Drill bored piles ≤ 600 mm checklist – no concreting

The checklist

Pre-Drilling & Setup

1. 1Confirm pile ID, grid location, design diameter (≤ 600 mm), and target depth against approved drawings; mark out on site and capture setout photos with datum references.
2. 2Verify rig capacity and calibrated instruments (inclinometer, depth meter, water level/interface meter); attach current calibration certificates and record serial numbers.
3. 3Inspect temporary casing stock (diameter, wall thickness, usable length) to extend through unstable strata and below groundwater as required; photograph casing IDs and tally lengths.

Verticality Measurement

1. 4Align and zero the rig mast using a spirit level and mast inclinometer before drilling; acceptance: initial verticality ≤ 0.3% or per approved project specifications; save inclinometer screenshot.
2. 5Record mast inclination at 1–2 m depth intervals during drilling; acceptance: cumulative deviation ≤ 1% of bore length or per specifications; maintain a time-stamped inclination log.
3. 6Measure verticality at final depth with the inclinometer or plumb bob in casing; acceptance: ≤ 1% of bore length; attach final reading and note any corrective actions.

Groundwater & Stability Control

1. 7Measure groundwater level pre-drilling using an interface/water level meter; record elevation relative to site datum to plan casing or fluid head requirements.
2. 8Maintain casing or support fluid head ≥ 1.0 m above groundwater level to prevent inflow and wall sloughing; log levels hourly and after depth changes with photos of gauges.
3. 9Advance/oscillate casing through unstable or water-bearing layers until competent stratum; acceptance: stable walls with no ongoing rilling; capture before/after photos and casing tip depth.
4. 10Suspend drilling and notify supervision if wall collapse, excessive inflow, or loss of head occurs; raise a hold point and record corrective plan approval.

Base Cleanliness (Sediment)

1. 11After reaching final depth, pause to allow cuttings to settle (minimum 5–10 minutes or per specifications); record waiting time and tool withdrawn.
2. 12Clean the base using an airlift bailer or clean-out bucket until returns are clear; acceptance: minimal fines in returns; photograph equipment and returns condition.
3. 13Measure sediment thickness with a weighted tape, spoon, or clean-out plate; acceptance: ≤ 50 mm or per approved project specifications; log three readings and average.
4. 14Repeat clean-out and measurement cycles until the average sediment thickness satisfies the acceptance limit; attach final measurements and supervisor confirmation.

Diameter & Geometry Verification

1. 15Verify bore diameter at multiple depths using a mechanical caliper, sonic caliper, or template; acceptance: measured diameter ≥ design; upload caliper profiles with depth markers.
2. 16Pass a full-length dummy cage or template equivalent to design reinforcement size; acceptance: unobstructed descent and retrieval; record video or photos of pass-through.
3. 17Confirm the last drilling tool diameter is not less than design diameter; document tool type, diameter, and manufacturer plate photo.
4. 18Check final depth against drawings; acceptance: depth ≥ design and within +0.3 m/−0.0 m or as specified; export depth meter log with timestamps.

Documentation & Handover

1. 19Capture geotagged photos of bore mouth, casing stick-up, wall condition, and base inspection/clean-out tools; label images with pile ID and time.
2. 20Compile inclinometer logs, groundwater and head readings, sediment measurements, diameter verification, and depth records; attach to the pile inspection report for review.
3. 21Obtain digital sign-off from site engineer/inspector; publish the record set and link a QR code at the pile location for traceable retrieval.

Preview the printable checklist

Preview page one below. Open the image or download the PDF for all pages.

At a glance

• Purpose-built checklist for small-diameter bored piles that validates the four critical factors—verticality, base cleanliness, groundwater stability, and diameter—before any placement, minimizing rework and structural risks through calibrated methods and objective evidence.
• Practical, tool-specific actions show how to measure inclination at intervals, maintain a safe head over groundwater, clean and gauge sediment thickness, and verify diameter at depth, producing consistent results across crews and shifts.
• Documentation-first approach captures inclinometer logs, depth and level readings, sediment measurements, caliper profiles, and geotagged photos; clear acceptance cues reference approved project specifications and authority requirements for defensible QA decisions.
• Interactive online checklist with tick, comment, and export features secured by QR code.

