1FAX COVER SHEET

MARYLAND DEPARTMENT OF THE ENVIRONMENTWASTE MANAGEMENT ADMINISTRATION

ENVIRONMENTAL RESTORATION AND REDEVELOPMENT PROGRAMTELECOPIER NUMBER (410) 631-3472

DATE:

TO:-'"'• .

DEPARTMENT:

TELECOPIER:

FROM:

MARYLAND DEPARTMENTOF THE ENVIRONMENT2500 Broenlng HighwayBaltimore, Maryland 21224

James V. Gravette(410)631-3440 Otologist(410) 631-3472 FAX Federal/N?L Superfund Divincn

NUMBER OF PAGES INCLUDING COVER: J-

Eric Newman February 25, 1999Remedial Project ManagerWoodlawn Landfill Superfund Site

Eric,

Below is MDE's revised version of the landfill closure paragraph that wasincluded in the draft Proposed Plan for the Woodlawn Landfill site. Give me a call whenyou receive this information.

Landfill Closure: Alternative 1 includes an engineered closure cap, which is consistentwith the State's landfill closure cap requirements (COMAR 26.04.07.21). Alternative 2provides an alternative closure strategy, a vegetative cover. Although a vegetative coveris not consistent with the State's closure cap requirements, the State may grant a variance(COMAR 26.04.07.26) to the requirements if the proposed alternative protects publichealth and the environment and controls air, water and land contamination to at least thesame extent as an engineered closure cap. EPA and MDE have determined that avegetative cover, in conjunction with monitored natural attenuation, are now effectivelycontaining the contaminant plume and would be technically appropriate at this site,protective of public health and the environment, and control air, water and landcontamination to at least the same extent as meeting the State's landfill closure caprequirements. EPA and MDE based these determinations, in part, on field investigations,engineering analysis included in the Administrative Record and over 18 years ofgroundwater data collected at the site and evaluated, to determine the effectiveness of avegetative cover remedy.

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SUPERFUND PROGRAMPROPOSED PLAN FOR ACHANGE IN REMEDYWoodlawn Landfill SiteColoraCecil County, Maryland March 1999

INTRODUCTION

This Proposed Plan has been prepared by the U.S. Environmental Protection Agency (EPA) toprovide the public with the opportunity to review and comment upon two alternatives foraddressing contaminated ground water and preventing exposure to municipal and industrialwaste and contaminated soil at the Woodlawn Landfill Superfund site. It contains a briefcomparative evaluation of the remedial alternative EPA selected for the site in its September 28,1993 Record of Decision (ROD) and a new alternative for site remediation which EPA did notconsider prior to issuing the ROD in 1993 but which the Agency has since identified as thepreferred alternative for addressing contamination at the site. Ground water studies conducted atthe site in 1997, and summarized below, support EPA's selection of a new preferred alternativefor addressing the site.

EPA, which is the lead agency for site activities, will select a final remedial alternative for theWoodlawn Landfill Superfund site hi consultation with the Maryland Department of theEnvironment (MDE), the support agency for this response action, only after careful considerationor any information submitted by the public during the public comment period. EPA is issuingthis Proposed Plan as part of its public participation responsibilities under Sections 113(k)(2)(B)and 117(a) of the Comprehensive Environmental Response, Compensation, and LiabilityAct of 1980, as amended (CERCLA), 42 U.S.C. §§ 9613(k)(2)(B) and 9617(a).

This Proposed Plan is based on information in site-related documents contained in theAdministrative Record for the Site, including the Remedial Investigation, the Baseline RiskAssessment, the Focused Feasibility Study Ground Water Remedy, and the Focused FeasibilityStudy Final Cover System. The Administrative Record is at the following locations:

Cecil County Public Library301 Newark Avenue

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Elkton, MD 21903(410) 996-5600Hours: Monday - Thursday, 10:00 a.m. - 9:00 p.m.

Friday - Saturday, 10:00 a.m. - 5:00 p.m.

Perryville Public Library515 Broad StreetPerryville, MD 21903(410) 996-6050Hours: Monday - Wednesday, 10:00 a.m. - 5:00 p.m.

Thursday, 12:00 p.m. - 8:00 p.m.Saturday, 10:00 a.m. - 5:00 p.m.

U.S. EPA Region IIIMs. Anna Butch6th Floor Docket Room1650 Arch StreetPhiladelphia, PA 19103(215)814-3157Hours: Monday - Friday, 8:30 a.m. to 4:30 p.m.

EPA and MDE encourage the public to review and comment on each of the clean-up optionsevaluated in this Proposed Plan, and other documents hi the Administrative Record file, duringthe public comment period, which begins on March 24,1999 and closes on April 26,1999. OnApril 15,1999, at 7:00 p.m., EPA will hold a public meeting to discuss the Proposed Plan at theElkton Middle School, 615 North Street, Elkton, Maryland. Written comments, postmarked nolater than April 26,1999, should be sent to:

Eric Newman (3HS23)Remedial Project ManagerU.S. Environmental Protection Agency1650 Arch StreetPhiladelphia, PA 19103

Although EPA has identified a preferred alternative, no final decision has been made. EPA maymodify the Preferred Alternative, select another response action or develop another alternative, ifpublic comment warrants or if new material is presented. EPA in consultation with MDE willmake its final selection of a remedy for the contamination at the Site in a Record of DecisionAmendment (Amended ROD).

A glossary explaining terms that may be unfamiliar to the general public is provided at the end ofthis Proposed Plan. Glossary terms are noted by bold print the first tune they appear hi the text.

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SITE HISTORY. CONTAMINATION. AND SELECTED REMEDY

The Woodlawn Landfill site is located in a rural and residential area approximately one milenorth of the intersection of Routes 275 and 276 in northwestern Cecil County, Maryland. TheWoodlawn Transfer Station, which began operations in June 1978, is located hi the northeastcorner of the site near the intersection of Firetower Road and Waibel Road (see Figure 1).

The 38-acre site property was a privately owned sand and gravel quarry before 1960 when it waspurchased by Cecil County. The County owned and operated a municipal landfill at the site from1960 until June 1978 when the landfill was closed to municipal waste under order from the Stateof Maryland Department of Health and Mental Hygiene (MDHMH).

