OK- looking for advice here. Need to replace about 150' of water line at my Mother's house (have new PVC, has sprung a leak somewhere we can't find, so looks like open it all back up.). In the woods, very damp location that has just had lots rain. I have a full size backhoe with a 24" bucket, but it is really tight in there, and really muddy. I don't own a trencher, but wondering how effective they are in mud? I can sneak in there with a CTL, and make a lot less mess- if the trencher will actually open up a trench. Having never run a trencher- have no idea how practical this is.
Hope you fixed it by now but my 2 cents. I have a t320 bobcat and a 313 bobcat trencher attachment with the added 1 foot extension, set 9 inch wide with rock teeth It will trench about 100 feet an hour in soil, roots and small rocks. The trencher chain can be set up for different conditions. Bobcat has a book on how to do it. With that being said I think either way it is going to be a mess. If it doesn't have big rocks or roots a vibratory plow and the black poly pipe might be something to think about.
Ended up with a 5T mini-ex. Brought enough clean in for backfill just around PVC. Then waited months for a dry spell to go finish up. Thankfully the woods hid it and she wasn't upset about the mess. The price was pretty good for her as well...