Info from client: When they excavated to the area of failure it was noted that there were other areas that looked similar to the failed areas that had not corroded through yet. These areas were corroding from the outside...

My theory was similiar to your reply with the electric current in the line leaving through the service connection (grounded). As to why this is only happening in the dormant connections, my theory is that in the active connections, they are bonding the water lines to the electric panel giving the current another route to travel....

Anyone else with insight into this occurance please reply. This is just a guess on my part.

Any suggestions on a remedy?

Maybe soil surveys could provide clues as to the presence of electrolyte and other corrosive environments. I guess one could also look on as-builts or other plans etc. for any nearby sources of stray current (e.g. cathodically protected gas etc. pipelines, subways, electrical devices, etc.) If stray currents are present, I suspect those with the proper technology/equipment could probably also be detected with the right expertise and equipment (e.g. with spaced, ground level cell-to-cell surveys or other means?) and/or maybe even somehow quantify this? Perhaps once it is determined what is going on a remedy might flow (so to speak) from that.

Is Ohio not loaded with salt? (Salt Rock - Salt Creek).

Is there salt in the vicinity?

What is the composition of salt or soil?

In the locations that we are talking about, there could be varying levels of salt in the ground at these locations, but it should be relatively low. I don't think this wouldn't explain the dormant v. active situation.... could it?

Acidic soils can cause this, but not usually to this degree. I would agree that the homes with active services have probably grounded the water service in some way, but probably not on purpose. I would think it is several problems compounding - acidic soils, stray currents, etc. Any time you install copper or DIP in the ground and leave it unused, it will degrade faster than if it was in use. Remember that most water systems use chemicals to treat the water, that actually stick to and "line" the interiors of the water mains and services.

Have you tried cathodic protection at least in some test areas to see if that will stop the problem?

Is there a lot of lighting strikes in the area?

Ok, let's assume that is it a stray electrical current leaving the system through the service laterals. What would be a possible solution to keep this situation from occuring?

Bond the line to a grounding rod similiar to the way you would an electrical system in a home? Other suggestions?

Sorry, the post above me showed up while my slow butt was typing... We have not tried anything at this point. The situation was just presented to me within the last couple of days.

What type of cathodic type protection are you referring to?

There are several sources which provide those services, but you might start with something as simple as the zinc cathodes you use on marine equipment. You can find those at any marine/ boat supply.

Is it possible there is a buried parallel utility, such as a steel gas line, for which your copper line is acting as a sacrificial anode?

These are occurring in a new condo development and the gas lines are a HDPE pipe, not steel. All other lines are typical of new construction.

I have had pipes corrode from the inside - with acidic water;
where the copper pipe walls were literally tissue paper thin.
Only the water pressure made them look like a pipe, and
when the pressure was removed they would just collapse in.

In the absence of soil or cement contact, I would suggest
something is touching the pipes and leaving an acidic coating,
e.g. mice/cat droppings or fluid? Even condensation drips?

Hope this helps. jt.

ohio andy; it sounds like a open neutral at the power line connection somewhere, i would take a clamp on AC ammeter, clamp around the water pipe and see if you have any current reading perry

We have scheduled an electric contractor to come in a see if he can detect any current flowing through the pipes.

Thank you everyone for your comments. I am happy to see that my line of thinking wasn't completely out in left field.

I know that metal pipelines in the close vicinity of electrified railways are always cathodically protected, specifically if the power supply is DC as opposed to AC. Let your contractor also look at that possibility. Doesn't really explain the disparity in active vs non-active lines or the way they are connected....

Salty or acidic soil can definitely do it, but unless the local ground is really salty you have a different problem. The problem has to do with electrical corrosion, but one does not need an electrical power source to cause the problem. As Randy Conner suggested, get a soil study done. The thing that will cause this problem and eat those pipes faster than anything else is simply having a dissimilar metal from the copper in the soil. A little dampness and we have a nice battery and tons of rapid corrosion running 24-7.

Contractors that I know always do soil studies before building and then provide piping of an appropriate material to prevent or at least reduce this kind of problem or on occaision when such is not possible or local codes prevent using other materials, they will 'fix' the soil by mixing in a chemical that binds tightly to the metals in question, preventing future corrosion. One contractor puts his piping in a PVC sleeve to avoid the issue and the associated costs altogether.

i've found thess articles from copper.org

Conditions Contributing to Underground Copper Corrosion

http://www.copper.org/resources/properties/protection/underground.html

How to Prevent Corrosion of Copper Tube in Underground or Buried Applications?

http://www.copper.org/applications/plumbing/techcorner/prevent_corrosion_cu_tube_buried.html

i think that it can give you some good info on the cause of copper corrosion

hope this can help u

S

corrosion prevention & control