NCG240000_Factsheet to Notice_20170628

DEPARTMENT OF ENVIRONMENTAL QUALITY
DIVISION OF ENERGY, MINERAL, AND LAND RESOURCES
FACT SHEET
GENERAL PERMIT NCG240000
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
PERMIT TO DISCHARGE STORMWATER AND WASTEWATER
Permit No. NCG240000 Date: June 28, 2017
1. TYPES OF DISCHARGES COVERED
a. Industrial Activities Covered by this General Permit
Coverage under the NCG240000 General Permit is applicable to owners or operators of
both stormwater and process wastewater discharges associated with activities classified as
compost manufacturing (SIC 2875, compost mixing & 2879, manufacturing soil
conditioners). Coverage is limited to those facilities classified as large Type 1, Type 2, and
small Type 3 composting operations as described in regulations administered by the North
Carolina Division of Waste Management (DWM) and found at 15A NCAC 13B .1402(f).
Coverage is also applicable to stormwater point source discharges from like industrial
activities deemed by the Division of Energy, Mineral, and Land Resources (DEMLR) to be
similar to these operations in the process, or the discharges, or the exposure of raw
materials, intermediate products, by-products, products, or waste products.
Except upon DEMLR determination of similarity as provided immediately above, the
following activities and associated discharges are excluded from coverage under the
General Permit:
• Composting operations classified in 15A NCAC 13B .1402(g) as small Type 1
Facilities. Rationale: DEMLR has determined that limited DEMLR resources might
achieve better state-wide protection of water quality by first focusing on the other
portions of the industry with more problematic feedstocks or larger physical extent.
Although the small Type I facilities are captured by the NPDES rules, DEMLR intends
to regulate the small yard waste facilities on a substantiated complaint basis, rather
than a state-wide blanket approach via the General Permit for at least the first five-
year permit cycle. Also, these facilities must notify DWM annually.
• Backyard composting and on -farm composting as described in 13B .1402(g).
Rationale: These facilities are not captured by the NPDES regulations, and are not
subject to the permitting required under those regulations.
Composting operations classified in 13B .1402(f) as Type 4 Facilities and large Type 3
Facilities. Rationale: DEMLR-s judgment is that this subsector processes feedstocks
of greater potential for water quality impacts, and consequently should be permitted
under the increased scrutiny attendant with individual permits, rather than under the
General Permit. During the first permit term, the Division has considered and
allowed some large Type 3 and Type 4 facilities when circumstances were
appropriate (ex. only having a stormwater discharge, and no wastewater).
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NCG240000 Fact Sheet - Composting General Permit
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• Composting operations for residuals management as described in regulations
administered by DEMLR and found at 15A NCAC 2T .1100. Rationale: DEMLR's
judgment is that this subsector processes feedstocks of greater potential for water
quality impacts, particularly with respect to the potential for the concentration of
heavy metals, and consequently should be permitted under the increased scrutiny
attendant with individual permits, rather than under the General Permit.
• Composting operations with discharges to especially protected receiving waters
classified as ORW, HQW, trout waters, PNA waters, areas with special water quality
management strategies established in North Carolina rules at 15A NCAC 2B .0200,
and zero -flow streams as described in 15A NCAC 2B .0206. Rationale: North
Carolina rules include prohibitions on waste discharges to some of these receiving
water classifications. In general, all of these classifications deserve the extra
administrative attention and regulatory protection available through the individual
permitting process, rather than though the General Permit.
• Stand-alone mulching -only operations are not regulated by NCG240000. Where
mulching operations are co -located at composting facilities and function to provide
feedstocks to the composting operations, they are included with the rest of the
composting operations, and are subject to regulation by NCG240000
Generally, composting operations that are not eligible for coverage under the General
Permit may apply for separate coverage under an individual stormwater discharge permit
and an individual wastewater discharge permit.
b. Types of Operations Covered
Basis for coverage: The federal NPDES program rules at 40CFR122.26(b)(14) specifically
define the industrial activities that are subject to regulation for storm water discharges
associated with industrial activity. These rules at 40CFR122.26(b)(14)(ii) and (xi) capture all
of SIC Major Group 28. Composting is a listed industrial activity in SIC 2875, compost mixing
and 2879, manufacturing soil conditioners, part of Major Group 28, and is subject to NPDES
stormwater permitting. The General Permit covers all on -site activities and features
associated with the compost manufacturing activity. Covered industrial activities and site
features may include, but are not limited to: scales, receiving, staging, grinding, screening,
rejects piles, storage, composting, turning, aeration, moisture addition, curing, blending,
packaging, labeling, warehousing, loading, and other related on -site manufacturing
activities. Also covered are stormwater runoff flows from on -site vehicle and equipment
maintenance areas.
