Appendix E - Supporting Lithium Hydroxide Conversion Plant Documentation

Piedmont Lithium Carolinas, Inc. I North Carolina Mining Permit Application
Appendices
PIEDMONT
LITHIUM
Appendix E: Supporting
Lithium Hydroxide
Conversion Plant
Documentation

Piedmont Lithium Carolinas, Inc. I North Carolina Mining Permit Application
Appendix E: Supporting Lithium Hydroxide Conversion Plant Documentation
E.1 Road, Parking, Walls, Fencing, and
Stream Crossing Construction Specifications

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.1 — Road, Parking, Walls, Fencing, and Stream Crossing Specifications
Page No.
Table of Contents
Introduction...................................................................................................................................2
Design Drawings, Plan View, Map, Construction Specifications and Cross Sections ..................2
Road Width, Gradient, and Surfacing Materials............................................................................2
Earthworkfor Roads.....................................................................................................................2
Culverts and Bridges for streams..................................................................................................3
Drainage Ditches, Drainage Structures & Erosion Control...........................................................3
ParkingLots..................................................................................................................................3
SiteRetaining Walls......................................................................................................................3
Fencing/Gates/Guardrail...............................................................................................................4
Operation and Maintenance Procedures......................................................................................4
Certification and Periodic Inspection Procedures.........................................................................4
Abandonment and/or Removal Plan.............................................................................................4
1

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.1 — Road, Parking, Walls, Fencing, and Stream Crossing Specifications
Introduction
The Lithium Hydroxide Conversion Plant will include site plan elements such as an access road,
parking lots, fencing and walls. The Lithium Hydroxide Conversion Plant general specifications
are noted here.
Design Drawings, Plan View, Map, Construction
Specifications and Cross Sections
See design drawings for a site plan of the Lithium Hydroxide Conversion Plant.
• Clearing and Grubbing — Clearing and grubbing shall be done as described in this
application.
• Excavation — Site Excavation is described in section E.3
Culverts — Major culverts for stream crossings shall be installed at the approximate
locations shown on the design drawings. Size requirements are included in this section.
Site storm drainage is described in section E.3
Road Width, Gradient, and Surfacing Materials
Road widths shall be as dimensioned in the design drawings for the access drive, site loop and
maintenance drives around and along the rail. Subgrade, base courses and surfacing materials
shall be as shown in the design drawings and shall be installed per the North Carolina
Department of Transportation's Standard Specifications for Roads and Structures 2018 addition
and any additions. Standard Specifications Library - All Documents (ncdot.gov). All roads should
be constructed to provide positive drainage off the drivable surface to roadside ditches and/or
drainage structures. Road gradients can be determined from the design drawings, but will have
a maximum slope of 5%. Road cross -slopes shall be 2% minimum and 3% maximum.
Earthwork for Roads
Roads for the Lithium Hydroxide Conversion Plant are internal drives and thus the
earthwork/grading associated with them fall within the same earthwork for other site elements
including the facility pad and associated parking. Earthwork specifications can be found in
section E.3
f►

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.1 — Road, Parking, Walls, Fencing, and Stream Crossing Specifications
Culverts and Bridges for streams
Culverts or bridges associated with the crossing of streams on the conversion plant site shall be
installed beneath roadways at the approximate locations as shown on the drawings. Where
applicable, culverts and bridges may need to follow the North Carolina Department of
Transportation's Standard Specifications for Roads and Structures 2018 addition (and any
additions) or the manufacturer's recommendations and specifications if a proprietary system
(e.g. structural plate bottomless arch culvert). Sizing of the crossings shall be found in the
design drawings.
Drainage Ditches, Drainage Structures & Erosion
Control
See section E.3 for drainage and erosion control specifications including maintenance.
Parking Lots
Parking lots are provided for in various locations as shown in the design drawings. Subgrade,
base courses and surfacing materials shall be as shown in the design drawings and shall be
installed per the North Carolina Department of Transportation's Standard Specifications for
Roads and Structures 2018 addition and any additions. Standard Specifications Library - All
Documents (ncdot.gov). All parking lots should be constructed to provide positive drainage off
the drivable surface to ditches and/or drainage structures. Parking lot gradients can be
determined from the design drawings but will have a maximum slope of 4% and a minimum
slope of 2%. Depending on use, parking lots may be a mix of heavy duty and light duty
pavement. Striping of parking lots shall be with thermoplastic paint. Accessible parking spaces
shall not exceed a slope of 2% in any direction.
Site Retaining Walls
Site retaining walls shall be installed where indicated within the design drawings and in the
manner described within the structural drawings (e.g. cast -in -place, segmental block, etc.).
Additional specifications may be required from a manufacturer in the use of a segmental block
wall or similar.
3

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.1 — Road, Parking, Walls, Fencing, and Stream Crossing Specifications
Fencing/Gates/Guardrail
Various fencing will be used on the site including perimeter security fencing, various gates
(vehicular and pedestrian) and along the top of walls to provide safety barriers. Unless special
provisions/specifications are provided by a manufacturer, fencing, gates and guardrails shall be
installed per the North Carolina Department of Transportation's Standard Specifications for
Roads and Structures 2018 addition and any additions.
Operation and Maintenance Procedures
Operation and maintenance procedures will consist of keeping a durable surface and keeping
sediment and drainage control structures maintained and operational. A road, wall, fencing,
gates, etc. damaged by a catastrophic event will be repaired as soon as practical after the
damage has occurred. Culverts shall be kept free of accumulating debris and shall be inspected
after heavy rainfall events.
Certification and Periodic Inspection Procedures
Access roads shall be inspected as part of the weekly site inspections required for the facility.
Certification of road construction shall be included in the required quarterly and annual reports.
Abandonment and/or Removal Plan
Buildings and equipment will be deconstructed after they are no longer needed for production
operations. Roads and rail will remain on the site for future industrial use. Regrading of slopes
shall be performed as necessary to be compatible with the post -mining land use and
revegetation requirements, and to compliment the natural drainage pattern of the surrounding
terrain.
C!

Piedmont Lithium Carolinas, Inc. I North Carolina Mining Permit Application
Appendix E: Supporting Lithium Hydroxide Conversion Plant Documentation
E.2 Rail Construction Specifications

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.2 — Rail Construction Specifications
Page No.
Table of Contents
Introduction...................................................................................................................................1
Design Drawings, Plan View, Map, Construction Specifications and Cross Sections ..................1
Culverts, Bridges, and Low -Water Crossings...............................................................................1
Drainage Ditches and Structures..................................................................................................1
Operation and Maintenance Procedures......................................................................................1
Certifications and Periodic Inspection Procedures.......................................................................2
ReclamationPlan.......................................................................................................................... 2
TrackDesign.................................................................................................................................2

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.2 — Rail Construction Specifications
Introduction
Rail access is provided to the site with a connection to the existing CSX main track. The lead
track crosses Hephzibah Church Road and extends through the site to the Lithium Hydroxide
Conversion Plant. Ditches, sediment traps, culverts, and silt fence will control the runoff from
the rail, storage yard, and associated access roads.
Design Drawings, Plan View, Map, Construction
Specifications and Cross Sections
A plan view of the rail and access road is shown on the Overall Site Plan Map (Appendix A),
and profiles are included in Appendix C.
• Clearing and Grubbing — Clearing and grubbing shall be done as described in this
application.
• Excavation — If excavation is required to construct the rail and yard area, excavations
shall not be steeper than 2H:1 V (Horizontal:Vertical) in soil or 0.25H:1 V in rock. Details
regarding road construction are provided in this section.
• Culverts — Culverts shall be installed at the approximate locations shown on the design
drawings. Size requirements are included in this section.
Culverts, Bridges, and Low -Water Crossings
Ditch culverts shall be installed beneath the rail at the approximate locations as shown on the
drawings.
Drainage Ditches and Structures
The appropriate road ditches and sediment traps will be installed at the approximate locations
as shown on the drawings.
Operation and Maintenance Procedures
Operation and maintenance procedures will consist of keeping a durable surface and keeping
sediment and drainage control structures maintained and operational. A rail structure damaged
by a catastrophic event will be repaired as soon as practical after the damage has occurred.

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.2 — Rail Construction Specifications
Certifications and Periodic Inspection Procedures
Rail lines and storage yards shall be inspected as part of the weekly site inspections required
for the facility. Certification of rail construction shall be included in the required quarterly and
annual reports.
Reclamation Plan
Rail and associated access roads will remain in place for future industrial site use.
Track Design
Rail access is provided to the site with a connection to the existing CSXT main track with a No.
10 right hand turnout. The lead track crosses Hephzibah Church Road at -grade and extends
through the site to the processing plant. The storage yard connects to the lead track
approximately 600 feet from the Hephzibah Church Road grade crossing. The maximum
horizontal curve is 12 degrees and the maximum compensated track grade is 2.50%. The
grade across the stream leading up to and through the plant site is 0.00%. The grade through
the storage tracks is 0.00%. A 15-foot-wide access road is provided adjacent to the lead track
and around the perimeter of the storage yard. The storage yard consists of seven tracks with
capacity for 54 rail cars. The fill slopes off the lead track are a maximum of 2:1. The fill slopes
off the storage tracks is 3:1 typical, 2:1 maximum. All track construction shall be in accordance
with the CSX Standard Specifications for the Design and Construction of Private Sidetracks.
F,

Piedmont Lithium Carolinas, Inc. I North Carolina Mining Permit Application
Appendix E: Supporting Lithium Hydroxide Conversion Plant Documentation
E.3 Drainage and Sediment Structure
Specifications

Piedmont Lithium Carolinas, Inc. i North Caroling Mining Permit Application Appendices ���
Appendix E.3 — Drainage and Sediment Structure Specifications
Page No.
Table of Contents
SitePreparation............................................................................................................................2
Demolition.....................................................................................................................................
2
SiteGrading/Excavation...............................................................................................................2
ErosionControl Measures............................................................................................................2
Sediment Control Structural BMP Excavation..............................................................................3
Stockpiles......................................................................................................................................
3
DitchLining — Vegetated...............................................................................................................3
Ditch Lining — Erosion Control Blanket.........................................................................................3
DitchLining — Rock Riprap...........................................................................................................4
Ditch Lining — Grouted Rock Riprap.............................................................................................4
WorkingEdge Ditches..................................................................................................................4
DitchMaintenance........................................................................................................................4
DitchOutlets.................................................................................................................................5
Culverts and Storm Drainage........................................................................................................5
Culvert/Storm Drainage Riprap Outlet Protection.........................................................................5
CleaningUp..................................................................................................................................5
Restoration of Surface and/or Structures......................................................................................5
Maintenance — Erosion and Sediment Control.............................................................................5
Maintenance — Storm Drainage....................................................................................................6
1

Piedmont Lithium Carolinas, Inc. i North Caroling Mining Permit Application Appendices ���
Appendix E.3 — Drainage and Sediment Structure Specifications
Site Preparation
All obstructions and vegetative material will be removed with the boundaries of the limits of
disturbance as is necessary for the construction of rail corridor, entrance drives, facility site,
parking, sediment control Best Management Practices (BMPs) and other project infrastructure.
Demolition
All demolition material shall be disposed of off -site in a legal manner, unless noted otherwise.
Site Grading/Excavation
Site Grading will conform to the lines, grades, and cross -sections shown on the applicable
design drawings located in Appendix B. Excavated slopes shall meet the percent grade
established within the drawings and at no time shall be steeper than 2:1. Fill areas shall be
compacted under the direction of a geotechnical engineer using material that is suitable for
structural fill and placed in lifts of a thickness that specified density can readily be achieved.
Compaction requirements shall be a minimum of:
Under Paved Areas, Sidewalks and Piping: Minimum 95% per ASTM D698 for Cohesive Soils.
Unpaved Areas: 90% per ASTM D698 for Cohesive Soils.
Inside of structures under foundations, under equipment support pads, under slabs -on -grade
and scarified existing subgrade under fill material: 98% per ASTM D698 and 100% in the top 12
inches for Cohesive Soils.
Outside structures next to walls, piers, columns and any other structure exterior member: 92%
per ASTM D698 for Cohesive Soils.
Erosion Control Measures
The following additional erosion and sediment control measures, if required and shown within
the design drawings shall be constructed and maintained per the North Carolina Erosion and
Sediment Control Planning and Design Manual. Where applicable, install per the manufacturer's
recommendations and specifications:
• Tree protection fencing
• Silt Fence (including J-Hooks)
• Inlet Protection
• Slope Drains
R

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.3 — Drainage and Sediment Structure Specifications
• Rock Check Dams and/or Sediment Tubes
• Slope Matting
• Dust Control
• Construction Entrance
• Culvert Inlet Protection
• Temporary Diversions
• Temporary/Permanent Seeding
• Concrete Washout
• Sediment Basins
• Sediment Traps
Sediment Control Structural BMP Excavation
The completed sediment basins and sediment traps will conform to the cross -sections and
design information shown on the applicable design drawings located in Appendix B. Structural
Sediment Control BMPs shall be developed and constructed in accordance with the North
Carolina Erosion and Sediment Control Planning and Design Manual: NC DEQ: Erosion and
Sediment Control Planning and Design Manual. Prior to installation of the BMPs the site shall be
cleared and grubbed of all organic and unsuitable material. Topsoil material shall be removed
and stockpiled. All obstructions will be removed along the line as is necessary for the
construction of the BMP features.
Stockpiles
Incorporate stockpiles near the area of work. Protect all stockpiles with erosion control
measures, but at a minimum include silt fence on the downstream side. Stockpiles shall be
stabilized or covered when not in use.
Ditch Lining — Vegetated
Vegetated lining, when required, will be placed upon completion of final grade of ditch line, the
ditch shall be vegetated according to the vegetation plan. Channels requiring vegetated lining
shall be covered with a layer of soil having a minimum thickness of 12 inches.
Ditch Lining — Erosion Control Blanket
Erosion Control Blanket Lining, when required for ditch stabilization, will be placed upon
completion of final grade of ditch line and installed per the manufacturer's recommendations
3

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.3 — Drainage and Sediment Structure Specifications
and specifications. Blanket design strength will be as noted in the design drawings. The ditch
shall be vegetated according to the vegetation plan.
Ditch Lining — Rock Riprap
Rock riprap lining, when required, will be placed in an eighteen (18) inch minimum thick blanket
on the bottom and sides of the channel. The rock will be non -toxic, non-acid producing, durable
rock having a minimum slake durability of ninety-five (95) percent and a median diameter (d50)
of twelve inches (12"). Twenty-five (25) percent by weight of the rock will be one and one-half
(1-1/2) times the median diameter or slightly larger. The remaining seventy-five (75) percent will
be well -graded material consisting of sufficient rock small enough to fill the voids between the
larger rocks.
Ditch Lining — Grouted Rock Riprap
Grouted rock riprap lining, when required, will be placed in an eighteen (18) inch thick blanket
on the bottom and sides of the channel. The rock will be non -toxic, non-acid producing, durable
rock having a minimum slake durability of ninety-five (95) percent. The sizing of the rock shall
range in nominal diameter from three (3) inches to eighteen (18) inches with a minimum median
diameter (d50) of twelve (12) inches. Twenty-five (25) percent by weight of the rock will be one
and one half (1 — 1/2) times median diameter or slightly larger. Ten (10) percent of the rock
shall be no smaller than three (3) inches. The remaining sixty-five (65) percent of the rock will
be graded between three (3) and eighteen (18) inches. The grout shall be a sand/cement
mixture with enough water added to yield a workable consistency that will fully penetrate the
rock riprap. The grout mixture shall develop a twenty-eight (28) day compressive strength of
three thousand (3000) psi. The grout mixture shall be approved by the Engineer and/or Owner
prior to placement.
Working Edge Ditches
Working edge ditches, when required, will be constructed in natural ground or compacted fill
and maintained as necessary to control surface drainage.
Ditch Maintenance
The ditches will be kept free of sediment and other debris during the working life of the facility so
that the flow of water will remain unimpeded. If needed, critical sections will be covered with
rock.
El

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices ���
Appendix E.3 — Drainage and Sediment Structure Specifications
Ditch Outlets
The ditches will outlet as shown on the plans. The outlet area will be riprapped if necessary and
disturbed soil areas will be revegetated according to the vegetation plan.
Culverts and Storm Drainage
Site Culverts and storm drainage shall be constructed per the details and to the grade lines
shown in the design drawings. All storm material and construction practices including but not
limited to piping, structures, bedding, compaction, dewatering, etc. shall be per the North
Carolina Department of Transportation's Standard Specifications for Roads and Structures 2018
addition and any additions. Standard Specifications Library - All Documents (ncdot.gov). Note:
see specification section E.1 for culverts/bridges associated with stream crossings.
Culvert/Storm Drainage Riprap Outlet Protection
The outlet area for site storm drainage will be riprapped per the dimensions and class of riprap
found within the design drawings and placed on a layer of nonwoven geotextile fabric.
Cleaning Up
Surplus material, tools and temporary structures will be removed by the Contractor. All dirt,
rubbish and excess earth from the excavation will be hauled to an approved disposal area
provided by the Contractor and the construction site will be left clean to the satisfaction of the
Engineer and/or Owner.
Restoration of Surface and/or Structures
The contractor will restore the surface and/or structures disturbed to a condition equal to that
before the work began and to the satisfaction of the Engineer and/or Owner and will furnish all
labor and material incidental thereto. All graded areas shall receive stabilization in the form of
permanent lawn via seeding. Reference the seeding specifications within the design drawings.
Maintenance — Erosion and Sediment Control
Reference the North Carolina Erosion and Sediment Control Planning and Design Manual for
detailed maintenance guidelines for each erosion and sediment control best management
5

Piedmont Lithium Carolinas, Inc. I North Caroling Mining Permit Application Appendices
Appendix E.3 — Drainage and Sediment Structure Specifications
practice (BMP) used within the project. In general, inspect all BMPs weekly and after each
rainfall event. Remove accumulated sediment where applicable and dispose of off -site or in a
protected stockpile onsite. Keep all stone clean where applicable for a specific measure.
Concrete Washout must maintain adequate holding capacity plus a freeboard of 12 inches.
Remove any trash/debris found within the BMPs. Immediately repair any damaged BMP.
Replace BMPs that continue to fail with a more structural BMP if stabilization can't be met.
Maintenance — Storm Drainage
Remove any accumulated trash and debris. Flush system at end of construction. Remove any
grout/concrete deposits in pipes and structures immediately so as not to impede the system
hydraulics.

