Certification Letter.pdf

HUBER TECHNOLOGY — MANUFACTURING EXPANSION & Charlotte - Downtown
PASSIVATION PLANT 704.334.7925
704.334.7926
SAND FILTER — ENGINEERS CERTIFICATION
STEWART
$TROLAGER BY DE$IGN
REPORT NUMBER: 1 STEWART PROJ. NUMBER: C22007.00 DATE: 12.20.2023
PROJECT NAME: Manufacturing Expansion & Passivation CLIENT: HUBER TECHNOLOGY
CONTRACTOR: EDIFICE
INSPECTOR: Riyad Baroudi
PURPOSE: Sand Filter Close-out
CONTACT: Cody Herbert
101 N. Tryon Street
Suite 1400
Charlotte, NC 28202
After careful review of the sand filter as built on the Huber Technology's property, I certify that the sand filter
stormwater BMP is constructed to the standards set forth in the North Carolina Department of Environmental
Quality (NCDEQ) BMP manual and complies with the Minimum Design Criteria set forth by NCDEQ. I have listed
my exceptions to my approval below:
• The contractor is working on establishing permanent stabilization on the top of the pond. Hydro -seed
was applied to the bmp top of berm prior to inspection but was washed out by a rain event shortly
thereafter.
• Contractor shall stabilize the floor of the sedimentation chamber with grass.
Please see images from my inspection in the attachments.
Thanks,
Riyad Baroudi PE ��� pl �aRo I'�f
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WWW.STEWARTINC.COM CHARLOTTE / DURHAM / RALEIGH / WILMINGTON / COLUMBIA,SC

HUBER TECHNOLOGY — MANUFACTURING EXPANSION &
PASSIVATION PLANT
SAND FILTER — ENGINEERS CERTIFICATION
STEWART
$TROLAGER 6Y DE$IGN
GENERAL PHOTOS:
Stabilization in process.
Charlotte - Downtown 101 N. Tryon Street
704.334.7925 Suite 1400
704.334.7926 Charlotte, NC 28202
Slope stabilization in process. Hydroseed failed due to rain event. Re -apply Hydroseed.
WWW.STEWARTINC.COM CHARLOTTE / DURHAM / RALEIGH / WILMINGTON / COLUMBIA,SC

HUBER TECHNOLOGY — MANUFACTURING EXPANSION &
PASSIVATION PLANT
SAND FILTER — ENGINEERS CERTIFICATION
STEWART
STRONGER 6Y DE$IGN
Charlotte - Downtown 101 N. Tryon Street
704.334.7925 Suite 1400
704.334.7926 Charlotte, NC 28202
Slope stabilization in process. Hydroseed failed due to rain event. Re -apply Hydroseed.
ON,
Stone/sand surface with underdrain cleanouts.
i Y._y. .: _ .... ry:.•..e _ .. v=fit;,::_4--...}'.-.:
Am
WWW.STEWARTINC.COM CHARLOTTE / DURHAM / RALEIGH / WILMINGTON / COLUMBIA,SC

HUBER TECHNOLOGY — MANUFACTURING EXPANSION & Charlotte - Downtown 101 N. Tryon Street
PASSIVATION PLANT 704.334.7925 Suite 1400
704.334.7926 Charlotte, NC 28202
SAND FILTER — ENGINEERS CERTIFICATION
STEWART
STRONGER 6Y DE$IGN
apply Hydroseed.
Cleanouts, rip -rap berm, sedimentation chamber. Stabilize sedimentation chamber with grass.
WWW.STEWARTINC.COM CHARLOTTE / DURHAM / RALEIGH / WILMINGTON / COLUMBIA,SC

HUBER TECHNOLOGY - MANUFACTURING EXPANSION &
PASSIVATION PLANT
SAND FILTER - ENGINEERS CERTIFICATION
STEWART
STRONGER 6Y DE$IGN
Outside of outlet control structure.
Inside of outlet control structure.
.4 +4i,
t
Charlotte - Downtown 101 N. Tryon Street
704.334.7925 Suite 1400
704.334.7926 Charlotte, NC 28202
WWW.STEWARTINC.COM CHARLOTTE / DURHAM / RALEIGH / WILMINGTON / COLUMBIA,SC

HUBER TECHNOLOGY - MANUFACTURING EXPANSION &
PASSIVATION PLANT
SAND FILTER - ENGINEERS CERTIFICATION
STEWART
STRONGER 6Y DE$IGN
Inside outlet control structure, looking at outlet pipe.
Charlotte - Downtown 101 N. Tryon Street
704.334.7925 Suite 1400
704.334.7926 Charlotte, NC 28202
WWW.STEWARTINC.COM CHARLOTTE / DURHAM / RALEIGH / WILMINGTON / COLUMBIA,SC

