Tanker Dome Gasket

You're only option for tank wash would be in reno. I'm sure they gotta have tanks running around out there. Truckee would stop you if your leaking enough that they can see it. Probably. Sacramento operates banker hours and sometimes they don't even work that. So you can roll through there after they close. If you have to go farther down to the 3rd scale. They hardly ever close.

As for popping the tank lid. EVERY tank has to have a valve somewhere that releases pressure and vacuum before popping the top. Kind of hard to fill up if you can't release the pressure and kind of hard to dump if you can't release the vacuum somehow. As for that picture you posted above. I'm pretty sure there's supposed to be a something to screw on them threads to tighten it down. Unless you left it out of the picture.

Course, i hauled one tank that had one missing and it didn't leak.

 

I've seen this happen before. Only way to stop it is to replace that gasket and/or tighten that LARGE bolt at the hinge of the dome lid if it's that type. Really sucks-it happened to me on a brand new trailer hauling asphalt oil. Bolt was loose as was the gasket slipped out of place.