Trial pitting can be carried out by a variety of methods, from hand dug pits to machine excavated trenches. Trial pitting is generally carried out to a maximum depth of 4.5m with standard excavation plant and, depending on soil conditions, is generally suitable for most low rise developments. All trial pit investigations are supervised by experienced engineers with a thorough understanding of geology and soil mechanics. Trial pitting is often used as a quick and cost-effective method for gleaning a basic understanding of the soil profile across a site, or to supplement information provided by other methods of investigation that are run concurrently.
Additional testing in trial pits can include infiltration/soakaway testing (in accordance with the guidance as set out in BRE 365), CBR testing and in-situ strength testing.
A variant of the standard geotechnical trial pit is the slit trench, generally taking the form of a long and narrow trench which is commonly excavated to expose existing utilities, whereby they are accurately logged and surveyed by an engineer and surveyor. Slit trenches are commonly excavated in urban environments to map out subterranean utilities prior to carrying out developments, where they may have to be diverted from their current positions.
Inspection pits are also commonly put down by light excavators and/or hand digging methods to expose existing foundations. These are a common element of the works scope for projects where refurbishment and extension works are scheduled.
Our services would include provision of a full report where we supply a detailed log of each trench (in plan and cross section) and full as-built plans, drawn-up in accordance with the Client’s requirements.