SW3221004_Peak Flow Design Calculations_20230531

SYNTHETIC TURF FIELD
PEAK FLOW ANALYSIS
For
MOUNT PLEASANT HIGH SCHOOL
Mount Pleasant NC
Cabarrus NC
•
kA
SEAL _ C
20165 p G
Kevin E. Herring
ENGINEERING
16101 SMI, Road
0akboro, NC28129
980 21-M

MOUNT PLEASANT HIGH SCHOOL TURF FIELD
PEAK FLOW ANALYSIS
PROJECT NARRATIVE
Project is the installation of a synthetic turf field inside the existing running track at
Mount Pleasant High School off Walker Rd in Mount Pleasant NC (Cabarrus
County).
Project is proposed as LOW DENSITY since the total BUA with the added field will be
less than 24%. Runoff from all new BUA will be tied to existing site drainage and
conveyances.
Based on USDA Web Soil Survey data the area soils primarily classify as MeD
(Mecklenburg), a loamy soil indicative of hydraulic group C.
PRE -DEVELOPED CONDITIONS AND FINDINGS
There are two (2) outfall conveyances leaving the project location. The home side of the
fields conveys through a 15" RCP closed pipe system sloped at 0.8% while the visitor's
side of the field conveys though a 24" RCP closed pipe system sloped at 1.6%.
As determined by field survey each of these outfall systems terminates outside of the
vegetative setback of Adams Creek allowing the discharge to drain through the setback as
dispersed flow. No proposed work is associated with these outfalls thereby leaving them
in their established natural state.
For purpose of this analysis, a detailed hydraulic study of the entire closed system was
not performed. Only a peak flow value of each outfall was determined based on the
contributing drainage area for the pre and post developed conditions.
For the pre -developed analysis the contributing drainage basin is broken up into 2 basins,
the existing 2.1 % sloped grass field inside the track perimeter and a combination of the
track, bleachers, and remaining grassed areas. A 13min time of concentration was
calculated for the grass field and a 5min Tc was applied to the track, bleachers, and
remaining grass areas. Using HydroCad it was determined that the pre -developed peak
flow for the home side is 12.97 cfs and the visitor's side is 13.91 cfs.
POST -DEVELOPED ANALYSIS
The project will require that the 101,250 sf interior (grass and high jump pad) of the
running track be removed and replaced with a synthetic artificial turf system. The turf
system is a perforated carpet layer with sand and rubber infill laying on a bed of 6" of
washed stone typically in 2 layers (2"-78s & 4"-57s). This system is laid on a non -woven
fabric that lines the subgrade. The subgrade is graded to a 0.75% slope which leads to a

fabric lined washed stone trench with a perforated drain. The trench drains tie to existing
inlets inside the field interior which then leads to the 2 outfalls outside of the project area.
2 xV Pressure Treated Nailer.
Synthetic Turf (2.0" Pile)
with SBR & Sand Infill
Ex T ds -0.75 % Slope
q�g n �ii i n ii i 4 _ 2" #78 Stone
-�° ...
•.,�_';'�\�,:�r-�q" #57 stone
f
New Concrete Curb 12" 12" Compacted Subgrade
8"h x 8"w ' min: min_
Geotexiile Liner 1'. min.
\_PERFORATED HDPE PIPE
(TURF PERIMETER DRAIN)
SYNTHETIC TURF SECTION (Not to Scale)
While the turf system is considered impervious the accepted method of determining the
time of concentration is to treat the system as porous pavement in which the water has to
travel though the stone base layers. In the past, HydroCad, referenced a study by the
UNH Stormwater Center that determined that a Tc of 790 minutes produced good
predictions of the final discharge from a porous pavement with a 41" base (measured
above the underdrains). It was further predicted that smaller base thicknesses could be
used for smaller base thicknesses. It should be noted that this reference is no longer on
the HydroCad website however using an internet archive search a screenshot of this
reference was found from 2010. A copy of this screenshot is provided as reference.
Use a proportional approach a base thickness of 6" would equate to a Tc of 115 min fir
the turf system. While this is significantly longer than calculated 13 min Tc for the pre -
developed condition it would be reasonable considering that the rainfall must first travel
through a layer of rubber infill, then silica sand used for ballast, then along the turf fabric
to a perforated hole. Once through that layer it has to travel though 6" of washed stone
base to the fabric lined subgrade. Once on the subgrade it travels along the 0.75% sloped
fabric lined subgrade covered in washed stone to the perimeter trench drain. The
perimeter trench drain consists of a perforated HDPE pipe laid on a 0.5% slope
surrounded by washed stone. Once in the trench drain system it then travels several
hundred feet to the tie-in inlets and from there to the outfall.

Rubber Granule infll
Sand InFll
IIl
Using a Tc of 115 minutes for synthetic turf portion of the post -developed condition it
was determined that the 10 year post developed peak flow of the home side outfall
system is 10.64 cfs and the post developed peak flow of the visitor's side is 11.22 cfs.
A comparison breakdown of the two are below:
PRE POST
North Side Outfall: 12.97 cfs > 10.64 cfs
South Side Outfall: 13.91 cfs > 11.22 cfs
The analysis demonstrates a reduction in the peak flow and reduced impact to the existing
outfalls. The existing outfalls are located outside of the vegetative setback of Adams
Creek and allow for dispersed flow.

