs
= 722 min
= 3,118 cuft
= 61
= 0 ft
= 10.00 min
= Type II
= 484
Q (cfs)
2.00
1.00
0.00
1080 1200 1320 1440 1560
Time (min)

36
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 6
Post DA-C
Hydrograph type
= SCS Runoff
Peak discharge
= 0.674 cfs
Storm frequency
= 100 yrs
Time to peak
= 722 min
Time interval
= 2 min
Hyd. volume
= 1,765 cuft
Drainage area
= 0.150 ac
Curve number
= 61
Basin Slope
= 0.0 %
Hydraulic length
= 0 ft
Tc method
= User
Time of conc. (Tc)
= 10.00 min
Total precip.
= 7.60 in
Distribution
= Type II
Storm duration
= 24 hrs
Shape factor
= 484
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
Post DA-C
Hyd. No. 6 -- 100 Year
Q (cfs)
1.00
0.90
I :1
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. 6 Time (min)

37
Hydrograph Report
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 7
Post DA-A > SF-1
Hydrograph type
= Reservoir
Peak discharge
= 21.20 cfs
Storm frequency
= 100 yrs
Time to peak
= 726 min
Time interval
= 2 min
Hyd. volume
= 55,860 cuft
Inflow hyd. No.
= 4 - Post DA-A
Max. Elevation
= 584.80 ft
Reservoir name
= Sand Filter - 1
Max. Storage
= 24,272 cuft
Storage Indication method used.
Q (cfs)
28.00
24.00
20.00
16.00
12.00
4.00
Post DA-A > SF-1
Hyd. No. 7 -- 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 1440 1560
Time (min)
— Hyd No. 7 — Hyd No. 4 Total storage used = 24,272 cult

Hydrograph
Report
38
Hydraflow Hydrographs Extension for Autodesk® Civil 3D® by Autodesk, Inc. v2021
Friday, 03 / 26 / 2021
Hyd. No. 8
Post Offsite NW
Hydrograph type
= Combine
Peak discharge
= 22.85 cfs
Storm frequency
= 100 yrs
Time to peak
= 724 min
Time interval
= 2 min
Hyd. volume
= 60,742 cuft
Inflow hyds.
= 5, 6, 7
Contrib. drain. area
= 0.415 ac
Post Offsite NW
Q (cfs) Hyd. No. 8 -- 100 Year Q (cfs)
24.00 24.00
20.00 20.00
16.00 16.00
12.00 12.00
8.00 8.00
4.00 4.00
0.00 - 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Time (min)
— Hyd No. 8 — Hyd No. 5 Hyd No. 6 Hyd No. 7

Hydraflow Rainfall Report
39
Hydraflow Hydrographs Extension for Autodesk0 Civil 3DO by Autodesk, Inc. v2021
Return
Period
Intensity -Duration -Frequency Equation Coefficients (FHA)
(Yrs)
B
D
E
(N/A)
1
62.1764
12.7000
0.8901
--------
2
69.8703
13.1000
0.8658
--------
3
0.0000
0.0000
0.0000
--------
5
79.2597
14.6000
0.8369
--------
10
88.2351
15.5000
0.8279
--------
25
102.6072
16.5000
0.8217
--------
50
114.8193
17.2000
0.8199
--------
100
127.1596
17.8000
0.8186
--------
File name: Concord OF Curve.IDF
Intensity = B / (Tc + D)^E
Friday, 03 / 26 / 2021
Return
Period
Intensity Values (in/hr)
(Yrs)
6 min
10
16
20
26
30
36
40
46
60
66
60
1
4.82
3.86
3.23
2.79
2.46
2.20
1.99
1.82
1.68
1.56
1.46
1.37
2
5.69
4.61
3.89
3.38
2.99
2.69
2.44
2.24
2.07
1.93
1.81
1.70
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
6.57
5.43
4.65
4.08
3.65
3.30
3.02
2.79
2.59
2.42
2.27
2.15
10
7.24
6.04
5.21
4.59
4.12
3.74
3.43
3.17
2.95
2.77
2.60
2.46
25
8.25
6.95
6.03
5.34
4.80
4.38
4.02
3.73
3.48
3.26
3.07
2.91
50
9.04
7.65
6.66
5.92
5.34
4.87
4.49
4.16
3.88
3.65
3.44
3.25
100
9.83
8.36
7.30
6.50
5.87
5.36
4.94
4.59
4.29
4.03
3.80
3.60
Tc = time in minutes. Values may exceed 60.
?00114.000 Pitts School Flex Park Final Enaineerina\2-Enaineerina\2-Calculations\4-Erosion Control\Concord PCP.DCD
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
2.90
3.50
0.00
4.40
5.10
6.00
6.80
7.60
SCS 6-Hr
2.06
2.48
0.00
3.09
3.57
4.21
4.72
5.23
Huff-1 st
0.00
0.00
0.00
0.00
0.00
0.00
0.00
0.00
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
0.00
0.00
0.00
0.00
0.00
0.00
0.00

Riprap

User Input Data
Calculated Value
Reference Data
Designed By: Date: 3/15/2021
Checked By:
Company: CESI
Project Name: Arrow Disposal
Project No.: 200658.000
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 tninimum tailwater condition tmless reliable flood stage elevations
show othe 'Wise..
Outlet pipe diameter, Do (in.) 15
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 2.88 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 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 Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.)
0.3
Minimum apron length, La (ft.)
8
Apron width at pipe outlet (ft.)
3.75 3.75
Apron shape
Trapezoidal
Apron width at outlet end (ft.)
9 1
tiro 4. Dereruune the ina-Mintuu stone diameter-
drrax = 1.5 x d5o
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 0.45 0
Step 5. Determine the apron thickness:
CLASS SELCTION:
Apron thickness = 1 5 x d_.
Apron Thickness(ft.)
Minimum TW Maximum TW
0.675 0
B
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
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 minimum
length, L,, 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 entrant-
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 overfalh exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8.

