SOIL WASHING TREATMENT

S00073577SUPERFUND RECORDS

tec Jib1

vvEPA

v* R«twi OlfltOS

Environmental ProtectionAgency

Office of Emergency andRemedial ResponseWashington, DC 20460

Office ofResearch and DevelopmentCincinnati, OH 45268

Superfund EPA/540/2-90/017 September 1990

Engineering Bulletinil Washing Treatment

PurposeSection 121(b) of the Comprehensive Environmental

Response, Compensation,and LiabilityAct(CERCLA) mandatesthe Environmental Protection Agency (EPA) to select remediesthat "utilize permanent solutions and alternative treatmenttechnologies or resource recovery technologies to the maximumextent practicable" and to prefer remedial actions in whichtreatment "permanently and significantly reduces the volume,toxkity, or mobility of hazardous substances, pollutants, andcontaminants as a principal element." The Engineering Bulletinsare a series of documents that summarize the latest informationavailable on selected treatment and site remediationtechnologies and related issues. They provide summaries ofand references for the latest information to help remedialproject managers, on-scene coordinators, contractors, andother site cleanup managers understand the type of data andsite characteristics needed to evaluate a technology for potentialapplicability to their Superfund or other hazardous waste site.Those documents that describe individual treatmenttechnologies focus on remedial investigation scoping needs.Addenda will be issued periodically to update the originalbulletin!.

AbstractSoil washing is a water-based process for mechanically

scrubbing soils ex-situ to remove undesirable contaminants.The process removes contaminants from soils in one of twoways: by dissolving or suspending them in the wash solution(which is later treated by conventional wastewater treatmentmethods) or by concentrating them into a smaller volume ofsoil through simple particle size separation techniques (simitarto those used in sand and gravel operations). Soil washingsystems incorporating both removal techniques offer the greatestpromise for application to soils contaminated with a widevariety of heavy metal and organic contaminants.

The concept of reducing soil contamination through theuse of particle size separation is based on the finding that mostorganic and inorganic contaminants tend to bind, eitherchemically or physically, to clay and silt soil particles. The siltand clay, in turn, are attached to sand and gravel particles byphysical processes, primarily compaction and adhesion.Washing processes that separate the fine (small) clay and siltparticles from the coarser sand and gravel soil particles effectively

separate and concentrate the contaminants into a smallervolume of soil that can be further treated or disposed. Theclean, larger fraction can be returned to the site for continueduse. This set of assumptions forms the basis for the volume-reduction concept upon which most soil washing technologyapplications are being developed.

At the present time, soil washing is used extensively inEurope and has had limited use in the United States. During1986-1989, the technology was one of the selected sourcecontrol remedies at eight Superfund sites.

The final determination of the lowest cost alternative willbe more site-specific than process equipment dominated.Vendors should be contacted to determine the availability of aunit for a particular site. This bulletin provides information onthe technology applicability, the types of residuals resultingfrom the use of the technology, the latest performance data,site requirements, the status of the technology, and where togo for further information.

Technology ApplicabilitySoil washing can be used either as a stand-alone technology

or in combination with other treatment technologies. In somecases, the process can deliver the performance needed toreduce contaminant concentrations to acceptable levels and,thus, serve as a stand-alone technology. In other cases, soilwashing is most successful when combined with othertechnologies. It can be cost-effective as a pre-processing stepin reducing the quantity of material to be processed by anothertechnology such as incineration; it also can be used effectivelyto transform the soil feedstock into a more homogeneouscondition to augment operations in the subsequent treatmentsystem. In general, soil washing is effective on coarse sand andgravel contaminated with a wide range of organic, inorganic,and reactive contaminants. Soils containing a large amount ofclay and silt typically do not respond well to soil washing,especially if it is applied as a stand-alone technology.

A wide variety of chemical contaminants can be removedfrom soils through soil washing applications. Removal efficienciesdepend on the type of contaminant as well as the type of soil.Volatile organic contaminants often are easily removed fromsoil by washing; experience shows that volatiles can be removedwith 90-99 percent efficiency or more. Semivolatile organics

may be removed to a lesser extent (40-90 percent) by selectionof the proper surfactant. Metals and pesticides, which are moreinsoluble in water, often require acids or dictating agents forsuccessful soil washing. The process can be applicable for thetreatment of soils contaminated with specific listed ResourceConservation and Recovey Act (RCRA) wastes and otherhazardous wastes including wood-preserving chemicals(pentachlorophenol, creosote), organic solvents, electroplatingresidues (cyanides, heavy metals), paint sludges (heavy metals),organic chemicals production residues, pesticides and pesticidesproduction residues, and petroleum/oil residues [1, p. 659][2,p. 15][4][7 through 13]*.

