ISDS 



existing and potential sources of contamination have been found, the visible ISDS 

 problems formed the basis for significant policy change in the towns, and spuired 

 development of a Special Area Management plan for the Salt Pond region. 



Given present inputs of sewage-related pollutants to the Bay proper from waste water 

 treatment facilities and CSOs, the loadings attributable to ISDS cannot be identified. 

 Nevertheless, watershed and baseflow loadings may be significant, and are considered to 

 be of key importance in themselves in the context of the Narragansett Bay Project 

 Therefore, Bay basin areas of clear current or potential concern must be considered in this 

 planning analysis. 



Important sections of the Bay watershed are characterized by upland till soils with severe 

 limitations for ISDS due to steep slopes, slow permeability, seasonal high water table and 

 shallow depth to impermeable layer. Impermeable soils with perched, seasonal high water 

 table or impermeable layer or layers are susceptible to ISDS failure through: a) effluent 

 siufacing and overland flow to water bodies; b) inadequate unsaturated separation distance 

 to limiting layers, resulting in movement of nutrients and biological pathogens through 

 groundwater, lateral movement along fragipan layer, or channeling through bedrock 

 crevices. 



Along the western shoreline of Narragansett Bay, as well as in the coastal ponds 

 watershai, soils arc predominantly coarse textured glacial outwash, characterized by 

 excessively rapid permeability. Upland till soils also associated with these areas may be 

 stony and excessively permeable, or may exhibit shallow high water table. Coastal sands 

 are characterized by fluctuating high water table and have severe flooding potential. 



Many areas of the Bay watershed experience ISDS overflows, and show evidence of 

 groundwater and well contamination. Bacterial contamination linked to ISDS effluent has 

 forced closure of shellfish beds in the Salt Ponds, and may be contributing to loss of 

 shellfish resources in shallow, semi-enclosed Bay estuaries which are incompletely 

 flushed. 



GENERAL FINDINGS 



Fundamental Issues 



In general, Rhode Island's ISDS regulations as written provide satisfactory 

 guidance to ensure proper functioning of ISDS systems. However, a 

 number of fundamental problems limit the effectiveness of the regulations 

 in addressing impacts of the systems on resource areas. In addition, 

 institutional and political issues affect the involved agencies' flexibility in 

 moving to address broader impact-related concerns. 



Secondly, in spite of a wealth of available documentation regarding the costs of sprawl 

 and the need to channel growth into areas where waste disposal can be made effective and 

 safe, development in the Bay basin continues to proceed in a manner which 

 largely ignores the pervasive impacts which improperly treated sewage 

 effluent can create across property lines and jurisdictional boundaries, the 

 costs and benefits which both ISDS and community sewers present, and 

 other issues of concern. 



48 



