NC0020656_Lab Inspection_20100609

ArA
NCDENR
North Carolina Department of Environment and Natural Resources
Division of Water. Quality
Beverly Eaves Perdue Coleen H. Sullins
Governor Director
June 9, 2010
133
Mr. Robert Ellis
Leith Creek WWTP Lab.
P.O. Box 249
Laurinburg, NC 28353-0249
Dee Freeman
Secretary
Subject: North Carolina Wastewater/Groundwater Laboratory Certification (NC WW/GW LC)
Maintenance Inspection
Dear Mr. Ellis:
Enclosed is a report for the inspection performed on April 28, 2010 by Ms. Tonja Springer and Mr. Chet
Whiting. Where finding(s) are cited in this report, a response is required. Within thirty days of receipt,
please supply this office with a written item for item description of how these finding(s) were corrected.
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 2H .0800.
Copies of the checklists completed during the inspection may be requested from this office. Thank you
for your cooperation during the inspection. If you wish to obtain an electronic copy of this report by
email or if you have questions or need additional information, please contact us at 919-733-3908.
Dana Satterwhite
Certification Unit Supervisor
Laboratory Section
Enclosure
cc: Tonja Springer
Fayetteville Regional Office
DENR DWQ Laboratory Section NC Wastewater/Groundwater Laboratory Certification Branch
1623 Mail Service Center, Raleigh, North Carolina 27699-1623
Location: 4405 Reedy Creek Road. Raleigh, North Carolina 27607-6445
Phone: [phone] FAX: [phone]
Internet: www.dwglab.org
An Equal Opportunity \Affirmative Action Employer Customer Service: 1-877-623-6748 www,ncwaterquality.org
DENR-FRO
PUN1.:62010
DVUQ
NorthCarolina
Naturally

LABORATORY NAME:
NPDES PERMIT #:
MAILING ADDRESS:
CERTIFICATE #:
DATE OF INSPECTION:
TYPE OF INSPECTION:
AUDITOR(S):
LOCAL PERSON(S) CONTACTED:
I.
INTRODUCTION:
On -Site Inspection Report
Leith Creek WWTP Lab
NC0020656
P.O. Box 249
Laurinburg, NC 28353-0249
133
April 28, 2010
Municipal Maintenance
Tonja Springer and Chet Whiting
Robert Ellis and Ricky Odom
This laboratory was inspected to verify its compliance with the requirements of 15A NCAC 2H .0800 for
the analysis of environmental samples.
II. GENERAL COMMENTS:
The lab was clean and well organized. The requirements associated with Findings A, E, F, G, H, I, J,
K, and M and are new since the last inspection. An Amendment to Laboratory Certification Application
was completed at the time of the inspection to add Total Residual Chlorine (Standard Methods 4500 CI
G) and remove Settleable Residue and Turbidity from the laboratory's certificate attachment.
III. FINDINGS, REQUIREMENTS, COMMENTS AND RECOMMENDATIONS:
General
A. Finding: Several instances of writing over a number as a means of error correction were
observed and indelible ink was not used for some of the data entries.
Requirement: All documentation errors must be corrected by drawing a single line through the
errorso that the original entry remains legible. Entries shall not be obliterated by erasures
or ,. ma'rkings., Wite-Out®, correction tape or similar products designed to obliterate
documentation` are not to be used. Write the correction adjacent to the error. The correction
muiniejnitiOed by the responsible individual and the date of change documented. All data
and log entries must be written in indelible ink. Pencil entries are not acceptable. Ref: North
Carolina Wastewater/Groundwater Laboratory Certification Policy.
Conductivity — Standard Methods, 18th Edition, 2510 B
Comment: The meter is calibrated with three standards and they are read back like samples. It is
recommended that the header be modified to read "cal/read" (Le., calibration/reading).

