groundwater remediation - startseite...1.5 risk assessment concepts 18 1.6 institutional controls 20...

Groundwater Remediation

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Groundwater Remediation

A Practical Guide for Environmental Engineers and Scientists

Edited by

Nicholas P. Cheremisinoff

This edition first published 2017 by John Wiley & Sons, Inc., 111 River Street, Hoboken, NJ 07030, USA

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Contents

Preface xi

About the Author xv

1 Conducting Groundwater Quality Investigations 11.1 Introduction 11.2 Evolution of Site Assessments 21.3 Technology Limitations and Cleanup Goals 141.4 Conceptual Models 14

1.4.1 Source and Release Information 151.4.2 Geologic and Hydrogeologic

Characterization 161.4.3 Contaminant Distribution, Transport

and Fate 171.4.4 Geochemistry Impacting Natural

Biodegradation 171.5 Risk Assessment Concepts 181.6 Institutional Controls 201.7 Risk-Based Cleanup Goals and Screening

Level Evaluations 201.8 Assessing Plume Migration Potential 25

2 The Family of DNAPLs 372.1 Defining DNAPL 372.2 Chemicals and Origins 38

2.2.1 Creosote and Coal Tars 382.2.2 Polychlorinated Biphenyls 412.2.3 Chlorinated Solvents 442.2.4 Mixtures 48

2.3 DNAPL Behavior 492.3.1 General Behavior and Concepts 492.3.2 Important Parameters for Site Characterization 56

2.4 Overview of Remediation Strategies 592.4.1 Remediation Goals 592.4.2 Technologies 63

2.4.2.1 Pump-and-Treat 63 2.4.2.2 Permeable Reactive Barriers 63 2.4.2.3 Physical Barriers 64 2.4.2.4 Enhanced Biodegradation 64 2.4.2.5 Thermal Technologies 64 2.4.2.6 Chemical Flushing 65 2.4.2.7 Excavation and Removal 65 2.4.2.8 Soil Vacuum Extraction 66 2.4.2.9 Water Flooding 662.4.2.10 Air Sparging 66

3 Hydrocarbons 693.1 Fate and Transport 69

3.1.1 General 693.1.2 Advective Transport 703.1.3 Dispersion 703.1.4 Sorption 713.1.5 Dilution and Recharge 733.1.6 Volatilization 73

3.2 Gasoline Compounds 743.2.1 General Description 743.2.2 The BTEX Compounds and MTBE 743.2.3 Properties of VOCs 753.2.4 Degradation 753.2.5 Half-Lifes 77

3.3 Pump and Treat 793.3.1 Concept 793.3.2 Non-Aqueous Phase Liquids 853.3.3 Contaminant Desorption and Precipitate

Dissolution 863.3.4 Remedial Technologies 873.3.5 EPA Cost Data for Pump-and-Treat 89

4 1,4-Dioxane 954.1 Overview 954.2 Properties, Fate and Transport 984.3 Health Effects and Regulations 103

vi Contents

4.4 Remediation Technologies 1044.4.1 Advanced Oxidation (Ex Situ) 1094.4.2 Adsorption (GAC) (Ex Situ) 1134.4.3 Bioremediation 1134.4.4 Treatment in Soil 114

5 Perfluorinated Compounds (PFCS) 1175.1 Overview 1175.2 Origins of the Contaminants 1185.3 PFAs Properties and Structures 121

5.3.1 General Description 1215.3.2 Variations of PFAS 1235.3.3 PFOS 1265.3.4 PFOA 129

5.4 Environmental Fate and Transport 1305.5 Groundwater Contamination 1445.6 Water Treatment 1495.7 Estimating Carbon Treatement Costs 157

6 Chlorinated Solvents 1636.1 Physico-Chemical Properties of Chlorinated Solvents 1636.2 Origins of Groundwater Contamination 1676.3 Fate and Transport 168

6.3.1 Properties 1686.3.2 Degradation and Daughter Products 1706.3.3 Biodegradation Half-Life 1736.3.4 DNAPL Migration 185

6.4 Groundwater Remediation Strategies 1886.4.1 Preliminary Considerations 1886.4.2 Soil Excavation, Treatment and Disposal 1956.4.3 Soil Vapor Extraction 1976.4.4 Enhanced Methods of Soil Vapor Extraction 2016.4.5 In Situ Air Sparging 2026.4.6 Enhanced Biodegradation 2106.4.7 In-well Aeration and Recirculation 2156.4.8 Reactive and Permeable Walls 216

6.5 Costs 2176.5.1 Soil Excavation, Treatment and Disposal 2176.5.2 Soil Vapor Extraction 2206.5.3 Air Sparging Comparisons to other Technologies 227

