Problem: The ground at the back of the back yard is 3" higher than the sidewalk by the dining room.
In big rains water from the back yard drains over the sidewalk by the dining room and into the front yard.
I could have tried to put a drain to catch that water from the back yard and drain it to the front but there were logistics problems, digging up plantings, going under a fence and around tree roots in the front yard.
See Plot Plan
I originally miscalculated and thought I could go under the back fence which would give me 8" of drop or 2" per 10' for a 2% grade recommended for corrugated pipe. When I found out the ground behind the fence was 4" higher I only got a 1% grade. The ditch is deeper at the end than needed but will act as a catch basin to hold some of the water until it soaks in.
