NC0090212_Correspondence_20240325 (2)

Responses to the SELC Comments
Permit NCO090212
Albemarle Kings Mountain Lithium Project
March 25, 2024
1. First, as it has for many industrial NPDES permits, DEQ has ignored in this draft permit
the mandatory requirement under the Clean Water Act to impose technology -based effluent
limitations (TBELs). DEQ is well aware of this issue because we have raised it with the
agency multiple times
Response:
During development of the permit DWR personnel reviewed all existing available data and
required more data from the applicant, reviewed EPA documents and resources for relevant
parameters of concern for established limits, conducted Reasonable Potential Analysis for
each parameter of concern, assessed water quality impacts, evaluated other pertinent items,
and as appropriate developed limits based upon Best Professional Judgement (BPJ) in
accordance with applicable rules and regulations.
DWR evaluated this concern and is not aware of specific industrial mining dewatering
information sufficient to develop BPJ BAT effluent limitations for mining dewatering
facilities.
2. Second, water in the mine's existing pit extends to a depth of 165 feet below the mine's
current surface. The draft permit proposes to authorize the discharge of that water.
However, the proposed wastewater treatment design was developed based on removing
water only up to 150 feet.
Response:
In accordance with established rules and practices the DWR conducted the EPA -
recommended analyses to determine the reasonable potential for toxicants to be discharged
at levels exceeding water quality standards/EPA criteria by this facility. For purposes of
the RPA background concentrations for all parameters were assumed to be below detection
level. The RPA uses 95% probability level and 95% confidence basis in accordance with
the EPA Guidance entitled "Technical Support Document for Water Quality -based Toxics
Control."
The Division used pollutant concentration data at a depth of 160 ft for the RPA because at
this depth the pollutant concentrations are the highest. This analysis is conservative and
considers the worst -case scenario.
3. 303(d) list. " Fact Sheet at 2. This is incorrect. Kings Creek (AU ID 12877) is listed as
impaired for benthos on the 2022 303(d) list.
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Response:
Kings Creek (AU ID 12877) is listed as impaired for benthos on the 2022 303(d) list.
DWR personnel reviewed and assessed Kings Creek (AU ID 12877) 2022 303(d) listing
and determined that the basis of the listing is not associated with any parameter of concern
associated with the proposed discharge. During the development of the permit, it was
determined that the status of the waterbody is based upon other factors, such as poor habitat
associated with periodic low flows during critical periods. Specifically, the 2022
Assessment Report indicates the creek is impaired for macroinvertebrates which is
typically associated with intermittent low flows which is common within this creek. The
Assessment Report also indicates the creek meets the standards for fish community.
Therefore, addition of the proposed flow is not going to contribute to the existing
impairment.
4. We request that DEQ develop a monitoring regime to ensure discharges of effluent cause
no increase in turbidity when background conditions in the receiving water already exceed
50 NTU.
Response:
Turbidity is a measure of water clarity and can be influenced by various factors, including
natural processes and human activities. This permit includes a turbidity monitoring
condition which requires that discharges do not cause excessive turbidity levels that could
harm aquatic ecosystems or violate water quality standards.
The turbidity condition has been slightly expanded to require additional effluent
monitoring, as follows, if effluent turbidity exceeds 50 NTUs.
The discharge shall not cause the turbidity of the receiving waters to exceed 50 NTU. If
the turbidity exceeds this level due to natural background conditions, the discharge level
cannot cause any increase in the turbidity in the receiving waters. Instream turbidity
monitoring shall not be required unless effluent turbidity exceeds 50 NTU. If effluent
turbidity exceeds 50 NTU, instream and effluent monitoring shall be conducted weekly
during the months of June, July, August, and September and monthly during the remaining
months of the year until effluent turbidity is less than 50 NTU.
5. Fifth, DEQ used a reasonable potential analysis to develop water quality based effluent
limitations. That reasonable potential analysis assumed that "background concentrations
for all parameters [are] below detection level" in Kings Creek. DEQ must rerun its
reasonable potential analysis accounting for these background concentrations.
Similarly, DEQ completed its reasonable potential analysis for hardness -dependent metals
"utilizing a default hardness value of25 mg/L CaCO3. "Fact Sheet at 2. But data in DEQ's
position indicates hardness in Kings Creek is much higher.
Response:
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DWR respects the concern raised and NPDES staff re-evaluated the situation. Review of
the background concentration data for Kings Creek indicates the majority of samples for
all parameters of concern are below detection limits or practical quantitation limits.
• Exceptions are As, Mo, and Chlorides. The limit for Chlorides is already in the permit
and inclusion of the background concentration would have no impact on the RPA
results. Two background samples for As are below practical quantitation limit, the
remaining two are 0.54 µg/L and 1.72 µg/L. The allowable As concentration is 157.5
µg/L, and even if we consider the background concentrations and potential effluent
concentration of 5.3 µg/L it would not change the RPA results. One background sample
for Mo is below detection level, the remaining three have the following concentrations:
2.33 µg/L, 0.55 µg/L, and 0.76 µg/L. The allowable Mo concentration is 2,100.6 µg/L,
and even if we consider the background concentrations and potential effluent
concentration of <0.2 µg/L it would not change the RPA results.
Employing a higher hardness value for the RPA analysis results in less strict permit limits.
Thus, DWR is utilizing a default hardness value of 25 mg/L CaCO3 for hardness -dependent
metals. This approach has been approved by the EPA, including the use of the default
hardness value. The Division does not have statistically significant number of hardness
data to change the conservative and environmentally protective default value.
6. Sixth, DEQ appears to be ignoring narrative water quality standards in calculating limits
in this permit. See Memo from Sam Billin, Linkan Engineering, to Morgan Wallen,
Albemarle, 5 (identifying sulfide and manganese as contaminants of concern).
Response:
While permitting authorities may not always be required to employ narrative water quality
standards in calculating permit limits, they must ensure compliance with all applicable
water quality standards, including both numeric and narrative criteria, to protect water
quality and meet regulatory requirements under the CWA. With that said, DWR:
• Specifically removed Mn standard on April 6, 2016because this element is naturally
present in high concentration in vast majority of North Carolina waters.
• Conducted the RPA for Sulfide and the limit was added to the permit.
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