Gundle/SLT Environmental, Inc. (GSE) is a global manufacturer and marketer of geosynthetic lining solutions, products and services used in the containment and management of solids, liquids, and gases for organizations engaged in waste management, mining, water, wastewater, and aquaculture.

GSE has a long history of manufacturing quality geosynthetic lining systems, providing reliable installation services and developing innovative products. The company's principal products are polyethylene-based geomembranes, geonets, geocomposites, geosynthetic clay liners, concrete protection liners and vertical barriers. GSE manufactures and installs its products primarily to line or cap hazardous and non-hazardous waste landfills; contain materials generated in certain mining processes; and contain water, liquid waste and industrial products in ponds, tanks, reservoirs, sewers, and canals.

Headquartered in Houston, GSE maintains sales and installation offices throughout the world. With manufacturing facilities in the United States, Canada, Chile, the United Kingdom, Germany, Thailand and Egypt, GSE has an annual liner manufacturing capacity of approximately 300 million pounds. GSE is a subsidiary of GEO Holdings Corp. owned by Code Hennessy & Simmons IV L.P.