From 1960 to 1978, agricultural, municipal and industrial wastes were disposed at the site.Among these wastes was polyvinyl chloride (PVC) sludge from the Firestone Tire & RubberCompany's nearby facility. The PVC sludge, which contained residual vinyl chloride, wasinitially disposed throughout the landfill. Between March 1978 and early 1981 the sludge wasdisposed in designated areas at the site, Cells A and B/C, under the terms of an Industrial WasteDisposal Permit issued to Firestone by MDHMH. In 1981, the State identified contaminants,including vinyl chloride and other organic compounds, in ground water samples collected frombeneath the landfill property with the highest concentrations found in monitoring wells locateddowngradient of Cell B/C.

EPA placed the site on the National Priorities List (NPL) on July 1,1987. On December 28,1988, EPA and two of the Potentially Responsible Parties (PRPs), the Firestone Tire & RubberCompany (Bridgstone/Firestone) and Cecil County, entered into an Administrative Order onConsent whereby the two PRPs agreed to perform a Remedial Investigation and FeasibilityStudy (RI/FS) with EPA oversight.

The Remedial Investigation, completed in 1992, identified the nature and extent ofcontamination present at the site. Ground water was found to be contaminated with vinylchloride, 1,2-dichloroethane and other volatile organic compounds (VOCs), polynucleararomatic hydrocarbons (PAHs), bis(2-ethylhexyl)phthalate, pentachlorophenol, pesticides,cadmium and manganese at levels that exceeded Maximum Contaminant Levels (MCLs) forpublic drinking water supplies or risk- and health-based concentrations. Vinyl chloride andmanganese are the most commonly detected and widely distributed ground water contaminants atthe site and were determined to be the greatest sources of carcinogenic and noncarcinogenic risk,respectively. Unrelated to the site landfilling activities, mercury was found in soil within theimmediate vicinity of the former dram field of the Transfer Station septic system atconcentrations greater than the level known to be protective of ecological receptors. TheFeasibility Study, completed in 1993, evaluated alternatives to reduce the potential riskspresented by hazardous substances at the site.

On June 8,1993, EPA held a public meeting. The public was invited to comment on all of the

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remedial alternatives evaluated in the Feasibility Study.

On September 28,1993, EPA issued a ROD for the Woodlawn Landfill site. The primarycomponents of the selected remedy included: capping of the landfill, including the PVC sludgedisposal cells with a low-permeability cap; excavation and disposal of mercury-contaminatedsurface soil; and, extraction and on-site treatment of contaminated ground water with dischargeof treated ground water to the on-site stream. The current estimate of the present worth cost ofthe remedy is $15,649,0001. A complete description of the selected remedy may be found in the1993 ROD.

In accordance with an Administrative Order for Remedial Design and Remedial Action, DocketNo. III-95-05-DC, issued by EPA on November 25,1994, Bridgstone/Firestone began toimplement the selected remedy. During predesign investigations, additional environmental datawas collected to aid in the design of the landfill cap and the ground water pump-and-treat system.

Upon review of the ground water monitoring data, it became apparent that vinyl chlorideconcentrations were clearly decreasing at a relatively rapid rate. This phenomenon of decliningorganic contaminant concentration was not anticipated when EPA issued the 1993 ROD.Between 1995 and 1998, a series of studies have demonstrated that a combination of naturallyoccurring processes, primarily biodegradation and chemical oxidation, are effectively degradingorganic compounds (i.e., vinyl chloride) to harmless substances and stabilizing inorganiccontaminants (i.e., manganese) to a form that does not dissolve in water. This new informationfundamentally changes our understanding of the fate of hazardous substances located at the site.

Recent studies indicate that the presence of oxygen within the subsurface environment is animportant component necessary to support both the biodegradation and. the stabilizationprocesses responsible for the natural cleansing observed. There is concern that construction ofthe impermeable landfill cap included as part of the original remedy may reduce the transfer ofoxygen to the subsurface environment, thereby slowing the observed natural attenuation ofhazardous substances.

REASON FOR PROPOSED CHANGE OF CLEANUP PLAN

The predesign investigations discussed above have led to a new and significantly differentcharacterization of the site. The investigations have demonstrated that, contrary to earlierpredictions based on a ground water flow and contaminant fate and transport model developed

1 The estimated cost for cleanup hi EPA's September 28,1993 ROD was $23,800,000.The difference between the ROD estimate and the current estimate is the result of newinformation gained during the design process on the size of the waste disposal area and theengineering requirements for the cap.

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during the Remedial Investigation, the vinyl chloride plume is receding and the mass of vinylchloride in the aquifer beneath the site has sharply declined (see Figure 2). The dissolvedmanganese plume has remained stable during the past ten years and is confined within thelandfill property boundaries as a result of the biogeochemical environment within the aquiferaround the landfill. Thus, these ground water conditions have improved without the benefit of animpermeable cap constructed over the landfill to reduce infiltration of rain water through theburied wastes.

The Focused Feasibility Study Ground Water Remedy Woodlawn Landfill Site documents theresults of the natural attenuation studies recently conducted at the site and describes thebiodegradation and biogeochemical mechanisms responsible for the natural attenuation of vinylchloride and manganese in ground water at the site. The other ground water contaminants forwhich cleanup levels were established in the ROD have been detected sporadically andinfrequently2. Many of those contaminants (e.g., PAH's and pesticides) have chemical propertieswhich limit their mobility in ground water. Others are susceptible to the biodegradationprocesses which are responsible for the destruction of vinyl chloride in ground water at the site.

The presence of oxygen within the subsurface environment is required to support thebiodegradation and stabilization processes responsible for the ground water purificationobserved. The reduced permeability cap called for in the original remedy would prevent directcontact with buried waste, but may reduce the available oxygen within the "treatment zone."EPA has concluded that two feet of clean soil placed over the landfilled wastes would alsoprevent direct contact with buried wastes but would allow oxygen to continue to pass into the"treatment zone."

Description of Proposed Remedy Modifications

Original Remedy

Construction of a low permeability landfillcap with gas vents; vegetate with a wildflower and grain seed mix

Maintain cap by removing deep rooted plants

Pump and treat for ground water restoration

Modified Remedy

Construction of a permeable landfill coverwithout gas vents; vegetate with a wild flowerand grain seed mix.

