NC0047384_Correspondence_20030812

0fr W A 7-
F9 Michael F. Easley, Governor
QG William G. Ross Jr., Secretary
y North Carolina Department of Environment and Natural Resources
r
1 Alan W. Klimek, P.E., Director
-c Division of Water Quality
Arthur White
City of Greensboro
P.O. Box 3136
Greensboro, NC
Dear NPDES Permittee:
27402
August 12, 2003
Subject: NPDES Permit NC0047384 Mercury Requirement
EPA Method 1631 / Additional Information
T.Z. Osborne WWTP
Guilford County
In a previous letter dated August 30, 2002, your facility was notified of being subject to a new low-level mercury
analysis (EPA Method 1631) for NPDES monitoring requirements beginning September 1, 2003. The notification
letter was mailed to 155 subject facilities. Since that mailing, the Division has participated in several Mercury 1631
Workshops to provide the regulated community with information on the new analytical requirements and clean
sampling recommendations. Based on comments received at these workshops, the following items are intended to
clarify certain NPDES requirements for the 155 subject facilities.
1. Mercury Sampling and Compliance: It is recommended that facilities collect some effluent samples for Method
1631 analysis prior to the 9/1/2003 effective date, in order to gain experience with the recommended clean
sampling techniques as well as the analysis requirements. NPDES compliance will be judged using the new
method results beginning 9/1/2003.
2. What Samples are Subject to Method 1631: Beginning 9/1/2003, all effluent samples collected for mercury
from the subject facility are required to perform low level mercury analysis. This includes effluent samples
collected for any of the following requirements: a) monitoring specified in your "Effluent Limitations and
Monitoring Requirements" page of your NPDES permit; b) monitoring specified in your NPDES Pretreatment
Short Term Monitoring Plan (STMP) or Long Term Monitoring Plan (LTMP); and c) NPDES permit renewal
requirements. The effluent samples must be analyzed by a laboratory certified by the Division for Method 1631,
and effluent results must be submitted with the applicable monthly Discharge Monitoring Report (DMR).
3. Grab Sampling: The Environmental Protection Agency (EPA) currently recommends that mercury samples for
Method 1631 analysis be collected as grab samples, since automatic composite samplers may be more subject to
contamination. Therefore, the Division will allow permittees to collect single grab samples directly into lab -
provided sample bottles for permit requirements, even though the NPDES permit may specify "composite"
samples for mercury. The grab sample must be representative of the discharge.
4. Laboratory Reporting Level: Based on the Division's review of commercial laboratories currently performing
Method 1631, a majority of labs were reporting a minimum level of quantitation (ML) of either 1.0 ng/1 or less.
The Division will require an ML of 1 ng/1 beginning 9/1/2003, which is considered reasonable and economically
achievable.
5. Field Blank Collection: Method 1631 requires that a minimum of one field blank accompany each set of samples
collected from the same site at the same time. The field blank is used to identify contamination during sample
collection and transport activities. If mercury is present in the field blank at levels that would compromise reliable
measurement of mercury in the wastewater sample, you should assume that the effluent sample was contaminated
during collection or transit, and you will need to eliminate any source of contamination that has been identified.
The permittee shall report all effluent sample results on the applicable monthly DMR. If a field blank fails to
meet quality control criteria, the permittee should note that fact in the DMR Comments Section, and append the
lab sheet for that field blank. For those facilities sampling for mercury under a limited monitoring frequency
(quarterly or less, such as Pretreatment LTMP/STMP monitoring), you must resample if the field blanks are
outside quality control criteria. However, for those facilities with more frequent effluent monitoring requirements
N. C. Division of Water Quality 1617 Mail Service Center Raleigh, NC 27699-1617 [phone]
Customer Service 1 800 623-7748

NPDES Mercury Requirement
Page 2 of 2
(i.e., monthly or more frequent), resampling is not required if field blank quality control criteria are not achieved
for a given sample event. Refer to Method 1631, Revision E (Section 9.4.5.2- Quality Control- Field Blanks), for
specific quality control criteria regarding field blank acceptability and effluent sample reliability.
6. Field Blank Subtraction: Method 1631 provides for subtraction of field blanks (provided they meet quality
control criteria defined above) from the effluent sample result if deemed appropriate by a regulatory agency.
Upon review, the Division will not allow field blank subtraction from effluent samples for reporting purposes.
