IMG_0478 Published 2014-05-29 at 3000 × 2250 in Biorock Sewage Treatment Plant Installation The primary tank (foreground) and the Biorock tank with concrete back-fill. The inlet pipe is just temporary to permit the tanks to be partially filled to resist the pressure of the back-fill. IMG_0478 by Marsh Flatts Farm Self Build Diary is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.