Machine Excavated Trial Pits
Machine excavated trial pits are crucial for a comprehensive understanding of subsurface conditions in construction and redevelopment projects. These pits provide detailed insights into soil properties, groundwater conditions, and existing foundations.
Why Do I Need to Have Machine Excavated Trial Pits?
1. Thorough Soil Investigation: Allows for the examination of deeper and larger soil profiles, as recommended by BS 5930:2015.
2. Foundation Assessment: Evaluates the existing foundation conditions and their suitability for new construction.
3. Identifying Groundwater Levels: Helps in assessing groundwater levels and potential issues.
4. Structural Safety: Ensures that the ground conditions can support the proposed structures.
5. Regulatory Compliance: Ensures that the project meets local building codes and regulations.
Description of the Machine Excavated Trial Pit Process
The process of excavating machine trial pits involves several critical steps to ensure accurate data collection and analysis:
Step 1: Planning and Site Selection
• Identify Locations: Select strategic locations for trial pits based on the site investigation plan.
• Safety Measures: Implement safety measures and mark areas to avoid underground utilities and other hazards.
Step 2: Excavation
• Mechanical Digging: Use 360° excavators (tracked/mini-excavators) or a hydraulic wheeled backhoe loader (e.g. JCB 3CX) to dig trial pits, typically to a depth of between 1.5-3.5 meters and widths of between about 0.3-0.6 meters.
• Controlled Excavation: Carefully control the excavation to prevent collapse and ensure accurate profiling.
Step 3: Inspection and Sampling
• Soil Examination: Inspect the exposed soil layers for colour, texture, and composition.
• Sample Collection: Collect soil samples from different depths for laboratory testing, following BS 1377 standards.
• Foundation Exposure: If assessing existing foundations, expose and inspect the foundation footings.
Step 4: Documentation and Analysis
• Detailed Logging: Record soil stratigraphy, groundwater conditions, and any anomalies.
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Our experienced Geotechnical / Geo-Environmental Engineer will log the strata in accordance with BS5930 whilst taking disturbed samples at regular intervals for subsequent contamination and/or geotechnical laboratory testing including pocket penetrometer testing where applicable.
