Bushwick Shaft 20B (1992)
New York, New York
Schiavone Construction Company
Construction of a 46-foot diameter, 300-foot deep shaft was attempted using the slurry diaphragm wall method for earth support and groundwater control. During the initial excavation, three breeches in the joints between slurry wall panels created significant inflows of groundwater and loose sandy materials. These inflows manifested themselves in the form of settlements of several inches of the surrounding streets and minor deformation of several structures in the immediate vicinity.
Layne Christensen installed and maintained a ground freezing system around the perimeter of the entire shaft, extending approximately 300 feet into bedrock. Freeze pipe installation was accomplished utilizing Layne’s Dual Wall Reverse Rotary System, which can decrease installation times of refrigeration pipes by one half. This drilling method was extremely successful in soils that had been grossly disturbed by the slurry wall failure and resulting blow-ins.
Due to the complexity of the surrounding area which included several buried utilities and an adjacent subway tunnel, any problems with the frozen earth wall could be devastating. An extremely rigid quality assurance program was implemented which included measuring of pipe deviations at 2-foot intervals, precise flow rate and volume measurements and electronic ground temperature monitoring and over 100 thermocouples to measure and ensure balance of the coolant flow.
New York, New York
Schiavone Construction Company
Construction of a 46-foot diameter, 300-foot deep shaft was attempted using the slurry diaphragm wall method for earth support and groundwater control. During the initial excavation, three breeches in the joints between slurry wall panels created significant inflows of groundwater and loose sandy materials. These inflows manifested themselves in the form of settlements of several inches of the surrounding streets and minor deformation of several structures in the immediate vicinity.
Layne Christensen installed and maintained a ground freezing system around the perimeter of the entire shaft, extending approximately 300 feet into bedrock. Freeze pipe installation was accomplished utilizing Layne’s Dual Wall Reverse Rotary System, which can decrease installation times of refrigeration pipes by one half. This drilling method was extremely successful in soils that had been grossly disturbed by the slurry wall failure and resulting blow-ins.
Due to the complexity of the surrounding area which included several buried utilities and an adjacent subway tunnel, any problems with the frozen earth wall could be devastating. An extremely rigid quality assurance program was implemented which included measuring of pipe deviations at 2-foot intervals, precise flow rate and volume measurements and electronic ground temperature monitoring and over 100 thermocouples to measure and ensure balance of the coolant flow.
