If I do connect them, I want more than a six inch pipe between. I think a wide ditch with a footbridge might work. I can walk or drive the mower all around the sediment pond now, so a bridge isn't essential.
I'll try to edit this and post a pic showing what they look like when completely full.
Any connection will depend on stopping the leakage from the pond my sediment pond runs over into. I expect my dirt guy to start in about a week, if he hasn't forgotten me. He's at a job about 2.5 miles from here now.
Here's a pic with a blue outline showing how the ponds look when completely full. The pond on the right is two feet lower at the surface than the other ponds when full.