Piedmont Lithium Carolinas, Inc. I North Carolina Mining Permit Application
Appendix E: Supporting Lithium Hydroxide Conversion Plant Documentation
EA Drainage Calculations

Stormwater
PIEDMONT
LITHIUM Calculations
Lithium Hydroxide Conversion
Plant
Gaston County, North Carolina
August 27, 2021

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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
4.0 Stormwater Calculations.................................................................................................. 2
5.0 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 Calculations
Appendix I —Stormwater Calculations
Appendix J — Stream Crossing Calculations
1

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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.
(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. The conversion plant site is
291.5 acres.
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 ft2/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

PLC I Lithium Hydroxide Conversion Plant — Stormwater Calculations ���
Stormwater Calculations
skimmer, as well as an emergency spillway designed to maintain 1-foot of freeboard. Porous
baffles are to be installed to reduce velocity and turbulence of the water flowing through the
basin.
3.2 Sediment Traps
For drainage areas less than 5 acres, sediment traps have been designed per NCDEQ
standards with a 25-year design storm based on local rainfall data. Each trap has a minimum
surface area ratio of 435 ft2/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.
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. 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 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 73-acre drainage area, was sized to be an open bottom metal arch span
of 10 ft. with a rise of 5 ft.-Y. The open bottom arch will allow the delineated stream to be
unimpacted in the area. (see Appendix J).
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 a crossing along the same delineated stream with a drainage area of 133.5 acres. An
open bottom arch span of 12' with a rise of 5' 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).

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

PLC I Lithium Hydroxide Conversion Plant — Stormwater Calculations
Appendices
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National Flood Hazard Layer FIRMette
81o19'48"W 35o24'3"N
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0 250 500 1,000 1,500 2,000
Basemap: USGS National Map: Orthoimagery. Data refreshed October, 2020
Legend
SEE FIS REPORT FOR DETAILED LEGEND AND INDEX MAP FOR FIRM PANEL LAYOUT
Without Base Flood Elevation (BFE)
Zone A, V, A99
SPECIAL FLOOD With BFE or Depth Zone Ae, AO, AH, VE, AR
HAZARD AREAS Regulatory Floodway
0.2%Annual Chance Flood Hazard, Areas
of 1% annual chance flood with average
depth less than one foot or with drainage
areas of less than one square mile zone x
_Future Conditions 1% Annual
Chance Flood Hazard zone x
Area with Reduced Flood Risk due to
OTHER AREAS OF Levee. See Notes. zone
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
V Cross Sections with 1% Annual Chance
17.5 Water Surface Elevation
s - - - Coastal Transect
^^^^ 513 — Base Flood Elevation Line (BFE)
Limit of Study
Jurisdiction Boundary
— --- Coastal Transect Baseline
OTHER _ Profile Baseline
FEATURES Hydrographic Feature
Digital Data Available N
No Digital Data Available
MAP PANELS Unmapped
YThe 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
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
reflect changes or amendments subsequent to this date and
time. The NFHL and effective information may change or
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,
FIRM panel number, and FIRM effective date. Map images for
unmapped and unmodernized areas cannot be used for
regulatory purposes.

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

PLC I Lithium Hydroxide Conversion Plant — Stormwater Calculations
Appendices
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81°22'30"
--. nnn,,, r n.... a ,.,.
35°30'
39281
27
25
601
35*22'
2fl-ZZ'.f1J"
Produced by the United States Geological Survey
North American Datum of 1983 (NAD83)
World Geodetic System of 1984 (WGS84). Projection and
1 000-meter grid: Universal Transverse Mercator, Zone 17S
10 000-foot ticks: North Carolina Coordinate System of 1983
Imagery ..................................................NAIP, June 2012
Roads..............................................©2006-2012
TomTom
Names..........................................................GNIS,
2013
Hydrography ....................National
Hydrography Dataset, 2012
Contours............................National
Elevation Dataset, 2008
Boundaries ....................Census,
IBWC, IBC, USGS, 1972 - 2012
N.
7° 14'
128 MILS
0° 11'
3 MILS
UTM GRID AND 2013 MAGNETIC NORTH
DECLINATION AT CENTER OF SHEET
U.S. National Grid
100,000-m Square ID
My
Grid Zone Designation
17S
The National Map
USTopo
20'
17'30"
ZU' -I /'3U"
SCALE 1:24 000
1 0.5 0 KILOMETERS 1 2
1000 500 0 METERS 1000 2000
1 0.5 0 1
MILES
1000 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000
FEET
CONTOUR INTERVAL 20 FEET
NORTH AMERICAN VERTICAL DATUM OF 1988
This map was produced to conform with the
National Geospatial Program US Topo Product Standard, 2011.
A metadata file associated with this product is draft version 0.6.11
NORTH
• CAROLINA
QUADRANGLE LOCATION
Banoak
Reepsville
Maiden
Cherryville
Lincolnton
Lincolnton
West
East
Waco
Bessemer
Gastonia
City
North
LINCOLNTON WEST QUADRANGLE
NORTH CAROLINA
7.5-MINUTE SERIES
81' 15'
A-... _ --- --- -
--- 5*30'
8
l 000
=T
'7
up
.5
14
17'30"
13
'2
10
?5'
9
8
7
6
5000m N
15°22'30"
51-1b'
ROAD CLASSIFICATION
Expressway o Local Connector
Secondary Hwy Local Road
Ramp 4WD
. Interstate Route 0 US Route O State Route
LINCOLNTON WEST, NC
2013
ADJOINING 7.5' QUADRANGLES

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

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

DA1, To \
TOC: 2 . . .....
CN: 78 \� �\
500 0 500 1000
SCALE: 1 " = 500'
// ��_ - ) GENERAL LEGEND
` / I( // �\\ a
��`>C\\\� TOC: 14.7 MIN
if ■ ■ ■ ■ ■ ■ ■ ■ ■ STREAM CROSSING DRAINAGE AREA
_�fai r� , 3T ✓ 5T-2 ®� \ I ' TIME OF CONCENTRATION
���
IT
�
� � / � — — — SEDIMENT BASIN/TRAP DRAINAGE AREA
DA3: 5.59 AC
-/ J1
TOC: 1:7 MIN . I�
CN:78
/I
��.
ool
kjI
L �X_5�''� k\ � � ` � 9T5 G L� •• II III I
n 1\
ST 6
--DA4.133.5AC�\�
(INCLUDES DA1-3)
TOC:36.3MIN / sB3 �1
CN:76 � �lo 'q
_
- - �
/ �; x
�.' SB-4
A ,
='X
�K
ff
------------
PIEDMONT
LITHIUM HYDROXIDE CONVERSION PLANT
SHEET TITLE
DRAINAGE ANALYSIS MAP,
PLAN VIEW
FILENAME OOC-02.DWG
SCALE 1 "=500'
SHEET OOC_02

This page intentionally left blank.

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

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

Hydrologic Soil Group —Gaston County, North Carolina
O
469700 470000 470300 470600 470900 471200
35' 24'30" N
00
35' 22'57" N
469700 470000 470300 470600 470900 471200
Map Scale: 1: 14,000 if printed on A portrait (85" x 11") sheet.
o Meters
N 0 200 400 800 1200
— Feet
0 500 1000 2000 300;
A Map projection: Web Mercator Comer coordinates: WGS84 Edge tics: LTrM Zone 17N WGS84
usDA Natural Resources Web Soil Survey
Conservation Service National Cooperative Soil Survey
471500
471500
471800
35' 24! 30"N
1
93
35' 22'57'N
471800
8/26/2021
Page 1 of 5

Hydrologic Soil Group —Gaston County, North Carolina
MAP LEGEND
Area of Interest (AOI)
Area of Interest (A01)
Soils
Soil Rating Polygons
0 A
0 A/D
0 B
0 B/D
C
0 C/D
0 D
Not rated or not available
Soil Rating Lines
r r A
r r A/D
r B
B/D
r r C
0 C/D
r r D
r r Not rated or not available
Soil Rating Points
0 A
0 A/D
B
B/D
MAP INFORMATION
p
C
The soil surveys that comprise your AOI were mapped at
1:24,000.
0
C/D
Please rely on the bar scale on each map sheet for map
0
D
measurements.
p
Not rated or not available
Source of Map: Natural Resources Conservation Service
Water Features
Web Soil Survey URL:
Streams and Canals
Coordinate System: Web Mercator (EPSG:3857)
Transportation
Maps from the Web Soil Survey are based on the Web Mercator
projection, which preserves direction and shape but distorts
Rails
distance and area. A projection that preserves area, such as the
#%-0
Interstate Highways
Albers equal-area conic projection, should be used if more
accurate calculations of distance or area are required.
US Routes
This product is generated from the USDA-NRCS certified data as
Major Roads
of the version date(s) listed below.
Local Roads
Soil Survey Area: Gaston County, North Carolina
Background
Survey Area Data: Version 20, Jun 4, 2020
®
Aerial Photography
Soil map units are labeled (as space allows) for map scales
1:50,000 or larger.
Date(s) aerial images were photographed: Apr 23, 2014—Nov
28, 2017
The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
imagery displayed on these maps. As a result, some minor
shifting of map unit boundaries may be evident.
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
87.3
CeB2
Cecil sandy clay loam, 2
B
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 ���
Appendices
Appendix E — Curve Number
and Time of Concentration

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

Table -12
Runoff Curve Numbers
Curve numbers for
---- ----------- --('i3Yr i#erap�it>rti----------------------------—L�yiirulSlIC BaalFi14L�--- -
A�'crakc pere�t
av cf lypc and hydrologi a coed i 6011 iii5prni&-L� ArCu , L' I
'FAY den-eli ed wha?r -urvas (w-gelalkin eswhftphed)
Opc;1 spmx if la% is, parks, *al f courses. cernalerks. cle, } 5':
Poor condition (grass cover < 3 i ) ............................ bpi
79
86
89
F air vandifion I grass cow 50% to 7M.................... 49
69
79
R4
GoM cojiditlon ($ms.L over> 75%)---------------.....-,..--- 34
61
74
80
1"kpCi'V100 :lr `HV
P;1 vd parking ]at!;, Awls, drivrwxys. E4r.
(excluding ri hl-ut-wa)............................,,.,..,.. 98
48
99
48
SIrew and roads:
Parrs& curbs and storm scw•crs (cxcluding
right-cf-way)...,,,.,.,,,,,,,,,,,,,,,,,,,,,.--.................... 98
9?:
9H
98
Paved. ap4i &fi�hts (Iris luding ry t-af way} .... 83
8is
92
93
Gravet (including right -A -way).......................... 76
85
89
191
Dirt {indudirig righi-or-way] .............................. 72
82
R7
get
Urban dratiicls:
Commcrcial and business„,,,,,,., ............................... , 85 89
92
94
95
lnduStrial............................... .,,,,,................................ 72 81
88
l
93
Resi&nval digricts key aq-trage lot sixi .
Ii� acm or luf& (t#1xm i'LcuscSI..................................... 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
Ag lmrar ��ds
Pasture, grassland or range i con witious for age for gazing
Poor hydrologic condition ..... "I'll—, ............................ 68
79
86
\4)
Fair h}dmlogiccondilPon ............................................
79
H4
GJwW hydrV19.9i-C c(widilion.......................................... 39
fit
74
NO
W
Poor hydrolcP& condition ........................................... 45
fw,
r
8.3
[air hydro ogic co ition .......... ............................... 36 �) 73 79
{ioibd hydrologic cwrdition....—.— .....................,,.,.,,., M r 77
Nr. MY graded art"
(p` vious arm Ofily. rio VqaiilIUd)-,,,,,,,,,,,,,,,,,--,,.... at, 91 94
I Mwaie nanoff co."iion, and la - IF, 2S.
2 The at•rrio pemm bYkpm arts shown wdawW'd lo&%•elgpIha: C+npo�lc CN'I. Oft? wsawpliafk� WC as DD11 Vs! imp=kK* am
" dlrrsrky COM es 1cd M 1he *coinage s}sirra irrWmiaas arm have a of ". and pwvw u s artm air cimriderc4 equivalern co qwn
tipara in goad hydmil it cmWliion,
I :� p;hOw" 41rc MVi+r*lcul Noihaac a1,rm-% rc. Cwr, iic (N'} nuv Ic w"cd fog odorvmib nwlim orapo rp�woca "iypc'
4 Pax: Furcsi Biter, mull hers, mid bnjA aw desiroyrd by hemN g,=ing or regvtar Naming.
Fair: Woo& arc grazed bYl1 rLw buried, snd some fin €I Boer c-overs Ihr mAl.
Good: Woods arc priAcded from graai.ag- and 17[Ler ;uid brush adegostety 4ovrr 1he 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
0.19
98
0.97
Woods
28.21
0.40
66
Grass
29.23
0.41
79
D
lWoods
12.10
11.00
183
10.03
COMPOSITE (B) 77.4
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
1.00
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
4.77
0.85
79
TOTAL COMPOSITE CN 78
DA4- STREAM CROSSING AT RAILROAD
SOIL GROUP
COVER TYPE
ACRES
%
CN
% of DA
B
Pvmt/Sidewall</Equipment pads
14.74
0.11
98
0.96
Woods
53.79
0.42
66
Grass
60.94
0.47
79
D
lWoods
13.87
10.96
183
10.04
Grass
10.16
10.04
189
COMPOSITE (B) 75.8
COMPOSITE (D) 83.2
TOTAL COMPOSITE CN 76

8/25/2021
PROJECT: PLI
SCENARIO: DA1-Stream Crossing at Road
Time of Concentration Worksheet
SCS TR-55 Method
DATE: 08/25/21
PREPARED BY: FLS
Drainage Area Information
Drainage Area Tc Summary Data
DRAINAGE AREA ID:
TOTAL BASIN LENGTH:
TOTAL ELEVATION UP:
TOTAL ELEVATION DOWN:
TOTAL ACRES:
DA 1
1980.7 ft
888.00
832.00
73.00
1
Flow Type
Sheet Flow
Shallow Concentrated Flow
Channel Flow - Rectangular
Channel Flow - Triangular
Channel Flow - Trapezoidal
Channel Flow - Circular
Length (ft)
Elev. Diff.
Tc
100.0
0.50
17.4 mins.
1880.7
55.50
10.8 mins.
0.0
0.00
0.0 mins.
0.0
0.00
0.0 mins.
0.0
0.00
1 0.0 mins.
0.0
0.00
0.0 mins.
NOTES:
Basin Totals-----+
28.1 mins.
,iis time of concentration calculation is based on survey data, aerial photography, and field investigation.
1. SHEET FLOW
2. SHALLOW CONCENTRATED
FLOW
Surface Description
Manning's "n"
2- Year, 24- Hr. Rain Fall (In)
Flow Length (ft)
Elevation Up (ft)
Elevation Down (ft)
Land Slope (ft/ft)
Time Of Concentration (Mins)
Segment #1 Segment #2
Segment #3
Segment #1 Segment #2
Surface Description Paved Unpaved
Flow Length (ft) 468.3 ft 1412.4 ft
Elevation Up (ft) 887.50 872.00
Elevation Down (ft) 872.00 832.00
Watercourse Slope (ft/ft) 0.033 0.028
Average Velocity (ft/Sec) 3.7 2.7
Time Of Concentration (Mins) 2.11 8.67
Segment #3
Grass
0.16
3.43
100.0 ft
888.00
887.50
0.005
17.35
Total Sheet
Flow Tc (Minutes):
17.4 min.
Total Shallow Concentrated Tc (Mins):
10.8 min.
CAUsers\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 1- Road 1 of3

8/25/2021
Time of Concentration Worksheet
SCS TR-55 Method
PROJECT: PLI DATE: 08/25/21
SCENARIO: DA1-Stream Crossing at Road PREPARED BY: FLS
3. CHANNEL FLOW - RECTANGULAR CHANNEL
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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Rectangular Channel Tc (Mins):
0.0 mins.
4. CHANNEL FLOW - TRIANGULAR CHANNEL
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 "n"
Average Velocity (ft/Sec)
Time Of Concentration (Mins)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Triangular
Channel Tc
0.0 min.
C:\Users\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 1- Road 2 of

8/25/2021
Time of Concentration Worksheet
SCS TR-55 Method
PROJECT: PLI DATE: 08/25/21
SCENARIO: DA1- Stream Crossing at Road PREPARED BY: FLS
5. CHANNEL FLOW - TRAPEZOIDAL CHANNEL
Surface Description
Bottom Width (ft)
Depth (ft)
Side Slopes (?H:1 V) (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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Time Of Concentration (Mins)
Total Trapezoidal Channel Tc
0.0 min.
6. CHANNEL FLOW - CIRCULAR CHANNEL (Gravity Flow)
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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Circular
Channel Tc
(Mins):
0.0 min.
7. Total Basin Time of Concentration (Mintues)
Total Basin Tc (Mins):
28.1 min.
C:\Users\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 1- Road 3 of

8/25/2021
PROJECT: PLI
SCENARIO: DA2- Crossing at Road
Time of Concentration Worksheet
SCS TR-55 Method
DATE: 08/25/21
PREPARED BY: FLS
Drainage Area Information
Drainage Area Tc Summary Data
DRAINAGE AREA ID:
TOTAL BASIN LENGTH:
TOTAL ELEVATION UP:
TOTAL ELEVATION DOWN:
TOTAL ACRES:
DA 2
367.1 ft
897.00
888.00
2.50
1
Flow Type
Sheet Flow
Shallow Concentrated Flow
Channel Flow - Rectangular
Channel Flow - Triangular
Channel Flow - Trapezoidal
Channel Flow - Circular
Length (ft)
Elev. Diff.
Tc
100.0
1.00
13.1 mins.
267.1
8.00
1.6 mins.
0.0
0.00
0.0 mins.
0.0
0.00
0.0 mins.
0.0
0.00
1 0.0 mins.
0.0
0.00
0.0 mins.
NOTES:
Basin Totals
MEM.
14.7 mins.
.ils time of concentration calculation is based on survey data, aerial photography, and field investigation.
1. SHEET FLOW
2. SHALLOW CONCENTRATED
FLOW
Segment #1 Segment #2
Surface Description Grass
Manning's "n" 0.16
2- Year, 24- Hr. Rain Fall (In) 3.43
Flow Length (ft) 100.0 ft
Elevation Up (ft) 897.00
Elevation Down (ft) 896.00
Land Slope (ft/ft) 0.010
Time Of Concentration (Mins) 13.15
Segment #3
Segment #1 Segment #2
Surface Description Unpaved
Flow Length (ft) 267.1 ft
Elevation Up (ft) 896.00
Elevation Down (ft) 888.00
Watercourse Slope (ft/ft) 0.030
Average Velocity (ft/Sec) 2.8
Time Of Concentration (Mins) 1.59
Segment #3
Total Sheet Flow Tc (Minutes):
13.1 min.
r Total Shallow Concentrated Tc (Mins):
1.6 min.
CAUsers\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 2- Road 1 of3