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#133 Leith Creek WWTP Lab
— Standard Methods, 18th Edition, 4500 H+ B
Dissolved Oxygen — Standard Methods, 18th Edition, 4500 0 G
Temperature — Standard Methods, 18th Edition, 2550 B
Comment: Samples are analyzed in -situ but two times (for sample collection and analysis) are
documented. If samples are analyzed in situ a statement can be documented at the bottom of the
benchsheet to indicate the sample collection and sample analysis times are the same and analysts
may record only one time.
pH —Standard Methods, 18th Edition, 4500 H+ B
Dissolved Oxygen — Standard Methods, 18th Edition, 4500 0 G
Temperature — Standard Methods, 18th Edition, 2550 B
Conductivity — Standard Methods, 18th Edition, 2510 B
B. Finding: Temperature corrections are not posted on the meters.
Requirement: Document any correction that applies (even if zero) on both the thermometer and
meter and on a separate sheet to be filed. Ref: North Carolina Wastewater/Groundwater
Laboratory Certification Policy.
pH - Standard Methods, 18th Edition, 4500 H+ B
C. Finding: The three pH- calibration buffers are read back like a sample and documented, but the
calibration of the pH meter is not documented.
Requirement: Supporting records shall be maintained as evidence that these practices are
being effectively carried out. All analytical records must be available for a period of five years.
Ref: 15A NCAC 2H .0805 (a) (7) and (a) (7) (G).
Ammonia Nitrogen — Standard Methods, 18th Edition, 4500 NH3 F
D. Finding: A distillation comparison study was performed on the influent samples but not on the
effluent.
Requirement: The titration method requires all samples to be distilled. For all other methods,
manual distillation is not required if comparability data on representative effluent samples are
on file to show that this preliminary distillation step is not necessary;, however, manual
distillation will be required to resolve any controversies. Ref: North Carolina Wastewater/
Groundwater Laboratory Certification Policy based upon Code of Federal Regulations, Title 40,
Part 136; Federal Register Vol. 72, No. 47, March 12, 2007; Table 1 B Footnote 6 . (See
attached document titled Ammonia/Fluoride Distillation Studies for guidance)
Recommendation: When performing the distillation study, it is recommended that the, lab spike
effluent samples with concentrations < 1.0 mg/L to yield measured values in the 1 — 5 mg/L
range.
E. Finding: Two mL of Ionic Strength Adjuster (ISA) solution is being used to elevate the sample
pH to above 11, but the volume is not documented.
Requirement: Record volume of 10N NaOH added in excess of 1 mL. Ref: Standard Methods,
18th Edition, 4500-NH3 F. (4) (e).
Comment: The ISA solution is used in place of the 10N NaOH solution.

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#133 Leith Creek VWVTP Lab
Comment: When the volume of 10N NaOH used for the samples is different than that used for
the calibration standards, this must be compensated for in the following calculation:
mg NH3— N/L =AxBx (100 + D)
(100 + C)
A= Dilution Factor
B= Concentration of NH3-N/L, mg/L, from calibration curve
C= Volume of 10N NaOH added to the calibration standards, mL
D= Volume of 10N NaOH added to sample, mL
F. Finding: After the addition of the ISA, the pH is not documented to be greater than 11.
Requirement: Add a sufficient volume of 10N NaOH solution (1 mL usually is sufficient) to
raise pH above 11. Ref: Standard Methods, 18th Edition, 4500-NH3 F. (4) (b).
Requirement: Supporting records shall be maintained as evidence that these practices are being
effectively carried out. Ref: 15A NCAC 2H .0805 (a) (7).
Comment: If the sample turns blue, it is assumed that the pH is above 11. A check box on the
benchsheet to indicate this will satisfy this requirement.
G. Finding: A calibration blank and calibration verification standard are not being analyzed at the
end of the run.
Requirement: The calibration blank and calibration verification standard (mid -range) must be
analyzed initially (i.e., prior to sample analysis), after every tenth sample and at the end of each
sample group to check for carry over and calibration drift. If either fall outside established
quality control acceptance criteria, corrective action must be taken (e.g., repeating sample
determinations since the last acceptable calibration verification, repeating the initial calibration,
etc.). Ref: North Carolina Wastewater/Groundwater Laboratory Certification Policy based upon
Standard Methods, 20tt' Edition, 1020 B. (10) (c), 3020 B. (2) (b), and 4020 B. (2).