HUBER TECHNOLOGY - MANUFACTURING EXPANSION &
PASSIVATION PLANT
SAND FILTER - ENGINEERS CERTIFICATION
I a
STEWART
$TROLAGER 6Y DE$IGN
Sand Filter
Rip -rap lined emergency spillway.
Charlotte - Downtown 101 N. Tryon Street
T 704.334.7925 Suite 1400
F 704.334.7926 Charlotte, NC 28202
WWW.STEWARTINC.COM CHARLOTTE / DURHAM / RALEIGH / WILMINGTON / COLUMBIA,SC

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HUBER TECHNOLOGY — MANUFACTURING EXPANSION &
PASSIVATION PLANT
SAND FILTER — ENGINEERS CERTIFICATION
■
STEWART
$TROLAGER 6Y DE$IGN
Rip -rap apron inlet pipe.
Charlotte - Downtown 101 N. Tryon Street
704.334.7925 Suite 1400
704.334.7926 Charlotte, NC 28202
WWW.STEWARTINC.COM CHARLOTTE / DURHAM / RALEIGH / WILMINGTON / COLUMBIA,SC

6S
Post De
Draina
lopment
Area 2
Sand Filter
Subcat Reach on Link

2023.12.19 - C22007 Huber Technology - Asbuilt
Prepared by Stewart, Inc Printed 12/20/2023
HydroCAD® 10.20-4a s/n 09358 © 2023 HydroCAD Software Solutions LLC Page 2
Rainfall Events Listing (selected events)
Event# Event Storm Type Curve Mode Duration B/B Depth AMC
Name (hours) (inches)
1 1-inch Charlotte 6-hr 1-inch Default 6.00 1 1.00 2
2 100-yr Charlotte 6-hr 100-yr Default 6.00 1 5.34 2

2023.12.19 - C22007 Huber Technology - Asbuilt
Prepared by Stewart, Inc Printed 12/20/2023
HydroCAD® 10.20-4a s/n 09358 © 2023 HydroCAD Software Solutions LLC Page 3
Area Listing (selected nodes)
Area CN Description
(acres) (subcatchment-numbers)
2.350 69 50-75% Grass cover, Fair, HSG B (6S)
5.980 98 Paved parking, HSG B (6S)

2023.12.19 - C22007 Huber Technology - Asbuilt
Prepared by Stewart, Inc Printed 12/20/2023
HydroCAD® 10.20-4a s/n 09358 © 2023 HydroCAD Software Solutions LLC Page 4
Soil Listing (selected nodes)
Area Soil Subcatchment
(acres) Group Numbers
0.000
HSG A
8.330
HSG B 6S
0.000
HSG C
0.000
HSG D
0.000
Other

2023.12.19 - C22007 Huber Technology - Asbuilt
Prepared by Stewart, Inc Printed 12/20/2023
HydroCAD® 10.20-4a s/n 09358 © 2023 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 2.350 0.000 0.000 0.000 2.350 50-75% Grass cover, Fair 6S
0.000 5.980 0.000 0.000 0.000 5.980 Paved parking 6S

2023.12.19 - C22007 Huber Technology - Asbuilt Charlotte 6-hr 1-inch Rainfall=1.00"
Prepared by Stewart, Inc Printed 12/20/2023
HydroCADO 10.20-4a s/n 09358 © 2023 HydroCAD Software Solutions LLC Page 6
Summary for Subcatchment 6S: Post Development Drainage Area 2
Runoff = 6.93 cfs @ 3.10 hrs, Volume= 0.222 af, Depth= 0.32"
Routed to Pond 7P : Sand Filter
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-10.00 hrs, dt= 0.05 hrs
Charlotte 6-hr 1-inch Rainfall=1.00"
Area (ac)
CN
Description
5.980
98
Paved parking, HSG B
2.350
69
50-75% Grass cover, Fair, HSG B
8.330
90
Weighted Average
2.350
28.21 % Pervious Area
5.980
71.79% Impervious Area
Subcatchment 6S: Post Development Drainage Area 2
Hydrograph
❑ Runoff
6.93 cfs
Charlotte 6-hr 1-finch
6 1 1 1 Rainfal4=111.00"
Runoff Area =-8 3310 ac
5 Runoff Volume=0.222 of
4 1 Runoff Depth=0.32"
U. — 1— Tc=O.01I -min
3 CIS=90
2 1 1 1
1 1
1 I I
0
0 1 2 3 4 5 6 7 8 9 10
Time (hours)

