This micro cache is along the Riverfront Bike Trail that runs from Laclede’s Landing to The Old Chain of Rocks Bridge, and is at the site of a failed 1855 slave escape.
I’ve never been anywhere near this cache by car, but here’s some directions from the Confluence website:
(By car) From downtown St. Louis, take I-70 West to the Adelaide exit. Turn right (east) on Adelaide, which ends at Hall Street. Turn right (south) on Hall and proceed to Prairie (this part of the route is through an industrial district). At Prairie, turn left and park near the ADM grain elevators, at the break in the floodwall. The Riverfront Trail is on the river side of the floodwall. The Meachum site, containing a marker, is a short distance to the right (south) and can be reached on foot or by bicycle.