Engineers Begin Preparatory Work for Border Wall Construction
WASHINGTON — The United States Army Corps of Engineers has begun preliminary preparations for the construction of segments of a wall in several places along the border with Mexico, the Department of Homeland Security said on Tuesday.
Engineers are drilling and taking soil samples to determine what type of barriers would be most effective in the different types of geography along the border, said David Lapan, a spokesman for the Department of Homeland Security.
https:// www.nytimes.com/2017/07/18/us/politics/border-wall-construction.html
Not saying any theory is correct, however posting this article from July 17 as it connects and backs up the Engineering Corps theory.