NCG090000_DRAFT Fact Sheet_20180806

DEPARTMENT OF ENVIRONMENT AND NATURAL RESOURCES
DIVISION OF ENERGY, MINERAL, AND LAND RESOURCES
FACT SHEET
GENERAL PERMIT NCG090000
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM
PERMIT TO DISCHARGE STORMWATER
Permit No. NCG090000 Date: August 6, 2018
1. TYPES OF DISCHARGES COVERED
a. Industrial Activities Covered by this General Permit
Coverage under this general permit is applicable to all owners or operators of
stormwater point source discharges associated with activities classified as
establishments primarily engaged in manufacture of paints, varnishes, lacquers,
enamels, and allied products [standard industrial classification (SIC) 28S]. Coverage is
also applicable to 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.
b. Types of Operations Covered
The Manufacturing Paints, Varnishes, Lacquers, Enamels, and Allied Products
categories include facilities primarily involved in the manufacturing of paints (in paste
and ready -mix form); varnishes; lacquers; enamels and shellacs; putties, wood fillers,
and sealers; paint and varnish removers; paint brush cleaners; and allied paint
products.
When viewed as a class, many of the facilities in this General Permit typically purchase
feedstock which is made into various surface coating products using an entirely
physical process (no chemical conversions take place) that involves mixing, grinding, as
well as other operations. However, the potential for exposure of toxic constituents at
these facilities exists especially at locations such as shipping and receiving areas, areas
used to store empty drums, and outside bulk chemical storage areas. Chemical spills are
not an uncommon occurrence at these facilities. Pollutant parameters of particular
concern in these industries can be broadly categorized as conventional pollutants,
heavy metals, and volatile organic compounds.
c. Characteristics of Discharged Stormwater
The decision to retain parameters from the previous permit is based on their continued
usefulness as stormwater pollution indicators for these industry types.

NCG090000 Fact Sheet — NC DEQ
d. GeographicArea(s) Covered by this General Permit
August 6, 2018
Discharges covered by this General Permit are located at any place within the political
boundary of the State of North Carolina. Discharges located on the Cherokee Indian
Tribal Reservation are subject to permitting by the US Environmental Protection
Agency and are not covered by this General Permit.
e. Receiving Waters
Receiving waters include all surface waters of North Carolina or municipal separate
storm sewer systems conveying stormwater to surface waters.
2. DISCHARGE CONTROLS AND LIMITATIONS
The General Permit incorporates two main approaches to reduce the discharge of polluted
stormwater from this category of industrial facilities: It requires a written management
plan with the specific objective of site management action to control polluted discharges,
and it requires periodic self-monitoring of the discharges. The General Permit
incorporates pollutant benchmark concentrations to provide facilities a tool with which to
assess the effectiveness of implementation of the management plan, the Stormwater
Pollution Prevention Plan (SPPP). These benchmark concentrations are not effluent limits,
but provide guidelines for implementation of the facility's SPPP. Exceedences of
benchmark values require the permittee to increase monitoring, increase management
actions, increase record keeping, and/or install stormwater BMPs in a tiered program.
Four (4) benchmark exceedences trigger notification to the DEMLR Regional Office and
may prompt additional requirements ("Tier 3"). This general permit first incorporated
stormwater benchmarks and tiered responses in the 2007 renewal.
3. PROPOSED MONITORING AND REPORTING REQUIREMENTS
The permit specifies monitoring and reporting requirements for both quantitative and
qualitative assessment of the stormwater discharge and operational inspections of the
entire facility. Specific pollutant parameters for which sampling must be performed and
the frequency of the sampling are based upon the types of materials used, stored, and
transferred at these sites and on the potential for contamination of the stormwater runoff
at these facilities.
The draft renewal permit proposes specific analytical monitoring requirements for the
following parameters: Total Cadmium, Total Chromium, Total Lead, and Total Rainfall.
Qualifying discharges from Vehicle Maintenance Areas will be analyzed for pH, Total
Suspended Solids (TSS), and Total Rainfall. These parameters are retained based in part on
data submitted by permittees, but also on the expectation of their continued presence in
the manufacturing activity and their usefulness as stormwater pollution indicators for
these industry types within the revised monitoring scheme.
