Further description:-  Tools and procedures 

Glossary Entry
A document or software produced with the aim of supporting decision making, i.e. something that carries 
out a process in decision support.
1000 word outline, 10 key web links and 10

A risk assessment tool can be any methodology, model or software package designed to qualify or quantify the risk posed by a contaminant in evaluating a source-pathway-receptor linkage. A tool may comprise a suite of risk based screening values, a methodology with recommended or prescribed algorithms, or a computer based package that allows site specific risk assessment to be carried out.

 

There are several risk assessment tools that have been developed commercially and many that have been developed specifically to support the approach to contaminated land of a particular country or region.

 

Summary of Available Tools across Europe

 

Key Reference: Much of the following information has been derived from NICOLE/ISG Risk Assessment Comparison Study. FINAL REPORT. Arcadis Geraghty and Miller International, April 2004. A number of other references, including some used extensively for the NICOLE study are given below.

 

A brief summary of some of the available tools is presented below. A number of European countries do not promote the use of a particular risk assessment tool, but none-the-less have prescriptive approaches or have developed screening levels.

 

CLEA                          - Contaminated Land Exposure Assessment

Origin                           - England

 

CLEA is an exposure assessment model for estimating child and adult exposure to soil contaminants for those potentially living, working and /or playing on contaminated sites over long periods of time. The software is currently designed to calculate soil guideline values (SGVs) and as such is not a fully site specific model. CLEA is a probabilistic model.

 

A limited number of contaminants are present in the database, for which accompanying documents are available to describe the derivation of the SGVs and the definition of health criteria used to describe the toxicity of a compound. New chemicals cannot be added to the current version 1.3.0.2 though work is on going on a revised version (due to be released Spring 2005). The model includes ten exposure pathways such as ingestion of soil and dust, dermal contact, ingestion of vegetables and inhalation of vapours and dust.

 

CLEA calculates risk levels for both threshold and non-threshold compounds assuming that the exposure duration is equal to the averaging time. Risks levels are always calculated as hazard quotients.

 

CLEA “back-calculates” to provide target values, or SGVs.

 

JAGG                          - Regneark til risikovurdering af Jord, Afdampning, Gas og

  Grundvand

Origin                           - Denmark

 

JAGG is used for assessment the risk from contaminated soils to human health and environmental receptors. The model is navigated by a series of buttons, opening excel spreadsheets. Five different fate and transport scenarios can be considered, soil, indoor air, outdoor air, landfill gas and groundwater.

 

The user specifies contaminant of concern, one at a time, from the in-built databases. The model allows predicts concentrations of contaminants within the air, water or soil, which can then be compared to accepted exposure concentrations for a receptor. These exposure concentrations are contained within the model.

 

P20-RTW - Publication 20 (Marsland & Carey 1999) Remedial Targets Spreadsheet

Origin - England

 

P20-RTW is a tool used for the site specific assessment of risks to groundwater resources from contaminated soils and groundwater. The system is intended to develop remedial targets for soil and groundwater and is navigated by a series of Excel spreadsheets. The user is required to input all the physical and chemical parameters required.

 

For a soil source the model includes the assessment of partitioning, dilution in an underlying groundwater body and prediction of a receptor point concentration at a distant point. For groundwater sources the model predicts groundwater concentrations at a distant point. The groundwater fate and transport model includes the OgataBanks, Domenico Steady State and Domenico Time Variant options.

 

Risk Assessment Model (RAM)

Environmental Simulations International Ltd has developed this proprietary system. The aim of the model is to assess the potential risks to water resources in line with the P20 methodology developed in the UK.

 

ConSim

A commercially available software package developed by Golder Associates on behalf of the Environment Agency of England and Wales. The software is designed to assess the potential risks to water resource receptors from impacted soil and groundwater sources, and includes the ability to model leaching through the unsaturated zone.

 

RBCA Toolkit - “Risk-Based Corrective Action” Toolkit

Origin                           - Commercial

 

The RBCA Tool Kit for Chemical Releases is designed to meet the requirements of the ASTM Standard Guide for Risk-Based Corrective Action. 

