Etymology: < dumpv.1 + -agesuffix.Previous versions of the OED give the stress as: ˈdumpage.
U.S.
The work of dumping or emptying out refuse, ballast, etc.; the privilege of doing this on a particular piece of ground; the fee paid for this privilege.
ΚΠ
1864 in Webster's Amer. Dict. Eng. Lang.
This entry has not yet been fully updated (first published 1897; most recently modified version published online June 2019).