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ffpf^p-r,^, _ fublic Health ServiceDEPARTMENT OF HEALTH A HUMAN SERVICES '"-CEIVED Agency for Toxic Substances

n-t- „- and Disease Registry——:————————wn^3—iu;———''» R JI J^ kWk «k. *• «k ——. «J •Memoranda...

ft^P SECTIONDate .April 24, 1989

From ToxicologistEmergency Response Branch, Office of Health Assessment, ATSOR

Subject Health Consultation: Proposed Clean-up Levels for Closure of the MobileIncinerator System, Denney Farm Site, Barry County, Missouri.

To Mr. Daniel HarperPublic Health AdvisorEPA Region VII -̂ yA/Through: Chief, Emergency Response Branch, OHA, ATSDR̂ ^̂ i.

C\JCM

The Environmental Protection Agency (ERA) constructed a mobileincineration system (MIS) at the Denney Farm Site. They used the MIS to <—destroy diozin in contaminated soil and chemical wastes. The EPA asked 0the Agency for Toxic Substances and Disease Registry (ATSDR) questionsconcerning acceptable chemical residues for both soils and structuresafter closure of the incinerator site.

DOCUMENTS REVIEWED

1. Memorandum Billy J, Fairless, EPA to Morris Kay, EPA datedJanuary 15, 1989.

2. Memorandum Paul Doherty, EPA to David Parker, ATSDR dated January31, 1989.

3. Memorandum Jonathan Russ and Bill Marcus, Environment and Ecologyto Paul Doherty, EPA dated January 12, 1989.

4. Memorandum Paul Doherty, EPA to Charles Hensley, EPA datedJanuary 30, 1989.

5. Memorandum Paul Doherty, EPA to David Parker, ATSDR dated March7. 1989.

6 . Memorandum Charles Hensley, EPA to David Parker, ATSDR datedMarch 9 , 1989.

7. Memorandum Donald Sandifer, EPA, to Charles Hensley, EPA datedApril 10, 1989.

RECEIVED

l i ' l r

Page 2 - Mr. Daniel Harper

CONTAMINANTS AND PATHWAYS

The purpose of the cleanup activity for the cite is one of the following:

to remove completely the chemical from environment,

to eliminate human exposure pathways, or

to reduce the potential human exposure to acceptable levels.mCM•^

Therefore, the contaminants and pathways considered in this evaluation arethose after completion of the cleanup. The most significant contaminantsat the site are 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) andpolychlorinated biphenyls (PCBs). Other contaminants identified arevarious phthalate esters, 2,4,5-trichlorophenol, a few polynuclear 0aromatic hydrocarbons (PAH's), 2,4-dimethylphenol, bromonaphthenols, Q2-broaonaphthlene, xylene, tetrachlorobenzene, hexachlorobenzene,methylene chloride, acetone, ethyl benzene, and chromium.

The data available shows that for most areas at the site the presence ofeither dioxin or PCB's will require cleanup actions. The actionsnecessary to achieve acceptable residues of these chemicals also mitigatedthe presence of the other chemicals. These actions were either to removethe contaminated soil for treatment or disposal, or to cover them with abarrier of clean soil at least 1 foot deep. These actions eitherprevented or to minimized human and animal exposure to the on-sitechemicals.

DISCUSSION

To understand the extent of contamination and the effectiveness of variouscleaning techniques the EPA conducted four sampling trips to the DenneyFarm site. The EPA provided the results of these trips that occurred onNovember 7-9, 1988, December 7-9, 1988, January 3-5, 1989, and January 19,1989 to assist ATSDR's evaluation of the site. The EPA used the 95percent confidence limit sampling procedure for surface soils. Othersampling activities included composite grab samples of soil, concrete,woodchip samples of interior vail structures or framework, and wipesamples of various interior and exterior building surfaces.

Using the results of these tests the EPA proposed and used the followingcleanup criteria to protect the public health and the environment for anyfuture use of this site.

