I do this for a living and the rates vary. I have a CT322 with a trencher (avatar). There are factors that decide how efficient the job can be done.
- Wet soil, especially wet clay, is not advisable to dig in. Gumming of the chain will slow trencher, thus heating the oil which may result in damage to seals of motor, etc. Cuttings will not shed properly either.
- Wet ground = less traction when trying to back up as the trencher is pulling you forward.
- Roots (self explanatory)
- Rock (self explanatory)
- Sand (cave back)
- Area of country
The above factors, as well as how deep the cut is needed, determine what I charge . My chain is 8 inches wide with a 8.5 inch cut. Figure your profit you want to make after your overhead.
As far as the size of pipe to run, at that distance, run a 2 in. line for 1000 ft. then reduce to 1 in. for the next 200 ft to minimize shock and popping if the water valve is closed abruptly.
From my experience 