"Feeling" lines with the backhoe

[digger242j]

In another thread recently, the subject came up of "feeling" something with the backhoe, and not breaking it. The particular comment had to do with an electric line, and the results were apparently not good.

I have some opinions, and a few war stories.

Anybody care to share their thoughts on whether or not this is an operationally practical approach to locating buried obstacles?

 

[RonG]

I have had a fair amount of success with ductile iron if it is big enough!! LOLOLOL Ron

 

[Bob Horrell]

I think it depends a lot on the dirt you are digging. If the dirt is fairly soft and rock free then you can feel iron pretty easy. If the soil is rocky, you can't feel squat. I recently did a job for a school were I had to dig about a mile of trench connecting all of the buildings. There were a lot of water lines that weren't marked and I felt every one of them (13 altogether) and broke none. I knew there were some unmarked water lines and was trying to feel for them and not digging as fast as I might if I wasn't expecting something. The soil was rock free and under sod so it was wet and easy digging. I did punch my teeth through a plastic drain pipe before I felt it. It was softer than the surrounding dirt so I couldn't feel it until the teeth were through it and the bucket contacted it. I ran into a little sand at one point and stopped and probed and one half inch lower was a newer plastic gas line with a tracer wire that was missed when they marked the underground utilities. You can never count 100% on the guys doing the marking.

 

[ForsytheBros.]

Digger-

I responded to another thread of yours on another situation but figured i'd follow on this as well.

I"m not embarrassed to admit that we are NOT good at feeling utilities on jobs. We'll typically pothole by hand to find marked lines (sometimes scratching with a machine for the first portion to start) and then continue trenching under the utility via backhoe and shovels combined. That said, we are pretty careful excavators in my opinion regarding honoring existing utilities.
We have found in trenching operations with backhoes (utilities are mostly what we're doing now) that if we take long, shallow passes with the machine that fill the bucket with crumbs as opposed to a big , massive , hog-out, that helps us to be a little luckier in finding pipes/cables that are unmarked without damaging them. I'm still fighting this battle in my mind, cause digging around such obstacles has been a major production dropper for us, and most of this stuff is not usually on the plans.

 

[tylermckee]

Digger-

I responded to another thread of yours on another situation but figured i'd follow on this as well.

I"m not embarrassed to admit that we are NOT good at feeling utilities on jobs. We'll typically pothole by hand to find marked lines (sometimes scratching with a machine for the first portion to start) and then continue trenching under the utility via backhoe and shovels combined. That said, we are pretty careful excavators in my opinion regarding honoring existing utilities.
We have found in trenching operations with backhoes (utilities are mostly what we're doing now) that if we take long, shallow passes with the machine that fill the bucket with crumbs as opposed to a big , massive , hog-out, that helps us to be a little luckier in finding pipes/cables that are unmarked without damaging them. I'm still fighting this battle in my mind, cause digging around such obstacles has been a major production dropper for us, and most of this stuff is not usually on the plans.

Thats pretty much how we operate as well. we pothole any utilities we will be crossing, using the machine and hand digging. And if we are digging around any existing utilites its shallow long passes. You can feel old steel gas lines pretty easy, same for ductile water lines, anything else is pretty tough. Usually find the old trench line, or the if the material you are digging gets soft or you find some sand, that gives it away. That being said it doesnt alway work out. I caught a power line a few months ago, it was in conduit to cross the street, and i hit it right where the conduit ended and it went direct bury. Ended up ripping it out of the transformer on the other side of the street. It wasnt a cheap repair they had to replace the transformer, send in a vac truck, had two power crews, flaggers, some environmental agency was out, they made a huge deal out of not much. All ive hit though, well besides a few unmarked sewer or storm services that we had no idea were there, those are a just a 5 minute fix though.

edit i forgot i also snagged a 50 pair phone cable a month ago. It was dead and wasnt located though, and i sure as hell didnt 'feel' i.

 

[mflah87]

One of my guys wackd a high voltage electrical line with the backhoe and melted part of the bucket. It was a real rocky type of soil so I can blame him, and o yea digsafe was off by 10 ft;.

