NCG200000_Response to Comments and Changes_20150129

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DEMLR Response to Comments on NCG20
January 29, 2015
North Carolina DEMLR Response to Comments
and Summary of Changes to
NPDES Stormwater draft General Permit NCG2OOOOO
(2015 Renewal)
Background
NPDES Stormwater General Permit NCG200000, which regulates industrial stormwater
discharges from scrap metal recycling facilities (a portion of SIC 5093), expired on December 31,
2014. The North Carolina Division of Energy, Mineral, and Land Resources (DEMLR) posted the
proposed draft General Permit and the supporting Fact Sheet on the Stormwater Permitting
Program website beginning December 15, 2014. We announced in sixteen selected
newspapers across the state on or before November 30, 2014 that the draft of the proposed
revised General Permit would be available on our website for public comment. DEMLR also ran
this notice in the December 15, 2014 issue of the North Carolina Register.
The public comment period closed on January 15, 2015 (31 days), consistent with the
regulatory minimum duration of 30 days.
DEMLR revises and reissues our NPDES stormwater General Permits on an approximately five-
year schedule. Every five years we solicit public comment, especially from the particular
regulated industry sector; we review analytical data from the previous five-year term of the
permits; we evaluate identified compliance problems and problems in our enforcement of the
permits as may be reported by our Regional Office inspectors; and we seek to improve the
effectiveness of the permits as stormwater management tools for the permittees.
As required by agreement with EPA, DEMLR sent the proposed General Permit to EPA Region IV
staff in Atlanta on December 15, 2014 for the agency's review. On December 23, 2014, EPA
Region IV responded with no comments, other than to request an additional review of the
General Permit if DENR had made significant changes in response to public comments. EPA's
additional review and approval would be necessary if the proposed final General Permit
incorporated significant changes from the published draft version or if significant public
comments objecting to the permit were received. DEMLR concluded that neither of these
criteria was met, and therefore further EPA review before final issuance was not required.
DEMLR routinely prepares this summary document both for those that submit written
comments on the draft General Permits, as well as for other interested parties. This document
will be posted on our website for public access.
Comments and Responses
DEMLR received only one set of comments on the proposed draft General Permit NCG200000
during the public comment period mandated by North Carolina rules. We note that we

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DEMLR Response to Comments on NCG20
January 29, 2015
similarly received only one set of comments on NCG20 during the previous public comment
period five years earlier (2009).
In addition, DEMLR also received public comments on five other General Permits in 2013, and
on another General Permit issued in 2014; together the comments covered six other regulated
industrial sectors. For the sake of a consistent regulatory approach across multiple industry
sectors, several of those comments received during the 2013 and 2014 General Permit
renewals were incorporated into the Draft NCG20 published for public comment.
The comments in this public comment period were thoughtful and relevant to key aspects of
the General Permit. We appreciate the time and effort reflected in the comments. We
paraphrase those comments as listed below. We have noted which comments have been
included in some form in the final version of the General Permit. We have also identified those
comments that we rejected, and the basis for doing so.
1. Commenter suggests that the copper benchmarks of 0.010 mg/L (freshwater) and
0.005 mg/L (saltwater) are too low. Commenter asks if there are studies establishing
the harmful levels of copper discharges. Commenter suggests that dissolved copper in
conjunction with the receiving water hardness would be a more appropriate way to
regulate the toxic aquatic impact of this heavy metal.
Response: Federal NPDES rules require that our permits be written to monitor metals
for the total recoverable amount (dissolved plus suspended) present. Copper
benchmarks are derived from the one-half Final Acute Value (1/2 FAV) reported in
studies from the water quality and bioassay literature. Our benchmark for total copper
results from a translator equation developed by EPA that yields total recoverable values
(as required by NPDES rules) but for which the inputs are generalized assumptions on
the dissolved fraction, the background hardness, pH, and total suspended solids.
We note that all of our General Permits, including NCG20, are intended to cover specific
industry sectors under the conditions of limited environmental risks and standardized
on -site conditions and standardized state-wide receiving water conditions. For toxic
heavy metals especially, in those circumstances where our standardized assumptions on
the receiving water hardness, pH, and TSS might be significantly different from the
actual conditions, we are amenable, on a case -by -case basis, to reviewing any
permittee's circumstances with an objective of ascertaining whether alternative
benchmark values are appropriate at the permittee's discharge point. We would expect
to work with the permittee in such a review while the permittee is in Tier 3 status. And
we would expect the permittee or his consultant to construct a persuasive argument
along the lines indicated: that the receiving water characteristics would support an
increased pollutant concentration beyond the % FAV from the literature while still
protecting the aquatic biota. Further, and based on the site -specific circumstances, it's
also possible that a persuasive argument might be constructed where in -stream
concentrations already exceed action levels upstream of the site, and the site discharges

