Retaining walls, Trench Drains, and Septic Tanks Dig a drench adjacent to hardscape (as close as possible) insuring depth is below where existing roots are found. After trenching, remove remaining roots, leaving walls of trench smooth. Place top edge of Biobarrier® at finished grade level, securing with installation strips and /or pins. Backfill carefully to … Continue reading Sidewalks, Paths, Streets, Kerbs, Medians, and Tennis Courts