Job: Mount Pleasant High School Job No.
Subject: Tc Calcs
PRE -DEVELOPED
SHEET FLOW
Date 2/25/2023 Sheet
By KEH Chk By
Segment ID: A
Surface description: Grass
Manning's roughness coeff., n: 0.24
Flow length, L (total L<300') (ft): 98.00 (From Center Field Crown to Edge)
2yr 24 hour rainfall, P (in): 3.48
Land slope, s (ft/ft): 0.021
Tc= 0.007 (nL) ^0.8 1 0.22 hours
P^0.5 x s^0.4
SHALLOW CONCENTRATED FLOW
Segment ID: B
Flow length, L (ft): 0.00
Watercourse slope, s (ft/ft): 0.000
Average velocity, V (fig3-5) (ft/s): 7
Tc= L / (3600xV) 1 0.000 hours
CHANNEL FLOW N/A
Segment ID: C
Assume velocity, V (ft/s): 0.00
Flow length, L (ft): 0.00
Tc= L / (3600xV) 1 0.000 hours
Total Tc path = 0.220 hours = 13.2 minutes
USE 13.0 Minutes For Field (Pre)
USE 5 Min For Track/Bleachers/Grass Areas
POST DEVELOPED
Time of Concentration for Proposed Turf system is modeled much like porous pavement.
Reference "Modeling Pavement" from http:llwww.hydrocad.netFpavernent.htrn
Tc through Stone Base is directly proportional to the following:
Tc = (Depth of Stone Base (in) / 41 " x 790 min) where proposed depth of stone media = 6"
Tc = (6" 141 ") x 790 min = 116.61 min
USE Tc m 115 min

Job: Mount Pleasant High School Job No. Date 2/25/2023 Sheet
Subject: Tc Calcs
Modeling Pavement
By KEH Chk By
Under ideal condirions. porouspavememivirh a.srtirable base will -accept (infiltrate) many irncrhes of water,
.so there may be zero "retrialffl' in the lradilional sense. In this case, you actually need to eva}irate the
"mina, f' drat is penetrating through The pavement. This requires the rise of a high CM value (98) to capture
most of the rainfoll.
Once intercepted by the pervious surface, lire water will take some fine to Travel Mrough the base layers of
the roadway, before pornding in the voids a, the stare base. To simulate this behzwior:
(A) Use an exianded 71c vahre try simulate the travel three through the base. This approach has been sirrdled
at [lie UINH Slormwater Crnrer, where a Tc of 790 minseles kas produced goad predief as of doe final
discharge frmu porous pavement with a d} "base (measerred uhave tine u,rderdrains)_ fl is befiemd And
a propartianaf Te can be used for a smaller base thicAness, as Icing as file Myers remain propo rional
and lire Irt accordance rs kis the SIN Y spec ficallons.
(B) Route the "runof flow (A) into a pored which represents .storage in base material. Depending an the
exact material, voids in the stone can he rip to 4W&. The "pond" discharge could be through exflbration
Mac the. surrounding soil, anWorspertfle ouflei devices, such as perforated pipe (modeled as a at art
andlor orifice array.)
Using these turn .steps together will simulate the significant reduction in the peak flow caused by tiro base
rrraterial and underdruins.
From h .11www.h drocad.neU avement.htiii

1111-1- 1 http:JMw .. hyd rack. nettpavement. htm
DRAWN captures
HydrDCADO Storrawater Modeling - Since 1986
L�J Fes nav 0
11 2010 2014
Modeling Pavement
Standard pavement is usually modeled as a subcatchment with a curve number of 98. You can enter the CN value directly, or select it from the lookup table. The high CN value will cause virtually all of the
rainfall to appear as runoff, as determined by the SCS runoff equation.
What about porous pavement?
Before attempting to model porous pavement, you need to evaluate the role of the pavement in your model, and how you expect the pavement to behave. There are three basic scenarios to consider:
1} No surface runoff
Under ideal conditions, porous pavement with a suitable base will accept (infiltrate) many inches of water, so there may be zero "runoff" in the traditional sense. In this case, you actually need to evaluate the
"runoff" that is penetrating through the pavement. This requires the use of a high CN value (98) to capture most of the rainfall.
Once intercepted by the pervious surface, the water will take some time to travel through the base layers of the roadway, before ponding in the voids of the stone base. To simulate this behavior:
(A) Use an extended Tc value to simulate the travel time through the base. This approach has been studied at the UNH Stormwater Center, where a Tc of 790 minutes has produced good predictions
of the final discharge from porous pavement with a 41' base (measured above the underdrains). It is believed that a proportional Tc can he used for a smaller base thickness, as long as the layers
remain proportional and are in accordance with the UNH specifications.
(B) Route the "runoff" from (A) into a pond which represents storage in base material. Depending on the exact material, voids in the stone can he up to 40%. The "pond" discharge could he
through exfiltration into the surrounding soil, and/or specific nutlet devices, such as perforated pipe (modeled as a culvert and/or orifice array.)
Using these two steps together will simulate the significant reduction in the peak flow caused by the base material and underdra ins.
2) Complete surface runoff
In the worst case, the pavement could he fully blocked with ice or debris, in which case you would he modeling normal surface runoff with a standard CN of 98 and a relatively short Tc, much like standard
pavement.
3) Partial runoff
If you expect partial runoff, you'll need to use an appropriate CN value to model the true surface runoff. A suitable CN value may he available from the pavement supplier However, the value you achieve will
depend largely on the base material, so it's important to follow manufacturers recommendations carefully. In some cases, you may he able to estimate a CN value based on the potential maximum retention oll
the roadway base, as described here.
An alternate for modeling partial runoff would he to use a CN value of 98, and then use a link to apportion the flow between surface runoff and infiltration. This would allow the use of a flow threshold and/or
scale factor to determine the point at which some of the rainfall begins to run off the pavement rather than passing through.

