There are 86 combined sewer overflow points that discharge a combination of untreated residential sewage, industrial process wastewater, and stormwater runoff into the receiving waters of Rhode Island within the Narragansett Bay Commission service area. Combined sewer overflows (CSOs) are known to be major contributors of fecal coliform and floatables loadings into Upper Narragansett Bay. In addition these overflows, to a lesser degree, are responsible for increased loadings of Biochemical Oxygen Demand, suspended solids, metals and nutrients.

CSOs are in violation of the Clean Water Act since they are considered to be a point source of pollution discharging into waters of the United States. The U.S. Environmental Protection Agency (EPA) drafted its first National CSO Strategy in 1989. The EPA CSO Strategy was aimed at providing states and municipalities with guidelines for abating combined sewer overflows. Rhode Island, a delegated state under the Clean Water Act, too has produced a policy which calls for the implementation of control measures concerning CSOs. In 1994, EPA amended its CSO policy which provided states with a more specific set of guidelines. The Narragansett Bay Commission, which is responsible for implementing these control measures has proposed a plan that consists of deep rock tunnels and near surface storage facilities that will serve to store the overflows which will be treated at a later time.

The main focus of my thesis concentrates on the costs and benefits associated with the recommended plan for CSO abatement. In addition, potential funding sources and plans of finance are described. The data for this thesis were obtained from a variety of sources. These sources included previous CSO studies, interviews with various government and non- government groups, and attendance at various CSO Stakeholders meetings.

Upon examination of the estimated $500 million cost for CSO abatement and subsequent benefits that are to result from the implementation of this plan, I conclude that other alternatives should be explored. The easily quantifiable benefits are clearly outweighed by the costs. In this situation many of the benefits associated with the recommended plan were difficult if not impossible to monetize, thus creating a cost intensive analysis. Additionally, changes have to be made in Rhode Island's CSO policy and the State's approach to CSO abatement. A more site-specific approach should be taken to produce a customized plan for abatement of wet weather flows.