Electric trench help

tbaero153 · Mar 17, 2016

Hello all,
I have a electrical contractor that I work with on a lot of jobs for some of the same gc's.
He has asked me if I would give him a price to excavate a trench for underground service from pole to house. He says it is about 150' and I would have to dig down 30" max. He is using sch. 40 conduit so I won't have to use sand in trench. I won't have to remove any excess fill off site, just backfill and rough grade out after. The job is about 1/2 hour ride out from the shop. I'll pull my mini out to and from with my I ton and a small trailer. Any thoughts on what this job is worth? Thank you for your input.

movindirt · Mar 17, 2016

Well, for starts your in CT, so I'm assuming you'll probably be in some rock? Around here, in clean clay with pretty much no rock that would take a couple hours or so. With a 3 ton machine here that would probably be about a $350 job. If he is going to glue the conduit up as soon as you dig it so you can backfill right away you could add a couple of hours on for backfill. Probably around $500 total, maybe little more or little less depending on site conditions. Again, prices vary by region, what could be high for me could be lowballing it for you. What are you billing your machine out per hour? What size mini is it? You're going to dig quite a bit faster with a 5 ton then a 2.5 ton..

tbaero153 · Mar 18, 2016

Thank you for the response movindirt! The area is pretty much all sandy since it is close to the river, done work in the area in the past and that is what i remember.
My machine is around a 5 ton. They will glue it and install conduit in trench pretty much right behind me. As soon as the inspector gives it his blessing, i will back fill
the trench and rough grade out the area. Im estimating a whole day because the inspector will not pin point a specific time to show up. Could be 10 am up till 1pm?
I quoted him 1100.00 to do the job and he called back and asked if I was sure about the price because the owner had gotten a couple other prices previous and they were up
around 2K. So I was concerned if they were just trying to whack the guy or was I bidding way to cheap? Any ways he has the job and I will do it next week, he is going
to carry 1500.00 for my part, so I guess it works out good. I own my machine already if that helps. Thank you.

RonG · Mar 18, 2016

You may have to backfill twice if you have to put warning tape in the trench which may take a little more time.It won't hurt to have the tape on the jobsite ahead of time.Ron G

tbaero153 · Mar 18, 2016

Thank you Ron. I will make sure the electrician has the tape for us to put in. Should i keep tape about 1 foot below finish grade?

RonG · Mar 18, 2016

I generally figure on 1' above the wire doing direct burial,the electrician will know what the code is in your town.Ron G

tbaero153 · Mar 18, 2016

Thanks Ron,
In your opinion what do you think that little job is worth?

RonG · Mar 18, 2016

If the machine is already on site maybe $1500.00 or so,otherwise factor in your mobilizing.Sounds like good digging.Ron G

Bliz · Mar 19, 2016

150' long x 2.5' deep x 3.5' wide = 1312.5 cu.ft. /27cu.ft./CY = 48.6CY
With a 5 ton machine you should easily be able to dig 15cy/hr.
50cy/15cy/hr = 3hr.s, 20 min.s or 4 hours.
4 hours x $95.00/hr = $380.00 to dig
4 hours x $95.00/hr = $380.00 to backfill & grade
1 hour x $125.00 = $125.00 mobilization
$215.00 waiting around, profit & overhead
Total: $1,100.00

In normal digging you should be fine at your quote.

tbaero153 · Mar 20, 2016

Thanks Bliz, sounds good, I'll use a 12" trench bucket to dig so I should be able to knock it out rather fast. I'll probably spend more time waiting on the electrician and inspector than dig and backfill.

