Bore 2

[Surcharged]

I need to run a 4" pvc line under an existing roadway. Is it necessary to jack and bore or is there some type of freebore that we could use? Thanks.

 

[semo]

Depends on who owns the roadway. If it is a DOT, more than likely you will have to jack and bore a steel casing to place the carrier pipe in.

Check with the authority.

If no casing is required, you can directional bore the line. This is probably your best bet; but, I've also seen contractors ream out a hole with a small service line type of boring machine and then push PVC pipe through by hand. I know this works on short punches (<30 ft) with smaller pipes (<8").

 

[coloeng]

It depends on what the 4" pvc is for. Is it a conduit for electrical/phone? a sewer service? a pressure water line?

We use almost exclusively directional drilling for our bores under roadways, which includes state highways where steel casing is required. Yes, you can use dd for steel, although it takes a lot longer tail ditch. We have used HDPE, Certa-lok PVC, fusible PVC, and schedule 40 glue joint PVC. Diameters that have been done are 14" to 24" steel and 2" to 12" HDPE and PVC.

 

[JedClampett]

I'm no expert, but when I've used jack and bore, I've been surprised at the size of the carrier pipe (30"-36" min) and the thickness (3/4"). It seems excessive for one 4 inch line.
If you can use directional drilling as mentioned above, there will be a lot less material.

 

[cvg]

minimum size of 30 - 36" for casing is often selected so that if rocks, boulders or other obstructions are encountered during the jacking process, somebody can crawl down the casing pipe with a pick, shovel or some other tool to remove the blockage...

 

[redbridge]

I would recommend bore and case or directional bore. Freeboring will cause road to settle.