Appendix B.2_Response_DEMLR_comments

Piedmont Lithium Carolinas,Inc. I Response to Additional Information Request(dated January 14,2022)
Appendix B:Response to Mooresville Regional Office Comments
B.2 Attachment 2 — Conversion Plant Drainage
Calculations

This page intentionally left blank.

FYZ
Stormwater
PIEDMONT
LITHIUM Calculations
Lithium Hydroxide Conversion
Plant
Gaston County, North Carolina
May 31, 2022
CARC�'�''�.
•�� SEAL �� •� =
032062
Valerie K.Hay,K4f.*Jl Jrg,2 1 .l v
f///ll111100

This page intentionally left blank.

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations
Contents
Contents
1.0 Project Description.............................................................................................................1
2.0 Site Information..................................................................................................................1
2.1 Project Location..............................................................................................................1
2.2 Soils................................................................................................................................1
2.3 Topography ....................................................................................................................1
2.4 Site Characteristics.........................................................................................................1
3.0 Erosion Control Calculations..............................................................................................1
3.1 Sediment Basins.............................................................................................................1
3.2 Sediment Traps ..............................................................................................................2
3.3 Skimmer Basins..............................................................................................................2
4.0 Stormwater Calculations ....................................................................................................2
5.0 Culvert and Stream Crossing Calculations ........................................................................2
Appendices
Appendix A— FEMA Firmette Map
Appendix B — USGS Topo Map
Appendix C — Drainage Area Maps
Appendix D — Soil Map and Report
Appendix E — Curve Number and Time of Concentration
Appendix F — NOAA Rainfall Data
Appendix G — Sediment Basin Calculations
Appendix H — Sediment Trap and Skimmer Basin Calculations
Appendix I —Stormwater Calculations
Appendix J — Stream and Culvert Crossing Calculations
Appendix K— Outlet Protection Calculations
1

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Project Description
1 .0 Project Description
Piedmont Lithium Carolinas, Inc. is proposing an integrated facility in Gaston County, North
Carolina that will include both Concentrate Operations (including Mine #1, Concentrate Plant,
and Industrial Minerals Plant) as well as a Lithium Hydroxide Conversion Plant. HDR
Engineering, Inc. of the Carolinas (HDR) is providing site layout, grading, stormwater, and
erosion control plans for the Lithium Hydroxide Conversion Plant. This will include an entrance
road, rail access, rail storage, the plant and associated administrative, operations, and
maintenance buildings. This report will address the site stormwater analysis and design.
2.0 Site Information
2.1 Project Location
The Lithium Hydroxide Conversion Plant will be located east of Cherryville on a combined
parcel of property just south of Hephzibah Church Road. The property is bound on the west by
Anthony Grove Road, and on the east by Saint Marks Church Road.
2.2 Soils
The onsite soils consist of both sandy and clay loams, (see soils map in Appendix D) with
moderate to poor infiltration rates. The majority of the site soils have a hydrologic soil group
rating 'B', with a small percentage of`D' or 'B/D' ratings.
2.3 Topography
Elevations range from 910 feet NAVD at the corner of Anthony Grove Road and Hephzibah
Church Road to 795 feet NAVD where Beaverdam Creek crosses St. Marks Church Road. The
existing topography is shown on the Drainage Area Maps in Appendix C of this report.
2.4 Site Characteristics
This site is located within a Water Supply— IV (WS-IV)watershed protected area. The site will
be developed under the low density option with less than 24% built upon area and 30-foot
stream buffers, following the standard rules for erosion and sediment controls, as set forth by
the North Carolina Department of Environmental Quality (NCDEQ).
3.0 Erosion Control Calculations
3.1 Sediment Basins
All sediment basins are designed per NCDEQ standards. They are designed for a 25-year
design storm, using local rainfall data (see Appendix F). Basins have a minimum surface area
ratio of 435 ftz/cfs or greater, with appropriate length-to-width ratios and inflow points located as
far as possible from the principal spillway inlet. All basins exceed the minimum volume
requirement of 1,800 ft3/acre. Basins are to be constructed with a primary spillway and skimmer,
as well as an emergency spillway designed to maintain 1-foot of freeboard. Porous baffles are
1

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Stormwater Calculations
to be installed to reduce velocity and turbulence of the water flowing through the basin (see plan
sheet OOG-007 for details).
3.2 Sediment Traps
For drainage areas less than 1 acre, sediment traps have been designed per NCDEQ standards
with a 25-year design storm based on local rainfall data (see Appendix F). Each trap has a
minimum surface area ratio of 435 ftz/cfs or greater and meet the minimum volume requirement
of 3,600 ft3/acre of disturbed area. All sediment traps are to be constructed per NCDEQ
minimum design criteria with a modified spillway designed to detain flow and allow improved
sediment trapping (see plan sheet OOG-007 for details).
3.3 Skimmer Basins
For drainage areas between 1 and 5 acres, skimmer sediment basins have been designed per
NCDEQ standards with a 25-year design storm based on local rainfall data. Each skimmer
basin has a minimum surface area ratio of 325 ftz/cfs or greater and a minimum volume
requirement of 1800 ft3/acre of disturbed area. The orifice of a skimmer should be selected in
order to achieve the desired dewatering time of 3 days (see plan sheet OOG-007 for details).
4.0 Stormwater Calculations
Storm sewer piping will convey stormwater runoff from the roadside ditches surrounding
conversion plant to the sediment basins. Using HydroCAD version 10.10-5a analysis software,
the storm sewer was designed based on the 25-year storm, as developed from local rainfall
data (see Appendix F). The storm sewer sizes were designed for full development, using a
minimum time of concentration of 6 minutes. All proposed storm sewer pipes were designed
assuming a minimum slope of 1% and a roughness coefficient of n= 0.012. The roadside
ditches surrounding the conversion plant were also designed based on the 25-year storm and
local rainfall data. The ditches are designed at a minimum slope of 1% with a 1-foot flat bottom
and 3:1 side slopes assuming a roughness coefficient of n= 0.025 (see Appendix 1).
5.0 Culvert and Stream Crossing Calculations
To provide access to the site, an entrance road must be constructed from Hephzibah Church
Road to the plant and will include 3 different culvert crossings along the route. The 3 crossings
are designed for the 25-year design storm and checked for the 100-year storm to prevent
overtopping using local rainfall data (see Appendix F). The first culvert crossing will consist of a
24-inch culvert with a contributing drainage area of 2.50 acres. The second crossing was sized
as 36-inch culvert for the 5.59 acres of contributing drainage area. The last culvert along the
entrance road, with a 74.73-acre drainage area, was sized to be an open bottom metal arch
span of 10 ft. with a rise of 5.25-ft. The open bottom arch will allow the delineated stream to be
unimpacted in the area (see Appendix J).
2

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Culvert and Stream Crossing Calculations
A railroad system is also shown to the south of the main entrance road. It will provide service
from the main CSX line, north of Hephzibah Church Road, to the plant site. The railroad will
require 2 drainage crossings: a culvert crossing near Hephzibah Church Road and a crossing
along the delineated stream. The culvert crossing will be a 48-inch culvert with a contributing
drainage area of 14.22 acres. The stream crossing has a contributing drainage area of 149.8
acres. An open bottom arch span of 14-feet with a rise of 7.25-feet was sized to accommodate
the crossing and to prevent the stream from being impacted (see Appendix J).
The hydrographs for each culvert were created using Hydraflow Extensions for Civil 3D 2018
(see Appendix J). The curve numbers and time of concentrations are showing in Appendix E for
they hydrograph calculations. The culvert crossing design and analysis were performed using
HY8 version 7.60 by FHA (see Appendix J).
3

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix A—FEMA Firmette Map
AppendixA — FEMA Firmette
Map

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix A—FEMA Firmette Map
This page intentionally left blank.

National Flood Hazard Layer FIRMette FEMA Legend
81°19'48"W 35o24'3"N SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
f
yl Without Base Flood Elevation(BFE)
Zone A,V,A99
w Iww% t SPECIAL FLOOD With BFE or Depth Zone Ae,AO,AH,VE,AR
_ lei r HAZARD AREAS Regulatory Floodway
+ ICI s 0.2%Annual Chance Flood Hazard,Areas
- of 1%annual chance flood with average
I�it # * depth less than one foot or with drainage
f * ', ` f, I # r {i areas of less than one square mile zone x
*!r FFuture Chance
Flood
l%Annual
_ Chance Flood Hazard zone
Area with Reduced Flood Risk due to
- •t OTHER AREAS OF Levee.See Notes.zone x
} # FLOOD HAZARD Area with Flood Risk due to Leveezone D
NO SCREEN Area of Minimal Flood Hazard zonex
' Q Effective LOMRs
# OTHER AREAS Area of Undetermined Flood Hazard zone
GENERAL ---- Channel,Culvert,or Storm Sewer
STRUCTURES IIIIIII Levee,Dike,or Floodwall
Cross
AREA OF IVIINI VIAL FLOOD I-IP I RD � Water Surface
Elevation
1%Annual Chance
i 17•5 Water Surface Elevation
Z?O 8- - - Coastal Transect
b _ ^^^^ 513— Base Flood Elevation Line(BFE)
•- LTA
" + tr L }+ Limit of Study
Jurisdiction Boundary
370455 —--- Coastal Transect Baseline
OTHER _ Profile Baseline
FEATURES Hydrographic Feature
w
Digital Data Available N
dIP + 4
No Digital Data Available
+y
} Awl' . _ . t MAP PANELS Unmapped
iF F •di. q Q
rt '; The pin displayed on the map is an approximate
+ point selected by the user and does not represent
■ an authoritative property location.
This map complies with FEMA's standards for the use of
w _ digital flood maps if it is not void as described below.
The basemap shown complies with FEMA's basemap
accuracy standards
The flood hazard information is derived directly from the
# authoritative NFHL web services provided by FEMA.This map
was exported on 8/26/2021 at 5:09 PM and does not
r A Y• reflect changes or amendments subsequent to this date and
.. • I qp time.The NFHL and effective information may change or
y Z on 2 E become superseded by new data over time.
This map image is void if the one or more of the following map
elements do not appear:basemap imagery,flood zone labels,
legend,scale bar,map creation date,community identifiers,
EKZZZM 81019'11"W 35023'34"N FIRM panel number,and FIRM effective date.Map images for
Feet 1:6 000 unmapped and unmodernized areas cannot be used for
0 250 500 1,000 1,500 2,000 regulatory purposes.
Basemap:USGS National Map:Orthoimagery.Data refreshed October,2020

This page intentionally left blank.

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix B—USGS Topo Map
Appendix B — USGS Topo
Map

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix B—USGS Topo Map
This page intentionally left blank.

m
ro
a
Q
c d
--
t
kkCC1155 C�6GG�m
I Caw'
AA
*00
41*
41f-
cc "Soso
A L
7A
Dw
� � m
ca eam�m .'
o �x
1 e
111

This page intentionally left blank.

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix C—Drainage Area Maps
Appendix C — Drainage Area
Maps

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix C—Drainage Area Maps
This page intentionally left blank.

"N
��-� ��'�\•`r�,�- l��l�����������ll� lJILi/ � � _ _ _ �� � 1>> 1� � � , 1 _ _ _ � �� 11 ��-,��
DA1:74.73 AC
TOC:28.1 MIN �� \ ��
CN.78 �/- ) I /�"
r� IT
��
Wli
�_\ � ��� �j� l 500 0 500 1000
\ /-A r
SCALE: 1" = 500'
/OP
'ice TOC:CN479MI\ ` ` �.\ \� \� (O -/
MA GENERAL LEGEND
TOC:12.9
5.59 IN
C �.�
CN:78
J I .
■ ■ ■ ■ ■ ■ ■ ■ ■ STREAM CROSSING DRAINAGE AREA
i� �� �- x -x �' A
+�" ��— ' X 1 TIME OF CONCENTRATION
SEDIMENT BASIN/TRAP DRAINAGE AREA
goo
� ' - X
fldh
1`4--x x-x-x x- -x-x x
It
r ,
r _
I
X _ _
o °
°
0
0
0
0
0
a
1 �
DA5:14.22 AC -- - �.• •�
°
TOC:16.1 MIN
CN:79 -'���\� A\ V
°8. °8 a
_ o °o DA4:149.8 A aC
° l
00 6 (INCLUDES DA1-3,5) I I \
---- __--- �a o o : O �•
TOC:27.7 MIN
CN:76
— •�- Do,
- SS
1 I
X I
X
SHEET TITLE FILENAME OOC-02.DWG
DRAINAGE ANALYSIS MAP, SCALE 1"=500'
PIEDMONT PLAN VIEW
SHEET OOC 02
LITHIUM HYDROXIDE CONVERSION PLANT

This page intentionally left blank.

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix D—Soil Map and Report
Appendix D — Soil Map and
Report

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix D—Soil Map and Report
This page intentionally left blank.

3 Hydrologic Soil Group—Gaston County, North Carolina
N M
O W
N
W W
469700 470000 470300 470600 470900 471200 471500 471800
35'24'30"N 35'24'30"N
00
wr e
R3 &npV
o
� o
• es
D
D �(
°
JJ `F l
• D
D
o
D
-4 4
35'22'57"N 35'22'57'N
469700 470000 470300 470600 470900 471200 471500 471800
3 3
N i0
Map Scale:1:14,000 if printed on A portrait(8.5"x 11")sheet.
o
N Meters
0 200 400 800 1200
Feet
0 500 1000 2000 3000
Map projection:Web Mercator Comer coordinates:WGS84 Edge tics:L TM Zone 17N WGS84
UsDA Natural Resources Web Soil Survey 8/26/2021
Conservation Service National Cooperative Soil Survey Page 1 of 5

Hydrologic Soil Group—Gaston County, North Carolina
MAP LEGEND MAP INFORMATION
Area of Interest(AOI) p C The soil surveys that comprise your AOI were mapped at
Area of Interest(A01) 0 C/D 1:24,000.
Soils Please rely on the bar scale on each map sheet for map
Soil Rating Polygons 0 D measurements.
0 A p Not rated or not available Source of Map: Natural Resources Conservation Service
0 A/D Water Features Web Soil Survey URL:
Streams and Canals Coordinate System: Web Mercator(EPSG:3857)
0 B Transportation Maps from the Web Soil Survey are based on the Web Mercator
0 B/D projection,which preserves direction and shape but distorts
Rails distance and area.A projection that preserves area,such as the
0 C #%-0 Interstate Highways Albers equal-area conic projection,should be used if more
accurate calculations of distance or area are required.
C/D US Routes
0
This product is generated from the USDA-NRCS certified data as p Major Roads of the version date(s)listed below.
Not rated or not available Local Roads
Soil Survey Area: Gaston County,North Carolina
Soil Rating Lines Background Survey Area Data: Version 20,Jun 4,2020
" x A ® Aerial Photography Soil map units are labeled(as space allows)for map scales
" r A/D 1:50,000 or larger.
B Date(s)aerial images were photographed: Apr 23,2014—Nov
B/D 28,2017
The orthophoto or other base map on which the soil lines were
" x C compiled and digitized probably differs from the background
" 0 C/D imagery displayed on these maps.As a result,some minor
shifting of map unit boundaries may be evident.
" r D
" r Not rated or not available
Soil Rating Points
0 A
0 A/D
B
B/D
UU� Natural Resources Web Soil Survey 8/26/2021
� Conservation Service National Cooperative Soil Survey Page 2 of 5

Hydrologic Soil Group—Gaston County, North Carolina
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
ApB Appling sandy loam, 1 to B 181.2 28.5%
6 percent slopes
CeB2 Cecil sandy clay loam,2 B 87.3 13.7%
to 8 percent slopes,
moderately eroded
CeD2 Cecil sandy clay loam,8 B 53.9 8.5%
to 15 percent slopes,
moderately eroded
CfB Cecil-Urban land B 7.5 1.2%
complex,2 to 8
percent slopes
ChA Chewacla loam,0 to 2 B/D 50.6 7.9%
percent slopes,
frequently flooded
HeB Helena sandy loam, 1 to D 14.5 2.3%
6 percent slopes
LdB2 Lloyd sandy clay loam,2 B 53.0 8.3%
to 8 percent slopes,
moderately eroded
MaB2 Madison sandy clay B 0.7 0.1%
loam,2 to 8 percent
slopes,moderately
eroded
MaD2 Madison sandy clay B 0.1 0.0%
loam,8 to 15 percent
slopes,moderately
eroded
PaD2 Pacolet sandy clay B 9.1 1.4%
loam,8 to 15 percent
slopes,moderately
eroded
PaE Pacolet sandy loam, 15 B 71.8 11.3%
to 25 percent slopes
W Water 2.2 0.3%
WeD Wedowee sandy loam,6 B 98.3 15.4%
to 15 percent slopes
WoA Worsham loam,0 to 2 D 6.3 1.0%
percent slopes
Totals for Area of Interest 636.4 100.0%
USDA Natural Resources Web Soil Survey 8/26/2021
Conservation Service National Cooperative Soil Survey Page 3 of 5

Hydrologic Soil Group—Gaston County, North Carolina
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
usDA Natural Resources Web Soil Survey 8/26/2021
Conservation Service National Cooperative Soil Survey Page 4 of 5

Hydrologic Soil Group—Gaston County, North Carolina
Aggregation is the process by which a set of component attribute values is
reduced to a single value that represents the map unit as a whole.
A map unit is typically composed of one or more "components". A component is
either some type of soil or some nonsoil entity, e.g., rock outcrop. For the
attribute being aggregated, the first step of the aggregation process is to derive
one attribute value for each of a map unit's components. From this set of
component attributes, the next step of the aggregation process derives a single
value that represents the map unit as a whole. Once a single value for each map
unit is derived, a thematic map for soil map units can be rendered. Aggregation
must be done because, on any soil map, map units are delineated but
components are not.
For each of a map unit's components, a corresponding percent composition is
recorded. A percent composition of 60 indicates that the corresponding
component typically makes up approximately 60% of the map unit. Percent
composition is a critical factor in some, but not all, aggregation methods.
The aggregation method "Dominant Condition"first groups like attribute values
for the components in a map unit. For each group, percent composition is set to
the sum of the percent composition of all components participating in that group.
These groups now represent"conditions" rather than components. The attribute
value associated with the group with the highest cumulative percent composition
is returned. If more than one group shares the highest cumulative percent
composition, the corresponding "tie-break" rule determines which value should
be returned. The "tie-break" rule indicates whether the lower or higher group
value should be returned in the case of a percent composition tie. The result
returned by this aggregation method represents the dominant condition
throughout the map unit only when no tie has occurred.
Component Percent Cutoff. None Specified
Components whose percent composition is below the cutoff value will not be
considered. If no cutoff value is specified, all components in the database will be
considered. The data for some contrasting soils of minor extent may not be in the
database, and therefore are not considered.
Tie-break Rule: Higher
The tie-break rule indicates which value should be selected from a set of multiple
candidate values, or which value should be selected in the event of a percent
composition tie.
usDA Natural Resources Web Soil Survey 8/26/2021
Conservation Service National Cooperative Soil Survey Page 5 of 5

This page intentionally left blank.

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix E—Curve Number and Time of Concentration
Appendix E — Curve Number
and Time of Concentration

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations
Appendix E—Curve Number and Time of Concentration
This page intentionally left blank.

Table -12
Runoff Curve Numbers
Curve numbers for
-- -------------C'r�wtr lkcrip�it>rti --------------------------
-- —L�yllrulslgie sail gr�1P--- -
AYcrakc
Ir avcr typc and hydrologi a cued i 6011 iii5�rt4'i�Yu�,arCu A $ L' I
'FAY den-eli ed whalr-ur vas (w -gelalk,n e.xwhf phed)
Opc;i spmx(Isuais,parks, *alf courses.cernalerks.cle,} 5v-
Poor condition (grass cover< 3 ia)............................ bpi 79 86 89
F air vandifion I grates cow 50% to 7M.................... 49 69 79 R4
GoM caiiditlan(gra_s.,over>75%)-------------------........ 34 61 74 80
P;1 vd parking]at!;,roofs,drivrwxys.E4r.
(excluding ri hl-of-wa )............................,,.,..,.. 98 48 99 48
SIrew and roads:
Parrs& curbs and storm scwcrs(cxcluding
right-cf-way)...,,,.,.,,,,,,,,,,,,,,,,,,,,,.--.................... 98 9?: 9H 98
Paved.ap4i &fi�hts(Iris luding rjpt-af vray} .... 83 8is 92 93
Gravet(including right,I'-way).......................... 76 8S 89 91
DO{indudirig righi-or-way] .............................. 72 82 R7 get
Urban dratncts:
Commcrcial and business„,,,,,,.,............................... , 85 89 92 94 95
lnduStrial................................,,,,,................................ 72 81 88 l 93
Resi&nval digricts key airtrige lc sixlw
Ii� acm or lcs&(t#tivr! hcascSI.-. •-------...---............. 65 77 95 90 92
1.4 acrr.....-------------------------.............._. _ ........ 38 61 _ 83 87
111 acre,,............................,.-..........................__......... 30 57 81 86
I�2 acre,,,,...........................,,... ..............................,,.. 25 54 71, 80 SS
Iacrc,,,,,,.—....................................,............................ 20 51 6S. 79 M
................,,,, 13 46 65 77 ST
AgF#cu l rrrf bawds
Pasture, grassland or range i con wwous for age for gazingl'
Poor hydrologic condition....."I'll-,............................ 68 79 86 \4)
Fair h}dmlogiccondil Pon............................................ 79 H4
GJn~W hydrV19.9i-C c(widilion .......................................... 39 fit 74 NO
W
Poor hydrolcP& can itran.,,....--•-------------........................................... 45 w, r
8.3
Fair hydra ogic co ilion„,-....-.--------------............................... 6 6I] 73 79
{pDod hydrolo4ic cwrdition ....-.-.....................,,.,.,,., M r 77
Nc u'ly graded
(I Vious arm Ofily.r�o Vqa>ilIUd)-,,,,,,,,,,,,,,,,,--,,.... NO 91 94
1 Mwaie nanoff"L"iion,and la- IF,2S.
2 TIw at•rrio pemm mkpm arts shown wda wTd 404C%'el*p ilr{C+Mp):+ic CN'J.11DACr tsrllmpliafk�WC&I follMV$!impar+'kK*ArM
"dlrms yconncsicd w ihe*minage 4pirm ampmi.o sarm have a of".and prrviuw armor air cimriderc4 equivalerrt co apen
tipara in goad hydrolo it cmWliion,
I :�Thow"arc Oviv*lepl NoIhaac a1,rm-% rc.Cwr iw(N'a may 1 e w"cd fog odor vmibanwlim orapo Ip�woca "lypc'
4 Pax:Fewil biker,mull hers,mid bnjAaw desrroyrd by hemN g,=ing 4r regvtar huming.
Fsir: Woo&arc grazed Irill rLw burued ind skifix fin€I Boer c-avers Ihr>oil.
l}m d: Wo ds arc pnAceled from graai.ag-and I1cL{[,ind brush Adegostety 4ovrr Ute sail,

COMPOSITE CURVE NUMBER CALCULATIONS
DA1-STREAM CROSSING AT ROAD
SOIL GROUP COVER TYPE ACRES % CN %of DA
B Pvmt/Sidewalk/Equipment pads 13.43 0.18 98 0.97
Woods 28.21 0.39 66
Grass 130.99 0.43 79
D lWoods 12.10 11.00 183 10.03
COMPOSITE (B) 77.5
COMPOSITE (D) 83.0
TOTAL COMPOSITE CN 78
DA2-CROSSING AT ROAD
SOIL GROUP COVER TYPE ACRES % JCN %of DA
B Pvmt/Sidewalk/Equipment pads 0.06 0.02 198 11.00
Grass 2.44 0.98 179
TOTAL COMPOSITE CN 79
DA3-CROSSING AT ROAD
SOIL GROUP COVER TYPE ACRES % CN %of DA
B Pvmt/Sidewalk/Equipment pads 0.13 0.02 98 1.00
Woods 0.68 0.12 66
Grass 14.77 0.85 79
TOTAL COMPOSITE CN 78
DA4-STREAM CROSSING AT RAILROAD
SOIL GROUP COVER TYPE ACRES % CN %of DA
B Pvmt/Sidewalk/Equipment pads 14.74 0.10 98 0.96
Woods 55.09 0.38 66
Grass 75.95 0.52 79
D Woods 3.87 0.96 83 0.04
Grass 0.16 10.04 189
COMPOSITE (B) 76.0
COMPOSITE (D) 83.2
TOTAL COMPOSITE CN 76
DA5-CROSSING AT RAIL SOUTH
SOIL GROUP COVER TYPE ACRES % CN %of DA
B Pvmt 1.06 0.07 98 1.00
Woods 1.30 0.09 66
Grass 111.86 0.83 79
TOTAL COMPOSITE CN I79

