Neighbor In Need: What The Heck Is That Sound?

A reader posted the following to our Facebook page. Anyone have an idea?

I need some help from my neighbors here. I live on Ocean Ave and Ave S. For the past few weeks, I have often (but not every night) heard noises starting in the very early morning hours that sound like it could be cars driving over a loose metal plate or hammering. once when it woke me up i thought it was a basketball bouncing till i realized it was coming from outside and, I think, a distance…kind of boom boom stop a few seconds, repeat. I’m hoping that if someone else hears this, it can be identified and stopped. Does anyone hear it?
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