Shoring part 1

The City building inspector required a plan to prevent the side walls of the excavation from collapsing and potentially damaging neighbouring property or causing an injury to a worker that is crushed by falling soil.  Whether this is actually necessary is a different issue, and if the cost of complying with the inspector is reasonable is not a discussion it is even possible to have with City Hall.

Even worse that the field work necessary to comply with the requirement is the significant cost to have an engineer come up with a design, because the City doesn't provide any guidance that could cause it liability.  This specialty in construction engineering tends to generate a large fee for the design work, and like most technical fields, there are many disagreements and wildly contrasting opinions about the best way to do shoring.  For simple shoring designs we could actually come up with a safe design ourselves, for zero cost.  The contractors we are using have substantial field experience in dealing with safety hazards.  They have a keen instinct about maintaining their own personal safety and ensuring valuable equipment isn't damaged.  In addition they have the 'farmer' mentality about how to get a job done with the least waste and inefficiency, and a vast body of experience in site 'work arounds' to deal with the unexpected.

Lacking a way forward except to proceed and absorb the cost of the shoring, we selected a wood post system.  Essentially post holes are drilled, posts are cemented into place, and boards are placed crosswise the posts to retain the soil.  With all the right equipment on site and some trial and error, we were able to integrate the shoring work with the excavation, using the same manpower and equipment along with a skid steer with an auger bit and funnel attachment, a chainsaw, nail gun and some effort.

Hard to see here, but the auger attachment it biting quickly into the clay material.  Coring the holes is done in minutes thanks to the machine doing the work 

Posts are installed and concrete added to ensure stability.  Each hole has 60kg of concrete in it at this stage of the install.  The posts are not particularly straight making the board install a little more awkward.  We will be improving the system for the other side of the excavation.

More planks are added and eventually the wood will be installed to the top of the posts

At this point we have had enough of hauling our own concrete and are relying on the machines to distribute the concrete with very little effort by the crew