Underwater Construction Corporation (UCC) completed the installation of a fish barrier net for a large hydroelectric facility located in Missouri. This net was located upstream from the dam and enclosed the powerhouse to restrict the aquatic life from entering the generating turbines of the facility.
The scale of the project required the use of equipment and material barges. These barges facilitated enough space to allow for a complete deep water dive package, a 70 ton crane and enough area to hold all materials for each task of the project. Each barge was manipulated with the use of push boats along with a hydraulic driven anchor system to stabilize the platform on location while work above as well as in water was being performed.
The deep water dive package included UCC’s own decompression chamber system and all other equipment required to successfully run multiple air and mixed gas (NITROX) dive operations. This specialized equipment on-site allows the UCC dive team to be self-sufficient during the length of the project while successfully completing more than 170 dives including planned surface decompression dive profiles to depths greater than 100 ft. The use of mixed gas and surface decompression allowed for extended bottom time for the divers meaning more production and less down time for the project. Along with the equipment, UCC provided a complete dive crew proficient in the use of mixed gas and decompression procedures including our own deep dive specialist to oversee all operations.
The net anchoring system consisted of large concrete blocks averaging in size from 2-6 tons per piece. This system was made up of both lower net anchors (21) and tie back anchors (13) that are designed to conform to the original configuration of the barrier. The crane barge was used to set these blocks remotely with a hydraulic release which was operated from surface or with diver’s assistance. In order to guarantee the correct location of each anchor, HYPAC hydrographic software was used. Using this software, UCC was able to position each block within an average of one foot or less to the planned location in as much as 110 feet of water.
During the first stage of the project, UCC’s dive team completed all structural work as well as the remote setting of all concrete anchors for the barrier net. During the second stage of the project, UCC’s dive team completed the initial anchor connections for the 900 foot net within two working days. The remaining tie backs, debris netting and final project inspections were completed shortly thereafter with the use of UCC’s two dive skiffs. All connections and hardware were verified and documented per specifications and planned drawings.