Deep rooted plants/trees acceptable

Monitored Natural Attenuation for groundwater restoration

2 For further information, see Table 1-1 in the document entitled Focused FeasibilityStudy Ground Water Remedy Woodlawn Landfill Site

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EPA's new preferred remedial alternative would provide the same level of protection as theremedy EPA selected for the site in 1993, effectively reducing the concentrations ofcontaminants hi the ground water to levels which are protective of human health and theenvironment in a time frame comparable to that which could be achieved through active pumpingand treatment of the ground water. In addition, the Agency's new preferred alternative would notresult in cross-media transfer of contaminants or the generation of residual wastes, and wouldresult in a more cost effective cleanup.

Revised Cleanup Levels for Noncarcinogenic Contaminants

The human health risk assessment and ecological risk assessment were completed prior toissuance of the 1993 ROD and remain the basis for risk-based decision making at the Site. Anaddendum to the human health risk assessment has been developed and is included hi theAdministrative Record. The addendum clarifies that the cleanup levels for groundwatercontaminants with noncareinogenic adverse health effects have been revised, consistent withAgency risk assessment guidance, hi order to account for the fact these contaminants havedifferent toxicological effects and affect different organs in the body (See Figure 3). Cleanupstandards for potentially carcinogenic contaminants remain unchanged.

SUMMARY OF ALTERNATIVES

The two remedial alternatives developed and evaluated hi detail hi the Focused FeasibilityStudies as possible response actions to address the risks posed by the current and future exposureto contamination at the Woodlawn Landfill are listed below.

Common Elements: Each of the alternatives now being considered include excavation ofapproximately 15 cubic yards of mercury-contaminated surface soils from the former septicsystem drain field. Excavated soil will be sampled for the characteristic of toxicity as defined hi40 C.F.R. § 261.24. Soil which exhibits the characteristic of toxicity will be transported to aRCRA Subtitle-C hazardous waste landfill. Soil found to be contaminated with a hazardoussubstance above the cleanup standards but which does not exhibit the characteristic of toxicitywill be transported to a RCRA Subtitle-D landfill. The excavated areas will be backfilled withclean material to replace the contaminated soil that was disposed off-site. The septic systemdrain field which is currently operating will not be affected.

The contracting contaminant plume provides the basis for lifting most ground water userestrictions affecting properties near the landfill. An analysis of the current and potential futureextent of contamination concludes that the ground water use restrictions would be limited to thelandfill property and property owned by Bridgestone/Firestone (see Figure 4). The ground wateruse restriction prohibiting drinking water wells on the parcel north of the Site, owned byBridgestone/Firestone will remain until that portion of the aquifer meets ground water cleanuplevels.

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Figure 3Revised Ground Water Cleanup Standards for Contaminants with

Noncarcinogenic Adverse Health Effects3

The revised ground-water cleanup levels are such that each of the following conditions'shall be met for arsenic, cadmium, endosulfan, manganese, mercury and vanadium:

To protect renal endpoints:

[endosulfan]/! 72 + [cadmium]/! 6 + [mercury]/9.4 < 1

To protect vascular endpoints:

[endosulfan]/172 + [arsenic]/9.4 < 1

To protect central nervous system endpoints:

[endosulfan]/! 72 + [manganese]/730 < 1

Where:

[vanadium] < 220 micrograms per liter (ug/L)

[cadmium] < 5 ug/L

[arsenic] < lug/L (or background)

[mercury] < 2 ug/L

where [chemical X] is the concentration of chemical X in ug/L.

3 Details related to the presented summary can be found in correspondence fromGeraghty & Miller to EPA, dated January 12,1998, located at pages 310087-91 of theAdministrative Record.

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PROPERTY OFBRIDGESTONE/FIRESTONE, INC.

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ITB-3 ® MONITORING WELL LOCATIONAPPROXIMATE LANDFILLBOUNDARYAPPROXIMATE PROPERTYBOUNDARYROUNDWATER USEESTRICTION AREA

0 500

SCALE IN FEET

d ViMOfC!\K8)aESI!!B\MB\Il£t1SJtf'VFYS£PJi-?ffl5

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FIGURE 4GROUNDWATER USE RESTRICTIONS

WOODLAWN LANDFILL

,'iflffiffll? MARYLAND

In addition, land use restrictions would be implemented for the landfill property to ensure thatthe property is not used in a manner inconsistent with the remedy.

Alternative 1: Low Permeability Cap, Ground Water Recovery and Treatment[Current Remedy]

Capital Cost: $ 4,410,000Annual O&M Cost: $ 795,000Present Worth Cost: $ 15,649,000Time to Implement: 32 months

This alternative involves constructing a low permeability cap over the landfill. The capconfiguration has been designed and consists of a foundation layer with a passive gas ventingsystem, a 40-millimeter thick flexible membrane liner, a drainage layer, and a vegetated soilcover to be placed over the landfill, including the PVC disposal cells. Capping the landfill wouldminimize the infiltration of precipitation through the buried wastes, thereby reducing themigration of hazardous substances to underlying ground water. The barrier would also reducethe natural flow of oxygen to the subsurface environment, thereby altering the biologicaldegradation of organic contaminants currently observed. In addition, the cap would create aphysical barrier that would prevent direct contact with landfilled materials. The total area to becapped would be 20.5 acres.

A ground water extraction and treatment system would be designed and installed to capturecontaminated ground water at the Site and prevent off-site migration of contamination.Approximately eighteen extraction wells would be installed around the perimeter of the landfill.The wells would intercept ground water migrating through the Site and prevent contaminatedground water from escaping the Site boundaries. The actual number and location of extractionwells would be determined during the Remedial Design of the system.

A water treatment plant would be constructed and operated on-Site. The effluent from the watertreatment facility would meet the contaminant-specific concentrations necessary for a permitteddischarge to the stream at the southern end of the landfill property. In addition to these numericcriteria, the effluent would meet the narrative State Ambient Surface Water Quality Standardsand Federal Ambient Water Quality Criteria which prohibit discharge of treated water that istoxic to aquatic organisms.

