Incorporating lava rock in your landscaping

[MarkP]

I think the only practical way to separate the soil from the lava is with a hose. Wash it to a low spot and dig it up from there. While digging holes in lava for fence posts I have used a wet/dry shop vac to vacuum up soil and muddy water to clean a hole. Rinse (literally) and repeat until desired results are obtained. That's after the weeding, whacking, and burning described above.

There is no way you can use a bulldozer, excavator, or bobcat and still leave behind anything like natural lava formations.