NCS000562_NOV Response_20190726

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July 25, 2019
Stanley E. Aiken
AMERICAN
ZINC RECYCLING
Delivering a Sustainable Future
Regional Engineer
Land Quality Section
North Carolina Department of Environmental Quality
2090 US 70 Highway
Swannanoa, NC 28778-8211
Re: American Zinc Products, LLC
Mooresboro Facility
Notice of Violation. June 20, 2019
Dear Mr. Aiken:
TIMOTHY R. BASILONE
Vice President — Environmental Affairs
3000 GSK Drive T 724-773-2223 www.azr.com
Suite 201 F 412-788-4526 [e-mail]
Moon Township, PA 15108
We have received from the Department the Notice of Violation (NOV 2019-PC0405)
dated June 20, 2019 (the "NOV") concerning the facility at Mooresboro, North Carolina (the
"Facility") owned and operated by American Zinc Products, LLC ("AZP"). The NOV addresses
compliance considerations at the Facility applicable to stormwater management, including
relative to NPDES Individual Stormwater Permit NCS000562 (the "NPDES Permit"). More
specifically, the NOV references the discharge event from the existing stormwater retention
basin on May 11, 2019 (the "Discharge Event').
AZP has previously provided to the Department information related to the Discharge
Event and to the issues addressed in the NOV. AZP has restated in this response certain of that
information to the extent responsive to the NOV, and has provided additional information
specifically requested through the NOV. The information included in this response reflects that
the circumstances giving rise to the Discharge Event did not result from any improper act or
omission by AZP, and that the Discharge Event was fully consistent with good operating
practices, minimized the potential for a significant release event, and had been addressed by AZP
through notifications provided by AZP to the Department in advance of the Discharge Event.
As you are aware, the Facility experienced a fire on April 28, 2019. In containing and
ultimately extinguishing the fire, the emergency responders only utilized water from the fire
water system; no fire suppression foam was employed in the response event. After quenching
the fire, the suppression water either flowed to the cell house basement containment structure or
reached paved surfaces, entered existing drains, and was directed by underground pipe to the
lower stormwater retention basin (the "Stormwater Retention Basin").
The cell house basement is an existing containment structure located beneath the cell
house, and is designed to ensure the containment of any liquids originating and released from the
Received
JUL 2 6 2019
Land Quality Section
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structure above. The fie water that accumulated in the cell house basement exhibited similar
characteristics to process water routinely used at the Facility, and was pumped to process tanks
to enable the water to be used in the production process. Therefore, the portion of the fire water
that reached the cell house basement was contained and did not reach the Stormwater Retention
Basin.
Fire water that did not flow to the cell house basement generally reached paved surfaces
and was conveyed to surface drains connected to the Facility's stormwater collection system.
This system directed the collected fire water to the Stormwater Retention Basin. At the initiation
of the emergency response actions related to the incident, the valve controlling discharge from
the Stormwater Retention Basin to the Broad River was closed. Therefore, no water related to
the fire suppression efforts could be discharged from the Stormwater Retention Basin during the
incident or in the context of the immediate response measures.
For several days following the fire, AZP commissioned actions to clean the paved
surfaces in the area surrounding the relevant structure where the fire had occurred, to collect and
remove any constituent impacts related to the fire incident. Thereafter, AZP undertook to
visually review these paved surfaces to confirm that they were both dry and clean; several
representatives of the Department and EPA also reviewed and observed these conditions.
Therefore, on or before May 3, 2019, AZP had taken appropriate actions to prevent any
additional surface contribution to stormwater of constituents related to the fire incident. For this
reason, as of May 3, any stormwater generated from surfaces at the Facility was unaffected by
the fire incident and has exhibited characteristics consistent with historic conditions.
With respect to water that had been collected in the Stormwater Retention Basin due to
the flow of fire water at the time of incident, AZP both evaluated the volume of water in the
basin and collected and analyzed samples of that water. After fire water had flowed through the
stormwater collection system to the basin, the Stormwater Retention Basin was observed to be
approximately one-third full, relative to intended operating capacity. The valve controlling
discharge from the stormwater retention basin to the river was closed at the onset of the fire as
part of emergency response measures taken to prohibit potential discharge of water from the
basin to the river. No water was being discharged from the basin to the river at the time the
valve was closed.
