I don’t live in Worcester anymore but I used to run around Lake Quinsigamond. Adding the small side and large size together will give you 10 miles but there will be points where you are running in the bike lane.

The West Boylston Rail Trail was good. It was 10 miles out and back from the parking lot to the end of the trail. Bonus to that was the way back was mostly downhill.

The Rutland rail trail is where I used to go to run over 10 off of the roads. I could easily get in 20+ there.