Hermosa and Manchester Fiber Optic Cable Lay
eTrac completed cable route surveys of two landing sites in northern and southern California. The client required information on any obstructions along the proposed route corridor, the gradient of the slope the cable would cross as well as a detailed understanding of the surface and subsurface sediment type. A full suite of geophysical survey equipment was mobilized on three vessels to obtain data up to the shoreline in environmentally challenging conditions. High resolution multibeam sonars were installed on a traditional survey boat as well as a WAM-V autonomous survey vessel (ASV). The two vessels worked in conjunction with each other to obtain 200% multibeam coverage across the route corridor above 0ft lowest astronomical tide and in a surf zone. A larger survey vessel was used to tow a dual frequency side-scan sonar with tandem towed magnetometer, as well as a CHIRP sub-bottom profiler. The combined dataset was analyzed to produce a detailed report on the environment of each potential cable route. The data was of high enough quality and detail to be able to detect and accurately locate, small debris, sand dollar beds, rock outcroppings and changes from sand to clay sediment. Cables as small as 6″ diameter crossing the route were picked up and tracked by the magnetometer.