Page 3 - Mr. Daniel Harper

For soils:

2,3,7,8-TCDD

Surface coils

less than 1 ppb

PCB's

volatile/semivolatile organics

Heavy Metals

For buildings:

less than 2 ppm

less than 50 ppm

non-E.P. Toxic

Subsurface coils

less than 10 ppb with 12Inches of clean soil cover

or•axifflua 4 feet excavation with4 feet soil cover

less than 10 ppm with 12inches of clean cover

less than 50 ppn

non-E.P. Toxic

All octal and wooden portions of buildings decontaminated and disposedin a local sanitary landfill.

All floors, reinforced concrete vails and foundations decontaminatedby appropriate methods.

Placement of decontaminated walls and foundations on thedecontaminated floors of either the Microbiological DecontaminationBuilding 1 (MDB-1) or Microbiological Decontamination Building (MDB-2)and covered with clean soil (2 to 4 feet) to existing grade.

The EPA established the following clean-up criteria for contaminatedbuilding surfaces:

2,3,7,8-TCDD

Wood FrameworkandSheet Metal Siding

<10 ng/n3

Buried ConcreteFoundation

<10 ppb and <100 ng/m(10 pg/m") with a minimum 12inches of soil cover

or 9<10 ppb and >100 ng/n-(10 pg/a2) (followingdecontamination efforts) plusa surface sealant and aminimum 12 inches of soilcover.

Page 4 - Mr. Daniel Harper

PCB's 10 ug/100 c«2 100 ug/100 en2 or greaterthan 100 ug/100 en*(following decontaminationeffort*) plus a surface•ealant and a •inixma 12Inches •oil cover

volatile/ no significant no •ignificant•eaivolatile contamination contaminationorganics

heavy metals no significant no significantcontamination contaminat ion.

inC\J<^-

Following trial cleanup efforts the EPA sampled the concrete by drilling 0through 75 to 90 percent of the total thickness of the fora with a carbide Qtipped masonry bit. They collected and analyzed the concrete dustgenerated by the drilling process for dioxin.

The EPA did not propose specific cleanup levels for volatile/semivolatileorganics and heavy metals since they considered the concentrations ofthese hazardous substances insignificant relative to the diozin and PCBlevels. They believe that the decontamination work effectively reducedthe concentrations of these compounds to below levels of concern.

For equipment:

All equipment decontaminated to the criteria proposed for the woodframework and sheet-metal siding.

For other contaminated material:

EPA desired the freedom to chose between incineration anddecontamination before disposal, when choosing decontaaination forspecific equipment, debris, or other solid waste, they used the woodframework and sheet-metal siding criteria.

The EPA has cleaned the site and covered it with from 1 to 5 feet ofsoil. The only portion of the site reportedly not covered by at least 1foot of •oil are two sections both with less than 1 ppb upper 95 percentconfidence limit 2,3, 7 , 8 - T C D D . These two areas reportedly are steep,rocky, and brush covered, conditions unconducive to cattle grazing.Therefore, the area of the site on which cattle grazing is likely to occurhas at least 1 foot of clean soil cover. The area not covered isphysically unconducive to animal grazing. The site is a small portion ofthe Denney farm, in an upland area, away from both water and normalgrazing areas. All of these contribute to reducing the exposure thatmight occur were grazing confined to the site itself.

Page 5 - Mr. Daniel Harper

After cleanup, the EPA reported the upper 95 percent confidence levelsampling results for each of the area* within the «ite. These resultsshow that oo section had more than 10 ppb TCDD before cover with up to 5feet of soil. The highest concentration reported, from section 104, was7.8 ppb. After final cover, this location had 2.5 feet of clean soil ontop of it. The maximum reported TCDD upper 95 percent confidence limitconcentration under 1 foot of clean soil was 2.5 ppb fron section 043.The TCDD concentration reported for this section before excavation was 1.7ppb. A slight increase in TCDD concentration also occurred in section 106 ^Qwhere it rose from 2.1 to 2.4 ppb after excavation. Neither of theseresidues at there respective locations present a significant threat tohuman health or the environment at this site.

CM«̂ -

During the cleanup activity, EPA found that it was impossible to remove 0the concrete walls and foundations from buildings. Because of the massive Qreinforcement used in construction, they left the walls and foundations inplace and covered them with at least 1 foot of clean soil. Thus thatportion of the proposed cleanup plan that entailed removal and depositionwithin either MDB-1 or MDB-2 did not occur.

