Look at the workers in the background, the construction equipment and the black iron fence. It appears this structure may be 8-10ft tall. To the left of the photo is a wood panel in between the concrete. The concrete appears to be 3-5" thick as one concrete slab is being lifted in the jaws of the construction vehicle.

We have no WH public events until Easter; Easter Bunny, Egg roll, etc. Here is an interesting article from 2019 about the WH Black fencing. https://www.nps.gov/whho/learn/management/white-house-fence-construction.htm