1. Dualisation of Ekim Itam - Ikot
Oku Ikono Road, Construction of
Discharge Drain, Akwa Ibom
Client:
Akwa Ibom State Ministry
of Works and Transport
Construction Period:
01/2009 – 12/2011
Services:
Construction of 3km
drainage system, inner
diameter 2,000mm
Uyo, the capital city of Akwa Ibom State, is
located on a flat area (plateau) without natural
surface drainage, where the rainfall of 3,000mm
per year cannot be discharged properly. During
the long rainy season the area is subject to
severe flooding. As a consequence, the city
was often inundated with storm water causing
major impacts to traffic flow, business and are
the potential for damage to infrastructure and
buildings.
In combination with the construction of three
new flyover bridges and the dualisation of the
Ekim Itam – Ikot Oku Ikono Road, a solution for
the discharging of the surface water of roads,
flyovers and the adjacent areas was required.
Julius Berger Nigeria PLC received in 2009 the
contract for the construction of a rainwater and
surface drainage system for the township of
Uyo.
The nearest discharge point is a valley with a
connection to the Ikpa River in a distance of
approximately 3km northeast of the flyover
location at Itam Roundabout. The city of Uyo
is located approx. 70m above sea level; the
bottom of the valley is 25m above sea level.
For these preconditions a technical solution
was found.
To discharge the surface water, the construction
of an underground drainage pipeline with a
total length of 2,300m and an inner diameter of
2,000mm was finally designed.
Due to the existing geology and topography the
pipeline is built as a micro tunnelling system
through the so called ‘pipe jacking’ method,
a closed construction of concrete pipes and
a stilling basin at the end. With this system,
massive earth works and demolition works
could be avoided.
The entire drainage system starts with an
open U-channel of 400m length with the cross
section 1.5x2.0m. The U-channel ends in a
manhole which is equally the starting point of
the underground discharge pipeline. The total
pipeline distance of 2,300m is divided by 4
manholes, which are called the start- & target
manholes for the ‘pipe jacking’ system.
The manholes were built as an overlapped
bored pile wall with an inner diameter of 11m
(start) and 7m (target) respectively and up to
23m depth. These manholes were additionally
used as inlet points for the surface drainage
system of the adjacent areas.
The pipeline is located in a depth between 6m
and 45m. The pipes have joining with rubber
sealing and are waterproof from inside and from
outside. The longitudinal slope of the pipeline
is up to 4.2% in the last section. At the end of
the pipeline a stilling basin is constructed to
reduce the velocity of the water. The maximum
discharge capacity of the pipeline is 21m³ per
second, while the expected flow velocity is
7-8m per second.
JBNProjectBookNo.NG-2007-041-02