Contents vii

viii Contents

7 Mineral Ions and Natural Groundwater Contaminants 2337.1 Overview 2337.2 Secondary Drinking Water Standards 2367.3 Irrigation Water Quality Standards 238

7.3.1 Salts 2387.3.2 Water Analysis Terminology 2387.3.3 Types of Salt Problems 2397.3.4 Salinity Hazard 2417.3.5 Sodium Hazard 2427.3.6 Trace Elements and Limits 242

7.4 Water Treatment Membrane Technologies 2477.4.1 Overview 2477.4.2 Reverse Osmosis (RO) 2487.4.3 Nanofiltration 2557.4.4 Microfiltration 2587.4.5 Ultrafiltration 2607.4.6 Treatment Costs 2627.4.7 Secondary Wastes 2657.4.8 Selection Criteria 265

7.5 Ion Exchange 2667.5.1 Technology Description 2667.5.2 Chelating Agents 2717.5.3 Batch and Column Exchange Systems 2727.5.4 Process Equipment 2727.5.5 Cost Data 275

7.6 Crystallization 2797.6.1 Technology Description 2797.6.2 Forced-Circulation Crysallizers 2867.6.3 Draft-tube Crystallizers and Draft-tube-baffle

Crystallizers 2887.6.4 Surface-Cooled Crystallizers 2897.6.5 Oslo Crystallizers 2917.6.6 Fluid-Bed Type Crystallizers 292

8 Heavy Metals and Mixed Media Remediation Technologies for Contaminated Soils and Groundwater 2998.1 Nature of the Problem 2998.2 Toxic Metal Chemical Forms, Speciation 300

and Properties

Contents ix

8.3 Remedial Technology Strategies 306 8.3.1 Isolation 306 8.3.2 Capping 306 8.3.3 Subsurface Barriers 313 8.3.4 Immobilization 315 8.3.5 Solidification/Stabilization 317 8.3.6 Vitrification 321 8.3.7 Toxicity and Mobility Reduction 323 8.3.8 Wet Oxidation Process 331 8.3.9 Advanced Oxidation Technologies 3338.3.10 Permeable Treatment Walls 3438.3.11 Biological Treatment 3448.3.12 Physical Separation 3468.3.13 Extraction 3498.3.14 Soil Washing 3498.3.15 Soil Screening 3508.3.16 Chemical Treatment 3508.3.17 Physical Treatment 3518.3.18 Pyrometallurgical Extraction 3528.3.19 In Situ Soil Flushing 3528.3.20 Electrokinetic Treatment 352

8.4 Cost Data 353 8.4.1 General Cost Information 353 8.4.2 Site Capping 356 8.4.3 In situ Solidification/Stabilization 358 8.4.4 Ex Situ Solidification/Stabilization 361 8.4.5 Soil Washing 365 8.4.6 Slurry Walls 367

Index 379

Preface

Clean, healthy groundwater is essential to sustaining civilization. Groundwater is relied on as the major source of drinking water and as a source for agricultural activities; it interacts with surface water bodies which support aquatic and other natural species that mankind relies on. Out of both ignorance and poor practices, historical industrial activi-ties have caused groundwater quality in many industrialized countries to become impaired, placing significant populations at risk, and causing water sources to become either restricted or unusable for long periods of time, and in some cases inaccessible for future generations. Properly address-ing and managing groundwater contamination problems can be complex, costly, and depending on the nature of the chemical contaminants and hydrogeological conditions, can take many years to address. Each affected site oftentimes poses a unique set of challenges, generally requiring sev-eral technologies to be tried, tested and evaluated before effective strate-gies are implemented. Addressing groundwater contamination commands the integration of several branches of science and engineering, as well as policy specialists; among these are the branches of hydrogeology, special-ists in conducting site investigations, risk assessment tools and models, an understanding of chemistry and in particular natural biodegradation factors, cost estimating, analytical tools, and many other fields. The sub-jects and fields of science, as well as the analytical tools required to address groundwater problems are many, and oftentimes require significant effort and costs to be invested prior to selecting strategies and technologies appropriate to address a site. Because of the comprehensive nature of this field, this volume was prepared to provide a primer for students, as well as environmental engineers, scientists and property managers who are faced with dealing with these issues early in their careers. The volume is written with the intent of providing a broad overview of the elements essential to conducting investigations and in the selection of strategies and technolo-gies for remedial action. At the same time, considerable practical informa-tion is included in the volume along with guidance on costs and levels of effort needed to address groundwater quality problems.

