The Wait is Over Tier 3 and 4 Operational Evaluation Level Reporting

Transcription

1 The Wait is Over Tier 3 and 4 Operational Evaluation Level Reporting (a part of the Stage 2 D/DBP Rule) Reed M. Barton, PE November 17, 2014

2 ROAD MAP Introduction Stage 2 D/DBPR Monitoring and Reporting DBP Levels The OEL Calculation OE Reporting Reducing DBP Formation

3 Introduction Stage 2 D/DBPR EPA regulates the use of disinfectants in drinking water: Requiring use for killing microorganisms Limiting concentrations of disinfection by-products (DBPs) Stage 2 D/DBPR replaced the Stage 1 D/DBPR

4 Introduction Stage 2 D/DBPR Applies to all community water systems (CWS) and non-transient non-community water systems (NTNCWS) which use chemical disinfectants. MRDL, MCL, and DBP precursor removal requirements unchanged Stage 2 D/DBPR has more stringent sampling requirements LRAA replaces RAA Review of sampling locations All samples must be collected in a pre-designated month

5 RAA vs. LRAA 1st Quarter 2nd Quarter 3rd Quarter 4th Quarter Average All Samples Average All Samples Average All Samples Average All Samples RAA of Quarterly Averages Must be Below MCL ( ( (( ) ))) EACH LRAA MUST BE BELOW MCL

6 Introduction Stage 2 D/DBPR Stage 2 D/DBPR (continued ) Focus is 2 classes of DBPs (TTHMs and HAA5) Sets MCL Goals(MCLGs) for (4) THMs and (5) HAAs (non-enforceable) Disinfection Byproducts MCL(mg/L) TTHM HAA Bromate Chlorite 1.0 TTHMs HAA5s Chloroform Monochloroacetic Acid Bromodichloromethane Dichloroacetic Acid Dibromochloromethane Trichloroacetic Acid Bromoform Bromoacetic Acid DibromoaceticAcid

7 Monitoring and Reporting DBPs All water systems required to submit a Stage 2 Compliance Monitoring Plan (CMP) sampling locations, rationale, and when sampling will take place The number of monitoring locations depends on source water type and utility size (est. # of pplserved) New requirement for Operational Evaluation (OE) reporting if trigger levels are exceeded.

8 Monitoring and Reporting DBPs New requirements rolled out by utility size: All system under Stage 2 Rules - Oct Schedule 1 Systems serving >100,000 ppl Schedule 2 Systems serving 50,000-99,999 ppl Schedule 3 Systems serving 49,999 10,000 ppl Schedule 4 Systems serving <10,000 people

9 Monitoring and Reporting DBPs Schedule 1 and 2 systems: Defined as >49,999 ppland the systems that purchase from these utilities Approx. 120 water systems in NC Approx. 10 systems have submitted OELs (since 2012) Schedule 3 and 4 systems: Defined as <50,000 ppl, not including systems purchasing from Schedule 1 or 2 systems. Approx water systems in NC Approx. 25 systems have OELs required (since summer 2014)

10 Purpose of OEL The OEL process is intended to be an early warning system for a possibletthm or HAA5 MCL exceedancein the following quarter. The OEL process provides the water system with three months to take proactive steps to reduce DBP formation and possibly avoid a MCL violation.

11 Calculating OEL The OEL is calculated for both TTHM and HAA5 at each monitoring location that has been approved for the Stage 2 D/DBPR compliance monitoring program. OEL = [(2*Q C +Q C-1 +Q C-2 )]/4 whereas: Q C = current quarter TTHM/HAA5 result Q C-1 = previous quarter TTHM/HAA5 result Q C-2 = Two quarters before current quarter TTHM/HAA5 result

12 When is an OE Required OEL calculation applies to all systems which are conducting quarterly monitoringunder the Stage 2 D/DBPR, and have at least 3 quarters of continuous sampling results. For systems that are on Reduced monitoring (annual, etc.); if a single sample site exceeds the MCL TTHM or HAA5 the utility is moved to Increased Monitoring for at least 4-quarters, and will begin completing OEL calculations after 3 quarters of data are collected The OE Report is required (within 90-days of sample results) when the OEL calculation projects a possible future MCL exceedancein the following quarter.

13 Complete OEL Calculations for TTHM/HAA5

14 Contents of an OE Report EPA has prepared the STAGE 2 DISINFECTANTS AND DISINFECTION BYPRODUCTS RULE: OPERATIONAL EVALUATION GUIDANCE MANUAL Templates have been developed by other states, Templates can help a water system collect, organize, and evaluate data to identify contributing factors to the OEL exceedance. The OE Report must propose steps (operational adjustments) aimed at lowering DBP formation.

