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RULE §290.42Water Treatment

    (B) The membrane system must be designed to conduct and record the results of direct integrity testing in a manner that demonstrates a removal efficiency equal to or greater than the removal credit awarded to the membrane filtration system approved by the executive director and meets the requirements in clauses (i) and (ii) of this subparagraph.

      (i) The design must provide for direct integrity testing of each membrane unit.

      (ii) The design must provide direct integrity testing that has a resolution of 3 micrometers or less.

      (iii) The design must provide direct integrity testing with sensitivity sufficient to verify the log removal credit approved by the executive director. Sensitivity is determined by the criteria in 40 CFR §141.719(b)(3)(iii).

      (iv) The executive director may reduce the direct integrity testing requirements for membrane units.

    (C) The membrane system must be designed to conduct and record continuous indirect integrity monitoring on each membrane unit. The turbidity of the water produced by each membrane unit must be measured using the Hach FilterTrak Method 10133. The executive director may approve the use of alternative technology to monitor the quality of the water produced by each membrane unit.

    (D) The level of removal credit approved by the executive director shall not exceed the lower of:

      (i) the removal efficiency demonstrated during challenge testing conducted under the conditions in subparagraph (A) of this paragraph; or

      (ii) the maximum removal efficiency that can be verified through direct integrity testing used with the membrane filtration process under the conditions in subparagraph (B) of this paragraph.

    (E) Pilot studies must be conducted using membrane modules that will meet the requirements of this section.

    (F) Membrane systems must be designed so that membrane units' feed water, filtrate, backwash supply, waste, and chemical cleaning piping shall have cross-connection protection to prevent chemicals from all chemical cleaning processes from contaminating other membrane units in other modes of operation. This may be accomplished by the installation of a double block and bleed valving arrangement, a removable spool system, or other alternative methods approved by the executive director.

  (4) Bag, cartridge, or membrane filtration systems or modules installed or replaced before April 1, 2012, and used for microbiological treatment, can receive up to a 2.0-log removal credit for Cryptosporidium and up to a 3.0-log removal credit for Giardia based on site-specific pilot study results, design, operation, and reporting requirements.

  (5) Ultraviolet (UV) light reactors used for microbiological inactivation can receive Cryptosporidium, Giardia, and virus inactivation credit if the reactors meet the criteria in subparagraphs (A) - (C) of this paragraph.

    (A) UV light reactors can receive inactivation credit only if they are located after filtration.

    (B) In lieu of a pilot study, the UV light reactors must undergo validation testing to determine the operating conditions under which a UV reactor delivers the required UV dose. Validation testing must be conducted according to the criteria established by 40 CFR §141.720(d)(2) and the executive director.

      (i) The validation study must include the following factors: UV absorbance of the water; lamp fouling and aging; measurement uncertainty of on-line sensors; UV dose distributions arising from the velocity profiles through the reactor; failure of UV lamps and other critical system components; inlet and outlet piping or channel configuration of the UV reactor; lamp and sensor locations; and other parameters determined by the executive director.

      (ii) Validation testing must be conducted on a full-scale reactor that is essentially identical to the UV reactor(s) to be used by the system and using waters that are essentially identical in quality to the water to be treated by the UV reactor.

    (C) The UV light reactor systems must be designed to monitor and record parameters to verify the UV reactors operation within the validated conditions approved by the executive director. The UV light reactor must be equipped with facilities to monitor and record UV intensity as measured by a UV sensor, flow rate, lamp status, and other parameters designated by the executive director.

  (6) Membrane filtration used by groundwater systems to achieve at least 4-log removal of viruses to comply with the groundwater rule requirements under §290.109 of this title (relating to Microbial Contaminants) and §290.116 of this title, the public water system shall meet the following criteria.

    (A) The membrane module must have an absolute molecular weight cut-off, or an alternate parameter that describes the exclusion characteristics of the membrane, that can reliably achieve at least 4-log removal of viruses.

    (B) The membrane system must be designed to conduct and record the results of integrity testing in a manner that demonstrates a removal efficiency equal to or greater than the removal credit awarded to the membrane system approved by the executive director.

(h) Sanitary facilities for water works installations. Toilet and hand washing facilities provided in accordance with established standards of good public health engineering practices shall be available at all installations requiring frequent visits by operating personnel.

(i) Permits for waste discharges. Any discharge of wastewater and other plant wastes shall be in accordance with all applicable state and federal statutes and regulations. Permits for discharging wastes from water treatment processes shall be obtained from the commission, if necessary.

(j) Treatment chemicals and media. All chemicals and any additional or replacement process media used in treatment of water supplied by public water systems must conform to ANSI/NSF Standard 60 for Drinking Water Treatment Chemicals and ANSI/NSF Standard 61 for Drinking Water System Components. Conformance with these standards must be obtained by certification of the product by an organization accredited by ANSI.

(k) Safety.

  (1) Safety equipment for all chemicals used in water treatment shall meet applicable standards established by the OSHA or Texas Hazard Communication Act, Texas Health and Safety Code, Chapter 502.

  (2) Systems must comply with United States Environmental Protection Agency (EPA) requirements for Risk Management Plans.

(l) Plant operations manual. A thorough plant operations manual must be compiled and kept up-to-date for operator review and reference. This manual should be of sufficient detail to provide the operator with routine maintenance and repair procedures, with protocols to be utilized in the event of a natural or man-made catastrophe, as well as provide telephone numbers of water system personnel, system officials, and local/state/federal agencies to be contacted in the event of an emergency. If operating a reverse osmosis or nanofiltration membrane system, the manual must also include the system's configuration, baseline performance data, and any set point for membrane cleaning or replacement.

(m) Security. Each water treatment plant and all appurtenances thereof shall be enclosed by an intruder-resistant fence. The gates shall be locked during periods of darkness and when the plant is unattended. A locked building in the fence line may satisfy this requirement or serve as a gate.

(n) Corrosion control treatment. Systems must install any corrosion control or source water treatment required by §290.117(f) and (g) of this title (relating to Regulation of Lead and Copper), respectively. Such treatment must be designed and installed consistent with the requirements of this subchapter. The requirements of 40 CFR §141.82(i) and §141.83(b)(7) relating to EPA involvement in treatment determination are adopted by reference.

Source Note: The provisions of this §290.42 adopted to be effective September 13, 2000, 25 TexReg 8880; amended to be effective May 16, 2002, 27 TexReg 4127; amended to be effective February 19, 2004, 29 TexReg 1373; amended to be effective January 9, 2008, 33 TexReg 198; amended to be effective May 15, 2011, 36 TexReg 2860; amended to be effective September 12, 2013, 38 TexReg 5880; amended to be effective July 30, 2015, 40 TexReg 4769; amended to be effective March 30, 2017, 42 TexReg 1466

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