How to Use This Checklist On Site

1. Preparation: Gather calibrated inclinometer, depth meter, water/interface level, clean-out tools (airlift bailer/clean-out bucket), caliper or template, casing, and PPE. Review drawings, approved project specifications, and method statements before mobilizing.
2. Start Interactive Mode: Open the checklist on a mobile/tablet, select the pile ID, and begin ticking items. Add comments for variances, attach photos/videos, and capture instrument screenshots directly in each step.
3. Record Measurements: Enter verticality readings by depth, groundwater and head levels, sediment thickness values, and diameter profiles. Use numeric fields and ensure timestamps and user IDs are captured.
4. Review and Resolve: Address any nonconformances before proceeding. Use the comment thread to note corrective actions and reference approvals per project specifications and authority requirements.
5. Export and Sign-Off: Generate an export as PDF/Excel with embedded photos and logs. Obtain digital signatures, distribute to stakeholders, and verify QR authentication for the archived record.

Controlling and Verifying Verticality

Vertical alignment is the foundation of bored pile performance. Begin by leveling the rig and zeroing the mast inclinometer before cutting ground. Track inclination at 1–2 m intervals; small corrections early prevent compounding deviations. Where soils vary, reduce crowd and torque to avoid drift. At full depth, recheck verticality using the mast instrument or a plumb line inside casing. Many projects accept ≤ 1% of bore length, but always apply the approved project specifications and authority requirements. If readings approach limits, adjust the mast and redrill/ream sections while maintaining bore stability. Capture screenshots of inclinometer readings with timestamps and pile ID to create a defensible audit trail. Consistent verticality control reduces bending demands on the pile and facilitates accurate cage placement in subsequent operations.

• Zero inclinometer and verify with a spirit level.
• Measure at 1–2 m intervals; log continuously.
• Target ≤ 1% deviation or per specifications.
• Correct early to prevent cumulative drift.
• Attach time-stamped screenshots and pile ID.

Groundwater Management and Bore Stability

Small-diameter bores are sensitive to groundwater inflow and wall sloughing. Establish the groundwater level before drilling and plan casing or support fluid accordingly. Maintain at least 1.0 m head above groundwater to create a stabilizing pressure differential. Where soils ravel or seepage increases, advance casing to a competent layer and oscillate to cut in cleanly. Monitor for signs of instability: turbid returns, loss of head, deformation at the mouth, or tool binding. Stop and escalate if collapse is suspected. Stability checks must be recorded, including water levels relative to datum, casing tip depth, and photographs of gauges. The objective is a stable, open hole with intact sidewalls ready for subsequent operations without introducing fines or soft pockets at the base.

• Measure baseline groundwater with an interface meter.
• Maintain casing/fluid head ≥ 1.0 m above groundwater.
• Advance casing through unstable layers as required.
• Stop and escalate on signs of collapse.
• Log levels, casing depth, and photo evidence.

Base Cleanliness and Sediment Thickness

A clean base ensures load transfer to competent strata. After reaching depth, let cuttings settle, then use an airlift bailer or clean-out bucket to remove fines. Confirm cleanliness by measuring sediment thickness with a weighted tape, spoon, or plate. Many projects limit residual sediment to ≤ 50 mm, but always apply the approved project specifications. Take three readings at the base and average them; repeat clean-out cycles until within the acceptance limit. Document the process with photos of returns, tools used, and the measurement method. Clear, repeatable measurements reduce soft toe risk, improve end-bearing reliability, and provide transparent evidence for acceptance prior to any placement activities.

• Allow settling before clean-out begins.
• Clean using bailer or clean-out bucket.
• Measure and average three sediment readings.
• Target ≤ 50 mm or per specifications.
• Attach photos of tools and readings.

Diameter and Geometry Confirmation

Verifying bore diameter and geometry in small piles avoids underbreak and obstructions. Use a mechanical or sonic caliper to profile diameter at several depths. Measurements should meet or exceed the design diameter; underbreak is unacceptable, while overbreak must remain within project limits. Pass a dummy cage or template matching reinforcement dimensions to confirm unobstructed descent, indicating proper alignment and no local necking. Record the last drilling tool diameter and confirm it is not smaller than design. Verify final depth meets drawings within the specified tolerance. Compile caliper logs, pass-through evidence, and depth records to demonstrate the bore is dimensionally compliant and ready for subsequent steps.

• Profile diameter at multiple depths.
• Measured diameter must meet or exceed design.
• Pass a dummy cage without obstruction.
• Confirm final depth within tolerance.
• Archive caliper logs and pass-through media.