BIG Trencher vs Cat 308 for digging through "forested" area

[Ebenbayer]

Hi All,

New member here!

I have done some searching and read various posts here on trenchers vs. excavators. Most seem to be walk behind trenchers and the general consensus seems to be that if you are going to roots or rocks, go w/ the excavator.

With that said, I have about 800 ft of trench I would like to put in; The soil ranges from relatively soft loam and clay, through loose shale on the end of the run. The path goes right through a relatively open forest (e.g. I can get through w/ out cutting trees, but they are some BIG old pines).

I'm trying to decide between a skid steer w/ Bradco 625 Trencher Attachment or a CAT 308 for this job. I'm wondering if the larger trencher will have the muscle to get through most of this job much faster or if I should plan to take my time and dig dig dig.

thoughts?

Thanks!

E

 

[RickP]

I used a skid steer mounted trencher to go about 1000' feet through a pine forest. It should be plenty for what you need to do.

How deep are you going? For my electric service, the local poco went about 4' deep through the forest and they used a Vermeer M470 articulated trencher. But I think it would be overkill for a 2' deep trench.

 

[WhiffySpark]

308 won't take that much longer

 

[wsettle]

I live in a forested area as well and the local electric service requires me to bury 2 3" conduits in case one gets damaged by earth movement or more likely tree root damage. I don't know what the "safe" distance is from a tree for underground power but I would go with the trackhoe to also pull up any tree roots that may be close enough to potentially migrate through your underground trench. Just thinking out loud as I've had roots tear up underground power in a previous residence.

 

[Ebenbayer]

Hey Guys,

Thanks both for the feedback!

Sounds like the trencher might be able to do it.

For reference, i'm running a 4" water line in this (for a micro-hydro system). 20 ft sections of PVC; (they are already glued and in place and in service, I will cut into prob. 100 ft sections and then lower into the trench.

I was also thinking I might get a smoother trench w/ the trencher which is important since I don't want the PVC to break as the ground settles.

I was planning to go either 4 ft, or if I can't, go a bit shallower and then lay 1" rigid board insulation on top before back filling.

The pipe is going to be flowing at ~ 10-30 GPM, so i'm not obsessed with getting beneath frost line (but surface exposure it will freeze at ~0 F, learned the hard way, 700 ft of broken pipe!!)

only other reason I can see going excavator route is maybe to get a bigger cut which I can get inside for glueing, etc...

E

 

[Milton Shaw]

A trencher will disturb the ground and make a whole lot less mess than an excavator. The ditch will be a whole lot more even on the bottom and a lot easier to get the pipe laid flat then dug with an excavator. Most trenchers will go through roots without a lot of problems and tear up ground a lot less than backhoe digging will. I would recommend covering the pvc with sand then the insulation or you would end up with a lot of voids around the pipe.

 

[Ebenbayer]

Hi Milton,

thank you for the feedback.

is there any need to level the trench w/ sand on the bottom side too, or just fill in? Whats the downside to having a void space (especially if I got the trench method and lay insulating board on top of the pipe)?

I"m going to give it a go on Monday. i'll report back.

Eben

 

[Charles (in GA)]

Please go to the user control panel and edit your profile with a location. State, city, whatever you like, but give us some idea of the area, climate, etc.

Charles

 

[BADSIX]

how wide is the trench that the trencher digs
Jay D.

 

[rancherbill]

Use the trencher.

As a rookie, it is hard to dig a smooth bottom trench with an excavator. It is not as easy as it looks. There is a big difference in the quality of the trench necessary for pipe versus wire.

 

[wnstwolf]

I am with Rancher Bill. I had to go about 500' to a pond for Geo-Thermal system. I "borrowed" the excavator that was on site on a day that followed a 3" rain the previous few days. No one was around as it was too wet and muddy to wok. First mistake was to ignore why the professionals were not on site using equipment. So as I had the day off from work I dug the trench..

Excavator on soft clay digging a ditch with a rookie: Priceless

Took the dozer and a lot of pressuring washing the mud off to get things back to normal. And a few cases of beer to the owners! Good luck if you go excavator route once you get the hang of it you will want to dig holes everywhere!

 

[rancherbill]

Excavator on soft clay digging a ditch with a rookie: Priceless

It's amazing how they can wiggle themselves into the ground.

