Determining Trenchless Renewal Options Using CCTV Information

There are now a substantial range of trenchless renewal options available in New Zealand for the rehabilitation or replacement of deteriorated gravity pipes (Storm or Sewer). All of these options have their own set of benefits and limitations as to where they can be used. A significant challenge for designers and asset owners is determining what the available trenchless renewal options are, and therefore what the optimum option is. 

The majority of sewer pre-renewal investigations involve CCTV inspections, and therefore is the primary basis for determining or designing the method of renewal. The information from the CCTV inspections provides an understanding as to how the trenchless methodologies can be applied and their limitations in that application. The key to a successful trenchless renewal project is the accurate interpretation of this CCTV information. 

This paper sets out the application parameters of the various renewal options and the limitations of information available from CCTV Inspections and also identifies where further investigation may be required. The paper’s conclusion will provide an independent guideline for the selection of trenchless renewal options based on the information that can be obtained from a CCTV inspection.