Operational Evaluation Level
Stage 2 D/DBP Rule Compliance
Michael W. Deal
Compliance Assurance Section
Central Office
Division of Drinking And Ground Waters
Overview
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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=
C=
D=
TTHM or HAA5 result for the quarter before the previous quarter
TTHM or HAA5 result for the previous quarter
TTHM or HAA5 result for current quarter
Current Operational Evaluation Level Value
Example
Location “X” (DS201)
TTHM Results
Current Quarter Value (3rd Qtr 2013) ……………………...(114.0 µg/L)
Previous Quarter Value (2rd Qtr 2013)……………….....…….61.3 µg/L
Quarter Before Previous (1st Qtr 2013)….............………..45.1 µg/L
2
334.4 µg/L
4
OEL = 83.6 µg/L
OEL Exceedance
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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)
OEL Exceedances
(Since Aug. 2012)
45 Total
62%
Purchased SW
84%
3rd Quarter
6 Repeat
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
OEL Form 5031
Section 1 –
Source Water
and Treatment
Section 1 – Source Water and
Treatment
Noteworthy Changes to Source Water:
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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
Section 2 – Distribution System
Operations
Noteworthy Events or Changes
to the Distribution System:
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Hydrant flushing
Line breaks
Rerouted flow
Significant demands
Section 3 –
Storage Tank
Operations
Section 3 – Storage Tank Operations
Calculate Percent Daily Fluctuation
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The difference between the high and
low water levels for each drain/fill event
ℎ𝑖𝑔ℎ 𝑤𝑎𝑡𝑒𝑟 𝑙𝑒𝑣𝑒𝑙 −𝑙𝑜𝑤 𝑤𝑎𝑡𝑒𝑟 𝑙𝑒𝑣𝑒𝑙
ℎ𝑖𝑔ℎ 𝑤𝑎𝑡𝑒𝑟 𝑙𝑒𝑣𝑒𝑙
X 100%
Section 4 – Chlorine
Residual Monitoring
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
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
Questions