8/25/2021
Time of Concentration Worksheet
SCS TR-55 Method
PROJECT: PLI DATE: 08/25/21
SCENARIO: DA2- Crossing at Road PREPARED BY: FLS
3. CHANNEL FLOW - RECTANGULAR CHANNEL
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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Rectangular Channel Tc (Mins):
0.0 mins.
4. CHANNEL FLOW - TRIANGULAR CHANNEL
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 "n"
Average Velocity (ft/Sec)
Time Of Concentration (Mins)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Triangular
Channel Tc
0.0 min.
C:\Users\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 2- Road 2 of

8/25/2021
Time of Concentration Worksheet
SCS TR-55 Method
PROJECT: PLI DATE: 08/25/21
SCENARIO: DA2- Crossing at Road PREPARED BY: FLS
5. CHANNEL FLOW - TRAPEZOIDAL CHANNEL
Surface Description
Bottom Width (ft)
Depth (ft)
Side Slopes (?H:1 V) (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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Time Of Concentration (Mins)
Total Trapezoidal Channel Tc
0.0 min.
6. CHANNEL FLOW - CIRCULAR CHANNEL (Gravity Flow)
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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Circular
Channel Tc
(Mins):
0.0 min.
7. Total Basin Time of Concentration (Mintues)
Total Basin Tc (Mins):
14.7 min.
C:\Users\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 2- Road 3 of

8/25/2021
PROJECT: PLI
SCENARIO: DA3- Crossing at Road
Time of Concentration Worksheet
SCS TR-55 Method
DATE: 08/25/21
PREPARED BY: FLS
Drainage Area Information
Drainage Area Tc Summary Data
DRAINAGE AREA ID:
TOTAL BASIN LENGTH:
TOTAL ELEVATION UP:
TOTAL ELEVATION DOWN:
TOTAL ACRES:
DA 3
680.7 ft
897.00
870.00
5.59
1
Flow Type
Sheet Flow
Shallow Concentrated Flow
Channel Flow - Rectangular
Channel Flow - Triangular
Channel Flow - Trapezoidal
Channel Flow - Circular
Length (ft)
Elev. Diff.
Tc
100.0
2.00
10.0 mins.
580.7
25.00
2.9 mins.
0.0
0.00
0.0 mins.
0.0
0.00
0.0 mins.
0.0
0.00
1 0.0 mins.
0.0
0.00
0.0 mins.
NOTES:
Basin Totals
12.9 mins.
,iis time of concentration calculation is based on survey data, aerial photography, and field investigation.
1. SHEET FLOW
2. SHALLOW CONCENTRATED
FLOW
Surface Description
Manning's "n"
2- Year, 24- Hr. Rain Fall (In)
Flow Length (ft)
Elevation Up (ft)
Elevation Down (ft)
Land Slope (ft/ft)
Time Of Concentration (Mins)
Segment #1 Segment #2
Segment #3
Segment #1 Segment #2
Surface Description Unpaved
Flow Length (ft) 580.7 ft
Elevation Up (ft) 895.00
Elevation Down (ft) 870.00
Watercourse Slope (ft/ft) 0.043
Average Velocity (ft/Sec) 3.3
Time Of Concentration (Mins) 2.89
Segment #3
Grass
0.16
3.43
100.0 ft
897.00
895.00
0.020
9.97
Total Sheet
Flow Tc (Minutes):
10.0 min.
r Total Shallow Concentrated Tc (Mins):1
2.9 min.
CAUsers\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 3- Road t of3

8/25/2021
Time of Concentration Worksheet
SCS TR-55 Method
PROJECT: PLI DATE: 08/25/21
SCENARIO: DA3- Crossing at Road PREPARED BY: FLS
3. CHANNEL FLOW - RECTANGULAR CHANNEL
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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Rectangular Channel Tc (Mins):
0.0 mins.
4. CHANNEL FLOW - TRIANGULAR CHANNEL
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 "n"
Average Velocity (ft/Sec)
Time Of Concentration (Mins)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Triangular
Channel Tc
0.0 min.
C:\Users\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 3- Road 2 of

8/25/2021
Time of Concentration Worksheet
SCS TR-55 Method
PROJECT: PLI DATE: 08/25/21
SCENARIO: DA3- Crossing at Road PREPARED BY: FLS
5. CHANNEL FLOW - TRAPEZOIDAL CHANNEL
Surface Description
Bottom Width (ft)
Depth (ft)
Side Slopes (?H:1 V) (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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Time Of Concentration (Mins)
Total Trapezoidal Channel Tc
0.0 min.
6. CHANNEL FLOW - CIRCULAR CHANNEL (Gravity Flow)
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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Circular
Channel Tc
(Mins):
0.0 min.
7. Total Basin Time of Concentration (Mintues)
Total Basin Tc (Mins):
12.9 min.
C:\Users\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 3- Road 3 of

8/25/2021
PROJECT: PLI
SCENARIO: DA4- Stream Crossing at Railroad
Time of Concentration Worksheet
SCS TR-55 Method
DATE: 08/25/21
PREPARED BY: FLS
Drainage Area Information
Drainage Area Tc Summary Data
DRAINAGE AREA ID:
TOTAL BASIN LENGTH:
TOTAL ELEVATION UP:
TOTAL ELEVATION DOWN:
TOTAL ACRES:
DA 4
3117.8 ft
888.00
810.00
133.50
Flow Type
Sheet Flow
Shallow Concentrated Flow
Channel Flow - Rectangular
Channel Flow - Triangular
Channel Flow - Trapezoidal
Channel Flow - Circular
Length (ft)
Elev. Diff.
Tc
100.0
0.50
17.4 mins.
3017.8
77.50
19.0 mins.
0.0
0.00
0.0 mins.
0.0
0.00
0.0 mins.
0.0
0.00
1 0.0 mins.
0.0
0.00
0.0 mins.
NOTES:
Basin Totals-----+
36.3 mins.
,iis time of concentration calculation is based on survey data, aerial photography, and field investigation.
1. SHEET FLOW
2. SHALLOW CONCENTRATED
FLOW
Surface Description
Manning's "n"
2- Year, 24- Hr. Rain Fall (In)
Flow Length (ft)
Elevation Up (ft)
Elevation Down (ft)
Land Slope (ft/ft)
Time Of Concentration (Mins)
Segment #1 Segment #2
Segment #3
Segment #1 Segment #2
Surface Description Paved Unpaved
Flow Length (ft) 468.3 ft 2549.4 ft
Elevation Up (ft) 887.50 872.00
Elevation Down (ft) 872.00 810.00
Watercourse Slope (ft/ft) 0.033 0.024
Average Velocity (ft/Sec) 3.7 2.5
Time Of Concentration (Mins) 2.11 16.89
Segment #3
Grass
0.16
3.43
100.0 ft
888.00
887.50
0.005
17.35
Total Sheet
Flow Tc (Minutes):
17.4 min.
Total Shallow Concentrated Tc (Mins):
19.0 min.
CAUsers\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 4- Railroad t of3

8/25/2021
Time of Concentration Worksheet
SCS TR-55 Method
PROJECT: PLI DATE: 08/25/21
SCENARIO: DA4- Stream Crossing at Railroad PREPARED BY: FLS
3. CHANNEL FLOW - RECTANGULAR CHANNEL
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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Rectangular Channel Tc (Mins):
0.0 mins.
4. CHANNEL FLOW - TRIANGULAR CHANNEL
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 "n"
Average Velocity (ft/Sec)
Time Of Concentration (Mins)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Triangular
Channel Tc
0.0 min.
C:\Users\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 4- Railroad 2 of

8/25/2021
Time of Concentration Worksheet
SCS TR-55 Method
PROJECT: PLI DATE: 08/25/21
SCENARIO: DA4- Stream Crossing at Railroad PREPARED BY: FLS
5. CHANNEL FLOW - TRAPEZOIDAL CHANNEL
Surface Description
Bottom Width (ft)
Depth (ft)
Side Slopes (?H:1 V) (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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Time Of Concentration (Mins)
Total Trapezoidal Channel Tc
0.0 min.
6. CHANNEL FLOW - CIRCULAR CHANNEL (Gravity Flow)
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)
Segment #1
Segment #2
Segment #3
Segment #4
Segment #5
Segment #6
Segment #7
Segment #8
Segment #9
Total Circular
Channel Tc
(Mins):
0.0 min.
7. Total Basin Time of Concentration (Mintues)
Total Basin Tc (Mins):
36.3 min.
C:\Users\fsadler\Documents\PLI\Stormwater\
PLI TOC DA 4- Railroad 3 of

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

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

Precipitation Frequency Data Server
Page 1 of 4
NOAA Atlas 14, Volume 2, Version 3
Location name: Lincolnton, North Carolina, USA''
Latitude: 35.4667°, Longitude:-81.3333°
Elevation: 919.07 ft"
'source: ESRI Mapsk,,�
*' 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/hour)'
Average
recurrence interval (years)
11
2 11
5
10 11
25 11
50
1 100
200
500
1000
5-min
4.67
5.52
6.49
7.24
8.15
8.81
9.46
10.1
10.9
11.5
(4.28-5.08)
1 (5.06 6.02)
1 (5.95-7.09)
(6.60-7.88)
(7.39-8.88)
(7.94 9.61)
1 (8.48-10.3)
(8.96-11.1)
(9.54-12.0)
(9.96-12.7)
8.00
8.60
9.04
10-min
(7.10-8.77)
(7.55-9.47)
(7.85-10.0)
15-min
3.10
3.70
4.39
4.88
5.48
5.92
6.34
6.72
7.22
7.56
(2.85-3.38)
1 (3.40-4.04)
(4.02-4.79)
(4.46-5.32)
(4.98-5.98)
(5.34-6.46)
1 (5.68-6.92)
(5.98-7.37)
(6.33-7.95)
(6.56-8.38)
30-min
2.13
2.55
3.12
3.54
4.06
4.46
4.85
5.23
5.74
6.13
(1.95-2.32)
1 (2.35-2.79)
1 (2.85-3.40)
1 (3.23-3.85)
1 (3.68-4.43)
1 (4.02-4.86)
1 (4.35-5.30)
(4.65-5.74)
1 (5.04-6.32)
1 (5.32-6.78)
60-min
1.33
(1.22-1.45)
1.60
(1.47-1.75)
2.00
(1.83-2.18)
2.30
(2.10-2.51)
2.70
1 (2.45-2.95)
3.02
(2.72-3.30)
3.34
(2.99-3.65)
3.67
(3.26-4.02)
4.12
1 (3.61-4.54)
4.47
(3.88-4.95)
0.770
0.935
1.17
1.36
1.62
1.83
2.04
2.26
2.58
2.83
2-hr
(0.706-0.843)
(0.856-1.02)
(1.07-1.29)
1 (1.24-1.49) 11
(1.47-1.77)
(1.64-2.00)
(1.82-2.24)
1 (2.00-2.49)
1 (2.25-2.85)
1 (2.44-3.15)
0.549
0.664
0.837
0.975
1.17
1.33
1.50
1.68
1.94
2.15
3-hr
(0.503-0.605)
(0.608-0.732)
(0.764-0.921)
(0.886-1.07)
1 (1.06-1.29)
1 (1.19-1.46)
1 (1.33-1.65)
1 (1.48-1.86)
1 (1.67-2.15)
1 (1.83-2.40)
0.339
0.408
0.512
0.595
0.714
0.812
0.916
1.03
1.19
1.32
6-hr
(0.312-0.370)
(0.376-0.447)
(0.469-0.560)
(0.544-0.650)
(0.647-0.779)
(0.731-0.887)
(0.817-1.00)
(0.907-1.13)
1 (1.03-1.31)
0.205
0.248
0.310
0.361
0.431
0.490
0.551
0.616
0.708
0.784
12-hr
(0.189-0.223)
(0.228-0.270)
(0.285-0.338)
(0.330-0.393)
(0.392-0.470)
(0.442-0.533)
(0.493-0.599)
(0.545-0.671)
(0.618-0.774)
(0.675-0.860)
0.124
0.150
0.189
0.220
0.262
0.296
0.331
0.367
0.416
0.456
24-hr
(0.116-0.133)
(0.140-0.161)
(0.176-0.203)
(0.205-0.236)
(0.243-0.281)
(0.274-0.317)
(0.304-0.354)
(0.336-0.393)
(0.380-0.447)
(0.414-0.490)
2-day
0. 69-0 079
0. 8 -0 096
0.104-0 120
0.120-0.9138
0.14170.3164
0.159-0.2184
0.1076-0 205
0.194-0 227
0.2118-0 257
0.2372--0 281
0.052
0.063
0.078
0.090
0.106
0.119
0.133
0.146
0.165
0.180
3-day
(0.049-0.056)
(0.059-0.067)
(0.073-0.084)
(0.084-0.097)
(0.099-0.114)
(0.110-0.128)
(0.122-0.142)
(0.135-0.157)
(0.151-0.178)
(0.164-0.194)
0.041
0.050
0.061
0.071
0.083
0.093
0.104
0.114
0.128
0.140
4-day
(0.039-0.044)
(0.046-0.053)
(0.057-0.066)
(0.066-0.076)
(0.077-0.089)
(0.086-0.100)
(0.095-0.111)
(0.105-0.122)
(0.118-0.138)
(0.127-0.150)
0.027
0.033
0.040
0.045
0.053
0.059
0.065
0.072
0.080
0.087
7-day
(0.026-0 029)
(0.031-0.035)
(0.037-0.042)
(0.043-0.048)
(0.050-0.057)
(0.055-0.063)
(0.061-0.070)
(0.066-0.076)
(0.074-0.086)
(0.080-0.093)
0.041
10-day
0 021--0 023
0.02 -0 028
0.030-0 033
0.03 -0 038
0.038-0 043
0.04 -0 048
0.046-0 052
0050-0 057
0.05 -0 063
0060-0 068
0.015
0.017
0.020
0.023
0.026
0.029
0.031
0.034
0.037
0.040
20-day
(0.014-0.015)
(0.016-0.018)
(0.019-0.021)
(0.022-0.024)
(0.025-0.028)
(0.027-0.030)
(0.029-0.033)
(0.032-0.036)
(0.035-0.040)
(0.037-0.043)
0.012
0.014
0.016
0.018
0.020
0.022
0.024
0.025
0.028
0.029
30-day
(0.011-0.013)
(0.013-0.015)
(0.016-0.017)
(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)
0.010
0.012
0.013
0.015
0.016
0.017
0.019
0.020
0.021
0.022
45-day
(0.010-0.011)
(0.011-0.012)
(0.013-0.014)
(0.014-0.015)
(0.016-0.017)
(0.017-0.018)
(0.018-0.020)
(0.019-0.021)
(0.020-0.022)
(0.021-0.024)
0.009
0.010
0.012
0.013
0.014
0.015
0.016
0.017
0.018
0.019
60-day
(0.009-0009)
(0.010-0.011)
(0.011-0.012)
(0.012-0.013)
(0.014-0.015)
(0.015-0.016)
(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 to Too
https://hdsc.nws.noaa.gov/hdsc/pfds/pfds_printpage.html?lat=3 5.4667&Ion=-81.3333 &dat... 8/20/2021

Precipitation Frequency Data Server
Page 2 of 4
PF graphical
PD5-based intensity -duration -frequency (IDF) curves
Latitude: 35.4667 Longitude:-81.3333'
100.000
10.000
r
ZI
1.000
C
a
C
r4
m m
r4 ru
-y
rP r4
-y
u9
6
ri
u1
rl
O
n
O
lG
N A
6 N
�" 1
�
N
-4
N f�] V
� -V
A OO
ri
-y
OO 6
INrn
-y
Ln OO
V �
Duration
IUO.000
r
10.000
G
41
c
1.000
a
c
c
° 0.100
a 0.010
0.001 1 ' ' ' ' ' ' ' ' 1
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval [years]
NOAA Atlas 14, Volume 2, Version 3 Created {GMT}: Fri Aug 20 14:36:00 2021
Back to Top
Average recufrence
inleml
(years}
— 1
2
5
— 10
25
50
100
200
500
1000
Duration
— 5-min —
2-day
— 1Dmin —
3-day
15min —
4-day
— 30-min —
7Aay
— 6Dmin —
10-say
— 2-hr —
20-day
— 3-hr —
30-day
— 5a1r —
45-day
— 12-hr —
60-day
— 2d-hr
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PLC I Lithium Hydroxide Conversion Plant — Stormwater Calculations ���
Appendices
Appendix G — Sediment
Basin Calculations

