Jeffrey A. Adams, PhD, PE Krishna R. Reddy, PhD, PE, D.GE

Jeffrey A. Adams, PhD, PE

Krishna R. Reddy, PhD, PE, D.GE

The State-of-the-Practice of Characterization and Remediation of

Contaminated Sites

Presentation Outline

‣Historical context and regulatory framework

‣Evolution in practice

• Site characterization• Risk assessment• Site remediation

‣Questions





‣Questions

Petroleum Industry

‣ Between 1950 and 1972, world energy consumption increased 179%

Doubled per capita consumption

‣ Oil consumption rose from 29% of energy consumption in 1950 to 46% in 1972

‣ 47% of US energy consumption by 1973

‣ 64% of western Europe; 80% of Japan energy consumption by 1973

‣ Petrochemicals were rapidly replacing glass, wood, natural rubber, iron, copper, aluminum, and paper

Pesticide Use

‣ Tenfold in pesticide expenditures between 1945 and 1972

‣ Pesticide production

Less than 100 million pounds in 1945 Over 600 million pounds by 1960

‣ Herbicide use

1952, 11% of corn and 5% of cotton acreage

1982, risen to 95% of corn and 93% of cotton

Source: livinghistoryfarm.org

Donora 1948 Smog Disaster

‣ Monongahela River Valley mill town

‣ In 5 days, 20 died and 7,000 became sick

‣ Temperature inversion trapped noxious emissions

Sulfur dioxide

Carbon monoxide

Metal dust

Source: www.pollutionissues.com

Los Angeles

Air Pollution Control Act

‣Passed in 1955

‣Initial attempt at addressing growing air pollution

‣Acknowledged air pollution was a growing threat to public health

‣LimitationsDeferred authority to statesDid not include power to sanction

or penalize

Cuyahoga River

1969 Santa Barbara Oil Spill

‣Blowout of oil well

‣3 million gallons of crude oil spilled, fouling beachesand wildlife

‣Inspired the formation of Earth Day

‣Sierra Club membership reportedly doubled in the following 2 years

Grass Roots Inspiration and Reaction

‣1962 – Silent Spring• Reaction to DDT spraying for mosquitoes• Contributed to ban in US

‣1968 Apollo 8 mission

‣1970 – Earth Day• Political groups• Business groups• Activist groups

‣ 1965, 1970 –first federal legislation regulating municipal solid waste • Reduction of solid waste volumes to protect human health

and environment• Improvement of waste disposal practices• Provisions funds to individual states for solid waste

management

‣ 1970 Amendments• Encouraged further waste reduction and waste recovery • Created system of national disposal sites for hazardous waste

National Environmental Policy Act (1969)• Council of Environmental Quality, a new executive branch

agency Environmental Protection Agency • Environmental Impact Statement (EIS) for any federal project

Solid Waste Disposal Act (SWDA)

‣ CWA 1977, 1981, and 1987 – Regulates discharges into U.S. waters • 129 priority pollutants were identified as hazardous wastes• National Pollutant Discharge Elimination System (NPDES)

permitting• Dredged material discharge only allowed with permit• Wastewater discharge treatment requirements• Discharges from POTWs must meet pre-treatment standards

‣ SDWA 1974, 1977, and 1986 – Protection of drinking water quality • MCLs, primary and secondary goals• Regulation of hazardous waste injections into subsurface• Designation and protection of aquifers

Clean Water Act (CWA) and Safe Drinking Water Act (SDWA)

‣ 1976 – Regulation and use of hazardous chemicals

• Industries required to report/test chemicals that may pose an environmental or human health threat

• Prohibition of the manufacture and import of chemicals that pose an unreasonable risk

• Requirement of pre-manufacture notifications to the USEPA

• Prohibition of PCBs

• Management of asbestos

Toxic Substances Control Act (TSCA)

‣ Many of the previous acts lacked enforcement ability and had loopholes

‣ Encouraged “shortcut” behaviors

‣ Few landfill regulations

Unintended Consequences…

‣ Passed to manage nonhazardous/hazardous wastes, USTs

‣ Emphasis on recovery/recycling instead of disposal • Subtitle C – control of hazardous wastes• Subtitle D – management of nonhazardous wastes• Subtitle I – UST regulations