1
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Rev. 11-93 8.06.3

User Input Data
Calculated Value
Reference Data
Designed By: Date: 3/26/2021
Checked By:
Company: CESI
Project Name: Arrow Disposal
Project No.: 200658.000
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 tninimum tailwater condition tmless reliable flood stage elevations
show othe 'Wise..
Outlet pipe diameter, Do (in.) 24
Tailwater depth (in.) 0
Minimum/Maximum tailwater? Min TW (Fig. 8.06a)
Discharge (cfs) 10.68 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 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 Maximum TW
Figure 8.06a Figure 8.06b
Riprap d50, (ft.) 0.4
Minimum apron length, La (ft.) 11
Apron width at pipe outlet (ft.) 6 6
Apron shape Trapezoidal
Apron width at outlet end (ft.) 13 2
tiro 4. Dereruune the ina-Mintuu stone diameter-
drrax = 1.5 x d5o
Minimum TW Maximum TW
Max Stone Diameter, dmax (ft.) 0.6 0
Step 5. Determine the apron thickness:
CLASS SELCTION:
Apron thickness = 1 5 x d_.
Apron Thickness(ft.)
Minimum TW Maximum TW
0.9 0
B
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
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 minimum
length, L,, 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 entrant-
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 overfalh exist at
pipe outlets or flows are excessive, a plunge pool should be considered, see
page 8.06.8.

1
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1 I
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im
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TRAPEZOID RIPRAP APRON FES-1 FES-2
RIP RAP CLASS B B
WIDTH AT PIPE OUTLET (FT.) 3.75 6.00
WIDTH AT APRON OUTLET (FT.) 9.25 13.00
LENGTH OF APRON (FT.) 8.00 11.00
MINIMUM DEPTH OF APRON (FT.) 0.68 0.90

Appendix

Table 4: HSGs for North Carolina Soil Types *
Urban areas runoff curve numbers fro SCS method (SCS 1986)
Cover Description
Curve Number by HSG
A
B
C
D
Fully developed urban areas
Open Space (lawns, parks, golf courses, etc.)
Poor Condition (< 50% Grass Cover)
68
79
86
89
Fair Condition (50% to 75% Grass Cover)
49
69
79
84
Good Condition (> 75% Grass Cover)
39
61
74
80
Impervious areas:
Paved parking lots, roofs, driveways, etc.)
98
98
98
98
Streets and roads:
Paved; curbs and storm sewers
98
98
98
98
Paved; open ditches
83
89
98
98
Gravel
76
85
89
91
Dirt
72
82
85
88
Developing Urban Areas
Newly graded areas
77
86
91
94
Pasture ( < 50% ground cover or heavily grazed)
68
79
86
89
Pasture (50% to 75% ground cover or not heavily grazed)
49
69
79
84
Pasture ( > 75% ground cover or lightly)
39
61
74
80
Meadow - continuous grass, protected from grazing and
generally mowed for hay
30
58
71
78
Brush ( < 50% ground cover)
48
67
77
83
Brush ( 50% to 75% ground cover)
35
56
70
77
Brush ( > 75% ground cover)
30
48
65
73
Woods (forest liter, small trees, and brush destroyed by heavy
grazing or regular burning
45
66
77
83
Woods (Woods are grazed but not burned, and some forrest
litter covers the soil)
36
60
73
79
Woods (Woods are protected from grazing, and litter and brush
adequately cover the soil)
30
55
70
77
* Table taken from NCDEQ Sormwater Design Manual Part B: Calculations Guidance, revised 3/5/2017

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Hydrologic Soil Group—Cabarrus County, North Carolina
200658.000 Arrow Disposal
Hydrologic Soil Group
Map unit symbol
Map unit name
Rating
Acres in AOI
Percent of AOI
CcB2
Cecil sandy clay loam, 2
.
17.5
32.2%
to 8 percent slopes,
moderately eroded
CcD2
Cecil sandy clay loam, 8
.
8.2
15.0%
to 15 percent slopes,
moderately eroded
ChA
Chewacla sandy loam, 0
B/D
5.7
10.4%
to 2 percent slopes,
frequently flooded
EnB
Enon sandy loam, 2 to 8
C
1.5
2.7%
percent slopes
IdA
Iredell loam, 0 to 2
C/D
1.3
2.4%
percent slopes
MeB
Mecklenburg loam, 2 to
C
0.0
0.1 %
8 percent slopes
MeD
Mecklenburg loam, 8 to
C
0.3
0.6%
15 percent slopes
PaF
Pacolet sandy loam, 15
B
8.8
16.3%
to 35 percent slopes
Ud
Udorthents, loamy
C
11.1
20.4%
Totals for Area of Interest
64.4
100.0%
USDA Natural Resources Web Soil Survey 2/23/2021
Conservation Service National Cooperative Soil Survey Page 3 of 4

Hydrologic Soil Group—Cabarrus County, North Carolina
200658.000 Arrow Disposal
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 2/23/2021
Conservation Service National Cooperative Soil Survey Page 4 of 4