Sewer line trench - roots ok to cut?

[David McMahon]

Hello Tree People!

Needing some helpful advice. I've got a couple of large Douglas Firs (48" and 36") that I need to trench between for a sewer line. The trees are about 16' apart at their edges.

The trench is probably going to be 24" W x 24"-30" D.

The contractor says he'll avoid cutting anything 4" or larger but anything else is game. Is this a fair approach or will I be looking at tree weakening or death some years down the road?

Anything else I should ask the contractor to pay attention to while digging here?

 

[TheJollyLogger]

What is his intended path? How wide are the stairs, for scale? Exactly how does he intend to "avoid" cutting anything 4" or more? After he finds it with his backhoe? Got a few questions...

 

[GenXer]

How big of a pipe is he putting in? I'm sure he could probably rent a 12" bucket.

 

[TheJollyLogger]

With that much fall I'm having a hard time believing that is the only A to B path, and if the first line failed, more than likely due to root intrusion, not sure I would want to repeat.

 

[TheJollyLogger]

To the OP, yes, you are right to be concerned with your contractors plan. More pics and an idea of his planned trench would be helpful

 

[David McMahon]

What is his intended path? How wide are the stairs, for scale? Exactly how does he intend to "avoid" cutting anything 4" or more? After he finds it with his backhoe? Got a few questions...

This is roughly the expected path diagonally across this view, under the steps, but the contractor says he will adjust as needed during the dig. The stairs are about 30"-36" at the cross point. The step path is widens as it goes up the hill.
I should have mentioned in the original post that the planned dig will be all by hand with no machinery due to the challenging slope and many obstacles.

How big of a pipe is he putting in? I'm sure he could probably rent a 12" bucket.

This will be a 4" sewer drain and a water run for a spigot. Electrical will also be in this trench.

 

[Heavyopp]

Is the view we are looking at from your front door? What is the building below, where the arrow is pointed?

I dig for a living -- that job wouldn't be fun or cheap by hand or machine.

 

[David McMahon]

Is the view we are looking at from your front door? What is the building below, where the arrow is pointed?

I dig for a living -- that job wouldn't be fun or cheap by hand or machine.

That view is just from a sitting area that the steps lead to. The building below is the main house. To the right of the photo is an RV parking spot where services will be run.

Yes it'll be a sucky dig and expensive.

But I'm really only concerned with the tree roots that I'll be passing through for this route. Just looking for any advice besides "don't cut the 4" roots" I can pass on to the contractor so as to avoid any tree problems in the future.

 

[Del_]

Either hand dig the trench or remove the trees as the backhoe is going to result in their death.

So figure the cost in of removing the trees when backhoe digging.

Hand digging or boring would be cheaper.

 

[Section VIII]

Residential electric and water lines (supply or sewer) are not recommended to go under a driveway or other path where vehicles may travel over.

Mostly due to cost of any future repairs. Is the contractor going to reinforce the area under the driveway?

 

[David McMahon]

Thanks all for the replies. It sounds like the plan to hand dig is the right way to go. My only question for the arborists is: Is there anything besides 'avoiding 4"+ roots' to consider or should we be ok as long as we avoid the 4"+ roots?

I'm wondering if there is anything relative to the distance to the trunk that might override that simple 4"+ recommendation or is that good enough? What are the other risks in general here with a tree of this size?

Thanks.

 

[TheJollyLogger]

He'll yeah it's a risk. You are going to be destroying a very substantial percentage of those trees' feeder roots. If you are looking for odds, I'd give them a 50% chance of survival. In addition to the root damage, there will be a lot of soil compaction and from the spoil and foot traffic. If there is any way to go around, I would.

 

[5155]

If the roots get trimmed you may consider trimming the growth. If needed now is the time. Nice looking yard trees, while standing.

Arborists, is aspiration the term I am thinking?

 

[David McMahon]

Just to close this out here. The trench was dug only about 18" deep between those trees and there were only a few smaller roots (no larger than 1-1.5" that they had to cut. I'm thinking it's going to be fine.

Thanks all for the comments and suggestions!

 

[TheJollyLogger]

Just to close this out here. The trench was dug only about 18" deep between those trees and there were only a few smaller roots (no larger than 1-1.5" that they had to cut. I'm thinking it's going to be fine.

Thanks all for the comments and suggestions!

Thanks for the update, we often get left hanging on how it turned out! Glad it went well.

 

[ATH]

I'm really late to the party here, going through some old threads on a slow Sunday afternoon...

Was horizontal boring ever discussed as an option? It's not cheap, but neither is removing trees (let along loss of value from loss of trees...). Neither is replacing the steps.

For example, I was involved with a multi-million dollar project where I was consulting on reducing compaction to protect the trees. We had a good visit and came up with some workable plans. Then, kinda as a "off topic" remark (the guy who said it didn't seem to think it was related to the concerns we discussed) someone said "and the trenches for water and sewer will run right here" (pretty close to some big trees). They said that would be too expensive...then somebody checked - $40,000. They went that way, that's a pretty small % of a project of that scale. And its not like it was added $40K. Take several thousand off of the original excavation plan... But the trees will be almost unimpacted (I'm sure they cut a few roots boring, but probably not many because they would have gone below 3' frost line and this was a wet site, so not many roots going that deep)

 

[David McMahon]

I'm really late to the party here, going through some old threads on a slow Sunday afternoon...

Was horizontal boring ever discussed as an option? It's not cheap, but neither is removing trees (let along loss of value from loss of trees...). Neither is replacing the steps.

For example, I was involved with a multi-million dollar project where I was consulting on reducing compaction to protect the trees. We had a good visit and came up with some workable plans. Then, kinda as a "off topic" remark (the guy who said it didn't seem to think it was related to the concerns we discussed) someone said "and the trenches for water and sewer will run right here" (pretty close to some big trees). They said that would be too expensive...then somebody checked - $40,000. They went that way, that's a pretty small % of a project of that scale. And its not like it was added $40K. Take several thousand off of the original excavation plan... But the trees will be almost unimpacted (I'm sure they cut a few roots boring, but probably not many because they would have gone below 3' frost line and this was a wet site, so not many roots going that deep)

I had a boring company come out to take a look at my rocky hilly twisty path and they noped out of there pretty quick. It would have cost a fortune anyway vs. hand-digging it. Turned out to be 100' for $11k. I do have to fix some landscaping, but that will be fairly minimal cost-wise.

I'm sure on some much bigger budget projects with more forgiving straight-line paths boring would make sense though. I wish I had a multi-million dollar project to have that choice!

 

[pdqdl]

Is this just a sewer line repair where you decided to add electrical & water line?

Re-lining a sewer is possible, but you'll be back to boring or trenching with the extra features added.

https://www.t3liningsupply.com/blog...ptions-pros-and-cons-of-pipe-relining-methods
https://www.nuflowmidwest.com/process-benefits/

 

[ATH]

I had a boring company come out to take a look at my rocky hilly twisty path and they noped out of there pretty quick. It would have cost a fortune anyway vs. hand-digging it. Turned out to be 100' for $11k. I do have to fix some landscaping, but that will be fairly minimal cost-wise.

I'm sure on some much bigger budget projects with more forgiving straight-line paths boring would make sense though. I wish I had a multi-million dollar project to have that choice!

Understand that it wasn't possible here....but I wonder how much that bore would have cost IF it were possible? The $40K one was for pretty big lines and a lot longer. If I had to guess, I would have started in the $10k neighborhood...but that may be way off!