Appledore Engineering
The University of New Hampshire (UNH) recently tasked Appledore Engineering's team of professional engineer divers to complete an underwater inspection and facility condition sssessment of a 1970s-vintage pier reportedly in poor condition due to marine borer attack. UNH acquired the New Castle, NH, pier and property from the US Coast Guard to develop a marine research facility.

Level I (visual and tactile) inspections of 100 percent of the pier's elements and Level II (cleaning and measurement) inspections on approximately 10 percent of the pier's elements were performed utilizing Appledore's commercial scuba dive locker, which allowed for rapid mobility to cover the 600-foot-long pier.

The initial routine inspections confirmed the timber cribs supporting the pier were being consumed by Limnoria tripunctata, a marine borer that is able to tolerate the moderate levels of toxic creosote used to preserve the timber.

A detailed underwater damage inspection was then performed on two representative timber cribs utilizing a surface-supplied dive locker that allowed for a significant amount of work to be completed in a small area. To better evaluate the extent of marine borer damage, this operation included high-pressure water blast cleaning of the entire crib surfaces, and exposure of connecting bolts for torque testing.

The inspection confirmed the pier to be in poor condition, and that replacement, not repair, was the most cost-effective solution. Appledore's engineer divers followed-up with in-depth underwater surveys necessary in the design of the new pier. A bottom survey of an area along a revised alignment for the new pier, adjacent to the existing pier, was performed to assess surficial geology and confirmed the new pier alignment does not impact environmentally sensitive flora, fauna, or historical artifacts. A second survey included installation of Appledore's acoustic Doppler current meter, which uses acoustic Doppler shift technology, to accurately measure and record critical data that was entered into an onsite computer to process current velocity and direction for use in design of the new pier.

Upon completion of fieldwork, Appledore engineers prepared a detailed multi-media report presenting their findings and conclusion that the pier be replaced.

Subsequently, UNH secured a NOAA grant to fund design and construction of a new pier and marine lab on the site. Appledore is currently designing the new $4 million pier to support a variety of marine research vessels, including NOAA's newest Swath vessel. Pier construction is expected to be complete by fall 2003.

Appledore Engineering is a waterfront engineering consultant with 14 engineer divers on staff, most holding advanced degrees in the specialty fields of civil, structural, and ocean engineering.

Appledore's President, Lawrence Wagner, P.E., and Vice President, Robert Snover, P.E., are ADC-certified Surface-Supplied Air Diving Supervisors with over 30 years dive experience each. Appledore provides services to the US Navy worldwide, the US Coast Guard throughout the Pacific and Atlantic coasts, and industrial marine terminals throughout the US and Canada. Appledore's home office is in Portsmouth, NH.

Krech Ojard and Associates
In February of this year, Duluth, Minnesota's Krech Ojard and Associates was contacted by the owner of an ocean bulk material transload facility to perform an underwater inspection, analysis, and assessment of a wharf structure. Over the life of the structure attempts had been made to make repairs as they became critical to the operations of the wharf. Recently it was noted there was more movement in the dock than ever before when their large gantry crane moved up and down between the hatches during the unloading process. It had been many years since this dock had received a comprehensive inspection and everyone involved knew that a major problem was developing.

The 1950s-era wharf was a 1,200-foot concrete structure supported by steel H piling, built-up steel box piling, and steel sheet piling. The main support piling for the gantry crane legs was 16-inches square, constructed from steel channels and flat plate. The remaining support piles were 12-inch steel H piles, with a fendering system of wood timbers.

As the wharf degraded throughout the years, a variety of modifications were made to maintain integrity. These modifications included concrete encasements through the splash zone region, filling the 16-inch built-up pilings with concrete, PVC wraps, impressed current systems, and even new piling and steel support beams. Given all the changes to the dock structure, the task of inspection, analysis and assessment became very complicated. All of the past modifications were performed as quick fixes to address the immediate problems, with no insight to the overall problem and long term degradation. Krech Ojard completed the inpection despite the complications.

This approach to the care of shipping facilities tends to be common practice due to the lack of funding and need for facilities to remain in operation during repairs. Yet, the fact remains that, in most cases, proper well-engineered repairs can be made with minimal impact to operations and at less cost. Short-term and short-sighted quick fixes either make the condition worse or compound the problem in the long run.

The worst-case scenario in many of Krech Ojard's facility inspections has been the change in load path to areas and members of the wharf, pier, dock, bridge, etc. Change in load path can greatly alter the performance of a facility, and the designer of the quick fix repair has now altered the dock's capability to carry loads properly without causing or increasing the risk of damage to other areas.

A clear example of this was seen in one of Krech Ojard's latest inspections. The facility had severely degraded piling that supported the concrete beam and deck system. A repair had been made by driving new piling on each side of the center span of the concrete beams and connecting it together with a steel beam. The steel beams were then grouted so that the concrete beams would bear properly.