H. Finding: The laboratory is not analyzing matrix spikes.
Requirement: Unless the referenced method states a greater frequency, spike 5% of samples
on a monthly basis. Laboratories analyzing .less than 20 samples per month must analyze at
least one matrix spike each month samples are analyzed. Prepare the matrix spike from a
reference source different from that used for calibration unless otherwise stated in the method.
If matrix spike results are out of control, the results must be qualified or the laboratory must
take corrective action to rectify the effect, use another method, or employ the method of
standard additions. When the method of choice specifies matrix spike performance acceptance
criteria for accuracy, and the laboratory chooses to develop statistically valid, laboratory -specific
limits, the laboratory -generated limits cannot be less stringent than the criteria stated in the
approved method. Ref: North Carolina Wastewater/Groundwater Laboratory Certification Policy.
(See attached document titled Matrix Spiking Policy and Technical Assistance for
guidance)
Total Residual Chlorine — Standard Methods, 18th Edition, 4500 CI G
Comment: Samples are analyzed in a field setting. A field setting is defined as: A location off the
primary facility grounds and/or at such a distance that sample collection and analysis could not be

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#133 Leith Creek WWTP Lab
achieved at the primary facility within the parameter holding. time (Le., 15 minutes). .Therefore, sealed
standards (liquid or "Gel -type") may be used for the daily standard curve verification. (See attached
document titled Guidance on Gel Standard Verification for guidance)
Comment: The range of the annual curve verification was 10 - 500 pg/L. The facility has a permit limit
of 28 µg/L. It is recommended that when the annual verification curve is done againto use the following
concentrations: 25, 30, 50, 200, and 400 µg/L.
Suspended Residue - Standard Methods, 18ti' Edition, 2540 D
I. Finding: A minimum dried residue weight gain of 1 mg is used to determine the reporting limit.
Requirement: Choose sample volume to yield between 2.5 and 200 mg dried residue. If
volume filtered fails to meet minimum yield, increase sample volume up to 1 L. If complete
filtration takes more than 10 minutes increase filter diameter or decrease sample volume. Ref:
North Carolina Wastewater/Groundwater Laboratory Certification Policy based upon Standard
Methods, 20th and 21 st Editions, 2540 D. (3) (b).
Comment: Since the publication of the Code of Federal Regulations; Title 40, Part 136; Federal
Register Vol. 72, No. 47, March 12, 2007, there is no longer an approved method that allows for
a 1 mg weight gain! -Currently, the minimum weight gain allowed is 2.5 mg. In instances where
the weight gain is Tess than the required 2.5 mg, the value must be reported as less than the
appropriate value based upon the volume used. For example, if 500 mL of sample is analyzed
and < 2.5 mg of dried residue is obtained, the value reported would be .< 5' mg/L. The minimum
reporting value is now established at 2.5 mg/L based upon a sample volume used of 1000 mL.
J. Finding: Filters are not weighed to a constant weight after initial washing nor is a dry filter blank
analyzed with each set of samples.
Requirement: If pre -prepared filters are not used, the method requires that filters must be
weighed to a constant weight after washing. In lieu of this- process, it is acceptable to analyze a
single daily dry filter blank (i.e., no additional rinsing during the analysis). The acceptance
criterion for the -blank is a weight change of Tess than 4% of the filter's initial weight or 0.5 mg,
whichever is less. Ref: North Carolina Wastewater/Groundwater Laboratory Certification Policy
based upon Standard Methods, 20th Edition, 2540 D. (3) (a).
Finding: The analytical balance weights have not been verified against ASTM standard
weights.
Requirement: ASTM Class 1 and 2 weights must be verified at least every 5 years. ASTM
Class 1 weights (20 g to 25 kg) and ASTM Class 2 weights (10 g to 1 mg) are equivalent to the
NBS Class S weights specified in 15A NCAC 2H .0805 (a) (7) (K). Ref: North Carolina
Wastewater/Groundwater Laboratory Certification Policy. (See attached document titled
Weight Verification for guidance)
Fecal Coliform — Standard Methods, 18th Edition, 9222 D
L. Finding: -No comparison test is conducted before a new lot of media and filters are put into
use.