The effectiveness of soil washing for general contaminantgroups and soil types is shown in Table 1 [1, p. 6S9][3, p.13][15, p.1 ]. Examples of constituents within contaminantgroups are provided in Reference 3, Technology ScreeningGuide For Treatment of CERCLA Soils and Sludges." This tableis based on currently available information or professionaljudgment where definitive information is currently inadequateor unavailable. The proven effectiveness of the technology fora particular site or waste does not ensure that it will be effectiveat all sites or that the treatment efficiency achieved will beacceptable at other sites. For the ratings used in this table, goodto excellent applicability means the probability is high that soil

ToblelApplicability of Soil Washing on General Contaminant

Groups for Various Soils

Contaminant Croups

w10

1|~*

i1

Halogenated volatilesHalogenated semivolatilesNonhalogenated volatilesNonhalogenated semivolatilesPCBsPesticides (halogenated)Dioxins/FuransOrganic cyanidesOrganic corrosives

Volatile metalsNonvolatile metalsAsbestosRadioactive materialsInorganic corrosivesInorganic cyanides

OxidizersReducers

MatrixSandy/ Sllty/Clay

Grove/tV So/ft Soils

mT

•T

T

T

T

V

V

•

•

Q

T

T

T

T

V

V

T

V

T

T

T

V

V

V

T

T

Q

T

T

T

T

T

• Good to Excellent Applicability: High probability that technology will besuccessful

T Moderate to Marginal Applicability: Exercise care in choosing technologyQ Not Applicable: Expert opinion that technology will not work

washing will be effective for that particular contaminant andmatrix. Moderate to marginal applicability indicates situationswhere care needs to be exercised in choosing the soil washingtechnology. When not applicable is shown, the technology willprobably not work for that particularcombination of contaminantgroup and matrix. Other sources of general observations andaverage removal efficiencies for different treatability groups arethe Superfund LDR Guide #6A, "Obtaining a Soil and DebrisTreatability Variance for Remedial Actions' (OSWER Directive9347.3-06FS), [16] and Superfund LDR Guide #68. "Obtaininga Soil and Debris Treatability Variance for Removal Actions*(OSWER Directive 9347.3-07FS) [17].

Information on cleanup objectives as well as the physicaland chemical characteristics of the site soil and its contaminantsis necessary to determine the potential performance of thistechnology and the requirements for waste preparation andpretreatment. Treatability tests are also required at the laboratoryscreening, bench-scale and/or pilot-scale level(s) to determine

Tab* 2Wast* SoB Characterization Parameters

• [reference number, page number]

Poramctcf

Key Physical

Particle size distribution:>2mm0.25-2 mm0.063-0.25 mm

<0.063 mm

Other Physical

Type, physical form,handling properties

Moisture content

Key Chemical

Organic*ConcentrationVolatilityPartition

coefficient

Metals

Humlc acid

Other Chemical

pH, bufferingcapacity

Purpose and Comment

Oversize pretreatment requirementsEffective soil washingLimited soil washingClay and silt fraction—difficult soilwashing

Affects pretreatment and transferrequirements

Affects pretreatment and transferrequirements

Determine contaminants and assessseparation and washing efficiency,hydrophobic interaction, washingfluid compatibility, changes inwashing fluid with changes incontaminants. May requirepreblending for consistent feed. Usethe jar test protocol to determinecontaminant partitioning.

Concentration and species ofconstituents (specific jar test) willdetermine washing fluid compatibility,mobility of metals, posttreatmenL

Organic content will affect adsorptioncharacteristics of contaminants on soil.Important in marine/wetland sites.

May affect pretreatmentrequirements, compatibility withequipment materials of construction,wash fluid compatibility.

o

Engineering Bulletin: Soil Washing Treatment

Figure 1Soil Washing Applicable Particle Size Range

SandAverage • Large

GravelAverage . Large

Soil Washing(Regime III) Soil Wash with

Specific Washing Fluid(Regime II) Economic Wash

with Simple ParticleSize Separation

Regime I)in

0.001 0.002 0.006 0.01 0.02 0.063 0.1 0.2 0.6 1 2

Diameter of Particle In Millimeters

10 20 60 100

the feasibility of the specific soil washing process beingconsidered and to understand waste preparation andpretreatment steps needed at a particular site. If bench-testresults are promising, pilot-scale demonstrations should normallybe conducted before final commitment to full-scaleimplementation. Treatability study procedures are explainedin the EPA's forthcoming document entitled "SuperfundTreatability Study Protocol: Bench-Scale Level of Soils Washingfor Contaminated Soils" [14].

