The following table provides a list of interpretive rules and policy statements issued by the NC WW/GW Laboratory Certification program. They are meant to clarify existing legislative rules or to provide guidance where a rule does not exist. Where multiple editions of a single reference source may be approved for reporting purposes and where these approved methods may have conflicting or unclear requirements, the NC WW/GW LC program may adopt a single policy based on a single edition to provide consistency in analytical reporting. Even when citing an alternate reference edition, laboratories must adhere to the NC WW/GW LC policy requirement. 

Policies with an asterisk (* ) beside it notate that this policy could be applicable to Field Laboratory certification, depending on what parameter methods a laboratory is certified for

Parameter Policy Revision
General Quality Control Correlation Coefficient for Linear Calibration Curves * 12/2014

Electrode Slope/Efficiency Documentation 


Electronic Data Storage, Signature and Reporting Policy *


Factory Set Curve Verification *

  In-line Meter Calibration/Verification * 2006
  Linear Dynamic Range/Linear Calibration Range Verification 11/2004

Manual Integration

  Required Documentation for Preservation and Hold Time * 10/2014
  Thermometer Calibration and Verification Policy * 8/2018
   Titrant Standardization * 5/2019
  Traceability of Chemicals, Reagents, Standards and Materials * 12/2009
  SW-846 Method Implementation 10/2018
  Weight Verification * 5/2008
  Matrix Spike 12/2019
  Chemical, Reagent and Consumable Expiration Policy* 1/2009
  Parameter Specific  
Ammonia/Fluoride Distillation* 4/2019
Bacteria Quanti-Tray Sealer Check 7/2013
  Fecal Coliform MF Consumables Testing 2/2017
  Fecal Coliform Reporting 5/2019
  Fecal Coliform Sample Bottle Sterility 9/2016
  Fecal Coliform MF Culture Positive 9/2016
  Bacteriological Reagent Water Testing 2/2018
  Fecal Sludge MPN Calculation 5/2019
BOD/CBOD Flagging QC Failures in BOD Data 8/2014
  BOD - Checking DO Meter for Drift 7/2012
  Seed Correction Factor Acceptance Criterion 4/2013
  Measuring BOD/CBOD Sample Volumes 4/2013
  Reporting Limit Policy 4/2013
  Neutralizing Total Residual Chlorine in BOD Samples 10/2014
CBOD CBOD GGA Standard Acceptance Criterion 11/2013
Chlorophyll Chlorophyll Sample Collection, Preservation and Holding Time Policy 


Conductivity Automatic Temperature Compensator (ATC) Verification * 2/2006
Free Available Chlorine FAC Hold Time * 6/2019
Oil & Grease Oil and Grease Duplicates 3/2016
Residue TSS Reporting Limit 9/2014
  TSS Blank Initial Constant Weight 7/2014
  TS and TDS Reporting Limit  3/2009
  TSS, TDS and TS Constant Weight/Drying Time Verification 2/2019
Turbidity Turbidity Standards * 12/2007
TRC  Total Residual Chlorine - Sealed Standards in a Field Setting * 10/2017
VAR Option 3 DO Measurement  9/2018
  Option 3 Minimum Sample Volume 9/2018


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