As the kids say today, "I K o C M O T Y D K W a L L I * " it's a septic tanks drain-field.What's a leech line?
*=( It Kind Of Creeps Me Out That You Don't Know What a Leech Line is.") ya dig? No! Wait! No digging in the leech field area!
As Erma Bombeck February 21, 1927 – April 22, 1996, would say, "the grass is always greener over the septic tank." And she was right in her observations.