In order to achieve compliance with the discharge requirements, the conceptual ground watertreatment system would utilize the following three-step process. The first step would entailprecipitation and flocculation/coagulation to remove manganese and other inorganiccontaminants. The filtered effluent from the precipitation unit would then enter an air strippercolumn for removal of VOCs, including vinyl chloride. The water discharged from the air

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stripper would be passed through granular activated carbon to remove semivolatile organiccompounds and other remaining contaminants. Solids from the precipitation process and spentcarbon would be collected and disposed off-site. Currently-available information indicates thatair emissions of VOCs from the air stripper would not exceed risk- or health-based emissionlimits. However, air emission controls would be implemented as necessary to protect humanhealth and to comply with federal and State regulations. The actual components of the systemwould be determined during the design phase.

Operation and maintenance activities would include, but not be limited to, maintaining theintegrity of the cap, operating the water treatment plant, maintaining the extraction wells (withperiodic cleaning of well screens), periodic ground water level and chemical measurements toconfirm that Site ground water is being captured, and routine chemical analyses of plant effluentwith quarterly bioassay tests to confirm that the discharge meets State requirements. The netpresent worth cost estimate was based on a 30-year operation period; however, operation couldcontinue beyond 30 years.

An engineered surface water runoff and erosion control system would be designed in accordancewith State Storm Water Control Regulations and installed to control surface water runoff. Thesystem would include surface grading and storm water retention basins with outfall structures, asnecessary.

The landfill cap would be vegetated in such a way as to provide a high quality wildlife habitat tothe maximum extent practicable (without endangering the liner). The surface would be plantedwith a diverse mix of grass seed. The landfill cap maintenance plan would require removal ofdeep-rooted plants to protect the liner. A chain-link fence would be constructed around theperimeter of the landfill property to minimize the potential for vandalism to the gas vents and thewater treatment plant.

Alternative 2: Soil Cover, Monitored Natural Attenuation of Ground Water

Capital Cost: $ 1,360,000Annual O&MCost: $ 186,000Total Present Worth Cost: $ 4,791,000Time to Implement: 17 months

This alternative has been developed based on EPA's recognition that natural processes occurringin the subsurface environment are effectively reducing the concentrations of organiccontaminants in ground water and, containing any further migration of inorganic contaminantswithin the property boundary. Alternative 2, supported by extensive ground water monitoring totrack progress, would enable this natural attenuation process to continue.

Rather than using ground water extraction wells to remove contaminated ground water for

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-*. *=subsequent treatment at an above-ground constructed facility, this alternative would utilize the insitu treatment processes naturally occurring at the Site to restore the ground water quality. Theground water monitoring program conducted since the 1993 ROD was issued has revealed thatthe natural system has been degrading organic contaminants to harmless compounds andcontaining manganese by chemically converting the metal to a form which does not dissolve inwater. The extent of organic ground water contamination at the Site has been significantlyreduced and the maximum detected contaminant concentrations have decreased. This suggeststhat an impermeable landfill cap constructed to reduce the rate at which contaminants leach to theunderlying ground water is not necessary to prevent off-site migration of contaminants.Therefore, Alternative 2 involves constructing a vegetated soil cover over the 20.5-acre landfillinstead of an impermeable cap (see Figure 5). The soil cover, which would be a minimum of 24inches thick, would reduce the risk of direct exposure to buried wastes and prevent off-sitemigration of surface soil by providing a physical barrier. The permeable soil cover would allowoxygen to continue to flow down into the subsurface environment. Oxygen availability isessential to support the biodegradation of vinyl chloride because the most effective naturally-occurring bacteria feeding on the organic contaminants require oxygen to "breathe."

The most important advantage of this remedy is that the water would be decontaminated while itremains underground, rather than having to pump the water out in order to be treated. Thatchange alone would eliminate the need to handle contaminated ground water, to manage airemissions and treatment plant wastes, and to discharge treated water to the nearby stream.

A long-term ground water monitoring plan would be implemented to document that the naturalattenuation mechanisms that are currently effective in attenuating contaminants at the sitecontinue; to ensure that concentrations of contaminants continue to decline and achieve cleanupstandards; and to ensure continued protection of human health and the environment. As an addedsafety measure, the ground water monitoring plan includes wells placed upgradient of potentialreceptors to ensure that any significant changes in ground water conditions are identified early.In the event that a significant potential risk of exposure was identified a plan to eliminate thatpotential exposure would be implemented. The presumptive response action would beimplementing localized ground water pumping and treatment and providing an alternate watersupply. Surface water from the Unnamed Creek will be monitored concurrent with the groundwater.

An effort would be made to return the landfill property to a beneficial use. The most likely reuseoption would be the creation of a wildlife habitat area. The areas disturbed by the soil coverconstruction activities would be revegetated with a diverse seed mix of grain and/or wildflowers.Other reuse options (i.e., a nature center, golf course, etc.) would be available provided that theintegrity of the remedy was maintained and State and local regulations were met. A security planwould be developed to minimize vehicular traffic and the potential for unauthorized dumping onthe property.

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LEGENDITB-3 A MONITORING WELL LOCATION (EXCLUDES WELLS

REMOVED PRIOR TO 1999)SW-2 • SURFACE WATER SAMPLE LOCATION•—— —— APPROXIMATE LANDFILL BOUNDARY

—— APPROXIMATE PROPERTY BOUNDARY"j APPROXIMATE LIMITS OF SOIL COVER

MW-109BVMW-109A

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GERAGHTY&MILLER

FIGURE 5PREFERRED REMEDY

WOODLAWN LANDFILLCECIL COUNTY. MARYLAND

——AH.n2601——

COMPARATIVE EVALUATION OF ALTERNATIVES

EPA's preferred alternative for addressing contaminated ground water and buried wastes at theWoodlawn Landfill is Alternative 2 (Soil Cover, Monitored Natural Attenuation). Based oncurrent information, this alternative appears to provide the best balance of trade-offs among thealternatives with respect to the nine criteria that EPA uses to evaluate the alternatives. The ninecriteria are set forth in the National Oil and Hazardous Substances Pollution Contingency Plan(NCP), 40 C.F.R. Section 300.430(e)(9)(iii) and are summarized in Table 1.

