Excavation Safety – Allowable Surcharge Loads
There is a special area around an excavation that is sacred. It is referred to as the “Adjacent Areaâ€. It can be defined as the area going out from the lip (or edge) of the excavation a distance that is equal to the depth of the excavation.
This area is sacred because we must respect and manage any structures or weights in this area. The idea isn’t to prohibit anything from this area, but just to manage it. For example, when using a manufactured protective system such as a shoring system or a trench shield, we must consult the manufacturer’s tabulate data to see what the weight limits are in place in that sacred area.
In the excavation safety industry, the most weight allowed by some manufacturers is going to be around 36,000 pounds or the equivalent of a three-foot-high spoil pile in the adjacent area. Outside of the adjacent area the spoil pile can be much greater than this three-foot limit.
Note that other manufacturers could have a lower allowable surcharge load. That is why having a copy of the manufacturer's tabulated data is so important.
Why is this a concern?
These limitations are important because in the adjacent area, any weight pushing down results in lateral pressure on the protective system. All protective systems have a limit as to how much lateral pressure it can withstand. So we have to be careful how much equipment, materials and spoil is placed in the adjacent area.
In 1926.652 (C)(2) it clearly states that we must follow the manufacturer’s specifications, recommendations, and limitations. Those limitations include surcharge loading such as that which has been described.
For more information on this and other related excavation safety topics please visit www.trenchandexcavationsafety.com
International Data Center Builder at The Weitz Company
11 个月Love to see an article on this topic. Do you have any information on areas of influence and the right distance and angle of repose necessary for say moving traffic or heavy loads like cranes?
Trainer: Excavation Safety with MMJ Services---Excavation Safety CPT, TTT, Construction Confined Space, OSHA 10/30, Field Leadership 40 plus years in excavation safety, manufacturing, marketing, training.
12 个月Thanks again! For the record, internal leadership at OSHA determined that if they had missed something really important, it was surcharge loads on protective systems. It is not missed entirely, of course, but there is not a proper snd focused emphasis. Shield manufacturers have done little put placed the weight of the issue on the back of the CP…who in this instance, why good, is not that good. The stability of adjacent buildings and so forth another example of this. Suffice to say NAXSA has asked and almost begged manufacturers to respond with charts/data to assist. One manufacturer has refused and while some have nodded ascent—-little has been accomplished, There is I think a request for greater help from manufacturers on this as well in a relevant OSHA interpretation. Joe Turner, P.E. Godfather of shoring Engineers and Jasper Calcara, currently on point have produced sample formats to be used…but if one manufacturer refuses, the competitive downside envisioned makes the rest cowards.