In accordance with NC General Statute 143-214.7A, A Type 1 solid waste compost facility
shall not be required to obtain a National Pollutant Discharge Elimination System (NPDES)
permit for discharge of process wastewater based solely on the discharge of stormwater
that has come into contact with feedstock, intermediate product, or final product at the
facility. For purposes of that G.S., "Type 1 solid waste compost facilities" are facilities that
may receive yard and garden waste, silvicultural waste, untreated and unpainted wood
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waste, or any combination thereof.
c. Characteristics of Discharged Stormwater and Wastewater
The composting process might be described as accelerated biological decomposition of
organic materials. Basic process control parameters include temperature, moisture
content, particle size, aeration rate, bulk porosity, feedstock selection, salts content, and
carbon to nitrogen ratio. Feedstocks vary greatly across the industry, and can include
leaves, wood chips, grass clippings, pre -consumer food wastes, post -consumer food wastes,
manures, sludges, septage, and specialized industrial wastes. The flows resulting from the
manufacturing process activities and from contact with on -site materials can be highly
variable in pollutant strength.
During initial permit development in 2011, the Division reviewed two published studies of
untreated compost discharges, as well as pollutant monitoring results collected under three
DEMLR stormwater permits previously issued to composting operations. The very limited
data set available, along with the inherent high variability of feedstocks, do not allow for a
single definitive characterization of the pollutant concentrations in discharge flows.
However, several categories of pollutants consistently appeared at high levels in the
literature, in permittee monitoring, or in independent Division testing at compost
manufacturing sites. See Appendix A for a tabulation of compost site monitoring data
from the previous permit term. Absent a larger and more differentiated data set, DEMLR
continues to conclude that the following are potential pollutants of concern in both
stormwater and wastewater discharges associated with composting activities.
1. BOD COD: These measures of oxygen demand were highly variable. The highest were
reported at levels several times greater than general characterizations of raw sewage.
2. TSS: The highest levels of TSS were similarly reported at levels well above raw sewage,
and well above the stormwater permitting benchmark for North Carolina.
3. Fecal coliform/E. coli: While reported bacteriological contamination was not as high as
raw sewage, it was still reported as several orders of magnitude greater than North
Carolina water quality standards.
4. Nitrogen: Highly variable results. In one published study, ammonia, an especially
problematic form of nitrogen in the aquatic environment due to its toxicity, was
reported at levels many times greater than general characterizations of raw sewage.
5. Phosphorus: Reported at levels several times greater than general characterizations of
raw sewage, and well beyond the North Carolina stormwater discharge benchmark
value.
6. Metals — Cu, Pb, Zn: DEMLR found limited data even within the limited data set we
reviewed. For Cu, Pb, and Zn there were some reports of discharge levels above the
stormwater discharge benchmark values for North Carolina. Industry representatives
reported to DEMLR that woody feedstocks can sequester metals, and are a probable
source in discharged flows.
7. Oil & grease: Vehicle and equipment maintenance areas only.
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8. pH. The limited data included some pH values below North Carolina Water Quality
Standards, but most values were within water quality standards.
Despite the potential for high absolute concentrations of pollutants in compost site
discharges, two aspects of the discharges may serve to moderate the impact on receiving
waters. First, discharges are typically associated with rain events. This means that the
delivery of pollutants is not typically continuous, and that receiving waters may have the
benefit of increased flows and increased pollutant dilution at the time of discharge.
Second, industry representatives report that for many composting sites, and under good
conditions, small rain events may be substantially absorbed by the composting materials,
reducing the discharge volume. These moderating factors are of course very site specific,
and the degree of the impact of the moderating factors has not been quantifiable.
Stormwater — Vehicle Maintenance Activities (VMAs): Although the analysis is the same,
the parameter name "Total Petroleum Hydrocarbons (TPH)" for stormwater discharges
associated with vehicle maintenance has been replaced by "Non -polar Oil & Grease by EPA
Method 1664 (SGT-HEM)." This description causes less confusion for permittees and their
laboratories because the request for "TPH" can be confused with more expensive gas
chromatography tests for this group of compounds. Non -polar 0&G continues to be a
useful indicator for targeting petroleum -based oils and greases. DEMLR has retained the
benchmark from the previous permit. We would only expect levels to exceed that 15 mg/I
in discharges with significant oil contamination. Based on the relatively small number of
compost sites that trigger the need to monitor discharges from VMAs, and the few hits
outside of the pH range of 6-9, the proposed monitoring suite removes the requirement to
monitor pH.
d. Geographic Area Covered by this General Permit
Discharges covered by this general permit are located at any place within the political
boundary of the State of North Carolina. However, discharges located on the Cherokee
Indian Tribal Reservation are subject to permitting by the U.S. Environmental Protection
Agency, rather than NC DEMLR, and are not eligible for coverage under this General Permit.
e. Receiving Waters
As suggested by the potential pollutant strengths noted above, composting operations
directly or indirectly discharging to especially protected receiving waters (receiving waters
classified as ORW, HQW, trout waters, PNA waters, areas with special water quality
management strategies established in North Carolina rules at 15A NCAC 2B .0200, and
zero -flow streams as described in 15A NCAC 2B .0206) are not eligible for coverage under
this General Permit. DEMLR believes that while exceptions to this prohibition may be
warranted on a case -by -case basis, individual permits should be strongly preferred for such
facilities.
