Surely the diesel and oil could be removed very easily? Anyway, this comment on the article you reference is interesting: "The truth is somewhere in between,

Surely the diesel and oil could be removed very easily? Anyway, this comment on the article you reference is interesting: "The truth is somewhere in between, if the JCB's were mini diggers and secondhand it would make economic sense to bury the kit and not a lot of space would be lost..." Also this quote from http://www.itv.com/news/london/2014-06-06/hundreds-of-jcb-diggers-have-been-buried-beneath-london/ http://www.itv.com/news/london/2014-06-06/hundreds-of-jcb-di...: "The diggers used are tiny little machines and they can be lifted out with a block and tackle. There is always an exit strategy for the equipment."