1. (a) Applicability. All community and nontransient, noncommunity water systems shall comply with the requirements of this section regarding radiological contaminants. Public water systems treating groundwater under the direct influence of surface water must comply with the radiological requirements for surface water systems.

2. (b) Maximum contaminant levels (MCLs). The concentration of radiological contaminants in the water entering the distribution system shall not exceed the following maximum contaminant levels.

   1. (1) MCLs for radium-226, radium-228 and gross alpha particle radioactivity for community systems are as follows:

      1. (A) the MCL for combined radium-226 and radium-228 is 5 pCi/l; and
      2. (B) the MCL for gross alpha particle activity (including radium-226 but excluding radon and uranium) is 15 pCi/l.

   2. (2) Maximum contaminant levels for beta particle and photon radioactivity from man-made radionuclides in drinking water in community water systems are as follows:

      1. (A) The average annual concentration of beta particle and photon radioactivity from man-made radionuclides in drinking water shall not produce an annual dose equivalent to the total body or any internal organ greater than four millirem (mrem)/year.
      2. (B) Except for the radionuclides listed in Table A, the concentration of man-made radionuclides causing four mrem total body or organ dose equivalents shall be calculated on the basis of a two-liter-per-day drinking water intake using the 168 hour data listed in "Maximum Permissible Body Burdens and Maximum Permissible Concentration of Radionuclides in Air or Water for Occupational Exposure," NBS Handbook 69 as amended August 1963, U.S. Department of Commerce. If two or more radionuclides are present, the sum of their annual dose equivalent to the total body or to any organ shall not exceed four mrem/year.
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3. (c) Monitoring requirements. Public water systems shall measure the concentration of radiochemicals at locations and frequencies specified in the system's monitoring plan. All samples must be collected during normal operating conditions.

   1. (1) The monitoring frequency requirements for gross alpha particle activity, radium-226 and radium-228 are as follows. Public water systems shall monitor at least once every four years following the procedure required by subsection (f)(1) of this section. At the discretion of the executive director, when an annual record taken in conformance with subsection (f)(1) of this section has established that the average annual concentration is less than one-half the maximum contaminant levels established by subsection (b) of this section, analysis of a single sample may be substituted for the quarterly sampling procedure required by subsection (f)(1) of this section.

      1. (A) More frequent monitoring shall be conducted when required by the executive director in the vicinity of mining or other operations which may contribute alpha particle radioactivity to either surface or groundwater sources of drinking water, or when changes in the distribution system or treatment processing occur which may increase the concentration of radioactivity in the finished water.
      2. (B) A public water system shall monitor in conformance with subsection (c)(1)(A) of this section within one year of the introduction of a new water source for a community water system.
      3. (C) A community water system using two or more sources having different concentrations of radioactivity shall monitor the source of water, in addition to water from a free-flowing tap, when required by the executive director.
      4. (D) Monitoring for compliance with subsection (b) of this section after the initial period need not include radium-228 provided that the average concentration of radium-228 has been assayed at least once using the quarterly sampling procedure required by this subsection.
      5. (E) Public water systems shall conduct annual monitoring of any community water system in which the radium 226 concentration exceeds three pCi/l when required by the executive director.

   2. (2) The monitoring frequency requirements for man-made radioactivity in community water systems are as follows:

      1. (A) Systems using surface water sources and serving more than 100,000 persons and such other community water systems as are designated by the executive director shall be monitored for compliance with the subsection (b) of this section by analysis of four quarterly samples. Compliance with subsection (b) of this section may be assumed without further analysis if the average annual concentration of gross beta particle activity is less than 50 pCi/l and if the average annual concentrations of tritium and strontium-90 are less than those listed in Table A of subsection (b)(2)(B) of this section, provided that if both radionuclides are present, the sum of their annual dose equivalents to bone marrow shall not exceed four mrem/year.

         1. (i) If the gross beta particle activity exceeds 50 pCi/l, an analysis of the sample must be performed to identify the major radioactive constituents present and the appropriate organ and total body doses shall be calculated to determine compliance with subsection (b) of this section.
         2. (ii) Public water systems shall conduct additional monitoring as required by the executive director to determine the concentration of man-made radioactivity in principal watersheds designated by the executive director.
         3. (iii) At the discretion of the executive director, public water systems utilizing only groundwater may be required to monitor for man-made radioactivity.
      2. (B) After the initial analysis required by subsection (c)(2)(A) of this section, public water systems shall monitor at least every four years following the procedure given in subsection (c)(2)(A) of this section.