Requirement: When a new lot of culture medium, membrane filters or a new source of
reagent -grade water is to be used, make comparison tests of the current lot in use (reference

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#133 Leith Creek VVWTP Lab
lot) against the new lot (test lot). As a minimum, make single analyses on five positive samples.
Ref: Standard Methods, 18th Edition, 9020 B. (3) (d).
Recommendation: It is recommended that the comparison tests be performed with a -culture
positive sample that will yield the desired 20 to 60 colonies. The culture positive sample should
be analyzed the day prior to the comparison testing to determine the appropriate dilution to
yield 20 — 60 colonies.
Fecal Coliform — Standard Methods, 18th Edition, 9222 D
Suspended Residue — Standard Methods, 18th Edition, 2540 D
M. Finding: The laboratory needs to increase the documentation of materials and reagents used
or made in the laboratory as well as procedures for standard and reagent preparation.
Requirement: All chemicals, reagents, standards and consumables used by the laboratory
must have the following information documented: Date received, Date Opened (in use), Vendor,
Lot Number, and Expiration Date (where specified). A system (e.g., traceable identifiers) must
be in place that links standard/reagent preparation information to analytical batches in which the
solutions are used. Documentation of solution preparation must include the analyst's initials,
date of preparation, the volume or weight of standard(s) used, the solvent and final volume of
the solution. This information as well as the vendor and/or manufacturer, lot number, and
expiration date must be retained for primary standards, chemicals, reagents, and materials
used for a period of five years. Consumable materials such as pH buffers, lots of pre -made
standards and/or media, solids and bacteria filters, etc. are included in this requirement.
Ref: North Carolina Wastewater/Groundwater Laboratory Certification Policy.
Biochemical Oxygen Demand — Standard Methods, 18th Edition, 5210 B
Recommendation: Many of the initial Dissolved Oxygen (DO) values observed during the data review
were in the range of 9.0 mg/L. While this is still within the acceptance criterion stated in the method, it
is at or near the maximum allowable saturation. It is recommended that samples near saturation be
vigorously shaken to remove the excess oxygen.
Recommendation: Many instances were observed where the seed corrections were in the range of
0.5 mg/L DO uptake. It is recommended that the laboratory adjust the amount of seed in an attempt to
raise the seed correctionsso that they fall within the optimum range of 0.6 — 1.0 mg/L DO uptake. This
would help to reduce the number of instances where the correction is below the optimum range.
Vector Attraction Reduction — Option 4: Specific Oxygen Uptake Rate
Comment: The Specific Oxygen Uptake Rate (SOUR) test must be conducted at the same
temperature that the digester is operating. The SOUR test must be temperature corrected to an
equivalent 20 °C value. The temperature correction equation is as follows:
SOUR20 = SOURT X 2(20-1)
where: T = sludge temperature in degrees Celsius
2 = 1.05 above 20°C
2 = 1.07 below 20°C
The Land Application Unit in the Division of Water Quality Aquifer Protection Section has a
spreadsheet thatcan be used to calculate the SOUR test. This spreadsheet can be found at:
http://portal. ncdenr. orq/web/wq/aps/Iau/reporti nq

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#133 Leith Creek WWTP Lab
IV. PAPER TRAIL INVESTIGATION:
The paper trail consisted of comparing laboratory bench sheets and contract lab reports to Discharge
Monitoring Reports (DMRs) submitted to the North Carolina Division of Water 'Quality: Data were
reviewed for February and March, 2010. The following error was noted:
Date
Parameter'
Location
Value on Benchsheet
Value on DMR
2/22/2010
Total Residual Chlorine
Effluent
12 µg/L
15 µg/L
In order to avoid questions of legality, it is recommended that you contact the appropriate Regional
Office for guidance as to whether an amended Discharge Monitoring Report will be required. A copy of
this report will be forwarded to the Regional Office.
V. CONCLUSIONS:
Correcting the above -cited findings and implementing the recommendations will help this lab to
produce quality data and meet certification requirements. The inspector would like to thank the staff for
its assistance during the inspection and data review process. Please respond to all findings.
