The seawater requirements for the project were calculated to be as follows:
|Pond volume (1 pond):||485 m3/h (128 000 US gal)|
|Requirements to fill 1 pond in 18 h:||27 m3/h = 7.6 l/s = 120 gal/min|
|Requirement to change 20 percent pond volume in 8 h (2 ponds):||24.25 m3/h = 7 l/s = 107 gal/min|
The project water requirements also incorporate the water requirements for the wet laboratory and the outside tank farm, which will be moved to Ras Haiyan when the laboratory is finished. The water system for the laboratory was removed from the laboratory construction contract. Although provision is made for water for the outside tanks and laboratory by a larger size pump for the ponds, the cost of a pipeline from the pump to the laboratory and tank farm will be provided from funds other than Feasibility Project funds.
The laboratory and outside tanks water requirements are:
|Laboratory (35 m3 of tanks)|
|Requires complete change every 3 h:||11.7 m3/h = 3.25 l/s = 52 gal/min|
|Outside tanks (130 m3 of tanks)|
|Requires 50 percent change/24 h:||2.7 m3/h = 0.75 l/s = 12 gal/min|
The total project quantities and the hours required are:
|06.00 (8 h)||14.00 (16 h)||06.00|
|Total||40 m3/h||15 m3/h|
Pumps required 11 l/s = 176 gal/min; 4 l/s = 66 gal/min
(say 11 to 12.5 l/s, designed for salt water use, diesel powered, 8 m total developed head)
The initial pump of 11 to 12.5 l/s will be a diesel powered seawater pump on a wheeled trolley. After the electricity is brought to the site (in early 1984 for the laboratory), the pump will be replaced by two electric pumps and the diesel pump kept for emergency standby and special projects. The small pump for the night service of the laboratory and tank farm will be electric and this pump and the pipeline from the pond pump for use during the day will be provided at the time the electricity arrives. A separate seawater intake for the laboratory will also be provided at that time, as the initial lagoon intake for the ponds may be changed to a larger seawater intake direct from the Gulf if the Pilot Project (Phase I) ponds are built as the next phase. They will require an additional 95 l/s (1 500 gal/min).
As an alternative to a direct Gulf seawater intake, there is the possibility that seawater can be obtained from the large diameter test well that was bored on the project site by the Water Resources Board for the Water Supply Directorate as a possible water source for a future desalination plant. Test pumping (72 h) indicated that the well could produce 105 l/s, with a good recovery rate, of seawater of constant temperature. Well salinity is 44 ppth as compared to an average of about 43.6 ppth for Gulf water from the same area. The level of the water in the well is sea level. The granting of the use of this well by the ministries involved would provide a clean, dependable water source for the entire project and its use is being actively pursued by the Directorate of Fisheries. In the meantime, plans will go ahead for the interim source from the lagoon.