1 March 1997
crushing head may be aided by the use of a hydraulic pulling unit or other apparatus. The
replacement pipe is pulled into place directly behind the pipe crushing tools. With this method
pipe from 150 to 300 mm (6 to 12 inches) can be replaced with the same size pipe or with larger
pipe, up to 300 mm (12 inches). A modification of the crushing head called a "ripper" may be
used to facilitate installation.
11-9. OTHER METHODS. Due to the large demand for cost reduction, new processes for
trenchless rehabilitation are constazntly being developed. Many of these have patents and could
require sole source justification if other processes are not allowed. Generally such processes
should be allowed only as one of several options or with performance specifications that do not
prevent other methods from being considered.