[¦dəb·əl ‚wȯl ′kȯf·ər‚dam] (civil engineering) A cofferdam consisting of two lines of steel piles tied to each other, and having the space between filled with sand.
double-wall cofferdam
A cofferdam formed by a double wall of sheeting (such as interlocking steel sections) and backfilled with soil or crushed stone.