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NCG090000 Fact Sheet — NC DEQ August 6, 2018
The draft permit incorporates a modified definition of what storm event should be
sampled. Previous permits required sampling during a "representative storm event." The
proposed NCG090000 permit renewal now requires permittees to sample the
"measurable storm event," a relatively new term for North Carolina stormwater permits.
The "measurable storm event" is an event that results in an actual discharge, rather than an
event with a rainfall measuring 0.1 inches or more. To qualify as a measurable storm event,
the previous storm event must have been at least 72 hours prior. In 2011, the NCG140000
Ready -Mixed Concrete General Permit was the first permit to implement this new storm
event definition.
The proposed general permit 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
and recorded on the data monitoring forms (DMRs). The proposed draft maintains the
requirement to separate semi-annual sampling events by a minimum of 60 days.
As before, the renewal permit specifies qualitative (visual) monitoring of each stormwater
outfall for the purpose of evaluating the effectiveness of the Stormwater Pollution
Prevention Plan and assessing new sources of stormwater pollution. Qualitative
monitoring parameters include color, odor, clarity, floating and suspended solids, foam, oil
sheen, and other obvious indicators of stormwater pollution. Qualitative monitoring
should be performed during the analytic sampling event.
The draft permit proposes more specific direction to the permittee about how to respond
to qualitative monitoring. If qualitative monitoring indicates that existing stormwater
BMPs are ineffective, or that significant stormwater contamination is present, the
permittee must investigate potential causes, evaluate the feasibility of corrective actions,
and implement those corrective actions within 60 days. A written record of the permittee's
investigation, evaluation, and response actions must be kept in the SPPP. The draft permit
also includes a Qualitative Monitoring Response, establishing actions for when a
permittee repeatedly fails to respond effectively to correct problems, or if the discharge
causes or contributes to a water quality standard violation.
4. COMPLIANCE SCHEDULE
The proposed compliance schedule in Part III, Section A was modified to address facilities
that are renewing coverage under this renewed permit. The permittee shall 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 12 months of the effective date of the Certificate of Coverage
and updated thereafter on an annual basis. Secondary containment, as specified in
Part II, Section A, Paragraph 2(b) of this general permit, shall be accomplished
within 12 months of the effective date of the issuance of the Certificate of
Coverage.
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NCG090000 Fact Sheet — NC DEQ
August 6, 2018
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 II, Section
A, Paragraph 2(b) 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, Paragraph 2(b) of this general permit shall be accomplished
prior to the beginning of discharges from the operation of the industrial activity.
5. SPECIAL CONDITIONS WHICH WILL HAVE A SIGNIFICANT IMPACT ON THE
DISCHARGE
This draft general permit does not propose any special conditions that will have a
significant impact on the discharge. However, the proposed draft does add Special
Conditions in Part II, Section D. that address electronic reporting requirements mandated
by the federal NPDES Electronic Reporting Rule. When the agency's electronic reporting
system is able to accept NPDES stormwater permit monitoring data, the permittee must
report discharge monitoring data electronically using NC Division of Water Resources'
Electronic Discharge Monitoring Report (eDMR) internet application. NC DEMLR will
notify permittees when eDMR is ready to accept data.
6. BASIS FOR CONTROLS AND LIMITATIONS
Stormwater Discharges
The conditions of this general permit have been designed using best professional judgment
to achieve water quality protection through compliance with the technology-based
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
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), the permit retains a set of
requirements for developing and implementing stormwater pollution prevention plans,
and specific requirements for monitoring and reporting on stormwater discharges.
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NCG090000 Fact Sheet — NC DEQ August 6, 2018
The permit conditions reflect the Environmental Protection Agency's (EPA) and North
Carolina's 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. This renewal permit still reflects the Division's position that
implementation of Best Management Practices (BMPs) and traditional stormwater
management practices which control the source of pollutants meets the definition of BAT
and BCT. The permit conditions 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 renewal permit are retained under the authority
of both of these regulatory provisions. The pollution prevention requirements (BMP
requirements) in this permit 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 general 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. The term
"pollution prevention" distinguishes this source reduction approach from traditional
pollution control measures that typically rely on end -of -pipe treatment to remove
pollutants in the discharges. The plan requirements are based primarily on traditional
stormwater management, pollution prevention and BMP concepts, providing a flexible
basis for developing site-specific measures to minimize and control the amounts of
pollutants that would otherwise contaminate the stormwater runoff.
