Is there an irrigation trencher that can create sloped trenches?

Question

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!

Answer 1

I'm pretty sure that I clearly understand what you want, but I find your disbelief at the fact that nobody makes it baffling. What you seem to think you want is predicated on dead level ground to run on - which is incredibly uncommon in actual practice. Odds are excellent that the ground you think is flat is not, unless you have measured it with a precise level and knew how to set that up and use it correctly.

To do what you want done on real ground (automatically) would require some sort of automatic level & position detection - typically done on extremely expensive earth moving equipment with a laser & reflector-prism arrangement. Good luck getting that and the associated control mechanisms built into a trencher and having anyone buy it, but perhaps it might be an option after a few more rounds of computer processing shrinking and cheap-ifying; though most of the expense is already in the mechanisms to get the machine to do what is needed, rather than the processing. Big earthmovers with laser level referencing make very flat fields for irrigation, so the general ideas are well understood. The economics don't really scale well for trenchers.

To do what you want (whether or not you need to, and whether or not sprinklers and landscaping that requires them are a good use of water in your area, or any area) with real equipment you can get now, all you need to do is use a precise level to set up planks in a track along the trench, sloped at 1%, and dig at a constant depth from the track.

Or do the same thing with a shovel, a hoe, some stakes, and a precise level.