 

[A_Pmech]

The trencher will handle roots and rocks better than the excavator. If you expect to encounter rock, make sure the chain is equipped with rock points or you'll tear up the chain.

 

[theoldwizard1]

For reference, i'm running a 4" water line in this (for a micro-hydro system). 20 ft sections of PVC; (they are already glued and in place and in service, I will cut into prob. 100 ft sections and then lower into the trench.

Please follow up with pictures. I am interested to see if you can actually put those 100' section in the trench without breaking them !

 

[Ebenbayer]

I'm going to go w/ the trencher!

I'll definitely post some photo's after I finish.

Had plenty of rookie "fun" on excavators digging the reservoir and experiencing just how slippery clay can get on phase I of this project...

The harder part was driving the Cat 312 down the hill; ~400 vertical feet, with lots of switch backs. It took a lot of bucket inching to get it back up last time. (another reason I like the skid steer option, i'm pretty sure I can drive it back up)

The water lines i'm burying are currently running a hydro-generator right now; 36 GPM @ 65 PSI putting out about .5KW; its in the 20's so no risk of freezing (yet!)

wish me luck!

 

[NC4AB]

+1 on the trencher. Had to put in 600 feet of water line, rented a 45 hp or so Vermeer ride on with about a 6 foot bar on it from the local Hertz dealer on Friday afternoon, took about 3 hrs to go through a heavily wooded area, the chain on the trencher was rated to cut asphalt and it made short work of the basketball sized rocks in the ground. Had a 4 way blade on the front that was great to backfill the trench.

Only suggestion is to start at the bottom and work your way up. Whole lot easier to back down than it is to back up an incline if you start spinning or hit a wet spot.

Andy

 

[Bighead38]

I would of went with the excavator but then again I am an operator.

 

[BADSIX]

+2 on the excavator, I'm still not sure how wide the trench is that your going to dig is going to be. but I had a trencher dig a 3FT.deep x 200' long for under ground power service. the trench was 4" wide so the 3" pipe was a snug fit and if the trench isn't perfectly straight your going to have problems. also the trencher that was used left a large mound of dirt on both sides of the trench, you couldn't even look at the trench with out some of the dirt going back in the trench. now comes time to put the pipe in the trench. 100' of pipe is not going to be easy to handle its going to take several people and your going to have dirt back in your trench. now if your trench is 4' as you say and you need to put the insulation on top or need to do anything in that trench. you won't be able to reach past about 30" unless you have arms like an ape. plus theirs that mound of dirt you have to contend with. I've done this job a few times and would never use a trencher if I had to go more than 2'. use the excavator and make a wide trench you can get into and lay your pipe and insulation with no problems. if you can drive a car you should be able to figure out how to run the excavator in short order. it won't be faster but easier in the long run.
Jay D.

 

[K2Orion]

As an operator who has laid sanitary, storm, and water line I vote for the excavator.
The trencher will go through almost anything. But with hoe, you can work around or through whatever you encounter. And backfilling will be a gentler, more precise process with the hoe.
I suggest digging your trench and making your grade with clean rock. Then laying your pipe. Then covering with more clean rock. Then backfill with dirt or whatever came out of the ditch. Compact with the bucket as you backfill.

 

[rancherbill]

I'm going to go w/ the trencher!

I'll definitely post some photo's after I finish.

Had plenty of rookie "fun" on excavators digging the reservoir and experiencing just how slippery clay can get on phase I of this project...

The harder part was driving the Cat 312 down the hill; ~400 vertical feet, with lots of switch backs. It took a lot of bucket inching to get it back up last time. (another reason I like the skid steer option, i'm pretty sure I can drive it back up)

The water lines i'm burying are currently running a hydro-generator right now; 36 GPM @ 65 PSI putting out about .5KW; its in the 20's so no risk of freezing (yet!)

wish me luck!

LUCK!!!!

I'd love to see the generator and the installation of the pipe. Plese posts ome pics as you go.

 

[TonkaJoe]

As an operator who has laid sanitary, storm, and water line I vote for the excavator.
The trencher will go through almost anything. But with hoe, you can work around or through whatever you encounter. And backfilling will be a gentler, more precise process with the hoe.
I suggest digging your trench and making your grade with clean rock. Then laying your pipe. Then covering with more clean rock. Then backfill with dirt or whatever came out of the ditch. Compact with the bucket as you backfill.