Further comments
Porous pavement can he an effective component of stormwater management, as well as providing valuable groundwater recharge. A growing number of agencies are encouraging the use of porous pavement,
and are developing standard designs and modeling procedures.
However, actual performance can vary widely depending on the exact construction, maintenance, and climate. When infiltration performance is uncertain, some agencies prefer to design for the "worst case" bl.
treating all pavement as impervious, with a CN value of 93. Unfortunately, this tends to discourage the use of porous pavement in situations where it could still have real benefits. The approach you ultimatel)
select will depend on the exact design and the requirements of the reviewing agency.
References
UNH Stormwater Center:
Home ❑aft e
Porous pavement fact sheet
Porous pavement snerc
National Ready Mixed Concrete Association:
Pervious Concrete - Overview
Pervious Concrete - Hydrolooical Oesion Considerations
Hydrologic Design of Pervious Concrete (5 parts)
Home] [Support]
Copyright u 2010 KV&.0 LD 5o Ft— E.1A.- LLC (26K cy) [legal a B—)

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Ex Field Ho
Subcat Reach on Link
1
Mw
3L
Outlet
achers/Grass
me
Side

Mint _Pleasant _Home Side_ Pre_022523
Prepared by Kevin E Herring Engineering
HvdroCAD® 10.20-2a s/n 12605 © 2022 HvdroCAD Software Solutions LLC
Area Listing (all nodes)
Area
(acres)
CN
Description
(subcatchment-numbers)
0.971
61
>75% Grass cover, Good, HSG B (1S, 2S)
1.515
74
>75% Grass cover, Good, HSG C (1S, 2S)
0.771
98
Impervious Areas (2S)
3.258
76
TOTAL AREA
Pre -Developed
Printed 2/26/2023
Paae 2

Pre -Developed
Mint _Pleasant _Home Side_ Pre_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HydroCADO 10.20-2q s/n 12605 © 2022 HydroCAD Software Solutions LLC Page 3
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Ex Field Home Side Runoff Area=48,000 sf 0.00% Impervious Runoff Depth>1.98"
Tc=13.0 min CN=71 Runoff=3.27 cfs 0.182 of
Subcatchment 2S: Track/Beachers/Grass Runoff Area=93,900 sf 35.78% Impervious Runoff Depth>2.56"
Tc=5.0 min CN=78 Runoff=10.69 cfs 0.460 of
Link 3L: Outlet Inflow=12.97 cfs 0.642 of
Primary=12.97 cfs 0.642 of
Total Runoff Area = 3.258 ac Runoff Volume = 0.642 of Average Runoff Depth = 2.36"
76.32% Pervious = 2.486 ac 23.68% Impervious = 0.771 ac

Pre -Developed
Mint _Pleasant _Home Side_ Pre_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2a s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 4
Summary for Subcatchment 1 S: Ex Field Home Side
Runoff = 3.27 cfs @ 12.05 hrs, Volume= 0.182 af, Depth> 1.98"
Routed to Link 3L : Outlet
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.07"
Area (sf) CN Description
35,600 74 >75% Grass cover, Good, HSG C
12,400 61 >75% Grass cover, Good, HSG B
48,000 71 Weighted Average
48,000 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
13.0 Direct Entry,
Subcatchment 1S: Ex Field Home Side
Hydrograph
127 cfs
Type II 24-hr
3 1Oyr-24hr Rainfall=5.07"
Runoff Area=48,000 sf
Runoff Volume=0.182 of
2 Runoff Depth>1.98"
LL
Tc=13.0 min
CN=71
1 I I I I I I
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Runoff

