|Owner||US Army Corps of Engineers - Mobile District|
|Contractor||TREVI ICOS - RODIO J.V.|
|Duration of work||2001|
With one pile in place crews leave a space of 16 in. (406 mm) before drilling the next shaft. After filling several shafts spaced in this way and allowing each to cure for approximately seven days, crews go back and drill a series of secondary shafts, also 50 in. (1,250 nun) in diameter, centred on the 16 in. (406 mm) gaps between the preliminary piles. The secondary shaft overlaps the two preliminary piles on either side of the 16 in. (406 mm) gap by about 10 in. (254 mm), thereby cutting out about 30 percent of the concrete from each. When the secondary shaft is drilled to the appropriate depth, it too is filled with concrete, closing the gap between the two preliminary piles and creating a section of the wall. The secant line between the two intersecting piles is required to be at least 24 in.(610 mm).
The secant wall was designed and constructed for the Corps by a joint venture between the Treviicos Corporation, based in Boston, and the Rodio Group, based in Milan, Italy. Simpson says the project is on schedule and should be completed in September 2004.