From Mod Wiki

The default surface type is stone. For all other surface types you will have to create shaders so that the impact sound/mark is correct for the material. Current surface types are as follows:

stone (default) puff of smoke, heavy boot on concrete surface sound
glass usually on glass func_explosive entities
grass steps brown bullet spray, springy footsteps
gravel steps brown bullet spray, crunchy footsteps
metal steps puff of smoke, clanky footsteps, metallic ricochet
roofs steps clanky footsteps
snow steps white bullet spray, crunchy footsteps
wood steps puff of smoke, hollow steps


A landmine is a small anti-personnel device used to blow up members of the opposing team. In order to allow players to place a landmine, there must be a floor surface with a surfaceparm type of landmine. This is a special surface type which can be used either on its own or with additional surfaceparm types.

As a rule only add the landmine surfaceparm to 'soft' materials like sand, earth etc. In the Enemy Territory game all wood / concrete / stone surfaces were excluded from landmine use.