20230804_ESC_Calculations

Appendix IX - Calculations

Culvert Design Calculation
Mining Modification Permit No. 61-16
The Quartz Corp. USA I I
Mitchell County, North Carolina
S&ME Project No. 213314
COMPUTATIONS BY: Signature Date 07/07/2023
Name C.Ty Brooks, E.I.
Title Staff Professional II
ASSUMPTIONS Signature l-Jd �- ' -� A Date 07/07/2023
AND PROCEDURES Name Cedric H. Ruhl, P.E.
CHECKED BY: Title Senior Engineer- Project Manager
COMPUTATIONS Signature Date 07/07/2023
CHECKED BY: Name Andrew E.Wilmer, E.I.
Title Associate Project Manager
Al
a�
REVIEWED BY: Signature Date 07/07/2023
Name Christopher J.L. Stahl, P.E.
Title Principal Engineer, V.P.
REVIEW NOTES/COMMENTS:
June 9, 2023 1

Culvert Design Calculation s
Mining Modification Permit No. 61-16
The Quartz Corp. USA I I
Mitchell County, North Carolina
S&ME Project No. 213314
OBJECTIVE:
The objective of this calculation report is to design a culvert and energy dissipation system at the new entrance
road for the proposed modification to the Quartz Corp. USA Mining Permit No. 61-16 for the facility in Mitchell
County, North Carolina.
SUMMARY:
The proposed culvert and dissipator design are in accordance with the design criteria presented in the North
Carolina Department of Environmental Quality (NCDEQ) Erosion and Sediment Control Planning and Design
Manual [Ref. 1].
REFERENCES
North Carolina Erosion and Sediment Control Planning and Design Manual; NCDEQ; May 2013.
2 NOAA Atlas 74, Volume 2, Version 3, Bonnin, G.M., Martin, D., Lin, B., Parzybok, T., Yekta, M., & Riley, D.,
April 21, 2017.
3 NRCS Soil Figures, S&ME Inc., June 2023.
4 Compiled HydroCAD Report, Culvert Design, S&ME Inc., June 2023.
Culvert Delineation Figure, S&ME Inc.,July 2023.
DEFINITION OF VARIABLES
A = drainage area (acres) CN = runoff curve number (dimensionless)
Q = flow rate (cfs) P = rainfall depth (in)
S = potential maximum retention after runoff(in) Tc = time of concentration (min)
n = Manning's roughness coefficient (dimensionless)
KNOWN AND ASSUMED VARIABLES:
P2 = 3.93 in, Pao = 5.89 in, P25 = 7.14 in, Pioo= 9.27 in. [Ref. 2]
June 9, 2023 2

Culvert Design Calculation
Mining Modification Permit No. 61-16
The Quartz Corp. USA I I I
Mitchell County, North Carolina
S&ME Project No. 213314
CALCULATIONS
S&ME applied the methodologies and approaches described within Section one (1.0) to calculate the peak run-off
flow capacity for the unnamed tributary to Grassy Creek at the proposed culvert location in accordance with the
proposed entrance road.
The culvert design was evaluated to determine culvert dimensions necessary to pass the calculated peak run-off
flow capacity for the design storm event. In parallel with the culvert design, a riprap energy dissipater was
designed to handle the peak outflows from the culvert. The riprap energy dissipator design included the
determination of the dissipater footprint and necessary riprap size/class.
1.0 Culvert Design
The proposed culvert has a maximum drainage area of 59.8 acres.The proposed culvert will be constructed in an
unnamed tributary to Grassy Creek. The approximate location of where the culvert is to be constructed is
approximately 550 linear feet upstream of the confluence with Grassy Creek.
1.1 Culvert Hydrology
The HydroCADS stormwater modeling software was utilized to calculate the runoff volume for the design storm
in the unnamed tributary at the location of the proposed culvert. S&ME utilized HydroCAD® to apply the SCS
Curve Number Method, specifically the SCS TR-20 event simulation model for the representative drainage area.
The curve number(CN) is an empirical parameter developed by the Natural Resources Conservation Service
(NRCS) from hydrology evaluations, soil type, and surface conditions to predict direct runoff volume from a rainfall
event. NRCS Technical Release 55 (TR-55) Table 2-2 [Ref. 3] was used to select the CN value for each cover type,
or surface condition, for the representative drainage area. Due to the variable Hydrologic Soil Groups (HSG)
referenced in the NRCS Web Soil Survey [Ref. 3], S&ME applied HSG "B" as a constant on-site soil type for the
representative drainage area. HSG "B"was the most prevalent Hydrologic Soil Group for the site.
The time of concentration is the time for flow from the most hydrologically remote point in the contributing
drainage area to leave the watershed. The minimum allowable time of concentration for use in TR-55 is 0.1 hours,
or 6 minutes.A time of concentration was manually computed for the representative watershed.
Since the project site is located in Mitchell County, a non-coastal county, a SCS Type-II rainfall distribution will be
utilized.The duration of these storms will be 24-hours. Rainfall data was obtained from NOAA Precipitation
Frequency Estimates [Ref. 2].
Woods/grass was selected as the land use for the representative area. Table 1, shown below, highlights the CN for
the selected land use [Ref. 1] considering the soil conditions [Ref. 3]. The 100-yr. storm event was utilized to
evaluate site conditions.
June 9, 2023 3

