Soil Types.....

I looked at the soil types around the Fitzroy Province.....this area extends east from the Dampier Peninsula to Wolfe Creek.....including the towns of Broome, Derby and Fitzroy Crossing.
Fitzroy Province is divided into 5 different zones based on soil and landscape. Djimbardi is in the North Fitzroy Plains Zone.....characterized by Floodplains and sandplains on Permian sedimentary rocks of the Canning Basin. Self mulching cracking clays with red deep sands, red sandy earths and red/brown non cracking clays, Yellow sandy earths and yellow loamy earths ( Loamy- 1)an easily worked fertile soil consisting of a mixture of clay, sand, and silt and sometimes also organic matter 2)a mixture of moist clay and sand used for making bricks and in plastering).

Based on this I would say it is possible to have some underground construction on our site.