Geo-environmental site investigation for Tunceli, Turkey municipal solid waste disposal site Ayten Öztüfekçi Önal a, 1 , Deniz Demirbilek b, 1 , Veysel Demir b, ⁎ a Department of Geological Engineering, Tunceli University, Tunceli, Turkey b Department of Environmental Engineering, Tunceli University, Tunceli, Turkey abstract article info Article history: Received 8 August 2012 Received in revised form 12 March 2013 Accepted 18 March 2013 Available online 28 March 2013 Keywords: Solid waste Site investigation Unsanitary storage Environmental geotechnics The environmental and geological condition of a current solid waste disposal site in the city of Tunceli, Turkey was investigated. Improper geological structure and soil properties of this unsanitary solid waste storage site as well as leachate from this site caused significant pollution in air, soil, and surface water. Natural soil character- istics and geology of the site are presented in this paper. Petrographic properties of vulcanized rubber rocks com- posed of tuff and volcanic sandstone at the bottom of storage sites and the mineralogical composition of the base composed of these rocks were examined. Permeability of the natural soil and index properties were determined using soil mechanics experiments (moisture content, specific gravity, Atterberg limit tests, sieve analysis, hydrometer analysis, falling-head permeability test, and standard proctor test) conducted on disturbed samples collected from excavated sites and the relationship between mineralogical composition and soil hydraulic behav- ior was investigated. Natural soil samples of six different parts of the site indicated that, the soil class in four samples is silty sands, sand–silt mixtures, one is clayey sands, sand–clay mixtures and one is clayey silts with slight plasticity. The values obtained using permeability tests for subsoil samples vary from 10 -5 to 10 -8 cm/s. Low permeability (10 -7 and 10 -8 cm/s) at the south part of the site increases to 10 -5 cm/s at the natural soil of the North side. Extensively faulted and fissured volcanic sandstone levels at the site give potential to waste leachate to reach deep levels. The soil composition, hydraulic conductivity, topographic conditions, and other location criteria in the current solid waste disposal site showed that the current disposal site is not suitable for this purpose. © 2013 Elsevier B.V. All rights reserved. 1. Introduction Unsanitary solid disposal sites have been generally considered as an irregular solution of the waste disposal problem and most of them are used without sufficient geological, hydrogeological and environmental assessments. Environmental problems are expected to occur if no secure and environmental friendly measures associated with develop- ment are carried out (Bruno, 2007; Depountis et al., 2009). A significant source of natural soil, water, and air contamination can be caused from municipal and environmental waste disposal sites. There have been many studies conducted to prevent the pollution of the surface and groundwater from solid waste's leachate (Wright et al., 1988). Different geoenvironmental site investigation techniques can be applied to assess possible contamination from waste disposal sites (Mondelli et al., 2007). To minimize environmental risk factors, sanitary solid waste dis- posal sites are constructed after sufficient geological and environmental assessments such as geotechnics of the site, hydrogeology, seismicity, etc. (Simsek et al., 2005; Sener et al., 2011). Open dumping is a common practice in Turkey. Around 67% of the generated municipal solid waste has been dumped at open dumps (Nas et al., 2008). Environmental problems caused by solid disposal such as odor problems, release of gases to atmosphere, risk of explosion or fire, uncontrolled leachate to surface and groundwater, and undesired visual pollution can easily be seen in these types of sites. In addition to these problems, even medical waste can be found in these sites. A site that is planned to become a sanitary landfill must initially be evaluated and assessed in details based on mineralogical and index properties of the subsoil and geological formations such as rock types, tectonic properties, the depth of groundwater level, etc. According to the solid waste control regulation of Turkey dated 1991 (14.3.1991-20814; amendment 05.04.2005-25777) the depth of the groundwater level must be at least 30–50 m and subsoil should have low permeability (10 -8 m/s) thick clay segment or natural subsoil should have between 10 -6 and 10 -8 cm/s permeability (Chapius, 1990). An impermeable zone separating aquifer and subsoil of the site can block leaching process from the wastes. The current practice is to try hydraulical isolation of the waste in order to minimize the adverse effects of the disposal site on groundwater (Kayabali, 1996). Engineering Geology 159 (2013) 76–82 ⁎ Corresponding author. Tel.: +90 428 213 1794; fax: +90 428 213 1861. E-mail addresses: aytenoztufekci@gmail.com (A. Öztüfekçi Önal), demirbilek.deniz@hotmail.com (D. Demirbilek), veyseldemir@tunceli.edu.tr (V. Demir). 1 Tel.: +90 428 213 1794; fax: +90 428 213 1861. 0013-7952/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.enggeo.2013.03.014 Contents lists available at SciVerse ScienceDirect Engineering Geology journal homepage: www.elsevier.com/locate/enggeo