Youtuber komodoyago (whose colleagues performed this experiment) sez:
The test was performed with a box of camp waste (largely food rests) in a bin bag. Estimated weight 30kg, Size 60x60x60cm. Fall height, about 80m. The lake reacts with violent lava fountaining activity, presumably in part due to steam produced from the organic matter.
Fingal County Council wishes it had one of these.