simulating erosion w mesh collide

Hi! 

I'm trying to approximate erosion by dropping particles on a spring mesh surface with very plastic springs. The particles should deform the mesh as they slide down the surface. Is there a way to deform a mesh in this manner? Do I need to use other meshes as "drops" instead of particles, or is there a way to do it with just points? This might entail an incredibly dense surface mesh... not sure my computer is up to the task.

thanks-

Oliver