CONCLUSIONS AND RECOMMENDATIONS

The EPA developed criteria for the site cleanup based on a potentialfuture use of grazing dairy animals.

The ATSDR believes that the effected cleanup plan will protect the publichealth for such future use.

rk A. McClanahan, Ph.D.

") ")

SECTION 9

DENNEY FARM SITE AND MIS CLOSURE

CLOSURE PLANS AND CLEANUP CRITERIA

After the MIS had completed incineration of thedioxin-contaniinated materials from the eight sites, the MISwas dosed by executing approved closure plans [ 9 , 3 0 ] .Because incineration activities and site activities wereconducted by different parties and were covered under twoseparate permits, two separate approved closure plans wererequired by the regulatory authorities, one for the MIS andone for the site. The closure of the MIS followed the planpresented in the 1987 final permit [ 9 ] . The closureprocedures for the MIS were updated by adding greater detailto the plan presented in the permit. These details wereincluded in the final closure plan for the Denney Farmsite [ 3 0 ] . Besides procedures for decontaminating anddecommissioning the MIS, the site closure plan includedsampling procedures for s o i l , buildings and equipment, scopeof the decontamination work, and action levels to triggerdecontamination work.

Closure of the MIS and Oenney Farm site, which took placefrom January 24, to June 30, 1989, involved decontaminationof the MIS, Denney Farm s o i l , and supporting equipment andbuildings. The cleanup criteria for the MIS and the site,which were included in the final site closure plan [ 3 0 ] , arepresented in Table 60. The Agency for Toxic Substances andDisease Registry provided health advisories used to developthese criteria, and the criteria were approved by MDNR.

CLOSURE SUMMARY

Closure activities included excavation and incinerationof dioxin-contaminated s o i l , decontamination or incinerationof contaminated debris, decontamination of buildings andequipment, and disassembly of buildings and the MI S . Closureactivities are summarized below.

Almost 3,000,000 1b of dioxin-contaminated soil anddebris were incinerated. The debris Included: the loadingdock, HEPA fitter and associated ducting, wooden pallets,metal drums, and plastic sheeting used to protect excavatedareas. The four buildings in the hot zone, which wereconstructed of sheet metal w a l l s , wooden supports, andconcrete foundations, were decontaminated. The followingequipment was decontaminated: the four rented pieces of soilmoving equipment used in the hot zone, including a.backhoe, aforklift, and two small front-end loaders ( B o b c a t s " ) ; andthe MIS feed system, consisting of three feed conveyors, the

193

TABLE 60. ACTION LEVELS OR CLEANUP CRITERIAFOR DENNET FARN CLOSURE

Cent—inane Surface Soils Sliiaurfac* Soil* BuildinasCa)

CO to 3 in. (>3 In. dfrth) (Uood Fr—fork/Sheetdepth) Metal Sidino/Foundationa)

2,3,7,8-TCDB

or Mxiam 4*ftexcavation * 4-ft•oil caw

PCS*

Volatile/S—ivolatiIe

H—vy Nefl*

<1 PPb

<ZppB

<50ppi

non-E.P. Toxic

<10pcto

+ 12- in wil cover

<IOB»4' 12-fn coil cover

<50pc

non-E.P. Toxic

10 no/M2 (1 pg/

or >10 ng/B *

100 nB/m2

or >1 ua/ca *

no cignificantconfined on

no lignificantcont—ination

«2)Sealant

Sealant

(a) Fouidatiorr had in additional criterion. Core •Mpl— ucre taken and the dust fromth« —pi— M— analyzed and had to «hoM concentrations of 2,3,7,0-TCDO <10 ppb.

1 9 4

shredder, weigh chute, weigh scale, ram, ram trough, andHapman1* conveyor. The rubber conveyor belts wereincinerated as part of the decontamination process.

