Stage 2 Disinfectants and Disinfection Byproducts Rule Bruce Macler USEPA Region 9 415 972-3569 [email protected] H. Cl. Br. Cl. Bromodichloromethane. Stage 2 DBPR. Will ultimately require TTHM and HAA5 MCL compliance at each monitoring point in distribution system
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Applies to all CWSs and NTNCWSs that add a disinfectant other than UV, or deliver water that has been treated with a disinfectant other than UV
Consecutive systems are defined in the Stage 2 Rule as public water systems that buy or otherwise receive some or all of their finished water from one or more wholesale systems for at least 60 days per year.
All 3 systems must comply based on the schedule of System B
System serving 12,000
System C System serving 500
Sells water to. . .
Who treats and sells water to. . .
System serving 60,000
Monitoring and MCL violations are attributed to the PWS where the violation occurred
System A sells to System B and a violation occurs in System B
System B is in violation because it has the legal responsibility for complying with the MCL
System B may set up a contract with System A that details water quality delivery specifications
Very Small System Waiver
System Specific Study (SSS)
Standard Monitoring Program (SMP)
Schedule for systems in a combined distribution system is based on that of the largest system in the combined distribution system
(1) A dual sample set (i.e., a TTHM and an HAA5 sample) must be taken at each monitoring location during each monitoring period.
(2) Taken during peak historical month. The peak historical month is the month with the highest TTHM or HAA5 levels or the warmest water temperature.
(3) You must monitor at or near the entry point if you are a consecutive system. If you are not a consecutive system, you must monitor at a high HAA5 location.
High TTHM concentration
High HAA5 concentration
Monitoring LocationSelecting Near Entry Point Sites– Example
Water age, but also consider biodegradation
Areas with known biofilm growth
Areas with difficulty maintaining a residual
Good HAA5 sites
Downstream of booster chlorination
Sites with low but detectable residual
Areas of high historic levels
Downstream of tanks
Hydraulic dead ends and mixing zones
Areas with low water useSelecting High HAA5 Sites
Data Sources and Tools
Disinfectant residual, maps, models, etc.
Select Candidate Sites
If the Primacy Agency does not take action within 12 months from the date when the Plan was due, the system can consider the plan approved