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2. CONSTRUCTING AND OPERATTION OF A TREATMENT FACILITY
An "Authorization to Construct" (ATC) permit for new or expanding wastewater treatment
facilities was once required by 15A NCAC 02H .0100 for the construction and operation of
water pollution control facilities necessary to comply with NPDES permit conditions. That
authorization had been incorporated into the NCG240000 General Permit to streamline the
permitting process. In 2011, Section 9 of Session Law 2011-394 eliminated the ATC
requirement for industrial wastewater treatment facilities.
Also now absent from the revised General Permit is the authorization to construct and operate
a Closed -Loop Recycle System (CLRS) that meets the requirements of the 15A NCAC 02T .1000
Rules. (Requirements for these recycle systems are driven by a State program and were not
impacted by SL 2011-394-s changes to the State Statute.) Facilities that construct and operate
CLRS facilities must apply and obtain the necessary permits or approvals through the Non -
Discharge Permitting Program in the Division of Water Resources (DWR). This change was
prompted by the Stormwater Permitting Program's move out of DWR into DEMLR and helps
ensure appropriate Division oversight of these systems. Systems that are not designed as
closed -loop and have the potential to discharge to surface waters are still covered by
NCG240000.
The Session Law did not remove authority for the Division to require that permittees notify the
DEMLR Regional Office in advance of operation of newly installed or expanded wastewater
treatment facilities. This directive remains a condition of this proposed permit (Part IV, Section
A). The rationale is that this notification alerts NC DEQ of potentially significant changes to
wastewater discharges and allows the opportunity for an inspection to verify compliance with
the NPDES permit.
3. PROPOSED DISCHARGE CONTROLS AND LIMITATIONS
a. Stormwater Pollution Prevention Plan
As in the previous version of this General Permit, stormwater pollution must be controlled
by the development and implementation of a Stormwater Pollution Prevention Plan (SPPP).
DEMLR continues to believe that effective control of the pollutant content in industrial
stormwater discharges can only be achieved when site management implements a written,
site -specific management plan serving that objective. The revised draft permit contains
several minor improvements in the SPPP largely related to improved clarity of language in
the permit text. See the draft permit for the proposed new version of the SPPP
requirements. All facilities covered under this General Permit must develop and implement
an SPPP.
b. Stormwater discharge analytical monitoring
As in the previous version of this General Permit, all permittees must perform quarterly
analytical monitoring of the stormwater discharges, must respond to any exceedances of
the numerical benchmark values for the monitored parameters, must keep records of the
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monitoring results and the permittee's response actions, and must report the monitoring
results to DEMLR. As before, the permittee has the option of applying and obtaining
Representative Outfall Status (ROS) for one or more outfalls to reduce the obligation to
monitor all stormwater discharge outfalls (SDOs) on site. ROS designation is handled
outside of the permit and is not available for wastewater outfalls.
c. Storm water discharges from vehicle maintenance areas (VMA)
As in the previous version of this General Permit and like most other industrial general
permits, permittees are required to separately monitor stormwater discharges originating
from site areas where vehicle maintenance activities are conducted. DEMLR's view
continues to be that monitoring discharges from qualifying vehicle maintenance areas
contributes to the prevention of stormwater pollution from those activities.
d. Qualitative (Visual) monitoring of stormwater discharges
As in previous versions of this General Permit, the permittee must perform twice -per -year
qualitative monitoring (visual monitoring) at all stormwater discharge outfalls. The
proposed revised permit requires visual monitoring to coincide with the analytical sample.
e. Numerical benchmarks and tiered response structure
As in the previous version of this General Permit, the permittee must respond to
benchmark exceedances with increased monitoring, increased management actions,
increased record keeping, and/or the installation of stormwater BMPs in a tiered program.