By way of more detailed responses to the specific requests included in the NOV, AZP
further responds as follows:
1) A reasonable explanation as to why the aforementioned violations occurred,
including but not limited to:
a. A detailed explanation for the method used to determine:
i. that the valve needed to be opened, and
ii. that the use of available storage volume in the basin would result in
damage to the dam.
b. An explanation as to why the prolonged release occurred from the outfall of Basin
1, and why the continued discharge observed on May 11, 2019 was not
discovered by AZP personnel.
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C. An explanation as to why the access road to the Basin 1 failed, resulting in
discontinuation of pump/haul efforts.
d. An explanation for exceedances of benchmark values for permit parameters
before and after the avoidable discharge.
Response:
AZP disputes the characterization of the discharge event as constituting a "violation," as
described in this provision of the NOV. AZP nonetheless responds to this specific request
without limitation to its claims and defenses in response to any allegation of noncompliance in
this context, and as if the specific request for information does not otherwise characterize the
Discharge Event as constituting a "violation."
As described in this response, AZP instituted extensive actions to minimize the potential
for discharge from the Stormwater Retention Basin of water that had been affected by the fire.
Moreover, and importantly, AZP had expressly communicated to the Department (by electronic
mail on May 3, 2019 and through several conversations) the probable need for a discharge from
the basin in order to preserve the structural integrity of the basin walls.
On May 11, AZP personnel closely monitored the rate at which the basin had filled with
water during the significant storm event. AZP also had, prior to and during the storm event,
carefully tracked the meteorological forecasts to understand the expected rain levels and thereby
projected that forecasted rain levels would overtop the basin walls, potentially disrupting the
structural integrity of the basin and causing a significant release to the river. Significantly, AZP
also acted in a manner to protect the safety of AZP personnel. Access to the vault was already
obstructed, and continued projected flow to the basin would completely block access, creating an
unsafe access condition. Moreover, the weather forecast indicated that rainfall would continue —
and basin levels would continue to rise — until nightfall, interfering with clear visual access to the
basin.
In this context, it is important to recognize that the vault component of the basin is
designed as a spillway for a 100-year flood, and the dam spillway is designed to prevent adverse
impact to the constructed structure. AZP's management of the event was fully consistent with
best management practices for basin/spillway management. For example, information included
within documents posted on-line by the United States Army Corp of Engineers recognizes that
many dams are not constructed to allow volumetric retention at levels fully consuming available
freeboard. Other research states that, for embankment dams, maintenance of three feet of
freeboard should be considered a minimum operating standard, especially in the event of
uncertainty regarding projected loading rates. Similarly, dam safety videos complied by and
made available from North Carolina explain that spillways are designed to remove excess
stormwater, and overtopping can result in dangerous situations. The FEMA report linked to the
North Carolina website specifically states that "[o]vertopping failures, which were the most
common failure type in South Carolina, can be mitigated using both operational and structural
approaches. Operational approaches include controlled releases in advance of an event,
permanently lowering the surface elevation of the reservoir, and conducting routine inspection
and maintenance activities." (Emphasis added.)
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Consistent with its notification to the Department and notwithstanding implementation of
multiple measures to manage the volume of accumulated water in the Stormwater Retention
Basin, storm conditions during the weekend of May 11 and 12 resulted in the need to allow
discharge from the basin to the river, as previously forecasted by AZP to the Department.
Specifically, the significant rain event resulted in a substantial volume of stormwater flow to the
basin, notwithstanding the reduction of flow by use of the plug inserted in the stormwater pipe
related to Facility roadway drainage.
The storm conditions also materially degraded the condition of the access road leading to
the basin, preventing additional use of trucks to pump water from the basin. The prevailing
weather forecasts projected the potential for at least another 2 inches of rain in the next 24 hours.
Therefore, when the volume of water in the basin had risen to a level that covered both the top of
the vault and walkway to the valve, AZP acted to protect the retaining walls of the basin by
opening the gate valve and allowing a limited, and carefully evaluated, discharge. In order to
protect against the potential for loss of structural integrity of the basin, AZP discharged
approximately 20,000 gallons of water from the basin from 3:15 pm— 5:15 pm on May 11. The
gate valve was closed when the discharge had reduced the volume of water in the basin to allow
the top of the vault to be visible. This May 11-12 event has been the only discharge from the
basin since the fire incident.
