[arebop]

I've heard there are concerns about disturbing the soil because it can trigger responsibility for dealing with the pollutants left by early valley hardware companies such as https://yosemite.epa.gov/r9/sfund/r9sfdocw.nsf/ViewbyEPAID/C...

[technofiend]

That is an excellent point and a great way to find yourself the proud owner of a Superfund site.