Humm.. Page cannot be found. Need a few details, and I can help. I've spent 40 years doing underwater and waterfront engineering projects, including foundation shoring under water. If you can't build a form, stack bags of pre-mixed concrete in place, assuming you have a foundation on which they will stay. The bag lasts long enough to set the concrete. However, the devil is in the details. I'd need to see the details to really be able to help.
Not a difficult thing to do .Use fabric formwork bags and just pump from above down an appropriate line.As above the ramifications are in the details. You may need to grout any voids behind the bags.