      3. (C) A community water system designated by the executive director as utilizing waters contaminated by effluents from nuclear facilities shall initiate quarterly monitoring for gross beta particle and iodine-131 radioactivity and annual monitoring for strontium-90 and tritium.

         1. (i) Quarterly monitoring for gross beta particle activity shall be based on the analysis of monthly samples. If the gross beta particle activity in a sample exceeds 15 pCi/l, the same or an equivalent sample shall be analyzed for strontium-89 and cesium-134. If the gross beta particle activity exceeds 50 pCi/l, an analysis of the sample must be performed to identify the major radioactive constituents present and the appropriate organ and total body doses shall be calculated to determine compliance with subsection (b) of this section.
         2. (ii) For iodine-131, a composite of five consecutive daily samples shall be analyzed once each quarter. When iodine-131 is identified in the finished water more frequent monitoring shall be conducted as required by the executive director.
         3. (iii) Annual monitoring for strontium-90 and tritium shall be conducted by the analysis of four quarterly samples.
         4. (iv) The executive director may allow the substitution of environmental surveillance data taken in conjunction with a nuclear facility for direct monitoring of man-made radioactivity by the public water system where the executive director determines such data is applicable to a particular community water system.
4. (d) Analytical requirements for radiological contaminants. Analytical procedures shall be performed in accordance with §290.119 of this title (relating to Analytical Procedures). Testing for radiological contaminants shall be performed at a laboratory certified by the TDH Bureau of Laboratories.
5. (e) Reporting requirements. Any owner or operator of a public water system subject to the provisions of this section is required to report to the executive director the results of any test, measurement, or analysis required to be made by this section within ten days following receipt of the results of such test, measurement, or analysis.

6. (f) Compliance determination. Compliance with the requirements of this section shall be determined as follows.

   1. (1) If the average annual MCL for gross alpha particle activity or total radium as set forth in subsection (b) of this section is exceeded, the system has committed a MCL violation. Monitoring at quarterly intervals shall be continued until the annual average concentration no longer exceeds the maximum contaminant level or until a monitoring schedule as a condition to a variance, exemption or enforcement action shall become effective. Compliance with subsection (b) of this section shall be based on the analysis or analyses of four quarterly samples.

      1. (A) A gross alpha particle activity measurement may be substituted for the required radium-226 and radium-228 analysis provided that the measured gross alpha particle activity does not exceed five pCi/l at a confidence level of 95% (1.65 theta where theta is the standard deviation of the net counting rate of the sample).
      2. (B) When the gross alpha particle activity exceeds five pCi/l, the same or an equivalent sample shall be analyzed for radium-226. If the concentration of radium-226 exceeds three pCi/l the same or an equivalent sample shall be analyzed for radium-228.
   2. (2) If the average annual maximum contaminant level for man-made radioactivity set forth in subsection (b) of this section is exceeded, the system has committed a MCL violation. Monitoring at monthly intervals shall be continued until the concentration no longer exceeds the maximum contaminant level or until a monitoring schedule as a condition to a variance, exemption or enforcement action shall become effective.
   3. (3) A public water system that fails to conduct the monitoring tests required by this subsection commits a monitoring violation.
   4. (4) A public water system that fails to report the results of the monitoring tests required by this subsection commits a reporting violation.

7. (g) Public notification. A public water system that violates the requirements of this subsection must notify the public drinking water program and the system's customers.

   1. (1) A public water system that violates the MCL for gross alpha particle activity or total radium shall give notice to the public drinking water program and notify the public as required by §290.122(b) of this title (relating to Public Notification).
   2. (2) The operator of a community water system that violates the MCL for man-made radioactivity shall give notice to the public drinking water program and to the public as required by §290.122(b) of this title.
   3. (3) A public water system which fails to conduct the monitoring required by this subsection 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 §290.108 adopted to be effective September 13, 2000, 25 TexReg 8880.