Preparation For Peir Removal From River

I walked down to the river this morning and spotted the bridge demolition crew preparing to recover a pair of cast iron piers from the old Windsor Bridge.
The piers are joined together by a steel frame with a large sandstone headstock on top and are filled with bricks and concrete.
Another frame is fitted to the piers with floatation bladders attached, after the piers have been separated from the sections going into the river bed they are pulled over with the intention of floating them across the river.
In this picture the piers are out of sight and resting on the river bed close to the bank while a diver frees the floatation frame so the piers can be dragged out of the river.