Here's how you fix this. We're going to dig up the streets and replace the sewers. The new sewers will be all steel. There's going to be flame throwers, and spiders inside.
Then, whenever one of these fatbergs exists, we'll just blast the flame throwers, and it'll burn it to nothing.
Eating flies. We've also planned ahead for lizards to eat the spiders, snakes to eat the lizards, gorillas to eat the snakes, and winter to kill off the gorillas.