Pre -Developed
Mint _Pleasant _Home Side_ Pre_022523 Type/1 24-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2q s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 5
Summary for Subcatchment 2S: Track/Beachers/Grass Home Side
Runoff = 10.69 cfs @ 11.96 hrs, Volume= 0.460 af, Depth> 2.56"
Routed to Link 3L : Outlet
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.07"
Area (sf) CN Description
29,900
61 >75% Grass cover, Good, HSG B
33,600
98 Impervious Areas
30,400
74 >75% Grass cover, Good, HSG C
93,900
78 Weighted Average
60,300
64.22% Pervious Area
33,600
35.78% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 2S: Track/Beachers/Grass Home Side
Hydrograph
■ Runoff
11
1
10
9
I_
8
7
H
LL
5
4
10.69 cfs
--I- -� 1----tType 1l2-4�h-r
- 1OXr-24hr kainfaH-5.01
1 Runoff Area=93,'9O0 Sf
rt Runoff Volume=0 I1460 of
- - -I runoff Depth�2.�W'
-I - - Tc---51.-0 m in
- - -; - -GN=78
I I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

Pre -Developed
Mint _Pleasant _Home Side_ Pre_022523 Type/1 24-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2q s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 6
Summary for Link 3L: Outlet
Inflow Area = 3.258 ac, 23.68% Impervious, Inflow Depth > 2.36" for 10yr-24hr event
Inflow = 12.97 cfs @ 11.97 hrs, Volume= 0.642 of
Primary = 12.97 cfs @ 11.97 hrs, Volume= 0.642 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Link 3L: Outlet
Hydrograph
■ Inflow
❑ Primary
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

is
Ex Field Visit
Subcat Reach Pon Link
2S
Track/B,bachers/Grass
3L
Outlet
VIsitiors Side

Mnt_Pleasant_Visitors Side_Pre_022523
Prepared by Kevin E Herring Engineering
HvdroCAD® 10.20-2a s/n 12605 © 2022 HvdroCAD Software Solutions LLC
Area Listing (all nodes)
Area
(acres)
CN
Description
(subcatchment-numbers)
0.200
61
>75% Grass cover, Good, HSG B (2S)
2.153
74
>75% Grass cover, Good, HSG C (1S, 2S)
0.787
98
Impervious Areas (2S)
3.140
79
TOTAL AREA
Pre -Developed
Printed 2/26/2023
Paae 2

Pre -Developed
Mint _ Pleasant _Visitors Side_Pre_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HydroCADO 10.20-2q s/n 12605 © 2022 HydroCAD Software Solutions LLC Page 3
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Ex Field Visitors Side Runoff Area=48,000 sf 0.00% Impervious Runoff Depth>2.22"
Tc=13.0 min CN=74 Runoff=3.66 cfs 0.204 of
Subcatchment 2S: Track/Beachers/Grass Runoff Area=88,800 sf 38.63% Impervious Runoff Depth>2.92"
Tc=5.0 min CN=82 Runoff=11.31 cfs 0.496 of
Link 3L: Outlet Inflow=13.91 cfs 0.700 of
Primary=13.91 cfs 0.700 of
Total Runoff Area = 3.140 ac Runoff Volume = 0.700 of Average Runoff Depth = 2.67"
74.93% Pervious = 2.353 ac 25.07% Impervious = 0.787 ac

Pre -Developed
Mint _ Pleasant _Visitors Side_Pre_022523 Type 11 24-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2q s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 4
Summary for Subcatchment 1 S: Ex Field Visitors Side
Runoff = 3.66 cfs @ 12.05 hrs, Volume= 0.204 af, Depth> 2.22"
Routed to Link 3L : Outlet
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.07"
Area (sf) CN Description
48,000 74 >75% Grass cover, Good, HSG C
48,000 100.00% Pervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
13.0 Direct Entry,
I
I
I
I
I
I
N
U
3 2
a
LL
11
Subcatchment 1S: Ex Field Visitors Side
Hydrograph
I I I i I
3.66 cfs
Type II 24-hr
11ov'r-2-4h r ka i nfa 11F1.5 7"
' RIundff Area=48,'000 sf
i Runoff VolI
ff�ume=0.204 of
-R-u;noff BeIpth�-2.22..
I I ' Tc�=131.0 min
I I I CN=74
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

Pre -Developed
Mint _ Pleasant _Visitors Side_Pre_022523 Type/1 24-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2q s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 5
Summary for Subcatchment 2S: Track/Beachers/Grass Visitiors Side
Runoff = 11.31 cfs @ 11.96 hrs, Volume= 0.496 af, Depth> 2.92"
Routed to Link 3L : Outlet
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.07"
Area (sf) CN Description
8,700
61 >75% Grass cover, Good, HSG B
34,300
98 Impervious Areas
45,800
74 >75% Grass cover, Good, HSG C
88,800
82 Weighted Average
54,500
61.37% Pervious Area
34,300
38.63% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 2S: Track/Beachers/Grass Visitiors Side
Hydrograph
T
- I- 1
- - 1
12
_I
iFil
11
I I
I I
10
9
-t----1--
fi--
8
w 7
6
_0
LL
5
4
3
- �
9
i
r
Type 1124h r
10yr-2hr air�fallr5.g7"
I Rundff Areal::88,18001 sf
I Runoff) Volume=0A961 of
- -11 moo D�pth�Z02-
- Tc=-51.0 _nA n
I I I I I I I
-4--1-- -----GN--82
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