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA1-Stream Crossing at Road PREPARED BY: FLS
Drainage Area Info IM Drainage Area Tc Summary Data
DRAINAGE AREA ID: DA 1 Flow Type Length(ft) Elev.Diff. Tc
TOTAL BASIN LENGTH: 1980.7 ft Sheet Flow 100.0 0.50 17.4 mins.
TOTAL ELEVATION UP: 888.00 Shallow Concentrated Flow 1880.7 55.50 10.8 mins.
TOTAL ELEVATION DOWN: 832.00 Channel Flow-Rectangular 0.0 0.00 0.0 mins.
TOTAL ACRES: 74.73 Channel Flow-Triangular 0.0 0.00 0.0 mins.
Channel Flow-Trapezoidal 0.0 0.00 1 0.0 mins.
Channel Flow-Circular 0.0 0.00 0.0 mins.
Basin Totals1980.7 56.0028.1 mins.
This time of concentration calculation is based on survey data,aerial photography,and field investigation.
2. SHALLOW CONCENTRATED FLOW
Segment#1 Segment#2 Segment#3
Surface Description Grass Segment#1 Segment#2 Segment#3
Manning's"n" 0.16 Surface Description Paved Unpaved
2-Year,24-Hr.Rain Fall(In) 3.43 Flow Length(ft) 468.3 ft 1412.4 ft
Flow Length(ft) 100.0 ft Elevation Up(ft) 887.50 872.00
Elevation Up(ft) 888.00 Elevation Down(ft) 872.00 832.00
Elevation Down(ft) 887.50 Watercourse Slope(ft/ft) 0.033 0.028
Land Slope(ft/ft) 0.005 Average Velocity(ft/Sec) 3.7 2.7
Time Of Concentration(Mins) 17.35 Time Of Concentration(Mins) 2.11 8.67
Total Sheet Flow Tc(Minutes): 17.4 min. Total Shallow Concentrated Tc(Mins):j 10.8 min.
cApw rking\east01\d2277368\
PLI TOC.Asm DA 1-Road 4 of]8

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA1-Stream Crossing at Road PREPARED BY: FLS
3. CHANNEL FLOW-RECTANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"n"
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Rectangular Channel Tc(Mins): 0.0 mins.
4. CHANNEL FLOW-TRIANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Top Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Triangular Channel Tc 0.0 min.
cApw rking\east01\d2277368\
PLI TOCAsm DA 1-Road 5 of 18

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA1-Stream Crossing at Road PREPARED BY: FLS
5. CHANNEL FLOW-TRAPEZOIDAL CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Side Slopes(?H:1V)(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Trapezoidal Channel Tc 0.0 min.
6. CHANNEL FLOW-CIRCULAR CHANNEL(Gravity Flow)
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Pipe Diameter(In)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"n"
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Circular Channel Tc(Mins): 0.0 min.
7.Total Basin Time of Concentration (Mintues)
Total Basin Tc(Mins): 28.1 min.
cApw rking\east01\d2277368\
Pu TOCAsm DA 1-Road 6 of]8

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA2-Crossing at Road PREPARED BY: FLS
Drainage Area Infor 1. M Drainage Area Tc Summary Data
DRAINAGE AREA ID: DA 2 Flow Type Length(ft) Elev.Diff. Tc
TOTAL BASIN LENGTH: 367.1 ft Sheet Flow 100.0 1.00 13.1 mins.
TOTAL ELEVATION UP: 897.00 Shallow Concentrated Flow 267.1 8.00 1.6 mins.
TOTAL ELEVATION DOWN: 888.00 Channel Flow-Rectangular 0.0 0.00 0.0 mins.
TOTAL ACRES: 12.50 Channel Flow-Triangular 0.0 0.00 0.0 mins.
Channel Flow-Trapezoidal 0.0 0.00 0.0 mins.
Channel Flow-Circular 0.0 0.00 0.0 mins.
Basin Totals367.1 9.0014.7 mins.
This time of concentration calculation is based on survey data,aerial photography,and field investigation.
2. SHALLOW CONCENTRATED FLOW
Segment#1 Segment#2 Segment#3
Surface Description Grass Segment#1 Segment#2 Segment#3
Manning's"n" 0.16 Surface Description Unpaved
2-Year,24-Hr.Rain Fall(In) 3.43 Flow Length(ft) 267.1 ft
Flow Length(ft) 100.0 ft Elevation Up(ft) 896.00
Elevation Up(ft) 897.00 Elevation Down(ft) 888.00
Elevation Down(ft) 896.00 Watercourse Slope(ft/ft) 0.030
Land Slope(ft/ft) 0.010 Average Velocity(ft/Sec) 2.8
Time Of Concentration(Mins) 13.15 Time Of Concentration(Mins) 1.59
Total Sheet Flow Tc(Minutes): 13.1 min. Total Shallow Concentrated Tc(Mins):1 1.6 min.
cApw rking\east01\d2277368\
PLI TOC.Asm DA 2-Road 7 of]8

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA2-Crossing at Road PREPARED BY: FLS
3. CHANNEL FLOW-RECTANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Rectangular Channel Tc(Mins): 0.0 mins.
4. CHANNEL FLOW-TRIANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Top Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Triangular Channel Tc 0.0 min.
cApw orking\east01\d2277368\
PLI MCA— DA 2-Road 8 or 18

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA2-Crossing at Road PREPARED BY: FLS
5. CHANNEL FLOW-TRAPEZOIDAL CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Side Slopes(?H:1V)(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Trapezoidal Channel Tc 0.0 min.
6. CHANNEL FLOW-CIRCULAR CHANNEL(Gravity Flow)
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Pipe Diameter(In)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"n"
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Circular Channel Tc(Mins): 0.0 min.
7.Total Basin Time of Concentration (Mintues)
Total Basin Tc(Mins): 14.7 min.
cApw rking\east01\d2277368\
PLI TOCAsm DA 2-Road 9 of 18

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA3-Crossing at Road PREPARED BY: FLS
Drainage Area Info Drainage Area Tc Summary Data
DRAINAGE AREA ID: DA 3 Flow Type Length(ft) Elev.Diff. Tc
TOTAL BASIN LENGTH: 680.7 ft Sheet Flow 100.0 2.00 10.0 mins.
TOTAL ELEVATION UP: 897.00 Shallow Concentrated Flow 580.7 25.00 2.9 mins.
TOTAL ELEVATION DOWN: 870.00 Channel Flow-Rectangular 0.0 0.00 0.0 mins.
TOTAL ACRES: 15.59 Channel Flow-Triangular 0.0 0.00 0.0 mins.
Channel Flow-Trapezoidal 0.0 0.00 0.0 mins.
Channel Flow-Circular 0.0 0.00 0.0 mins.
Basin Totals •:i 12.9 mins.
This time of concentration calculation is based on survey data,aerial photography,and field investigation.
2. SHALLOW CONCENTRATED FLOW
Segment#1 Segment#2 Segment#3
Surface Description Grass Segment#1 Segment#2 Segment#3
Manning's"n" 0.16 Surface Description Unpaved
2-Year,24-Hr.Rain Fall(In) 3.43 Flow Length(ft) 580.7 ft
Flow Length(ft) 100.0 ft Elevation Up(ft) 895.00
Elevation Up(ft) 897.00 Elevation Down(ft) 870.00
Elevation Down(ft) 895.00 Watercourse Slope(ft/ft) 0.043
Land Slope(ft/ft) 0.020 Average Velocity(ft/Sec) 3.3
Time Of Concentration(Mins) 9.97 Time Of Concentration(Mins) 2.89
Total Sheet Flow Tc(Minutes): 10.0 min. Total Shallow Concentrated Tc(Mins):1 2.9 min.
cApw rking\east01\d2277368\
PLI TOC.Asm DA 3-Road 10 of 18

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA3-Crossing at Road PREPARED BY: FLS
3. CHANNEL FLOW-RECTANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Rectangular Channel Tc(Mins): 0.0 mins.
4. CHANNEL FLOW-TRIANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Top Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Triangular Channel Tc 0.0 min.
cApw orking\east01\d2277368\
PLI MCA— DA 3-Road I I or 18

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA3-Crossing at Road PREPARED BY: FLS
5. CHANNEL FLOW-TRAPEZOIDAL CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Side Slopes(?H:1V)(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Trapezoidal Channel Tc 0.0 min.
6. CHANNEL FLOW-CIRCULAR CHANNEL(Gravity Flow
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Pipe Diameter(In)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Circular Channel Tc(Mins): 0.0 min.
PLBasin Time of Concentration(Mintues)
Total Basin Tc(Mins): 12.9 min.
cApw rking\east01\d2277368\
PLI TOCAsm DA 3-Road 12 of]8

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA4-Stream Crossing at Railroad PREPARED BY: FLS
Drainage Area Info Drainage Area Tc Summary Data
DRAINAGE AREA ID: DA 4 Flow Type Length(ft) Elev.Diff. Tc
TOTAL BASIN LENGTH: 3117.8 ft Sheet Flow 100.0 0.50 17.4 mins.
TOTAL ELEVATION UP: 888.00 Shallow Concentrated Flow 730.3 25.50 3.5 mins.
TOTAL ELEVATION DOWN: 810.00 Channel Flow-Rectangular 0.0 0.00 0.0 mins.
TOTAL ACRES: 149.81 Channel Flow-Triangular 2287.5 52.00 6.8 mins.
Channel Flow-Trapezoidal 0.0 0.00 0.0 mins.
Channel Flow-Circular 0.0 0.00 0.0 mins.
Basin Totals3117.8 78.0027.7 mins.
This time of concentration calculation is based on survey data,aerial photography,and field investigation.
2. SHALLOW CONCENTRATED FLOW
Segment#1 Segment#2 Segment#3
Surface Description Grass Segment#1 Segment#2 Segment#3
Manning's"n" 0.16 Surface Description Paved Unpaved
2-Year,24-Hr.Rain Fall(In) 3.43 Flow Length(ft) 468.3 ft 262.0 ft
Flow Length(ft) 100.0 ft Elevation Up(ft) 887.50 872.00
Elevation Up(ft) 888.00 Elevation Down(ft) 872.00 862.00
Elevation Down(ft) 887.50 Watercourse Slope(ft/ft) 0.033 0.038
Land Slope(ft/ft) 0.005 Average Velocity(ft/Sec) 3.7 3.2
Time Of Concentration(Mins) 17.35 Time Of Concentration(Mins) 2.11 1.39
Total Sheet Flow Tc(Minutes): 17.4 min. Total Shallow Concentrated Tc(Mins):1 3.5 min.
cApw rking\east01\d2277368\
PLI TOCxlsm DA 4-Railroad 13 of]8

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA4-Stream Crossing at Railroad PREPARED BY: FLS
3. CHANNEL FLOW-RECTANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"n"
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Rectangular Channel Tc(Mins): 0.0 mins.
4. CHANNEL FLOW-TRIANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description Stream-Clean
Top Width(ft) 5.0
Depth(ft) 1.5
Area(Sq.ft) 3.8
Wetted Perimeter(ft) 5.8
Hydraulic Radius(ft) 0.6
Flow Length(ft) 2287.5
Elevation Up(ft) 862.00
Elevation Down(ft) 810.00
Channel Slope(ft/ft) 0.023
Manning's"no 0.030
Average Velocity(ft/Sec) 5.6
Time Of Concentration(Mins) 6.84
Total Triangular Channel Tc 6.8 min.
cApw rking\east01\d2277368\
PLI TOCAsm DA 4-Railroad 14 of 18

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA4-Stream Crossing at Railroad PREPARED BY: FLS
5. CHANNEL FLOW-TRAPEZOIDAL CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Side Slopes(?H:1V)(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Trapezoidal Channel Tc 0.0 min.
6. CHANNEL FLOW-CIRCULAR CHANNEL(Gravity Flow)
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Pipe Diameter(In)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"n"
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Circular Channel Tc(Mins): 0.0 min.
7.Total Basin Time of Concentration (Mintues)
Total Basin Tc(Mins): 27.7 min.
cApw rking\east01\d2277368\
PLI TOCAsm DA 4-Railroad 15 of 18

12/10/2021
Time of Concentration Worksheet F:)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA5-Stream Crossing at Railroad PREPARED BY: BSS
Drainage Area Info Drainage Area Tc Summary Data
DRAINAGE AREA ID: DA 5 Flow Type Length(ft) Elev.Diff. Tc
TOTAL BASIN LENGTH: 1025.0 ft Sheet Flow 100.0 1.50 11.2 mins.
TOTAL ELEVATION UP: 915.00 Shallow Concentrated Flow 925.0 34.50 4.9 mins.
TOTAL ELEVATION DOWN: 879.00 Channel Flow-Rectangular 0.0 0.00 0.0 mins.
TOTAL ACRES: 14.22 Channel Flow-Triangular 0.0 0.00 0.0 mins.
Channel Flow-Trapezoidal 0.0 0.00 0.0 mins.
Channel Flow-Circular 0.0 0.00 0.0 mins.
Basin Totals1025.0 36.0016.1 mins.
This time of concentration calculation is based on survey data,aerial photography,and field investigation.
2. SHALLOW CONCENTRATED FLOW
Segment#1 Segment#2 Segment#3
Surface Description Grass Segment#1 Segment#2 Segment#3
Manning's"n" 0.16 Surface Description Unpaved
2-Year,24-Hr.Rain Fall(In) 3.43 Flow Length(ft) 925.0 ft
Flow Length(ft) 100.0 ft Elevation Up(ft) 913.50
Elevation Up(ft) 915.00 Elevation Down(ft) 879.00
Elevation Down(ft) 913.50 Watercourse Slope(ft/ft) 0.037
Land Slope(ft/ft) 0.015 Average Velocity(ft/Sec) 3.1
Time Of Concentration(Mins) 11.18 Time Of Concentration(Mins) 4.95
Total Sheet Flow Tc(Minutes): 11.2 min. Total Shallow Concentrated Tc(Mins):1 4.9 min.
cApw rking\east01\d2277368\
PLI TOCxlsm DA 5-Railroad South 16 ofls

12/10/2021
Time of Concentration Worksheet K)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA5-Stream Crossing at Railroad PREPARED BY: BSS
3. CHANNEL FLOW-RECTANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"n"
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Rectangular Channel Tc(Mins): 0.0 rains.
4. CHANNEL FLOW-TRIANGULAR CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Top Width(ft)
Depth(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Triangular Channel Tc 0.0 min.
cApw rking\east01\d2277368\
PLI TOCAsm DA 5-Railroad South 17 of1s

12/10/2021
Time of Concentration Worksheet K)R
SCS TR-55 Method
PROJECT: PLI DATE: 12/10/21
SCENARIO: DA5-Stream Crossing at Railroad PREPARED BY: BSS
5. CHANNEL FLOW-TRAPEZOIDAL CHANNEL
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Bottom Width(ft)
Depth(ft)
Side Slopes(?H:1V)(ft)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"no
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Trapezoidal Channel Tc 0.0 min.
6. CHANNEL FLOW-CIRCULAR CHANNEL(Gravity Flow)
Segment#1 Segment#2 Segment#3 Segment#4 Segment#5 Segment#6 Segment#7 Segment#8 Segment#9
Surface Description
Pipe Diameter(In)
Area(Sq.ft)
Wetted Perimeter(ft)
Hydraulic Radius(ft)
Flow Length(ft)
Elevation Up(ft)
Elevation Down(ft)
Channel Slope(ft/ft)
Manning's"n"
Average Velocity(ft/Sec)
Time Of Concentration(Mins)
Total Circular Channel Tc(Mins): 0.0 min.
7.Total Basin Time of Concentration (Mintues)
Total Basin Tc(Mins): 16.1 min.
cApw rking\east01\d2277368\
PLI TOCAsm DA 5-Railroad South 18 ores

This page intentionally left blank.

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix F—NOAA Rainfall Data
Appendix F — NOAA Rainfall
Data

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations
Appendix F—NOAA Rainfall Data
This page intentionally left blank.

NOAA Atlas 14,Volume 2,Version 3
' Location name:Crouse,North Carolina,USA*
Latitude:35.3949*, Longitude: -81.32140
Elevation: 809.16 ft**
source:ESRI Maps m y�
**source:USGS
POINT PRECIPITATION FREQUENCY ESTIMATES
G.M.Bonnin,D.Martin,B.Lin,T.Parzybok,M.Yekta,and D.Riley
NOAA,National Weather Service,Silver Spring,Maryland
PF tabular I PF graphical I Maps & aerials
PF tabular
PDS-based point precipitation frequency estimates with 90% confidence intervals (in inches/hourp
Average recurrence interval(years)
Duration 1� 100
����
2 5 10 25 50 200 500 1000
5-min 4.70 1 5.57 6.55 7.28 8.18 F 8.84 9.49 10.1 10.9 11.5
(4.32-5.14) 1 (5.11-6.08) 1 (6.00-7.15) (6.65-7.94) (7.43-8.93) 1 (7.98-9.65) (8.51-10.4) 1 (8.99-11.1) 1 (9.56-12.0) 1 (9.97-12.7)
10-min 3.76 4.46 5.25 5.83 6.53 7.04 7.54 -----IF8.60 9.03
(3.46-4.10) 11 (4.09-4.87) 1 (4.80-5.73) (5.32-6.35) (5.92-7.12) 11 (6.35-7.69) (6.76-8.24) 1 (7.13-8.77) 1 (7.56-9.46) 1 (7.85-9.98)
15-min 3.13 3.74 4.42 4.92 5.52 5.95 6.35 6.74 7.22 7.56
(2.88-3.42) (3.43-4.08) 1 (4.05-4.83) 1 (4.48-5.36) 1 (5.00-6.01) 1 (5.36-6.49) 1 (5.70-6.94) 11 (6.00-7.38) 1 (6.34-7.94) 11 (6.57-8.35)
30-min 2.15 2.58 3.14 3.56 4.08 4.48 4.87 5.24 5.74 6.12
(1.97-2.34) (2.37-2.82) 1 (2.88-3.43) 1 (3.25-3.88) 1 (3.71-4.45) 1 (4.04-4.89) 1 (4.36-5.31) 1 (4.67-5.74) 1 (5.05-6.32) 1 (5.32-6.76)
60-min 1.34 1.62 2.02 2.32 2.72 3.03 3.35 3.68 4.12 4.47
(1.23-1.46) 1 (1.49-1.77) 1 (1.84-2.20) 1 (2.12-2.53) 1 (2.47-2.96) 1 (2.74-3.31) (3.01-3.66) (3.27-4.03) (3.62-4.53) 11 (3.88-4.94)
2-hr 0.780 0.946 1.19 1.37 1.63 1.84 2.05 2.27 2.58 2.84
(0.714-0.854) (0.866-1.04) 1 (1.08-1.30) 1 (1.25-1.50) 1 (1.48-1.78) 1 (1.65-2.01) 1 (1.83-2.25) (2.02-2.50) (2.26-2.85) (2.45-3.15)
3-hr 0.555 0.671 0.844 0.982 1.18 1.34 ( 1.51 1.69 1.95 2.16
(0.508-0.611) (0.614-0.739) (0.770-0.929) (0.892-1.08) (1.06-1.29) (1.20-1.47) 1.34-1.66) (1.49-1.86) 1 (1.68-2.16) 1 (1.85-2.41)
6-hr 0.342 0.411 0.515 0.599 0.718 0.817 0.921 1.03 1.20 1.33
(0.314-0.373) (0.378-0.451) (0.472-0.564) (0.547-0.654) (0.651-0.784) (0.736-0.892)1(0.822-1.01) (0.913-1.13) 1 (1.04-1.32) 1 (1.14-1.47)
12-hr 0.206 0.248 0.311 0.362 0.433 0.492 0.554 0.620 0.715 0.794
(0.190-0.224) (0.229-0.271) (0.286-0.339) (0.331-0.394) (0.394-0.471) (0.444-0.535) (0.496-0.602) (0.549-0.675) (0.624-0.780) (0.683-0.868)
24-hr 0.124 0.150 0.188 0.219 0.260 0.294 0.328 0.364 0.413 0.453
(0.115-0.133) (0.140-0.161) (0.175-0.202) (0.203-0.235) (0.241-0.279) (0.271-0.315) (0.302-0.352) (0.333-0.391) (0.377-0.444) (0.411-0.487)
2-day 0.073 0.088 ) ( 0.111 0.128 0.152 ) ( 0.171 ) 0.190 ) 0.210 0.238 0.260
(0.068-0.079) (0.082-0.095 0.103-0.119) (0.119-0.137) (0.140-0.163 0.157-0.183 (0.175-0.204 (0.193-0.226) (0.217-0.256) (0.236-0.280)
3-day 0.052 0.062 0.078 0.089 0.106 0.119 0.132 IF 0.146 F 0.164 F 0.1 99
(0.048-0.056) (0.058-0.067) (0.072-0.083) (0.083-0.096) (0.098-0.113) (0.110-0.127) (0.121-0.141) (0.134-0.156) (0.150-0.177) (0.163-0.193)
4-day 0.041 0.049 0.061 0.070 0.083 0.093 0.103 0.113 0.128 0.139
(0.038-0.044) (0.046-0.053) (0.057-0.065) (0.065-0.075) (0.077-0.089) (0.086-0.099) (0.095-0.110) (0.104-0.121) (0.117-0.137) (0.127-0.149)
7-day 0.027 0.033 0.040 0.045 0.053 0.059 0.065 F 0.072 70.080 F 0.087
(0.026-0.029) (0.030-0.035) (0.037-0.042) (0.042-0.048) (0.049-0.056) (0.055-0.063) (0.061-0.069) (0.066-0.076) (0.074-0.086) (0.080-0.093)
10-day 0.022 0.026 0.031 0.035 0.041 0.045 0.049 IF 0.054 F 0.060 F 0.0 44
(0.021-0.023) (0.024-0.027) (0.029-0.033) (0.033-0.037) (0.038-0.043) (0.042-0.048) (0.046-0.052) (0.050-0.057) (0.055-0.063) (0.059-0.068)
20-day 0.015 0.017 0.020 0.023 0.026 0.029 0.031 0.034 0.037 0.040
(0.014-0.015) (0.016-0.018) (0.019-0.021) (0.021-0.024) (0.024-0.027) (0.027-0.030) (0.029-0.033) (0.032-0.036) (0.035-0.039) (0.037-0.042)
F��d:a:y] 0.012 0.014 0.016 0.018 0.020 0.022 0.024 0.025 0.028 0.029
(0.011-0.012) (0.013-0.015) (0.015-0.017) (0.017-0.019) (0.019-0.021) (0.021-0.023) (0.022-0.025) (0.024-0.027) (0.026-0.029) (0.028-0.031)
--[45-day 0.010 0.012 0.013 0.015 0.016 0.017 0.019 0.020 0.021 0.022
(0.010-0.010) (0.011-0.012) (0.013-0.014) (0.014-0.015) (0.015-0.017) (0.017-0.018) (0.018-0.019) (0.019-0.021) (0.020-0.022) (0.021-0.024)
�-day 0.009 0.010 0.012 0.013 0.014 0.015 0.016 0.017 0.018 0.019
(0.009-0.009) (0.010-0.011) (0.011-0.012) (0.012-0.013) (0.013-0.015) (0.014-0.016) (0.015-0.017) (0.016-0.018) (0.017-0.019) (0.018-0.020)
Precipitation frequency(PF)estimates in this table are based on frequency analysis of partial duration series(PDS).
Numbers in parenthesis are PF estimates at lower and upper bounds of the 90%confidence interval.The probability that precipitation frequency estimates(for a
given duration and average recurrence interval)will be greater than the upper bound(or less than the lower bound)is 5%.Estimates at upper bounds are not
checked against probable maximum precipitation(PMP)estimates and may be higher than currently valid PIMP values.
Please refer to NOAA Atlas 14 document for more information.
Back to Top
PF graphical

PDS-based intensity-duration-frequency (IDF) curves
Latitude: 35.39491, Longitude: -31.32141
100-000
Average recurrence
Ynlerval
10-000 '....:.....:.... ... --- (years)
L
2
1.000 -------- ........ .......... --- — 5
di
C 1Q
G 25
i
�2 0.100 -------
_---------
+� 50
V
a 2Qd
0.010 _____ ______________________ ___ —
500
- 10UU
0-001
L L L L L rp rq r4 M r4 r4 rp r9 r4
o o o A A 46 H A4 � a o o �o
,4 ,4 m w H N rn v Ln
Duration
100-000
10-000 ................................................. ....
Duration
ZI
1-000 ..... .... .... ....................... ................. — "in — 2-day
76-min — 3-day
C
I5-min — 4-day
}°- 0-100 . ........ ..... . ---- ...... ----.. — 30�-min — 7-day
— 60-min — 10-eay
— 2-nr — 2D-clay
a0-010 :. :_._._.._.: ---- - — 3-hr — 3OL--day
— 6-hr — 45-day
— 12-hr — 6o-eay
0-001 — 24-hr
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval (years)
NDAAAtlas 14,Volume 2,Version 3 Created{GMTY Tue May 31 19:17:12 2022
Back to Top
Maps & aerials
Small scale terrain

.8 ",at Crouse rous
clierryvillE
3km
.Large scale terrain
KingS13011' Bristol
Johnson city*
Dul
Greensboro
L
1A NORTH C A P,0 L I N A
Charlotte
'Greenville `
100krn OUTH CAROLINA
Large scale map
B11A.-I
Johnson City
Winston-Salem Greensbou
Ash Fie North
Carolina
arlotte
100krn
M1
Large scale aerial

_KingsWrt Bri sti
J. i
Greensboro Durh
AsheyiLle
North
Ue
'LK&iotte
I -
700km
60mi
Back to Top
US Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring,MD 20910
Questions?:[e-mail]
Disclaimer

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix G—Sediment Basin Calculations
Appendix G — Sediment
Basin Calculations

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations
Appendix G—Sediment Basin Calculations
This page intentionally left blank.

