First, maybe because it was a transcript, "chucking" translate to "chunking"? Kind of up there with relying too heavily on Word's spell checker <lol>
I wonder, however, if WC meant another entrance to the Evansdale Nature Trail that is a bit further west of Elmer Ave? If you follow Gilbert west and pass Elmer Ave until almost to Jonas Rd (opposite, north side of Gilbert), there is a section marked on the map "Evansdale Nature Trail" that goes south and intersects with the trail proper. It passes an (empty) warehouse building that had caught my eye some time ago. Also, from Elmer, there really doesn't look to be that many houses/buildings where people might have seen them. IOW, not Exchange Park/boat dock, but a bit farther west. It does still match up to LE's areas of late.
to chuck/chucked/chucking is to throw carelessly, toss, etc. btw