RBMcCloskey · Mar 20, 2016

I would make sure about the need for sand backfill, in most cases the sand is placed as a warning a buried conduit it present.

tbaero153 · Mar 29, 2016

Well did the job today, all in all I think it went well. Took 1.5 hrs to dig with a 6 ton mini. All sand but many roots from close pine trees. Turned out the trench was 250' long, not the 150' I thought he told me. Used a 12" bucket and went down 30". They laid the conduit in right behind me. The inspector showed up at 10:30 gave it his ok and pushed in fill to 12" below top and laid warning tape, then finished filling it. Just ran a rough grade over area, loaded up and headed out. I was back at the shop by 1:00, I had worked in the area before so I knew the soil was good. I just wish all the jobs i do could be like this. Every other town you work in has a different type of soil. Every thing from gumbo clay, red hard pan, to ledge and rock. Its good to get lucky once in a while.

movindirt · Mar 29, 2016

tbaero153 said:
Well did the job today, all in all I think it went well. Took 1.5 hrs to dig with a 6 ton mini. All sand but many roots from close pine trees. Turned out the trench was 250' long, not the 150' I thought he told me. Used a 12" bucket and went down 30". They laid the conduit in right behind me. The inspector showed up at 10:30 gave it his ok and pushed in fill to 12" below top and laid warning tape, then finished filling it. Just ran a rough grade over area, loaded up and headed out. I was back at the shop by 1:00, I had worked in the area before so I knew the soil was good. I just wish all the jobs i do could be like this. Every other town you work in has a different type of soil. Every thing from gumbo clay, red hard pan, to ledge and rock. Its good to get lucky once in a while.

Glad it all went well for you!! Sounds like it turned out to be a profitable job!

CM1995 · Mar 30, 2016

tbaero153 said:
I just wish all the jobs i do could be like this. Every other town you work in has a different type of soil. Every thing from gumbo clay, red hard pan, to ledge and rock. Its good to get lucky once in a while.

Good deal, it's nice to make some $$ every now and then.

Your digging sounds a lot like ours. One better know their soil types as it can change drastically in a short distance.

Willie B · Apr 2, 2016

I take exception with 30" ditch, and no sand. I insist the top of the pipe be 36" down from grade. The pipe is nearly 4" and it needs 6" of sand under it. I dig, or ask for a 4' deep ditch. Only once have I got deeper than I asked for. Usually I am pleased to have the 46".

PVC has a big shrink habit, the wider the temperature range, the more tension when it shrinks. With 100 degrees temperature range there is the risk of a joint popping loose. 3 feet down, temperatures change maybe 50 degrees F. The aluminum URD or USE cable in it is notorious for corroding if even a small nick in the jacket. Treat it like a newborn baby, you'll never have to touch it again.

RonG · Apr 2, 2016

I think the depth of the trench generally depends on what goes in it and is sometimes dictated by zoning etc. but the power company generally wants to be on the bottom of the trench and I think direct burial will be deeper than conduit and direct burial will have more bedding than conduit.Direct burial also uses different wire than conduit.Whatever goes in the same trench (telephone etc.) will have there own rules but I always plan on the power being on the bottom.As a rule there needs to be 1' of cover over the top service then warning tape and then backfilll to surface grade.YMMV.Ron G

CM1995 · Apr 2, 2016

This is a primary power installation we did at a fast food rest. last month.

APCO spec's for underground primary service, 3 phase:

2 runs of 5" SCH 40 conduit 42" deep from finished grade to top of conduit, no stone bedding or backfill required, at the discretion of the owner/GC.

Conduits coming out of the pull box.

Bedding not required but I like to do it for support.

1' or so of backfill and warning tape.

Conduit swept up into the 3 phase transformer pad. Now here's the deal, we can install the 5" primary all day long but we can't run the secondary to the building because we don't have a sparky license.:beatsme

tbaero153 · Apr 2, 2016

Thanks willie, the local code is24" to top of pipe down from grade. The site was pure dead sand. Wasn't a single stone or rock. That being said sch 40 is pretty stout pipe. We are not required to back fill with sand even in a site with hard pan. We always bed gas, water pipe in sand but electrical almost never.

Willie B · Apr 2, 2016

I'm not talking about code. I'm talking about forever. I installed my first underground 47 years ago. I'm very proud that none of the few dozen I have replaced were my original installs. Two hours extra care at install will translate to trouble free forever. It's expensive to install underground. The second time, it's catastrophic. Code depth will vary with circumstances. It is a minimum, and doesn't concern itself with durability. Code is about safety. Buried deep, bedded in 1"minus, sweeping with schedule 80, or galvanized long radius sweeps will pay in the dividend of never having to dig again.

RonG · Apr 3, 2016

You can do my work Willie!Ron G

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