In selecting its preferred alternative, EPA evaluated each proposed remedy against the criteriaspecified in the NCP. The alternative must first satisfy the threshold criteria. Next, the primarybalancing criteria are used to weigh the tradeoffs, or advantages and disadvantages, of thealternatives. Finally, after public comments have been received, the modifying criteria will beconsidered.

Based on new information or public comments, EPA, in consultation with the MDE, may latermodify the preferred alternative or select another alternative presented in this Proposed Plan.The public, therefore, is encouraged to review and comment on each of the alternatives identifiedin this Proposed Plan. The Administrative Record, including the RI/FS, should be consulted formore information on these alternatives.

The following summary profiles the performance of the preferred alternative hi terms of the ninecriteria, noting how it compares to the other alternative under consideration.

1. Overall Protection of Human Health and the Environment

A primary requirement of CERCLA is that the selected remedial alternative be protective ofhuman health and the environment. A remedy is protective if it reduces current and potentialrisks to acceptable levels under the established risk range posed by each exposure pathway at theSite.

Alternatives 1 and 2 are each protective of human health and the environment. Each of theseAlternatives reduce the potential for exposure to and migration of Site contaminants, but eachdoes it hi a different way. Significant advantages are realized by Alternative 2 because thecontaminated ground water is not brought to the surface for treatment. EPA remains confidentthat the pump and treat system selected in the original ROD (i.e., Alternative 1) could be safelyimplemented with a minimal transfer of contaminants to air and surface water. Nevertheless, thenatural attenuation processes (Alternative 2) provide for water treatment at depth, thuseliminating issues related to handling contaminated ground water, managing air emissions andtreatment plant residuals, and maintaining a surface water discharge to the Unnamed Creekwhich is safe for aquatic life. The performance goal, treating ground water to the point that thewater will achieve drinking water quality outside the landfill boundary, remains unchanged fromthe objective described in the ROD.

11

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Under each of the alternatives the buried wastes would remain in place, but the threat posed topeople or animals from contact with the wastes and the potential for off-site migration is reducedby placing a cover over the landfill. Alternative 2 would utilize a soil cover over the landfill;Alternative 1 would add a 40-mil thick polyethylene membrane, a gas venting system and asurface water drainage layer. Both alternatives include long-term monitoring to ensure that theremedy continues to be effective.

2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)

Any cleanup alternative considered by EPA must comply with all applicable or relevant andappropriate federal and state environmental requirements. Applicable requirements are thosesubstantive environmental standards, requirements, criteria, or limitations promulgated underfederal or state law that are legally applicable to the Remedial Action to be implemented at thesite. Relevant and appropriate requirements, while not being directly applicable, addressproblems or situations sufficiently similar to those encountered at the site that their use is well-suited to the particular site. The remedial alternatives evaluated in this Proposed Plan wouldcomply with ARARs, as appropriate.

Chemical-Specific ARARs

Soil: There are currently no ARARs establishing acceptable concentrations for contaminants insoil at the Site. However, as noted previously, the Remedial Investigation determined that theconcentration of mercury in the surface soil in the immediate vicinity of the former septicsystem drain field does present an unacceptable risk to ecological receptors. Soil containinggreater than 1 mg/kg mercury will be excavated from the drain field under both alternatives.

Ground Water: The Maximum Contaminant Levels (MCLs) and non-zero MaximumContaminant Level Goals (MCLGs) for public drinking water supplies established under the SafeDrinking Water Act are considered to be relevant and appropriate standards for ground watercleanup under the Superfund program. In the context of a landfill, the extent of the landfill isconsidered a waste management area. The goal is to create an "area of attainment" justdowngradient of the waste management area. The area of attainment is the zone where groundwater cleanup standards will be met. At the Woodlawn Landfill, the concentrations ofcontaminants within the area of attainment are significantly lower than they were when theoriginal ROD was issued. Nevertheless, several contaminants in ground water within the area ofattainment exceed MCLs and/or site-specific cleanup levels. Under Alternative 1 ground waterwould be extracted and treated. The ground water recovery wells would operate to contain thecontaminated ground water at the Site boundary, preventing off-site migration of contamination.Alternative 2 utilizes natural processes to treat the ground water and prevent contaminants frommigrating off-site. Each alternative would ultimately comply with MCLs (40 C.F.R. §§ 141.11-.12,141.61-.62) and non-zero MCLGs (40 C.F.R. §§ 141.50-.51) for inorganic and organicchemicals and with State regulations for the protection of drinking water (MarylandEnvironmental Article, Title 9, Subtitle 2 and Subtitle 4).

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Health Effects Assessments and U.S. EPA Health Advisories were also considered inestablishing the site-specific ground water cleanup levels for the Site. Alternatives 1 and 2would each achieve the performance standards for the Site.

Action-Specific ARARs

Water Wells: The abandonment or construction, operation and maintenance of any ground waterextraction or monitoring well under both Alternatives would be completed in conformance withCOMAR 26.04.04.

Discharge of Treated Ground -water: The ground water extraction and treatment component ofAlternative 1 involves discharging treated water from the ground water treatment system into theUnnamed Creek which crosses the southern end of the Site. Since the State-designated uses ofthe stream include public water supply and protection of aquatic life, the discharge of treatedground water in Alternative 1 would comply with the MCLs and non-zero MCLGs listed above,State water quality standards (COMAR 26.08.02.03), and those federal ambient water qualitycriteria established pursuant to Section 304 of the Clean Water Act (33 U.S.C. § 1251) whichapply to protection of aquatic life. Alternative 1 would also comply with State and federalrequirements pertaining to point source discharges to surface water, including dischargelimitations (COMARs 26.08.03.01 and .07), standards for best management practices (40 C.F.R.Part 125, Subpart K) and test procedures (40 C.F.R. Part 136).

