Coho,
As one of the Structural Engineers in the crowd, be aware that the Black & Decker plans show 2x4 floor joists for wood stacked only 3' high based on the depicted 1x6 siding. You're not planning on going much higher for storing a single chord, but if you span 2x4's too far between pier blocks with 4 or 5 feet of wood stacked on them you may have a Homer Simpson moment