Based on a recent study using Method 1631 for wastewater samples collected at 38 wastewater treatment plants,
field blank concentrations were generally below the method quantitation level. Therefore, beginning 9/1/2003,
the permittee shall report the result of the effluent sample as provided by the certified lab, without field blank
subtraction, on the monthly DMR submission. In the event of a mercury limits violation, the permittee retains
the option to request remission of any penalty. If the permittee believes that the violation resulted from
background contamination as indicated by the field blank, the permittee will need to document that fact with field
blank quality control data.
7. Sample Preservation/Holding Times: Samples for total mercury analysis by Method 1631 must be collected in
tightly -capped fluoropolymer or glass bottles and preserved with BrC1 or HCI within 48 hours of sample
collection. The time to sample preservation may be extended to 28 days if a sample is oxidized in the sample
bottle. Samples must be analyzed within 90 days of sample collection.
If you have any questions about the contents of this letter, please contact the applicable Division staff listed below:
Mercury Method:
Certified Labs for Method 1631:
NPDES Permitting:
NPDES Compliance:
NPDES Pretreatment:
Roy Byrd
Fred Bone
Tom Belnick
Vanessa Manuel
Dana Folley
919-733-3908, extension 213
919-733-3908, extension 273
919-733-5083, extension 543
919-733-5083, extension 532
919-733-5083, extension 523
6PirA Signed By
David A. Goodrich
Alan W. Klimek, P.E.
cc (hardcopy): CLANC, c/o Lew Hicks, Environmental Chemist Inc., 6602 Windmill Way, Wilmington, NC 28405
DWQ Regional Offices, Water Quality
cc (email):
EPA Region 4, Madolyn Dominy, Marshall Hyatt
DWQ Water Quality Section; Regional Office Supervisors
DWQ Laboratory Section; Steve Tedder, Larry Ausley, Jim Meyer, Roy Byrd, Fred Bone
DWQ Modeling/TMDL, Michelle Woolfolk
DWQ NPDES Compliance, Vanessa Manual
DWQ Pretreatment Unit
DWQ NPDES Unit
NC League of Municipalities, Anita Watkins
NC Labs Certified for Method 1631e

NC0047384
Michael F. Easley, Govemor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.E., Director
Division of Water Quality
August 30, 2002
Subject: NPDES Mercury Requirement
Implementation of EPA Method 1631
Dear NPDES Pen-nittee:
Mercury continues to be a water quality concern throughout North Carolina. Fish consumption advisories and
impaired stream segments as a result of elevated mercury levels have been issued for several locations. NPDES
permittees have worked with the state to reduce potential risks from this pollutant, including tasks associated with
collecting and reporting more accurate data. The most commonly used laboratory analysis for total mercury (EPA
Method 245.1) has a method detection level of 0.2 ug/1, while the current water quality standard is an order of
magnitude lower at 0.012 ug/1. Thus, true compliance with the water quality standard could not be judged. A
more recently approved laboratory method (EPA Method 1631) should produce a detection level below the water
quality standard, which would allow the Division to assess potential water quality impacts from dischargers more
accurately. Therefore, this letter serves as notification to your facility that effective September 1, 2003, you will
be required to begin using EPA Method 1631 (or subsequent low-level mercury methods approved by EPA in
40 CFR 136) when analyzing for total mercury. Your facility is subject to this new requirement because either 1)
your facility has a current total mercury limit in its NPDES permit that is <0.20 ug/1; or 2) your facility has limited
instream dilution (i.e., the instream waste concentration (IWC) is >6%). This requirement complies with 15 A NCAC
213.0505(e)(4), which requires that "test procedures must produce detection and reporting levels below the permit
discharge requirements."
Mercury Laboratory Analysis - EPA Method 1631
On June 22. 1999, the US EPA approved a new analytical method (EPA Method 1631) for measuring very low
concentrations of mercury in water. Subsequent revisions to Method 1631 include Revision C (current approved
method) and Draft Revision D (scheduled for promulgation in October 2002). Method 1631 has a minimum level of
quantitation of 0.0005 ug/1 (0.5 ng/1). which is 400-times more sensitive than Method 245.1. The new method
requires a clean laboratory environment which generally requires some lab retrofitting; thus, many permittees will
likely contract a commercial lab to perform the analysis. Based on data compiled by Ohio EPA. commercial labs
that are currently analyzing for EPA Method 1631 charge between $50-90 per sample. with turnaround times
ranging from 5-28 days. Currently there is one commercial lab certified by North Carolina for EPA Method 1631.
