Can anyone tell me what good they are other than a pump?

I would guess that they are a starting point, similar to gravity anomoly testing. I heard that ATEMs were flown by the province a few years ago, using a fairly widely-spaced pattern, just to get a reference for the industry. Since then, the various companies have reflown closer patterns.

This test obviously cannot be used alone, but they do point to area to perform other tests, such as VTEM and ground geos.