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NC Department of Environmental Quality | Division of Water Resources | Laboratory Certification Branch
4405 Reedy Creek Road | 1623 Mail Service Center | Raleigh, North Carolina 27699-1623
919-733-3908
September 9, 2022
5767
Mr. Justin Shell
Town of North Wilkesboro
PO Box 218
North Wilkesboro, NC 28659-0218
Subject: North Carolina Wastewater/Groundwater Laboratory Certification Branch (NC
WW/GW LCB) Maintenance Inspection
Dear Mr. Shell:
Enclosed is a report for the inspection performed on August 25, 2022 by Michael Cumbus. Where
Finding(s) are cited in this report, a response is required. Within thirty days, please supply this
office with a written item for item description of how these Finding(s) were corrected. Please
describe the steps taken to prevent recurrence and include an implementation date for each
corrective action. If the Finding(s) cited in the enclosed report are not corrected, enforcement
actions may be recommended. For Certification maintenance, your laboratory must continue to
carry out the requirements set forth in 15A NCAC 02H .0800.
A copy of the laboratory’s Certified Parameter List at the time of the audit is attached. This list will
not reflect any changes made during the audit. Copies of the checklists completed during the
inspection may be requested from this office. Thank you for your cooperation during the
inspection. If you have questions or need additional information, please contact me at (919) 733-
3908 Ext. 251.
Sincerely,
Anna Ostendorff
Technical Assistance & Compliance Specialist
Division of Water Resources
Attachment
cc: Todd Crawford, Beth Swanson, Michael Cumbus, Master File #5767
On-Site Inspection Report
LABORATORY NAME: Town of North Wilkesboro
NPDES PERMIT #: NC0020761
ADDRESS: 100 Thurman Street
North Wilkesboro, NC 28659
CERTIFICATE #: 5767
DATE OF INSPECTION: August 25, 2022
TYPE OF INSPECTION: Field Municipal Maintenance
AUDITOR(S): Michael Cumbus
LOCAL PERSON(S) CONTACTED:
Scott Perry and Justin Shell
I. INTRODUCTION:
This laboratory was inspected by a representative of the North Carolina Wastewater/Groundwater Laboratory
Certification Branch (NC WW/GW LCB) to verify its compliance with the requirements of 15A NCAC 02H
.0800 for the analysis of compliance monitoring samples.
II. GENERAL COMMENTS:
The facility is extremely neat and very well organized and has all the equipment necessary to perform the
analyses. Staff were pleasant and forthcoming and responded well to suggestions from the auditor.
The laboratory relinquished all non-Field parameters on July 7, 2022 and were reclassified as a Field
Municipal laboratory. Prior to this date, the laboratory was classified as a Municipal laboratory (Certificate
# 492).
All required Proficiency Testing (PT) Samples have been analyzed for the 2022 PT Calendar Year and the
graded results were 100% acceptable.
The laboratory submitted their Quality Assurance (QA) and/or Standard Operating Procedure (SOP)
document(s) in advance of the inspection. The laboratory is reminded that any time changes are made to
laboratory procedures, QA/SOP document(s) must be updated and relevant staff retrained. Staff must
acknowledge that they have read and understand the changes as part of the documented training
program. The same requirements apply when changes are made in response to Findings,
Recommendations or Comments listed in this report, to ensure the methods are being performed as
stated, references to methods are accurate, and the QA and/or SOP document(s) is in agreement with
each approved practice, test, analysis, measurement, monitoring procedure or regulatory requirement
being used in the laboratory. In some instances, the laboratory may need to create an SOP to document
how new functions or policies will be implemented. Revisions to the SOPs, based on the Findings,
Comments and Recommendations within this report must be submitted to this office by March 30,
2023.
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#5767 Town of North Wilkesboro
The laboratory is also reminded that SOPs are required to be reviewed at least every two years and are
intended to describe procedures exactly as they are to be performed. Use of the word “should” is not
appropriate when describing requirements (e.g., Quality Control (QC) frequency, acceptance criteria, etc.).
Evaluate all SOPs for the proper use of the word “should”.
Contracted analyses are performed by Meritech, Inc. (Certification # 165).
Approved Procedure documents for the analysis of the facility’s currently certified Field Parameters were
provided at the time of the inspection.
III. FINDINGS, REQUIREMENTS, COMMENTS AND RECOMMENDATIONS:
Documentation
A. Finding: Error corrections are not properly performed.
Requirement: All documentation errors shall be corrected by drawing a single line through
the error so that the original entry remains legible. Entries shall not be obliterated by erasures
or markings. Wite-Out®, correction tape, or similar products designed to obliterate
documentation are not to be used; instead the correction shall be written adjacent to the error.
