What information should be included in a soil report
In the previous article (Soil report) we explain meaning by soil
report and take general view about the information inside it. Here we will go
deep inside the most and important information should include in soil report.
1- Introduction.
In the introduction section, the geotechnical engineer
should mention the main objective of the soil report or investigation report.
Also, mentioned the site number, plot number, name of project, client, and main
contractor names, etc.
2- Regional geology.
In this section geotechnical engineer describe the
geological condition in this area and basic soil information.
3- Field work.
Include the start and completion date, the scope of work,
total number of boreholes done with the depth of every borehole, number and
type of tests conducted in site and in laboratory. Good soil report should have
clear site plan drawings with location of boreholes.
4- Methodology.
Include the methods of boreholes drilling and methods of
tests conducted. Also, soil report should have the log sheets of the drilled
boreholes as well as the laboratory test and in-situ test results as annexes of
the report.
5- Laboratory testing.
In this section geotechnical will explain in detail the
laboratory testing program was implemented to confirm the visual
classifications, define index properties, and determine corrosion potential of
soil, rock, and groundwater table. Also, describe the standard test methods
used for test soil and rock. All these data should put in the laboratory tests
carried out on boreholes table. The table should include information such as
type of test, standard test methods and number of tests with copy of all test
results as annexes of the soil report.
6- Groundwater condition.
In this section, geotechnical engineer will mention the
water table level during the drilling period.
7- Soil conditions.
In this section the geotechnical engineer will explain the
types of soil at different depth based on boreholes test results. Also, give
statement for liquefaction status at the site. This can be in general site
stratigraphy table. The stratigraphy table can include approximate elevation by
meter and strata description.
8- Conclusions.
Base on in-situ and laboratory test results, the allowable
bearing value can be obtained and according to this value, the geotechnical
engineer can decide the type of foundation will be used in site such as shallow
foundation or deep foundation. Also, can decide the required water table level
and if required to use dewatering system or not. In case of required to
excavate and replace the existing soil by another type of soil such as engineer
fill materials, the geotechnical engineer should describe the required excavate
depth, type of replacement soil, the thickness backfilling layer, the maximum
dry density requirements, etc.
9- Slope stability.
In this section the geotechnical engineer will give
recommendation about a safe slope requirement during excavation. This can be
done at save slope angle table. This table can include soil type, average SPT
test, H: V (horizontal to vertical) ratio and slope angle.
10- Construction approaches.
The soil report should contain suggestions concerning the
method of construction. Such as need for dewatering excavation, the need for
casing piles, and considerations of settling of soil around excavations causing
damaged to nearby structures.