IDSE Report Reminder for Schedule 4 Systems: Stage 2 Disinfectants and Disinfection Byproducts Rule
December 2, 2010
Schedule 4 systems that have chosen the standard monitoring option under the Stage 2 Disinfectants and Disinfection Byproducts Rule (Stage 2 DBPR) are required to complete their standard monitoring by March 31, 2010 and must submit their Initial Distribution System Evaluation (IDSE) report by July 1, 2010.
The Stage 2 DBPR applies to all community water systems (CWS) and nontransient noncommunity water systems (NTNCWS) that either add and/or deliver water that has been treated with a primary or residual disinfectant other than ultraviolet light. Schedule 4 public water systems include CWSs and NTNCWSs serving fewer than 10,000 people and not belonging to a combined distribution system in which any system serves less than 10,000 people.
The Stage 2 DBPR requires some systems to complete an Initial Distribution System Evaluation (IDSE) to characterize disinfection byproducts (DBP) levels in their distribution systems and identify locations to monitor DBP’s throughout the distribution system. The rule builds on the Stage 1 Disinfectants and Disinfection Byproducts Rule (Stage 1 DBPR) by focusing on monitoring for and reducing concentrations of two classes of DBPs – trihalomethanes (TTHM) and five haloacetic acids (HAA5) in drinking water.
An important aspect of the Stage 2 DBPR is that NTNCWSs serving less than 10,000 people do not need to complete any of the IDSE options, but must conduct State 2 DBPR compliance monitoring. No later than October 1, 2013, Schedule 4 systems must begin complying with monitoring requirements of the Stage 2 DBPR. However, states may allow up to an additional 24 months for compliance with maximum contaminant levels for systems requiring capital improvements.
Systems that serve fewer than 500 people and have eligible TTHM and HAA5 data may have qualified for a VSS Waiver. VSS systems that have obtained waivers have no IDSE monitoring requirements but will still need to conduct Sage 2 DBPR compliance monitoring.
Under the Stage 2 DBPR, compliance with the maximum contaminant levels for TTHM of 0.080 milligrams per liter (mg/L) and for HAA5 of 0.060 mg/L will be calculated based upon a running annual average for each required disinfection byproduct (DBP) monitoring location. This is referred to as the locational running annual average (LRAA) and is a change over the previous regulation which calculated compliance based upon a system wide running annual average.
Connecticut reports 140+ Schedule 4 systems, New Hampshire 25 and Massachusetts 154. The agencies encourage public water suppliers to be in contact with the state programs prior to the compliance due dates if you have questions regarding the Stage 2 DBPR.
The Connecticut, Massachusetts, and New Hampshire regulatory contacts for the Stage 2 DBR are:
- Connecticut: Carissa Madonna, CT Department of Public Health, Drinking Water Section at 860-509-7333
- Massachusetts: Nicholas Anastas, MA Department of Environmental Protection, Boston Headquarters at 617-556-1157
- New Hampshire: Bob Mann, NH Department of Environmental Services, Drinking Water and Groundwater Program at 603-271-2953
Darlene H. Gurnon
dhgurnon@geoinc.com