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

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 1 10302238
DATE: 08.27.2021 BY: AKL F)R
REVISED: RVW: VH
Riser Sediment Basin : SEDIMENT BASIN 1
Drainage Area Characteristics
Total drainage area (TDA)1
11.16 ac
Disturbed area (DA)
6.68 ac
Rational Coefficient (C)2
0.60
Time of Concentration (Tc)3
5.0 min
10 Yr Storm Rainfall Intensity (i)4
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)4
8.2 in/hr
Design Criteria
Bottom Elevation
832.00 msl
Depth of Storage Volume
2.50 ft
Depth of Flow over Riser (1 ft min)5
1.00 ft
Depth of Flow over Emergency Spillway
0.50 ft
25 Yr Storm Freeboard (1 ft req'd)5
1.00 ft
Basin Configuration
Bottom Elevation
832.00 msl
Sediment Storage Elevation
834.50 msl
Riser Crest
834.50 msl
Emergency Spillway Crest
835.50 msl
,Top of Berm
837.00 msl
Skimmer Outlet
Desired Skimmer Drawdown Time (td)6
72 hrs
Desired Skimmer Drawdown Rate (Qd)
6,696 ft3/day
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
Required Storage Volume
10 Yr Peak Flow (Q10)
48.61 cfs
25 Yr Peak Flow (Q25)
54.77 cfs
Req'd Min. Surface Area per cfs of Q25)5
23,826 sf
Req'd Min. Storage Volume per ac of TDA)5
20,088 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume cf
832.00
0.00
20,173
0
833.00
1.00
22,098
21,128
834.00
2.00
24,079
44,210
835.00
3.00
26,116
69,300
836.00
4.00
28,211
96,457
837.00
5.00
30,362
125,737
Basin Size Check
Basin Surface Area Provided at Spillway Crest 25,098 sf
Basin Storage Volume Provided Below Spillway Crest 56,503 cf
Barrel
Riser Diameter (15 in min)5
36 in
Riser Flow as Weir13
29.22 cfs
Barrel Diameters
18 in
Riser Flow as Orifice14
34.04 cfs
Barrel Invert Elevation
831.50 msl
Barrel Length
50.00 ft
Barrel Flow as Orifice14
15.34 cfs
Barrel Marming's IN 10
0.025
Barrel Flow as Pipe15
11.03 cfs
Sharp Crested Weir Coefficient (C)11
3.1
Orifice Coefficient (C)12
0.6
Controlling Flow through Riser and Barrel Spillway
11.03
Barrel
Riser Diameter (15 in min)5
72 in
Riser Flow as Weir13
58.43 cfs
Barrel Diameters DOUBLE
24 in
Riser Flow as Orifice14
136.14 cfs
Barrel Invert Elevation
831.50 msl
Barrel Length
50.00 ft
Barrel Flow as Orifice14 DOUBLE
52.40 cfs
Barrel Marming's IN 10
0.025
Barrel Flow as Pipe15 DOUBLE
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
Total of controlling Barrel Flows 53.17 cfs
Spillway
Minimum Allowable Spillway Length16 20 ft Difference b/n 10 Yr Peak Flow and Riser/Barrel Flow 1.61 cfs
Broad Crested Weir Coefficient (C)17 2.80 Design Spillway Length13 20 ft
Page 1 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)I
REVISED: RVW: VH
Concrete
Length of Exposed Outlet Pie
10 ft
Buoyancy's 6371 Ibs
Concrete Anchor Width
7.0 ft
Weight of Concrete Anchor 7105 Ibs
Concrete Anchor Length
7.0 ft
Concrete Anchor Thickness
1.00 ft
Safety Factor's 1.1
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 6.61 - 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 equatii
(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 corrugated metal pipe risers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
12. 0.6 for corrugated metal nine ricers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
13. Weir equation: Q = CLH' S (see note 11)
14. Orifice equation: Q = CA (2gHr5 (see note 12)
15. Pipe Flow equation: 2gh �O5 ` See
Q = a [t+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 1.1 per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
Page 2 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 1 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Riser Sediment Basin : SEDIMENT BASIN 2
Drainage Area Characteristics
Total drainage area (TDA)1
5.79 ac
Disturbed area (DA)
5.79 ac
Rational Coefficient (C)2
0.60
Time of Concentration (Tc)3
5.0 min
10 Yr Storm Rainfall Intensity (i)4
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)4
8.2 in/hr
Design Criteria
Bottom Elevation
825.00 msl
Depth of Storage Volume
2.50 ft
Depth of Flow over Riser (1 ft min)5
1.00 ft
Depth of Flow over Emergency Spillway
0.50 ft
25 Yr Storm Freeboard (1 ft req'd)5
1.00 ft
Basin Configuration
Bottom Elevation
825.00 msl
Sediment Storage Elevation
827.50 msl
Riser Crest
827.50 msl
Emergency Spillway Crest
828.50 msl
,Top of Berm
830.00 msl
Skimmer Outlet
Desired Skimmer Drawdown Time (td)6
72 hrs
Desired Skimmer Drawdown Rate (Qd)
3,474 ft3/day
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
Required Storage Volume
10 Yr Peak Flow (Q10)
25.22 cfs
25 Yr Peak Flow (Q25)
28.42 cfs
Req'd Min. Surface Area per cfs of Q25)5
12,362 sf
Req'd Min. Storage Volume per ac of TDA)5
10,422 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume cf
825.00
0.00
9,393
0
826.00
1.00
11,000
10,186
827.00
2.00
12,665
22,009
828.00
3.00
14,386
35,525
829.00
4.00
16,162
50,790
830.00
5.00
17,996
67,861
Basin Size Check
Basin Surface Area Provided at Spillway Crest 13,526 sf
Basin Storage Volume Provided Below Spillway Crest 28,555 cf
Barrel
Riser Diameter (15 in min)5
72 in
Riser Flow as Weir13
58.43 cfs
Barrel Diameters DOUBLE
24 in
Riser Flow as Orifice14
136.14 cfs
Barrel Invert Elevation
824.00 msl
Barrel Length
50.00 ft
Barrel Flow as Orifice14
56.60 cfs
Barrel Marming's IN 10
0.025
Barrel Flow as Pipe15
45.51 cfs
Sharp Crested Weir Coefficient (C)11
3.1
Orifice Coefficient (C)12
0.6
Controlling Flow through Riser and Barrel Spillway
45.51 cfs
Spillway
Minimum Allowable Spillway Length16 20 ft Difference b/n 10 Yr Peak Flow and Riser/Barrel Flow -17.09 cfs
Broad Crested Weir Coefficient (C)17 2.80 Design Spillway Length13 20 ft
Concrete
Length of Exposed Outlet Pipe
10 ft
Buoyancy" 6371 Ibs
Concrete Anchor Width
6.5 ft
Weight of Concrete Anchor 9189 Ibs
Concrete Anchor Length
6.5 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 3 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)I
REVISED: - 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, http://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 equath CC
D=�Qa/(2310*VH) (inch..) (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 corrugated metal pipe risers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
12. 0.6 for corrugated metal nines ricers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
13. Weir equation: Q = CLH15 (see note 11)
14. Orifice equation: Q = CA (2gHr5 (see note 12)
15. Pipe Flow equation: 2gh O5 * See
Q=a [l+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 1.1 per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
Page 4 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Riser Sediment Basin : SEDIMENT BASIN 3
Drainage Area Characteristics
Total drainage area (TDA)1
3.93 ac
Disturbed area (DA)
3.93 ac
Rational Coefficient (C)2
0.60
Time of Concentration ITj3
5.0 min
10 Yr Storm Rainfall Intensity (i)4
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)4
8.2 in/hr
Design Criteria
Bottom Elevation
808.00 msl
Depth of Storage Volume
2.50 ft
Depth of Flow over Riser (1 ft min)5
1.00 ft
Depth of Flow over Emergency Spillway
0.50 ft
25 Yr Storm Freeboard (1 ft req'd)5
1.00 ft
Basin Configuration
Bottom Elevation
808.00 msl
Sediment Storage Elevation
810.50 msl
Riser Crest
810.50 msl
Emergency Spillway Crest
811.50 msl
,Top of Berm
813.00 msl
Skimmer Outlet
Desired Skimmer Drawdown Time (td)6
72 hrs
Desired Skimmer Drawdown Rate (Qd)
2,358 ft3/day
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
Required Storage Volume
10 Yr Peak Flow (Q10)
17.12 cfs
25 Yr Peak Flow (Q25)
19.29 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
8,390 sf
Req'd Min. Storage Volume
(1800 cf per ac of TDA)5
7,074 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
808.00
0.00
5,874
0
809.00
1.00
7,118
6,486
810.00
2.00
8,435
14,253
811.00
3.00
9,809
23,367
812.00
4.00
11,239
33,882
813.00
5.00
12,726
45,857
Basin Size Check
Basin Surface Area Provided at Spillway Crest 9,122 sf
Basin Storage Volume Provided Below Spillway Crest 18,641 cf
Barrel
Riser Diameter (15 in min)5
48 in
Riser Flow as Weir13
38.96 cfs
Barrel Diameters
24 in
Riser Flow as Orifice14
60.51 cfs
Barrel Invert Elevation
807.50 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
Spillway
Minimum Allowable Spillway Length16 20 ft Difference b/n 10 Yr Peak Flow and Riser/Barrel Flow -1.78 cfs
Broad Crested Weir Coefficient (C)17 2.80 Design Spillway Length13 20 ft
Concrete
Length of Exposed Outlet Pie
10 ft
Buoyancy18 3921 Ibs
Concrete Anchor Width
6.0 ft
Weight of Concrete Anchor 5220 Ibs
Concrete Anchor Length
6.0 ft
Concrete Anchor Thickness
1.00 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 5 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)I
REVISED: - 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, http://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 equath CC
D=�Qa/(2310*VH) (inch..) (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 corrugated metal pipe risers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
12. 0.6 for corrugated metal nines ricers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
13. Weir equation: Q = CLH15 (see note 11)
14. Orifice equation: Q = CA (2gHr5 (see note 12)
15. Pipe Flow equation: 2gh O5 * See
Q=a [l+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 1.1 per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
Page 6 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Riser Sediment Basin : SEDIMENT BASIN 4
Drainage Area Characteristics
Total drainage area (TDA)1
8.00 ac
Disturbed area (DA)
8.00 ac
Rational Coefficient (C)2
0.60
Time of Concentration ITj3
5.0 min
10 Yr Storm Rainfall Intensity (i)4
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)4
8.2 in/hr
Design Criteria
Bottom Elevation
813.00 msl
Depth of Storage Volume
2.50 ft
Depth of Flow over Riser (1 ft min)5
1.00 ft
Depth of Flow over Emergency Spillway
0.50 ft
25 Yr Storm Freeboard (1 ft req'd)5
1.00 ft
Basin Configuration
Bottom Elevation
813.00 msl
Sediment Storage Elevation
815.50 msl
Riser Crest
815.50 msl
Emergency Spillway Crest
816.50 msl
,Top of Berm
818.00 msl
Skimmer Outlet
Desired Skimmer Drawdown Time (td)6
72 hrs
Desired Skimmer Drawdown Rate (Qd)
4,800 ft3/day
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
Required Storage Volume
10 Yr Peak Flow (Q10)
34.85 cfs
25 Yr Peak Flow (Q25)
39.26 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
17,080 sf
Req'd Min. Storage Volume
(1800 cf per ac of TDA)5
14,400 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
813.00
0.00
12,899
0
814.00
1.00
14,609
13,745
815.00
2.00
16,375
29,229
816.00
3.00
18,198
46,507
817.00
4.00
20,007
65,603
818.00
5.00
22,013
86,605
Basin Size Check
Basin Surface Area Provided at Spillway Crest 17,287 sf
Basin Storage Volume Provided Below Spillway Crest 37,643 cf
Barrel
Riser Diameter (15 in min)5
72 in
Riser Flow as Weir13
58.43 cfs
Barrel Diameters DOUBLE
24 in
Riser Flow as Orifice14
136.14 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
42.13 cfs
Spillway
Minimum Allowable Spillway Length16 20 ft Difference b/n 10 Yr Peak Flow and Riser/Barrel Flow -2.87 cfs
Broad Crested Weir Coefficient (C)17 2.80 Design Spillway Length13 20 ft
Concrete
Length of Exposed Outlet Pie
10 ft
Buoyancy18 6371 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 1.2
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 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)I
REVISED: - 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, http://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 equath CC
D=�Qa/(2310*VH) (inch..) (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 corrugated metal pipe risers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
12. 0.6 for corrugated metal nines ricers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
13. Weir equation: Q = CLH15 (see note 11)
14. Orifice equation: Q = CA (2gHr5 (see note 12)
15. Pipe Flow equation: 2gh O5 * See
Q=a [l+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 1.1 per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
Page 8 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Riser Sediment Basin : SEDIMENT BASIN 5
Drainage Area Characteristics
Total drainage area (TDA)1
4.50 ac
Disturbed area (DA)
4.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration ITj3
5.0 min
10 Yr Storm Rainfall Intensity (i)4
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)4
8.2 in/hr
Design Criteria
Bottom Elevation
828.00 msl
Depth of Storage Volume
1.80 ft
Depth of Flow over Riser (1 ft min)5
1.00 ft
Depth of Flow over Emergency Spillway
0.20 ft
25 Yr Storm Freeboard (1 ft req'd)5
1.00 ft
Basin Configuration
Bottom Elevation
828.00 msl
Sediment Storage Elevation
829.80 msl
Riser Crest
829.80 msl
Emergency Spillway Crest
830.80 msl
,Top of Berm
832.00 msl
Skimmer Outlet
Desired Skimmer Drawdown Time (td)6
72 hrs
Desired Skimmer Drawdown Rate (Qd)
2,700 ft3/day
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
Required Storage Volume
10 Yr Peak Flow (Q10)
19.60 cfs
25 Yr Peak Flow (Q25)
22.09 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
9,607 sf
Req'd Min. Storage Volume
(1800 cf per ac of TDA)5
8,100 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
828.00
0.00
8,809
0
829.00
1.00
10,387
9,587
830.00
2.00
12,048
20,794
831.00
3.00
13,778
33,698
832.00
4.00
15,576
48,366
Basin Size Check
Basin Surface Area Provided at Spillway Crest 11,716 sf
Basin Storage Volume Provided Below Spillway Crest 18,423 cf
Barrel
Riser Diameter (15 in min)5
48 in
Riser Flow as Weir13
38.96 cfs
Barrel Diameters
24 in
Riser Flow as Orifice14
60.51 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
Spillway
Minimum Allowable Spillway Length16 20 ft Difference b/n 10 Yr Peak Flow and Riser/Barrel Flow 1.02 cfs
Broad Crested Weir Coefficient (C)17 2.80 Design Spillway Length13 20 ft
Concrete
Length of Exposed Outlet Pie
10 ft
Buoyancy18 3372 Ibs
Concrete Anchor Width
6.0 ft
Weight of Concrete Anchor 5220 Ibs
Concrete Anchor Length
6.0 ft
Concrete Anchor Thickness
1.00 ft
Safety Factor19 1.5
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 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)I
REVISED: - 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, http://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 equath CC
D=�Qa/(2310*VH) (inch..) (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 corrugated metal pipe risers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
12. 0.6 for corrugated metal nines ricers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
13. Weir equation: Q = CLH15 (see note 11)
14. Orifice equation: Q = CA (2gHr5 (see note 12)
15. Pipe Flow equation: 2gh O5 * See
Q=a [t+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 1.1 per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
Page 10 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Riser Sediment Basin : SEDIMENT BASIN 6
Drainage Area Characteristics
Total drainage area (TDA)1
5.50 ac
Disturbed area (DA)
5.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration ITj3
5.0 min
10 Yr Storm Rainfall Intensity (i)4
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)4
8.2 in/hr
Design Criteria
Bottom Elevation
833.00 msl
Depth of Storage Volume
1.80 ft
Depth of Flow over Riser (1 ft min)5
1.00 ft
Depth of Flow over Emergency Spillway
0.20 ft
25 Yr Storm Freeboard (1 ft req'd)5
1.00 ft
Basin Configuration
Bottom Elevation
833.00 msl
Sediment Storage Elevation
834.80 msl
Riser Crest
834.80 msl
Emergency Spillway Crest
835.80 msl
,Top of Berm
837.00 msl
Skimmer Outlet
Desired Skimmer Drawdown Time (td)6
72 hrs
Desired Skimmer Drawdown Rate (Qd)
3,300 ft3/day
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
Required Storage Volume
10 Yr Peak Flow (Q10)
23.96 cfs
25 Yr Peak Flow (Q25)
26.99 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
11,742 sf
Req'd Min. Storage Volume
(1800 cf per ac of TDA)5
9,900 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
833.00
0.00
11,208
0
834.00
1.00
12,924
12,056
835.00
2.00
14,717
25,867
836.00
3.00
16,560
41,496
837.00
4.00
18,449
58,992
Basin Size Check
Basin Surface Area Provided at Spillway Crest 14,358 sf
Basin Storage Volume Provided Below Spillway Crest 22,964 cf
Barrel
Riser Diameter (15 in min)5
60 in
Riser Flow as Weir13
48.69 cfs
Barrel Diameters
36 in
Riser Flow as Orifice14
94.54 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
48.69 cfs
Spillway
Minimum Allowable Spillway Length16 20 ft Difference b/n 10 Yr Peak Flow and Riser/Barrel Flow -21.70 cfs
Broad Crested Weir Coefficient (C)17 2.80 Design Spillway Length13 20 ft
Concrete
Length of Exposed Outlet Pie
10 ft
Buoyancy18 6616 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 1.6
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 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)I
REVISED: - 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, http://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 equath CC
D=�Qa/(2310*VH) (inch..) (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 corrugated metal pipe risers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
12. 0.6 for corrugated metal nines ricers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
13. Weir equation: Q = CLH15 (see note 11)
14. Orifice equation: Q = CA (2gHr5 (see note 12)
15. Pipe Flow equation: 2gh O5 * See
Q=a [l+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 1.1 per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
Page 12 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Riser Sediment Basin : SEDIMENT BASIN 7 - Phase 1
Drainage Area Characteristics
Total drainage area (TDA)1
7.55 ac
Disturbed area (DA)
6.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration ITj3
5.0 min
10 Yr Storm Rainfall Intensity (i)4
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)4
8.2 in/hr
Design Criteria
Bottom Elevation
891.00 msl
Depth of Storage Volume
1.80 ft
Depth of Flow over Riser (1 ft min)5
1.00 ft
Depth of Flow over Emergency Spillway
0.20 ft
25 Yr Storm Freeboard (1 ft req'd)5
1.00 ft
Basin Configuration
Bottom Elevation
891.00 msl
Sediment Storage Elevation
892.80 msl
Riser Crest
892.80 msl
Emergency Spillway Crest
893.80 msl
,Top of Berm
895.00 msl
Skimmer Outlet
Desired Skimmer Drawdown Time (td)6
72 hrs
Desired Skimmer Drawdown Rate (Qd)
4,530 ft3/day
Skimmer Size
6.0 in
Head on Orifice (H)5
0.417 ft
Calculated Orifice Diameter?
1.743 in
Actual Orifice Diameter$
1.750 in
Actual Skimmer Drawdown Time?
71 hrs
Required Storage Volume
10 Yr Peak Flow (Q10)
32.89 cfs
25 Yr Peak Flow (Q25)
37.06 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
16,119 sf
Req'd Min. Storage Volume
(1800 cf per ac of TDA)5
13,590 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
891.00
0.00
15,267
0
892.00
1.00
17,072
16,161
893.00
2.00
18,394
33,890
894.00
3.00
20,852
53,500
895.00
4.00
22,827
75,332
Basin Size Check
Basin Surface Area Provided at Spillway Crest 18,130 sf
Basin Storage Volume Provided Below Spillway Crest 30,240 cf
Barrel
Riser Diameter (15 in min)5
72 in
Riser Flow as Weir13
58.43 cfs
Barrel Diameters DOUBLE
24 in
Riser Flow as Orifice14
136.14 cfs
Barrel Invert Elevation
890.20 msl
Barrel Length
50.00 ft
Barrel Flow as Orifice14
48.78 cfs
Barrel Manning's N10
0.025
Barrel Flow as Pipe15
39.22 cfs
Sharp Crested Weir Coefficient (C)11
3.1
Orifice Coefficient (C)12
0.6
Controlling Flow through Riser and Barrel Spillway
39.22 cfs
Spillway
Minimum Allowable Spillway Length16 10 ft Difference b/n 10 Yr Peak Flow and Riser/Barrel Flow -2.17 cfs
Broad Crested Weir Coefficient (C)17 2.80 Design Spillway Length13 10 ft
Concrete
Length of Exposed Outlet Pie
20 ft
Buoyancy18 7096 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 1.5
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 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)I
REVISED: - 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, http://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 equath CC
D=�Qa/(2310*VH) (inch..) (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 corrugated metal pipe risers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
12. 0.6 for corrugated metal nines ricers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
13. Weir equation: Q = CLH15 (see note 11)
14. Orifice equation: Q = CA (2gHr5 (see note 12)
15. Pipe Flow equation: 2gh O5 * See
Q=a [l+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 1.1 per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
Page 14 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 1 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Riser Sediment Basin : SEDIMENT BASIN 8 - Phase 1
Drainage Area Characteristics
Total drainage area (TDA)1
5.65 ac
Disturbed area (DA)
5.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration (Tc)3
5.0 min
10 Yr Storm Rainfall Intensity (i)4
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)4
8.2 in/hr
Design Criteria
Bottom Elevation
874.00 msl
Depth of Storage Volume
2.50 ft
Depth of Flow over Riser (1 ft min)5
1.00 ft
Depth of Flow over Emergency Spillway
0.50 ft
25 Yr Storm Freeboard (1 ft req'd)5
1.00 ft
Basin Configuration
Bottom Elevation
874.00 msl
Sediment Storage Elevation
876.50 msl
Riser Crest
876.50 msl
Emergency Spillway Crest
877.50 msl
,Top of Berm
879.00 msl
Skimmer Outlet
Desired Skimmer Drawdown Time (td)6
72 hrs
Desired Skimmer Drawdown Rate (Qd)
3,390 ft3/day
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
Required Storage Volume
10 Yr Peak Flow (Q10)
24.61 cfs
25 Yr Peak Flow (Q25)
27.73 cfs
Req'd Min. Surface Area per cfs of Q25)5
12,063 sf
Req'd Min. Storage Volume per ac of TDA)5
10,170 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume cf
874.00
0.00
9,393
0
875.00
1.00
11,000
10,186
876.00
2.00
12,665
22,009
877.00
3.00
14,386
35,525
878.00
4.00
16,162
50,790
879.00
5.00
17,996
67,861
Basin Size Check
Basin Surface Area Provided at Spillway Crest 13,526 sf
Basin Storage Volume Provided Below Spillway Crest 28,555 cf
Barrel
Riser Diameter (15 in min)5
72 in
Riser Flow as Weir13
58.43 cfs
Barrel Diameters DOUBLE
24 in
Riser Flow as Orifice14
136.14 cfs
Barrel Invert Elevation
874.00 msl
Barrel Length
50.00 ft
Barrel Flow as Orifice14
47.83 cfs
Barrel Marming's IN 10
0.025
Barrel Flow as Pipe15
38.46 cfs
Sharp Crested Weir Coefficient (C)11
3.1
Orifice Coefficient (C)12
0.6
Controlling Flow through Riser and Barrel Spillway
38.46 cfs
Spillway
Minimum Allowable Spillway Length16 20 ft Difference b/n 10 Yr Peak Flow and Riser/Barrel Flow -10.73 cfs
Broad Crested Weir Coefficient (C)17 2.80 Design Spillway Length13 20 ft
Concrete
Length of Exposed Outlet Pipe
10 ft
Buoyancy" 6371 Ibs
Concrete Anchor Width
7.5 ft
Weight of Concrete Anchor 8156 Ibs
Concrete Anchor Length
7.5 ft
Concrete Anchor Thickness
1.00 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 15 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)I
REVISED: - 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, http://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 equath CC
D=�Qa/(2310*VH) (inch..) (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 corrugated metal pipe risers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
12. 0.6 for corrugated metal nines ricers per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
13. Weir equation: Q = CLH15 (see note 11)
14. Orifice equation: Q = CA (2gHr5 (see note 12)
15. Pipe Flow equation: 2gh O5 * See
Q=a [l+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 1.1 per Section 8.07 - Sediment Basin Design of the NCDEQ Erosion and Sediment Control Planning and Design Manual.
Page 16 of 35

