So another way to put what your asking (to rephrase your question) is:
What should I use for base current to guarantee saturation ?
In this case I (col) should be 0.150A
To guarantee saturation, assume the gain is minimum (40) so
0.150/40=0.00375A (3.75mA)
If you assume a base-emitter voltage of 0.9 V when saturated:
5V-0.9V=4.1V
4.1V/0.004A (4mA) =1025 ohm
You can use a 1 k resistor for the base resistor and the arduino output will drive it to saturation.