Reboring an existing water borewell can help restore or increase the water yield if the original borewell has dried up or is underperforming. Here are the steps to follow while reboring an existing water borewell:
1. Preliminary Assessment
- Survey the Existing Borewell: Assess the current condition of the borewell. Check the borewell depth, static water level, yield, and any visible damage to the casing or structure.
- Geological Survey: Engage a geologist or hydrogeologist to assess the groundwater availability in the area. They will suggest whether reboring is feasible and recommend an appropriate depth.
- Permission from Local Authorities: Ensure that you have the necessary permits and approvals from local authorities to conduct reboring, as some regions regulate groundwater extraction.
2. Choose a Suitable Reboring Method
- Deepening the Existing Borewell: This involves extending the depth of the current borewell to access deeper aquifers. It’s the most common method.
- Side Boring or Redrilling: In some cases, drilling a new borewell next to the existing one may be recommended if geological conditions suggest better water potential nearby.
3. Site Preparation
- Clear the Area: Remove any debris or obstructions around the borewell to ensure the rebore machinery can access the site safely.
- Set Up Equipment: Bring in the required machinery (such as a drilling rig) and set it up properly. Ensure that the equipment is well-maintained and suitable for the depth and geology of the site.
4. Borewell Casing Inspection
- Inspect the Existing Casing: Check the condition of the existing borewell casing for cracks, corrosion, or damage that could affect the reboring process.
- Repair or Replace Casing if Needed: If the casing is damaged, replace or repair it before proceeding with reboring. This ensures that the borewell remains structurally sound and prevents contamination from surface water.
5. Start the Reboring Process
- Drilling Deeper: Begin the drilling process using rotary or percussion methods, depending on the geological conditions. The new drilling depth should be decided based on groundwater studies and the advice of a hydrogeologist.
- Drilling Fluid/Cleaning: Use appropriate drilling fluids (water, mud, etc.) to clear the borehole of debris, sand, and gravel. Keep the borewell clean during drilling to avoid clogging and ensure smooth operations.
6. Monitor Water Inflow
- Check for Water: As you drill deeper, periodically check for water inflow by measuring the water level and yield. This helps determine if you’ve reached a productive water-bearing layer (aquifer).
- Perform Test Pumping: Once water is found, perform test pumping to assess the yield and water quality. If the yield is insufficient, drilling may need to continue deeper.
7. Install Casing and Well Screen
- Install New Casing (If Required): If reboring requires deeper or wider casing, install new sections of casing to support the borewell walls and prevent collapse.
- Install a Well Screen: If the new section taps into an aquifer, install a well screen at the bottom to filter out sand and silt, ensuring clean water flows into the borewell.
8. Gravel Packing and Sealing
- Gravel Pack: Add a gravel pack around the well screen to prevent fine sand or silt from entering the borewell while allowing water to flow freely.
- Seal the Borewell: After completing reboring, seal the area around the casing with a concrete slab or grout to prevent surface water contamination.
9. Develop the Borewell
- Clean and Develop: Flush out any debris, sand, and mud left from the drilling process by developing the well. This can be done through airlifting or high-pressure water jetting to ensure good water flow.
- Yield Testing: Once the borewell is cleaned, perform a final yield test to determine its flow rate and ensure it meets the required capacity.
10. Water Quality Testing
- Test Water Quality: After reboring, test the water quality to check for contaminants such as TDS, hardness, nitrates, bacteria, and other pollutants. Treat the water if necessary (e.g., through filtration, chlorination, or reverse osmosis).
11. Pump Installation
- Install an Appropriate Pump: Based on the new water yield and depth, install a suitable submersible or jet pump. Ensure the pump capacity matches the borewell’s flow rate.
- Check Electrical Connections: Ensure the pump’s electrical wiring and connections are properly set up for safe operation.
12. Regular Monitoring and Maintenance
- Monitor Water Yield: After reboring, regularly monitor the borewell’s water level, yield, and pump performance to ensure sustained productivity.
- Periodic Cleaning and Flushing: Clean the borewell periodically to prevent sediment buildup and maintain good water flow.
By following these steps, reboring can help improve water availability from an existing borewell, ensuring a reliable and long-lasting water source.