International Case Studies

Service: Groundwater Risk Assessment

Location: Ruwais Oil Refinery, United Arab Emirates

Client: AEA Technology

A major extension of the oil refinery and industrial complex at Ruwais, on the Arabian Gulf coast, was planned. As part of the environmental impact assessment for the extension, ESI was engaged by AEA Technology to undertake a groundwater risk assessment for existing and proposed disposal and storage facilities. The location of the refinery posed interesting hydrological problems, as significant rainfall only occurs once or twice per decade. The disposal facilities, which are above the water table, therefore only contribute dissolved contaminants to the groundwater in pulses at irregular intervals. Another interesting feature of the groundwater system is that because of surface salt pan deposits, recharge waters tend to be much more saline than the groundwater and sink through to the base of the aquifer. A custom RAM model was developed that simulated mixing and transport of the pulsed contaminant inputs and showed that the rate of groundwater movement was so slow that the new developments posed insignificant risks to the coastal water ecosystems.

Service: Service Impact Assessment of Water Extraction

Location: River Traza, Milan

Client: CAP Milano

An impact assessment was undertaken for a proposed public water supply well adjacent to the River Traza, near Milan, Italy. The Environment Agency IGARF methodology was used to assess the impact of the abstraction on river flow. In addition a risk assessment was undertaken to assess the risk from adjacent nitrate contamination and to model the rate at which the nitrate may impact the proposed supply well. The project concluded that there was unlikely to be a significant impact on river flow but that the abstraction could influence nitrate migration in groundwater in the region. On the basis of this information, the proposed development was cancelled.

Service: Groundwater Resource Study

Location: Prato Aquifer, Tuscany

Client: Publiacqua spa

Publiacqua spa was set up in January 2002 to provide water supplies to central Tuscany. It serves 1.25 million customers providing an average of 274 Ml/d. The company needed to develop a strategic water resource for the region in case the supply from the river Arno at Florence was out of action. The sand and gravel deposits of the Prato aquifer was identified as being potentially capable of forming such a resource. However, the aquifer had suffered from over abstraction in the past and groundwater levels have fallen substantially (up to 20 m) over the past 40 years. Publiacqua spa commissioned ESI Italia to develop a groundwater model of the aquifer that could be used as a tool for assessing the feasibility of different management options for the aquifer. The model was developed and calibrated against groundwater levels for the last 30 years. The project also included a significant training component to allow technical staff from the client to use the model as an in-house management tool.

Service: Data management

Location: Kazakhstan

Client: AGIP KCO

AGIP KCO required a software system to store, manipulate and report oceanography data for a wide range of environmental studies carried out in Kakazhstan (including both land based studies and oceanography). ESI was commissioned to review this data being collected, identify an appropriate software solution (this required a thorough investigation into the relevant corporate IT systems etc), assist AGIP/KCO in purchasing the solution (EQuIS 5), customise the EQuIS 5 software system and provide training on the resultant system.

Service: Groundwater Modelling

Location: Oman

Client: AIL

ESI was appointed by AIL, Oman, to undertake development of a groundwater model for a number of Tertiary limestone aquifers in southern Oman. The project was undertaken on behalf of the Ministry of Regional Municipalities, Environment and Water Resources in Oman. The primary objectives of the project were to develop a groundwater model that could be used to aid development of the aquifers, in particular those located in the Umm Er Radhuma Formation, and subsequently to develop a management plan to ensure that any development was environmentally sustainable. The initial data collection phase was undertaken by AIL in Oman and an inception report compiled jointly with ESI. The data collected in the report was used to develop a conceptual model of the groundwater system and to provide the basis for the construction of the groundwater model. An interim modelling report was completed to allow the Ministry to approve the conceptual understanding and the proposed approach to modelling. A 2-layer Modflow model was developed and calibrated against the available data. The model was then used to evaluate a number of abstraction scenarios from proposed wellfields in the Nejd. The model has proved a useful tool to highlight uncertainties in the data and the conceptual understanding and the need for additional data to increase confidence in the knowledge of the aquifer behaviour.

Service: Water Supply Options

Location: Kazakhstan

Client: Confidential

ESI Ltd was appointed as a specialist groundwater and water resource consultancy, to review the available information on the various water supply options for a major refinery development project in a former CIS country and to identify any gaps in the data available. The output was an initial baseline report on the previously identified water resources in the region. The aim of this report was to: note all the known information and make a critical evaluation about what is known, what is not known and the confidence in the available data; and to make recommendations to make available data more robust for meeting the client s aims of identifying potential sustainable water supplies for exploitation.

Service: Groundwater Modelling

Location: Lisheen Lead-Zinc Mine, Ireland

Client: Water Management Consultants Ltd

Development of a regional 3D transient MODFLOW model of the Carboniferous Limestone aquifer and prediction of future impact of various abstraction regimes under differing recharge conditions. A four layer model was developed to represent this complex multilayer aquifer system, drawing on extensive regional monitoring data and specific field investigations.

