(a) For a collection system pipe that will transport wastewater by gravity flow, the design must specify an infiltration and exfiltration test or a low-pressure air test. The test must conform to the following requirements:
  (1) Low Pressure Air Test.
    (A) A low pressure air test must follow the procedures described in American Society for Testing and Materials (ASTM) C 828, ASTM C 924, or ASTM F 1417 or other procedure approved in writing by the executive director. The testing times listed in Table C.4. in Figure: 30 TAC §217.57(a)(1)(C) or Equation C.3 in Figure: 30 TAC §217.57(a)(1)(B)(ii) must be used, regardless of the testing procedure.
    (B) For sections of collection system pipe with an average inside diameter less than 36 inches, the following procedure applies, unless a pipe is to be tested as required by paragraph (2) of this subsection.
      (i) A pipe must be pressurized to 3.5 pounds per square inch (psi) gauge. If groundwater is present, then a pipe must be pressurized to 3.5 psi gauge greater than the pressure exerted by groundwater above the pipe.
      (ii) Once the pressure is stabilized, the minimum time allowable for the pressure to drop from 3.5 psi gauge to 2.5 psi gauge is computed from the following equation:
Attached Graphic
    (C) Since a K value of less than 1.0 may not be used, the minimum testing time for each pipe diameter is shown in the following table:
Attached Graphic
    (D) An owner may stop a test if no pressure loss has occurred during the first 25% of the calculated testing time.
    (E) If any pressure loss or leakage has occurred during the first 25% of a testing period, then the test must continue for the entire test duration as outlined above or until failure of the test.
    (F) Collection system pipes with a 27 inch or larger average inside diameter may be air tested at each joint instead of following the procedure outlined in this section.
    (G) A testing procedure for a pipe with an inside diameter greater than 33 inches must be approved in writing by the executive director.
  (2) Infiltration/Exfiltration Test.
    (A) The total exfiltration, as determined by a hydrostatic head test, must not exceed 10 gallons per inch of diameter per mile of pipe per 24 hours at a minimum test head of 2.0 feet above the crown of a pipe at an upstream manhole, or at least two feet above the existing groundwater level, whichever is greater.
    (B) An owner shall use an infiltration test in lieu of an exfiltration test when pipes are installed below the groundwater level.
    (C) If the quantity of infiltration or exfiltration exceeds the maximum quantity specified, an owner shall take remedial action in order to reduce the infiltration or exfiltration to an amount within the limits specified by Equation C.3. in Figure: 30 TAC §217.57(a)(1)(B)(ii) before putting the system into service. An owner shall retest a pipe following a remedial action according to the requirements of this chapter.
(b) If a gravity collection system pipe is composed of flexible pipe, deflection testing is also required.
  (1) For a collection system pipe with an inside diameter less than 27 inches, deflection measurement requires a rigid mandrel.
    (A) Mandrel Sizing.
      (i) A rigid mandrel must have an outside diameter not less than 95% of the base inside diameter or average inside diameter of a pipe, as specified in the appropriate standard by the ASTM, American Water Works Association, UNI-BELL, or American National Standards Institute.
      (ii) If the mandrel diameter is not specified in the standard used in clause (i) of this subparagraph, the mandrel must have an outside diameter equal to 95% of the inside diameter of a pipe. In this case, the inside diameter of the pipe, for the purpose of determining the outside diameter of the mandrel, must equal the average outside diameter minus two minimum wall thicknesses for outside diameter controlled pipe and the average inside diameter for inside diameter controlled pipe.
      (iii) All mandrel dimensions must meet the standard used in clause (i) of this subparagraph.
    (B) Mandrel Design.
      (i) A mandrel must be constructed of a metal or a rigid plastic material that can withstand 200 psi without being deformed. Adjustable or flexible mandrels are prohibited.
      (ii) A mandrel must have an odd number of runners or legs.
      (iii) A mandrel must have nine or more runners or legs.
      (iv) The length of the mandrel's barrel section must equal at least 75% of the inside diameter of the collection system pipe.
      (v) Each mandrel size must use a separate proving ring.
    (C) Method Options.
      (i) An owner may not use television inspection as a substitute for a deflection test.
      (ii) If requested, the executive director may approve, in writing, the use of a deflectometer or a mandrel with removable legs or runners on a case-by-case basis.
    (D) Trenchless Testing. The executive director may exempt pipe sections installed by trenchless technologies from mandrel testing in writing on a case-by-case basis.
  (2) For a gravity collection system pipe with an inside diameter of 27 inches and greater, other test methods approved in writing by the executive director may be used to determine vertical deflection.
  (3) A deflection test method must be accurate to within plus or minus 0.2% deflection.
  (4) An owner shall not conduct a deflection test until at least 30 days after the final backfill.
  (5) Collection system pipe deflection must not exceed 5%.
  (6) If a pipe section fails a deflection test, an owner shall correct the problem immediately, and then must conduct a second test after the final backfill has been in place at least 30 days.
  (7) An owner shall not use any mechanical pulling devices during deflection testing.
  (8) An owner shall include a certification in the notice of completion required in §217.14 of this title (relating to Completion Notice), that the collection system passed the deflection tests.
(c) An owner of a collection system must inspect the structural integrity of the collection system under the direction of an engineer during the construction and testing phases of the project.

Source Note: The provisions of this §217.57 adopted to be effective August 28, 2008, 33 TexReg 6843; amended to be effective December 4, 2015, 40 TexReg 8254