Disinfection Byproducts Rules and Regulations Update Presented by: Turner Morrison II D/DBP Rule Manager Public Water Supply Section.

Transcription

1 Disinfection Byproducts Rules and Regulations Update Presented by: Turner Morrison II D/DBP Rule Manager Public Water Supply Section July 27, 2017 NC Presentation Topics Stage 2 Disinfectants and Disinfection Byproducts (D/DBP) Rule Review of Rule Requirements Monitoring Schedules Compliance Calculations Operational Evaluation Level (OEL) Calculations Operational Adjustment and Treatments for Systems with High DBP Levels Area Wide Optimization Program Alternative Disinfectants Results/Conclusions 1

2 Basics Applicable to all community and non-transient-noncommunity public water systems in the State which disinfect their drinking water with something other than UV (~2200 water systems) All of these systems are now subject to Stage 2 requirements Some systems had approved extensions for construction or Cryptosporidium monitoring under the LT2 Rule Basics MCL Compliance is based on a Locational Running Annual Average (LRAA) Number of monitoring locations is based on current population and source water type All applicable water systems were required to submit a Stage 2 DBP Compliance Monitoring plan (CMP) to the Public Water Supply Section, which included Stage 2 sample locations, rationale for location selection, and when the samples will be collected This is also a requirement for new water systems 2

3 DBP Sample Locations: All Stage 2 DBP sample locations should be listed using B0_ codes For systems with more than one required sample location, codes ending in odd numbers are High Total Trihalomethane (TTHM) sites B01, B03, B05, etc. Codes ending in an even number are High Total Haloacetic Acid (HAA5) sites DBP Sample Locations Continued: For systems with only one required sample location, B01 should be the only code used and indicates that the site is highest for both TTHM and HAA5 The Stage 2 DBP location codes are specific to the Stage 2 DBP Rule and these codes must be reused if sample sites are moved due to distribution system changes You can view your DBP sample location addresses online at Drinking Water Watch or in your paper file of your Stage 2 DBP Compliance Monitoring Plan 3

4 Sample Schedules: All Stage 2 DBP samples must be collected in a specific predesignated month representing a water system s month of peak DBP formation For purchasers, monitoring schedules should be synchronized with the Seller Routine, Reduced, and Increased monitoring schedules are included on each system s CMP Routine Monitoring Schedules: 4

5 Reduced Monitoring Schedules (Surface Water): Reduced Monitoring Schedules (Ground Water): 5

6 Reduced Monitoring Qualifications: TTHM LRAA < mg/l at ALL locations HAA5 LRAA < mg/l at ALL locations Annual Average TOCs at each treatment plant < 4.0 mg/l for Surface water and purchased surface water system A system may remain on reduced monitoring as long as: TTHM LRAA < mg/l at ALL locations and HAA5 LRAA < mg/l at ALL locations for systems monitoring quarterly OR Each TTHM sample < mg/l and each HAA5 sample < mg/l at ALL locations for systems monitoring annually or triennially AND Annual source water TOC average < 4.0 mg/l for surface water systems Increased Monitoring Requirements: If any TTHM sample at any location exceeds mg/l OR any HAA5 sample at any location exceeds mg/l, the system is required to begin increased monitoring immediately Dual sample sets taken on a quarterly basis at ALL DBP monitoring locations To return to routine monitoring: Conduct at least four consecutive quarters of increased monitoring TTHM LRAA for every monitoring location < mg/l HAA5 LRAA for every monitoring location < mg/l Contact DBP Rule manager to get approval for any reduction in monitoring frequency 6

7 Representative DBP Sampling Monitoring Requirements (a) General requirements (1) Systems must take all samples during normal operating conditions. Compliance sampling should take place near midpoint between flushing events Compliance Calculations: LRAA=(Q C +Q C-1 +Q C-2 +Q C-3 )/4 Calculated quarterly to determine compliance with Maximum Contaminant Levels: TTHM MCL=0.080 mg/l HAA5 MCL=0.060 mg/l Tier 2 MCL Violation if LRAA MCL exceedance occurs OEL=(2Q C +Q C-1 +Q C-2 )/4 Calculated quarterly to determine if the Operational Evaluation Level (OEL) has been exceeded TTHM OEL=0.080 mg/l HAA5 OEL=0.060 mg/l If OEL exceedance occurs, an Operational Evaluation Report must be completed and submitted to the NC PWS Section 7

8 Triggering an OEL Report The OEL Report must address the following ( ): The results of the OEL calculations An examination of system treatment and distribution operational practices including: Storage tank operations Excess storage capacity Distribution system flushing Changes in sources or source water quality, and Treatment changes or problems that may contribute to TTHM or HAA5 formation A discussion about what steps could be considered to minimize future exceedances ***There is also an abbreviated limited scope reporting option that may be applicable in some cases Stage 2 DBP Rule Status # of DBP Monitoring Violations Schedule 1 Systems under Stage 2 monitoring requirements All systems under Stage 2 monitoring requirements

