Okay. Done.
It was done a few days ago. It's part of the latest update.
Just go into the settings, and turn on landfill placement, and if desired, changed the 'pump clearance' value. The default leaves a very small pool around pumps. Setting it to 0 will just landfill everything, leaving a functional pump, but if you remove the pump, you won't be able to place it there again.
