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Brief Overview of: Lowry Landfill Superfund Site

Denver, Colorado, USAFrank LewisFrank LewisFrank LewisFrank Lewis

International Seminar on Solid Waste Management in Metropolitan RegionsInternational Seminar on Solid Waste Management in Metropolitan RegionsInternational Seminar on Solid Waste Management in Metropolitan RegionsInternational Seminar on Solid Waste Management in Metropolitan RegionsSSSSããããoooo Paulo, Paulo, Paulo, Paulo, BrasilBrasilBrasilBrasil

29 September 2005 29 September 2005 29 September 2005 29 September 2005

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LowryLandfill

Site

LowryLandfill

SiteAsbestos

Disposal Pit

G un

Club

Roa

d

East Quincy Avenue

East Hampden Avenue

Unn

eam

e d C

re k

Tire Shreds Monofill

Limit of Refuse

WMCMaintenanceFacility

Section 6

Section 3

Not to Scale

Former Tire PileArea

Landfill Mass

North BoundaryBarrier Wall

UnnamedCreek

Section 31Landfill Site

Former WastePits

Command Post

Water TreatmentPlant

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The Problem

✦ “Codisposal” of 138 million gallons of liquid industrial waste andsolid municipal waste dumped into 75 unlined trenches or wastepits with refuse, tires, and soils to absorb the liquids– Asbestos, sewage sludges, metal plating wastes, radioactive and

non-radioactive medical wastes, petroleum derived products,pesticides, industrial solvents, sewage sludge, paints, tires, animalcarcasses

– 8 million tires stockpiled✦ Contaminated liquids seeped out of waste pits and mixed with

surrounding soils, surface, water, and groundwater

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Early History

✦ 1940-62 Air Force Lowry

Bombing Range✦ 1966 -1980 Co-disposal of liquid,

solid and industrialwaste

✦ After 1980 Only municipal waste

disposal

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Pre-Remedial Investigation Activities

✦ 1982 - Preliminary Assessment and Site Inspectionconducted

✦ 1984 - Site placed on the National Priorities List✦ 1985 - North Boundary Barrier Wall and Water

Treatment Plant constructed (Interim RemedialMeasures)

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Phase I Remedial Investigation✦ 1985 to 1986 - Phase I Remedial Investigation (RI)

– Borings– Geophysics– Soil vapors and air monitoring– Sampled ground and surface-water– Soils– Sediments– Landfill solids– Landfill gas– Waste pit locations, etc…

✦ Phase I Report issued September 1986

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Remedial Investigation Activities

✦ 1985 -1989– Fund-lead investigations– Potential Responsible Party searches– Initial waste-in list developed

✦ 1987– Determination of public health threat due to:

• Groundwater contamination• Volatile organic compounds (VOCs) released from the soil

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Phase II Remedial Investigation

✦ 1987-1989 - EPA conducted Phase II RI including:– Borings– Well points– Deep and shallow ground-water wells– Soil and landfill solids sampling– Water and liquid level monitoring– Refuse leachate wells– Waste pit liquids– Limited air monitoring– Preliminary Endangerment Assessment, identification of

alternatives, operable units, overall work plan,database

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Interim Removal Measures

✦ Groundwater barrier wall and water treatment facilityoperating since 1985 to address the northwardmigration of groundwater

✦ Surface Water Removal Action built within unnamedcreek to separate contaminated groundwater fromsurface water drainage

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Key Milestones

✦ 1989-1992 - City of Denver tire shredding operation– Shredded 8 million stockpiled tires– Stored in a monofill onsite

✦ 1989 - Drum Removal Action Phase I:– Removed and stabilized liquids from damaged drums on site– Constructed temporary lined storage pads to manage liquids

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Key Milestones

✦ 1990 - Drum Removal Action Phase II: EPA and the Cityof Denver– Bulked and treated less contaminated waste at the WTP– Repackaged old drums– Decontaminated and disposed of empty drums– Decommissioned the temporary drum storage pad

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✦ 1988 - 1993 - Operable Units Studies– Site divided into six Operable Units due to the size and

complexity of the site– Objectives developed for all Operable Units– Remedy priorities set for the most critical areas– Administrative Orders on Consent negotiated with groups of

PRPs to perform studies and remedies on the Operable Unitswith EPA and State of Colorado oversight

Key Milestones (cont.)Key Milestones (cont.)

