Few people are aware of how much they benefit from those who toil beneath the seas, lakes and reservoirs. From dam maintenance, hull repair and pipeline welding to dredging for boat lifts to constructing dry docks and locks, underwater work is a complex – and sometimes dangerous – undertaking. As with construction and restoration above ground, careful design, preparation and inspection are required for a project to succeed. An underwater survey is needed to comprehend the subsurface terrain. Certain best practices should be followed to maintain accuracy, precision and, above all else, safety. Some of them are listed here.
Multiple Surveys for Multi-Phased Projects: Dredging, for example, is performed in four phases – excavation, lifting, transportation and placement. Sometimes an initial survey is no longer operative after excavation because sand, sediment and other matter is displaced. Similarly, after vertical transport, the area will have again changed after the excavated materials are removed. Each phase of the project should proceed from an in-time representation of underwater conditions rather than assumptions based on an earlier survey.
Surveying after Storms: The effects of hurricanes and storms go far beyond flooded communities and power failures. Currents resulting from the churning of warm surface water with deeper and colder water can reach depths of 90 meters or greater. In doing so, they can decimate coral formations; tear up beds of undersea fauna; and do harm to a large swath of marine creatures. These changes significantly alter conditions on the floor, necessitating a new survey.
Regular Surveying Due to Shoaling: Port and wharf administrators have an absolute need to know the operational depths of their berths where vessels are moored and supplied. The constant movement and accumulation of sediment and material beneath the surface – known as shoaling – can substantially amend that depth, posing danger in terms of a ship’s under-keel clearance. An orderly and consistent survey regime gives marine terminal operators confidence as they direct incoming and outgoing shipping traffic.
Surveying after Loss: Items large and small, shipping containers included, are often lost from maritime vessels or – in some cases – fall from docks. These can serve as obstructions in shallow waters so reconnaissance surveys are employed to map them and, many times, recover them. Three technologies dominate these efforts – side-scan sonar, magnetometer and multi-beam echo-sounding. The sonar works best for berthing areas although the magnetometer gets the edge with metallic items. The multi-beam approach is restricted to locating anything that has not sunk into the sediment.
Preparing ahead of a Dive: Survey diver teams do well to have an emergency aid list at the ready before a dive. Contacts should include information on the decompression chamber closest to the project site; nearest hospital and available physician; emergency transportation; and a rescue number for the Maritime Border Command or corresponding service. A comprehensive first aid kit should include a resuscitator with a transparent hose and mask. All diving and survey equipment should be inspected thoroughly.
Practicing Safety during a Dive: A platform or ladder is best for entering and exiting the water, and provision should be made for conveying any injured diver to the surface. Changes in pressure and breathing gas can be monitored and recorded by a crew leader or dive participant. Furthermore, a protocol should be established as to the conditions under which a dive should be aborted. If a diver fails to respond to instructions for example, or communication is disrupted, there may be cause to terminate the dive. Use of reserve breathing apparatus also would occasion the temporary ceasing of operations.
Evaluating Health following a Dive: Divers should receive a rudimentary examination, especially after deep dives. Decompression can sometimes cause illness and the symptoms might be slow to appear. Those diagnosed require a decompression chamber, i.e. a hyperbaric compartment that infuses cells and tissues with a high oxygen concentration, thereby repairing any damage.
Confirming Survey Credentials: Underwater survey divers like those at Southern Divers Ship Surveys comply with the highest standards and comply fully with government regulations. They should always maintain a record of safe practices, quality work and environmental stewardship.
Lisa Eclesworth is a notable and influential lifestyle writer. She is a mom of two and a successful homemaker. She loves to cook and create beautiful projects with her family. She writes informative and fun articles that her readers love and enjoy.