The bottom of this lock head is at -22 meters NAP. The outer head is now a dry construction pit about 25 meters deep. We did not let this milestone pass by lightly. At the vantage point today (Thursday, September 24, 2020) the Nieuwe Sluis Terneuzen steering committee and the project directors were present to view and celebrate the deepest point of the outer head.
Safe and closed construction pit
So the creation of a dry construction pit of the outer head has succeeded. That was quite an operation. We first excavated to -11 meters NAP dry. The pit was then filled with water to wet excavate to -22 meters NAP. Then we made a bottom of underwater concrete. After that, the tub was put dry step by step. During which the walls and floor were closely monitored. Below the bottom of the construction pit we are now extracting groundwater. We spray this back into the surrounding area. This return drainage is necessary to reduce the pressure on the construction pit and by spraying it back, the groundwater in the area remains the same. We are monitoring this closely. Now that a safe and closed construction pit has been created, we can get to work on the complex concrete work required for the door casings, bridge basement and leveling system. The inner head is expected to be a dry construction pit by early 2021.