 

It has the ability to generate generic risk-based screening levels (RBSLs) for on-site exposure, assuming default exposure factors and site properties. Alternatively the user can evaluate baseline risks and/or site-specific target levels (SSTLs) for both on-site and off-site receptor locations based on site-specific soil, groundwater and air parameters.

 

In addition to steady-state air, soil, and groundwater exposure models, the toolkit allows transient groundwater modelling analyses to help you estimate not only how high but how soon exposure could occur. An array of default transport parameters is provided for various soil types and a chemical database is included in the model.

 

RISC               - Risk Integrated Software for Clean-ups

Origin               - Commercial

 

RISC is a multimedia risk assessment tool primarily used for human health risk assessment (both in quantifying risks and calculating clean up targets) but is diverse enough that the component environmental fate and transport models can be used independently. The programme has in-built databases for chemical properties and standardised soil types.

 

RISC can assess more than one contaminant at a time and can assess impacts in both soil and groundwater. A number of pathways can be selected e.g. ingestion of soil and vegetables, dermal contact and inhalation of indoor/outdoor air. RISC includes a number of sub-models for predicting concentrations in indoor air: Johnson and Ettinger, the dominant layer model and the oxygen limited model. RISC includes a database of exposure parameter or the user can input their own values.

 

RISC-HUMAN

Origin                           - Netherlands

 

Risc-Human v3.1 is a software system designed to investigate human exposure (to contaminants within both the soil and groundwater via up to 15 exposure pathways) and to calculate risk levels.  The system is based on three different model approaches – CSOIL (developed by the Dutch National Institute of Pubic Health and the Environment, RIVM), VOLASOIL and SEDISOIL.  Either VOLASOIL or CSOIL can be used to assess exposure via the volatilisation pathway from groundwater to indoor air.  SEDISOIL is used for exposure to sediments, in surface water and through ingestion of fish.

 

Risc-Human has an inbuilt database of over 120 chemicals with on-site contaminant concentrations being added in a number of forms: concentration in soil, concentration in groundwater and concentration in contact media, for example concentration in indoor air. 

 

Risc-Human assesses exposure in indoor air from both soil and groundwater sources, with a basement or crawl-space always assumed to be present.  Adult and child exposure scenarios can be considered, with both exposure rates and exposure times potentially different between the two. 

 

ROME                      - ReasOnable Maximum Exposure

Origin                           - Italy

 

ROME, developed by the National Agency for Protection of the Environment (ANPA), is a risk assessment tool for human health (sanitary risk) and water resources (groundwater and surface water). The model adopts a risk-based tiered procedure that takes into consideration two simplified types of assessment (generic Tier 1 and site specific Tier 2), derived from the standard ASTM RBCA (Risk-Based Corrective Actions). The end use of the site, residential/green area or industrial/commercial is also considered.

 

A chemical/physical and toxicological database for 118 compounds and default environmental and exposure parameters are included. Different sources can be considered: shallow soil, deep soil, groundwater and free product. The human health receptors are defined as child and adult for residential purpose and workers for industrial purpose. The environmental receptors are defined as groundwater and surface water.

 

ROME quantifies human risks and can calculate as clean-up levels or Site Specific Target Levels.

 

SFT Report 99:06            - Statens forurensningstilsyn Report 99:06 (Norwegian Pollution

Origin                           - Norway

 

SFT Report 99:06 is a guidance document for the risk assessment of contaminated sites, used for assessing the risk from contaminated soils to human health and ecological receptors. The report outlines a step by step approach to generating alternative acceptance criteria for soil to which the concentrations of contaminants on the site can be compared. The risk assessment process requires the identification of contaminants of concern, these contaminants are then considered individually in the process. A database of chemical and toxicological properties is presented in the report. The user may only input soil source concentrations. Default exposure parameters for human health are presented in the report, for the most sensitive use, however the parameters can be modified to suit the situation. The concentrations of the contaminant that the receptor is exposed to are compared to accepted toxicological values presented in the report for each contaminant.