Table 2 contains physical and chemical soil characterizationparameters that must be established before a treatability test isconducted on a specific soil washing process. The parametersare defined as either "key" or "other* and should be evaluatedon a site-specific basis. Key parameters represent soilcharacteristics that have a direct impact on the soil washingprocess. Other parameters should also be determined, but theycan be adjusted prior to the soil washing step based on specificprocess requirements. The table contains comments relating tothe purpose of the specific parameter to be characterized andits impact on the process [6, p. 90][14, p. 35].

Particle size distribution is the key physical parameter fordetermining the feasibility of using a soil washing process.Although particle size distribution should not become the solereason for choosing or eliminating soil washing as a candidatetechnology for remediation, it can provide an initial means ofscreening for the potential use of soil washing. Figure 1presents a simplistic particle size distribution range of curvesthat illustrate a general screening definition for soil washingtechnology.

In its simplest application, soil washing is a particle sizeseparation process that can be used to segregate the finefractions from the coarse fractions. In Regime I of Figure 1,where coarse soils are found, the matrix is very amenable to soilwashing using simple particle size separation.

Most contaminated soils will have a distribution that fallswithin Regime II of Figure 1. The types of contaminants foundin the matrix will govern the composition of the washing fluidand the overall efficiency of the soil washing process.

In Regime III of Figure 1, soils consisting largely of finersand, silt, and clay fractions, and those with high humiccontent, tend to contain strongly adsorbed organics thatgenerally do not respond favorably to systems that work by onlydissolving or suspending contaminants in the wash solution.However, they may respond to soil washing systems that alsoincorporate a particle size separation step whereby contaminantscan be concentrated into a smaller volume.

LimitationsContaminants in soils containing a high percentage of silt-

and clay-sized particles typically are strongly adsorbed anddifficult to remove. In such cases, soil washing generally shouldnot be considered as a stand-alone technology.

Hydrophobic contaminants generally require surfactantsor organic solvents for their removal from soil. Complexmixtures of contaminants in the soil (such as a mixture ofmetals, nonvolatile organics, and semivolatile organics) and


Figure 2Aqueous Soil Washing Process

Volatile*

ContaminatedSoil

Makeup water

Extracting Agents)(Surfactants, etc.)

SoilPreparation

(1)

PreparedSoil

Son WashingProcess

(2)-Washing-Rinsing-Size Separation

EmissionControl

TreatedAir Emissions

Recycled water

Chemicals

SlowdownWater

1WastewaterTreatment

(3)

TreatedWater

Sludges/Contaminated Fines

Clean Soil

Oversized Rejects

frequent changes in the contaminant composition in the soilmatrix make it difficult to formulate a single suitable washingfluid that will consistently and reliably remove all of the differenttypes of contaminants from the soil particles. Sequentialwashing steps may be needed. Frequent changes in the washformulation and/or the soil/wash fluid ratio may be required [3,p.76][14,p.7].

While washwater additives such as surfactants and chelantsmay enhance some contaminant removal efficiencies in the soilwashing portion of the process, they also tend to interfere withthe downstream wastewater treatment segments of the process.The presence of these additives in the washed soil and in thewastewater treatment sludge may cause some difficulty in theirdisposal [1 A, p. 7][15, p. 1 ]. Costs associated with handling theadditives and managing them as part of the residuats/wastewaterstreams must be. carefully weighed against the incrementalimprovements in soil washing performance that they mayprovide.

Technology DescriptionFigure 2 is a general schematic of the soil washing process

l1,p.657][3,p.72][l5,P.1].

Soil preparation (1) includes the excavation and/or movingof contaminated soil to the process where it is normallyscreened to remove debris and large objects. Depending uponthe technology and whether the process is semibatch orcontinuous, the soil may be made pumpable by the addition ofwater.

A number of unit processes occur in the soil washingprocess (2). Soil is mixed with washwaterand possibly extractionagent(s) to remove contaminants from soil and transfer themto the extraction fluid. The soil and washwater are thenseparated, and the soil is rinsed with clean water. Clean soil isthen removed from the process as product. Suspended soilparticles are recovered directly from the spent washwater, assludge, by gravity means, or they may be removed by flocculationwith a selected polymer or chemical, and then separated bygravity. These solids will most likely be a smaller quantity butcarry higher levels of contamination than the original soil and,therefore, should be targeted for either further treatment orsecure disposal. Residual solids from recycle water cleanup mayrequire post-treatment to ensure safe disposal or release. Waterused in the soil washing process is treated by conventionalwastewater treatment processes to enable it to be recycled forfurther use.


