Cem B. Avci

Evaluation of flow leakage through abandoned wells and boreholes

Flow leakage through abandoned wells and improperly plugged boreholes drilled between hydrogeologically separated water-bearing zones represent potential pathways of contamination. The present study provides an analytical evaluation of the transient flow rate through these artificial conduits and the resulting hydraulic head distributions when (1) artificial gradients are created by an injection well operating in one of the aquifers or (2) natural hydraulic head differences are present between two confined aquifers. The analysis is conducted by solving the groundwater flow equations in the confined aquifers that are coupled by the flow through the well or borehole. A case study was investigated involving contamination leakage through abandoned wells and improperly plugged boreholes caused by the operation of deep waste injection wells.

Assessment of advective–dispersive contaminant transport in heterogeneous aquifers using a meshless method

Groundwater solute transport phenomena typically occur in water-bearing zones with heterogeneous solute dispersive characteristics and/or media hydraulic properties. A radial basis function collocation method (RBFCM)-based numerical method was developed in order to investigate the ability of RBFCM to accurately portray solute transport phenomena under heterogeneous conditions. Simulations were performed for 1-D and 2-D transport scenarios in which scale-dependent dispersivity fields were taken into consideration and compared with available analytical solutions. Different radial basis functions (RBFs) were employed for assessing the sensitivity of the present method on the selected RBFs. The simulation results were also compared with the results of MT3DMS which is a modular three-dimensional transport model with alternative solution schemes including the method of characteristics, the implicit central finite difference and the third order total variation diminishing finite volume. The proposed model was also used to simulate a real case condition where solute transport through a two-layer soil medium had been investigated experimentally. The results showed that RBFCM represented a powerful tool for predicting the solute transport occurrence under heterogeneous conditions with high accuracy.

Environmental and Social Risk Management in Emerging Economies: An Analysis of Turkish Financial Institution Practices

Turkish Financial Institutions (FIs) have come to recently realise that nonfinancial factors can materially affect an institution’s long-term performance. Environmental and social issues (i.e. pollution, resource depletion, wastes, biodiversity, land acquisition and resettlement, labour and working conditions, occupational/community health and safety, cultural heritage) have been recognised to pose risks to the Turkish FIs through their project finance operations. This awareness developed in parallel to the concept of sustainability being embraced by Turkey’s corporate sector. Several large Turkish lending institutions have developed environmental and social (ES) management systems for evaluation of the projects considered for financing. Although the majority of these are based on international standards that include ES performance criteria of the International Finance Corporation (IFC), European Bank for Reconstruction and Development (EBRD) and European Investment Bank (EIB), they do not yet fully encompass the requirements of the international standards in the actual implementation process. The projects considered for financing are typically subject to the Turkish Environmental Impact Assessment (EIA) Regulations that set the commitments for the project owner for environmental protection based on the Turkish regulatory framework. Compared to the international standards, there are gaps in the Turkish EIA studies that include a lack of a structured impact assessment, insufficient baseline studies and limited community engagement programmes. These gaps may eventually pose legal risks to the project during development and operations and also to the lending institution in terms of financial and reputational risks. Although several institutions have developed ES management systems internally, experience shows that these systems initially focus on following the Turkish EIA process without fully assessing issues such as biodiversity, cultural heritage and social impact assessments including expropriation and resettlement issues. This chapter will provide an overview of ES procedures of large lending institutions in Turkey and discuss generic data gaps between Turkish EIA studies and international requirements as well as the evaluations of ES risk management systems in place. Discussions include main risks and opportunities in applying international standards in investment finance in Turkey as well as identifying future trends.

Environmental Impact Assessment Standards and Thresholds for Sanitary Landfills

Municipal waste landfills represent a viable and quite commonly used method for domestic waste disposal even though the method has been used for centuries. Municipal waste landfills, at the same time, pose potentially adverse environmental impacts that need to be considered during the site selection process, landfill design, operational and post closure phases. An Environmental Impact Assessment (EIA) study represents an effective tool built into the legislative process of many countries and institutions that can be used to identify potential adverse effects on human health, environment impacts and ecologic risks. The decision makers are able to review all the necessary data on potential impacts prior to project approval. In this manner appropriate remedial measures can be identified and implemented prior to the project start-up.

Monitoring of Leakage in Subsurface Injection of Liquid Industrial Wastes

Deep well injection operations represent one of the available methods of waste disposal. Approximately 14 million tons of liquid wastes in United States were injected into the subsurface in 1988 [Hanson, 1989]; the majority of the hazardous waste injection wells were located along the Gulf Coast and near the Great Lakes. The location of these wells often coincided with areas where oil and gas related explorations had been performed; the exploration efforts provided abundant data on the subsurface formations which were found to be environmentally safe for injection of wastes. The largest user of hazardous waste injection wells in the United States was noted to be the chemical industry [U.S.EPA, 1985]. Deep well injection programs are used in several countries including Canada and Greece. The environmental regulations for hazardous wastes which are presently being drafted in Turkey envision the use of deep well injection programs.