 

UMS                - Umwelt (Environment), Mensch (HumanHealth), Schadstoff (pollutant)

Origin               - Germany

 

UMS is a tool used for assessing the risk from contaminated soils to human health receptors.  Nine different land-use scenarios are defined within the model. Each of the nine scenarios incorporates an in-built selection of receptors.

 

Contaminants are selected from a chemical database, to which new chemicals can be added and toxicity data is either specified or the default values adopted. Concentrations in the appropriate media are specified for each exposure pathway.

 

The exposure pathways are pre-defined based on the selected exposure scenario, for example dust ingestion and air/dust inhalation are active pathways in the residential building. Extensive fate and transport modelling is not carried out and appears to have been replaced by a number of empirical factors, for example, the concentration in indoor air is assumed to be a factor of 100 times less than the concentration in the soil air.

 

The model calculates a risk index, which is in turn used to calculate a risk value. Three ranges of risk value are specified to determine whether action is required on the site. Groundwater cannot be modelled as a receptor within the UMS module. However, there is a second module, which may be used in conjunction with UMS:

 

SISIM             - (Sickerwassersimulation or leachate simulation)

Origin               - Germany

 

SISIM calculates vertical pollutant transport in the unsaturated zone, predicting the extent and time of impacts reaching the groundwater. There is no exposure assessment associated with this module and it does not predict the impacts to any off-site receptors.

 

VLIER-HUMAAN

Origin                           - Belgium (Flanders), developed in Netherlands

 

Vlier-Humaan v2.0 has the same layout as RISC-HUMAN. The system is based on models similar to the Dutch C-Soil and HESP models, adapted for Flemish use and designed to investigate human exposure to contaminants within both soil and groundwater. 

 

Vlier-Humaan has an inbuilt database of chemicals with the ability to add new chemicals. On-site contaminant concentrations can be added in a number of forms: concentration in soil, concentration in groundwater and concentration in contact media, for example concentration in indoor air. 

 

Vlier-Humaan assesses exposure in indoor air from both soil and groundwater sources, with or without a basement or crawl-space present.  Adult and child exposure scenarios can be considered, by inputting different exposure times between the two.  Two output screens provide receptor point concentrations, child/adult doses and risks. 

 

Other Risk Assessment Approaches

 

A number of countries in Europe are in the process of developing risk assessment approaches, as discussed below on a country by country basis

 

Austria

Austrian Standard ŐNORM S 2088-2 (completed June 2000) provides assessment criteria for soil contamination, specifying that the focus should be on the direct effect of contamination to humans, plants and animals.  Intervention values are provided for sensitive land uses such as residential areas, with screening values for other land uses. Reference values are provided for leachate concentration, soil gas concentration and ‘total’ contaminant concentration. The values are generally derived from drinking water standards.

 

Finland

Three levels of risk assessment are applied in Finland:

 

Firstly, a qualitative site risk assessment is completed, often using a site ranking system such as the US Environment Protection Agency Hazard Ranking System.  Secondly, measured concentrations are compared with guideline values for soil contaminants, published in the SAMASE report and mostly based on Dutch values.  The "SAMASE" project, was carried out between 1989 and 1993 to examine measures for and develop recommendations on the investigation, categorization and restoration of contaminated sites throughout Finland. The use of risk-based approaches was included as a specific element of the project.  Thirdly, an in-depth risk assessment is undertaken, although few have been completed to date.  Various unnamed computer-based exposure models have been used at this third stage of risk assessment.

 

France

Simplified Risk Assessment

 

The procedure for the completion of the simplified risk assessment is presented in the document "Guide relatif à l’évaluation simplifiée des risques d’un site" (version 2 - juillet 2000, Editions du BRGM).

 

The simplified risk assessment is completed using a simple scoring system that that assesses 40 parameters using the Source-Pathway-Receptor model. 

 

As part of the development of version 2 of the Simplified Risk Assessment (SRA) some French Fixed Impact Values (FIV) have been defined. FIV's are presented in "Management of (potentially) Contaminated Sites" (Gestion des sites et sols pollues), version 2 was issued in March 2000".

