Reficar Cartagena Refinery Expansion, Colombia - EKN

4.1 Environmental Conditions
1101335.000 04F1 0611 MJ21
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June 21, 2011
The Project site is part of the coastal plain and is relatively flat with some small undulations
about 6 m high. In the Project area, there are low-altitude ridges and hills (approximately 100 to
200 m above sea level east of the site. The refinery site elevation is slightly above sea level.
The Cartagena Bay and surrounding islands are formed by Middle to Upper Miocene
(approximately 11.2 million years old) and Pleistocene (1.6 million years old) geologic
formations, both of sedimentary marine and shoreline (litoral) origin. In the coastal area, the
latter lie above the former. Overlying both of these units, recent Quaternary alluvial and marine
sediments constitute the upper layer.
Based on site boring logs at the Project site, the subsurface conditions underlying the site to
approximately 15 m depth (50 ft) consist of fill materials, including clay varying to sandy and
silty loam and other fine-grained hydraulic fill material of low permeability, with intercalations
of sporadic calcareous gravel and sandy clay lenses. Based on site monitoring wells, there is an
upper clay layer, mixed with organic compounds, with an average thickness between 1 and 6 m,
which covers the majority of the existing refinery area. A second layer, with an average
thickness of 15 m, constitutes the phreatic aquifer in the area. This aquifer consists of finegrained
clayey sands, intermixed with calcareous and micaceous gravels. Below this aquifer,
ICP reports the presence of a thick (> 20 m) clay layer. The region is reported as a zone of low
seismic threat.
The Project area is classified as having a dry tropical climate. The Project is located in an area
traversed by the Intertropical Convergence Zone (ITCZ), a belt of low pressure and atmospheric
instability that circles the Earth near the equator. As the ITCZ crosses the Project site, the
climate shifts from dry to wet and back. Total annual average rainfall in the area is
approximately 1,044 mm per year. The dry season typically lasts from late December until
early April, with average monthly rainfall of 5.3 mm. February is, climatologically, the driest
month, with an average of only 0.3 mm. The rainy season occurs during the remaining months,
with substantial rainfall (188.2 mm/month) between early April and late June. The monthly
average rainfall rate dips in July, but climbs back to 104.2 mm/month from the beginning of
August until the end of December. On an annual basis, the average monthly temperature is