Infiltration: A Unique Seawater Intake System
The Infiltration is a uniquely engineered filter bed to keep marine life and debris including mussels, jolly fish, seaweed, fish and fish eggs and larvae, sand and silt, trash, and oil from entering into raw water systems. It delivers a continuous supply of clean water in sufficient quantities to virtually run any system capacity. The Infiltration system performance and flow rates are unaffected by the violent breaking of waves on the beach during a storm. It is maintenance-free requiring no backwash, cleaning, treatment, scrapping, replacement, recharging, or rehabilitation. No moving parts, nothing to rust, to tear, or to wear. It is expandable without the need for system shutdown. It meets and exceeds all environmental requirements worldwide.
The Infiltration is very simple. Once the system is designed and the filtration area is selected, screens and materials are assembled, the installation takes a few days to start up and commission the system. Clean water is drawn by gravity through a trunk pipe to an equalizing pool or wet well – a small basin located onshore from which water is pumped to the plant.
Water level goes down during pumping in the equalizing pool, head is created thus gravity is activated. That process causes water to rush into the pool through the trunk pipes which are connected to a series of header pipes. The header pipes are in turn connected to a net work of screens impeded in the infiltration bed. All piping is none metallic. Water filters down to the screens through the infiltration bed. This process is controlled so that the local submarine currents, which are active in different directions in the open sea on the top of the Infiltration bed, have much higher velocities than the velocity of the filtering water. As a result, the filter bed stays clean and porous. However, it is not an easy task to have down flow velocity uniformly distributed throughout the area of the bed. Through research, we are able to get the entire bed tuned to the same flow conditions with uniform velocity distribution throughout. It is a man-made controllable aquifer.
The Infiltration system requires no settling basin since there is nothing to settle. The system needs an equalizing pool where pump intake pipes are placed and where the downstream end of the system intake pipes are located. This pool can be made of a section of a pipe with a diameter large and deep enough to activate gravity and handle the flow requirements and to house the intake outlet and pump inlet pipes. Large diameter polyethylene pipe sections work well.
Artificial filter intakes, under seafloor seawater intakes, and infiltration galleries have been considered for some time, but instances of actual application and experience are limited. The studies that have been done deal with small capacity intakes using relatively clean waters and with minimal wave disturbances. Back washing was usually an integral part of these intakes. The maximum capacity obtained by these systems usually did not exceed 4 m^3/s (60,000 GPM). The Infiltration intake system is different from the types that have been studied or constructed before.
In open channel intake systems a great deal of measures are often considered during their design and engineering including protection against wind forces, waves, currents, mussels, seaweed, fish, sand, trash, etc. In the offshore pipeline systems ocean currents twist and break intake heads, erode pipeline beds and cause them to break. All these factors must be well studied and integrated in the design of open intake channels or pipeline systems.
In the Infiltration, flow rates increase in stormy weather. The currents clean the filtration bed. When waves break they dissolve oxygen, which creates aerobic conditions in the filtration bed thus reducing biological fouling. Oxygen in open intakes is not welcomed because it causes corrosion to the intake inlets, stationary and moving screens, pumps, heat exchangers, etc. Compacted sea weeds, which flow into open intake channels and clog them during storms in many parts of the world, are used in the Infiltration as additional filtering media.
However, If site condition prove to be totally inadequate to provide a suitable home for the Infiltration, our Offshore Intake system would be the best alternative to fill the gap.