Report prepared by: Tonja Springer Date: June 4, 2010
Report reviewed by: Jason Smith Date: June 8, 2010

AMMONIA/FLUORIDE DISTILLATION STUDIES (NC WW/GW LC Policy 01/15/2009)
The titration method requires all samples to be distilled. For all other methods, manual distillation is not
required if comparability data on representative effluent samples are on file to show that this
preliminary distillation step is not necessary; however, manual distillation will be required to resolve any
controversies. In the case of low concentration effluents, the samples must be spiked to allow for a
meaningful statistical comparison. It is recommended that samples with a concentration < 1.0 mg/L be
spiked to yield a value in the 1 - 5 mg/L range. Comparisons performed in this concentration range
should check within 20% RPD. Additional samples must be analyzed comparatively if the results do not
indicate approximately the same values for distilled and undistilled samples. It is recommended that
both the distilled and undistilled portions of the sample be analyzed by the same laboratory using the
same methodology. The following frequencies are required:
Municipal and Industrial Laboratories shall analyze initially four samples distilled and undistilled from
each discharge and; thereafter, analyze two samples a year from each effluent.
Commercial Laboratories shall analyze initially at least six samples distilled and undistilled, but at least
two samples from all waste types. Analyze one sample distilled and undistilled yearly from all wastes
types.
Ref: North Carolina Wastewater/Groundwater Laboratory Certification (NC WW/GW LC) Policy,
01/15/2009; based upon Code of Federal Regulations, Title 40, Part 136; Federal Register Vol. 72, No.
47, March 12, 2007: Table 1 B Footnote 6.
Guidance on Gel standard verification:
Purchased Gel -type or sealed liquid ampoule standards may be used for daily calibration verification
only. These standards must be verified initially and every 12 months thereafter, with the standard
curve. Note: It is only necessary to verify the gel or sealed liquid standard which falls within the
concentration range of the curve used to measure sample concentrations. For example, if you are
measuring samples against a low range curve, a 200 pg/L standard would be verified, and not the 800
pg/L standard since the 800 standard would be measured using a high range curve. Immediately.
following curve verification:
1. Zero the instrument with the gel blank.
2. Read and record gel standard values.
3. Assign the obtained values as the true value.
The assigned values will be used for the next twelve months, or until a new curve verification is
performed. The gel/liquid standard verification must be performed for each instrument on which they
are to be used. If multiple instruments and/or standard sets are used, each must have assigned values
specific for the instrument and standard set. Some commercial laboratory facilities may be able to
provide assistance with the field photometric meter curve verifications.

North Carolina Wastewater/Groundwater Laboratory Certification
Matrix Spiking Policy and Technical Assistance (4/6/2010)
Policy Statement
Unless the referenced method states a greater frequency, spike 5% of samples on a monthly basis. Laboratories
analyzing less than 20 samples per month must analyze at least one matrix spike (MS) each month samples are
analyzed. Prepare the MS from a reference source different from that used for calibration unless otherwise stated
in the method. If MS results are out of control, the results must be qualified or the laboratory must take corrective
action to rectify the effect, use another method, or employ the method of standard additions. When the method of
choice specifies MS performance acceptance criteria for accuracy, and the laboratory chooses to develop
statistically valid, laboratory -specific limits, the laboratory -generated limits cannot be less stringent than the criteria
stated in the approved method.
When spiking with multi -component standards, if the method does not specify the spiking components, the
Laboratory Control Spike (LCS) and MS must contain all analytes that are reported.
If the unspiked sample result is in the top 40% of the calibration range, the sample should be diluted and the MS
prepared using the diluted sample. The recovery of the MS samples must be bracketed by the calibration range.
The volume of spike solution used in MS preparation must in all cases be <_ 10% of the total MS volume. It is
preferable that the spike solution constitutes <_ 1% of the total MS volume so that the MS can be considered a
whole volume sample with no adjustment by calculation necessary. If the spike solution volume constitutes >1 % of
the total sample volume, the sample concentration or spike concentration must be adjusted by calculation.
