Esi Water Resources Brochure

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Water Resource Management – Monitoring, Conceptualisation, and Groundwater Flow and Transport Modelling, Field Investigation

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Transcript of Esi Water Resources Brochure

Page 1: Esi Water Resources Brochure

Water Resource Management – Monitoring, Conceptualisation, and Groundwater Flow and Transport Modelling, Field Investigation

Page 2: Esi Water Resources Brochure

ESI is the UK’s leading independent scientific and environmental consultancy specialising in water resource management, land quality and ground source energy. As a technical specialist advisor to corporate and governmental clients ESI is respected for its pragmatism, sound science and strong commercial focus.

Water Resource Management – Monitoring, Conceptualisation, and Groundwater Flow and Transport Modelling, Field Investigation.

Consultancy Services for Water Resources ESI is a specialist consultancy dealing with all aspects of groundwater science and groundwater resource management and has one of the largest and most technically capable groundwater teams in the UK. With a detailed technical understanding and experience of the key issues involved in field investigation, monitoring, conceptualisation, and groundwater

flow and transport modelling ESI is recognised as the leading independent provider of water resource services. Groundwater support is provided to a diverse group of clients who need to understand, assess, map and plan, including: Utility companies, Developers, Extractive, Mining and Tunneling companies, Local Authorities and the Environment Agency.

Low Flow Studies and Hydro-ecologyTraditionally, water resource assessments for groundwater abstraction have focused on the impacts at a relatively large or catchment scale. Ecological concerns are often very local and site specific. Low flow studies and hydro-ecology assessments therefore need to combine the broad catchment scale approach with a more detailed local understanding. ESI’s combination of strong technical skills with a detailed experience of local scale processes is essential to resolving these issues.

ESI has over 15 years of experience working with a range of clients, particularly in the water industry, to develop more targeted and efficient ways of defining the impact of groundwater abstraction on surface water ecology (hydro-ecology). With multiple and complex projects completed ESI has a record of working alongside other specialists (e.g. in aquatic ecology and hydrology) as part of a team to deliver clear answers to these problems.

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Groundwater Control and Dewatering The development of sophisticated tunnelling techniques on major engineering projects has led to the increased demand for accurate predictions of rates of dewatering required. In the extractive industry, planning constraints on the lateral extensions to quarries has put increased pressure to deepen existing sites below the water table. In both of these industries, the energy costs of dewatering have become significant operational factors, whilst environmental constraints are often critical to the feasibility of these schemes.

ESI’s senior team has extensive experience of handling complex dewatering projects and has provided innovative solutions to the issues faced. The consultancy team has successfully developed and are operating groundwater models of some of the largest dewatering schemes in the UK. ESI’s approach in all of its projects is to work closely with clients to determine the most appropriate level of assessment required for each site. This ensures that the most cost effective solutions can be achieved in all cases.

Borehole Drilling and Testing and Deployable Outputs ESI has built an experienced team of groundwater scientists with a good balance between pragmatic field experience and in-depth quantitative skills for the analysis of field results.  All contractors used to support projects are carefully chosen, all must meet a work standard dictated by ESI and all are required to provide copies of their own Quality and Health and Safety standards and accreditations. All contractors are supervised, whether on small site investigations or on major production borehole drilling and testing contracts. ESI is committed to providing

quality assured data to ensure total accuracy in its reporting.

Water companies are required to plan extensively for the future with detailed Water Resource Management Plans for the next 25 years of operation. A key building block of these plans is the source reliable output assessments for all groundwater sources.  ESI’s strengths in applied groundwater science and experience of borehole yield assessment have been critical to developing an accurate assessment of the water available from these sources for clients across the UK.

Groundwater Modelling Groundwater models can improve our understanding of how aquifer systems behave and can be used to make predictions about the system’s future behaviour. Specific questions that can be addressed using a groundwater model include:

• How might a change in abstraction be used to improve river flows or reduce impacts on a wetland?

• Is a potential river support scheme effective?

• How might climate change influence available resources?

• Will this abstraction cause saline intrusion?

• How might changes in abstraction affect groundwater quality?

