NCS000598_Renewal application_20240327

A119al
an Air Uquide company
March 22,2024 �ZOZ L d�hf
State of North Carolina Department of Environmental Quality 0 3 A(3 a 3 8
Energy, Mineral and Land Resources
1612 Mail Service Center,
Raleigh,NC 27699-1612
Attention: Brianna Young
Subject: NPDES Permit Stormwater Permit No.NCS000598 Renewal Application
Airgas USA, LLC—Mebane Facility
Mebane,Alamance County,North Carolina
Dear Ms. Young:
Airgas USA, LLC (Airgas) is submitting the enclosed application for the individual National Pollutant
Discharge Elimination System (NPDES) Stormwater Permit No. NCS000598 Renewal. The Permit
renewal application package includes:
1. One(1)copy of completed and signed EPA Form I with a topographic map;
2. One(1)copy of completed and signed EPA Form 2F with a site drainage map;and
3. Two (2) copies of the Supplemental Information Required for Renewal of Individual NPDES
Stormwater Permit
The NPDES Stormwater Permit No. NCS000598 expires on September 30, 2024 and the Permit renewal
application needs to be submitted 180 days prior to the Permit expiration date. Thus, Airgas meets the
required permit renewal application deadline. As instructed, an electronic copy of the permit application
package is also emailed to your attention at [e-mail].
Please be advised that Airgas had planned to collect a sample from Outfall 001 for analyses of the
pollutants listed in Table A of EPA Form 2F prior to the submission of the Permit renewal application.
However,the planned sampling and analysis did not occur at the time of the application preparation and
Airgas is reporting the 2023 compliance sampling data in Table A of EPA Form 2F. BOD5 is one of the
pollutants listed in Table A of EPA Form 2F but not listed in the current Permit and therefore it was not
analyzed in 2023. Due to the nature of the Nitrogen, Oxygen and Argon production operations at the
facility, BOD5 is unlikely detected or even if it is detected, it may be present in a very low concentration.
If you need additional information and/or have any questions about the renewal application, please
contact Mr. Stephen Kim, our consultant, at(215)941-2770 or [e-mail] or me
at(330)454-1330 or rodney..st.john @air aQ s.com.
Sincerel ,
Rodney John
Plant Manager
cc: File
Enclosures: As Noted

EPA FORM'1

EPA Identification Number NPDES Permit Number Facility Name OMB No.2040-0004
N/A NCS000598 Airgas USA LLC Expires 077311202E
Form U.S.Environmental Protection Agency
1 \-.EPA Application for NPDES Permit to Discharge Wastewater
NPDES GENERAL INFORMATION
REQUIRINGSECTION 1.ACTIVITIES •D r AND
1.1 Applicants Not Required to Submit Form 1
1.1.1 Is the facility a new or existing publicly owned 1.1.2 Is the facility a sludge-only facility(i.e.,a facility
treatment works or has your permitting authority
directed you to submit Form 2A? that does not discharge wastewater to surface
waters)?
If yes,STOP.Do NOT complete No If yes,STOP.Do NOT complete [a No
Form 1.Complete Form 2A.If the Form 1.Complete Form 2S.
facility is also a treatment works
treating domestic sewage,you
must also complete Form 2S.
1.2 Applicants Required to Submit Form I
€ 1.2.1 Is the facility a concentrated animal feeding 1.2.2 Is the facility an existing manufacturing,
CL
operation or a concentrated aquatic animal commercial,mining,or silvicultural facility that is
a production facility? currently discharging process wastewater?
z Yes 4 Complete Form 1 and 0 No ❑ Yes 4 Complete Form Ej No
Form 2B. 1 and Form 2C.
1.2.3 Is the facility a new manufacturing,commercial, 1.2.4 Is the facility a new or existing manufacturing,
mining,or silvicultural facility that has not yet commercial,mining,or silvicultural facility that
commenced to discharge? discharges only nonprocess wastewater?
Yes 4 Complete Form 1 and E] No ❑ Yes 4 Complete Form 1 0 No
Form 2D. and Form 2E.
a1.2.5 Is the facility a new or existing facility whose 1.2.6 Is the facility a new or existing treatment works
discharge is composed entirely of stormwater treating domestic sewage that discharges
associated with industrial activity or whose wastewater to surface waters?
discharge is composed of both stormwater and non.
stormwater?
0 Yes 4 Complete Form 1 and ❑ No ❑ Yes 4 Complete Form 1, ✓� No
Form 2F unless Form 2S,and
exempted by 40 CFR any other
122,26(b)(14)(x)or applicable forms,
(b)(15). as directed by
your permitting
authorii .
SECTIONDD• • • i
2_1 Facility Name
0
Airgas USA LLC
2.2 EPA Identification Number
-a
M N/A
N
2_3 Facility Contact
a Name(first and last) Title Phone number
Rodney St.John Plant Manager_ g [phone]
Email address
4
E
b
z [e-mail]
EPA Form 3510-1 Page 1

EPA Identification Number NPDES Permit Number Facility Name OMB No.2040-0004
N/A NC5000598 Airgas USA LLC
Expires 07131/2026
224 Facility Mailing Address
Street or P.O.box
2025 Development Center Drive
City or town State ZIP code
Mebane NC 27302
2_5 Facility Location
Street,route number,or other specific identifier
b C
v 2025 Development Center Drive
rn
.2 County name County code(if known)
u Alamance
0
E _j City or town State ZIP code
Z 'c° 1 1 Mebane INC 127302
CODESSECTION 3.SIC AND NAICS r
3 1 SIC Code(s) Description(optional)
2813 Industrial gases manufacturing-Nitrogen,Oxygen and Argon
N
N
78
U
z 3.22 NAICS Code(s) Description(optional)
iO v 325120 Industrial gases manufacturing Nitrogen,Oxygen and Argon
SECTION 4.OPERATOR INFORMATION(40
4_1 Dame of Operator
Airgas USA LLC
c
0 4.2 Is the name you listed in Item 4.1 also the owner?
R
w
121 Yes ❑ No
7. 4.3 Operator Status
o —
2 ❑ Public—federal ❑ Public—state ❑ Other public(specify)
d
o © Private ❑ Other(specify)
444 Phone Number of Operator
[phone]
EPA Form 3510-1 Page 2