However, it is anticipated that several additional labs will also offer this analysis in the future as the demand for
this method increases. When selecting a lab to perform low level mercury analyses, the permittee should review the
lab's performance, experience. and reliability with the method, as well as cost considerations. Attachment A
provides additional information on this method.
Mercury Clean Sampling Techniques - EPA Method 1669
The greatest risk of contaminating the wastewater sample for low-level mercury analysis is during the sample
collection effort. Thus. those facilities subject to EPA Method 1631 will also need to evaluate clean sampling
recommendations provided in EPA Method 1669. Attachment A provides highlights on this method.
NPDES Compliance
All mercury monitoring data submitted to the Division will be reviewed for compliance with current effluent limits.
If the permit contains monitoring only, the new method must still be used, and the need for a permit limit
will be evaluated at a later date by comparing a statistical evaluation of the effluent data with the water
quality standard and corresponding allowable effluent concentration. Therefore, the potential problem of
sample contamination cannot be overemphasized. since it could result in NPDES effluent limits for total mercury,
increased monitoring costs, and possibly unnecessary violations. All data submitted to the Division for NPDES
compliance monitoring requirements are the responsibility of the permittee. Therefore, facilities subject to this new
method are strongly encouraged to begin evaluating sampling methods and commercial labs before the deadline
date, to ensure that field staff are properly trained in the use of "clean sampling" techniques. and sampling and lab
procedures are fully developed to minimize sample contamination.
AiTA
NCDENR
N. C. Division of Water Quality 1617 Mail Service Center Raleigh, NC 27699-1617 [phone]
Customer Service 1 800 623-7748

NPDES Mercury Requirement
Page 2 of 3
Additional Information
For additional information and guidance
following resources:
North Carolina Division of Water Quality
Laboratory Analysis:
Lab Certification:
Clean Sampling:
NPDES Permitting:
Pretreatment::
US Environmental Protection Agency
Method 1631/1669 Questions:
regarding EPA Methods 1631/1669. the
Roy. Byrd. 919-733-3908. ext. 213
Lab Staff, 919-733-3908
Sandy Mort, 919-733-2136, ext 245
Tom Belnick. 919-733-5083. ext 543
Tom Poe, 919-733-5083, ext 522
permittee may consult the
Maria Gomez -Taylor. 202-566-1005
EPA Sample Control Center, 703-461-2100
Websites:
http: / /www.epa.state.oh.us/dsw/guidance/permitl0att3.pdf
The state of Ohio EPA provides an updated listing of laboratories providing contract services for EPA
Method 1631, including costs, turnaround time, and lab contacts. The labs are identified for informational
purposes only, and do not constitute an endorsement. The listed commercial laboratories may also provide
advice on training, equipment, and sampling techniques appropriate for Method 1631.
http: / /www. epa.gov/ost/methods/ 1631.html
This EPA site provides information on the 1631 Method requirements and implementation guidance.
httn://www.esb.enr.state.nc.usilab
This DWQ site provides information on EPA Methods (including 1669 clean sampling techniques). and a
listing of state -certified labs for EPA Method 1631.
http://www.h2o.enr.state.nc.us/NPDES/NPDESweb.html;click Documents
This DWQ website includes a copy of this letter plus a list of facilities currently subject to EPA Method
1631.
Conclusion
The Division realizes that changing the method of mercury measurement will not be without difficulty on the part of
the permittees. The requirement will affect approximately 155 facilities with mercury limits and/or monitoring
requirements. These permittees will need to evaluate available laboratories, costs, and sampling techniques. For
these reasons, the implementation date for EPA Method 1631 was delayed until September 1, 2003. The Division
thanks you for your cooperation and understanding in this matter. If you have any questions about the contents of
this letter, please contact the applicable staff listed above.
Sincerely,
th/-
J. William Reid, PE
Supervisor, Point Source Branch
cc (hardcopy): CLANC. c/o Lew Hicks. Environmental Chemistry Inc.. 6602 Windmill Way. Wilmington. NC 28405
cc (email): EPA Region 4. Marshall Hyatt. Scott Gordon. Roosevelt Childress
DWQ Water quality Section; Coleen Sullins, Regional Offices
DWQ Laboratory Section: Steve Tedder. Larry Ausley. Jim Meyer. Roy Byrd. Connie Brower
mg Aquatic Toxicology Unit. Sandy Mort
DWQ Pretreatment Unit. Tom Poe
DWQ Modeling/TMDL, Michelle Woolfolk
DWQ NPDES Compliance Unit. Shannon Langley
DWQ NPDES Unit
MCIC. Michael Johnson
NC League of Municipalities. Paula Thomas
Clean Water Fund of NC. Hope Taylor
Severn Trent.Lab. Ohio, Mark Bruce

-▪ e.