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xii Preface

Selecting the proper strategy needs to be based first and foremost on understanding whether pathways to human and other sensitive receptors are open and therefore present risks. Risks may in fact be both present and future – as an example, today’s commercial or industrial property that has a groundwater quality problem may not have an open pathway to human exposure, but it could if the land were to be redeveloped at some future time. Therefore, institutional controls may play a very large part in selec-tion of the remedial strategy. An additional concern is that in the past, the costs for addressing remediation became open ended because conceptual site models were not properly developed and a clear understanding and documentation of groundwater plume behavior and chemistry were lack-ing. Many times it has been assumed that the technology that was appli-cable to remediating the groundwater at one site is equally applicable to another site with the same or similar set of chemical contaminants – only to find that insufficient planning and technology vetting contributed to ineffective cleanup with timeframes that were unrealistic.

This volume provides a broad overview of the current and most widely applied remedial strategies. Instead of discussing these strategies in a generic way, the volume is organized by focusing on major contaminants that are of prime focus to industry and municipal water suppliers. The specific technologies that are applicable to the chemical contaminants discussed in different chapters are presented, but then cross-referenced to other chemi-cal classes or contaminants that are also candidates for the technologies. The reader will also find extensive cost guidance in this volume to assist in developing preliminary cost estimates for capital equipment and opera-tions & maintenance costs, which should be useful in screening strategies.

There are eight chapters. Chapter 1 provides an overview of the concepts and important factors to consider when conducting site and groundwa-ter quality investigations. Chapter 2 provides an overview of an important class of groundwater contaminants known as DNAPLs (dense non-aque-ous phase liquids) which are extremely challenging from the standpoint of remediation. Chapter 3 address technologies suitable for addressing the cleanup of common hydrocarbons like VOCs and gasoline. Chapter 4 addresses a particular chemical contaminant (1,4-Dioxane), which many municipal water suppliers are concerned about due to emerging regula-tions as a contaminant of concern. Chapter 5 focuses on perfluorinated compounds. These chemical contaminants are extremely stable and persis-tent in the environment and are of major concern because of world health advisories which link exposures to trace amounts in the parts per trillion range to health problems. Chapter 6 discusses chlorinated solvents. These toxins have been found at almost every Superfund site in the United States

Preface xiii

and at numerous industrial complexes around the world because of the extensive use of these solvents in industrial cleaning and degreasing opera-tions. The biodegradation properties of these contaminants is better under-stood today than a mere decade ago, and hence for some sites groundwater management strategies may be based on natural attenuation and careful monitoring. Chapter 7 addresses mineral ions and natural groundwater contaminants with a focus on ensuring good-quality irrigation sources. Finally Chapter 8 tackles the subject of heavy metals and mixed media remediation technologies for contaminated soils and groundwater.

The author extends heartfelt gratitude to Scrivener Publishers for their efforts in producing this volume.

Nicholas P. Cheremisinoff, Ph.D.

About the Author

Nicholas P. Cheremisinoff is a chemical engineer with more than 40 years of industry, R&D and international business experience. He has worked extensively in the environmental management and pollution prevention fields, while also representing and consulting for private sector companies on new technologies for power generation, clean fuels and advanced water treatment technologies. He is a Principal of No Pollution Enterprises. He has led and implemented various technical assignments in parts of Russia, eastern Ukraine, the Balkans, South Korea, in parts of the Middle East, Nigeria, and other regions of the world for such organizations as the U.S. Agency for International Development, the U.S. Trade & Development Agency, the World Bank Organization, and the private sector. Over his career he has served as a standard of care industry expert on a number of litigation matters. As a contributor to the industrial press, he has authored, co-authored or edited more than 160 technical reference books concerning chemical engineering technologies and industry practices aimed at sound environmental management, safe work practices and public protection from harmful chemicals. He is cited in U.S. congressional records concern-ing emerging environmental legislations, and is a graduate of Clarkson University (formally Clarkson College of Technology) where all three of his degrees – BSc, MSc, and PhD. – were conferred.

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1

1.1 Introduction

The volume is intended as a primer to address groundwater contamination often caused by legacy pollution or unintentional releases of chemicals to the subsurface. When groundwater has been adversely impacted, a variety of sciences, strategies, technologies and actions are needed to assess human and ecological risks from the contamination. The first step in assessing impacts requires a body of good practices that are recognized by industry on the whole and is referred to as the environmental site assessment.