EPA Identification Number NPDES Permit Number Facility Name OMB No.2040-0004
N/A NC5000598 Airgas USA LLC Expires 0713112026
4_5 Operator Address
o Street or P.O.Box
3 2025 Development Center Drive
City or town State ZIP code
4� U
12 Mebane NC �27302
C address of operator
[Email
[e-mail]
1 1
5-1 Is the facility located on Indian Land?
❑Yes ❑✓ No
ENVIRONMENTALSECTION 6.EXISTING i
6.1 Existing Environmental Permits(check all that apply and print or type the corresponding permit number for each)
a ® NPDES(discharges to ❑ RCRA(hazardous wastes) ❑ UIC(underground injection of
a H surface water) fluids)
NCS000598
❑ PSD(air emissions) ❑ Nonattainment program(CAA) ❑ NESHAPs(CAA)
�Dff=cean mping(MPRSA) ❑ Dredge or fill(CWA Section 404) ❑ Other(specify)
71 Have you attached a topographic map containing all required information to this application?(See instructions for
specific requirements.)
✓❑ Yes ❑ CAFO—Not Applicable(See requirements in Form 2B.)
SECTIONr
81 Describe the nature of your business,
Airgas USA LLC(Airgas)separates the atomospheric air,produces liguid Nitrogen,liquid Oxygen and liquid
y Argon(SIC 2813),and distribute products to its customers in the region via tank trucks. Airgas has
.N
truck maintenance operations inside a maintenance shop at the site location.
m
a
z
SECTION
•• r
91 Does your facility use cooling water?
❑ Yes ❑✓ No 4 SKIP to Item 10.1.
99.22 Identify the source of cooling water.(Note that facilities that use a cooling water intake structure as described at
M 2 40 CFR 125,Subparts I and J may have additional application requirements at 40 CFR 122.21(r).Consult with your
a NPDES permitting authority to determine what specific information needs to be submitted and when.)
o m
V c
EPA Form 3510-1 Page 3

EPA idenbfication Number NPDES Permit Number Facility Name OMB No.2040-0004
N/A NCS000598 Airgas USA LLC Expires 0713112026
SECTIONI VARIANCE REQUESTS # I
Q.1 Do you intend to request or renew one or more of the variances authorized at 40 CFR 122.21(m)?(Check all that
w apply.Consult with your NPDES permitting authority to determine what information needs to be submitted and when.)
❑ Fundamentally different factors(CWA ❑ Water quality related effluent limitations(CWA Section
Cr
Section 301(n)) 302(b)(2))
❑ Non-conventional pollutants(CWA ❑ Thermal discharges (CWA Section 316(a))
Section 301(c)and(g))
❑✓ Not applicable
SECTION • CERTIFICATION STATEMENT(40
11.1 In Column 1 below, mark the sections of Form 1 that you have completed and are submitting with your application.
For each section,specify in Column 2 any attachments that you are enclosing to alert the permitting authority. Note
that not all applicants are required to provide attachments.
Column 1 Column 2
0 Section 1:Activities Requiring an NPDES ❑ w/attachments
Permit
❑ Section 2: Name, Mailing Address,and ❑ w/attachments
Location
✓❑ Section 3:SIC Codes ❑ wl attachments
❑ Section 4:Operator Information ❑ w/attachments
Section 5: Indian Land ❑ w/attachments
Section 6: Existing Environmental Permits ❑ wl attachments
❑ wl additional
0 Section 7: Map 0 w/topographic map attachments
a ✓❑ Section 8:Nature of Business ❑ w/attachments
:~ ✓❑ Section 9:Cooling Water Intake Structures ❑ wl attachments
0 Section 10.:Variance Requests ❑ wl attachments
0 Section 11:Checklist and Certification ❑ wl attachments
y Statement
1?.2 Provide the following certification.(See instructions to determine the appropriate person to sign the application.)
ca
Certification Statement
I certify under penalty of law that this document and all attachments were prepared under my direction or supervision
in accordance with a system designed to assure that qualified personnel properly gather and evaluate the information
submitted. Based on my inquiry of the person or persons who manage the system,or those persons directly
responsible for gathering the information,the information submitted is, to the best of my knowledge and belief,true,
accurate,and complete. I am aware that there are significant penalties for submitting false information,including the
possibility of fine and imprisonment for knowing violations.
Name(print or type first and last name) Official title
Thomas Stringer Vice President,Production&Project Execution
Signature Date signed
r 3�Zo�y�x y
EPA Form 3510-1 Page 4

ATTACHMENT TO EPA FORM 4
TOPOGRAPHIC MAP
(USGS MAP Mebane Quadrangle, North Carolina,7.5 Minute Series)

-a• CANTERWOOO OR •._ , ..,,
y �
1V[aNtER 9T
. l�irgas`Site Locafion
Outfall001 0
_ � o
DIP
Olt
n
4
� o
w
Y
sr ff 5 cxo )RA Sr EXO
�sr sf N
O i ;/
a
.$i S Fly ST o O
4 S �bSUa F~
SCALE 1:24 OW
1 0.5 0 KILOMEfER5 1 2
1000 500 0 YETERS 1000 2000
1 0.5 0 1
MILES
1000 0 1000 2000 3000 4000 5111A buuc M0 am 9000 10000
FCC-"
Source: Figure 1 TOPOGRAPHIC MAP
USGS Topo Map—Mebane Airgas USA, LLC
Quadrangle, NC 2022 2026 Development Center Drive, Mebane, NC 27302

ERA FORM 2F

EPA Identification Number NPDES Permit Number Facility Name OMB No.2040-0004
N/A NC5000598 Airgas USA LLC Expires 0713112026
Form U.S Environmental Protection Agency
2F V,EPA Application for NPDES Permit to Discharge Wastewater
NPDES STORMWATER DISCHARGES ASSOCIATED WITH INDUSTRIAL_ACTIVITY
SECTION • r 1
1.1 Provide information on each of the facilit 's outfalls in the table below
Outfall Receiving Water Name Latitude Longitude
Number
001 Tributary(Tinnis Creek) 36 Deg 5' 30.36" 79 Deg 17` 57.42"
c
0
*'a to Moadams Creek
u
0
J
ep
7
0
SECTION '• 1
21 Are you presently required by any federal,state,or local authority to meet an implementation schedule for
constructing,upgrading,or operating wastewater treatment equipment or practices or any other environmental
programs that could affect the discharges described in this application?
❑ Yes ❑✓ No 4 SKIP to Section 3.
2_2 Briefly identify each applicable project in the table below.
Final Compliance
Brief Identification and Affected Outfaits Source(s)of Discharge Dates
Description of Project (list outfall numbers)
Required Projected
c
d
E
0
C
a
E
22.33 Have you attached sheets describing any additional water pollution control programs(or other environmental
projects that may affect your discharges)that you now have underway or planned?(optional item)
❑ Yes ❑ No
EPA Form 3510.21' Page 1

EPA Idenfficalion Number NPDES Permit Number Facility Name OMB No.2040-0004
N/A NCS000598 Airgas USA LLC Expires 0713112026
SECTION 3.SITE D' 1
31 Have you attached a site drainage map containing all required information to this application?(See instructions for
Im
A to c ra specific guidance.)
r 'T M
n ❑✓ Yes
SECTION 4. •O i
Provide information on the facility's pollutant sources in the table below.
Outfall Impervious Surface Area Total Surface Area Drained
Number (within a mile radius of the facility) (within a mile radius of the facility)
specify units specify units
001 4.11 6.07
acres acres
specify units specify units
specify units specify units
specify units specify units
specify units specify units
specify units specify units
4.2 Provide a narrative description of the facility's significant material in the space below.(See instructions for content
requirements.)
w The site is an air separation unit(ASU)plant.The raw material is the atmospheric air and the final
products are liquid nitrogen,liquid oxygen and liquid argon. The final products are stored in the cryogenic tanks
a outdoors.Loading activities takes place in the truck loading scale area and the stormwater runoff from the truck
y loading area is collected and discharged into the public sewer system. Trash is collected in a trash dumpster with lid
c
a and is hauled away periodically by a licensed hauler. Trucks are maintained inside the truck maintenance shop.
o Diesel Fuel Exhaust(DEF)is stored outdoors and added to transport trucks. Herbicides are used for weed control
once or twice a year and applied by a contracted third party.
43 Provide the location and a description of existing structural and non-structural control measures to reduce pollutants
in stormwater runoff, See instructions forspecificguidance.)
Stormwater Treatment
Codes
Outfall from
Number Control Measures and Treatment Exhibit
2F-1
lisle
001 Sedimentation(Settling)-(Onsite)Wet Pond 1-U
001 Discharge to Surface Water 4-A
EPA Form 3510-2F Page 2