Wastewater treatment (3) processes the blowdown ordischarge water to meet regulatory requirements for heavymetal content, organic*, total suspended solids, and otherparameters. Whenever possible, treated water should berecycled to the soil washing process. Residual solids, such asspent ion exchange resin and carbon, and sludges from biologi-cal treatment may require post-treatment to ensure safe disposalor release.

Vapor treatment may be needed to control air emissionsfrom excavation, feed preparation, and extraction; theseemissions are collected and treated, normally by carbonadsorption or incineration, before being released to theatmosphere.

Process ResidualsThere are four main waste streams generated during son

washing: contaminated solids from the soil washing unit,wastewater, wastewater treatment sludges and residuals, andair emissions.

Contaminated clay fines and sludges resulting from theprocess may require further treatment using acceptabletreatment technologies (such as incineration, low temperaturedesorption, solidification and stabilization, biological treatment,and chemical treatment) in order to permit disposal in anenvironmentally safe manner [16]. Blowdown water may needtreatment to meet appropriate discharge standards prior torelease to a local, publicly owned wastewater treatment worksor receiving stream. To the maximum extent practical, thiswater should be recovered and reused in the washing process.The wastewater treatment process sludges and residual solids,such as spent carbon and spent ion exchange resin, must beappropriately treated before disposal. Any air emissions fromthe waste preparation area or the washing unit should becollected and treated, as appropriate to meet applicableregulatory standards.

Site RequirementsAccess roads are required for transport of vehicles to and

from the site. Typically, mobile soil washing process systemsare located onsite and may occupy up to 4 acres for a 20 ton/hour unit; the exact area will depend on the vendor systemselected, the amount of soil storage space, and/or the numberof tanks or ponds needed for washwater preparation andwastewater treatment.

Typical utilities required are water, electricity, steam, andcompressed air. An estimate of the net (consumed) quantity oflocal water required for soil washing, assuming water cleanupand recirculation, is 130,000-800,000 gallons per 1,000 cubicyards (2,500,000 Ibs.) of soil (approximately 0.05-0.3 gallonsper pound).

Because contaminated soils are usually consideredhazardous, their handling requires that a site safety plan bedeveloped to provide for personnel protection and specialhandling measures during soil washing operations.

Moisture content of soil must be controlled for consistenthandling and treatment; this can be accomplished, in part, bycovering excavation, storage, and treatment areas.

Fire hazard and explosion considerations should be minimal,since the soil washing fluid is predominantly water. Generally,soil washing does not require storing explosive, highly reactivematerials.

Climatic conditions such as annual or seasonal precipitationcause surface runoff and water infiltration. Berms, dikes, orother runoff control methods may be required. Cold weatherfreezing must also be considered for aqueous systems and soilexcavation operations.

Proximity to a residential neighborhood will affect plantnoise requirements and emissions permitted in order to minimizetheir impact on the population and meet existing rules andregulations.

If all or part of the processed soil is to be redeposited at thesite, storage areas must be provided until analytical data areobtained that verifies that treatment standards have beenachieved. Onsite analytical capability could expedite thestorage/final disposition process. However, soil washing mightbe applied to many different contaminant groups. Therefore,the analytes that would have to be determined are site specific,and the analytical equipment that must be available will varyfrom site to site.

Performance DataThe performances of soil washing processes currently

shown to be effective in specific applications are listed in Table3 [1][2][4J[7 through 13]. Also listed are the range of particlesize treated, contaminants successfully extracted, byproductwastes generated, extraction agents used, major extractionequipment for each system, and general process comments.

The data presented for specific contaminant removaleffectiveness were obtained from publications developed bythe respective soil washing system vendors. The quality of thisInformation has not been determined.

RCRA Land Disposal Restrictions (LDRs) that requiretreatment of wastes to best demonstrated available technology(BOAT) levels prior to land disposal may sometimes bedetermined to be applicable or relevant and appropriaterequirements (ARARs) for CERCLA response actions. The soilwashing technology can produce a treated waste that meetstreatment levels set by BOAT, but may not reach these treatmentlevels in all cases. The ability to meet required treatment levelsis dependent upon the specific waste constituents and thewaste matrix. In cases where soil washing does not meet theselevels, it still may, in certain situations, be selected for use at thesite if a treatability variance establishing alternative treatmentlevels is obtained. ERA has made the treatability varianceprocess available in order to ensure that LDRs do notunnecessarily restrict the use of alternative and innovativetreatment technologies. Treatability variances may be justifiedfor handling complex soil and debris matrices. The followingguides describe when and how to seek a treatability variance forsoil and debris: Superfund LDR Guide *6A, "Obtaining a Soil


and Debris Treatability Variance for Remedial Actions" (OSWERDirective 9347.3-06FS) [161 and Superfund LDR Guide #68,"Obtaining a Soil and Debris Treatability Variance for RemovalActions" (OSWER Directive 9347.3-07FS) [17]. Anotherapproach could be to use other treatment techniques in serieswith soil washing to obtain desired treatment levels.

