Polyurea Repair of a MSW Landfill Liner System

Penetrations of synthetic liner waste containment systems during or after filling can be a disaster for a landfill owner or operator, particularly if the liner penetration is caused during drilling of gas wells. Waste thickness over the liner at the time of gas well drilling could be 50 feet or more, making repair a difficult and costly operation. Methods for repair of synthetic liner systems at depth have been limited. In most cases, the waste has been excavated to expose the liner for a manual repair, a very costly and time consuming method for waste depths in excess of 50 feet. In some cases, the repair has consisted of a bentonite plug to seal the penetration. While less costly, the assurance of an effective, permanent seal is greatly reduced. Further, this method does not address regulatory assertion that compliance with Subtitle D requires a synthetic liner. Through the aid of a case history, an alternate means of repairing liners under significant waste thickness will be demonstrated. The use of polyurea, a fluid two-part synthetic material that cures under liquid, will be discussed. Applied remotely under tightly controlled conditions, polyurea has been successfully used to repair a synthetic liner system under 60 feet of waste.