Culvert Abandonment

[mickcwa]

I am in the process of designing a commercial develoment that involves the re-alignment of a public street. The roadway has 2 culverts under it. The drainage through these 2 culverts is being re-routed and the owner wants to abandon the culverts. The culverts now are approximately 20' in the ground. The cost to dig the culverts out and replace the soils seems much higher than just filling the culverts with flowable fill or grout.

The question I have is what is the best way to get the flowable fill into the culverts to insure there are no voids. Both culverts are approximately 300' long. Both are 6'x6' boxes.

The contractor and I had also talked about pressurized grout but how do you keep from blowing out both ends and again how do you insure no voids.

Thanks,
Mick

 

[jdonville]

mickcwa,

Could you run the grout line along the top (ceiling) of the culvert with outlet ports at regular intervals? It would be sacrificial, of course, but would help ensure that the grout filled all the way to the top.

More details about the end conditions would be helpful.

Jeff

 

[mickcwa]

That would have been my thoughts was to push the grout line to the downstream end and work back upstreams and pump as you pull it out. I assume by outlet ports that you mean holes in the top of the culvert that would allow the grout to come out so you could tell you were filling the voids. The only disadvantage I see is that you would have to uncover the culvert to do so (more money) and replace the fill (more money). Although it still may be cheaper to uncover the culvert, fill with grout with the ports, and then backfill than it would be to have to remove the culvert completely.

The culvert is about half full of sediment. Both ends are open now but will be filled along with rough grading. We had talked about forming a concrete wall at both ends to contain whatever we placed in the culvert. But we could just fill on the downstream end and avoid the concrete wall. That should give us enough of a barrier to hold back the grout.

sounds great and easy "Just leave it in place and fill it." But the actual construction techniques to do this is complicated.

Thanks for your response and please keep them coming.

 

[semo]

Why not use the same process as sliplining. Bulkhead both ends with a plug of non-shrink grout. In the lower bulkhead, place a pipe with a threaded end so that it can be capped. On the upstream end, place two such pipes.

After the bulkhead hardens, pump the grout fill through one or both of the upstream pipes until grout comes out of the downstream pipe. Place the cap on the downstream pipe and continue grouting through one of the upstream pipes letting the other vent. Once grout comes out of the upstream vent pipe, the culvert should be full.

The grout should be flowable so as to be partially self leveling.

 

[civilperson]

Use flowable fill until the culvert top is submerged. Fill from the high end.

 

[jdonville]

mick,

I meant to put holes in the grout line as outlet ports. The grout line would be attached to the ceiling. This would theoretically help to prevent voids between the ends if the ceiling is level.

Based on the 6x6 dimension, you may need to design and construct temporary bulkheads to retain the flowable fill. I don't think that a packer (inflatable seal) could be obtained large enough for this application.

Good luck.

Jeff