Irvin Centeno heads... - California State Parks workers on Backbone Trail - latimes.com Brian van der Brug / Los Angeles Times / August 30, 2012 Irvin Centeno heads off to work along the Backbone Trail in Pacific Palisades. Part of a state parks crew, he and some of his work mates are from urban Los Angeles and have traded the streets for trees, chaparral and overnight campouts.