Plastic pipe is intended for surface and subsurface drainage applications where soil provides support to its flexible walls. Its major use is to collect or convey drainage water by open gravity flow, as culverts, storm drains, et cetera.
Currently, NTPEP is auditing Polypropylene Thermoplastic Pipe manufacturers, which includes split sample testing. Audit and test protocols are described in the "Project Work Plan." All audit requirements conform with the latest version of AASHTO Standard Specification M 330.
The NTPEP Technical Committee responsible for authoring the Project Work Plan convenes yearly at the NTPEP National (Annual) Meeting. During this working meeting, the Project Work Plan is discussed, changes made, and shortly thereafter balloted for adoption. Improvements are immediately implemented in the next available audit tour. When compared to other standards development exercises, the NTPEP process is agile, effective and efficient.