PLC I Lithium Hydroxide Conversion Plant — Stormwater Calculations ���
Appendices
Appendix H — Sediment Trap
Calculations

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

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Sediment Trap: ST1
Drainage Area Characteristics
Total drainage area (TDA)'
0.50 ac
Disturbed area (DA)
0.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 891.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
891.00 msl
Sediment Storage Elevation
893.00 msl
Emergency Spillway Crest
894.00 msl
Top of Berm
895.50 rn l
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
2.18 cfs
25 Yr Peak Flow (Q25)
2.45 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
1,067 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
1,800 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
891.00
0.00
852
0
892.00
1.00
1,091
969
893.00
2.00
1,355
2,190
894.00
3.00
1,645
3,687
895.00
4.00
1,960
5,488
Basin Size Check
Basin Surface Area Provided at Spillway Crest 1,355 sf
Basin Storage Volume Provided Below Spillway Crest 2,190 cf
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: rD = CLH1 5
Page 17 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST2
Drainage Area Characteristics
Total drainage area (TDA)'
0.40 ac
Disturbed area (DA)
0.40 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 883.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
883.00 msl
Sediment Storage Elevation
885.00 msl
Emergency Spillway Crest
886.00 msl
Top of Berm
887.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
1.74 cfs
25 Yr Peak Flow (Q25)
1.96 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5 854 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5 1,440 cf
Basin Size
Elev. msl
Depth (ft)
I Area sf
Cumulative Volume c
883.00
0.00
642
0
884.00
1.00
853
745
885.00
2.00
1,088
1,713
886.00
3.00
1,349
2,929
887.00
4.00
1,635
4,419
Basin Size Check
Basin Surface Area Provided at Spillway Crest 1,088 sf
Basin Storage Volume Provided Below Spillway Crest 1,713 cf
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: rD = CLH1 5
Page 18 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST3
Drainage Area Characteristics
Total drainage area (TDA)'
0.65 ac
Disturbed area (DA)
0.65 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 878.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
878.00 msl
Sediment Storage Elevation
880.00 msl
Emergency Spillway Crest
881.00 msl
Top of Berm
882.50 rn l
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
2.83 cfs
25 Yr Peak Flow (Q25)
3.19 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
1,388 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
2,340 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
878.00
0.00
1,081
0
879.00
1.00
1,348
1,212
880.00
2.00
1,640
2,704
881.00
3.00
1,957
4,500
882.00
4.00
2,300
6,626
Basin Size Check
Basin Surface Area Provided at Spillway Crest 1,640 sf
Basin Storage Volume Provided Below Spillway Crest 2,704 cf
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: rD = CLH1 5
Page 19 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST4
Drainage Area Characteristics
Total drainage area (TDA)'
1.50 ac
Disturbed area (DA)
1.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 878.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
878.00 msl
Sediment Storage Elevation
880.00 msl
Emergency Spillway Crest
881.00 msl
Top of Berm
882.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
6.53 cfs
25 Yr Peak Flow (Q25)
7.36 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
3,202 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
5,400 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
878.00
0.00
2,483
0
879.00
1.00
2,877
2,678
880.00
2.00
3,296
5,762
881.00
3.00
3,740
9,277
882.00
4.00
4,210
13,250
Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,296 sf
Basin Storage Volume Provided Below Spillway Crest 5,762 cf
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: rD = CLH1 5
Page 20 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST5
Drainage Area Characteristics
Total drainage area (TDA)'
1.75 ac
Disturbed area (DA)
1.75 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 842.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
842.00 msl
Sediment Storage Elevation
844.00 msl
Emergency Spillway Crest
845.00 msl
Top of Berm
846.50 rn l
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
7.62 cfs
25 Yr Peak Flow (Q25)
8.59 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
3,736 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
6,300 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
842.00
0.00
3,069
0
843.00
1.00
3,505
3,285
844.00
2.00
3,966
7,018
845.00
3.00
4,453
11,225
846.00
4.00
4,964
15,931
Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,966 sf
Basin Storage Volume Provided Below Spillway Crest 7,018 cf
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: rD = CLH1 5
Page 21 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Sediment Trap: ST6
Drainage Area Characteristics
Total drainage area (TDA)'
1.50 ac
Disturbed area (DA)
1.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 836.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
836.00 msl
Sediment Storage Elevation
838.00 msl
Emergency Spillway Crest
839.00 msl
Top of Berm
840.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
6.53 cfs
25 Yr Peak Flow (Q25)
7.36 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
3,202 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
5,400 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
836.00
0.00
2,483
0
837.00
1.00
2,877
2,678
838.00
2.00
3,296
5,762
839.00
3.00
3,740
9,277
840.00
4.00
4,210
13,250
Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,296 sf
Basin Storage Volume Provided Below Spillway Crest 5,762 cf
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: rD = CLH1 5
Page 22 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST7 - Phase I only
Drainage Area Characteristics
Total drainage area (TDA)'
0.70 ac
Disturbed area (DA)
0.70 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 876.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
876.00 msl
Sediment Storage Elevation
878.00 msl
Emergency Spillway Crest
879.00 msl
Top of Berm
880.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
3.05 cfs
25 Yr Peak Flow (Q25)
3.44 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
1,494 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
2,520 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
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 Size Check
Basin Surface Area Provided at Spillway Crest 1,640 sf
Basin Storage Volume Provided Below Spillway Crest 2,704 cf
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: rD = CLH1 5
Page 23 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST8
Drainage Area Characteristics
Total drainage area (TDA)'
0.80 ac
Disturbed area (DA)
0.80 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 882.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
882.00 msl
Sediment Storage Elevation
884.00 msl
Emergency Spillway Crest
885.00 msl
Top of Berm
886.50 rn l
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
3.48 cfs
25 Yr Peak Flow (Q25)
3.93 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
1,708 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
2,880 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
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 Size Check
Basin Surface Area Provided at Spillway Crest 1,808 sf
Basin Storage Volume Provided Below Spillway Crest 3,010 cf
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: rD = CLH1 5
Page 24 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Sediment Trap: ST9
Drainage Area Characteristics
Total drainage area (TDA)'
1.50 ac
Disturbed area (DA)
1.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 874.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
874.00 msl
Sediment Storage Elevation
876.00 msl
Emergency Spillway Crest
877.00 msl
Top of Berm
878.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
6.53 cfs
25 Yr Peak Flow (Q25)
7.36 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
3,202 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
5,400 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
874.00
0.00
2,483
0
875.00
1.00
2,877
2,678
876.00
2.00
3,296
5,762
877.00
3.00
3,740
9,277
878.00
4.00
4,210
13,250
Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,296 sf
Basin Storage Volume Provided Below Spillway Crest 5,762 cf
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: rD = CLH1 5
Page 25 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST10
Drainage Area Characteristics
Total drainage area (TDA)'
2.25 ac
Disturbed area (DA)
2.25 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 841.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
841.00 msl
Sediment Storage Elevation
843.00 msl
Emergency Spillway Crest
844.00 msl
Top of Berm
845.50 rn l
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
9.80 cfs
25 Yr Peak Flow (Q25)
11.04 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
4,804 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
8,100 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
841.00
0.00
3,827
0
842.00
1.00
4,312
4,067
843.00
2.00
4,821
8,631
844.00
3.00
5,356
13,717
845.00
4.00
5,916
19,351
Basin Size Check
Basin Surface Area Provided at Spillway Crest 4,821 sf
Basin Storage Volume Provided Below Spillway Crest 8,631 cf
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: rD = CLH1 5
Page 26 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST11
Drainage Area Characteristics
Total drainage area (TDA)'
0.60 ac
Disturbed area (DA)
0.60 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 819.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
819.00 msl
Sediment Storage Elevation
821.00 msl
Emergency Spillway Crest
822.00 msl
Top of Berm
823.50 rn l
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
2.61 cfs
25 Yr Peak Flow (Q25)
2.94 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
1,281 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
2,160 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
819.00
0.00
1,081
0
820.00
1.00
1,348
1,212
821.00
2.00
1,640
2,704
822.00
3.00
1,957
4,500
823.00
4.00
2,300
6,626
Basin Size Check
Basin Surface Area Provided at Spillway Crest 1,640 sf
Basin Storage Volume Provided Below Spillway Crest 2,704 cf
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: rD = CLH1 5
Page 27 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST12
Drainage Area Characteristics
Total drainage area (TDA)'
0.80 ac
Disturbed area (DA)
0.80 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 812.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
812.00 msl
Sediment Storage Elevation
814.00 msl
Emergency Spillway Crest
815.00 msl
Top of Berm
816.50 rn l
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
3.48 cfs
25 Yr Peak Flow (Q25)
3.93 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
1,708 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
2,880 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
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 Size Check
Basin Surface Area Provided at Spillway Crest 1,808 sf
Basin Storage Volume Provided Below Spillway Crest 3,010 cf
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: rD = CLH1 5
Page 28 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Sediment Trap: ST13
Drainage Area Characteristics
Total drainage area (TDA)'
1.15 ac
Disturbed area (DA)
1.15 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 840.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
840.00 msl
Sediment Storage Elevation
842.00 msl
Emergency Spillway Crest
843.00 msl
Top of Berm
844.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
5.01 cfs
25 Yr Peak Flow (Q25)
5.64 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
2,455 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
4,140 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
840.00
0.00
1,943
0
841.00
1.00
2,294
2,116
842.00
2.00
2,670
4,596
843.00
3.00
3,071
7,464
844.00
4.00
3,497
10,746
Basin Size Check
Basin Surface Area Provided at Spillway Crest 2,670 sf
Basin Storage Volume Provided Below Spillway Crest 4,596 cf
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: rD = CLH1 5
Page 29 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Sediment Trap: ST14
Drainage Area Characteristics
Total drainage area (TDA)'
0.50 ac
Disturbed area (DA)
0.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 820.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
820.00 msl
Sediment Storage Elevation
822.00 msl
Emergency Spillway Crest
823.00 msl
Top of Berm
824.50 rn l
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
2.18 cfs
25 Yr Peak Flow (Q25)
2.45 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
1,067 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
1,800 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
820.00
0.00
1,081
0
821.00
1.00
1,348
1,212
822.00
2.00
1,640
2,704
823.00
3.00
1,957
4,500
824.00
4.00
2,300
6,626
Basin Size Check
Basin Surface Area Provided at Spillway Crest 1,640 sf
Basin Storage Volume Provided Below Spillway Crest 2,704 cf
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: rD = CLH1 5
Page 30 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Sediment Trap: ST15
Drainage Area Characteristics
Total drainage area (TDA)'
0.25 ac
Disturbed area (DA)
0.25 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 820.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
820.00 msl
Sediment Storage Elevation
822.00 msl
Emergency Spillway Crest
823.00 msl
Top of Berm
824.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
1.09 cfs
25 Yr Peak Flow (Q25)
1.23 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5 534 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5 900 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
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 Size Check
Basin Surface Area Provided at Spillway Crest 621 sf
Basin Storage Volume Provided Below Spillway Crest 902 cf
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: rD = CLH1 5
Page 31 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST16 - Phase 1
Drainage Area Characteristics
Total drainage area (TDA)'
2.80 ac
Disturbed area (DA)
2.10 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 877.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
877.00 msl
Sediment Storage Elevation
879.00 msl
Emergency Spillway Crest
880.00 msl
Top of Berm
881.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
12.20 cfs
25 Yr Peak Flow (Q25)
13.74 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
5,978 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
10,080 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
877.00
0.00
4,724
0
878.00
1.00
5,322
5,020
879.00
2.00
6,071
10,712
880.00
3.00
6,611
17,052
881.00
4.00
7,302
24,005
Basin Size Check
Basin Surface Area Provided at Spillway Crest 6,071 sf
Basin Storage Volume Provided Below Spillway Crest 10,712 cf
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: rD = CLH1 5
Page 32 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL F)l
REVISED: RVW: VH
Sediment Trap: ST17 - Phase 1
Drainage Area Characteristics
Total drainage area (TDA)'
1.60 ac
Disturbed area (DA)
1.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 888.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
888.00 msl
Sediment Storage Elevation
890.00 msl
Emergency Spillway Crest
891.00 msl
Top of Berm
892.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
6.97 cfs
25 Yr Peak Flow (Q25)
7.85 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
3,416 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
5,760 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
888.00
0.00
3,069
0
889.00
1.00
3,505
3,285
890.00
2.00
3,966
7,018
891.00
3.00
4,453
11,225
892.00
4.00
4,964
15,931
Basin Size Check
Basin Surface Area Provided at Spillway Crest 3,966 sf
Basin Storage Volume Provided Below Spillway Crest 7,018 cf
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: rD = CLH1 5
Page 33 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST18 - Phase 1
Drainage Area Characteristics
Total drainage area (TDA)'
0.50 ac
Disturbed area (DA)
0.50 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 892.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
892.00 msl
Sediment Storage Elevation
894.00 msl
Emergency Spillway Crest
895.00 msl
Top of Berm
896.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
2.18 cfs
25 Yr Peak Flow (Q25)
2.45 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
1,067 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
1,800 cf
Basin Size
Elev. msl
Depth (ft)
I Area sf
Cumulative Volume c
892.00
0.00
722
0
893.00
1.00
859
790
894.00
2.00
1,224
1,826
895.00
3.00
1,517
3,194
896.00
4.00
1,839
4,869
Basin Size Check
Basin Surface Area Provided at Spillway Crest 1,224 sf
Basin Storage Volume Provided Below Spillway Crest 1,826 cf
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: rD = CLH1 5
Page 34 of 35

RISER SEDIMENT BASIN CALCULATIONS
Lithium Hydroxide Conversion Plant
HDR PROJECT NO.: 10302238
DATE: 08.27.2021 BY: AKL
REVISED: RVW: VH
Sediment Trap: ST19 - Phase 1
Drainage Area Characteristics
Total drainage area (TDA)'
3.20 ac
Disturbed area (DA)
2.05 ac
Rational Coefficient (C)2
0.60
Time of Concentration IT�)3
5.0 min
10 Yr Storm Rainfall Intensity (i)°
7.3 in/hr
25 Yr Storm Rainfall Intensity (i)°
8.2 in/hr
Design Criteria
Bottom Elevation 856.00 msl
Depth of Storage Volume 2.00 ft
Basin Configuration
Bottom Elevation
856.00 msl
Sediment Storage Elevation
858.00 msl
Emergency Spillway Crest
859.00 msl
Top of Berm
860.50 msl
Spillway Length
Drainage Area
Length of S illwa
1
4
2
6
3
8
4
10
5
12
Required Storage Volume
10 Yr Peak Flow (Q10)
13.94 cfs
25 Yr Peak Flow (Q25)
15.71 cfs
Req'd Min. Surface Area
(435 sf per cfs of Q25)5
6,832 sf
Req'd Min. Storage Volume
(3600 cf per ac of TDA)5
11,520 cf
Basin Size
Elev. msl
Depth ft
Area sf
Cumulative Volume c
856.00
0.00
5,603
0
857.00
1.00
6,313
5,954
858.00
2.00
7,059
12,637
859.00
3.00
7,842
20,084
860.00
4.00
8,662
28,333
Basin Size Check
Basin Surface Area Provided at Spillway Crest 7,059 sf
Basin Storage Volume Provided Below Spillway Crest 12,637 cf
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: rD = CLH1 5
Page 35 of 35

This page intentionally left blank.

