Unable to find any well suited trencher for digging ditches for irrigation pipes to be laid into. It seems there are no models on the market that would take care of the slanting for us. All models are just able to manually set the trenching depth and use that one all along, nothing like an 1% or 2% slant option. Also, I would need them to go about 2 feet deep maximum. Are there any such trenchers on the market ? Thanks!
EDIT: slanting as in sloping the trench:
The easiest way to deal with lawn drainage problems is to slope all land, patios, walkways, etc. away from your house. The minimum slope that I work with is two percent, or 1/4 inch per foot
http://www.landscape-design-advice.com/landscape-grading.html#.VWTNrrzsc2s
EDIT 2: I feel I am not making myself understood.
So, the trencher should automatically lower its sawing head (chain / disk) into the ground as it advances. For a 1% slope, it should continuously lower its sawing head at a rate of 1 cm for every meter of dug trench. The operator should just set up the initial digging depth together with the desired sloping (1% for our case), walk along the trencher and after 10 meters of walking the sawing head should be 10 cm lower than initially set up. Hope I was clear, thanks!