When carrying out drilling work, especially for geotechnical drilling, you must pay attention to the following things, such as:

1. Drill Point Location

The location of the drilling points will be determined after looking at the length of the landslide and applied according to SNI, where for small landslides (less than 150m) there are 3 drilling points and for landslides with large landslides, the drilling points are adjusted according to needs. The location of the drilling point is determined in the field at a planned depth by referring to the engineering requirements in accordance with SNI-8460-2017: Geotechnical Design Requirements.

2. Final Drilling Depth

The final depth of drilling that has been completed in accordance with the applicable technical provisions is checked by inserting the drill handle until it touches the bottom of the drill hole or by other means that have been approved by the Board of Directors and whose implementation is within the knowledge of the Supervisor.

3. Taking Driller Samples (Core Sample)

The percentage of nuclei taken for each sample is strived to reach 100%. If the core return is not good, it will be reported immediately.

4. Recording of Ground Water Level

Water level recording was carried out 2 (two) times. The first measurement is at the start of drilling and the second measurement is carried out after drilling is complete.

5. Sampling Box (Corebox)

Made from planks of wood equivalent to Borneo wood, shaved and painted, has a hinged lid and a key holder (padlock). Each box has a capacity of 5 m (depth) divided into 5 lanes @ 1 m depth.

6. Labeling Examples (Samples)

Each storage box is labeled/ticketed. The information included includes:

• Project name/location
• Drill point number
• Storage box number (order).
• Depth range
• Name of Work Executor

The label is written in black paint on the outer lid, inside and front side of the box. The pilot box is placed in a dry place protected from water and sunlight. The storage location for all pilot boxes is further determined by the work director.

7. Drilling Work Equipment

• Drive hammer Assembly: The hammer weighs 63.5 kg, The guide pipe is long enough to allow the hammer to fall freely to a height of 75 cm, Protective cap (knocking head) and steel cable/slin.
• Stang Bor / Rod: The diameter corresponds to the drill hole or according to the type of drilling machine used.
• Split Spoon Sampler Barrel: The outer diameter is 2 inches and the inner diameter is 1 3/8 inches.
• Etc: Materials such as lubricants, paraffin, plastic bags and others are provided in sufficient quantities, considering the remote location.

8. General Testing Methods

• After drilling reaches the planned depth, the drill hole is cleaned to the bottom with drill bits and other tools to ensure that what will be tested is not disturbed.
• Split Spoon Sampler Barrel (clean and slightly lubricated with oil) is installed at the end of the drill handlebar. All connections are installed firmly so that they do not come loose during work. The spoon is lowered to the bottom of the drilling hole and the protective guide cap is installed on the top of the drill handle.
• Then the hammer is dropped on the protective cap from a height of 75 cm. For stakes in the initial position, the split spoon is inserted 15 cm deep. The number of blows/impacts required is recorded (N1).
• After that, drive testing begins with procedure point 3, until the split spoon enters a depth of 30 cm, recording the number of strokes in 2 stages. Stage-1 is a blow to enter the next 15 cm deep (N3) so, Price N = N2 + N3.
• If the value of N is greater than 60 strokes. Testing stopped.
• Consultants make protectors/tents at testing/drilling locations in the event that work cannot be guaranteed due to rain or other causes.