1. Disinfection Byproducts (DBPs) Operational Evaluation Level (OEL)
Mia Gonzales
Water Supply Division
Texas Commission on Environmental Quality
Environmental Trade Fair 2018

2. OEL Goal
Evaluate your system for any issues that could increase disinfection byproducts (DBP), identify changes to decrease levels, and work to solve the issue.

3. OEL Terms
OEL Compliance Program – component of the Stage 2 DBP Rule encompassing triggers, evaluations, and reporting.
Operational Evaluation Level – level at which an evaluation is triggered: milligrams per liter (mg/L) for TTHM, mg/L for HAA5.
Operational Evaluation Report – report documenting the evaluation of your system and any actions that may be taken to minimize future exceedances.

4. OEL Compliance Program
Uses DBP samples already collected by TCEQ contract samplers
NOT A VIOLATION, Public notice not required
A comprehensive review of system operations to identify the cause of the total trihalomethane (TTHM) or total haloacetic acids (HAA5) increase and identify actions to minimize future exceedances.

5. OEL Triggers Quarterly DBP schedule
Three consecutive quarters of DBP data
Exceed the TTHM or HAA5 trigger levels:
TTHM mg/L (80 µg/L)
HAA mg/L (60 µg/L)
Calculated using the OEL formula

6. OEL Formula
Use the three most recent quarters of data from each sample location:
Add two previous results together
Double the current result
Divide by four
1Q + 2Q + 3Q + 3Q = Sum / 4 = 3Q OEL
2Q + 3Q + 4Q + 4Q = Sum / 4 = 4Q OEL

7. OEL Formula Example

8. OEL Schedule in DWW

9. OEL Schedule in DWW

10. Operational Evaluation Report

11. TCEQ (07/06/2017)

16. Completed Operational Evaluation Report
What did I learn? Identify the issues that caused the exceedance(s)
Identify steps to prevent future exceedances
Summarize your findings and share with co-workers
Implement changes

17. Submit the Operational Evaluation Report
Make a copy of the Operational Evaluation Report for your records
Submit to TCEQ by or mail to:
TCEQ,
PO Box 13087,
MC-155, Attn: OEL,
Austin, TX

18. Financial, Managerial, and Technical Assistance
Resources
Financial, Managerial, and Technical Assistance
If you operate a water or wastewater system and would like to arrange for free financial, managerial, or technical assistance, contact our program:
(512)

19. Resources Small Business and Local Government Assistance
Free confidential hotline

20. DBP or OEL Questions DBP@tceq.texas.gov Mia Gonzales (512) 239-6576
Steven Swierenga
(512)