Nov. 22, 2004 – A group on St. Croix has submitted a proposal to the Wastewater Management Authority to design a "constructed wetland" to assist in wastewater treatment. This procedure, which joins environmentally safe technology with natural waste filtering process, is being touted as an economical alternative to water treatment facilities currently in use in the territory. The group includes Onaje Jackson, president and founder of Sustainable Systems Development Inc.; Kelly Groger, senior administrator of SSD Inc.; Pat Mahoney, Energy Answers; and Ron Levigne of New England Waste Systems Inc.
Levigne, a leading expert on the subject, presented the project to a small group of St. Croix residents last week at the University of Virgin Islands. He said beds of constructed wetlands topped with indigenous grasses could process sewage cheaper and more efficiently than our present treatment system.
Levigne's presentation included a slide show of numerous wetlands systems he assisted in installing in Europe, South America and communities in the United States. Levigne pointed to the indigenous German grass that is commonly used on islands as forage for goats as an integral part of the proposed wetland treatment system that can provide "near drinking quality water."
The group has proposed that the V.I. Waste Management Authority install a half-acre wetland treatment system at the Anguilla treatment facility to demonstrate the technologys performance locally. The demonstration system would process up to 50,000 gallons of wastewater per day. The reclaimed water would be used for the irrigation of forage and vegetable crops that would be monitored by the UVI Agricultural Experiment Station.
A constructed wetland has the capability to effectively remove many pollutants associated with municipal and industrial wastewater and storm water. Contaminants such as suspended solids, nitrogen, phosphorous, hydrocarbons and others can be removed from wastewater through constructed wetland systems. Plants and microorganisms are the active agents in the treatment process. Additionally, the constructed wetland area can be used for the grazing of animals such as goats.
Presently 1.2 million gallons of sewage is pumped daily out from St. Croix into the ocean after only primary treatment. Jackson said the EPA "Is putting pressure on to make something happen quickly to change that."
Gloger said the wetlands project will save money in two areas construction and on-going operation and maintenance. Gloger said constructed wetlands use little or no electricity because the wastewater moves through the system by gravity and plants pump oxygen to the wastewater during the treatment process instead of machines as in a mechanical treatment facility. The existing primary plant at Anguilla, built in 1973, has a three-million-gallon capacity, however it's taken over 30 years to reach one-half of its design capacity and presently only 1.6 million gallons currently pass through the system each day. The mechanical treatment system proposed for St. Croix has a design capacity of four-million gallons day. Mechanical treatment systems are built for future flows because it is costly to add on to these systems as flows increase. By comparison, constructed wetlands can be built economically in increments, as treatment capacity is needed. Groger also explained that constructed wetlands do not require chemical use, there are no mechanical systems to maintain, and labor costs are substantially reduced. "Buying a four-million-gallon treatment plant at $25 million means that we will be sitting on about $12 million in unused capacity for many years," Gloger said. "With a wetland we buy what we need when we need it. In addition, the territory could save at minimum $16 million in operation maintenance cost over the 20-year contract with the contract operator. This money could be used for the needed upgrades to the sewer collection system on St. Croix."
According to Jackson, this project has been years in the making. He said the method used with constructed wastelands would bring the Virgin Islands up to EPA standards. "Right now we only have primary treatment of wastewater," said Jackson. Constructed wetlands can provide secondary treatment by putting the wastewater through a series of treatments using vegetation, sand and other components. Jackson said the wastewater remains one meter below the surface on the land providing a possible pasture. An impermeable liner prevents the wastewater from filtering down into the groundwater.
Jackson said constructed wetlands would provide irrigation-quality water to St. Croix farms and golf courses.
St. Croix is the ideal environment for this type of wastewater treatment system and its a much better alternative to discharging sewage 3,000 feet off the south shore of St. Croix, Jackson said.
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