Dumping Sites store 70 waste rock. Waste rock is produced as a side product of mining basic resources .
Without a Dumping Site the waste produced by Extractors (e.g. Metals Extractor) will be stored around the edge of the extractor until it impedes (or prevents) production.
With a nearby dumping site the waste is transported by Drones away from the extractor until the site is full. Drones can still navigate between multiple dumping sites when they are tessellated on the surface but move at a reduced speed through the field of debris.