2023.12.19 - C22007 Huber Technology - Asbuilt Charlotte 6-hr 1-inch Rainfall=1.00"
Prepared by Stewart, Inc Printed 12/20/2023
HydroCAD® 10.20-4a s/n 09358 © 2023 HydroCAD Software Solutions LLC Page 7
Summary for Pond 7P: Sand Filter
Inflow Area = 8.330 ac, 71.79% Impervious, Inflow Depth = 0.32" for 1-inch event
Inflow = 6.93 cfs @ 3.10 hrs, Volume= 0.222 of
Outflow = 0.17 cfs @ 5.95 hrs, Volume= 0.095 af, Atten= 98%, Lag= 171.3 min
Primary = 0.17 cfs @ 5.95 hrs, Volume= 0.095 of
Secondary = 0.00 cfs @ 0.00 hrs, Volume= 0.000 of
Routing by Stor-Ind method, Time Span= 0.00-10.00 hrs, dt= 0.05 hrs
Peak Elev= 770.44' @ 5.95 hrs Surf.Area= 6,741 sf Storage= 7,934 cf
Plug -Flow detention time= 208.1 min calculated for 0.095 of (43% of inflow)
Center -of -Mass det. time= 175.2 min ( 392.2 - 217.0 )
Volume Invert Avail.Storage Storage Description
#1 769.00' 39,347 cf Custom Stage Data (Prismatic)Listed below (Recalc)
Elevation Surf.Area Inc.Store Cum.Store
(feet) (sq-ft) (cubic -feet) (cubic -feet)
769.00 3,903 0 0
770.00 6,281 5,092 5,092
771.00 7,336 6,809 11,901
772.00 8,553 7,945 19,845
773.00 9,725 9,139 28,984
774.00 11,000 10,363 39,347
Device Routing Invert Outlet Devices
#1 Primary 766.22' 36.0" Round Culvert
L= 66.6' RCP, sq.cut end projecting, Ke= 0.500
Inlet / Outlet Invert= 766.22' / 761.96' S= 0.0640'/' Cc= 0.900
n= 0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1 769.00' Special & User -Defined
Head (feet) 0.00 1.00 2.00 3.00
Disch. (cfs) 0.000 0.153 0.197 0.241
#3 Device 1 771.98' 48.0" x 48.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#4 Secondary 773.26' 30.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=0.17 cfs @ 5.95 hrs HW=770.44' (Free Discharge)
L1=Culvert (Passes 0.17 cfs of 56.10 cfs potential flow)
L2=Special & User -Defined (Custom Controls 0.17 cfs)
3=Orifice/G rate
( Controls 0.00 cfs)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=769.00' (Free Discharge)
L4= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

2023.12.19 - C22007 Huber Technology - Asbuilt Charlotte 6-hr 1-inch Rainfall=1.00"
Prepared by Stewart, Inc Printed 12/20/2023
HydroCADO 10.20-4a s/n 09358 © 2023 HydroCAD Software Solutions LLC Page 8
Pond 7P: Sand Filter
Hydrograph
I I
7
,
--7--7-
6
,
5
i
L
L
4
i
_o
/
LL
III
3
i
2
1
0 1 2 3
■ Inflow
—— —————————— ■Outflow
0 Prima
Inflow Al�rea4336 ac ■ Se ondary
Peak'IElevi=7701.44'
- - r - - rStofage�,934 cf
----++
I I I I
------------
I I I I I
I I I I
I I I I
;CAMP
4 5 6 7 8 9 10
Time (hours)

2023.12.19 - C22007 Huber Technology - Asbuilt Charlotte 6-hr 100-yr Rainfall=5.34"
Prepared by Stewart, Inc Printed 12/20/2023
HydroCAD® 10.20-4a s/n 09358 ©2023 HydroCAD Software Solutions LLC Page 9
Summary for Subcatchment 6S: Post Development Drainage Area 2
Runoff = 70.09 cfs @ 3.08 hrs, Volume= 2.919 af, Depth= 4.20"
Routed to Pond 7P : Sand Filter
Runoff by SCS TR-20 method, UH=SCS, Weighted-CN, Time Span= 0.00-10.00 hrs, dt= 0.05 hrs
Charlotte 6-hr 100-yr Rainfall=5.34"
Area (ac)
CN
Description
5.980
98
Paved parking, HSG B
2.350
69
50-75% Grass cover, Fair, HSG B
8.330
90
Weighted Average
2.350
28.21 % Pervious Area
5.980
71.79% Impervious Area
Subcatchment 6S: Post Development Drainage Area 2
75
— — — — —
70
— — — — — 1
65
60
55
50—
w 45
40
— — — — — —
LL 35
I—
--�---I
30
— — — — — I— —
25I-
20
10
Hydrograph
I
- Charlotte 6-hr 100 y-r
---11--- 1 Raipfal=0-3-4"
Runoff Areal=8.330 ac
- - -I- - - T - - - I — — — r - - - - - - F - -
- - -1- - - - Ru-n-off Volume=2.919-a#
- - - - --1-Runpff Dgpth=,�20"
- — — — — - — — — — — — — — — — — — — —
Tc=0.01 min
--- G"- 0
—-1— —-1———L——-1———L——
T- — —
0 1 2 3 4 5 6 7 8 9 10
Time (hours)
■ Runoff

