Performance Monitoring of Remediation Technologies for Soil and Groundwater Contamination: Review

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<ul><li><p>ReCo</p><p>. D.</p><p>nologin techlt undntamlishedntaminntamintigateto enschemd themeter</p><p>roun</p><p>major component of soil and groundwater remediation projects. mance of the remediation technologies applied on meeting reme-</p><p>Dow</p><p>nloa</p><p>ded </p><p>from</p><p> asc</p><p>elib</p><p>rary</p><p>.org</p><p> by </p><p>Iow</p><p>a St</p><p>ate </p><p>Uni</p><p>vers</p><p>ity o</p><p>n 09</p><p>/22/</p><p>13. C</p><p>opyr</p><p>ight</p><p> ASC</p><p>E. F</p><p>or p</p><p>erso</p><p>nal u</p><p>se o</p><p>nly;</p><p> all r</p><p>ight</p><p>s res</p><p>erve</p><p>d.Based on monitoring data, the remediation technologies appliedto contaminated sites can be evaluated whether they perform asexpected to clean up the sites to meet site-specific remediationobjectives. The monitoring results are also crucial for deciding thetermination date of the remediation projects and the implementa-tion of contingency plans for further treatment. Another important</p><p>diation objectives. The possible changes in contaminant zonesduring the remediation include redistribution of contaminants insubsurface, consequently creating a more extensive contaminantsource zone; change of microbial communities accordingly dis-rupting native natural attenuation capability in subsurface; andplugging of soil matrix which prevents further contaminantsource reduction by the delivery systems of the applied remedia-tion technologies ITRC 2004. For instance, thermal treatmentand surfactant/cosovlent flushing technologies may mobilizedense nonaqueous phase liquids DNAPLs beyond the treatmentzone. The chemicals injected during in situ chemical oxidationISCO may suppress native microorganisms in subsurface andsupport other microbial communities. Furthermore, gas evolvedfrom ISCO using hydrogen peroxide and biofilm formed duringbioremediation may lead to plugging of the soil matrix. Innova-tive technologies, such as monitored natural attenuation MNA,phytoremediation, and permeable reactive barriers PRBs requiremore extensive performance monitoring than the more acceptedremediation approaches Gavaskar et al. 2000; USEPA 2000,2004b.</p><p>Performance monitoring of the remediation technologies is notonly a measure of technical success of the technologies to con-form state regulation but also involves the cost effectiveness ofthe technologies on soil and groundwater remediation. In assess-ing the performance of the remediation technologies, there aretwo primary criteria: remediation effectiveness and efficiency. Ef-fectiveness refers to the capability of the remediation technolo-gies to achieve remediation objectives at contaminated sites</p><p>1Postdoctoral Fellow, Dept. of Civil, Architectural, and EnvironmentalEngineering, ECJ 8.210, Univ. of Texas at Austin, 301 E Dean Keeton,Austin, TX 78705.</p><p>2Engineer Director and Adjunct Professor of EnvironmentalEngineering, Univ. of NebraskaLincoln, U.S. Environmental ProtectionAgency, P.O. Box 172141, Kansas City, KS 66117 correspondingauthor. E-mail: surampalli.rao@epa.gov</p><p>3Professor, Water, Earth, and Environment Center, National Instituteof the Scientific Research, Univ. of Quebec, 490, de la Couronne, QubecQubec, Canada G1K 9A9.</p><p>4Associate Professor, Dept. of Civil Engineering, Hong Kong Univ. ofScience and Technology, Clear Water Bay, Kowloon, Hong Kong.</p><p>5Ph.D. Student, Water, Earth, and Environment Center, NationalInstitute of the Scientific Research, Univ. of Quebec, 490, de laCouronne, Qubec Qubec, Canada G1K 9A9.</p><p>Note. Discussion open until December 1, 2007. Separate discussionsmust be submitted for individual papers. To extend the closing date by onemonth, a written request must be filed with the ASCE Managing Editor.The manuscript for this paper was submitted for review and possiblepublication on September 13, 2006; approved on October 20, 2006. Thispaper is part of the Practice Periodical of Hazardous, Toxic, andRadioactive Waste Management, Vol. 11, No. 3, July 1, 2007. ASCE,ISSN 1090-025X/2007/3-132157/$25.00.