Device and method for producing a containment barrier underneath and around in-situ buried waste

An apparatus for building a horizontal underground barrier by cutting through soil and depositing a slurry, preferably on which cures into a hardened material. The apparatus includes a digging means for cutting and removing soil to create a void under the surface of the ground and injection means for inserting barrier-forming material into the void. In one embodiment, the digging means is a continuous cutting chain. Mounted on the continuous cutting chain are cutter teeth for cutting through soil and discharge paddles for removing the loosened soil. This invention includes a barrier placement machine, a method for building an underground horizontal containment barrier using the barrier placement machine, and the underground containment system. Preferably the underground containment barrier goes underneath and around the site to be contained in a bathtub-type containment.