A Bored Well Drilling Demonstration

On October 20, 2021, the Illinois State Water Survey staff were invited to a bored well drilling demonstration in North Central Illinois. Professor Mike Phillips, from Illinois Valley Community College, invited ISWS staff to view the construction of a new bored well. Reynold’s Well Drilling, Riverton, IL, was contracted to construct the well. Reynold’s Well Drilling only installs large-diameter bored wells, typically 30-40 wells every year. According to the driller onsite, they have been busier in the last 5-6 years. The entire process took 4-5 hours and was estimated to cost around $15,000. Reynolds was contracted to drill the well and a separate contractor, Lutes H2O Well Drilling Inc. was contracted to install the distribution lines to home the following day.

Regarding the existing hand-dug large diameter well on the property, the owner mentioned that the sample from that well was tested in 1999 when the home was purchased. The test results showed that the drinking water was high in coliform bacteria, nitrates, iron, and manganese. In response, the Phillips installed a UV treatment system and water softener. The water hasn’t been tested since the initial test in 1999. The old well is brick lined well and about 23 feet deep. The water yield for the old well was 5 gallons per minute.

Figure 1. Well Cover for Brick Lined Well

Figure 2. A View Down into the Brick Lined Well

Figure 3. Drill Rig, Trailer, and Water Truck

The process began with selection of a location for the new well. They chose a location in the front yard and approximately 15-20 feet from the driveway. The drillers began by setting up their truck over the chosen location. Once in place, they started digging, using a 36-inch dirt bucket that removes 1ft of dirt per pass.

Figure 4. Drill Rig Set up over the Well Location

The digging continued for several passes, and a large mound of dirt accumulated near the new well. Once there was a depth of 16 ft removed, a metal sleeve was placed in the top 16 feet of the new well. The sleeve worked as a guard to prevent the dirt along the sides from caving in, which allowed the drillers to continue to dig deeper.

Figure 5. Drill Cuttings

Figure 6. Metal Sleeve to Prevent Cave In

Figure 7. Metal Sleeve In Place in the Borehole

Figure 8. Water From the Bucket Indicates Saturated Material

Drilling continued until water was evident in the drill cuttings. When the driller determined they were at a sufficient depth, they prepared the well for installation.

The well was constructed from a single length of fiberglass casing. To allow water into the well, thin slits were cut into the bottom section of the well. Centralizers were attached in three places equidistant apart which acted as stabilizers to position well casing upright and center it in the borehole. Water was pumped into the annulus to hold pressure to the sides to prevent caving, while a vertical metal beam was used to hold down the fiberglass well casing, so it didn’t float. Filter sand and gravel placed in the annulus served to both hold the well in place, allow for additional water storage around the well, and to help filter the water in the formation before it can get into the well.

Figure 9. Driller Cutting Slits in the Well Casing

Figure 10. Close Up of the Cut Slits in the Well Casing

Figure 11. Fastening Centralizers and A Lid to Lower the Casing into the Well Borehole

Figure 12. Lowering the Well Casing into the Borehole

Figure 13. Adding Water into the Annulus Around the Well

Figure 14. Adding Sand and Gravel into the Annulus Around the Well

To finish the well, water is pumped from the new well until it runs clear, a cap is added to the fiberglass well screen, a submersible pump is installed, and a 6-inch PVC well casing is installed from the fiberglass well cap to the surface. The sleeve is then removed, and the upper portion of the well bore is filled with clay or concrete. At the end of the drilling process, the total depth of the borehole was 43 ft on the bottom, 13 ft at the top, and the top of the water was reached at 22ft. The well will be able to provide 8 gallons/minute. The last responsibility for the driller is to complete a well log and file it with the county health department.

Figure 15. Developing the Well by Pumping It Until the Water Runs Clear

Figure 16. The Fiberglass Cap and 6-inch PVC Casing that will Extend to the Surface

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The Private Well Class is a collaboration between the Rural Community Assistance Partnership and the University of Illinois, through the Illinois State Water Survey and the Illinois Water Resources Center, and funded by the U. S. Environmental Protection Agency.