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Case Studies fromDOE Closure Sites:

Emphasis on Reduction of Risk andRequirements for Long Term

Monitoring in Site Closure Design

Carol A. Eddy-Dilek and Brian B. Looney

Savanna River Technology Center

April 20, 2004

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Office of Closure Support (EM-23)

qTechnical assistance from nationallyrecognized experts

q Focus is support to site with acceleratedclosure schedules

qRocky Flats and Ohio (Ashtabula,Columbus, Mound, Fernald) in 2006

q Parts of Oak Ridge Reservation in 2008q Sites are currently developing

Stewardship Plans

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Intelligent Closure Design

qDesign of Remedial and Closuresystems can significantly impact longterm monitoring requirements

q Low-energy hydraulic controls can beused to contain and focus residualcontamination and optimize monitoringrequirements

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Ashtabula Closure Project (ACP)

qRMI Extrusion Plant operated for DOEqRMI processed uranium between 1962

and 1968q Primary function was extrusion of

metallic uraniumq Extensive Contamination of Surface

Soilsq Localized U and solvent contamination

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ACP Regulatory framework

q Cleanup of radioactive contamination (TCE, Tc-99) isbeing conducted under Decommissioning Plan

§ DP initially approved by NRC

§ Now under regulatory authority of Ohio Department ofHealth (ODH)

q TCE contamination

§ Waste Management Unit (WMU)

§ Estimated 1.3 acre groundwater plume

§ Ohio Environmental Protection Agency (OEPA) regulatoryauthority

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Current Clean-up Levels

Total Uranium 30 pCi/g

Tc-99 65 pCi/g

TCE 5 ug/L

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Hydrogeology

qVery low permeability glacial sedimentsqUpper till has thin sand and silt lenses

in the predominately clayey materialqResidual contaminants present in clayey

material

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Closure Strategy

q Excavate source termqResidual contamination in groundwater

expected to exceed regulatory levelsq Install gravity induced pumping system

to pull back contaminated groundwaterfor treatment

qAmendments could be added to highpermeability backfilled material

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Map view of Possible Closure System

cree

k

Pond

s (p

oten

tial

mon

itorin

g or

com

plia

nce

poin

t)

GeoDrain

excavated source and line(s)backfill w/ coarse fill or treatment bed

hill

horizontal wells or drains if needed

treatment bed or system as needed

amendments if neededto remaining soil &

groundwater

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excavation

initial water level

constant operatingwater level-- free

draining or controlledmanually

Treatment Options

in situ usingamendments in

backfillor

ex situ using waterfrom drain orpumped well

Possible Configuration of Closure System

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Advantages of Proposed Design

qHydraulic control of residual plumeqCollection of contaminated groundwater

focused to one collection pointqAmendments could be used to further

stabilize contaminationqHigh permeability fills would improve

gradients

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Monitoring Design

q Initially monitor groundwater toestablish contaminant trends

qGroundwater at discharge point couldbe collected/monitored/treated

qMonitoring options include§ Periodic analysis of water samples§ Sensor at outfall location to measure

trigger levels§ Sorbent/integrated sampling system for

periodic analysis

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East Tennessee Technology Park

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East Tennessee Technology Park

qTwo thousand acres potentiallyimpacted by site activities

q Zone 1: Area outside operationalfences where most disposal activitiesoccurred

qCOC’s include VOC’s, heavy metals,radionuclides, PCB’s

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Zone Map ofthe EastTennesseeTechnologyPark

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Graded Approach

q Site developed graded approach for sitecharacterization, remediation, andclosure

q Four classes of soil unitsqDeveloped criteria for classificationqDeveloped strategy for characterizationqBlair Quarry chosen as pilot area for

approach

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Soil Unit Classification

qClass 1 Soil Unit§ is, or was, impacted (potentially influenced

by contamination)§ the SU has moderate to high potential for

COC concentrations to exceed RLs; and§ insufficient evidence for no-action

qClass 2 Soil Unit.§ SU is, or was, impacted;§ there is low to moderate potential for COC

concentrations to exceed RLs; and§ insufficient evidence for no-action decision.

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Soil Unit Classification

qClass 3 Soil Unit§ the unit is, or was, impacted§ there is no or very low potential for COC

concentrations to exceed RLs; and§ there is insufficient for no-action decision.

q Class 4 Soil Unit/Non-impacted.§ no evident anthropogenic impacts will be

designated as Class 4/Non-impacted.

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Graded Approach

qAnticipated that only units found toClass 1 will require consideration forlong term monitoring.

qUse of graded approach limits greatlyareas to be monitored and focusesactivities on areas with higher risk.

qMovement of areas from Class 1 toClass 2 may be allowed based onresults of characterization studies.

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Conclusions

qDesign of remedial and closure systemscan significantly impact long termmonitoring requirements

q Experience is that closure sites resistinnovations relative to baseline asclosure dates approach.