Equipment located outside the hot zone was cleaned andwipe tested to ensure that It was not contaminated. Wipetesting of the HIS building located outside the hot zoneshowed that the walls were not contaminated. However, thefloor beneath the feed system had to be decontaminated. The17 pieces of rental equipment located In the safe zone,consisting of two air compressors, eight trailers serving asoffices and crew quarters, four storage trailers for spareparts and other materials, and three frag tanks forwastewater storage, were cleaned and wipe tested. The MISequipment was also cleaned and wipe tested. This equipmentincluded the three trailers on which the major components ofthe MIS were mounted, the air pollution monitoring trailer,HEPA trailer, electric generators, Monarch1- CPI separator,cyclone, WEP, air dryer, water softener, four wastewaterstorage tanks, process water storage tank, caustic storagetank, three discharge water holding tanks, and several pumps.

Final MIS closure activities consisted of dismantling theunit and preparing its components for shipment and storage atthe EPA facility in Edison, New jersey. Final Denney Farmclosure activities included disassembly of the buildings andfinal grading of the site. The site was covered with aminimum of one foot of soil and seeded. Closure of the MISand site were certified by an independent professionalengineer registered in the State of Missouri.

S O I L , BUILDING AND EQUIPMENT DECONTAMINATION

The extent of contamination was determined throughpredosure sampling and analysis conducted in November andDecember 1988. Soil samples, samples from various parts ofthe b u i l d i n g s , and samples from the equipment were taken andanalyzed to determine the extent of contamination resultingfrom activities at the site. The samples were analyzed usingapproved SW Methods for dioxins/furans, PCBs, organics, andmetals. The results of the analyses were compared with theaction levels for the site presented in Table 60.Soil Sampling and Decontamination

Sampling was conducted prior to the start of site closureactivities to determine the extent of contamination of thesite s o i l . This sampling and analysis was primarily fordioxin using a statistical procedure to guarantee that thedioxin levels reported were within 95% confidence limits[ 3 1 ] . This means that there is less than a 5% chance that

195

the actual concentration exceeds the maximum concentrationobtained from the statistical analysis of the analyticalresults. In addition, grab samples were taken and analyzedfor dioxin and the other constituents listed in Table 6 0 .The results of this sampling are presented in Tables 61 and6 2 . The sample locations are depicted on Figure 30.

\ The sampling and analysis method for dioxin referencedabove is described below. The site is divided intosections. Each section is divided into 50 equal areas, andthree aliquots are taken from each area. The aliquots takencorrespond to locations 2, 4 , and 5 as shown in Figure 31.The 50 aliquots from location 2 are composited to form onesample. The same is done for the aliquots from location 4and location 5. Therefore, a total of three compositesamples are analyzed. The results of the three compositesamples are combined statistically to arrive at the 95%confidence li m i t for the section (see footnote 1 , Table 6 1 ) .

The preclosure sampling at Oenney Farm for dioxin wasexecuted by dividing the site into 16 sections ofapproximately 5000-ft- areas consisting of 6 sectionsinside the hot zone and 10 sections outside the hot zone asshown in Figure 30. Dioxin contamination was found in thehot zone as expected and was also found in the 10 outsidesections. At the beginning of closure activities in January1989 , the 10 outside sections were divided into 2400-ft'-sections to further delineate the dioxin-contaminated area(Figure 3 2 ) . In addition, another 16 sections outside thehot zone were added during the closure process to determinethe extent of the contamination. The final allocation ofareas with their levels of contamination is shown in Figure32. The areas with dioxin concentrations greater than theaction level were designated as contaminated areas and weretargeted for remediation.

Contaminated soil was scraped in layers of at least threeinches and incinerated. After each scraping, the underlyingsoil was sampled and analyzed for dioxin. Dioxin wasselected as the indicator chemical for the soildecontamination/excavation process due to its prevalence atthe site and the stringent action level for i t . Scraping andincineration continued until sampling and analysis showedthat the contamination of the remaining soil was below theaction level for d i o x i n . Once an area was below the dioxinaction l e v e l , it was sampled and analyzed for the otherconstituents listed on Table 60. Decontaminated areas werecovered temporarily with plastic sheeting to prevent thespread of contamination from contaminated areas unfit theexcavation was completed and the entire site was covered with

196

TABLE 61. INITIAL PRECLOSURE SOIL SAMPLING RESULTS [November 1988]

Section No. Sampling Date 2,3,7,8-TCDD(a) Chromium(b) PCBs(c)(ppb) (ppm) (ppm)

Perimeter Sections(d)