AZP conducted sampling in connection with this single discharge event. Metals samples
were collected from the vault when it was opened at 3:15, and from the Outfall when the valve
was closed at 5:15. AZP also collected samples for analyses as requested by the Department, at
the Outfall at 11:00 p.m. All such sample results have previously been submitted to the
Department.
Following its attempt to shut the discharge valve in the context of this limited discharge
event necessitated to preserve the integrity of the basin, AZP observed (and communicated with
the Department concerning) a small amount of water discharging from the basin at the control
valve, apparently as a result of an incomplete seal on the discharge valve. AZP promptly
investigated the seepage and discovered that debris from the basin (i.e., cattails) had become
lodged in the valve and prevented full closure. AZP then took action to clear the debris, and
successfully restored full function (and complete closure) of the valve at approximately 3:00 a.m.
on May 12. Representatives of the Department subsequently observed the basin and valve and
confirmed that the seepage/discharge had been eliminated.
AZP further disputes the characterization by the Department of the discharge incident as
a "prolonged release." AZP carefully and methodically limited the duration of the discharge
event and the volume of the discharge to that necessary to preserve the integrity of the basin.
Upon identifying the opportunity to terminate the discharge event, AZP took all appropriate
actions to close the relevant valve and discontinue further discharge. Because of the
significantly elevated level of the river associated with the storm event that prompted the need
for the release, the valve was not visible to AZP personnel at the moment when the valve was
closed. Therefore, AZP could not visually observe the presence of small pieces of vegetation in
the valve seal, preventing the valve from properly seating. Although prior discharges from the
basin had been infrequent, and therefore the valve had not been operated frequently, within its
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limited use, the valve had not previously failed to seal, including because of the presence of any
vegetation. For these reasons, AZP had no reason to further investigate that the valve had fully
and properly sealed when the river levels had later receded to reveal that the valve had not fully
closed. Upon receiving the information of the continued discharge from the valve, AZP acted
promptly to investigate the cause of the incomplete valve closure and remedy it.
With respect to the access roads, AZP had implemented consistent and routine
maintenance efforts of these access roads for several years without any road failure. The erosion
of the road in the context of the event resulted from the combination of significant repeated
rainfall and the extended use of the roads by the trucks for hauling of water. AZP continued to
implement all potential maintenance efforts, but could not implement effective repair measures
while the rainy weather continued to erode the roads and create challenges for maintenance
options.
As the Department is aware, discharges from the basin had exceeded the benchmark
values established in the NPDES Permit prior to the fire and related discharges. As stated above
and as previously reported, the reduced pH of the water effected by the fire reduced the pH of the
collected water in the basin and resulted in an increase in the concentration of certain metal
parameters that leached under the slightly acidic conditions.
It is critical to recognize in evaluating the incident and the discharge conditions relative
to benchmark values, that these benchmark parameters neither did nor do constitute discharge
limits applicable to the Facility under the NPDES Permit. Instead, upon identifying basin water
concentrations above these benchmark values in 2018, AZP had developed, and had been
implementing, a program to pursue reductions in constituent concentrations with an objective of
pursuing those benchmark values. Actions consistent with that plan are fully compliant with the
obligations applicable to AZP under the NPDES Permit.
2) A detailed account of all response actions taken leading up to, and after, the
aforementioned violations, including but not limited to:
a. The volume, dates and extent of pump/haul efforts to remove contaminated water
from Basin 1.
b. Efforts to neutralize contaminated water and location of application.
C. Design, location, and effectiveness of measures implemented to isolate
stormwater flow to Basin 1.
d. Maintenance efforts related to access road for Basin 1.
Response:
As stated above, AZP disputes the characterization of the discharge event as constituting
a "violation," as described in this provision of the NOV. AZP nonetheless responds to this
specific request without limitation to its claims and defenses in response to any allegation of
noncompliance in this context, and as if the specific request for information does not otherwise
characterize the Discharge Event as constituting a "violation."
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AZP expended significant efforts to remove accumulated water from the Stormwater
Retention Basin to maximize the available volumetric retention capacity for storm events without
triggering a need to discharge. Specifically, AZP commissioned a program to pump water from
the basin into trucks to allow it to be placed into tanks at the Facility for process use. More than
one million gallons of water were removed from the Stormwater Retention Basin in this manner.
