NC0024571_TRC for DMRQA-21 Study_20020116

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January 16, 2002
Mr. Jim Meyer
NCDENR Laboratory Section
1623 Mail Service Center
Raleigh, NC 27699-1623
SUBJECT: Corrective Action on TRC for DMRQA-21 Study
Dear Mr. Meyer,
JN•2 22002
The City of Lumberton participated in the DMRQA-21 Study for Laboratory Certification and results
were mailed to ERA on 9/10/01. Results were received from ERA 12/10/01 with a Performance Evaluation
of "Not Acceptable" for Total Residual Chlorine. Total Residual Chlorine was analyzed for this study on
7/19/01 using Standard Methods 4500-CL I (Iodometric Electrode Technique). On 7/25/01, a Laboratory
Certification Maintenance Inspection was performed by Fred Bone and he informed us that this method did
not provide linearity at calibrations below 1.0 mg/1. The calibration performed for the DMRQA-21
Standard was 0.1 'to 1.0 mg/I. Thus"the 'problem 'was identified after analysis of the PE Standard for TRC.
This method was determined to not be sensitive enough for the concentration being measured.
Upon identification of the problem, I began seeking appropriate technology to be able to determine TRC
levels in the correct analytical range and that demonstrated a linearity coefficient of .995 or greater; On
8/20/01, the City of Lumberton implemented the State approved Standard Methods 4500-CL G (DPD
Colorimetric Method), for Total Residual Chlorine analysis.
To demonstrate Corrective Action for the "Not Acceptable" PE Standard for TRC, the City of Lumberton
requested a QuiK Response Blind PE Standard from ERA and analyzed using the new Standard Methods
4500-CL G on 1/9/02. Results received on 1/14/02 showed a report of "Acceptable" for Total Residual
Chlorine.
The City of Lumberton Laboratory strives to maximize the accuracy and quality of our analytical results. If
you have any questions for comments, please contact me at [phone].
Sincerely,
Karen H. Lewis
Laboratory' Supervisor
cc: Frederick L. Bone
e/Belinda Henson (Fayetteville Regional Office)
!P. D. Dax 1388, J. U,ntE2ton, wortr eaaottna 28359 • 91 o-671-3858 • 910-671-3889 • 9ax 910-671-3814