integrated concept for groundwater remediation incore · integrated concept for groundwater...

Integrated concept for groundwaterremediation INCORE

T.Ertel & B. SchugUW Umweltwirtschaft GmbH, Stuttgart, Germany

Abstract

Pressure on drinking water resources due to urban industrial areas is a common

problem in European cities. State-of-the-art remediation of contaminatedgroundwater is based on single-site approaches neglecting cost-effective regionalgroundwater management and urban planning aspects. Ongoing research by a

consortium of technology developers, problem holders, economists andadministrators is focussed on a comprehensive approach to tackle theseproblems. Technology development include the integrated investigation ofgroundwater contamination at regional scale, fingerprinting and on-site analysisat single site scale and the implementation of innovative remediationtechnologies. Problem oriented implementation strategies include administrativeprocedures, urban planning aspects, and real estate market needs. Key goals to bemet are the conservation of groundwater resources and economic revitalisation of

urban industrial areas

1 Introduction

Most European cities are located in river basins and use groundwater from local

shallow aquifer systems, Rapid industrial development in this century has beenand is still generating groundwater pollution within city boundaries, exceedinglegal requirements. Within the last decades changes in land use have resulted incomplex contamination patterns, such as heterogeneous distribution ofcontaminants, different contaminants and large Landfill areas (see fig. 1).State of the art approaches for site investigation and remediation regard only sitespecific solutions (see fig.2), But in general all site owners are declaring that

contamination has been caused either by their neighbors or a former user of this

site, Traditional investigation methods in most cases need very long time for theidentification of the real polluter or even fail on this matter.

© 2002 WIT Press, Ashurst Lodge, Southampton, SO40 7AA, UK. All rights reserved.Web: www.witpress.com Email [email protected] from: Brownfield Sites, CA Brebbia, D Almorza & H Klapperich (Editors).ISBN 1-85312-918-6

232 Brow@ield Sites: Assessment, Rehabilitation and De~’e[opntent

well

I hyd]

%%’Q.&Po Iution by chlorinat~d hydrocarbons

Figure 1: Actual situation on the investigation site

Today, legal treatment of soil and groundwater impurities is targeted on thespecific endangering situation caused by a specific polluter, All measures aim ata fast reduction of environmental damages so that dangers from a single propertyfor public security do not exist any more. This procedure fails in extensivepolluted areas with different property owners and complex pollutant situation:1. Evaluation of groundwater pollution is based on the sampling of single wells

downstream the polluted site. But underground heterogeneity and spatiallyvarying input of pollutants causes an inhomogeneous pollutant spreading inthe groundwater.

2. Identification of polluters is possible only with high expenditure if differentinputs of similar hazardous substances overlap.

3. Remediation of single hot spots contributes only rarely to a sustainableimpro

f’ 0

Direction ofgroundwaterflow 1

0

Figure 2: Classical investigation strategy


Browtzfield Sites: Assessment, Rehabilitation and De~’elopntent 233

Today, large amounts of private and public money are spent to identify and

assess point sources of contamination without being able to reliably quantify theirimpact on the groundwater quality; numerous remediation schemes are operated

without an economical evaluation of their long-term performance.Four European cities, Stuttgart Linz, Strasbourg and Milan, which share the same

groundwater problems within their industrialised urban areas, have committedthemselves to jointly develop such solutions. Within the different project areasspecific local conditions vary with respect to groundwater conditions, existenceof public and private monitoring wells, type of pollutants, size of areas, risinggroundwater problems etc., and therefore provide a representative range to be

expected at EU scale. In order to achieve the project goals in a cost-efficient way,different parts of the anticipated tool set are applied and evaluated at different

levels of detail in the four selected areas.

2 Innovative approach

The proposed strategy for investigation, remediation and revitalisation of

industrial areas is based on an integral quantification of total contaminant

emissions, by considering entire industrial areas instead of single sites, in order to

obtain a high level of investigation certainty.

An innovative cyclic approach is being proposed which starts with the screening

of groundwater plumes at the scale of entire industrial areas, and ends with the

remediation of individual source areas or the containment of plumes. The major

advantage of this approach is that the number of local scale sites or the size of the

area to be considered, respectively, is reduced step by step from one cycle to the

next. Consequently, a large potentially contaminated area is screened but only a

small area may ultimately be remediated. Figure 4 presents the scheme of this

new approach.

investigated area[m’ / cycle]

I I

regained land[m’] i Icosts[m’ and cycle]

Figure 3: INCORE cyclic approach


234 Browttfield Sites: Assessment, Rehabilitation and De~elopntent

It exhibits that the investigation / assessment / revitalisation cycle is repeated

three times at a different scale:

(a) In cycle I of the new approach, the groundwater quality is screened down-

stream of the potential source areas. This is done by employing an innovative

flux-based groundwater investigation approach.

(b) In cycle II only those sites are being re-considered where the groundwater

quality is not acceptable, There, analytical methods are used to backtrack and

identify the contamination source and determine its extent. Based on a site-

specific risk assessment, the decision whether or not to proceed to the third cycle

is made.

(c) In cycle III source zones are being considered for emission oriented

remediation or implementation of monitored natural attenuation. For this purpose

a comparative cost-benefit analysis is performed based on the available

technologies, Again, the future land-use and the corresponding tolerable

emissions need to be taken into consideration in order to make a final decision on

the most appropriate technology.

