Submersible Surveys of the Deep Seawater Pipelines at the Natural Energy Laboratory of Hawai‘i Authority (NELHA)

John R. Smith, Christopher D. Kelley, Jan C. War
University of Hawai`i, United States

Keywords: HOV, ROV, submersible, inspection, survey

The Natural Energy Laboratory of Hawaii Authority (NELHA) currently operates three deep seawater pipeline systems to provide cold seawater to a variety of tenants using this resource for desalinated bottled drinking water, aquaculture products (including nutraceuticals), and cooling applications. These pipelines, with intakes at 620, 674 and 920 meters, require periodic inspection to determine the condition of fittings, pendants, and anchors. NELHA charters the University of Hawai‘i’s Pisces human occupied vehicles (HOVs, or submersibles) for such inspections because untethered free-moving vehicles have a lower chance of entanglement in the variety of gear associated with the pipes. Unlike tethered, remotely operated vehicles (ROVs), the submersibles can safely inspect the condition of fittings and anchors on the sides and undersides of suspended pipe sections in unfavorable currents. Submersible video from recent inspections is presented to show how the vehicle was maneuvered to obtain the information NELHA requires to maintain the condition of their pipelines. The Pisces submersibles have also been used to survey pipe and power cable routes for proposed alternative energy projects in Hawai‘i. The submersibles are a valuable tool for state and federal agencies, along with entrepreneurs interested in developing these new industries.

← Back