</p><p>132 / PRACTICE PERIODICAL OF HAZARDOUS, TOXIC, AND RADIOACTIVE WASTE MANAGEMENT ASCE / JULY 2007Performance Monitoring ofSoil and Groundwater</p><p>Keith C. K. Lai1; R. Y. Surampalli2; R</p><p>Abstract: Performance monitoring of applied remediation techmeasurement of site parameters to evaluate whether the remediatioof remediation projects. Performance monitoring can be a difficuobjectives, such as a reduction in mass discharge rate from a comonitored is highly dependent on the remediation objectives estabnant concentration in soil, soil vapor, and groundwater within a coof a contaminant zone is the prime remediation objective, while coshould be the main monitoring parameter if the objective is to miis a unique monitoring parameter for in situ thermal remediationoxidant concentration is the monitoring parameter only for in situcriteria for establishing the site-specific remediation objectives anwhich help avoid waste of efforts to collect unnecessary site para</p><p>DOI: 10.1061/ASCE1090-025X200711:3132</p><p>CE Database subject headings: Contamination; Efficiency; Gevaluation; Soil sampling; Water sampling.</p><p>Introduction</p><p>Monitoring of the performance of remediation technologies is aPract. Period. Hazard. Toxic Radioact. Wmediation Technologies forntamination: Review</p><p>Tyagi3; Irene M. C. Lo4; and S. Yan5</p><p>es is an important part of site remediation. It involves periodicnologies perform as expected or to determine the termination dateertaking if there are no well-defined and measurable remediationinant source. Besides, the selection of the site parameters to beand the remediation technologies applied. For instance, contami-ant zone should be monitored if reduction of the mass or volumeant concentration in groundwater just outside a contaminant zonethe contaminant migration. Furthermore, subsurface temperatureure the proper operation of the technology, whereas groundwaterical oxidation technologies. This paper mainly covers the generalkey monitoring parameters for various remediation technologies,s during the performance monitoring.</p><p>d-water pollution; Monitoring; Parameters; Remedial action; Site</p><p>point is that performance monitoring can help site managers orengineers to examine whether the changes in contaminant zonesresulting from remediation activities can deteriorate the perfor-aste Manage. 2007.11:132-157.</p></li><li><p>Table 1. Performance Metrics, Monitoring Methods, and Monitoring Parameters for the Performance Monitoring of the Remediation Technologies forDNAPL Source Zone Treatment</p><p>Mp</p><p>oncentrnt con</p><p>minantreakdooncentr</p><p>acers</p><p>nt cononcentr</p><p>ant cont connt con</p><p>vities</p><p>acers rnts reta</p><p>series</p><p>Dow</p><p>nloa</p><p>ded </p><p>from</p><p> asc</p><p>elib</p><p>rary</p><p>.org</p><p> by </p><p>Iow</p><p>a St</p><p>ate </p><p>Uni</p><p>vers</p><p>ity o</p><p>n 09</p><p>/22/</p><p>13. C</p><p>opyr</p><p>ight</p><p> ASC</p><p>E. F</p><p>or p</p><p>erso</p><p>nal u</p><p>se o</p><p>nly;</p><p> all r</p><p>ight</p><p>s res</p><p>erve</p><p>d.ITRC 2004. For example, if the remediation objective is areduction in hexavalent chromium CrVI mobility, the effective-ness is defined whether the remediation technologies can haltthe continuous CrVI migration. Normally, assessment of theremediation effectiveness involves quantifying reductions in con-taminant mass, concentration, mobility, and/or toxicity by theremediation technologies NRC 1997.</p><p>Efficiency of the remediation technologies refers to the opti-mization of the time, energy, and costs expended toward theachievement of remediation effectiveness. It is typically assessedby comparing system operating parameters to the relevant designspecifications. For example, ISCO systems are usually effective inreducing contaminant concentrations at the beginning stage butthe rate of reduction becomes lower and less efficient succes-sively with each injection in terms of time, energy, and moneyexpended. Thus optimization of the operating parameters to main-tain good remediation efficiency is required ITRC 2004.