Section 290.115 - Stage 2 Disinfection Byproducts (TTHM and HAA5)(a) Applicability for total trihalomethanes (TTHM) and haloacetic acids (group of five) (HAA5). All community and nontransient, noncommunity water systems shall comply with the requirements of this section for TTHM and HAA5. (1) Systems must comply with the initial monitoring requirements starting on the dates given in subsection (c) of this section.(2) Systems must comply with all of the additional requirements in this section starting on the date shown in the table entitled "Date to Start Stage 2 Compliance." Attached Graphic
(A) Systems required to conduct quarterly monitoring, must begin monitoring in the first full calendar quarter that includes the compliance date in the table titled "Date to Start Stage 2 Compliance."(B) Systems required to conduct routine monitoring less frequently than quarterly must begin monitoring in the calendar month approved by the executive director in their Initial Distribution System Evaluation (IDSE) report or revised monitoring plan identifying Stage 2 sample sites.(3) Systems must complete their monitoring plan for the additional Stage 2 TTHM and HAA5 requirements according to § 290.121 of this title (relating to Monitoring Plans) before the date shown in the table entitled "Date to Start Stage 2 Compliance."(b) Maximum contaminant levels (MCL) and operational evaluation levels (OELs) for TTHM and HAA5. Systems shall comply with MCLs and OELs. (1) The locational running annual average (LRAA) concentration of TTHM and HAA5 shall not exceed the MCLs. A public water system that exceeds a MCL shall determine compliance as described in subsection (f) of this section. (A) The MCL for TTHM is 0.080 milligrams/liter (mg/L).(B) The MCL for HAA5 is 0.060 mg/L.(2) The OEL at any monitoring location is the sum of the two previous quarters' results plus twice the current quarter's result, divided by 4 to determine an average. A public water system that exceeds an OEL shall perform operation evaluation monitoring and reporting described in subsection (e) of this section. (A) The OEL for TTHM is 0.080 mg/L.(B) The OEL for HAA5 is 0.060 mg/L.(c) Monitoring requirements for TTHM and HAA5. Monitoring shall be performed at locations and frequency specified in the system's monitoring plan as approved by the executive director. The executive director may require changes to a system's sampling locations. The executive director may require sampling at additional sampling locations. (1) Monitoring locations. Systems must establish Stage 2 compliance monitoring sites throughout the distribution system at locations with the potential for relatively high disinfection byproduct formation. Systems must determine Stage 2 compliance monitoring locations by the dates shown in the table titled "Date to Establish Stage 2 Sites." Attached Graphic
(A) Systems that perform IDSE sampling in accordance with paragraph (5) of this subsection must use the IDSE and Stage 1 results to set Stage 2 compliance monitoring sites.(B) Systems that do not perform IDSE sampling must set Stage 2 compliance monitoring sites through consultation with the executive director in accordance with this subparagraph. (i) Systems required to sample at the same number of sites under Stage 1 and Stage 2, can use the Stage 1 sites for Stage 2 compliance monitoring.(ii) Systems required to sample at more sites under Stage 2 than Stage 1 must identify Stage 2 sites in addition to the existing Stage 1 sites. Systems must identify additional sites representing areas of the distribution system with potentially high TTHM or HAA5 levels and provide the rationale for identifying these locations as having high levels of TTHM or HAA5. The required number of compliance monitoring locations must be identified.(iii) Systems required to sample at fewer sites under Stage 2 than Stage 1 must identify which locations will be used for Stage 2. Stage 2 sites will be selected by alternating selection of Stage 1 locations representing the highest TTHM levels and highest HAA5 levels until the required number of compliance monitoring locations have been identified.(C) The protocol given in 40 Code of Federal Regulations (CFR) §141.605(c) - (e) for selecting Stage 2 sample sites is hereby adopted by reference.(D) To change monitoring locations, a system must replace existing compliance monitoring locations with the lowest LRAA with new locations that reflect the current distribution system locations with expected high TTHM or HAA5 levels. Changes must be approved by the executive director and included in the monitoring plan.(2) Monitoring frequency and number of sample sites. Routine sampling frequency and number of sample sites are given in the following table, titled "Routine Stage 2 Monitoring Frequency and Number of Sites." Systems must take all routine compliance TTHM and HAA5 samples during normal operating conditions. Attached Graphic