EPA Identification Number NPDES Permit Number Facility Name OMB No.200-0004
N/A NCS000598 Airgas USA LLC Expires 0713112026
SECTION •N STORMWATER 1 I
5 Provide the following certification.(See instructions to determine the appropriate person to sign the application.)
I certify under penalty of law that the outfall(s) covered by this application have been tested or evaluated for the
presence of non-stormwater discharges. Moreover, I certify that the outfalls identified as having non-stormwater
discharges are described in either an accompanying NPDES Form 2C, 2D, or 2E application.
Name(print or type first and last name) Official title
Thomas Stringer Vice President, Production&Project Execution
Signature Date signed
w
Er G
—2 Provide the testing information requested in the table below.
Onsite Drainage Points
o Outfall Description of Testing Method Used Date(s)of Testing Directly Observed
{Number Dudng Test
m
3
001 Review of the facility's design and 02/13/2024 Drainage inlet
cis
c
observations of facility operations during a dry period to the onsite wet pond
SECTION . SIGNIFICANT LEAKS OR 1
Q
6—� Describe any significant leaks or spills of toxic or hazardous pollutants in the last three years.
Cn
None
0
co
Y
d
J
C
LTJ
SECTIONDISCHARGE • ' • I
See the instructions to determine the pollutants and parameters you are required to monitor and, in turn,the tables you must
complete.Not all applicants need to complete each table.
7_1 Is this a new source or new discharge?
Yes 4 See instructions regarding submission of � No 4 See instructions regarding submission of
estimated data. actual data.
Tables A,B,C,and D
cc
T�2 Have you completed Table A for each outfall?
0 Yes
EPA Form 3510-2F Page 3

EPA Identification Number NPDES Permit Number Facility Name OMB No.2040-0004
N/A NCS000598 Airgas USA LLC Expires 0713112026
73 Is the facility subject to an effluent limitation guideline(ELG)or effluent limitations in an NPDES permit for its
process wastewater?
❑ Yes No 4 SKIP to Item 7.5.
7_4 Have you completed Table 6 by providing quantitative data for those pollutants that are(1)limited either directly or
indirectly in an ELG and/or(2)subject to effluent limitations in an NPDES permit for the facility's process
wastewater?
❑ Yes
7. Do you know or have reason to believe any pollutants in Exhibit 2F-2 are present in the discharge?
❑ Yes ❑✓ No 4 SKIP to Item 7,7.
7_6 Have you listed all pollutants in Exhibit 2F-2 that you know or have reason to believe are present in the discharge
and provided quantitative data or an explanation for those pollutants in Table C?
❑ Yes
7_7 Do you qualify for a small business exemption under the criteria specified in the Instructions?
❑ Yes-SKIP to Item 7.18. ❑ No
d
7_8 Do you know or have reason to believe any pollutants in Exhibit 2F-3 are present in the discharge?
❑ Yes ❑ No 4 SKIP to Item 7,10.
0
0 7_9 Have you listed all pollutants in Exhibit 2F-3 that you know or have reason to believe are present in the discharge in
Table C?
0 ❑ Yes
C
m
a' 710 Do you expect any of the pollutants in Exhibit 2F-3 to be discharged in concentrations of 10 ppb or greater?
L
U
o ❑ Yes ❑ No 4 SKIP to Item 7.12.
7.11 Have you provided quantitative data in Table C for those pollutants in Exhibit 2F-3 that you expect to be discharged
in concentrations of 10 ppb or greater?
❑ Yes
7.12 Do you expect acrolein,acrylonitrile,2,4-dinitrophenol,or 2-methyl4,6-dinitrophenol to be discharged in
concentrations of 100 ppb or greater?
❑ Yes ❑✓ No 4 SKIP to item 7.14,
713 Have you provided quantitative data in Table C for the pollutants identified in Item 7.12 that you expect to be
discharged in concentrations of 100 ppb or greater?
❑ Yes
7.14 Have you provided quantitative data or an explanation in Table C for pollutants you expect to be present in the
discharge at concentrations less than 10 ppb(or less than 100 ppb for the pollutants identified in Item 7.12)?
❑ Yes
7.15 Do you know or have reason to believe any pollutants in Exhibit 2F-4 are present in the discharge?
❑ Yes © No 4 SKIP to Item 7,17.
EPA Form 3510-2F Page 4

EPA Idenffication Number NPOES Permit Number Facility Name OMB No,2040-0004
N/A NCS000598 Airgas USA LLC Expires 07131/2026
7.16 Have you listed pollutants in Exhibit 217-41 that you know or believe to be present in the discharge and provided an
explanation in Table C?
❑ Yes
a 7.17 Have you provided information for the storm event(s)sampled in Table D?
❑� Yes
U
`0 Used or Manufactured Toxics
7.18 Is any pollutant listed on Exhibits 2F-2 through 2F-4 a substance or a component of a substance used or
,o manufactured as an intermediate or final product or byproduct?
c
❑ Yes ❑✓ No 4 SKIP to Section 8,
L
7.19 List the pollutants below,including TCDD if applicable.Attach additional sheets,if necessary.
v,
�. 4. 7.
2, 5. 8.
3, 6. 9.
SECTIONBIOLOGICAL TOXICITYi
60 Do you have any knowledge or reason to believe that any biological test for acute or chronic toxicity has been made
R on any of your discharges or on a receiving water in relation to your discharge within the last three years?
0
c' ❑ Yes ❑✓ No 3 SKIP to Section 9,
B_2 Identify the tests and their purposes below.
Test(s) Purpose of Test(s) Submitted to NPDESPermittin Authority?
Date Submitted
0
❑ Yes ❑ No
❑ Yes ❑ No
0
m
❑ Yes ❑ No
SECTION9.CONTRACT •- • r
9_1 Were any of the analyses reported in Section 7(in Tables A through C)performed by a contract laboratory or
consulting firm?
ED Yes ❑ No 4 SKIP to Section 10.
0 92 Provide information for each contract laboratory or consulting firm below.
Laboratory Number 1 Laboratory Number 2 Laboratory Number 3
Dame of laboratory/firm pace Analytical Services,LLC
Hl
.y
Z.
Laboratory address 6701 Conference Drive,
Raleigh,NC 27607
b
Phone number
0
U [phone]
Pollutant(s)analyzed O&G,COD,TSS,Total
Phosphorus,TKN, Total
Nitrogen and pH
EPA Foam 3510-2F Page 5

