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Discussion Starter #1 (Edited)
So heres the rundown. Digging a ditch 8' wide 7ft deep and 140ft long. What size plywood do I need to bury on the sides of the ditch to keep the dirt off me and my guys? 2x4s or 4x4s to brace with, need enough space to lay 2 12in lines and 1 16in line.
 

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Plumber Manhattan Beach
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dude, you need a trench box. Not sure where you are, but 2 x 4's and lumber would be illegal here. say hello to OSHA

Trench Shoring Co is the company we have here.

I took their 8 hr certification class, interesting stuff about soil type and the such. Get it done right.
 

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Build yourself a cage on skids with steel top and sides wide enough for the pipes to be laid without leaving it. Have the trackhoe pull it along and lay the pipe as you go.

We made ours out of 1/4" plate and a bunch of left over 2" sch 40 steel pipe. I have used it laying sewer mains 21' deep. And no I wouldn't leave it if there was a pile of money laying 20' away from it in the ditch.
 

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Oh 2 x 4's work work like the op is saying?

That's interesting to know :)

Thanks guys

@westcoast what type of class did you take?
 

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You could call a local utility company and see where they rent shoring when they do large jobs. Most utilities will have their own, but may have to rent some on occasion.
 

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Discussion Starter #8
Down here timber shoring can be used as a alternative means. The ditch is a vertical wall ditch with concrete on each side. I have ordered a trench box and it is heading this way. They also gave me an extra to reroute a 12" return line that is leaking pretty bad in the area I have to dig. That is what is causing the cave ins. My safety man will be onsite in the morning to look the job over and let me know what he wants done
 

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We use 2 x 12 planks for vertical shoring.

http://ohioline.osu.edu/aex-fact/0391.html

We build square frames and put them in the trench. Then we use vertical 2 x 12 planks. We to not nail the planks to the frames because we want to drive the planks down as we dig deeper.

We always use shoring when we are over 5 feet deep. As in the diagram in this link, the pressure at 5 feet could be 250 pounds per square foot. That is not a lot of pressure and 3/4 inch plywood would be sufficient. If you had 250 pounds per square inch then you would have a lot of pressure.

I take that back. If you already know a water main is leaking go with the 2 x 12 planks.
 

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dude, you need a trench box. Not sure where you are, but 2 x 4's and lumber would be illegal here. say hello to OSHA

Trench Shoring Co is the company we have here.

I took their 8 hr certification class, interesting stuff about soil type and the such. Get it done right.
I'm taking the class next weekend. You don't want to be in that hole with a shady setup, you could kill someone.
 

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Okay, took the class, passed the test (it's open book mind you) got a perfect score while some didn't.

Some of you guys are suggesting some real shady stuff.

The class starts off with the instructor sharing pics and stories of jobs that went wrong. One included a crew using some big auger bits drilling a hole about 24" wide or so. Crew breaks for lunch, bit gets pulled out of hole. Inspector is on site checking things out. When crew returns, bit goes back in the hole. Suddenly, auger pushes out blood, and fabric. Turns out the inspector fell in the hole while crew is on break.

The long and the short, if you don't know OSHA standards on this stuff, you can get heavily fined, and kill people. The amount of pressure you're dealing with is serious business. You can't just use 2x4 and ply. There are specific techniques, sizes, and material that have to be used.

I would never work for some of you after reading what I have in this thread.
 

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So heres the rundown. Digging a ditch 8' wide 7ft deep and 140ft long. What size plywood do I need to bury on the sides of the ditch to keep the dirt off me and my guys? 2x4s or 4x4s to brace with, need enough space to lay 2 12in lines and 1 16in line.
Don't you dare put anyone in a hole until you get certified. You need 8 x 8 cross braces made of mixed oak for type C soil or 6" x 6" of Douglas fir for type C, vertically spaced at 5'. Wales need to be 10" x 12" for mixed oak and 10" x 10" for Douglas fir, also vertically spaced at 5' Uprights spaced close are 2" x 6" for mixed oak, 3" x 6" for Douglas fir.

There is a lot more info you need before you do this.
 

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Discussion Starter #14
Don't you dare put anyone in a hole until you get certified. You need 8 x 8 cross braces made of mixed oak for type C soil or 6" x 6" of Douglas fir for type C, vertically spaced at 5'. Wales need to be 10" x 12" for mixed oak and 10" x 10" for Douglas fir, also vertically spaced at 5' Uprights spaced close are 2" x 6" for mixed oak, 3" x 6" for Douglas fir.

There is a lot more info you need before you do this.
Thanks for the advice, but the the lines are layed and the concrete is poured. Been setting up for about 3 weeks now. I ended up saw cutting 6ft more of concrete on each side of the 8ft ditch line. Which made the ditch 20ft wide. We reshot our elevation and we ended up only about 6ft deep. I stair stepped the ditch walls back per OSHA guidelines. At 6ft deep you have to shore 6ft back on each side. We also had a trench box on site just incase our saftey man wanted us in it. He looked over the ditch line BEFORE we got in it.
 

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Build yourself a cage on skids with steel top and sides wide enough for the pipes to be laid without leaving it. Have the trackhoe pull it along and lay the pipe as you go.

We made ours out of 1/4" plate and a bunch of left over 2" sch 40 steel pipe. I have used it laying sewer mains 21' deep. And no I wouldn't leave it if there was a pile of money laying 20' away from it in the ditch.
Just because it's made of metal doesn't mean it doesn't have to be engineered. What if your trench box collapsed and someone died? What qualifications do you have to design one? Not trying to bust your balls but give you something to think about. I built one in guam with 1/2 steel plate and 6x6 square tubing. No engineer would sign there name on the design so we put it on it's side and put 10 tons(crane cert weight) on it. After they saw that, getting the design blessed was easy.
 
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