The plastic concrete secant pile cut-off wall was successfully completed by BAUER Georgia Foundation Specialists LLC in February 2017.
133 nos. secant piles with a nominal diameter of 1500 mm were executed with 500 mm intersecting with adjacent piles. Average depth amounted to 26,5 m; the longest pile depth was 34,3 m. A total of 3500 m piling was installed using a BAUER BG 28 with a BV 1500 oscillator.
As specified, piles at the abutments had to be installed at least 1 m into the competent rock. Other piles were designed to be embedded into the coarse alluvium, a stratum below a 2 m thick clay layer. All pile depths and rock/alluvium levels were checked and confirmed by inspectors of Mott MacDonald. A rope inclinometer device was used to assure overcut at each pile for wall continuity within the designed tolerances.
The toughest part was working during heavy winter conditions.