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-201
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 11.16 ac 10 Yr Peak Flow(Q10) 48.61 cfs
Disturbed area(DA) 8.90 ac 25 Yr Peak Flow(Q25) 54.77 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 23,826 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 20,088 cf
10 Yr Storm Rainfall Intensity(i)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 833.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.50 ft 833.00 0.00 20,173 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 834.00 1.00 22,098 21,128
Depth of Flow over Emergency Spillway 0.50 ft 834.25 1.25 22,588 26,714
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 835.00 2.00 24,079 44,211
835.50 2.50 25,091 56,503
Basin Configuration 836.00 3.00 26,116 69,304
Bottom Elevation 833.00 msl 836.50 3.50 27,157 82,621
Sediment Storage Elevation 835.50 msl 837.00 4.00 28,211 96,462
Riser Crest 835.50 msl 838.00 5.00 30,362 125,742
Emergency Spillway Crest 836.50 msl
Top of Berm 838.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 25,091 sf
Desired Skimmer Drawdown Rate(Qd) 6,696 ft3/day Basin Storage Volume Provided Below Spillway Crest 56,503 cf
Skimmer Size 5.0 in
Head on Orifice(H)5 0.333 ft
Calculated Orifice Diameter' 2.241 in
Actual Orifice Diameter' 2.250 in
Actual Skimmer Drawdown Time' 71 hrs
Riser Structure
Riser Inside Dimension(square) 6 ft Riser Flow as Weir13 62.00 cfs
Barrel Diameter' DOUBLE 30 in Riser Flow as Orifice14 120.37 cfs
Barrel Invert Elevation 832.50 msl
Barrel Length 70.00 ft Barrel Flow as Orifice14 78.39 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 62.37 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 62.00 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow -7.23 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length13 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 13770 Ibs
Concrete Anchor Width 8.0 ft Weight of Concrete Anchor 18560 Ibs
Concrete Anchor Length 8.0 ft
Concrete Anchor Thickness 2.00 ft Safety Factor19 1.3
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 1 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control
Q=a [1+Km+K,L
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 2 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-202
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 5.65 ac 10 Yr Peak Flow(Q10) 24.61 cfs
Disturbed area(DA) 5.79 ac 25 Yr Peak Flow(Q25) 27.73 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 12,063 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 10,170 cf
10 Yr Storm Rainfall Intensity(i)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 825.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.50 ft 825.00 0.00 9,393 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 826.00 1.00 11,000 10,186
Depth of Flow over Emergency Spillway 0.50 ft 826.25 1.25 11,411 12,987
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 827.00 2.00 12,665 22,012
827.50 2.50 13,518 28,556
Basin Configuration 828.00 3.00 14,386 35,531
Bottom Elevation 825.00 msl 828.50 3.50 15,267 42,943
Sediment Storage Elevation 827.50 msl 829.00 4.00 16,162 50,799
Riser Crest 827.50 msl 830.00 5.00 17,996 67,870
Emergency Spillway Crest 828.50 msl
Top of Berm 830.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 13,518 sf
Desired Skimmer Drawdown Rate(Qd) 3,390 ft3/day Basin Storage Volume Provided Below Spillway Crest 28,556 cf
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft
Calculated Orifice Diameter' 1.441 in
Actual Orifice Diameter' 1.500 in
Actual Skimmer Drawdown Time' 66 hrs
Riser Structure
Riser Inside Dimension(square) 4 ft Riser Flow as Weir13 37.20 cfs
Barrel Diameter' DOUBLE 24 in Riser Flow as Orifice14 43.33 cfs
Barrel Invert Elevation 824.50 msl
Barrel Length 50.00 ft Barrel Flow as Orifice14 52.40 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 42.13 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 37.20 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow -9.47 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length" 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 7821 Ibs
Concrete Anchor Width 7.0 ft Weight of Concrete Anchor 10658 Ibs
Concrete Anchor Length 7.0 ft
Concrete Anchor Thickness 1.50 ft Safety Factor19 1.4
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 3 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 4 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-203
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 3.93 ac 10 Yr Peak Flow(Q10) 17.12 cfs
Disturbed area(DA) 3.93 ac 25 Yr Peak Flow(Q25) 19.29 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 8,390 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 7,074 cf
10 Yr Storm Rainfall Intensity i 4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 808.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.50 ft 808.00 0.00 5,857 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 809.00 1.00 7,118 6,477
Depth of Flow over Emergency Spillway 0.50 ft 809.25 1.25 7,442 8,297
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 810.00 2.00 8,435 14,247
810.50 2.50 9,115 18,634
Basin Configuration 811.00 3.00 9,809 23,363
Bottom Elevation 808.00 msl 811.50 3.50 10,517 28,444
Sediment Storage Elevation 810.50 msl 812.00 4.00 11,239 33,882
Riser Crest 810.50 msl 813.00 5.00 12,726 45,857
Emergency Spillway Crest 811.50 msl
Top of Berm 813.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 9,115 sf
Desired Skimmer Drawdown Rate(Qd) 2,358 ft'/day Basin Storage Volume Provided Below Spillway Crest 18,634 cf
Skimmer Size 6.0 in
Head on Orifice(H)5 0.417 ft
Calculated Orifice Diameter' 1.257 in
Actual Orifice Diameter' 1.250 in
Actual Skimmer Drawdown Time' 73 hrs
Riser Structure
Riser Inside Dimension(square) 4 ft Riser Flow as Weir13 37.20 cfs
Barrel Diameter' 24 in Riser Flow as Orifice14 43.33 cfs
Barrel Invert Elevation 807.80 msl
Barrel Length 50.00 ft Barrel Flow as Orifice14 24.86 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 19.99 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 19.99 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow -0.70 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length13 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 5860 Ibs
Concrete Anchor Width 6.0 ft Weight of Concrete Anchor 7830 Ibs
Concrete Anchor Length 6.0 ft
Concrete Anchor Thickness 1.50 ft Safety Factor19 1.3
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 5 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 6 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-204
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 8.00 ac 10 Yr Peak Flow(Q10) 34.85 cfs
Disturbed area(DA) 8.00 ac 25 Yr Peak Flow(Q25) 39.26 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 17,080 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 14,400 cf
10 Yr Storm Rainfall Intensity(i)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 813.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.50 ft 813.00 0.00 12,899 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 814.00 1.00 14,609 13,745
Depth of Flow over Emergency Spillway 0.50 ft 814.25 1.25 15,045 17,452
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 815.00 2.00 16,375 29,231
815.50 2.50 17,279 37,643
Basin Configuration 816.00 3.00 18,198 46,511
Bottom Elevation 813.00 msl 816.50 3.50 19,130 55,843
Sediment Storage Elevation 815.50 msl 817.00 4.00 20,007 65,626
Riser Crest 815.50 msl 818.00 5.00 22,013 86,628
Emergency Spillway Crest 816.50 msl
Top of Berm 818.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 17,279 sf
Desired Skimmer Drawdown Rate(Qd) 4,800 ft3/day 113asin Storage Volume Provided Below Spillway Crest 37,643 cf
Skimmer Size 6.0 in
Head on Orifice(H)5 0.417 ft
Calculated Orifice Diameter' 1.794 in
Actual Orifice Diameter' 1.750 in
Actual Skimmer Drawdown Time' 76 hrs
Riser Structure
Riser Inside Dimension(square) 4 ft Riser Flow as Weir13 37.20 cfs
Barrel Diameter' DOUBLE 24 in Riser Flow as Orifice14 43.33 cfs
Barrel Invert Elevation 812.50 msl
Barrel Length 50.00 ft Barrel Flow as Orifice14 52.40 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 42.13 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 37.20 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow 2.06 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length" 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 7821 Ibs
Concrete Anchor Width 7.0 ft Weight of Concrete Anchor 10658 Ibs
Concrete Anchor Length 7.0 ft
Concrete Anchor Thickness 1.50 ft Safety Factor19 1.4
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 7 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 8 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-205
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 4.50 ac 10 Yr Peak Flow(Q10) 19.60 cfs
Disturbed area(DA) 4.50 ac 25 Yr Peak Flow(Q25) 22.09 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 9,607 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 8,100 cf
10 Yr Storm Rainfall Intensity i 4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 828.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 1.80 ft 828.00 0.00 8,809 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 828.90 0.90 10,182 8,538
Depth of Flow over Emergency Spillway 0.20 ft 829.00 1.00 10,387 9,567
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 829.80 1.80 11,661 18,381
830.00 2.00 12,048 20,752
Basin Configuration 830.80 2.80 13,380 30,919
Bottom Elevation 828.00 msl 831.00 3.00 13,778 33,634
Sediment Storage Elevation 829.80 msl 832.00 4.00 15,576 48,302
Riser Crest 829.80 msl
Emergency Spillway Crest 830.80 msl
Top of Berm 832.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 11,661 sf
Desired Skimmer Drawdown Rate(Qd) 2,700 ft'/day Basin Storage Volume Provided Below Spillway Crest 18,381 cf
Skimmer Size 5.0 in
Head on Orifice(H)5 0.333 ft
Calculated Orifice Diameter' 1.423 in
Actual Orifice Diameter' 1.500 in
Actual Skimmer Drawdown Time' 65 hrs
Riser Structure
Riser Inside Dimension(square) 4 ft Riser Flow as Weir13 37.20 cfs
Barrel Diameter' 24 in Riser Flow as Orifice14 43.33 cfs
Barrel Invert Elevation 826.80 msl
Barrel Length 50.00 ft Barrel Flow as Orifice14 26.20 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 21.07 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 21.07 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow 1.02 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length13 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 4768 Ibs
Concrete Anchor Width 5.5 ft Weight of Concrete Anchor 6579 Ibs
Concrete Anchor Length 5.5 ft
Concrete Anchor Thickness 1.50 ft Safety Factor19 1.4
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 9 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 10 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-206
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 5.50 ac 10 Yr Peak Flow(Q10) 23.96 cfs
Disturbed area(DA) 5.50 ac 25 Yr Peak Flow(Q25) 26.99 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 11,742 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 9,900 cf
10 Yr Storm Rainfall Intensity i 4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 833.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 1.80 ft 833.00 0.00 10,804 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 833.90 0.90 12,251 10,368
Depth of Flow over Emergency Spillway 0.20 ft 834.00 1.00 12,538 11,607
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 834.80 1.80 13,893 22,175
835.00 2.00 14,357 25,000
Basin Configuration 835.80 2.80 15,785 37,052
Bottom Elevation 833.00 msl 836.00 3.00 16,253 40,256
Sediment Storage Elevation 834.80 msl 837.00 4.00 18,226 57,486
Riser Crest 834.80 msl
Emergency Spillway Crest 835.80 msl
Top of Berm 837.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 13,893 sf
Desired Skimmer Drawdown Rate(Qd) 3,300 ft3/day Basin Storage Volume Provided Below Spillway Crest 22,175 cf
Skimmer Size 6.0 in
Head on Orifice(H)5 0.417 ft
Calculated Orifice Diameter' 1.487 in
Actual Orifice Diameter' 1.500 in
Actual Skimmer Drawdown Time' 71 hrs
Riser Structure
Riser Inside Dimension(square) 6 ft Riser Flow as Weir13 62.00 cfs
Barrel Diameter' 36 in Riser Flow as Orifice14 120.37 cfs
Barrel Invert Elevation 831.00 msl
Barrel Length 50.00 ft Barrel Flow as Orifice14 61.83 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 56.41 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 56.41 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow -29.41 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length13 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 9914 Ibs
Concrete Anchor Width 7.5 ft Weight of Concrete Anchor 16313 Ibs
Concrete Anchor Length 7.5 ft
Concrete Anchor Thickness 2.00 ft Safety Factor19 1.6
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 11 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 12 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-207
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 5.79 ac 10 Yr Peak Flow(Q10) 25.22 cfs
Disturbed area(DA) 5.79 ac 25 Yr Peak Flow(Q25) 28.42 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 12,362 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 10,422 cf
10 Yr Storm Rainfall Intensity(i)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 843.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.50 ft 843.00 0.00 10,116 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 844.00 1.00 11,727 10,912
Depth of Flow over Emergency Spillway 0.50 ft 844.25 1.25 12,139 13,895
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 845.00 2.00 13,395 23,466
845.50 2.50 14,250 30,376
Basin Configuration 846.00 3.00 15,119 37,717
Bottom Elevation 843.00 msl 846.50 3.50 16,003 45,497
Sediment Storage Elevation 845.50 msl 847.00 4.00 16,900 53,722
Riser Crest 845.50 msl 848.00 5.00 18,737 71,532
Emergency Spillway Crest 846.50 msl
Top of Berm 848.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 14,250 sf
Desired Skimmer Drawdown Rate(Qd) 3,474 ft3/day Basin Storage Volume Provided Below Spillway Crest 30,376 cf
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft
Calculated Orifice Diameter' 1.458 in
Actual Orifice Diameter' 1.500 in
Actual Skimmer Drawdown Time' 68 hrs
Riser Structure
Riser Inside Dimension(square) 4 ft Riser Flow as Weir13 37.20 cfs
Barrel Diameter' 24 in Riser Flow as Orifice14 43.33 cfs
Barrel Invert Elevation 841.20 msl
Barrel Length 50.00 ft Barrel Flow as Orifice14 31.37 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 25.22 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 25.22 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow 3.20 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length" 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 5860 Ibs
Concrete Anchor Width 6.0 ft Weight of Concrete Anchor 7830 Ibs
Concrete Anchor Length 6.0 ft
Concrete Anchor Thickness 1.50 ft Safety Factor19 1.3
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 13 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 14 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin:
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 5.65 ac 10 Yr Peak Flow(Q10) 24.61 cfs
Disturbed area(DA) 5.50 ac 25 Yr Peak Flow(Q25) 27.73 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 12,063 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 10,170 cf
10 Yr Storm Rainfall Intensity(i)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 874.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.50 ft 874.00 0.00 9,033 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 875.00 1.00 10,632 9,822
Depth of Flow over Emergency Spillway 0.50 ft 875.25 1.25 11,034 12,530
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 876.00 2.00 12,665 21,410
876.50 2.50 13,155 27,864
Basin Configuration 877.00 3.00 14,061 34,667
Bottom Elevation 874.00 msl 877.50 3.50 14,964 41,922
Sediment Storage Elevation 876.50 msl 878.00 4.00 15,868 49,629
Riser Crest 876.50 msl 879.00 5.00 17,718 66,414
Emergency Spillway Crest 877.50 msl
Top of Berm 879.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 13,155 sf
Desired Skimmer Drawdown Rate(Qd) 3,390 ft3/day Basin Storage Volume Provided Below Spillway Crest 27,864 cf
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft
Calculated Orifice Diameter' 1.441 in
Actual Orifice Diameter' 1.500 in
Actual Skimmer Drawdown Time' 66 hrs
Riser Structure
Riser Inside Dimension(square) 6 ft Riser Flow as Weir13 62.00 cfs
Barrel Diameter' DOUBLE 24 in Riser Flow as Orifice14 120.37 cfs
Barrel Invert Elevation 873.50 msl
Barrel Length 50.00 ft Barrel Flow as Orifice14 52.40 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 42.13 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 42.13 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow -14.40 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length" 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 11565 Ibs
Concrete Anchor Width 7.5 ft Weight of Concrete Anchor 16313 Ibs
Concrete Anchor Length 7.5 ft
Concrete Anchor Thickness 2.00 ft Safety Factor19 1.4
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 15 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 16 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-209-Phase 1
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 6.40 ac 10 Yr Peak Flow(Q10) 27.88 cfs
Disturbed area(DA) 6.40 ac 25 Yr Peak Flow(Q25) 31.41 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 13,664 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 11,520 cf
10 Yr Storm Rainfall Intensity(i)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 824.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 1.50 ft 824.00 0.00 11,576 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 824.75 0.75 12,743 9,116
Depth of Flow over Emergency Spillway 0.50 ft 825.00 1.00 13,138 12,351
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 825.50 1.50 13,941 19,120
826.00 2.00 14,757 26,293
Basin Configuration 826.50 2.50 15,401 33,832
Bottom Elevation 824.00 msl 827.00 3.00 16,432 41,789
Sediment Storage Elevation 825.50 msl 828.00 4.00 18,164 59,080
Riser Crest 825.50 msl
Emergency Spillway Crest 826.50 msl
Top of Berm 828.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 13,941 sf
Desired Skimmer Drawdown Rate(Qd) 3,840 ft3/day Basin Storage Volume Provided Below Spillway Crest 19,120 cf
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft
Calculated Orifice Diameter' 1.533 in
Actual Orifice Diameter' 1.500 in
Actual Skimmer Drawdown Time' 75 hrs
Riser Structure
Riser Inside Dimension(square) 6 ft Riser Flow as Weir13 62.00 cfs
Barrel Diameter' 30 in Riser Flow as Orifice14 120.37 cfs
Barrel Invert Elevation 822.00 msl
Barrel Length 50.00 ft Barrel Flow as Orifice14 42.61 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 36.89 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 36.89 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow -5.48 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length" 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 7649 Ibs
Concrete Anchor Width 7.0 ft Weight of Concrete Anchor 10658 Ibs
Concrete Anchor Length 7.0 ft
Concrete Anchor Thickness 1.50 ft Safety Factor19 1.4
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 17 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 18 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Riser Sediment Basin: SB-210-Phase 1
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)1 10.65 ac 10 Yr Peak Flow(Q10) 46.39 cfs
Disturbed area(DA) 6.00 ac 25 Yr Peak Flow(Q25) 52.27 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 22,738 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 19,170 cf
10 Yr Storm Rainfall Intensity(i)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)4 8.2 in/hr
Design Criteria Basin Size
Bottom Elevation 880.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.50 ft 880.00 0.00 20,173 0
Depth of Flow over Riser(1 ft min)5 1.00 ft 881.00 1.00 22,098 21,128
Depth of Flow over Emergency Spillway 0.50 ft 881.25 1.25 22,588 26,714
25 Yr Storm Freeboard(1 ft req'd)5 1.00 ft 882.00 2.00 24,079 44,211
882.50 2.50 25,091 56,503
Basin Configuration 883.00 3.00 26,116 69,304
Bottom Elevation 880.00 msl 883.50 3.50 27,157 82,621
Sediment Storage Elevation 882.50 msl 884.00 4.00 28,211 96,462
Riser Crest 882.50 msl 885.00 5.00 30,326 125,724
Emergency Spillway Crest 883.50 msl
Top of Berm 885.00 msl
Skimmer Outlet Basin Size Check
Desired Skimmer Drawdown Time(td)6 72 hrs Basin Surface Area Provided at Spillway Crest 25,091 sf
Desired Skimmer Drawdown Rate(Qd) 6,390 ft3/day 113asin Storage Volume Provided Below Spillway Crest 56,503 cf
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft
Calculated Orifice Diameter' 1.978 in
Actual Orifice Diameter' 2.000 in
Actual Skimmer Drawdown Time' 70 hrs
Riser Structure
Riser Inside Dimension(square) 6 ft Riser Flow as Weir13 62.00 cfs
Barrel Diameter' DOUBLE 24 in Riser Flow as Orifice14 120.37 cfs
Barrel Invert Elevation 879.50 msl
Barrel Length 30.00 ft Barrel Flow as Orifice14 52.40 cfs
Barrel Manning's N10 0.025 Barrel Flow as Pipe15 47.52 cfs
Sharp Crested Weir Coefficient(C)11 3.1
Orifice Coefficient(C)12 0.6 Controlling Flow through Riser and Barrel Spillway 47.52 cfs
Emergency Spillway Design
Minimum Allowable Spillway Length16 20 ft Difference b/n 25 Yr Peak Flow and Riser/Barrel Flow 4.75 cfs
Broad Crested Weir Coefficient(C)17 2.80 Ell Design Spillway Length" 20 ft
Riser Concrete Anchor Design
Length of Exposed Outlet Pipe 10 ft Buoyancy18 11565 Ibs
Concrete Anchor Width 7.5 ft Weight of Concrete Anchor 16313 Ibs
Concrete Anchor Length 7.5 ft
Concrete Anchor Thickness 2.00 ft Safety Factor19 1.4
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
Page 19 of 51

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,hftp://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.61-Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Skimmer orifice equatic I
D= V Qa/(2370*V H) (inches) (see note 5)
8.Actual skimmer orifice diameter is rounded to the nearest 1/4 inch.
9.Riser cross-sectional area is required to be more than 1.5 times the barrel cross-sectional area.
10.Use 0.025 for CMP and 0.013 for RCP.
11.3.1 for sharp-crested wiers.
12.0.6 for sharp-edged orifice.
13.Weir equation: Q= CLH's (see note 11)
14.Orifice equation: Q=CA(2gH)R5 (see note 12)
15.Pipe Flow equation: 2gh O5 *See
Q=a [1+Km+KPL
16.Minimum allowable emergency spillway length is 20 feet(see note 5).
17.2.80 is the maximum allowable coefficient per Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
18.Weight of water displaced by riser and exposed outlet pipe.
19.Minimum safety factor is 1.25,exceeding requirements of Section 8.07-Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Mar
Page 20 of 51

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix H—Sediment Trap and Skimmer Basin Calculations
Appendix H — Sediment Trap
and Skimmer Basin
Calculations

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations
Appendix H—Sediment Trap and Skimmer Basin Calculations
This page intentionally left blank.

