Fixing a Low, Flood-Prone Backyard with a Dry Sump

A 3-foot-deep rock-filled trench in the yard center (dry sump) helps slightly but silts up in 15–20 years. It's a band-aid. Better: intercept water before it enters your yard (swale, pipe, gutter). If not possible, test subsoil percolation: dig a hole, fill with water, measure drain time. Over 60 minutes/inch = poor drainage = more gravel needed.

Community yard likely has metered outflow. Your sump is a bathtub with rocks—if the 'drain' (subsoil) is slow, it overflows. Heavy clay = failed sump. Sandy soil = works well.

Long-term: regrade with a perimeter swale directing water to a proper outlet.