Pre -Developed
Mint _ Pleasant _Visitors Side_Pre_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2p s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 6
Summary for Link 3L: Outlet
Inflow Area = 3.140 ac, 25.07% Impervious, Inflow Depth > 2.67" for 10yr-24hr event
Inflow = 13.91 cfs @ 11.97 hrs, Volume= 0.700 of
Primary = 13.91 cfs @ 11.97 hrs, Volume= 0.700 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
1
1
1
1
1
1
N
V
3
0
LL
Link 3L: Outlet
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Inflow
■ Primary

is 2S
New Turf Fiel Home Track/ eachers/Grass
Side Home Side
3L
Outlet
Subcat Reach on Link Routing Diagram for Mnt_Pleasant _Home Side _Post _022523
Prepared by Kevin E Herring Engineering, Printed 2/26/2023
HydroCAD® 10.20-2g s/n 12605 ©2022 HydroCAD Software Solutions LLC

Post -Developed
Mint _Pleasant _Home Side_ Post_022523
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HydroCADO 10.20-2q s/n 12605 © 2022 HydroCAD Software Solutions LLC Page 2
Area Listing (all nodes)
Area CN Description
(acres) (subcatchment-numbers)
0.686 61 >75% Grass cover, Good, HSG B (2S)
0.666 74 >75% Grass cover, Good, HSG C (2S)
0.728 98 Impervious Areas (2S)
1.177 98 New Turf Field (1 S)
3.258 85 TOTAL AREA

Post -Developed
Mint _Pleasant _Home Side_ Post_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HydroCADO 10.20-2q s/n 12605 © 2022 HydroCAD Software Solutions LLC Page 3
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: New Turf Field Home Runoff Area=51,250 sf 100.00% Impervious Runoff Depth>4.38"
Tc=115.0 min CN=98 Runoff=1.72 cfs 0.430 of
Subcatchment 2S: Track/Beachers/Grass Runoff Area=90,650 sf 35.00% Impervious Runoff Depth>2.56"
Tc=5.0 min CN=78 Runoff=10.32 cfs 0.444 of
Link 3L: Outlet Inflow=10.64 cfs 0.874 of
Primary=10.64 cfs 0.874 of
Total Runoff Area = 3.258 ac Runoff Volume = 0.874 of Average Runoff Depth = 3.22"
41.53% Pervious = 1.353 ac 58.47% Impervious = 1.905 ac

Post -Developed
Mint _Pleasant _Home Side_ Post_022523 Type/1 24-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2q s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 4
Summary for Subcatchment 1S: New Turf Field Home Side
Runoff = 1.72 cfs @ 13.28 hrs, Volume= 0.430 af, Depth> 4.38"
Routed to Link 3L : Outlet
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.07"
Area (sf) CN Description
51,250 98 New Turf Field
51,250 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
115.0 Direct Entry,
Subcatchment 1 S: New Turf Field Home Side
Hydrograph
❑ Runoff
Type II 24hr
10yr-24hr, Rainfal1=5.,07"
Runoff Area=151,250 0
Runoff Volunne=0.430 of
R nolf 6gpt �>4. 89r
LL Td=1 15.0 'min,
CM=98
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

Post -Developed
Mint _Pleasant _Home Side_ Post_022523 Type/1 24-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2q s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 5
Summary for Subcatchment 2S: Track/Beachers/Grass Home Side
Runoff = 10.32 cfs @ 11.96 hrs, Volume= 0.444 af, Depth> 2.56"
Routed to Link 3L : Outlet
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.07"
Area (sf) CN Description
29,900
61 >75% Grass cover, Good, HSG B
31,725
98 Impervious Areas
29,025
74 >75% Grass cover, Good, HSG C
90,650
78 Weighted Average
58,925
65.00% Pervious Area
31,725
35.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 2S: Track/Beachers/Grass Home Side
11
'
10
9
T
8
7
v
6
— — —
o
T 1 1— T
rL 5
3
—T—-1—-1-
2
Hydrograph
10.32 cfs
- ----� - Type 1124-�hr
1Oyr-24-hr Ikain1fallr5.Q7"
T - RundfUATrea-JO,'165Orsi
- Runoffvo[ume=0A44i of
- - - -Ri;noff DIPpthh�Z$6"
T - -1 - - F - T - Tc=J!-Oryfin
--'--'--------G1=78
I I I I
I
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Runoff

Post -Developed
Mint _Pleasant _Home Side_ Post_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2p s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 6
Summary for Link 3L: Outlet
Inflow Area = 3.258 ac, 58.47% Impervious, Inflow Depth > 3.22" for 10yr-24hr event
Inflow = 10.64 cfs @ 11.96 hrs, Volume= 0.874 of
Primary = 10.64 cfs @ 11.96 hrs, Volume= 0.874 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
9
8
7
N
V
3 6
0
LL 5
4
3
2
1
0
5
Link 3L: Outlet
Hydrograph
6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Inflow
❑ Primary

is ) C 2S
Ex Field Visit s Side Track/ eachers/Grass
isitors Side
Outlet
Subcat Reach on Link

