The effect:
class GrenadeExplosion ->class MineWater1
is spawn effect of water splash.
It spawns even when grenade explodes on the ground (even if there is no water near, but ground level is close to sea level)
enabled="distToWater interpolate [-5.0001,-5,-1,1]";
Probably it spawn every time when grenade explodes at level > -5 m from sea level.