(3) Reduced monitoring for TTHM and HAA5. Monitoring may be reduced when the LRAA is less than or equal to 0.040 mg/L for TTHM and less than or equal to 0.030 mg/L for HAA5 at all Stage 2 compliance monitoring locations. The Stage 2 reduced sampling frequency and number of sample sites are given in the following table, titled "Reduced Stage 2 Monitoring Frequency and Number of Sites." Attached Graphic
(A) Only data collected under the provisions of § 290.113 of this title (relating to Stage 1 Disinfection Byproducts (TTHM and HAA5)) and under this section may be used to qualify for reduced monitoring.(B) In order to remain on reduced monitoring, a system must meet the applicable conditions of this subparagraph. (i) Systems with annual or less frequent reduced monitoring qualify to remain on reduced monitoring as long as each TTHM sample is less than or equal to 0.060 mg/L and each HAA5 sample is less than or equal to 0.045 mg/L.(ii) Systems on quarterly reduced monitoring qualify to remain on reduced monitoring as long as the TTHM LRAA is less than or equal to 0.040 mg/L and the HAA5 LRAA is less than or equal to 0.030 mg/L at each monitoring location.(iii) To qualify for and remain on reduced monitoring, the source water annual average Total Organic Carbon (TOC) level, before any treatment, must be less than or equal to 4.0 mg/L at each treatment plant treating surface water or groundwater under the direct influence of surface water, based on monitoring conducted under § 290.112(c)(2)(C) of this title (relating to Total Organic Carbon (TOC)).(C) Systems will be returned to routine monitoring:(i) if the LRAA at any monitoring location exceeds either 0.040 mg/L for TTHM or 0.030 mg/L for HAA5 based on quarterly monitoring, or(ii) if the annual (or triennial) sample at any location exceeds either 0.060 mg/L for TTHM or 0.045 mg/L for HAA5, or(iii) if the source water annual average TOC level, before any treatment, exceeds 4.0 mg/L at any treatment plant treating surface water or groundwater under the direct influence of surface water.(D) The executive director may return a system on reduced monitoring to routine monitoring at any time.(E) A system that is on reduced Stage 1 monitoring in accordance with § 290.113(c)(4) of this title that has monitoring locations for Stage 2 different from those under Stage 1 must initiate routine monitoring in accordance with paragraph (2) of this subsection on the schedule given in subsection (a) of this section.(F) A system that is on reduced monitoring in accordance with § 290.113(c)(4) of this title may remain on reduced monitoring after the dates identified in subsection (a)(2) of this section only if the system: (i) received a very small system (VSS) IDSE waiver under paragraph (5)(A) of this subsection or received a 40/30 IDSE waiver under paragraph (5)(B) of this subsection,(ii) meets the reduced monitoring criteria in subparagraph (B) of this paragraph, and(iii) is approved to use the same monitoring locations under Stage 1 and Stage 2.(G) The executive director may choose to perform calculations and determine whether the system is eligible for reduced monitoring in lieu of having the system report that information.(4) Increased monitoring for TTHM and HAA5. The executive director may increase monitoring in accordance with this paragraph.(A) A system required to routinely monitor at a particular location annually or less frequently than annually under paragraph (2) of this subsection must increase monitoring to quarterly dual sample sets (every 90 days) at all locations if any TTHM compliance sample is greater than 0.080 mg/L or if any HAA5 compliance sample is greater than 0.060 mg/L at any location.(B) The executive director may return a system on increased quarterly monitoring to routine monitoring after at least four consecutive quarters if the LRAA for every monitoring location is less than or equal to 0.060 mg/L for TTHM and less than or equal to 0.045 mg/L for HAA5.(C) A system that is on increased monitoring under § 290.113 of this title must remain on increased monitoring until the system qualifies for a return to routine monitoring under subparagraph (B) of this paragraph. The increased monitoring schedule must be conducted at the Stage 2 monitoring locations approved under paragraph (1) of this subsection, beginning on the date identified in subsection (a)(2) of this section.(5) IDSE requirements. All community systems of any size and nontransient, noncommunity systems that serve at least 10,000 people must comply with these IDSE requirements. (A) The executive director may grant a VSS IDSE monitoring waiver to systems that serve fewer than 500 people. Systems that receive a VSS IDSE monitoring waiver are not required to do IDSE monitoring. Systems must be compliant with all of the Stage 1 monitoring requirements of § 290.113 of this title to be eligible for a VSS IDSE waiver.