Laboratory - Frequently Asked Questions (FAQs) Listed below are frequently asked wastewater laboratory technical questions. If you have another question for this list, please email the IWEA Laboratory Committee at labcommittee@iweasite.org When did the USEPA Part 136 methods change and where can I find what tests were part of those changes? What is the hold time for setting up BOD’s taken from a composite sample? A set of Laboratory Standards have been established by the National Environmental Laboratory Accreditation Conference (NELAP).  There are several versions from different conferences.  What version of the standards is approved? What is the acceptable range for the Glucose-Glutamic Acid (GGA) standard for BOD analysis? Standard Methods for the Examination of Water and Wastewater requires duplicates to be run as part of a quality control program.  What is the frequency of duplicates? Does the Illinois EPA require laboratories to be certified under their Environmental Laboratory Accreditation Program?   When did the USEPA Part 136 methods change and where can I find what tests were part of those changes? The  last changes to 40CFR part 136  Guidelines Establishing Test Procedures for the Analysis of Pollutants ,was finalized in March of 2007.    The final rule was published in the Federal Register , volume 72, Number  47, Monday March 12, 2007 under Rules and Regulations.  Methods from the 18th, 19th, and 20th editions of Standard Methods were approved for many analytes. Part 136 Table 1B deleted some of the EPA Methods in wet chemistry and AA metals analysis.  Please read the footnotes at the end of the table for additional clarification.  What is the hold time for setting up BOD’s taken from a composite sample?  Table II of 40CFR136 Required Containers, Preservation Techniques, and Holding times, states the maximum holding time is 48 hours.  Please remember that the hold time starts at the end of the composite period.  Footnote number 4 states that “For a composite sample collected with an automatic compositor (e.g., using a 24-hour composite sampler), the holding time begins at the time of the end of collection of the composite sample”. A set of Laboratory Standards have been established by the National Environmental Laboratory Accreditation Conference (NELAP).  There are several versions from different conferences.  What version of the standards is approved? The current approved standards were effective July 5, 2003 .   It is listed as EPA/600/R-04/003.  The website is nelac-institute.org and contains the standards in PDF format. These current standards are used by NELAC institute accreditation bodies for the accreditation of environmental laboratories. What is the acceptable range for the Glucose-Glutamic Acid (GGA) standard for BOD analysis? According to Standard Methods 18th Edition Method 5210B the mean should be 198 mg/L plus or minus 30.5 mg/L.   The quality Control limit range then would be 167.5mg/l to 228.5 mg/L.  Also remember that sample dilutions must meet the criteria of a residual DO of at least 1.0 mg/L and a DO depletion of at least 2.0 mg/L.  Standard Methods for the Examination of Water and Wastewater requires duplicates to be run as part of a quality control program.  What is the frequency of duplicates? Duplicates need to be done on 10 percent of your samples.  The quality assurance section of Standard Methods also discusses how to set up control charts for your analysis.  Then you can determine warning and control limits for your duplicates as well as your spike recoveries. Does the Illinois EPA require laboratories to be certified under their Environmental Laboratory Accreditation Program? Participation in IL ELAP (Environmental Laboratory Accreditation Program) is voluntary except for any laboratory submitting community water supply compliance data to Illinois EPA, Bureau of Water, Compliance Assurance Section. Any laboratory submitting community water supply water compliance data must be accredited for those particular analytes. More information on ILAP is available at http://www.epa.state.il.us/labs/