Culvert Design Calculation
Mining Modification Permit No. 61-16
The Quartz Corp. USA I I I
Mitchell County, North Carolina
S&ME Project No. 213314
Table 1: Hydrologic Conditions-Culvert
24-Hour Rainfall
Curve Drainage Time of Peak Flow
Storm Depth
Tributary Area Land Use Description Recurrence {P} Number Area Concentration {Q}
Interval (inches) {CN} {A} {T�} (cfs)
[Ref.1] (ac) (min) [Ref.1]
(years) I [Ref.2]
Woods/Grass I 100-Year 1 9.27 71 59.8 36.9 257.29
The culvert will be designed to pass the peak flow of a 100-yr. storm event (257.29 cfs).
1.2 Culvert Capacity
The culvert design was evaluated, in the sections below, to determine culvert dimensions, the dimensions are
presented in Table 2.
The culvert capacity was evaluated using HydroCAD [Ref. 4].The dimensions of the culvert design were
determined based on the culvert capacity to pass the 100-yr. design storm.
The culverts failure mode of concern is road overtopping.The culvert design was evaluated with a minimum cover
depth of 2-ft., as listed in Table 2.Any culvert with a cover depth less than 2-ft. has an increased risk of failure due
to overtopping.
The Manning's roughness, "n" for the culvert design is shown in Table 2.
Table 2: Culvert Characteristics
Quantity
Diameter Length Manning's n Upstream Downstream Flow Area Longitudinal
Culvert Type {Q} {D} {L} Pipe {n} Invert Invert {A} Slope
[Ref.4] (in) (ft) Material [Ref. {IU} {ID} (ft2) {S}
[Ref.4] [Ref.4] (ft) (ft) (ft/ft)
Circular 2.0 48.0 170.0 RCP 0.012 2610 2598 25.13 0.071
The dimensions of the culvert design (Table 2) indicate that the proposed culvert size has sufficient capacity to
handle the peak flow (Table 3) for the hydraulic conditions found on site.
Table 3: Culvert Design Results
Culvert Road Water
Upstream Elevation Surface Freeboard Outflow
Invert {RE} Elevation {F} {Q}
{IU} (ft) {WSE} (ft) (cfs)
(ft) (ft)
2610.0 2636.0 2616.2 19.8 248.23
2.0 Riprap Energy Dissipater Design
In parallel with the culvert design a riprap energy dissipater was designed to prevent the outflow from the culvert
from scouring the existing stream channel bed. The NCDEQ Riprap Energy Dissipater Nomograph Figure 8.06a
June 9, 2023 4

Culvert Design Calculation
Mining Modification Permit No. 61-16
The Quartz Corp. USA I I I
Mitchell County, North Carolina
S&ME Project No. 213314
[Ref 1.] was utilized to determine the d50 Riprap size and the apron footprint. The figure is for the "Design of
outlet protection from a round pipe flowing full, minimum tailwater condition (Tw < 0.5 diameter)." Utilizing the
culvert discharge for the design storm event the parameters for the riprap energy dissipater were determined and
are shown in Table 4.
Table 4: Riprap Energy Dissipater Design Parameters
Culvert Culvert Minimum Minimum
Diameter Capacity Riprap d50 Apron Apron
{DI M (D) Length Width
(in) (cfs) (in) {LaI {LaI
[Ref.5] [Ref.5] [Ref.6] (ft) (ft)
[Ref.6] [Ref.6]
48 124.12 10.0 28.0 32.0
CONCLUSIONS
A culvert design over the unnamed tributary to Grassy Creek was evaluated to be used within the design for the
proposed modification to the Quartz Corp. USA Mining Permit No. 61-16. The proposed culvert and dissipator
design are in accordance with the design criteria presented in the North Carolina Department of Environmental
Quality (NCDEQ) Erosion and Sediment Control Planning and Design Manual [Ref. 1].
June 9, 2023 5

References

Reference 1
North Carolina Erosion and Sediment Control Planning and Design Manual;NCDEQ;May2073.