Technical Assistance
Spike Preparation
The spike concentration may be set at either 5 to 50 times the Method Detection Limit (as determined by the
Method Detection Limit or MDL study) for the analyte, or at 1 to 10 times the ambient level (average concentration)
of the analyte in samples. There are 3 options for preparing spikes:
Option 1 (Recommended - easiest) - If the spike solution volume is equal to 1% or less of the total
sample volume, direct subtraction of the unspiked sample is allowed. When the volume of the standard
solution spiked into a sample or a sample extract is less than 1% of the total volume then the final
concentration need not be adjusted (e.g., 10 pL of spike solution added to a 1 mL final extract results in
only a negligible 1 % change in the final extract volume).
Option 2 - Adjust spike solution to a known volume with sample. In this case the sample concentration
must be adjusted: When the volume of spike solution exceeds 1% of the total MS volume the sample
concentration must be adjusted prior to determining spike recovery.
Option 3 (Not recommended — most difficult) - Add spike solution to a full volume sample. In this case,.
the spike concentration must be adjusted. When the volume of spike solution exceeds 1_% of the total MS
volume the spike concentration must be adjusted prior to determining spike recovery.

Spike Preparation Examples
Option 1 - If the spike solution volume is equal to 1 % or less of the total sample volume, direct subtraction of the
unspiked sample is allowed.
Option 1 Example:
0.5 mis of a 1000 mg/L standard spike added to 100 mis of sample has a theoretical value of 5 mg/L.
(A) The spiked sample recovery is 5.1 mg/L
(B) If the unspiked sample result is 0.5 mg/L
(C) Theoretical value is 5.0 mg/L
The Percent Recovery = spiked sample recovery (A) — unspiked sample result (B) divided by theoretical
value (C) X 100 or
5.1 — 0.5 X 100 = 92% recovery A — B X 100 = Percent recovery
5.0 C
Option 2 - Adjust spike solution to a known volume with sample. In this case the sample concentration must be
adjusted.
Option 2 Example 1:
10 mis of spike (concentration 50 mg/L) brought to 100 mis with sample the theoretical MS value is 5 mg/L.
(A) The spiked sample recovery is 5.1
(B) If the unspiked sample result is 0.5 mg/L
(C) % sample is 0.90 (sample volume used (90) divided by final volume (100))
(D) Theoretical value is 5.0 mg/L
The Percent Recovery = spiked sample recovery (A) — (unspiked sample result (B) x % sample (C))
divided by theoretical value (D) X 100 or
5.1 — (0.5 x 0.9) X 100 = 93% recovery A — (B x C) X 100 = Percent recovery
5.0 D
Option 2 Example 2: Larger spike volume
25 mis of spike (concentration 50 mg/L) brought to 250 mis with sample the theoretical MS value is 5
mg/L.
(A) The spiked sample recovery is 5.6
(B) If the unspiked sample result is 0.5 mg/L
(C) % sample is 0.90 (sample volume used (225) divided by final volume (250))
(D) Theoretical value is 5.0 mg/L
The Percent Recovery = spiked sample recovery (A) — (unspiked sample result (B) x % sample (C))
divided by theoretical value (D) X 100 or
5.6 — (0.5 x 0.9) X 100 = 103% recovery A — (B x C) X 100 = Percent recovery
5.0 D
Option 3'- Add spike solution to a full volume sample. In this case the spike concentration must be adjusted.
Option 3 Example:
5 mis of a spike (concentration 100 mg/L) is added to 100 mis of a sample (105 mis final volume).
(A) The spiked sample recovery is 5.1

(B)
(C)
(D)
If unspiked sample result is 0.5 mg/L
Spike conc. adjustment is 0.9524 (sample volume (100) divided by sample + spike volume (105))
Actual spike value is 4.7619 (Theoretical value (5 mg/L based on 100 ml sample) x C)
The Percent Recovery = spiked sample recovery (A) x (sample volume divided by sample volume + spike
volume (C)) — unspiked sample result (B) divided by Actual spike value (D) X 100 or
(5.1 x 100 )-0.5 (AxC) —B X100=91.5%
D
100+5 X 100 = 91.5% recovery
4.7619
Corrective Action/Qualifications for MS
Spike accuracy is usually based on a range of percent recovery (e.g., 80-120%). Refer to the method of choice for
specific acceptance criteria for the matrix spikes until the laboratory develops or adopts statistically valid,
laboratory -specific performance criteria for accuracy. If a MS fails, and the LCS is acceptable, qualify the data for
the MS sample. Repeated failures for a specific matrix may require use of an alternate method or method of
standard addition. Base the sample batch acceptance on the results of the LCS analyses (and other quality control
results) rather than the MS alone, because the matrixof the spiked sample may interfere with the method
performance. If a MS and the associated LCS fail, re -prepare and reanalyze affected samples.