Variable drift cover across the area, which is of low relief, was found to exert a strong control over recharge distribution and interaction between surface water and groundwater dominates the water balance of the region. Detailed consideration of recharge was undertaken, based on a recharge model using a soil moisture balance approach on the basis of daily data, and aggregate potential recharge was incorporated in the model on a monthly time step, divided between two main recharge seasons. Systematic calibration of the model, initially to steady state conditions, and subsequently to transient conditions, was undertaken, and the sensitivity of the model to input parameters including recharge, storage coefficients, permeability and boundary conditions was assessed through sensitivity analysis.

The model was subsequently applied to the prediction of drawdown zone extent, resources assessment and the evaluation of water quality issues using MODPATH and PATH3D for particle tracking. The model was presented as part of a planning application, and will ultimately be applied as an operational aquifer management tool for the area.

Service: Field Investigation

Location: Al Kamil Coal Mine, Oman,

Client: Wardell Armstrong

A detailed field investigation was designed and implemented using borehole drilling, pumping tests, packer tests, hydrochemical sampling and analysis to characterise critical hydrogeological parameters as the basis for dewatering design. Predictions were made of the likely extent of surface water depletion resulting from the abstractions.

Service: Hydrological Assessment

Location: Proposed Cement Works, Republic of Ireland,

Client: Confidential

The client had applied for planning permission to construct a cement works together with two quarries to provide raw materials. ESI was instructed to provide a hydrogeological assessment of the proposed quarries and associated cement works. The study involved an extensive programme of fieldwork including the construction and testing of 20 monitoring boreholes and two pumping tests.

On the basis of the data collected, a groundwater model was constructed for the site to predict the effect of the proposed dewatering on groundwater levels on the site and on flows in the nearby river. An Environmental Impact Assessment was prepared and submitted to the relevant planning authorities. Planning permission was granted following an appeal. Meanwhile ESI has provided hydrogeological inputs to an application for an IPC licence to operate the site.

Service: Landfill Risk Assessment

Location: Southern Sweden

Client: Confidential

The Spillepeng landfill comprises an old municipal solid waste landfill and a new municipal solid waste and special waste extension that has been built out into Lomma Bay in the Oresund Strait between southern Sweden and Denmark. A large data set of boreholes, groundwater level and groundwater quality data were available in a mixture of paper and electronic formats. These data were Quality Assured and entered into an EQuIS database. Based on these data, a conceptual model of the groundwater and leachate system was developed and was used as the basis to construct a MODFLOW model of the drift and limestone aquifer systems.

Service: Groundwater and Human Health Risk Assessment

Location: Milan, Italy

Client: Confidential

A large company wished to develop an area to the north of the city centre of Milan into a residential area with a number of sports and recreational facilities. The project area was located on the site of a former quarry that was subsequently used as a waste disposal facility. The waste within the site contained a number of contaminants at high concentrations.

A remedial engineering design for the site was produced by sat s.r.l (SAT) on behalf of the client and ESI was commissioned to undertake an assessment of the risk from the wastes to both groundwater and human health and to assess the effectiveness of the proposed engineering design. The risk assessment needed to demonstrate whether the site could comply with the EU Groundwater Directive and a local authority decree with respect to safeguarding the biosphere from identified contaminants.

A probabalistic risk assessment approach was used in the study based on a Source-Pathway-Receptor methodology, chosen to provide a robust and transparent assessment of risk using conservative parameters. The project included a synthesis of available data to construct hydrogeological and toxicological conceptual models for the site. The contaminants of concern and migration pathways were represented in the models as the basis for prediction of the risks associated with the proposed development. The hydrogeological risk was evaluated using an in-house model whilst the toxicological risk was evaluated with the commercially available Risc-Human package. A report was produced for SAT that was presented to the regulatory authority as part of the overall planning submission.

Service: Groundwater Flow Modelling Assistance to Assess Stream Flow Impact

Location: Florida, USA

Client: Southwest Florida Water Management District

Southwest Florida Water Management District is the state agency responsible for assessing abstraction licence applications and issuing water use permits. The District has a responsibility to ascertain whether a proposed licensed abstraction would have a significant impact on adjacent abstractions or on surface water flows.

The District currently assesses impacts on adjacent abstractions via the use of numerical modelling tools. These are used to assess whether or not the proposed withdrawal will cause an adverse impact on existing groundwater resources, on a case by case basis with regard to the specific needs of the resources that could be affected. Currently no assessment is made as to whether the abstraction is likely to impact surface water resources.

ESI developed a software tool, based on Microsoft Excel that allows the District to rapidly assess whether a license application is likely to impact surface water. Three analytical solutions are available, depending on the conceptual model. Output is in terms of graphical illustration of the timing and spatial extent of the impact on the identified surface water body.