Appendices
Table 8.03e Runoff curve numbers of urban areas'
Curve number for
---------------------------------------Cover Description------------------------- ---------hydrologic soil group--------
Covertype and hydrologic condition Average percent A B C D
impervious area
Fully developed urban areas (vegetation established)
Open space (lawns, parks, golf courses, cemeteries, etc.)3:
Poor condition (grass cover< 50%) ............................. 68 79 86 89
Fair condition (grass cover 50% to 75%) ..................... 49 69 79 84
Good condition (grass cover> 75%) ............................ 39 61 74 80
Impervious areas:
Paved parking lots, roofs, driveways, etc.
(excludingright-of-way) 98 98 98 98
Streets and roads:
Paved; curbs and storm sewers (excluding 98 98 98 98
right-of-way) ..................................................................
Paved; open ditches (including right-of-way) ................ 83 89 92 93
Gravel (including right-of-way) ...................................... 76 85 89 91
Dirt(including right-of-way) ........................................... 72 82 87 89
Urban districts:
Commercial and business ................................................. 85 89 92 94 95
Industrial ........................................................................... 72 81 88 91 93
Residential districts by average lot size:
1/8 acre or less (town houses) ......................................... 65 77 85 90 92
1/4 acre ............................................................................ 38 61 75 83 87
1/3 acre ............................................................................. 30 57 72 81 86
1/2 acre ............................................................................. 25 54 70 80 85
1 acre ............................................................................... 20 51 68 79 84
2 acres .............................................................................. 12 46 65 77 82
Developing urban areas
Newly graded areas 77 86 91 94
(pervious areas only, no vegetation)a ..............................
Idle lands (CN's are determined using cover types
similar to those in table 2-2c).
1.Average runoff condition,and la=0.2S.
2.The average percent impervious area shown was used to develop the composite CN's.Other assumptions are as follows:impervious
areas are directly connected to the drainage system,impervious areas have a CN of 98,and pervious areas are considered equivalent
to open space in good hydrologic condition.CN's for other combinations of conditions may be computed using Figure 8.03c or 8.03d.
3.CN's shown are equivalent to those of pasture.Composite CN's may be computed for other combinations of open space cover type.
4.Composite CN's to use for the design of temporary measures during grading and construction should be computed using Figure 8.03c
or 8.03d based on the degree of development(impervious area percentage)and the CN's for the newly graded pervious areas.
Rev.6/06 8.03.17

Appendices
30
Outlet W Do + La +I.
pipe
diameter (Do)
La — 80 I ).
�,� T ilwater < 0.5Da
o _ _
1 �
v `4
a 4
i - �,oA
3 } d� •►
20 , �5 3
2 I
10TH
a
- m
......... Ma IlTf�1�1111111i it Mi `j _N
2 U)
r
a a
a
°C
20
1 k v
I, I v c 10 d ► I.
Iv 6 j . .
I j I fj I6
;l�
3 5 10 20 50 100 2001 500 1000
Discharge(0/sec)
Curves may not be extrapolated.
Figure 8.06a Design of outlet protection protection from a round pipe flowing full,minimum tailwater condition(TW<0.5 diameter).
Rev.12/93 8.06.3

Reference 2
NOAA Atlas 74, Volume 2, Version 3, Bonnin, G.M., Martin, D., Lin, B., Parzybok, T., Yekta, M., & Riley, D., April 21,
2017.

