The main ground (around here) is required to be on the street side of the meters, because gaskets may interrupt the connection.
A visible cable jumper around the meters is used.
No need for a new clamp, but the connection occasionally corrode.
No need to ““bury a metal plate in the ground) with a grounding wire attached”.
IIRC mine was four or five feet in length, if the earth is soft easly pounded in, the rods are steel and copper plated. NOT REBAR.
Needs a tag: https://www.garvinindustries.com/fittings/grounding-clamps-straps/electrical-connection-warning/j-tag
If the ground is hard, a rotor hammer with a socket is used.
Technically the main ground should be one continuous wire from the main ground (earth) to the main panel.
Hopefully, you have resolved the problem already.
Thanks for the follow up. There are definitely two wires attached to the water pipe with the whole house cut-off handle. These two wires go behind the dry wall in the direction of the nearby basement and first floor electric boxes, each of which is attached to an above ground meter. The water meter is several feet down in the ground surrounded by a round container with a metal lid on the surface of the earth.
Other emergencies have prevented me from following through with the suggestions already received. Once there is some forward movement I may post again.