Coming from another Operating Engineer who has a number of years of experience in mining and road/water/sewer construction. That excavator will do more than what you need without a problem.. plenty of mobility and like what was previously stated you'll be able to back fill with B and A grade aggregate or dirt without touching a shovel.. if more compaction is needed in your work area than you can sustain with a bucket, a simple plate tamper attachment can assist you.

 

[Ebenbayer]

Okay Okay-- now you folks are talking me back into the Excavator. :

I'm no expert by any means, but have enough hours in the seat running some of the mini's (mostly the 308 and 312's I can rent in my area) and can see the advantage of the flexibility it gives.

I'm still a little concerned about getting the excavator down there this time of year (was hard in July last time, now there is few inches of snow).

I'm going to walk the route again this afternoon and I guess make a game time decision!

Attached are a few pic's of the system set up from earlier in the year--
*few shots of the 4" PVC that needs to be buried
*Shot of "old" pond I dug-- i've added another 600' ft of 2" black poly to a higher point in the stream for more pressure (also planning to bury...)
*shot of my YOTA with the "generator" house on the back; driving it down to bottom fully assembled...

Thanks for all the feedback!

 

[Heavymetalmechanic]

That is a pretty cool setup. Both the excavator and the chain trencher have plus/minus points.

Trencher +:
-consistent trench depth and width.
-if outfitted with ripper teeth and good blades it will cut through pretty much anything.
- user friendly for beginner operators.
- leaves a pile on each side that's easy to use to backfill.
Trencher -:
- can leave a pile alongside the trench that can shift back in.
- if not in good condition then it will struggle with rocks/roots.
- trench will be narrow, if ground is soft or wet it may collapse.
- less common at rental shops
Excavator +:
- easy to deal with problem rocks/roots.
- can make a trench of any width.
- can be used to complete other tasks in your yard/project.
- availible at most rental companies.
- can be used to lay your pipe into the trench.
Excavator -:
- less user friendly for beginners (but you may learn quick).
- May be a wider unit then a trencher, may not fit in some areas.
- May be more expensive to rent

Hope that helps. I worked in a rental shop for 5 years, and work for a shop that services chain trenchers now (DitchWitch). PM if you have any particular questions.

 

[TonkaJoe]

If you could get your hands on a newer style CAT 312 excavator with a Zero degree tail swing and push blade you'd have plenty of clearance trenching through those trees by the looks of it. There are also some good points to consider in the above post.

 

[galute]

How deep is that ground frozen? If it's froze very deep that could be some tough digging for a mini ex.

 

[WhiffySpark]

A 308 is an 8 ton "mini" ex. Hardly underpowered or small. You'd have to have it delivered as well it's to heavy for a traditional bobcat trailer

 

[Ebenbayer]

Hi All!

So after 6 hours of machine time today I have about 800 ft of 12-36" deep trench. I got better as I went along, but some of my earlier work is a little shallow w/ caving walls. Guess I'll be digging them out by hand.

I really enjoyed the flexibility of the skid-steer and trencher, though I think the 312 Prob would have gone just as fast w/ a bigger cut.

Overall, I'm happy to have made some progress. I'll post photo's a bit later

Tomorrow I will do the last 200' ft or so, then figure out how to drive the unit back up the hill!

 

[Ebenbayer]

Few Pics attached!

Pipe is connected and full of water again next to trench (needed to get power back on).

I'm planning to drop into the trench and cover Friday.

Its been really wet (Like 1-2" inches of run-off predicted next 48 hours) and I'm wondering what the best suggestions are to get some of the slump off the bottom. Just go over it w/ the trenching shovel?

 

[Ebenbayer]

With Photos.

 

[Rentawrench]

You should run a tracer wire on top of the pipe so when you get older / new owner can find the pipe run.

 

[hockey88fan]

Okay Okay-- now you folks are talking me back into the Excavator. :



I'm no expert by any means, but have enough hours in the seat running some of the mini's (mostly the 308 and 312's I can rent in my area) and can see the advantage of the flexibility it gives.



I'm still a little concerned about getting the excavator down there this time of year (was hard in July last time, now there is few inches of snow).



I'm going to walk the route again this afternoon and I guess make a game time decision!



