# Presentation: 629539

## Stage 2 Disinfection Byproduct Rule Proposal 

## Stage 1 Disinfection Byproducts Rule (DBPR)

- DBP MCLs:
- TTHM 80 ug/L as a running annual average (RAA)
- HAA5 60 ug/L as an RAA
- Bromate 10 ug/L as a RAA
- Enhanced Coagulation/Softening Treatment Technique requirement.

## Stage 2 DBPR Regulatory Development Process

- EPA negotiated with a Federal Advisory Committee which developed recommendations
- FACA met from 3/30/99 to 9/6/00
- 21 members from different stakeholder groups
- Data analysis
- treatment and occurrence data: ICR, National Rural Water Survey, Supplemental Surveys, State data
- Cost analysis
- Focus of DBP health concern on reproductive & developmental health effects.

## Why is the Stage 2 DBPR Needed?

- DBP reproductive & developmental health effects
- Epidemiology studies:  miscarriage, stillbirth, birth defects, low birth weight.
- Not enough data to prove causality or estimate dose levels but epidemiological studies suggest that DBPs are likely to be reproductive toxicants under appropriate exposure conditions.
- Toxicology studies.
- Toxicology screening studies suggest that some DBPs may be reproductive/developmental hazard
- DBP cancer health effect risks
- DBP levels at some sites regularly exceed MCL

## Stage 2 M-DBPR Advisory Committee Recommendations

- Stage 2 DBPR & LT2ESWTR negotiated together.
- Agreement in Principle signed September 2000.
- http://www.epa.gov/fedrgstr/EPA-WATER/2000/December/Day-29/w33306.htm
- Consensus on Stage 2 DBPR recommendations
- Phased MCLs:  locational running annual average
- LRAA = annual average at each monitoring site
- Phase 1:  TTHM/HAA5 = 120/100 ug/L
- Phase 2:  TTHM/HAA5 = 80/60 ug/L
- Initial distribution system evaluation (IDSE) to find new compliance monitoring sites at points with highest DBP levels.
- System compliance schedules

## Basis for LRAA & IDSE

- Intent of rule is to focus on DBP peaks
- Peaks in DBP levels in distribution system when compliance based on RAA.
- Populations in different parts of the distribution system will receive equitable health protection.
- Do Stage 1 DBPR compliance sites capture the highest DBPs in the distribution system?
- Maximum residence time locations do not always capture highest DBP occurrence.
- TTHM & HAA5 highest levels often occur in different places.

## Who is Required to Comply with the Stage 2 DBPR? 

- Community and nontransient noncommunity water systems that add a primary or residual disinfectant other than ultraviolet light or deliver water that has been treated with a primary or residual disinfectant other than ultraviolet light.

## System Compliance Requirements

- Stage 2 DBPR is very similar to Stage 1 DBPR
- Change in compliance calculation from RAA to LRAA
- Routine monitoring on same schedule
- Some systems will monitor at one extra site.
- new sites determined by IDSE
- Same type of reduced monitoring provisions for systems with low DBPs
- IDSE
- Monitoring for 1 year or site-specific data study
- Opportunities for waivers and monitoring outs
- Small systems consecutive to large systems are required to comply on the same schedule as the larger system.

## IDSE Monitoring Requirements

- Guidance for states and systems on how to select IDSE monitoring sites.
- 	Draft guidance manual will be available at the time of proposal 		for recommendations from states and systems.

## Phased MCL Requirements

- Phase 1 (monitor at Stage 1 DBPR sites)
- TTHM MCL = 120 ug/L as a LRAA
- HAA5 MCL = 100 ug/L as a LRAA
- Systems must continue to comply with Stage 1 DBPR RAA 80/60 ug/L MCLs
- Phase 2 (monitor at new sites selected from IDSE)
- TTHM MCL = 80 ug/L as a LRAA
- HAA5 MCL = 60 ug/L as a LRAA
- Systems must monitor approximately every 90 days

## Routine Monitoring Requirements

- *   Sys 500-9,999:  State may determine that highest HAA5 & highest TTHM are at same location.
- ** Sys <500:  State may determine that highest HAA5 & highest TTHM are at different locations.

## Compliance Schedules*   Simultaneous compliance with LT2ESWTR

## EPA Rule Development Schedule 

- Draft Guidance Manual for IDSE at Proposal
- Proposal Late 2001
- Final Rule Statutory Deadline May 2002
- Consistent with statutory requirements for risk balancing, EPA will finalize a Long Term 2 Enhanced Surface Water Treatment Rule along with the Stage 2 Disinfectants and Disinfection Byproducts Rule, to ensure a proper balance between microbial and disinfection byproduct risks (Section 1412(b)(5)).