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Section 38 – Sewer and Storm Drain Construction

38-10.02.C.(6)(d) Air Pressure Adjustment

The air pressure correction, which must be added to the three and one-half pounds per

square inch, gauge (3.5 psig) normal test starting pressure, shall be calculated as follows:

(Average vertical height, in feet, of groundwater above the invert of the storm

drain pipe to be tested)

The result gives the air pressure correction in pounds per square inch to be added. (For

example, if the average vertical height of groundwater above the pipe invert is 2.8 feet, the

additional air pressure required is 2.8 divided by 2.31, or 1.2 psig. This requires a minimum

starting pressure of 3.5 plus 1.2, or 4.7 psig.). The allowable pressure drop of one pound per

square inch, gauge (1.0 psig) and the times in Table 38-3 are not affected and shall remain the

38-10.02.C.(6)(e) Maximum Test Pressure

In no case should the starting test pressure exceed nine pounds per square inch, gauge (9

psig). If the average vertical height of groundwater above the pipe invert is more than twelve

and seven tenths feet (12.7’), the section so submerged may be tested using nine pounds per

square inch, gauge (9 psig) as the starting test pressure. The nine pounds per square inch,

gauge (9 psig) limit is intended to further ensure worker safety and falls within the range of the

pressure monitoring gauges normally used.

38-10.02.C.(6)(f) Re-sealing Of Pipe Nipples

After the groundwater height has been determined, each pipe nipple shall be recapped and

sealed to prevent any future infiltration.

38-10.02.C.(7) Test Times

38-10.02.C.(7)(a) Test Time Criteria

The test time criteria requires that no test section shall be accepted if it loses more than

0.0015 cubic feet per minute per square foot of internal pipe surface area for any portion

containing less than six hundred twenty-five (625) square feet internal pipe surface area. The

total leakage from any test section shall not exceed 0.9375 cubic feet per minute.

38-10.02.C.(7)(b) Test Time Calculation

All test times shall be calculated using the following equation:

T = Shortest time, in seconds, allowed for the air pressure to drop 1.0 psig,

K = 0.000419 DL, but not less than 1.0,

Q = 0.0015 cubic feet/minute/ square feet of internal surface,

D = Nominal pipe diameter in inches, and

L = Length of pipe being tested in feet.

For more efficient testing of long test sections and/or sections of larger diameter pipes, a

timed pressure drop of one-half pound per square inch, gauge (0.5 psig) may be used in lieu of

the one pound per square inch, gauge (1.0 psig) timed pressure drop. If a one-half pound per

square inch, gauge (0.5 psig) pressure drop is used, the appropriate required test times shall be

exactly half as long as those obtained using the equation for T cited above.