The correction shall be initialed by the responsible individual and the date of change
documented. Ref: 15A NCAC 02H .0805 (g) (1).
Comment: Several instances were noted on the laboratory benchsheet where the sample
identification was replaced with the PT study, but the corrections were lacking the date and
initials of the analyst.
B. Finding: The laboratory is not documenting that the established acceptance criterion for the
pH check-standard buffer is being met.
Requirement: All laboratories shall use printable laboratory benchsheets. Certified Data shall
be traceable to the associated sample analyses and shall consist of: the quality control
assessments. Each item shall be recorded each time samples are analyzed. Analyses shall
conform to methodologies found in Subparagraph (a)(1) of this Rule. Ref: 15A NCAC 02H
.0805 (g) (2) (O).
Comment: The acceptance criterion of the check standard buffer is ± 0.1 S.U. A checkbox
used to indicate that the acceptance criterion had been met would meet this requirement. No
data reviewed during the inspection failed to meet this criterion.
Proficiency Testing
C. Finding: PT Samples are not being analyzed in the same manner as routine Compliance
Samples.
Requirement: Laboratories are required to analyze an appropriate PT Sample by each
parameter method on the laboratory’s CPL. The same PT Sample may be analyzed by one
or more methods. Laboratories shall conduct the analyses in accordance with their routine
testing, calibration and reporting procedures, unless otherwise specified in the instructions
supplied by the Accredited PT Sample Provider. This means that they are to be logged in and
analyzed using the same staff, sample tracking systems, standard operating procedures
including the same equipment, reagents, calibration techniques, analytical methods,
preparatory techniques (e.g., digestions, distillations and extractions) and the same quality
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#5767 Town of North Wilkesboro
control acceptance criteria. PT Samples shall not be analyzed with additional quality control.
They are not to be replicated beyond what is routine for Compliance Sample analysis.
Although, it may be routine to spike Compliance Samples, it is neither required, nor
recommended, for PT Samples. PT sample results from multiple analyses (when this is the
routine procedure) must be calculated in the same manner as routine Compliance Samples.
Ref: Proficiency Testing Requirements, February 19, 2020, Revision 5, Section 3.6.
Comment: The laboratory is currently analyzing PT Samples in duplicate, but not analyzing
compliance samples in duplicate. Sample duplicates are not required for Field Parameters.
D. Finding: PT Samples have not been distributed among all analysts from year to year.
Requirement: Laboratories shall also ensure that, from year to year, PT Samples are equally
distributed among personnel trained and qualified for the relevant tests and instrumentation
(when more than one instrument is used for routine Compliance Sample analyses), that
represents the routine operation of the work group at the time the PT Sample analysis is
conducted. Ref: Proficiency Testing Requirements, February 19, 2020, Revision 5, Section
3.6.
Comment: Two analysts are currently in the PT rotation. Laboratory staff commented that
there were two other employees who are currently not in the PT rotation but could potentially
analyze compliance samples. An acceptable grade on PT samples is noted in the SOP as
part of the training requirements.
Temperature – Standard Methods, 2550 B-2010 (Aqueous)
Comment: The laboratory is reporting temperature to one decimal place.
Recommendation: Unless greater precision is required by the permit or data receiving agency, it is
recommended that all temperatures reported for compliance monitoring, be reported in whole
numbers as recommended by the DWR’s Precision in Discharge Monitoring Reports document.
E. Finding: The compliance temperature-measuring device is not checked at two temperatures
that bracket the range of observed sample temperatures.
Requirement: Laboratory procedures shall comply with Subparagraph (a)(1) of this Rule. Ref:
15A NCAC 02H .0805 (g) (4).
Requirement: To check a compliance temperature-measuring device, compare readings at
two temperatures that bracket the range of compliance samples routinely analyzed against a
Reference Temperature-Measuring Device and record all four readings. The readings from
both devices must agree within 0.5 ºC. If they do not, the device may not be used for
temperature compliance monitoring. Ref: NC WW/GW LCB Approved Procedure for the
Analysis of Temperature. Please submit an acceptable verification with the report
Response.
Comment: The compliance temperature measuring device was verified at temperatures of
19.8°C and 14.2°C. During data review, temperatures that fell outside of this range were
noted. Examination of historical DMR temperature data will provide guidance on the range of
temperatures that need to be used for verification.
Reporting
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#5767 Town of North Wilkesboro
Comment: Prior to relinquishing certification for Ammonia Nitrogen, the laboratory was analyzing
samples by Standard Methods 4500 NH3 C-1990 (Nesslerization). Following the 2012 EPA Method
Update Rule, the laboratory’s Certified Parameter Listing (CPL) was updated to Standard Methods
4500 NH3 C-1997 (Titration) and later to Standard Methods 4500 NH3 C-2011 (Titration) without
anyone realizing that the technology had not been updated in response. There is no longer a
Nesslerization method in Standard Methods. However, the technology is still approved in 40 CFR
Part 136.3, Table IB. The laboratory has been passing PT samples using this method technology.
