large site construction question

Factual Questions
1

The building I’m in is in one corner of a city block. Over the last several weeks, they’ve demolished every other building on the block and they’re going to build some hellish mall or something. I can see the construction right outside my window. It’s been pretty exciting to watch huge machines eat the buildings like dinosaurs, and watch them relocate a couple of the buildings. My boys have come over at lunch a few times to watch; it’s pretty cool.

Oh yeah, the question: They’ve been doing a funny thing the last couple days and I wonder if anyone knows why.

They dug a huge rectangular pit maybe 50’x30’ and 20’ deep. They layed down plastic across the whole area. (I went on the site and looked; the plastic is meshed, so it will allow water through.) Then they put down about a foot of rock, and covered that with another layer of the meshed plastic. Now they seem to be filling the hole back in with dirt.

Maybe they won’t fill it all the way in; they’ve quit for the day. But it sure looks like they’re just going to fill it back in.

Anyone know what’s going on here?

2

Please take this with a grain of salt, my construction experience is limited to residential.

It sounds as though it is a drainage pit of some sort. Without seeing actual plans, and based on your description alone, that’s the best answer I can come up with.

If it is drainage, it could be for any number of reasons, most likely site drainage during construction.

Might be fun to wander over about lunch time with your kids and inquire. Most construction workers are a pretty proud lot and will probably go out of their way to answer your questions. Assuming that they are on their lunch hour too and sitting close enough to the edge of the site to get their attention. Of course, you never want to enter any construction site without invitation.