Travelers along I-89 in Sharon, Vt., now have more than one reason to pull over at the rest stop. The $6.3 million expanded facility opened in September with a new wastewater treatment system that includes a tropical plant greenhouse and a large Vietnam veterans memorial.

With the rest stop on the verge of closing in the mid-1990s because of a failing sewage treatment system, a coalition of veterans lobbied Gov. Howard Dean and the legislature to spare the area, where a Vietnam veterans memorial — a simple granite obelisk — had been standing for more than 20 years. Because of public pressure, the legislature spared the rest area and committed to building a larger memorial while fixing the site's sewage treatment problems. They decided the redesigned site should feature the wastewater treatment system as a greenspace amenity and educational attraction.

Officials in the Department of Building and General Services began searching for an ecologically based treatment system that would remedy existing issues, expand capacity and process wastewater to use onsite to flush toilets. The rest stop was not large enough for conventional on-site treatment systems, such as recirculating gravel filters, or advanced filter systems and activated sludge package plants. So, the state turned to Taos, N.M.-based Living Designs Group and Concord, Mass.-based The RETEC Group to design an onsite treatment and reuse system that uses a combination of bacteria, microorganisms, small invertebrates and plants.

All wastewater from toilets and sinks is collected in an underground storage tank where it is pumped into the treatment system in the facility's greenhouse wing, which includes a raised walkway and signs describing the ecological processes. The first two tanks in the process provide air to bacteria in the wastewater, which begin to consume the nutrients. Odorous gasses are intercepted and removed by biofilters sitting on top of the tanks, which contain peat moss, plants and soil microbes.

The wastewater then flows downstream into the hydroponic reactors where tropical wetland plants are suspended over tanks of partially treated sewage so their roots hang into the water. The plants catalyze an ecology of microorganisms, which colonize their root surfaces and consume the bacterial cells generated in the covered aerobic reactors. Aerators in the reactors keep the bacterial cells suspended and provide oxygen for the grazers. Next, a clarifier collects any unconsumed bacterial cells, producing effluent that is disinfected with chlorine to remove potential pathogens before it is pumped to the toilets. As a final precaution, the treated wastewater is died blue, and signs in the bathrooms indicate that toilet water is not for potable consumption. The reused wastewater will reduce the rest stop's overall water use by approximately 60 percent, or 1.4 million gallons per year. Excess wastewater is discharged to the environment and will not adversely affect local ecosystems.

A focal point of the original rest stop, the Vietnam veterans memorial remains outside, housed in a small granite amphitheater, which lists the 138 Vermonters killed during that era. A complementary glass monument stands in the center of the 6,000-square-foot rest area with the names of all 7,230 state residents who served in Vietnam. A timeline of major events in the United States, Vermont and in Vietnam in the 1960s and 1970s is displayed on a nearby stone wall.