The Stage 2 Disinfection By-Product Rule becomes effective for public water systems based on the following chart. All systems serving 50,000 or less in population will begin Stage 2 monitoring in the 4th quarter of 2013. The only exception is for Schedule 4 systems (those serving less than 10,000 in population) that monitored for Cryptosporidium and have a letter from the Division of Water (DOW) moving their compliance date to October 2014.
After Oct. 1, 2013, Stage 1 monitoring for THMs and HAAs stops, and Stage 2 monitoring begins. Please make sure you
Review your IDSE report for the correct sample site locations and schedule.
- Make sure the sample site codes for the new Stage 2 sites are three digits and acceptable to the SDWIS database (contact Kellee Husband with DOW for assistance). Should you need to change your sample site location code, the form can be found at http://water.ky.gov/DrinkingWater/Pages/Forms.aspx.
- Notify your lab of the new sample sites and schedule.
- Remind your lab that there is a DOW data report form specific for the Stage 2 THM and HAA reporting, which can be found at http://water.ky.gov/DrinkingWater/Pages/Forms.aspx.
Compliance with the TTHM and HAA5 MCLs for Stage 2 DBPR is based on your monitoring results at each monitoring location. Compliance for Stage 2 will be calculated after four quarters of monitoring (or after the one annual monitoring event).
NOTE: Surface water treatment plants will continue to monitor for total organic carbon.
If you monitor once per quarter:
• Compliance is based on the LRAA of monitoring results, calculated quarterly (see example on the next page).
• If you take more than one sample per quarter at a monitoring location, you must average all samples taken in the quarter at that location—sampling multiple times at a single location during a quarter must be included in your Stage 2 DBP monitoring plan.
• If the LRAA at any location exceeds the MCL, you are in violation.
• Failure to monitor will be treated as a monitoring violation for the entire period, covered by a locational running annual average compliance calculation for the Stage 2 MCLs.
If you monitor once per year:
• Compliance is based on the value of the yearly samples at each location.
• You must make compliance calculations beginning with the first compliance sample taken after the compliance date.
• If any sample exceeds the MCL, you are not immediately in violation. You must begin to increase monitoring immediately (monitor quarterly at each location).
• If any sample exceeds the MCL and you are on reduced monitoring, you must begin increased monitoring immediately (monitor quarterly at each location).
• Failure to monitor will be treated as a monitoring violation for the entire period covered by a locational running annual average compliance calculation for the Stage 2 MCLs.
Operational Evaluation Requirements
After three quarters of sampling, Operational Evaluation Level (OEL) reporting forms are to be submitted to DOW if an exceedance occurs at any sample site location. Forms will then be completed every quarter should any exceedance occur. Only submit the OEL forms to do if an exceedance is determined.
If your system exceeds an OEL, an operational evaluation must be conducted to determine the cause of the exceedance. A written report summarizing the operational evaluation must be submitted to the state no later than 90 days after being notified of the analytical result that exceeded the OEL.
The OEL form can be found at http://water.ky.gov/DrinkingWater/Pages/Forms.aspx.
Contact Kellee Husband with the Division of Water at 502-564-3410 or at KelleeM.Husband@ky.gov for assistance with the rule. DOW staff can also provide technical assistance should your system struggle with meeting the new Stage 2 Rule. Contact Natalie Bruner at 502-564-3410 or at Natalie.Bruner@ky.gov, and she can provide you with your DOW technical assistance staff person.
U.S. Environmental Protection Agency. (2008). Operational evaluation guidance manual. Retrieved from http://www.epa.gov/ogwdw/disinfection/stage2/pdfs/draft_guide_stage2_operationalevaluation.pdf
U.S. Environmental Protection Agency. (2007). The Stage 2 disinfectant and disinfection byproduct rule (stage 2 dbpr) implementation guide. Retrieved from http://www.epa.gov/ogwdw/disinfection/stage2/pdfs/guide_stage2_stateimplementationguide.pdf