Navigation Channel Dredging - Knik Arm Shoal Cook Inlet, Alaska

The channel dimensions for this Cook Inlet dredging project were approximately 370 meters wide, 13 meters deep and 2,500 meters long. Estimated dredging quantities were about 1,000,000 cubic meters.

Surveying in Cook Inlet is dangerous and technically challenging due to high tidal fluctuations and swift currents. Yet, in spite of these conditions, our hydrographers provided 15 surveys and a cable location with a high level of efficiency for the client.

Dredging surveys were conducted from the M/V Sea Ducer, our custom-built 30' aluminum survey vessel. We used an Odom DF 3200 Mark II Dual Frequency Echo Sounder, a Trimble Ag120 Differential Global Positioning System (DGPS), and a Coastal Oceanographic HYPACK & HYSWEEP hydrographic software package.

A survey to locate an existing electric cable was conducted to incorporate its location into the survey maps. This location information allowed the cables to be entered into the positioning software used by the construction contractor and engineers during operations to safely place their mooring anchors. We used a Radio Detection RD-600 Cable Locator with a marine sensor to locate the electric cable. This location effort required that toning be applied to the cable.

Following the surveys, we processed, reduced and analyzed the data that was collected. Maps were created showing the condition of the sea floor, cross-section sheets were plotted, and dredge volumes were computed.

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