Real-Time ROV Monitoring of HDD Punch-Out During Subsea Cable Landing on Guam

Contributing Authors:

Michael J. Wilder, CEP, Marine Biologist
Hugo Sanchez, Certified ROV Pilot

Subsea fiber optic cables carry more than 99% of international data traffic and are a core component of global communication infrastructure. Installing these systems requires precise offshore routing and controlled nearshore cable landing methods, particularly in environmentally sensitive areas. This case study documents the use of horizontal directional drilling (HDD) combined with real-time remotely operated vehicle (ROV) monitoring to support subsea cable landing in Guam. The approach enabled direct observation of HDD punch-out events, allowing for immediate verification of drill head location, reduced installation risk, and avoidance of coral reef impact.

Real-time ROV monitoring was used to observe HDD punch-out during subsea fiber optic cable landing on the West Coast of Guam, enabling direct visual confirmation of cutter head emergence. The approach allowed the drill team to verify and adjust punch-out location during active operations, maintaining all six conduits within the designated sandy seabed zone and avoiding nearby coral reef impact. Compared to conventional post-installation inspection methods, this real-time subsea monitoring reduced rework risk, eliminated delayed verification steps, and improved overall HDD installation accuracy and efficiency.

Key Metrics: HDD Punch-Out Monitoring, West Coast of Guam

Metric	Result
Monitoring method	Real-time subsea observation using a Deep Trekker PIVOT ROV
Operating depth	Over 100 feet
Punch-out detection	Sediment plume identified approximately 50 ft from the ROV, minutes before cutterhead emergence
Adjustment capability	Cutterhead retracted and repositioned during the active punch-out window
Verification timeline	Immediate, compared with days to weeks for post-installation diver inspection
Environmental outcome	No direct disturbance to the adjacent coral reef zone
Operational outcome	All six conduits placed within the designated sandy seabed zone, with no rework required

This case study falls under offshore trenchless subsea cable installation engineering with real-time marine inspection systems.

Submarine Cables and Their Role in Global Communication Infrastructure

History of Subsea Communication Cables and Global Network Development

How Fiber Optic Submarine Cables Are Installed on the Seafloor

In the fiber optic cable industry, cables are laid on the sea bottom following a considerable ship-board effort to locate the preferred route while avoiding a myriad of obstacles: protected natural resources, oceanic trenches, and seamounts–just to name a few. It is also preferred that cables not cross over other cables.

Laying a submarine cable is a highly complex process requiring meticulous planning and state-of-the-art technology.

The installation involves:

• Surveying the Seabed: Hydrographic and geophysical surveys to determine the optimal submarine cable route, identifying obstacles such as underwater ridges, tectonic activity zones, existing pipelines, and marine resources.
• Cable Laying Vessels: Specially equipped ships deploy cables using dynamic positioning systems to ensure precise placement on the seabed.
• Cable Protection: Depending on seabed conditions, subsea cables may be buried or armored to protect against external threats such as fishing gear, anchors, and seismic activity.
• Maintenance and Repair: Although designed for long-term durability, submarine cables occasionally require repairs. Remotely operated vehicles (ROVs) are used for deep-sea maintenance to inspect, and retrieve and replace damaged sections.

Challenges of Subsea Cable Landing in Nearshore and Coral Reef Environments

Nearshore cable landing zones present significant engineering and environmental constraints. Coastal seabed areas often contain protected marine ecosystems, including coral reef systems monitored by regulatory and scientific organizations such as NOAA Coral Reef Conservation Program.

Construction activities in these zones are subject to sediment disturbance limits, turbidity controls, and permitting requirements defined by agencies in the United States and their Territories, such as the U.S. Environmental Protection Agency (EPA), U.S. Army Corps of Engineers (USACE), and the U.S. Fish and Wildlife Service (USFWS).

