AWWA ACE61749

AWWA ACE61749 Examples of the Alternate Approaches to IDSE Compliance
Conference Proceeding by American Water Works Association, 06/17/2005

Dowbiggin, William B.; Huggins, Russell L., Jr.; Brown, Stephen J.

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The Initial Distribution System Evaluation (IDSE) requirements of the Stage 2 Disinfection Byproducts Rule (DBPR) are applicable to all systems that add aprimary or residual disinfectant other than ultraviolet (UV) radiation to their water. Perthe proposed Stage 2 DBPR, the municipality's IDSE report will be due 2 years afterpromulgation of the rule for systems serving over 10,000 people and smaller systemsthat are purchasing or selling water to combined systems that include a member servingover 10,000 people (so small systems do their reports concurrent with the systemsthey are buying from). Systems serving less than 10,000 that do not buy or sell from acombined distribution system with a large member get 4 years to do the IDSE.The Proposed Stage 2 DBPR provides four alternatives for IDSE compliance. The first alternative is tocomplete the Standard Monitoring Program (SMP). The SMP entails 1 year ofdistribution system monitoring.The second alternative is to conduct a System-Specific Study (SSS). The SSS is to evaluate DBPconcentrations throughout the distribution system using data sources such ashistorical DBP and disinfectant residual data, water distribution system modeling,and tracer studies. The third alternative is touse a 40/30 Certification. If ALL TTHM compliance samples are less than or equalto 40 g/L and ALL HAA5 compliance samples are less than or equal to 30 g/Lduring the monitoring period specified in the final rule, then the utility may just certifythey have met this 40/30 requirement as their IDSE report. The proposed rule saidto use the two previous years, e.g. 2002 and 2003, for large systems. Since thisrule was delayed, these dates could change, so utilities should check the final rulefor these dates. The fourth alternative involves the very small system waiver. Any system serving less than 500 persons can applyto their state for a waiver.Examples of each of the first three approaches above are discussed in this paper and involve the Town of Cary, North Carolina, the Greater Cincinnati Water Works, and the Charleston Commissioners of Public Works. Thefourth option is straight-forward and only applicable to very small systems. Includes tables, figures.