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Water: Nonpoint Source Success Stories

Virgin Islands Section 319 Success Stories, Vol. III

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Virgin Islands Partnership:
Alternative Treatment Systems Prevent Contamination of Coastal Waters


Syed A. Syedali
Environmental Engineer
Department of Planning
and Natural Resources
45 Mars Hill
Frederiksted, VI 00840-4474
Primary Sources of Pollution:

failing septic systems
Primary NPS Pollutants:


Project Activities:

alternative treatment systems installed

effectively controlled discharge of residential wastewater
Preservation of coastal water quality is critical in the U.S. Virgin Islands, where tourism is the main industry. Public sewer systems do not extend throughout the islands, and there is a large dependency on conventional septic tank/seepage pit systems. Unfortunately, the hilly terrain of the islands, the shallow soils, and in many instances the dense residential development are factors that contribute to the failure of conventional systems and subsequent discharge of improperly treated waste.

The Virgin Islands Department of Planning and Natural Resources (DPNR), through a study conducted by Kimball-Chase, documented that a major source of contamination of beaches and other coastal areas in the U.S. Virgin Islands is failing septic systems. These widely used units are failing because they lack the 2 to 3 feet of pervious soil through which effluent should pass to be properly treated.

An innovative solution

To remedy this problem, DPNR and the University of the Virgin Islands (UVI) entered into a partnership. DPNR asked the public for proposals for the design and installation of affordable alternative systems that would treat residential wastewater using nonmechanical means and would require minimal maintenance. Two of the designs submitted were selected, and the systems were installed at two residences where conventional systems had failed to meet treatment needs. The new systems used a series of closed cells filled with gravel and soil in which plants with high water uptake rates were planted. In addition, the systems blended in with the topography of the sites and were installed in such a way that they enhanced the appearance of the properties.

DPNR observed the installation of the systems, and UVI closely monitored their performance for a 6-month period following their installation. Plants thrived in the systems, and it was interesting to note that at one site exotic flowers fared better than anywhere else on the island. No discharge of effluent from the systems, odor, or any other unpleasant effects were recognized at either site. Effluent quality was found to improve as it passed through the systems. Most significantly, because no discharge was ever noted, the surrounding environment was never threatened.

The pilot alternative systems for treatment of residential wastewater have a high potential for reducing the pollution threat to the fragile coastal ecosystems of the Virgin Islands. Thus far, they have proven to be affordable to install, effective, and easy to maintain. The systems are being closely monitored to assess their performance over an extended period.

Because of the high public interest in these systems, DPNR has developed a handbook available to the public to guide in their design, construction, and use. DPNR is also proposing regulations that would permit use of these systems in areas where sensitive environmental factors preclude the installation of conventional septic tank systems. The innovative systems have the potential to maintain high environmental quality for present and future generations in the U.S. Virgin Islands.

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