1. (a) Applicability. A public water system that treats surface water or groundwater under the direct influence of surface water must comply with the requirements of this section. A public water system that uses groundwater under the direct influence of surface water must comply with the requirements of this section by a date specified by the executive director. This compliance date shall not exceed 18 months from the date that the executive director first notifies the system that the groundwater source is under the direct influence of surface water.

2. (b) Treatment technique requirements for turbidity. The filtration techniques used by public water systems treating surface water or groundwater under the direct influence of surface water must ensure the system meets the following treatment technique requirements and criteria.

   1. (1) Through December 31, 2001, the treatment process used by public water systems treating surface water or groundwater under the direct influence of surface water must achieve at least a 3-log removal or inactivation of Giardia lamblia cysts and a 4-log removal or inactivation of viruses before the water is supplied to any consumer. The executive director may require additional levels of treatment in cases of poor source water quality.

      1. (A) Treatment plants using conventional media filtration must achieve the following turbidity levels.

         1. (i) The turbidity level of the combined filter effluent must never exceed 5.0 NTU.
         2. (ii) The turbidity level of the combined filter effluent must be 0.5 NTU or less in at least 95% or the samples tested each month. The executive director may allow a turbidity level of up to 1.0 NTU in at least 95% of the samples if the system can achieve the required 3-log removal or inactivation of Giardia lamblia cysts and 4-log removal or inactivation of viruses at that higher turbidity level.
      2. (B) Membrane facilities must meet site-specific performance standards approved by the executive director.

   2. (2) Beginning January 1, 2002, the treatment process must achieve at least a 2-log removal of Cryptosporidium oocysts, a 3-log removal or inactivation of Giardia lamblia cysts, and a 4-log removal or inactivation of viruses before the water is supplied to any consumer. The executive director may require additional levels of treatment in cases of poor source water quality.

      1. (A) Treatment plants using conventional media filtration must achieve the following turbidity levels.

         1. (i) The turbidity level of the combined filter effluent must never exceed 1.0 NTU.
         2. (ii) The turbidity level of the combined filter effluent must be 0.3 NTU or less in at least 95% of the samples tested each month.
      2. (B) Membrane facilities must meet site-specific performance standards approved by the executive director.

      3. (C) The executive director may extend the compliance date for systems serving fewer than 10,000 people.

         1. (i) The compliance date may not be extended beyond January 1, 2004.
         2. (ii) During any extension that is granted, the turbidity level of the combined filter effluent must meet the requirements of subsection (b)(1) of this section.

   3. (3) The filtration techniques used by public water systems that serve 10,000 people or more and treat surface water or groundwater under the direct influence of surface water must ensure the system meets the following criteria.

      1. (A) Beginning January 1, 2002, the turbidity from each individual filter should not exceed 0.5 NTU at four hours after the individual filter is returned to service after backwash or shut down.
      2. (B) Beginning January 1, 2002, the turbidity from each individual filter should never exceed 1.0 NTU.

3. (c) Monitoring requirements for turbidity. Public water systems with surface water sources or groundwater sources that are under the direct influence of surface water shall monitor the performance of their filtration facilities.

   1. (1) Public water systems that serve fewer than 500 people must monitor the turbidity of the combined filter effluent at least once each day that the system serves water to the public.
   2. (2) Public water systems that serve 500 people or more must monitor the turbidity of the combined filter effluent at least every four hours that the system serves water to the public.
   3. (3) Beginning January 1, 2002, public water systems that serve 10,000 people or more must continuously monitor the filtered water turbidity at the effluent of each individual filter and record the turbidity value every 15 minutes.
   4. (4) Beginning January 1, 2002, public water systems that serve fewer than 10,000 people and use surface water or groundwater under the direct influence of surface water must measure and record the filtered water turbidity level at the effluent of each individual filter at least once each day that the plant is in operation.

   5. (5) Special monitoring requirements. Beginning January 1, 2002, public water systems which serve 10,000 people or more and fail to meet the turbidity criteria specified in subsection (b)(3) of this section must conduct additional monitoring. The executive director can waive these special monitoring requirements for systems that have a corrective action schedule approved by the executive director.

      1. (A) Each time a filter exceeds either of the filtered water turbidity levels specified in subsection (b)(3) of this section for two consecutive 15-minute readings, the public water system must either identify the cause of the exceedance or complete a Filter Profile Report on the filter within seven days of the exceedance.
      2. (B) Each time a filter exceeds the filtered turbidity level specified in subsection (b)(3)(B) of this section for two consecutive 15-minute readings on three separate occasions during any consecutive three month period, the public water system must conduct a filter assessment on the filter within 14 days of the exceedance.
      3. (C) Each time the filtered water turbidity level for a specific filter or any combination of individual filters exceeds 2.0 NTU on two consecutive 15-minute readings during two consecutive months, the public water system must participate in a third-party comprehensive performance evaluation within 90 days of the exceedance.