The exceedance of a numerical benchmark is not considered a violation of the permit
conditions, although failure to respond as per the Tiered response structure would be. In
that context, the benchmark value is not a numerical 'permit limit', but rather a
management action level value. Four (4) benchmark exceedances require the permittee to
notify the DEMLR Regional Office, and may prompt additional requirements under the
provisions of Tier Three.
f. Wastewater discharge analytical monitoring and limitations
The draft permit specifies monitoring and reporting requirements for process wastewater
discharges. DEMLR relies primarily on the definition of process wastewater found in the
NPDES federal regulations at 40CFR122.2, "Process wastewater means any water which,
during manufacturing or processing, comes into direct contact with or results from the
production or use of any raw materials, intermediate product, finished product, byproduct,
or waste product." In addition, DEMLR received an informal opinion in 2010, from the
state's Attorney General's Office concluding that discharges from final product at a
compost manufacturing facility meet the federal NPDES definitions of both wastewater
discharges and stormwater discharges. The Attorney General's Office opinion was confined
to finished product, and did not address feedstocks and other in -process materials. DEMLR
considers that those other materials give rise to process wastewater discharges per the
federal definition cited above.
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DEMLR has sought to identify under what circumstances a discharge from the final product
at a compost facility may be permitted as a wastewater discharge, or instead a stormwater
discharge. In 2010, DEMLR enlisted the assistance of DWM to develop a new criterion for
presumptively identifying the polluting potential for the final product produced by a
composting operation, and to presumptively distinguish wastewater flows from stormwater
flows. The term 'finished compost' has been adopted by DWM and DEMLR, and is used in
the General Permit to identify final products that have reached a higher degree of
degradation and completion of the composting process. In the permitting process, DEMLR
will presumptively consider that stormwater discharges arise from contact with 'finished
compost.' Not all final products produced at a compost facility go to the same end user
market. Some final products can be delivered to the customer in less time, at less cost, and
at a lesser degree of degradation. That means that more organic and nutrient pollution
potential remains in the compost final product, compared to more mature 'finished
compost.' In the permitting process, DEMLR will presumptively consider that flows
originating from contact with these less effectively composted final products give rise to
process wastewater discharges.
Process wastewater discharges are subject to effluent limitations for the conventional
pollutants of TSS, fecal coliform, BOD5, and pH. The General Permit requires quarterly
sampling. DEMLR considered that unlike many wastewater flows from other industrial
activities, flows from composting operations are likely to be intermittent and to be
associated with sporadic rainfall events.
DEMLR intends that if our presumptive determination that a flow should be permitted as a
stormwater does not lead to the permittee's effective control of pollutant discharges from
any particular site, we may on a case -by -case basis revisit that presumptive determination
to assess whether such a flow might be more effectively controlled if re-classified as a
process wastewater discharge, in accordance with the more inclusive scope of the
40CFR122.2 definition of process wastewater.
4. MONITORING AND REPORTING REQUIREMENTS
This General Permit specifies monitoring and reporting requirements for both quantitative
(analytical) and qualitative (visual) assessment of the stormwater discharges, and operational
inspections of the entire facility. Sample parameters and sample frequency are based upon
pollutants potentially generated from composting operations as reported in the literature and
in on -site monitoring reports from current DEMLR permittees.
The proposed monitoring and reporting requirements include the following changes:
• The proposed permit has been restructured to remove authorization to construct (ATC)
requirements that are no longer applicable to this industry. In addition, authorization
to construct and operate a Closed -Loop Recycle System (CLRS) that meets design
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requirements in the 15A NCAC 2T Rules is no longer included as part of this General
Permit. Explanation: The revised structure simplifies the permit and brings
requirements up to date with legislation passed in 2011. Because the Stormwater
Permitting Program has since moved out of the Division of Water Resources (DWR),
which administers the Non -Discharge Permitting Program, DEMLR concluded any
necessary reviews and approvals of Closed -Loop Recycle Systems should originate with
D WR.
• The proposed permit has updated language in the Stormwater Pollution Prevention
Plan (SPPP). Explanation: The revisions make the permit consistent with other more
recently updated general permits and attempt to reduce confusion.
• The proposed permit also allows the permittee to forgo sampling if adverse weather
conditions prevent sample collection (see the Definitions section of the draft permit).
Inability to sample because of adverse weather conditions must be documented in the
SPPP, recorded on the data monitoring forms (DMRs), and DMRs submitted to DEMLR.
Explanation: DEMLR feels this is a reasonable accommodation and keeps the safety of
all employees in mind. The allowance mimics a similar provision in the EPA's 2015 Multi -
Sector Permit without the directive to take a "make-up" sample in the next monitoring
period. DEMLR routinely advises permittees to take a "make-up" sample if one is missed
during a period and plans to include this information in the final Technical Bulletin.
The proposed permit also provides that the permittee is not required to sample runoff
events outside of the normal operating hours of the business (except in the case of
inactive facilities, as they are not operating but may still be bound to sampling
requirements —unless suspended by the Division's granting "dormant status.").
