Trial Pits
Trial pits are best suited to large, undeveloped sites, where the excavations can be used to rapidly characterise variations in ground conditions over a wide area in advance of the main investigation. They can also inform the design of temporary works, where they permit a direct visual assessment of groundwater flow rates and trench stability issues, while rippability assessments can be conducted in areas where shallow rock is encountered. Hand-dug inspection pits can also be used to expose and record the dimensions of the shallow foundations of existing buildings.
Inspection pits
Machine or hand-dug inspection pits would typically be excavated during the preliminary phase of an investigation, when the holes would be supervised and logged by an experienced Ground Engineer. Trial pits would normally extend to depths ranging between 2 and 4.5m relative to excavator size, where large bulk samples would be recovered for laboratory testing.
