New York City, New York
Urban fill overlying a mixture of medium dense sands and silts becoming till of varying thickness over bedrock at about 30 feet depth
6,000 square feet of jet grouting, 57 micropiles and 87 tiebacks
Nicholson created a support of excavation down to bedrock with jet grout walls internally reinforced with micropiles and supported with three levels of tiebacks beneath the 11th Avenue six lane viaduct in New York City. The overall work area was limited because of the main Hudson Yards commercial development site access road, allowing access to only half of the area at a time. All of the work was completed in only 15 feet of headroom, operating 24 hours a day and adjacent to live railway yard tracks.