Geotechnical & Tunnel Consultants

A consultant is a universal observer who can look at a problem outside the environment in which the problem came to be, thereby creating a solution that was never possible before.  Fernando Flores

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B-Type 1 or 2?
C-Jacked Pipe Failure
D-Top of Rock
E-PI Litigation Support
F-Geotech Assessment
G-Microtunneling Hard/Soft
H-Machine Failure
I-Boulders-Tunnel Boring
K-Plowing Utilities
L-Rock Socket Overrun
M-Bored Tunnel Inflow
N-Rock Comminution
O-Sub-Std TBM Performance
P-Bored Tunnel-Shear Zone
Q-Disputes Resolution
R-Problem Proj. Completion
S-Bored Tunnel Overbreak
T-Auger Sampling Problems
U-Bored Tunnel Delay
V-Hoe Ram - Failure to Rely
Peter J. Tarkoy
differing, site, conditions, auger drilling, misrepresentation, consulting

The Danger of Auger Borings
--- Mischaracterizes Material Character ---

All of our professional career, we have found auger borings to be the cause of extensive and consistent problems unlike bentonite wash borings. 

The sample quality has been substandard, the blow counts have been unreliable, the top of rock misleading, and the nature of the material misidentified (e.g.- sand when the material was actually sandstone).

The tungsten carbide fingers and bullet bits tend to disintegrate  the rock into soil, penetrating the rock far below the actual the top of rock.  In some cases as much as 2 meters below the top of rock identified in wash borings. 

The auger is basically a screw that imposes its own thrust for the tool to advance into the rock.