Thursday, June 11, 2009

Article: The Athens Alternative

The May/June issue of Government Engineering magazine features an article about Athens, Tennessee. Athens replaced its failing gravity sewer system with an E/One low pressure sewer LPS system.

The gravity sewer had been constructed during the 1960's. The system experienced huge amounts of infiltration and inflow, causing overflows and leading to a moratorium on new sewer connections in 1990. As a result, economic growth in the town suffered. Renovation of the wastewater treatment plant helped, but was still not a solution.

Railroad Avenue is a relatively flat but rocky area with high water tables. The Athens Utility Board (AUB) decided to abandon the gravity sewer system in this area and install a low pressure sewer system with E/One grinder pumps.

In 2003, with the gravity system, pump stations in the area recorded nine overflow events for a total of 500,000 gallons of water overflow. After the LPS system was installed, there were zero overflow events and zero gallons of infiltration. Records indicate that 27.5 million gallons per year less flows to the treatment plant. This translates to a yearly savings of $89,212 in treatment costs alone. And, because stop-ups have also been eliminated, AUB has experienced fewer maintenance requirements and less overtime, providing additional cost savings.

Installation costs also offered a savings of 25 to 35 percent versus gravity, even with the cost of the gravity system abandonment included. Directional drilling had been used for much of the installation of the main, which offers little disruption to homeowners' yards.

AUB is planning to attack other problematic areas and is considering grinder pumps for other areas of the town.