I'm using pressure treated, ground contact lumber like this one bought from Home Depot for an outdoor project in my backyard. Parts of the lumber are buried underground, and some of the buried ends are cut by me before burial. I don't apply any sealants on top of the pressure treatment. I called Home Depot to confirm that burying even after cut is OK, and they said it is, and that it's expected to last 25 years. When I look online (at blogs etc.) to confirm though, I see that some people recommend at least 0.40 lb./cu.ft.chemical retention. The Home Depot lumber I use has only 0.15 lb./cu.ft. Is the discrepancy because Home Depot uses some superior chemicals that requires less lb./cu.ft.? Can anyone confirm from experience that such department store lumber lasts as long as they claim?