Ditching & keeping grade or slope

Slippy · Feb 21, 2005

When using my backhoe I am constantly getting off and checking depth of ditch. Is there a trick to it? Sometimes I want to keep it level, and other times I want it to slope for drainage. If you are digging a long drainage ditch that is pretty flat, how do you keep from having a deep ditch at the end which makes it difficult to drain into a stream, etc.?

EddieWalker · Feb 21, 2005

The simplist method is to know your dephth of your bucket.

Extend your bucket all the way and mark one foot incriments, or more with some spray paint on the front so you can see the lines.

If you are dealing with changing slope, you can either measure the slope and mark the sides of you trench before you dig with stakes or just spray the amount of change on the ground.

Egon · Feb 21, 2005

Batter boards or a spirit level were used to maintain a trench grade. Now I would beleive a lazer level would be the instrument of choice.

Egonl

dummy · Feb 23, 2005

Spirit level? Is that what the northern guys call a story pole?

Egon · Feb 23, 2005

Nope, Just an ordinary ol'l carpenters level that has a bubble of air in the container filled with spirits.

Egon /forums/images/graemlins/grin.gif /forums/images/graemlins/grin.gif

Henro · Feb 23, 2005

Following grade using a mark on the stick like Eddie said works real well.

Now if you want to make the bottom of the trench level while digging on a slope, that is more difficult.

The easiest way I have found is to get the high end where I want it, then let get some water in the ditch. As I continue digging, the water level tells me where I am at...this works even better when trying to get the slope gradual for drainage, while digging where the ground is sloping also... /forums/images/graemlins/smile.gif You don't need a lot of water that way...it just keeps following the bucket as you move along... /forums/images/graemlins/cool.gif At least in clay as we have here... /forums/images/graemlins/tongue.gif

Hope this makes some sense...I think I stumbled on this method after it rained one day.... /forums/images/graemlins/blush.gif

Currmudgeon · Feb 23, 2005

The way it's usually done on a construction site, is with a laborer marking grade.

Using a laser level set to the grade you want, and a easy offset, say a foot, above the trench bottom grade, is about the easiest way to maintain grade. The only problem is that the bucket blocks the view of the laser-spot - it hits the backside of the bucket. But with a bright laser, you should be able to see the spot on the near slope, and gauge from there.

Othewise, you're kinds stuck using a surveyor's level or batter boards and a stringline.

rdbrumfield · Feb 23, 2005

Keeping grade is a real talent and it takes practice. To keep on the digging machine and keep grade, it takes two people. By opening the bucket to the stop and painting markers up the bucket and crowd is a nice reference as long as the ground is at the same angle of grade you need to dig. I like to use a pee-gun or eyelevel, one and the same. you don't have to use lazers and such to get a good ditch. Use an engineers tape that is measured in 10th's instead of the usual 12inch foot. You will find that it is much easier to get grade % with them. Just by sighting at a rock or paint mark that is a permanent spot, you can sight from your tape to the mark to keep grade.

Slippy · Feb 23, 2005

I think what I have done is what you have described. I have a transit and stick. I have set up the transit level and checked my depth at the starting end, and then move the stick along the ditch watching the grade variations. I don't know what a pee gun is. Is it similar to a transit?
The lazer is a good idea, but I have not found one that is reasonably priced that is bright enough.
Any one seen ones that beep and as you move the stick the beeping or lack thereof tells you if you are keeping grade? You could do this with one person as opposed to two with a transit and stick.

rdbrumfield · Feb 25, 2005

A pee-gun is a small hand held level that has a bubble in it that you look through like a transit. Only it is hand held and is about the size of a large cigar. I do have a transmitter-reciever that uses the beep system and has visual cues that let you know grade. They are very handy tools for trenching and large areas like house footings as you can set up and check grade for the whole of the footing. I use mine right on the blade of my dozer. Having welded an attach point on the back of the blade and putting a short pole that the reciever can attach to inables a person to cut grade right to fractions of an inch. I have also used a carpenters level with the red lazer for ditching. They are reasonably cheap, can be put in the bottom of a ditch and some have a bubble that can be rotated a bit to get percentage for fall. I once used one for a small open ditch that was a couple hundred feet long. By setting the lazer on a tripod centered on the ditchline, attaching a 2x4 on the edge of the dozer blade and stapeling a small arms target for a reference I was able to keep constant grade as I moved away from the lazer. I hope this all makes sense.