The system exceeded the OEL at any monitoring site where the sum of the two previous quarters’ total trihalomethane (TTHM) results plus twice the current quarter’s TTHM result, divided by four, exceeds 80 ppb, or where the sum of the two previous quarters’ HAA5 results plus twice the current quarters’ HAA5 result, divided by four, exceeds 60 ppb (CFR 141.626 (a)).

No, OEL exceedances are not violations; however, the system must complete an OEL and submit a written report to the State, no later than 90 days after being notified of the result that triggered the OEL exceedance (CFR 141.626 (b)(1)).

No, but a copy of the evaluation report must be maintained on file and made available to the public upon request (CFR 141.626 (b)(1)).

You must submit a written report of the evaluation to the State no later than 90 days after being notified of the analytical results that caused the OEL exceedance (CFR 141.626 (b)(1)).

The OEL must include a thorough examination of system treatment and distribution operational practices, including storage tank operations, excess storage capacity, distribution system flushing, changes in source or source water quality, and treatment changes or problems that may contribute to TTHM and HAA5 formation and what steps could be considered to minimize future exceedances. (CFR 141.626 (b)(2)).

If the cause of the OEL exceedance can be identified the system may request to limit the scope of their evaluation. The request can be made by contacting your compliance assistance coordinator. You will receive the approval in writing indicating the new required evaluation elements. The written approval must be maintained on file with the completed report (CFR 141.626 (b)(2)(i, ii)).

The State recommends that systems make requests at least 45 days prior to the deadline for submitting the written report of the evaluation. Every request will be reviewed individually. 

The questionnaires and forms are not a required part of the evaluation report. They are provided to assist water system personnel with the evaluation.

Yes, the consecutive system will be required to conduct an operational evaluation. The system may request to limit the scope of the evaluation. Every request to limit the scope will be reviewed individually. Consecutive systems may include information provided by their wholesalers in the evaluation report. 

No, a request to limit the scope will not be required. The system may simply state in the report that treatment is not applicable. Consecutive systems may include treatment information provided by their wholesalers in the evaluation report. 

Yes, consecutive systems may include information provided by their wholesalers in the evaluation report.

The system may request to limit the scope of evaluation to a particular source, treatment plant, or section of the distribution system if the system can provide evidence that the service area where the exceedance occurred was not affected by the other sources, plants, or sections of distribution system directly or indirectly. Every request to limit the scope will be reviewed individually.

Systems affected by this scenario will be divided into three categories.

• Category 1: The system has documentation of the DBP levels at the site where the exceedance occurred prior to their Stage 2 D/DBPR compliance start date and can identify the cause of the OEL exceedance. The system may request to limit the scope of evaluation. Every request to limit the scope will be reviewed individually.
• Category 2: The system had an OEL exceedance which occurred at the same location as a previous monitoring period for which a cause has been identified but the solution has not yet been implemented or is in progress. The system may request to limit the scope of evaluation. Every request to limit the scope will be reviewed individually. 
• Category 3: The system does not meet the criteria in the other two categories. The system will need to conduct a full evaluation the first year the OEL exceedance occurs to identify all possible contributing factors. After the first evaluation the State will review requests to limit the scope of the evaluation for OEL exceedances that occur at the same location as a previous monitoring period for which a cause has been identified but the solution has not yet been implemented or is in progress. Every request to limit the scope will be reviewed individually.

Yes, if a monitoring site is not representative of the service area the system may request to change the site. As long as the locations represented still show the key areas of risk for DBPs, the system can request a change by contacting your compliance assistance coordinator by email. The new monitoring plan must be maintained on file.

All monitoring location requests must be accompanied with relevant data.