I would say no guarantees just good design, slope conduits away from buildings to manhole structures with proper base and drainage, link seals on conduit ?cores?, and on the interior of the conduits I have specified a product by Tyco called Rayflate ( http://www.tycoelectronics.com/catalog/cinf/en/c/19998/2110 ). I have even had one owner mock-up and test it to a certain extent and was satisfied, since I have specified, and had it installed on many projects, with no complaints (that I know of) and when it had to be removed it was an easy and clean removal and re-installation in the same duct, according to the installing contractor. Just a thought.
I am going to try the Polywater system, its about $85 for a kit to get you started. There is a video at the polywater web site.
Duct Seal is good for moisture and to prevent condensation.
Thank you for the replies. I have used the Raychem products in the past and also have used spray foam from the cans. I will try the polywater foam on my next project.