Critter control is always part of raising worms. I have heard gophers and moles love worms and can devastate a bin. I have been battling large wood rats in my worm beds. YUCK! I have had some luck repeling gophers with those electronic stakes.

Many line the bottom with hardware cloth. This would be tough with a vermi-trench. On a new raised bed this could be attached to the underside of the frame.

Do the moles come into your current raised beds? If not maybe they will not bother them. Please describe your raised bed and trench and how many worms ect.

Hope this helps. Good luck

Mendopete - thanks for answering. My raised beds are old, so that is out to put the hardware cloth in there. I have not seen any evidence of moles working in the beds, but then I did not have any worms in there either. We are just starting, so I do not have as yet a large number of worms. I guess the only thing I can do is hope for the best. Thanks again. Barb

Oh, yeah, moles are on worms like a toddler on a French fry! LOL
You might want to get one of the commercial mole repellants on the market and use it just around the perimeter of your raised bed area. Maybe that would be enough to discourage any forays into territory that is new to them.
Just be careful since I think the active ingredient is derived from castor beans and of course they are toxic. Just read/follow directions though and all will be well.

If you lived near me I would give you a brand new container of it that I got just before we moved to central OH from SW PA (where I did have moles). Although there are moles around this area, there are none in any of the yards around us for as far as I can see. :-)