Elevator cylinder hole collapse – Undermining building

Colley Elevator does a lot of cylinder work, probably the most in the City of Chicago/State of Illinois.  We have experienced a lot of different underground conditions that could create challenges.  Last week we ran into a non-cased hole that was drilled in the late 1960’s that was all clay.  When we pulled the cylinder it didn’t seem promising but we gave it a shot with the vacuum truck and the hole started to collapse.  It is very important to know when to turn of the vacuum truck or you could start to undermine the building.  In this event the project team called it correctly and stopped the undermining before it became substantial and was isolated to the elevator pit.

[Cylinder prior to replacement]

[Hole in ground after cylinder was removed]

[After debris was removed and pit began to be undermined]

Definition of Undermine - erode the base or foundation of (a rock formation).

Potential danger – The potential danger we encounter is to create a foundation issue for the building if we continue to remove material from underneath the building.  Our hole doesn’t get deeper, it gets wider.

 #1 - Shows the elevator cylinder in the ground, in this case it goes down 27'

#2 - Shows the underground undermine potential

Moving forward – A well driller will need to be hired to put down casing to get a clear hole and when they are completed we will back fill the pit to replace any material that was removed during the vacuum truck visit.

Take away – When considering your cylinder replacement project, make sure that the company you are working with has experience with cylinder replacements and has a project team that has the domain knowledge to navigate your project in a safe manner.  Hiring a big name doesn’t necessarily mean that the team managing or completing your project has the correct domain knowledge.

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If you have any questions or would like additional information feel free to contact me at CraigZ@colleyelevator.com or 630-766-7230 ext. 107.