Explanation: DEMLR feels this is a reasonable accommodation and keeps the safety of
employees in mind. Also, since early 2012 the Division's Stormwater Permitting Program
has allowed NPDES stormwater permittees to avoid monitoring requirements under the
conditions of plant shut down or extended inactivity when no regulated industrial
activities were on -going. Dormant status is granted only upon the Division's inspection
of the facility, and concurrence that industrial activities have ceased and no remaining
threats to water quality exist from stormwater runoff. No wastewater generation or
discharges are allowed during the dormant status period.
• The proposed permit drops pH monitoring in stormwater discharges from vehicle
maintenance areas (VMA). Explanation: DEMLR observed that very few pH
measurements from VMA were outside of the benchmark range (See Appendix B) and
suggests that pH should not be considered a characteristic pollutant of concern for
vehicle maintenance areas in this industry. DEMLR has eliminated pH monitoring from
VMA monitoring for other industry sectors over the last couple of years based on
minimal added value to pollution prevention for runoff from these areas versus the rigor
of equipment calibration requirements and constraints of a 15-minute hold time. DEMLR
also notes that EPA's 2015 MSGP does not include pH monitoring for Sector P, Land
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Transportation and Warehousing (which specifically includes vehicle maintenance
activities).
• The proposed permit has updated language in the Tier Responses to Benchmark
Exceedances. Explanation: The revisions make the permit consistent with other more
recently updated general stormwater permits. Most notably, the proposed permit
allows the permittee to contact the Regional Office as early as Tier 2 to coordinate
response actions of Tier 3, rather than waiting to trigger Tier 3.
• The proposed permit revises the reporting requirements to be more consistent with
other general permits in DEMLR's program. This includes revisions in accordance with
the EPA's Electronic Reporting Rule. This special condition (Part III, Section F) requires
all NPDES permittees to report data electronically. The Stormwater Permitting Program
continues to coordinate with EPA and the Division of Water Resources to use the eDMR
infrastructure already in place to implement electronic reporting capabilities for NCG24.
• The proposed permit revises the qualitative monitoring requirements to (1) allow
representative outfall status (ROS) designation to reduce the number of outfalls
monitored throughout the permit term, and (2) requires qualitative monitoring to be
performed during the same event as the analytical samples (this is consistent with other
permits). Explanation: DEMLR has allowed ROS for qualitative monitoring for other
general permits. Also, under this permit facilities are subject to semi-annual facility
inspections. With a monitoring frequency quarterly, and with semi-annual facility
inspections, the combined site management oversight in support of stormwater pollution
control is sufficient and should not preclude ROS for qualitative monitoring.
Part V, Standard Conditions for NPDES General Permits has updated language in
various sections. These include (1) Section A: Reducing period for an existing facility
that applies for coverage for the first time to develop its SPPP from 1 year to 6 months,
(2) Section C: Distinct bypassing conditions for stormwater controls and wastewater
treatment facilities, (3) Section D: Allowance for permittee to provide analytical records
to a DEMLR inspector electronically upon request. Explanation: The revisions make the
permit consistent with other more recently issued permits in DEMLR's Stormwater
Program, and address authorized wastewater discharges covered under this General
Permit. DEMLR also concluded that six months is a reasonable expectation for anew
facility to develop and implement an SPPP and sees no reason to retain the one year
allowance.
The draft General Permit specifies monitoring and reporting requirements for quantitative
assessment of the wastewater discharge. Specific pollutant parameters for which sampling
must be performed and the frequency of the sampling are based upon the pollutants
potentially generated from composting operations as reported in the literature and in site
monitoring reports from current DEMLR permittees.
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The draft permit continues to include specific monitoring requirements for the following
conventional parameters for wastewater discharges: BOD, TSS, fecal coliform, pH, and total
flow. The process wastewater permit limits are taken from federal rule for the minimum level
of effluent quality attainable by secondary treatment as established in 40 CFR 133.102.
Unlike stormwater discharges, a monitoring value for these wastewater discharge parameters
higher than the permit limit constitutes a violation of the terms and conditions of the permit.
S. COMPLIANCE SCHEDULE
The proposed compliance schedule in Part V, Section A was modified to address facilities that
are renewing coverage under this new permit, and to reduce the time period for SPPP
development at existing facilities applying for first-time coverage (from 12 months to 6
months). The permittee is required to comply with Limitations and Controls specified for
stormwater discharges in accordance with the following schedule:
Existing Facilities already operating but applying for permit coverage for the first time: The
Stormwater Pollution Prevention Plan shall be developed and implemented within 6 months of the
effective date of the Certificate of Coverage and updated thereafter on an annual basis. Secondary
containment, as specified in Part III of this General Permit, shall be accomplished within 12 months of
the effective date of the issuance of the Certificate of Coverage.