AZP continued its program of withdrawing water from the basin via pumping to trucks, to the
extent that such efforts could be safely and effectively employed in the face of specific storm
impacts and the conditions of the area access roads and structures at the Stormwater Retention
Basin. AZP specifically communicated to representatives of the Department that, despite AZP's
extensive efforts to remove water and prevent any discharge from the basin, AZP expected that a
significant storm event directing large volumes of water to the Stormwater Retention Basin
would necessitate a discharge to preserve the integrity of the retention basis as a critical
stormwater management feature.
AZP implemented additional measures to attempt to preserve the hydraulic capacity of
the retention basin and with the objective of limiting the potential for a necessary discharge to
the river. In particular, AZP installed a plug within the stormwater pipe conveying to the
stormwater retention basin stormwater collected in drains from the Facility roadways. Although
measures taken by AZP since the fire incident ensure that the quality of stormwater generated
on -site is consistent with the character of the stormwater prior to the incident, use of the plug
within the pipe enabled water to be diverted (via pump truck) to an upper basin at the Facility
(helping to preserve the capacity of the lower basin).
Following the fire incident, sampling results revealed reduced pH, likely associated with
the sulfuric acid present in the process area of the Facility directly affected by the fire. In
addition, concentrations of several metals were elevated compared to the established baseline for
waters in this basin. The increase in metals concentration was most likely the result of the more
acidic character of the water flow which resulted in leaching of metals from material in contact
with the flow as it was directed to the Stormwater Retention Basin. Recognizing the.need for and
value of restoring the pH of the collected water to the neutral range (i.e., 6-9) -- consistent with
the pH discharge standard under the Facility's NPDES permit -- AZP communicated with the
Department regarding AZP's intention to neutralize the pH of the collected water. AZP then
implemented appropriate neutralization efforts to establish a pH within NPDES Permit limits.
These efforts consisted of the introduction of sodium bicarbonate and lime into the basin.
Subsequent monitoring efforts demonstrated that the pH of water in the basin was within the
neutral range, between 6 and 9 s.u., and that metal constituents (other than zinc) were generally
consistent with the monitored range for stormwater samples taken prior to the accidental fire.
As stated above, AZP had implemented consistent and routine maintenance efforts of the
access roads for several years without any road failure. The erosion of the access road in the
context of the event resulted from the combination of significant repeated rainfall and the
extended use of the roads by the trucks for hauling of water. To the extent that conditions
supported safe and effective road maintenance, AZP continued to implement its established
maintenance program, but could not implement effective repair measures while the rainy weather
continued to erode the roads, interfere with successful maintenance options, or pose safety
hazards to employees or contractors.
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AZP committed significant additional resources to repair of and enhancements to the
access roadway. Among other actions, the corridor road was raised 6 -8 inches, sloped for
appropriate drainage, and widened, and turnoffs were installed to allow for more than one
vehicle to travel on the roadway at the same location. AZP also cleaned and repaired the drains
running under the roadway. Riprap was added to re-establish roadway drainage, and AZP created
a concrete pool to drain water to piping under the roadway. Concrete was also installed at
certain roadway locations to increase structural stability.
3) An engineered study of the effectiveness of stormwater piping and treatment
systems implemented on site.
Response:
The design and operation of the Stormwater Retention Basin, coupled with AZP's
development and implementation of strong policies and procedures to address unplanned,
significant events, resulted in the effective capture and management of water impacted by the
fire incident. These procedures and systems prevented any significant impact to the environment
from the fire event. Further, even after the effective implementation of its emergency response
measures and the successful use of the properly designed and maintained Stormwater Retention
Basin, AZP pursued additional measures to effectively manage any affected water, further
minimize impact to the environment and prevent discharges of the fire -affected water to the
river, except under the very limited circumstance that occurred on May 11, and that had been
forecasted by AZP and addressed in its prior notification to the Department.
4) An engineered Plan of Action to prevent these violations from recurring in the
future.
Response:
AZP disputes the characterization of the discharge event as constituting a "violation," as
described in this provision of the NOV. AZP nonetheless responds to this specific request
without limitation to its claims and defenses in response to any allegation of noncompliance in
this context, and as if the specific request for information does not otherwise characterize the
incident as constituting a "violation."
