Constructors have started working on building a stretch of President Trump’s border wall this week, near Lukeville, Arizona.

The construction of this stretch of the border wall, known as Tucson Project 2, was started with plans to get rid of 2 miles of existing fence. The fencing is to be replaced with 30 foot tall bollards (a steel post 6 inches wide), spaced 4 inches apart, with the remainder filled with concrete. A “linear ground detection system” is also to be installed, with lighting on 40 foot high towers.

The project is estimated to take 45 days, after which they will start on Tucson Project 1, a 38.6 mile stretch along Cabeza Prieta National Wildlife Refuge and Organ Pipe Catcus Monument. This project will feature the same wall designs as Project 2. Tucson Project 3, a 19.7 mile stretch over 3 locations, will not begin until after early October, as “the final barrier designs are not yet complete,” says Paul Enriquez, the director of the Border Wall Program Management Office with US Customs and Border Protection.

The timeline was released in the government’s response to a lawsuit brought about by the Center for Biological Diversity in opposition to the building of the wall. Laiken Jordahl, a spokesperson for the CBD, told the Tucson Sentinel that the construction was “extremely concerning”:

[The construction the wall will] result in significant, irreversible impacts to these lands [which serve as] refuges to some of the last remaining populations of endangered species whose continued existence and recovery rely on the freedom of cross-border migration.

Government sources have the completion date for the 3 projects as January 31st 2020; it is unclear whether this stretch was included in President Trump’s estimation that 400 miles of border wall would be built by the end of 2020.

National File Editor-in-Chief Tom Pappert reported that President Trump told Fox & Friends in June that the wall is “going up rapidly”:

The wall is very important. It’s hard to breach it, it’s high, it’s strong, it’s powerful, and it’s going up at a much lower cost than the wall that was planned prior to me getting there… We’re going to have over 400 miles of wall built, and that’s going to be in the most important areas, and we’re going to have all of it built before you know. This is despite tremendous obstacles that have been put in front of us by the Democrats, you have no idea. We just won the lawsuit on the wall… brought by Nancy Pelosi.