We're told the bridge was sold to an American in 1968, and it was dismantled, transported, and reconstructed in Lake Havasu, Arizona. Everyone's free to believe fairy tales, but IMHO normally functioning adults should give it up. So does this one hold up?
No, it does not.
No "9/11 Pentagon"-level photographic analysis is needed, just use your favorite search engine and look up something like "london bridge arizona construction". But before you do, what do you expect to see? Probably pictures of a bridge at different levels of completion over a body of water, right?
Wrong. What you see is a complete bridge over a desert, with dirt piled up to the top of the arches. Well WTF, huh? What are we seeing?
This was a completely existing bridge that had been buried under the desert. Probably because of erosion, at some point it became impossible to hide it's existence. So they dreamed up a tale to tell you about how it got there.
If you look around you can actually see that the waters of Havasu were originally nowhere near where the bridge is located. So between the "shore" and the "island" they had to excavate all the dirt to create a waterway, and then construct a brand new roadway to the bridgehead.
The population of Lake Havasu City, even by 1990, was only 24,000, and was not centered near the "island". No one was living on a hill out in the desert and no "bridge" was needed.
I believe they invented the whole "Spring Break" phenomenon to blow smoke around this whole incident. Culturally, that may be the strangest thought of all.
Look at a map. There wasn't a "river" and there still is not. There was just a high spot of land across from another high area. They had to excavate very far down to connect Lake Havasu to itself around that high spot.
Piles are driven under the water all the time. Have you ever noticed the ocean being blocked off every time they want to build a pier? Me neither. There are no photos of what would have been a rather large coffer dam.
As far as your speculation about sand under the bridge to support the arches, you may want to look into something called "scaffolding". It's been in common use for quite some time and has many advantages over enormous piles of dirt.
As far was you assertion that that fucking bridge was built there, you apparently forgot to link any photos of a time when that fucking bridge was not there, or when that fucking bridge was only partially constructed. But obviously your claim alone carries fucking conclusive evidentiary weight.
I trust everyone reading this is appropriately impressed by the demonstration of your knowledge of topography, construction, and engineering. I know I am.