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Operational Evaluation Level Stage 2 D/DBP Rule Compliance . Michael W. Deal Compliance Assurance Section Central Office Division of Drinking And Ground Waters. Overview. Ohio Administrative Code Goals of OEL Calculation OEL Exceedance OEL Form 5031 Take Home.
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Operational Evaluation Level Stage 2 D/DBP Rule Compliance Michael W. Deal Compliance Assurance Section Central Office Division of Drinking And Ground Waters
Overview • Ohio Administrative Code • Goals of OEL • Calculation • OEL Exceedance • OEL Form 5031 • Take Home
Ohio Administrative Code • OAC 3745-81-24 (D) (21) • OEL calculated for DBPs at all monitoring locations • Exceedance of the MCL requires a report • OEL report due 90 days following notification • Publicly accessible upon request
Goals • Primary: to help prevent an MCL through advanced warning of increased DBP Locational Running Annual Averages (LRAA) for quarterly monitoring • Secondary: to cause PWSs to address locations or facilities with seasonal DBP issues
Calculation of OEL A = TTHM or HAA5 result for the quarter before the previous quarter B = TTHM or HAA5 result for the previous quarter C = TTHM or HAA5 result for current quarter D = Current Operational Evaluation Level Value
Example • Location “X” (DS201) • TTHM Results • Current Quarter Value (3rdQtr 2013) ……………………...(114.0 µg/L) 2 • Previous Quarter Value (2rdQtr 2013)……………….....…….61.3 µg/L • Quarter Before Previous (1stQtr 2013)….............………..45.1 µg/L • 334.4 µg/L • 4 • OEL = 83.6 µg/L • 83.6 > MCL of 80.0 µg/L for TTHM • Result is an OEL Exceedance
OEL Exceedance • Early warning • Not a violation • No public notice requirement • Can be at 1 or more monitoring location(s) • TTHM or HAA5
Following an Exceedance • Receive call from OEPA to determine scope • Receive letter from OEPA with report template • Complete OEL report (Form 5031)
OEL Exceedances (Since Aug. 2012) 18 13 9 2 3
Limited Scope • Limited scope OEL report if cause is known • High DBP levels result from a certain change in water quality, treatment or distribution
What’s the Point? • Begin dealing with DBP issues prior to NOV • Investigate areas of concern • Make adjustments to lower DBP levels • Document investigation on Form 5031
Section 1 – Source Water and Treatment Noteworthy Changes to Source Water: • Significant algal blooms • Uncharacteristic precipitation events • Alternative well usage • Distinctive change to purchased water Changes to Treatment: • Chemical feed increase or decrease • Chemical product changes
Section 2 – Distribution System Operations Noteworthy Events or Changes to the Distribution System: • Hydrant flushing • Line breaks • Rerouted flow • Significant demands
Section 3 – Storage Tank Operations Calculate Percent Daily Fluctuation • The difference between the high and low water levels for each drain/fill event • X 100%
Section 4 – Chlorine Residual Monitoring Disinfectant residual information; • Average residual can be found on your MOR • Number of distribution samples includes daily samples and samples collected with TC • Number of samples <0.2 mg/L for free or <1.0 mg/L for combined chlorine • Repeated for each month of the quarter
Section 5 – Additional Information • Additional monitoring information • Plans to comply with the MCL • Corrective actions taken from past OEL exceedances
Take Home • Early warning not a violation • OEPA will notify of an exceedance • Report covers treatment, storage and distribution • Failure to submit a report is a violation • Goal is to optimize control of DBPs and avoid MCL exceedances
More Information • www.epa.ohio.gov/ddagw • www.epa.gov/safewater/disinfection/stage2