A few suggestions
Have gates which can be open or closed or turned by powering them to redirect the flow of creeper.
A deep well which would swallow up the creeper. Used with the gates above might make some interesting gameplay.
It would be interesting if you could create a pit or well which would be able to temporarily hold back the creeper until it filled up. Would be like having a temporary blocker if you needed just a little bit more time. Gates would be odd, and why wouldn't the creeper just plow down a gate? A well can't be because it is just a hole. I like the idea of a well/hole though!