A Green Improvement project at the wastewater treatment plant in the Village of Lyons, N.Y. (population 4,000), shows you don’t have to be big to do big things. The installation of a green roof on the plant’s solids building, combined with other energy-savings upgrades, will save the plant about 15 percent in future energy costs.

“Although it can’t be seen from ground level, the rainwater impact of the green roof adds to the overall operations and maintenance savings of the plant,” says Mark Chadwick, foreman of the contact stabilization/aerated activated sludge plant (0.75 mgd design flow, 0.35 mgd average).

 

Less runoff

Constructed of multilayer pregrown modules, the 1,000-square-foot green roof reduces stormwater runoff by capturing up to 30,000 gallons per year and recycling it through a 2,500-gallon buried holding tank. From there, the runoff is used for irrigation, cleaning equipment, and other nonpotable purposes.

Each 3- by 6-foot premanufactured module contains self-sustaining layers of soil and attractive plants and grasses. The roof requires no maintenance or mowing. In addition to harvesting rainwater, the greenery also lightens heating and cooling demand, while protecting and extending the life of the roof’s waterproofing membrane.

The $607,000 improvement project was made possible through a 90 percent grant from the New York Environmental Facilities Corporation Green Innovative Grant Program, says village mayor Corrine Kleisle. In-kind services, such as excavation and grading, were provided by village employees. “We are very fortunate to have such an outstanding crew in our Department of Public Works,” she says.

 

Blower control

Other elements of the project will contribute significantly to energy savings, says Chadwick. Original plans called for retrofitting two 40 hp and one 50 hp aerator blowers with variable-speed drives controlled through dissolved oxygen sensors. This approach will enable airflow based on demand. At present, at least two blowers run constantly at full capacity regardless of dissolved oxygen content in the aeration basins.

The village is also considering installing a 50 hp turbo blower to handle the entire load for even greater efficiency, says Chadwick. The two 40 hp centrifugal blowers would be kept for backup. Either upgrade would be the project’s largest contributor to energy savings.

To achieve further savings, the village replaced incandescent light bulbs with LED fixtures in the main control building, and installed motion sensors now control the lighting. Exterior lights were fitted with sensors to provide dusk to dawn lighting.

 

Looking to the sun

Another big contribution to energy savings comes from solar panels. The 40 kW array of photovoltaic panels is the most obvious change to the plant’s appearance: It can be seen from the roadway in front of the plant. The panels are expected to reduce treatment electric utility demand by 8 percent and save the village about $5,000 a year.

Three years ago, village officials surveyed all the municipal buildings in search of upgrades that would provide sustainable benefits, and they chose the wastewater treatment plant. “This was an excellent project, but it’s too soon to determine exactly the overall efficiencies we will gain,” Kleisle says. “That will take a few years.”