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Section 38 – Sewer and Storm Drain Construction

38-10.02.C.(5)(f) Determination Of Line Failure

If the pressure drops one pound per square inch, gauge (1 psig) before the appropriate time

shown in Table 38-3 has elapsed, the air loss rate is considered excessive and the section of

pipe has failed the test.

38-10.02.C.(5)(g) Line Repair Or Replacement

If the section fails to meet these requirements, the Contractor shall, at his own expense,

determine the source, or sources, of leakage, and repair or replace all defective materials

and/or workmanship to the satisfaction of the Agency. The extent and type of repair that may

be allowed, as well as results, shall be subject to the approval of the Agency. The completed

pipe installation shall then be retested and required to meet the requirements of this test.

38-10.02.C.(6) Determination Of Groundwater Elevation and Air Pressure

38-10.02.C.(6)(a) Applicability

The requirements of this Section shall only apply where groundwater is known to exist or is

anticipated above the storm drain to be tested.

38-10.02.C.(6)(b) Pipe Nipple Installation

During manhole installation, a one-half inch (1/2”) diameter threaded pipe nipple shall be

installed through the manhole wall directly on top of one (1) of the storm drain pipes entering the

manhole. The threaded end of the nipple shall extend no more than two inches (2”) on the

inside of the manhole. The total length of the nipple shall exceed the manhole wall thickness by

no less than four inches (4”). The pipe nipple shall be non-corrosive and resistant to chemicals

common in domestic sewage. Special attention shall be given to providing a permanent,

watertight seal around the pipe nipple at the manhole wall. The pipe nipple shall be sealed with

a threaded one-half inch (1/2”) cap. Not every manhole need have a pipe nipple. A few key

manhole locations should be sufficient to establish a groundwater profile for the test area. The

Agency will assist the Contractor in selecting appropriate manholes for pipe nipple installation.

38-10.02.C.(6)(c) Groundwater Elevation

Immediately before air testing, the groundwater level shall be determined by removing the

threaded cap(s) from the nipple(s) nearest the section to be tested, blowing air through the pipe

nipple(s) to remove any obstructions, and then connecting clear plastic tube(s) to the pipe

nipple(s). Each plastic tube shall be held vertically to allow groundwater to rise in it. After the

water level in the tube has stopped rising, a measurement of the height in feet of water over the

invert of the storm drain pipe shall be taken. (See Figure 38A below.) If the section to be tested

is not immediately adjacent to an installed pipe nipple, the groundwater height shall be

estimated based upon nearby height readings and the pipe's invert elevation.