The contractor shall, in the presence and under the direction of the Engineer, test the airtightness of all main sewer lines. The test will be made between each adjacent structure and between the most upstream structure and dead end. The air test will be made only after all other utilities and the curb and gutter have been installed and before any street base rock has been oiled. The Engineer shall be present during installation of plugs prior to air testing.
(A) When tested.
(1) In areas to be left unpaved, the air test shall be made after the backfill is satisfactorily compacted.
(2) In areas to be paved, per improvement plans, when the outside top of the sewer is less than three feet below the top of backfill, the air test shall be made after the “base rock” portion of the paving is satisfactorily compacted and before any street base rock has been oiled.
(3) (a) In areas to be paved, per improvement plans, when the outside top of the sewer main is three feet or more below top of backfill, the air test shall be made after all other utilities and the curb and gutter have been installed and the “sub-base” material portion of the paving is satisfactorily compacted.
(b) The air test as noted in divisions (A)(1), (A)(2) or (A)(3) above is considered the “official test”. However, preliminary air testing is strongly recommended and may be conducted by the contractor at any time prior to the “official test”.
(4) As directed by the Engineer, the contractor shall conduct a preliminary air test if the Engineer has reason to believe that the contractor’s means and methods have impacted the condition of the system. The preliminary test will not be considered the “official test”.
(B) Equipment. The contractor shall furnish all necessary equipment for conducting the test, including, but not limited to, an air compressor, air hoses, blank plug, liquid-filled test gauge, test plug, stopwatch and personnel.
(C) Air test procedure.
(1) Air testing sewer mains, particularly larger diameter mains, can be very dangerous due to the very large forces developed. The contractor shall be fully responsible and take all precautions necessary to ensure the safety of their workers. All plugs shall be adequately braced and restrained to support the full load developed. No workers shall be allowed in the excavation or manhole while the line is under pressure. The contractor shall make provisions for reading the pressure at the ground surface, and for safely releasing the air pressure without entering the manhole or excavation.
(2) The following procedure shall be used for air testing:
(a) Prior to testing, clean pipe to be tested by propelling a snug fitting inflated rubber ball through the pipe with water and remove any debris;
(b) Plug all pipe outlets with suitable test plugs. Brace each plug securely;
(c) If the pipe to be tested is submerged in groundwater, insert a pipe probe by boring or jetting into the backfill material adjacent to the center of the pipe, and determine the pressure in the probe when air passes slowly through it. This is the backpressure due to groundwater submergence over the end of the probe. All gauge pressures in the test shall be increased by this amount;
(d) Add air slowly to the portion of the pipe being tested until the internal pressure is raised to 4.0 psi greater than the average back pressure of any groundwater that may submerge the pipe;
(e) Check exposed pipe and plugs for abnormal leakage by coating with a soap solution. If any leakage is observed, bleed off air and make necessary repairs;
(f) After an internal pressure of 4.0 psig is obtained, allow at least two minutes for air temperature to stabilize, adding only the amount of air required to maintain pressure;
(g) After the two-minute period, disconnect the air supply. When pressure decreases to 3.5 psig, start stopwatch. Determine the time in seconds that is required for the internal air pressure to reach 2.5 psig. The minimum allowable time in seconds shall be based on the diameters and lengths of pipe under test;
(h) The pipeline shall be considered acceptable when the total time interval for the pressure drop from 3.5 to 2.5 psi meets or exceeds the calculated test time based on the following table. This table is based on a rate of 0.0015 cubic feet per minute per square foot of internal pipe surface when tested per ASTM F-1417. At the inspector’s option, the test may be conducted for a pressure drop of 3.5 to 3.0 psi and one-half of the time shown; and
(I) If the pipe installation fails to meet these air test requirements, the contractor shall determine the source or sources of leakage, and he or she shall repair or replace all defective materials or workmanship in accordance with these specifications and in the presence of the Engineer. The completed pipe installation shall meet the requirements of this test.
Pipe Diameter, Inches | Test Time, Seconds/Feet by Feet | Minimum Test Time, Minutes: Seconds |
Pipe Diameter, Inches | Test Time, Seconds/Feet by Feet | Minimum Test Time, Minutes: Seconds |
4 | 0.38 | 3:46 |
6 | 0.85 | 5:40 |
8 | 1.52 | 7:34 |
10 | 2.37 | 9:26 |
12 | 3.42 | 11:20 |
15 | 5.34 | 14:10 |
18 | 7.69 | 17:00 |
21 | 10.47 | 19:50 |
24 | 13.67 | 22:40 |
27 | 17.31 | 25:30 |
30 | 21.37 | 28:20 |
33 | 25.85 | 31:10 |
36 | 30.77 | 34:00 |
(D) Mandrel or deflectometer test. Mandrel test for flexible pipes shall also meet the requirements specified in § 33.116(B)(2)(b)8.
(1) Flexible pipe less than 18 inches In diameter: Upon completion of the air test, the contractor shall pull a mandrel or deflectometer, approved by the Engineer, through the installed flexible pipe. This test shall be performed without mechanical pulling devices. Mandrel shall not be tampered with.
(2) Flexible pipe 18 inches or greater in diameter: At the end of each working day, or as directed by the Engineer, the contractor shall pull an approved mandrel or deflectometer through the portion of the pipe specified by the Engineer. This section of pipe will have pipe embedment fully in place and compacted per these specifications plus at least four feet of backfill in place with a minimum of 85% relative compaction per ASTM D-1557. This shall be a preliminary test only to ensure the integrity of the pipe at the time of installation. The mandrel test for acceptance shall be performed after the air test as described in division (C) above, but before final paving is installed.
(Ord. 2019-02, passed 4-25-2019)