High flow capacity corrugated coilable dual wall plastic pipe having improved longitudinal flexibility and a bend radius sufficient to permit coiling and plowing of such pipe into the ground using automated installation equipment. The coilable dual wall pipe has an outer corrugated wall formed of a thermoplastic material such as high density polyethylene, and an inner smooth wall formed of a different more flexible and resilient thermo-bondable material that has an enhanced strain capacity and lower modulus of elasticity. The inner wall material also has enhanced mechanical properties which generally improve processing and help prevent excessive drag and tearing of the liner material during the manufacturing process. Suitable material blends for the inner wall in corporating a thermoplastic elastomer additive in combination with a thermoplastic material have proven suitable in providing the required longitudinal flexibility and pipe bend radius to permit the desired pipe coiling and plow installation without failure.