EPA Identification Number NPDES Permil Number Facilily Name OMB No.2040-0004
N/A NCS000598 Airgas USA LLC Expires 0713112026
SECTION 1 CHECKLIST AND 1 AND
10.1 In Column 1 below,mark the sections of Form 2F that you have completed and are submitting with your application.
For each section,specify in Column 2 any attachments that you are enclosing to alert the permitting authority. Note
that not all applicants are required to complete all sections or provide attachments.
Column 1 Column 2
❑� Section 1 ❑ wl attachments(e.g., responses for additional outfalls)
❑✓ Section 2 ❑ w/attachments
Section 3 0 w/site drainage map
❑� Section 4 ❑ wl attachments
❑� Section 5 ❑ wl attachments
❑✓ Section 6 ❑ wl attachments
❑✓ Section 7 ❑ Fable A ❑ wl small business exemption request
-` ❑ Table B ❑ wl analytical results as an attachment
C
❑ Table C ❑ Table D
V
d 0 Section 8 ❑ w/attachments
ca
✓❑ Section 9 ❑ wl attachments(e.g., responses for additional contact laboratories or firms)
U ❑✓ Section 10
w
c �0 2 Provide the following certification,(See instructions to determine the appropriate person to sign the application.)
Certification Statement
I certify under penalty of law that this document and all attachments were prepared under my direction or supervision
in accordance with a system designed to assure that qualified personnel property gather and evaluate the information
submitted.Based on my inquiry of the person or persons who manage the system or those persons directly responsible
for gathering the information, the information submitted is, to the best of my knowledge and belief, true, accurate, and
complete. l am aware that there are significant penalties for submitting false information,including the possibility of fine
and imprisonment for knowing violations.
Name(print or type first and last name) Official title
Thomas Stringer Vice President,Production&Project Execution
Signature Date signed
EPA Form 3510-2F Page 6

EPA Identification Number NPDES Permit Number Facility Name Outfall Number OMB No.2040-0004
N/A I NCS000598 Airgas USA LLC col Expires 07/3112026
TABLE A.CONVENTIONAL AND NON CONVENTIONAL PARAMETERS(40
You must provide the results of at least one anal1 sis for every polkitant in this table.Complete one table for each ouffaT.See instructions for additional details and requirements.
MaXltnafn�DaliyaDischarge Average
"MON
618 ar'g
ape
100
Atimur of Stbiw
der
A Iv "Sam ed 0"
Mo.--
Eta!'
codbs 166 Instruc*O:
Ig �dlwh
-00
Oil and grease <4.9 n <4.9 mg/I 2
Biochemical oxygen demand(BOD5) Not measured N/A Not measured N/A 0
Chemical oxygen demand(COD) <25 mg/I N/A <25 mg/I N/A 2
A Total suspended solids(TSS) 17.4 mg/I N/A 15.8 mg/I N/A 2
S..:,. Total phosphorus 0.061 mg/I N/A <0.056 mg/I N/A 2
IS. Total Kjeldahl nitrogen(TKN) 0.88 mg/I N/A <0.565 mg/I N/A 2
7.1' Total nitrogen(as N) 2.00 mg/I N/A <0.6745 mg/I N/A 2
pH(minimum) 6.1 s.u. N/A I
8.
pH(maximum) 6.6 sm. N/A
Sampling shall be conducted according to sufficiently sensitive test procedures(i.e.,methods)approved under 40 CFR 136 for the analysis of pollutants or pollutant parameters or
required under 40 CFR Chapter 1,Subchapter N or 0.See instructions and 40 CFR 122.21(e)(3).
EPA Form 3510-2F Page 7

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EPA IdenVication Number NPDES Permit Number Facility Name Outfall Number OMB No.2040-0004
N/A NCS000598 Airgas USA LLC 001 Expires 07/31/2026
TABLE B.CERTAIN CONVENTIONAL AND NON CONVENTIONAL '• 1 CFR 122.26(C)(1)(1)(E)(4) t
List each pollutant that is limited in an effluent limitation guideline(ELG)that the facility is subject to or any pollutant listed in the facility's NPDES permit for its process wastewater(if the
facility is operating under an existing NPDES permit).Complete one table for each cuNall.See the instructions for additional details and requirements.
�fn YYyy -
axiMa" al{y f3isahairg a Dslliy, ischarge Source of
P61tiartt grid CAS Ntnntier' u Niumberrdf 5tonm Mormation
Grab$ftle7aken :. Giab Sarh le TaTcetlr (newsu�ucdsaw
(if avaUabte). Flow4i(feighbed _ p FIiWdlgltted Et/ents Sampled
Dtidrtg�i1 dudn]Fiist
C discfiaigers ardy;use!>
omposite Eoritt�otdte
30 Mlnukss .301Mlmites codes'in mshucBons)"
Not applicable
Sampling shall be conducted according to sufficiently sensitive test procedures(i.e.,methods)approved under 40 CFR 136 for the analysis of pollutants or pollutant parameters or
required under 40 CFR Chapter I,Subchapter N or 0.See instructions and 40 CFR 122.21(e)(3).
EPA Form 3510-2F Page 9

This page intentionally,left blank.

EPA Identification Number NPOES Permit Number Facility Name Outfall Number OMB No.2040-0004
N/A NCSOCO598 Airgas USA LLC 001 Expires 0713112026
TABLE C.TOXIC POLLUTANTS,CERTAIN HAZARDOUS SUBSTANCES,AND ASBESTOS(40 CFR 122.26(C)(1)(1)(E)(4)AND 40 CIFIR 122.21(G)(7)(VI)(B)AND(VII))i
List each pollutant shown in Exhibits 2F-2,2F-3,and 2F4 that you know or have reason to believe is present.Complete one table for each outfall.See the instructions for additional
details and requirements.
Maximum Daily Discharge Average Daily Discharge Source of
(Spec' units s eci units Information
Pollutant and CAS Number Number of Storm
Grab Sample Taken Grab Sample Taken (new sourceinew
(if available) During First Flow-Weighted During First Flow-Weighted Events Sampled dischargers only;use
30 Minutes Composite 30 Minutes Composite codes in instructions)
Not applicable
Sampling shall be conducted according to sufficiently sensitive test procedures(i.e.,methods)approved under 40 CFR 136 for the analysis of pollutants or pollutant parameters or
required under 40 CFR Chapter I,Subchapter N or 0.See instructions and 40 CFR 122.21(e)(3),
EPA Form 3510-2F Page 11