2/2/23,3:44 PM Precipitation Frequency Data Server
NOAA Atlas 14,Volume 2,Version 3
' Location name: Spruce Pine,North Carolina,USA* � ,1"
Latitude:35.902°,Longitude: -82.064°
Elevation:2595.26 ft**
source:ESRI Maps
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)1
Average recurrence interval(years)
Duration� 2 � 1 1000
5-min 0.372 0.443 0.526 0.591 0.675 0.740 0.805 0.872 0.960 1.03
(0.339-0.410) (0.405-0.488) (0.478-0.579) (0.536-0.648) (0.608-0.743) (0.662-0.815) (0.716-0.889) (0.767-0.967) (0.833-1.07) (0.883-1.16)
10-min 0.595 0.709 0.843 0.944 1.08 1.18 1.28 1.38 1.52 1.62
(0.541-0.655) (0.648-0.780) (0.766-0.927) (0.856-1.04) (0.970-1.18) 1 (1.06-1.30) 1 (1.14-1.41) 11 (1.22-1.53) (1.32-1.69) (1.39-1.83)
15-min 0.744 0.891 1.07 1.20 1.36 1.49 1.62 1.75 1.91 2.04
(0.677-0.818) (0.814-0.981) (0.969-1.17) 1 (1.08-1.31) 1 (1.23-1.50) 11 (1.34-1.64) 11 (1.44-1.79) 1 (1.54-1.93) (1.66-2.13) (1.75-2.29)
30-min 1.02 1.23 1.52 1.73 2.62 2.25 2.48 2.72 3.04 3.30
(0.928-1.12) (1.13-1.36) (1.38-1.67) (1.57-1.90) (1.82-2.22) (2.01-2.48) (2.20-2.74) 11 (2.39-3.01) (2.64-3.39) (2.83-3.71)
60-min 1.27 1.55 1.94 2.25 2.69 3.05 3.41 3.81 4.36 4.82
(1.16-1.40) (1.41-1.70) (1.77-2.14) (2.04-2.48) (2.42-2.96) (2.73-3.35) (3.03-3.77) (3.35-4.22) (3.79-4.87) (4.13-5.41)
2-hr 1.46 1.79 2.28 2.67 3.25 3.73 4.24 4.80 5.62 6.31
(1.33-1.61) (1.63-1.97) (2.07-2.50) (2.42-2.94) (2.92-3.57) (3.32-4.10) (3.75-4.68) (4.21-5.32) (4.84-6.27) (5.37-7.09)
E
-hr 1.59 1.93 2.44 2.87 3.50 4.04 4.63 5.29 6.26 7.10
(1.44-1.75) (1.75-2.13) (2.22-2.69) (2.59-3.16) (3.14-3.86) (3.59-4.47) (4.07-5.13) 11 (4.60-5.88) (5.34-7.01) (5.98-8.01)
:6.hr 2.03 2.45 3.04 3.55 4.31 4.96 5.69 6.49 7.71 ) 8.77 )
(1.86-2.22) (2.25-2.68) (2.78-3.33) (3.23-3.88) (3.89-4.72) (4.45-5.44) (5.04-6.26) (5.69-7.18) (6.62-8.60 (7.41-9.84
12-hr 2.61 3.15 3.90 4.51 5.37 6.09 6.85 7.68 8.88 9.90
(2.41-2.83) 1 (2.91-3.43) (3.59-4.24) (4.14-4.90) (4.91-5.86) (5.52-6.66) (6.17-7.52) (6.85-8.47) (7.82-9.87) (8.62-11.1)
24-hr 3.24 5.0 3.93 1 5.89 7.14 8.17 9.27 10.5 12.2 13.6
(2.93-3.66) 1 (3.55-4.45) 1 (4.52-5.68) (5.29-6.68) (6.37-8.12) (7.23-9.32) (8.13-10.6) (9.08-12.0) (10.4-14.1) (11.4-15.9)
2-day 3.90 4.71F 5.96 6.98 7 8.43 F 9.63 10.9 12.3 14.3 16.0
(3.54-4.32) 1 (5.41-6.63) (6.30-7.77) 1 (7.54-9.40) 1 (8.55-10.8) (9.60-12.3) (10.7-14.0) 1(12.2-16.4) (13.5-18.5)
3-day 4.17 5.03 F 6.31 F 7.35 F 8.82 F 10.0 F 11.3 F 12.7 i 14.7 iF 16.3
(3.79-4.62) 1 (4.58-5.58) 1 (5.73-7.02) 1 (6.65-8.18) (7.91-9.84) 1 (8.93-11.2) 1 (9.98-12.7) 1 (11.1(11.1-14.4) 1(12.6-16.7) 1(13.8-18.8)
4-day 4.44 5.34 F 6.67 F 7.73 9.22 10.4 11.7 13.1 15.0 16.6
(4.05-4.92) (4.87-5.93) (6.06-7.41) (7.00-8.59) (8.29-10.3) 1 (9.30-11.7) 1 (10.4-13.2) 1 (11.4-14.8) (12.9-17.1) (14.2-19.2)
7-day 4 5.16 6.19 7.59 8.70 10.2 11.5 12.8 14.1 16.0 17.6
( .71-5.78) (5.64-6.94) (6.90-8.53) (7.89-9.80) (9.23-11.6) 1 (10.3-13.0) (11.3-14.6) 11 (12.4-16.2) (13.9-18.5) (15.0-20.5)
10-day 5.91 7.65 8.50 9.63 11.2 12.4 13.6 14.8 16.5 18.0
(5.42-6.57) (6.46-7.85) (7.77-9.48) (8.79-10.8) (10.1-12.5) (11.1-13.9) (12.1-15.3) (13.2-16.8) (14.5-18.9) (15.6-20.8)
20-day 7.90 9.35 11.1 12.5 14.3 15.8 17.3 18.8 20.9 22.6
(7.34-8.62) (8.67-10.2) (10.3-12.1) (11.5-13.7) (13.2-15.8) (14.4-17.4) (15.7-19.2) 1 (16.9-20.9) (18.6-23.4) (19.9-25.4)
30-day 9.76 11.5 13.4 14.9 16.8 18.3 19.8 21.3 23.3 -1 24.8
(9.08-10.5) 1 (10.7-12.4) 1 (12.5-14.5) 11 (13.8-16.2) 1 (15.5-18.3) 1 (16.8-20.0) 1 (18.1-21.7) 11 (19.3-23.4) (20.9-25.7) (22.1-27.5)
45-day 12.3 14.4 16.5 F 18.1 F 20.2 21.8 23.4 25.0 27.1 28.6
(11.5-13.1) 1 (13.5-15.4) 1 (15.5-17.6) 1 (16.9-19.3) 1 (18.9-21.6) 1 (20.3-23.4) 1 (21.7-25.2 1 (23.0-27.0) (24.7-29.4) (26.0-31.3)
60-day 14.6 17.1 19.4 F 21.2 23.5 25.2 26.9 28.5 30.6 32.1
(13.8-15.6) (16.1-18.2) (18.3-20.7) (19.9-22.6) (22.0-25.1) (23.6-27.0) (25.0-28.8) (26.4-30.7) (28.2-33.1) 1 (29.5-34.9)
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 NOAAAtlas 14 document for more information.
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PF graphical
https:Hhdsc.nws.noaa.gov/hdsc/pfds/pfds_Printpage.html?lat=35.9020&Ion=-82.0640&data=depth&units=english&series=pds 1/4