Environmental site assessment practices are also commonly referred to as environmental audits. The practices for conducting an environ-mental site assessment began evolving in the United States in the 1970s. Throughout the 1980s environmental site assessment practices evolved further with the promulgation of the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) and the Resource Conservation and Recovery Act (RCRA), which required commercial facilities to identify, report and remediate recognized environmental

1Conducting Groundwater Quality Investigations

2 Groundwater Remediation

conditions. Throughout the 1990s environmental site assessment practices were enhanced with more precise tools that aided in site characterization and quantification of recognized environmental conditions. Over the years additional analytical tools have evolved to aid environmental site assess-ment practices.

The goal of an environmental site assessment is to identify recognized environmental conditions. The term recognized environmental conditions means “the presence or likely presence of any hazardous substances or petroleum products on a property under conditions that indicate an exist-ing release, a past release, or a material threat of a release of any hazardous substances or petroleum products into structures on the property or into the ground, groundwater, or surface water of the property.”1

1.2 Evolution of Site Assessments

The control of hazardous substances and the prevention of the entry of these substances into the environment is the objective of several acts of U.S. Congress. Rules regulating various aspects of hazardous waste can be attributed to the Toxic Substances Control Act (TSCA); the Clean Water Act (CWA); the Clean Air Act (CAA); the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA); the Safe Drinking Water Act (SDWA); the Resource Conservation and Recovery Act (RCRA); and the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). RCRA and CERCLA are the two that are most often associated with envi-ronmental site assessments.

RCRA was passed to control industrial and municipal solid wastes, including sludges, slurries, etc. The act also called for a tracking system to document the generation, transport, and disposal/storage of solid wastes. The discovery of a large number of uncontrolled and abandoned hazard-ous waste sites, such as at Love Canal, New York, prompted a much greater emphasis on the hazardous nature of the wastes. In the 1980s the regu-lations and resources of RCRA were primarily devoted to the control of hazardous wastes, with a lesser emphasis on nonhazardous solid wastes.

In 1980, legislation aimed at providing federal money for the cleanup of inactive waste disposal sites was enacted. The Comprehensive Environmental Response, Compensation and Liability Act (CERCLA), often called the “Superfund Act”, provides regulatory agencies with the

1ASTM Designation: E 1527 – 97

Conducting Groundwater Quality Investigations 3

authority to deal with inactive sites, funds to deal with hazardous waste emergencies and a means to assign the liability of cleanup to the responsi-ble parties. It also provides monies (Superfund) to pay for the mitigation of hazards from abandoned sites when no responsible party can be found or when the responsible party refuses to take action. In addition, it empowers the government to seek compensation from responsible parties to recover funds used in mitigation actions.

Section 105 of the CERCLA requires that the National Contingency Plan (NCP), developed under the Clean Water Act, be revised to include procedures and standards for responding to releases of oil and hazardous substances. The revised plan reflected and effectuated the responsibilities and powers created by the act.

Subpart F of the NCP, Hazardous Substance Response, establishes a seven-phase approach for determining the appropriate extent of a response authorized by CERCLA “when any hazardous substance is released or there is a substantial threat of such a release into the environment, or there is a release or substantial threat of a release of any pollutant or contami-nant which may present an imminent and substantial danger to the public health or welfare”2. Each phase sets specific criteria to establish the need for further action. The phases are:

1. Phase I – Discovery and Notification2. Phase II – Preliminary Assessment3. Phase III – Immediate Removal4. Phase IV – Evaluation and Determination of Appropriate

Response – Planned Removal and Remedial Action5. Phase V – Planned Removal6. Phase VI – Remedial Action7. Phase VII – Documentation and Cost Recovery

This phased approach is the basis for implementation of all CERCLA-authorized Hazardous Substance Responses with which industry is obli-gated to comply.

The practice of conducting environmental site assessments began in the 1970s in the United States. These practices evolved over time, which is why it is important to place them within a historical context. As early as the 1970s specific property purchasers in the United States undertook studies

2Characterization of Hazardous Waste Sites: A Methods Manual, Volume I – Site Investigations,

EPA/600/4-84/075, April 1985


resembling current Phase I ESAs, to assess risks of ownership of commer-cial properties which had a high degree of risk from prior toxic chemical use or disposal. Many times these studies were preparatory to understand-ing the nature of cleanup costs if the property was being considered for redevelopment or change of land use.

The evolution of best practices in conducting site assessments was driven by an expanding knowledge base on the fate and transport of harmful chemicals. Until the early 1960s, the question of whether or not groundwa-ter was significantly affected by organic wastes was generally addressed by observing the subsurface breakdown of sewage and similar matter. There was a general belief that the easiest way to eliminate contamination was through the natural processes of separation, filtration, dilution, oxidation and chemical reaction. Soils were believed to serve the purpose of filtra-tion, aid in chemical reaction by adsorbing some chemicals, while ground-water was generally believed to be an infinite medium, thereby diluting any harmful chemicals. Not until the mid-1960s did organic contaminants begin to receive attention.