Post Digestion Spikes (PDS)
Post Digestion Spikes (PDS) are used for some analyses (e.g., metals) to assess the ability 'of a method to
successfully recover target analytes from an actual sample matrix after the digestion process has been performed.
The PDS results are used with MS results to evaluate matrix interferences. The MS and PDS should be prepared
from the same environmental sample. A PDS is not to be analyzed in place of a MS. Post Digestion Spikes must
be reported as post -digested and must not be misrepresented as pre-digested spikes. (Exception: TCLP and
SPLP samples are always spiked post digestion.)
Corrective Action/Qualifications for Post Digestion Spikes
In general, if the MS recovery for an analyte does not fall within the quality control acceptance range but the PDS
recovery is acceptable, then a matrix affect (associated with the preparatory process) should be suspected and
the unspiked sample results must be qualified on the basis of the matrix spike recovery. However, when historical
data for the effect does not exist, the laboratory would normally be expected to perform a second digestion and
reanalysis of the MS to confirm the result. The result would be confirmed if the MS recoveries and PDS recoveries
for both sets of analyses were similar in magnitude and bias. When both the MS recovery and PDS recovery for a
particular analyte falls outside of quality control acceptance range in the same manner (i.e., the PDS and MS
failures are of similar magnitude and the direction of bias is the same), confirmatory analyses are unnecessary but
the data must be qualified.
Parameters Excluded from MS Requirements
Acidity
BOD/CBOD
Chlorophyll
Color — ADMI
Conductivity
Ignitability '
Paint Filter Test
pH
Salinity
Total Residual Chlorine
Alkalinity
Aquatic Humic Substances
All Bacteriological Parameters
Color - PtCo
Dissolved Oxygen
All Residues
Turbidity
Temperature
Sulfite
Vector Attraction Reduction (All Options)
(Field Laboratories
and
Field Setting analyses
are exempt.)

Weight Verification (NC WW/GW LC Policy 05/23/2008)
ASTM Class 1 and 2 weights must be verified at least every 5 years. ASTM Class 1 weights (20 g to 25
kg) and ASTM Class 2 weights (10 g to 1 mg) are equivalent to the NBS Class S weights specified in
15A NCAC 2H .0805 (a) (7) (K). Verification may be accomplished by:
1. Sending laboratory weights back to the manufacturer for recertification - reference weights shall
be calibrated by a body that can provide traceability to ASTM specifications, or
2. Checking laboratory weights against certified reference weights (i.e., weights that have been
recertified as above) and found to be within ASTM Class 1 or Class 2 tolerances (see table
below) - often the balance service technician may provide this service.
Note: Although some manufacturers will assign a one-year calibration due date, 5 years is considered
an acceptable calibration interval due to the limited use of the reference weight set.
Documentation of weight verifications or recertification must be maintained for 5 years. If the condition
of a weight(s) is in question at any time due to damage (e.g., corrosion, nicks, scratching, etc.), the
laboratory must have that weight(s) re -verified as described above.
Maximum tolerances (Ref. ASTM E 617-97, 2003)
Denomination
Maximum tolerance for
ASTM Class 1 and 2
weights, (± mg)
500 g
1.2
300 g
0.75
200 g
0.50
100 g
0.25
50g
0.12
30 g
0.074
20 g
0.074
10 g
0.074
5 g
0.054
3g
0.054
2 g
0.054
1 g
0.054
500 mg
0.025
300 mg
0.025
200 mg
0.025
100 mg
0.025
50 mg
0.014
30 mg
0.014
20 mg
0.014
10 mg
0.014
5 mg
0.014
3 mg
0.014
2 mg
0.014
1 mg
0.014