15 Contents of an OE Report NCDENR expects the following information in the OE Report (per Section ): 1. Results of OEL Calcs 2. An examination of system treatment and distribution operational practices including: a) Storage tank operations, b) Excess storage capacity, c) Distribution system flushing, d) Changes in sources or source water quality, and e) Treatment changes or problems that may contribute to TTHM or HAA5 formation. 3. A discussion about what steps could be considered to minimize future exceedance. Limited scope report may be applicable in some cases

16 What Happens is the LRAA Exceeds MCL for TTHMs or HAA5s? NCDENR issues a Notice of Violation (NOV) and an Administrative Order setting a target date to be back in compliance Public notification of MCL exceedance, per Stage 2 D/DBPR Water System continuesto complete OEL calculations, OE Reporting, and evaluate operational/treatment adjustments Quarterly Status Report can combine requirements of QSR and OE Report

17 High DBP Levels What s the Solution? Systems with high DBP levels will need to look at Operational Adjustments and/or Treatment Adjustments. Operation Considerations: Evaluating data and changes made within the problematic period (ph, Temperature, bromide, SUVA, TOC) DBP Profile determine the location of DBP formation Disinfectant dose or location adjustments Residual disinfectant dose or location adjustments Contact time and mixing conditions (water age, flushing) Raw water quality / TOC concentrations throughout treatment processes

18 High DBP Levels What s the Solution? Treatment Considerations: Alternate disinfectants / alternate residuals disinfectants Ozone, Chloramines, UV, Chlorine Dioxide, Permanganate Technologies for Reducing NOM GAC / PAC Membranes (NF, MF, UF) Ion Exchange Organic Carbon + Disinfectant + Time= DBPs

19 QUESTIONS Reed M. Barton, PE Project Manager Bill Dowbiggin, PE, BCEE Vice-President

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21 Monitoring and Reporting DBPs Three Categories of Monitoring Requirements: Increased Monitoring Routine Monitoring Reduced Monitoring Use tables in Rules Governing Water Systems (15A: 18C Monitoring Requirements)

22 Reduced Monitoring Requirements To qualify for reduced monitoring, a system must have: TTHM LRAA mg/l [50% of MCL (0.080 mg/l)] at ALL locations HAA5 LRAA mg/l [50% of MCL (0.060 mg/l)] at ALL locations Annual average TOCs at each treatment plant <4.0 mg/l for surface water systems (and those who are 100% SW purchase systems)

23 Reduced Monitoring Requirements A system can remain on reduced monitoringas 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 for TTHM AND each HAA5 sample mg/l for HAA5 at ALL locations for systems monitoring annually or less frequently AND For Subpart H systems and their purchasers the source water annual average TOC level, before any treatment 4.0 mg/l at each treatment plant treating SW or GWUDI

24 Increased Monitoring Required Any TTHM sample at any location exceeds mg/l, OR any HAA5 sample at any location exceeds mg/l Dual sample sets taken quarterly (every 90 days) If ANY site meets the criteria, the system must increase monitoring at ALL sites

25 Monitoring Requirements Dropping from Increased back to Routine A system can return to routine monitoring if after conducting at least four consecutive quarters of increased monitoring: TTHM LRAA for EVERY monitoring location is mg/l [75% of MCL (0.080 mg/l)] HAA5 LRAA for EVERY monitoring location is mg/l [75% of MCL (0.060 mg/l)]

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27 DBP Formation Organic Carbon + Disinfectant + Time= DBPs Higher Temperature increases the rate of reaction ph increases greatly elevate THMs and slightly decrease HAAs Increased Br- (saltwater intrusion) increases DBPs

28 Stage 2 D/DBPR

29 Who is Under Stage 2? All public water systems in the State of North Carolina that disinfect their drinking water, with a few exceptions,are now under the Stage 2 DBP rule as of October 1, Ten water systems that triggered Cryptosporidiummonitoring under the Long-Term 2 Enhanced Surface Water Treatment Rule (LT2 Rule), and any system that they sell water to, will not begin Stage 2 until October 1, 2014.

30 OE Report Contents (EPA Guidance) The OE Report serves as a primary communication tool between the water system and the state and federal regulatory agencies. It will also aid the water system in taking steps to resolve the causes of the MCL violation. The recommended OE steps are: Step 1: Confirm that Data Collection and Analysis Protocols Were Followed Step 2: Review DBP Data at Other Sites Step 3: If the Cause of the OEL Exceedance Is Known, Request State Approval to Limit Scope of Operational Evaluation Step 4: Conduct Operational Evaluation Step 5: Identify Steps to Minimize Future OEL Exceedances Step 6: Prepare and Submit Report