As stated above, AZP strongly asserts that the design and operation of the Stormwater
Retention Basin, coupled with AZP's development and implementation of well designed policies
and procedures to address unplanned, significant events, resulted in the effective capture and
management of water impacted by the fire incident. These procedures and systems prevented
any significant impact to the environment from the fire event. Further, AZP pursued additional
measures to effectively manage any affected water, further minimize impact to the environment
and prevent discharges of the fire -affected water to the river, except under the very limited
circumstance that occurred on May 11, and that had been forecasted by AZP and addressed in its
prior notification to the Department.
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5) An implementable action plan to evaluate, quantify and address the long- and short-
term effects of the aforementioned violations.
Response:
AZP disputes the characterization of the discharge event as constituting a "violation," as
described in this provision of the NOV. AZP nonetheless responds to this specific request
without limitation to its claims and defenses in response to any allegation of noncompliance in
this context, and as if the specific request for information does not otherwise characterize the
incident as constituting a "violation."
The May 11-12 Discharge Event has been the only discharge from the Stormwater
Retention Basin since the fire incident. AZP conducted sampling in connection with this single
discharge event. Metals samples were collected from the vault when it was opened at 3:15, and
from the Outfall when the valve was closed at 5:15. AZP also collected samples for analyses as
requested by the Department, at the Outfall at 11:00 p.m. All such sample results have
previously been submitted to the Department.
The sampling performed by AZP demonstrates that the discharge from the basin did not
cause any in -stream concentrations in excess of applicable water quality standards. In particular,
the discharge was necessitated by the heavy rainfall in the region, which resulted in significant
flow to the basin and more generally to the Broad River. The high flowrates in the river during
the discharge event result in in -stream concentrations of all parameters within appropriate water
quality standards.
6) A reasonable timetable for completion of all actions to be taken in response to the
aforementioned violations.
Response:
AZP undertook, and has now completed its efforts, to remove from the Stormwater
Retention Basin all water that had been related to the response to the fire. In addition, and as had
been previously communicated to the Department, AZP then excavated down to indigenous clay
the sediment that had accumulated over time in the retention basin, analyzed that.sediment and
confirmed that it did not exhibit concentrations of any constituents that would characterize the
material as hazardous waste, and disposed of that sediment off -site. AZP then installed a
synthetic liner in the basin, in order to facilitate future maintenance of the basin and prevent the
recurrence of vegetation from the base of the basin from interfering with the operation of the gate
valve controlling discharge from the basin. In the aggregate, the measures taken by AZP related
to the Stormwater Retention Basin ensure that any water now accumulating in the retention basin
cannot be affected by the April fire, and instead is consistent with the stormwater managed by
AZP within the Stormwater Retention Basin prior to the fire incident. Therefore, discharges
from the Stormwater Retention Basin will be fully consistent with discharge conditions prior to
the fire.
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AZP interprets the existing, effective NPDES Permit to authorize and govern its use of
the Stormwater Retention Basin for stormwater management and discharge to the Broad River.
AZP will continue its efforts, consistent with both the NPDES Permit and AZP's written
program previously submitted to the Department, to pursue reductions in measured
concentrations of relevant parameters toward the "benchmark" values identified in the NPDES
Permit. AZP recognizes that such benchmark values do not constitute discharge limits, but AZP
nonetheless restates its commitment to implement those actions previously identified to the
Department to pursue further reductions in discharge concentrations in pursuit of those
benchmarks.
Based on the current conditions and for the reasons addressed above, AZP interprets its
current NPDES Permit to authorize discharge from the basin of any stormwater that hereafter
accumulates in the basin from the Facility. Of course, stormwater will accumulate in the
Stormwater Retention Basin in the normal course of Facility operations. When the accumulated
volume reaches the level warranting discharge from the basin to the river, AZP believes that it is
both necessary and appropriate to resume its discharge practices, in a manner consistent with its
activities prior to the fire. Therefore, please be advised that AZP intends to discharge
stormwater from the basin in accordance with the NPDES Permit at the point that an appropriate
stormwater volume is accumulated consistent with historic, good stormwater management
practices. AZP will monitor stormwater discharges consistent with the requirements of the
NPDES Permit.
Please let me know if you have any questions about the information provided in this letter
or this matter more generally.
Very truly yours,
/. xak, ,r
TimothyR. Basilone
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