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST-220
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.55 ac 10 Yr Peak Flow(Q10) 2.40 cfs
Disturbed area(DA) 0.55 ac 25 Yr Peak Flow(Q25) 2.70 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 1,174 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (3600 cf per ac of TDA)5 1,980 cf
10 Yr Storm Rainfall Intensity(1)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST-220
Bottom Elevation 889.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 889.00 0.00 852 0
890.00 1.00 1,091 969
891.00 2.00 1,355 2,190
892.00 3.00 1,645 3,687
893.00 4.00 1,960 5,488
Basin Configuration
Bottom Elevation 889.00 msl
Sediment Storage Elevation/Spillway 891.00 msl
Top of Berm 893.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 Basin Surface Area Provided at Spillway Crest 1,355 sf
2 6 113asin Storage Volume Provided Below Spillway Crest 2,190 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 24 of 51

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST-221
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.51 ac 10 Yr Peak Flow(Q10) 2.22 cfs
Disturbed area(DA) 0.51 ac 25 Yr Peak Flow(Q25) 2.50 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 1,089 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (3600 cf per ac of TDA)5 1,836 cf
10 Yr Storm Rainfall Intensity(1)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST-221
Bottom Elevation 884.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 884.00 0.00 778 0
885.00 1.00 1,032 902
886.00 2.00 1,317 2,074
887.00 3.00 1,632 3,545
888.00 4.00 1,978 5,348
Basin Configuration
Bottom Elevation 884.00 msl
Sediment Storage Elevation/Spillway 886.00 msI-
Top of Berm 888.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 Basin Surface Area Provided at Spillway Crest 1,317 sf
2 6 Basin Storage Volume Provided Below Spillway Crest 2,074 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 25 of 51

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST-222
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.70 ac 10 Yr Peak Flow(Q10) 3.05 cfs
Disturbed area(DA) 0.70 ac 25 Yr Peak Flow(Q25) 3.44 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 1,494 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (3600 cf per ac of TDA)5 2,520 cf
10 Yr Storm Rainfall Intensity(1)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST-222
Bottom Elevation 876.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 876.00 0.00 1,081 0
877.00 1.00 1,348 1,212
878.00 2.00 1,640 2,704
879.00 3.00 1,957 4,500
880.00 4.00 2,300 6,626
Basin Configuration
Bottom Elevation 876.00 msl
Sediment Storage Elevation/Spillway 878.00 msl
Top of Berm 880.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 Basin Surface Area Provided at Spillway Crest 1,640 sf
2 6 113asin Storage Volume Provided Below Spillway Crest 2,704 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 26 of 51

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST-223-Phase 2
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.80 ac 10 Yr Peak Flow(Q10) 3.48 cfs
Disturbed area(DA) 0.80 ac 25 Yr Peak Flow(Q25) 3.93 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 1,708 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (3600 cf per ac of TDA)5 2,880 cf
10 Yr Storm Rainfall Intensity(1)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST-223-Phase 2
Bottom Elevation 882.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 882.00 0.00 1,219 0
883.00 1.00 1,501 1,358
884.00 2.00 1,808 3,010
885.00 3.00 2,141 4,982
886.00 4.00 2,498 7,299
Basin Configuration
Bottom Elevation 882.00 msl
Sediment Storage Elevation/Spillway 884.00 msl
Top of Berm 886.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 Basin Surface Area Provided at Spillway Crest 1,808 sf
2 6 Basin Storage Volume Provided Below Spillway Crest 3,010 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 27 of 51

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST-224
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.60 ac 10 Yr Peak Flow(Q10) 2.61 cfs
Disturbed area(DA) 0.60 ac 25 Yr Peak Flow(Q25) 2.94 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 1,281 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (3600 cf per ac of TDA)5 2,160 cf
10 Yr Storm Rainfall Intensity(1)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST-224
Bottom Elevation 820.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 820.00 0.00 1,081 0
820.00 0.00 1,348 0
821.00 1.00 1,640 1,492
822.00 2.00 1,957 3,288
823.00 3.00 2,300 5,414
Basin Configuration
Bottom Elevation 820.00 msl
Sediment Storage Elevation/Spillway 822.00 msl
Top of Berm 824.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 113asin Surface Area Provided at Spillway Crest 1,957 sf
2 6 113asin Storage Volume Provided Below Spillway Crest 3,288 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 28 of 51

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST-225
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.80 ac 10 Yr Peak Flow(Q10) 3.48 cfs
Disturbed area(DA) 0.80 ac 25 Yr Peak Flow(Q25) 3.93 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 1,708 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (3600 cf per ac of TDA)5 2,880 cf
10 Yr Storm Rainfall Intensity(1)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST-225
Bottom Elevation 812.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 812.00 0.00 1,219 0
813.00 1.00 1,501 1,358
814.00 2.00 1,808 3,010
815.00 3.00 2,141 4,982
816.00 4.00 2,498 7,299
Basin Configuration
Bottom Elevation 812.00 msl
Sediment Storage Elevation/Spillway 814.00 msl
Top of Berm 816.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 113asin Surface Area Provided at Spillway Crest 1,808 sf
2 6 113asin Storage Volume Provided Below Spillway Crest 3,010 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 29 of 51

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST-226
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.50 ac 10 Yr Peak Flow(Q10) 2.18 cfs
Disturbed area(DA) 0.50 ac 25 Yr Peak Flow(Q25) 2.45 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 1,067 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (3600 cf per ac of TDA)5 1,800 cf
10 Yr Storm Rainfall Intensity(1)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST-226
Bottom Elevation 822.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 822.00 0.00 1,081 0
823.00 1.00 1,348 1,212
824.00 2.00 1,640 2,704
825.00 3.00 1,957 4,500
826.00 4.00 2,300 6,626
Basin Configuration
Bottom Elevation 822.00 msl
Sediment Storage Elevation/Spillway 824.00 msl
Top of Berm 826.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 Basin Surface Area Provided at Spillway Crest 1,640 sf
2 6 113asin Storage Volume Provided Below Spillway Crest 2,704 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 30 of 51

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST-227
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.25 ac 10 Yr Peak Flow(Q10) 1.09 cfs
Disturbed area(DA) 0.25 ac 25 Yr Peak Flow(Q25) 1.23 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (435 sf per cfs of Q25)5 534 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (3600 cf per ac of TDA)5 900 cf
10 Yr Storm Rainfall Intensity(i)° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST-227
Bottom Elevation 820.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 820.00 0.00 300 0
821.00 1.00 446 371
822.00 2.00 621 902
823.00 3.00 821 1,620
824.00 4.00 1,046 2,552
Basin Configuration
Bottom Elevation 820.00 msl
Sediment Storage Elevation/Spillway 822.00 msl
Top of Berm 824.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 Basin Surface Area Provided at Spillway Crest 621 sf
2 6 Basin Storage Volume Provided Below Spillway Crest 902 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 31 of 51

SEDIMENT TRAP CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Sediment Trap: ST228-Phase 1
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 0.75 ac 10 Yr Peak Flow(Q10) 3.27 cfs
Disturbed area(DA) 0.75 ac 25 Yr Peak Flow(Q25) 3.68 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 1,196 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 1,350 cf
10 Yr Storm Rainfall Intensity(1)4 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria ST228-Phase 1
Bottom Elevation 892.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 892.00 0.00 708 0
893.00 1.00 947 825
894.00 2.00 1,212 1,901
895.00 3.00 1,501 3,255
896.00 4.00 1,816 4,911
Basin Configuration
Bottom Elevation 892.00 msl
Sediment Storage Elevation/Spillway 894.00 msl
Top of Berm 896.00 msl
Spillway Length
Drainage Area Length of Spillway Basin Size Check
1 4 Basin Surface Area Provided at Spillway Crest 1,212 sf
-]
2 6 Basin Storage Volume Provided Below Spillway Crest 1,901 cf
3 8
4 10
5 12
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.60-Sediment Trap of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
13.Weir equation: 0=CLH'S
Page 32 of 51

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin:
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 1.55 ac 10 Yr Peak Flow(Q16) 6.75 cfs
Disturbed area(DA) 0.65 ac 25 Yr Peak Flow(Q25) 7.61 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 2,472 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 2,790 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-240-Phase 2
Bottom Elevation 878.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 878.00 0.00 1,853 0
879.00 1.00 2,203 2,025
Basin Configuration 880.00 2.00 2,579 4,414
Bottom Elevation 878.00 msl 881.00 3.00 2,979 7,191
Sediment Storage Elevation 880.00 msl 882.00 4.00 3,405 10,380
Emergency Spillway Crest 881.00 msl
Top of Berm 882.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 930 ft3/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 2,579 sf
Calculated Orifice Diameter' 0.755 in Basin Storage Volume Provided Below Spillway Crest 4,414 cf
Actual Orifice Diameter' 0.750 in
Actual Skimmer Drawdown Time' 73 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 7.61 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH'S
Page 1 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-241 -Phase 1
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 2.58 ac 10 Yr Peak Flow(Q16) 11.24 cfs
Disturbed area(DA) 2.58 ac 25 Yr Peak Flow(Q25) 12.66 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 4,115 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 4,644 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-241 -Phase 1
Bottom Elevation 874.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 874.00 0.00 3,928 0
875.00 1.00 4,426 4,175
Basin Configuration 876.00 2.00 4,949 8,860
Bottom Elevation 874.00 msl 877.00 3.00 5,497 14,080
Sediment Storage Elevation 876.00 msl 878.00 4.00 6,071 19,862
Emergency Spillway Crest 877.00 msl
Top of Berm 878.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 1,548 ft'/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 4,949 sf
Calculated Orifice Diameter' 0.974 in Basin Storage Volume Provided Below Spillway Crest 8,860 cf
Actual Orifice Diameter' 1.000 in
Actual Skimmer Drawdown Time' 68 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 12.66 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 2 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-241 -Phase 2
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 1.66 ac 10 Yr Peak Flow(Q16) 7.23 cfs
Disturbed area(DA) 1.66 ac 25 Yr Peak Flow(Q25) 8.15 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 2,648 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 2,988 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-241 -Phase 2
Bottom Elevation 874.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 874.00 0.00 2,483 0
875.00 1.00 2,382 2,432
Basin Configuration 876.00 2.00 2,792 5,017
Bottom Elevation 874.00 msl 877.00 3.00 3,228 8,024
Sediment Storage Elevation 876.00 msl 878.00 4.00 3,688 11,479
Emergency Spillway Crest 877.00 msl
Top of Berm 878.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 996 ft3/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 2,792 sf
Calculated Orifice Diameter' 0.781 in Basin Storage Volume Provided Below Spillway Crest 5,017 cf
Actual Orifice Diameter' 0.750 in
Actual Skimmer Drawdown Time' 78 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 8.15 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH'S
Page 3 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-242-Phase 2
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 1.50 ac 10 Yr Peak Flow(Q16) 6.53 cfs
Disturbed area(DA) 1.50 ac 25 Yr Peak Flow(Q25) 7.36 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 2,393 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 2,700 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-242-Phase 2
Bottom Elevation 834.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 834.00 0.00 1,770 0
835.00 1.00 2,114 1,939
Basin Configuration 836.00 2.00 2,483 4,235
Bottom Elevation 834.00 msl 837.00 3.00 2,877 6,913
Sediment Storage Elevation 836.00 msl 838.00 4.00 3,296 9,997
Emergency Spillway Crest 837.00 msl
Top of Berm 838.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 90o ft3/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 2,483 sf
Calculated Orifice Diameter' 0.742 in Basin Storage Volume Provided Below Spillway Crest 4,235 cf
Actual Orifice Diameter' 0.750 in
Actual Skimmer Drawdown Time' 71 hrs
Emergency Spillway Design
^1.5 h= 1.00 Q= 7.36 cfs
C= 3.00 L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.htmi.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 4 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-243-Phase 1
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 1.99 ac 10 Yr Peak Flow(Q16) 8.67 cfs
Disturbed area(DA) 1.99 ac 25 Yr Peak Flow(Q25) 9.77 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 3,174 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 3,582 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-243-Phase 1
Bottom Elevation 874.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 874.00 0.00 2,676 0
875.00 1.00 3,083 2,877
Basin Configuration 876.00 2.00 3,515 6,174
Bottom Elevation 874.00 msl 877.00 3.00 3,972 9,915
Sediment Storage Elevation 876.00 msl 878.00 4.00 4,454 14,126
Emergency Spillway Crest 877.00 msl
Top of Berm 878.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 1,194 ft'/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,515 sf
Calculated Orifice Diameter' 0.855 in Basin Storage Volume Provided Below Spillway Crest 6,174 cf
Actual Orifice Diameter' 0.750 in
Actual Skimmer Drawdown Time' 94 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 9.77 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 5 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-243-Phase 2
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 1.50 ac 10 Yr Peak Flow(Q16) 6.53 cfs
Disturbed area(DA) 1.50 ac 25 Yr Peak Flow(Q25) 7.36 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 2,393 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 2,700 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-243-Phase 2
Bottom Elevation 874.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 874.00 0.00 2,483 0
875.00 1.00 2,877 2,678
Basin Configuration 876.00 2.00 3,296 5,762
Bottom Elevation 874.00 msl 877.00 3.00 3,740 9,277
Sediment Storage Elevation 876.00 msl 878.00 4.00 4,210 13,250
Emergency Spillway Crest 877.00 msl
Top of Berm 878.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 90o ft3/day
Skimmer Size 6.0 in
Head on Orifice(H)5 0.417 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,296 sf
Calculated Orifice Diameter' 0.777 in Basin Storage Volume Provided Below Spillway Crest 5,762 cf
Actual Orifice Diameter' 0.750 in
Actual Skimmer Drawdown Time' 77 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 7.36 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 6 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-244
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 2.25 ac 10 Yr Peak Flow(Q16) 9.80 cfs
Disturbed area(DA) 2.25 ac 25 Yr Peak Flow(Q25) 11.04 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 3,589 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 4,050 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-244
Bottom Elevation 841.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 841.00 0.00 2,726 0
842.00 1.00 3,147 2,934
Basin Configuration 843.00 2.00 3,594 6,302
Bottom Elevation 841.00 msl 844.00 3.00 4,066 10,130
Sediment Storage Elevation/Spillway 843.00 msl 845.00 4.00 4,563 14,442
Emergency Spillway Crest 844.00 msl
Top of Berm 845.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 1,350 ft'/day
Skimmer Size 5.0 in
Head on Orifice(H)5 0.333 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,594 sf
Calculated Orifice Diameter' 1.006 in Basin Storage Volume Provided Below Spillway Crest 6,302 cf
Actual Orifice Diameter' 1.000 in
Actual Skimmer Drawdown Time' 73 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 11.04 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 7 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-245-Phase 1
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 3.10 ac 10 Yr Peak Flow(Q16) 13.50 cfs
Disturbed area(DA) 3.10 ac 25 Yr Peak Flow(Q25) 15.21 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 4,945 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 5,580 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-245-Phase 1
Bottom Elevation 840.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 840.00 0.00 3,964 0
841.00 1.00 4,470 4,214
Basin Configuration 842.00 2.00 5,001 8,947
Bottom Elevation 840.00 msl 843.00 3.00 5,558 14,225
Sediment Storage Elevation 842.00 msl 844.00 4.00 6,139 20,071
Emergency Spillway Crest 843.00 msl
Top of Berm 844.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 1,860 ft'/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 5,001 sf
Calculated Orifice Diameter' 1.067 in Basin Storage Volume Provided Below Spillway Crest 8,947 cf
Actual Orifice Diameter' 1.000 in
Actual Skimmer Drawdown Time' 82 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 15.21 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 8 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-245-Phase 2
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 1.15 ac 10 Yr Peak Flow(Q16) 5.01 cfs
Disturbed area(DA) 1.15 ac 25 Yr Peak Flow(Q25) 5.64 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 1,834 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 2,070 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-245-Phase 2
Bottom Elevation 840.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 840.00 0.00 1,263 0
841.00 1.00 1,577 1,417
Basin Configuration 842.00 2.00 1,946 3,175
Bottom Elevation 840.00 msl 843.00 3.00 2,321 5,306
Sediment Storage Elevation 842.00 msl 844.00 4.00 2,721 7,824
Emergency Spillway Crest 843.00 msl
Top of Berm 844.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 690 ft3/day
Skimmer Size 4.0 in
Head on Orifice(H)5 0.333 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 1,946 sf
Calculated Orifice Diameter' 0.719 in Basin Storage Volume Provided Below Spillway Crest 3,175 cf
Actual Orifice Diameter' 0.750 in
Actual Skimmer Drawdown Time' 66 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 5.64 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 9 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin:
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 2.80 ac 10 Yr Peak Flow(Q16) 12.20 cfs
Disturbed area(DA) 2.10 ac 25 Yr Peak Flow(Q25) 13.74 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 4,466 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 5,040 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-246-Phase 1
Bottom Elevation 877.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 877.00 0.00 3,539 0
878.00 1.00 4,013 3,774
Basin Configuration 879.00 2.00 4,512 8,034
Bottom Elevation 877.00 msl 880.00 3.00 5,036 12,805
Sediment Storage Elevation 879.00 msl 881.00 4.00 5,585 18,113
Emergency Spillway Crest 880.00 msl
Top of Berm 881.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 1,680 ft'/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 4,512 sf
Calculated Orifice Diameter' 1.014 in Basin Storage Volume Provided Below Spillway Crest 8,034 cf
Actual Orifice Diameter' 1.000 in
Actual Skimmer Drawdown Time' 74 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 13.74 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 10 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin: SK-247-Phase 1
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 1.90 ac 10 Yr Peak Flow(Q16) 8.28 cfs
Disturbed area(DA) 1.90 ac 25 Yr Peak Flow(Q25) 9.33 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 3,031 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 3,420 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-247-Phase 1
Bottom Elevation 888.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 888.00 0.00 2,273 0
889.00 1.00 2,658 2,463
Basin Configuration 890.00 2.00 3,069 5,324
Bottom Elevation 888.00 msl 891.00 3.00 3,505 8,609
Sediment Storage Elevation 890.00 msl 892.00 4.00 3,966 12,342
Emergency Spillway Crest 891.00 msl
Top of Berm 892.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 1,140 ft'/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,069 sf
Calculated Orifice Diameter' 0.835 in Basin Storage Volume Provided Below Spillway Crest 5,324 cf
Actual Orifice Diameter' 0.750 in
Actual Skimmer Drawdown Time' 89 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 9.33 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH's
Page 11 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: 05.31.2022 RVW: VH
Skimmer Basin:
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 2.95 ac 10 Yr Peak Flow(Q16) 12.85 cfs
Disturbed area(DA) 2.95 ac 25 Yr Peak Flow(Q25) 14.48 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 4,706 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 5,310 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-248-Phase 1
Bottom Elevation 870.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 870.00 0.00 3,720 0
871.00 1.00 4,214 3,964
Basin Configuration 872.00 2.00 4,732 8,435
Bottom Elevation 870.00 msl 873.00 3.00 8,276 14,857
Sediment Storage Elevation 872.00 msl 874.00 4.00 5,845 21,882
Emergency Spillway Crest 873.00 msl
Top of Berm 874.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 1,770 ft'/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 4,732 sf
Calculated Orifice Diameter' 1.041 in Basin Storage Volume Provided Below Spillway Crest 8,435 cf
Actual Orifice Diameter' 1.000 in
Actual Skimmer Drawdown Time' 78 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 14.48 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 12 of 13

SKIMMER BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 05.31.2022 BY: AKL
REVISED: RVW: VH
Skimmer Basin: SK-249-Phase 1
Drainage Area Characteristics Required Storage Volume
Total drainage area(TDA)' 2.40 ac 10 Yr Peak Flow(Q16) 10.45 cfs
Disturbed area(DA) 2.40 ac 25 Yr Peak Flow(Q25) 11.78 cfs
Rational Coefficient(C)2 0.60 Req'd Min.Surface Area (325 sf per cfs of Q25)5 3,828 sf
Time of Concentration(TC)3 5.0 min Req'd Min.Storage Volume (1800 cf per ac of TDA)5 4,320 cf
10 Yr Storm Rainfall Intensity i° 7.3 in/hr
25 Yr Storm Rainfall Intensity(i)° 8.2 in/hr
Design Criteria SK-249-Phase 1
Bottom Elevation 812.00 msl Elev.(msl) Depth(ft) Area(sf) Cumulative Volume(cf)
Depth of Storage Volume 2.00 ft 812.00 0.00 3,026 0
813.00 1.00 3,482 3,251
Basin Configuration 814.00 2.00 3,964 6,972
Bottom Elevation 812.00 msl 815.00 3.00 4,470 11,186
Sediment Storage Elevation 814.00 msl 816.00 4.00 5,001 15,919
Emergency Spillway Crest 815.00 msl
Top of Berm 816.50 msl
Skimmer Outlet
Desired Skimmer Drawdown Time(td)6 72 hrs
Desired Skimmer Drawdown Rate(Qd) 1,440 ft'/day
Skimmer Size 8.0 in
Head on Orifice(H)5 0.500 ft Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,964 sf
Calculated Orifice Diameter' 0.939 in Basin Storage Volume Provided Below Spillway Crest 6,972 cf
Actual Orifice Diameter' 1.000 in
Actual Skimmer Drawdown Time' 63 hrs
Emergency Spillway Design
��A
1.5)) h= E3000EE]
Q= 11.78 cfs
C= L= 10.00 ft
Notes
1.See attached drainage area map.
2.Entire area is denuded.Conservative rational coefficient for smooth bare packed soil is 0.60.
3.Time of concentration was assumed to be the minimum of 5 minutes.
4.Rainfall intensity at project location was acquired from the NOAA website,http://hdsc.nws.noaa.gov/hdsc/pfds/pfds_map_cont.html.
5.From Section 6.64-Skimmer Sediment Basin of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
6.Basin is required to be dewatered by the skimmer in 48 to 120 hours.The optimal dewatering time is 72 hours(see note 5).
7.Weir equation: 0=CLH''
Page 13 of 13

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix I—Stormwater Calculations
Appendix I —Stormwater
Calculations

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations
Appendix I—Stormwater Calculations
This page intentionally left blank.

Ca
5A-N rz�A5A � F5AR A-N o- 5A-S 1A-S -� 1A-R D 1A- —D F
24"PIPE \ SB-5(North) SB-5(North) SB-5(North) SA-1(North) SA-1(North) SA-1(North) 24"PIPE
5BB ' 5B-R ,— 5B-S B-S 1 B-R —fl 1 BB
1O
SB-5(South) SB-5(South) SB-5(South) SB-1(South) SB-1(South) SB-1 (South) 24"PIPE
F4A-N � A4A '�— [4A R] A2A
2A-S —� [2A-R �
24"PIPE SB-4(North) SB-4(North) SB-4(North)
SB-2(North) SB-2(North) SB-2(North) 24"PIPE(North)
cs
46C-N � 46-P
SB-2(South) SB-2(South) SB-2(South) 24"PIPE(South)
24"PIPE SB-4 outh)
[413-R]
SB-4(South) SB-4(South) SB-3 SB-3 8B_3 24"PIPE
Subcat Reach On Link Routing Diagram for Piedmont Ditches and Storm Sewer
Prepared by HDR, Inc, Printed 5/31/2022
HydroCAD®10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 2
Time span=0.00-2.00 hrs, dt=0.01 hrs, 201 points
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment1A-S:SA-1 (North) Runoff Area=2.926 ac 94.53% Impervious Runoff Depth=0.77"
Tc=0.0 min C=0.91 Runoff=20.71 cfs 0.188 of
Subcatchment1 B-S: SB-1 (South) Runoff Area=1.881 ac 96.28% Impervious Runoff Depth=0.78"
Tc=0.0 min C=0.92 Runoff=13.46 cfs 0.122 of
Subcatchment2A-S:SB-2(North) Runoff Area=1.230 ac 93.50% Impervious Runoff Depth=0.76"
Tc=0.0 min C=0.90 Runoff=8.61 cfs 0.078 of
Subcatchment2B-S: SB-2(South) Runoff Area=2.380 ac 93.70% Impervious Runoff Depth=0.77"
Tc=0.0 min C=0.91 Runoff=16.85 cfs 0.153 of
Subcatchment3-S: SIB-3 Runoff Area=1.632 ac 87.25% Impervious Runoff Depth=0.73"
Tc=0.0 min C=0.86 Runoff=10.92 cfs 0.099 of
Subcatchment4A-S:SB-4(North) Runoff Area=3.076 ac 92.98% Impervious Runoff Depth=0.76"
Tc=0.0 min C=0.90 Runoff=21.54 cfs 0.196 of
Subcatchment4B-S: SB-4(South) Runoff Area=2.907 ac 89.85% Impervious Runoff Depth=0.75"
Tc=0.0 min C=0.88 Runoff=19.90 cfs 0.181 of
Subcatchment5A-S:SB-5(North) Runoff Area=0.740 ac 93.24% Impervious Runoff Depth=0.76"
Tc=0.0 min C=0.90 Runoff=5.18 cfs 0.047 of
Subcatchment5B-S: SB-5(South) Runoff Area=2.180 ac 88.53% Impervious Runoff Depth=0.74"
Tc=0.0 min C=0.87 Runoff=14.75 cfs 0.134 of
Reach 1A-N:24" PIPE Avg. Flow Depth=1.41' Max Vet=8.75 fps Inflow=20.70 cfs 0.180 of
24.0" Round Pipe n=0.012 L=35.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=20.69 cfs 0.180 of
Reach 1A-R:SA-1 (North) Avg. Flow Depth=1.12' Max Vet=4.25 fps Inflow=20.71 cfs 0.188 of
n=0.025 L=250.0' S=0.0100 '/' Capacity=84.64 cfs Outflow=20.70 cfs 0.180 of
Reach 1 B-N: 24" PIPE Avg. Flow Depth=0.95' Max Vet=9.13 fps Inflow=13.46 cfs 0.117 of
24.0" Round Pipe n=0.012 L=35.0' S=0.0143 '/' Capacity=29.29 cfs Outflow=13.46 cfs 0.117 of
Reach 1 B-R: SB-1 (South) Avg. Flow Depth=0.93' Max Vet=3.81 fps Inflow=13.46 cfs 0.122 of
n=0.025 L=200.0' S=0.0100 '/' Capacity=84.64 cfs Outflow=13.46 cfs 0.117 of
Reach 2A-N:24" PIPE(North) Avg. Flow Depth=0.78' Max Vet=6.96 fps Inflow=7.98 cfs 0.075 of
24.0" Round Pipe n=0.012 L=65.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=7.85 cfs 0.075 of
Reach 2A-R:SB-2(North) Avg. Flow Depth=0.87' Max Vet=2.58 fps Inflow=8.61 cfs 0.078 of
n=0.025 L=400.0' S=0.0050 '/' Capacity=59.85 cfs Outflow=7.98 cfs 0.075 of
Reach 2B-N: 24" PIPE(South) Avg. Flow Depth=1.18' Max Vet=8.31 fps Inflow=16.04 cfs 0.146 of
24.0" Round Pipe n=0.012 L=65.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=15.89 cfs 0.146 of

