In case you missed it, that was a joke. There is infact an Army Corps of Engineers that is responsible for exactly what the comment suggested (amongst a lot of other things).
The Army Corps of Engineers has its prominent civil engineering role because early America did not have a lot of federal resources and was born from war. So when the Federal government decided it wanted to take on large scale civil engineering works, the only ready to go resource at hand were the military engineers. And then afterwards, it's pretty much been inertia.
The Army Corps of Engineers civil works division is basically almost completely staffed by civilians. So there's a convoluted top level organization, but on the ground, it's not like they have soldiers and military engineers building levees.
Congressional Research Service report: https://www.congress.gov/crs-product/R48322
It includes a section about discussions on transferring civil works responsibility out of DoD.