Technology StatusDuring 1986-1989, soil washing technology was selected

as one of the source control remedies at eight Superfund sites:Vineland Chemical, New Jersey; Koppers Oroville Plant,California; Cape Fear Wood Preserving, North Carolina; EwanProperty, New jersey; Tinkam Garage, New Hampshire; UnitedScrap, Ohio; Koppers/Texarkana, Texas; and South Cavalcade,Texas [18].

A large number of vendors provide a soil washingtechnology. Table 3 shows the current status of the technologyfor 14 vendors. The front portion of the table indicates the scaleof equipment available from the vendor and gives someindication of the vendor's experience by showing the year itbegan operation.

Processes evaluated or used for site cleanups by the EPA areidentified separately by asterisks in the Proprietary VendorProcess/EPA column in Table 3.

The following soil washing processes that are underdevelopment have not been evaluated by the EPA or included

in Table 3. Environmental Group, Inc. of Webster, Texas, hasa process that reportedly removes metals and oil from soil.Process efficiency is stated as greater than 99 percent for leadremoval from soils cleaned in Concord, California; greater than99 percent for copper, lead, and zinc at a site in Racine,Wisconsin; and 94 percent for PC8 removal on a Mom'son-Knudsen Company project. The process does not appear toseparate soil into different size fractions. Detailed informationon the process is not available. Consolidated Sludge Companyof Cleveland, Ohio, has a soil washing system planned thatincorporates their Mega-sludge Press at the end of the processfor dewatering solids. The system has not yet been built.

Vendor-supplied treatment costs of the processes reviewedranged from $50 to $205 per ton of feed soil. The upper endof the cost range includes costs for soil residue disposal.

EPA ContactTechnology-specific questions regarding soil washing may

be directed to:

Michael GruenfeldU.S. EPA, Releases Control BranchRisk Reduction Engineering LaboratoryWoodbridge Avenue, Building 10Edison, New jersey 08837Telephone FTS 340-6625 or (201) 321-6625.


Table 3. Summary of Performance Data and Technology Status - Part I

Proprietary VendorProcea/fPA

——————————U.S.*Proccsses .-• i V

(1) SOIL CLEANING COMPANYOF AMERICA [5][1 5, p. 2J

(2)- 8IOTROLSOILTREATMENTSYSTEM (BSTS)Kp.«Jli2J

(3) EPA'S MOBILE COUNTER-CURRENT EXTRACTOR19J15. p. 5]

(4)« EPA'S FIRST GENERATIONPHOT DRUM SCREENWASHER [10, p. 8)

(S)* MTA REMEDIALRESOURCES111J115.P.2J

Non-U.S. Processes •• • • • - • •

(6) ECOTECHNIEKBVftp. 17)

(7) BODEMSANERINGNEDERLAND8V(BSN)ft p. 17]

(8) HARBAUERftp.20J[7,p.S]

(9) HWZBODEMSANERING BVft p. 171

(10) HEIJMANMIUELTTECHNIEK BVftp.17J[7.p.6]

(11) HEIDEMIJ FROTHFLOTATIONft p. 8]

Hlghett Scaleof Operation

?-••:••..-.(" •<*••>-.••:-

Full scale1 5 tons/hr

Pilot scale500 Ibs/hr

Pilot scale4.1 tons/hr

Pilot scale

Bench scale

-•••' •-..--^••-

CommerciallOOton/hrmax

Commercial20ton/hr

Commercial1S-20tonsVhr

Commercial20-25 tons/hr

Pilot scale10-15 tons/hr

Full scale

Year OperationBegan

/-V:vT.'«< •.-.'••-•:•, -*..'*

1988

Fall, 1987

Modified withdrum washer

and shakedown-1982

Full Scale-1 986

1988

N/A

1982

1982

Lab -1985

Commercial -1986

With finesremoval -1987

1984

198S

N/A

Range of ParticleShe Treated

.;-,.i »•—-'•• .?-*<-*,' "I .', - '

Bulk son

Above clay size andbelow O.S in. Somecleaning of fine par-ticles in bio-reactor

2-25 mm in drumwasher<2 mm in four-stageextractor

Oversize (>2 mm)removed prior totreatment

Oversize removedprior to treatment

•H NHHBh H

Sandy soil

>1 00 mm removed

No more than 20%<63|im

Sludge <30 urn notcleaned

15 jim -5mm Pre-treatment: coarsescreens, electromagnetblade washer

<10 mm and >63 jim

<1 0 mm and no morethan 30% <63 Jim

<4 mm and no morethan 20% <50 um

Contaminant!extracted From Soil

^ ^mm g miiiijOil and grease

Organics - pentachloro-phenol, creosote,naphthalene, pyrene.fluorene, etc

Soluble organics(phenol, etc.)