(B) The executive director may grant a 40/30 IDSE monitoring waiver to IDSE monitoring to systems with levels for TTHM less than 0.040 mg/L and levels for HAA5 less than 0.030 mg/L. Systems that receive a 40/30 IDSE monitoring waiver are not required to do IDSE monitoring. Systems must be compliant with all of the Stage 1 monitoring requirements of § 290.113 of this title to be eligible for a 40/30 IDSE waiver. The timing of samples that all need to be less than 0.040 mg/L and 0.030 mg/L respectively for TTHM and HAA5 are given in the following table, titled "Timing of Stage 1 Samples Evaluated for 40/30 Initial Distribution System Evaluation (IDSE) Waiver." Attached Graphic
(i) To qualify for a 40/30 IDSE waiver a system must certify to the executive director that every individual sample taken under § 290.113 of this title were less than 0.040 mg/L for TTHM and less than 0.030 mg/L for HAA5, and must have not had any TTHM or HAA5 monitoring violations during the period specified in subsection (a) of this section.(ii) To qualify for a 40/30 IDSE waiver, a system must submit compliance monitoring results, distribution system schematics, and recommended Stage 2 compliance monitoring locations to the executive director upon request. The executive director may require a system that fails to submit the requested information to perform IDSE sampling.(iii) The executive director may still require a system that meets the 40/30 IDSE waiver or VSS IDSE waiver requirements to do IDSE sampling under subparagraph (C) of this paragraph.(C) Systems that must perform IDSE sampling must submit any needed documentation for waivers, produce an IDSE Plan, do IDSE sampling, and report the IDSE results to the executive director on the schedule in the following table titled "Initial Distribution Schedule Evaluation (IDSE) Schedule." Attached Graphic
(i) The IDSE plan has required elements. (I) The IDSE plan must include a schematic of the distribution system (including distribution system entry points and their sources, and storage facilities), with notes indicating locations and dates of all projected standard monitoring, and also Stage 1 compliance monitoring under § 290.113 of this title.(II) The IDSE plan must include justification of IDSE monitoring location selection and a summary of data used to justify IDSE monitoring location selection.(III) The IDSE plan must include the system type and population served by the system.(ii) Systems must do required IDSE sampling in accordance with this clause. (I) Systems must monitor at the number and type of sites indicated in the following table titled "Number and Type of Initial Distribution System Evaluation (IDSE) Sample Sites:" Attached Graphic
(II) Systems must collect dual sample sets at each monitoring location. One sample in the dual sample set must be analyzed for TTHM. The other sample in the dual sample set must be analyzed for HAA5.(III) IDSE sample locations must be different than the existing Stage 1 monitoring locations established under § 290.113 of this title.(IV) IDSE sample locations must be distributed throughout the distribution system.(V) Systems must monitor at the frequency indicated in the following table titled "Frequency of Initial Distribution System Evaluation (IDSE) Monitoring:" Attached Graphic
(VI) The IDSE monitoring frequency and locations may not be reduced.(iii) The IDSE report must comply with the elements in this clause. (I) The IDSE report must include all TTHM and HAA5 analytical results from Stage 1 compliance monitoring under § 290.113 of this title and all IDSE sample results and locational running annual averages presented in a tabular or spreadsheet format acceptable as described in Texas Commission on Environmental Quality regulatory guidance number 384: "How to Develop a Monitoring Plan for a Public Water System."(II) If changed from the IDSE plan submitted under clause (ii) of this subparagraph, the IDSE report must also include an updated distribution system map, documentation verifying the population served, and an updated list of sources including their water type.(III) The IDSE report must include an explanation of any deviations from the approved IDSE plan.(IV) The IDSE report must recommend and justify Stage 2 compliance monitoring locations consistent with paragraph (1) of this subsection. The recommended Stage 2 compliance monitoring locations must be listed in a Stage 2 sample plan as part of the system's monitoring plan.(V) The IDSE report must include recommendations and justification for when Stage 2 samples should be collected.