Water Well Journal
Issue link: http://read.dmtmag.com/i/740475
change in direction or a set of low hills all in a row with an unusually steep side. Keep in mind when looking at an aerial image not to asso- ciate man-made structures such as fences and canals with any potential lineaments or features. Sometimes a keen observation of road cuts on the way to the drill site can give some insight into potential subsurface problems. Regional stresses can materialize in the form of faults and fractures that can be recognized and measured in road cuts. Oftentimes if the road cut is long, multiple joint sets can be seen. With careful observation and review, these joint sets can be recognized and can help when making the decision of well placement, especially if the well could be close to a potential source of contamination. Geohazards can act as natural subsurface conduits and can transmit surface water like precipitation-based runoff, or inter- cept surface water flow from streams, ponds, and lakes. They can also be interconnects between impoundments and septic systems—allowing the migration of harmful constituents into groundwater. It is important to recognize these hazards prior to locating the well site as well as during the drilling. Standing on the drill platform is a unique experience. With time and training, the average driller can tell the formation type the drill is encountering simply by the way the rig feels when in operation. It is difficult to explain to someone who has never stood at the controls of a drill and had to visualize the subsurface and the drilling environment. Every vibration has a meaning. If you've ever reviewed a driller's log and seen in the margin or on the log the words fracture, void, or lost circulation, they are signs the driller encountered something out of the ordinary. The driller made an interpretation of the event based on their experience and understanding of the drill site conditions. If interpreted correctly, this information is potentially a sign of a subsurface geohazard. As the drill bit intersects a fracture, fault, or joint, the cut- ting surface is no longer smooth and square with the bit face. As the bit loads more on one side than the other, as it passes through the contact, the drag on the bit will torque the drill string, creating a substantial vibration within the drill. FIELD NOTES from page 27 waterwelljournal.com 28 November 2016 WWJ Many unfortunate problems arising later can be recognized beforehand from a simple overview of an aerial image of the site. A fault gouge within a fault in the Dog Canyon area of Big Bend National Park in southwest Texas. Joint as seen in an outcrop. It is part of a much larger joint set network found on Blue Mountain in Winkler County, Texas.