PART 2: APPROACHING NON-POINT SOURCE POLLUTION 

 CONTROL VIA SOURCE CONTROLS 



2.1 TNnTVTniJAL SEWAGE DTSPOSAT, SYSTKMS 



Irm-oduction 



When properly sited, designed, installed and maintained, individual sewage disposal 

 systems (ISDS) can be used to treat household waste simply and effectively. However, 

 discharge of improperly treated effluent to groundwater and surface waters can create 

 significant hazards to human health, can degrade potable water supplies, and can promote 

 eutrophication leading to loss of valuable fisheries habitat and closure of recreational areas. 



ISDS effluent contains several types of pollutants including: nutrients; conventional 

 pollutants such as suspended solids, oil, and grease; pathogens, including bacteria and 

 viruses; and toxic chemicals such as synthetic organics and metals. Of these, nutrient and 

 pathogen loadings present the greatest concern as pollutants of receiving waters, followed 

 by organics. Suspended solids and metals should be removed by a properly functioning 

 system. Oil and grease may clog leach fields, limiting treatment capacity. 



Although scientific knowledge concerning the biochemical fate of these pollutants, and 

 their interactions in waterbodies, is incomplete, sufficient data exists to justify a high 

 degree of concern where dense development has led to groundwater contamination, and 

 where effluent is transported into poorly flushed waterbodies or embayments. These 

 issues present potential health hazards in the Bay watershed as well as in all affected 

 portions of the state. 



THE ISDS TASK FORCE 



In Rhode Island, recognition of existing and potential hazards presented by ISDS led to 

 the formation of a technical advisory group known as the ISDS Task Force, which met 

 between April, 1986 and January, 1987 to investigate alternative solutions to problems of 

 older, substandard septic systems and to develop siting and design criteria for new systems 

 in sensitive areas. 



This group of engineering, planning, and research professionals formed three 

 subcommittees to research, evaluate, and prepare preliminary findings with respect to ISDS 

 maintenance and education, regulations for new systems, including those in critical areas, 

 and innovative systems. In approaching their tasks of evaluation, the subcomminees 

 undertook surveys of current Uterature and other state regulatory programs to assess effects 

 of ISDS, and alternate controls. 



The subcommittees prepared analyses of current research findings showing ISDS as 

 sources of non-conventional pollutants, microbial contaminants, and excess nutrient loads. 

 Other state ISDS regulations were examined, innovative systems were evaluated, and state 

 and local regulations pertaining to ISDS maintenance were reviewed. Using these research 

 results, the Task Force prepared a comprehensive set of findings and recommendations to 

 address means to control effluent from ISDS. 



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