</p><p>To assess the remediation effectiveness and efficiency, perfor-mance monitoring is conducted specifically to collect data fromcontaminated sites. By definition, performance monitoring in-volves periodic measurement of physical and/or chemical siteparameters to evaluate whether the remediation technologiesperform as expected. Generally, contaminant concentrations ingroundwater, soil, and soil vapor for volatile organic contami-nants are the parameters usually measured during the perfor-mance monitoring. However, each remediation technology has itsown specific measuring parameters. For instance, monitoring ofthe concentration of biological nutrients in subsurface is requiredin assessing the performance of in situ bioremediation. Normally,the selection of the monitoring parameters is dependent on theremediation objectives, performance metrics, and types of reme-diation technologies applied. Performance metrics are the envi-ronmental conditions and monitoring parameters measured to</p><p>Performancemetrics</p><p>Monitoringmethods</p><p>Adsorbed-phase reduction Soil coring Soil contaminant cDissolved-phase reduction Groundwater sampling Aqueous contamina</p><p>Source mass extracted Effluent sampling Volumes and contaSource mass destroyed Groundwater sampling Concentration of bSource mass remaining Soil coring Soil contaminant c</p><p>Tracer tests Concentration of tr</p><p>Groundwater sampling Aqueous contaminaMobility reduction Soil coring Soil contaminant c</p><p>Product gauging NAPL thicknessToxicity reduction Soil coring Adsorbed contamin</p><p>Groundwater sampling Aqueous contaminaMass flux/massdischarge reduction</p><p>Well transect sampling Aqueous contaminaHydraulic conductiHydraulic gradients</p><p>Flux meter transects Mass of resident trMass of contamina</p><p>Integral pumping tests ConcentrationtimePRACTICE PERIODICAL OF HAZARDOUS, TOXIC, AND</p><p>Pract. Period. Hazard. Toxic Radioact. Wevaluate remediation progress or to confirm attainment of reme-diation objectives ITRC 2004. Table 1 shows common perfor-mance metrics, monitoring methods, and monitoring parametersrequired for the monitoring of the performance of the remediationtechnologies for DNAPL source zone treatment.</p><p>In light of the importance of the performance monitoring tosoil and groundwater remediation, and the difficulty of the selec-tion of appropriate and representative monitoring parameters, thischapter aims to introduce the remediation objectives, performancemetrics, and monitoring parameters generally involved during theperformance assessment of remediation technologies. Groundwa-ter and soil sampling systems commonly applied are also in-cluded. In the final part, key monitoring parameters of eachremediation technology, which includes pump-and-treat P&amp;Tsystems, soil vapor extraction SVE, air sparging AS,surfactant/cosolvent flushing, in situ thermal remediation, ISCO,in situ bioremediation, MNA, PRBs and phytoremediation, arespecifically mentioned Bedient et al. 1999; USEPA 2004a; Loet al. 2006b.</p><p>Remediation Objectives</p><p>Measuring the effectiveness of the remediation technologies is adifficult undertaking if clear remediation objectives are not speci-fied. Remediation objectives can be quantitative or qualitative innature but should at least be measurable so that the remediationprogress toward the remediation objectives can be monitored ob-jectively. In most contaminated sites, remediation objectives areusually designed based on the overriding goals of most state andfederal regulatory programs, namely protection of human healthand natural environment from contaminated sites. Generally, the</p><p>onitoringarameters</p><p>Derivedparameters</p><p>ations Sorbed concentrationcentrations Plume extent</p><p>Change in NAPL compositionconcentrations of extracted fluids Contaminant mass removed</p><p>wn