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EPA Identification Number NPDES Permit Number Facility name Outfall Number OMB No.2040-0004
N/A NCS000598 Airgas USA LLC 001 Expires 07/31/2026
STORMTABLE D. a- • r
Provide data for the storm event(s)that resulted in the maximum daily discharges for the flow-weighted composite sample.
Number of Hours Between
Total Rainfall During Maximum Flow Rate
Duration of Storm Event (in inches} Beginning of Storm Measured and Total Flow from Rain Event
Date of Storm Event (in hours) Storm Event End of Previous Measurable Rain During Rain Event (in gallons or specify units)
(in gpm or specify units)
Event
12/17/7023
App.15.3 hours 2.75 App. 148 hours Not estimated App.349,377 gallons
Provide a description of the method of flow measurement or estimate.
It rained on 12/17/2023 but the sampling was conducted on 12/18/2023.
Stormwater runoff from the industrial activity areas at the facility is collected in the onsite wet pond with the design total capacity of approximately 112,270 ft3. Due to the design,the
stormwater discharge occurs at Outfall 001(the wet pond 18"HDPE outlet/effluent pipe)when the water level in the wet pond reaches the drawdown orifice of the riser structure. This
drawdown orifice is approximately 9 feet above the bottom of the wet pond. Due to the retention volume of the wet pond,often there is not a discharge from the wet pond even if a
qualified storm event occurs. Part of the wet pond function is a slow release of the stormwater runoff collected from the site.
It rained on December 17,2023 and the rainfall was approximately 2.75 inches. During this rain event,the amount of runoff from the drainage area into the onsite wet pond is
approximately 46,708 ft3(equivalent to 349,377 gallons). The new stormwater discharge runoff was combined with the stormwater already present in the wet pond. Some of the
stormwater collected in the wet pond was discharged via the drawdown orifice of the riser structure and the wet pond 18"HDPE outlet/effluent pipe(Outfall 001). There is not a flow
measurement device in the wet pond overflow structure nor at the outfall, Thus the actual discharge rate was not measured nor able to be estimated.
EPA Farm 3510-2F Paae 13

ATTACHMENT TO EPA FORM 2F
SITE DRAINAGE MAP

•�"� ' � .,.-_ - - —�"``i', � yeot�a--owc-1-1= I may'^ ce:Kwr--rr re_I�;a,l r
—
�
I
OUTFAI�001
NOTES:
Outfa11001:
Lat: 360 5'30.36„
1i3 ,,,,. Long: 7901 T 57.42"
• � I I I 1
Drainage area for
Outfall 001:6.07 acres
Ar
��,gym.nr.ac ec.�M - ►: � r'- �.
Source : Figure 2 SITE DRAINAGE MAP
Site Construction Grading &Drainage Plan : C.60098-DWG-1-1-0004 Airgas USA, LLC
2025 Development Center Drive, Mebane, NC 27302

SUPPLEMENTAL INFORMATION REQUIRED FOR RENEWAL OF INDIVIDUAL NPDES
STORMWATER PERMIT

SUPPLEMENTAL INFORMATION REQUIRED FOR RENEWAL OF INDIVIDUAL
NPDES STORMWATER PERMIT
Two copies of each of the following shall accompany this submittal in order for the application
to be considered complete:
(Do not submit the site Stormwater Pollution Prevention Plan)
Initials
TS 1. A current Site Map from the Stormwater Pollution Prevention Plan. The location of
industrial activities(including storage of materials,disposal areas,process areas and
loading and unloading areas),drainage structures,drainage areas for each outfall,
building locations and impervious surfaces should be clearly noted.
TS 2. A summary of Analytical Monitoring results during the term of the existing permit
(if your permit required analytical sampling). Do not submit individual lab reports.
The summary can consist of a table including such items as outfall number,
parameters sampled,lab results, date sampled,and storm event data.
TS 3. A summary of the Visual Monitoring results. Do not submit individual monitoring
reports.The summary can consist of a table including such items as outfall number,
parameters surveyed,observations,and date monitoring conducted.
TS 4. A summary of the Best Management Practices utilized at the permitted facility.
Summary should consist of a short narrative description of each BMP's in place at
the facility. If the implementation of any BMP's is planned,please include
information on these BMP's.
TS 5. A short narrative describing any significant changes in industrial activities at the
permitted facility. Significant changes could include the addition or deletion of
work processes,changes in material handling practices,changes in material storage
practices,and/or changes in the raw materials used by the facility.
TS 6. Certification of the development and implementation of a Stormwater Pollution
Prevention Plan for the permitted facility(Sign and return attached form).
If the final year analytical monitoring of the existing permit term has not been completed
prior to filing the renewal submittal,then the last years monitoring results should be submitted
within 30 days of receipt of the laboratory reports. (i.e. do not withhold renewal submittal
waiting on lab results)

SUPPLEMENTAL INFORMATION REQUIRED FOR RENEWAL OF INDIVIDUAL NPDES
STORMWATER PERMIT(No. NCS000598)
Airgas USA LLC-Mebane ASU
2025 Development Center Drive
Mebane, Alamance County, NC 27302
1. Current Site Map from the Stormwater Pollution Prevention Plan
See attached.
2. A Summary of Analytical Monitoring Results during the Term of the Existing Permit
Airgas USA LLC -Mebane ASU was under the final phase of the construction when the current NPDES
Permit (No.NCS000598)was issued in September 2019. The NPDES Permit requires that the analytical
monitoring be conducted semi-annually during Period 1 from January 1 through June 30 and during
Period 2 from July 1 through December 31 and that the first analytical monitoring period begin from
Period 1 in 2020. There is one stormwater discharge outfall designated as Outfall 001 at the facility.
The available analytical monitoring results during the current permit period are summarized below.
Parameters( Anal tical�viomtarin )Zesults at Outfall R01
Disc WW Benchmark 2020 2022, - 2023
Charaetertics Values - Penod 2 Penod 1 Period 2 Peio 1 Period 2
,.. .
- (11/12/20 :0) (3IQ9/2022 (].Q/OI/2022} (6/23/2023� (12/18/202..
Oil&Grease 15mg/I <5.0m 1 <15m <15mg/I <4.9m 1 <4.9mg/I
COD 120 mg/l <25 mg/1 26.2 mg/I <25 mg/I <25 mg/I <25 mg/l
TSS 100 m 1 18.9m 1 66.5m 1 9.5m 1 17.4m 14.2m 1
Total N/A <0.05 mg/1 0.14 mg/l 0.06 mg/l <0.05 mg/I 0.061 mg/I
Phosphorus
Total Nitrogen N/A <0.52 mg/I 0.73 mg/1 0.41 mg/1 1.00 mg/1 <0.349
mg/I
H 6-9 s.u. 6.6 s.u. 7.1 s.u. 7.3 s.u. 6.6 m 6.1 s.u.
Total Rainfall - 3.3 inches 2.4 inches 2.5 inches 2.5 inches 2.75 inches
New Motor Oil -- <55 gallons <55 gallons <55 gallons <55 gallons <55 gallons
Usage
It is noted that there were certain periods (Period 1 in 2020 and Periods 1 and 2 in 2021) when the
analytical monitoring was not able to be conducted during the current permit period.
Although the startup of the facility occurred in February 2020, the site continued to be under the final
phase of construction and the stormwater discharge from the site continued to be under the construction
permit for a period due to the ongoing construction activities including those in the wet pond. The final
inspection under the NPDES Permit for Construction Activities was conducted in early June 2020 and the
final inspection report that served as the Notice of Termination (NOT) of the NPDES Permit for
Construction Activities was issued on June 5, 2020. Thus, the facility was not able to begin conducting
the actual stormwater sampling under the current NPDES Permit during Period 1 in 2020 but it began
from Period 2 in 2020.
Page 1 of 4

