'Tech' guys accurately measuring precise depths of pipe trenches. They said new drain will be set raised 50 to 80 cm above the main outlet (at corner of tennis courts). He told me some water will drain naturally thru the gravel layers surrounding the pipes - most flood water will collect 'n run thru the 8" dia drain-pipe. They are also installing 2 debri/sill bucket "traps" - one at the main outlet; the other at the cricket boundary (seen on the left of video). Good job!