Conceptual Engineering Services Anchorage, Alaska

The Knik Arm Bridge and Toll Authority (KABATA) was created on September 15, 2003 by Alaska Statute 19.75.011 to construct a bridge across Knik Arm connecting the Municipality of Anchorage and the Matanuska-Susitna Borough.

Our role was to provide a multibeam survey of the project area and conduct Acoustic Doppler Current Profiles (ADCPs) at static positions and transects. Our hydrographers collected water level measurements, bottom sampling, water column sampling and drogue studies.

Reson 8101 and 8124 multibeam survey systems were mounted on vessels to collect the bathymetry data. All data was processed to correct for water level and velocity of sound in water.

Acoustic Doppler Profiling was performed with both stationary installations and across transects. We operated Teledyne RD Instrument's ADCPs mounted on catarafts for the stationary installations. The decision to mount ADCPs on rafts enabled us to more carefully measure the currents next to the sea floor. This part of the water column has the greatest effect on shoaling and scouring.

The stationary installations also carried satellite tracking equipment to monitor their location. Several times during the project the rafts were ripped from their moorings and had to be retrieved and reset. ADCP's were also mounted onboard the vessels for transects. Currents from transects and stationary installations were correlated in the final report with data collected from drogues.

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