Heavy metals(Pb, etc.)

Petroleumhydrocarbons

Organics (oil)

Heavy metals (inorganics;removed using counter-current decantationwith leaching

Crude oil

Oil from sandy soil

Mostly organics

Limited heavy metalsremoval experience

Cyanide, ChlorinatedHC, some heavymetals, PNA

Cyanide, heavy metals,mineral oil (waterimmiscible hydro-carbons)

Cyanide, heavy metals,chlorinated HCs, oil,toluene, benzene,pesticides, etc

iextraction Agent(t)

,^^_^_^^^__^ ^BaVUUH^ H

Hot water withsurfactant

Proprietaryconditioningchemkals

Various solvents,additives, surfactants,redox acids and basesChelating agent(EDTA)

Biodegradablesurfactant(aqueous slurry)

Surfactants andalkaline chemicalsadded upstream offroth flotation cells.Acid for leaching.

• • •••• • • ••• •B

None. Water-sandslurry heated to 90*Cmax. with steam.

None. Uses highpressure water jetfor soils washing.

Hydraulkalryproduced oscillation/vibration

SurfactantsAcid/base

Sodium Hydroxideto adjust pH

Surfactants

Proprietary extractionagents. HydrogenPeroxide (H,0,)added to reactwith extracted CNto form CO, and NH,

Proprietary Surfact-ants and other pro-prietary chemkals

•Process evaluated or used for site cleanup by the EPA. N/A « Not available.


Table 3. Summary of Performance Data and Technology Status - Part I (continued)

Proprietary VendorPnctu/CPA

Highest Scaleof Operation

Non U.S 'Processes (continued>

02) EWHALSEN-BREITENBURCDekomat System [2, p. 20]

(13) TBSCINDUSTRIEVEJTIETUNGENOn Crep 1 System [7, p. 7]

04) KLOCKNERUMWELTECHNIKJet-Modified BSN [2, p. 20]

PHot scale8-1 0 cu. m/hr

Pilot scale

PBot scale

Year OperationBegan

•BBKBB n

N/A

1986

N/A

Range of Portkktoe Treated

M9MBBMVI<80mm

Clays treated offsite

Sand <50 mm

Particles <1 00 urntreated offsite

No more than 20%<63u/n

Contaminant!extracted from Sott

Oil from sandy soil

Hydrocarbon and oil

Aliphatics and aromaticswith densities < water,volatile organics, someother hydrocarbons

Extraction Agcntfs)

••MHH BIIBBllllllll

Proprietary

Proprietary combina-tion of surfactants,solvents, and aromatichydrocarbons

None. Soil blastedwith a water jet (at5,075 psi)

Table3. Summary of Performance Data and Technology Status -Part II

Proprietary VendorPmctu/lPA

U.S. Processes rv.--: . -*<

(1) SOIL CLEANINGOF AMERICA

(2)* BIOTROLSOILTREATMENT SYSTEM(BSTS)

(3) EPA'S MOBILECOUNTER-CURRENTEXTRACTOR

(4)« EPA's FIRSTGENERATION PILOTDRUM SCREENWASHER (POSW)

(5)' MTA REMEDIALRESOURCES (MTARRI)Froth Flotation

Byproduct WattesGenerated

Wet oil

Oil and grease

Sludge from bio-ogical treatment

Gay fraction

Recovered organics(extractor skimmings)

Spentcarbon (oversize)

Sludge

Flocculated fines

Fk/cculation froth

Extractionequipment

Screw conveyors

Agitatedconditioning tank

Froth flotation

Slurry bioreactor

Drum screen

Water knife

Soil scrubber

4-StageCounter-current

chemical extractor

Drum screenwasher

Reagent blendtank

Flotation cellsCounter-current

decantation

efficiency ofContaminant Removal

• ••••••••••• ••••B MmnH

Contom- Removal Residualinont Efficiency 96 pom

Oil and 50-83 250-600grease

For the case presented:90-95% for Pentachlorophenol;

to residuals <1 15 ppm.85-95% for most other organics;to residuals <1 ppm.

