There was a short-lived town called Port
Walthall on the Appomattox River in VA. The
dock was shown on one of the A. D. Bache maps
in the 1840's. It's also discernible on some
of the Petersburg theater maps in the
Official Military Atlas of the Civil War. The
pilings are still above water and exactly
reflect the shape on the Bache map. Basically
vertical pilings and "x" members nailed and
bolted together.

Also, you might look at the Brady, Gardner,
and other Civil War photographers. They took
photos of the docks at Hopewell after the
unsuccessful assassination attempt on A.
Lincoln.

Lyle