Application of WQMAP to Upper Narragansett Bay, Rhode Island

Swanson, J. C.; Mendelsohn, D. L.; ,

Application of WQMAP to Upper Narragansett Bay, Rhode Island

by J. C. Swanson, Applied Science Associates, Inc, Narragansett, United States,
D. L. Mendelsohn, Applied Science Associates, Inc, Narragansett, United States,

Document Type: Proceeding Paper

Part of: Estuarine and Coastal Modeling

Abstract:

WQMAP is a PC-based water quality analysis tool linking numerical models and environmental data with a geographic information and display system. For this application the model set consisted of boundary-fitted hydrodynamic and pollutant transport finite difference models. WQMAP is used to display model results such as time varying velocity vectors and pollutant contours, maximum pollutant concentrations and other post processing products. An application of WQMAP was made to the Providence River and Upper Narragansett Bay (PR/UB) in Rhode Island. Storm induced combined sewer overflows (CSOs) cause the dumping of untreated sewage into the receiving waters at 85 sites at the head of Narragansett Bay. The impacts on the shellfishing industry include the conditional closure of prime beds for more than 200 days a year. The purpose of the study was to evaluate a series of mitigative measures designed to reduce the deleterious effects of fecal coliform (FC) contamination in the PR/UB and specifically the conditional closure areas. These measures included a set of near surface storage facilities, tunnel options, and combinations of both. A series of 13 mitigation alternatives was developed. These alternatives consisted of near surface storage and treatment, tunnel storage and treatment, and a mixture of both types. Time series of loads from each CSO, alternative facility and other sources were developed as model input to the PR/UB model. The pollutant loading was analyzed with respect to four design storms of 3, 6, 12, and 24 month return frequency.

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