 

Detailed Risk Assessment

 

Detailed risk assessment is used to aid the decision process to define the strategy for the remediation of sites regarded to have an unacceptable risk to human health and the environment, and is completed after further site investigation.  The principal objective being to identify the sites requiring remediation for the proposed future use of the site and those that present a low risk. 

 

Following contact with INERIS (Institut National de l’Environnement Industriel et des Risques) it has been ascertained that there is no official risk model developed in France, and that there is no national guidance to recommend the use of a particular model.

 

Spain

Basque Country


The Environmental Protection Act of the Basque Country (March 1998) constitutes the legal framework for addressing the problem of contaminated land. The Basque Country takes a ‘suitable for use’ approach to the management of contaminated sites in which potential land use depends on the degree of contamination. Accordingly, soil quality is defined on the basis of risk assessment for protected targets (human health and the environment) and intended land uses.

 

Soil screening values known as Indicative Values for Assessment (VIEs) are land use dependent and provide a generic assessment that will allow essentially risk-free soils to be differentiated from soils that pose or could potentially pose risks for the intended use.

 

The Basque country commissioned the assistance of CRBE at Nottingham Trent University, UK to create a modified version of the CLEA software, named EUSCLEA to develop “distribution” based screening values.

 

Cataluña

 

The Generalitat of Cataluña has developed provisional criteria for soils quality to be used in this territory. These guidelines include the Cataluña soil quality indication values and a methodology for determination and application. Cataluña soil quality criteria are numeric values of substance concentrations in soil, designed to swiftly evaluate the need for further action.

 

Galicia

 

Similar initiatives to those of the Cataluña region are being reviewed and develop in the Galicia region.

 

Whilst the legislation and assessment of contaminated land issues are advancing in Spain, and more specifically in its Autonomous Communities, there are not as yet any widely available or recommended modelling packages for carrying out site specific risk assessments.

 

Sweden

When the Environmental Code came into force on 1 January 1999, a new legal instrument, environmental quality standards (EQS), was introduced into Swedish environmental practice. EQS are adopted in order to address actual or potential environmental problems, to achieve environmental objectives and to implement EC directives that prescribe this type of standard.

 

For some sites the conditions may be such that the generic guidelines are not applicable, in these cases a site-specific analysis would be carried out.

 

There is currently no ‘official’ risk assessment computer model for Sweden, the formulae presented in Report 4639 (Development of Generic Guideline Values) give the equations and assumptions used to develop the Swedish Generic Guideline Values using risk assessment.

 

Switzerland

A decision to take remedial action requires a site specific risk analysis based on present and future interactions between the site and the environment, mainly groundwater, surface water, soil and air, taking into account potential for transport and barriers. Intervention values for leachate and air have been derived based on human toxicity consistent with the relevant laws concerning water and soil.

 

A groundwater risk assessment model, TransSim, has been developed for the Swiss Agency for the Environment Forests and Landscapes by BMG Engineering Ltd.  TransSim simulates contaminant fate and transport in the unsaturated and saturated zone.  It is broadly equivalent with models such as P20 RTW, RAM, ConSim and the groundwater functions within BP RISC, RBCA Toolkit, Risc-human, etc.

 

 

Table 1 provides a summary of the capabilities of 15 risk assessment tools currently in use (to varying degrees) across Europe.


Table 1

Summary of Risk System Capabilities

 

Pro-forma Reference

Model

Software package

Human health risk assessment

Compliance risk assessment

Ecological risk assessment

Back calculations

Soil models

Groundwater models

Vapour transport models

Air mixing models

Surface water mixing models

Presence of NAPL

Probabilistic capability

Exposure Assessment Models

Chemical properties database

Toxicological properties database

Geological properties database

Compliance Criteria database

Default values

English language

Help system

Soil

Air

Groundwater

Surface water

Direct contact

Vegetable uptake

Inhalation of particulates

Inhalation indoor air

Inhalation outdoor air

Direct contact

Vegetable uptake

Shower model

Irrigation model

1

CLEA

 

 

 

 

 

 

 

 

 

 

 

2

ConSim

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

3

Giuditta

 

 

 

 

 

 

 

 

 

 

4

JAGG

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

5

P20-RTW

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

6

RAM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

7

RBCA Toolkit

 

