- Since 1901, Subsurface has been providing a full range of deep foundation techniques including complete design and build services, soil investigation, structural stabilization, installation of caissons, drilled shafts, slurry walls, soil mixing, augercast piles, soil nail retaining walls, regrouted soil anchors, pin pile, pre-cast concrete pile, micro-pile, and much more.www.subsurfaceconstructors.com