‣ Amendments in 1984• Restrictions on liquid waste• New UST regulations• Landfill liner, leachate collection, and monitoring

requirements• Small generator and TSDF requirements• USEPA authorized to inspect, enforce, and penalize

Resource Conservation and Recovery Act (RCRA) - 1976

Love Canal

‣Toxics placed in canal; capped with clay

‣Residential and school construction on top of canal

‣Noxious odors and acute health problems observed

‣Confirmed presence of widespread soil and groundwater contamination

‣U.S. government paid for the relocation of hundreds of residents

‣ Addresses abandoned/uncontrolled hazardous waste sites necessitating immediate cleanup

‣ Fund from taxes on chemical/petroleum companies • $1.6 Billion ($5 Billion in 2011 dollars)

‣Identified PRPs as current or past owners of site as well as generators and transporters

‣ Hazard Ranking System- Population, degree/nature of contamination, pathways• Sites scoring “high enough” added to National Priorities List

‣ Methods evolved to study sites• Remedial Investigation – characterizes site• Feasibility Study – considers remediation alternatives

Comprehensive Environmental Response, Compensation,

and Liabilities Act (CERCLA), or “Superfund” (1980)

‣ $8.5 billion for site cleanup; $500 million for USTs • $18.9 billion and $1.1 billion in 2011 dollars, respectively

‣ Established community right-to-know provisions

‣ Standard framework – Applicable or relevant and appropriate requirements (ARARs) – chemical specific, action specific, and location specific

‣Established liability for innocent purchasers and landowners • Gave rise to Phase I, II, and III studies

‣ Also, annual hazardous substance release reporting requirements

Superfund Amendments and Reauthorization Act (SARA)

‣ Often driven by property transaction

‣ Many “flavors” (screen, update, PEA); “strongest” flavor provides liability protection – AAI – ASTM 1527-05

‣ Clear requirements about content, shelf life, etc.

‣ Report summarizes site history• Radius report• Aerial photographs• Topographic maps• Title reports/lien search• File reviews of numerous agencies• Interviews

‣ Identify data gaps

‣ Recognized Environmental Conditions (RECs)

CERCLA/RCRA – ESA1

‣ Follow-up on findings of Phase One ESA

‣ Field characterization• Soil, groundwater, soil vapor

‣ First efforts often general; follow-up work may occur

‣ Soil, groundwater, and/or soil vapor sampling

‣ Laboratory analysis for target analytes

‣ Consider results with screening values• MCLs, PRGs/RSLs, state criteria


‣ Goal: remediate the site to an acceptable level of risk for future use• Dependent on anticipated land use• Regulatory oversight – NFA status

‣ Develop a remedial approach to mitigate site contamination

‣ Cost-benefit analysis• Cash flow considerations• Tax incentives

‣ “Real time” and post-remediation monitoring


‣ When enacted, 36,000 sites identified; 1,200 placed on NPL

‣ As of end of FY 2010• 1,627 sites remain on NPL• 475 sites have been closed• $40 million per site (2011 $); 11 years on average to close• $40 million x 1,627 = $65.1 billion• $1.2 billion / 400,000 LUSTs = $3,000 per LUST

‣ $6 billion in trust in 1996 exhausted by 2003 (general Congressional appropriations since 2003)

CERCLA Progress

‣ EPA Superfund 2008 FY progress:

• Controlled all identified unacceptable human exposures at a net total of 24 sites, exceeding the annual target of 10”

• “Controlled the migration of contaminated ground water through engineered remedies or natural processes at a net total of 20 sites, exceeding the target of 15 for the year”

• Spent $500 million

CERCLA Progress (Cont.)