 

[DigDug]

I have had a fair amount of success with ductile iron if it is big enough!! LOLOLOL Ron

HAHAHAHA!

 

[tuney443]

Thank God when I found that skull to the mastodon I had my old machine because I would have never felt it with the new one with pilot controls.How do you tell 20 scientists ''Oops,sorry'' after you smash a 12,000 yr. old skull?----------You don't.

 

[dayexco]

when it comes to the loss of life, serious injury, or damage to property......man, i'm reluctant to trust my "feel" on the sticks, and it's not like i'm a newbie here, i've been running hoes now for over 30 yrs.

all pilot controls do is remotely actuate the valve body and remove the mechanical linkage. in theory, you should get the same "feel" from the machine whether you're direct linked to it or through pilot controls. i doubt there are many "if any" here that can feel the difference between a 1" poly water line, and the virgin surrounding soil. you see a discoloration in the soil from the excavation, or what you're feeling is a difference in the soil that has already been excavated at one time or another. i'll buy into the idea that you can feel a larger phone/power cable, a larger diameter steel, pvc water/sewer line. but in my opinion, what you're sensing is your machine working a little harder.

 

[Bob Horrell]

Sometimes you can see the ground move on each side of the trench before you break a line. This is especially true if you expect something might be there. This has saved me a number of times. The deeper the trench the less likely this will work for you as the force required to move the dirt in a deep trench is more than the force to break a pipe (the pipe is help firm by all the surrounding dirt).

 

[Dozerboy]

I can feel a 3/4 conduit if I have a good idea where it is but normally I feel them right by a fitting and brake it. Out here there is so much rock most of the time you never know. Now with my dozer anything is fair game even the 12" water line that didn't exist per the "as builds" I hit a few weeks ago.

 

[jmac]

In just a few short years I have hit my share of stuff. On one job two summers ago the water line to the house was never marked by the water board and was very old. The home I was working was 100 years old. Hit the water line twice on the same job and city could not find curb box to shut off water. We had to repair it under pressure twice. Good thing it was 90 out both days because every one got wet.

On a job this summer had a 4" sewer line to put in and connect to main. It was about 300’ of trench to dig. Running the whole length of the trench was a direct burry phone line that ran the fire alarm to the building. I told the plant manager that chances of me not hitting the phone line was not very good. He said to me "if you hit the phone line the plant will pay to have it fixed because he wanted the sewer line to run at the location he specified and not move it over a few feet. After digging the whole trench but about 10' left the line was so old that it was broken by the shovel my guy was using when he was digging it up. The repair cost $1100 and the plant billed back the GC the whole bill and the GC deducted the bill from my check. I tried to argue the point, even called the plant manager and he remembered our conversation but he said "I didn't realize it would cost that much to fix so I have no choice but to charge the cost to the GC" Basically I got screwed. :Banghead Worked for free that day. I don’t know if I am making any point here but just to say that if you hit you will pay to fix it. It has been that way in my past experience. Next time I will get it in writing or put my machine back on the trailer.

 

[tuney443]

when it comes to the loss of life, serious injury, or damage to property......man, i'm reluctant to trust my "feel" on the sticks, and it's not like i'm a newbie here, i've been running hoes now for over 30 yrs.

all pilot controls do is remotely actuate the valve body and remove the mechanical linkage. in theory, you should get the same "feel" from the machine whether you're direct linked to it or through pilot controls. i doubt there are many "if any" here that can feel the difference between a 1" poly water line, and the virgin surrounding soil. you see a discoloration in the soil from the excavation, or what you're feeling is a difference in the soil that has already been excavated at one time or another. i'll buy into the idea that you can feel a larger phone/power cable, a larger diameter steel, pvc water/sewer line. but in my opinion, what you're sensing is your machine working a little harder.

All I meant was IF {if being the key} I'm looking for something,then you stand a much better chance of not hurting it than with a machine with pilot controls--no question.I'm not looking to dig things up either by feel without calling Before You Dig.It was meant as a light-hearted, if you will ,post--that's all--really no need for all the seriousness.