Stormwater runoff from the industrial activity areas at the facility is collected in the onsite wet pond with
the design capacity of approximately 112,270 ft3. Due to the design, the stormwater discharge occurs at
Outfall 001 (the wet pond 18" HDPE outlet/effluent pipe) when the water level in the wet pond reaches
the drawdown orifice of the riser structure. This drawdown orifice is 9 feet above the bottom of the wet
pond. Due to the retention volume of the wet pond,often there is not a discharge from the wet pond even
if a qualified storm event occurs. In addition, it was discovered that during a good portion of 2021, the
riser structure in the wet pond leaked and Airgas investigated and corrected the identified leakage issue.
For this reason,the analytical monitoring was not conducted during Periods 1 and 2 in 2021.
It is noted that the analytical monitoring required in 2024 has not been conducted at the time of the
NPDES Permit renewal application preparation.
In accordance with the available analytical monitoring results above,the stormwater disdischarge did not
exceed the benchmark values.
3. A Summary of Visual (Qualitative) Monitoring Results
The NPDES Permit requires that the visual monitoring be conducted semi-annually during Period 1 from
January 1 through June 30 and during Period 2 from July 1 through December 31. As discussed in
Section 2 above, due to the construction completion progress in 2020 and due to the design and leakage
issue of the onsite wet pond,there were not discharges during Period 1 in 2020 and during Periods 1 and
2 in 2021 during the current NPDES Permit period. The available visual monitoring results are
summarized below.
Visual:IvIonitorin :Rest-its at Qdtfa11..001.: .
Discharge Characteristics 2020 2022 2022 2, 23 2023
Period'2 Pefiod l Reriod 2'` Period 1 Pezxod2
- = -
11X1212020 3109j2022 1OX01/2022 6/23%20.23; � X2/18/2023
Color Clear Clear Clear Clear Clear
Odor None None None None None
Clarity Clear Clear Clear Clear Clear
Floating Solids Absent Absent Absent Absent Absent
Suspended Solids Absent Absent Absent Absent Absent
Foam Absent Absent Absent Absent Absent
Oil Sheen None None None None None
Erosion or deposition at the None None None None None
outfall
Other obvious indicators of None None None None None
stormwater pollution
It is noted that the visual monitoring required in 2024 has not been conducted at the time of the NPDES
Permit renewal application preparation.
In accordance with the visual monitoring results above, no issues are identified and it is determined that
the SWPPP is effective as written and no additional control measures/best management practices are
needed.
Page 2 of 4

4. A Summary of Best Management Practices
Stormwater Control Measures (SCMs) and structural and non-structural Best Management Practices
(BMPs)employed at the facility are identified in the SWPPP and presented below.
Structural and Noz1 Descnptton o Activities
Wet pond • All stormwater runoff associated with industrial activities at the
facility is collected in the wet pond.
• The wet pond effluent is discharged into the nearby receiving water in
a controlled manner.
a The runoff flow and certain pollutants associated with settleable
articles are controlled.
Secondary containment • Oil-filled equipment subject to SPCC rules are provided with
secondary containment;
• Oil storage tanks are provided with secondary containment;
• Water treatment chemical storage containers are provided with
secondary containment;and
• All oil drums are placed on the secondary containment pallets.
• The rain water collected in a dike for the transformer is checked and
released only when no oil sheen is observed.
• DEF storage container is a double-walled tank and is provided with the
"gun"operations with a drip pan.
• DEF drips received in the drip pan are collected in a separate container
for offsite disposal or for reuse.
Minimize exposure • All compressors with the oil reservoirs are located in the compressor
building.
a All oil drums are stored indoors.
• All chemicals are stored inside buildings or shelter.
• Truck maintenance activities take place indoors in the maintenance
shop.
• Dum ster cover remains closed when not in use.
Good housekeeping • All tanks are properly labeled;
• Locate tanks away from areas of heavy traffic;
• Maintain up-to-date material inventory;
a Arrange for regular trash pickup;
• Train staff in basic cleanup procedures;and
• Encourage proper material storage techniques.
Preventive maintenance • Quarterly inspection of all structures,storage tanks,catch basins,and
equipment;and
• Proper upkeep of tanks,piping and equipment
Spill prevention and • Maintain spill response kits for each plant and restock as necessary,as
response specified in the facility SPCC plan.
Visual site inspections • Quarterly facility inspections; and
and evaluation • Semi-annual visual observations of discharges
Erosion and sediment • Stabilization of the site with gravel,stones or vegetation as needed;
controls and
• Silt fence,where needed.
Page 3 of 4

Note:
(1) Additional BMPs related to oil storage are discussed within the facility's Spill Prevention,
Control,and Countermeasure(SPCC)Plan.
5. A Short Narrative Describing Any Significant Changes in Industrial Activities
Since the completion of the facility construction in 2020,the facility operations largely remained the same
during the current NPDES Permit period. The only change is an addition of Diesel Exhaust Fuel (DEF)
operations at the facility. A DEF tote is stored outdoors and the transport truck drivers add/pump DEF
into the diesel fuel tank in their trucks.Proper SCMs/BMPs are employed for this operation.
6. Certification of the Development and Implementation of a SWPPP
See attached.
Page 4of4

ATTACHMENTS TO
SUPPLEMENTAL INFORMATION REQUIRED FOR RENEWAL OF INDIVIDUAL NPDES
STORMWATER PERMIT
• Current Site Map(Site Plan)from the Stormwater Pollution Prevention Plan
• Stormwater Pollution Prevention Development and Implementation Certification

SITE PLAN [Revised November 20221
" — " — . — . — . — . _ . ... —�
LEGEND: � • Pond
• — App.Property Line I
• • - App.Fence Line
General Runoff Direction I
• Oil Storage
8 Spill Kit I
---- Storm Sewer Line �• Grass
® Storm Sewer Inlet / I
Approximate drainage area
for Wet Pond — . . — . . — . . — . . — . . . . — . . — . . — . . — . .
/ Grass I
Tinnis Creek / Wet Acce
Pond 1 ; Truck Road
[ Parking Gravel I
Truck Argon tank
Outfall 001 e I
Lat:36'05'29"N 1 Scal O O Cold Box
Long:79'17"57'VV O 0
Grass �J I
Cryogenic
rGas Tanks t7
f � • � r ; ompressor Bld ■ 0 I'
Substation r ■ ©nsfo er +� Coding
(owned by Duke ' ❑ Tojver
Grass Energy) O O I
Gravel ' Car
Office/ ;Car
. • _ • i Parking Control Rm parking
1 _ _
Car Parking
Asphalt Water Treil.
Note: • � • � • . ■ Maintenance Sldg
1. Not to scale • Asphalt Shop
2. Total property area:11.68 acres `. DEF Operations
3. Outfall 001 drainage area: App.6.07 acres according to the design
4. Total impervious area:App.4.11 acres,67,71%of the Outfall 001
drainage area ` Access Road
5. Receiving water: Tinnis Creek,a tributary of Moadams Creek,
Class WS-V;NSW,Cape Fear River Basin Gate
6. The receiving water is reportedly impaired but a TMDL has not
been established. .