Brownfields Concepts and Framework

‣Desire to pursue “land recycling”• remediate to anticipated land use and

exposure

‣Small Business Liability Relief and Brownfields Revitalization Act (2002)• Promotes cleanup and reuse of

brownfields• Liability relief to small businesses

• Provides financial assistance

• Enhanced state programs

• Liability protection for prospective purchasers, contiguous property owners, and innocent landowners

Legal and Engineering Controls

‣Land use legal controls• Deed restrictions• Easements for long-term monitoring

‣Engineering controls• Vapor barriers

• Venting systems

• Long-term collection and treatment

‣ Collaborative local/state framework

• Voluntary agreement between RP and agency

• Often feature a formal agreement w/ timeline, cleanup goals, and reimbursement

• Goal is to achieve a No Further Action (NFA) Status

• Cost-benefit analyses are common to select remediation alternative

Voluntary Site Remediation Programs





‣Questions

“Traditional” Soil and Groundwater Characterization

‣Soil sampling and laboratory analysis

‣Groundwater• Monitoring wells• “Grab samples”

‣Precise, quantitative (and expensive) data

‣USEPA SW-846• Guidance for compliance with

RCRA regulations

• Basis for other methods

Direct Push Soil and Groundwater Sampling

‣Cost-effective alternative to conventional rotary drilling

‣Reduces IDW volume

‣Soil

‣Groundwater• “Grab” sampling• Temporary or permanent

packed wells

Innovative Characterization Technologies

‣Analytics• Membrane Interface Probe • X-ray Fluorescence• Fiber Optic Chemical Sensors• Laser-induced Fluorescence• Immunoassays

‣Geophysics• Ground Penetrating Radar• Magnetics

Membrane Interface Probe (MIP)

‣Advanced with direct push rig

‣Continuous, real-time profile of hydrocarbon/VOC impacts

‣Three detectors used to analyze a range of contaminants✓ Electron capture detector (ECD)✓ Photo ionization detector (PID) ✓ Flame ionization detector (FID)

‣Semi-quantitative locating of “hot spots”

Membrane Interface Probe (MIP)

X-Ray Fluorescence

‣Hand-held field unit or direct-push system

‣Soil bombarded with x-rays; induces fluorescence

‣“Hits” are unique to element (more hits = higher concentration)

‣Portable, fast, multiple analyses; best for metals

‣Detection limits exceed action levels for some analytes

‣Licensing issues due to radioactive source

Fiber Optic Chemical Sensors (FOCS)

‣Optical fiber used to transport light

‣ Interaction of the analyte with fiber creates a detected reaction • Absorbance• Reflectance• Fluorescence• Light polarization

‣Detected intrinsically or extrinsically

‣Real-time, transmits a long distance, multi-compound analysis

‣High detection limits, gross estimation, time and temperature sensitivities

Laser-Induced Fluorescence‣Fiber optic-based, direct push system

‣Induces fluorescence of aromatic compounds or PAHs

‣Peak wavelength and intensity used to infer contaminant type or relative concentration

‣Real-time; semi-quantitative

‣No cuttings, continuous logging, minimally invasive

‣Cost-prohibitive on small projects

‣Select minerals and organic matter may cause interference

Immunoassays‣Use of biological systems to detect

target analytes (organic compounds, some metals)

‣Colorimetric analysis based on analyte and relative concentration

‣Compared with standard chart or with photometer

‣Fast, easy, portable, inexpensive low detection limits

‣Pre-prediction of target analytes, some analytes yield questionable results, field conditions can affect reactions

Ground Penetrating Radar (GPR)‣GPR uses high frequency pulsed

electromagnetic waves

‣Energy is propagated downward and reflected back, showing contrasts

‣Locate pipes, drums, tanks, cables, and boulders, landfill and trench boundaries, mapping contaminants

‣Easy; non-intrusive; in-field data review possible

‣Interpretation requires skilled personnel; depth of penetration affected by subsurface conditions

Magnetics‣Used for locating subsurface ferrous

alloys

‣The stronger the force, the greater the ferrous mass

‣Used to locate drums, tanks, pipes, ordnance, abandoned well casings, boundaries of landfills (if ferrous metal present), and mineralized iron ores

