I got nothing on this right now. I'm sure you figured what I figured on trying noise removal, but the problem of course is that the volume of the speaker is on par or quieter in a lot of sections than the background noise. Other tricks didn't seem to go too far either. I'm not very skilled with this stuff though, so I'm sure somebody way smarter can help you.
S3C
Use a noise filter. Isolate and select a sample of the background/garbage noise from the foreground speaking as best you can (when the foreground speaker isn't talking). Then get the noise profile from this sample. Then re-select the entire audio clip and apply the noise profile to sample to remove the noise as desired. Additional notch eqing may also eliminate some of the noise if some of the garbage sound frequencies are distinct from the foreground speakers range.