Engineering and Environmental Constraints in Cable Landing Zones

While fiber optics cables are laid on the ocean floor, they eventually must be brought ashore to a dedicated cable landing station where they are connected to the grid, providing the communication needs of the general public, industry, and military. The process of bringing these cables ashore is just as complicated a process as laying them on the ocean floor. This process includes: surveying the seabed to determine the best location, while doing the least damage to nearshore marine resources, all while protecting the cable itself.

These cables can be laid on the bottom in shallow water where ocean energy is low, but must be pinned down in some way so that they don’t move around and get damaged. Sometimes, in high energy situations, trenches are dug and the cables are buried, called “cut and cover”. Sometimes, cables are pulled through conduits that are embedded into a bulkhead for added protection.

Horizontal Directional Drilling (HDD) for Subsea Cable Landing

What Is HDD and How It Is Used in Submarine Cable Installation

Horizontal Directional Drilling (HDD) is a trenchless installation method used to route subsea cables beneath the seabed in nearshore environments. In submarine cable landing applications, HDD enables conduit installation from an onshore drill site to an offshore exit point, avoiding direct disturbance of the seabed surface. HDD systems are widely documented in trenchless engineering literature and industry standards published by the North American Society for Trenchless Technology (NASTT).

Where natural resources are important and protected, cables cannot be laid on the surface or buried in shallow trenches. In these situations, cables are installed in conduits using Horizontal Directional Drilling (HDD). This process originated in the early 1960’s, in California, pioneered by Martin Cherrington (Father of HDD) as a trenchless alternative to traditional utility installation–which required cutting through roads. The HDD methodology allowed cables to be routed beneath roads, eliminating the need for cut and cover that caused traffic holdups.

Since that time, HDD has become an important part of installing fiber optic submarine cables under the ground in rivers, lakes, and the ocean all over the world. This is the case for some fiber optic cables on the island of Guam in the Western Pacific Ocean.

Limitations of Traditional Cable Landing Methods in Sensitive Marine Zones

Historically, cables landed on Guam were either laid on the sea bottom–protected in articulated pipe and pinned to the sea floor (surface lay)–or buried in shallow trenches (cut and cover). Both of these applications have been successful, but new environmental protection regulations often prevent such applications because the marine resources (corals) are too valuable to damage, or too difficult, or expensive to mitigate.

Benefits of HDD for Fiber Optic Cable Landing in Protected Coastal Areas

HDD is commonly selected for subsea cable landing in environmentally sensitive areas, including coral reef systems and protected coastal zones. By routing conduits beneath the seabed, HDD eliminates the need for surface trenching or mechanical disturbance in nearshore habitats.

Key advantages of HDD in submarine cable installation include:

• Reduced impact to coral reefs and marine ecosystems
• Controlled cable routing beneath high-energy shoreline zones
• Elimination of nearshore trenching and associated sediment disturbance
• Improved protection of cables from external damage (anchors, wave action)

However, HDD operations introduce a critical requirement: accurate control and verification of the offshore punch-out location. Deviation during drilling can result in the cutter head exiting outside the intended zone, potentially impacting protected habitats or requiring costly corrective work.

Case Study: HDD Subsea Fiber Optic Cable Landing on Guam

Project Overview: Cable Installation on West Coast of Guam

To avoid protected marine resources, the HDD method was used to go under them, and punch out the conduits on the sea bottom at a chosen site, seaward of the coral reef on the sandy bottom. This site was surveyed by a team of marine scientists using a remotely operated vehicle (ROV), a Deep Trekker PIVOT.

HDD Drill Planning and Offshore Punch-Out Targeting

Once the site was chosen, the drill team set up their HDD drill rig on a land-based site oriented to the punch out location. One of the most important aspects of this drill operation was to make sure that the drill-head punch out was within the selected punch out location. Any deviation in the directional drilling may have caused the HDD cutter head to punch out within a protected coral zone nearby.

