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Why do people not understand the need of quality subsurface investigations?
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Stuck boring machine 4
- Thread starter TigerGuy
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hpaircraft
Member
Well, it's ONLY US$65 million ;-)
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I can do absolutely anything. I'm an expert! faq731-376 forum1529 Entire Forum list
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verymadmac
Mechanical
Is the Geotech just for the tunnel or does it include the underground power station as well
- Thread starter
- #46
From my experience, the design team always wants the geotechnical report as cheap as they can get. I try to help clients understand that the geotechnical investigation is not the design phase where you want to cut corners.
I suspect the $100 million is total design fees for the entire project, and the geotechnical investigation was kept to a minimum bare bones service.
Time will tell. We pre-drilled for a drilled shaft once to determine the depth at which rock excavation would start. When the drilled shaft contractor cored into the bedrock for the rock socket, they discovered a void just off from our 4-inch test bore. The ground does indeed contain surprises.
I suspect the $100 million is total design fees for the entire project, and the geotechnical investigation was kept to a minimum bare bones service.
Time will tell. We pre-drilled for a drilled shaft once to determine the depth at which rock excavation would start. When the drilled shaft contractor cored into the bedrock for the rock socket, they discovered a void just off from our 4-inch test bore. The ground does indeed contain surprises.
Bang on Tiger... my experience, too. I recall a cartoon from 40 years back... a 'builder/engineer' holding up the drawings for the Tower of Pisa, commenting to the owner, "...and we can save another 1000 lira if we skip the soils report."
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So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates
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TugboatEng
Marine/Ocean
Maybe this gives some perspective. At the rates listed, and making a whole lot of assumptions, if they test bored the entire 27km of tunnel for geo survey, the cost would have been $26 million USD or $40 million AUD.
The cost per for goes up linearly with length. Drilling multiple smaller bores linked together would have been substantially less.
- Thread starter
- #49
The cost per foot varies greatly with the depth of boring. You can knock out a 25-foot boring, faster than you can drill the next 15 feet. Things only slow down more with increased depth.
With average drilling depths of over 3,000 feet, the average cost per foot is significantly higher than if they were drilling 100-foot borings along the alignment. There are many factors that come into play with a geotechnical investigation cost estimate. Distance of mobilization, terrain (track-mounted rigs typically charge out at an increased rate), type of drilling (auger vs mud-rotary vs rock coring), and daily travel from the hotel to the drilling site are just a few.
I've never drilled for gas and oil, so I can't speak to what all the steps are for drilling a new well. I presume their drilling has more involved and costs more per foot than geotechnical.
With average drilling depths of over 3,000 feet, the average cost per foot is significantly higher than if they were drilling 100-foot borings along the alignment. There are many factors that come into play with a geotechnical investigation cost estimate. Distance of mobilization, terrain (track-mounted rigs typically charge out at an increased rate), type of drilling (auger vs mud-rotary vs rock coring), and daily travel from the hotel to the drilling site are just a few.
I've never drilled for gas and oil, so I can't speak to what all the steps are for drilling a new well. I presume their drilling has more involved and costs more per foot than geotechnical.
bacon4life
Electrical
There is also the danger of the remnants of a geotech investigation directly damaging the boring machine (i.e. Seattle's Bertha).
davidbeach
Electrical
Yeah, that was rather ironic...
I’ll see your silver lining and raise you two black clouds. - Protection Operations
I’ll see your silver lining and raise you two black clouds. - Protection Operations
TugboatEng
Marine/Ocean
I was thinking directional drilling would be used to drill fewer, long wells? Not necessarily many deep wells.
Some information on the drilling. A total of 40 boreholes, ranging in depth from 47 metres to 1165 metres. 14100 metres of boreholes drilled in total.
With all the fractured rock and faulting, it became obvious that the project would be difficult in the extreme, and so it has proved.
With all the fractured rock and faulting, it became obvious that the project would be difficult in the extreme, and so it has proved.
Just Some Nerd
Structural
Correction...14100 in June of 2018. Same source states expected over 17000m by completion, were only about 80% of the way through at the time.
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Why yes, I do in fact have no idea what I'm talking about
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