Post -Developed
Mint _ Pleasant _Visitors Side_Post_022523
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HydroCADO 10.20-2q s/n 12605 © 2022 HydroCAD Software Solutions LLC Page 2
Area Listing (all nodes)
Area CN Description
(acres) (subcatchment-numbers)
0.200 61 >75% Grass cover, Good, HSG B (2S)
1.020 74 >75% Grass cover, Good, HSG C (2S)
0.744 98 Impervious Areas (2S)
1.177 98 New Turf Field (1 S)
3.140 88 TOTAL AREA

Post -Developed
Mint _ Pleasant _Visitors Side_Post_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2a s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 3
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 1S: Ex Field Visitors Side Runoff Area=51,250 sf 100.00% Impervious Runoff Depth>4.38"
Tc=115.0 min CN=98 Runoff=1.72 cfs 0.430 of
Subcatchment 2S: Track/Beachers/Grass Runoff Area=85,550 sf 37.90% Impervious Runoff Depth>2.92"
Tc=5.0 min CN=82 Runoff=10.90 cfs 0.478 of
Link 3L: Outlet Inflow=11.22 cfs 0.908 of
Primary=11.22 cfs 0.908 of
Total Runoff Area = 3.140 ac Runoff Volume = 0.908 of Average Runoff Depth = 3.47"
38.83% Pervious = 1.220 ac 61.17% Impervious = 1.921 ac

Post -Developed
Mint _ Pleasant _Visitors Side_Post_022523 Type/1 24-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2q s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 4
Summary for Subcatchment 1 S: Ex Field Visitors Side
Runoff = 1.72 cfs @ 13.28 hrs, Volume= 0.430 af, Depth> 4.38"
Routed to Link 3L : Outlet
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.07"
Area (sf) CN Description
51,250 98 New Turf Field
51,250 100.00% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
115.0 Direct Entry,
Subcatchment 1S: Ex Field Visitors Side
Hydrograph
❑ Runoff
Type II 24hr
10yr-24hr, Rainfal1=5.,07"
Runoff Area=151,250 0
Runoff Volunne=0.430 of
R nolf Dept �>4. ��r
LL Td=1 15.0 'min,
CM=98
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

Post -Developed
Mint _ Pleasant _Visitors Side_Post_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2a s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 5
Summary for Subcatchment 2S: Track/Beachers/Grass Visitors Side
Runoff = 10.90 cfs @ 11.96 hrs, Volume= 0.478 af, Depth> 2.92"
Routed to Link 3L : Outlet
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 10yr-24hr Rainfall=5.07"
Area (sf) CN Description
8,700
61 >75% Grass cover, Good, HSG B
32,425
98 Impervious Areas
44,425
74 >75% Grass cover, Good, HSG C
85,550
82 Weighted Average
53,125
62.10% Pervious Area
32,425
37.90% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
5.0 Direct Entry,
Subcatchment 2S: Track/Beachers/Grass Visitors Side
Hydrograph
11
"
I I I I
10
"
9
7
y
21
——-1——I—-
6
o
—1—-1——I——L
U.
5
4
3
2
Type II 24-hr
1Oyr-24hr Rainfall=5.07"
Runoff Area=85,550 sf
Runoff Volume=0.478 of
— —1 Runoff Depth>2.92"
— —I — Tc=5.0 min
rt — —I CN=82
4——i
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
❑ Runoff

Post -Developed
Mint _ Pleasant _Visitors Side_Post_022523 Type 1124-hr 10yr-24hr Rainfall=5.07"
Prepared by Kevin E Herring Engineering Printed 2/26/2023
HvdroCAD® 10.20-2p s/n 12605 © 2022 HvdroCAD Software Solutions LLC Paae 6
Summary for Link 3L: Outlet
Inflow Area = 3.140 ac, 61.17% Impervious, Inflow Depth > 3.47" for 10yr-24hr event
Inflow = 11.22 cfs @ 11.96 hrs, Volume= 0.908 of
Primary = 11.22 cfs @ 11.96 hrs, Volume= 0.908 af, Atten= 0%, Lag= 0.0 min
Primary outflow = Inflow, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
3
0
U_
Link 3L: Outlet
Hydrograph
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)
■ Inflow
■ Primary

PROJECT: MOUNT PLEASANT HIGH SCHOOL TURF FIELD
NOAA ATLAS 14 RAINFALL DATA
Map v a rPr a] Select location
Uwe ctosshair or douhla click
e hJ Click on station icon
�Q O` rl Show stations on map
o°
u c Location information:
°y. Name: North Camlina- USA`
e� Latitude: 35-4047`
Longitude: -90.4929c
o: Elevation: 617.23 g "
8
I 3
P�
G
0.4Rm
� `Source: ESRI Maps
"Source: USGS

