Section 3
Annex H
Site Assessment Report
A scaled map of 1:250 will be issued separately.
1.
Introduction
This site assessment report comprises a precis of a detailed geotechnical investigation and a desk study of the following aspects:
(a) Geology
(b) Seismicity
(c) Meteorological data including rainfall,
temperatures, humidity, wind speed and direction.
(d) Availability of services including water,
electricity, foul and surface water drainage and telephones.
(e) Design standards, codes of practice and
building regulations used locally.
2. Geology
A geotechnical survey comprising 6 boreholes, 24 trial pits, field and laboratory tests was conducted in March 1988.
The results revealed a uniform geological formation across the site. The bedrock is derived from the Nairobi Trachyte horizon a gently, easterly dipping tertiary lava flow. Overlying the trachyte in restricted areas is a 'trachytic agglomerate', the weathered remnant of fused rubble which developed on the top of the lava flow as it was cooled. Generally, the overburden consists of variable thickness of orange-brown clayey silts. Rock outcrops appear spasmodically across the site. An important geological feature of the Site is a deep erosion gulley cutting across the plot in a NW-SE direction. This is likely to be a buried erosion feature in the trachyte, possibly caused by a fault or shear zone. The gulley has been infilled with tuffo and agglomorates overlain by fine to coarse cateritic soil and gritty ash. The depth to the trachyte bedrock in the gulley areas is approximately 7.5 metres deep.
The trachyte sheet will provide a stable base for any medium height structure. The infill soil to the gulley area is a common feature within the Nairobi lava horizons and again should adequately support a medium rise structure.
A geological map of the Site and geological section is shown in Annex H.
A full report is available on request.
No comments yet.
Private notes are available after approval.