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Hydro-geochemical modelling of an unlined landfill site

Paris, Emma C. 2005. Hydro-geochemical modelling of an unlined landfill site. PhD Thesis, Cardiff University.

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Abstract

This project reports results of a hydro-geochemical study of leachate production at the Silent Valley landfill, Blaenau Gwent, South Wales, UK. Silent Valley landfill site is an active unlined landfill in South Wales. It lies on interbedded sandstones and mudstones of the Rhondda Beds, which are overlain by a mixture of boulder clay, head deposits and made ground. The annual rainfall recorded in the area is approximately 1250 mm. Resistivity surveys were performed across part of the site to help improve the understanding of the internal structure of the landfill. Instrumentation to measure leachate discharge, conductivity and meteorological inputs installed at the Silent Valley landfill site are described and relationships between the rainfall and discharge data are analysed. Regression analysis is used to model the discharge of leachate from the measured meteorological data. Water balance analysis has demonstrated that groundwater is entering the site. The leachate generated on site is collected by a series of drains that feed into the Settlement Tank, which then discharges to foul sewer. The discharge through the Settlement Tank shows a rapid response to rainfall events with dilution effects indicated by conductivity readings and chemical analysis. The volume of discharge from the Settlement Tank is shown to have a long-term upward trend. A preliminary study was undertaken to investigate the use of neural networks to model the discharge in the Settlement Tank. Feedforward backpropogation neural networks were constructed using the measured meteorological data to produce predictions of daily discharge for the Settlement Tank. Ion Chromatography analysis was performed on the leachate to complement the historical leachate analysis data. Element concentration was correlated with conductivity data and variations related to discharge measurements. Since monitoring began in 1993, many of the leachate constituents have shown an increase in concentration.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Earth and Ocean Sciences
Subjects: G Geography. Anthropology. Recreation > GE Environmental Sciences
ISBN: 9781303201349
Funders: Blaenau Gwent County Borough Council, Silent Valley Waste Services
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 05:53
URI: http://orca.cf.ac.uk/id/eprint/54545

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