Following an extended period of severe erosion to the coastline of Bar Beach, situated along Amadu Bello Way in Victoria Island Lagos,  shoreline protection works was required to alleviate ingress of the sea at the points of the most severe erosion of the beach currently experienced.

Following an extensive survey of the beach where the erosion is most evident, a survey report was generated. The point of the most severe erosion was identified as adjacent to the Bauchi State Liaison Office in Amadu Bello Way, at this point  the width of the beach is less than 3 metres.

The works commenced on the 1st of January 2006 and should finish by 2006 year ending. It comprise the construction of shoreline protection 1,000m in length commencing at a point just to the west of The Abia State Liaison Office and to IMB Bank. The construction of the shoreline protection is designed to provide permanent protection for this section of the shoreline. 

The design utilizes layers of rock placed on a geo-textile sheet with pre-cast concrete elements (x-blocs), placed to the leading face of the beach front, as the primary protection. These x-blocs weigh 3.6 tonnes each and are designed to form an interlocking barrier to incoming waves. The size of the blocs were determined by computer simulation to withstand the worst predictable storm conditions within a 100 years period.

The works will be executed in the following stages:

a.      Sand replenishment of the beach to a level corresponding to 3 metres above Mean Low Water Spring Tide level (MLWS) and to a width of 20 metres extending from the existing road kerb to the upper leading edge of the x-bloc layer.

b.       Contour the sand to the required profile.

c.      Lay geo-textile material on the sand extending to a point 10 metres out to sea from the lower leading edge of the x-bloc layer utilizing suitable weights to anchor the material on the sea bed.

d.      Place a layer of rock (particle size 10 – 60 kg) 300mm thick on top of the geo-textile material on the sea bed and up the sloping face of beach front.

e.      Place a layer of rock (particle size 300 – 1000 kg) 700mm thick on top of the initial rock layer on the sea bed (item d) and up the sloping face of beach front; making a total rock thickness of 1000mm.

f.        Place x-blocs on top of the previous rock layers (items d & e) to a pattern insuring interlocking of blocs in both horizontal and sloping faces.

g.      Lay geo-textile material on the horizontal surface of the sand (level MLWS + 3.00 m) extending from the rear of the x-blocs to a width of 5 metres.

h.        Place a concrete slab of 10m width 150mm thick on top of the protected area of the beach.

The above procedure will be applied in 15 m sections along the length of the beach, with all stages completed consecutively in each section to insure full protection at the earliest opportunity.

The concrete x-blocs are pre-cast at a factory established in the site yard using preformed steel moulds fabricated to the design prescribed by Delta Marine Consultants (DMC) the designers of the x-bloc system. The blocs are stored in the site yard for a period of not less than 2 weeks following casting before transporting to the final location and placing.