Engineering geological properties of oil-contaminated granitic and metasedimentary soils

Abstract

Hidrocarbon is a light-non aqueous phase liquid, LNAPL. It cause contamination because of its properties that not soluble in water. These contaminants comes from oil spill at the surface. Basic properties includes sieve analysis, specific gravity test and x-ray diffraction (XRD). While the geotechnical properties include Atterberg limit, compaction and triaxial test to the contaminated and non-contaminated sample. Contaminated samples are prepared by adding 4%, 8%, 12% and 16% hidrocarbon from the dry weight of sample into the sample while non-contaminated sample also been used for comparison. XRD result of granite sample shows that it consists of quartz, kaolinite and gibbsite while metasediments only consists of quartz and kaolinite. Spesific gravity value of the granite soil is 2.56 while metasediments is 2.61. Partical size distribution result shows that granite consists of 38% sands, 33% silt and 4% clay while metasediment consists of 4% sand. 43% silt dan 29% clay. Despite of that, Atterberg limits test resulted decreasing value of plastic and liquid limit with increasing the percentage of oil. Also, compaction test shows decreasing trend; means that decreasing value of maximum dry density and optimum water content with increasing oil percentage. Triaxial test results show that shear strength.Ci.for 0%-16% metasediment's samples is ranging from 27kPa until8kPafor while granite's sample is from 28kPa until 6kPa. C, values is decreasing with increasing of oil percentage in each samples.