Download geological report of pdp site

GEOLOGICAL REPORT OF PDP SITE
BY ESANG VICTOR WILLIAMS
IT STUDENT FROM FUTMINNA,
DEPARTMENT OF GEOLOGY
TO
THE PROJECT MANAGER
BOUYGUES NIGERIA LTD
PDP NATIONAL SECRETARIATE
COMPLEX SITE ABUJA, F.C.T
NOVEMBER 2010
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TABLE OF CONTENT
TITLE
PAGE
INTRODUCTION……………………………………………………………………….. 2
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
LOCATION……………………………………………………………………….. 3
GEOLOGY OF THE AREA…………………………………………………… 3
METHOD EMPLOYED………………………………………………………. 3
SOIL…………………………………………………………………………………. 3
THICK LATERITIC SOIL………………………………………………………. 3
DESCRIPTION…………………………………………………………………… 4
USES………………………………………………………………………………… 4
CONCLUSION AND RECOMMENDATION………………………….. 5
REFFERENCES…………………………………………………………………… 6
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INTRODUCTION
The objectives of this geological report is to provide the composition,
behavior and usefulness of the excavated soil from the site. This report
gives in details information about the soil type.
The role of a geologist in soil analysis is to provide details about the
origin and history of the rock and soil of a particular area, and to give
advice on how to cope with the behavior of the soil, for the safety of
whatever structure or construction that would be sited on a particular
area. It also includes:
The evaluation of earth material for construction purpose and
evaluation of waste disposal and hazardous waste on site. Also to help
the engineering geologist supply the site engineer with geological info
and insures that the geological factors are properly considered.
Finally, note that this geological report is not the same as the soil
test rather it is aimed at unveiling the usefulness of the excavated soil
on the site.
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1.2 LOCATION
The area mapped is located in plot number 243 cadastral zone A00
central business area district, Abuja. The global positioning system is
09 ° 03.000 'north, 007° 29.026' east.
1.3 GEOLOGY OF THE AREA
The area is basically underlain by rocks of Precambrian basement
complex, comprising mainly of biotite-hornblende granite. The mapped
area is covered by thick lateritic soil and traces of kaolin clay soil and no
visible outcrops.
1.4 METHOD EMPLOYED
The absence of outcrop means that the use of compass clinometer
Would not be necessary and the grain size of the soil are visible to the
human eyes. Therefore it is described with it physical appearance and it
mineralogical composition through geological research and transverse
method was used during this mapping exercise.
1.5 SOIL
Soil have been defined in different ways according to the field they
involved. Generally we can define it as the upper layer of the earth in
which plant grows.
In engineering, soil is either naturally occurring or man-made and
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distinguished from rocks because the individual particle is not sufficient
bonded together. while in engineering geology, soil is refer to as the
entire unconsolidated material that overlies and distinguish it from it’s
bed rocks.
Finally, it can also be said to be a naturally conclomeration of
mineral grains ranging from large borders to single mineral crystal of
Microscopic size.
1.6 THICK LATERITIC SOIL
This is a red residual surface soil formation rich in iron and
aluminum, formed by the leaching of silica, especially in hot and wet
tropical areas, developed by intensive and long lasting weathering of
the underlying parent rock.
Lateritic soil is also said to be a product of a long prolonged
process of mechanical and chemical weathering which produces a wide
varieties in the thickness grade, chemistry and all the mineralogy of the
resulting soil. Nearly all lateritic soil are rusty-red because of its iron
oxide content. Lateritic soil are found to be thick on the stable area of
the Africa shield.
Thick lateritic soil can either be soft or easily broken into smaller
pieces of firm and physically resistant. Basement rocks are buried under
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thick weathered layer and seldom expose. Lateritic soil forms the
uppermost soil of the lateritic cover. Lateritic soil may contain clay
mineral but tend to be silica-poor because silica is leach out by water
passing through the spoil. Typical lateritic soil is porous and clay-like.
There are some traces of with colored grain in the area which
are known as kaolinite, a product of alteration of feldspar in granite due
to chemical weathering. It is one of the popularly known member of
clay minerals.
1.7 DESCRIPTION
• Chemical composition
Chemical composition of laterite depends on their parent rock and
They include quartz SiO₂, iron oxide minerals: goethite HFeO₂, Titanium
Oxide, Zircon, Iron, Tin Lepidocrocite FeO (OH), Heamatite Fe₂O₃ and
hydrated oxides: Aluminum or Gibbsite Al₂O₃.3H₂O.
• Specific Gravity: 2
• Hardness: 1.5-2
• Colour: Blackish-brown to reddish brown.
• Appearance: Red, Yellow and Brown when fresh.
• Texture: fine grained.
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1.8 USES
i. Building blocks: that is normally refered to as red bricks.
ii. Building construction: It has been prove in the past that not all soil is
suitable for foundation of structures especially clay for a long period of
time. Lateritic soil is used to fill such site before the commencement of
any foundation work. One good example of this is the present work at
B.O.B (Body Of Benchers) site.
iii Road Construction: Lateritic soil is recently taking the place of stone
base in road construction, in other not waste resources and energy.
Lateritic soil is used as a sub-base during road construction before the
Hard course material is applied to it, and this act prevents pot holes
because when ordinary clay soil is used especially montmorillonite it
can lead to shrinkage and expansion during the hot and wet seasons.
Iv. Acts like an aquifer : thick laterite layer is porous and slightly
Permeable, an aquifer is a geological formation capable of holding
Substantial quantity of water that can be drilled out for human
consumption.
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v. Waste treatment: it can be used for the phosphorous and heavy
metals at several sewage facilities up to 99%. Percolating columns of
laterite remove enough Cadmium, Chromium and this can lead to
undetectable concentration at a low cost and technology, efficient for
rural areas.
vi. Ore: Laterite acts as ore for bauxite, Iron Nickel. An Ore can be a
metaliferrous geologic formation from which metal of great importance
can be extracted from as listed above. Its has known to be the earliest
ore for Nickel and currently account for about 40% of the world Nickel.
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CONCLUSION AND RECOMMENDATION
Base on the mapping carried out on the plot number 243 cadastral zone
A00 central business district F.C.T Abuja and the nature of geological
data at or near the surface area, it is thus deduce that the formation is
a hard rock terrain covered by thick lateritic soil and traces of whitish
kaolinite member group of clay mineral.
Thus the excavated thick lateritic soil from the mapped area should not
be taken as waste but as an important economic construction material
which can also act as an economic material especially for brick industry.
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Fig : Picture Showing Foundation On Lateritic Soil
SOURCE: BNL CONSTRUCTION AND ENGINEERING 2010 (PDP SITE
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REFFERENCES
1.
2.
3.
4.
CIE315 Course Materials.
Google
Geology of Nigeria.
Minerallogy.
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