Client: Thames Water
Location: Abingdon, Oxfordshire
Services: Groundwater Modelling , Environmental Impact Assessments
Issues: Impact of reservoir construction on local groundwater system and wider surface water environment
Summary: ESI supported the preparation of the hydrogeological component of the Environmental Impact Statement for a proposed reservoir. Groundwater and solute transport modelling were used to predict groundwater chemistry in the aquifer beneath the proposed reservoir site resulting from a complex hydrogeological history, with old, brackish water being flushed by fresh recharge wasters.
Thames Water is currently re-evaluating the requirement for a major water resource development in the Upper Thames area including the case identified previously for a reservoir south west of Abingdon. A project team has been appointed by Thames Water to undertake this work.
ESI is supporting Thames Water and Cascade Consulting in the preparation of the hydrogeological component of the Environmental Impact Statement (EIS) for the proposed scheme. ESI is also working alongside Jacobs UK Ltd which has been appointed by Thames Water to lead the engineering input to the project. An integrated approach to the groundwater related aspects of the engineering and environmental components of the project is critical to a successful outcome for the project.
ESI has been working with Thames Water for a number of years to carry out baseline work at the site. In parallel with the ongoing fieldwork programme, ESI has been developing the hydrogeological conceptual model that will be a key input to the EIS, and a fundamental step towards determining whether the proposed scheme will have impacts on the groundwater system and wider surface water environment.
One key technical challenge to understanding the impact of a future reservoir is to be able to accurately predict current conditions. The current distribution of groundwater chemistry in the aquifer beneath the proposed reservoir site is the product of a complex hydrogeological history, with old, brackish water being flushed by fresh recharge waters. Groundwater and solute transport modelling has been used to successfully predict this distribution at the site.
This will not only provide quantitative support for the current conceptual model but will also lead to the development of a tool to predict the likely effects of the proposed development.
ESI’s innovative and proactive approach to groundwater investigation and characterisation has yielded key contributions to the EIS and improved the understanding of the groundwater system greatly.