Septic pump squirting

I just replaced my septic tank pump that pumps to the mound system. It wanted to make sure it all worked properly, so I lifted the on/off floats with a couple of rakes and it worked! I was shocked though because a hard stream of water was shooting out of the side of the PVC riser. Is this on purpose? I can’t believe I didn’t notice a hole in the pipe when I had the unit out of the ground.

Could it be to let the pipe drain after the pump turns off? But, wouldn’t the water drain beck through the pump anyway?

Or could it be to relieve pressure while the pump is pumping?

Thanks!

Unless it is cracked / broken it is there to prevent the pump from becoming air locked.

You should also have a check valve and it should be below that.