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DEMLR Response to Comments on NCG20
January 29, 2015
are not increasing concentrations or contributing to water quality standards violations
downstream of the site. However, while we are open to a case -by -case examination of
special circumstances, we continue to believe that the more protective programmatic
approach is to establish the General Permit first as a broad regulatory vehicle, but to be
prepared to accommodate site -specific exceptions as they may infrequently arise and as
they may be shown to be justified by further consideration of receiving water
conditions.
We also note that as a result of the recently completed Triennial Review of water quality
standards, the proposed copper benchmark has already increased from 0.007 mg/L
(previous 2009 version of the permit) to 0.010 mg/L (draft 2015 version of the permit.)
This increase reflects an improvement in the relevant knowledge and methodology for
assessing aquatic impacts. Note that ultimately the benchmark values are based on
what concentrations of what pollutants will be detrimental to the aquatic biota, not on
other considerations.
Result: The draft General Permit proposes a copper benchmark that has already been
increased from 0.007 mg/L to 0.010 mg/L based on recent results of the Triennial
Review. For the reasons above, we are not persuaded that an additional basis for a
further increase has been established for use in the General Permit. The draft General
Permit remains unchanged for the copper benchmark concentration.
2. Along the same lines, commenter points out that the drinking water action level for
copper is 1.3 mg/L, two orders of magnitude higher than the General Permit
benchmark of 0.010 mg/L. Commenter suggests that DEMLR adopt a benchmark of
twice the drinking water action level.
Response: It is important to understand that generally the stormwater discharge
benchmark values are designed to protect the aquatic biota from pollutants generated
at industrial sites. Consequently, comparisons to human health criteria generally are
not relevant. Consider that humans routinely drink chlorinated water specifically
because chlorine has been added into the water to kill selected aquatic biota. Similarly,
copper chemicals have been added to drinking water reservoirs specifically to kill
objectionable aquatic organisms. That humans can safely ingest chemicals in quantities
toxic to aquatic biota does not argue that those concentrations should be converted
into benchmarks which are intended to prevent surface water pollution and protect,
rather than kill, the aquatic biota.
Result: As noted previously, the copper benchmark has already been increased from
0.007 mg/L to 0.010 mg/L based on advances in knowledge and methodology. It seems
to us that additional increases in the copper benchmark have not been justified. The
draft General Permit remains unchanged for the copper benchmark concentration.

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DEMLR Response to Comments on NCG20
January 29, 2015
3. Commenter suggests that the Tier 2 Response requirements are too burdensome.
Specifically the requirements for monthly sampling for all parameters at the outfall
where two consecutive exceedances have occurred. Commenter offers that a less
burdensome approach could contain some of the following elements: sample
monthly only for the parameter that was twice exceeded, not all of them; monthly
sampling to be waived if appropriate BMPs have been installed; or, monthly sampling
to be limited to no more than four samples per year.
Response: Background: Tier 2 of the draft General Permit requires that upon two
consecutive benchmark exceedances for the same parameter at the same outfall the
permittee must begin monthly sampling at that outfall for all the parameters regulated
at that outfall. The tier and benchmark structure (including monthly monitoring) is
widely implemented as a standard part of our NPDES industrial stormwater permits that
include analytical monitoring. The objective of the tier and benchmark structure is to
achieve the reduction in stormwater pollutant discharges in months, rather than in
years. The structure includes several flexible options for the permittee. The tier and
benchmark structure is intended to involve the permittee in an increasing level of
attention in feasible attempts to solve the 'mystery' and the discharge of pollutants
above the benchmark levels. Consistent with the problem solving approach, it is
important to understand that the monthly sampling requirement is intended to provide
additional data as an early step in solving the problem. The monthly sampling
requirement is not intended to be punitive. Exceeding a benchmark value is not a
violation of a permit limit, and the exceedance itself is not a sufficient basis for agency
enforcement actions.
Consistent with the problem solving approach, we view the monthly sampling
requirement as an opportunity to gather potentially helpful information early. We have
considered previously the suggestion that monthly sampling should be for only the
exceeded parameter, not the full suite of parameters regulated under the permit. We
disagree with this partial approach to early data gathering in a problem solving
endeavor. Further, consider that the permittee's generalized obligation is to control the
discharge of all regulated pollutants into the surface waters of North Carolina at all
times. Note the sequence of the Tiered structure in NCG20:
• With no exceedances the permittee continues just to sample twice per year.
• Tier 1: With one exceedance, the permittee must assess potential sources and
feasible response actions. If he is successful, then he is out of Tier 1 status with
the next sampling event, nominally six months later.
• Tier 2: With two consecutive exceedances the permittee again performs the Tier
1 response analysis and actions. Additionally, monthly sampling begins. The
interpretation here is that the permittee's initial attempt in Tier 1 was not fully
successful, and with that information in hand he should try again to identify the
source and a feasible response action. Note that the flexibility built into the
permit text provides three paths out of Tier 2 status: a) The permittee can in the
relatively short time of several months accumulate three monthly results lower

