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Assessing the effectiveness of landfill restoration and remediation at a closed landfill site

Ling, Sarah R.A. 2007. Assessing the effectiveness of landfill restoration and remediation at a closed landfill site. PhD Thesis, Cardiff University.

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Abstract

This research project was established to investigate the varying environmental impact of a landfill waste mass after the installation of a fully engineered landfill capping system. Nant-y-Gwyddon Landfill Site is a waste disposal site situated in the Rhondda Fawr in South Wales, UK. The site was established on an area of high ground overlooking the densely populated valley floor. The key environmental body at risk from the site was identified as the layered aquifer system supported by the cyclical geological strata dominated by sandstone aquifers separated by less permeable siltstone, mudstone and coal seams. The research adopts an integrated approach, where the understanding of the changes occurring in the waste mass are directly linked to predicted changes in the contamination levels in the groundwater system. Emphasis is also given to the mechanisms for contaminant transport between the waste mass and the environmental systems. As such the entire landfill system including the surrounding environment is considered as a set of closely interconnected systems. A monitoring system was designed to observe the changes occurring to the waste mass in terms of leachate level and saturation conditions after the installation of the landfill cap in an attempt to assess the changing leachate generation rates and quality within the waste mass. The key findings from the waste mass are then used to interpret variations in contaminant levels in the groundwater systems. Geophysical investigations highlight the extent of the leachate contamination detected in the groundwater hydrogeologically down gradient of the waste mass. The findings from groundwater monitoring are then used to develop a hydrogeological numerical model for the site using the program Visual MODFLOW. The key findings from groundwater monitoring and modelling highlight the importance of the unsaturated zone beneath the site in providing a source of contaminants which are mobilised during increased groundwater levels triggered by rainfall events. The majority of the contaminant loading was determined to be sourced from the area where a direct pathway exists between the waste mass and the Main Aquifer system. Predictions for future trends of contamination levels are then made in response to the findings and show a dynamic system intrinsically linked to the development of the waste mass and the meteorological conditions on site.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Earth and Ocean Sciences
Subjects: Q Science > QE Geology
ISBN: 9781303213519
Date of First Compliant Deposit: 30 March 2016
Last Modified: 25 Oct 2017 14:32
URI: http://orca.cardiff.ac.uk/id/eprint/54748

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