Stable bore ≠ clean pile base. Sand, silt, clay and rock cuttings can settle after excavation and after the first cleanout. Bottom cleaning therefore needs its own construction procedure.

Where sediment comes from

Sources include normal excavation spoil, wall fallout, settled sand in polymer systems and rock cuttings. Initial cleanout may not be the final condition because particles can continue settling.

Cleaning methods

Depending on project procedure, cleanout can use a cleanout bucket, airlift, hydraulic pumping or controlled circulation. Maintain support-fluid head during cleaning.

Sample the bottom fluid

Surface slurry may not represent the lower column. A clean tank plus dirty bottom is possible, especially after long holding time or in polymer systems.

Concrete is not a cleaning tool

Tremie concrete should displace an acceptable support fluid after the toe and lower slurry are ready. Do not rely on rising concrete to correct excessive sediment.

Pair this procedure with the slurry contamination and replacement guide.

Frequently asked questions

Does low sand content prove the base is clean?

No. Coarse particles may already have settled out of the sampled fluid.

Is one cleanout always enough?

Not necessarily. The project should verify post-cleanout settlement behaviour.

Can chemistry remove bottom sediment?

No. Sediment already at the toe requires physical removal.