1 SW 11-7-88 7. 6 9 16 1602 SE 11-7-88 1.14 11 N03 NE 11-7-88 5.33 19 N04 NW 11-7-88 5.10 13 ND5 AshStorage 11-7-88 2.94 200 N0

Hot Zone Sections

67891011

SWNWSM-NETrenchNESE

11-7-8811-7-8811-7-8811-7-8811.8-8811-8-88

127.44659.00227.3716.777.756.68

304.78.5

137.8

15

240(e)40(f)16

1901.6

ND

( a ) All 2,3,7,8-TCDD concentrations are at the 95% Upper ConfidenceLimit (UCL):q ' X + 2.92 S/1.731where:C^ » Maximum concentration of contamination at 95% UCL.X = Mean concentration of three composite samples.S " Standard Deviation of three composite samples.

( b ) Chromium is total chromium not EP toxicity chromium. The levelsdetected were considered to be safe.

( c ) PCBs expressed as Aroclor-1260.( d ) SW-southwest, NW-northwest, SE-southeast, NE=northeast.( e ) Also contained 200 ppm tetrachlorobenzene and 30 ppm

hexachlorophene.(f ) Aroclor-1016.

Note: Other organics were detected at low levels (<10 ppm).Action levels: See Table 60.

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TABLE 6 2 . FOLLOW-UP PRECLOSURE SOIL SAMPLINGRESULTS [December 1988]

Sample Type TCDD Concentration fppbl

I . 95X UCL Soil Samples (0 to 2 i n . )

1 . Section 122. Section 133. Section 144. Section 155. Section 16

I I . Depth Samples in Section l ( a )

1 . 0 to 3 i n .2 . 3 to 6 I n .3 . 6 to 9 I n .4. 9 to 12 I n .

14 6 911 610 311 43

10.4 93.003'^ND

I I I . Depth Samples in Section 6 ( a )

1 . 0 to 3 i n .2. 3 to 6 i n .3 . 6 to 9 i n .

1 1 9 . 6 63.213.51

I V . Depth Samples in Section 8 ( a )

1 . 0 to 3 i n .2. 3 to 6 i n .3. 6 to 9 i n .4. 9 to 12 i n .

10.132.010 . 6 71.25

V . Grab Samples in Section 7 (0 to 2 i n . )(10 aliquots each)

1 . Around waste oil containment1. Underneath HEPA duct3. Between MDB-1 and DSB

11.238.23

3798

V I . Wooded Area South of Trailers (0 to 2 i n . )( 5 to 7 aliquots)

1 . Soils south of the site2. Runoff behind trailer n

N D ( b )12.74

( a ) Grab samples( b ) ND • not detected

198

-x-x-x- Hot Zone FenceOSB Drum Storage BuildingMDB-l Hazardous Waste Storage BuildingMDB-2 Hazardous Waste Storage BuildingEWB Equipment Mashdown Building

o Grab Sample Location (See Table 62)

Data = 2,3.7.8-TCDD concentrations

PCB = PCB concentrations

Figure 30. Denney Farm Site Preclosure Sampling ResultsNovember and December 1988

199

50 SOIL SAMPLES COMPOSITED

TO FORM COMPOSITE 2

— y —a • a cs • iii-̂

B

r[̂11

a • c[4]

—(s]——5Hl

^

.(a • [aEl

1

]

^tr\•̂ l-«r—

00

Figure 3 1 . Systematic Sampling Design for Obtainingthe 3 Composite Samples.

200

NorthernArea

0.84 ppb FACILITY LAYOUTMISSOURI FIELD DEMONSTRATION

OF U.S. EPAMOBILE INCINERATION SYSTEM

AT DENNEY FARM SITE

Data = 2 , 3 , 7 , 8 - T C D D concentrations.U = Not detected at 0.300 ppb detection l i m i t .

Figure 32. Final Allocation of Areas With TheirLevels of Dioxin Contamination.

201

clean soil in accordance with the cleanup criteria. Thedioxin concentrations remaining after excavation areindicated in Figure 33.