F. Finding: The laboratory does not report results of all tests on the characteristics of the effluent
when duplicate sample analyses are performed.
Requirement: The results of all tests on the characteristics of the effluent, including but not
limited to NPDES permit monitoring requirements, shall be reported on the monthly report
forms. Ref: 15A NCAC 02B .0506 (b) (3) (J).
Requirement: When only one dilution is duplicated, that would be included in the sample
calculation and not reported as separate result. When the entire dilution scheme for a
sample is duplicated or if more than one sample is collected in a single day, all results
must be reported. The DWR Water Quality Permitting Section has directed that those
results may be reported discretely, or a as a geometric mean. If reported discretely, the
highest value would go in the daily cell and the rest would go in the comment section. If
the geometric mean is reported, the comment section must indicate the reported value is
a geometric mean of either a duplicate sample or of multiple samples collected on that
day. Ref: NC WW/GW LCB Fecal Coliform Reporting Policy.
Comment: The laboratory was performing fecal coliform analyses by Colilert®-18 prior to
relinquishing parameter certification in July 2022. During the inspection, it was noted that
a fecal coliform sample collected January 5, 2022 was duplicated with results of 50
MPN/100 mL and 38 MPN/100 mL. A fecal coliform sample collected May 2, 2022 was
duplicated with results of 8 MPN/100 mL and 4 MPN/100 mL. In both cases, the laboratory
reported the higher of the two values in the daily cell but not the other value in the comments
section.
Recommendation: It is recommended that you contact the appropriate Regional Office for
guidance as to whether an amended DMR(s) will be required. A copy of this report will be
made available to the Regional Office.
G. Finding: Values for pH were reported that exceed the method specified accuracy of 0.1 units.
Requirement: By careful use of a laboratory pH meter with good electrodes, a precision of
±0.02 unit and an accuracy of ±0.05 unit can be achieved. However, ± 0.1 pH unit represents
the limit of accuracy under normal conditions, especially for measurement of water and poorly
buffered solutions. For this reason, report pH values to the nearest 0.1 pH unit. Ref: Standard
Methods, 4500 H+ B-2011. (6).
Comment: Per PT Vendor instructions, the PT Sample results should be reported to two
decimal places, which is an exception to the requirement for Compliance Samples.
Recommendation: The laboratory currently reports pH sample results to two decimal places.
It is recommended that the laboratory continue to measure and document sample results on
the benchsheet to two decimal places, and to round to the nearest 0.1 S.U. when reporting
results on the DMR.
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#5767 Town of North Wilkesboro
IV. PAPER TRAIL INVESTIGATION:
The paper trail consisted of comparing original records (e.g., laboratory benchsheets, logbooks, etc.) and
contract laboratory reports to Discharge Monitoring Reports (DMRs) submitted to the North Carolina
Division of Water Resources. Data were reviewed for Town of North Wilkesboro (NPDES permit #
NC0020761) for January, April and May 2022. No transcription errors were observed. The facility appears
to be doing a good job of accurately transcribing data.
V. CONCLUSIONS:
Correcting the above-cited Findings and implementing the Recommendations will help this laboratory to
produce quality data and meet Certification requirements. The inspector would like to thank the staff for
their assistance during the inspection and data review process. Please respond to all Findings and
include supporting documentation, implementation dates and steps taken to prevent recurrence
for each corrective action.
Report prepared by: Michael Cumbus Date: August 26, 2022
Report reviewed by: Tom Halvosa Date: August 31, 2022
Certificate Number:5767
Effective Date:7/7/2022
Expiration Date:12/31/2022
Lab Name:Town of North Wilkesboro
Address:100 Thurman Street
North Wilkesboro, NC 28659
North Carolina Wastewater/Groundwater Laboratory Certification
Certified Parameters Listing
Date of Last Amendment:
The above named laboratory, having duly met the requirements of 15A NCAC 2H.0800, is hereby certified for the measurement of the parameters listed below.
CERTIFIED PARAMETERS
INORGANIC
pH
SM 4500 H+B-2011 (Aqueous)
TEMPERATURE
SM 2550 B-2010 (Aqueous)
This certification requires maintance of an acceptable quality assurance program, use of approved methodology, and satisfactory performance on evaluation samples. Laboratories are subject to civil penalties and/or decertification for infractions
as set forth in 15A NCAC 2H.0807.