Confom- Removal Residuafinont Efficiency 96 ppm

Phenol 90 from in. soil 180 from or. soil 96

AS20, 50-80 0.5-1.3

Soil Size ftesf*Contam-Froction Removal dualinont mm Effic.% ppm

Oil and 0.25-2 99 <5grease <0.25 90 2400

Contom- Removal Residualinant Efficiency % ppm

Volatileorganics 98-99+ < SO

Semivolatileorganics 98-99+ < 250

Most fuelproducts 98-99+ < 2200

AdditionalProcess Comments

Three screw conveyors operatedin series, hot water with surfactantinjected into each stage. Final soilrinse on a fourth screw conveyor.

Dewatered clays and organics to betreated offsite by incineration,solidification, etc. Washed soil wasapprox. 78% of feed. Therefore,significant volume reduction wasachieved.

Clay fraction treated elsewhere.

Process removal efficiencyincreases if extracting medium isheated. Install wet classifiersbeneath the PDSW to removewaste water from treated soil.Auger classifiers are required toto discharge particles effectively.

Flotation cells linked by underflowweir gates. Induced air blowndown a center shaft in each w|>.Continuous flow operation. Frothcontains 5-1 0 wt% of feed soil.

•Process evaluated or used for site cleanup by the EPA. N/A = Not available.

8 Engineering Bulletin: Soil Washing Treatment

Table 3. Summary of Performance Data and Technology Status • Part II (continued)

I Proprietary VendorProceu/tPA

Byproduct WastesGenerated

| Non-U.S:4>rocesscs ••••::•>•»....--.:•. ;' ••:•*?*: • • : - • -

(6) ECOTECHNIEKBV

(7) BODEMSANERINCNEDERLANDBV(BSN)

(8) HARBAUEROF AMERICA

(9) HWZBODEMSANERINC BV

(10) HEIJMANMIUEUTECHNIEK BV

01) HEIDEMIJ FROTHFLOTATION

02) EWHALSEN-BREITENBURCOekomit System

(13) TBSCINDUSTRIEVEmET-UNCENOil Crepl System

(14) KLOCKNERUMWELTECHNIKHigh Pressure Waterlet-Modified BSN

Wet 08

Oil/organic*recovered from

wastewater fines

Carbon which maycontain contami-

nant*

Fines

Sludge containingiron cyanide

Large particles —carbon, wood, grass

Flocculated finessludge

Oil (if any) and silt

Contaminated float

Recovered oil

Flocculated fines(sludge)

Oil phase contain-ing Oil Crep 1

Oil/organksrecovered from

wastewater fines

Sludge

Extractionequipmentjummumi

Jacketed, agitatedtank

Water Jet

Conditioning tank

Low frequencyvibration unit

Scrubber(for causticaddition)

Upflow classifier

Mix tankfollowed by soilsfraction equip-ment — hydro-clones, sieves,

tilt plate separators

Conditioning tank

Froth flotationtanks

High-shearstirred tank

Screw mixerfollowed by a

rotating separationdrum for oil

recovery

Water jet-circular nozzlearrangement

Efficiency ofContaminant Removal

About 90%20,000 ppm residual oil

Selected results:Content- Removal ResidualInont Efficiency* ppmAromatks >«1 >4SPNAs 95 ISCrude oi 97 2300

Contom- Removal ResidualInont Efficiency* ppm

Organlc-d NOTot organic* 96 159-201Tot phenol 86-94 7-22.5PAH 86-90 91.4-97.5PCB 84-88 03-1.3

Contom- Removal ResidualInont Efficiency * ppm

CN 95 5-15PNAs 98 15-20Chlorin-HC 98 <1Heavy meUls 75 75-125

Contom- Removal ResidualInant Efficiency N ppm

Cyanide 93-99 <1SHeavy metalcations approx. 70 <200

Contom- Remove/ ResidualInant Efficiency % ppm

Cyanide >95 5Heavy metals >90avg >150Chlorin-HC >99 0.5Ofl >99 20

About 95% on removed

>95% Removal of hydrocarbonshas been achieved. Results areinfluenced by other contaminantspresent

Selected results:Contom- Removal Residual

Inant Efficiency N ppmHC 96.3 82.05Chlorin-HC >75. <0.01Aromatks 99.8 <0.02PAHs 95.4 15.48Phenol >99.8 <OX>1

Additional \Process Comments |

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Effectiveness of process depen-dent on soil particle size and typeof oil to be separated.

No comments

Vibrating screw conveyor used.

Cleaned sod separated fromextractant liquor in stages; coarsesoil by sedimentation, mediumfraction In hydroclone, fines(1 5-20 urn) by vacuum filter press.

When the fines fraction (<63 urn) isgreater than 20%, the process is noteconomical. HWZ has had someproblems in extracting PNAs andoily material.

Process works best on sandy soflswith a minimum of humus-likecompounds. Because no sand orcharcoal fitters are employed byHeijmans, the system does notremove contaminants such aschlorinated hydrocarbons.