Landfill Closure: Alternative 1 includes an engineered closure cap, which is consistent with theState's landfill closure cap requirements (COMAR 26.04.07.21). Alternative 2 provides analternative closure strategy, a vegetative cover. Although a vegetative cover is not consistentwith the State's closure cap requirements, the State may grant a variance (COMAR 26.04.07.26)to the requirements if the proposed alternative protects public health and the environment andcontrols air, water and land contamination to at least the same extent as an engineered closurecap. EPA and MDE have determined that a vegetative cover, in conjunction with monitorednatural attenuation, are now effectively protective of public health and the environment, andcontrol air, water and land contamination to at least the same extent as meeting the State'slandfill closure cap requirements. EPA and MDE based these determinations, in part, on fieldinvestigations, engineering analysis included in the Administrative Record and over 18 years ofground water data collected at the site and evaluated to determine the effectiveness of avegetative cover remedy.

Identification of Hazardous Wastes: Excavated soils hi both Alternatives and water treatmentplant residuals in Alternative 1 would be evaluated in accordance with the federal and statehazardous waste identification requirements (40 C.F.R. §§ 261.24 (toxicity); COMARs10.51.02.10-.12 and COMARs 26.13.02.11-.13 (ignitability, corrosiviry, reactivity)). On-sitehandling of any materials found to exhibit a characteristic of a hazardous waste would complywith the substantive portions of state regulations that pertain to generators of hazardous waste(COMARs 10.51.04.01-.04 and COMARs 26.13.03.01, .03-.06 and .08).

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Hazardous Waste Stored or Stockpiled: Each Alternative includes excavation and handling ofmercury-contaminated soil from the drain field. The excavated soil may be temporarily stored orstockpiled prior to its off-site transport. Any on-site storage of characteristic hazardous wastewould comply with the substantive portions of federal and state requirements regulatingcontainers (40 C.F.R. § 264.171-.178; COMAR26.13.05.09), tanks (40 C.F.R. §§ 264.191-.196,.198, .199; COMAR26.13.05.10), and waste piles (40 C.F.R. §§ 264.251-.256, .259; COMAR26.13.05.12), depending on the type of waste present and the manner in which it is stockpiled.

Air Emissions: The treatment of ground water in Alternative 1 would result hi VOC emissionsfrom an air stripper to ambient air. Air emissions would be monitored to ensure that they meetState and federal requirements for air emissions from air strippers. These requirements includeState regulations pertaining to Toxic Air Pollutants, including the authorized State program thatestablishes National Emission Standards for Hazardous Air Pollutants (Code of MarylandAnnotated Regulations (COMAR) 26.11.15), federal air emission standards for process vents (40C.F.R. Part 264, Subpart AA), and State requirements pertaining to emissions of VOCs(COMAR 26.11.06.06). The EPA guidance document entitled Control of Air Emissions fromSuperfimdAir Strippers at Superfitnd Ground-water Sites would be considered in assessing theneed for controlling air emissions from the air stripper.

Sediment and Stormwater: A stormwater and sediment management plan consistent withsubstantive portions of COMARs 26.17.01 (erosion and sediment control) and COMAR26.17.02 (stormwater management) must be developed and approved by EPA beforeconstruction of either Alternative can begin.

Worker Safety: Worker safety requirements set forth in 29 C.F.R. § 1910, including those thatrelate to the handling of hazardous substances, are applicable to each Alternative requiringphysical contact with soil, sediment, ground water or residual sludge from ground watertreatment.

Location-Specific ARARs

Protection of Wetlands: Provisions for carrying out Executive Order 11990 (Protection ofWetlands), set forth in 40 C.F.R. Part 6, Appendix A apply to this Site. Remedial alternativesmust avoid adverse effects, minimize potential harm, and restore and preserve natural andbeneficial values of wetlands. Alternatives 1 and 2 would both be implemented so that noadverse impact on wetlands occurs.

In summary, each Alternative would meet its respective applicable or relevant and appropriaterequirements of federal and state environmental laws.

3. Long-term Effectiveness and Permanence

Alternatives 1 and 2 would reduce risks to acceptable levels for the ground water pathway by

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either capturing the contaminated water before it migrates off-site (Alternative 1) or maintainingconditions necessary to support the continued natural cleansing process documented to beoccurring at the Site (Alternative 2).

Alternative 1 provides good long-term effectiveness by constructing a low-permeability cap toreduce the leaching of hazardous substances to the underlying aquifer and by utilizing groundwater extraction wells to prevent contaminated ground water from migrating off-site. Theground water extraction wells would function effectively for as long as the wells are maintained.At some point, the rate of contaminant migration from the landfill to the ground water would besmall enough that ground water performance standards would be achieved. The pump and treatsystem would be maintained until the concentration of contaminants in ground water met theperformance standards.

The fraction of contaminants extracted from the ground water would be permanently removedfrom the aquifer which underlies the Site. An above-ground treatment system would employ aseries of treatment processes to separate the contaminants from the extracted water prior todischarging clean water to the Unnamed Creek.

Alternative 2 provides very good long-term effectiveness through the continued natural treatmentprocesses documented to be occurring at the Site. The most significant treatment processesoccurring in the natural system require the presence of oxygen. Recent studies have confirmedthat "oxygen-breathing" bacteria are feeding on organic compounds (i.e., vinyl chloride) and inthe process transforming them into harmless substances. Once organic contaminants aredestroyed through biological activity, the chemical degradation is permanent. This same oxygen-rich environment also creates the conditions necessary to convert manganese and iron dissolvedin ground water to a solid state, thereby preventing them from migrating from the landfillproperty. The landfill soil cover included in Alternative 2 would allow oxygen to flow into thesubsurface environment. Ground water monitoring performed during the last several yearsdocuments that the extent of contamination continues to decline and the amount of hazardousorganic substances in the aquifer has been reduced. If the current environmental conditions aremaintained these trends are expected to continue. Alternative 2 has greater long-termeffectiveness than Alternative 1 because engineered systems are not utilized to containcontaminants; therefore, long-term system failure is not a concern. Each successive year thelandfill will become more stable.

4. Reduction of Toxicity. Mobility, or Volume through Treatment

Section 121(b) of CERCLA, 42 U.S.C. Section 9621(b), establishes a preference for RemedialActions which include treatment that permanently and significantly reduces the toxicity,mobility, or volume of contaminants.

