Pouring footers for beam supports with minor standing water

[Schmoleskin]

Greetings, I am usually in the electrical area, but not today... I am replacing some of the bearing wall in our basement with a steel beam that has two poured footers for support. I got a design from a structural engineer, but he is out of town this week as we prepare to pour the beam support footers. My house is down low in a valley with a creek nearby. We have a couple of sumps in the basement that always have some standing water in them. As my contractor was excavating, we started to see groundwater. I have a permanent sump pump in one sump that I have been lifting the float on periodically to keep that pumped out. I added a temporary pump in the other sump and am running that periodically to keep the groundwater as low as possible. One of the holes (the larger one that will have more weight on it) is pretty dry, I'd call it damp. The other one has maybe 1/4" to 3/8" of standing water in it no matter how much I pump. I saw lots of articles about pouring footers that said that concrete will displace standing water if you provide a path for it to drain away, but we're in a basement, there's nowhere for it to go, and it's being replaced from below to some extent. I also understand that concrete needs water to hydrate and set, but too much is bad, and you don't want floating water atop the pour to dilute it and create other issues I read about. There will be another 4" pour above this once the beam support is installed to bring it back up to floor level. My contractor had a couple of thoughts, how about lining the hole with plastic to keep the concrete separate from the wetter material? We could line the hole completely and keep the new concrete off the wetter material altogether. Though there would likely be some voids if we lined it completely. What about just a square of plastic the size of the footer? He also thought about having some drier concrete on the bottom layer to help soak it up. Does anyone have any ideas about how best to proceed? Let me know if you want a photo. Thanks, D