The OceanSpring seafloor-based monopile desal plant is scalable from 2,000 to approximately 3,000 AFY.  The monopile is comprised of two primary components consisting of a prefabricated reinforced concrete base, approximately 75 feet in diameter, and anchored to the seafloor with steel piling and the prefabricated mono-tube, measuring approximately 25 feet in diameter, will be lowered into the pre-installed base, and fastened in place.  No anchors are required.  The plant will be installed just outside the coastal closure depth in approximately 60 feet of water and approximately 5,000 to 7,000 feet offshore.  The monopile will extend above the waterline no more than approximately 30 feet and will have less visual vertical square footage than a fully sailed 25-foot sailboat at the same distance offshore.

As with the barge-based desal plant, a single permeate pipeline consisting of high-density polyethylene is installed in a horizontal directionally drilled bore from a point onshore to the bore’s designed seafloor exit point offshore just shoreward of the monopile installation. 

In fact, the same permeate pipeline used to support the barge-based desal plant can be repurposed to support the monopile desal plan.  Permeate pipeline dimensions will vary depending on the capabilities of a given configuration.  Multiple monopile desal plants, or in combinations of barge-based and seafloor-based desal plants, may be clustered around a single permeate pipeline seafloor termination and connected to the permeate pipeline via a small seafloor manifold.

The seawater intakes of the monopile desal plant will draw no more than approximately 5.4 MGD (based on 3,000 AFY maximum capability) per individual monopile plant.  All seawater will be filtered through proven rotating wedge wire screens mounted on the bottom of the monopile base. 

Brine will be discharged from circular diffuser piping, compliant with the specifications of a third-party diffusion study, attached to the exterior of the monopile just under the water surface to provide maximum diffusion as the heavier brine water drifts down to the seafloor through the water column.

Impacts to the seafloor will be limited to the base of the monopile and the seafloor exit point of the horizontal directionally drilled permeate pipeline.  These impacts will be less than 4,500  square feet (slightly less than a 1/10 of an acre).