Shallow ditch - grade up or down?

[RedDirt]

When you have a shallow ditch to grade, a trough really, on level, or almost level ground, is it better to begin at the low point and work up to the source or start at the source and grade down?

I am fortunate to have my house on a high spot but it is almost level right around the house for about 80-100 ft before I get to a natural grade away from the house. I've graded shallow, wide troughs from the downspouts to lead away roof water and some of the ground surface run-off. While maintaining these over the years I've found if I start at the downspout and go downstream I invariably go deeper than I want at the start and end up having to grade further each time before I pick up the natural slope again. My troughs are getting longer each year and now I'm at a driveway crossing. With the hoe now I'll eventually put the rain water leaders underground but not this year. I've been experimenting starting to grade from the low end and work up to the high point and that seems to be working better.

What do you do?

 

[daBear]

I am not an old hand at tractor work and with my box blade I find myself tilting it as far as possible in one direction and cutting one side then the other after I turn around. However, I work with experienced military and civil engineers and their advice to me has always been to set the grade by going up hill.

 

[LBrown59]

I am not an old hand at tractor work and with my box blade I find myself tilting it as far as possible in one direction and cutting one side then the other after I turn around. However, I work with experienced military and civil engineers and their advice to me has always been to set the grade by going up hill.

If there is water in the upper end and you start there you will always be digging in mud.

 

[daBear]

Well that makes sense about always be digging in mud. What I do know for sure is mud plus dirt = more mud. Not dry dirt.

 

[LBrown59]

Well that makes sense about always be digging in mud. What I do know for sure is mud plus dirt = more mud. Not dry dirt.

But if on the other hand you start at the top you can tell by the water flow if you're digging it at enough slope for it to drain.

 

[CurlyDave]

With the hoe now I'll eventually put the rain water leaders underground but not this year.

When you get to that part, I have a tendency to dig a trench deeper as I go along with a hoe.

Nothing that paying a lot of attention doesn't cure, but be aware of it.

 

[RedDirt]

LBrown59
Scratching out a drain trench in wet weather is actually my method of choice if I have to do it by hand with a shovel. I can tell immediately if I am making grade and stop digging down and move onward. I find this much more difficult with the tractor especially if the ground is wet/soft. Then it is just as easy to grab six inches of depth instead of one inch. If starting at the top the trench now has to be longer than the minimum needed.


CurlyDave,
I have a lot of experience designing and laying out complex underground systems as a minor aspect of my work. For underground trenching I'd check distance versus drop as I go and shoot for 2% slope. I guess I could grade stake my surface drainage as well, with a minimum slope, maybe .5%, and rough it in with the tractor in the summer, then fine tune it by hand in the winter. It's only a few 80-100ft drain swales. If I wasn't four hours away from work (I tele-commute) I'd bring home one of our theodolites and do the job proper and easy. My home tools are just tapes and a good builder's level. This got the job done before we got so sophisticated and high tech so it would still work now too.

My initial question still remains though. For such fine grading is it easier to maintain grade by starting at the low point an work upstream? DaBear says yes and I tend to agree. Anyone differ?

 

[ampsucker]

me, i always tend to look for the cheapest way to do a good job. that being, in the case of grading drainage ditches and pipes, a cheap laser level (about 30 bucks) a couple of stakes and some string. if you really want to do it on a budget, and accuracy is a problem, a small line level (5 bucks) will do the trick, too.

start at one end with a stake, strap on laser level. put next stake about 30 feet away. point the dot at the stake. move the level to that stake and line up the laser with the dot and shoot to next stake. repeat until end of run is reached. now you have a reference point that is all at the same level. you can then figure out what kind of drop you want and run a string from stake to stake with the correct slope. now you have several options or more.

first, you can dig a small hole of the correct depth at each stake. this give you something to shoot for and you know immediately as you get close if you have it right. or, you can pick a reference point on your digging machine and sight along it to the string to check your progress as you go. me, i'm a hole digger, but i can see how some would prefer referencing as you go.

using this approach, it doesn't matter which end you start at, it always ends up the same. it's just a matter of preference or where you want the spoils to end up. once you're done, you can pound the posts in with the reference marks above grade so it's easy to do next time or figure out another more permanant and decorative way to mark things so you can go it the same each time.

best is probably just bite the bullet and put in the underground plastic pipe so you don't have to mess with it anymore and the lawn can start looking pretty ;-0

i am just about to finish up a drainage project in front of our shop building and have several more to do. wish it would stop raining long enough to get things dried out a little.

amp

 

[RedDirt]

ampsucker,
Thanks for the detailed explanation for the grading process. That's a very good, easy and accurate system; many will find it useful. I've plenty of experience with laying out grades but pros have always done the machine work. It is the finesse required to fine grade with a tractor that I am lacking.

I guess it will be like my sheetrock taping efforts. I can get the job done and it will look beautiful; I just do more sanding than an experienced taper does. Here I'll do more hand shovel and raking work than an experienced operator would.

We'd sure like to have some of your rain. Our forest's are ablaze and you can't see 1/4 mile. Luckily none of the fires are terribly close or immediately threatening to us but with so many fires (800 now) the entire state in under a smoke blanket.