 

 

 

 

 

 

8

Report 4639

 

 

 

 

 

 

 

 

 

 

9

RISC

 

 

10

Risc-Human

 

 

 

 

 

 

 

 

11

ROME

 

 

 

 

 

 

 

 

12

SFT 99:06

 

 

 

 

 

 

 

 

 

13

SNIFFER

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

14

UMS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

15

Vlier‑Humaan

 

 

 

 

 

 

 

 

 

 

 

Notes

Software Package –                             Risk System software is available

Human Health Risk Assessment –    Risk System considers the risk posed to human receptors

Compliance Risk Assessment –        Risk System considers the modelling of contaminant levels to set compliance criteria

Ecological Risk Assessment –           Risk System considers the risk posed to environmental receptors

Back Calculations –                             Risk System back calculates risk posed to receptors to produce target contaminant levels at the source

Soil Models –                                       Risk System models contamination from a soil source

Groundwater Models –                       Risk System models contamination from a groundwater source

Vapour Transport Models –              Risk System considers transport of vapour within the risk system

Air Mixing Models –                           Risk System considers air mixing within the risk system

Surface Water Mixing Models –       Risk System considered mixing of surface waters within the risk system

Presence of NAPL –                            Risk System considers the presence of low and high density free phase product (model dependant)

Probabilistic Capability –                    Risk System allows the use of stochastic input concentrations and exposures parameters giving                                                                       a resultant, statistically evaluated risk.

Chemical Properties Database –        Risk System contains a chemical properties database

Toxicological Properties Database - Risk System contains a toxicological properties database

Geological Properties Database-       Risk System contains a geological properties database

Compliance Criteria Database-           Risk System contains a compliance criteria properties database

Default Values-                                     Risk System contains default values

English Language-                               Risk System is available in English

Help System-                                        Risk System contains a help system

Exposure Assessment Models:

 

Soil (Direct Contact) –                         Direct human contact with contaminated soil

Soil (Vegetable Uptake) –                   Uptake of contaminants into vegetable grown on contaminated soil

Soil (Inhalation of Particulates) –      Human inhalation of contaminated soil particulates

Inhalation of Indoor Air –                  Human inhalation of vapours in indoor air. Where the Risk System considers soil models vapour                                                                      transport from soil to air is a pathway and/or where the Risk System considers groundwater models                                                                 vapour transport from groundwater to air is a pathway

Inhalation of Outdoor Air -                Human inhalation of vapours in outdoor air. Where the Risk System considers soil models vapour                                                                   transport from soil to air is a pathway and/or where the Risk System considers groundwater models                                                                 vapour transport from groundwater to air is a pathway

Groundwater (Direct Contact) -         Direct human contact with contaminated groundwater

Groundwater (Vegetable Uptake -     Uptake of contaminants into vegetable grown with contaminated groundwater

Groundwater (Shower Model) -         Direct human contact with contaminated groundwater used for a shower

Groundwater (Irrigation Model) -      Uptake of contaminants into vegetable grown irrigated with contaminated groundwater

Surface Water –                                   Transport of contamination from soil and/or groundwater to surface water

 


Many of the commercial packages are in widespread use throughout Europe (and globally), including in countries that have not yet developed their own methodology. These tools (RBCA Toolkit, RISC, RAM and ConSim) are therefore included in Table 1.

 

Conclusions

 

The development and acceptance of risk assessment as a tool for the management of contaminated land is growing, however the level of development varies considerably, including between different regions of a country. The tools mentioned here are likely to be added to as the management of contaminated land progresses.

 

It should be noted that there are many similarities between some tools, which are in some cases developed directly based on an existing system or methodology. Some of the tools are in effect a combination of sub models, many of which are common between different software packages, e.g. the Johnson and Ettinger indoor air model is used in RISC, RBCA-Toolkit, ROME, and will be included in the next version of CLEA.

 

 

 

Authors
Helen Hayward
Arcadis Geraghty and Miller International Ltd, United Kingdom

Who does what?
Katy Baker
Arcadis Geraghty and Miller International, Ltd, United Kingdom

Who does what?