STORMWATER POLLUTION PREVENTION PLAN
DEVELOPMENT AND IMPLEMENTATION
CERTIFICATION
North Carolina Division of Energy, Mineral, and Land Resources— Stormwater Program
Facility Name: Alrgas USA LLC
Permit Number: NCS000598
Location Address: 2025 Development Center Drive
Mebane,NC 27302
County: Alamance
"I certify, under penalty of law, that the Stormwater Pollution Prevention Plan (SPPP) document and all
attachments were developed and implemented under my direction or supervision in accordance with a system
designed to assure that qualified personnel properly gather and evaluate the information required by the SPPP.
Based on my inquiry of the person or persons who manage the system, or those persons directly responsible
for gathering the information, the information gathered is, to the best of my knowledge and belief, true,
accurate and complete."
And
"I certify that the SPPP has been developed, signed and retained at the named facility location, and the SPPP
has been fully implemented at this facility location in accordance with the terms and conditions of the
stormwater discharge permit."
And
"I am aware that there are significant penalties for falsifying information, including the possibility of fines and
imprisonment for knowing violations."
Sign (according to permit signatory requirements) and return this Certification. DO NOT
SEND STORMWATER POLLUTION PREVENTION PLAN WITH THIS CERTIFICATION.
Signature Date
Thomas Stringer Vice Presldent,Production&Project Execution
Print or type name of person signing above Title
SPPP Certification 10/13

SUPPLEMENTAL INFORMATION REQUIRED FOR RENEWAL OF INDIVIDUAL NPDES
STORMWATER PERMIT

SUPPLEMENTAL INFORMATION REQUIRED FOR RENEWAL OF INDIVIDUAL
NPDES STORMWATER PERMIT
Two copies of each of the following shall accompany this submittal in order for the application
to be considered complete:
(Do not submit the site Stormwater Pollution Prevention Plan)
Initials
TS 1. A current Site Map from the Stormwater Pollution Prevention Plan. The location of
industrial activities(including storage of materials,disposal areas,process areas and
loading and unloading areas), drainage structures,drainage areas for each outfall,
building locations and impervious surfaces should be clearly noted.
TS 2. A summary of Analytical Monitoring results during the term of the existing permit
(if your permit required analytical sampling). Do not submit individual lab reports.
The summary can consist of a table including such items as outfall number,
parameters sampled, lab results, date sampled,and storm event data.
TS 3. A summary of the Visual Monitoring results. Do not submit individual monitoring
reports.The summary can consist of a table including such items as outfall number,
parameters surveyed,observations,and date monitoring conducted.
TS 4. A summary of the Best Management Practices utilized at the permitted facility.
Summary should consist of a short narrative description of each BMP's in place at
the facility. If the implementation of any BMP's is planned,please include
information on these BMP's.
TS 5. A short narrative describing any significant changes in industrial activities at the
permitted facility. Significant changes could include the addition or deletion of
work processes,changes in material handling practices,changes in material storage
practices,and/or changes in the raw materials used by the facility.
TS 6. Certification of the development and implementation of a Stormwater Pollution
Prevention Plan for the permitted facility(Sign and return attached form).
If the final year analytical monitoring of the existing permit term has not been completed
prior to filing the renewal submittal,then the last years monitoring results should be submitted
within 30 days of receipt of the laboratory reports. (i.e. do not withhold renewal submittal
waiting on lab results)

SUPPLEMENTAL INFORMATION REQUIRED FOR RENEWAL OF INDIVIDUAL NPDES
STORMWATER PERMIT(No. NCS000598)
Airgas USA LLC-Mebane ASU
2025 Development Center Drive
Mebane,Alamance County, NC 27302
1. Current Site Map from the Stormwater Pollution Prevention Plan
See attached.
2. A Summary of Analytical Monitoring Results during the Term of the Existing Permit
Airgas USA LLC- Mebane ASU was under the final phase of the construction when the current NPDES
Permit(No.NCS000598)was issued in September 2019. The NPDES Permit requires that the analytical
monitoring be conducted semi-annually during Period 1 from January I through June 30 and during
Period 2 from July 1 through December 31 and that the first analytical monitoring period begin from
Period l in 2020. There is one stormwater discharge outfall designated as Outfall 001 at the facility.
The available analytical monitoring results during the current permit period are summarized below.
." i ".� vc S a'5 :.a� ''��.
s s ,ge}s i �Bll n h tar �4 0 "n 2M. a r
AMON
(Ij1 �: 3`A ` ss( i 2�4 =
Oil &Grease 15 mg/I <5.0 mg/I <15 mg/l <15 mg/I <4.9 mg/l.._ <4.9 mg/I
COD 120 m <25 mg/I 26.2 m <25 mg/I <25 m l <25 mg/l
TSS 100 m 1 19.9 mgtl 66.5m 1 9.5m 1 17.4m 14.2m 1
Total N/A <0.05 mg/I 0.14 mg/I 0.06 mg/I <0.05 mg/1 0.061 mg/l
Phosphorus
Total Nitrogen N/A <0.52 mg/I 0.73 mg/l 0.41 mg/1 1.00 mg/1 <0.349
mg/I
H 6-9 s.u. 6.6 s.u. 7.1 s.u. 7.3 s.u. 6.6 mg/l 6.1 s.u.
Total Rainfall 3.3 inches 2.4 inches 2.5 inches 2.5 inches 2.75 inches
New Motor Oil - <55 gallons <55 gallons <55 gallons <55 gallons <55 gallons
Usage
It is noted that there were certain periods (Period 1 in 2020 and Periods 1 and 2 in 2021) when the
analytical monitoring was not able to be conducted during the current permit period.
Although the startup of the facility occurred in February 2020, the site continued to be under the final
phase of construction and the stormwater discharge from the site continued to be under the construction
permit for a period due to the ongoing construction activities including those in the wet pond. The final
inspection under the NPDES Permit for Construction Activities was conducted in early June 2020 and the
final inspection report that served as the Notice of Termination (NOT) of the NPDES Permit for
Construction Activities was issued on June 5, 2020. Thus,the facility was not able to begin conducting
the actual stormwater sampling under the current NPDES Permit during Period 1 in 2020 but it began
from Period 2 in 2020.
Page 1 of 4

Stormwater runoff from the industrial activity areas at the facility is collected in the onsite wet pond with
the design capacity of approximately 112,270 ft3. Due to the design, the stormwater discharge occurs at
Outfall 001 (the wet pond 18"HDPE outlet/effluent pipe) when the water level in the wet pond reaches
the drawdown orifice of the riser structure. This drawdown orifice is 9 feet above the bottom of the wet
pond. Due to the retention volume of the wet pond, often there is not a discharge from the wet pond even
if a qualified storm event occurs. In addition, it was discovered that during a good portion of 2021,the
riser structure in the wet pond leaked and Airgas investigated and corrected the identified leakage issue.
For this reason,the analytical monitoring was not conducted during Periods 1 and 2 in 2021.
It is noted that the analytical monitoring required in 2024 has not been conducted at the time of the
NPDES Permit renewal application preparation.
In accordance with the available analytical monitoring results above,the stormwater disdischarge did not
exceed the benchmark values.
3. A Summary of Visual (Qualitative) Monitoring Results
The NPDES Permit requires that the visual monitoring be conducted semi-annually during Period 1 from
January I through June 30 and during Period 2 from July 1 through December 31. As discussed in
Section 2 above, due to the construction completion progress in 2020 and due to the design and leakage
issue of the onsite wet pond,there were not discharges during Period I in 2020 and during Periods I and
2 in 2021 during the current NPDES Permit period. The available visual monitoring results are
summarized below.
- `` .�: Y�sual,lv�eztitQri,� ;,It:�su]ts_�at�Ori�f�IltQQl..,, '
Dis6harge. es
' e`r per 7 � eo ��no"1A.
'erid�
111�112420 3U91422 1QQ1'122 i 61202 1' 18J2{123=
Color Clear Clear Clear Clear Clear
Odor None None None None None
Clarity Clear Clear Clear Clear Clear
Floating Solids Absent Absent Absent Absent Absent
Suspended Solids Absent Absent Absent Absent Absent
Foam Absent Absent Absent Absent Absent
Oil Sheen None None None None None
Erosion or deposition at the None None None None None
outfall
Other obvious indicators of None None None None None
stormwater pollution
It is noted that the visual monitoring required in 2024 has not been conducted at the time of the NPDES
Permit renewal application preparation.
In accordance with the visual monitoring results above, no issues are identified and it is determined that
the SWPPP is effective as written and no additional control measures/best management practices are
needed.
Page 2 of 4

