Techniques to Abandon Culverts under Roadway 2

[garnetspur]

hello everyone. i'm new to this forum.

wanted to see if anyone had a tip on my question:

i have 3 culverts that are being replaced under a highway. diameters are 18", 24" and 36". The location is a mountainous, river canyon - roadway is approximately 100' above the river - 2:1 slope down to the river.

pipes are at 45-degree angles on average. outlets cannot be located easily. and maintenance is an issue due to the terrain.

so, we're replacing them with new pipes.

but, we need to abandon them. excavation is not an option (excavation would be huge/deep).

foam?
lean concrete?
other?

due to the depth of the pipes under the roadway..i'm not too concerend about a void leading to settlement or anything. that is, if a void was created when/if the metal pipe corroded away at some point in the distant future.

any advice/input would be great.

thanks

 

[cvg]

if you are not concerned with voids and settlement, just plug the ends with brick and mortar. this is typical procedure in urban areas and prevents water from flowing through and also keeps the varmints out.

 

[msquared48]

Since the outlets cannot be located easily, I take it that you only want to work with the upstream end. I would the upstream end with gravel for a four to five foot length to within 2 feet of the entrance and fill the entrance with a stiff concrete mix. The gravel will serve as a temporary dam for the concrete to be placed against.

Mike McCann
MMC Engineering

 

[bimr]

Agree with cvg on this one.

However, if you own stock in a cement company or have extra funds available, go for the lean concrete.

 

[Drumchaser]

Pressure grout them.

 

[gbam]

Maybe just grout under roadway

 

[garnetspur]

thanks for the responses everyone. we have the money to "fill" them with something.

given the steepness and confined/difficult/steep working terrain - that's an issue.

also, the steepness of the pipes - many, many years ago when this was a forest service road...they just threw the pipes in then backfilled until they had a benched in road.

i like the idea of just pressure grouting them under the roadway, and then capping it off.

trouble is blocking the downslope end.

suppose the contractor could get on teh downslope side. find the end of the pipe...cut the bottom away...and block it with a temporary earthen damn. .

has anyone ever had experience with "foam" products such as uretek?

http://www.uretekicr.com/solutions_infrastructure_repair.php

things i want to see from the abandonment:

1)void is filled IF metal pipe is to corrode away. i.e. material is inert. under the roadway only. filling entire pipe not necessary.

2)does this material need to be hydroinsensitive? or, would putting a good cap at the inlet prevent an water intrusion and be sufficient. probably the later. put on a good, water tight cap.

i am in the process of writing a spec for this. so, whether it's done with concrete, pressure grout, foam, other. i just need to lay out the specs we want with the abandonment.

thanks again for everyone's help. the construction of this should be interesting. we'll see what the contractor proposes to do.

 

[PELS]

Insert an inflatable pipe plug from the upstream end of the culverts until it reaches the outlet and inflate to seal the pipe. Then fill the pipe from the inlet with a low grade (inexpensive) concrete. You can leave the plug in place even after the concrete hardens.

http://www.matjack.com/plugs.htm

 

[PELS]

Here's a couple of other inflatable plug suppliers:

http://www.pipeplug.com/?gclid=CILNwt6Tm5gCFRwpawodQ0eY3A

http://www.musthane.com/english/products/stoppers-muststop.htm?gclid=CKbl7umTm5gCFQ9Jagod_jfNnw

 

[civilperson]

Flowable fill with a plug in the outlet. (100 psi compressive strength is suitable)

 

[cvg]

if you plan to grout this, I would leave the means and methods up to the contractor. all you really need to specify is that you want portland cement, sanded grout and the minimum strength requirement. if you plan to grout only the portion under the roadway, then define the station limits. however, I would recommend doing the entire length. Either way, define a method for the inspector and contractor to determine that the pipe has been fully grouted such as measuring the volume of grout placed or look for indication of grout coming out the other end etc. Specifiy maximum pressure so you don't start injecting grout into the embankment.

have them set a rebar in the end of the pipe so you can locate the pipe in the future if you ever need to.

 

[bimr]

This is a actually a standard DOT pay item.

FILLING EXISTING CULVERTS
This work shall consist of filling the existing culverts as shown on the plans, and as directed by the Engineer.
The existing culverts shall be sealed at the ends with concrete or masonry and filled with a grout mixture in a manner meeting the approval of the Engineer. The grout mixture shall be pumped into the culvert from the ends with the seals sequenced to provide the flow and release of air as the structure is filled. Equipment and methods used to perform this work shall meet the approval of the Engineer. This work shall be paid for at the contract unit price per cubic yard for PLUG EXISTING CULVERTS which price shall include all labor, materials and equipment necessary to complete the work herein specified.

http://www.dot.ca.gov/hq/oppd/dib/dib83-5.htm

http://www.dot.state.ut.us/main/uconowner.gf?n=1128117589169310

 

[rconner]

Just one further comment. You mentioned these pipes are apparently at a 45 degree +- vertical slope. While you did not mention specifically the age of these pipes nor the specific reason for replacement, maybe particularly if this happens to be corrugated metal pipe I believe there is some history of such pipes being eroded through (and perhaps earlier than some would expect) as a consequence of the very thin actual wall membrane, high velocity, and maybe even some transport of abrasives (rocks, pebbles, etc.?)
Therefore, I guess someone keeping up somehow with amount ofgrout and where it goes might also be advisable, and maybe particularly if pipes are in real bad shape and there is any chance escaping grout might not necessarily come to the surface!

 

[garnetspur]

good points rconner.

these are corrugated metal pipes - 40-50 years in age - best guess.

we video inspected the pipes. there is rust observed in the bottoms. no evidence of being fully eroded YET..but other pipes along roadway has show this type of wear.

main reason to replace these steep pipes is the difficulty in maintaining them.

the outfalls are way down the slope - and the maintenance guys have not and won't maintain due to this difficulty.

we won't have a chance to deal with these pipes for a long, long time..so, the time to replace them is now.

thanks for all the input. really good ideas/points here.

still, trying to write this spec. really appreciate the spec posted by bimr. good starting point for me.

thanks!