(tl;dr - check the bolded questions and look at the pictures)
Earlier this week I had a frozen (and burst) pipe. It's on the way to the outside spigots and not particularly important in the winter, so I turned off the valve feeding it (that should have been off already, yes) and put the repair on my todo list.
However, I noticed today that it hadn't dried completely in the basement space below this leak. It looks like the shutoff valve didn't work completely - there's still some flow out this ruptured pipe.
The problem now is that I can't figure out how to operate the only other valve upstream of this leak. I tried once in the past and couldn't make it budge.
No markings other than Meuller. I gripped the handle on the left with a large pair of adjustable pliers and applied as much force as I could in both directions, no luck.
Here's the layout, in case it's in any way helpful -
Water enters the T at the bottom center. To the left through the blue handled valve and defunct water meter is the rest of the house - no issues there. To the right and up are the pipes feeding a pair of outdoor spigots. At the top, the red handled valve is the leaking valve leading out to the ruptured pipe. As far as I can spot, this Mueller valve is the only other way to cut off that side, short of the buried valve at the curb - and I don't have a t-handle to reach in there.
I've plugged up the leak as best I can at the pipe, and fiddled with the cheap plastic valve some more, and stopped things for now. The question I have for you guys -- How do I operate the Mueller valve? Is turning the key on the left correct? Does it turn clockwise? Do I need to do anything with the coverlike part on the left side of the valve body?