a geosynthetic clay liner is provided for installation in landfill sites equipped with lower drainage systems . the self - sealing bentonite mat precludes substantial migration of bentonite downward during activation thereby avoiding clogging of the drainage systems with activated bentonite . overlap extensions disposed on outer edges of the liners effectively contain the activated bentonite . the bentonite mat , or geosynthetic clay liner , does not require a first protective layer of geotextile material disposed below the bentonite clay liners to protect the drainage system .