A Surveying First

C. H. Fenstermaker and Associates performs underwater acoustic surveys that provide image visualization of underwater features for the first time on record.

C. H. Fenstermaker and Associates performed the first underwater inspection of the Huey P. Long Bridge which spans the Mississippi River in New Orleans, LA.  Thebridge, having been put into service in 1935, is set to undergo a major expansion requiring extensive modification to the upper section of the bridge piers.  A detailed inspection of the bridge piers to assess their condition and establish a baseline was needed before commencing construction of the expansion project. Fenstermaker, as a sub consultant to Modjeski & Masters, Inc., was commissioned to evaluate and record the condition of the bridge piers using underwater Acoustic imaging technology.  The inspection of the bridge piers was accomplished by deploying a set of Kongsberg-Mesotech steered beam sonar/profilers from a barge work platform positioned along each face of the piers.  A rotating guyed tower mechanism designed by Fenstermaker, was used to deploy the sensors to the necessary depth and direct the acoustic scan patterns while maintaining the stability necessary for high-resolution imaging in a severe water current environment.  The high definition acoustic visualization allowed observation of the bridge piers and support caissons with the capability of distinguishing the grout seams between the granite armoring on the upper section of the piers.  The water depth at the piers varied from 36’ to 98’ requiring different deployment elevations at each respective pier.  The entire inspection required five days on-site with two additional days of mobilization time.  The information gathered served dual purposes for the Louisiana Department of Transportation and Development.  First, the surveys confirmed the condition of the piers establishing an objective record that the piers are in very good condition.  Second, recorded sonar data and translated image visualization will serve as a baseline reference of the pier condition prior to commencing construction of the extensive bridge expansion project. 

On a second project, the Fenstermaker Underwater Acoustics team performed the first ever acoustic imaging and profiling investigation of Buffalo and White Oak Bayou at “Allen’s Landing” in downtown Houston, Texas for Harris County Flood Control District. The survey encompassed the confluence of the waterways and approximately 750’ along each branch of waterway. The survey was accomplished by utilizing a Kongsberg-Mesotech steered beam sonar / profiler that was attached to a small 18’ flat-bottom survey vessel.  High definition sonar data for image visualization was acquired over the described area along with a high definition sonar inspection of the face of the sheet-pile wall along the east bank of the bayou adjacent to the confluence. A precise acoustic profile of the water bottom and embankment of the bayous was also performed. The sonar data showed a visual representation as well as precise measurement information with respect to features and undulations of the water bottom. This survey, while providing first-time visualization beneath the surface of Buffalo and White Oak Bayou, also provided a baseline reference of the stream bottom condition and contour. 

About C.H. Fenstermaker
C.H. Fenstermaker is a multidisciplinary consulting firm founded in 1950. The company’s expertise includes civil engineering, surveying and environmental consulting. Fenstermaker’s offices are located in Lafayette, New Orleans, Baton Rouge and Houston.

For more information contact
Ken LaBry
Manager – Underwater Acoustics Group
C. H. Fenstermaker & Associates, Inc.