New Facilities applying for coverage for the first time: The Stormwater Pollution Prevention Plan
shall be developed and implemented prior to the beginning of discharges from the operation of the
industrial activity and be updated thereafter on an annual basis. Secondary containment, as specified
in Part III of this General Permit shall be accomplished prior to the beginning of discharges from the
operation of the industrial activity.
Existing facilities previously permitted and applying for renewal under this General Permit:
All requirements, conditions, limitations, and controls contained in this permit (except new SPPP
elements in this permit renewal) shall become effective immediately upon issuance of the Certificate
of Coverage. New elements of the Stormwater Pollution Prevention Plan for this permit renewal
shall be developed and implemented within 6 months of the effective date of this General Permit and
updated thereafter on an annual basis. Secondary containment, as specified in Part III of this General
Permit shall be accomplished prior to the beginning of discharges from the operation of the industrial
activity.
6. SPECIAL CONDITIONS WHICH WILL HAVE A SIGNIFICANT IMPACT ON THE DISCHARGE
The special conditions in the draft General Permit are the requirements for implementation of
the new electronic reporting of monitoring reports [G.S. 143-215.1(b)]. These are included in
Part III. Section F.
7. BASIS FOR CONTROLS AND LIMITATIONS
Stormwater Discharges
The conditions of this draft General Permit have been designed using best professional
judgment to achieve water quality protection through compliance with the technology -based
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standards of the Clean Water Act (Best Available Technology [BAT] and Best Conventional
Pollutant Control Technology [BCT]). Where the Director determines that a water quality
standard violation is occurring and water quality -based controls or effluent limitations are
required to protect the receiving waters, coverage under the General Permit shall be
terminated and an individual permit will be required. Based on a consideration of the
appropriate factors for BAT and BCT requirements, and a consideration of the factors discussed
below in this fact sheet for controlling pollutants in stormwater discharges associated with the
activities as described in Item 1 (Types of Discharge Covered), this proposed permit retains a
set of requirements for developing and implementing stormwater pollution prevention plans,
and specific requirements for monitoring and reporting on stormwater discharges.
The proposed permit conditions reflect the Environmental Protection Agency's (EPA) and North
Carolina's continued pollution prevention approach to stormwater permitting. The quality of
the stormwater discharge associated with an industrial activity will depend on the availability
of pollutant sources. The Division maintains the position that implementing Best Management
Practices (BMPs) and traditional stormwater management practices which control the source
of pollutants meets the definition of BAT and BCT. The proposed permit conditions (for
stormwater) are not numeric effluent limitations, but rather are designed to be flexible
requirements for developing and implementing site specific plans to minimize and control
pollutants in the stormwater discharges associated with the industrial activity.
Title 40 Code of Federal Regulations (CFR) Part 122.44(k)(2) authorizes the use of BMPs in lieu
of numeric effluent limitations in NPDES permits when the agency finds numeric effluent
limitations to be infeasible. The agency may also impose BMP requirements which are
"reasonably necessary" to carry out the purposes of the Act under the authority of 40 CFR
§122.44(k)(3). The conditions of the revised renewal permit are retained under the authority
of both of these regulatory provisions. The pollution prevention requirements (BMP
requirements) operate as limitations on effluent discharges that reflect the application of
BAT/BCT. The basis is that the BMPs identified require the use of source control technologies
which, in the context of this permit, are the best available of the technologies economically
achievable (or the equivalent BCT finding).
All facilities covered by this stormwater General Permit must prepare, retain, implement, and
(at a minimum of annually) update a stormwater pollution prevention plan (SPPP). The term
"pollution prevention" distinguishes this source reduction approach from traditional pollution
control measures that rely on end -of -pipe treatment to remove pollutants in the discharges.
The pollution prevention approach adopted in the SPPPs in this renewal permit still focuses on
two major objectives: 1) to identify sources of pollution potentially affecting the quality of
stormwater discharges associated with industrial activity from the facility; and 2) to describe
and ensure that practices are implemented to minimize and control pollutants in those
discharges from the facility.
The Division believes that it is not appropriate, at this time, to require a single set of effluent
limitations (for stormwater) or a single design or operational standard for all facilities which
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discharge stormwater associated with industrial activity. The permit instead establishes a
framework for the development and implementation of a site -specific SPPP. This framework
provides flexibility to address the variable risk for pollutants in stormwater discharges
associated with the industrial activities from this industry sector, while ensuring procedures to
prevent stormwater pollution at a facility are appropriate given the processes employed,
engineering aspects, functions, costs of controls, location, and age of facility (as discussed in 40
CFR §125.3). This approach also allows flexibility to establish controls to address varying
sources of pollutants at different facilities.
There has been no significant change to this rationale since the previous general permit.
