Impact/Purpose:

Establish optimum performance criteria for current TOC technologies for application to Stage 2 D/DBP Rule.

Develop a TOC and SUVA (incorporating DOC and UV254) method to be published in the Stage 2 D/DBP Rule that will meet requirements as stated in the Stage 1 D/DBP Rule (Revise Method 415.3, "Measurement of Total Organic Carbon, Dissolved Organic Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water", to include additional ruggedness data, method study data, and a combustion TOC procedure).

Investigate the cause for instrument response differences as observed between different kinds of TOC instrument systems.

Develop a method procedure that will control and/or eliminate the cause of TOC instrument response differences.

Revise Method 415.3 Quality Control section to include additional controls for the minimization and/or the elimination of instrument response differences.

Publish Method 415.3 and document in a journal article the development of the method.

Description:

The purpose of this project is to provide a total organic carbon (TOC)/specific ultraviolet absorbance (SUVA) method that will be used by the Office of Ground Water and Drinking Water (OGWDW) to support monitoring requirements of the Stage 2 Disinfectant/Disinfection By-products (D/DBP) Rule. The Stage 2 Rule requires that enhanced water treatment be used if the source water is high in aquatic organic matter prior to the application of a disinfectant. Disinfectants (chlorine, ozone, etc.) are used in the production of drinking water in order to reduce the risk of microbial disease. These disinfectants react with the organic material that is naturally present in the source water to form disinfection by-products (DBPs). Exposure to some of these by-products may pose a long term health risk. The number and nature of DBPs make it impossible to fully characterize all of the by-products formed during the treatment of drinking water and it is more cost effective to reduce formation of DBPs than to remove them from the water after they are formed. Two measurements (TOC and SUVA) are believed to be predictive of the amount of by-products that can be formed during the disinfection of drinking water and are considered to be surrogates for DBP precursors. SUVA is calculated as the ultraviolet absorption at 254nm (UV254) in cm-1 divided by the mg/L dissolved organic carbon (DOC) concentration (measured after filtration of the water through a 0.45um pore-diameter filter) and multiplied by 100. As a result, the OGWDW included a requirement in the Stage 1 Disinfectant/Disinfection By-products (D/DBP) Rule for large systems using conventional filtration treatment to remove a certain percentage of the TOC between their source water and the combined filter effluent. If the water has a SUVA concentration at or below 2 L/mg-m, then the TOC removal requirement may be waived. However, the current TOC, DOC, and UV254 methods do not include enough quality control and sample collection/preservation requirements to ensure that laboratories perform these analyses reliably. Therefore, OGWDW has requested a TOC and SUVA (incorporating DOC and UV254) method for the Stage 2 D/DBP Rule that will provide the precision and accuracy necessary to demonstrate compliance with the Stage 1 D/DBP Rule requirements. OGWDW has also requested that the precision and accuracy that can be achieved under controlled laboratory conditions for current TOC technologies be documented and evaluated. In addition, recent studies have shown that relatively large instrument response differences exist between different kinds of TOC instrument systems when analyzing the same source water matrix. These instrument response differences were noted when analyzing source waters under controlled experimental conditions. The OGWDW requested that the cause for the instrument response differences be investigated and that the cause be minimized or eliminated and documented in the new method. This important addition to the method will directly affect the quality of the monitoring data as required by Stage 1 and 2 Rule and help ensure safe drinking water.

Record Details:

Record Type:PROJECT

Start Date:09/01/1997

Projected Completion Date:09/01/2005

OMB Category:Other

Record ID: 18287

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Project Information:

Progress :Research under this task has been completed with the development of U.S. EPA Method 415.3 entitled "Determination of Total Organic Carbon, and Specific UV Absorbance at 254 nm in Source Water and Drinking Water". The task is remaining open in FY05 while a journal article describing the research is completed and published.

Research history:

Method 415.3 was submitted for external peer review in December, 2002 (2 EPA reviewers including a representative of OGWDW and 3 independent external reviewers). All the comments and suggestions of the reviewers have been reconciled and the method has been completed. The final peer reviewed Method 415.3 was delivered to Office of Ground Water and Drinking Water (OGWDW) in July, 2003. The Method 415.3 is posted on the web at: http://www.epa.gov/nerlcwww/ordmeth.htm.

The authors of Method 415.3 have drafted a journal article that will provide the drinking water utility community with the scientific background for the development of the TOC/SUVA method. It will be submitted to a scientific journal in FY05. The journal article will document the scientific reasons for the additional quality control provisions of the Method 415.3 and the reason for the inorganic removal procedure of that method. Of particular significance to the scientific community is that consistent TOC and DOC measurements can be made. Many scientists have raised concerns that different instrument types do not produce consistent data for TOC and DOC measurements when analyzing the same water matrices. The journal article will provide a reason for these inconsistent responses and provide corrective procedures that will improve instrument relative response differences.

The project files were prepared for archive in FY04.

The EPA Method 415.3 was submitted for public comment in the Federal Register in FY04. Comments were favorable. The Method is expected to be promulgated sometime in FY05.

Relevance :The EPA Office of Ground Water and Drinking Water (OGWDW) needed a total organic carbon (TOC) method that could meet the monitoring requirements as promulgated in the Stage 1, Disinfection By Products (D/DBP) Rule, as stated in the Federal Register. The TOC and SUVA method was needed by OGWDW for inclusion in the Stage 2, Disinfection By-Products (D/DBP) Rule proposal. The OGWDW needed an optimized method for the regulatory decision point (2 ppm TOC, or 2 L/mg-m SUVA) for the treatment of source water for the removal of DBP precursors. The need for the TOC method by July 2001 was delayed in order to investigate differences which were discovered in the relative instrument responses between the five different TOC instrument systems.

The Principle Investigator (PI) confirmed that there were many published papers on the subject of TOC instrument response differences and that it was a concern with many researchers. Because of the potential impact on the Stage 2 Rule, the PI consulted with and shared experimental data on instrument response differences and the possible causes with OGWDW. As a result of these findings, the delivery of the product (EPA Method 415.3) to the client (OGWDW) was delayed to ensure that TOC/SUVA method would not be flawed and result in a poor regulation of the utilities under the Stage 2 D/DBP Rule.

In summary, the delivery of EPA Method 415.3 will now allow consistent data of known quality to be collected and will have the outcome of supporting a fair regulation for the drinking water industry. Furthermore, it will provide TOC/SUVA data for enhanced water treatment that will reduce DBP precursors, control treatment costs, and protect the drinking water consumer.

Clients :Office of Ground Water and Drinking Water (Pat Fair)

Research Component :M/DBP (DBP)

Risk Paradigm :EXPOSURE

Project IDs:

ID Code :EX.D.3

Project type :ORD-DW Plan

ID Code :399

Project type :OMIS