Method of and system for installing foundation elements in an underwater ground formation

Abstract

A method of and system for installing a foundation element, in particular a (mono)pile, in a hard underwater ground formation uses a driver. The method comprises the steps of placing a foundation element on the underwater ground formation, placing a screen for reducing noise input from the driver, driving the foundation element into the ground formation by means of the driver while the screen is positioned about the foundation element, and attenuating noise transfer from the underwater ground formation to the outer wall of the screen during at least part of the driving.

1 . A method of installing a foundation element in a hard underwater ground formation by means of a driver, comprising:
 placing a foundation element on the underwater ground formation,   placing a screen for reducing noise input from the driver,   driving the foundation element into the ground formation by means of the driver while the screen is positioned about the foundation element, and   attenuating noise transfer from the ground formation to an outer wall of the screen during at least part of the driving.   
     
     
         2 . The method according to  claim 1 , comprising at least substantially dynamically uncoupling at least the outer wall of the screen from the ground formation. 
     
     
         3 . The method according to  claim 2 , wherein at least a lower end of the outer wall of the screen is maintained at a distance from the ground formation. 
     
     
         4 . The method according to  claim 3 , wherein the screen is suspended. 
     
     
         5 . The method according to  claim 3 , wherein the screen is at least 50% buoyant. 
     
     
         6 . The method according to  claim 5 , wherein the screen floats and is held in position by one or more weights on the ground formation. 
     
     
         7 . The method according to  claim 1 , wherein a noise attenuating material is being positioned between the ground formation and the lower end of the outer wall of the screen. 
     
     
         8 . The method according to  claim 7 , wherein a modulus of the material is lower than a modulus of the material of the outer wall of the screen and lower than a modulus of the underwater ground formation. 
     
     
         9 . A system for installing foundation elements in a hard underwater ground formation, comprising a driver, a surface vessel configured to secure the driver, and a screen carried by the surface vessel to be placed about the foundation element to reduce noise input from the driver, and an assembly configured to attennuate noise transfer from the ground formation to an outer wall of the screen during at least part of the driving. 
     
     
         10 . The system according to  claim 9 , wherein the surface vessel comprises, in addition to a crane configured to secure the driver during driving, a crane configured to maintain the screen at a distance from the ground formation during at least part of the driving. 
     
     
         11 . The system according to  claim 9 , wherein the screen is at least 50% buoyant. 
     
     
         12 . The system according to  claim 11 , wherein the screen comprises at least an inner wall and an outer wall. 
     
     
         13 . The system according to  claim 12 , wherein the screen has a buoyancy in excess of 100% and the system further comprises a weight configured to maintain the floating screen upright. 
     
     
         14 . The system according to  claim 9 , wherein the screen is provided with a support of a noise attenuating material to be positioned between the lower rim of the screen and the ground formation. 
     
     
         15 . The system according to  claim 14 , wherein a modulus of the support is lower than a modulus of the material of the outer wall of the screen and lower than a modulus of the underwater ground formation. 
     
     
         16 . A noise mitigation system comprising a screen configured to be placed about a foundation element to reduce noise when driven into a ground formation, and an assembly configured to attenuate noise transfer from the ground formation to an outer wall of the screen. 
     
     
         17 . The system according to  claim 16 , wherein the screen is at least 50% buoyant. 
     
     
         18 . The system according to  claim 16 , wherein the screen comprises at least an inner wall and an outer wall. 
     
     
         19 . The system according to  claim 16 , wherein the screen has a buoyancy in excess of 100% and the system further comprises a weight configured to maintain the floating screen upright. 
     
     
         20 . The system according to  claim 16 , wherein the screen is provided with a support of a noise attenuating material to be positioned between a lower rim of the screen and the ground formation. 
     
     
         21 . The system according to  claim 16 , wherein a modulus of the support is lower than a modulus of the material of the outer wall of the screen.