To the extent that the natural attenuation processes observed to be occurring are recognized as insitu "treatment," Alternative 2 compares favorably to the pump and treat system (Alternative 1)

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when considering reduction of toxicity, mobility and volume through treatment. More of themass of contaminants will be destroyed by the chemical and biological oxidation-reductionreactions inherent to Alternative 2 than by the air stripping and carbon adsorption mass transfertechnologies included in the original remedy.

5. Short-Terns Effectiveness

Each Alternative includes excavation and off-site transport of approximately 15 cubic yard ofmercury-contaminated surface soil from the former septic system drain field. All short-termrisks to site workers would be minimized using standard safety measures.

Alternative 1 would include construction of a low-permeability landfill cap, installation of aground water recovery well network and construction of a water treatment facility. The finaldesign of the low-permeability landfill cap was completed in July 1998. The water treatmentplant design was suspended at the 30% design stage. The time necessary to implementAlternative 1 is estimated to be 32 months. Alternative 1 would achieve good short-termeffectiveness as the there would be little potential for significant exposure to contaminants duringinstallation of recovery wells or construction of the on-site water treatment plant. Potential forsignificant exposure to Site-related contaminants during the operation of the pump and treatsystem would be minimal. It is estimated that the water treatment plant will operate for 30 years.

Alternative 2 would include monitored natural attenuation of ground water contaminants andconstruction of a landfill soil cover. Revisions to the existing landfill cap design to reflect thesoil cover profile would take less than 3 months. Natural attenuation processes and the groundwater monitoring program are underway. The time necessary to construct the soil cover isestimated to be 17 months. The monitored natural attenuation process offers better short-termeffectiveness than the pump and treatment remedy because the contaminated ground water willnot be brought to the surface. Therefore, the potential for exposure to contaminants is even morelimited than hi Alternative 1, and the tune to implement the remedy will be shorter.

6. Implementability

This evaluation criterion addresses the difficulties and unknowns associated with implementingthe cleanup technologies associated with each Alternative, including the ability and timenecessary to obtain required permits and approvals, the availability of services and materials, andthe reliability and effectiveness of monitoring.

Ground water extraction technology included hi Alternative 1 is proven and can be readilyimplemented. Ground water modeling would be conducted to select the most efficient locationsfor extraction well placement. Materials and services are readily available.

The high iron and manganese concentrations in the extracted ground water could complicate thepump and treatment process because they could potentially foul the well screens, clarifier, filter,

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and air stripper. The treatment plant required to treat the array of contaminants in the groundwater would require several coupled water treatment technologies making the overall processtechnically complex. Nevertheless, vendors capable of constructing and operating such a systemare readily available.

The installation of either the low-permeability landfill cap (Alternative 1) or the soil cover(Alternative 2) would involve well-known construction methods. Necessary services andmaterials are readily available.

The area of mercury-contaminated soil has already been delineated and its excavation will be aroutine process in either Alternative. Additional waste characterization will determine whetherpre-treatment requirements are necessary, and the appropriate type(s) of landfill(s) for disposal.Appropriate landfill facilities with capacity for the contaminated soil are available within severalhundred miles from the Site.

Worker exposure and protective equipment requirements for construction activities can bereadily achieved for each of the Alternatives, and appropriate measures to control dust will beemployed.

7. Cost

Evaluating the costs of any remedy involves calculating the direct and indirect capital costs andthe annual operation and maintenance (O&M) costs, and then converting these calculations to apresent worth basis. The estimated capital, annual O&M and total present worth cost for each ofthe Alternatives has been calculated for comparative purposes and is presented in Table 2.

Table 2Summary of Estimated Costs

Alternative 1

Alternative 2

Capital Cost

$4,410,000

$1,360,000

Annual O&M Cost

$795,000

$186,000

Present Worth

$15,649,000

$4,791,000

Direct capital costs include costs of construction, equipment, building and services, and wastedisposal. Indirect capital costs include engineering expenses, start-up and shutdown, andcontingency allowances. Annual O&M costs include labor and material; chemicals, energy, andfuel; administrative costs and purchased services; monitoring costs; cost for periodic Site review(every five years); and insurance, taxes, and license costs. For cost estimation purposes, a periodof 30 years has been used for O&M. In reality, maintenance of a site with waste left hi place

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would be expected to continue beyond this period. Similarly, the actual duration of operation forthe ground water extraction and treatment system would depend on a demonstration that Site-related contaminants no longer migrated off-site after plant shut-down. The actual cost for eachAlternative is expected to be in a range from 50 percent higher than the costs estimated to 30percent lower than the costs estimated. The evaluation was based on the cost estimates includedin the documents entitled Focused Feasibility Study Ground Water Remedy and FocusedFeasibility Study Final Cover System,

8. State Acceptance

The State of Maryland supports the preferred alternative (Alternative 2) but reserves its finalconcurrence until community comments are evaluated.

9. Community Acceptance

Community acceptance of the preferred alternative will be evaluated after the public commentperiod ends and will be discussed in the Responsiveness Summary of the Amended Record ofDecision for the Site.

PREFERRED REMEDIAL ALTERNATIVE

Based on the comparison of the evaluation criteria summarized previously for each of theAlternatives in this Proposed Plan, EPA's preferred Alternative is Alternative 2: Soil Cover,Monitored Natural Attenuation. The preferred Alternative meets the threshold criteria of overallprotection to human health and the environment and compliance with ARARs. In consideringthe balancing criteria, EPA believes that this Alternative can be readily implemented, achieveslong-term effectiveness and permanence at a reasonable cost, minimizes the short-term impacts,and effectively reduces the toxicity, mobility and volume of Site contaminants through naturaltreatment processes.

The cumulative estimated cost of implementing EPA's preferred Alternative is:

Capital Cost: $1,360,000Annual O&MCost: $ 186,000Total Present Worth Cost: $4,791,000

THE ROLE OF COMMUNITY IN THE SELECTION PROCESS

This Proposed Plan is being distributed to solicit public comment on the appropriate cleanupaction for the Site. EPA relies on public input so that the remedy selected for each Superfundsite addresses the concerns of the local community and other interested parties. EPA is providing

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a 30-day public comment period beginning on March 24,1999 and ending on April 26,1999, toencourage public participation in the selection process. EPA will conduct a public meetingduring the comment period in order to present the Proposed Plan and supporting information,answer questions, and accept both oral and written comments from the public. The publicmeeting will be held on April 15,1999, at 7:00 p.m at the Elkton Middle School, 615 NorthStreet, Elkton, Maryland.

