Conduit seals at manholes

[buddy91082]

Anyone know of a paper or article that summarizes various conduit seals for waterproofing and water pressure? Looking at hydrophilic foams but don't have any experience with them.

Thanks.
b

 

[rcw retired EE]

Conduits into manholes leak water. My expereince is that it is more effective, but costly, to put in sump pumps than to waterstop the conduits. Any method to stop he water intrusion seems to fail.

 

[EEJaime]

buddy91082,
91082...,What is that South Beverly Hills? Just kidding. I have had very good results with CSD Sealing Systems North America. They have several systems, some fire rated, some gas and moisture tight. Look through their catalog and contact their technical services guys. They are very responsive and helpful. Their original mandate was shipboard systems, now their landside systems are getting popular as well.
Regards,
EEJaime

 

[dvclark5]

I agree with rcwilson, manholes are below grade and will accumulate water. Whether it is through the cover, conduit, or base. It is usually an option from the mfr. to have a recess in the bottom for a pump. This is normally used to pump out the water if you need to go down and work in there. You would not normally install a permanent pump unless it were a special case, such as the manhole being inside a building.

 

[davidbeach]

If the NEC is the governing code, assume that anything installed below grade is submersed. If the NEC isn't the governing code, you won't go wrong if you assume submersed. I wouldn't count on much else for protection of underground installations.

 

[7anoter4]

I agree with rcwilson. It is cheaper using a sump pump. But cable entries into the basement it is better to seal it using a RTV Silicon Rubber and the best for fire stop also. See [for instance]:
DOW CORNING® Firestop

http://www.geocel.co.uk/dynpdfs/626.pdf

I used once RTV supplied by General Electric.

 

[rcw retired EE]

Roxtec also makes a retrofit product that looks like it will work to seal conduit entries after cables are installed. It is custom manhfactured. Raychem (Tyco?) had a C02-filled, adhesive-coated, mylar balloon system that wrapped around the cables and expanded to seal when inflated with CO2 that seemed to work on one project.

Our problems were usually leaking manholes and leaking ducts with the field personnel looking for easy cheap solutions. Duct seal and other putty type compounds could not withstand the hydraulic pressure. We could hear them popping out as the rains came.

 

[buddy91082]

Thanks to all for the feedback.

 

[dicksewerrat]

There are a few good grouts out there that will withstand some hyd. head. go to Trenchlessonline and look at the products there. I know Avanti has a good one and a few others.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com