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Operable Unit Studies – ActionsPerformed by EPA and State

✦ Perform risk assessment✦ Develop/maintain community involvement program✦ Development of Remedial Action Objectives✦ Formulation of Record of Decision

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Operable Unit Studies – ActionsPerformed by PRPs

✦ Separate activities conducted for each Operable Unit– Initial evaluation of existing field data– Perform additional site characterization studies– Develop reports nature and extent of contamination– Perform treatability studies– Evaluate Applicable or Relevant and Appropriate

Requirements (ARARs)– Develop feasibility studies/remedial costs

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Baseline Risk Assessments✦ 1992-1993 Risk assessments preformed

– Provide analysis of conditions– Basis for action– Determine levels of contamination– Provide basis for comparison of potential health impacts

Data Collection &Evaluation

Data Collection &Evaluation

ExposureAssessmentExposure

AssessmentToxicity

AssessmentToxicity

Assessment

RiskCharacterization

RiskCharacterization

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Record of Decision

✦ 1994 - Record of Decision– The selected sitewide remedy was an integrated remedy

incorporating interim remedial measures and remedies forthe Operable Units and all contaminated media.• Groundwater and landfill gas are addressed by containment,

collection, and treatment• Landfill solids and soils and addressed by containment• Contaminated seepage and surface water addressed through

drainage and underground collection• Former tire pile area waste pits and principal threat wastes

addressed through excavation and treatment

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Sitewide Remedy

✦ North Boundary Barrier Wall System✦ Landfill Gas Collection and Treatment System✦ Wetlands Mitigation✦ East/South/West Ground-water Bentonite Slurry

Wall✦ North Toe Groundwater Extraction System✦ On-site Water Treatment Plant

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Sitewide Remedy

✦ Institutional Controls including site restrictions,fences, signs, deed restrictions, zoning controls

✦ Performance and Compliance Monitoring✦ Five-Year Review✦ Continuation of the Interim Measures

LowryLandfillSitewideRemedy

LowryLandfillSitewideRemedy

ClosedLandfill Area

North BoundaryGround-Water

Barrier WallOld Ground-WaterTreatment Plant and

Landfill Gas Flare

North ToeGround-Water

ExtractionSystem

E/S/WBentoniteSlurryWall

E/S/WBentoniteSlurryWall

E/S/W BentoniteSlurry Wall

WetlandsMitigation

Area

Surface WaterRemoval Action

CollectionSystem

Former TirePile Area

Waste Pits

North FaceLandfill Cover

Lowry LandfillSitewide Remedy

Gas Extraction Wells

Legend:Green = CompleteRed = Incomplete

Ground-WaterFlow Direction

WMCMaintenanceFacility

E A S T Q U I N C Y A V E N U E

EAS TH AM P D EN

AV EN U E

Gate

Not to Scale

CommandPost

N

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Technical Challenges

✦ Hidden complexities of hydrogeology– Sand channels/heterogeneities– Complex subsurface conditions difficult to identify and monitor

migration pathways– Evolving site understanding

✦ North Boundary Barrier Wall– Because of residual contamination at time of construction, difficult

to evaluate its effectiveness✦ Chemical complexity and complex mixtures of wastes

– Treatability issues

Remedial ActionConceptual Site Model

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Technical Challenges✦ Multiple types of waste disposal in northern portion

– Tank bottoms, sludge disposal✦ Subsidence of landfill

– Challenge to maintain cover✦ Unlined Landfill

– Highly dependant on groundwater monitoring✦ Physical constraints

– East - two high pressure gas lines– West - high tension power lines– South – other utilities– All around - limited space between the barrier wall and adjacent

facilities

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Community Concerns of Area Residents

✦ Containment Concerns✦ Contaminant migration/ drinking well concerns✦ Potential for vertical contamination✦ Reliability of the Onsite Water Treatment Plant✦ Maintenance of the Landfill Cover✦ Development/Land Use Concerns✦ Secrecy of the Lowry Trust✦ Political concerns

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Next Steps

✦ Top portion of closed landfill to be re-opened for C&Dwaste.– Settlement created depression on top of landfill– Increase final slope from 1% to 5%– Provide revenue to partially offset costs of remediation.– Private company operating at a profit.

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Total Approximate Costs

✦ $40 Million total spent to 1994.✦ $134 Million since 1994 and projected into the future.

– Treatment plant operation– Groundwater monitoring (> 6 km perimeter, multiple depths)– Data base management– Landfill cap maintenance– Erosion control– Fence repair– Reporting