The pollution prevention approach adopted in the SPPP in the 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
stormwater discharges associated with industrial activity from the facility and to ensure
compliance with the terms and conditions of this permit.
The Division believes that it is not appropriate, at this time, to require a single set of
effluent limitations or a single design or operational standard for all facilities which
discharge stormwater associated with industrial activity. The permit instead establishes a
framework for the development and implementation of site-specific stormwater pollution
prevention plans. This framework provides the necessary flexibility to address the variable
risk for pollutants in stormwater discharges associated with the industrial activities that
are addressed by the permit, while ensuring procedures to prevent stormwater pollution
at a given facility are appropriate given the processes employed, engineering aspects,
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NCG090000 Fact Sheet — NC DEQ August 6, 2018
functions, costs of controls, location, and age of facility (as discussed in 40 CFR 125.3). This
approach allows flexibility to establish controls which can appropriately address different
sources of pollutants at different facilities.
The EPA and NPDES States have, on a case-by-case basis, imposed BMP requirements in
NPDES permits. The EPA has also continued to review and evaluate case studies involving
the use of BMPs and the use of pollution prevention measures associated with spill
prevention and containment measures for oil. The development of the NPDES permit
application requirements for stormwater discharges associated with industrial activity
resulted from the evaluation and identification of the potential contaminants and the
resultant water quality impacts of stormwater discharges from industrial sites. Public
comments received during the rule making provided additional insight regarding
stormwater risk assessment, as well as appropriate pollution prevention and control
measures and strategies. During that time EPA again reviewed stormwater control
practices and measures. These experiences have shown the Division that pollution
prevention measures such as BMPs can be appropriately used and that permits containing
BMP requirements can effectively reduce pollutant discharges in a cost-effective manner.
BMP requirements are imposed in general permits in lieu of numeric effluent limitations
pursuant to 40 CFR 122.44(k)(2).
There has been no significant change to this rationale since the 2012 renewal of
General Permit NCGO90OOO.
Stormwater Benchmarks
The proposed pH benchmark range of between 6.0 and 9.0 standard units for discharges
from vehicle maintenance areas is based on N.C. Water Quality Standards in 15A NCAC 02B
.0211 and is consistent with other renewed general stormwater permits.
The standard total suspended solids (TSS) benchmark of 100 mg/1 for discharges from
vehicle maintenance areas is based on the median concentration derived from the National
Urban Runoff Program (NURP) study in 1983 and serves as a benchmark in most other
industrial stormwater permits with TSS monitoring. The lower TSS benchmark for ORW,
HQW, trout, and primary nursery area (PNA) waters of 50 mg/l reflects half that standard
value and was set to flag potential problems in discharges to waters with much lower
water quality standards for TSS concentrations (20 mg/l for HQW and ORW; 10 mg/l for
trout and PNA waters).
The benchmarks for the toxic heavy metals cadmium, chromium, and lead remain the
same as in the previous version of the permit; i.e. 0.001 mg/L, 1.0 mg/L, and 0.03 mg/L,
respectively. The 2012 permit changed the required reporting to be in mg/L rather than
ug/L. Although the change in units represented no change in the benchmarks or in the
measured pollutant concentrations, our examination of the reported data suggests that on
some occasions permittees were confused as to the required reporting units and the
reporting of values below the method detection limit. See Appendices D and E for more
information on the heavy metals.
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NCG090000 Fact Sheet — NC DEQ August 6, 2018
The values for all three benchmarks are based on 1/2 FAV as reported in EPA's Ambient
Water Quality Criteria documents in 2001, 1980, and 1980 for cadmium, chromium, and
lead respectively. North Carolina is currently proposing changes to water quality (WQ)
metals standards that will establish dissolved metals standards for the first time. If those
WQ standards are finalized, acute values for total recoverable metals will change as a result
of a revised translation method (for translating a dissolved value to a total recoverable
value, which federal NPDES regulations require to be used in a permit) and a different
assumed water hardness. However, the proposed metals standards will not be finalized for
some time. Because those changes are not final, DEMLR is not proposing new stormwater
benchmarks for the three toxic heavy metals at this time.
