(A) All sanitary sewer systems shall be subjected to infiltration, air, or exfiltration tests or a combination thereof in accordance with the following requirements prior to acceptance of the system by the Oakland County Department of Public Works and prior to removal of the bulkhead as required in § 52.17.
(B) All final acceptance tests shall be witnessed by the Oakland County Department of Public Works.
(C) Infiltration Test.
(1) All sewers over a 24-inch diameter shall be subjected to infiltration tests. All sewers of 24-inch diameter or smaller where the ground water level above the top of the sewer is over seven feet shall be subjected to an infiltration test.
(2) Maximum allowable infiltration shall not exceed 250 gallons per inch of diameter per mile of pipe per 24 hours for the overall project. Maximum allowable infiltration shall not exceed 500 gallons per inch of diameter per mile of pipe per 24 hours for any individual run between manholes.
(D) Air Test or Exfiltration Test.
(1) All sewers of 24-inch diameter or less, where the ground water level above the top of the sewer is seven feet or less, shall be subjected to air tests or exfiltration tests.
(2) For exfiltration tests, the internal water level shall be equal to the external water level plus seven feet as measured from the top of pipe.
(3) The allowable exfiltration rate shall be the same as that permitted from infiltration.
(4) The procedure for air testing of sewers shall be as follows:
(a) The sewer line shall be tested in increments between manholes. The line shall be cleaned and plugged at each manhole. Such plugs shall be designed to hold against the test pressure and shall provide an airtight seal. One of the plugs shall have an orifice through which air can be introduced into the sewer. An air supply line shall be connected to the orifice. The air supply line shall be fitted with suitable control valves and a pressure gauge for continually measuring the air pressure in the sewer. The pressure gauge shall have a minimum diameter of 3½ inches and a range of 0 - 10 PSIG. The gauge shall have minimum divisions of 0.10 PSIG and an accuracy of +0.04 PSIG.
(b) The sewer shall be pressurized to 4.0 PSIG greater than the greatest back pressure caused by ground water over the top of the sewer pipe. At least two minutes shall be allowed for the air pressure to stabilize between 3.5 and 4.0 PSIG. If necessary, air shall be added to the sewer to maintain a pressure of 3.5 PSIG or greater.
(c) After the stabilization period, the air supply control valve shall be closed so that no more air will enter the sewer. The sewer air pressure shall be noted and timing for the test begun. The test shall not begin if the air pressure is less than 3.5 PSIG, or such other pressure as is necessary to compensate for ground water level.
(d) The time required for the air pressure to decrease 1.0 PSIG during the test shall not be less than the time shown in the “Oakland County Department of Public Works Air Test Tables.”
(5) Manholes on sewers to be subjected to air tests shall be equipped with a 1/2 inch diameter galvanized capped pipe nipple extending through the manhole, three inches into the manhole wall and at an elevation equal to the top of the sewer pipe. Prior to the air test, the ground water elevation shall be determined by blowing air through the pipe nipple to clear it and then connecting a clear plastic tube to the pipe nipple. The tube shall be suspended vertically in the manhole and the ground water elevation determined by observing the water level in the tube. The air test pressure shall be adjusted to compensate for the maximum ground water level above the top of the sewer pipe to be tested. After all tests are performed and the sewer is ready for final acceptance, the pipe nipple shall be plugged in an acceptable manner.
(E) If a sewer fails to pass any of the previously described tests, the contractor shall determine the location of the leaks, repair them and retest the sewer. The tests shall be repeated until satisfactory results are obtained.
(F) All visible leaks and cracks shall be repaired regardless of test results.
(Ord. 23.27, passed 1-8-90) Penalty, see § 10.99