Construction is progressing steadily and on schedule on both the liquefaction facility site and the site for pretreatment. On Quintana Island, work is underway on building the construction materials and equipment dock and ramp that will be used to unload liquefaction train components that arrive by barge on the Intracoastal Waterway. Nearby, the Velasco drainage ditch culvert under the future ramp is being rebuilt.
On the western side of the liquefaction facility site, work is complete on an aggregate materials dock. Aggregate now arrives here by barge for use by the two newly finished concrete batch plants. The material is transferred to the batch plants from the dock by a large repositionable conveyor. Cement and water are then added to truckloads of aggregate, and specially trained crews mix in just the right amount of an additive to perfect the consistency needed for use in the facility's foundation pilings. Placement of pilings on both sites will be underway for several more months. When piling work is complete, there will be approximately 15,000 piles at the liquefaction site and 7,000 piles at the pretreatment site.
When piling work is complete, there will be approximately 15,000 piles at the liquefaction site and 7,000 piles at the pretreatment site.
The New DeWaal Process for Pilings
PRESS "F" FOR FULLSCREEN
DeWaal Piling System
As of October 2015, most of the piling work has taken place at the pretreatment site. The drilling method chosen for both sites is called the DeWaal pile system. In this process, a rig positions an auger on the end of a long drill shaft at the insertion location. The drill shaft has a feature that forces soil material into the hole's sidewall so that little material finds its way to the surface and needs to be hauled away. When the auger reaches the designated depth, the center drill shaft acts like a pipe and is used to pump concrete into the hole. As the auger is withdrawn, the concrete is deposited behind it. In the final step, the drilling rig is moved out of the way, and a special pre-assembled rebar cage is placed into the fresh concrete. A very important feature of this piling method is that unlike conventional driven piles that are hammered into the ground, this method is noise-free
Each pile will eventually be connected to the facility's foundation by creating a concrete pile cap, two to three feet in thickness. The rest of the foundation is built off of the pile cap. At the pretreatment site, the deepest piles will be approximately 95 feet in depth, while at the liquefaction facility, piles will be placed up to 120 feet deep.