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DEMLR Response to Comments on NCG20
January 29, 2015
than the benchmark and drop out of the Tiered response action obligation. Or,
b) the permittee can in the relatively short time of several months accumulate
the fourth exceedance (the permittee already has two) and is then under the
Tier 3 obligation to contact the DEMLR Regional Office for assistance. Or, c) the
permittee can contact the Regional Office as part of the Tier 2 response action
and essentially ask to be accelerated into Tier 3 response status.
Tier 3: The Tier 3 status (whether arrived at normally with four exceedances, or
through the permittee's request to be accelerated from Tier 2 status) allows the
Regional Office staff to work with the permittee under a wide freedom of permit
interpretation and actions. The Regional Office may conclude that continuing
monthly sampling does not hold sufficient promise for understanding the source
and achieving the reduction of discharged pollutants. Or to the contrary, the RO
may conclude that additional sampling is necessary to assess the source of, or
the magnitude of, or a feasible response to polluted discharges. The focus on
monthly sampling is: Let's get some early data, but let's not just continue
sampling with no hope of a benefit in our problem -solving mode. We want the
permittee to gather some little bit of data as a potential basis for rational
decision making. We do not want the permittee to gather data for no
meaningful purpose.
We disagree that installing a BMP should automatically substitute for monthly sampling.
However, consider that while in Tier 3 status a permittee is obligated to engage the
Regional Office, and may propose a BMP in lieu of continued monthly sampling, and the
Regional Office can assess the acceptability of that proposal.
We disagree with limiting monthly sampling to four times per year. Our focus in the Tier
and benchmark structure is to achieve a reduction in polluted stormwater discharges
within months, rather than within years. Monthly sampling can accelerate the
accumulation of either the three monitoring results below benchmark (so that the
permittee is dropped out of the tiered structure and back into only twice per year
sampling), or the accumulation of two more results in excess of the benchmark (total of
four) and the required involvement of the Regional Office staff in solving the problem.
Summary: For the reasons identified above, we continue to think that the Tier and
benchmark structure, and especially including the monthly monitoring requirement in
Tier 2, is an effective approach for improved control of stormwater pollution. Our
feedback from some permittees, and some consultants, and our Regional Office staff is
that the structure as presented has resulted in significantly improved performance
during the several years of implementation starting slowly in 2007 and continuing with
each subsequent batch of General Permit renewals.
Result: No change to the proposed General Permit NCG20 in response to these
comments.