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

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

CB v SB-5 (North)
5-N 5P � 5R
24" PIPE SB-5 (North) SB-5 (North)
4A-S
SB-4torth)
4A-N �- 4A-R
24" PIPE SB-4 (North) SB-4 (North)
4B-N N�— 46BP 4B-R
24" PIPE SB-4 (South) SB-4 outh)
4B-S
SB-4 (South)
Subcat Reach on Link
14 --0 1A-R A—D 1A-N
SA-1 (North) SA-1 (North) SA-1 (North) 24" PIPE
1 B-S 1 B-R 1 BBP 1 B-N
SB-1 (South) SB-1 (South) SB-1 (South) 24" PIPE
R2-R 2-P 2-N
SB-2 SB-2 SB-2 24" PIPE
3-R —p 3 p —� 3-N
SB-3 SB-3 8B-3 18" PIPE

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCADO 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 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=0.76"
Tc=0.0 min C=0.91 Runoff=20.49 cfs 0.186 of
Subcatchment1 B-S: SB-1 (South) Runoff Area=1.881 ac 96.28% Impervious Runoff Depth=0.77"
Tc=0.0 min C=0.92 Runoff=13.31 cfs 0.121 of
Subcatchment2-S: SB-2 Runoff Area=3.607 ac 93.76% Impervious Runoff Depth=0.76"
Tc=0.0 min C=0.91 Runoff=25.25 cfs 0.230 of
Subcatchment3-S: SB-3 Runoff Area=1.632 ac 87.25% Impervious Runoff Depth=0.72"
Tc=0.0 min C=0.86 Runoff=10.80 cfs 0.098 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=21.30 cfs 0.194 of
Subcatchment4B-S: SB-4 (South) Runoff Area=2.907 ac 89.85% Impervious Runoff Depth=0.74"
Tc=0.0 min C=0.88 Runoff=19.68 cfs 0.179 of
Subcatchment5S: SB-5 (North) Runoff Area=2.907 ac 89.85% Impervious Runoff Depth=0.74"
Tc=0.0 min C=0.88 Runoff=19.68 cfs 0.179 of
Reach 1A-N: 24" PIPE
Avg. Flow Depth=1.37' Max Vet=8.69 fps Inflow=20.37 cfs
0.178 of
24.0" Round Pipe
n=0.012
L=269.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=19.85 cfs
0.178 of
Reach 1A-R: SA-1 (North)
Avg. Flow Depth=1.11' Max Vet=4.21 fps Inflow=20.49 cfs
0.186 of
n=0.025
L=466.6' S=0.0100 '/' Capacity=84.58 cfs Outflow=20.37 cfs
0.178 of
Reach 1 B-N: 24" PIPE
Avg. Flow Depth=1.05' Max Vet=7.96 fps Inflow=13.31 cfs
0.116 of
24.0" Round Pipe
n=0.012
L=269.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=13.29 cfs
0.116 of
Reach 1 B-R: SB-1 (South)
Avg. Flow Depth=0.93' Max Vet=3.79 fps Inflow=13.31 cfs
0.121 of
n=0.025
L=204.5' S=0.0100 '/' Capacity=84.53 cfs Outflow=13.31 cfs
0.116 of
Reach 2-N: 24" PIPE
Avg. Flow Depth=1.61' Max Vet=8.89 fps Inflow=25.20 cfs
0.219 of
24.0" Round Pipe
n=0.012
L=627.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=24.01 cfs
0.219 of
Reach 2-R: SB-2
Avg. Flow Depth=1.21' Max Vet=4.45 fps Inflow=25.25 cfs
0.230 of
n=0.025
L=407.0' S=0.0100 '/' Capacity=84.64 cfs Outflow=25.20 cfs
0.219 of
Reach 3-N: 18" PIPE
Avg. Flow Depth=1.15' Max Vet=7.31 fps Inflow=10.80 cfs
0.094 of
18.0" Round Pipe
n=0.012
L=627.0' S=0.0100 '/' Capacity=11.38 cfs Outflow=10.53 cfs
0.094 of
Reach 3-R: SB-3
Avg. Flow Depth=0.61' Max Vet=6.22 fps Inflow=10.80 cfs
0.098 of
n=0.012
L=278.4' S=0.0100 '/' Capacity=176.20 cfs Outflow=10.80 cfs
0.094 of
Reach 4A-N: 24" PIPE
Avg. Flow Depth=1.35' Max Vet=8.66 fps Inflow=20.06 cfs
0.185 of
24.0" Round Pipe
n=0.012
L=269.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=19.48 cfs
0.185 of

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 3
Reach 4A-R: SB-4 (North)
Avg. Flow Depth=1.11' Max Vet=4.21 fps Inflow=21.30 cfs
0.194 of
n=0.025
L=627.0' S=0.0100 '/' Capacity=84.64 cfs Outflow=20.06 cfs
0.185 of
Reach 4B-N: 24" PIPE
Avg. Flow Depth=1.33' Max Vet=8.63 fps Inflow=19.33 cfs
0.171 of
24.0" Round Pipe
n=0.012
L=269.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=19.10 cfs
0.171 of
Reach 4B-R: SB-4 (South)
Avg. Flow Depth=1.09' Max Vet=4.18 fps Inflow=19.68 cfs
0.179 of
n=0.025
L=420.0' S=0.0100 '/' Capacity=84.64 cfs Outflow=19.33 cfs
0.171 of
Reach 5-N: 24" PIPE
Avg. Flow Depth=1.34' Max Vet=8.64 fps Inflow=19.50 cfs
0.171 of
24.0" Round Pipe
n=0.012
L=196.0' S=0.0100 '/' Capacity=24.51 cfs Outflow=19.18 cfs
0.171 of
Reach 5R: SB-5 (North) Avg. Flow Depth=1.09' Max Vet=4.19 fps Inflow=19.68 cfs 0.179 of
n=0.025 L=400.0' S=0.0100 '/' Capacity=84.74 cfs Outflow=19.50 cfs 0.171 of
Pond 1A-P: SA-1 (North) Peak Elev=832.99' Inflow=20.37 cfs 0.178 of
24.0" Round Culvert n=0.012 L=269.0' S=0.0100 '/' Outflow=20.37 cfs 0.178 of
Pond 1 B-P: SB-1 (South) Peak Elev=831.95' Inflow=13.31 cfs 0.116 of
24.0" Round Culvert n=0.012 L=269.0' S=0.0100 '/' Outflow=13.31 cfs 0.116 of
Pond 2-P: SB-2 Peak Elev=833.51' Inflow=25.20 cfs 0.219 of
24.0" Round Culvert n=0.012 L=269.0' S=0.0100 '/' Outflow=25.20 cfs 0.219 of
Pond 3-P: SB-3 Peak Elev=833.39' Inflow=10.80 cfs 0.094 of
18.0" Round Culvert n=0.012 L=269.0' S=0.0100 '/' Outflow=10.80 cfs 0.094 of
Pond 4A-P: SB-4 (North) Peak Elev=832.49' Inflow=20.06 cfs 0.185 of
24.0" Round Culvert n=0.012 L=269.0' S=0.0100 '/' Outflow=20.06 cfs 0.185 of
Pond 4B-P: SB-4 (South) Peak Elev=832.36' Inflow=19.33 cfs 0.171 of
24.0" Round Culvert n=0.012 L=269.0' S=0.0100 '/' Outflow=19.33 cfs 0.171 of
Pond 5P: SB-5 (North) Peak Elev=838.10' Inflow=19.50 cfs 0.171 of
24.0" Round Culvert n=0.012 L=196.0' S=0.0100 '/' Outflow=19.50 cfs 0.171 of
Total Runoff Area = 18.936 ac Runoff Volume = 1.187 of Average Runoff Depth = 0.75"
7.76% Pervious = 1.469 ac 92.24% Impervious = 17.467 ac

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCADO 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 4
Summary for Subcatchment 1A-S: SA-1 (North)
Runoff = 20.49 cfs @ 0.00 hrs, Volume= 0.186 af, Depth= 0.76"
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Gaston County, NC 25-Year Duration=6 min, Inten=7.63 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
22 - - -
20.49 cfs
20 - - - - -Gaston ACounty
18 - - - - - - -NG 23- Gar
17 - - - - - - - - - - -
16----------- Duration=6Kmin-,
15 - 1 -
14 - - 1 I Lle n 7.6 a iMft
12 - fi :R-unoff ACea*zm -ac
11 _ i 11rlD fY� =0. 6
LL 10 -
8 JhnoffDepth#G--7i"
7--- - - - -- TED.:Omin-
5 .-9
3 - - - -
2
1
0
0 1 2
Time (hours)
■ Runoff

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCADO 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 5
Summary for Subcatchment 1 B-S: SB-1 (South)
Runoff = 13.31 cfs @ 0.00 hrs, Volume= 0.121 af, Depth= 0.77"
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Gaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Area (ac) C Descriotion
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
— — — — — — — — ■Runoff
13.31 cfs
13 - - - - - Gaston County
12 ————- NC25-Yeas
11
Duration=6 min-,
10 I
9 ———————————lnten=7.63in/hr
8 T Runoff Area=1.881 ac
Runoff Volume=0.12-1-af
LL
6
- - - - -- - I --- Runoff Depth=0.77"
5
4 Tc=0.0 m i n
3 — - — —— C_=OM
2
1
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCADO 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 6
Summary for Subcatchment 2-S: SB-2
Runoff = 25.25 cfs @ 0.00 hrs, Volume= 0.230 af, Depth= 0.76"
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Gaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Area (ac) C Description
3.382 0.95
0.225 0.25
3.607 0.91 Weighted Average
0.225 6.24% Pervious Area
3.382 93.76% Impervious Area
Subcatchment 2-S: SB-2
Hydrograph
■ Runoff
25.25 cfs
24 -Gaswt7o/teL
n +you my
22 IYv 5--Year
20 Duration=6 min,
18
3 16 - - -Runoff Area=3.607 -ac
14
LL 12 Ran-off Vorurve=0.230 of
101 Runoff: Depth=0.76"
T--------- Tc=O.Omin
6-1 -C-
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCADO 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 7
Summary for Subcatchment 3-S: SB-3
Runoff = 10.80 cfs @ 0.00 hrs, Volume= 0.098 af, Depth= 0.72"
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Gaston County, NC 25-Year Duration=6 min, Inten=7.63 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
0
Gaston County
10 NC 25-Year
Duration=6 min,
Inten=7.63 in/hr
Runoff Area=1.632 ac
° 6 Runoff Volume=0.098 of
LL 5
Runoff Depth=0.72"
4
3 Tc=0.0 m i n
C=0.86
1
0 1 2
Time (hours)
❑ Runoff

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCADO 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 8
Summary for Subcatchment 4A-S: SB-4 (North)
Runoff = 21.30 cfs @ 0.00 hrs, Volume= 0.194 af, Depth= 0.76"
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Gaston County, NC 25-Year Duration=6 min, Inten=7.63 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
23 - - - - - - -- - - - - - -- -
21.30 cfs ,� �+
21 Gaston aston -C-ounty
20
19--------- NCi5--Yeai
18 -
17 - - - - --Duir'afian-6 mim
16 ----+-----------------
15----- T - - - - -- fiMen--7.6arnft
14 13 - - - - - 1 - - -Runoff Area=10-7f -ac
12 - - - - - - L - - - - - - - -. „-�-,�- p- - - - -
o UL 11 T Ru-n-off�1{.1111C=V.194�
9------- - -—--- FD- ---7_-
7 — — — — — — L — — — — — — — — — c--O
5 - fi
4 - - - - - - - -
0 1 2
Time (hours)
■ Runoff

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCADO 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 9
Summary for Subcatchment 4B-S: SB-4 (South)
Runoff = 19.68 cfs @ 0.00 hrs, Volume= 0.179 af, Depth= 0.74"
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Gaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Area (ac) C Description
2.612 0.95
0.295 0.25
15
1E
17
1E
1E
14
1
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
7Ga-sfon :CbuntY
- NG 25 vea-r
+ Duration=6 miry,
T tnte --7.6a in/hr
-Runoff Area=2:907 -ac
- -1- Runoff-/okame=0.47-9-af
- — — — —
�
- + - - - nafF Depth=0:7-4"
--------------
--------- Tc -0.0 min
0 1 2
Time (hours)
■ Runoff

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCADO 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 10
Summary for Subcatchment 5S: SB-5 (North)
Runoff = 19.68 cfs @ 0.00 hrs, Volume= 0.179 af, Depth= 0.74"
Runoff by Rational method, Rise/Fall=1.0/1.0 xTc, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Gaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Area (ac) C Description
2.612 0.95
0.295 0.25
15
1E
17
1E
1E
14
1
2.907 0.88 Weighted Average
0.295 10.15% Pervious Area
2.612 89.85% Impervious Area
Subcatchment 5S: SB-5 (North)
Hydrograph
7Ga-sfon :CbuntY
- NG 25 vea-r
+ Duration=6 miry,
T tnte --7.6a in/hr
-Runoff Area=2:907 -ac
- -1- Runoff-/okame=0.47-9-af
- — — — —
�
- + - - - nafF Depth=0:7-4"
--------------
--------- Tc -0.0 min
0 1 2
Time (hours)
■ Runoff

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 11
Summary for Reach 1A-N: 24" PIPE
Inflow Area = 2.926 ac, 94.53% Impervious, Inflow Depth = 0.73" for 25-Year event
Inflow = 20.37 cfs @ 0.13 hrs, Volume= 0.178 of
Outflow = 19.85 cfs @ 0.14 hrs, Volume= 0.178 af, Atten= 3%, Lag= 0.6 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.69 fps, Min. Travel Time= 0.5 min
Avg. Velocity = 1.65 fps, Avg. Travel Time= 2.7 min
Peak Storage= 617 cf @ 0.13 hrs
Average Depth at Peak Storage= 1.37' , Surface Width= 1.86'
Bank -Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 269.0' Slope= 0.0100 '/'
Inlet Invert= 830.18', Outlet Invert= 827.49'
21
1£
1E
17
1E
1E
14
n 1
12
3 11
0
LL 1C
1
0
i
i
i
Reach 1A-N: 24" PIPE
Hydrograph
INLET PIPE TO SB-1
(Basin has double inlet pipes)
-� - - - anflow Area=2426 -ac
-i - - -A g.-F4owQep h=1.3T
-�------ NaxVe1,8.69-fps
— — — — — — — — — — — — — -24.-0n
------------Round Pipe
------------- n-0.Da2
--------------
26�9_G
— S=0. V1 1110—Ir
- - - Lapacify=24.51-cJs
1
Time (hours)
2
■ Inflow
■ outflow

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 12
Summary for Reach 1A-R: SA-1 (North)
Inflow Area = 2.926 ac, 94.53% Impervious, Inflow Depth = 0.76" for 25-Year event
Inflow = 20.49 cfs @ 0.00 hrs, Volume= 0.186 of
Outflow = 20.37 cfs @ 0.13 hrs, Volume= 0.178 af, Atten= 1 %, Lag= 7.5 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 4.21 fps, Min. Travel Time= 1.8 min
Avg. Velocity = 0.82 fps, Avg. Travel Time= 9.4 min
Peak Storage= 2,254 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.11' , Surface Width= 7.68'
Bank -Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 84.58 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= 466.6' Slope= 0.0100 '/'
Inlet Invert= 838.84', Outlet Invert= 834.18'
21
15
1E
17
1E
1E
14
N 1C
12
3 11
LL 1C
1
Reach 1A-R: SA-1 (North)
Hydrograph
49 cfs spi
20.37 Inf1owArea-2-926 ac
— — — — —� — — — — — — — — — — — — — — — -
---- ---Avg.-Row De_h
--------- Meow—'M=4.21Ip
i
-------rrn=0.025
— — — — — — — L=46r6Xr
- - S=0.0100-''
0ap&city=84:58-e#s
0 1 2
Time (hours)
■ Inflow
■ Outflow

