The PlaneWave CDK400 system is mounted on a massive concrete pier. The pier is 30” in diameter and rises 4.5 feet above the observatory floor in order to put the intersection of the right ascension and declination axes of the L500 mount at the center of the 10’6” Ash Dome. This massive pier is necessary to handle to torques of the L500 direct drive mount. The cylindrical portion of the pier above ground weighs about 1 ton and there is an equal amount of concrete in the ground as a rectangular footing with a cylindrical projection into the ground beneath that to prevent the pier from leaning over time. The pier is extremely stable. I can open and close the observatory door, walk around on the observatory deck, and the dome motors can rotate the dome to update the alignment of the dome slot with the telescope aperture, all without jiggling the telescope/mount and ruining a sub-exposure.