Overview
This method statement covers the drilling of boreholes for geophysical investigation. It includes procedures for borehole drilling, sampling, installation of monitoring equipment, and safety measures.
Scope of Work
The scope includes mobilization of drilling equipment, drilling of boreholes to specified depths, collection of soil and rock samples, installation of piezometers or monitoring wells, and site restoration.
Equipment
- Rotary drilling rig (truck-mounted or track-mounted)
- Drill bits (drag, tricone, or diamond)
- Drilling fluid (mud or air)
- Sampling tools (split spoon, Shelby tube, core barrel)
- Casing and screen materials
- Grout materials
Step-by-Step Procedure
1. Mobilization
Transport drilling equipment to site. Set up rig on level ground. Verify utility clearances before drilling.
2. Drilling
Drill borehole to specified depth using appropriate method. Maintain drilling records including penetration rate, drilling fluid returns, and water level observations.
3. Sampling
Collect soil samples at specified intervals using split spoon sampler. Obtain undisturbed samples using Shelby tube where required. Rock core samples using double or triple tube core barrel.
4. Borehole Logging
Log all geological formations, water strikes, and sampling locations. Photograph all samples and cores.
5. Instrument Installation
Install piezometer or monitoring well as per design. Seal annular space with bentonite and grout. Install protective casing and lockable cap.
6. Site Restoration
Restore ground surface to original condition. Remove all drilling waste and debris. Demobilize equipment.
Quality Control
Maintain detailed drilling logs. Verify sample preservation and labeling. Calibrate monitoring instruments before installation.
Health & Safety
All personnel shall wear PPE including hard hats, safety boots, hearing protection, and dust masks. Maintain safe distance from rotating equipment. Follow procedures for handling drilling fluids and cuttings.