NPDES Mercury Requirement
Page 3 of 3
ATTACHMENT A
Summary of EPA Methods 1631/1669
Effluent samples collected for mercury may become contaminated by numerous routes, including: 1) metal -
containing labware, reagents, containers, and sampling equipment; 2) improperly cleaned or stored equipment; and
3) atmospheric mercury inputs in dirt and dust. Even human contact can be a source of mercury contamination
(e.g., mercury amalgam fillings in the mouths of lab/field personnel can contaminate samples directly exposed to
exhalation). Thus, it is essential that every effort be made to minimize sample contamination during collection. The
US EPA provides recommendations to minimize contamination during sample collection in EPA Method I669:
Sampling Ambient Water for Determination of Trace Metals at EPA Water Quality Criteria Levels. This guidance
describes a "clean hands/dirty hands" sampling technique to collect mercury samples, which is ideally performed
with two people. A designated "clean hands" sampler handles all operations involving direct contact with the
sample bottle, while the "dirty hands" sampler is responsible for all activities that do not involve direct contact with
the sample bottle. This team sampling technique is recommended as a means to minimize sample contamination,
but is not required. The US EPA is developing a trace metal sampling guidance strictly for effluent collection
(Method 1670). The permittee will need to evaluate the various sampling recommendations and develop a sampling
strategy appropriate for their particular situation. The overall philosophy behind any mercury sampling strategy
should be to ensure that any object or substance that contacts the sample is nonmetallic and free from any
material that may contain metals, in order to produce a reliable mercury measurement.
Requirements and recommendations for EPA Method 1631
and clean sampling for low level mercury include:
• It is strongly recommended that the permittee discuss sample collection, preservation, and shipping
requirements with their laboratory, to ensure that the most current requirements of Method 1631 will
be met. There have been several revisions to EPA Method 1631, and Revision D is proposed.
• Each laboratory must perform and meet the minimum requirements of Method 1631 Quality Control.
• Effluent samples for mercury analysis must be collected in clean fluoropolymer or borosilicate glass
containers. It is recommended that the permittee request appropriate clean sample bottles or a
mercury sampling kit from their lab.
• Method 1631 requires that a minimum of one field blank accompany each set of samples collected at a
given site. The field blank is used to identify contamination from sample collection and transport. If
mercury is present in the field blank at levels that would compromise reliable measurement of mercury
in the wastewater sample, you should assume that the sample was contaminated during collection or
transit, and you will need to eliminate any source of contamination that has been identified and
possibly resample. Including the field blank, the permittee should budget for two samples per
monitoring event.
• Samples must be preserved or analyzed within 48-hours after collection. Samples do not need to be
refrigerated/iced during shipment provided they are tightly capped. shipped overnight to the lab, and
preserved or analyzed by the lab within 48 hours of collection (per Draft Revision D).
• If the samples are preserved within 48 hours, then they have a maximum holding time of 90 days prior
to analysis (per Draft Revision D).
• Sampling personnel must wear clean, non -talc latex gloves during sample collection and handling.
• EPA currently recommends that mercury samples for Method 1631 analysis be collected as grab
samples, since automatic composite samplers may be subject to contamination and loss of mercury via
volatilization. Therefore, the Division will allow permittees to collect single grab samples directly into
lab -provided sample bottles for permit requirements. The grab sample must be representative of the
discharge.
• If the person collecting the sample cannot directly reach the wastewater stream, a pole -type sampler
may be attached to the sample bottle to extend the reach for sample collection. The pole and bottle
clamp should be made of plastic and/or stainless steel and the mouth of the bottle should be held
facing upstream of the pole. The use of a transfer vessel should be avoided.
• All sampling equipment must be nonmetallic, or free of material that may contain metals. All materials
that will directly or indirectly contact the sample must be cleaned using the procedures in Method
1631.
• To minimize atmospheric contamination, do not sample during rainy weather or when the wind could
blow dust particles into the sample bottle. To minimize human contamination, do not breathe into the
sample bottle if you have mercury amalgam fillings in your teeth.
• Sampling personnel should be trained in techniques for sampling mercury at low levels. Sample
collection via the "clean hands/dirty hands" technique is recommended, but not required.
• Since Method 1631 is performance -based. there is some flexibility in Method requirements.
.•
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