THE FEDERAL HILL AMMO DUMP

"In 1917 a building was erected on the base of Federal Hill for the purpose of making ammunition for World War I. The foundations of this building can still be seen along with a small cave where ammunition was stored. Any ammunition which was faulty was dumped into piles on the east side of the hill. About 10 years ago some was found, but nobody has found any since."

--From my 1964-ish Riverdale School report
on the History of Riverdale

(Note: The building was in the center of the south side of the Hill, atop a very large rock. The "cave" was a small storage area carved into the side of the mountain right behind it. The storage area was about the size of a large closet.)