Some properties are associated with groundwater contamination that can be characterized as being comprised of Dense Non-Aqueous Phase Liquids (DNAPLs). DNAPLs are characterized by their lack of noticeable taste or odor and their higher density relative to water. These proper-ties render them difficult to detect and monitor. In contrast, petroleum spills float atop the water table and are usually volatile with distinctive tastes and odors. The rare discovery of DNAPL contamination before the development and ready availability of analytical techniques allowing the measurement of organic contaminants on the ppm to ppt level is not surprising.

Although appropriate analytical methods actively existed and were relied on by industry since the mid-1950s, there was no drive to investigate groundwater for the presence of chlorinated solvents. Analytical chemists instead concentrated efforts on alkyl benzene sulphonate (ABS) detergents and organic pesticides such as DDT and aldrin. The surreptitious nature of DNAPLs led them to be disregarded as groundwater contaminants until much later. Dissolved plumes caused by DNAPLs were not discovered until the 1970s. DNAPL (the free phase, not dissolved phase) was not discovered until the mid-1980s. This was partially because monitoring wells was not understood, as it is now, to be a poor method to detect DNAPL (i.e., it has rarely been reported in wells).

The discovery of DNAPLs was prompted by legislation introduced during the previous decade: Safe Drinking Water Act (1974), Resource Conservation and Recovery Act (RCRA, 1976) and the Comprehensive


Environmental Response, Compensation and Liability Act (CERCLA, 1980). These legislations required sampling of municipal wells specifically for chlorinated solvents, which were discovered in some drinking water systems. Unlike some other contaminants, such as methyl tert-butyl ether (MTBE), chlorinated solvents have high taste and odor thresholds, mean-ing that people don’t taste or smell the compounds in water until there is a relatively high concentration. Chlorinated solvents have taste thresh-olds around several hundred μg/L (i.e., ppb) whereas MTBE is nearly two orders of magnitude lower. Furthermore, taste thresholds are highly dependent on the individual.

The 1980s ushered in a vast cache of knowledge supported by reports and peer reviewed publications concerning groundwater investigations and DNAPLs. During this time period the evolution of vapor intrusion pathway (VIP) science also took place.

VIP refers to the migration of vapors from the soil zone into structures. The pathway starts from the groundwater to soil gas pathway. The origins of VIP may be traced back to the 1930s when petroleum exploration by soil gas analysis for hydrocarbons was first understood, but not from an environmental aspect. From the 1950s onward it was common practice to use volatile chemicals as root zone fumigants. This application added to the general knowledge of VIP, but there was no link to environmental con-cerns. In the 1960s vapor intrusion began to be understood as a risk associ-ated with acute exposure or fire/explosion, mostly from petroleum wells. The American Petroleum Institute (API) published warnings, guidelines and best practices to reduce these risks associated with well drilling and exploration activities.

Beginning in the early 1960s and onward landfill gas surveys and radon surveys were steadily reported in the industry and in the scientific litera-ture. In the 1970s VOC plume mapping by soil gas surveys began to evolve. By the late 1980s VOC plume mapping by soil gas surveys was a well- established and standard technique used in environmental investigations.

Throughout the 1980s vapor intrusion risk from acute exposure and chronic risks began to be considered in tandem where acute chemical risks were identified. Chronic exposure and risks via the VIP was recognized in the late 1970s/early 1980s which gave rise to OSHA’s focus on VOCs as inhalation carcinogens (1970s); and then in the early 1980s it was rec-ognized as a mainstream topic of concern for residential indoor air qual-ity. The most significant topic of VIP in the early 1980s concerned radon intrusion.

Along with the evolution of science, best practices and tools for indus-try, statutory evolution took place. In 1980 RCRA 261.31 F001 listing of


spent degreasing solvents became an obligation. The U.S.EPA defined TCE and PCE mobility in groundwater along with the properties of volatility and carcinogicity, and further acknowledged the pathway of vapor intru-sion into the basements of buildings as a human health risk.

In 1984 the U.S.EPA published a nationwide strategy for groundwater protection3. It stated that “ground water contamination looms as a major environmental issue of the 1980’s. The attention of agencies at all levels of government, as well as that of industry and environmentalists, is now focused on this vital resource. As contamination has appeared in well water and wells have been closed, the public has expressed growing con-cern about the health implications of inappropriate use and disposal of chemicals. As concern has increased, so have demands for expanded pro-tection of the resource.”