(iv) The executive director may approve a system specific study that meets the requirements in 40 CFR § 141.602 to comply with IDSE sampling requirements. The commission hereby adopts the requirements of 40 CFR § 141.602 by reference.(D) The executive director may require a system to perform IDSE sampling or a system specific study for any reason. The executive director may require a system to perform IDSE sampling or a system specific study even if the system meets the criteria for an IDSE waiver. The executive director may require new systems and systems with a change in population or system type to perform IDSE sampling or a system specific study.(d) Analytical requirements for TTHM and HAA5. Analytical procedures required by this section shall be performed in accordance with § 290.119 of this title (relating to Analytical Procedures). Testing for TTHM and HAA5 shall be performed at a laboratory accredited by the executive director.(e) Reporting requirements for TTHM and HAA5. Public water systems must submit reports related to TTHM and HAA5 to the executive director. Reports must be mailed to the Water Supply Division, MC 155, Texas Commission on Environmental Quality, P.O. Box 13087, Austin, Texas 78711-3087.(1) The owner or operator of a public water system must ensure the executive director is provided with a copy of the results of any test, measurement, or analysis required by this subsection. The copies must be submitted within the first ten days following the month in which the result is received by the public water system, or the first ten days following the end of the required monitoring period as provided by this subsection, whichever occurs first. (A) The owner or operator of a public water system is responsible for reporting the following information for each monitoring location to the executive director within ten days of the end of any quarter in which monitoring is required:(i) number of samples taken during the last quarter;(ii) date and results of each sample taken during the last quarter;(iii) arithmetic average of quarterly results for the last four quarters for each monitoring location (LRAA), beginning at the end of the fourth calendar quarter that follows the compliance date and at the end of each subsequent quarter;(iv) whether the MCL was violated at any monitoring location; and(v) any OELs that were exceeded during the quarter and, if so, the location and date, and the calculated TTHM and HAA5 levels.(B) If the LRAA based on fewer than four quarters would cause the MCL to be exceeded regardless of the monitoring results of subsequent quarters, the system must report a potential MCL violation as part of the first report due following the compliance date or anytime thereafter that this determination is made. A system required to conduct monitoring at a frequency that is less than quarterly must make compliance calculations beginning with the first compliance sample taken after the compliance date, unless the system is required to conduct increased monitoring under subsection (c)(4) of this section.(C) A system that treats surface water or groundwater under the direct influence of surface water that seeks to qualify for or remain on reduced TTHM and HAA5 monitoring must measure and report TOC monthly in accordance with § 290.112 of this title and distribution system disinfection levels in accordance with § 290.110 of this title (relating to Disinfectant Residuals).(2) A system that exceeds an OEL described in subsection (b)(2) of this section must conduct an operation evaluation and submit a written operation evaluation report that meets the requirements of this paragraph. (A) The operation evaluation report must be submitted to the executive director no later than 90 days after being notified of the analytical result that causes the exceedance of the OEL.(B) The operation evaluation report must document an examination of system treatment and distribution operation practices that may contribute to TTHM and HAA5 formation, including: (i) storage tank operations;(ii) excess storage capacity;(iii) distribution system flushing;(iv) changes in sources or source water quality;(v) treatment changes or problems; and(vi) what steps could be considered to minimize future exceedances.(C) If the cause of the OEL exceedance is identifiable the scope of the report may be limited with the approval of the executive director. A request to limit the scope of the evaluation does not extend the schedule in subparagraph (A) of this paragraph for submitting the written report. The executive director's approval to limit the scope of the operation evaluation report must be in writing. The system must keep a copy of the executive director's approval with the completed operation evaluation report.(D) The operation evaluation report must be submitted and approved in writing.