Attached are a few pic's of the system set up from earlier in the year--

*few shots of the 4" PVC that needs to be buried

*Shot of "old" pond I dug-- i've added another 600' ft of 2" black poly to a higher point in the stream for more pressure (also planning to bury...)

*shot of my YOTA with the "generator" house on the back; driving it down to bottom fully assembled...



Thanks for all the feedback!

Look like a '92 Yota, I have one as well, nice truck!

 

[BADSIX]

yep, getting that pipe in the trench might not be much fun. you'll be a pro with a hand shovel when you get finished.
Jay D.

 

[Ebenbayer]

Okay. Mostly Done. Trench really collapsed in during rains. I am now very familiar with "trench shovel", "re" dug many sections.

Heres a few final pic's for all !

If I had to do it again ( and will for Phase III) I would likely go skid steer + trencher for ONLY trenching if it was 1) Dryer 2) did not have snow/slush on ground 3) was not going to rain the following few days.

Since phase III will involve building a dam, I think i'll trench the smaller 600' ft spur w/ the 308 and then can have a true comparison.

Thanks for all the help and suggestions!

Eben

 

[RickP]

Nice job - that looks like a lot of work... especially with wet conditions. That skid steer is the exact setup I used and it worked really well. I'll be interested to hear how you like the mini-ex for the spur line.

 

[toplessHO]

did the trencher have a crummer shoe attached? it will do a good job of pulling most of the loose material out as you go.

 

[theoldwizard1]

Heres a few final pic's for all !

What are we looking at in the first picture ? The pipe obviously is making a transition from 4" PVC to ... ? Is that a clean out there ?

If I had to do it again ( and will for Phase III) I would likely go skid steer + trencher for ONLY trenching if it was 1) Dryer 2) did not have snow/slush on ground 3) was not going to rain the following few days.

Live and learn !

Any issues with roots ?

Any issues moving the pipe into the trench ?

 

[NUTTSGT]

What are we looking at in the first picture ? The pipe obviously is making a transition from 4" PVC to ... ? Is that a clean out there ?

I was curious about that also and I see a water stream coming out.

Looks like a muddy damn mess, no offense, but better you than me.

 

[galute]

I must be missing something. Sure seems like a big expense for only 525 watts.

 

[Ebenbayer]

Okay-- so to answer a few questions/comments:

*line goes from 2" PE to 4" PVC at that point, will be burying this junction later in the week and leaving a manifold extension point (in case I want to add a second 2" PE section).

The PE line is another 600' ft going further up the hill to the top of my stream, where a screened inlet feeds water into the pipe. Its already under a bit of pressure at this transition point.

*it was a muddy mess! I had the crumb shoe which helped a lot. biggest issue was cave in's while I was away for XMAS and got so much rain.

Getting the pipe in the trench wasn't terrible. I had already glued the 4" PVC into a 1000 ft length (the original section from last year, above ground). So I cut that into manageable lengths that I could pull by hand (60-120 ft) and dragged them, re-glued, and then gently laid in trench. I then pressure tested and used weight of filling pipe to let it all settle down.

I had one joint blow, which was a huge PITA as pulling 200' ft of pipe "up" to make a new connection is not fun

Regarding power out put. For us, we live off grid. At this time of year we can produce about 750 watts continuously from falling water, which adds up. This works out to about 500 kWh-month! Prob. smaller than your average home consumption, but sufficient. The other benefit is our solar panels make ZILCH for days in the rainy and snowy winters, normally you would compensate by having a big (read: expensive) battery bank, so this lets me keep that component small. ON sunny days during wet months we have way to much power-- use it to run the hot water heater etc.

Next year i'm planning a dam to build a big "water battery" which will store ~30 days power

I still need to backfill. For the areas that are close to surface I was thinking of backfilling with insulation scraps to add more freeze protection (essentially laying 6" or 4" foam strips on top of pipe before filling). Think this buys much?

Thanks for all the suggestions!!

 

[justin1795]

just had my wire put in. had a operator doing grading and other work so I asked him to dig me a trench. he had a deere 35 I think excavator. I would of been happy him digging it and leaving but he would dig out about 5-6 foot at a time I would lay the wire in and he would fill it up and back up and do another 5-6 foot. went very fast. I couldn't keep up and he jumped off the excavator to help a few times.