7. 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.
8. THE ADMINISTRATIVE RECORD
The administrative record, including application, draft permit, fact sheet, public notice,
comments received, and additional information is available by writing to:
Stormwater Program
Division of Energy, Mineral, and Land Resources (DEMLR)
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
The above documents are available for review and copying at:
Archdale Building, 9th Floor
DEMLR Stormwater 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 a charge of 10 cents per page.
9. STATE CONTACT
Additional information about the draft and final permit may be obtained at the above
address between the hours of 8:00 AM and 5:00 PM Monday through Friday by contacting:
Annette Lucas at [phone].
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NCG090000 Fact Sheet — NC DEQ
10. SCHEDULE OF PERMIT ISSUANCE
August 6, 2018
Draft Permit to Public Notice - Statewide notice to publish September 4, 2018
Draft available on-line September 4, 2018;
Comment period ends October 5, 2018.
Permit Scheduled to Issue - October 15, 2018 (Effective November 1, 2018)
11. PROCEDURE FOR THE FORMULATION OF FINAL DETERMINATIONS
a. Comment Period
The Division of Energy, Mineral, and Land Resources proposed to issue an NPDES
General Permit for the above described stormwater discharges subject to the outlined
effluent limitations, management practices, and special conditions. These
determinations were open to comment from the public.
Interested persons were invited to submit written comments on the permit application
or on the Division of Energy, Mineral, and Land Resources' proposed determinations to
the following address:
Stormwater Program
Division of Energy, Mineral, and Land Resources
1617 Mail Service Center
Raleigh, North Carolina 27699-1617
Attn: Annette Lucas
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 of Energy, Mineral, and
Land Resources' 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
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NCG090000 Fact Sheet — NC DEQ
August 6, 2018
If no public meeting or appeal hearing is held, after review of the comments received,
and if the Division of Energy, Mineral, and Land Resources' 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 of Energy, Mineral, and Land Resources 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 month following the issuance
date. This will be the final action of the Division of Energy, Mineral, and Land Resources
unless a public meeting or appeal hearing is granted.
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NCG090000 Fact Sheet — NC DEQ August 6, 2018
APPENDIX A
Comparison of Other States' TPH Stormwater Benchmarks and/or Limits:
APPENDIX B
Comparison of TPH Analysis Costs vs. 0&G Analysis:
Page 10 of 15
Benchmark, Limit,
Agency
Media
criteria, etc
Value (mg/L)
Notes
CT
groundwater
protection criteria
0.5
EPA Method 418.1
NV
groundwater
discharge limit1.0
Technology-based limit
VA
groundwater
reporting limit
1.0
Virginia Petroleum Storage Tank Program
KS
groundwater
cleanup standard
0.5
Risk-based standard
TX
groundwater
MCL
1.1
Maximum Contaminant Level
OK
groundwater
MC
3.0
May require cleanup down to 0.1 mg/L if near well
Tacoma, WA
slormwater
mance goal
perforL
10.0
24 -hr average
Tacoma, WA
stormwater
performance goal
15.0
Grab sample
Port of Seattle NPDES permit technology-based limit for construction
areas5.0 hi typically used for all construction sites In slate; plus no
WA
stormwater
max daily limit
5.0
risible sheen non -numerical limit.
WA
slormwater
ax daily limit
8.0
Pod of Seattle NPDES permit for deicing areas
WA
slormwater
max daily limit
15.0
Port of Seattle NPDES permit for roadways
24 -hr average, EPA Method 1664A, NJPDES NJO132721 (hot -mix asphalt
NJ
stormwater
mo. Ave. limit
10.0
plants)
Grab sample, EPA Method 1664A, NJPDES NJO132721 (hot -mix asphalt
NJ
stormwater
max daily limit
15.0
plants)
Grab sample, TPDES permit TXG340000 (petroleum bulk stations and
TX
stormwater
max daily limit
15.0
terminals)
APPENDIX B
Comparison of TPH Analysis Costs vs. 0&G Analysis:
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NCG090000 Fact Sheet - NC DEQ
Notes.