2023.12.19 - C22007 Huber Technology - Asbuilt Charlotte 6-hr 100-yr Rainfall=5.34"
Prepared by Stewart, Inc Printed 12/20/2023
HydroCAD® 10.20-4a s/n 09358 © 2023 HydroCAD Software Solutions LLC Page 10
Summary for Pond 7P: Sand Filter
Inflow Area = 8.330 ac, 71.79% Impervious, Inflow Depth = 4.20" for 100-yr event
Inflow =
70.09 cfs @
3.08 hrs,
Volume=
2.919 of
Outflow =
64.85 cfs @
3.11 hrs,
Volume=
2.538 af, Atten= 7%, Lag= 1.5 min
Primary =
64.85 cfs @
3.11 hrs,
Volume=
2.538 of
Secondary =
0.00 cfs @
0.00 hrs,
Volume=
0.000 of
Routing by Stor-Ind method, Time Span= 0.00-10.00 hrs, dt= 0.05 hrs
Peak Elev= 773.13' @ 3.11 hrs Surf.Area= 9,892 sf Storage= 30,269 cf
Plug -Flow detention time= 34.4 min calculated for 2.525 of (87% of inflow)
Center -of -Mass det. time= 21.5 min ( 220.5 - 199.0 )
Volume Invert
Avail.Storage Storage Description
#1 769.00'
39,347 cf Custom Stage Data (Prismatic)Listed below (Recalc)
Elevation Surf.Area
Inc.Store Cum.Store
(feet)
(sq-ft)
(cubic -feet) (cubic -feet)
769.00
3,903
0 0
770.00
6,281
5,092 5,092
771.00
7,336
6,809 11,901
772.00
8,553
7,945 19,845
773.00
9,725
9,139 28,984
774.00
11,000
10,363 39,347
Device Routing
Invert
Outlet Devices
#1 Primary
766.22'
36.0" Round Culvert
L= 66.6' RCP, sq.cut end projecting, Ke= 0.500
Inlet / Outlet Invert= 766.22' / 761.96' S= 0.0640'/' Cc= 0.900
n= 0.013 Concrete pipe, bends & connections, Flow Area= 7.07 sf
#2 Device 1
769.00'
Special & User -Defined
Head (feet) 0.00 1.00 2.00 3.00
Disch. (cfs) 0.000 0.153 0.197 0.241
#3 Device 1
771.98'
48.0" x 48.0" Horiz. Orifice/Grate C= 0.600
Limited to weir flow at low heads
#4 Secondary
773.26'
30.0' long x 10.0' breadth Broad -Crested Rectangular Weir
Head (feet) 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60
Coef. (English) 2.49 2.56 2.70 2.69 2.68 2.69 2.67 2.64
Primary OutFlow Max=63.87 cfs @ 3.11 hrs HW=773.12' (Free Discharge)
L1=Culvert (Passes 63.87 cfs of 79.09 cfs potential flow)
L2=Special & User -Defined (Custom Controls 0.24 cfs)
3=Orifice/G rate
(Weir Controls 63.63 cfs @ 3.49 fps)
Secondary OutFlow Max=0.00 cfs @ 0.00 hrs HW=769.00' (Free Discharge)
L4= Broad -Crested Rectangular Weir( Controls 0.00 cfs)

2023.12.19 - C22007 Huber Technology - Asbuilt Charlotte 6-hr 100-yr Rainfall=5.34"
Prepared by Stewart, Inc Printed 12/20/2023
HydroCAD® 10.20-4a s/n 09358 ©2023 HydroCAD Software Solutions LLC Page 11
Pond 7P: Sand Filter
Hydrograph
70.09 cfs
I
I I I
4nflow Are"- 336 ac
75
70:
/
/ / / /
64.85 cfs
— — — 64.85 cfs r
T 7C' � � T
65
/ / /
----+--+--StOTAge=307,269Cf
60
/' / /
— — — 4- — —
+ — — + — — — -4 — —
55
/
/
— — 4- — —
— — — — — — 4 — — -4 — —
50
//
—— 1
L—-1—-1—-1——-i——
w 45
/'/
——
———————— —— ——
40
o35
/ /
'//1
'
——
——
—— —— —— —— ——
-—— —— —— —— ——
u 30
/ /I
— — -
— — — — — —
25
20
/
— — -
— — — — — —
15
10
1 2 3 4 5 6 7
Time (hours)
LInflow
wrydary