You can put in at the south end of the soccer fields off of Sunbury Rd. just south of Easton Way and take out at the Bexley Pool parking lot. Or you can put in at the Bexley Pool and take out at Heron Pond in Three Creeks Park. There is also a takeout at Watkins Road about a mile above Heron Pond, but that one is a couple of hundred yards from the parking lot. Heron Pond isn't an official access, but if you pull out there on the bank, it is a short pull through the woods to the parking lot. I've used it a dozen times or more. Both of those floats are around 6 miles.
The toughest part of an Alum float is finding a good water level as it fluctuates wildly from runoff. If the Livingston Ave. gage is around 2.5 feet you are good. If you get much below that, there is dragging involved. If it gets close to 3 feet, you are going to be zipping along pretty quickly.
USGS Current Conditions for USGS 03229000 Alum Creek at Columbus OH x