products e.g., chloride Mass of DNAPL destroyed in situations and visual observation DNAPL distribution</p><p>Sorbed massNAPL volumeSaturation</p><p>centrations Aqueous concentrationations and visual observation NAPL presence and saturation</p><p>NAPL thicknessncentrations DNAPL compositioncentrations Concentrations of toxic parameterscentrations Darcy flux</p><p>Mass fluxMass discharge</p><p>etained on sorbents Darcy fluxined on sorbents Mass flux</p><p>Mass dischargesampling from extraction well Mass discharge</p><p>Average plume concentrationRADIOACTIVE WASTE MANAGEMENT ASCE / JULY 2007 / 133</p><p>aste Manage. 2007.11:132-157.</p></li><li><p>remediation objectives fall into three categories: short-term,intermediate-term, and long-term remediation objectives.</p><p>nant concentrations in soil, groundwater and/or soil vapor. How-ever, these performance metrics of reduction in contaminant con-</p><p>Dow</p><p>nloa</p><p>ded </p><p>from</p><p> asc</p><p>elib</p><p>rary</p><p>.org</p><p> by </p><p>Iow</p><p>a St</p><p>ate </p><p>Uni</p><p>vers</p><p>ity o</p><p>n 09</p><p>/22/</p><p>13. C</p><p>opyr</p><p>ight</p><p> ASC</p><p>E. F</p><p>or p</p><p>erso</p><p>nal u</p><p>se o</p><p>nly;</p><p> all r</p><p>ight</p><p>s res</p><p>erve</p><p>d.Short-term remediation objectives typically involve the alle-viation of the immediate risks from contaminated sites to humansor natural resources through the prevention of further expansionof contaminant source zones. Therefore, short-term objectivescustomarily take account of the control of contaminant mobilityand mitigation of contaminant migration. Intermediate-term reme-diation objectives are established to guide the remediation activitywhen complete removal of a contaminant source in one aggres-sive remedial effort is not feasible and the contaminants remain-ing in contaminated sites still exceed the regulatory standardsNRC 1994. Intermediate-term objectives may include: 1depletion of a contaminant source adequately to allow for naturalattenuation; 2 reduction of dissolved phase contaminant concen-trations outside a contaminant source zone; 3 decrease in massdischarge rate or flux from a contaminant source; 4 reduction ofthe mass or volume of a contaminant source to a smaller extent;and 5 prevention of the migration of remediation fluids beyonda treatment zone. According to the information provided by U.S.Environmental Protection Agency USEPA, application of theinformation obtained from the interim remediation actions forlong-term risk management can accelerate the risk reduction fromcontaminant sites USEPA 1997. It may take a year or severalyears for contaminated sites to meet the intermediate-term objec-tives. Besides, long-term monitoring is required to ensure that theinterim treatment levels achieved are sustainable and are not sub-ject to a rebound in contaminant concentrations in groundwaterwhen posttreatment equilibrium is established in aquifers. Long-term remediation objectives focus on the compliance with theregulatory treatment standards applicable to all contaminatedmedia i.e., groundwater, soil, and soil vapor at the sites.Achievement of the regulatory standards leads to the terminationof remediation activities; but in analogy to intermediate-term ob-jectives, long-term monitoring is also required to ensure that thecompliance is sustainable. If long-term remediation objectives arenot met or achievable, a contingency plan is needed to implementand a secondary treatment may be required.</p><p>Performance Metrics and Monitoring Parameters</p><p>Each remediation objective should have its own set of perfor-mance metrics for assessing and monitoring the performance ofthe remediation technologies applied toward this objective. Thesemetrics are neither equivalent to nor interchangeable with oneanother. They range from qualitative indicators of remediationprogress to quantitative measures of specific factors followingremediation see Table 1. Currently, there are three m...</p></li></ul>

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