NC0004308_More Information (Received - treatment pilot study)_20240805

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[External] RE: NC0004308_Alcoa_Pilot Study
Mibroda, Jason <[e-mail]>
Thu 8/1/20244:40 PM
To:Dowden, Doug <[e-mail]>
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Doug,
The last update was provided at the end of May. We are now at a point where sufficient information has been collected to
provide a meaningful update. We will work to submit an update letter later this month, sticking to quarterly progress
reporting unless another frequency is desired.
In general, BBP continues to see favorable compliance results associated with the low Outfall 005 discharge rates
observed during the summer months. Modifications have been made to the system to increase efficiency and reliability.
Details of the modifications will be included in the update letter.
Give me a call if there are any specific questions I can answer for you prior to receiving the letter.
Jason Mibroda, PE
Alcoa Corporation I Remediation Manager
[phone] (0) [phone] (M)
From: Dowden, Doug <[e-mail]>
Sent: Thursday, August 1, 2024 9:57 AM
To: Mibroda, Jason <Jason.Mibroda @alcoa.com>
Subject: EXT: NC0004308_Alcoa_Pilot Study
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Good Morning Jason,
Thought that I would touch base with you and inquire into the status of the Pilot Treatability Study and potential results?
Please let me know where we are at, next steps and estimated timeline for all?
Thanks much,
Sincerely,
Douglas Dowden
Environmental Program Supervisor II
Division of Water Resources / Permitting
Department of Environmental Quality
Office: Archdale Building, 9th Floor (925Q)
512 North Salisbury Street, Raleigh, NC 27604
Mailing Address: 1617 Mail Service Center, Raleigh, NC 27699-1617
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Badin Business Park LLC
201 Isabella Street
Suite 500
Pittsburgh, PA 15212-5858 USA
Tel: [phone]
May 24, 2024
Bob Sledge
Environmental Specialist II
Division of Water Resources,
Water Quality Permitting Section — NPDES
1611 Mail Service Center
Raleigh, NC 27699-1611 Submitted via email: [e-mail]
RE: Response to Request for Additional Information - Treatment Pilot Study
Badin Business Park, LLC
Dear Mr. Sledge:
Badin Business Park, LLC provides this update as requested by the May 8, 2024, North Carolina
Department of Environmental Quality (DEQ), Water Quality Permitting Section email regarding
the treatment pilot study for the reduction of fluoride concentrations at Badin Business Park
Outfall 005. Each specific request for information is listed with a response to follow.
Request 1— Include a description of the treatment system installed, including its location(s)
within the conveyance.
Response 1: Since September 2023, the use of activated alumina has been tested to passively
treat water discharged at Outfall 005. The use of activated alumina was introduced in a virtual
meeting with DEQ in early 2023 and subsequent correspondences dated August 31, 2023, and
September 12, 2023.
The assessment commenced on September 6, 2023, with the placement of 12 woven,
monofilament filtration geotextile bags containing approximately 50-60 pounds of activated
alumina each. The bags were placed directly in the storm sewer, in areas with storm water of
known elevated fluoride concentrations and secured with ropes tethered to the surface. More
specifically, 4 bags were placed in storm sewer utility access number 2.200, 3 bags in access
number 2.210, and 5 bags in access number 2.310. Each of these locations are illustrated on
Figure 1, attached. Flows in the sewer were observed to be very low or non-existent as a result
of the dry conditions experienced in Badin during the months following installation. In attempt
to improve system performance during the dry conditions all bags were relocated to access 2.310
on November 6th to create a dam like feature; thereby, increasing the potential surface area
interface and media contact time.
The initial stage of the pilot program was simplistic in design and application and utilized to
promptly employ a known and proven treatment process (i.e., use of activated alumina) while a
more complex system was designed and constructed. In April 2024, an ex -situ treatment
approach was installed where the fluoride -bearing water is pumped from the storm sewer to the
surface and processed through a media adsorption bed. This method supports a more direct