The plan for this system was that the original piling would corrode away and the new beams' support points would carry the loads, which in this case were from a gantry crane. What the designer failed to take into account was the original placement of the reinforcement in the deck beams. When the beams were analyzed with the existing placement of the new supports, the concrete beams were only capable of holding only 40 percent of their original design load. This quick fix to support the dock in essence did nothing but complicate the future repairs to the dock structure.

Proper repairs to dock structures are not as simple as finding visual problems and then patching things up. In many cases, changes in the use of a facility lead to the beginning of visual problems not previously detected. These visual problems, if not properly assessed, can lead to major repairs and or failures, which could become critical and would have been unnecessary if properly assessed in the beginning stages.

The most common change in use, which is ignored time and time again, is the increase in the size of the ship from the original design. Numerous facilities around the world are utilizing facilities designed prior to the 1950s. Most of these structures are not designed to handle the increased loads without causing damage, which in many cases is unseen below the water line. Proper recognition of the changes to the facility, reinforcement, rehabilitation, and inspection programs in the end save a facility the need for major repairs. If a facility budgeted money for proper inspections and analysis, major repairs and changes to facilities could be adverted, and proper planning could prevent unseen capital cost.

Krech Ojard prides themselves on assisting major facilities with planning, underwater inspections, condition assessment, and cost budgeting to insure the condition of their facility is maintained. This reduces the risks of unseen repairs, upgrades, and failures due to natural degradation, damage, and overload.

M&M Diving Service
M&M Diving Service, located in Eureka, California, is a small company that provides seasoned divers. All the company's personnel have 15 or more years in the industry and are able to describe problems found outside of the scope of work.

Recently, M&M inspected a circulation intake pump at a power plant with the minimum dive crew of three. The pump had been pulled for servicing, but no one had marked the alignment for reinstalling. When the pump was reinstalled, a terrible vibration occurred. The pump was shut down and the divers were called.

The dive team's job was to find the alignment keyway in the casing. Fifty years of no servicing of the casing resulted in cleaning marine growth and rust scale down to clean steel. Results were that no keyway existed - however, an alignment key was in place. Its position was noted and all was good.

Exiting the casing, the diver noted the patch installed 18 months previous. Heavy visual indications were present at 9:00, 3:00, and 6:00 in the perimeter of the corrosion hole.

The diving supervisor got the customer and showed him the live video and explained this should be explored at least by removing the heavy rust layer. The customer, however, wanted to get the plant back online and chose not to explore the potential problem.

A perfect example of "you can pay us now or pay us later."

The following day, after the pump was reinstalled and put in service, it stopped pumping. M&M was called back to investigate the problem. Inspection found that the pump casing had fractured 360 degrees and fallen to the bottom. The customer just looked at the M&M crew and said, "Maybe next time I will listen to your inspection advice."

M&M believes the indications were indeed cracks. The gap of the crack was enough for misalignment and vibration caused the crack to grow to the full circumference. The rest of the day was spent recovering the broken section sitting on bottom.

If the M&M dive team had it to inspect it over again, they would have inspected the patch area first, knowing that the structural integrity of the casing was in question. The casing, being 3/4-inch wall and with flanges, would have ruined the diver's day when it fell. Reporting relevant information to the client outside of the work order is extremely important. It is the customer, however, who decides to proceed or not. Safety is the real issue. The customer must trust the integrity of the dive crew. This trust can only be earned through experience.

General Robotics Limited
For many years the "Holy Grail" of underwater inspection in the North Sea was the inspection of nodal welds on platform jackets using ROVs. Despite the difficulty of inspecting very complex node shapes, regular inspection was needed to satisfy platform certification requirements. The development of ROVs with advanced manipulator toolskids led to the Stolt REMO, Sonsub's ATES, and, most advanced of all, Mobil/Perry Slingsby's ARM systems. However, just as development of these systems came to fruition, changes in certifying philosophy in the late 1990s led to a reduction in inspection requirements and they were mothballed.

As luck would have it, at about this time Woodside Petroleum in Australia saw a requirement for inspection of nodal welds on the North Rankin Alpha platform. This led to the development of a new ROV manipulator toolskid inspection system using the original ARM computer control system developed by General Robotics Limited (GRL), but adapted for the Schilling Titan range of manipulators.

The work was conducted by Covus Corporation, with the inspection personnel provided by SureSpek ISS, both in Perth, Australia. Covus developed a special new toolskid known as the Nodal Inspection Cleaning System (NICS).

Detailed advance simulation of the inspection work using the ARM computer software led to a number of important features being incorporated by Covus into the NICS design, including dual manipulator shoulder rotate systems, attachment claws with hydraulic fingers, a high-pressure water system, and an advanced inspection probe mounting for the ACFM NDT array probe.

The GRL / Covus ARM NICS system was first deployed in September 2000 to clean and inspect five large nodal welds on North Rankin. It was up to 10 times faster than the manual manipulator weld inspections conducted in the North Sea.