2/26/23, 9:36 PM
Precipitation Frequency Data Server
NOAA Atlas 14, Volume 2, Version 3
Location name: North Carolina, USA*`
Latitude: 35.4049*, Longitude:-80.4829°
le
S
Elevation: 616.82 ft**
i
.
'source: ESRI Maps
`y
" source: USGS
F
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M. Bonnin, D. Martin, B. Lin, T. P-ybok, M.Yekta, and D. Riley
NOAA, National Weather Service, Silver Spring, Maryland
PF tabular i PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches)'
Average
recurrence interval (years)
Duration
���
10
25
50
100
200
500
1000
0.402
0.474
0.552
0.607
0.668
0.709
0.746
0.777
0.811
0.834
5-min
(0.371-0.436)
(0.438-0.517)
(0.508-0.601)
(0.557-0.658)
(0.610-0.723)
(0.644-0.767)
(0.674-0.807)
(0.700-0.842)
(0.725-0.880)
1 (0.739-0.905)
0.642
0.758
0.884
0.970
1.06
1.13
1.19
1.23
1.28
1.31
10-min
(0.592-0.696)
(0.700-0.826)
(0.814-0.962)
(0.890-1.05)
(0.972-1.15)
(1.03-1.22)
(1.07-1.28)
(1.11-1.33)
(1.15-1.39)
(1.16-1.43)
0.802
0.953
1.12
1.23
1.35
1.43
1.50
1.55
1.62
1.65
15-min
(0.740-0.870)
(0.880-1.04)
(1.03-1.22)
1 (1.13-1.33)
1 (1.23-1.46)
1 (1.30-1.55)
1 (1.36-1.62)
1 (1.40-1.68)
1 (1.44-1.75)
1 (1.46-1.79)
30-min
(1.01 1019)
(1.22--31.44)
1.46--1973
1.63 1893)
(1.83 2016)
1.96 2.33
2.08 2948)
(2. 8 2?62)
(2. 0 2?79)
(2.37 2790
1.37
1.65
2.04
2.32
2.66
2.92
3.16
3.39
3.69
3.90
60-min
(1.26-1.49)
(1.53-1.80)
(1.88-2.22)
(2.13-2.51)
(2.43-2.88)
(2.65-3.16)
(2.86-3.42)
(3.06-3.68)
(3.29-4.00)
(3.45-4.23)
1.59
1.92
2.38
2.73
3.17
3.50
3.83
4.15
4.56
4.87
2-hr
(1.45-1.73)
(1.76-2.10)
(2.17-2.60)
(2.48-2.97)
(2.88-3.46)
(3.16-3.81)
(3.44-4.17)
(3.69-4.53)
(4.02-4.98)
(4.26-5.32)
1.69
2.04
2.11
2.94
3.45
3.81
4.25
4.66
5.20
1.62
3-hr IF
(1.55-1.85)
(1.87-2.24)
(2.34-2.79)
(2.68-3.20)
(3.13-3.76)
(3.48-4.19)
(3.81-4.61)
(4.14-5.06)
(4.57-5.65)
(4.89-6.12)
6-hr IF
2.01
(1.88-2.25)
2.47
(2.27-2.71)
3.09
(2.82-3.37)
3.56
(3.25-3.89)
4.20
(3.81-4.57)
4.71
(4.24-5.12)
5.22
(4.66-5.68)
5.74
(5.08-6.24)
6.46
(5.64-7.01)
7.01
(6.05-7.63)
2.43
2.94
3.69
4.28
5.09
5.74
6.41
7.11
8.08
8.85
12-hr
(2.24-2.65)
(2.70-3.22)
(3.38-4.03)
(3.91-4.68)
(4.61-5.53)
(5.16-6.23)
(5.72-6.94)
(6.27-7.68)
(7.00-8.70)
(7.57-9.55)
2.89
3.48
4.37
5.07
6.01
6.77
7.55
8.35
9.44
10.3
24-hr
(2.68-3.12)
(3.24-3.77)
(4.06-4.72)
(4.70-5.48)
(5.56-6.50)
(6.24-7.31)
(6.93-8.15)
(7.64-9.01)
(8.61-10.2)
1 (9.36-11.2)
2ilay
(3. 4 3864)
(3. 8-0AO)
(4.715847)
(5.44 6732)
(6.41- 46)
(7. 8 8939)
(7.96 9632)
(8. 6---10.3)
(9.8-161.6)
(10.7- 2.7)
4.31
3day
(3.333985)
(4.01-4.64)
(4.975575)
(5.761-6.62)
(6.2-.17 -7881)
(7.5218.77)
(8.339774)
(916.160.7)
(10.3-2.1)
(112213.2)
3.80
456
562
646
7.62
8.54
9.48
10.4
1-.8
(3.53-4.07)
.
(4.24-4.88)
.
(5.22-6.02)
.
(5.99-6.92)
(7.04-8.
87-9.
71-10
57-11)
(1712)
( 1112.84dy
.7-13.8)
4.37
5.21
6.35
7.25
8.49
9.48
10.5
11.5
13.0
0
14.1
7 day
(4.10-4.66)
(4.89-5.56)
(5.95-6.77)
(6.78-7.73)
(7.93-9.05)
(8.83-10.1)
(9.74-11.2)
(10.7-12.3)
(11.9-13.9)
(12.9-15.1)
5.00
5.95
7.15
8.10
9.37
10.4
11.4
12.4
13.8
14.9
10-day
(4.70-5 32)
(5.59-6.33)
(6.71-7.60)
(7.59-8.61)
(8.76-9.95)
(9.67-11.0)
(10.6-12.1)
(11.5-13.2)
(12.8-14.7)
(13.7-15.9)
6.71
7.92
9.36
10.5
12.0
13.2
14.4
15.6
17.3
18.5
20-day
(6.35-7 08)
(7.50-8.35)
(8.85-9.85)
(9.91-11.0)
(11.3-12.6)
(12.4-13.9)
(13.5-15.2)
(14.6-16.5)
(16.1-18.2)
(17.2-19.6)
30-day
8.25
9.71
11.3
12.5
14.1
15.4
16.6
17.8
19.5
20.7
(7.83-8 68) 11
(9.21-10.2)
1 (10.7-11.9)
1 (11.8-13.1)
1 (13.4-14.8)
1 (14.5-16.2)
1 (15.6-17.5)
1 (16.8-18.8)
1 (18.2-20.5)
1 (19.4-21.9)
10.4
12.2
13.9
15.2
17.0
18.3
19.6
20.8
22.5
23.7
45-day
(9.95-10.9) 11
(11.6-12.7)
1 (13.3-14.5)
1 (14.5-15.9)
1 (16.2-17.7)
1 (17.4-19.1)
1 (18.6-20.5)
1 (19.7-21.8)
21.2-23.6)
1 (22.3-24.9)
2.5
2.8
60-day
11.19-12.9
1319-15.1
15.176-17.0
17.11- 8.6
18.t8- 0.5
20.11.1
21 42.4
22 63.8
24 25 6.7
25.4628.0
t Precipitation frequency (PF) estimates in this table are based on frequency analysis of partial duration series (PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90 % confidence interval. The probability that precipitation frequency estimates (for
a given duration and average recurrence interval) will be greater than the upper bound (or less than the lower bound) is 5 % . Estimates at upper bounds are not
checked against probable maximum precipitation (PMP) estimates and maybe higher than currently valid PIMP values.
Please refer to NOAA Atlas 14 document for more information.
Back to Top
PF graphical
https://hdsc. nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=35.4049&Ion=-80.4829&data=depth&units=engiish&series=pds 1 /3