Any comments sent must be post-marked by April 26,1999 to be considered in theResponsiveness Summary section of the Amended Record of Decision, which will documentEPA's final remedy selection. To obtain additional information relating to this Proposed Plan,please contact either of the following EPA representatives:

Vance Evans (3HS43) Eric Newman (3HS23)Community Involvement Facilitator Remedial Project ManagerU.S. EPA - Region III U.S. EPA - Region III1650 Arch Street 1650 Arch StreetPhiladelphia, PA 19103 Philadelphia, PA 19103Phone: 215-814-5526 Phone: 215-814-3237

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Table 1

Below is a description of each of the nine criteria set forth in the NCP, 40 C.F.R.§ 300.430(e)(9), used to evaluate each of the remedial alternatives summarized in this plan.These nine criteria can be categorized into three groups: threshold criteria, primary balancingcriteria, and modifying criteria.

Threshold Criteria:

1. Overall Protection of Human Health and the Environment addresses whether a remedyprovides adequate protection and describes how risks are eliminated, reduced, orcontrolled through treatment, engineering controls, or institutional controls.

2. Compliance with Applicable or Relevant and Appropriate Requirements (ARARs)addresses whether a remedy will meet all of the applicable, or relevant and appropriaterequirements of environmental statutes and/or whether there are grounds for invoking awaiver of these requirements. This criterion also addresses whether or not the remedycomplies with advisories, criteria and/or guidance that may be relevant.

Primary Balancing Criteria:

3. Long-term Effectiveness refers to the ability of a remedy to maintain reliable protection ofhuman health and the environment over time once cleanup goals are achieved.

4. Reduction ofToxicity, Mobility, or Volume through Treatment addresses the degree towhich alternatives will reduce the toxicity, mobility, or volume of the contaminantscausing site risks.

5. Short-term Effectiveness addresses the period of time needed to achieve protection andany adverse impacts on human health and environment that may be posed during theconstruction and implementation period until cleanup goals are achieved.

6. Implementability addresses the technical and administrative feasibility of a remedy,including the availability of materials and services needed to implement a particularoption.

7. Cost includes estimated capital cost and operation and maintenance costs, converted to apresent worth cost basis.

Modifying Criteria:

8. State Acceptance indicates whether, based on its review of backup documents and theProposed Plan, the State concurs with, opposes, or has no comment on the preferredalternative.

9. Community Acceptance will be assessed in the Record of Decision following a review ofpublic comments received on the Proposed Plan and supporting documents included inthe Administrative Record.

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Administrative Order on Consent: A legal agreement signed between EPA and the potentiallyresponsible parties (PRPs) whereby the PRPs agree to perform or pay for site cleanup activities.The agreement describes actions to be taken at a site.

Administrative Record File: An official compilation of documents that form the basis ofresponse actions selected for a Superfund site.

Air Stripping: The process of removing or "stripping" volatile organic compounds fromcontaminated ground water or surface water by forcing an air-stream through the water, causingthe compounds to evaporate.

Carcinogen: A substance that may cause cancer.

Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA): AFederal law (commonly known as "Superfund") passed in 1980 and modified hi 1986 by theSuperfund Amendments and Reauthorization Act (SARA). The law gives EPA the authority toinvestigate sites where there is a suspected threat to public health or the environment caused bythe release or potential release of hazardous substances. The law also allows EPA to take legalaction to force parties responsible for site contamination to clean up the site or pay back theFederal government for the cost of the cleanup.

Ecological Receptors: Any plant, animal or natural resource that could be exposed to and/ordamaged by hazardous substances.

Flocculation/Coagulation: Process by which clumps of solids in water or sewage aggregatethrough biological or chemical action so they can be separated from water to settle outimpurities.

Ground Water: Water found underground in gaps between soil, sand and gravel particles, andwhich often is a major source of drinking water.

Maximum Contaminant Level (MCL): Levels of substances allowable in public drinkingwater supplies as regulated by the Safe Drinking Water Act.

National Priorities List (NPL): EPA's list of the nation's most serious uncontrolled orabandoned hazardous waste sites that are eligible to receive Federal money for response underCERCLA.

Natural Attenuation: The combination of natural processes by which a compound is reduced inconcentration over tune, through absorption, adsorption, chemical and/or biological degradation,dilution, and/or chemical transformation. At the Woodlawn site, studies have confirmed thatbiological degradation is the most important factor with the attenuation of the volatile organic

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compounds.

Precipitation: The act of converting dissolved substances to insoluble solid substances whichwill settle out or be removed from a liquid.

Polynuclear Aromatic Hydrocarbons (PAHs): A group of compounds derived from petroleumwhich do not readily volatilize at standard temperature and pressure.

Potentially Responsible Party (PRP): Any mdividual(s) or company(ies) that is potentiallyresponsible for contributing to the contamination problems at a Superfund site.

Renal: Relating to, or in the region of the kidneys.

RCRA Subtitle-C Hazardous Waste Landfill: A land disposal facility permitted to handlehazardous substances and wastes.

RCRA Subtitle-D Landfill: A land disposal facility permitted to handle only solid or non-hazardous waste material.

Semivolatile Organic Compounds: Organic compounds that volatilize slowly at standardtemperature (20 degrees C and 1 atm pressure).

Sludge: A waste material that has a moist, mud-like, consistency.

Superfund: The program operated under the legislative authority of CERCLA and SARA toupdate and improve environmental laws. The program has the authority to respond directly toreleases or threatened releases of hazardous substances that may endanger public health, welfare,and/or the environment. The Superfund is a trust fund that can be used to finance clean-upactions at hazardous waste sites. Money for the Superfund comes from a tax on chemical andpetroleum industries.

Volatile Organic Compound (VOC): Organic (carbon-containing) compounds that readilyevaporate (volatilize) under atmospheric conditions. These chemicals are commonly used assolvents, degreasers, and dry cleaning chemicals.

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