NC0041696_Staff Comments_20030919

NPDES DOCUHENT SCANNING COVER SIIEE '
NPDES Permit:
NC0041696
Lake Rhodhiss WWTP
Document Type:
Permit Issuance
Wasteload Allocation
Authorization to Construct (AtC)
Permit Modification
Complete File - Historical
Engineering Alternatives (EAA)
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Staff Comments'?
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Instream Assessment (67b)
Speculative Limits
Environmental Assessment (EA)
Document Date:
September 19, 2003
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content on the rezrerse side

Valdese and Huffman Finishing permit corrections
Subject: Valdese and Huffman Finishing permit corrections
Date: Fri, 19 Sep 2003 15:27:35 -0400
From: Jackie Nowell <[e-mail]>
Organization: NC DENR DWQ
To: Jim Reid <[e-mail]>
CC: Forrest Westall <[e-mail]>,
Dave Goodrich <Dave.Goodrich @ncmail.net>
Hello Jim,
Hope that all is well with you. I finally got a chance to check on the
June llth memo you sent to Dave on the subject permits. Valdese had a
permit mod in May 2002 after they submitted a request that DWQ
re-evaluate the need for mercury monitoring or limit. They submitted
twelve months of mercury data and after the analysis, we determined that
the mercury monitoring and limit could be dropped. Valdese is still
required to do quarterly Hg sampling in their Pretreatment LTMP and that
data must be reported on their DMR. That is probably the April 2003
data that was recorded. A letter and modified effluent pages were
mailed out on May 31, 2002 and the Asheville Regional Office along with
Point Source Compliance Unit were cc'd. Please let me know if your
Office did not receive a copy of the permit mod letter and I will
forward one to you.
Regarding Huffman Finishing, that effluent page is incorrect and it
should state quarterly monitoring for silver as in the permit cover
letter. Huffman obviously went by what was written in the letter and
not on the effluent page. I will be forwarding a corrected effluent
page which also reflects quarterly monitoring for total silver.
Hope this will clarify these issues.
1 of 1 9/19/03 3:50 PM

[Fwd: Town of Valdese - NC0041696 - Mercury testing method]
Subject:
Date:
From:
Organization:
To:
CC:
[Fwd: Town of Valdese - NC0041696 - Mercury testing method]
Tue, 02 Sep 2003 09:52:39 -0400
Jackie Nowell <[e-mail]>
NC DENR DWQ
"[e-mail]" <[e-mail]>
Jim Reid <[e-mail]>, Bob Sledge <[e-mail]>,
Dave Goodrich <[e-mail]>,
Tom Belnick <[e-mail]>, Dana Folley <[e-mail]>,
deborah gore <[e-mail]>
Mr. Bortnik,
As a followup to a phone call from Valdese a couple of weeks ago, I
have consulted with Tom Belnick of our office and Valdese will still be
allowed to monitor for mercury using EPA Method 245.1 as referenced in
the attached email. Upon expansion above 7.5 MGD permitted flow,
Valdese must immediately monitor for mercury using the new Method 1631.
If any questions, I can be contacted at 919-733-5083 ext. 512.
Subject:
Date:
From:
Organization:
To:
CC:
Mr. Bortnick,
Town of Valdese - NC0041696 - Mercury testing method
Tue, 28 Jan 2003 11:49:54 -0500
Jackie Nowell <[e-mail]>
NC DENR DWQ
[e-mail]
Shannon Langley <[e-mail]>, Jim Reid <[e-mail]>,
Roy Byrd <[e-mail]>, Dave Goodrich <[e-mail]>
Per our telephone conversation on January 27, 2003, the DWQ NPDES Unit has reevaluated the
mercury testing requirement for your Town. Valdese was sent the mercury requirement memo on
August 30, 2002, noting that effective September 1, 2003, you would be required to begin using EPA
Method 1631 because of either the mercury limit in your permit or your facility's IWC. Valdese
currently has a phased permit with permitted wastewater flows of: 1) 7.5 MGD with an IWC of 4.8%
and, 2)10.5 MGD with an IWC of 6.6%. The mercury memo was sent based on an analysis using the
higher flow of 10.5 MGD.
Valdese is currently operating under the 7.5 MGD effluent page and neither a mercury limit or
monitoring are required in the NPDES permit. A permit modification was made in May 2002 which
deleted the mercury limit at 7.5 and 10.5 MGD, based on effluent data submitted for evaluation.
However, you must monitor for mercury under the Pretreatment Program. Based on this information,
we will allow Valdese to continue to monitor for mercury in the Pretreatment Long Term
Monitoring Plan using the previous EPA Method 245.1 until the wasteflow goes above 7.5 MGD.
Upon expansion above 7.5 MGD, EPA Method 1631 must immediately be employed for any
mercury monitoring (or limits) required by the Town of Valdese.
Please contact me via email or call at 919-733-5083 ext. 512, if there are any questions.
1 of 1 9/2/03 10:33 AM

