sounds like the spring inside the tensioner finally broke

Had nothing to do with the tensioner after all.  I found out the morning
after the belt had come off what really happened.  When I opened the hood
that morning, I noticed that the tensioner was swung way back, yet the belt
was still loose.  So I checked the routing of the belt on the pulleys and
that's when I saw the idler pulley below the water pump was completely
missing.  The belt was resting on the bearing and the pulley was laying in
the bottom of my driveway.  The bearing was seized completely solid and
apparently the belt, while trying to spin that frozen bearing, ripped the
idler pulley right off the bearing and chucked it out into the driveway.

Long story short, my brother in law happened to have an old Cutlass Ciera
junked in his yard, so I pulled the idler pulley off of it and slapped it
onto my car.  Today after work, I stopped at a bearing supplier in Burnside
and picked up two new bearings, one for each idler pulley on my car.  Once
the new bearings are pressed in, I won't have to worry about them seizing up
again.  The tensioner is working fine and everything is back to normal
again.

Only on a Chev product would the water pump AND the idler pulley bearings
both self destruct at the same time, LOL.

Sharky