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 3
Reach 213-R: SB-2(South) Avg. Flow Depth=1.17' Max Vet=3.08 fps Inflow=16.85 cfs 0.153 of
n=0.025 L=400.0' S=0.0050 '/' Capacity=59.85 cfs Outflow=16.04 cfs 0.146 of
Reach 3-N: 24" PIPE Avg. Flow Depth=0.93' Max Vet=7.57 fps Inflow=10.91 cfs 0.095 of
24.0" Round Pipe n=0.012 L=120.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=10.91 cfs 0.095 of
Reach 3-R: SIB-3 Avg. Flow Depth=0.72' Max Vet=4.83 fps Inflow=10.92 cfs 0.099 of
n=0.012 L=278.4' S=0.0050 '/' Capacity=125.04 cfs Outflow=10.91 cfs 0.095 of
Reach 4A-N:24" PIPE Avg. Flow Depth=1.45' Max Vet=8.80 fps Inflow=21.49 cfs 0.187 of
24.0" Round Pipe n=0.012 L=100.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=21.47 cfs 0.187 of
Reach 4A-R:SIB-4(North) Avg. Flow Depth=1.02' Max Vet=5.17 fps Inflow=21.54 cfs 0.196 of
n=0.025 L=380.0' S=0.0165 '/' Capacity=108.72 cfs Outflow=21.49 cfs 0.187 of
Reach 413-R: SIB-4(South) Avg. Flow Depth=1.09' Max Vet=4.19 fps Inflow=19.90 cfs 0.181 of
n=0.025 L=420.0' S=0.0100 '/' Capacity=84.64 cfs Outflow=19.55 cfs 0.173 of
Reach 4BC-N: 24" PIPE Avg. Flow Depth=1.34' Max Vet=8.64 fps Inflow=19.55 cfs 0.173 of
24.0" Round Pipe n=0.012 L=290.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=19.31 cfs 0.173 of
Reach 5A-N:24" PIPE Avg. Flow Depth=1.31' Max Vet=8.58 fps Inflow=18.71 cfs 0.173 of
24.0" Round Pipe n=0.012 L=60.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=18.57 cfs 0.173 of
Reach 5A-R:SIB-5(North) Avg. Flow Depth=0.52' Max Vet=3.87 fps Inflow=5.18 cfs 0.047 of
n=0.025 L=200.0' S=0.0201 '/' Capacity=119.84 cfs Outflow=5.18 cfs 0.045 of
Reach 5B-R: SIB-5(South) Avg. Flow Depth=0.99' Max Vet=3.69 fps Inflow=14.75 cfs 0.134 of
n=0.025 L=455.0' S=0.0088 '/' Capacity=79.46 cfs Outflow=14.27 cfs 0.128 of
Pond 1A-P:SA-1 (North) Peak Elev=839.15' Inflow=20.70 cfs 0.180 of
Outflow=20.70 cfs 0.180 of
Pond 1 B-P: SB-1 (South) Peak Elev=837.97' Inflow=13.46 cfs 0.117 of
Outflow=13.46 cfs 0.117 of
Pond 2A-P:SB-2(North) Peak Elev=837.49' Inflow=7.98 cfs 0.075 of
Outflow=7.98 cfs 0.075 of
Pond 2B-P: SB-2(South) Peak Elev=838.33' Inflow=16.04 cfs 0.146 of
Outflow=16.04 cfs 0.146 of
Pond 3-P: SIB-3 Peak Elev=837.67' Inflow=10.91 cfs 0.095 of
Outflow=10.91 cfs 0.095 of
Pond 4A-P:SB-4(North) Peak Elev=838.41' Inflow=21.49 cfs 0.187 of
Outflow=21.49 cfs 0.187 of
Pond 4B-P: SB-4(South) Peak Elev=837.33' Inflow=19.55 cfs 0.173 of
Outflow=19.55 cfs 0.173 of

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 4
Pond 5A-P:SIB-5(North) Peak Elev=839.39' Inflow=5.18 cfs 0.045 of
Outflow=5.18 cfs 0.045 of
Pond 513-P: SIB-5(South) Peak Elev=838.98' Inflow=14.27 cfs 0.128 of
Outflow=14.27 cfs 0.128 of
Total Runoff Area = 18.952 ac Runoff Volume = 1.199 of Average Runoff Depth = 0.76"
7.80% Pervious = 1.479 ac 92.20% Impervious = 17.473 ac

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 5
Summary for Subcatchment 1A-S: SA-1 (North)
Runoff = 20.71 cfs @ 0.00 hrs, Volume= 0.188 af, Depth= 0.77"
Routed to Reach 1A-R : SA-1 (North)
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
2.766 0.95
0.160 0.25
2.926 0.91 Weighted Average
0.160 5.47% Pervious Area
2.766 94.53% Impervious Area
Subcatchment 1A-S: SA-1 (North)
Hydrograph
23 — — — — — — — — — — — — — — — — —
■Runoff
20.71 cfs 20 - - - PLGGaston-Gd--25- -
18 - Duration=6 min,
17 — — — —16 Udan 7.72 Cnlhr
15
14
12 t -Bufto - Otuftfe-Q.18$S9
- 10 - - - - - - - -unofFDepth:* 77"
8
7 - — — — — — — — — --
6 — — — — — — - =0.91
5
4
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 6
Summary for Subcatchment 1 B-S: SB-1 (South)
Runoff = 13.46 cfs @ 0.00 hrs, Volume= 0.122 af, Depth= 0.78"
Routed to Reach 1 B-R : SB-1 (South)
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
1.811 0.95
0.070 0.25
1.881 0.92 Weighted Average
0.070 3.72% Pervious Area
1.811 96.28% Impervious Area
Subcatchment 1 B-S: SBA (South)
Hydrograph
15 ■Runoff
13.46 cfs
13 PL1_-Gasfon G0 23=yr
12
- - - - - - - - -Duration=Cmin,
11 - - - - - - - - Inten=7.72Fnft
10
Area=r881 ac
8 Runoff Volume=0.122 of
LL ' - - - ! - - - -Runoff Depth=0_78
- - - - T Tc=O fl-m i n
q C=0.92
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 7
Summary for Subcatchment 2A-S: SB-2 (North)
Runoff = 8.61 cfs @ 0.00 hrs, Volume= 0.078 af, Depth= 0.76"
Routed to Reach 2A-R : SB-2 (North)
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
1.150 0.95
0.080 0.25
1.230 0.90 Weighted Average
0.080 6.50% Pervious Area
1.150 93.50% Impervious Area
Subcatchment 2A-S: SB-2 (North)
Hydrograph
+ ■Runoff
8.61 cfs
�1
- 4- - PLI-Gaston Co 25-yr
8
- _Duration=6 min,
Inten=7.72 in/hr
- � - - - - - - - - - - -
6 Runoff Area=1 .230 ac
5 - - - - Runoff Volume=0.078 of
o - - - - - - - - -Runoff Depth-0-76"
LL 4
- - - - - - - -Tc=0.0min-
3 I I
- C=0.90
2 1
� L
1 I I
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 2B-S: SB-2 (South)
Runoff = 16.85 cfs @ 0.00 hrs, Volume= 0.153 af, Depth= 0.77"
Routed to Reach 2B-R : SB-2 (South)
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
2.230 0.95
0.150 0.25
2.380 0.91 Weighted Average
0.150 6.30% Pervious Area
2.230 93.70% Impervious Area
Subcatchment 2B-S: SB-2 (South)
Hydrograph
■Runoff
16.85 cfs
1s - - - PLI--G fSton-CO 25yr
- T — — — — —
15
T - - - - - -Dwafian=6r im,
14
- T — — — — — — rnten=7.72inthr
12 - - - - - - - -Runoff Area=2.380-ae
10
- - - - fi -Runoff-VoI_u_me=Q.153-af
t - - - -Runoff Depth=G-.77u
LL $ -
7 — — — — — — — — — — — — — + - - - - - - - - - Te=0-0-mjq
6 — — — — — — — — — — — — — — — -k — — — — — — — — — — — —/�
5 — — — — — — — — — — — — — — - — — — — — — — — — — — C=0.91
4
3 _
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment 3-S: SB-3
Runoff = 10.92 cfs @ 0.00 hrs, Volume= 0.099 af, Depth= 0.73"
Routed to Reach 3-R : SB-3
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
1.424 0.95
0.208 0.25
1.632 0.86 Weighted Average
0.208 12.75% Pervious Area
1.424 87.25% Impervious Area
Subcatchment 3-S: SB-3
Hydrograph
12 ■Runoff
10.92 cfs
PLI-Gaston Co 25-yr
10 - - - - Duration=6 min,
- - - - ! - - - Inten=7.72in/hr
- - - - - - - - 4- - - -Runoff Area=1:632 ac
' -Run-off- Volume=0.099-af
° 6 - - ! - - Runoff Depth=0.73—'
LL 5
Tc=0.0 m i n
4
- - - - - - -C=9.-86
3-
2-
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 10
Summary for Subcatchment 4A-S: SB-4 (North)
Runoff = 21.54 cfs @ 0.00 hrs, Volume= 0.196 af, Depth= 0.76"
Routed to Reach 4A-R : SB-4 (North)
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
2.860 0.95
0.216 0.25
3.076 0.90 Weighted Average
0.216 7.02% Pervious Area
2.860 92.98% Impervious Area
Subcatchment 4A-S: SB-4 (North)
Hydrograph
24 — — — — — - ■Runoff
21.54 cfs
21 4- — — — -PLI-Gaston-Go-25 y
20 - fi
19 - Duration=6 mjw,
17 - ! - - - - - - Irate-n=7.72i-nft
15 fi -ftnof# IA1res=1076-aE
13
3 12 211 -Runoff ^ 7y
9 T 1 c---O-O-nTin
s — - — -- — —
5
4
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 11
Summary for Subcatchment 4B-S: SB-4 (South)
Runoff = 19.90 cfs @ 0.00 hrs, Volume= 0.181 af, Depth= 0.75"
Routed to Reach 4B-R : SB-4 (South)
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
2.612 0.95
0.295 0.25
2.907 0.88 Weighted Average
0.295 10.15% Pervious Area
2.612 89.85% Impervious Area
Subcatchment 4B-S: SB-4 (South)
Hydrograph
22 ■Runoff
19.90 cfs
20 F # 25
18
1 =DuTafim=6 mhy,
16 tnten=7.72 mfhr
15
14 Runoff Area=2.907 ac
13
12
RunoffA/olume=0.181- of
LL 10 off Depth=01-5-'
8 - - - - - - - - - - - - - - - Tc7--O.O-mjpp
6 - - - - - - - - - - - C n 00
5
4
3 — — — —
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 12
Summary for Subcatchment 5A-S: SB-5 (North)
Runoff = 5.18 cfs @ 0.00 hrs, Volume= 0.047 af, Depth= 0.76"
Routed to Reach 5A-R : SB-5 (North)
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
0.690 0.95
0.050 0.25
0.740 0.90 Weighted Average
0.050 6.76% Pervious Area
0.690 93.24% Impervious Area
Subcatchment 5A-S: SB-5 (North)
Hydrograph
■Runoff
5.1 s ors
5 PC1=Gasfon�Co-23=yr
Duration=6 min,
4 - - rnten=7.72-in/hr
Runoff Area=0.740 ac
w 1 3 I I Runoff Volume=0.047 of
LL
Runoff Depth=0.76"
A
- rc=O.Omin
C=0.90
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 13
Summary for Subcatchment 5B-S: SB-5 (South)
Runoff = 14.75 cfs @ 0.00 hrs, Volume= 0.134 af, Depth= 0.74"
Routed to Reach 5B-R : SB-5 (South)
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Area (ac) C Description
1.930 0.95
0.250 0.25
2.180 0.87 Weighted Average
0.250 11.47% Pervious Area
1.930 88.53% Impervious Area
Subcatchment 5B-S: SB-5 (South)
Hydrograph
16 — — — — — — — — — — — — — — — — — — ■Runoff
14.75 cfs
14
- - - - - - - Ptl=Gaston o25yr
13 - — — — — — —Durafion=5min-,
12 L - - - - - - In#en=7.72 inft
10 runoff Area=2-.TBD-ad
9 - — — — — — — T —Runoff Volume=0.13"
- - - - - - - - - - - -Runoff Dep#h=G-.74"
LL 7 — — — — — — — — — — — — -
- ! - - - - - - - - - Tc=99min
5 — — — — — — — — — — — — — — — — — — — — — — — — — -C=9.$7
4
I
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 14
Summary for Reach 1A-N: 24" PIPE INLET PIPE TO SB - 201
[52] Hint: Inlet/Outlet conditions not evaluated (Basin has double inlet pipes)
[79] Warning: Submerged Pond 1A-P Primary device # 1 INLET by 1.26'
Inflow Area = 2.926 ac, 94.53% Impervious, Inflow Depth = 0.74" for 25-yr event
Inflow = 20.70 cfs @ 0.11 hrs, Volume= 0.180 of
Outflow = 20.69 cfs @ 0.11 hrs, Volume= 0.180 af, Atten= 0%, Lag= 0.0 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.75 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 1.82 fps, Avg. Travel Time= 0.3 min
Peak Storage= 83 cf @ 0.11 hrs
Average Depth at Peak Storage= 1.41' , Surface Width= 1.82'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012 Concrete pipe, finished
Length= 35.0' Slope= 0.0100 '/'
Inlet Invert= 833.35', Outlet Invert= 833.00'

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 15
Reach 1A-N: 24" PIPE
Hydrograph
i
23 i — — — — ❑Inflow
zo 70 of5 —1— — ■Outflow
2; 20.69ofs _ _ - IInflow Area=7-926 aC
19 - - - - - - - - -KYg._-�Fllo—w—T-Dep6�1.4V
17 — — — — — — — — 1 �YJCIJc�L���.� f-PS
15 - - - - - - - - - — — — — — — — — � Om
y 14 - - - - 1 Rdund Pipe
13
� 12 —1- - - - — — —
c 11 —1- - - - - — — — — — — nID:012
a 10 = ��Y
9 —1— — — — — — — — — — —
7 '
5 —I- - - - -APwC III Y24.50LdS
4 — — — — — — — — — — — — — — — —
3 '
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 16
Summary for Reach 1A-R: SA-1 (North)
Inflow Area = 2.926 ac, 94.53% Impervious, Inflow Depth = 0.77" for 25-yr event
Inflow = 20.71 cfs @ 0.00 hrs, Volume= 0.188 of
Outflow = 20.70 cfs @ 0.11 hrs, Volume= 0.180 af, Atten= 0%, Lag= 6.6 min
Routed to Pond 1A-P : SA-1 (North)
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 4.25 fps, Min. Travel Time= 1.0 min
Avg. Velocity = 0.90 fps, Avg. Travel Time= 4.6 min
Peak Storage= 1,219 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.12' , Surface Width= 7.72'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 84.64 cfs
1.00' x 2.00' deep channel, n= 0.025 Earth, clean &winding
Side Slope Z-value= 3.0 7' Top Width= 13.00'
Length= 250.0' Slope= 0.0100 '/'
Inlet Invert= 839.60', Outlet Invert= 837.10'
Reach 1A-R: SA-1 (North)
Hydrograph
■Inflow
23 20.71 cfs — — — — — — — — — —1 — — r— — — — — — — — — — — — — — ■outflow
21 zo.7o�ts — — — — — — — — — — — — — — —1 — — N flout�'"'!1 eC�2�926 ar,
20 - — — — — I — — — — — — — — — — — — — — — —
19-
-Flow Depth=t.1-2'
18 — — — — — — — —g'— — — — — — — — —
17 - — — — — — — — — — — —Max V-e =4.25-fps
16
15 -n=0.02.
14 t InL
13 — — — — — — — — — — — — — =ZWO'
12
r 10 — —I — —
8 - - - - ��padty=84:64 cfs
7
6 - — -
5
4
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 17
Summary for Reach 1B-N: 24" PIPE INLET PIPE TO SB - 201
[52] Hint: Inlet/Outlet conditions not evaluated (Basin has double inlet pipes)
[88] Warning: Qout>Qin may require smaller dt or Finer Routing
[79] Warning: Submerged Pond 1 B-P Primary device # 1 INLET by 1.10'
Inflow Area = 1.881 ac, 96.28% Impervious, Inflow Depth = 0.75" for 25-yr event
Inflow = 13.46 cfs @ 0.11 hrs, Volume= 0.117 of
Outflow = 13.46 cfs @ 0.11 hrs, Volume= 0.117 af, Atten= 0%, Lag= 0.0 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 9.13 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 2.16 fps, Avg. Travel Time= 0.3 min
Peak Storage= 52 cf @ 0.11 hrs
Average Depth at Peak Storage= 0.95' , Surface Width= 2.00'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 29.29 cfs
24.0" Round Pipe
n= 0.012
Length= 35.0' Slope= 0.0143 T
Inlet Invert= 833.50', Outlet Invert= 833.00'

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 18
Reach 1 B-N: 24" PIPE
Hydrograph
15 ■Inflow
/ 13.46cfs ❑Outflow
14 13.46ofs - - - -/�Tn-flow Area=T.&81 aCc
13 -Avg.-1ovv-Depth=- 0.9f
12 - —
11
- - - - - - - - - - -MaxVeE=9.1-3-fps
_ _ _lof +}4
w 9 - Round Pim
3 8
� — — - - - - - - — — — n=O.O12
o —
LL 6 — — — — — — — — — — — — -L=35.V
5 S=0.0143 '/'
4 -�- - - - -CapacitX 29.29-cfs
3
2 — — — — — — — — — — — —
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 19
Summary for Reach 1 B-R: S113-1 (South)
Inflow Area = 1.881 ac, 96.28% Impervious, Inflow Depth = 0.78" for 25-yr event
Inflow = 13.46 cfs @ 0.00 hrs, Volume= 0.122 of
Outflow = 13.46 cfs @ 0.11 hrs, Volume= 0.117 af, Atten= 0%, Lag= 6.6 min
Routed to Pond 1 B-P : SB-1 (South)
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 3.81 fps, Min. Travel Time= 0.9 min
Avg. Velocity = 0.91 fps, Avg. Travel Time= 3.7 min
Peak Storage= 707 cf @ 0.10 hrs
Average Depth at Peak Storage= 0.93' , Surface Width= 6.59'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 84.64 cfs
1.00' x 2.00' deep channel, n= 0.025 Earth, clean &winding
Side Slope Z-value= 3.0 7' Top Width= 13.00'
Length= 200.0' Slope= 0.0100 '/'
Inlet Invert= 839.10', Outlet Invert= 837.10'
Reach 1 B-R: SBA (South)
Hydrograph
— — — — — — — — — —I — — — — — — — — — — — — — -
- — — — — — — — — — — — — — — — —I — — — — — — — — — — — — — — — ■Inflow
15 13.46 cfs ■Outflow
14 " 13.46cfs inflow Area= ac
13
12 - - -I - Aug.-Row Depth=0.93'
11
- - - - - - - - - - - - - - - Max_Ve4-3-S1-fps
10 — — — J'L=0.025
9-
200�
w t= L
8 — —I L�Iv
LL ' I S=0.0100 T
6
5 - -Gapacity-84 64-cfg
4
3-
2-
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 20
Summary for Reach 2A-N: 24" PIPE (North) INLET PIPE TO SB - 202
(Basin has double inlet pipes)
[52] Hint: Inlet/Outlet conditions not evaluated
[79] Warning: Submerged Pond 2A-P Primary device # 1 INLET by 0.78'
Inflow Area = 1.230 ac, 93.50% Impervious, Inflow Depth = 0.73" for 25-yr event
Inflow = 7.98 cfs @ 0.14 hrs, Volume= 0.075 of
Outflow = 7.85 cfs @ 0.14 hrs, Volume= 0.075 af, Atten= 2%, Lag= 0.2 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 6.96 fps, Min. Travel Time= 0.2 min
Avg. Velocity = 1.48 fps, Avg. Travel Time= 0.7 min
Peak Storage= 74 cf @ 0.14 hrs
Average Depth at Peak Storage= 0.78' , Surface Width= 1.95'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 65.0' Slope= 0.0100 '/'
Inlet Invert= 825.65', Outlet Invert= 825.00'

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 21
Reach 2A-N: 24" PIPE (North)
Hydrograph
■Inflow
zsa ofs ❑Outflow
8 785cfs Inflow Area=1.230 ac
Avg. Flow Depth=0.78'
' - Max Vel=6-96-fps-
6 —
- - - - - - - - - - - 24.0.,
I
5 R_o_und Pipe
-
- - - - - - -
3 n=0.012
0 4
LL - I - L=65:0'
I
3 —I - - - S=0.0100
2 Capacity=24.51 cfs
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 22
Summary for Reach 2A-R: SB-2 (North)
Inflow Area = 1.230 ac, 93.50% Impervious, Inflow Depth = 0.76" for 25-yr event
Inflow = 8.61 cfs @ 0.00 hrs, Volume= 0.078 of
Outflow = 7.98 cfs @ 0.14 hrs, Volume= 0.075 af, Atten= 7%, Lag= 8.3 min
Routed to Pond 2A-P : SB-2 (North)
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 2.58 fps, Min. Travel Time= 2.6 min
Avg. Velocity = 0.57 fps, Avg. Travel Time= 11.6 min
Peak Storage= 1,251 cf @ 0.10 hrs
Average Depth at Peak Storage= 0.87' , Surface Width= 6.21'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 59.85 cfs
1.00' x 2.00' deep channel, n= 0.025 Earth, clean &winding
Side Slope Z-value= 3.0 '/' Top Width= 13.00'
Length= 400.0' Slope= 0.0050 T
Inlet Invert= 839.10', Outlet Invert= 837.10'
Reach 2A-R: SB-2 (North)
Hydrograph
❑Inflow
8.61 cfs ❑Outflow
9 Inflow Area=1 .230 ac
7.98 cfs
8 ' Avg. Flow Depth=0.87'
Max Vet=2.58 fps
6 I n_0.025
5 L=400.0'
LL 4 S=0.0050 T
3 Capacity=59.85 cfs
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 23
Summary for Reach 2B-N: 24" PIPE (South) INLET PIPE TO SB - 202
(Basin has double inlet pipes)
[52] Hint: Inlet/Outlet conditions not evaluated
[79] Warning: Submerged Pond 2B-P Primary device # 1 INLET by 1.18'
Inflow Area = 2.380 ac, 93.70% Impervious, Inflow Depth = 0.74" for 25-yr event
Inflow = 16.04 cfs @ 0.13 hrs, Volume= 0.146 of
Outflow = 15.89 cfs @ 0.13 hrs, Volume= 0.146 af, Atten= 1%, Lag= 0.2 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.31 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 1.62 fps, Avg. Travel Time= 0.7 min
Peak Storage= 125 cf @ 0.13 hrs
Average Depth at Peak Storage= 1.18' , Surface Width= 1.97'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 65.0' Slope= 0.0100 '/'
Inlet Invert= 825.65', Outlet Invert= 825.00'

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 24
Reach 2B-N: 24" PIPE (South)
Hydrograph
/ ❑Inflow
16.04 cfs — /� ■Outflow
17 4 flow Area=2-38-00 -aE
16
15 , _ _ _ _ -'- - Avg. F_lo_w_D_eth=
13
- -�- - - -
14 - - - - - - - - -MaxA(e1=8.31 fps
12 —— — � nn
w 11 - - - - - - - - - - - -Ro-undPipe
N
— — — — — — — — — — — - - — — —
3 9 - - - - - - - - - - - - - n--0-012
LL $ — -L=VV�
6 — — — — — — —
6 - - - - - - - - - -S-0 -Oa0-0-'/�
4 - - - - -C-apacit 24.5r cfs
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 25
Summary for Reach 2113-R: S113-2 (South)
Inflow Area = 2.380 ac, 93.70% Impervious, Inflow Depth = 0.77" for 25-yr event
Inflow = 16.85 cfs @ 0.00 hrs, Volume= 0.153 of
Outflow = 16.04 cfs @ 0.13 hrs, Volume= 0.146 af, Atten= 5%, Lag= 7.7 min
Routed to Pond 2B-P : SB-2 (South)
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 3.08 fps, Min. Travel Time= 2.2 min
Avg. Velocity = 0.63 fps, Avg. Travel Time= 10.7 min
Peak Storage= 2,125 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.17' , Surface Width= 8.05'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 59.85 cfs
1.00' x 2.00' deep channel, n= 0.025 Earth, clean &winding
Side Slope Z-value= 3.0 7' Top Width= 13.00'
Length= 400.0' Slope= 0.0050 T
Inlet Invert= 839.10', Outlet Invert= 837.10'
Reach 2113-R: S113-2 (South)
Hydrograph
■Inflow
18 16.85 cfs — — — — — - — — — 0 Outflow
17 ,6.04cf5 - - - - Inflow=Area=2.380 ac
16
15 - -I - Avg.-Flow Depth= 1 A71
14 ' - -� - - - - -Ma7xVe1=,3-.V8_fp&
13 i
12 - - - - - - - - - - - - - - - - - - - m7-0.025
11
10 -0-0.-Ot
- -Gapacity—W..SrJ-cfs
6
4-
3-
2-
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 26
Summary for Reach 3-N: 24" PIPE INLET PIPE TO SB - 203
[52] Hint: Inlet/Outlet conditions not evaluated
[79] Warning: Submerged Pond 3-P Primary device # 1 INLET by 0.93'
Inflow Area = 1.632 ac, 87.25% Impervious, Inflow Depth = 0.70" for 25-yr event
Inflow = 10.91 cfs @ 0.11 hrs, Volume= 0.095 of
Outflow = 10.91 cfs @ 0.11 hrs, Volume= 0.095 af, Atten= 0%, Lag= 0.0 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 7.57 fps, Min. Travel Time= 0.3 min
Avg. Velocity = 1.79 fps, Avg. Travel Time= 1.1 min
Peak Storage= 173 cf @ 0.11 hrs
Average Depth at Peak Storage= 0.93' , Surface Width= 2.00'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 120.0' Slope= 0.0100 '/'
Inlet Invert= 809.20', Outlet Invert= 808.00'