2/2/23,3:44 PM Precipitation Frequency Data Server
PDS-based depth-duration-frequency (DDF) curves
Latitude: 35.90201, Longitude: -82-1315401
35
Average recurrence
30 t ............ ----- ----t --- Ynlenral
{yeara�
25 --- -- -- . --- — 1
C 2
20 --- -- -- - --- — 5
0
15 --- -- --- -- -- -- — 25
M — 60
100
— 200
500
5 -- -.:. ..............
— 1000
0 -
r- L L L L M
o o o A A Lb
A r-� a o o U�o
,I H m [aH ry rn v Ln
Duration
35
30 -- - ------- ----- -------- ---- ----- ----- --------
25 .- . ------- ----- --------- ........ - Duration
t
CL
� 20 .- ----------=- ----=------ ---- - ............. — n — 2�ay
5�nY
e — 76-mYn — 3-day
" 15 - -------- --- - - ------ - . - — —
75�-mn 4-day
30-min 7-day
--- — 60-mYn — 10-eay
10 ..... ........ ...... ...... — 2-nr — 20 rJay
3-hr — S�d2Yy
5 ----.. ........... — 6-hr — 45-tlay
------- — 12-hr — bo-eay
0 1 — 24-hr
1 2 5 10 25 50 100 200 500 1000
Average recurrence interval (years)
NDAAAtlas 14,Volume 2,Version 3 Created(GMT):Thu Feb 2 20-43.37 2023
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Maps & aerials
Small scale terrain
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2/2/23,3:44 PM Precipitation Frequency Data Server
'Spruce Pine
-F
Grassy Creek
3 km
2mi
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https:Hhdsc.nws.noaa.gov/hdsc/pfds/pfds—Printpage.html?lat=35.9020&lon=-82.0640&data=depth&units=english&series=pds 3/4

2/2/23,3:44 PM Precipitation Frequency Data Server
Johnson
Asheville
Greensl
GreenvilLe
100km
60mi
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US Department of Commerce
National Oceanic and Atmospheric Administration
National Weather Service
National Water Center
1325 East West Highway
Silver Spring,MD 20910
Questions?: HDSC.Questionsflnoaa.gov
Disclaimer
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Reference 3
NRCS Soil Figures, S&ME, Inc., June 2023.

3 Hydrologic Soil Group—Mitchell County,North Carolina
a (Bottomless Culvert DA)
402700 402BOO 402900 403000 403100 403200 403300 403400 403500 403600 Q
35o 54'13"N y� 35°54'13"N
HffD—
�.
WgD
o D
o D
r
M41chone,Rd
44.
�Y, t
II I
35o 53 51"N - 35'53'51"N
.1. 402800 412 W 403000 403100 403200 40. 403400 403500 403600
3 3
lV
v Map Scale:1:4,930 if printed on A landscape(11"x 8.5")sheet. e
Meters N
0 50 100 20D 300
Feet
0 200 400 8D0 1200
Map projection:Web Mer�tor Comer coordinates:WGS84 Edge tics:UTM Zone 17N WGS84
USDA Natural Resources Web Soil Survey 6/5/2023
Conservation Service National Cooperative Soil Survey Page 1 of 4

Hydrologic Soil Group—Mitchell County,North Carolina
(Bottomless Culvert DA)
MAP LEGEND MAP INFORMATION
Area of Interest(AOI) p C The soil surveys that comprise your AOI were mapped at
Area of Interest(A01) 0 C/D 1:12,000.
Soils D Warning:Soil Map may not be valid at this scale.
Soil Rating Polygons �
A p Not rated or not available Enlargement of maps beyond the scale of mapping can cause
misunderstanding of the detail of mapping and accuracy of soil
0 A/D Water Features line placement.The maps do not show the small areas of
Streams and Canals contrasting soils that could have been shown at a more detailed
0 B scale.
Transportation
0 B/D
Rails Please rely on the bar scale on each map sheet for map
0 C measurements.
Interstate Highways
0 C/D US Routes Source of Map: Natural Resources Conservation Service
Web Soil Survey URL:
0 D Major Roads Coordinate System: Web Mercator(EPSG:3857)
Not rated or not available Local Roads
Maps from the Web Soil Survey are based on the Web Mercator
Soil Rating Lines Background projection,which preserves direction and shape but distorts
q distance and area.A projection that preserves area,such as the
® Aerial Photography Albers equal-area conic projection,should be used if more
• A/D accurate calculations of distance or area are required.
+'* B This product is generated from the USDA-NRCS certified data as
B/D of the version date(s)listed below.
x C Soil Survey Area: Mitchell County, North Carolina
Survey Area Data: Version 17,Sep 12,2022
P1 0 C/D
Soil map units are labeled(as space allows)for map scales
* r D 1:50,000 or larger.
r Not rated or not available Date(s)aerial images were photographed: Apr 1,2022—May 9,
Soil Rating Points 2022
p A The orthophoto or other base map on which the soil lines were
compiled and digitized probably differs from the background
p A/D imagery displayed on these maps.As a result,some minor
B shifting of map unit boundaries may be evident.
B/D
UU� Natural Resources Web Soil Survey 6/5/2023
� Conservation Service National Cooperative Soil Survey Page 2 of 4

Hydrologic Soil Group—Mitchell County,North Carolina Bottomless Culvert DA
Hydrologic Soil Group
Map unit symbol Map unit name Rating Acres in AOI Percent of AOI
CaE Cashiers sandy loam, A 2.2 3.6%
30 to 50 percent
slopes,stony
HnD Huntdale silty clay loam, B 0.2 0.3%
15 to 30 percent
slopes,stony
SdD Saunook-Thunder B 7.7 12.9%
complex, 15 to 30
percent slopes,stony
Ud Udorthents,loamy C 13.1 21.9%
WgC Watauga sandy loam,8 B 20.2 33.7%
to 15 percent slopes,
stony
WgD Watauga sandy loam, B 16.5 27.6%
15 to 30 percent
slopes,stony
Totals for Area of Interest 59.9 100.0%
USDA Natural Resources Web Soil Survey 6/5/2023
Conservation Service National Cooperative Soil Survey Page 3 of 4

