sorry..lol.....we dont have stuff like that out here in AZ...
I know my mother in law has this problem in the basement...they did research and found out under ground there was a running stream down deep in the ground under the house. She put a sump pump in????? Apparently as the snow melts (in MT) the stream runs higher. That is probably not your problem.
Do you think you could have someone come out and see if they can concrete the crawl space though?? Sorry I don't have any other advice. I don't even know the bleach mixture as we cut EVERYTHING out and threw everything even remotely touching away. Literally we were seeing the outside bricks of the house.
Please be sure that you are wearing a mask while doing this work as that stuff is nasty...especially in children ...and can cause, amongst other things, asthma.