Key Points for Supervision of the Entire Well Drilling Process

Key Points for Supervision of the Entire Well Drilling Process

Effective supervision throughout the entire well drilling process is crucial to ensuring a well with sufficient water volume, good water quality, and a long lifespan. Supervision does not mean constant intervention, but rather focusing on quality control points in several core stages.

I. Pre-Drilling Supervision Preparation

Confirm the construction plan and contract: Clearly define and record key indicators such as the target drilling depth, diameter, casing material specifications (e.g., PVC pipe wall thickness), and expected water level. Ensure the construction team has experience in local hydrogeology.

Inspect equipment and materials: Verify that the drilling rig model is suitable for the local strata. Inspect the well casing to ensure it is brand new or in good condition with thickened material, free from cracks and deformation; the filter pipe (perforated pipe) should have uniform pores to effectively block sand.

Supervise well location: Confirm that the drilling point is far away from pollution sources such as septic tanks, sewage ditches, and livestock pens (a horizontal distance of at least 30 meters is recommended), while also considering future water access convenience.

II. Key Monitoring Points During Drilling

**Following Up and Recording Formations:** The construction team is required to briefly record soil and rock samples taken at different depths (e.g., depths of clay, sand, gravel, and rock layers). This is the most important basis for determining the location of the aquifer and the depth to which the filter pipe is lowered.

**Monitoring Borehole Quality:** Observe whether the drilling process is smooth, whether the borehole is vertical, and whether the diameter is uniform. This directly affects whether the well casing can be successfully lowered into place.

**Inspecting Core Samples (for rock formation wells):** If bedrock is encountered, the extracted core samples should be examined to confirm the rock hardness and integrity, and to determine if they match expectations.

III. Key Monitoring Points During Casing, Gravel Filling, and Cementing

This stage is crucial for ensuring the well can consistently produce clean water, prevent collapse, and avoid contamination. Full presence is required throughout this process.

**Supervising Casing Lowering Operation:** Ensure the filter pipe section is accurately lowered to the previously recorded aquifer location, with the solid pipe section corresponding to the impermeable layer. Check that the well casing connections are secure and sealed, and that the lowering process is smooth to prevent jamming or disengagement.

Supervising Gravel Filling (Filter Material Installation): Clean, appropriately sized quartz sand or coarse sand filter material must be evenly and continuously filled into the annular space between the well casing and the well wall. Supervise the even filling from all sides to ensure an effective filter layer is formed, preventing fine sand from entering the well.

Supervising Well Sealing: After the filter material is filled to the predetermined height, it must be tightly and densely sealed with high-quality bentonite (commonly known as "clay") or clay balls until it is close to the ground surface. This step is to completely prevent surface sewage infiltration; ordinary soil must never be used for backfilling.

IV. Supervision of Well Washing and Final Acceptance

Supervising Thorough Well Washing: After the casing and gravel filling, a powerful and continuous well wash must be performed using an air compressor or large pump until the pumped water is completely clear and free of sand particles. Incomplete well washing is a major cause of long-term turbid water from wells.

On-site Water Test Acceptance:

Measuring Static Water Level: Measure the stable depth of the well water after pumping stops.

Conduct a pumping test: Perform continuous pumping for several hours (e.g., 4-8 hours) to observe whether the water volume is sufficient and stable, and whether the water level recovers quickly after a drop.

Check water quality: Collect a water sample in a clean container. Visually, it should be clear and transparent, free of visible impurities, and taste free of any off-odors.

Summary: Document the process and confirm each step. Effective supervision relies on on-site witnessing and confirmation of key steps. It is recommended to take photos or videos of the pipe-laying depth, materials used, and well-washing results. Payment should ideally be linked to the construction progress, with payment made only after the quality of each key step is confirmed to be correct. A detailed well structure diagram and geological record provided by the contractor should be included in the as-built documentation. Rigorous supervision ensures a reliable and worry-free well for the next decade or more.