Stormwater and Sediment 



indicated that entry of standard urban and highway runoff is substantially affected by 

 greater traffic volumes and by the destruction of wetiands. 



Waste Oil Disposal 



In order to determine the Bay pollutant loading attributable to improper disposal of used 

 crankcase oil, Hoffinan et al. (1981) surveyed 1000 Providence residents. Waste 

 lubricating oil is disposed of in various ways by the 35 percent of Providence residents 

 who change their own automobile lubricating oil (Hoffman et al., 1980). Methods 

 included garbage can disposal (41 percent), backyard dumping (30 percent), disposal down 

 sewers or storm drains (8 percent), return to a service station (7 percent), pouring the oil on 

 the road (5 percent), and disposal at the town dump (3 percent). 



On a weight basis, road or sewer disposal can account for 44 metric tons of 

 hydrocarbons discharged into the city's combined storm and sanitary sewage treatment 

 system, or 19 percent of the total hydrocarbons discharged by the city plant Disposal on 

 land, or in dumps (direcdy or via solid waste collection) also contributes to deterioration of 

 Bay water quality, due to contamination of land runoff, urban runoff, and groundwater, 

 though inputs due to these sources are difficult to measure. 



Using the Providence results to predict waste oil contributions of each city and town in 

 the Bay drainage basin, the same authors classified each town as urban, suburban, or rural 

 and applied appropriate data sets to derive metals and PAH constituent loadings. The 

 authors calculated that waste oil dumped down sewers alone (not including CSOs, overland 

 flow, or other disposal methods) accounts for 132 tons per year contribution to the 

 watershed. 



Hydrocarbons 



Within the major classes of hydrocarbons, sources vary significantiy. While urban 

 runoff accounts for 48 percent of total hydrocarbons, it contributes only 3 percent of low 

 molecular weight PAHs, which are found in high concentrations in used crankcase oil and 

 in drips of crankcase oil on the street surface, but are weathered prior to incorporation in 

 urban runoff. In petroleum products discharged directiy to the sewer system, the low 

 molecular weight PAHs are not exposed to weathering, and are preserved. Heavier PAHs 

 formed during fossil fuel combustion are not weathered to the extent that lighter petroleum 

 compounds are, but are at lower concentrations in sewage and crankcase oil, so that 

 atmospheric deposition becomes the principal source of these compounds (Hoffman, 

 1985). Urban runoff accounts for 71 percent of total high molecular weight PAH inputs to 

 the Bay. The annual rate of total PAH and total aromatic hydrocarbon urban runoff inputs 

 to the upper Bay watershed is approximately 1.0 and 51 grams per capita per year, 

 respectively (Hoffman et al., 1984). 



Hydrocarbon input budgets for the Narragansett Bay watershed have been developed 

 which distinguish between spillage and other inputs contributing to runoff or discharge via 

 sewage treatment plants or CSOs. Latimer (1984) collected oil spill data from three state 

 and federal data sets and showed that the amount of oil spilled and reaching receiving water 

 varied broadly, ranging from 2830 gallons in 1982 to 35,587 gallons in 1976. Fuel oil is 

 the oil most frequendy spilled in the Bay area, and, in terms of volume, the greatest spillage 

 occurs at bulk oil storage teraiinals followed by truck accidents and industrial discharges. 



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