Product Manual

Figure 4-4 Sound Attenuation of Different Frequencies by 4 feet of Soil
Finally, the ground cover, whether it is an asphalt street, loose dirt, concrete slab,
or grass lawn, also makes an important difference. Hard street surfaces and con-
crete slabs resonate with the sounds of the water leak, and the leak may be heard
for 5 to 10 feet or more on either side of the water pipe. Grass lawns and loose
dirt surfaces do not offer such a resonating plate-like surface.
Sound Transmission Through Pipe Walls
Metal pipes, particularly iron mains between 6 inches and 12 inches, copper ser-
vices, and steel pipes, transmit the sounds of water leaks for hundreds of feet in
every direction. Asbestos-cement pipe and PVC pipe do not transmit the sounds
nearly as far, and the sounds of leaks in these materials may be transmitted only
100 to 400 feet (see Figure 4-5).
Figure 4-5 Sound Transmission vs. Distance from Leak
4-4
200
-80
-60
-40
-20
1,000 5,000
Frequency (Hz)
Sound
Attenuation
(dB)
Transmitted Frequencies
100 - 20,000 Hz
100 - 10,000 Hz
Pipe Material
Cast Iron
PVC
Distance from Leak, Axially along Pipe
Sound
Intensity
(Amplitude)
PVC ACP CIP