In order to produce a groundwater model that can be used as a reliable management tool, it is essential to base it on a carefully worked out conceptual model. This requires a thorough review of all the relevant data. The consultancy team at ESI has extensive experience and are able to use their knowledge in this area to select the right groundwater modelling approach for the problem being faced. Groundwater models should never be more complex than the problem requires or available data allows.

ESI has one of the largest and most technically capable groundwater modelling teams in the UK. Over the last decade the team has consistently delivered technically robust groundwater models that are used to provide practical answers to the important water resource questions faced

by their clients. Groundwater models have been developed to solve problems involving water resource management, borehole yield, tunnel dewatering, quarry dewatering, climate change, saline intrusion and groundwater contamination (including petrol spills and landfill issues).  

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Investigation of the London AquiferThe aquifer beneath London is subject to a considerable number of stresses including rising groundwater levels, abstraction sustainability, artificial recharge, saline intrusion, groundwater flooding, and the growth of ground source energy. ESI has recently undertaken two key projects for the Environment Agency to aid the management of these pressures in a sustainable and cost effective manner.

Following consolidation and analysis of the available data and a comprehensive literature review, ESI has formulated a detailed conceptual understanding of the key hydrogeological processes which occur within the London Basin aquifer. Using the most-up-to-date interpretation of the geology beneath London, ESI furthered current understanding of geological controls on groundwater flow, most notably faulting and structure within the basin and the

influence Chalk stratigraphy on aquifer properties. The robust and quantified conceptual model has formed the basis for the construction of a numerical MODFLOW model. The conceptual and numerical models will aid the Environment Agency manage water resources.

ESI has developed a coupled groundwater flow-heat transport FEFLOW model of central London, building on recent work undertaken on the ‘Cooling the Tube’ project for the London Underground. The aim of the model was to provide a tool to aid the Environment Agency effectively manage and make regulatory decisions regarding open-loop ground source energy schemes. A series of models were developed to simulate heat transport under a range of operational scenarios, including ‘worst case’ and a range of realistic operating conditions.

Case Studies

Dealing with Climate Change The impact of climate change on groundwater resources is a complex issue and does not lend itself to an easy solution. Most global climate models suggest that on average there will be wetter winters and drier summers in the UK. This should imply that on average there will be more winter recharge to the aquifer providing increased groundwater availability than at present. However, increased variability is also a significant feature of current climate change predictions and not all winters will have higher rainfall than average. Furthermore, an increase in the number of intense summer storms may provide significant summer

recharge, as has been experienced in recent years. The increase in variability will make it more likely that an extended sequence of dry winters could occur with potentially significant implications for water resource management. The reliability of these model predictions is still a topic for debate, in the meantime it is clear that increased uncertainty requires increased resilience of water supply systems.

ESI’s strengths in quantitative hydrogeology (including a proven track record in calculating recharge rates from meteorological data) are well suited to assessment of the risks to water resources from climate change.

Groundwater Flood Risk Assessment and MappingGroundwater floods occur after long periods of high rainfall, when the water table rises above the ground surface.  Insurance companies estimate that groundwater flooding claims amount to between £50 million and £100 million per year. Each event costs about three times as much as fluvial or tidal flooding because a groundwater flood can last for weeks or months. 1.6 million homes in the UK that are outside existing fluvial and tidal flood risk areas may be

susceptible to groundwater flooding. In addition, civil engineering work can often have very localised effects on shallow groundwater levels resulting in damage to adjacent properties. In all cases, understanding the causes of groundwater flooding and development of robust mitigation measures requires a thorough quantitative understanding of the local groundwater conditions, something that ESI’s experienced staff are well placed to provide.

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Cornelly Group of QuarriesThe planning permissions for the Cornelly Group of Quarries were subject to review under the provisions of the Environment Act 1995 (ROMP). The National Assembly for Wales (NAW) had concerns about the potential impacts of further working of the quarries; the regulators had particular concerns about the potential for dewatering Special Areas of Conservation under the Habitats Directive.

The NAW requested Environmental Statements to assist in the determination of the ROMP submissions. Tarmac appointed ESI to carry out a hydrogeological investigation and impact assessment, the work involved field investigations (construction of 20 new monitoring

boreholes and borehole and surface geophysics), monitoring (level, flow and quality), tracer tests, data review and analysis, development of a conceptual model and preparation of the Environmental Statement.

