One support suffered a head-on collision by a work boat which broke through both 

 jacket and pile wall, leaving a hole 5- by 1.5-feet wide. This was repaired by enlarging the 

 break to sound concrete, wrapping a steel sleeve around the section, and grouting the 

 broken area and the interior. 



(2) Maintenance. Regularly scheduled inspections are made of the structural areas of 

 the platforms, including a divers' inspection of the underwater parts. The only deterioration 

 noted has been the spalUng off of the Gunite coating on the steel collars and cross braces 

 (Fig. 54). All piling and bracing between water surface and platform are regularly 

 sandblasted and painted. This has been satisfactory in preventing corrosion of the bare steel, 

 but the owner feels that using galvanized steel would be advisable in the future. 



h. Effect of Structures on Environment. 



(1) Physical. Scour attributable to storms and surface waves exists at all structures 

 with the depth continually changing. Scour has reached a maximum known depth of 8 feet, 

 but averages 3 feet. However, no records have been maintained. 



(2) Biota. Some sea growth has developed on the concrete surfaces but more on the 

 steel. Fish are plentiful in the area, but concentrations vary daily because of the numerous 

 platforms. The Louisiana Wildlife and Fishery Commission is of the opinion that the total 

 fish population has not changed with erection of the offshore structures as evidenced by the 

 consistency of total tonnage taken annually by commercial fishermen. 



(3) Aesthetics. Due to location 25 miles offshore and in an area devoted completely 

 to the oil industry, aesthetics have had little influence on construction. 



i. Engineering (three concrete platform structures only). MagnoUa Petroleum Company 

 (subsidiary of MobU Oil Company), Dallas, Texas 75221; and Raymond Concrete Pile 

 Company, New York, New York 10001. 



j. Construction Contractors. 



(1) Onshore Prefabrication. Gulf Prestressed Concrete Products, Morgan City, 

 Louisiana 70380. 



(2) Offshore Erection. J. Ray McDermott, Incorporated, Harvey, Louisiana 70058. 

 k. Construction Date. November 1954 to August 1955. 



I. Construction Cost. Contract value: $1,500,000 (three concrete platform structures 

 only). 



98 



