A typical trial pit log of the engineer’s observations is given in Fig. 3.5.
A borehole log should give details of the foreman driller’s log, the observations of the supervising engineer and the results of any site tests. A typical borehole log is shown in Fig. 3.6.
Trial pits, trenches and boreholes should be given reference numbers, located on plan, their ground level noted and the date of excavation recorded. It is advisable to record the following additional information:
(1) Type of rig, diameter and depth of bore or width of bucket.
(2) Diameter and depth of any casing used and why it was necessary.
(3) Depth of each change of strata and a full description of the strata. (Was the soil virgin ground or ﬁll?)
(4) Depths at which samples taken, type of sample and sample reference number.
(5) In situ test depth and reference number.
(6) The levels at which groundwater was ﬁrst noted; the rate of rise of the water; its level at start and end of
each day. (When more information on permeability, porewater pressure, and the like is required, then it is vitally important that the use of piezometers should be considered.)
(7) Depth and description of obstructions (i.e. boulders), services (drains) or cavities encountered.
(8) Rate of boring or excavation (useful to contractors and piling sub-contractors as such information gives some guidance in ease of excavation or pile driving).
(9) Name of supervising engineer.
(10) Date and weather conditions during investigation.
Fig. 3.4 Recommended symbols for soils and rocks
Fig. 3.5 Typical trial pit log (Weltman, A.J. & Head, J.M., Site Investigation Manual, CIRIA (1983),
Fig. 3.6 Example of a typical borehole log (BS 5930, Fig. 22).