Hydrologic Soil Group—Mitchell County,North Carolina Bottomless Culvert DA
Description
Hydrologic soil groups are based on estimates of runoff potential. Soils are
assigned to one of four groups according to the rate of water infiltration when the
soils are not protected by vegetation, are thoroughly wet, and receive
precipitation from long-duration storms.
The soils in the United States are assigned to four groups (A, B, C, and D) and
three dual classes (A/D, B/D, and C/D). The groups are defined as follows:
Group A. Soils having a high infiltration rate (low runoff potential)when
thoroughly wet. These consist mainly of deep, well drained to excessively
drained sands or gravelly sands. These soils have a high rate of water
transmission.
Group B. Soils having a moderate infiltration rate when thoroughly wet. These
consist chiefly of moderately deep or deep, moderately well drained or well
drained soils that have moderately fine texture to moderately coarse texture.
These soils have a moderate rate of water transmission.
Group C. Soils having a slow infiltration rate when thoroughly wet. These consist
chiefly of soils having a layer that impedes the downward movement of water or
soils of moderately fine texture or fine texture. These soils have a slow rate of
water transmission.
Group D. Soils having a very slow infiltration rate (high runoff potential)when
thoroughly wet. These consist chiefly of clays that have a high shrink-swell
potential, soils that have a high water table, soils that have a claypan or clay
layer at or near the surface, and soils that are shallow over nearly impervious
material. These soils have a very slow rate of water transmission.
If a soil is assigned to a dual hydrologic group (A/D, B/D, or C/D), the first letter is
for drained areas and the second is for undrained areas. Only the soils that in
their natural condition are in group D are assigned to dual classes.
Rating Options
Aggregation Method: Dominant Condition
Component Percent Cutoff. None Specified
Tie-break Rule: Higher
usDA Natural Resources Web Soil Survey 6/5/2023
Conservation Service National Cooperative Soil Survey Page 4 of 4

Reference 4
Compiled HydroCAD Report, Culvert Design, S&ME Inc., June 2023.

5S
Conv . Culv . Entrance
1�7
Z4
Cult'
Subcat Reach on Link Routing Diagram for 213314_Culvert HydroCAD
Prepared by S&ME, Inc., Printed 6/29/2023
HydroCAD®10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC

213 314_C u I ve rt_H yd ro CAD
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCADO 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Paces
Project Notes
Defined 10 rainfall events from 213314_Quartz Corp PF_Depth OF

213 314_C u I ve rt_H yd ro CAD
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCADO 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Paces
Area Listing (selected nodes)
Area CN Description
(acres) (subcatchment-numbers)
19.034 70 1/2 acre lots, 25% imp, HSG B (5S)
8.778 98 Paved parking, HSG B (5S)
32.031 65 Woods/grass comb., Fair, HSG B (5S)
59.843 71 TOTAL AREA

213 314_C u I ve rt_H yd ro CAD
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCADO 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Page 4
Soil Listing (selected nodes)
Area Soil Subcatchment
(acres) Group Numbers
0.000 HSG A
59.843 HSG B 5S
0.000 HSG C
0.000 HSG D
0.000 Other
59.843 TOTAL AREA

213 314_C u I ve rt_HydroCAD
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCAD® 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Page 5
Ground Covers (selected nodes)
HSG-A HSG-B HSG-C HSG-D Other Total Ground Subcatchment
(acres) (acres) (acres) (acres) (acres) (acres) Cover Numbers
0.000 19.034 0.000 0.000 0.000 19.034 1/2 acre lots, 25% imp 5S
0.000 8.778 0.000 0.000 0.000 8.778 Paved parking 5S
0.000 32.031 0.000 0.000 0.000 32.031 Woods/grass comb., Fair 5S
0.000 59.843 0.000 0.000 0.000 59.843 TOTAL AREA

213 314_C u I ve rt_H yd ro CAD
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCADO 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Paces
Pipe Listing (selected nodes)
Line# Node In-Invert Out-Invert Length Slope n Diam/Width Height Inside-Fill
Number (feet) (feet) (feet) (ft/ft) (inches) (inches) (inches)
1 1 P 2,610.00 2,598.00 170.0 0.0706 0.011 48.0 0.0 0.0

213314_Culvert_HydroCAD Type 11 24-hr 100-yr Rainfall=9.27"
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCADO 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Page 7
Time span=5.00-20.00 hrs, dt=0.05 hrs, 301 points
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN
Reach routing by Stor-Ind+Trans method - Pond routing by Stor-Ind method
Subcatchment 5S: Conv. Culy. Entrance Runoff Area=2,606,748 sf 22.62% Impervious Runoff Depth>5.24"
Flow Length=3,140' Tc=36.9 min CN=71 Runoff=257.29 cfs 26.138 of
Pond 1P: Culy Peak Elev=2,616.22' Storage=27,877 cf Inflow=257.29 cfs 26.138 of
48.0" Round Culvert x 2.00 n=0.011 L=170.0' S=0.0706 '/' Outflow=248.63 cfs 26.119 of
Total Runoff Area = 59.843 ac Runoff Volume=26.138 of Average Runoff Depth = 5.24"
77.38% Pervious =46.306 ac 22.62% Impervious = 13.536 ac

