Needle-punched nonwoven geotextiles are made from polypropylene fibres that are tangled together in a needle-punching process. The fibres may be made in continuous or short lengths and achieve their strength by interlocking. Needle-punched nonwoven geotextiles have excellent water flow rates and are used for filtration of soil fines. Needle-punched nonwoven geotextiles have been used in drainage applications, including trench drains (also known as french drains). It can also be used for wrapping a perforated pipe, erosion protection, separation of a road sub-base and base course, and combined with three-dimensional structures to create prefabricated drains. They are also commonly used with geomembranes to provide a protective cushion. Needle-punched nonwoven primary functions: filtration; separation; protection; drainage.