3
m
$N
W
546820
35° 24' 24" N
P
93
35o 24' 13" N
546820 546860 546900 546940 5469W
3
Map Scale: 1:1,620 W printed on A portrait (8.5" x 11") sheet
Meters N
0 20 40 80 120
Feet
0 50 100 200 300
Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: UTM Zone 17N WGS84
U}DA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
Hydrologic Soil Group—Cabarrus County, North Carolina
(Mount Pleasant High School)
5468M 5469M 546940 5469M
547020
547020
3
W
5470M
35° 24' 24" N
5
93
ro
M
35° 24' 13" N
547060
3
in
N
2/26/2023
Page 1 of 4

Hydrologic Soil Group—Cabarrus County, North Carolina
(Mount Pleasant High School)
MAP LEGEND
Area of Interest (AOI)
Area of Interest (AOI)
Soils
Soil Rating Polygons
0 A
0 A/D
0 B
0 B/D
C
0 C/D
0 D
Not rated or not available
Soil Rating Lines
r r A
r r A/D
r B
B/D
r r C
0 C/D
r r D
r r Not rated or not available
Soil Rating Points
0 A
0 A/D
■ B
■ B/D
MAP INFORMATION
p C
The soil surveys that comprise your AOI were mapped at
1:24,000.
0 C/D
0 D
Warning: Soil Map may not be valid at this scale.
p Not rated or not available
Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
Water Features
line placement. The maps do not show the small areas of
Streams and Canals
contrasting soils that could have been shown at a more detailed
scale.
Transportation
§_§_+ Rails
Please rely on the bar scale on each map sheet for map
#%-0 Interstate Highways
measurements.
US Routes
Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
Major Roads
Coordinate System: Web Mercator (EPSG:3857)
Local Roads
Maps from the Web Soil Survey are based on the Web Mercator
Background
projection, which preserves direction and shape but distorts
distance and area. A projection that preserves area, such as the
® Aerial Photography
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: Cabarrus County, North Carolina
Survey Area Data: Version 22, Sep 7, 2022
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Mar 13, 2022—May
9, 2022
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.
UU� Natural Resources Web Soil Survey 2/26/2023
� Conservation Service National Cooperative Soil Survey Page 2 of 4

Hydrologic Soil Group—Cabarrus County, North Carolina
Mount Pleasant High School
Hydrologic Soil Group
Map unit symbol
Map unit name
Rating
Acres in AOI
Percent of AOI
CuB2
Cullen clay loam, 2 to 8
percent slopes,
moderately eroded
B
2.0
27.6%
MeD
Mecklenburg loam, 8 to
15 percent slopes
C
5.2
72.4%
Totals for Area of Interest
7.1
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 2/26/2023
Conservation Service National Cooperative Soil Survey Page 3 of 4

Hydrologic Soil Group—Cabarrus County, North Carolina
Mount Pleasant High School
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff.- None Specified
Tie -break Rule: Higher
usDA Natural Resources Web Soil Survey 2/26/2023
Conservation Service National Cooperative Soil Survey Page 4 of 4