r|        UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
\         *                       WASHINGTON, D.C. 20460

   imo"                                                                    WSG 155
                                                           Date Signed: March 28, 2002
                                     MAR 28 2002

                                                                              OFFICE OF
                                                                               WATER
 MEMORANDUM
 Subject:       Definition of a Significant Non-Compiler
 From;        Clive Davies, Acting Chief (_J><-*
               Drinking Water Protection Branch

 To:           Joe Theis, Acting Chief
               Municipal Branch

        Thank-you for the opportunity to review the Draft Guidance on Establishing the
 Definition of a Significant Noncomplier (SNC), dated January 15,2002.  Based on our review
 we do not have comments regarding the raicrobial or disinfection-by-products SNC definitions.
 We do have a few recommendations regarding the Chemical/Radiological SNC definition:

        To avoid redundancy, delete all references in your draft guidance to unreasonable risk to
        health (URTH). Currently, we are developing URTH definitions in the implementation
        manual for each rule if appropriate.

        To achieve broad consistency in definition of SNC for chemical/radiological
        contaminants, we recommend replacing the concentrations listed in the national data
        system - SDW1S - that define SNC. The following definition was developed for the
        radionuclides rale as part of the implementation guidance for that rule. Stakeholders
        believed it should be applied to all chemical/radiological rules:

        *      "A system is characterized as a SNC if it has a violation at concentrations of
               twice the Maximum Contaminant Level (MCL)."
               "A system monitoring once a year or more frequently is characterized as a SNC if
               it fails to monitor or report analytical results for two consecutive monitoring
               periods,  A system monitoring less frequently than once a year is characterized as
               a SNC if it fails to monitor or report the monitoring results in one monitoring
               period."
               For nitrate, we recommend making an exception to the rule and setting the SNC at
               the MCL. We make this recommendation because of the very slim factor of
               safety that was used to set this standard and because of nitrate's acute health
               effects.

        Thanks     for the opportunity to review this document. If you have further questions
 or need additional information, please contact Ron Bergman at 564-3823.
                               Internet Address (URL) • http://www.epa.gov
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