To make sure that the cutter head punched out in the selected site and not within protected marine resources, a team of scientists from Guam-based engineering firm, Duenas Camacho Associates, Inc. (DCA) were on location to witness the punch out using their Deep Trekker PIVOT ROV.

Real-time observation of HDD punch-out events using scuba divers or ROV video systems is rarely documented in published case studies. Most recorded examples consist of post-event inspection imagery captured after punch out has occurred, often hours to days later.

ROV Monitoring Setup for Real-Time HDD Punch-Out Observation

The punch-out event was monitored using a Deep Trekker PIVOT ROV deployed from a surface vessel. “We coordinated with the drill team to determine the precise day and time and identify a 30-minute punch-out window.” The DCA research team had to be on site at least an hour prior to the punch out to assure the underwater ROV was on the bottom and in position to witness the punch out event in real time.

To position the system accurately, an anchor was set on the seafloor as close as possible to the GPS coordinates of the punch-out location and connected to a surface buoy. This reference point on the ocean surface enabled the vessel operator to maintain position directly above the target site at a depth of over 100 feet.

“We flew the submersible drone to the GPS location for the punch out site and settled it on the bottom at a depth slightly deeper, and oriented shoreward looking into shallower water. In this way, we only had to scan 180 degrees of ocean floor to make sure we witnessed the punch out. And then we waited.”

The team remained on standby while monitoring updates from the drill operator regarding cutterhead progression. Upon notification that the drill head was approaching the seafloor interface, the ROV was lifted off the bottom and maneuvered laterally back and forth to scan for visual indicators of the punch-out. As this type of real-time observation had not been previously performed, pre-emergence indicators were not definitively known.

Real-Time Detection of HDD Punch-Out Using ROV Imaging

“My knowledge of the HDD process, oceanography, marine biology, and the punch out site led me to believe that the sand and loose sediments in the vicinity should be disturbed by water flowing from the HDD cutter head. So, I was looking for some kind of disturbance of sediments on the seafloor,” noted Michael J. Wilder, CEP, Marine Biologist.

After only a few minutes, there it was, a swirling mass of sediments, approximately 50 ft in the distance just off to the left. The sediment plume indicated imminent cutterhead emergence. The ROV pilot was directed to reposition toward the disturbance area for closer observation.

The ROV was maneuvered into position and held station. Within approximately one minute, the cutterhead emerged from the seafloor.

“It emerged like an alien worm with a churning set of gnarly rotating teeth spitting out a plume of sediments and an interesting globular substance that was a combination of cutting fluid (bentonite) and sand. This substance is visible in the video as it spewed out from the cutterhead and floated up into the water column.”

The team immediately relayed confirmation to the drill operator:

DRILLER ONE, DRILLER ONE
WE HAVE VISUAL ON YOUR PUNCH OUT!
WE HAVE VISUAL ON YOUR PUNCH OUT!

Improving HDD Accuracy with Real-Time ROV Feedback

Based on real-time visual feedback, the drill operator requested information on cutterhead position and orientation. Using this input, the cutterhead was retracted several feet to achieve the correct exit placement.

Historically, repositioning of the conduit could not be done until days, or even weeks following a punch out, when scuba divers were deployed to inspect it, costing considerably more time and money. In this case, real-time ROV observation enabled immediate verification and correction during the operation.

Results: Improved Accuracy and Reduced Rework in Subsea Cable Landing

The integration of ROV-based monitoring provided:

• Immediate verification of HDD punch-out location
• Reduced risk of deviation into coral reef zones
• Elimination of delayed post-installation inspection for positioning
• Reduced likelihood of rework and associated project costs

This was a huge success for DCA Inc. The approach delivered a verified punch-out on the first attempt.

This project demonstrates the application of real-time ROV inspection in HDD subsea cable landing operations, particularly in environments with strict environmental constraints and limited tolerance for positional error. By utilizing the Deep Trekker PIVOT ROV, the drill team was able to make real-time adjustments to conduit placement, reducing rework risk and improving overall installation efficiency.

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