Mr. Bob Sledge
May 24, 2024
Page 2
assessment of performance as well as improved potential for fluoride reduction through
increased contact.
The ex -situ system presently extracts stormwater from storm sewer utility access number 2.200
via a solar -powered, surface -mounted pump with an operating range between 3 and 18 gallons
per minute (gpm). Water is being pumped directly from the storm sewer while awaiting the
construction of two pumping sumps within the storm sewer near access 2.100. A delay in the
sump construction was due to qualified contractor scheduling constraints. The extracted water is
processed through a baffled four -chamber filter box, approximately 4 ft wide x 8 ft long x 3.5 ft
deep. Each chamber is loaded with approximately 2 ft of activated alumina. The system effluent
is discharged to sewer access number 2.100.
A few structural and operational modifications were completed following initial installation to
avoid short circuiting of the baffles and treatment media. The ex -situ system began operating on
April 30, 2024, at a flow rate of approximately 5 gpm.
DEQ Comment 2 — A list of results to date from the analytical testinz performed for the
treatment pilot study.
Response 2: A summary of the analytical testing results performed for the treatment pilot study
are presented to follow in Table Response 2. In general, no discernable trend has developed from
the information gathered to assess the performance of the in -situ pilot treatment. Multiple
changes in the sample locations identified in the Table were employed as a result of the dry
conditions observed in the storm sewer during the monitoring period. Some of these locations are
upstream of plugs installed in 2018 as part of the shallow storm sewer modifications which
further complicated performance assessment.
Two sets of samples have been collected following the initiation of the ex -situ system with the
first preliminary results received coinciding with the writing of this letter. Although it is
premature to formulate conclusions, the preliminary data shows a reduction in the fluoride
concentration across the treatment system with an Outfall 005 fluoride concentration of 1.4 mg/L
(May 2nd grab sample). Samples will continue to be collected to assess the ex -situ system
performance approximately every other week. Presently the system is only being monitored for
fluoride and pH. Modifications to the monitoring plans may be employed.
Table Response 2 — In -Situ Monitoring Results
Upstream
Downstream
Date
Access
pH
Fluoride
(mg/L)
Access
pH
Fluoride
(mg/L)
Access
pH
Fluoride
(mg/L)
9/13/2023
2.330
3.1
2.000
3.7
9/22/2023
2.330
2.6
2.000
3.5
9/27/2023
2.330
2.6
2.000
3.3

Mr. Bob Sledge
May 24, 2024
Page 3
Upstream
Downstream
Date
Access
pH
Fluoride
(mg/L)
Access
pH
Fluoride
(mg/L)
Access
pH
Fluoride
(mg/L)
10/4/2023
2.330
2.9
2.200
3.4
10/11/2023
2.330
3.0
2.200
3.4
10/25/2023
2.330
4.7
2.200
3.1
11/8/2023
2.330
2.7
2.200
2.6
11/22/2023
2.330
2.8
2.100
2.8
12/6/2023
2.330
1.8
2.000
2.5
12/19/2023
2.330
2.3
2.100
2.6
1/3/2024
2.330
7.14
2.4
2.100
7.24
2.6
1/17/2024
2.330
6.81
2.3
2.100
7.1
2.5
2/1/2024
2.330
6.65
2.2
2.100
6.98
2.8
2/8/2024
2.100
7.04
2.5
2.05
6.87
1.9
2/14/2024
2.330
6.57
2.3
2.100
6.86
3.4
2/28/2024
2.330
7.34
2.6
2.100
7.59
2.6
2.05
7.09
2.1
3/13/2024
2.330
6.93
2.7
2.100
7.21
2.9
2.05
7.08
2.4
3/26/2024
2.330
6.96
2.8
2.100
7.17
2.6
2.05
7.08
2.2
4/2/2024
2.330
6.87
2.5
2.100
7.24
<1
2.05
7.06
2.2
4/17/2024
2.330
6.92
2.3
2.000
7.05
2.9
2.05
6.92
2.0
5/2/2024
2.330
7.50
2.5
2.000
7.44
<1.0
2.05
6.85
1.6
DEO Comment 3 - A preliminary evaluation of the effectiveness of the treatment system and
its prospects for achieving consistent compliance with permit limits for fluoride at Outfall 005.
Response 3: The in -situ treatment has been in place since September 2023 with modifications
conducted in November. No discernable trend has developed from the information gathered to
assess the performance of the in -situ pilot treatment. However, since November 2023, the
NPDES Outfall 005 has met the monthly average permit limit of 1.8 mg/L.
Insufficient information has been obtained to date to formulate an educated opinion on the
effectiveness of the ex -situ treatment system followings its initiation on April 30, 2024.
DEO Comment 4 - A statement regarding current plans and next steps proposed to ensure
compliance with permit limits at Outfall 005, including a timeline for their implementation.
Response 4: The site has been compliant with NPDES Outfall 005 permit limits since November
2023. Operation of the pilot treatment system is planned to continue throughout 2024. At present
the in -situ treatment system remains in place but may be removed upon further assessment of the
ex -situ treatment effectiveness. Operation of the ex -situ system will continue to be monitored to
assess both short and long-term viability. Installation of the collection sumps are scheduled for
June and a redundant system is being considered taking into account design modifications

