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Operational Evaluation Level Stage 2 D/DBP
Rule Compliance
Michael W. DealCompliance Assurance SectionCentral OfficeDivision 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 + B + (2∗C ¿¿ ¿𝟒 =𝐃
A = TTHM or HAA5 result for the quarter before the previous quarterB = TTHM or HAA5 result for the previous quarterC = TTHM or HAA5 result for current quarterD = Current Operational Evaluation Level Value
ExampleLocation “X” (DS201)
TTHM Results
Current Quarter Value (3rd Qtr 2013) ……………………...(114.0 µg/L) 2Previous Quarter Value (2rd Qtr 2013)……………….....…….61.3 µg/LQuarter Before Previous (1st Qtr 2013)….............………..45.1 µg/L
334.4 µg/L
4
OEL = 83.6 µg/L
83.6 > MCL of 80.0 µg/L for TTHMResult 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
1. Receive call from OEPA to determine scope
2. Receive letter from OEPA with report template
3. Complete OEL report (Form 5031)
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
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 1 – Source Water and Treatment
Section 2 – Distribution System OperationsNoteworthy 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