213314_Culvert_HydroCAD Type 11 24-hr 100-yr Rainfall=9.27"
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCADO 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Page 8
Summary for Subcatchment 5S: Conv. Culy. Entrance
Runoff = 257.29 cfs @ 12.33 hrs, Volume= 26.138 af, Depth> 5.24"
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Type II 24-hr 100-yr Rainfall=9.27"
Area (sf) CN Description
1,395,267 65 Woods/grass comb., Fair, HSG B
382,358 98 Paved parking, HSG B
829,123 70 1/2 acre lots, 25% imp, HSG B
2,606,748 71 Weighted Average
2,017,109 77.38% Pervious Area
589,639 22.62% Impervious Area
Tc Length Slope Velocity Capacity Description
(min) (feet) (ft/ft) (ft/sec) (cfs)
13.1 100 0.2297 0.13 Sheet Flow,
Woods: Dense underbrush n= 0.800 P2= 3.70"
14.0 1,001 0.2276 1.19 Shallow Concentrated Flow,
Forest w/Heavy Litter Kv= 2.5 fps
8.8 1,077 0.0855 2.05 Shallow Concentrated Flow,
Short Grass Pasture Kv= 7.0 fps
1.0 962 0.0891 16.10 563.63 Channel Flow,
Area= 35.0 sf Perim= 20.0' r= 1.75'
n= 0.040 Mountain streams
36.9 3,140 Total

213314_Culvert_HydroCAD Type 1124-hr 100-yr Rainfall=9.27"
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCAD® 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Page 9
Subcatchment 5S: Conv. Culv. Entrance
Hydrograph
280 ❑Runoff
ze .z9 ors
2so -1 - -1- - � Type ail-24+.hr-
240 1
11
220 - 1 - - - - - 1 - - - 1 1�Yr Oai 'nfaH'1=9.#
200 urho Area 606,7 1 s
180 1Rur, 1 olume�26,1381 of
- - - - - - - - - - - - - - - - - - - - - - - - -
160 T _ _RO-o# Do{-thy5.24"
0140 — 4 - - - - - - - � _ Flow Lengthx3,140'
LL 120 1 1 1 1
- - - - - - - - - - - -Te=3§.Jtyj-jn-
100
80 — 1 — —I — — I— — L — J — —I — I— I — —I— — L 1 1 — — — —
60 1 1 1 1 1 1 1 1 1 1
— — - — — — — — — - — — 1 1— — i 1 — ,— -
40
20
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

213314_Culvert_HydroCAD Type 11 24-hr 100-yr Rainfall=9.27"
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCADO 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Page 10
Summary for Pond 1 P: Culy
Inflow Area = 59.843 ac, 22.62% Impervious, Inflow Depth > 5.24" for 100-yr event
Inflow = 257.29 cfs @ 12.33 hrs, Volume= 26.138 of
Outflow = 248.63 cfs @ 12.39 hrs, Volume= 26.119 af, Atten= 3%, Lag= 4.0 min
Primary = 248.63 cfs @ 12.39 hrs, Volume= 26.119 of
Routing by Stor-Ind method, Time Span= 5.00-20.00 hrs, dt= 0.05 hrs
Peak Elev= 2,616.22' @ 12.39 hrs Surf.Area= 9,003 sf Storage= 27,877 cf
Plug-Flow detention time= 1.4 min calculated for 26.119 of(100% of inflow)
Center-of-Mass det. time= 1.1 min ( 800.2 - 799.1 )
Volume Invert Avail.Storage Storage Description
#1 2,610.00' 110,509 cf Custom Stage Data (Prismatic) Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic-feet) (cubic-feet)
2,610.00 998 0 0
2,612.00 2,711 3,709 3,709
2,614.00 5,446 8,157 11,866
2,616.00 8,616 14,062 25,928
2,618.00 12,113 20,729 46,657
2,620.00 15,889 28,002 74,659
2,622.00 19,961 35,850 110,509
Device Routing Invert Outlet Devices
#1 Primary 2,610.00' 48.0" Round Culvert X 2.00
L= 170.0' RCP, square edge headwall, Ke= 0.500
Inlet/ Outlet Invert= 2,610.00' /2,598.00' S= 0.0706 '/' Cc= 0.900
n= 0.011 Concrete pipe, straight & clean, Flow Area= 12.57 sf
Primary OutFlow Max=248.23 cfs @ 12.39 hrs HW=2,616.21' (Free Discharge)
L1=Culvert (Inlet Controls 248.23 cfs @ 9.88 fps)

213314_Culvert_HydroCAD Type 1124-hr 100-yr Rainfall=9.27"
Prepared by S&ME, Inc. Printed 6/29/2023
HydroCAD® 10.00-26 s/n 06707 ©2020 HydroCAD Software Solutions LLC Page 11
Pond 1 P: Culv
Hydrograph
i ■Inflow
280 — 25Z29 cfs —I `u Q h ■Primary
260 / — t — _ 248.63 cfs _ Infle YY Arap-1 59.84rpy_/�
� I
240 lea ElIev:7�1;6-is2'-
220
200 -11 11-##race="�7,�77ICf
— — — — — I— — - 4 — —I Q-
180 �v.o-il—
�
160 -II -_R_o_u_nId _Culvert_x_2.0_0
140 + i I I I I I I ,I�
LL 120 — + — � — — — — — - - — � n-10,QI11-
100 - L - � - -11- - i- - - - iL=�7070�
80 - - - - S--�0.07061 T
40
20
0
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
Time (hours)

Reference 5
Culvert Delineation Figure, S&ME Inc.,July 2023.