 

[Klutz]

The generic older american backhoe has an open center hydraulic system with gearpumps. In a system like that the force of the bucket depends on the position of the lever (and hence the spool) and the flow (engine rpm). This is a dead simple system that works good enough for most purposes. One of the advantages is that, theoretically, it gives you a chance to "feel" things in the ground. The disadvantage is that effiency goes radically down when you are doing slow movements that require a lot of force.

Today I think most american manufacturers offers a couple of models with a more modern load sensing system using variable axial piston pumps. It's an unfortunate choice of name as this type of hydraulic system does NOT allow you to sense what's in the dirt.
The name comes from the fact that the pump regulator "senses" the pressure on the load side of the valve. The pump then keeps a constant pressure drop across the valve (for any given spool position) regardless of the load and the rpm. The germans sometimes use the word "lastunabhängig" (load independent) which better describes the charachteristics of the system.

While it is certainly possible to make an open center system with pilot controls or a load sensing system with "floor sticks" neither is very common.
It would be like ordering a new car with a powered sun roof and manual crank windows. Maybe that was a poor example but I hope you see what I mean.

This means that both tuney443 and dayexco are absolutely correct in my opinion.

 

[Klutz]

Maybe I should clearify a little. Dayexco is right when he says that all pilot controls do is remotely actuate the valve body and hence it wouldn't make much difference on the ability to feel something in the ground.

True, but a machine with pilot controls is very likely to have a load sensing system and away goes the ability to feel stuff in the ground, just like tuney443 noticed.

 

[lgammon]

Maybe I should clearify a little. Dayexco is right when he says that all pilot controls do is remotely actuate the valve body and hence it wouldn't make much difference on the ability to feel something in the ground.

True, but a machine with pilot controls is very likely to have a load sensing system and away goes the ability to feel stuff in the ground, just like tuney443 noticed.

the old 580sl was alot easyer to feel it SEEMED than the 420e we have now it just feels like nothing when you are digging with it. and the fact that when we used to idle the machine down when digging around stuff hence less power so when you hit a little resistance you heard it where as the cat has pretty much the same power full throtal or at idle it doesn't help much

 

[KeithRA]

I don't know what you guy are talking about pilot controls they are more precise then old style controls.I dig i can feel plastic pipe.My father could feel 1/2 gas pipes with old controls.I make alot of operators scared the way i dig.I can dig all dirt from around utility with machine.I not talking with a worm digger.I have dug up water mains and don't even look taking out dirt on both side of main i can feel it with pilot controls.I start on one side of main go down then into main and back up across top of main then back down on other side.Last week i cut a 3 phase cable inside a building laided 4" deep in concrete with a electric jackhammer and the concrete floor was 16" thick.It cost building owner $8,000 to replace it with wiring overhead in building.

 

[mflah87]

the old 580sl was alot easyer to feel it SEEMED than the 420e we have now it just feels like nothing when you are digging with it. and the fact that when we used to idle the machine down when digging around stuff hence less power so when you hit a little resistance you heard it where as the cat has pretty much the same power full throtal or at idle it doesn't help much

I'd have to agree with you. I had 580s up untill the case dealer went out and we were a few years without a close dealer and I was worried about parts. I started buying Cats after that and when it comes to feeling sometihng a 580 wins hands down.

 

[dayexco]

I don't know what you guy are talking about pilot controls they are more precise then old style controls.I dig i can feel plastic pipe.My father could feel 1/2 gas pipes with old controls.I make alot of operators scared the way i dig.I can dig all dirt from around utility with machine.I not talking with a worm digger.I have dug up water mains and don't even look taking out dirt on both side of main i can feel it with pilot controls.I start on one side of main go down then into main and back up across top of main then back down on other side.Last week i cut a 3 phase cable inside a building laided 4" deep in concrete with a electric jackhammer and the concrete floor was 16" thick.It cost building owner $8,000 to replace it with wiring overhead in building.

i would consider you too dangerous, take too many chances to be an operator for me.

 

[Squizzy246B]

I have found digging away until you hear like an underground explosion followed by a puff off smoke usually means you have found the 415 volt three phase you can also tell by the copper impregnated into the bucket teeth :crying