(f) Compliance determination for TTHM and HAA5. Compliance with the provisions of this section shall be determined as follows.(1) A public water system violates the MCL for TTHM if any locational running annual average for TTHM exceeds an MCL specified in subsection (b)(1)(A) of this section. A public water system violates the MCL for HAA5 if any locational running annual average for HAA5 exceeds the MCL specified in subsection (b)(1)(B) of this section. (A) Compliance with the MCLs for TTHM and HAA5 shall be based on the LRAA of all samples collected during four consecutive quarters of monitoring. If a single quarterly sample would cause an LRAA exceedance regardless of the results of subsequent quarters, compliance may be based on fewer than four quarters of data. Should a system fail to collect all required samples, compliance will be based on the available data. All samples collected at the sampling sites designated in the public water system's monitoring plan shall be used to compute the quarterly and annual averages unless the analytical results are invalidated by the executive director for technical reasons.(B) Stage 2 MCL compliance determination with LRAAs will start after Stage 2 samples are collected.(i) For systems required to conduct routine quarterly monitoring, compliance calculations will be made starting at the end of the fourth calendar quarter that follows the compliance date in subsection (a)(2) of this section and at the end of each subsequent quarter.(ii) For systems on quarterly monitoring, where the LRAA based on fewer than four quarters would exceed the MCL regardless of the monitoring results of subsequent quarters, compliance will be calculated beginning with the first sample that causes that exceedance.(iii) For systems that are required to monitor less frequently than quarterly, compliance shall be calculated beginning with the first compliance sample taken after the compliance date.(iv) For systems monitoring annually or triennially that start monitoring quarterly in the quarter following an LRAA exceedance, compliance shall be calculated based on the results of all available samples.(C) If a public water system's failure to monitor makes it impossible to determine compliance with the MCL for TTHM or HAA5, the system commits an MCL violation for the entire period covered by the annual average.(D) The executive director may choose to perform calculations and determine MCL exceedances in lieu of having the system report that information.(E) IDSE results will not be used for the purpose of determining compliance with MCLs.(2) A system that fails to monitor in accordance with this section commits a monitoring violation. A system on a quarterly monitoring schedule is in violation of the monitoring requirements for each quarter that it fails to monitor.(3) A system that fails to perform a required operation evaluation under subsection (e)(2) of this section commits a monitoring violation.(4) A public water system that fails to report the results of the monitoring tests required by subsection (e) of this section commits a reporting violation.(5) A system that fails to submit an operation evaluation report as required under subsection (e)(2) of this section commits a reporting violation.(6) A system that fails to perform a required public notification commits a public notification violation.(g) Public notification requirements for TTHM and HAA5. A public water system that violates the treatment technique requirements of this section must notify the executive director and the system's customers. (1) A public water system that commits an MCL violation described in subsection (f)(1) of this section shall report to the executive director and the water system customers in accordance with the requirements of § 290.122(b) of this title (relating to Public Notification).(2) A public water system which fails to conduct the monitoring required by subsection (c) of this section must notify its customers of the violation in accordance with the requirements of § 290.122(c) of this title.(3) Any IDSE compliance documents required under subsection (c)(5) of this section must be made available to the executive director or the public upon request.(4) Any operation evaluation report required under subsection (e)(2) of this section must be made available to the executive director or the public upon request.(h) Best available technology for TTHM and HAA5. Best available technology for treatment of violations of MCLs in subsection (b) of this section are listed in 40 CFR § 141.64(b)(2)(ii) and (iii).30 Tex. Admin. Code § 290.115
The provisions of this §290.115 adopted to be effective January 9, 2008, 33 TexReg 198; amended to be effective May 15, 2011, 36 TexReg 2860; Amended by Texas Register, Volume 42, Number 12, March 24, 2017, TexReg 1519, eff. 3/30/2017