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.

Slippy · Feb 25, 2005

I think I have seen a surveyor use the pee gun your are talking about. He walked through the woods and marked a boundary line with it. I have a small lazer that goes on a little trypod. Uses a couple of AA batteries. Has a level on it. Trouble is it is not very bright. Maybe I should do my digging at night or wear dark sun glasses. /forums/images/graemlins/cool.gif How much does one of the beeping levels cost. Saw them on tool web sites for about $250 self leveling. Are they worth it?

Highbeam · Feb 28, 2005

I use the pee level for designing septic systems. They are not as accurate as a tripod mounted level but they are a quick and easy deal that you can keep in your shirt pocket. You aren't building a watch here.

The problem is you will either have to climb into the trench or set a rod down there to be able to compare the invert to your reference point. If you don't want to climb in (can't blame you) then you will need another person.

rdbrumfield · Feb 28, 2005

for a beeping unit, self leveling, that is a good price. Mine was close to a grand 5yrs ago and I have to level it. It does have a window on that I can put % grade however. That can come in handy.

Slippy · Mar 2, 2005

Humm, that would be a nice feature so you would not have to move your level or keep track of the changes.

How do you create a ditch for drainage if the area you are trying to drain is lower than the area you want to move the water to? I built a lean too on the back of a barn and have a low spot. Put in a ditch but by the time I got to where I need to be, I was so deep I don't know how to finish off the run. I guess one way to do it would be to put in a tank of some kind and run the water in with an outlet out higher, would that work?

slydog · Mar 2, 2005

( How do you create a ditch for drainage if the area you are trying to drain is lower than the area you want to move the water to? I built a lean too on the back of a barn and have a low spot. Put in a ditch but by the time I got to where I need to be, I was so deep I don't know how to finish off the run. )

"Gravity, it's not just a good idea. It's the Law!"

I'd like to hear the answers to this one myself /forums/images/graemlins/smile.gif The only thing I can think of to make water run uphill is a pump.

( I guess one way to do it would be to put in a tank of some kind and run the water in with an outlet out higher, would that work?)

There again...if the water can run in, it's not going to fill "up" from the level it runs in at. But if you can figure this one out someway, please post a few pictures and instructions.

Highbeam · Mar 2, 2005

The tank trick will work if you are only interested in conveying the roof water. Surface water needs to me motivated to run uphill.

If you have a closed depression with no outlet, you will end up with a swamp unless the soils percolate very well.

The answer is to bring in fill to level the depression

aondre · Mar 2, 2005

I use grading stakes that I set with a laser. When I first started I would put a stake about every 5 feet, now with a lot of experience I put them every 10-20 feet.

A long drainage ditch on level land is going to be deep on one end. If you want good drainage you need that slope, the longer the ditch, the deeper the ditch. Most of the cities where I am require at least 1/8" of slope every 1' of run (if possible). So a 200' ditch on level ground will have one end over 2' deep.

If you do get a laser I highly recommend a self leveling one, it will save you an unbelievable amount of time.

drm · Mar 2, 2005

Slippy,

The tank with higher outlet will not work without a pump. There are a couple of ways of draining the water at the end of your run:
1. Install tank to collect water and sump pump to pump water to higher ground. Expensive and a maintenance issue.
2. If your soil drains well you may be able to dig a large pit, line with filter fabric, put in large rock to create a holding area for the water to collect. Cover with filter fabric and topsoil.
3. Same as above with a sump pit type box or culvert box with bottom removed sitting on a bed of gravel.
4. Leach field.

Of course the applicability and cost of these will depend on the amount of water and soil conditions.

…Derek

Slippy · Mar 5, 2005

If you put in grade stakes, how do they work? If you site a line with a lazer from your start point, do you mark the grade stakes level with the starting point and then measure the depth of the ditch from the level point on the stakes making sure that you are keeping a slope as you go along?

My soil does not drain well, so only option would be a sump of some sort. /forums/images/graemlins/crazy.gif

rdbrumfield · Mar 7, 2005

Grade stakes are a reference point from which to work. As the ground is not always level or at a constant slope, you can put a stake in every so often as you like to take grade off of. You can put them in, takes two people with a transit, one with a lazer. By putting a "depth to dig" mark on the stake and a number for depth when you get to that point in the ditch or footing, you can come off that mark to keep you at grade. Always offset the grade stakes so that you have room to work your machine, and do not pile dirt in front of them so you can be in the ditch and see the mark on the stake. If you know where some construction is going on, whether it is laying pipe or road building, stop in and see if someone is willing to give you a short lesson on how to do this. Once the light comes on it is easy.