Stormwater Benchmarks
The pH benchmark range is based on N.C. Water Quality Standards contained in 15A NCAC 02B
.0211 and is consistent with other renewed general stormwater permits.
The total suspended solids (TSS) benchmark of 100 mg/I is based on the median concentration
derived from the National Urban Runoff Program (NURP) study in 1983 and serves as a
benchmark in industrial stormwater permits with TSS monitoring.
The non -polar oil and grease (vehicle maintenance only) benchmark of 15 mg/I has been
carried over from the previous permit cycle. The value is consistent with other states'
benchmarks and/or limits at the time it was introduced and reflects a value we would associate
only with significant oil contamination.
The Chemical Oxygen Demand (COD) benchmark is 120 mg/L. A ratio of 4:1 has been adopted
as within the characteristic range for COD:BOD in domestic wastewaters. The benchmark for
BODs is based on the Secondary Treatment Regulation specified in the Code of Federal
Regulations, Title 40, Part 133 (40 CFR §133). This regulation defines the minimum level of
effluent quality attainable by secondary wastewater treatment as 30 mg/L for the 30-day
average of BODs. (30 x 4 = 120 mg/1)
The Fecal Coliform benchmark is 1000 col/100 mL. This value is based on BPJ and was
consistent with the maximum (one -sample) threshold specified in Virginia's older Water
Quality Standards. The N.C. Water Quality Standard (for all Class C waters, based on human
health) provides that fecal coliforms shall not exceed a geometric mean of 200/100mL (MF
count) based upon at least five consecutive samples examined during any 30-day period, nor
exceed 400/100mL in more than 20 percent of the samples examined during such period. The
SW Program does not consider these values practical for a stormwater benchmark. In addition,
the N.C. Standard, 2B .0211, specifies that violations of that standard "are expected during
rainfall events."
The Total Nitrogen benchmark is 30 mg/L. The benchmark for total nitrogen is the sum of the
(nitrate + nitrite) and TKN benchmarks. The National Primary Drinking Water Regulation (40
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NCG240000 Fact Sheet - Composting General Permit June 28, 2017
CFR §141.11) specifies a maximum contaminant level of 10 mg/L nitrate. This value is the same
as the N.C. water quality standard for water supply (WS) waters in the T15A NCAC 2B .0200
rules. The benchmark for TKN (organic nitrogen [20 mg/L]) is based on an approximate
equivalency to secondary treatment of wastewater. This is reasonable, given that the majority
of TKN found in stormwater is unlikely to be directly bio-available. Organic nitrogen, in the
form of decaying leaves and twigs for example, will exert less demand on in -stream dissolved
oxygen (DO) than TKN from domestic wastewater. Furthermore, low DO in receiving streams is
rarely attributed to rainfall events. The lack of documented water quality problems, coupled
with the sporadic nature of rainfall events, justifies the use of a TKN benchmark of 20 mg/L.
Therefore, TN = 30 mg/L.
The Total Phosphorus benchmark is 2.0 mg/L, and is based on BPJ and is consistent with
wastewater permit limits imposed on NSW dischargers.
Total Copper, Total Lead, and Total Zinc benchmarks:
Because of the sporadic nature of rainfall, acute (short-term) effects are considered when
establishing stormwater benchmarks for toxicants. Toxicant benchmarks are set at one half
the Final Acute Value (1/2 FAV) for metals. NCDEQ uses the % FAV to set daily maximum
wastewater limits for toxicants in conjunction with weekly average limits. The FAV is estimated
by a statistical analysis of acute toxicity data and protects 95 percent of the species in the most
sensitive genera that has been tested. A safety factor of two is applied for water quality
protection purposes. EPA's recommended Criteria Maximum Concentrations [CIVIC = % FAV]
are based on dissolved metal criteria, but N.C. translates the values into total. Where metal
values are hardness -dependent, the value is based on a hardness of 25 mg/L. The SW Program
recognizes that acute values for these metals are low, and that their toxicity is highly variable
(depending on the amount dissolved, which is affected by many factors). One of the primary
factors influencing toxicity for Cu and Zn is hardness. North Carolina currently assumes 25
mg/L hardness when calculating toxicity values for these metals. The benchmark values for
Cu, Pb, and Zn have increased since the last permit term, based on a revised default hardness
and method of translating dissolved criteria to total metal concentrations.
The Total Copper benchmark is 0.010 mg/L, and is based on % FAV and is converted to total
copper from dissolved copper reported in EPA's National Recommended Water Quality
Criteria.
The Total Lead benchmark is 0.075 mg/L, and is based on % FAV and is converted to total lead
from dissolved lead reported in EPA's 1980 Ambient Water Quality Criteria for Lead.