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DEMLR Response to Comments on NCG20
January 29, 2015
Summary of Significant Changes from the draft General Permit
1. We have adopted no changes to the proposed draft General Permit NCG20 based on the
public comments received during the 2014-2015 public comment period.
2. As included in the section following, public comments on other General Permits from
the 2013 and 2014 renewals were included in the published draft version of NCG20.
3. Public comments previously received in the 2009 public comment period for NCG20
resulted in minor changes in the 2009 version of NCG20.
Summary of Significant Changes from the Previous General Permit
1. The following minor changes appear throughout the revised General Permit:
a. Minor word changes, format changes, and sequencing of paragraphs;
b. Table of Contents reflects minor re -ordering of some sections;
c. Reference now to the Division of Energy, Mineral, and Land Resources as the
permitting authority, rather than the now defunct Division of Water Quality.
2. Part I, Section B now provides that the permittee's Certificate of Coverage is an
enforceable part of the General Permit.
3. Part II, Section A has renamed the several elements required as part of the Stormwater
Pollution Prevention Plan (SPPP).
4. Part II, Section A includes minor re -wording to be more specific on the required content
of several of the elements of the SPPP.
5. Part II A 2(b) now further clarifies that an Oil Spill Control and Countermeasure Plan
(SPCC) can serve to partially comply with the SPPP requirements.
6. Part II A 3 amends the requirement to have a responsible person on site during facility
operations that have increased potential to contaminate stormwater.
7. Part II, Sections B, C, and D require monitoring during a measureable storm event (new
term) rather than a representative storm event (old term.) This revised sampling
requirement should make it easier for permittees to obtain the required samples.
8. Part II, Section B removes the requirement to sample for pH in site stormwater
discharges. Basis for change: As reported in our Fact Sheet, during the last permit cycle
only eight percent of measurements of pH were outside the benchmark range of
6<pH<9. Further, we were not able to identify a likely source for pH excursions on scrap
metal sites. We concluded that it is not appropriate to include monitoring of this
parameter in an industry -wide General Permit intended to address pollutants likely
present across the industry.
9. Part II, Section B removes the requirement to sample for cadmium in site stormwater
discharges. Basis for change: As reported in our Fact Sheet, our review of the collected
monitoring data from the last permit cycle revealed that in every instance of a cadmium
benchmark exceedance three other monitored metals (copper, lead, and zinc) also
exceeded their respective benchmarks each time. Further, we expect that any response
action to address the exceedances from copper, lead, and zinc would also likely address
any concurrent cadmium levels above its benchmark concentration.

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DEMLR Response to Comments on NCG20
January 29, 2015
10. Part II, Section B also revises the requirement to sample for Oil & Grease by
substituting Non -polar Oil & Grease. Non -polar oil and grease is a narrower test that
focuses on petroleum -based materials. We feel this is a better test parameter at these
sites where animal and vegetable fats, oils, and greases are less likely to be present.
11. Part II, Section B adds a new lower benchmark for TSS (50 mg/L), applicable to
especially protected and sensitive waters classified as Outstanding Resource Waters,
High Quality Waters, Trout Waters, and Primary Nursery Area waters.
12. Part II, Section B Table 2 has been revised to adjust the duration of the first and last
monitoring periods so that the start and end dates of the intervening periods coincide
with the calendar half -year dates (Jan —June, July— Dec).
13. Part II, Section D On -Site Vehicle Maintenance Monitoring Requirements has been
revised to eliminate pH monitoring; to replace Oil and Grease and the 30 mg/L
benchmark with the narrower parameter non -polar oil and grease with a 15 mg/L
benchmark. The TSS benchmarks have been expanded to include a new lower
benchmark (50 mg/L) for especially sensitive waters (ORW, HQW, Tr, and PNA).
14. The Standard Conditions in old Parts III — VI have been reorganized to be consistent with
other NPDES permits Standard Conditions. All newly re -issued General Permits are
being rewritten to include the elements of the new Standard Conditions. Most of the
provisions are unchanged. However, some significant changes include:
a. Part III A 1 clarifies SPPP compliance requirements for existing facilities applying
for renewal.
b. Federal and state law and rule citations have been added for reference in several
of the paragraphs throughout the Standard Conditions.
c. Part III B 1 no longer requires the permittee to submit a renewal application
within 180 days of permit expiration.
d. Part III, Sections B, D, and E provide new standard conditions related to the
anticipated roll -out of on-line electronic reports and electronic records.
Conclusion
DEMLR's overall intent in proposing changes to the General Permit was to provide permit
requirements that will encourage permittees to respond with prompt corrective action to the
discovery of pollutant discharges indicated by visual observation or analytical results in excess
of the benchmark values. DEMLR has incorporated selected public comments received during
other recent (2013 and 2014) public comment periods on other recent draft General Permits
where we agreed that the comments were helpful and relevant to NCG20.
LUED