The proposed “fit for use” –approach finally provides a cost-efficient set of tools,

meeting both technological and administrative demands, for optimised

investigation, evaluation and management of contaminated ground-water and

land in industrialised urban communities.

3 INCORE results

3.1 Cycle I - plume screening

At the beginning of the project investigations are emission oriented and shall

focus on groundwater contamination. Quantification of contaminant emission is

obtained from the application of a novel integral groundwater investigation

method, which yields the total pollutant mass flux and the mean and maximum

pollutant concentrations originating from contaminant source zones.

The basic idea of the new integral groundwater investigation technique is that the

total contaminant mass flux downstream of potentially contaminated sites is

covered by the capture zones of one or more pumping wells, which are

positioned along control planes perpendicular to the mean groundwater flow

direction (see fig, 4) Analyses of multiple groundwater samples obtained at the

wells during pumping yield concentration time series. Within these time series,

concentrations vary as a consequence of the increasing capture zones and the

spatial distribution of the contaminant mass within the aquifer. The total

contaminant mass flux (emission) and the mean and maximum concentrations

within the undisturbed groundwater flow field are determined through the

mathematical inversion of the concentration time series using a particle tracking

based inversion algorithm and a numerical flow and transport model of the



investigation area. These took are also used for determination and the

delimitation of boundaries of potential polluted source zones. With the means of

numeric-stochastical flow and transport model-ling approaches based on

geostatistical simulation techniques parameter uncertainty can be described. This

yields to estimations of probabilities of contaminant concentrations exceeding

regulation limits within large areas. The size of these areas under consideration

depends on the transport and degradation behavior of different contaminants.

Figure 4: Principle of integral groundwater investigation approach

I

dimof naturalgroundwater,f70w

source zone characterization pumping tests

+

c

~ Cu CKt tconcentration time series obtained during

pumping tests (compound specific) -

+transient inversion algorithm based on a numerical

flow and transport model of the area

total contaminant mass flux, mean and maximum 1(location non-unique) concentrations

Final result is a map (see fig. 5) of the investigation area distinguishing between

areas with different level of groundwater impact. This allows a ranking of these

areas with a distinct level of confidence. This map enables the administration to

set priorities for fhrther activities. Focus sing the efforts on the red areas helps to

concentrate man-power resources on these sites which cause rnaj or impacts on

groundwater pollution. This leads to maximum effectiveness in administrative

activities.


236 Browttfield Sites: Assessment, Rehabilitation and De~elopntent

Figure 5: Cycle I - plume screening

The mapping of areas with different groundwater impact further identifies areas

in which urban and economic development can take place without any hindrance

by pollution matters (green areas), This ensures development and structural

change with low risks on investment.

3.2 Cycle II - source identification

The results of the integrated investigation give a rough localisation of suspected

source areas. However, more precise identification of the contamination source

area is needed in order to apply the polluter pays principle. With the means of

cost-effective laboratory and on-site analytical systems as well as isotopic finger-

printing techniques the backtracking from the control plane along the path line of

the plume yields to a precise localisation of the source of contamination (see

fig.6).

The results of cycle II verify the sources of groundwater pollution and identify

the polluter with a very high degree of probability. This secures the application of

the “polluter pays principle”.

These results also help to avoid law-suits which leads to an acceleration of in-

vestments and to faster administrative procedures.



Figure 6: Cycle II - source identification

3.3 Cycle III - remediation strategy

Monitored natural attenuation as well as emission-focussed in-situ remediation

combined with passive remediation techniques are major options which have to

be considered in the management of contaminated groundwater and land in urban

industrial areas,

The work deals with dual solutions of source and plume remediation, taking into

account natural attenuation as a part of a comprehensive remediation approach,

depending on the remaining/tolerable contamination levels and extent. The basic

idea is to find the most efficient hot spot treatment technology for a given hydro-

geological and contamination situation, and to treat the remaining plumes with

passive remediation technologies.

These alternative or partly combined remediation scenarios are actually under

Remediation schemes lead to joint remediation strategies for several sources of

contamination. The application of “private-public partnership” and innovative

technologies will result in cost-efficient and faster treatment of polluted sites. By

this means the costs for industrial settlement as an important locational factor for

industry will be lowered, which strengthens international competitiveness.

consideration in feasibility studies (see fig. 7).


238 Browwfield Sites: Assessment, Rehabilitation an d De~’elopntent

scenario 1: jointremediation of whole areausing one reactive barrier

scenario 2: remediation of eachhot spot I source separately

scenario 3: combinedremediation of clusters ofrelated hot spots

Figure 7: Cycle III - remediati on strategy



4 Outlook

In the final working phase of INCORE the activities are focussed on three main

questions:

Does the methodology of Cycle I and II ensure a strict application of the

“polluter pays principle”?

How cost-effective is the “fit for use” approach of INCORE?

What kind of administrative measures will be able to support the

implementation of the INCORE-methodology in future practical application?

5 Acknowledgement

The project receives funding from the European Commission in the specific re-

search and technological development program “Energy, Environment and

Sustainable Development”. The author is solely responsible for the content of

this publication which does not represent the opinion of the community. The

community is also not responsible for any use that might be made of data

appearing in this publication,


integrated concept for groundwater remediation incore · integrated concept for groundwater...

Documents