I would say a truckload, because bananas radiations are making just a bit more crack noises than the background, here the Geiger counter go crazy. But without the background reading and units it's hard to tell
Serious answer would be, it depends on the underlying soil. Granite is particularly radioactive, to the point that yearly exposure to background radiation in Scandinavia (a granite penninsula) would be considered as crossing threshold of general population exposure to artificial sources (i.e. over background) in my country.
Also, famously, the dose of radiation in one of the long term storage facilities nearby (measured on the floor, outside containers) is lower than in the main church in that town, which, you've guessed it, is built from granite blocks.
A major rock-forming mineral is Potassium Feldspar (K-spar to geologists). The weathering products of K-spar include many varieties of clay. Those, in turn, wind up incorporated in sedimentary rocks
When logging a well for permeability -- an activity that occurs for both hydrocarbon and geothermal projects -- detection of radio-emissions due to K is an indicator of sedimentary strata that are unlikely to have much permeability because the clays clog up the fluid-flow pathways.
