Changing damage recieved by a block

There is a minigame called Spleef.
In that game, you dig snow to try to make other peoples falls.

For now, if you play with a diamond shovel or a stone shovel, it will make a small difference in the speed at wich you break snow.

What i want is make every shovel make the same amount of damage, but only if the damage are done to a SNOW_BLOCK.

So in the BlockDamageEvent there is a .getDamageLevel() but no .setDamageLeve(int) or something similar.

So, is there a way to achieve this ... or its just not done yet?