Service: Modelling of Subsurface Migration of Crude Oil,

Location: Azerbaijan

Client: Confidential

ESI was commissioned to model subsurface crude oil migration resulting from a hypothetical pipeline breach in Azerbaijan. The modelling contributed to a quantitative assessment of risks to groundwater associated with such a pipeline spillage. Crude oil is a mixture of many hydrocarbons which forms an essentially immiscible fluid that is lighter than water. However, many components are sparingly soluble in water, often at concentrations that are many orders of magnitude greater than water quality standards based on toxicological and/or aesthetic criteria. As such, a leakage of crude oil into the subsurface posed a potential source of contamination to groundwater.

Initial scoping calculations were used to derive the location of the crude oil in the unsaturated zone, including the dimensions of the source area in terms of contaminated area of unsaturated zone and lens at the water table. Detailed analytical solutions of solute transport in the saturated zone, assessed the travel distance over which the contaminants are attenuated to below water quality standards.

Service: Catalytic Oxidiser Review

Location: Italy

Client: Confidential

ESI undertook an evaluation of the performance of a poorly performing catalytic oxidiser used as part of a soil vapour extraction remediation process as a chlorinated solvents-contaminated site in Italy. Evaluation of the process design, oxidiser specification and operating data highlighted a number of inappropriate features and corrective actions were recommended to ensure improved performance and system reliability.

Service: Development of a Methodology for the Characterisation of Unpolluted Groundwaters,

Location: Ireland

Client: Environmental Protection Agency Ireland

In order to comply with its responsibilities under the Water Framework Directive, the Irish EPA will have to report the qualitative status of the country s groundwater bodies. This assessment of qualitative status is by reference to unpolluted groundwater. ESI, in partnership with TMS Environment of Dublin, were engaged to develop a methodology that could be used to characterise unpolluted groundwater for Irish groundwater bodies. The methodology developed consider ed a number of aspects including aquifer lithology, hydrogeochemistry, rainfall chemistry, hydrogeological parameters, and geographical location within the island. It was tested on a number of Irish groundwater bodies using available monitoring data to ensure that it was sufficiently flexible to accommodate the variety in data availability of Irish aquifers.

Following successful development of the methodology, ESI was involved in training for EPA staff and consultants carrying out the work in Irish groundwater bodies.

Service: Evaluation of the potential effect of effluent water on phosphate removal at a municipal wastewater treatment plant

Location: Germany

Client: Confidential

An independent evaluation was performed of the apparent detrimental effect of a chemical plant s effluent water on phosphate removal at a municipal wastewater treatment plant (WWTP) where it was co-treated. Detailed evaluation of plant data indicated no direct causative relationship between commercial effluent quantity or composition and the phosphate removal performance of the WWTP. However, a number of the WWTP operating practices were identified that could have contributed to the performance shortfall and corrective actions recommended.

Service: Spill Response - Caustic Soda Spill

Location: Ireland

Client: Confidential

The client experienced a spill of caustic soda from the bulk storage tank on the site. A large volume of caustic was discharged to ground which comprised a small thickness of made ground / drift strata underlain by limestone. A short distance down hydraulic gradient lies a small river, the valley of which is classified as a Special Area of Conservation. ESI was requested to provide specialist hydrogeological assistance to the main contractors on the site. Initial efforts focussed on installing monitoring wells to identify and delineate the spill. These showed a complex contaminant migration geometry within the limestone aquifer, and suggested that dilution and reaction of contamination had resulted in a significant reduction in contaminant concentration within the aquifer.

Efforts then moved on towards determining whether the river was at any risk from the spill. A simple, spreadsheet based, risk assessment was carried out which demonstrated that the spill posed little risk to the river environment once groundwater and surface water dilution was accounted for. In the event, no remedial engineering was recommended other than continual monitoring until concentrations reduced to background levels.

Service: Groundwater Resource Study

Location: Verona Aquifer Italy

Client: AGSM Verona

The Verona sand and gravel aquifer is an important water resource for industrial and public water supply. It also feeds a series of springs that provide baseflow to streams and ditches in the south of the area (the fontanili line). As a first stage in a project to develop a comprehensive management system for the aquifer the client commissioned ESI Italia to develop a regional groundwater model of the aquifer. This first pass groundwater model was important in demonstrating the key features of the local water balance and the main areas of impact from abstraction. Further, more detailed modelling was planned.

Service: Data Management

Location: Portugal

Client: EDSR Ltd

ESI provided support to EDSR Ltd in setting up an environmental data management project using EQuIS 5 Professional and Envirolnsite. Data was migrated from legacy spreadsheets into EQuIS 5. The analysis and reporting included 2D and 3D chemical concentrations spatial plots, geochemical cross-sections and site plans with time-series chemical plots, charts, statistics and cross-tab data. The client was able to deliver the figures efficiently, on-time and with confidence in the data.

Service: Review of Status of Water Quality Monitoring

Location: Shanghai

Client: World Bank

The project was related to a major urban environmental investment programme in Shanghai that aims to tackle the countries problem of assuring clean drinking water for its citizens. ESI's Italian branch led a team of biologists and specialists in water resources management and sustainable development who were tasked with reviewing the status of the water quality monitoring program in Shanghai. This involved assessing the scope for developing a biological monitoring programme for its vast network of surface waters.