Mr. Bob Sledge
May 24, 2024
Page 4
identified from the initiation of the existing system. Ultimately, the pilot treatment assessment on
the Outfall 005 storm sewers will be used to inform a final remedy proposal.
If you have any questions or need additional information, please do not hesitate to contact me at
Robyn. Grosskalcoa. com or 412.315.2780.
Sincerely,
Robyn L. Gross
Global Director, Alcoa Transformation
Badin Business Park LLC
cc: Julie Grzyb, NCDEQ
John Hennessy, NCDEQ
Andrew Moore, NCDEQ
Brandy Costner, NCDEQ
Roberto Scheller, NCDEQ
Wes Bell, NCDEQ
Jason Mibroda, Alcoa Corporation

Mr. Bob Sledge
May 24, 2024
Page 5
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Badin Business Park LLC
201 Isabella Street
Suite 500
Pittsburgh, PA 15212-5858 USA
Tel: [phone]
August 31, 2023
Michael Montebello
Division of Water Resources
Water Quality Permitting Section - NPDES
1617 Mail Service Center
Raleigh, NC 27699-1617
Re: Notice of Intent to Commence Pilot Treatment Assessment
Badin Business Park LLC, Badin, NC
NPDES Permit No. NC0004308
Dear Mr. Montebello,
Badin Business Park LLC (BBP) is in receipt of the Division of Water Resources (DWR)
NPDES permitting section's June 14, 2023, letter (Letter) regarding the recent Treatability
Presentation. In accordance with the Letter, BBP is providing this notice of intent to begin
field testing the use of activated alumina to treat water discharged at Outfall 005. Further,
BBP interprets the Letter that DWR considers the proposed field pilot testing to be acceptable
activity under BBP's current permit (NC0004308) and does not require a permit modification.
The field testing will begin immediately as the activated alumina is onsite, and support
materials are readily available for purchase.
BBP intends to pilot the use of activated alumina as discussed in the December 16, 2022,
Focused Treatability Study Work Plan (Work Plan) with a revised approach. In lieu of
pumping fluoride -bearing water into a treatment system, the activated alumina will be
installed in the Outfall 005 storm sewer for direct contact with the effluent. This will provide
an initial assessment of treatment performance. Modifications may be proposed and
communicated to DWR following the initial assessment.
This field trial is being conducted as a presumptive treatment remedy while the Treatability
Study, as presented in the Work Plan, progresses. Presently, vendors are evaluating site
specific water quality information in review of various treatment technologies; completion of
the Treatability Study is expected later in 2023.
Activated alumina, a form of aluminum oxide, was selected for the pilot based on experience
with its use for the treatment of process water and stormwater at active aluminum smelting

Notice of Intent — Badin Business Park
August 31, 2023
Page 2
sites. Further, it is commonly used in municipal and industrial water filtration applications and
is very stable; it will bond with other substances without changing its own chemistry or form.
Should you have questions, please contact me at 412.389.1768 or Robyn. Gros s(c�r�,alcoa.com.
Sincerely,
Robyn L. Gross
Director, Asset Management Americas
Badin Business Park LLC
ec: Jason Mibroda, Alcoa Corporation
Amir Adaryani, PhD, NCDEQ
Doug Dowden, NCDEQ
John Hennessey, NCDEQ
Julie Grzyb, NCDEQ
Richard Rogers, NCDEQ
Anna Gurney, NCDEQ
Andrew Pitner, NCDEQ