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

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.

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: 0.080 milligrams per liter (mg/L) for TTHM, 0.060 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.

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.

OEL Triggers Quarterly DBP schedule Three consecutive quarters of DBP data Exceed the TTHM or HAA5 trigger levels: TTHM 0.080 mg/L (80 µg/L) HAA5 0.060 mg/L (60 µg/L) Calculated using the OEL formula

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

OEL Formula Example

OEL Schedule in DWW

OEL Schedule in DWW

Operational Evaluation Report

TCEQ-20797 (07/06/2017)

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

Submit the Operational Evaluation Report Make a copy of the Operational Evaluation Report for your records Submit to TCEQ by email or mail to: TCEQ, PO Box 13087, MC-155, Attn: OEL, Austin, TX 78711-3087 DBP@tceq.texas.gov

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: FMT@tceq.texas.gov https://www.tceq.texas.gov/drinkingwater/fmt (512) 239-4691

Resources Small Business and Local Government Assistance Free confidential hotline 1-800-447-2827 https://www.tceq.texas.gov/assistance

DBP or OEL Questions DBP@tceq.texas.gov Mia Gonzales (512) 239-6576 Mia.Gonzales@tceq.texas.gov Steven Swierenga (512) 239-6611 Steven.Swierenga@tceq.texas.gov