Buildings and Equipment Sampling and Decontamination

Wipe sampling of the sheet metal wa l l s , concretefoundations, and wood framework of the buildings wasconducted in order to determine the level and extent ofcontamination in the buildings. The metal, wood, andconcrete were each wipe tested separately. Coring samples ofthe foundations were also taken. The methods used aredescribed below.

Wipe samples were taken using 3 - i n . by 3 - i n . sterile v0gauze pads that were soaked with isooctane. The sampling nprocedure consisted of wiping several areas over a designated <̂ j-portion of the building with the gauze so that the total areawiped was 2500 cm'-. The gauze was placed in an 8 oz j a r . ^This procedure was used to collect samples for metals, °organics/PCBs, and 2 , 3 , 7 . 8 - T C D D analyses. 0

Concrete floor dust samples were collected from randomlocations throughout the buildings by using an impact drillwith 1 - i n . carbide tipped bits to obtain dust from the entiredepth of concrete. The dust was composited into three 8-ozjars for metals, organics/PCBs, and 2,3,7.8-TCDD analyses.

Buildings were decontaminated by scrubbing with brushesusing a detergent solution and rinsing with high pressurewater or steam cleaning. This was preceded by scraping whennecessary. The decontamination process was repeated untilsampling and analyses showed that residual contamination wasbelow the action l e v e l s .

All building materials were decontaminated to the actionlevels indicated on Table 60 except for some of the wood.The contaminated wood was fed to the MIS while it was stillin operation. The buildings were all disassembled andremoved from the site. The foundations remained and werecovered with a minimum of one foot of clean s o i l .

All equipment was decontaminated by scrubbing withbrushes using detergent solution, and rinsing with highpressure water or steam cleaning. The process was repeateduntil sampling and analyses showed that the residualcontamination was below the action l e v e l s . It should benoted that although the MIS closure,plan ( 9 ] stipulated anequipment cleanup level of 10 pg/cm2 for d i o x i n , theequipment was cleaned to meet the more stringent cleanuplevel of 1 pg/cm^ indicated in the site closure plan [ 3 2 ] .

202

MorttrmAr««

0.84 ppbFACILITY LAYOUT

MISSOURI FIELD DEMONSTRATIONOF U.S. EPA

MOBILE INCINERATION SYSTEMAT DENMEY FARM SITE

Site covered by a minimum of 1 foot of clean s o i l .Data » 2 , 3 , 7 , 8 - T C D D concentrations.U = Not detected at 0.300 ppb detection l e v e l .

Figure 33 Dioxin Levels at Denney Farm RemainingAfter Excavation and Site Closure.

203

Wastewater generated during the decontamination processwas passed through a filter train consisting of 50 micron and20 micron paper filters, a sand filter, and two activatedcarbon filters. The filters were mounted in series. Thefilter trains were incinerated periodically. All water wasdischarged in accordance with the NPDES permit for the site.

Some contaminated material was generated after theincinerator was shutdown for dismantling. This materialincluded paper filters, carbon filters, sludge fromwastewater tanks, and floor sweepings. This material was putinto marked and sealed drums and sent to a permitted storagefacility.

DISASSEMBLY AND TRANSPDRT OF INCINERATION SYSTEM

The disassembly and transport strategy for the MIScomponents depended upon whether the equipment was rented,trailer-mounted or mounted in other ways. Generally, thedecontaminated components of the MIS were disassembled onlyto the degree that a11 elements could be mounted onover-the-road equipment and transported back to the EPAEdison, New Jersey, facility. The non-rented equipmentrequired a total of 21 trailers for transport. Thedisassembly and transportation strategies are discussedbelow.

The rental equipment, listed above in the closuresummary, was returned to the appropriate vendors after beingrestored to its " a s supplied" condition.

Many of the major components consisting of the k i l n , SCC,MX scrubber, and flue gas analyzers were mounted on seventrailers. Disassembly of the trailer-mounted units wasconducted as follows: The kiln and SCC were destagged. Theequipment was cleaned and painted. The front one third ofthe SCC was removed and placed on another trailer to bringthe SCC trailer within highway weight restrictions. Allservice piping and three-phase cables were disconnected,plugged, capped, and tagged. A11 instrumentation wasprotected and seated. The trailers were inspected, serviced,and prepared for road operation.