The Total Zinc benchmark is 0.126 mg/L, and is based on % FAV and is converted to total zinc
from dissolved zinc as reported in EPA's National Recommended Water Quality Criteria.
Wastewater Discharge Limitations
The authorized process wastewater discharge types from leachates, wash waters, and rinse
waters are also retained in this draft permit. This draft permit includes non -polar oil and
grease action levels for wastewater when VMA-derived stormwater drains and commingles
with wastewater before discharge. The draft permit effluent limitations are based on N.C.
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NCG240000 Fact Sheet - Composting General Permit
June 28, 2017
Water Quality Standards. The pH and TSS limitations are based on water quality standards in
15A NCAC 2B .0200, .0300, and .0400 (40 CFR by reference).
8. REQUESTED VARIANCES OR ALTERNATIVES TO REQUIRED STANDARDS
There are no requested variances or alternatives to required standards. Facilities requesting
variances to required standards will not be covered under this General Permit but will instead
be required to seek coverage under an individual permit.
9. THE ADMINISTRATIVE RECORD
The administrative record, including the draft permit, fact sheet, public notice, comments
received, and additional information is available by writing to:
Stormwater Permitting Program
Division of Energy, Mineral, and Land Resources
1612 Mail Service Center
Raleigh, North Carolina 27699-1612
The above documents are available for review and copying at:
Archdale Building, 91" Floor
DEMLR Stormwater Permitting Program
512 N. Salisbury Street
Raleigh, North Carolina
between the hours of 8:00 AM and 5:00 PM Monday through Friday. Copies will be provided at
DEMLR's currently established estimate of the cost of reproduction.
10. DEMLR CONTACT
Additional information about the draft permit may be obtained at the above address between
the hours of 8:00 AM and 5:00 PM Monday through Friday by contacting: Robert Patterson at
[phone] 1 [e-mail]
11. SCHEDULE OF PERMIT ISSUANCE
Draft Permit Public Notice —Statewide notice published August 15, 2017;
Draft available on DEMLR website August 15, 2017;
Comment Period Ends September 15, 2017.
Permit Scheduled to Issue — Scheduled for September 30, 2017
Effective October 1, 2017
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NCG240000 Fact Sheet - Composting General Permit June 28, 2017
12. PROCEDURE FOR THE FORMULATION OF FINAL DETERMINATIONS
a. Comment Period
The Division of Energy, Mineral, and Land Resources proposes to issue the NPDES General
Permit for the above described stormwater discharges subject to the outlined limitations,
management practices, and conditions. These determinations are open to comment from
the public.
Interested persons are invited to submit written comments on the permit text or on the
Division's proposed determinations to the following address:
NC Dept. of Environmental Quality
DEMLR Stormwater Program
512 N. Salisbury St.
1612 Mail Service Center
Raleigh, NC 27699-1612
Attn: Robert Patterson
All comments received within thirty days following the date of public notice are considered
in the formulation of final determinations.
b. Public Meeting
The Director of the Division of Energy, Mineral, and Land Resources may hold a public
meeting if there is a significant degree of public interest in a proposed permit or group of
permits. Public notice of such a meeting will be circulated in newspapers in the
geographical area of the discharge and to those on the Division's mailing list at least thirty
days prior to the meeting.
c. Appeal Hearing
An applicant whose permit is denied, or is granted subject to conditions he deems
unacceptable, shall have the right to a hearing before the Commission upon making written
demand to the Office of Administrative Hearing within 30 days following issuance or denial
of the permit.
d. Issuance of a Permit When No Hearing is Held
If no public meeting or appeal hearing is held, after review of the comments received, and
if the Division's determinations are substantially unchanged, the permit will be issued and
become effective on the first day of the month following the issuance date. This will be the
final action of the Division of Energy, Mineral, and Land Resources.
If a public meeting or appeal hearing is not held, but there have been substantial changes,
public notice of the Division's revised determinations will be made. Following a 30-day
comment period, the permit will be issued and will become effective on the first day of the
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month following the issuance date. This will be the final action of the Division unless a
public meeting or appeal hearing is granted.
APPENDIX A
NCG240000 2011- May 2017 DM Data
(13 Facilities covered under NCG24)
Stormwater
TSS
COD
Fecal
Coliform
Nitrogen
Phosphorous
Copper
Lead
Zinc
pH
# of exceedances
6
11
20
1
8
11
0
2
1
# of samples
26
28
28
26
25
28
28
28
27
exceedance %
23%
39%
71 %
4%
32%
39%
0%
7%
4%
min
1.5
18
17
bdl
bdl
bdl
bdl
bdl
5.1
max
388
1310
60000
61.3
8.36
0.95
0.012
0.38
8.4
*based on current sw benchmarks
**7 facilities reporting (others
reporting no flow
Wastewater
No wastewater DMRs were located.
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