Grassed over improves water entry to the hill (instead of forming small streams and running downhill as it might on a dirt hill), and also prevents erosion.
It would work with wood chips just fine, but you may want to supplement with actual logs as well. Otherwise you'll need to build your hill very high, or keep rebuilding the hill for a few years(a pile of wood chips has way more air in it than a log, and will compress way more than log would).
It would work with wood chips just fine, but you may want to supplement with actual logs as well. Otherwise you'll need to build your hill very high, or keep rebuilding the hill for a few years(a pile of wood chips has way more air in it than a log, and will compress way more than log would).