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 27
Reach 3-N: 24" PIPE
Hydrograph
■Inflow
12 10.91 cfs ❑Outflow
11 10.91df Inflow Area=1.632 ac
10 Avg. Flow-Depth=0.93'
9 Max Yet=7.57 fps
8 24.0"
w 7 Round Pipe
3 6 n=0.012
0
LL 5 - - - - - - - -+ —L-=120-.0
4 — — — — — — —�7��O-.OlW -'
3 - - -Capacity=24.57-cfs
2-'
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 28
Summary for Reach 3-R: SB-3
Inflow Area = 1.632 ac, 87.25% Impervious, Inflow Depth = 0.73" for 25-yr event
Inflow = 10.92 cfs @ 0.00 hrs, Volume= 0.099 of
Outflow = 10.91 cfs @ 0.11 hrs, Volume= 0.095 af, Atten= 0%, Lag= 6.6 min
Routed to Pond 3-P : SB-3
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 4.83 fps, Min. Travel Time= 1.0 min
Avg. Velocity = 1.26 fps, Avg. Travel Time= 3.7 min
Peak Storage= 629 cf @ 0.10 hrs
Average Depth at Peak Storage= 0.72' , Surface Width= 5.30'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 125.04 cfs
1.00' x 2.00' deep channel, n= 0.012
Side Slope Z-value= 3.0 '/' Top Width= 13.00'
Length= 278.4' Slope= 0.0050 '/'
Inlet Invert= 838.50', Outlet Invert= 837.10'
Reach 3-R: SB-3
Hydrograph
❑Inflow
12 10.92df ❑Outflow
11 10.91 cfs Inflow Area=1 .632 ac
10= Avg. Flow Depth=0.72'
Max Vet=4.83 fps
n=0.012
L=278.4'
3 6
LL 6 — — - — — — — S=0.0050T
4- Capacity=125.04 cfs
3-
2-
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 29
Summary for Reach 4A-N: 24" PIPE INLET PIPE TO SB - 204
(Basin has double inlet pipes)
[52] Hint: Inlet/Outlet conditions not evaluated
[79] Warning: Submerged Pond 4A-P Primary device # 1 INLET by 1.45'
Inflow Area = 3.076 ac, 92.98% Impervious, Inflow Depth = 0.73" for 25-yr event
Inflow = 21.49 cfs @ 0.12 hrs, Volume= 0.187 of
Outflow = 21.47 cfs @ 0.12 hrs, Volume= 0.187 af, Atten= 0%, Lag= 0.0 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.80 fps, Min. Travel Time= 0.2 min
Avg. Velocity = 1.72 fps, Avg. Travel Time= 1.0 min
Peak Storage= 244 cf @ 0.12 hrs
Average Depth at Peak Storage= 1.45' , Surface Width= 1.78'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 100.0' Slope= 0.0100 '/'
Inlet Invert= 814.00', Outlet Invert= 813.00'

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 30
Reach 4A-N: 24" PIPE
Hydrograph
24 i — — — — - — — — — — — ❑Inflow
23 21.49 cfs ■Outflow
22 21.47 cfs - - _ - 4 fl low Area=1 V7-6 ae
20 - - -4vg.+FowDepth=1.4r
18 —I - - - - - -FaxVe1=8.80-fpe
17
16 24.0"
15
w14 —Round Pipe
313
12 — — — — — — — — — — — — — n=0�12
'
0 11
g @ qv r
6 — — - - - - - - — — Ca acrt -25'rc#a
5 - p
4 - — — — — — — — — — — — — — — — — — — —
3
2 '
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 31
Summary for Reach 4A-R: S113-4 (North)
Inflow Area = 3.076 ac, 92.98% Impervious, Inflow Depth = 0.76" for 25-yr event
Inflow = 21.54 cfs @ 0.00 hrs, Volume= 0.196 of
Outflow = 21.49 cfs @ 0.12 hrs, Volume= 0.187 af, Atten= 0%, Lag= 7.2 min
Routed to Pond 4A-P : SB-4 (North)
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 5.17 fps, Min. Travel Time= 1.2 min
Avg. Velocity = 1.07 fps, Avg. Travel Time= 5.9 min
Peak Storage= 1,580 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.02' , Surface Width= 7.13'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 108.72 cfs
1.00' x 2.00' deep channel, n= 0.025 Earth, clean &winding
Side Slope Z-value= 3.0 7' Top Width= 13.00'
Length= 380.0' Slope= 0.0165 '/'
Inlet Invert= 840.00', Outlet Invert= 833.73'
Reach 4A-R: S113-4 (North)
Hydrograph
-I - - - - - - - - - - - - - -
■Inflow
24 23 21.54 ds - - - - - - - - - - - -3- - - - - ■outflow
22 21.49 cfs - - - 17�i 1 o- YY- Area= -0■ 6 ac
21 - - - - - - - - - -I - - - - - - - - - - - - - - - -
20 - - - - - - - - - - - - -- - Avg.-RowDepth='ha
19 - -
18 i - - - - - - - - -Max_Vel=�5_17Jps
17
16 I - - - - o.t215 -n�
14
N13 - L—V V V.V,
3 12 - I - - - - - - - - - - - - - - -
110 - - -1 - - - - - - - - - - - --s- -
6
5
4
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 32
Summary for Reach 4113-R: S113-4 (South)
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.75" for 25-yr event
Inflow = 19.90 cfs @ 0.00 hrs, Volume= 0.181 of
Outflow = 19.55 cfs @ 0.12 hrs, Volume= 0.173 af, Atten= 2%, Lag= 7.1 min
Routed to Pond 4B-P : SB-4 (South)
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 4.19 fps, Min. Travel Time= 1.7 min
Avg. Velocity = 0.80 fps, Avg. Travel Time= 8.7 min
Peak Storage= 1,970 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.09' , Surface Width= 7.57'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 84.64 cfs
1.00' x 2.00' deep channel, n= 0.025 Earth, clean &winding
Side Slope Z-value= 3.0 '/' Top Width= 13.00'
Length= 420.0' Slope= 0.0100 '/'
Inlet Invert= 837.93', Outlet Invert= 833.73'
Reach 4113-R: S113-4 (South)
Hydrograph
— — —I — — — — — — — — — — — — -
- ■Inflow
22 19.90 cfs — — — — — — — — — —I — — — — — — — — — — — — — — — — 0 Outflow
21 955cfs — —I — — rnicW Area-247 a,
20
18 - - - - - Av9.19ow Depth-f- 91
16 - - - -' - Max_V_W= 419fps
— — — — — — — — — — — — — — — — —C-
14 — — — — — — — — — — — — — — —I — — — — — — -�=0.02.5
13 — — — — — — — — — — — — — — —I — — — — — — —w n
5 12-
3: 11-
19 i S=0.0100,/,
8 - - IC-apacity=84.64-cfs
6-
5-
4 -
3 -
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 33
Summary for Reach 4BC-N: 24" PIPE INLET PIPE TO SB - 204
(Basin has double inlet pipes)
[52] Hint: Inlet/Outlet conditions not evaluated
[79] Warning: Submerged Pond 4B-P Primary device # 1 INLET by 1.34'
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.71" for 25-yr event
Inflow = 19.55 cfs @ 0.12 hrs, Volume= 0.173 of
Outflow = 19.31 cfs @ 0.13 hrs, Volume= 0.173 af, Atten= 1%, Lag= 0.8 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.64 fps, Min. Travel Time= 0.6 min
Avg. Velocity = 1.60 fps, Avg. Travel Time= 3.0 min
Peak Storage= 649 cf @ 0.12 hrs
Average Depth at Peak Storage= 1.34' , Surface Width= 1.88'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012 Corrugated PP, smooth interior
Length= 290.0' Slope= 0.0100 '/'
Inlet Invert= 815.90', Outlet Invert= 813.00'

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 34
Reach 4BC-N: 24" PIPE
Hydrograph
/ — — — - - - — — — — — ❑Inflow
21 / 19.55 cfs — — — � Y-� -A e r- p �n 0 Outflow
20 19.31 0f - Inflow IL ea=2-907 ac
18 i Avg.:Io�Dep I:. AV
15 / - - - - - - - - - - - - - - - - — — — — — — — — — - Oa4
14
13 - - - - - - - - - - - - - — — — — — — — — —RoundPipe
12 — — — — — — — — —
3 11 — — — — — — — — — — — — — — — — — — — — — — —O-M
0 10
8 — — —
5 - - - apaci#y=24.501 c#s
4 — — — — —
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 35
Summary for Reach 5A-N: 24" PIPE INLET PIPE TO SB - 205
[52] Hint: Inlet/Outlet conditions not evaluated
[79] Warning: Submerged Pond 5A-P Primary device # 1 INLET by 1.30'
[79] Warning: Submerged Pond 5B-P Primary device # 1 OUTLET by 1.30'
Inflow Area = 2.920 ac, 89.73% Impervious, Inflow Depth = 0.71" for 25-yr event
Inflow = 18.71 cfs @ 0.11 hrs, Volume= 0.173 of
Outflow = 18.57 cfs @ 0.11 hrs, Volume= 0.173 af, Atten= 1%, Lag= 0.2 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.58 fps, Min. Travel Time= 0.1 min
Avg. Velocity = 1.64 fps, Avg. Travel Time= 0.6 min
Peak Storage= 130 cf @ 0.11 hrs
Average Depth at Peak Storage= 1.31' , Surface Width= 1.90'
Bank-Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 60.0' Slope= 0.0100 '/'
Inlet Invert= 828.60', Outlet Invert= 828.00'

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 36
Reach 5A-N: 24" PIPE
Hydrograph
— — — — — ❑Inflow
20 18.71 cfs ■Outflow
19 18.57cfs Inflow Area=2.92D ac
18 17 - - Avg.ftow[?e�th='C.3'f'
16 - - - - - — — — — — MaxVel-8.58fps
14 — — — — — — — — — — — — — — 24.n
y ;z - - - - - - - -Round Pipe
11 _ _ _
010 - - - - - n=�.0'I
7 — @ O—.MGvr
—I — — — — — — — — — — — —
5 — — —
- —apacity=24.5t cfs
4 — — — — — — — — — — — — — — —
3
2 '
1 '
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 37
Summary for Reach 5A-R: S113-5 (North)
Inflow Area = 0.740 ac, 93.24% Impervious, Inflow Depth = 0.76" for 25-yr event
Inflow = 5.18 cfs @ 0.00 hrs, Volume= 0.047 of
Outflow = 5.18 cfs @ 0.11 hrs, Volume= 0.045 af, Atten= 0%, Lag= 6.6 min
Routed to Pond 5A-P : SB-5 (North)
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 3.87 fps, Min. Travel Time= 0.9 min
Avg. Velocity = 1.20 fps, Avg. Travel Time= 2.8 min
Peak Storage= 268 cf @ 0.10 hrs
Average Depth at Peak Storage= 0.52' , Surface Width= 4.13'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 119.84 cfs
1.00' x 2.00' deep channel, n= 0.025 Earth, clean &winding
Side Slope Z-value= 3.0 7' Top Width= 13.00'
Length= 200.0' Slope= 0.0201 T
Inlet Invert= 839.44', Outlet Invert= 835.43'
Reach 5A-R: S113-5 (North)
Hydrograph
■Inflow
5.18 cfs ❑Outflow
5.18 cfs Fnflow Area-0.7 ac
5 Avg. Flow Depth=0.52'
4 Max Vet=3.87 fps
n=0.025
3 L=200.0'
U_ S=0.0201
2 Capacity=119.84 cfs
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 38
Summary for Reach 5113-R: S113-5 (South)
Inflow Area = 2.180 ac, 88.53% Impervious, Inflow Depth = 0.74" for 25-yr event
Inflow = 14.75 cfs @ 0.00 hrs, Volume= 0.134 of
Outflow = 14.27 cfs @ 0.13 hrs, Volume= 0.128 af, Atten= 3%, Lag= 7.6 min
Routed to Pond 5B-P : SB-5 (South)
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 3.69 fps, Min. Travel Time= 2.1 min
Avg. Velocity = 0.76 fps, Avg. Travel Time= 10.0 min
Peak Storage= 1,782 cf @ 0.10 hrs
Average Depth at Peak Storage= 0.99' , Surface Width= 6.93'
Bank-Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 79.46 cfs
1.00' x 2.00' deep channel, n= 0.025 Earth, clean &winding
Side Slope Z-value= 3.0 7' Top Width= 13.00'
Length= 455.0' Slope= 0.0088 T
Inlet Invert= 839.44', Outlet Invert= 835.43'
Reach 5113-R: S113-5 (South)
Hydrograph
I
■Inflow
16 14.7e crs — — — —I — — — — — — — — — — — — ■Outflow
15 " 14.27cfs Inflow Area-2.1 80 ac
- - - - - - - - - - - - - - - - - - - - - - - - - -
14 — — — — —13 — — — —I — Avg.-Flaw Depth=O-.99
12 — — — —I Max-Ve1_3.0_fPS
—I — — — — — — — — — — — — —
11
- - - - - - - - - - - - - - - - -n=0.025,
10
9 L= — — - —
LL ; - - - S=O.OG 8'P
6 — — - —Ca aci "-cfs-
5 p —
9
4
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 39
Summary for Pond 1A-P: SA-1 (North)
[57] Hint: Peaked at 839.15' (Flood elevation advised)
[62] Hint: Exceeded Reach 1A-R OUTLET depth by 1.08' @ 0.11 hrs
Inflow Area = 2.926 ac, 94.53% Impervious, Inflow Depth = 0.74" for 25-yr event
Inflow = 20.70 cfs @ 0.11 hrs, Volume= 0.180 of
Outflow = 20.70 cfs @ 0.11 hrs, Volume= 0.180 af, Atten= 0%, Lag= 0.0 min
Primary = 20.70 cfs @ 0.11 hrs, Volume= 0.180 of
Routed to Reach 1A-N : 24" PIPE
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 839.15'@ 0.11 hrs
Device Routing Invert Outlet Devices
#1 Primary 833.50' 24.0" Round Culvert
L= 35.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 833.50'/833.00' S= 0.0143 '/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 837.10' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Limited to weir flow at low heads
Primary OutFlow Max=20.70 cfs @ 0.11 hrs HW=839.15' (Free Discharge)
L1=Culvert (Passes 20.70 cfs of 32.63 cfs potential flow)
L2=Orifice/Grate (Orifice Controls 20.70 cfs @ 6.90 fps)
Pond 1A-P: SA-1 (North)
Hydrograph
- ❑ Inflow
23 / 20.70 cfs — — — — — — — — — — — — — — — — — — — — — — — — — — ❑Primary
2; I -Inflow Area=2.926 ac
20.70 cfs
20 — — — — — — — — — —I — — — — — — — — — — — — — — — —
19 — — — — —Peak Elev=8-39.-15'
18
17
16 - — — — — — —I — — — — — — — — — — — — — — — —
15 — — — — — —I — — — — — — — — — — — — — — — —
14
y 13
12 -
0 11
M 10
9 — — — — — — — — — — — — — —I — — — — — — — — — — — — — — — —
8
7 — — —
6 — —
5 — — — —
4
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 40
Summary for Pond 1 B-P: SB-1 (South)
[57] Hint: Peaked at 837.97' (Flood elevation advised)
[62] Hint: Exceeded Reach 1 B-R OUTLET depth by 0.07' @ 0.11 hrs
Inflow Area = 1.881 ac, 96.28% Impervious, Inflow Depth = 0.75" for 25-yr event
Inflow = 13.46 cfs @ 0.11 hrs, Volume= 0.117 of
Outflow = 13.46 cfs @ 0.11 hrs, Volume= 0.117 af, Atten= 0%, Lag= 0.0 min
Primary = 13.46 cfs @ 0.11 hrs, Volume= 0.117 of
Routed to Reach 1B-N : 24" PIPE
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 837.97'@ 0.11 hrs
Device Routing Invert Outlet Devices
#1 Primary 833.35' 24.0" Round Culvert
L= 35.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 833.35'/833.00' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 837.10' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Primary OutFlow Max=13.46 cfs @ 0.11 hrs HW=837.97' (Free Discharge)
L1=Culvert (Passes 13.46 cfs of 28.77 cfs potential flow)
L2=Orifice/Grate (Orifice Controls 13.46 cfs @ 4.49 fps)
Pond 1 B-P: SBA (South)
Hydrograph
15 ❑ Inflow
13.46 cfs ❑Primary
14 13.46 cfs Inflow Area=1 .881 ac
13
12 Peak Elev=837.97'
11
10
9
N
8
0 7
LL
6
5
4
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 41
Summary for Pond 2A-P: SB-2 (North)
[57] Hint: Peaked at 837.49' (Flood elevation advised)
[61] Hint: Exceeded Reach 2A-R outlet invert by 0.39' @ 0.14 hrs
Inflow Area = 1.230 ac, 93.50% Impervious, Inflow Depth = 0.73" for 25-yr event
Inflow = 7.98 cfs @ 0.14 hrs, Volume= 0.075 of
Outflow = 7.98 cfs @ 0.14 hrs, Volume= 0.075 af, Atten= 0%, Lag= 0.0 min
Primary = 7.98 cfs @ 0.14 hrs, Volume= 0.075 of
Routed to Reach 2A-N : 24" PIPE (North)
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 837.49'@ 0.14 hrs
Device Routing Invert Outlet Devices
#1 Primary 825.65' 24.0" Round Culvert
L= 65.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 825.65'/825.00' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 837.10' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Limited to weir flow at low heads
Primary OutFlow Max=7.99 cfs @ 0.14 hrs HW=837.49' (Free Discharge)
L1=Culvert (Passes 7.99 cfs of 49.81 cfs potential flow)
L2=Orifice/Grate (Weir Controls 7.99 cfs @ 2.04 fps)
Pond 2A-P: SB-2 (North)
Hydrograph
❑ Inflow
.98 cfs ❑Primary
8 7.98 cfs Inflow Area=1 .230 ac
Peak Elev=837.49'
6
y 5
3
0 4
LL
3
2-
1-
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 42
Summary for Pond 2B-P: SB-2 (South)
[57] Hint: Peaked at 838.33' (Flood elevation advised)
[62] Hint: Exceeded Reach 2B-R OUTLET depth by 0.41' @ 0.13 hrs
Inflow Area = 2.380 ac, 93.70% Impervious, Inflow Depth = 0.74" for 25-yr event
Inflow = 16.04 cfs @ 0.13 hrs, Volume= 0.146 of
Outflow = 16.04 cfs @ 0.13 hrs, Volume= 0.146 af, Atten= 0%, Lag= 0.0 min
Primary = 16.04 cfs @ 0.13 hrs, Volume= 0.146 of
Routed to Reach 2B-N : 24" PIPE (South)
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 838.33'@ 0.13 hrs
Device Routing Invert Outlet Devices
#1 Primary 825.65' 24.0" Round Culvert
L= 65.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 825.65'/825.00' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 837.10' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Limited to weir flow at low heads
Primary OutFlow Max=15.97 cfs @ 0.13 hrs HW=838.32' (Free Discharge)
L1=Culvert (Passes 15.97 cfs of 51.68 cfs potential flow)
L2=Orifice/Grate (Orifice Controls 15.97 cfs @ 5.32 fps)
Pond 2B-P: SB-2 (South)
Hydrograph
❑ Inflow
❑Prima
17 4�f° cfs 16 - - - - - - - Inflow Area=2.380 ac Primary
14 Peak Elev=838.33'
13
12 — — — — — — — — — —I — — —
11. — — — — — — — — — — —I — — —
F 10
3 9
0
LL 8
7 - - - - - - - - - - - - - - - -
6
5
4
3
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 43
Summary for Pond 3-P: SB-3
[57] Hint: Peaked at 837.67' (Flood elevation advised)
[62] Hint: Exceeded Reach 3-R OUTLET depth by 0.07' @ 0.12 hrs
Inflow Area = 1.632 ac, 87.25% Impervious, Inflow Depth = 0.70" for 25-yr event
Inflow = 10.91 cfs @ 0.11 hrs, Volume= 0.095 of
Outflow = 10.91 cfs @ 0.11 hrs, Volume= 0.095 af, Atten= 0%, Lag= 0.0 min
Primary = 10.91 cfs @ 0.11 hrs, Volume= 0.095 of
Routed to Reach 3-N : 24" PIPE
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 837.67'@ 0.11 hrs
Device Routing Invert Outlet Devices
#1 Primary 809.20' 24.0" Round Culvert
L= 120.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 809.20'/808.00' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 837.10' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Limited to weir flow at low heads
Primary OutFlow Max=10.93 cfs @ 0.11 hrs HW=837.67' (Free Discharge)
L1=Culvert (Passes 10.93 cfs of 79.28 cfs potential flow)
L2=Orifice/Grate (Orifice Controls 10.93 cfs @ 3.64 fps)
Pond 3-P: SB-3
Hydrograph
❑ Inflow
12 10.91 cfs ❑Primary
11 10.91 cfs Inflow Area=1 .632 ac
10 - - - - - - - Peak Elev=837.67'
g
N7 _ — — — — — — — — — -
V
3 g I — —
0
` 5 — — — — — — — — — — — — — —I — — —
4 — — — — — — — — — — — —I — — —
3-
2-
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCADO 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 44
Summary for Pond 4A-P: SB-4 (North)
[57] Hint: Peaked at 838.41' (Flood elevation advised)
[62] Hint: Exceeded Reach 4A-R OUTLET depth by 3.98' @ 0.12 hrs
Inflow Area = 3.076 ac, 92.98% Impervious, Inflow Depth = 0.73" for 25-yr event
Inflow = 21.49 cfs @ 0.12 hrs, Volume= 0.187 of
Outflow = 21.49 cfs @ 0.12 hrs, Volume= 0.187 af, Atten= 0%, Lag= 0.0 min
Primary = 21.49 cfs @ 0.12 hrs, Volume= 0.187 of
Routed to Reach 4A-N : 24" PIPE
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 838.41' @ 0.12 hrs
Device Routing Invert Outlet Devices
#1 Primary 814.00' 24.0" Round Culvert
L= 100.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 814.00'/ 813.00' S= 0.0100 '/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 836.20' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Limited to weir flow at low heads
Primary OutFlow Max=21.49 cfs @ 0.12 hrs HW=838.41' (Free Discharge)
L1=Culvert (Passes 21.49 cfs of 73.20 cfs potential flow)
L2=Orifice/Grate (Orifice Controls 21.49 cfs @ 7.16 fps)
Pond 4A-P: SB-4 (North)
Hydrograph
24 i — — — — — — —I — — — — — — — — — — — — — — ■Inflow
21.49 cfs ❑Primary
22 21.49cfs — — — — — — —In law Arrea=10-Mac
21 / — — — — — — — — — — — — — — — — — — — — — —
19 - _ -P(WcElev=MBAT
18 — — — — — — — — — — — — — — —
17
16 — — — — — — — — — — — — — — —
15 — — — — — — — — — — — — — — — — — — —
N 14 — — — — — — — — — — — — — —
u 13 — — — — — — — — — — — — —
3 12 — — — — — — — — — — — — — — — —
a 11
u10 — — — — — — — — — — — — — —I — — — — — — — — — — -
9 — — — — — — — — — — —
8 — — — — — — — — — — — — — — — — — — — — — — — —
7 — — — — — — — — — — —
6 — — — — — — — — — — — — — — — — — — — —
5 — — - — — — — — — — — — — — —
4 — — — — — — — — — — — —
3 — — — — — — —
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 45
Summary for Pond 4B-P: SB-4 (South)
[57] Hint: Peaked at 837.33' (Flood elevation advised)
[62] Hint: Exceeded Reach 4B-R OUTLET depth by 2.78' @ 0.13 hrs
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.71" for 25-yr event
Inflow = 19.55 cfs @ 0.12 hrs, Volume= 0.173 of
Outflow = 19.55 cfs @ 0.12 hrs, Volume= 0.173 af, Atten= 0%, Lag= 0.0 min
Primary = 19.55 cfs @ 0.12 hrs, Volume= 0.173 of
Routed to Reach 4BC-N : 24" PIPE
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 837.33'@ 0.12 hrs
Device Routing Invert Outlet Devices
#1 Primary 815.90' 24.0" Round Culvert
L= 290.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 815.90'/813.00' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 835.50' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Limited to weir flow at low heads
Primary OutFlow Max=19.47 cfs @ 0.12 hrs HW=837.32' (Free Discharge)
L1=Culvert (Passes 19.47 cfs of 55.65 cfs potential flow)
L2=Orifice/Grate (Orifice Controls 19.47 cfs @ 6.49 fps)
Pond 4B-P: SB-4 (South)
Hydrograph
❑ Inflow
21 19.55 cfs — —I — ❑Primary
20 19.55 cfs
— —I Inflow Area=2.907 ac
19 i
18 — — —Peak Elev=8-37.-33'
17 —
16 — — — — — — — — — — — — — — — — — — — — — —
15 — — — — — — — — — — — — — — — — — — — — — —
14 — — — — — —I — — — — — — — — — — — — — — — —
13 — — — — — — — — — — —I — — — — — — — — — — — — — — — —
12 — — — — — — — — — — — —I — — — — — — — — — — — — — — — —
3 11
0 10
LL 9 -
8 -
7 — — —I — — — — — — — — — — — —
6 - — — — — — — — — — — — — —
5 — — — — — — — — — — — — — — — — — — — — —
4 — — — — — — — — — — — — — — — — — — — — —
3 — — — — — — — — — — — — — — — — — — —
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 46
Summary for Pond 5A-P: SB-5 (North)
[57] Hint: Peaked at 839.39' (Flood elevation advised)
[62] Hint: Exceeded Reach 5A-R OUTLET depth by 3.67' @ 1.99 hrs
Inflow Area = 0.740 ac, 93.24% Impervious, Inflow Depth = 0.73" for 25-yr event
Inflow = 5.18 cfs @ 0.11 hrs, Volume= 0.045 of
Outflow = 5.18 cfs @ 0.11 hrs, Volume= 0.045 af, Atten= 0%, Lag= 0.0 min
Primary = 5.18 cfs @ 0.11 hrs, Volume= 0.045 of
Routed to Reach 5A-N : 24" PIPE
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 839.39'@ 0.11 hrs
Device Routing Invert Outlet Devices
#1 Primary 828.60' 24.0" Round Culvert
L= 60.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 828.60'/828.00' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 839.10' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Limited to weir flow at low heads
Primary OutFlow Max=5.13 cfs @ 0.11 hrs HW=839.39' (Free Discharge)
L1=Culvert (Passes 5.13 cfs of 47.33 cfs potential flow)
L2=Orifice/Grate (Weir Controls 5.13 cfs @ 1.76 fps)
Pond 5A-P: SB-5 (North)
Hydrograph
❑ Inflow
5.18 cfs ❑Primary
5.18 cfs Inflow Area=0.740 ac
5
Peak Elev=839.39'
4-
3-
0
LL
2
1
0
0 1 2
Time (hours)

