How to dig safely next to basement wall

toddmanqa · 03-13-2012, 10:10 AM

I need to install/replace the drain tile around my basement walls.

I've read about how to safely dig:

1. Don't stack/stage excavated material near the hole.

2. Have a ladder to get out of the hole

3. Don't allow heavy equipment near the sides of the hole / no vibrations

What is the an economical but safe way to keep the hole wall from collapsing in?

I can't afford to pay for heavy equipment to rent a trench shield.

What about the use of trench jacks with plywood?

Also, If I'm going to be applying a water proofing material to the sides of the basement walls, how do I do that with the trench jacks in the way? Water proof a small section, then move the trench jack to that location, then water proof the rest?

Thanks!

Willie T · 03-13-2012, 10:16 AM

Dig at a 45 degree slope. ie: If you are digging down 7 feet, then keep the top of the slope 7 feet from the wall.

Do only about 10 foot sections at a time... fill in, and do another 10 feet.

Daniel Holzman · 03-13-2012, 10:20 AM

Exactly how deep a trench are you planning, and how wide? I realize this is your own house, and from the sounds of it you are financially pressed, but in the commercial world, any trench 3 or more feet deep is OSHA regulated. People can and do routinely die in trench collapses due to improper use of trench supports, failure to use trench supports, or greater soil pressure than anticipated. The safest way to do trench work is to slope the sides of the trench back at a safe angle, which is typically flatter than 45 degrees. Of course, this means more digging, and sometimes it is not possible to slope the trench back, hence the use of trench support technology such as sheeting, tiebacks, trench boxes etc.

The use of trench support equipment is normally way beyond DIY stuff, certainly designing such a system over the internet is irresponsible and potentially fatal to you. The need for support depends entirely on the geometry of the trench, the soil conditions, and the water table. If your trench would trigger OSHA controls, regardless of whether you are actually subject to such controls due to this being your house, you need to understand the safety procedures at a minimum. Unfortunately they are complex and lengthy.

conclusion: If your project is dangerous enough to warrant trench support, this is probably not a good DIY project.

hyunelan2 · 03-13-2012, 10:39 AM

Quote:

Originally Posted by Daniel Holzman

The safest way to do trench work is to slope the sides of the trench back at a safe angle, which is typically flatter than 45 degrees. Of course, this means more digging, and sometimes it is not possible to slope the trench back, hence the use of trench support technology such as sheeting, tiebacks, trench boxes etc.

The angle of repose of earth is 30-45 degrees, depending on composition. So you are looking at a 30 degree slope for safety. That means a 7' deep trench needs to be dug on a slope up to about 12' off the wall. That's about 15 cubic yards of dirt to move for every 10 feet of wall. A lot to move DIY.

woodworkbykirk · 03-13-2012, 11:09 PM

its perfectly safe to use a mini excavator to dig a trench along side the foundation wall.. you just need a operator that isnt overly aggressive with the machine and the foundation doesnt have any cracks in it

we specialize in additions on homes which requires putting footings and foundations in the ground attached to the existing. to do this we call a excavation company and they use the mini for digging around the existing.. if foundation for a new home they just send the big scoop