4. A Summary of Best Management Practices
Stormwater Control Measures (SCMs) and structural and non-structural Best Management Practices
(BMPs)employed at the facility are identified in the SWPPP and presented below.
es--
-Sw f4wommmk.
Wet pond * All stormwater runoff associated with industrial activities at the
facility is collected in the wet pond.
0 The wet pond effluent is discharged into the nearby receiving water in
a controlled manner.
e The runoff flow and certain pollutants associated with settleable
particles are controlled.
Secondary containment * Oil-filled equipment subject to SPCC rules are provided with
secondary containment;
a Oil storage tanks are provided with secondary containment;
0 Water treatment chemical storage containers are provided with
secondary containment; and
a All oil drums are placed on the secondary containment pallets.
0 The rain water collected in a dike for the transformer is checked and
released only when no oil sheen is observed.
* DEF storage container is a double-walled tank and is provided with the
"gun"operations with a drip pan.
0 DEF drips received in the drip pan are collected in a separate container
for offsite disposal or for reuse.
Minimize exposure 9 All compressors with the oil reservoirs are located in the compressor
building.
* All oil drums are stored indoors.
* All chemicals are stored inside buildings or shelter.
a Truck maintenance activities take place indoors in the maintenance
shop.
0 Dunipster cover remains closed when not in use.
Good housekeeping 6 All tanks are properly labeled;
* Locate tanks away from areas of heavy traffic;
9 Maintain up-to-date material inventory;
* Arrange for regular trash pickup;
0 Train staff in basic cleanup procedures;and
0 Encourage proper material storage techniques.
Preventive maintenance * Quarterly inspection of all structures,storage tanks,catch basins,and
equipment;and
9 Proper upkeep of tanks,piping and equipment
Spill prevention and 0 Maintain spill response kits for each plant and restock as necessary,as
response specified in the facility SPCC plan.
Visual site inspections 0 Quarterly facility inspections; and
and evaluation 0 Semi-annual visual observations of discharges
Erosion and sediment * Stabilization of the site with gravel,stones or vegetation as needed;
controls and
* Silt fence,where needed.
Page 3 of 4

Note:
(1) Additional BMPs related to oil storage are discussed within the facility's Spill Prevention,
Control, and Countermeasure(SPCC)Plan.
6. A Short Narrative Describing Any Significant Changes in Industrial Activities
Since the completion of the facility construction in 2020,the facility operations largely remained the same
during the current NPDES Permit period. The only change is an addition of Diesel Exhaust Fuel(DEF)
operations at the facility. A DEF tote is stored outdoors and the transport truck drivers add/pump DEF
into the diesel fuel tank in their trucks.Proper SCMsBMPs are employed for this operation.
6. Certification of the Development and Implementation of a SWPPP
See attached.
Page 4 of 4
I

ATTACHMENTS TO
SUPPLEMENTAL INFORMATION REQUIRED FOR RENEWAL OF INDIVIDUAL NPDES
STORMWATER PERMIT
• Current Site Map(Site Plan)from the Stormwater Pollution Prevention Plan
• Stormwater Pollution Prevention Development and Implementation Certification

SITE PLAN [Revised November 2022]
LEGEND' �' 1 Pond
APR.Property Line e
App.Fence Line
~- General Runoff Direction
• Oil Storage
6 Spill Kit �. I
----- Storm Sewer Line
® Storm Sewer Inlet /� Grass
Approximate drainage area /� I
for Wet Pond . . . _ . .
Grass I
Tinnis Creek / Wet i Acce
o Pond i Truck Road.
Parking Gravel I
'Outfall
Truck Argon lank
� � e I
Lai:36°45'29"N 1 � Scal Cold eoO 0 ❑
Long:79'17"57'W O O
Grass Cryogenic I
Gas Tanks
ompressor Bid ■ �
Substation •! ■ f nsforr er Cojing
/ Grass (Owned by Duke ' ❑ l>r O To+fer
Energy) ; 0 I
_ Gravel ag rkin Office/ I
. , Control Rm parking
• ' ' WaterTre L.
Car Parking Asphalt'
Note: � , � • -- �� ■]Shop
Maintenance Bldg
1. Not to scale Asphalt
2. Total property area:11.68 acres ` . -- DE1=Operations f
3. Outfall 001 drainage area: App.6.07 acres according to the design J
4. Total impervious area:App.4.11 acres,67.71%of the Outfall 001 .
drainage area Access Road -"
5. Receiving water: Tinnis Creek,a tributary of Moadams Creek, .
Class WS-V;NSW,Cape Fear River Basin 1 . ` _ Gate
6. The receiving water is reportedly impaired but a TMDL has not
been established.

STORMWATER POLLUTION PREVENTION PLAN
DEVELOPMENT AND IMPLEMENTATION
CERTIFICATION
North Carolina Division of Energy, Mineral, and Land Resources—Stormwater Program
Facility Name: Airgas USA LLC
Permit Number: NCS000598
Location Address: 2025Deveiopment Center Drive
Mebane.NC 27302
County:
Alamarxxi
"I certify, under penalty of law, that the Stormwater Pollution Prevention Plan (SPPP) document and all
attachments were developed and implemented under my direction or supervision in accordance with a system
designed to assure that qualified personnel properly gather and evaluate the information required by the SPPP.
Based on my inquiry of the person or persons who manage the system, or those persons directly responsible
for gathering the information, the information gathered is, to the best of my knowledge and belief, true,
accurate and complete."
And
"I certify that the SPPP has been developed, signed and retained at the named facility location, and the SPPP
has been fully implemented at this facility location in accordance with the terms and conditions of the
stormwater discharge permit."
And
"I am aware that there are significant penalties for falsifying information, including the possibility of fines and
imprisonment for knowing violations."
Sign (according to permit signatory requirements) and return this Certification. DO NOT
SEND STORMWATER POLLUTION PREVENTION PLAN WITH THIS CERTIFICATION.
Signature Date ylzv�0.2-s
Thomas Stringer Vice President.Production&Project Executian
Print or type name of person signing above Title
SPPP Certification 10/13