Piedmont Ditches and Storm Sewer PLI-Gaston Co 25-yr Duration=6 min, Inten=7.72 in/hr
Prepared by HDR, Inc Printed 5/31/2022
HydroCAD® 10.10-7b s/n 07102 ©2022 HydroCAD Software Solutions LLC Page 47
Summary for Pond 5B-P: SB-5 (South)
[57] Hint: Peaked at 838.98' (Flood elevation advised)
[62] Hint: Exceeded Reach 5B-R OUTLET depth by 2.86' @ 0.13 hrs
Inflow Area = 2.180 ac, 88.53% Impervious, Inflow Depth = 0.70" for 25-yr event
Inflow = 14.27 cfs @ 0.13 hrs, Volume= 0.128 of
Outflow = 14.27 cfs @ 0.13 hrs, Volume= 0.128 af, Atten= 0%, Lag= 0.0 min
Primary = 14.27 cfs @ 0.13 hrs, Volume= 0.128 of
Routed to Reach 5A-N : 24" PIPE
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 838.98'@ 0.13 hrs
Device Routing Invert Outlet Devices
#1 Primary 830.40' 24.0" Round Culvert
L= 180.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 830.40'/828.60' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
#2 Device 1 838.00' 24.0" x 1.5" Horiz. Orifice/Grate
X 12 rows C= 0.600 in 24.0" x 36.0" Grate (50% open area)
Limited to weir flow at low heads
Primary OutFlow Max=14.11 cfs @ 0.13 hrs HW=838.95' (Free Discharge)
L1=Culvert (Passes 14.11 cfs of 39.45 cfs potential flow)
L2=Orifice/Grate (Orifice Controls 14.11 cfs @ 4.70 fps)
Pond 5B-P: SB-5 (South)
Hydrograph
❑ Inflow
1a.z7ors 1 ❑Primary
15 a.z��rs — — — — — — — — — — -1 —Inflow-Area=2-.180-ac-
14
13 Peak Elev=838.98'
12
11
10
y9 — — — — — — — — — — — — — — — — — — — — — —
� I
3 8
0
LL 7
6 1
5
3
2 — —
1
0
0 1 2
Time (hours)

1
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 1
DA1- Stream Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 189.56 cfs
Storm frequency = 10 yrs Time to peak = 730 min
Time interval = 2 min Hyd. volume = 758,686 cuft
Drainage area = 74.730 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 28.10 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA1- Stream Crossing at Road
Q (cfs) Hyd. No. 1 -- 10 Year Q (cfs)
210.00 210.00
180.00 180.00
150.00 150.00
120.00 120.00
90.00 90.00
60.00 60.00
30.00 30.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

2
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 2
DA2- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 9.112 cfs
Storm frequency = 10 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 25,553 cuft
Drainage area = 2.500 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.70 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA2- Crossing at Road
Q (cfs) Hyd. No. 2 -- 10 Year Q (cfs)
10.00 10.00
8.00 8.00
6.00 6.00
4.00 4.00
2.00 2.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 2 Time (min)

3
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 3
DA3- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 22.57 cfs
Storm frequency = 10 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 58,525 cuft
Drainage area = 5.590 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 12.90 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA3- Crossing at Road
Q (cfs) Hyd. No. 3-- 10 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
Hyd No. 3 Time (min)

4
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 4
DA4- Stream Crossing at Railroad
Hydrograph type = SCS Runoff Peak discharge = 354.47 cfs
Storm frequency = 10 yrs Time to peak = 730 min
Time interval = 2 min Hyd. volume = 1,423,773 cuft
Drainage area = 149.810 ac Curve number = 76
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 27.70 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA4- Stream Crossing at Railroad
Q (cfs) Hyd. No. 4-- 10 Year Q (cfs)
400.00 400.00
350.00 350.00
300.00 300.00
250.00 250.00
200.00 200.00
150.00 150.00
100.00 100.00
50.00 50.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

5
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 5
DA 5 - Railroad Crossing South
Hydrograph type = SCS Runoff Peak discharge = 51.83 cfs
Storm frequency = 10 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 145,344 cuft
Drainage area = 14.220 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 16.10 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA 5 - Railroad Crossing South
Q (cfs) Hyd. No. 5-- 10 Year Q (cfs)
60.00 60.00
50.00 50.00
40.00 40.00
30.00 30.00
20.00 20.00
10.00 10.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 5 Time (min)

6
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 1
DA1- Stream Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 296.09 cfs
Storm frequency = 25 yrs Time to peak = 730 min
Time interval = 2 min Hyd. volume = 1,184,395 cuft
Drainage area = 74.730 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 28.10 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA1- Stream Crossing at Road
Q (cfs) Hyd. No. 1 --25 Year Q (cfs)
320.00 320.00
280.00 280.00
240.00 240.00
200.00 200.00
160.00 160.00
120.00 120.00
80.00 80.00
40.00 40.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

7
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 2
DA2- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 14.01 cfs
Storm frequency = 25 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 39,593 cuft
Drainage area = 2.500 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.70 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA2- Crossing at Road
Q (cfs) Hyd. No. 2 --25 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. 2 Time (min)

8
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 3
DA3- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 34.99 cfs
Storm frequency = 25 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 91,364 cuft
Drainage area = 5.590 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 12.90 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA3- Crossing at Road
Q (cfs) Hyd. No. 3--25 Year Q (cfs)
35.00 35.00
30.00 30.00
25.00 25.00
20.00 20.00
15.00 15.00
10.00 10.00
5.00 5.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 3 Time (min)

9
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 4
DA4- Stream Crossing at Railroad
Hydrograph type = SCS Runoff Peak discharge = 564.89 cfs
Storm frequency = 25 yrs Time to peak = 730 min
Time interval = 2 min Hyd. volume = 2,257,193 cuft
Drainage area = 149.810 ac Curve number = 76
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 27.70 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA4- Stream Crossing at Railroad
Q (cfs) Hyd. No. 4--25 Year Q (cfs)
640.00 640.00
560.00 560.00
480.00 480.00
400.00 400.00
320.00 320.00
240.00 240.00
160.00 160.00
80.00 80.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

10
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 5
DA 5 - Railroad Crossing South
Hydrograph type = SCS Runoff Peak discharge = 79.66 cfs
Storm frequency = 25 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 225,203 cuft
Drainage area = 14.220 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 16.10 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA 5 - Railroad Crossing South
Q (cfs) Hyd. No. 5--25 Year Q (cfs)
80.00 80.00
70.00 70.00
60.00 60.00
50.00 50.00
40.00 40.00
30.00 30.00
20.00 20.00
10.00 10.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 5 Time (min)

11
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 1
DA1- Stream Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 448.37 cfs
Storm frequency = 100 yrs Time to peak = 730 min
Time interval = 2 min Hyd. volume = 1,809,269 cuft
Drainage area = 74.730 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 28.10 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA1- Stream Crossing at Road
Q (cfs) Hyd. No. 1 -- 100 Year Q (cfs)
480.00 480.00
420.00 420.00
360.00 360.00
300.00 300.00
240.00 240.00
180.00 180.00
120.00 120.00
60.00 60.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 1 Time (min)

12
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 2
DA2- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 20.94 cfs
Storm frequency = 100 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 60,121 cuft
Drainage area = 2.500 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.70 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA2- Crossing at Road
Q (cfs) Hyd. No. 2-- 100 Year Q (cfs)
21.00 21.00
18.00 18.00
15.00 1 1 1 1 115.00
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. 2 Time (min)

13
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 3
DA3- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 52.65 cfs
Storm frequency = 100 yrs Time to peak = 720 min
Time interval = 2 min Hyd. volume = 139,567 cuft
Drainage area = 5.590 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 12.90 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA3- Crossing at Road
Q (cfs) Hyd. No. 3-- 100 Year Q (cfs)
60.00 60.00
50.00 50.00
40.00 40.00
30.00 30.00
20.00 20.00
10.00 10.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 3 Time (min)

14
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 4
DA4- Stream Crossing at Railroad
Hydrograph type = SCS Runoff Peak discharge = 868.54 cfs
Storm frequency = 100 yrs Time to peak = 730 min
Time interval = 2 min Hyd. volume = 3,490,608 cuft
Drainage area = 149.810 ac Curve number = 76
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 27.70 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA4- Stream Crossing at Railroad
Q (cfs) Hyd. No. 4-- 100 Year Q (cfs)
875.00 875.00
750.00 750.00
625.00 625.00
500.00 500.00
375.00 375.00
250.00 250.00
125.00 125.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 4 Time (min)

15
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Tuesday, 12/7/2021
Hyd. No. 5
DA 5 - Railroad Crossing South
Hydrograph type = SCS Runoff Peak discharge = 119.11 cfs
Storm frequency = 100 yrs Time to peak = 722 min
Time interval = 2 min Hyd. volume = 341,967 cuft
Drainage area = 14.220 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 16.10 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA 5 - Railroad Crossing South
Q (cfs) Hyd. No. 5-- 100 Year Q (cfs)
120.00 120.00
100.00 100.00
80.00 80.00
60.00 60.00
40.00 40.00
20.00 20.00
0.00 0.00
0 120 240 360 480 600 720 840 960 1080 1200 1320 1440 1560
Hyd No. 5 Time (min)

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix J—Stream and Culvert Crossing Calculations
Appendix J — Stream and
Culvert Crossing Calculations

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations
Appendix J—Stream and Culvert Crossing Calculations
This page intentionally left blank.

1
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 1
DA1- Stream Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 185.17 cfs
Storm frequency = 10 yrs Time to peak = 12.17 hrs
Time interval = 2 min Hyd. volume = 741,122 cuft
Drainage area = 73.000 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 28.10 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA1- Stream Crossing at Road
Q (cfs) Hyd. No. 1 -- 10 Year Q (cfs)
210.00 210.00
180.00 180.00
150.00 150.00
120.00 120.00
90.00 90.00
60.00 60.00
30.00 30.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 1 Time (hrs)

2
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 2
DA2- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 9.112 cfs
Storm frequency = 10 yrs Time to peak = 12.03 hrs
Time interval = 2 min Hyd. volume = 25,553 cuft
Drainage area = 2.500 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.70 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA2- Crossing at Road
Q (cfs) Hyd. No. 2 -- 10 Year Q (cfs)
10.00 10.00
8.00 8.00
6.00 6.00
4.00 4.00
2.00 2.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 2 Time (hrs)

3
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 3
DA3- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 22.57 cfs
Storm frequency = 10 yrs Time to peak = 12.00 hrs
Time interval = 2 min Hyd. volume = 58,525 cuft
Drainage area = 5.590 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 12.90 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA3- Crossing at Road
Q (cfs) Hyd. No. 3 -- 10 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 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 3 Time (hrs)

4
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 4
DA4- Stream Crossing at Railroad
Hydrograph type = SCS Runoff Peak discharge = 275.22 cfs
Storm frequency = 10 yrs Time to peak = 12.27 hrs
Time interval = 2 min Hyd. volume = 1,254,347 cuft
Drainage area = 133.500 ac Curve number = 76
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 36.30 min
Total precip. = 5.10 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA4- Stream Crossing at Railroad
Q (cfs) Hyd. No. 4 -- 10 Year Q (cfs)
280.00 280.00
240.00 240.00
200.00 200.00
160.00 160.00
120.00 120.00
80.00 80.00
40.00 40.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 4 Time (hrs)

5
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 1
DA1- Stream Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 289.24 cfs
Storm frequency = 25 yrs Time to peak = 12.17 hrs
Time interval = 2 min Hyd. volume = 1,156,974 cuft
Drainage area = 73.000 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 28.10 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA1- Stream Crossing at Road
Q (cfs) Hyd. No. 1 -- 25 Year Q (cfs)
320.00 320.00
280.00 280.00
240.00 240.00
200.00 200.00
160.00 160.00
120.00 120.00
80.00 80.00
40.00 40.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 1 Time (hrs)

6
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 2
DA2- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 14.01 cfs
Storm frequency = 25 yrs Time to peak = 12.03 hrs
Time interval = 2 min Hyd. volume = 39,593 cuft
Drainage area = 2.500 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.70 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA2- Crossing at Road
Q (cfs) Hyd. No. 2 -- 25 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 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 2 Time (hrs)

7
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 3
DA3- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 34.99 cfs
Storm frequency = 25 yrs Time to peak = 12.00 hrs
Time interval = 2 min Hyd. volume = 91,364 cuft
Drainage area = 5.590 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 12.90 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA3- Crossing at Road
Q (cfs) Hyd. No. 3 -- 25 Year Q (cfs)
35.00 35.00
30.00 30.00
25.00 25.00
20.00 20.00
15.00 15.00
10.00 10.00
5.00 5.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 3 Time (hrs)

8
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 4
DA4- Stream Crossing at Railroad
Hydrograph type = SCS Runoff Peak discharge = 439.11 cfs
Storm frequency = 25 yrs Time to peak = 12.23 hrs
Time interval = 2 min Hyd. volume = 1,988,590 cuft
Drainage area = 133.500 ac Curve number = 76
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 36.30 min
Total precip. = 6.88 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA4- Stream Crossing at Railroad
Q (cfs) Hyd. No. 4 -- 25 Year Q (cfs)
480.00 480.00
420.00 420.00
360.00 360.00
300.00 300.00
240.00 240.00
180.00 180.00
120.00 120.00
60.00 60.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 4 Time (hrs)

9
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 1
DA1- Stream Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 437.99 cfs
Storm frequency = 100 yrs Time to peak = 12.17 hrs
Time interval = 2 min Hyd. volume = 1,767,385 cuft
Drainage area = 73.000 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 28.10 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA1- Stream Crossing at Road
Q (cfs) Hyd. No. 1 -- 100 Year Q (cfs)
480.00 480.00
420.00 420.00
360.00 360.00
300.00 300.00
240.00 240.00
180.00 180.00
120.00 120.00
60.00 60.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 1 Time (hrs)

10
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 2
DA2- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 20.94 cfs
Storm frequency = 100 yrs Time to peak = 12.03 hrs
Time interval = 2 min Hyd. volume = 60,121 cuft
Drainage area = 2.500 ac Curve number = 79
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 14.70 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA2- Crossing at Road
Q (cfs) Hyd. No. 2 -- 100 Year Q (cfs)
21.00 21.00
18.00 18.00
15.00 15.00
12.00 12.00
9.00 9.00
6.00 6.00
3.00 3.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 2 Time (hrs)

11
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 3
DA3- Crossing at Road
Hydrograph type = SCS Runoff Peak discharge = 52.65 cfs
Storm frequency = 100 yrs Time to peak = 12.00 hrs
Time interval = 2 min Hyd. volume = 139,567 cuft
Drainage area = 5.590 ac Curve number = 78
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 12.90 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA3- Crossing at Road
Q (cfs) Hyd. No. 3-- 100 Year Q (cfs)
60.00 60.00
50.00 50.00
40.00 40.00
30.00 30.00
20.00 20.00
10.00 10.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 3 Time (hrs)

12
Hydrograph Report
Hydraflow Hydrographs Extension for AutoCAD®Civil 3D®2018 by Autodesk, Inc.v2018.3 Wednesday,08/25/2021
Hyd. No. 4
DA4- Stream Crossing at Railroad
Hydrograph type = SCS Runoff Peak discharge = 675.92 cfs
Storm frequency = 100 yrs Time to peak = 12.23 hrs
Time interval = 2 min Hyd. volume = 3,075,232 cuft
Drainage area = 133.500 ac Curve number = 76
Basin Slope = 0.0 % Hydraulic length = 0 ft
Tc method = User Time of conc. (Tc) = 36.30 min
Total precip. = 9.37 in Distribution = Type II
Storm duration = 24 hrs Shape factor = 484
DA4- Stream Crossing at Railroad
Q (cfs) Hyd. No. 4 -- 100 Year Q (cfs)
700.00 700.00
600.00 600.00
500.00 500.00
400.00 400.00
300.00 300.00
200.00 200.00
100.00 100.00
0.00 0.00
0 2 4 6 8 10 12 14 16 18 20 22 24 26
Hyd No. 4 Time (hrs)

HY-8 Culvert Analysis Report

Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 9.11 cfs
Design Flow: 14.01 cfs
Maximum Flow: 20.94 cfs

Table 1 - Summary of Culvert Flows at Crossing: Crossing 1 - DA2
Headwater Elevation Culvert 1 Discharge Roadway Discharge
(ft) Total Discharge(cfs) (cfs) (cfs) Iterations
889.96 9.11 9.11 0.00 1
890.09 10.29 10.29 0.00 1
890.22 11.48 11.48 0.00 1
890.35 12.66 12.66 0.00 1
890.50 14.01 14.01 0.00 1
890.62 15.03 15.03 0.00 1
890.76 16.21 16.21 0.00 1
890.92 17.39 17.39 0.00 1
891.08 18.57 18.57 0.00 1
891.26 19.76 19.76 0.00 1
891.45 20.94 20.94 0.00 1
893.02 28.80 28.80 0.00 Overtopping

Rating Curve Plot for Crossing: Crossing 1 - DA2
Total atui i Curve
Crossing: Crossing 1 - D
893_5
893.0
E 892_5
Cm
0
892.0
w
891_
c�
891.0
aD
_ 8pp90_5
890.0
IF
10 15 20 25 30
Total Discharge (cfs)

Table 2 - Culvert Summary Table: Culvert 1
Total Culvert Headwater Inlet Outlet Flow Normal Critical Outlet Tailwater Outlet Tailwater
Discharge Discharge Elevation Control Control Type Depth(ft) Depth(ft) Depth(ft) Depth(ft) Velocity Velocity
(cfs) (cfs) (ft) Depth(ft) Depth(ft) (ft/s) (ft/s)
9.11 9.11 889.96 1.565 0.0* 1-S2n 0.563 1.077 0.592 0.308 11.693 2.740
10.29 10.29 890.09 1.692 0.0* 1-S2n 0.599 1.149 0.639 0.324 11.908 2.829
11.48 1 11.48 890.22 1.818 1 0.0* 1-S2n 1 0.634 1.216 0.672 1 0.340 12.390 2.911
12.66 12.66 890.35 1.946 0.0* 1-S2n 0.668 1.279 0.717 0.355 12.511 2.986
14.01 14.01 890.50 2.097 0.0* 5-S2n 0.704 1.348 0.755 0.371 12.901 3.066
15.03 15.03 890.62 2.216 0.0* 5-S2n 0.731 1.397 0.790 0.382 13.025 3.122
16.21 16.21 890.76 2.362 0.0* 5-S2n 0.762 1.451 0.827 0.395 13.215 3.184
17.39 17.39 890.92 1 2.517 0.0* 5-S2n 0.791 1.503 0.859 0.407 13.483 3.243
18.57 18.57 891.08 2.683 0.0* 5-S2n 0.821 1.551 0.895 0.419 13.635 3.298
19.76 19.76 891.26 2.860 0.134 1 5-S2n 0.849 1.597 0.932 0.430 13.778 3.351
20.94 20.94 891.45 3.049 0.321 1 5-S2n 0.877 1.639 0.965 0.441 13.947 3.402

* Full Flow Headwater elevation is below inlet invert.
Straight Culvert
Inlet Elevation(invert):888.40 ft, Outlet Elevation(invert):885.39 ft
Culvert Length:65.60 ft, Culvert Slope:0.0459

Culvert Performance Curve Plot: Culvert 1
Perfonnali U1-'e
Divert: 02vert 1
0 0
Inlet Control Elev Outlet Control Elev
392
a,
w 91
390
170
a)
10 15 20 25 30
Total Discharge (cfs)

Water Surface Profile Plot for Culvert: Culvert 1
Crossili - Crossing I - DA2, Design Discharge - 14.0 efs
Cuh-ert Culvert 1_ C&ert Discharge 14.0 cfs
894
892
891
4-----
890
co
w 889
888
887
886 ---
88
-20 0 20 40 60 80
Station (ft)
Site Data - Culvert 1
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 888.40 ft
Outlet Station: 65.53 ft
Outlet Elevation: 885.39 ft
Number of Barrels: 1
Culvert Data Summary - Culvert 1
Barrel Shape: Circular
Barrel Diameter: 2.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0120
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None

Table 3 - Downstream Channel Rating Curve (Crossing: Crossing 1 - DA2)
Flow(cfs) Water Surface Depth (ft) Velocity(ft/s) Shear(psf) Froude Number
Elev(ft)
9.11 885.70 0.31 2.74 0.77 1.13
10.29 885.71 0.32 2.83 0.81 1.14
11.48 885.73 0.34 2.91 0.85 1.14
12.66 885.75 0.36 2.99 0.89 1.15
14.01 885.76 0.37 3.07 0.93 1.16
15.03 885.77 0.38 3.12 0.95 1.16
16.21 885.79 0.40 3.18 0.99 1.17
17.39 885.80 0.41 3.24 1.02 1.18
18.57 885.81 0.42 3.30 1.05 1.18
19.76 885.82 0.43 3.35 1.07 1.19
20.94 885.83 0.44 3.40 1.10 1.19
Tailwater Channel Data - Crossing 1 - DA2
Tailwater Channel Option: Irregular Channel
Channel Slope: 0.0400
User Defined Channel Cross-Section:
Coord No. Station (ft) Elevation (ft) Manning's n
1 0.00 888.26 0.0350
2 16.95 886.56 0.0350
3 35.27 885.43 0.0350
4 39.94 885.39 0.0350
5 70.19 886.41 0.0350
6 93.78 886.85 0.0000
Roadway Data for Crossing: Crossing 1 - DA2
Roadway Profile Shape: Irregular Roadway Shape (coordinates)
Irregular Roadway Cross-Section:
Coord No. Station (ft) Elevation (ft)
0 350.00 894.44
1 363.74 893.99
2 400.00 893.02
Roadway Surface: Paved
Roadway Top Width: 26.00 ft

