Apparently, McVeigh used less than 50 gallons of diesel fuel in the Oklahoma City bombing. He made about a 7000lb payload in delivery van that "destroyed or damaged 324 buildings within a 16-block radius, destroyed or burned 86 cars, and shattered glass in 258 nearby buildings, causing at least an estimated $652 million worth of damage." (from wikipedia).
Not sure how much C4 it would take to come close to that but I'm betting
the Colony doesn't have it. AN, diesel fuel, primer/blasting caps, some catalyzing agent. i bet they could come up with that....
And then there's always Redshirt's Pantex call.....