Help with a curb stop

[rjh]

I have a steel building with water lines underground to it. Inside the building copper supply lines come through the concrete (both cold water) to a sink. Outside on the sidewalk is an old fashioned farm pump looking valve that sticks up about 3 feet from the ground; you lift the huge handle and water comes out year round (I guess it's driving a valve deep under ground). Next to that is a 3" PVC cap that when removed, reveals a 3-4 foot pipe with a simple valve in the bottom. I use a curb stop tool to open that valve to turn the water on to the sink inside the shop.

My problem is now that when I try and close the curb stop so I can shut off the heat in the shop for the winter and prevent those pipes from freezing, the valve leaks - you can hear water hissing out and see it in the bottom of the access pipe. If I open the valve and let the sink faucet stop the water flow everything is fine - the curb stop doesn't leak. It was closed for ~2 years, then left open continuously for ~5 year, then we opened and closed it a few times this fall. I just went out to winterize and found it leaking when closed.... so now I've got an electric heater running to keep the pipes from freezing, but it will occasionally trip the breaker and I don't want to have to go check on it every morning.

Does anyone know of a way to stop that curb stop from leaking when closed? The only access I have too it is down a 3-4 foot length of pipe. I'm really hoping I don't have too jackhammer out the sidewalk and excavate all the way down there to the valve to turn it off!

Thanks!
Rich

 

[rjh]

Could I run some kind of expansion tank on the stubbed in pipes to allow them to freeze and not split the copper that's run up through the unheated cement slab?

 

[Dirtmechanic]

Could I run some kind of expansion tank on the stubbed in pipes to allow them to freeze and not split the copper that's run up through the unheated cement slab?

Go to a convenient spot and put in a shutoff so you do not have to jackhammer the walk up. Just leave the old valve on if it works that way. Its not necessarily the pipes splitting, as there are different thicknesses of copper pipe and some are quite strong, but certainly the appliances are not made for freezing.

 

[rjh]

After more experimentation and consultation with a local plumber, we've determined there is a relief valve on the curb stop.... it's a shutoff for the sink in my barn, so when you turn the curb stop off and have the sink valve opened, the water in the line is allowed to drain out to prevent freezing. While turning on/off there is a small part of the turn where the relief valve is open to the water line pressure, causing it to "hiss".. but closing it past that point just allows the sink line to drain out. After 5-10 minutes, the water drains through the gravel in the bottom of the access pipe and seems to stop.

 

[Dirtmechanic]

After more experimentation and consultation with a local plumber, we've determined there is a relief valve on the curb stop.... it's a shutoff for the sink in my barn, so when you turn the curb stop off and have the sink valve opened, the water in the line is allowed to drain out to prevent freezing. While turning on/off there is a small part of the turn where the relief valve is open to the water line pressure, causing it to "hiss".. but closing it past that point just allows the sink line to drain out. After 5-10 minutes, the water drains through the gravel in the bottom of the access pipe and seems to stop.

I like that better than my separate drain valve on my lawn irrigation. Less to mess with in the end.