Pipe Cutoff Collars

[GeoJeff]

What experience does everyone have with pipe cutoff collars? Have a pipeline project we are designing. It has several stretches of pipe to be installed on hills. Is there any criteria published on minimum slope angles for implementing cutoff collars? i.e. Do you use cutoff collars on the pipe (to reduce seepage) on slopes steeper than 3:1? Flatter? Steeper? Any published info I can reference?

Thanks

 

[GeoPaveTraffic]

My experience with cutoff collars is with pipes crossing levees. The US Army Corps of Engineers no longer installs cutoff collars due problems during construction. Unless you are particullary concerned with seepage, I would just specify no gravel bedding or backfill periodically along the pipe and use a moderate to fat clay for the bedding and backfill at those locations.

 

[cvg]

gravel backfill is not recommended at all, it may create a path for water and cause piping.

Los Angeles County Deptartment of Public Works has a standard for pipe anchors / backfill stabilizers. It is published in the American Public Works Association Standard Plans, Detail No. 221. Standard detail shows the anchors or stabilizers installed on slopes as flat as 3H:1V.