red ear sliders?

I also posted this is the water garden thread:

My husband and I will be making a pond in our backyard in the next few months. We plan on having goldfish (shubunkins?). A friend of mine has 2 red ear slider turtles that are too big for her fish tank, and is looking for a new home for them (2 females). Can they peacefully coexist with the goldfish in our pond? The pond is open to our yard, but the yard has a standard closed cedar fence. I wanted to ask before I gave them a new home....