1N A TAR 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
Division of Water Quality
Jeffrey V. Morse
Town of Valdese
P.O. Box 339
Valdese, NC 28690
Dear NPDES Permittee:
August 12, 2003
Subject: NPDES Permit NC0041696 Mercury Requirement
EPA Method 1631 / Additional Information
Lake Rhodiss WWTP
Burke 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
NebENR
AlifWA

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 HCl 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
Sincerely,
Original 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

State of North Carolina
Department of Environment
and Natural Resources
Asheville Regional Office
Michael F. Easley, Governor
William G. Ross, Jr., Secretary
Alan W. Klimek, Y.E., Director
Division of Water Quality
WATER QUALITY SECTION
June 11, 2003
MEMORANDUM
TO:
Dave Dicke
Dave Goodrich
Forrest Westall
FROM: Jim Rei
ARO
SUBJECT: DMRs & BIMS
ATA
NCDENR
NORTH CAROLINA DEPARTMENT OF
ENVIRONMENT AND NATURAL RESOURCES
-11
JUN 2 4 2003
For the month of April 2003, BIMS showed monitoring violations for the
Town of Valdese (mercury, Hg) and Huffman Finishing Company (silver, Ag).
The Town of Valdese's permit does not contain a testing requirement for
mercury, and despite there not being a testing requirement, the Town did
report a result for mercury in April 2003. See attached copies of
Valdese's permit and monitoring report.
For Huffman Finishing Company, the monitoring requirement for silver is
contradictory. See attached copies of the facility's permit and
monitoring report for April 2003.
Your attention to this matter is appreciated.
59 Woodfin Place, Asheville North Carolina 28801 Telephone [phone] FAX [phone]
An Equal Opportunity Affirmative Action Employer 50% recycled/10% post -consumer paper

Town of Valdese - NC0041696 - Mercury testing method
Subject: Town of Valdese - NC0041696 - Mercury testing method
Date: Tue, 28 Jan 2003 11:49:54 -0500 '
From: Jackie Nowell <[e-mail]>
Organization: NC DENR DWQ
To: [e-mail]
CC: Shannon Langley <[e-mail]>, Jim Reid <[e-mail]>,
Roy Byrd <[e-mail]>, Dave Goodrich <[e-mail]>
Mr. Bortnick,
Per our telephone conversation on January 27, 2003, the DWQ NPDES Unit has reevaluated the
mercury testing requirement for your Town. Valdese was sent the mercury requirement memo on
August 30, 2002, noting that effective September 1, 2003, you would be required to begin using EPA
Method 1631 because of either the mercury limit in your permit or your facility's IWC. Valdese
currently has a phased permit with permitted wastewater flows of: 1) 7.5 MGD with an IWC of 4.8%
and, 2)10.5 MGD with an IWC of 6.6%. The mercury memo was sent based on an analysis using the
higher flow of 10.5 MGD.
Valdese is currently operating under the 7.5 MGD effluent page and neither a mercury limit or
monitoring are required in the NPDES permit. A permit modification was made in May 2002 which
deleted the mercury limit at 7.5 and 10.5 MGD, based on effluent data submitted for evaluation.
However, you must monitor for mercury under the Pretreatment Program. Based on this information,
we will allow Valdese to continue to monitor for mercury in the Pretreatment Long Term
Monitoring Plan using the previous EPA Method 245.1 until the wasteflow goes above 7.5 MGD.
Upon expansion above 7.5 MGD, EPA Method 1631 must immediately be employed for any
mercury monitoring (or limits) required by the Town of Valdese.
Please contact me via email or call at 919-733-5083 ext. 512, if there are any questions.
1 of 1 1/28/03 12:16 PM

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NC0041696
OF w A T Michael F. Easley, Governor
7G William G. Ross Jr., Secretary
7 North Carolina Department of Environment and Natural Resources
Alan W. Klimek, P.E., Director
Division of Water Quality
-71
rt
August 30, 2002
Subject: NPDES Mercury Requirement
Implementation of EPA Method 1631
Dear NPDES Permittee:
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/l; or 2) your facility has limited
instream dilution (i.e., the instream waste concentration (IWC) is >6%). This requirement complies with 15 A NCAC
2B.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/l), 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.
ATA
N. C. Division of Water Quality 1617 Mail Service Center Raleigh, NC 27699-1617 [phone]
Customer Service 1 800 623-7748
NCOENR

NPDES Mercury Requirement
Page 2 of 3
Additional Information
For additional information and guidance regarding EPA
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:
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
Maria Gomez Taylor, 202-566-1005
EPA Sample Control Center, 703-461-2100
Websites:
http://www.epa.state.oh.us/dsw/guidance/perrnitlOatt3.pdf
The state of Ohio EPA provides an updated listing of laboratories providing contract
Method 1631, including costs, turnaround time, and lab contacts. The labs are identified
purposes only, and do not constitute an endorsement. The listed commercial laboratories
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.
http: / /www.esb.enr.state.nc.us/lab
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.
iJWilliam Reid, PE
Supervisor, Point Source Branch
consult the
services for EPA
for informational
may also provide
Sincerely,
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
DWQ Aquatic Toxdcology 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
7

f
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.