Process has broad application forremoving hazardous materials fromsoil. Most experience has been ona laboratory scale.

Cleaned soil from high shearstirred tank is separated intofractions using vibrating screens,screw classifiers, hydroclones, andsedimentation tanks.

Oil Crep system was used success-folly in Flansburg, FRC On 1986)to remove PCBs, PAHs, and otherhydrocarbons.

No comments

•Process evaluated or used for site deanup by the EPA. N/A • Not available.

Engineering Bulletin: So// Washing Treatment

^PREFERENCES

2.

3.

4.

5.

6.

7.

8.

AislnkJ.W. Extractive Methods for SoilDecontamination; a General Survey and Review ofOperational Treatment Installations. In: Proceedingsfrom the First International TNO Conference onContaminated Soil, Ultrecht, Netherlands, 1985.Raghavan, R., D.H. Dietz, and E. Coles. CleaningExcavated Soil Using Extraction Agents: A State-of-the-Art Review. EPA 600/2-89/034, U.S. EnvironmentalProtection Agency, 1988.Technology Screening Guide for Treatment of CERCLASoils and Sludges. EPA 540/2-88/004, U.S.Environmental Protection Agency, 1988.M.K. Stinson, et al. Workshop on the ExtractiveTreatment of Excavated Soil. U.S. EnvironmentalProtection Agency, Edison, New Jersey, 1988.Smarkel, K.L Technology Demonstration Report - SoilWashing of Low Volatility Petroleum Hydrocarbons.California Department of Health Services, 1988.Guide for Conducting Treatability Studies UnderCERCLA, Interim Final. EPA/540/2-89/058, U.S.Environmental Protection Agency, 1989.Nunno, T.J., J.A. Hyman, and T. Pheiffer. Developmentof Site Remediation Technologies in EuropeanCountries. Presented at Workshop on the ExtractiveTreatment of Excavated Soil. U.S. EnvironmentalProtection Agency, Edison, New Jersey, 1988.Nunno, T.J., and J A Hyman. Assessment ofInternational Technologies for Superfund Applications.EPA/540/2-88/003, U.S. Environmental ProtectionAgency, 1988.

9. Scholz, R., and ]. Milanowski. Mobile System forExtracting Spilled Hazardous Materials from ExcavatedSoils, Project Summary. EPA/600/52-83/100, U.S.Environmental Protection Agency, 1983.

10. Nash, J. Field Application of Pilot Scale SoHs WashingSystem. Presented at Workshop on the ExtractingTreatment of Excavated Soil. U.S. EnvironmentalProtection Agency, Edison, New Jersey, 1988.

11. Trost, P.B., and R.S. Rickard. On-site Soil Washing—ALow Cost Alternative. Presented at ADPA. Los Angeles,California, 1987.

12. Pflug, A.D. Abstract of Treatment Technologies, Biotrol,Inc., Chaska, Minnesota, (no date).

13. Biotrol Technical Bulletin, No. 8 7-1 A, Presented atWorkshop on the Extraction Treatment of ExcavatedSoil, U.S. Environmental Protection Agency, Edison,New Jersey, 1988.

14. Superfund Treatability Study Protocol: Bench-ScaleLevel of Soils Washing for Contaminated Soils, InterimReport U.S. Environmental Protection Agency, 1989.

15. Innovative Technology: Soil Washing. OSWER Directive9200.5-250FS, U.S. Environmental Protection Agency,1989.

16. Superfund LDR Guide #6A: Obtaining a Soil and DebrisTreatability Variance for Remedial Actions. OSWERDirective 9347.3-06FS, U.S. Environmental ProtectionAgency, 1989.

17. Superfund LDR Guide #6B: Obtaining a Soil and DebrisTreatability Variance for Removal Actions. OSWERDirective 9347.3-07FS, U.S. Environmental ProtectionAgency, 1989.

18. ROD Annual Report, FY1989. EPA/540/8-90/006, U.S.Environmental Protection Agency, 1990.

OTHER REFERENCES

Overview—Soils Washing Technologies ForComprehensive Environmental Response,Compensation, and Liability Act, Resource Conservationand Recovery Act, Leaking Underground Storage Tanks,Site Remediation, U.S. Environmental ProtectionAgency, 1989.

Engineering Bulletin: Soil Washing Treatment• U.I. COVf.fimr.ll1 MIP,II1C orrict l»0/»1-ll»t-»fll

United States Center for Environmental Research BULK RATEEnvironmental Protection Information POSTAGE & FEES PAIDAgency Cincinnati, OH 45268 EPA

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SOIL WASHING TREATMENT