Set the drill rig at the intended well location and drill a borehole to the total planned depth. If you are unsure how deep to drill your well, contact the local environmental or water bureau for information on typical well depths and construction in your area. Keep the borehole vertical as you drill, or you will have difficulty installing the PVC pipe. Use a plug in the bottom of the first auger so that the open interior of the hollow-stem augers do not accumulate formation soil during the drilling process. You want the interior of the augers to remain open so that you can set the casing inside the auger. Remove the drill cuttings from the work area with a shovel. After you reach the total well depth, leave the augers in the borehole while you prepare the casing materials.
Screw the threaded PVC pipe together so that the well point is at the bottom of the well, the slotted screen is in the center, and the solid casing is at the top. Lower the PVC pipe into the open center of the hollow stem augers. You should fully assemble the well materials on the land surface before you place it inside the augers, because the materials can be too heavy to hold in the borehole while you screw the pieces together. When the well materials reach the plug at the bottom of the borehole, push on the PVC to dislodge the disposable plug from the end of the auger. The plug will remain in the borehole after the well is complete. Use enough PVC pipe that the casing extends above the top of the land surface. Place a well cap on top of the PVC pipe. You can use a slip cap or locking well cap from a drilling supply company.
Pour sand into the annular space between the PVC pipe and the inside of the augers, raising the augers slightly as your pour the sand. You want the sand to fall through the augers. Do not rotate the augers as you raise them. For example, if you pour three inches of sand, raise the augers approximately three inches. The purpose of raising the augers as you pour the sand is to fill the entire borehole with sand between the PVC pipe and the surrounding soil. Measure the thickness of the sand with a measuring tape. Place sand in the borehole until it extends at least two feet above the top of the slotted PVC screen. For example, if your well depth is 30 feet and you use a 10-foot screen, you need at least 12 feet of sand in the borehole, ranging from 30 to 18 feet below the land surface. Insert the measuring tape into the borehole until it rests on the top of the sand. When the tape measure reads 18 feet from the land surface to the top of the sand, you know that you have sufficient sand in the borehole. The sand allows groundwater to move into the well screen through the slots.
Place at least two feet of dry bentonite into the borehole. Both bentonite chips and pellets are appropriate for water wells. Pour the bentonite, measure the thickness, and raise the augers as you did with the sand. Hydrate the bentonite with water and allow the bentonite clay to swell before you continue.
Install cement grout in the remaining annular space, using a grout pump or tremie pipe and funnel. A tremie pipe is a one-inch PVC pipe that you can use to pour the grout through and into the bottom of the borehole. Completely remove the augers from the borehole as you place the grout. The grout should reach the land surface to properly seal and set the PVC well pipe. If desired, complete the well with a metal cover.
Things You Will Need
- Drill rig
- Hollow-stem augers, preferred
- Disposable auger plug
- PVC casing, solid, threaded
- PVC screen, slotted, threaded
- PVC well point, threaded
- PVC well cap
- Filter sand
- Measuring tape, weight attached
- Cement grout
- Tremie pipe with funnel
- Grout pump, optional
- Metal well cover, optional
- The inside diameter of the hollow-stem augers must be larger than the diameter of your well materials.
- If you do not have access to a drill rig, contact your local environmental or water bureau for a list of certified drillers in your area who can help you install the borehole.
- You can drill the borehole with solid-stem augers if the soil is competent clay that will not cave when you remove the augers from the ground.
- Call the local utility companies and ask them to mark the underground utilities on your property before you install the well casing.