STREAM CROSSING #3

STREAM CROSSING #3
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 22.57 cfs
Design Flow: 34.99 cfs
Maximum Flow: 52.65 cfs

STREAM CROSSING #3
Table 4 - Summary of Culvert Flows at Crossing: Crossing 2 - DA3
Headwater Elevation Culvert 2 Discharge Roadway Discharge
(ft) Total Discharge(cfs) (cfs) (cfs) Iterations
873.46 22.57 22.57 0.00 1
873.64 25.58 25.58 0.00 1
873.82 28.59 28.59 0.00 1
873.99 31.59 31.59 0.00 1
874.19 34.99 34.99 0.00 1
874.35 37.61 37.61 0.00 1
874.54 40.62 40.62 0.00 1
874.74 43.63 43.63 0.00 1
874.95 46.63 46.63 0.00 1
875.17 49.64 49.64 0.00 1
875.41 52.65 52.65 0.00 1
878.21 79.45 79.45 0.00 Overtopping

STREAM CROSSING #3
Rating Curve Plot for Crossing: Crossing 2 - DA3
Total Ratilig Curve
Crossing: Crossing 2 - D A3
879
878
0 877
u 876
87r,
874
20 40 60 60 70 80 90
Total Discharge (cfs)

STREAM CROSSING #3
Table 5 - Culvert Summary Table: Culvert 2
Total Culvert Headwater Inlet Outlet ter Outlet Tailwater
Flow Normal Critical Outlet Tailwa
Discharge Discharge Elevation Control Control Type Depth al Depth( Depth(ft) Deth ter Velocity Velocity
yp p
(cfs) (cfs) (ft) Depth(ft) Depth(ft) p (ft/s) (ft/s)
22.57 22.57 873.46 2.173 0.0* 1-S2n 0.720 1.529 0.835 0.288 14.048 2.690
25.58 25.58 873.64 2.353 0.0* 1-S2n 0.768 1.632 0.901 0.305 14.308 2.786
28.59 28.59 873.82 2.529 0.0* 1-S2n 0.812 1.730 0.964 0.320 14.577 2.874
31.59 31.59 873.99 2.703 0.0* 1-S2n 0.855 1.823 1.022 0.335 14.870 2.955
34.99 34.99 874.19 2.903 0.0* 1-S2n 0.901 1.922 1.089 0.350 15.094 3.039
37.61 37.61 874.35 3.062 0.027 5-S2n 0.935 1.995 1.138 0.362 15.293 3.100
40.62 40.62 874.54 3.251 0.237 5-S2n 0.973 2.075 1.194 0.374 15.485 3.166
43.63 43.63 874.74 3.450 0.454 5-S2n 1.011 2.152 1.247 0.386 15.699 3.228
46.63 46.63 874.95 3.6 10.676 5-S2n 1.047 2.224 1.301 0.397 15.870 3.292
49.64 49.64 875.17 3.883 1.259 5-S2n 1.083 2.293 1.351 0.408 16.067 3.356
52.65 52.65 875.41 1 4.120 1.462 5-S2n 1.117 2.358 1.402 0.418 16.248 3.417

STREAM CROSSING #3
* Full Flow Headwater elevation is below inlet invert.
Straight Culvert
Inlet Elevation(invert):871.29 ft, Outlet Elevation(invert):868.54 ft
Culvert Length:45.49 ft, Culvert Slope:0.0606

STREAM CROSSING #3
Culvert Performance Curve Plot: Culvert 2
Performance Curve
Cuh-ert: Cuh-ert 2
0 0
Inlet Control Elev Outlet Control Elev
879
878
877
0
876
w 875
874
= 873
872 A-k-
71
20 30 40 60 60 70 80 90
Total Discharge (cfs)

STREAM CROSSING #3
Water Surface Profile Plot for Culvert: Culvert 2
Crossili - Crossing 2 - D 3, Design Discharge - 35.0 efs
Cuh-ert Culvert I Culvert Discharge 35-0 cfs
880
87
876
874 ———'
.a,
u
872
---�C
63 -
-10 0 10 20 30 40 60 60
Station (ft)
Site Data - Culvert 2
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 871.29 ft
Outlet Station: 45.41 ft
Outlet Elevation: 868.54 ft
Number of Barrels: 1
Culvert Data Summary - Culvert 2
Barrel Shape: Circular
Barrel Diameter: 3.00 ft
Barrel Material: Concrete
Embedment: 0.00 in
Barrel Manning's n: 0.0120
Culvert Type: Straight
Inlet Configuration: Square Edge with Headwall
Inlet Depression: None

STREAM CROSSING #3
Table 6 - Downstream Channel Rating Curve (Crossing: Crossing 2 - DA3)
Flow(cfs) Water Surface Depth (ft) Velocity(ft/s) Shear(psf) Froude Number
Elev(ft)
22.57 868.83 0.29 2.69 0.72 1.12
25.58 868.84 0.30 2.79 0.76 1.13
28.59 868.86 0.32 2.87 0.80 1.14
31.59 868.87 0.33 2.95 0.84 1.15
34.99 868.89 0.35 3.04 0.87 1.16
37.61 868.90 0.36 3.10 0.90 1.16
40.62 868.91 0.37 3.17 0.93 1.17
43.63 868.93 0.39 3.23 0.96 1.17
46.63 868.94 0.40 3.29 0.99 1.18
49.64 868.95 0.41 3.36 1.02 1.19
52.65 868.96 0.42 3.42 1.04 1.19
Tailwater Channel Data - Crossing 2 - DA3
Tailwater Channel Option: Irregular Channel
Channel Slope: 0.0400
User Defined Channel Cross-Section:
Coord No. Station (ft) Elevation (ft) Manning's n
1 0.00 870.14 0.0350
2 26.21 868.93 0.0350
3 45.28 868.54 0.0350
4 58.05 868.57 0.0350
5 71.82 868.72 0.0350
6 93.78 869.09 0.0000
Roadway Data for Crossing: Crossing 2 - DA3
Roadway Profile Shape: Irregular Roadway Shape (coordinates)
Irregular Roadway Cross-Section:
Coord No. Station (ft) Elevation (ft)
0 950.00 879.78
1 990.06 878.53
2 1000.00 878.21
Roadway Surface: Paved
Roadway Top Width: 26.00 ft

STREAM CROSSING #4

STREAM CROSSING #4
Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 185.17 cfs
Design Flow: 289.24 cfs
Maximum Flow: 437.99 cfs

STREAM CROSSING #4
Table 7 - Summary of Culvert Flows at Crossing: Crossing 3 - DA1
Headwater Elevation Open Bottom Arch 3 Roadway Discharge
(ft) Total Discharge(cfs) Discharge(cfs) (cfs) Iterations
832.03 185.17 185.17 0.00 1
832.46 210.45 210.45 0.00 1
832.88 235.73 235.73 0.00 1
833.29 261.02 261.02 0.00 1
833.76 289.24 289.24 0.00 1
834.14 311.58 311.58 0.00 1
834.58 336.86 336.86 0.00 1
835.01 362.14 362.14 0.00 1
835.48 387.43 387.43 0.00 1
836.06 412.71 412.71 0.00 1
836.65 437.99 437.99 0.00 1
839.48 540.51 540.51 0.00 Overtopping

STREAM CROSSING #4
Rating Curve Plot for Crossing: Crossing 3 - DA1
Total Rathig Curve
Crossing: Crossing 3 - DA1
840
839
838
0
837
G 836
a�
83
c6
= 834
833
8,32
2U- 250 300 350 400 450 500 560 600
Total Discharge (cfs)

STREAM CROSSING #4
Table 8 - Culvert Summary Table: Open Bottom Arch 3
Total Culvert Headwater Inlet Outlet ter Outlet Tailwater
Flow Normal Critical Outlet Tailwa
Discharge Discharge Elevation Control Control Type Depth al Depth( Depth(ft) Deth ter Velocity Velocity
yp p
(cfs) (cfs) (ft) Depth(ft) Depth(ft) p (ft/s) (ft/s)
185.17 185.17 832.03 4.061 0.0' 1-S2n 1.919 2.193 1.919 2.334 9.834 8.874
210.45 210.45 832.46 4.488 0.133 1-S2n 2.105 2.386 2.105 2.497 10.232 9.191
235.73 235.73 832.88 4.906 0.695 1-S2n 2.290 2.572 2.290 2.650 10.586 9.479
261.02 261.02 833.29 5.324 1.295 5-S2n 2.475 2.750 2.475 2.795 10.908 9.744
289.24 289.24 833.76 5.792 2.011 5-S2n 2.681 2.936 2.681 2.947 11.232 10.017
311.58 311.58 834.14 6.174 2.630 5-S2n 2.849 3.080 2.849 3.062 11.453 10.218
336.86 336.86 834.58 6.606 3.383 5-S2n 3.045 3.238 3.045 3.187 11.679 10.432
362.14 362.14 835.01 7.038 4.179 5-S2n 3.247 3.393 3.247 3.307 11.882 10.634
387.43 387.43 835.48 7.508 5.008 5-S2n 3.458 3.535 3.458 3.422 12.057 10.825
412.71 412.71 836.06 8.093 8.076 7-M2c 3.691 3.670 3.670 3.533 12.240 11.007
437.99 437.99 836.65 8.678 1 8.405 7-M2c 3.947 1 3.802 3.802 3.640 1 12.638 11.180

STREAM CROSSING #4
* Full Flow Headwater elevation is below inlet invert.
Straight Culvert
Inlet Elevation(invert):827.97 ft, Outlet Elevation(invert):824.00 ft
Culvert Length: 111.46 ft, Culvert Slope:0.0356

STREAM CROSSING #4
Culvert Performance Curve Plot: Open Bottom Arch 3
Perfolluali U1 e
Ci- v-ert: Open Bottom Arch 3
0 0
Inlet Control Elev Outlet Control Elev
34C�
� 33r
a 1
w 34 1
33,2
.a,
_ 81
323
2r�r, 2 5 C-) 300 350 400 450 500 560 600
Total Discharge (cfs)

STREAM CROSSING #4
Water Surface Profile Plot for Culvert: Open Bottom Arch 3
Crossing - Crossing 3 - DAL Design Discharge - 289.2 cfs
Cuh-ert - Open Bottom Arch 3, Cuh-ert Discharge -289.2 cfs
842
840
838
836
834 ---
0
8�2
LLJ ��iVi
828
----4C
326
824
0 50 100
Station (ft)
Site Data - Open Bottom Arch 3
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 827.97 ft
Outlet Station: 111.39 ft
Outlet Elevation: 824.00 ft
Number of Barrels: 1
Culvert Data Summary - Open Bottom Arch 3
Barrel Shape: Arch, Open Bottom
Barrel Span: 10.00 ft
Barrel Rise: 5.25 ft
Barrel Material: Corrugated Steel
Embedment: 0.00 in
Barrel Manning's n: 0.0350 (top and sides)
Manning's n: 0.0350 (bottom)
Culvert Type: Straight
Inlet Configuration: Thin Edge Projecting

Inlet Depression: None STREAM CROSSING #4

STREAM CROSSING #4
Table 9 - Downstream Channel Rating Curve (Crossing: Crossing 3 - DA1)
Flow(cfs) Water Surface Depth (ft) Velocity(ft/s) Shear(psf) Froude Number
Elev(ft)
185.17 826.33 2.33 8.87 3.64 1.20
210.45 826.50 2.50 9.19 3.90 1.20
235.73 826.65 2.65 9.48 4.13 1.21
261.02 826.79 2.79 9.74 4.36 1.22
289.24 826.95 2.95 10.02 4.60 1.22
311.58 827.06 3.06 10.22 4.78 1.23
336.86 827.19 3.19 10.43 4.97 1.23
362.14 827.31 3.31 10.63 5.16 1.24
387.43 827.42 3.42 10.82 5.34 1.24
412.71 827.53 3.53 11.01 5.51 1.25
437.99 827.64 3.64 11.18 5.68 1.25
Tailwater Channel Data - Crossing 3 - DA1
Tailwater Channel Option: Irregular Channel
Channel Slope: 0.0250
User Defined Channel Cross-Section:
Coord No. Station (ft) Elevation (ft) Manning's n
1 0.00 835.17 0.0350
2 25.14 830.00 0.0350
3 47.91 828.00 0.0350
4 54.56 824.00 0.0350
5 60.25 824.00 0.0350
6 64.95 828.18 0.0350
7 76.03 830.91 0.0350
8 99.59 834.74 0.0000
Roadway Data for Crossing: Crossing 3 - DA1
Roadway Profile Shape: Irregular Roadway Shape (coordinates)
Irregular Roadway Cross-Section:
Coord No. Station (ft) Elevation (ft)
0 2000.00 841.16
1 2050.00 840.07
2 2083.00 839.64
3 2150.00 839.48
4 2200.00 839.91
Roadway Surface: Paved
Roadway Top Width: 26.00 ft

Crossing Discharge Data
Discharge Selection Method: Specify Minimum, Design, and Maximum Flow
Minimum Flow: 275.22 cfs
Design Flow: 439.11 cfs
Maximum Flow: 675.925 cfs

Table 10 - Summary of Culvert Flows at Crossing: Railroad Crossing 4 - DA4
Open Bottom Arch 4-
Headwater Elevation Total Discharge(cfs) Railroad Discharge Roadway Discharge Iterations
(ft) (cfs) (cfs)
821.29 275.22 275.22 0.00 1
821.90 315.29 315.29 0.00 1
822.52 355.36 355.36 0.00 1
823.14 395.43 395.43 0.00 1
824.02 439.11 439.11 0.00 1
824.79 475.57 475.57 0.00 1
825.72 515.64 515.64 0.00 1
826.82 555.71 555.71 0.00 1
827.92 595.78 595.78 0.00 1
829.17 635.85 635.85 0.00 1
830.45 675.92 675.92 0.00 1
838.23 838.68 838.68 1 0.00 Overtopping

Rating Curve Plot for Crossing: Railroad Crossing 4 - DA4
Total Rathig Curve
Crossing:RAroad Crossing 4 -D A4
838
836
834
0
832
a�
w 83p
828
a 826
824
822
,rr 4C-) 500 600 700 800 000
Total Discharge (cfs)

Table 11 - Culvert Summary Table: Open Bottom Arch 4 - Railroad
Total Culvert Headwater Inlet Outlet Flow Normal Critical Outlet Tailwater Outlet Tailwater
Discharge Discharge Elevation Control Control Type Depth(ft) Depth(ft) Depth(ft) Depth(ft) Velocity Velocity
(cfs) (cfs) (ft) Depth(ft) Depth(ft) (ft/s) (ft/s)
275.22 275.22 821.29 5.041 0.0* 5-JS1t 1.908 2.565 4.558 4.558 6.325 7.213
315.29 315.29 821.90 5.648 0.145 51iS1t 2.100 2.801 4.845 4.845 7.076 7.461
355.36 1 355.36 822.52 1 6.268 1.336 5JS1f 1 2.291 3.029 5.000 5.111 7.927 1 7.686
395.43 395.43 823.14 6.887 2.599 5-JS1f 2.480 3.247 5.000 5.358 8.821 7.893
439.11 439.11 824.02 7.772 4.103 51iS1f 2.689 3.460 5.000 5.612 9.795 8.101
475.57 475.57 824.79 8.536 5.393 5-JS1f 2.867 3.630 5.000 5.811 10.609 8.263
515.64 515.64 825.72 9.469 6.937 5-JS1f 3.067 3.810 5.000 6.020 11.503 8.430
555.71 555.71 826.82 10.568 8.524 5-JS1f 3.274 3.965 5.000 6.220 12.397 8.588
595.78 595.78 827.92 11.668 10.179 5-JS1f 3.497 4.105 5.000 6.410 13.290 8.738
635.85 635.85 829.17 12.922 11.912 4-FFf 3.737 4.238 5.000 6.593 14.184 8.880
675.92 675.92 830.45 14.201 13.711 4-FFf 4.018 4.357 5.000 6.769 15.078 9.015

* Full Flow Headwater elevation is below inlet invert.
Straight Culvert
Inlet Elevation(invert):816.25 ft, Outlet Elevation(invert):808.00 ft
Culvert Length: 162.06 ft, Culvert Slope:0.0510

Culvert Performance Curve Plot: Open Bottom Arch 4 - Railroad
Perfonlian U1 e
C&-ert: Open Bottom Arch 4- Railroad
0 0
Inlet Control Elev Outlet Control Elev
u
�2r
_ 8 2C�
,rr 4r,r� 500 600 700 800 900
Total Discharge (cfs)

Water Surface Profile Plot for Culvert: Open Bottom Arch 4 - Railroad
Crossing - Raitroad Crossing 4 - DA4. Design Discharge - 439.1 cfs
Cuh-ert - Open Bottom Arch 4 -Railroad Cuh-ert Discharge -439.1 cfs
840
83
8 21
825-
{TS
W 820
81�
---
31 C�
r� 0 50 100 150 200
Statfon(ft)
Site Data - Open Bottom Arch 4 - Railroad
Site Data Option: Culvert Invert Data
Inlet Station: 0.00 ft
Inlet Elevation: 816.25 ft
Outlet Station: 161.85 ft
Outlet Elevation: 808.00 ft
Number of Barrels: 1
Culvert Data Summary - Open Bottom Arch 4 - Railroad
Barrel Shape: Arch, Open Bottom
Barrel Span: 12.00 ft
Barrel Rise: 5.00 ft
Barrel Material: Corrugated Aluminum
Embedment: 0.00 in
Barrel Manning's n: 0.0240 (top and sides)
Manning's n: 0.0350 (bottom)
Culvert Type: Straight
Inlet Configuration: Thin Edge Projecting

Inlet Depression: None

Table 12 - Downstream Channel Rating Curve (Crossing: Railroad Crossing 4 - DA4)
Flow(cfs) Water Surface Depth (ft) Velocity(ft/s) Shear(psf) Froude Number
Elev(ft)
275.22 812.56 4.56 7.21 2.84 0.77
315.29 812.85 4.85 7.46 3.02 0.77
355.36 813.11 5.11 7.69 3.19 0.78
395.43 813.36 5.36 7.89 3.34 0.78
439.11 813.61 5.61 8.10 3.50 0.79
475.57 813.81 5.81 8.26 3.63 0.79
515.64 814.02 6.02 8.43 3.76 0.80
555.71 814.22 6.22 8.59 3.88 0.80
595.78 814.41 6.41 8.74 4.00 0.80
635.85 814.59 6.59 8.88 4.11 0.80
675.92 814.77 6.77 9.02 4.22 0.81
Tailwater Channel Data - Railroad Crossing 4 - DA4
Tailwater Channel Option: Irregular Channel
Channel Slope: 0.0100
User Defined Channel Cross-Section:
Coord No. Station (ft) Elevation (ft) Manning's n
1 0.00 816.00 0.0350
2 15.50 816.00 0.0350
3 26.56 808.00 0.0350
4 29.35 808.00 0.0350
5 42.14 820.00 0.0350
6 52.13 821.38 0.0350
Roadway Data for Crossing: Railroad Crossing 4 - DA4
Roadway Profile Shape: Irregular Roadway Shape (coordinates)
Irregular Roadway Cross-Section:
Coord No. Station (ft) Elevation (ft)
0 1975.00 840.76
1 2083.00 838.23
2 2175.00 838.46
3 2425.00 840.96
Roadway Surface: Paved
Roadway Top Width: 45.00 ft

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations ���
Appendix K—Outlet Protection Calculations
Appendix K — Outlet
Protection Calculations

PLC I Lithium Hydroxide Conversion Plant—Stormwater Calculations
Appendix K—Outlet Protection Calculations
This page intentionally left blank.

OUTLET PROTECTION CALCULATIONS
Lithium Hydroxide Conversion Plant
DATE:
wwllil.!/im■i.i.a/iw■.mll.aaiaiii.wl.aEwl.l:waalii
.i.lwi.�lwaaiar:wa:..Eal.lriillii.a.aaaa/i..a.a..a
Erriiril.\lr.iiiafiri...iwililNriilili.rfl!/lira r!
awialmriEl:amiwana:a■/.ialEnlafa:aOmal.ONaOOaa1E!
a....l Nl.\r/.lilia gas
..r//l.rN.riii...iww..i..w.r
aaaaaaamrmlaOEmaaliana:lraaNNOOOO■ra:mm7mammOman
! waliilwr/1►'ailfaNiiiaiiiriOlm!!!llnEiaffr.riara!!
.aa/iraarwi\iiwsa:l..aiEri:iauai://m:law.a:isam:a
.i.�rlrf�rii\NilalaallwrrwlrwN:iiiai.aN.:aaaiaaa
iaSOama'ana:a■Oisas■.s:wmaNwa am on am as am"mom man
aw/.:asaa!liaalsNiiaE..l..filraaia//.■l/a/i.aEN/a
.iEal�/lEm:::snrwas:mmas:maNwnla.i.aaaaisiNnamaa
amim\mw�imail.\NNaaamaww!/1Omlmar!!:ilmlaimiamma
mina V awaaw--/i1ll.i.i.i..i..O/pa....a...m..wOfso:O
a�lwnlaniraai�aaslal.i:iaiiNNaaaaia.aa/ai/iwnfN
OLIE:mcOm:wOwNww�asa■i:■aaENia:iila■OamawiaOwas"
• aaaama\Nir::naaa\awiiiaasaNNwiaaaiiwpliEmnE:aa
.walla►a
1Otfaa:Eialal.aOOa./ai�aElaaa.E...awlNaaiiaaiailaa.ataa.lf
lifOnmf.\aaa■7mEmmewaa .Oman
w/Ea7�amfilalallrmaaawmnaOam
Nw.�t.aiaim/OOiwnanmwfnmaal::.Oman
rl.f:Elllli/.Ei.Ns.r\mi/.EimwNEiwwwwiwai:a :wa.i
:ir.tOlEl:L'a:NaaNN:!\naliiaaNlOwn1■aaami waammlm
Ilia wawawwwns.:aaOsn:aw:ia
WOMMOMMOMW
Oi w1l'awanirwla��a11N E.i:r.�NaNaawOO1 Onn:a w:i/O:O
! t:aaO"Man
laa.!■.-1WOOM awaa�lfralarii■am:anaiiinla
■a:wwaHill:.E.ls/a��:lmiw.l:4�aNaiaaaam//./a/.aaa
=..iwalh■aMIMOafa.�.EalEEO�.000irmlaw:Oiatn:a
::0lawff►a:/\laaa■:Un:aaaNaf��iawsmaaimaia/wn
.a'aarmwi\/l.a.aaam\a■.i......a�+.:a:naiolrn//w/EE:
OOOimm.Oa mlamiilai►\lwllaa.iwONw:00m; wf..-.Wa--
a�Js♦<wiwiwi:silolNErillias aw.wwm.���•
.:aiivai./sEil//lE.a./aan
sN\EfN1llaOnammam Ei.r�Oiawilti:aaa O:OaOO:naa/aaa
alai Ofi.saa\NOiaaain■EO►laiaNElrawlfiaa:iiriliaE
:.wa!l..ml.
■/`.a►`iOi:aaalJirawilaaiwaa/1��NiaalaEsilwr.aEEaaa■
:=Ol�lOaaEfOJaaEawla.aa nownaz�laamimiaam:■Om■:aO:
./�..awi....i.i.`..mil..../lm...:mil................
::NiMV Oww::C/rrr.r...rr.wrawC.a.r.a.!siii:aw
■i
Nam arilrliaaaaf►':Oil:niaalNOii/lazsarrwammasi.m
.aE.mt/Va.saa::.ipl/. mm�-wnwwmmOm=m
as:firnmaismEmamr:::E►.ii■:aal man
Oalaaaaaam�.laana■
■:a1r a.swllsaiw ws::w:i.ai is w1.pla:irliaaww ilil w:O
TO PREVENT SCOUR HOLE

This page intentionally left blank.

555 Fayetteville Street, Suite 900
Raleigh, NC 27601-3034
919.232.6600
NC License F0116
hdrinc.com
© 2022 HDR, Inc., all rights reserved

This page intentionally left blank.