Dear Editor,
In an article which appeared in Sunday Stabroek of December 20 captioned ‘Shallow outfall, high dam best option for Hope Relief Channel,’ it was reported that the consortium of consultants for the Hope Relief Channel for the East Demerara Water Conservancy (EDWC) has now determined that a shallow outfall channel with a high crested weir over the sea defences would be the preferred option to reducing peak conservancy levels.
In the consultants’ Draft Report of June 18, 2009 on the engineering design of the EDWC Hope Relief Channel, it was stated that, “the high foreshore discharge option [now recommended] was not as effective as the deep outfall channel option either in terms of reduction of peak conservancy levels or volumes of water discharged to the Mahaica River through the Lama and Maduni Sluices. However, if the height of the weir is reduced performance will be improved but expensive foreshore excavation and maintenance [still indeterminate] will be required.”
In a press release of November 24, 2009 Minister of Agriculture Robert Persaud stated that he had expected the final design for this project by December 9, 2009 with the bidding and the other necessary documents to proceed and be complete at that time also.
The Sunday Stabroek article of December 20 suggests that a revised draft of the final report has now been submitted to Minister Persaud, which he stated is being rigorously scrutinized by a special technical team. Therefore, the question being asked is whatever happened to the design, specification and contract documents for this project which should have been ready by December 9 as Minister Persaud alluded to in an earlier press release?
It is reasonable to conclude that a lot of work remains to be done with respect to preparations for the final design, specifications, contract documents and estimated cost for this project. Mr Latchmansingh, Chief Consultant for the project, is reported to have said, “the consultants are still awaiting some tests conducted and when the results arrive next year they will be added to the final draft report.” Hence it seems that the project is still in the reporting and data collecting stage, and critical aspects of the design at this juncture cannot be completed to achieve the greatest effectiveness that Minister Persaud so eloquently emphasized.
Mr Latchmansingh stated that the construction of the outfall channel and high crested weir would cost approximately $3.6 billion. How could this cost be estimated when the design is not finalized? He further stated that the system will have a discharge capacity of 62.1 cubic meters/sec. It is not clear how this figure was arrived at, but whether it was obtained from empirical hydraulic calculations or deduced from modelling, it is a fuzzy estimate, or as Minister Persaud stated in one of his earlier press releases, “a lot of guessing by the consultants.”
The consultants have vague ideas as to the cost of constructing and maintaining the proposed outfall channel, as the information is not presently available for them to realistically prepare their estimate, although they realize that the softness of the soil (slingmud) which clogs outfall channels with regularity, was found to be problematic. In an attempt to solve this problem they have proposed the use of geotubes which have never been tried in Guyana. Hence their suggestion that rigorous testing of these materials to counteract the siltation and erosion problems of outfall channels should be imperative, and urged that the National Drainage and Irrigation Authority (NDIA) be part of the testing process. Is the NDIA not paying the consultants to do this work for them? It seems therefore that further work remains to be done to get the required information so necessary for the design of these variables for which so little is known.
It is inconceivable that an approximate cost of $3.6 billion has been given for a project that has no final design or contract documents on which any costing should be based.
Minister Persaud seems to be correct when he stated in his news conference of November 24, that our technical people do not really understand scientifically how the EDWC behaves, and a lot is being done by ‘guessing.’ I trust and hope that guessing by the consultants designing this project would eventually solve the flooding problem of the EDWC.
Yours faithfully,
Charles Sohan