In 1985 through Love Canal Enforcement actions the well-known, so-called Murphy Models were applied to assessing VIP into basements as part of performing risk assessments; and in 1986 RCRA OSWER4 Corrective Action directives required that investigations be conducted in environ-mental site assessments in order to characterize subsurface gasses from buried waste and hazardous constituents found in groundwater.

In 1989, RFI Guidance for Conducting RI/FS5 noted inter media trans-fer from groundwater to soil gas to air. In 1992 Air/Superfund guidance and best practices were published (U.S.EPA - “Assessing Potential Indoor Air Impacts for Superfund Sites”). This document includes case stud-ies. In 1993 a further Air/Superfund guidance document was published

3U.S. Environmental Protection Agency, Office of Ground-Water Protection, Washington,

DC, August 1984.4OSWER stands for Office of Solid Waste and Emergency Response. This office has the

responsibility of overseeing the Superfund program.5RI/FS refers to remedial investigation/feasibility study. The remedial investigation serves as

the mechanism for collecting data to characterize site conditions; determine the nature of

the waste; assess risk to human health and the environment; and conduct treatability testing

to evaluate the potential performance and cost of the treatment technologies that are being

considered. The FS is the mechanism for the development, screening, and detailed evalua-

tion of alternative remedial actions. The RI and FS are conducted concurrently – data col-

lected in the RI influence the development of remedial alternatives in the FS, which in turn

affect the data needs and scope of treatability studies and additional field investigations. This

phased approach encourages the continual scoping of the site characterization effort, which

minimizes the collection of unnecessary data and maximizes data quality. A wide variety

of technologies are used throughout the remedial investigation and feasibility process. The

RI/FS process includes these phases: Scoping; Site Characterization; Development and

Screening of Alternatives; Treatability Investigations; and Detailed Analysis. (U.S.EPA 2013).


(“Options for Developing and Evaluating Mitigation Strategies for Indoor Air Impacts at Superfund Sites”). This publication includes examples, case studies and best practices.

From the mid-1990s onward several states began to require VIP evalu-ations when conducting an environmental site assessment. These states were Massachusetts, Michigan, Connecticut, and Rhode Island. In later years more states added such requirements. In 1994 and again in 1995 the ASTM developed separate but complementary guidelines for conducting general Phase I and Phase II site assessments. In 1996 U.S.EPA published the NPL (National Priority List) Guidance document titled “Soil Screening Guidance User’s Guide.”

The ASTM developed the RBCA standard for petroleum releases that includes VIP. RBCA stands for Risk-Based Corrective Action, which is a generic term for corrective action strategies that categorizes a site accord-ing to risk and moves the site toward completion using appropriate lev-els of action and oversight. The most recent ASTM standard provides a framework for implementing a RBCA strategy. With this process, regu-lators and investigators can make sound, quick, consistent management decisions for a variety of sites using a three-tiered approach to data collec-tion and site review contained in ASTM’s E1739 standard guide for “Risk-Based Corrective Action applied at Petroleum Release Sites.”

The RBCA helps to categorize sites according to risk, allocate resources for maximum protection of human health and the environment, and provide resources for appropriate levels of oversight. These actions are intended to assist sites to move forward quickly towards defining risks and mitigating them.

The ASTM RBCA standard, like the early ones established by the U.S.EPA in 1985, is intended to identify exposure pathways and receptors at a site; determine the level and urgency of response required at a site; determine the level of oversight appropriate for a site; incorporate risk analysis into all phases of the corrective action process; and enable selection of appropriate and cost-effective corrective action measures. RBCA is not a substitute for corrective action, but a tool for determining the amount and urgency of action necessary.

The ASTM standard (E1739) is based on a “tiered” approach to risk and exposure assessment, where each tier refers to a different level of complex-ity. The goal of all of ASTM’s tiers is to achieve similar levels of protection. The difference is that, in moving to higher tiers, more efficient and cost-effective corrective action results because the conservative assumptions of earlier tiers are replaced with more realistic site-specific assumptions. Additional site assessment data may be required as sites move to higher


tiers. In contrast to earlier approaches to conducting site assessments which tend to be executed in steps, the approach taken today is more streamlined.

In 2001/2002 the U.S.EPA published “Guidance for Evaluating the Vapor Intrusion to Indoor Air Pathway From Groundwater and Intrusion to Indoor Air Pathway from Groundwater and Soils.”

