Hello,
I'm gonna tell you how we do that over here.
When I read an article like that, all bells gonna ring.
I saw that they gonna dig it and transport it to a dump I guess.
You need to find out when the digging starts, and when they are active, ask the drivers were they gonna dump that sediment.
When u know that, and after a few days when the water is dropped out..
Ask permission and detect that!
90% off all metals will be in that sediment.
Let me know how it did go.
This sir is the cherry on the pie. (If it's an old lake)
Greetings from Holland.
Harald.
Sorry for bad English.