Mr. Rafter,

Fascinating review of state of the art in trenchless technology, as well as a reminder that traditional techniques will still have a role in many applications.

A couple of minor observations:

"...plastic pipe is resistant to rust... Did you mean immune or impervious? Perhaps I'm missing something.

Searched in vain for 411 on "collapsed cylinder pipelines". Google only displayed this article and a visit to Northwest Pipe Company's site and Wiki was not productive. Did I not look hard enough?

Thanks for the informative article.

Steve, consumer