title: An assessment of subsurface contamination of an urban coastal aquifer due to oil spill.
abstract: Incidences of leakages of chemicals from underground oil storage tanks or oil-carrying pipelines have posed huge threat to the coastal aquifers around the world. One such leak was recently identified and notified by the people of Tondiarpet, Chennai, India. The assessment of the contamination level was done by obtaining electrical resistivity maps of the subsurface, drilling of 20 new borewells for soil and water analysis, and testing the water quality of 30 existing borewells. Samples were collected from the borewells, and observations were made that included parameters such as odor, moisture, contamination characteristics, lithology, groundwater level, thickness of the free product that are used to demarcate the extent of soil, and water contamination. Furthermore, a multigas detector was used to detect hydrocarbon presence as soil vapor. Moreover, to capture the transport of dissolved hydrocarbons, 10 samples were collected in the periphery of the study area and were analyzed for the presence of petroleum hydrocarbon and polyaromatic hydrocarbon. Analysis of the data indicated the presence of free-phase hydrocarbon in soil and groundwater close to the junction of Thiruvottiyur high (TH) road (TH) and Varadaja Perumal Koil (VPK) street. Although the contaminant plume is confined to a limited area, it has spread more to the southern and eastern side of the pipeline possibly due to continuous abstraction of groundwater by residential apartments. After cutting a trench along the VPK street and plotting of the plume delineation map, observations indicated that the source of the hydrocarbon leak is present in VPK street close to TH road. A multipronged strategy was suggested targeting the remediation of oil in various phases.
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology Madras, Environmental and Water Resources Engineering, Chennai, Tamil Nadu, 600036, India. indunambi@iitm.ac.in.
authors.forename: Indumathi M
authors.initials: IM
authors.lastname: Nambi
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology Madras, Environmental and Water Resources Engineering, Chennai, Tamil Nadu, 600036, India.
authors.forename: Bokam
authors.initials: B
authors.lastname: Rajasekhar
authors.affiliation: Department of Civil Engineering, Indian Institute of Technology Madras, Environmental and Water Resources Engineering, Chennai, Tamil Nadu, 600036, India.
authors.forename: Vijay
authors.initials: V
authors.lastname: Loganathan
authors.affiliation: Department of Chemical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
authors.forename: R
authors.initials: R
authors.lastname: RaviKrishna
mesh_terms: D004784:Environmental Monitoring; D060587:Groundwater / Q000032:analysis / Q000737:chemistry*; D006838:Hydrocarbons / Q000032:analysis; D007194:India; D010578:Petroleum / Q000032:analysis*; D059392:Petroleum Pollution / Q000032:analysis*; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D014876:Water Pollution / Q000032:analysis
chemical_list: D006838:Hydrocarbons; D010578:Petroleum; D012987:Soil; D012989:Soil Pollutants; D014874:Water Pollutants, Chemical
keywords: Environmental assessment; Hydrocarbon; LNAPL; North Chennai; Oil spill; Tamil Nadu