APPLICATION OF U.S. DECENTRALIZED WASTEWATER TECHNOLOGIES IN EASTERN EUROPE: CASE STUDY OF THE RABA RIVER WATERSHED, POLAND

The Dobczyce Reservoir, located within Poland's Raba River watershed, provides a majority of the City of Kraków's drinking water supply in addition to serving a number of smaller communities in the watershed. The reservoir, constructed in 1986, is in the early stages of eutrophication as a result of nutrient inputs from inadequate wastewater treatment and extensive agricultural land uses.An existing comprehensive management plan for the watershed recommended centralized wastewater collection and treatment, requiring long and expensive collection systems. In 2001, a Coler & Colantonio project team completed a new Feasibility Study designed to find a more cost-effective approach to achieving the region's water quality objectives. The study describes a new decentralized paradigm and recommends the use of low-pressure collection systems, small modular wastewater treatment plants, and a sludge pasteurization technology. By drastically reducing the length of required collection systems and utilizing efficient new treatment technologies, significant cost savings are shown to be achievable. The Feasibility Study has resulted in two demonstration projects thus far: a low-pressure collection system and a small modular wastewater treatment plant.The first demonstration project (installed November 2002) is a low-pressure collection system connecting a group of homes located along the banks of the Dobczyce Reservoir to an existing gravity sewer at a higher elevation. The project avoids the deep excavation, redundant piping, and expensive pump station that would have been required to connect these houses to the existing sewer network via a traditional collection system. The second demonstration project is a 47,600-gpd Amphidrome™ wastewater treatment plant (to be installed Spring 2004) serving a small community on a tributary stream to the Dobczyce Reservoir. The plant will remove nitrogen and phosphorus as required by European Union law and all tanks will be located underground in order to minimize visual impacts. By locating this small modular plant within the community where wastewater is generated, the need for constructing long force mains through the region's hilly terrain is eliminated.This paper summarizes the Feasibility Study conclusions, describes the implementation of the demonstration projects, and details the applicability of the recommended technologies throughout the region. Discussion includes technical design aspects, relative costs and benefits, progress of present demonstration projects, and unique challenges faced while working in a foreign country.