HEM = n -hexane extractable material
SGT -HEM = silica gel treated n -hexane extractable material
GRO = gasoline range organics
DRO = diesel range organics
Page 11 of 15
August 6, 2018
O&G/HEM TPH as SGT -HEM
TPH-GRO
TPH-DRO
LABORATORY
EPA 1664A
SW -846 EPA
8015B
Entironmental Chemists Inc.
$50
$50
$50
$50
Pace Analytical Services, Inc.
$50
$60
$40
$40
Microbac Laboratories, Inc.
$55
$55
na
na
Cameron Testing SeMces
$45
$60
$43
$43
Entironmental Conservation Laboratories, Inc.
$75
$75
$40
$45
Water Tech Labs, Inc.
$50
ria
$60
$60
DWO Lab
$34
na
$87
$87
Mentech, Inc.
$45
$68
$50
$50
Chadotte-Mecklenburg Utilities Laboratory
$30
$43
na
na
Avg (TPH-GRO + TPH-DRO)
costto capture full range
of TPH
Average Cost
$48
$59
$53
$54
$106
Notes.
HEM = n -hexane extractable material
SGT -HEM = silica gel treated n -hexane extractable material
GRO = gasoline range organics
DRO = diesel range organics
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August 6, 2018

NCG090000 Fact Sheet - NC DEQ
APPENDIX C
NPDES Stormwater General Permits NCG030000 and NCG100000
(Modified and proposed in 2012 for the renewal of NCG090000)
Total Toxic Organics (TTO) Benchmark Development
August 6, 2018
1. Reference: Subchapter N - Effluent Guidelines and Standards, 40CFR433.10ff, Part 433 - Metal
Finishing Point Source Category. Forty-six types of metal finishing operations are listed,
appearing to be a comprehensive list of the types of activities that might be labeled, `metal
finishing.'
a. Subpart A presents wastewater and pretreatment effluent limitations in 433.13, 433.14,
433.15, 433.16, and 433.17 for BPT, BAT, PSES, NSPS, and PSNS respectively. These
paragraphs uniformly present a TTO effluent limitation of 2.13 mg/L maximum for any one
day. No monthly average effluent limitation is established.
b. TTO for the metal finishing category includes 111 toxic organics, including solvents,
chlorinated hydrocarbons, pesticides, PCBs, and dioxin. The reportable value for the TTO
analysis is the sum of all concentrations for the 111 analytes greater than 0.01 mg/L.
c. Paragraph 433.12(a) provides that in lieu of TTO monitoring the permitting authority may
allow the permittee to certify on each DMR that there has been no dumping of
concentrated TTO into the wastewater stream.
d. Further, 433.12(a) provides that if TTO monitoring is required, the permittee may `analyze
for only those pollutants that would reasonably be expected to be present.'
e. Paragraph 433.12(b) provides that if the permittee selects the certification alternative to
TTO monitoring, he must submit a solvent management plan to the permitting authority's
satisfaction, and that the plan shall be incorporated as a part of the permit.
2. DWQ had established stormwater benchmark values for sixteen of the 111 toxic organics:
benchmark values of 0 ug/L for dioxin and for the 7 PCBs; anthracene - 0.005 mg/L;
pentachlorophenol - 0.019 mg/L; toluene - 0.055 mg/L and 0.0018 mg/L in trout waters; 1.0
mg/L for 2,4 -dimethylphenol and for naphthalene; acrylonitrile - 3.8 mg/L; phenol - 4.5 mg/L
in trout waters; and benzene - 6.7 mg/L.
The current draft permit provides as follows:
a. The permittee may elect to develop a solvent management plan and incorporate it in his
SPPP. All in imitation of the federal effluent guidelines for wastewater and pretreatment
discharges. Consistent with the previous version of the permits NCG03 and NCG10.
b. DWQ is willing to work with the permittee on alternate analyses and/or benchmarks to
satisfy the TTO monitoring requirement. This provision is parallel to, but not identical to,
the federal provision establishing that wastewater permittees need only analyze for the
pollutants reasonably expected to be present.
c. The benchmark is set at 1.0 mg/L. This is not a limit value in the sense that an
exceedence constitutes a permit violation. This is more like an action level value. DWQ has
benchmark values set for only a very small portion of the TTO suite. A value of 1.0 mg/L
corresponds to our benchmarks for naphthalene and 2,4 -dimethylphenol. Three
benchmark values are above 1.0 mg/L, and 11 benchmark values are below 1.0 mg/L.
d. DWQ may evaluate analysis results and determine if any chemicals are present at levels of
concern, even if below 1.0 mg/1, and require appropriate actions.
