A seabed trenching plow has a chassis, a sled and a towing assembly. The towing assembly has a pair of wings extending laterally from each side of the chassis. The wings are aligned on an axis transverse to the chassis and adapted for connection to a towing line. The transverse axis is forward of the center of gravity of the plow and rearward of the sled, affording an over the stern releasable and retrievable trenching plow of sufficient weight and strength to excavate a three meter trench in a single pass. To assess the protective capabilities of the trench, a threshold signal indicative of a desired composition of seabed-trench soil is compared with a real-time data signal indicative of the actual to produce an alarm signal when the real-time data signal is not protective-capability compliant with the threshold signal.

An apparatus features front blade sections fixed to the frame in a V-configuration, and a pull tongue extending over the blade apex to a pivotal connection near a rear of the frame. An actuation mechanism effects relative pivoting between the frame and the pull tongue to adjust an angle between the front blade and the trailer tongue to control a position of the blade apex. Two rear blade sections on opposing sides of the frame are movable between deployed positions extending rearwardly and laterally outward from the front blade sections, and stowed positions elevated out of the deployed positions. The rear blade sections are movable downwardly past a plane in which they align with the front blade sections, thus enabling different working operations.

A method and apparatus for installing a monitoring cable or other utility near an existing pipeline. An electromagnetic signal may be induced on the pipeline, either directly, or by transmitting a signal from a vehicle carrying a sensor array. The sensors disposed on the vehicle communicate with a processor to determine a distance and orientation of the vehicle relative to the pipeline. The signal may be electromagnetic, acoustic, capacitive, or the like. A plow or other digging tool may be on the vehicle or a secondary vehicle. Such a digging tool opens a trench and installs the cable along a path disposed next to the pipeline within an acceptable distance range from the pipeline. The vehicle may be remotely or automatically operated.

A plow attachment for an excavator, including a distal portion having elongated curved front and rear walls, and an elongated top wall, a pair of oppositely disposed elongated hook-shaped side walls connected to the top, front and rear walls and defining an elongated trough, a soil-deflecting wedge portion extending from between the sidewall portions and positioned opposite the top wall member. The plow attachment includes a proximal portion connected to the distal portion and having a flat skid plate member, a structural member connected to the flat plate member, and a hoe connecting member connected to the structural member.

A soil spreading scraper device has a cutting blade to cut soil from the ground and a rotating impeller member for spreading the cut soil as the frame is displaced forwardly. The impeller member includes a main disc body and a plurality of impeller blades on the main disc body which are pivotal relative to the body between a working position in which the blade body extends in a direction of the impeller axis away from the main disc body and a deflected position in which the blade body extends in a circumferential direction of the disc body in a trailing relationship relative to the pivot axis of the blade body. An actuating assembly resists displacement of the blade body into the deflected position until pressure on the paddle exceeds a prescribed holding force. A spring biases the body to return to the working position.