Underground Valve VERY Hard to Turn

I have a quarter turn valve for a sprinkler system that is buried 3 ft deep. It has gotten so hard to turn on or off that at 71 yrs old, I cannot do it. My tenant is 35, pumps iron and is totally fit. It takes all his strength to turn it. These were installed in 1993 and were supposed to be "50 yr valves". I am afraid of something breaking, creating a real mess. Are there any tricks short of excavating (hand digging) and replacing this? This is a duplex and the twin valve on the other side still works perfectly.

 

And how would anyone know, we have no picture, no idea what type valve it is.
PVC, ABS, Steel, cast iron?

 

As Joe states, we really need a picture before making any suggestions. Most likely it WILL require digging it up and at least disassembling if not outright replacement.

If it is a PVC (plastic) ball valve it may have union ends to allow it to be disconnected. If it is glued in place it will be a difficult job. In any case, PVC ball valves are suspect unless you get very high quality ones.

It may be a bronze/brass lubricated plugcock and if so it may be able to be re-lubricated. It will still require a fairly large hole to access the bottom of the valve. If it is a steel or cast iron plugcock then whoever installed it should be shot.

 

I can't provide a photo because it is 3 ft underground. It is a brass valve set in 3/4 copper. I do recall the plumber drilling the valve body so that it would drain when shut off for the winter. I wonder if that hole has led to contamination. It is working for this summer, so I guess I'll excavate in the fall.

 

Sounds like it is a tapered plugcock. You will most likely have to dig down to it in order to take it apart and re-lubricate.

I have a vague recollection of "upside down" tapered plugcocks that were also spring loaded. They were specifically for buried applications and could be loosened by smacking the "reach rod" (the extension piece that allows operation from above) with a hammer. I have no idea if they still make these valves or if you might have such a valve. You might try gently, but smartly, tapping the reach rod to see if it loosens.

 

I'll try that. Another thing I remember from the plumber was that he had a lot of difficulty in stopping a leak on the new valve and I think packed it with some extra heavy grease. At my age I remember snippets from 23 yrs ago, but not what I ate fore breakfast. The tapered plug valve makes sense and I recall this being an expensive job in '93. I was young enough to dig the holes then.