‣Simple, portable, easy to operate, accurate, less susceptible to interference

‣Limited information on depth, specific applicability

Special Challenges and Approaches

in Site Characterization

Fractured Rock‣ Contamination presents several challenges

• Contaminant movement along bedding planes, joints, fractures

• Fluid diffusion into the matrix• NAPL flow very complex

✓ Capillarity, gravity, viscosity considerations

‣ Downhole geophysical methods

‣ Televiewers (optical and acoustic)

‣ Coring methods

‣ Groundwater flow modeling• Pumping tests• Monitoring wells• Tracer testing• Flowmeter testing

Dense Nonaqueous Phase Liquids (DNAPLs)

‣Heavier than water; low solubility; pooling issues

‣Often difficult to find source• Traditional soil and groundwater

sampling is “hit-or-miss”

‣Geophysical methods

‣Innovative characterization technologies• Membrane interface probe• Laser-induced fluorescence

Triad - EPA

‣EPA framework for site characterization and remediation that incorporates three key principles:• Systemic planning – key decisions,

conceptual site model, identifying and mitigating potential uncertainty

• Dynamic work strategies – characterization and monitoring; flexibility to make decisions based on incoming data

• Real-time measurement – rapid lab TAT, mobile lab, characterization technologies

Soil Vapor Sampling

‣Vapor samples collected directly from subsurface

‣Temporary or permanent sampling wells

‣Replacing modeling and passive indoor sampling

‣Leak detection methods• Common compounds applied

at connections• Positive pressure inert gas

environment (“shroud”)

Mass Flux/Mass Discharge Approach

‣Alternative to analysis based on point concentrations

‣Mass flux – mass/time/area

‣Mass discharge – mass/time

‣Parameters can help answer:• Is plume stable?• How will remediation affect

fate/transport?• When to introduce additional remedial

technologies?

‣Transect method, well pumping, or in-well meters





‣Questions

Pre-Risk Era (Early 80s)

‣Remediation goals often set to “pristine” condition/restoration• e.g., groundwater MCLs

‣Proved to be cost and time prohibitive

Emergence of Risk Era

‣National Research Council/National Academy of Sciences (NRC/NAS)

‣RED BOOK (1983) Risk Assessment in the Federal Government: Managing the Process • Addressed health risk assessments across

all Federal Agencies

• Defined four-step risk assessment process

• Steps used in several EPA statutes but with different methods (e.g., RCRA, CERCLA, FIFRA, TSCA)

Four Steps of Risk Assessment and Risk Management

Hazard Identification

‣Determines if a compound is causally linked to health effects at environmentally relevant concentrations• Select Chemicals of Potential Concern (COPC)

• Establish relationship between each COPC and adverse health effects (review tox. data)

• Determine “critical” health effect for each COPC

• Evaluate scientific weight-of-evidence for “critical” health effects (cancer and non-cancer)

Dose-Response (Toxicity) Assessment

‣Determines relationship between the magnitude of the contaminant dose and the probability of occurrence and magnitude of health effect(s)

Exposure Assessment

‣Evaluation of exposure to each chemical by medium, receptor, and exposure route:

• Environmental Media: Concentrations in air, water, soil

• Receptors: Any potentially exposed group

• Routes: Ingestion, inhalation, dermal

• Cumulative exposure is important!!!!

‣Quantify exposures using exposure concentrations and intake variable data

Generic Equation for Estimating Chemical Exposures –Inhalation

Risk Characterization‣ Likelihood of injury, disease, or death resulting from exposure to a

potential environmental hazard

‣ Cancer Risk Equation

• Cancer Risk = L(ADD) x CSF

✓ Risk = incremental probability of an individual developing cancer from exposure

✓ L(ADD) = L(chronic lifetime daily dose averaged over 70 years

✓ CSF = cancer slope (or potency) factor

‣ Noncancer Risk Equation

• Hazard Quotient = ADD/RfD

✓ ADD = average daily dose (or intake)

✓ RfD = reference dose

✓ HI > 1 – potentially of health concern

‣ Assumes risk additive over all chemicals in mixture

‣ Address uncertainty and variability

Risk-based Screening/Corrective Levels

‣Calculate allowable concentrations in media based on allowable risk - inverse of USEPA approach