9 Stage 2 DBP Rule Status There has been an increase in monitoring violations due to Stage 2 monitoring requirements Most common reasons for DBP monitoring violations: Not sampling Sampling in the wrong month Dual samples vs. individual samples 70 Stage 2 DBP Rule Status # of DBP MCL Vios Almost All Systems on Stage Q1 2006Q2 2006Q3 2006Q4 2007Q1 2007Q2 2007Q3 2007Q4 2008Q1 2008Q2 2008Q3 2008Q4 2009Q1 2009Q2 2009Q3 2009Q4 2010Q1 2010Q2 2010Q3 2010Q4 2011Q1 2011Q2 2011Q3 2011Q4 2012Q1 2012Q2 2012Q3 2012Q4 2013Q1 2013Q2 2013Q3 2013Q4 2014Q1 2014Q2 2014Q3 2014Q4 2015Q1 2015Q2 2015Q3 2015Q4 2016Q1 2016Q2 2016Q3 2016Q4 2017Q1 9

10 Stage 2 DBP Rule Status There has been no significant increase in MCL violations under the Stage 2 Rule 65% TTHM MCL Violations 35% HAA5 MCL Violations Many MCL violations under Stage 2 are by systems who struggled to maintain Stage 1 Rule compliance Under Stage 2, samples can not be averaged with results from different locations To stay in compliance, water systems with high DBP levels need to look at adjustments in system operation and possible installation of new treatment technologies DBP Operational Considerations Adjustments to current operations, may be able to reduce DBP levels in your water system (Source: 10

11 DBP Operational Considerations Area Wide Optimization Program (AWOP) Voluntary program to increase public health protection Not related to compliance Comprehensive Performance Evaluations (CPE) Distribution System Optimization DBP and TOC removal goals Operational spreadsheets DBP Treatment Technologies Technologies Likely to be used by Small Systems: Chloramination Ultraviolet Light (UV) Granular Activated Carbon (GAC) Adsorption At least 20 minutes of empty bed contact time and annual average reactivation/replacement frequency no greater than 240 days (GAC 20) At least 10 minutes of empty bed contact time and an annual average reactivation/replacement frequency no greater than 120 days (GAC 10) plus enhanced coagulation or softening (Source: 11

12 DBP Treatment Technologies Other Technologies Tank Aeration and Mixing Nanofiltration Microfiltration and Ultrafiltration Membrane Technology Magnetic Ionic Exchange Resin Alternative Disinfectants Chlorine dioxide Ozone (Source: Rules for Alternative Disinfectants Chlorine Dioxide: Daily Chlorine dioxide and chlorite monitoring at the entry point to the distribution system Monthly chlorite monitoring in the distribution system (3 locations) Chlorine dioxide MRDL = 0.8 mg/l Chlorite MCL = 1.0 mg/l (Note: Additional monitoring in the distribution system is required each day following an exceedance of the chlorine dioxide MRDL or the chlorite MCL at the entry point.) Ozone: Monthly bromate monitoring at the entry point to the distribution system Bromate MCL = mg/l 12

13 Expectations vs. Results Pre-Stage 2 Expectations (2014) Water systems with high results at particular locations that had not been proactive in treatment would likely violate the TTHM and/or HAA5 MCLs under the Stage 2 DBP Rule 60 systems at risk for quarterly MCL violations An initial increase in systems failing to meet Stage 2 Compliance, but a drop below 2014 levels of non-compliance as improvements in treatment are made Results So Far (2017) Maximum of 29 MCL violations in a single quarter Minimum of 12 MCL Violations in a single quarter 55 water systems have at least one MCL violation since Stage 2 began 21 water systems have had 4 or more MCL violations Conclusions Less MCL violations have occurred than predicted The systems with 4 or more DBP MCL violations were not proactive in resolving DBP issues ahead of Stage 2 Monitoring Violations: Monitoring in the wrong month is the most common monitoring issue of new Stage 2 requirements Monitoring reminders are sent to systems monitoring on annual or 3-year schedules If water systems are unsure of their monitoring schedule, consult the DBP Rule Manager or Stage 2 DBP Compliance Monitoring Plan Schedules are also posted online at Drinking Water Watch 13

14 Contact Information Turner Morrison DBP Rule Manager o o turner.morrison@ncdenr.gov Dave McCartney Team Leader for DBPs, Public Notice (PN), Consumer Confidence Report (CCR) o o dave.mccartney@ncdenr.gov 27 14