We are doing just that at the Crescent
City Food Forest:
https://permies.com/t/99256/Crescent-City-Food-Forest
It may be California, but it feels very much like the Pacific NW climate (I grew up in Seattle).
This seems to me to be the best place possible to do tall hugels. We have abundant woody debris available for virtually free, and the Pacific NW of the US is somewhere nurse logs, which hugels imitate, are integral to ecosystem function. This is largely because we have abundant rain for 40-60% of the year but almost none for the rest, requiring large woody debris for moisture retention (75% of the available water for plants in an old growth NW forest in August is in dead wood). A couple recommendations:
- avoid redwood or cedar
- use wood in as close to the state you find it as plausible (lopping off wonky branches is fine, but burying chips is counter productive)
- use clean wood (watch out for persistent herbicides from adjacent lawns, roads, farms etc, these can last decades in wood that absorbed it while alive and likely died from it)
- make sure all the wood is well buried to avoid wicking of water out of the bed
- should go without saying, but do not make a dam out of a hugel, and this essentially what one would be doing with an ill advised "hugel-swale" perfectly on contour without adequate alternate overflow. Its better to have a gentle meandering slope for edge, drainage, and microclimate benefits.
- dig in if you have sandy soil with exceedingly good drainage (improving water retention, but requiring more work and losing microclimate/windbreak effects)
- just build right upon the sod or weeds if the soil is clay or that spot gets boggy at times (improving drainage)