National Bureau of Standards Special Publication 556. Proceedings of a Workshop on Measurements and Standards for Recycled 011 - II held at NBS, Gaithersburg, Maryland, November 29 and 30, 1977. (Issued September 1979) RUNOFF OF OILS FROM RURAL ROADS TREATED TO SUPPRESS DUST Frank J. Freestone U.S. Environmental Protection Agency Abstract Two rural roads in Readington Township, Hunterdon County, New Jersey, which are treated with waste crankcase oils, were examined to determine whether or not the oil leaves the road. Analyses indicated that roughly 1 percent of the total oil estimated to have been applied remains in the top inch of road surface material, that oil penetration below the top inch of road was minimal, and that lead was concentrated (≈ 200 mg/kg) in the top inch of road material. Laboratory weathering experiments indicate an estimated maximum weathering loss of oil from a road would be approximately 18 percent. Rain runoff studies on simulated rural road surfaces indicated two mechanisms by which oil is transported from the road: leaching of the oil by flotation, and flotation of oil-wet soil particles. The greatest oil transport is during the first few rains after oil application, with continuous, low-level leaching during each subsequent rain. Analyses of soil samples taken from a field subjected to runoff from an oiled road showed significantly higher lead content than soil taken from a field 150 feet from the road. Five photographs clearly showing oil leaching from the test road surface and entering drainage ditches after a rain are presented. Introduction An estimated 200 million gallons of waste crankcase oils and an unknown quantity of other waste oils are applied yearly to rural roads in this country for the purpose of dust control [1]. The waste crankcase oil contains approximately 1 percent by weight of lead compounds, which amounts to 14.0 million pounds of lead applied yearly to roads. In Readington Township, Hunterdon County, New Jersey, dirt roads are oiled twice yearly, in June and August, to suppress dust in front of houses along the roads. Two of the roads in Readington Township were examined to determine if the waste oils were leaving the road surfaces. The problem was approached by attempting a mass balance to determine the amount of oil applied to the road surface, the amount remaining in the road surface, and the amounts leaving the surface by various mechanisms. Additionally, analyses were made to determine if the lead component of the oil were also leaving the road. The top inch of road surface material extending the width of the road between drainage ditches was considered the object of the mass balance. Oil could leave the road surface by several mechanisms: volatilization; runoff mechanisms; adhesion to vehicles passing (with possible redeposition at other areas); adhesion to dust particles with wind transport from the road surface; or penetration into the road material below the surface, possibly through capillary action. Additionally, the oil remaining in the road surface could be biodegraded. Some of the variables affecting the above movements are oil application history, frequency, quantity per application; oil type, source, viscosity, density, volatility, presence of surface active agents; road conditions: crown, slope, compaction, density 1 Underlined numbers in brackets indicate the literature references at the end of this report. . and porosity of soil, soil grain size distribution; traffic conditions on the road; weather conditions: time to the first rain after oil application, total yearly rainfall, temperature affecting volatility of oil, wind affecting dust transport; and factors affecting biodegradation: presence of oil-consuming microorganisms, road surface moisture content, and presence of nitrogen and phosphorus nutrients. With such a range of variables and oil movement mechanisms, precise quantitation of oil movement applicable to numerous roads is beyond the scope of this study. However, with information available, estimates may be made of some of the more significant movements of oil. Oiling History Experimental No records are available of the true oiling history of the test roads. The Readington Township Clerk indicates that the roads have been oiled twice yearly for at least 12 years. The waste oil collector who has done the oiling indicates the roads have been oiled by him for 16 years (since 1955) and by others before him for an unknown number of years. Road oiling to lay dust is usually done in other townships in response to complaints from persons living along the roads; thus, during dry years the roads may be oiled twice, and in wet years once or not at all. A conservative estimate of the total number of oilings on the test roads is 24, considering 2 oilings per year for 12 years, with the understanding noted above. Oil Type and Application Rate The oil type and application rate is highly variable. Conversations with the waste oil collector who oils the Readington roads indicate that he uses a mixture of Nos. 4, 5, or 6 fuel oil sludge obtained from tank cleaning operations, and waste crankcase oils collected from service stations in the Trenton, New Jersey, area. The ratio of the mixture depends upon the availability of the fuel oil sludge, and ranges from 15 to 30 percent sludge, the balance being waste crankcase oils. A waste oil collector from the Boston area who oils roads in New England and upstate New York indicates that he uses waste water-soluble cutting oils, waste crankcase oils, terminal waste oils (from the oil/water separator on a water effluent), and oils from tank-cleaning operations. The oil applied to a given road depends on the availability of oils at the time of the oiling and follows no particular pattern. Application rate is apparently related to the qualitative judgment of the operator of the truck doing the oiling and ranges from 0.025 to 0.05 gallon per square foot of road surface, with the 0.05 figure being used on the test roads. The two test roads were sampled in four oiled locations and in two unoiled locations to determine concentration of hydrocarbons versus depth. In all oiled locations the top inch of road surface showed the greatest concentration of oil, an average of 0.74 percent weight, with trace quantities of oils at lower depths (which may be contamination attributable to the sampling technique). The road surface material was made up predominately of clay, with some sand. No attempt was made to characterize the material in more detail. Complete sampling data are presented in table 1. Estimate of Oil Remaining in Test Road Oil Applied 0.05 gal/ft2 per application 2 applications/yr x 12 yrs 24 applications 0.05 x 24 = 1.2 gal/ft2 total applied oil 1.2 gal/ft2 x 9 ft2/yd2 - 10.8 gal/yd2 Oil penetrates 1 inch; consider unit of road surface to be 1 yd3 10.8 gal/yd2 x 36 yd2/yd3 (for depth of 1 inch) - 388.8 gal/yd3 For 12 yrs of application = 2930.25 lb oil/yd3 road surface Oil in road surface: average concentration = 0.74 percent weight To estimate the level of volatility of waste oil applied to Readington Township roads, a laboratory weathering experiment was performed. Waste oil obtained from the waste oil collector and being of a "typical" composition of approximately 20-percent No. 6 sludge and 80-percent waste crankcase oil was placed in shallow 11-inch by 14-inch laboratory pans under infrared lamps and in the draft of a fan. The surface temperature of the oil was held at 100° F for a duration of 288 hours to achieve a high, though arbitrary, weathering stress. At the end of the weathering period, a 16- to 18-percent change in weight of oil was noted. |