In large installs, I have seen rotors sink down because they are placed in the deep trench machine cut for the pipe. That thing about placing a rotor on a base of undisturbed soil helps to prevent sinking vs throwing the rotor in the soft backfill dug up by the trencher. Its bad when an I25 cannot clear a lawn cut at 1".
They who can give up essential liberty to obtain a little temporary safety, deserve neither liberty nor safety.
Benjamin Franklin 1775
Sell not virtue to purchase wealth, nor Liberty to purchase power.
Benjamin Franklin Poor Richard's Almanac1738