Two Heavy Weights for New Orleans Surge Barrier
British piling equipment manufacturer BSP International Foundations has supplied two of its largest hydraulic piling hammers for the construction of the world’s largest surge barrier designed to protect the coastal city of New Orleans in Louisiana.
Known as the Inner Harbour Navigation Canal (IHNC) project, the two BSP hydraulic piling hammers,
a CG240 and a CG300, were supplied last June to Traylor-Massman-Weeks (TMW), appointed by main contractor Shaw Infrastructure and Environmental, to carry out the piling works on the project. Both hammers were supplied by Jinnings Equipment, based in Fort Wayne, Indiana and the Midwest distributor for BSP International Foundations in the USA.
TMW is using the hammers to drive the 600 steel batter piles, 61m long and 914mm in diameter, at a 45 degree angle on the inland side of the barrier to support lateral loads. When completed in 2011 the surge barrier will be 3.21km long and 7.9m high.
The crane-suspended CG240 with a 16t ram weight is driving the piles on a day to day basis while the larger CG300, equipped with 20t ram weight, is on standby and used when driving is difficult as it has the extra power needed to drive a pile to the required depth.
Both hammers have been designed by BSP to operate from pilling rig leaders or crane-suspended and are suitable to drive s wide variety of load bearing piles and include hinged type back guides to allow quicker installation onto the leader. Fitted with a BSP remote control panel, the CG range is capable of delivering an infinitely variable stroke and blow rate enabling precise delivery of energy to the pile thereby allowing the contractor to maximize production, avoid pile damage and problems of pile runaway.
A major feature of the CG hammers is the design of the hydraulic actuator which, for a given blow rate and energy transference, results in less fuel consumption and reduced exhaust emissions Piling helmets are also available to efficiently transfer the hammer’s impact to the pile. Using a BSP manifold control valve the CG range can be connected into existing power supply from a hydraulic piling rig or crawler crane base.
The surge barrier is a key element in a 100-year plan to protect New Orleans and surrounding areas. It will have to resist the tremendous impact of a water surge which originates from the Gulf of Mexico during a hurricane and may enter the Inner Harbour Navigation Canal. The barrier extends across the IHNC from the north of Louisiana’s Gulf Intracoastal Waterway to the south of the Mississippi River-Gulf Outlet.
In addition to the two BSP units TMW has assembled an impressive array of plant and as the barrier is being built from the water, all the cranes and pile driving equipment are mounted on barges. There are around 50 barges and other items of equipment floating at any one time and moving around the project. Several phases of the wall are being built simultaneously so round the clock, seven days a week working is going on. Although a four-hour window has been set aside each day for routine maintenance to be carried out.
The central section of the barrier, approximately 2.28km long, is being built using 43.9m long, 1.67m diameter reinforced concrete spun-cast piles with a 1.67m diameter which are being vertically driven to a depth of 39.62m at an average rate of 10 blows per 300mm into the marsh soil. They are spaced 15cm apart and each weigh 92t.
The space between the concrete piles is being closed using 2,600 square concrete piles 18.28m long and 480mm square to seal the seam. A precast concrete cap, weighing around 96t, is placed on the pile and post-tensioned in place. Sections of the cap between the precast sections will be filled with caste-in-place concrete. The final elevation with pile, concrete cap and parapet wall will be approximately 7.92m high.
In fact a milestone was reached on October 21st when the main contractor Shaw announced that the final 1,271st pile of this first major phase of the project had been driven, just 10 months since the ground breaking ceremony.
Although pile driving has been fairly straight forward, the biggest problems facing the contractors are wind and rain made worse by frequent thunderstorms. Safety procedures are given top priority on the project. This is particularly important especially when wind speeds exceed 40km/h and with so many cranes on the site operations are suspended.
ENDS