By Joe Haynes
When drilling in a remote location, such as in the case of a mission project in a developing country, finding a suitable groundwater source to tap into is critical to the well’s long-term viability. It’s important to find an aquifer large enough to support the surrounding communities.
Use clues from the landscape and lean on local knowledge to locate an area where groundwater is close enough to the surface to reach. Also, consider how deep the rig you are working with can drill. For example, some smaller mechanically powered drills can drill to 200 feet, while some hydraulic rigs can reach depths of 300 feet.
Professional geophysical survey equipment is ideal for finding plentiful groundwater close to the surface, but it isn’t necessary. Drillers can take clues from the landscape to make an educated guess about what’s below.
- Ask locals where they currently get their water. Existing hand-dug wells will reveal groundwater depth and give insight into subsurface soil properties.
- Sand or gravel areas in the bottom of valleys will often be home to groundwater. These layers can be covered by clay or silt, so it’s prudent to check these areas thoroughly.
- Natural springs usually indicate groundwater is nearby. A spring that flows year-round will likely reveal a productive aquifer. Even if a spring dries up at times, it may still be atop a suitable groundwater supply, so it is worth looking into further.
- If there are streams in the area, look for sections where the flow is greater. This can mean groundwater is discharging into the stream, pointing to a good spot to drill.
- Groundwater at shallow depths often can nourish above-ground vegetation. Trees or shrubs that stay green in dry seasons may have roots that can reach the supply. Even greener patches of grass can indicate close-to-surface groundwater.
- Animals, especially bees and pigs, can be talented at finding groundwater.
- A white crust on the ground surface may be salt or other mineral deposits left after groundwater has evaporated, indicating a reservoir underneath.
The Pilot Hole
Despite efforts to select an appropriate site, there’s no guarantee water will be found with every bore. That’s why most drilling projects should start with a pilot hole. Use a small pilot bit to bore a hole. Depending on your well drilling equipment and site conditions, the time for this process will vary. Carefully collect and record the cutting samples from this exploratory hole to develop a boring log, which will help design the future well if the site works out.
Watch for signs that an aquifer has been reached as the borehole is advanced, such as:
1) Thinner mud.
2) “Streams” of clear water in the drilling mud as it exits the borehole.
3) Changes in mud temperature.
4) Sand or gravel in the cuttings.
5) Clay chips that are moist inside when broken apart.
6) A rapid increase or decrease in mud levels in the suction pit.
Remember that finding a site that produces a sufficient amount of water is more important than choosing a convenient location. Drilling close to a community should not cause drillers to sacrifice well viability.
About the author
As President of Little Beaver and Lone Star Drills, Joe Haynes works with a team of engineers to develop digging and drilling solutions, including earth drills, mini trenchers, water well drills, and horizontal boring kits. He has more than four decades of experience in the drilling industry and is committed to providing long-lasting solutions to customers around the world.
About the company
Lone Star Drills are innovative additions to the Little Beaver product family that are designed to be a convenient, powerful solution in areas with minimal resources for transportation and operation. Twelve models are available, and they are ideal for use in a variety of applications including water well drilling, soil sampling, geotechnical testing and auger drilling. For more information, contact Lone Star Drills at email@example.com or www.lonestardrills.com.