Financial terms of the deal, announced Tuesday, weren't revealed.
The 23-year-old Galiardi played only 35 games last season because of wrist and forearm injuries. He finished with seven goals and eight assists. The Avalanche selected Galiardi in the second round of the 2007 draft.
Rissmiller, 32, played for five teams last season, including the Lake Erie of the American Hockey League. He was originally signed by the San Jose Sharks in June 2003 and has played in 192 NHL games.
It's about enjoying the moment. It's pretty cool to get that many people together and that excited about hockey to the point they really want you to mess up. They've got a ton of red jerseys and you have to sit back and appreciate people love hockey that much and you are the one out there who gets to play the game. Just try and stick with that respect for the game and also the mentality that for me it's just about entering the fight and seeing how long I can stay in it.
— Canucks goaltender Ryan Miller on what he expects from the fans in Calgary for Game 6