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Section 38 – Sewer and Storm Drain Construction

38-10.02.C.(5) Test Procedure

38-10.02.C.(5)(a) Plug Installation and Testing

After a manhole-to-manhole reach of pipe has been backfilled to final grade, prepared for

testing and the specified waiting period has elapsed, the plugs shall be placed in the line at

each manhole and secured.

It is advisable to seal test all plugs before use. Seal testing may be accomplished by laying

one length of pipe on the ground and sealing it at both ends with the plugs to be checked. The

sealed pipe should be pressurized to nine pounds per square inch, gauge, (9 psig). The plugs

shall hold against this pressure without bracing and without any movement of the plugs out of

the pipe. No persons shall be allowed in the alignment of the pipe during plug testing.

It is advisable to plug the upstream end of the line first to prevent any upstream water from

collecting in the test line. This is particularly important in high groundwater situations.

When plugs are being placed, the pipe adjacent to the manhole shall be visually inspected

to detect any evidence of shear in the pipe due to differential settlement between the pipe and

the manhole. A probable point of leakage is at the junction of the manhole and the pipe, and

this fault may be covered by the pipe plug, and thus not revealed by the air test.

38-10.02.C.(5)(b) Line Pressurization

Low pressure air shall be slowly introduced into the sealed line until the internal air pressure

reaches four pounds per square inch, gauge, (4 psig) greater than the average back pressure of

any groundwater above the pipe, but not greater than nine pounds per square inch, gauge, (9

psig). If groundwater is present, refer to Section 38-10.02.C.(6), "Determination of Ground

Water Elevation and Air Pressure Adjustment", in this Section of these Specifications.

38-10.02.C.(5)(c) Pressure Stabilization

After a constant pressure of four pounds per square inch, gauge, (4.0 psig) greater than the

average groundwater back pressure is reached, the air supply shall be throttled to maintain that

internal pressure for at least two (2) minutes. This time permits the temperature of the entering

air to equalize with the temperature of the pipe wall.

38-10.02.C.(5)(d) Timing Pressure Loss

When temperatures have been equalized and the pressure stabilized at four pounds per

square inch, gauge, (4.0 psig) greater than the average groundwater back pressure, the air

hose from the control panel to the air supply shall be shut off or disconnected. The continuous

monitoring pressure gauge shall then be observed while the pressure is decreased to no less

than three and one-half pounds per square inch, gauge (3.5 psig) greater than the average back

pressure of any groundwater over the pipe. At a reading of three and one-half pounds per

square inch, gauge (3.5 psig), or any convenient observed pressure reading between three and

one-half pounds per square inch, gauge (3.5 psig) and four pounds per square inch, gauge, (4.0

psig) greater than the average groundwater back pressure, timing shall commence with a

stopwatch or other timing device that is at least ninety-nine and eight-tenths percent (99.8%)

38-10.02.C.(5)(e) Determination Of Line Acceptance

If the time shown in Table 38-3 for the designated pipe size and length elapses before the

air pressure drops one pound per square inch, gauge (1 psig); the section undergoing test shall

have passed and shall be presumed to be free of defects. The test may be discontinued once

the prescribed time has elapsed even though the one pound per square inch, gauge (1 psig)

drop has not occurred.