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�y 2875 28'8 c67° 2727 \ 25s6�^) LySU cs>y 60� °o
707 277,9
0 °'�2017 2823 2> c>6p' ,� m rn ( /6'j5
0 2191 2802 2� �qb �r 2>07 s, ra0
SCALE:
z791 219s s zsy�s� LEGEND
�> 2692 �6 1 " = 300 '
ss 2787 >>
1 1 CULVERT LOCATION
277a N �11p DATE:
2'j2 2153 °s 270 — SHEET FLOW 7/7/2023
ap 2752 6
Z o o SHALLOW CONCENTRATED FLOW PROJECT NUMBER
2743 1 �682 �°b E
�,� CHANNELIZED FLOW 213314
CULVERT DRAINAGE AREA FIGURE NO.
d REFERENCE: 6y°
3 GIS BASE LAYERS WERE OBTAINED FROM ESRI. THIS MAP IS FOR INFORMATIONAL 0 300 600 2663 �611 1 — MAJOR INTERVALS - (10')
PURPOSES ONLY. ALL FEATURE LOCATIONS DISPLAYED ARE APPROXIMATED.THEY ARE N 6.,6 266
NOT BASED ON CIVIL SURVEY INFORMATION,UNLESS STATED OTHERWISE. (FEET) e 2666• 26So 2 MINOR INTERVALS - (2')
IV 2ss6 asp c'6ys s53 2656

Temporary Holding Basin Volume Calculation
Mining Modification Permit No. 61-16
The Quartz Corp. USA I I I
Mitchell County, North Carolina
S&ME Project No. 213314
COMPUTATIONS BY: Signature Date 07/07/2023
Name Cedric H. Ruhl, P.E.
Title Senior Engineer— Project Manager
ASSUMPTIONS Signature "d. Wt Date 07/07/2023
AND PROCEDURES Name Ty Holderbaum, P.E.
CHECKED BY: Title Project Manager
COMPUTATIONS Signature Date 07/07/2023
CHECKED BY: Name Andrew E.Wilmer, E.I.
Title Associate Project Manager
/* Al
REVIEWED BY: 2023 Signature Date 07 07 a / /
Name Christopher J.L. Stahl, P.E.
Title Principal Engineer, V.P.
REVIEW NOTES/COMMENTS:
July 7, 2023 1

Temporary Holding Basin Volume Calculation
Mining Modification Permit No. 61-16
The Quartz Corp. USA I I
Mitchell County, North Carolina
S&ME Project No. 213314
OBJECTIVE:
The objective of this calculation report is to evaluate the proposed temporary holding basin volume, and flow
rates into and out of the temporary holding basin.
SUMMARY:
The storage capacity of the proposed temporary holding basin was evaluated for a range of inflow and outflow
pumping scenarios.
CALCULATIONS
The plant periodically needs to shut down the wastewater treatment system for maintenance. The temporary
holding basin will be a double-lined facility that will temporarily store wastewater, allowing the plant to maintain
operations during wastewater treatment system maintenance. The liquids in the temporary holding basin will be
pumped to the existing wastewater treatment system when the system becomes operational after completion of
maintenance activities.
The temporary holding basin has an operating volume of 715,000 gallons not including freeboard. Several
pumping scenarios were evaluated on a flow rate basis as summarized in the following table:
Table 1: Temporary Holding Basin Pumping Analysis
Temporary Holding Initial
Condition Basin Operating Temporary Inflow Outflow Net Flow Filling Time Dewatering
Description Holding Basin Time
No. Volume (gpm) (gpm) (gpm) (hours)
Storage Volume (hours)
(gallons) (gallons)
Inflow=100 gpm
1A Outflow=0gpm 715,000 0 100 0 100 119.2 N/A
Basin is empty
Inflow=1,000gpm
1B Outflow=0gpm 715,000 0 1,000 0 1,000 11.9 N/A
Basin is empty
Inflow=2,500 gpm
1C Outflow=0gpm 715,000 0 2,500 0 2,500 4.8 N/A
Basin is empty
Inflow=0 gpm
2A Outflow=50 gpm 715,000 715,000 0 50 -50 N/A 238
Basin is full
Inflow=0 gpm
2B Outflow=100 gpm 715,000 715,000 0 100 -100 N/A 119
Basin is full
Inflow=0 gpm
2C Outflow=1,000 gpm 715,000 715,000 0 1000 -1,000 N/A 12
Basin is full
July 7, 2023 2

Temporary Holding Basin Volume Calculation
Mining Modification Permit No. 61-16
The Quartz Corp. USA I I I
Mitchell County, North Carolina
S&ME Project No. 213314
CONCLUSIONS
The storage capacity of the proposed temporary holding basin was evaluated for a range of inflow and outflow
pumping scenarios.
July 7, 2023 3