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 13
Summary for Reach 1 B-N: 24" PIPE
Inflow Area = 1.881 ac, 96.28% Impervious, Inflow Depth = 0.74" for 25-Year event
Inflow = 13.31 cfs @ 0.11 hrs, Volume= 0.116 of
Outflow = 13.29 cfs @ 0.11 hrs, Volume= 0.116 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= 7.96 fps, Min. Travel Time= 0.6 min
Avg. Velocity = 1.75 fps, Avg. Travel Time= 2.6 min
Peak Storage= 450 cf @ 0.11 hrs
Average Depth at Peak Storage= 1.05' , 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= 269.0' Slope= 0.0100 '/'
Inlet Invert= 830.18', Outlet Invert= 827.49'
Reach 1 B-N: 24" PIPE
Hydrograph
INLET PIPE TO SB-1
(Basin has double inlet pipes)
13.31 cfs
14 13.29cN Inflow Area=1.881 ac
13 _ -Av(J• _FfowDe th=1_.05'
12 — —� — ap
11--�------UaxVel=7.96-fps
10
----------- -2.-0''-
N 9-
_______ Round Pipe
3 8-
- - - - - - - - - - - n="l 2
o 7
LL 6-------------L=269.W
5 S=0.0100 T
4---1-----Gapacity=24.51-cfs
0 1 2
Time (hours)
■ Inflow
■ outflow

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 14
Summary for Reach 1 B-R: S113-1 (South)
Inflow Area = 1.881 ac, 96.28% Impervious, Inflow Depth = 0.77" for 25-Year event
Inflow = 13.31 cfs @ 0.00 hrs, Volume= 0.121 of
Outflow = 13.31 cfs @ 0.11 hrs, Volume= 0.116 af, Atten= 0%, Lag= 6.6 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 3.79 fps, Min. Travel Time= 0.9 min
Avg. Velocity = 0.90 fps, Avg. Travel Time= 3.8 min
Peak Storage= 717 cf @ 0.10 hrs
Average Depth at Peak Storage= 0.93' , Surface Width= 6.56'
Bank -Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 84.53 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= 204.5' Slope= 0.0100 '/'
Inlet Invert= 836.22', Outlet Invert= 834.18'
Reach 1 B-R: SBA (South)
Hydrograph
■ Inflow
0 Outflow
14 Inflow Area=1.881 ac
13
12 - - - Avg. -low Depth=0:93'
11 — — ——Max1Te] =_3-79_fps
10I ----------------n-7 5
_ 9
N L -_�
U $ L
' LL ----- S=0.0t0_0 _
6
5 - - - - - - ICfs -apacity=84.53-c
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 15
Summary for Reach 2-N: 24" PIPE
Inflow Area = 3.607 ac, 93.76% Impervious, Inflow Depth = 0.73" for 25-Year event
Inflow = 25.20 cfs @ 0.12 hrs, Volume= 0.219 of
Outflow = 24.01 cfs @ 0.14 hrs, Volume= 0.219 af, Atten= 5%, Lag= 1.7 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.89 fps, Min. Travel Time= 1.2 min
Avg. Velocity = 1.73 fps, Avg. Travel Time= 6.0 min INLET PIPE TO
Peak Storage= 1,695 cf @ 0.12 hrs SB-2
Average Depth at Peak Storage= 1.61' , Surface Width= 1.59'
Bank -Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 627.0' Slope= 0.0100 '/'
Inlet Invert= 829.74', Outlet Invert= 823.47'
Reach 2-N: 24" PIPE
Hydrograph
22-
❑ Inflow
❑ Outflow
20-
18
y 16.
14
3
0
LL 12
10
8
6
4
2
Inflow Area=3.607 ac
Avg. Flow Depth=1.61'
Max Vet=8.89 fps
24.0"
Round Pipe
n=0.012
L=627.0'
S=0.0100 '/'
Capacity=24.51 cfs
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 16
Summary for Reach 2-R: S113-2
Inflow Area = 3.607 ac, 93.76% Impervious, Inflow Depth = 0.76" for 25-Year event
Inflow = 25.25 cfs @ 0.00 hrs, Volume= 0.230 of
Outflow = 25.20 cfs @ 0.12 hrs, Volume= 0.219 af, Atten= 0%, Lag= 6.9 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 4.45 fps, Min. Travel Time= 1.5 min
Avg. Velocity = 0.82 fps, Avg. Travel Time= 8.3 min
Peak Storage= 2,289 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.21' , Surface Width= 8.28'
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= 407.0' Slope= 0.0100 '/'
Inlet Invert= 837.81', Outlet Invert= 833.74'
Reach 2-R: S113-2
Hydrograph
i
28 2s.25 cfs
26 25.20df In#law-Area=3.607 ac
24 - _ _ _ _ _; _ Avg. Flow Depth=1.21'
22 — — — —
20 —————— Max-5fps
18—————————————— n=0.025
——————————————————————
161L=407.0'
3 14
1VV
L—°° 12 — — —— — — — — — — — C=0.0'P
10 - - - - - -capacity=$4.64-ds
0 1 2
Time (hours)
■ Inflow
❑ Outflow

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 17
Summary for Reach 3-N: 18" PIPE
Inflow Area = 1.632 ac, 87.25% Impervious, Inflow Depth = 0.69" for 25-Year event
Inflow = 10.80 cfs @ 0.11 hrs, Volume= 0.094 of
Outflow = 10.53 cfs @ 0.13 hrs, Volume= 0.094 af, Atten= 2%, Lag= 1.2 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 7.31 fps, Min. Travel Time= 1.4 min
Avg. Velocity = 1.38 fps, Avg. Travel Time= 7.6 min
Peak Storage= 909 cf @ 0.11 hrs
Average Depth at Peak Storage= 1.15' , Surface Width= 1.27'
Bank -Full Depth= 1.50' Flow Area= 1.8 sf, Capacity= 11.38 cfs
18.0" Round Pipe
n= 0.012
Length= 627.0' Slope= 0.0100 '/'
Inlet Invert= 831.03', Outlet Invert= 824.76'
Reach 3-N: 18" PIPE
Hydrograph
I
INLET PIPE TO
SB-3
❑ Inflow
❑ Outflow
11
10.53 cfs
10
9
8
7
y
V
3 6
0
LL 5
4
3
2
1
,
Inflow Area=1.632 ac
Avg. Flow Depth=1.15'
Max Vet=7.31 fps
18.0"
Round Pipe
n=0.012
L=627.0'
S=0.0100 '/'
Capacity=11.38 cfs
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 18
Summary for Reach 3-R: S113-3
Inflow Area = 1.632 ac, 87.25% Impervious, Inflow Depth = 0.72" for 25-Year event
Inflow = 10.80 cfs @ 0.00 hrs, Volume= 0.098 of
Outflow = 10.80 cfs @ 0.11 hrs, Volume= 0.094 af, Atten= 0%, Lag= 6.6 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 6.22 fps, Min. Travel Time= 0.7 min
Avg. Velocity = 1.88 fps, Avg. Travel Time= 2.5 min
Peak Storage= 483 cf @ 0.10 hrs
Average Depth at Peak Storage= 0.61' , Surface Width= 4.67'
Bank -Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 176.20 cfs
1.00' x 2.00' deep channel, n= 0.012
Side Slope Z-value= 3.0 7' Top Width= 13.00'
Length= 278.4' Slope= 0.0100 '/'
Inlet Invert= 837.81', Outlet Invert= 835.03'
Reach 3-R: S113-3
Hydrograph
I
12 10.80 cfs
11 ' 10.80 cfs - - - - - - Inflow Area=a -682 ac
10 Avg. Flow Depth=0.61'
Max Vet=6.22 fps
- - - n=0.D12
L=278.4'
LL 5 - S=0.0100 T
4 Capacity=17-6-.20-cfs-
1
0 1 2
Time (hours)
■ Inflow
■ Outflow

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 19
Summary for Reach 4A-N: 24" PIPE
Inflow Area = 3.076 ac, 92.98% Impervious, Inflow Depth = 0.72" for 25-Year event
Inflow = 20.06 cfs @ 0.14 hrs, Volume= 0.185 of
Outflow = 19.48 cfs @ 0.15 hrs, Volume= 0.185 af, Atten= 3%, Lag= 0.7 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.66 fps, Min. Travel Time= 0.5 min
Avg. Velocity = 1.83 fps, Avg. Travel Time= 2.5 min
Peak Storage= 607 cf @ 0.14 hrs
Average Depth at Peak Storage= 1.35' , Surface Width= 1.87' INLET PIPE TO SB-4
Bank -Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs (Basin has double inlet pipes)
24.0" Round Pipe
n= 0.012
Length= 269.0' Slope= 0.0100 '/'
Inlet Invert= 829.73', Outlet Invert= 827.04'
Reach 4A-N: 24" PIPE
Hydrograph
- - - - - - - - - - - - - -- - - - - - - - - - - - - - -
i- - - - - - - - - - - - - -I- - - - - - - - - - - - - - -
22 20.06 cfs — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —
21 i
----------------- inflow Area=10-76-ao
20 / 19.48 cfs — — — — — — — — — — — — — — — — — — — — — — — — — — — — — —
-----------------A-v �bw-D th=4.3r
19 i pp-��
18 - - - - - - - - - - - - -- - - - - - - - - - - - - - -
17-------------------MaxAtel=8.66Af_ps
15 - - - - - - -� - - - - - - - - - -
14
y13------ - - - - -- Round Pipe
u 12 - -�- - - - -
3 11 n=0-01 2
10 i
LL 9 ------------L=269.0'
8-__-----S_0_01GO-,
5 - - - apac y �4.3'Fc#s
4
0 1 2
Time (hours)
■ Inflow
■ Outflow

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 20
Summary for Reach 4A-R: S113-4 (North)
Inflow Area = 3.076 ac, 92.98% Impervious, Inflow Depth = 0.76" for 25-Year event
Inflow = 21.30 cfs @ 0.00 hrs, Volume= 0.194 of
Outflow = 20.06 cfs @ 0.14 hrs, Volume= 0.185 af, Atten= 6%, Lag= 8.2 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 4.21 fps, Min. Travel Time= 2.5 min
Avg. Velocity = 0.90 fps, Avg. Travel Time= 11.6 min
Peak Storage= 3,000 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.11' , Surface Width= 7.64'
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= 627.0' Slope= 0.0100 '/'
Inlet Invert= 840.00', Outlet Invert= 833.73'
Reach 4A-R: S113-4 (North)
Hydrograph
— — — —I — — — — — — — — — — — — — — — —
■ Inflow
23 21.30 cfs _ — — — — — — — — — — — — — — — — — — —
Outflow
22 - — — — — — - — — — —I — — "low- rea=3.076 ac
21 20.06 cis
20 - - Avg. Flaw Delith=t t'L
— — — — — — — — —
19
1$--------- MaxVt&z1jp
15 �' — - — — — — — —-n=0.02
14
13 — — — — — — — — L=V27.-0,
12 — — — — — — — — — — — — — — — — —A —/�—�— —
LL10-------,�---£-Q.00LOW�'
8 — j-QpG-city—U.s
7
1
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 21
Summary for Reach 4113-N: 24" PIPE
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.71" for 25-Year event
Inflow = 19.33 cfs @ 0.12 hrs, Volume= 0.171 of
Outflow = 19.10 cfs @ 0.13 hrs, Volume= 0.171 af, Atten= 1 %, Lag= 0.7 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 8.63 fps, Min. Travel Time= 0.5 min
Avg. Velocity = 1.60 fps, Avg. Travel Time= 2.8 min
Peak Storage= 597 cf @ 0.12 hrs
Average Depth at Peak Storage= 1.33' , Surface Width= 1.89'
Bank -Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 269.0' Slope= 0.0100 '/'
Inlet Invert= 829.73', Outlet Invert= 827.04'
INLET PIPE TO SB-4
(Basin has double inlet pipes)
Reach 4113-N: 24" PIPE
Hydrograph
/ — — — — — — — — — — — — — — — —I— — — — — — — — — — — — — — — —
21 / 19.33 cfs - - - - - - - - - - - - -N- - `- -e -p - - - �-n- - -
20 19.10 cfs - - - - - - - - — - - - 4nf to Y� TTea=1907 -ac
19 — — — — — — — — — — — — — — — — —
18—————————————---Avg.-RowDepth=1.33'
16———————————————————-MaxyQl_=8.63fps
15
14 — — — — — —— — — — — — — — — — — — — — — — 2.�'r
— — I — — — — — — — — — — — — — — —
13 ———— — — — — — ---------Round Pipe
12 — — — — — — — — — — — —I — — — — — — — — — — — — —
311—— — — — — ————————————————n--"l2
0 10
LL 9 - - -- - -- L-=269�G-
8
5
- - �apaci#y--24.5'� cfa
4
d3
0 1 2
Time (hours)
■ Inflow
■ outflow

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 22
Summary for Reach 4113-R: S113-4 (South)
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.74" for 25-Year event
Inflow = 19.68 cfs @ 0.00 hrs, Volume= 0.179 of
Outflow = 19.33 cfs @ 0.12 hrs, Volume= 0.171 af, Atten= 2%, Lag= 7.1 min
Routing by Stor-Ind+Trans method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Max. Velocity= 4.18 fps, Min. Travel Time= 1.7 min
Avg. Velocity = 0.80 fps, Avg. Travel Time= 8.8 min
Peak Storage= 1,953 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.09' , Surface Width= 7.54'
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= 420.0' Slope= 0.0100 '/'
Inlet Invert= 837.93', Outlet Invert= 833.73'
Reach 4113-R: S113-4 (South)
Hydrograph
- - -1- - - - - - - - - - - - - - - -
-�-rp- - - -7y1- - -
- --jam-� -
■ Inflow
21 19.68 cfs - - - - - - - - - - - I -
Outflow
^_
`-A,
20 19.33 cfs - - - - - - - - - - -I - - N FfID Y-Y -/-41 ea=2M7 ac
19 i - - - - - - - - - - -1- - - - - - - - - -
18 , - - - - - -1 - Avg. -Flaw Depth=I-
17 - - - - - - - - - - - - -
16 - - - - -I - - - - -IWC�x V�Ct�18-fps
15
14 - - - -1 - - - - - - - - - - -n=e.025
- 13 - - -1 - - - - - - - - - - - - - -- -
tn
u 12 L=42n�,
a 10 S=e.e 1 V V 'r
LL
8 j Capacity=&4.64_ds
6
I -
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 23
Summary for Reach 5-N: 24" PIPE
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.71" for 25-Year event
Inflow = 19.50 cfs @ 0.12 hrs, Volume= 0.171 of
Outflow = 19.18 cfs @ 0.12 hrs, Volume= 0.171 af, Atten= 2%, Lag= 0.5 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= 0.4 min
Avg. Velocity = 1.57 fps, Avg. Travel Time= 2.1 min
Peak Storage= 438 cf @ 0.12 hrs INLET PIPE TO
Average Depth at Peak Storage= 1.34' , Surface Width= 1.88' SB-5
Bank -Full Depth= 2.00' Flow Area= 3.1 sf, Capacity= 24.51 cfs
24.0" Round Pipe
n= 0.012
Length= 196.0' Slope= 0.0100 T
Inlet Invert= 835.44', Outlet Invert= 833.48'
Reach 5-N: 24" PIPE
Hydrograph
21 / 19.50 cfs `-., _e -p - - �_n_ - -
20 19.18 cfs - -� - - - inflow
o Y� Area=2.907 ac
19 / — — —
18 -� - --vg._F1owD0ffi_ 1.34!
17
_I_ _ _ _ _
-� — — — — — — —
14 — — — — — .�µ
13 -� - - - - - Round Pipe
12
a;o - -----------n--"12-
LL 9 - - - L=19641
8
7- - - - - - - - S=0-.01 WIP
5 - - - _apac1ty--24.501_ cfs
4
3
0 1 2
Time (hours)
■ Inflow
■ Outflow