Negotiation and technical discussion with the regulators was a central part of the assessment due to the complexity of the local hydrogeology and the potential degree of uncertainty in any predictions that could be made. The work was carried out in a phased manner to allow results from the early stages to be circulated and the scope for later phases to be adjusted in the light of these findings. Work has progressed through the EIA stage and is now focussed around future water management at the site.

Low Flow Investigation SitesOver the last ten years ESI has worked closely with Severn Trent Water on key low flow sites in the Midlands, spanning the AMP3, AMP4 and AMP5 programmes in 40 catchments and reviewing over 60 PWS abstraction boreholes.

The sites were initially flagged up by the Environment Agency and included several SSSIs and a Habitats Directive site. ESI worked closely with STWL, the regulators and other specialists to determine whether these concerns were justified. At several of the sites it was quickly apparent that either there was a significant low flow problem and the site could progress to options appraisal or there was no significant PWS impact and the sites could be

dropped from the programme.

ESI drew up a scope of further investigations for each site and was then appointed with partners to carry out the works. In AMP4 this involved detailed site surveys, 15 new observation boreholes and an extensive programme of groundwater level and spot flow gauging (80 sites) over a 3-5 year period at each site. The data collected was regularly reviewed and annual reports presented. At the end of the monitoring period, ESI prepared impact assessment reports to summarise the improvement of understanding of the problem and to make an assessment of the significance of any impacts.

Croydon Cable Tunnel National Grid’s plan to construct a 10 km tunnel to house its new 400kV line through South Croydon was a great way of avoiding years of traffic disruption. The tunnel needed to be built carefully through the chalk aquifer, an important source of public water supply, passing within a few hundred metres of several of Thames Water’s critical supply boreholes, without affecting water supplies. The contract for the detailed design and construction of the tunnel was awarded to Morgan Est. ESI were a technical partner involved in finding pragmatic ways of

mitigating the potential risks to water supplies and supporting discussions with the Environment Agency and Thames Water.

The risks to the sources were minimised by changes to the design of the tunnel and an ongoing groundwater level and quality monitoring programme throughout the course of the project. Detailed contingency measures were designed that would be actioned if certain triggers were breached. The tunnel was completed on time and to budget with no significant adverse impacts on the environment.

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ESI LtdNew Zealand House160 Abbey ForegateShrewsburySY2 6FDT: +44 (0) 1743 276100 E: [email protected] W: www.esinternational.com

Expert Witness SupportESI has a team of senior consultants with experience of delivering Expert Witness support in groundwater, groundwater flooding, land contamination, ground source energy and in relevant sub-specialisms. The Expert Witness team is supported by industry leading technical consultants.

Expert WitnessBSc MSc CGeol FGSWater Resources Director ESI Ltd

Mike Streetly

Mike Streetly is a very experienced hydrogeologist and project director/manager who is well known throughout the industry for his skills and experience in water resource assessment. He has strong numerical skills which have been applied to solving a wide variety of hydrogeological problems. He also has extensive practical experience, particularly in the design, installation and operation of hydrometric networks and pumping tests. 

Expert WitnessBSc MSc DUC MBA CGeol FGS Managing Director ESI Ltd

EurGeol Mark Fermor

Mark Fermor is a hydrogeologist with particular expertise in quantitative methods for resource management, contamination assessment and groundwater modelling. He has practical experience of investigating and remediating a wide range of contamination hazards in soil and groundwater and in undertaking hydrogeological risk assessments using both qualitative and quantitative methods. 

Expert WitnessMA MSc PhD FGS CGeolPrincipal Hydrogeologist, ESI Ltd

Dr Steve Buss

Dr Steve Buss is a Chartered Geologist with extensive experience of understanding and modelling groundwater flow and contaminant transport. He has led projects that have examined groundwater flow and contaminant transport in all the principal UK aquifers; from the site scale to the scale of regional aquifers. These have included: assessments of groundwater resource availability, the impact of groundwater abstraction on stream flows, the impacts of changes in groundwater flow on groundwater chemistry, and risk assessments for groundwater flooding.