4. (d) Analytical requirements for turbidity. All monitoring required by this section must be conducted by a facility approved by the executive director and using methods that conform to the requirements of §290.119 of this title (relating to Analytical Procedures). Equipment used for compliance measurements must be maintained and calibrated in accordance with §290.46(s) of this title (relating to Minimum Acceptable Operating Practices for Public Drinking Water Systems).

   1. (1) Turbidity must be measured with turbidimeters that use nephelometric methods or Great Lakes Instruments Method 2.
   2. (2) Monitoring of combined filter effluent may be conducted by either continuously monitoring turbidity levels with an on-line turbidimeter or measuring the turbidity level in grab samples with a benchtop turbidimeter.

   3. (3) Beginning January 1, 2002, systems serving 10,000 or more people must monitor the turbidity of the water produced by individual filters with a continuous, on-line turbidimeter and a continuous recorder.

      1. (A) Continuous individual filter turbidity may be recorded electronically by a SCADA system or on a strip chart. Circular strip charts, if used, must be set to record no more than one day's readings per chart.
      2. (B) If there is a failure in the continuous turbidity monitoring equipment, the system must conduct grab sampling every four hours in lieu of continuous monitoring but for no more than five working days following the failure of the equipment.
   4. (4) Beginning January 1, 2002, systems serving fewer than 10,000 people must monitor the turbidity of the water produced by individual filters by continuously monitoring turbidity levels with an on-line turbidimeter or measuring the turbidity level in grab samples with a benchtop turbidimeter.

5. (e) Reporting requirements for turbidity. Public water systems shall properly complete and submit periodic reports to demonstrate compliance with this section.

   1. (1) A public water system that has a turbidity level exceeding 5.0 NTU in the combined filter effluent shall notify the public drinking water program by the next business day.
   2. (2) Public water systems which use surface water sources or groundwater sources under the direct influence of surface water, must submit a Monthly Operating Report for Surface Water Treatment Plants each month. Until January 1, 2001, systems must submit TNRCC Form 0102A. After January 1, 2001, systems must submit TNRCC Form 00102.
   3. (3) Public water systems that must complete the additional monitoring required by subsection (c)(5)(A) of this section must submit a Filter Profile Report for Individual Filters with their Monthly Operating Report for Surface Water Treatment Plants.
   4. (4) Public water systems that must complete the additional monitoring required by subsection (c)(5)(B) of this section must submit a Filter Assessment Report for Individual Filters with their Monthly Operating Report for Surface Water Treatment Plants.
   5. (5) Public water systems that must complete the additional monitoring required by subsection (c)(5)(C) of this section must submit a Request for Compliance CPE with their Monthly Operating Report for Surface Water Treatment Plants.
   6. (6) Periodic reports required by this section must be submitted to the Texas Natural Resource Conservation Commission, Water Permitting and Resource Management Division, MC 155, P.O. Box 13087, Austin, Texas 78711-3087 by the tenth day of the month following the end of the reporting period.

6. (f) Compliance determination. Compliance with the requirements of this section shall be determined using the following criteria.

   1. (1) A public water system that fails to conduct the combined filter effluent or individual filter monitoring tests required by this section commits a monitoring violation.
   2. (2) A public water system that fails to report the results of the combined filter effluent or individual filter monitoring tests required by this section commits a reporting violation.
   3. (3) Beginning on January 1, 2002, a public water system that serves 10,000 or more people and fails to submit the reports required by subsection (e)(3) - (5) of this section commits a reporting violation.
   4. (4) A public water system that has a turbidity level exceeding 5.0 NTU in the combined filter effluent commits an acute treatment technique violation.
   5. (5) Until December 31, 2001, a public water system that violates the requirements of subsection (b)(1)(A)(ii) of this section commits a treatment technique violation.
   6. (6) Beginning January 1, 2002, a public water system that violates the requirements of subsection (b)(2)(A) of this section commits a treatment technique violation.
   7. (7) Beginning January 1, 2002, a system that fails to correct the performance-limiting factors identified in a CPE conducted pursuant to the requirements of subsection (c)(5)(C) of this section commits a violation.

7. (g) Public notification for turbidity. The owner or operator of a public water system that violates the requirements of this section must notify the public drinking water program and the people served by the system.

   1. (1) A public water system that has a turbidity level exceeding 5.0 NTU in the combined filter effluent shall notify the public drinking water program by the next business day and the water system customers of the acute violation in accordance with the requirements of §290.46(s)(4) of this title (relating to Minimum Acceptable Operating Practices for Public Drinking Water Systems) and §290.122(a) of this title (relating to Public Notification).
   2. (2) A public water system that fails to meet the treatment technique requirements of subsection (b)(1) or (2) of this section shall notify the public drinking water program by the end of the next business day and the water system customers in accordance with the requirements of §290.122(b) of this title.
   3. (3) A public water system which fails to conduct the monitoring required by this section must notify its customers of the violation in accordance with the requirements of §290.122(c) of this title.

Source Note:The provisions of this §290.111 adopted to be effective September 13, 2000, 25 TexReg 8880.