(A) Required leakage test. Prior to acceptance, all gravity sewers, including service laterals, shall be tested and pass a test for leakage. The contractor shall furnish all labor, materials and equipment required for making the tests and the groundwater level determinations with no extra compensation over and above the specified contract prices for the sewers. Testing shall not be performed until backfilling and compaction are completed. All gravity sewers shall pass a leakage test as further specified below.
(B) Low-pressure air test.
(1) A “Low-Pressure Air Test” conforming to the requirements of the latest revisions of ASTM C828 and ASTM C924 shall be performed on all new sanitary sewer pipe. Low-pressure air testing is used to determine the existence of pipe leaks; however, it does not indicate water-leakage limits.
(2) Prior to the low-pressure air testing, all wyes, tees or end-of-side sewer stubs shall be plugged with flexible-joint caps or an acceptable alternative and securely fastened to withstand the internal test pressures. Such plugs or caps shall be readily removable, and their removal shall provide a socket suitable for making a flexible-jointed lateral connection or extension.
(3) All plugs shall be securely braced to prevent a possible blowout due to internal air pressure. One plug shall have an inlet tap or other provision for connecting a hose to a portable air- supply source. Air hoses shall be connected to an inlet tap and a portable air-supply source.
(4) Air equipment shall consist of all necessary valves and pressure gages to control the rate of air flow into the test section and to enable the monitoring of air pressure within the test section. A testing apparatus shall also be equipped with a pressure-relief device to prevent the possibility of loading the test section with the full capacity of the compressor.
(5) Air shall be slowly added to a test section until the pressure inside the pipe is raised to 4.0 psig, plus an additional allowance for groundwater level above the pipe, converted into pounds per square inch (psi). However, in no case shall the maximum test pressure exceed 9.0 psi. After a pressure of 4.0 psig plus groundwater allowance is obtained, the air supply shall be regulated such that pressure is maintained between 3.5 and 4.0 psig for a period of two minutes to allow the air temperature to stabilize in equilibrium with the temperature of the pipe walls. The pressure will normally drop slightly until equilibrium is obtained. During this period, all plugs shall be checked with soap solution to detect any plug leak.
(6) (a) After the two-minute air stabilization period, the air supply shall be disconnected and the test pressure allowed to decrease. The time required for the test pressure to drop from 3.5 psig to 2.5 psig is determined by means of a stop watch, and this time interval is then compared with the required time to determine if the rate of air loss is within the allowable limit.
(b) The required time to arrive at the allowable air loss is calculated by means of the following formula:
T = 0.0850 DK
Q
Q
Where: T = time in seconds
K = .000419 DL, but not less than 1.0
Q = rate of loss (= 0.0015 cfm/sq. ft.
of internal surface)
L = length of pipe tested in feet
(7) Upon completion of the test, the bleeder valve shall be opened and all air allowed to escape. Plugs shall not be removed until all air pressure in the test section has been released.
(8) If the measured time interval for the pressure to drop from 3.5 psig to 2.5 psig is less than the required time as calculated, then the sewer section shall be deemed to have failed the test. The contractor shall then proceed to repair the pipe at his or her cost as necessary until the sewer section passes the test.
(9) All testing shall be conducted in the presence of the town’s representative.
(Ord. 2010-3, passed 10-6-2010)