BK Int’l touts alternative to wave wall sea defence

Oct 29, 2010 News

A section of the Stewartville sea defence site - the rip rap versus the wave wall.

– media given practical demonstration at Stewartville

By Kristen Macklingam

Durable sea defences have been a problem locally for some time, and this is evident with the many structures that are currently in dire need of repairs and maintenance, especially along the coast.
Cognizant of this, BK International Incorporated (BK Int’l) yesterday, held a press briefing and took media operatives to the Stewartville sea defence site at West Coast Demerara (WCD) to have a practical idea of the alternative that the company proposed to the Government of using “rip rap construction” to build stronger sea defences rather than having to build more “wave walls”.
Kit Nascimento, a Public Communications Consultant to the Company, stated that in keeping with the designs and specifications and as a responsible contractor, BK Int’l has an obligation and duty to point out any of its concerns as it relates to the execution of the European Development Fund (EDF) Sea Defence Programme which BK Int’l has been contracted to carry out.
Nascimento explained that Government used a French Consultancy firm, Egis Bceom, with this project, which is a normality, since most consultants are foreign-based.
However, he said that BK Int’l wrote the government about its concerns of using the wave wall design for a number of projects, stating with ‘considerable evidence’ that the rip-rap construction alternative would be more successful than having wave walls.
He said that the “rip rap” would reduce the “wave run-up” and this would be very easily maintained, since unlike the wave walls where a lot of work needs to be done when they are damaged, in the case of using the rip-rap construction, all that would have to be done is the replacement of the necessary boulder(s) or adding more boulders to strengthen the defence system.
Nascimento went on to say that BK International has provided extensive evidence that the wave wall designs have begun to sink around the country and they are “impossible to maintain”.
There were 34 sites identified for works to be carried out, and currently there are nine sites which the contractor has proposed to the Ministry of Finance that they should change.
The wave wall is almost always built on top of an old wall which cannot hold it for a long period of time – as such it begins to sink then eventually cracks.
Nascimento told the media that Gov’t has seen the proposal for some sites and would “look at it again”. The sites at Montrose/Vryheid’s Lust, Better Hope and Melanie Damishana on the East Coast of Demerara, are some of these.
However, sites at La Bonne Intention, Chateau Margot, also on the East Coast and Zeelugt, on the West Coast of Demerara, have already been “looked at” and BK Int’l has been given the go-ahead to proceed with the required works.
In these cases, the contractor has no choice but to proceed with the works, and even though some are under revision, the company has noted that it cannot delay commencing work in those areas since there is a stipulated time frame that has to be met for the completion of all sites.
Nascimento added that the rip-rap construction would cost around 15-20% more than the wave walls for the sites, however, it would only need to be checked around every 20 years or so to ensure that everything is running smoothly.
Dr. Clifton Inniss, Project Manager (acting) for BK Int’l stated that the site at Stewartville is 550 metres, and clearly shows an example of the “rip-rap construction”.
The project there is Government funded. It consists of boulders which have rough surfaces and frictional resistance that cause the water not to overspill much.
He explained that the rip-rap area measures about 12 metres while the wave wall, which is over a short distance, will place a lot of pressure on the earth.
The waves have a lot of energy and the boulders would dissipate this energy; in some cases 8 metres before it reaches in, causing less wave spilling.
Inniss added that the wave wall is initially supposed to be of a height of eight to nine feet high and this would be a great risk to persons who will want to climb over for recreational or religious purposes.
This height is much higher than what is required for the rip-rap construction.
He explained that some of the sites catered for in the project only require a little work such as putting on beams to raise the walls, filling some small areas etc. So far, 31% of the project is completed.