‣Risk-based Corrective Action (RBCA) for Petroleum Release Sites

• ASTM E1739

• Tiered Approach

‣States - examples

• Illinois: Tiered Approach to Corrective Action Objectives (TACO)- IAC 620

• California:

✓ Department of Toxic Substances Control (DTSC) – California Human Health Screening Levels (CHHSLs)

✓ San Francisco Bay Regional Water Quality Control Board (RWQCB) – Environmental Screening Levels (ESLs)

Ecological Risk Assessment

‣USEPA (1992): Evaluate the likelihood that adverse ecological effects result from exposure to one or more stressors (contaminants)

• Aquatic animals (e.g., fish and invertebrates)

• Terrestrial animals (e.g., birds and wild mammals)

• Plants, or other non-target organisms (e.g., insects)

• Includes endangered and threatened species





‣Questions

Remediation Implementation Strategy

In-Situ Containment

Traditional GW Remediation: Pump-and-Treat

Pump-and-Treat Limitations

‣Often reach asymptotic behavior short of cleanup goal

‣Can become expensive and time-consuming

‣What to do with the extracted groundwater?

Traditional Soil Remediation: Dig-and-Haul

Dig-and-Haul Limitations

‣Becomes prohibitive with larger, complex sites• Groundwater• Double-handling and characterization• Backfilling/staging• Surface obstructions

‣Tipping fees keep increasing

‣Regulators increasingly looking for alternatives• Emissions, space

Soil Vapor Extraction‣Vadose zone soil remediation technology

‣Vacuum is applied to the soil

‣ Induces volatilization, advection, diffusion, and desorption

‣Vents are typically used at depths 5 feet or greater

‣VOCs and volatile HC fractions (Henry's law constant > 0.01 or a vapor pressure > 0.5 mm Hg)

‣Limitations

• Vadose zone only

• Asymptotic behavior

• Ineffective in low-permeable and stratified soils

Soil Vapor Extraction

Air Sparging‣Saturated zone (soil and groundwater)

remediation technology

‣Air injected into subsurface; rises due to buoyancy (often with SVE system)

‣Effective for variety of phases (gas, sorbed, dissolved, free-phase)

‣ Induces volatilization, advection, diffusion, desorption, and biodegradation (increases dissolved oxygen)

‣VOCs and volatile HC fractions (similar to SVE criteria)

‣Limitations

• Best in homogenous soils

• SVE to control fugitive vapors

• Hydraulic conductivity > 1 x 10-3 cm/s

Air Sparging

Stabilization/Solidification or Immobilization

‣Involves mixing a binding agent into contaminated soil/groundwater

‣Binding agents: • Portland cementCement kiln dustFly

ashLimeSlagCement-based proprietary mixturesSilicate, phosphate, and sulfateImmobilizes hazardous constituents within treated materialPhysical (solidification) and chemical (stabilization) changes to the treated material

Thermal Methods

‣Heat can destroy or volatilize organic chemicals

‣Gases are mobilized for extraction and treatment

‣Useful for DNAPLs or LNAPLs

‣Methods can be in-situ or ex-situ

Thermal Methods

‣ Injection of hot air, hot water, or steam

‣Electrical Resistance heating – arrays of electrodes installed around a central neutral electrode creates concentrated flow of current toward the central point

‣Radio frequency heating – electromagnetic energy to heat soil using rows of vertical electrodes embedded in soil or other media

‣Thermal conduction – supplies heat to the soil through steel wells or with a blanket such that contaminants are destroyed or evaporated

‣Vitrification – uses an electric current to melt contaminated soil

• Vitrification product is chemically stable and leach-resistant

• Organic materials are destroyed or removed; radionuclides and heavy metals are retained within the vitrified product

Enhanced Bioremediation/Bioaugmentation

‣Goal: utilize microbial populations to break down contaminants

‣Contaminants are oxidized; oxygen and other compounds act as electron acceptor

‣Additives (oxygen, nutrients, co-metabolites, other microbes)

‣Monitor closely

‣Drawback – how to maintain ideal conditions?

Monitored Natural Attenuation

‣More than “leave it alone!”

