Solution: Take the center O of the cone bottom, connect OS and OA, and then

∠O=∠ABC=90，OS∨BC，

∴∠ACB=∠ASO，

∴△SOA∽△CBA，

∴ = ,

∴OS=，

∫OA =≈5.5，BC= 1.6，AB= 1.2，

∴OS= ≈7.3，

The depth of the cone pit is about 7.3 meters.

So the answer is: 7.3 meters.