(a) Applicability. All community water systems shall comply with the requirements of this section regarding radionuclide contaminants. Public water systems treating groundwater under the direct influence of surface water must comply with the radionuclide requirements for surface water systems. Public water systems shall comply with the initial monitoring requirements.
(b) Maximum contaminant levels (MCL). The concentration of radionuclide contaminants in the water entering the distribution system shall not exceed the following MCLs.
  (1) MCLs for naturally occurring radionuclides are as follows:
    (A) 5 picoCuries per liter (pCi/L) for combined radium-226 and radium-228, as calculated by the summation of the results for radium-226 and radium-228;
    (B) 15 pCi/L for gross alpha particle activity (including radium-226 but excluding radon and uranium); and
    (C) 30 micrograms per liter for uranium.
  (2) MCLs for beta particle and photon radioactivity from man-made radionuclides in drinking water in community water systems are equivalent to the MCLs under 40 Code of Federal Regulations (CFR) §141.66(d), as amended and adopted in the CFR through December 7, 2000 (65 FR 76708), which is adopted by reference.
(c) Monitoring requirements. Public water systems shall measure the concentration of radionuclides at locations and frequencies specified in the system's monitoring plan. All samples must be collected during normal operating conditions.
  (1) Monitoring frequency for naturally occurring radionuclides. The monitoring frequency requirements for gross alpha particle activity, combined radium-226 and radium-228, and uranium are as follows.
    (A) Initial monitoring frequency. All systems that use a new source of water must begin to conduct initial monitoring of the new source within 90 days after initiating use of the source.
      (i) If the initial monitoring results are at or above an MCL, the system must perform quarterly monitoring as described in subparagraph (C) of this paragraph.
      (ii) If the initial monitoring results are below all of MCLs given in subsection (b)(1) of this section, the system shall perform routine monitoring as described in subparagraph (B) of this paragraph.
    (B) Routine monitoring. The results of samples collected during initial and routine monitoring periods will be used to determine the monitoring frequency for subsequent monitoring periods.
      (i) If the results for all contaminants (gross alpha particle activity, combined radium-226 and radium-228, and uranium) are below the detection limits specified in Table A of this clause, the system must collect and analyze at least one sample at that sampling point once every nine years.
Attached Graphic
      (ii) If the result for any contaminant is at or above the detection limit but at or below one-half the MCLs given in subsection (b) of this section, the system must collect and analyze at least one sample at that sampling point every six years.
      (iii) If the result for any contaminant is above one-half the MCLs given in subsection (b) of this section but below the MCL, the system must collect and analyze at least one sample at that sampling point every three years.
      (iv) If the result for any contaminant is at or above any of the MCLs given in subsection (b) of this section, monitoring must be performed at the frequency given in subparagraph (C) of this paragraph.
    (C) Increased monitoring. A system must perform increased monitoring if any results at a sampling point are at or above the MCLs, or at the direction of the executive director.
      (i) If the results for any contaminant are at or above any of the MCLs given in subsection (b) of this section, consecutive quarterly monitoring must be performed at that sample point.
      (ii) If the average of quarterly monitoring results is less than the MCLs in subsection (b) of this section, the sample point may be returned to the routine sampling frequency given in subparagraph (B) of this paragraph.
      (iii) To fulfill quarterly monitoring requirements a system may composite up to four consecutive quarterly samples from a single entry point if analysis is done within a year of the first sample.
      (iv) The analytical results from a composite sample will be treated as the annual average to determine compliance with the MCLs and future monitoring frequency requirements.
      (v) When required by the executive director, more frequent monitoring must be conducted in the vicinity of mining or other operations that 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 that may increase the concentration of radionuclide in the finished water.
      (vi) Community public water systems shall conduct monitoring when required by the executive director.
    (D) Historical data. A system may use historical data to comply with the initial monitoring requirement, if approved by the executive director.
      (i) A system having only one entry point to the distribution system may use the monitoring data from the previous entry point or distribution system compliance monitoring to satisfy initial monitoring requirements.
      (ii) A system with multiple entry points that has appropriate historical monitoring data for each entry point to the distribution system may use previous compliance monitoring data to satisfy initial monitoring requirements.
      (iii) To satisfy initial monitoring requirements, a community water system with appropriate historical data for a representative point in the distribution system may use the monitoring data from the distribution system, provided that the executive director finds that the historical data satisfactorily demonstrates that each entry point to the distribution system is expected to be in compliance based upon the historical data and reasonable assumptions about the variability of contaminant levels between entry points.
    (E) Sample invalidation. The executive director may invalidate the results of obvious sampling or analytic errors.
    (F) Confirmation samples. The executive director may require more frequent monitoring or may require confirmation samples at the executive director's discretion.
    (G) Sampling scheduling. Systems shall monitor at the time designated by the executive director.
  (2) Monitoring and compliance for man-made radionuclides. The monitoring and compliance requirements for man-made radionuclide under 40 CFR §141.26(b), as amended and adopted in the CFR through December 7, 2000 (65 FR 76708), are adopted by reference.
  (3) Monitoring locations for radionuclide contaminants. Systems must monitor at sample sites described in the system's monitoring plan.
    (A) Initial monitoring for a new water source must be conducted at a site representative of the water quality of the new source of water.
    (B) Routine compliance monitoring for the radionuclide covered by this section must be performed at sampling points representing each entry point to the distribution system. If results from an entry point exceed one-half the MCL, the executive director may require the system to sample all water sources providing water to that entry point.
(d) Analytical requirements for radionuclide contaminants. Analytical procedures shall be performed in accordance with §290.119 of this title (relating to Analytical Procedures). Testing for radionuclide contaminants shall be performed at a laboratory certified by the executive director.
(e) Reporting requirements. 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 section. 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. The copies must be mailed to the Water Supply Division, MC 155, Texas Commission on Environmental Quality, P.O. Box 13087, Austin, Texas 78711-3087.
(f) Compliance determination. Compliance with the requirements of this section shall be determined as follows.
  (1) If the running average annual MCL for gross alpha particle activity, combined radium-226 and radium-228, or uranium as set forth in subsection (b) of this section is exceeded, based on quarterly monitoring results, the system has committed an MCL violation.
    (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 5 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).
Cont'd...