Beginning circa 1980, the U.S.EPA began to steadily develop best prac-tices for conducting environmental site assessments. These best practices were widely published and accessible to industry. By 1985 well-defined best practices were established, constituting the foundation for further refine-ments over the next decade. From about 1995 onward, further refinements to both technologies that aid in site assessments as well as more refined best management practices were devised and published by the American Society of Testing Materials (ASTM) and later further refined by such orga-nizations as the World Bank Organization (WBO), ANSI, ISO, and others.

In 1985 U.S.EPA published a three-volume manual of best practices for industry to follow when conducting environmental site assessments. The first volume was titled: Characterization of Hazardous Waste Sites: A Methods Manual, Volume I – Site Investigations6. The following are excerpts from the publication, annotated in some instances with my comments. Overall the statements and recommended good industry practices are self-evident.

“At the first meeting of the Agency-Wide Steering Group for the Development of a Methods Manual for Characterization of Hazardous Waste Sites in August 1981, the scope of the planned Available Methods Manual was expanded from sampling and analysis to site characterization. The steering group agreed that sampling and analysis of hazardous wastes must be closely tied to sampling and analysis strategy. Before methods can be useful, they must be related to the purposes and objectives of sampling and analysis. Such an association leads to the necessity of considering all aspects of hazardous waste site characterization.”

As early as 1981 the U.S.EPA recognized and recom-mended that proper site characterization requires that a strategy with clearly defined objectives be established in order to properly identify and characterize the environ-mental conditions of a property.

6Characterization of Hazardous Waste Sites: A Methods Manual, Volume I – Site Investigations,

EPA/600/4-84/075, April 1985.


“The objective of this manual is to provide field and labo-ratory managers, investigators, and technicians with a con-solidated source of information on the subject of hazardous waste site characterization. The manual covers the range of endeavors necessary to characterize hazardous waste sites, from preliminary data gathering to sampling and analysis.”“Because of the large number of subjects covered in this manual and the need to provide detailed methodology in the areas of sampling and sample analysis, this manual com-prises three volumes: Volume I - Site Investigations; Volume II - Available Sampling Methods; Volume III - Available Laboratory Analytical Methods.”U.S.EPA’s 1985 multi-volume manual of practices pro-vides guidance on information-gathering activities in support of the requirements specified in the National Oil and Hazardous Substances Pollution Contingency Plan. “The National Contingency Plan contains a seven-phase approach to implementing the authority of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA). Each phase represents a level of response dependent upon the situation. Information must be obtained to determine the appropriate level of environmental response. Both remedial and enforcement actions under CERCLA require reliable site information. This volume describes approaches to obtaining this information and follows a semi-chronological order through subsequent phases of the National Contingency Plan. These steps range from preliminary data gathering, to site inspections, to large field investigations.”

U.S.EPA’s manual described policies and procedures common to all data-gathering efforts, such as personal conduct, document control, and quality assurance. Sections included in the manual provided a framework for gathering the required information. U.S.EPA detailed what information is necessary, where that information can be found and how the information can be acquired in an environmental site assessment. Its manual presented topics such as investigative conduct, documentation and recordkeeping, quality assurance, site entry, etc., from the viewpoint of Agency policy. It stated that although its discussions were based on EPA policy, they were intended to “serve as a guideline for anyone conducting a hazardous waste site investigation.”


U.S.EPA stated that the following requirements constitute good practices: Persons conducting hazardous waste site investigations must “develop and report the facts of an investigation completely, accurately, and objectively.”

On p. 2–3 of EPA’s document control practices are discussed. “The pur-pose of document control is to assure that all project documents issued to or generated during hazardous waste site investigations will be accounted for when the project is completed. The purpose is achieved through a pro-gram which makes all investigation documents accountable. This should include serialized document numbering, document inventory procedures, and an evidentiary filing system. Accountable documents used or gener-ated during investigations include: Project Work Plans, Project Logbooks, Field Logbooks, Sample Data Sheets, Sample Tags, Chain-of-Custody Records and Seals, Laboratory Logbooks, Laboratory Data, Calculation, Graphs, etc., Sample Checkout, Sample Inventory, Internal Memos, External Written Communication, Business Confidential Information, Photographs, Drawings, Maps, Quality Assurance Plan, Litigation or Enforcement Sensitive Documents, and Final Report.”

EPA recognized that site investigations have the potential to generate large volumes of information and reports and that document control is an essential element to controlling information, and in support of any analy-sis applied towards remediation. It recommended that each document be assigned a “serialized number” and be “listed, with the number, in a proj-ect document inventory assembled at the project’s completion.” Volume II, Appendix D, provides further discussion of Document Control/Chain-of-Custody Procedures.

Beginning on p. 2–17 of Volume I U.S.EPA recommended good prac-tices to be applied in environmental site assessments to ensure high qual-ity and reliability throughout the assessment and in developing remedial actions.

