This is a general 'basementsections' replacer.
This mod actually saves your VRAM and reduces the load by reducing the amount of textures used for 'basement setions' for the floors, walls and ceilings from 46 down to 4. At almost no visual cost, too; the floor tiles can look a bit whacky on 2 (just two) sections of the floor; the curved corridor and some stairs.
Vanilla floor, ceiling and wall sections have separate textures for each corner and curve, but you don't *really* need those if you have actual Ambient Occlusion in your game. The screenshots below are made with vanilla graphics that doesn't have this feature, however, and it still looks relatively decent.