Due to the chemical spill, the commute into the city will be delayed

We do use "due to" to explain reason or cause. But note that "due" is adjective and hence it should refer to a noun (the effect of the cause). The thumbrule is as follows:

If the effect is noun, use "due to" before the cause.
If the effect is verb, use "because of" before the cause.

The game stopped BECAUSE OF rain....correct (The effect is verb: stopped).
The stoppage was DUE TO rain..... correct (The effect is noun: stoppage)
(Do not get confused about the cause - the cause "rain" is noun in both cases.)

Similarly in the subject question,
The commute will be delayed BECAUSE OF spill. (The effect is verb: will be delayed)
The delay will be DUE TO spill. (The effect is noun: delay)
(The cause "spill" is noun in both cases.)