Abandoned pipe by law, in most cases, is required to be removed or properly decommissioned by being sufficiently grout filled. This will prevent future collapse and the creation of voids. This could be the cause of settlement to the topsoil or the substrate of the roadbed.
Most commonly, cement grout is used. Most pipes are open-ended or have a vent in order to void the air pressure as the grout is injected. The second option is to grout the run with Chemical Grout. Chemical Grout is dispensed using a long tube and injection begins after the tube is inserted into the full length of the pipe run. Once the product begins to flow, it flows toward the entrance port (now the grout’s exit) as a liquid and expands up to 20 times its volume as a closed-cell, structural foam. The pressure is voided through the entry point as the chemical reaction takes place and the expansion occurs. Once the Chemical Grout expands and sets, the tubing is cut below grade and buried.