NC0021156_Correspondence_20081015

Mr. Michael Moretz
Operator in Responsible Charge
Mt. Holly Wastewater Treatment Plant
PO Box 406
Mount Holly, North Carolina 28120
Subject
Dear Mr. Moretz:
Michael F. Easley, Governor
William G. Ross Jr., Secretary
North Carolina Department of Environment and Natural Resources
Coleen H. Sullins, Director
Division of Water Quality
October 15, 2008
New Total Residual Chlorine Compliance Level
As per our conversation today I am enclosing a copy of the Total Residual Chlorine
Compliance Level letter that was sent to all permittees in May 2008. I am sorry that you did not
receive a copy and apologize for any inconvenience. If you have any questions concerning the
enclosed letter, please do not hesitate to contact me at [phone].
Sincerely,
Marcia Allocco, MS
Environmental Chemist
Surface Water Protection
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Mooresville Regional Office Division of Water Quality Phone [phone] Customer Service
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May 1, 2008
To: NPDES Permittees
Subject: Total Residual Chlorine 50 ug/1 Compliance Level
Michael F. Easley, Governor
State of North Carolina
William G. Ross, Jr,, Secretary
Department of Environment and Natural Resources
Coleen H. Sullins, Director
Division of Water Quality
In a previous letter dated August 14, 2001, the Division of Water Quality (DWQ) notified
NPDES permittees that water/wastewater treatment facilities with Total Residual Chlorine
(TRC) effluent limits would be required to use analytical methods that produce detection levels
below their permit limit by July 1, 2002. [Note: TRC permit limits are typically set between 17
to 28 ug/1 for discharge to freshwater systems, and 13 ug/1 for discharge to saltwater systems].
This requirement was based on an Environmental Protection Agency (EPA) audit of the NC
enforcement program. It was also necessary to ensure water quality protection and compliance
with state monitoring regulations [15A NCAC 2B.0505(e)(4)].
Since that time, DWQ has received several inquiries regarding difficulties with the new
analytical methods, primarily focused on 1) lack of precision with field instrumentation at low
TRC levels for both water and wastewater treatment plants; and 2) manganese interference with
TRC measurement at several water treatment plants. Some facilities have overcome these
problems through various changes, such as: 1) switching dechlorination chemicals; 2) adding a
second dechlorination feed; 3) changing analytical methods; 4) incorporating manganese
correction; 5) switching to UV disinfection; 6) removing sludge from water treatment plant
settling basins. Also, the DWQ Laboratory Certification staff have provided extensive field
assistance for the new lab methods. Still, some analytical issues remain. In response to the
permittee's concerns, the Division is providing the following changes to its TRC requirements:
o TRC Compliance Level Changed to 50 ug/l. DWQ continued discussions with EPA
regarding analytical difficulties with TRC measurements, and in March 2008 received
EPA approval to allow a 50 ug/l TRC compliance level. This will not change the
analysis, annual verification of meter performance, or data reporting, but simply how the
reported values will be evaluated by DWQ from a compliance standpoint. Facilities will
still be required to report actual results on their monthly DMR submittals, but for
compliance purposes all TRC values below 50 ug/1 will be treated as zero. For example,
if the facility has a TRC limit of 17 ug/1 and reports a TRC value of 40 ug/1 on the DMR,
this value will be considered compliant under this new policy. This new compliance
level is effective March 1, 2008 (beginning with March 2008 DMR submittals).
DWQ will continue to incorporate TRC effluent limitations into NPDES permits for all
water/wastewater treatment facilities that discharge chlorine -bearing wastestreams to surface
waters. While this new TRC compliance level of 50 ug/1 is effective beginning March 1, 2008, it
will be incorporated into existing NPDES permits with TRC effluent limits upon permit renewal.
At that time, the following TRC footnote language will added to the Effluent Limitations Sheet:
"The facility shall report all effluent TRC values reported by a NC certified laboratory including
field certified. However, effluent values below 50 ug/1 will be treated as zero for compliance
purposes."
Division of Water Quality, Point Source Branch Telephone [phone] one
1617 Mail Service Center, Raleigh, North Carolina 27699-1617 FAX [phone] No Carolina
512 N. Salisbury Street, Raleigh, North Carolina 27604 On the Internet at http://h2c.enr.state.ncu5/ QtllrQl`J
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Page 2 of 2
May 1, 2008
TRC 50 ug/l Compliance Memo
DWQ reserves the right to modify this policy in the future as analytical methods evolve. If you
have questions about the content of this letter, please contact Tom Belnick at [phone],
extension 543. If you need assistance with your TRC analytical methodology, please contact
Gary Francies with the DWQ Water Quality Lab at [phone]
Sincerely,
Matt Matthews, Supervisor
Point Source Branch ,
2