RC sewer pipe 2

[civeng80]

Hi all !

Im doing a project at the moment where part of the works involve cleaning (i.e remove top and soft soil about 6 to 8 inches) and backfilling with crushed rock (about 12inches) to make a hardstand area so used for car parking and general small to medium parcel express trucks.

Part of the property is on an easement with a 2 ft Reinforced concrete sewer main (about 40 years old) of which the Water authority has rights over. It has a cover of about 3 feet. Apparently the main is in pretty bad condition according to the authority and their very nervous about letting me do anything at all over the pipe, apparently even increasing the cover.

Has anyone any experience in matters like this ? Any points both from a legal view and from a practical view would be greatly appreciated.

Thanks!

 

[cvg]

ask them to relocate, replace or protect their sewerline so you can develop your property? (I would vote for either replacement or encasement to protect it)

 

[civeng80]

Its a main sewer they wont relocate, I think they would laugh at me if I even mentioned it. Its within an easement of a private property so they have certain rights to that property (without going into the legality of easement law !)

Encasement well again I think they just dont want to go near it and I think their philosophy is, let sleeping dogs lay. Great for them but not so great for the Property owner who wants to use his land as efficiently as possible.

Actually the main is about 3 foot in diameter ( 1m) with the same cover mentioned above.

Any further ideas?

 

[civilperson]

Bridge it with a reinforced concrete slab.

 

[oldestguy]

This has been used where a high fill went over a concrete pipe that could not be taken out of service. The job was the interstate Hy 94 over a sewage treatment plant outfall at Eau Claire, WI..

A trench was excavated over the pipe (not sure how deep) but to have a place for a compressible fill. I'd expect the tench probably was almost to the pipe.

The fill was corn stalks in that trench.

The area then had a concrete slab built over the area and off to each side. You can see that slab also has to extend far enough sideways to avoid placing added stress on the pipe. Obviously the slab had to be designed to carry the fill, like a bridge. Fill was at least 10 feet, probably much higher over that slab.

This general concept was first proposed many years ago by an engineer professor at Iowa State U. by the name of Marston. I think, but if not, by his successor, Spangler, and it is called the"Imperfect Trench".

I know of another job like this, but not as big a fill, with a building sitting over a force main, again carrying sewage.

Sounds silly, but it works.

 

[cvg]

easements only grant certain rights, and preventing the property owner from utilizing his property is not one of them. The owner can certainly ask them to protect their line as a ruptured pipe caused by nearby traffic loading could damage his property as well as being very costly for them. Not to mention the potential environmental impact. I would insist that the pipe be encased or replaced. By encasement, I mean concrete blanket aka "bridging" as previously described in detail.

 

[civeng80]

Thanks civilperson, oldestguy, cvg all very useful comments. Bridging across the pipe is something I have thought of and will certainly using this as a last resort. Im particularly interested in cvg's comments where "easements only grant certain rights and preventing the property owner from utilizing his property is not one of them."

The way these people approach the problem is on a daily basis. Ive spoken to them before on this and the guy at the counter told me a few beuties which I didn't bother auguing. Said that if a truck or semi trailer were to cause damage to the pipe the owner would bear the cost. Sure I thought but what would the courts decide. I have a meeting with a person higher up in the new year and want to sit down and calmly find a solution to the problem. The owner is prepared to do anything reasonable consistant with the occupiers and the Water Authority, but if they have a sewer main thats badly corroded then it also becomes their problem and a solution is not to just stay away (and force the owners to do likewise!).

Any further tips on how to approach them would be appreciated on this !

Thanks!

 

[LCruiser]

Sewer gases contain sulfur and precipitate on the walls of a concrete pipe as sulfuric acid, which corrodes it. Their problem is probably due to this corrosion. Did they TV it? They may not want you to see that video. I have seen concrete pipe that was completely gone at the soffit where the gases precipitate, but still good down below the continuous water level..It may well be completely corroded on top. In that case any disturbance could cause a cave-in, and a cave in could plug the pipe. You would have a *real* problem on your hands then - you don't just "shut down" a 3' sewer main!

 

[LCruiser]

P.S. I'm not saying forget the idea, I'm just trying to give you some perspective. They may need to slip-line the pipe:

http://www.hobaspipe.com/

 

[cvg]

repairing or replacing the pipe can be done without sliplining by plugging the upstream manhole and pumping to the next downstream one. Depending on the flow rate, this may require substantial temporary piping and pumps and is not cheap (neither is sliplining). But it does allow complete removal and replacement of the pipe which may arguably be better than a repair. it sounds like this needs to be done sooner rather than later, regardless of your clients plans to build a parking lot.

You may want to consult with a local real estate expert / attorney to find out what your (client's) rights are with respect to using his property near the easement before you go into your meeting next month.

 

[LCruiser]

Definitely. Plus, I doubt if the easement was for a defective line...

 

[civeng80]

LCruiser you have really hit the nail on the head. I use to work for this authority some 20 years ago and know of this sort of corrosion in RC pipes. Indeed there may be nothing at the crown of the pipe except a hard crust of soil. The sewer also crosses roads and public property and private property such as this one.

Whats more if the main were to fail it would become a hazaed as it carries corrosive chemicals from a petrochemical plant upstream which have apparently caused the corrosion in the first place.

That being said they have rights over the property but so to does the owner who paid big bucks for the land and is aware of the sewer main but only to that extent.

I think some legal advise on this issue would be in order.

Thanks all, you have given me some very good points.

 

[LCruiser]

As cvg said, the easement does not give the water authority ownership. I think that's the bottom line. Provide them with written notice...

 

[civeng80]

I agree LVruiser

I think a carefully drafted letter from the land owner taking in account legal advise would be more appropriate than a meeting.