I am bidding an elevator addition on an existing building. The elevator will be installed in a corner, therefore 2 sides of the elevator shaft foundation will require underpinning. The actual underpinning is not in my scope of work and I am also not including the excavation for under the existing footer. I will just be digging down to grade.
I have to dig down 9' to hit existing building floor slab. I then need to dig down an additional 5' for the bottom of the elevator pit. That 5' will be the underpinning. I also need to dig another 3' for the elevator sump pit.
Here is my question. What would be the proper way to excavate this.
1) Dig all the way down the 14' and leave a vertical dirt wall from the existing footer down and let the underpinning contractor dig out where he needs to be ??
2)Dig down the first 9' and then dig down the remaining 5' starting at the existing footer and down at a 2:1 slope and let the underpinning contractor go from there ?
Either way, I am gonna have to be on-site to scoop out any dirt that the underpinning contractor excavates. I am guessing that I will be sitting there for awhile reading a magazine.
Foundation is 8' wide. So, I will opening up a hole that will be about 10-11' wide on a wall that is about 15' long on one side and 30' on the other.
What really makes this tough is the fact that it is jammed up into a corner and I cannot swing. I'll have to sit at a 45 degree angle to dig and my tracks will be sitting on the sidewalk part way in the parking lot. I also will be using my 200 since it is deep.
Oh, did I mention that there is no geo-tech report so I have no idea on soil conditions. I also I have rip out a 7,000lb duct bank and install a new one.
When I called the GC to confirm that I will be bidding (they called me first to ask), when I told the secretary yes, she said "Oh goodie !!!" That sounds like bad news, lol.
I have to dig down 9' to hit existing building floor slab. I then need to dig down an additional 5' for the bottom of the elevator pit. That 5' will be the underpinning. I also need to dig another 3' for the elevator sump pit.
Here is my question. What would be the proper way to excavate this.
1) Dig all the way down the 14' and leave a vertical dirt wall from the existing footer down and let the underpinning contractor dig out where he needs to be ??
2)Dig down the first 9' and then dig down the remaining 5' starting at the existing footer and down at a 2:1 slope and let the underpinning contractor go from there ?
Either way, I am gonna have to be on-site to scoop out any dirt that the underpinning contractor excavates. I am guessing that I will be sitting there for awhile reading a magazine.
Foundation is 8' wide. So, I will opening up a hole that will be about 10-11' wide on a wall that is about 15' long on one side and 30' on the other.
What really makes this tough is the fact that it is jammed up into a corner and I cannot swing. I'll have to sit at a 45 degree angle to dig and my tracks will be sitting on the sidewalk part way in the parking lot. I also will be using my 200 since it is deep.
Oh, did I mention that there is no geo-tech report so I have no idea on soil conditions. I also I have rip out a 7,000lb duct bank and install a new one.
When I called the GC to confirm that I will be bidding (they called me first to ask), when I told the secretary yes, she said "Oh goodie !!!" That sounds like bad news, lol.