General Trenchless Technology FAQs

Q: Should rehabilitation projects be contracted as design/build? This would reduce the CCTV work.

A: Design/Build is used by some municipalities for larger size projects. However, it may not save on CCTV work. The lines need to be TV'd during the design to assess the condition. The post preparation CCTV gives the Owner a visual verification of that the system is ready to be rehabilitated to specified requirements. The pre lining CCTV confirms that the line isclear of all foreign materials. And the post CCTV inspection confirms that the liner has been installed correctly.


Q: Is flow by‐pass always required?

A: It depends on the technology. For instance, CIPP installations always require some by‐pass pumping or flow diversion depending on the size. Other technologies such as slip‐lining and spray type applications in some cases can be performed without total flow diversion.


Q: What is NASSCO's position on pipe‐bursting Asbestos Cement pipe?

A: Asbestos cement pipe can be lined using a number of trenchless technologies. The process typically does not disturb the asbestos material. When an asbestos pipe is burst, the fragments that remain in the ground are considered friable and therefore create a hazardous material site. Currently pipe bursting is not used extensively to replace asbestos cement pipe. NASSCO's position is to follow the regulatory requirements. Through industry advocacy efforts NASSCO has, in the past, worked with members to address regulatory issues and effect appropriate changes.