‣Goal: let natural transport, transfer, and transformation processes take place (including biodegradation)

‣Monitor conditions, daughter products, etc.

‣Consider if conditions are ideal

Flushing

‣Purge contaminants using an aqueous flushing solution• Clean

waterSurfactantsCosolventsAcids/basesReductants/oxidantsHigh permeability soils

Permeable Reactive Barrier

‣Degrade or immobilize contaminants in groundwater as it passes through the barrier

‣Permeable reactive media in barrier• Zero-valent

ironZeolitesOrganobentonitesHydroxyapatiteContinuous Vs. Funnel-and-Gate PRBsLoss of reactivity and clogging issuesLonger treatment time

Chemical Oxidation/Reduction

‣Redox reactions chemically convert hazardous contaminants to nonhazardous or less toxic compounds

‣Redox reactions involve the transfer of electrons from one compound to another

‣One reactant is oxidized (loses electrons) and one is reduced (gains electrons)

Chemical Oxidation

‣Contaminants are chemically oxidizedHydrogen peroxide-based Fenton’s reagent, permanganate, and ozoneContaminants driven to harmless by-products (e.g., CO2, H2O, disassociated HCl)

‣Implications • Injection permitting, salts, Cr(VI) and

other metals mobilization

Chemical Reduction

‣Can be chemically induced (i.e., zero-valent iron)Anaerobic reductive dechlorination• Direct - Electron donor supplies hydrogen

(molasses, lactic acid, vegetable oil, beer, HRC)Co-metabolism (need co-substrate); degraded by enzymes by “mistake”Halogen replaced with hydrogen; gets worse before it gets betterNeed ideal bacteria and nutrients

Phytoremediation

‣Removal, stabilization or degradation of contaminants by plants

‣Applied at large sites with low contaminant concentrations (as polishing treatment)

‣Selection of plant species and fate of plants

ElectrokineticsLow-voltage direct current applied between electrodes Induces electrolysis reactions (oxidation at anode creates H+ ions; reduction at cathode creates in OH- ions) Electroosmotic flow toward the cathodeIons move toward electrodes; non-charged compounds travel with the pore fluid Often enhanced with co-solvents or reagents Reagent compounds dissolve into ions; migrate and reactOxidizing agents effective at oxidizing organic compounds

ElectrokineticsAdvantagesEffective in heterogeneous and/or clayey soils Effective in both the vadose zone and groundwaterMinimally invasiveCo-solvent or reagent enhancements Disadvantages Can be time-consumingSubsurface metallic structures can affect performance

Electrically Induced Redox Barrier

Fractured Rock – RemediationVery difficult to get an accurate characterization of flow systemPump-and-treat most common methodOther emerging technologies being usedBioremediationChemical oxidationChemical reductionThermal methods

DNAPLs – RemediationExcavation (if you can get to it)Pump-and-treat when applied judiciously“Innovative” in-situ methodsBioremediationChemical oxidation/reductionSVE/IASPermeable reactive barriersSolidification/stabilizationCombinations of these technologies

Mixed Contaminants -Remediation

Green and Sustainable RemediationPresidents’ Executive Orders13123-Greening the Government through Efficient Energy Management (6/1999) 13514-Federal Leadership in Environmental, Energy, and Economic Performance (10/2009)2011 NRC Green BookRecommends EPA to formally adopt sustainability approachFramework for EPA Sustainability DecisionsTheme – “Cleanup based on holistic approach (triple bottom line)”

Green and Sustainable Remediation“Traditional” approaches may result in negative net environmental benefitHolistic approach to environmental remediationMinimizes ancillary environmental impactsEfficiently remediates; protects air, water, and soil; reduces emissions and waste burdenUltimate goal is to maximize the Triple Bottom LineEconomicSocialEnvironmental

Triple Bottom Line

Thanks for your attention

Krishna R. Reddy, Ph.D., P.E.

Professor of Civil & Environmental EngineeringDirector, Geotechnical & Geoenvironmental Engineering Laboratory

Documents

Jeffrey A. Adams, PhD, PE Krishna R. Reddy, PhD, PE, D.GE