Rockdumping

The Coast Guard assisted by supervising the rockdumping and by securing lines to the barges to stabilize the dump.

Source: wiktionary

Or the trench may be too shallow in some places which requires additional rockdumping on the line to attain stability.

Source: wiktionary

Should the cable protection system be too buoyant, it is less likely to remain in contact with the seabed, thus the CPS is more likely to require additional remedial stability measures, such as installation of concrete mattresses, rock bags, or rockdumping.

Source: wiktionary