Soak hole turned out to be sheet drainage. Have removed a 1.5 m dia hole, chucked in some logs, twigs etc. and refilled it with the topsoil ready for the peach. Im now worried about the Tagasaste which can go down 10m, the citrus which need 3 to 4 feet for tap roots, and the Maqui berries which I cant find any info on whatsoever. This is a good lesson for planting urban sections - find out what the idiots have buried before you start.