Section 4 (beginning p. 4–1) of EPA’s 1985 good practices manual pro-vides practices, protocols and stepwise procedures for data gathering in order to perform a proper environmental site assessment. EPA recom-mended that a task should be “initiated to collect and review available infor-mation about the known or suspected hazardous substance site or release.” EPA’s recommended practices constitute what is commonly referred to as a Phase I environmental audit.

In Section 5 beginning on p. 5–1 EPA provided detailed procedures, pro-tocols and best practices for conducting site inspections. It defined these as being important components of Phase II, Preliminary Assessment and Phase IV, Evaluation and Determination of Appropriate Response - Planned Removal and Remedial Action. It stated that the “major objective of a site


inspection is to determine if there is any immediate danger to persons living or working near the facility.” It explained in great detail the recommended practices, protocols and procedures for conducting these activities and stated that the primary items addressed during the site inspection are:

1. “A determination of the need for immediate removal action”;2. “An assessment of the amounts, types and location of stored

hazardous substances”;3. “An assessment of the potential for substances to migrate”;

and4. “Documentation of immediate threats to the public or

environment”.

The section covers various topics and best practices for conducting pre-liminary site investigations, Phase I site investigations, Phase II site investiga-tions, and conducting remedial investigations. The recommended practices are detailed and stepwise. It stated for examples (p. 5–6) that “Inspections of basins and vessels should verify structural dimensions and note the num-ber and location of input or discharge lines. Any manways, hatches, or valve pits should be identified and monitored with the survey instruments. If the structures contain a material, an estimate of percent full (look for staff gauges or site glasses) and a description of the material should be noted. A general assessment of structural condition also should be included…. The presence of buried vessels is often only apparent upon discovery of small standpipes or vents protruding above the ground surface. All such pipes should be noted and marked with colored tape and/or flags. Closer investigation of the immediate vicinity of the vents often uncovers hatches or valve pits. Further investigation during the inspection should be limited to screening the vents and hatch seals with an OVA, HNu or other monitors…”

On p. 5–7 EPA recommended that “information regarding population size and distribution should be available from the preliminary assessment. In many instances this information, if obtained from state or regional agencies will be somewhat dated. It is important therefore to tour the area assessing the likelihood of significant demographic changes. Recently con-structed housing developments, apartments, schools and public buildings may indicate that changes have occurred since the information was pub-lished.” Such practices were recommended in order for the environmental site assessment to define the potential risks of hazardous substances on-site to neighboring off-site receptors.

Beginning on p. 6–1 EPA addressed the need and best practices for data evaluation. It wrote that “a data assessment is performed to ultimately


assist in formulating response management decisions affecting later stages of the investigation. The data evaluation may also indicate data gaps which need to be filled either by further background research or additional site inspections (or an initial inspection if one has not yet been conducted)… The evaluation should encompass the scope detailed below:

1. the existence (or nonexistence) of a potential hazardous waste problem;

2. probable seriousness of the problem and the priority for fur-ther investigation or action; and

3. the type of action or investigation appropriate to the situation.”

In 1996 the ASTM published its standard Designation: E 1528 – 96: Standard Practice for Environmental Site Assessments: Transaction Screen Process. It wrote, “The purpose of this practice, as well as Practice E 1527, is to define good commercial and customary practice in the United States of America for conducting an environmental site assessment of a parcel of commercial real estate with respect to the range of contaminants within the scope of the Comprehensive Environmental Response Compensation and Liability Act (CERCLA) and petroleum products…” It further defined the term Recognized Environmental Conditions: “In defining a standard of good commercial and customary practice for conducting an environmental site assessment of a parcel of property, the goal of the processes established by this practice is to identify recognized environmental conditions. The term recognized environmental conditions means the presence or likely presence of any hazardous substances or petroleum products on a property under con-ditions that indicate an existing release, a past release, or a material threat of a release of any hazardous substances or petroleum products into struc-tures on the property or into the ground, groundwater, or surface water of the property. The term includes hazardous substances or petroleum products even under conditions in compliance with laws. The term is not intended to include deminimis conditions that generally do not present a material risk of harm to public health or the environment and that generally.”

It further wrote, “Objectives guiding the development of this practice and Practice E 1527 are (1) to synthesize and put in writing good com-mercial and customary practice for environmental site assessments for com-mercial real estate, (2) to facilitate high quality, standardized environmental site assessments, (3) to ensure that the standard of appropriate inquiry is practical and reasonable…”

It also wrote, “This practice and Practice E 1527 are designed to assist the user in developing information about the environmental condition of a