Let me share a story you may not have heard. A young man stumbled upon a cave and wanted to explore it. In his haste, he grabbed a book of matches and ran toward the cave. Upon entering, the darkness began to envelope the young man. With each footstep the light grew fainter. Soon he stood in complete darkness. He fumbled for the matches. Striking the first match, a small glow appeared, illuminating his face. But just as he started to focus on the details around him, the match burnt out, leaving darkness. He struck a second match. The light penetrated a short distance but within seconds it too was gone. He lit a third match but this time he heard a sudden flutter and a quick rush of air extinguished the small flame. Something leathery hit his face, and filled with fear, he ran hard toward the cave opening. However in his panic, he hit his head on the roof of the cave before he was able to stumble out to the surface.
Not long afterward, the young man ran into his friend, who inquired about the bruise on his forehead. The young man then shared his experience in the cave. His friend exclaimed, “Wait here!” And after a few minutes, returned with a staff and a leather pouch. The friend pulled an oiled cloth from the pouch and wrapped the cloth around the top of the staff. He then instructed the young man to light the oiled cloth with one of his remaining matches. The staff, now a blazing torch, provided just the right amount of light for the two friends to explore the cave together. To the young man’s delight he could now clearly see the magnificent stalactites and stalagmites, the glass-like reflection of a small pool near the bottom of the cave, and the group of bats hanging from the ceiling. He was no longer fearful but filled with excitement as he and his friend gazed upon this wondrous Underground world.
Exploring the Underground today is not that different. Anxious for results, test borings are commissioned, but in an effort to keep costs low, lab tests are not run. Unfortunately, test borings alone seldom present the whole picture, often resulting in more questions than answers. Without the proper field/lab tests, we can only speculate on the soils’ strength and compressibility. Rushed field investigations may also leave out important information such as dimensioned locations, ground and water elevations, and site geology. The Client is left wondering how the limited borings drilled relate to the project, and may even find the borings were not drilled deep enough. The Client’s Design Team is left with attempting to make important decisions for the project with only sketchy data.
Without a clear approach, test borings, like the young man’s matches, shed little light on the subject. It is only when the Client and the Geotechnical Engineer work together, developing a thoughtful approach to investigate the unknowns, can the project be successful. By illuminating unknowns such as high groundwater, shallow rock, sinkholes, existing fill, soft clays, running sands, and other conditions, the Geotechnical Engineer assists the Client to see a clear picture of the Underground, thereby reducing the risks that often have the greatest impact on the project’s schedule, costs, and/or performance - no longer a fearful proposition.
Originally published as a LinkedIn post, May 27, 2015