Water Well Journal
Issue link: http://read.dmtmag.com/i/715953
waterwelljournal.com 28 September 2016 WWJ Mechanical drills provide the necessary power and versatil- ity for drilling in sand, clay, and loamy soils. These machines drill 6-inch boreholes to depths of 100 to 200 feet—tackling the scope of most water well and geotechnical projects. Mechanical drills have few moving parts, making it easy for less-experienced drillers to operate. This helps minimize the risk of inexperienced drillers accidentally damaging the drill, and in turn, needing costly repairs. They are also light- weight and portable, so one or two people can easily load or unload the drills from the back of a truck or utility vehicle. Often, nonprofits select these for water well drilling projects in locations that have soft soil or clay, such as Guatemala's coastal region. However, mechanical drills aren't the answer for every project. For example, drill crews in some areas face high- density rock, requiring the force of a hydraulic drill. These machines achieve depths of 300 feet and are the go-to choice for operators consistently drilling to 150 feet or more. To generate as much as 5000 pounds of pull-down force in rugged rock formations, some manufacturers offer an anchor- ing option and a bypass flow switch. With these capabilities, water well drill crews efficiently reach all necessary aquifers to access clean water, and geotechnical drillers reach the required depths for attaining soil samples. Also consider if your project could benefit with a trailer- mounted rig. Although these models generally cost a bit more than standard hydraulic drills, they provide a fast transporta- tion solution and achieve depths of 400 feet. Some trailer- mounted rigs offer space for transporting equipment. For example, look for models with pipe racks to save on the cost of using an additional vehicle to haul drill pipe. In addition, a trailer-mounted rig eliminates time loading and unloading the drill from the back of a utility vehicle. Some manufacturers ship the model fully assembled in a 20- foot rod rack and design it with a fold-down mast for conven- ient transportation. Built to Last Drills don't look all that different from the outside, but look closer to find units built to last. It's crucial to understand this when purchasing a geotechnical drill, especially when using the drill for multiple projects. Some manufacturers entice customers with low prices by avoiding the discussion of quality, but customers soon realize those drills don't last. When calculating return on investment, it's difficult to see positive growth after a low-quality drill is unable to complete more projects or be resold. Heavy-duty welded steel frames and thick drill pipes, for example, assure the drill can withstand all challenging forma- tions. Some manufacturers cut corners on quality by con- structing frames with thinner steel. This can cause the frame to bend or twist while driving over rough terrain or prema- turely wear due to corrosion in hot, humid climates. In addition to the frame, look for manufacturers that use 2- inch-diameter drill pipe and connections made of heat-treated alloy steel. Low-quality drills generally use ¾- or 1-inch- diameter pipes intended for less intense projects, like sprinkler installation. For changing drill pipes quickly, some manufacturers offer a three-way ball valve with their drills. The ball valve allows operators to divert mudflow back into the mud pits rather than down the drill pipe. This reduces pressure on the pipe, making it easy for an operator to clamp off the drill pipe and unscrew the drill head. It also minimizes the risk of the borehole col- lapse, which can be caused by cuttings flowing back into the borehole. Drills with features simplifying maintenance make it easy for drill crews to achieve its full service life. For example, an easily accessible adjustment screw and locking nut minimizes downtime when removing slack from the drive chain. Conve- niently located greasing points also save a significant amount of time during routine greasing and maintenance checks. If maintained properly, a quality drill can last several decades. It's reassuring to recognize the brand of engine on a drill, too. Some manufacturers reduce costs by using small horse- power engines. This can force the engines to work harder in harsh conditions, increasing the amount of servicing and re- pairs. Be sure the engine comes from a reputable manufac- Easily accessible points for greasing can help geotechnical drill operators save on replacement parts. MORE FOR YOUR DOLLAR from page 27 Some manufacturers incorporate drill racks into their drill design, enabling crews to maximize their time at the job site.