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NCG090000 Fact Sheet — NC DEQ August 6, 2018
APPENDIX D
Previous Data Analysis Summary, 2007
Summary of NCG090000 Monitoring Data provided by Julie's 4/12/07 DMR FileMaker file.
None of these data were eliminated, with the exception of a couple of "0" entries.
Data
Total
Units
Benchmark
Count of Event Precip.
129
Max of Event Precip.
4.03inches
Min of Event Precip.
0.1
inches
Average of Event Precip.
0.99inches
Count of Event Duration
128
Max of Event Duration
2448minutes
Min of Event Duration
0.5minutes
Average of Event Duration
76.30minutes
Count of Total Flow
125
Max of Total Flow
515MG
Min of Total Flow
OMG
Average of Total Flow
28.22MG
Count of Cadmium
115
Max of Cadmium
200
g/I
0.001 mg/I
Min of Cadmium
0.001
g/I
0.001 mg/I
Average of Cadmium
7.82
A g/l
0.001 m /I
Count of Chromium
116
Max of Chromium
1109
g/I
1 mg/I
Min of Chromium
0.005
g/I
1 mg/I
Average of Chromium
29.88
/I
1 m /I
Count of Lead Recovered
120
Max of Lead Recovered
200
g/I
.03 mg/I
Min of Lead Recovered
0.003
g/l
.03 mg/I
Average of Lead Recovered
16.49
/I
.03 m /I
Compiled by A. Lau
16 facilities have submitted monitoring data since 9/1/02, and as of 7/1/07
there were 16 active permits.
The data on this form represents all of the data submitted since the beginning of the program.
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NCG090000 Fact Sheet - NC DEQ
APPENDIX E
NCG090000 Data Analysis Summary, 2012
August 6, 2018
• Seventeen permittees reported 362 measurements on Cd, Cr, and Pb concentrations during the
5 -year term of NCG09.
• Only six vehicle maintenance data points were reported in the five-year permit term,
suggesting that most facilities do not meet the qualifying criterion of 55 gallons of new motor
oil per month.
• The number of reported exceedances of the heavy metals benchmarks is low, (only 10
out of 362 data points) suggesting that the industry is doing a pretty good job in
controlling heavy metal stormwater pollutants. However, the picture is confused by the
large number of unintelligible reports in the form of: 'below detection' or'<MDL' or'BRL' or
'non -detect' or similar useless notations that do not allow us to conclude that any particular
discharge was or was not below the benchmark value.
• Additionally confusing the picture, the data suggest several instances of the use of inadequate
method or reporting levels, i.e. the laboratory analytical tests were not run to levels equal to or
below the benchmark value. These instances should be considered exceedances.
• Additionally, some permittees identified in our database as having a valid permit have not
submitted any sampling results in the five-year term of the permit. This circumstance should
be viewed as a compliance problem for the specific facilities, and not necessarily a fair
characterization of other permittees in the industry.
• Tabulated data count
Reported values
Count
Percent
Comment
Exceedances
10
3%
Above benchmarks
Inadequate MDL
26
7%
Should be interpreted as a benchmark
exceedance
Indistinct MDL
79
22%
Physical facts are questionable, but in the form
received by DWQ, these reports cannot be
interpreted as below benchmarks.
Apparently below
247
68%
However, the data also seems to indicate some
benchmarks
possibility of permittee confusion on both the
mg/L vs. ug/L question and the appropriate MDL
question. Consequently upon closer inspection,
the count may be lower.
362
100%
Summary data -based conclusions and data -based draft permit actions:
o The industry may be doing a good job, but poor reporting procedures make the
industry -wide circumstances unclear. Revise permit text to require mg/L units and
to prohibit reporting"BRL', "<MDL', etc. Hope that with this extra guidance, the
next permit cycle produces data that will support clearer conclusions about the
industry's performance.
o Retain all three current heavy metal analytes.
Page 14 of 15

NCG090000 Fact Sheet — NC DEQ
Page 15 of 15
August 6, 2018