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 24
Summary for Reach 5R: S113-5 (North)
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.74" for 25-Year event
Inflow = 19.68 cfs @ 0.00 hrs, Volume= 0.179 of
Outflow = 19.50 cfs @ 0.12 hrs, Volume= 0.171 af, Atten= 1 %, Lag= 7.0 min
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= 1.6 min
Avg. Velocity = 0.79 fps, Avg. Travel Time= 8.4 min
Peak Storage= 1,862 cf @ 0.10 hrs
Average Depth at Peak Storage= 1.09' , Surface Width= 7.54'
Bank -Full Depth= 2.00' Flow Area= 14.0 sf, Capacity= 84.74 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= 0.0100 '/'
Inlet Invert= 839.44', Outlet Invert= 835.43'
Reach 5R: S113-5 (North)
Hydrograph
- - -I- - - - - - - - - - - - - - - -
—�—rp— —
—TM— — —
—--j'�-2T —
■ Inflow
21 19.68 cfs — - — — — — I —
Outflow
7—/1 ^—
`—A,
20 19.50 cfs - — — — — — — H HIOY-Y -11-� Ga-2M7 aV-
19 - - - - - - - - -
18 - - - - -I - Avg. -Flaw Depth=I-
17 i - - - - - - - - - - - -
16 - - - -I - - - - -Max V�Ct�� 9-fps
15
14 - - -I - - - - - - - - - - -n=e.025
- 13 - - - - - - - - - - - - - - - -- - -
tn
u 12 - -I - - L=4N�J,
3 11
2 19 �7=e.OM 'P�
Capacity=&4.74_ds
6 -
' -
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 25
Summary for Pond 1A-P: SA-1 (North)
Inflow Area =
2.926 ac,
94.53% Impervious,
Inflow Depth = 0.73" for 25-Year event
Inflow =
20.37 cfs @
0.13 hrs, Volume=
0.178 of
Outflow =
20.37 cfs @
0.13 hrs, Volume=
0.178 af, Atten= 0%, Lag= 0.0 min
Primary =
20.37 cfs @
0.13 hrs, Volume=
0.178 of
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 832.99' @ 0.13 hrs
Device Routing Invert Outlet Devices
#1 Primary 830.18' 24.0" Round Culvert
L= 269.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 830.18' / 827.49' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
Primary OutFlow Max=19.95 cfs @ 0.13 hrs HW=832.92' (Free Discharge)
L1=Culvert (Inlet Controls 19.95 cfs @ 6.35 fps)
Pond 1A-P: SA-1 (North)
Hydrograph
— — — — — — — — — — — — — — — —I — — — — — — — — — — — ❑ Inflow
22 20.37 its — — — — — — — — — — —I — — — — — — — ❑ Primary
21 20.37 cfs — — — — — — — —I —Inflow Area=2.926 ac
20
18 - - - - - _ Peak Elev=832.99'
17 i
16 24.0"
15
14 Round Culvert
w 13
3 11 n=0.012
0
LL 19
L=269.0'
8
S=0.0100 T
6
5
4
3
2
1
0
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 26
Summary for Pond 1 B-P: SB-1 (South)
Inflow Area = 1.881 ac, 96.28% Impervious, Inflow Depth = 0.74" for 25-Year event
Inflow = 13.31 cfs @ 0.11 hrs, Volume= 0.116 of
Outflow = 13.31 cfs @ 0.11 hrs, Volume= 0.116 af, Atten= 0%, Lag= 0.0 min
Primary = 13.31 cfs @ 0.11 hrs, Volume= 0.116 of
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 831.95' @ 0.11 hrs
Device Routing Invert Outlet Devices
#1 Primary 830.18' 24.0" Round Culvert
L= 269.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 830.18' / 827.49' S= 0.0100'/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
Primary OutFlow Max=13.31 cfs @ 0.11 hrs HW=831.95' (Free Discharge)
L1=Culvert (Inlet Controls 13.31 cfs @ 4.53 fps)
Pond 1 B-P: SBA (South)
Hydrograph
—I ❑ Inflow
13.31 cfs ❑ Primary
14 13.31cfs _Inflow_Area= L.6&1_ac_
13
12 ———————————PeakEIev=8-31M'
11 ————————— ———————————— 24.0"
10
Round Culvert
N
8 _ n=0-012-
0 7 — —, —
LL 6 L=269.0'
5 & -0—Q1D0 '/'_
1
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 27
Summary for Pond 2-P: SB-2
Inflow Area = 3.607 ac, 93.76% Impervious, Inflow Depth = 0.73" for 25-Year event
Inflow = 25.20 cfs @ 0.12 hrs, Volume= 0.219 of
Outflow = 25.20 cfs @ 0.12 hrs, Volume= 0.219 af, Atten= 0%, Lag= 0.0 min
Primary = 25.20 cfs @ 0.12 hrs, Volume= 0.219 of
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 833.51' @ 0.12 hrs
Device Routing Invert Outlet Devices
#1 Primary 829.74' 24.0" Round Culvert
L= 269.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 829.74' / 827.05' S= 0.0100'/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
Primary OutFlow Max=24.90 cfs @ 0.12 hrs HW=833.45' (Free Discharge)
L1=Culvert (Inlet Controls 24.90 cfs @ 7.93 fps)
Pond 2-P: SB-2
Hydrograph
_ _
28 ❑ Inflow
� z5.zocrs — — — — — — — — — — — — — — — — — — — — ❑Primary
26 25.20 cfs - -I -Inflow area=3:60Tac
z2 _ _ _ -P-eak Elev=833.51'
20-
------ - - - - -- 24.0WL
--
------------ Round Culvert
w 16-
3 14- — — — — — — — — — — — — — — — 1� — . 0'��
0
LL 12-———————————————————----- L -269.-Or
---------II----S---0-0-1-001/1
-
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 28
Summary for Pond 3-P: SB-3
Inflow Area =
1.632 ac,
87.25% Impervious,
Inflow Depth = 0.69" for 25-Year event
Inflow =
10.80 cfs @
0.11 hrs, Volume=
0.094 of
Outflow =
10.80 cfs @
0.11 hrs, Volume=
0.094 af, Atten= 0%, Lag= 0.0 min
Primary =
10.80 cfs @
0.11 hrs, Volume=
0.094 of
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 833.39' @ 0.11 hrs
Device Routing Invert Outlet Devices
#1 Primary 831.03' 18.0" Round Culvert
L= 269.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 831.03' / 828.34' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 1.77 sf
Primary OutFlow Max=10.80 cfs @ 0.11 hrs HW=833.39' (Free Discharge)
L1=Culvert (Inlet Controls 10.80 cfs @ 6.11 fps)
Pond 3-P: SB-3
Hydrograph
12 10.80 cfs
11 10.80 cfs Inflow Area=1.632 ac
10 Peak Elev=833.39'
9 18.0"
8
7
Round Culvert
N - — -
w
3 6 n=0.012
LL 5 L=269.0'
4 S=0.0100 T
3
2
1
0
0 1 2
Time (hours)
❑ Inflow
❑ Primary

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 29
Summary for Pond 4A-P: SB-4 (North)
Inflow Area =
3.076 ac,
92.98% Impervious,
Inflow Depth = 0.72" for 25-Year event
Inflow =
20.06 cfs @
0.14 hrs, Volume=
0.185 of
Outflow =
20.06 cfs @
0.14 hrs, Volume=
0.185 af, Atten= 0%, Lag= 0.0 min
Primary =
20.06 cfs @
0.14 hrs, Volume=
0.185 of
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 832.49' @ 0.14 hrs
Device Routing Invert Outlet Devices
#1 Primary 829.73' 24.0" Round Culvert
L= 269.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 829.73' / 827.04' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
Primary OutFlow Max=19.78 cfs @ 0.14 hrs HW=832.44' (Free Discharge)
L1=Culvert (Inlet Controls 19.78 cfs @ 6.30 fps)
22
21 [
20
19
18
17
16
15
14 i
y 13 i
12 i
° 10
LL
9
8
7
6
5
4
3
2
1
0
0
Pond 4A-P: SB-4 (North)
Hydrograph
-
— — — — — — — — — — — — — — — — — — — — — — — - — — — ❑ Inflow
06 ifs — — — — — — — — — — — — — —I — — — — — — — - — — — ❑ Primary
5 Inflow Area=3.076 ac
Peak Elev=832.49'
1
Time (hours)
24.0"
Round Culvert
n=0.012
L=269.0'
S=0.0100 T
2

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 30
Summary for Pond 4B-P: SB-4 (South)
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.71" for 25-Year event
Inflow = 19.33 cfs @ 0.12 hrs, Volume= 0.171 of
Outflow = 19.33 cfs @ 0.12 hrs, Volume= 0.171 af, Atten= 0%, Lag= 0.0 min
Primary = 19.33 cfs @ 0.12 hrs, Volume= 0.171 of
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 832.36' @ 0.12 hrs
Device Routing Invert Outlet Devices
#1 Primary 829.73' 24.0" Round Culvert
L= 269.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 829.73' / 827.04' S= 0.0100'/' Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
Primary OutFlow Max=19.25 cfs @ 0.12 hrs HW=832.35' (Free Discharge)
L1=Culvert (Inlet Controls 19.25 cfs @ 6.13 fps)
Pond 4B-P: SB-4 (South)
Hydrograph
— — — — — —I — — - — — — — — — — — — — ❑ Inflow
21 i 19.33 cfs — — — — — — — — — — — — — — — — — ❑ Primary
20 19.33 cfs - - - Inflow Arrea=Z 9a7 ac-
19 i — — — — — - — — — — — — — — — — — — — — — — — —
18 ————— —————PeakElev=8-32.-3-6'-
16 - - - - - - - - - - - - - - - - - - - - - - - 2, 0 "-
13 — —
31; ----
----------n a.012
o 10
9 --------L-=269.0'-
6 ——O-M-001'- 5
1
0 1 2
Time (hours)

PLI Storm Sewer & Dltch Calculations - 25 Yr Storm
Piedmont Ditches and Storm SeGaston County, NC 25-Year Duration=6 min, Inten=7.63 in/hr
Prepared by HDR, Inc Printed 8/27/2021
HvdroCAD® 10.10-5a s/n 05756 © 2020 HvdroCAD Software Solutions LLC Paae 31
Summary for Pond 5P: SB-5 (North)
Inflow Area = 2.907 ac, 89.85% Impervious, Inflow Depth = 0.71" for 25-Year event
Inflow = 19.50 cfs @ 0.12 hrs, Volume= 0.171 of
Outflow = 19.50 cfs @ 0.12 hrs, Volume= 0.171 af, Atten= 0%, Lag= 0.0 min
Primary = 19.50 cfs @ 0.12 hrs, Volume= 0.171 of
Routing by Stor-Ind method, Time Span= 0.00-2.00 hrs, dt= 0.01 hrs
Peak Elev= 838.10' @ 0.12 hrs
Device Routing Invert Outlet Devices
#1 Primary 835.44' 24.0" Round Culvert
L= 196.0' RCP, square edge headwall, Ke= 0.500
Inlet / Outlet Invert= 835.44' / 833.48' S= 0.0100 T Cc= 0.900
n= 0.012, Flow Area= 3.14 sf
Primary OutFlow Max=19.33 cfs @ 0.12 hrs HW=838.07' (Free Discharge)
L1=Culvert (Inlet Controls 19.33 cfs @ 6.15 fps)
Pond 5P: SB-5 (North)
Hydrograph
�
I
21
19.50 N
20
19.50 cfs
19
i
18
i
17
16
—
15
14
13
— — -
12
11
0 10
LL Q
— — — — — —
i
0 1
Time (hours)
❑ Inflow
❑ Primary
Inflow Area=2.907 ac
Peak Elev=838.10'
24.0"
Round Culvert
n=0.012
L=196.0'
S=0.0100 T
E

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

PLC I Lithium Hydroxide Conversion Plant — Stormwater Calculations
Appendices
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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
Q (cfs)
210.00
180.00
150.00
120.00
30.00
0.00 ' '
0 2 4
Hyd No. 1
DA1- Stream Crossing at Road
Hyd. No. 1 -- 10 Year
Q (cfs)
210.00
180.00
150.00
120.00
.1 1It
30.00
L I I I I I 1 -1%. i
0.00
8 10 12 14 16 18 20 22 24 26
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
Q (cfs)
10.00
M
4.00
2.00
0.00 ' '
0 2 4
Hyd No. 2
6 8
DA2- Crossing at Road
Hyd. No. 2 -- 10 Year
Q (cfs)
10.00
M
4.00
2.00
10 12 14 16 18 20 22 24 26
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
Q (cfs)
24.00
20.00
16.00
12.00
4.00
0.00 ' '
0 2 4
Hyd No. 3
6 8
DA3- Crossing at Road
Hyd. No. 3 -- 10 Year
Q (cfs)
24.00
20.00
16.00
12.00
M
4.00
'FI- ' ' ' ' - ' 0.00
10 12 14 16 18 20 22 24 26
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
Q (cfs)
280.00
240.00
A7111111TIM
160.00
120.00
40.00
0.00 ' '
0 2 4
Hyd No. 4
DA4- Stream Crossing at Railroad
Hyd. No. 4 -- 10 Year
6 8
Q (cfs)
280.00
240.00
200.00
160.00
120.00
ff-TIOT11
40.00
.f I I I I I I I` i 0.00
10 12 14 16 18 20 22 24 26
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
Q (cfs)
320.00
240.00
rO1 1It
160.00
120.00
40.00
DA1- Stream Crossing at Road
Hyd. No. 1 -- 25 Year
Q (cfs)
320.00
280.00
240.00
200.00
160.00
120.00
40.00
0.00 ' ' ' ' ' ' ' ' 1 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
Q (cfs)
15.00
12.00
.M
3.00
0.00 ' '
0 2 4
Hyd No. 2
6 8
DA2- Crossing at Road
Hyd. No. 2 -- 25 Year
Q (cfs)
15.00
12.00
M
3.00
-r ' ' ' ' I i 0.00
10 12 14 16 18 20 22 24 26
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
Q (cfs)
35.00
30.00
25.00
15.00
10.00
5.00
0.00 ' '
0 2 4
Hyd No. 3
DA3- Crossing at Road
Hyd. No. 3 -- 25 Year
Q (cfs)
35.00
30.00
25.00
20.00
15.00
10.00
5.00
- ' 0.00
8 10 12 14 16 18 20 22 24 26
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
420.00
360.00
300.00
240.00
180.00
120.00
60.00
0 00
480.00
420.00
360.00
300.00
240.00
180.00
120.00
60.00
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
Q (cfs)
480.00
420.00
�C.1 11
300.00
240.00
180.00
120.00
Re 11
DA1- Stream Crossing at Road
Hyd. No. 1 -- 100 Year
Q (cfs)
480.00
420.00
360.00
300.00
240.00
180.00
120.00
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
Q (cfs)
21.00
18.00
15.00
12.00
• m
. 11
3.00
0.00 ' '
0 2 4
Hyd No. 2
DA2- Crossing at Road
Hyd. No. 2 -- 100 Year
Q (cfs)
21.00
18.00
15.00
12.00
M
. M
3.00
*-- ' ' ' ' ' - ' 0.00
8 10 12 14 16 18 20 22 24 26
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
Q (cfs)
60.00
50.00
40.00
30.00
20.00
10.00
0.00 ' '
0 2 4
Hyd No. 3
6 8
DA3- Crossing at Road
Hyd. No. 3 -- 100 Year
Q (cfs)
60.00
50.00
40.00
30.00
20.00
10.00
-T ' ' ' 0.00
10 12 14 16 18 20 22 24 26
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
Q (cfs)
700.00
500.00
400.00
100.00
0.00 ' '
0 2 4
Hyd No. 4
DA4- Stream Crossing at Railroad
Hyd. No. 4 -- 100 Year
Q (cfs)
700.00
500.00
400.00
300.00
200.00
100.00
w� I I I I I I I I t i 0.00
8 10 12 14 16 18 20 22 24 26
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
(ft)
Total Discharge (cfs)
Culvert 1 Discharge
(cfs)
Roadway Discharge
(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
893_5
893.0
892_5
0
892.0
w
ID 8g1_5
m
891.0
aD
89V_F
890.0
Total atui i Curve
Crossing: Crossing 1 - D
Total Discharge (cfs)

Table 2 - Culvert Summary Table: Culvert 1
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation
(ft)
Inlet
Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet
Depth (ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(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
8913
892
w 891
-0 89C
889
Perfonnali U1-'e
Divert: C12vert 1
0 0
Inlet Control Elev Outlet Control Elev
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
89ti
892
891
c�
890
889
w
888
887
886
886
0 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
Elev (ft)
Depth (ft)
Velocity (ft/s)
Shear (psf)
Froude Number
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

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

Table 4 - Summary of Culvert Flows at Crossing: Crossing 2 - DA3
Headwater Elevation
(ft)
Total Discharge (cfs)
Culvert 2 Discharge
(cfs)
Roadway Discharge
(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

Rating Curve Plot for Crossing: Crossing 2 - DA3
879
878
o 877
u 876
87r,
874
Total Rathig Curve
Crossing: Crossing 2 - D A3
Total Discharge (cfs)

Table 5 - Culvert Summary Table: Culvert 2
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation
(ft)
Inlet
Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet
Depth (ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(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
1 28.59
873.82
2.529
1 0.0*
1-S2n
1 0.812
1.730
0.964
1 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
3.660
0.676
5-S2n
1.047
2.224
1.301
0.397
15.870
3.292
49.64
49.64
875.17
3.883
1.259
1 5-S2n
1 1.083
2.293
1.351
1 0.408
16.067
3.356
52.65
1 52.65
875.41
4.120
1.462
1 5-S2n
1 1.117
2.358
1.402
1 0.418
16.248
3.417

* 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

Culvert Performance Curve Plot: Culvert 2
879
878
877
r-
0
876
w 875
874
c�
= 878
872
71
Perfonlian U1-'e
Divert: C12vert 2
0 0
Inlet Control Elev Outlet Control Elev
Total Discharge (cfs)

Water Surface Profile Plot for Culvert: Culvert 2
Crossili - Crossing 2 - D 3, Design Discharge - 35.0 efs
Cuh-ert - Culvert 2_ Culvert Discharge - 35.0 cfs
880
878
— 876
874
.a,
u
872
87G
68
-10 0 10 20 80 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

Table 6 - Downstream Channel Rating Curve (Crossing: Crossing 2 - DA3)
Flow (cfs)
Water Surface
Elev (ft)
Depth (ft)
Velocity (ft/s)
Shear (psf)
Froude Number
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

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

Table 7 - Summary of Culvert Flows at Crossing: Crossing 3 - DA1
Headwater Elevation
(ft)
Total Discharge (cfs)
Open Bottom Arch 3
Discharge (cfs)
Roadway Discharge
(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

Rating Curve Plot for Crossing: Crossing 3 - DA1
840
89
838
0
837
G 836
a�
835
CO
= 834
833
82,2
Total Rathig Curve
Crossing: Crossing 3 - DA1
Total Discharge (cfs)

Table 8 - Culvert Summary Table: Open Bottom Arch 3
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation
(ft)
Inlet
Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet
Depth (ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(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
1 235.73
832.88
1 4.906
0.695
1-S2n
1 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
8.405
7-M2c
3.947
3.802
3.802
3.640
12.638
11.180

* 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

Culvert Performance Curve Plot: Open Bottom Arch 3
84C,
-. 838
w 834
82,2
.a,
828
Performance U1 e
Ci- v-ert: Open Bottom Arch 3
0 0
Inlet Control Elev Outlet Control Elev
Total Discharge (cfs)

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
828
326
824
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

Table 9 - Downstream Channel Rating Curve (Crossing: Crossing 3 - DA1)
Flow (cfs)
Water Surface
Elev (ft)
Depth (ft)
Velocity (ft/s)
Shear (psf)
Froude Number
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
Headwater Elevation
(ft)
Total Discharge (cfs)
Open Bottom Arch 4 -
Railroad Discharge
(cfs)
Roadway Discharge
(cfs)
Iterations
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
838
836
834
0
832
a�
w 830
828
a 826
824
822
Total Rathig Curve
Crossing: RAroad Crossing 4 - D A4
Total Discharge (cfs)

Table 11 - Culvert Summary Table: Open Bottom Arch 4 - Railroad
Total
Discharge
(cfs)
Culvert
Discharge
(cfs)
Headwater
Elevation
(ft)
Inlet
Control
Depth (ft)
Outlet
Control
Depth (ft)
Flow
Type
Normal
Depth (ft)
Critical
Depth (ft)
Outlet
Depth (ft)
Tailwater
Depth (ft)
Outlet
Velocity
(ft/s)
Tailwater
Velocity
(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
1 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
u
8
r7
.a,
_ 8C,
Perfonlian U1 e
C&-ert: Open Bottom Arch 4 - Railroad
0 0
Inlet Control Elev Outlet Control Elev
Total Discharge (cfs)

Water Surface Profile Plot for Culvert: Open Bottom Arch 4 - Railroad
Crossing - Raihoad Crossing 4 - DA4. Design Discharge - 439.1 cfs
Cuh-ert - Open Bottom Arch 4 - Railroad Cuh-ert Discharge - 439.1 cfs
840
835
821
C-
O 825
iT3
W 820 d
81
31 C,
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
Elev (ft)
Depth (ft)
Velocity (ft/s)
Shear (psf)
Froude Number
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

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