The remaining equipment, consisting of the WEP, cyclone,CPI separator, pumps, p i p i n g , hoses, interconnectingelectrical cable, storage tanks, e t c . , were loaded on flatbed trailers after cleaning and disassembly.

The WEP and cyclone required special handling. Theelectrode assemblies were removed and packed in separatecrates and the WEP was filled with styrofoam packing. Thesupport frame of the WEP was modified to allow shipment of

204

the unit within its frame. Cross-beams to which theplatforms were attached were replaced with shorter beams tobring the unit within the permissible shipping clearances.The WEP was loaded on a flat bed trailer and shipped in ahorizontal position. The cyclone also was shipped completelywithin its support frame. Preparation of the cyclone forshipment consisted of removing the spring supports andreplacing them with rigid links. Shims were then weldedbetween the unit and its vertical guides.

The process water system and electrical system weredisassembled and inspected. A11 steel and plastic piping wasscrapped because of reduced wall thickness or internal scalebuildup. Only rubber hoses and trailer-mounted piping forthe process water system was salvaged. A11 electrical cableswere coiled and placed on trailers for shipping. tr\

^A11 remaining equipment was disassembled, placed on -r-

pallets or crated if required and then loaded onto flat bedtrailers for shipment. 0

0LESSONS LEARNED

Several important lessons were learned from this closureexperience that could make future closure operations of thisnature more efficient. These lessons are discussed below.

The hot zone at Oenney Farm was separated from thesurrounding area by a fence, and the buildings holding thehazardous wastes were designed for spill control. However,some materials handling occurred outside the buildingscreating the potential for contamination of hot zone s o i l s .Contamination in the hot zone, which was at a higherelevation than the rest of the s i t e , created the potentialfor contamination to migrate outside the hot zone duringperiods of heavy rainfall. In fact, the spread ofcontamination outside the hot zone boundary was discoveredduring closure. A narrow plume of contaminants migrated outof the hot zone and was carried along by stormwater runoffinto the adjacent wooded area. The discovery of this plumenecessitated additional sampling and analysis work duringclosure to define the area of contamination, as well asadditional remediation work to correct the condition.

Contamination outside of the buildings can be minimizedby confining feed handling to inside the buildings. The useof conveyors to transport the contaminated soil betweenbuildings did reduce handling outside the buildings afterthey were installed in March, 1988. A dike at the fence linewould have been effective in minimizing the spread ofcontamination from the hot zone to the outside.

205

Conducting routine soil sampling in both the hot zone andsafe zone during the operational phase of the fielddemonstration would have been useful to minimizecontamination of the site. Having such a program in placewould have allowed earlier discovery of the soilcontamination. This in turn would have allowed sitepersonnel to remediate the situation and prevent the spreadof contamination beyond the hot zone.

It would have been useful to have had routine wipetesting of the equipment and buildings during the operationalphase of the MIS program. If this had been done, potentialsources of contamination around the MIS and in the personneldecontamination area could have been identified andremediated quickly, and additional contamination of theseareas could have been prevented. This in turn would havehelped simplify final closure operations.

FUTURE OF THE MOBILE INCINERATION SYSTEM

Although the MIS is temporarily being stored at the EPAFacility in Edison, Mew Jersey, plans for its future weremade at the beginning of 1989, when EPA decided to make theunit available to private developers or other federalagencies through the Federal Technology Transfer Act (FTTA)[ 3 2 ] . This law allows EPA to seek a technology partnershipwith a commercial or other governmental organization forfurther development of the system.

A Technology Transfer Program for the MIS was held inMonett, Missouri on March 2 9 , 1989. The presentationconsisted of two identical half-day sessions. The first partof each session presented the FTTA legislation, and technicaland permitting information on the MIS. The second part ofeach session involved a tour of the MIS operation at theDenney Farm site. There were 42 attendees representing 31companies at the program. Interested parties were requestedto submit proposals to EPA stating how they would furtherdevelop the technology and provide financial support for thisdevelopment. Several proposals were received and arecurrently being reviewed by EPA so that a technology partnercan be selected. Anyone interested in more information onthe future of the MIS should contact the Releases ControlBranch of the Risk Reduction Engineering Laboratory at( 2 0 1 ) 321-6635.

206