Fluidized Bed PCB Incineration in Alaska

Harold R. Diot Derrell T. Yoslng

Hmocd R Dht is &rector, sales and marketing at %den Envitonnrental Services, Inc in GarCsb4 C4. %den Environmental provides remediation servjces to ptivate inhcshy and to state and federal agencies. Derrell Z Young is aprolect manager witb tbe same

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OgdenEtwimnmentalSarZcesZnc. (OD) isoperatingaPCBincinera- tionpmjeet 012 the Kenai Peninsula, Alaskra. The facility & appraxrmately 150 milesfrom Anchorage, Alaska, on a US. Fish and WiUlge SavcCe refueandrecreatlonarea.BefollPattaining izscurrentstatus, tbearea was an 0 U ~ U ; ~ I i ~ a n d c o m p r e s s o r ~ a r e s r r U i n thearea. ogden5 facUi~arelocatedadjacenttoanoperatingcompressorsta~ inanarea transected by pipeline. The site became contaminated with PCRs as an indirect result of a compressor explosion in 1972. In March 1988 OES contracted to ?mediate tbe site using rtsproprletary tran.po?fable Circu- lating Bed Combustor (CBC)p an aduanced technology fluidized bed incinerator.

n e p j e c t wUI thermally mat more than 80, OOO tons ofPCB-contami- nuted soil. Treated SOU (ash) contains less than 0.1 ppm PCB and is pennanentlyplaced on site. @den designed, constmcted, m i t t e d , conducted Ma1 bums, and made@& opational th& major facility on the remoteKenaiPeninsula ofAlaska. Allsystems tuere designed to urfthstand the rigors of shipping and to be hr'ghly reliable in cold weather and remote- site operations.

SITE INYESTIGATIONS In 1985 an Order By Consent went into effect at the Kenai Peninsula

site, administered by the US. Fish and Wildlife Service (VSFWS) in coordination with the Bureau of Land Management (BLM) and the Alaska Department of Environmental Conservation (ADEC) and in consultation with the US. Environmental Protection Agency @PA). EPA declined to sign the Order By Consent because, according to its solicitor, doing so might compromise its responsibilities under CERCLA.

Ecology & Environment, Inc. (E&E) was retained to provide environ- mental management support services related to implementation of the Order By Consent. A considerable number of studies, including extensive sampling and analysis, have been completed by E&E to characterize the site, determine the levels of contamination, assess the risks to humans, wildlife, and the rest of the environment, and examine the feasibility of various technologies as required by the Order. The Order originally called for cleanup to 50 ppm or less of PCBS, but due to "No Observable Effects Level" studies by USFWS, lower cleanup levels were imposed. A negotiated Memorandum of Agreement establishing the cleanup level for the site was

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HAROLD R. Drm DERRELL T. YOUNG

Theprimary advantages of thermul treatment include compkte destruction of the waste material with subsequently reduced long-term liability.

approved by the USFWS, BLM, and the ADEC with the concurrence of EPA on November 14, 1986. A FCB cleanup level of 12 ppm was established, except in areas with difficult access and low risk where a level of 24 ppm was imposed.

FeaSU>mty Stucfy A feasibility study of the alternatives available for mitigating PCB

contamination was conducted, and six remedial alternatives were selected for consideration at the site. Five of these alternatives involved on-site thermal treatment. The primary advantages of thermal treatment include complete destruction of the waste material with subsequently reduced long-term liability. It was highly udikely that the USFWS would have accepted alternatives involving on-site landfilling, solidification, or in-situ vitrifcation since the site is a wildlife refuge.

Mitigation Plan A Mitigation and Restoration Plan was prepared to meet the stipulations

in the Order By Consent. The overall goal of the PCB-mitigation program at the site is to protect the integrity of the wildlife populations and other natural resources of the site and the National Wildlife Refuge. In addition, public health and welfare, including the safety of workers on the lease, is addressed in the proposed mitigation measures. The specific objectives of this plan are summarized below:

Establish dishibution of PCB contamination wquirfng mitigation - The methodology employed in interpreting analytical results and mapping areas that exceed the established cleanup level were presented. Desc?ibe methodology for mwgation - A brief description of the excavation and the on-site thermal treatment technology to be implemented for the PCB mitigation was provided. The rationale employed in selecting this method as well as a general overview of the anticipated work plan was included. Verification ofsamplingprogram- Verification procedures to ensure compliance with the established cleanup level were presented. Release sampling, analytical protocols, and On-scene Coordinator (OSC) approval processes were discussed in detail. Establish schedule - A tentative schedule for implementing the mitigation and restoration program was presented.

Contamination Delineatton andverfffcation Sampling An on-site analytical laboratory was established to delineate areas of

contamination and verify the effectiveness of remediation. Significant c a t savings were realized compared to what off-site laboratory analyses would have cost. The on-site laboratory provided rapid turn-around in analytical results, which minimized excavation down time, eliminated sample shipping costs, and provided for some economies of scale.

PLUIDI~~D BED PCB INCINERATION M ALASXA

The CBC system is an advanced technology flu id ized- bed combustor that uses high-velocity air to entrain circulating solids in a highly turbulent combustion loop.

Facility Operations Ogden is conducting extensive excavation in and around contami-

nated buildings and other facility structures. Because the pipeline gas compressor station still functions, much of this work is conducted on operational natural gas pipelines and equipment. Activities at the site include the following:

Excavation of PCB-contaminated soils from around pipeways, both buried and lying on the surface. The work is complex because functioning lines are under pressure and flow, requiring a significant level of care and planning during excavation. Excavation within sheds for functioning equipment. This work includes excavating contaminated soils from around equipment pads, foundations, and pipeways within the structures.

Potential human exposure to PCBS from contaminated soils is by direct contact, ingestion, or inhalation. Data collected to date at the site indicate that PCB levels identified on the roads and other areas do not appear to present a significant hazard to humans. Workers involved with PCB remediation activities work in protective gear since they have the potential for direct contact with the contaminated soils. Health and safety personnel are on-site during the remediation project monitoring personnel exposure.

CIRCULATING BED COMBUSTOR APPLICATKON TO PCB OFS provides turn-key services in fmed waste treatment facilities such

as off-site regional facilities or on-site facilities. These are fured, permanent facilities. OES also provides turn-key services in transportable waste treatment facilities for on-site remediation. The PCB remediation project on the Kenai Peninsula is in this latter category; when the project is completed in 1991, the unit will be demobilized, the site restored, and the unit shipped to another remediation project site.

CBC Technology The CBC system is an advanced technology fluidized-bed combustor

that uses high-velocity air to entrain circulating solids in a highly turbulent combustion loop. It uses the "3 T's" of combustion-time, temperature, and turbulence-in a most efficient combination. Figure 1 shows the configuration of a typical CBC system.

Solid waste feed is introduced at an inlet located between the cyclone and the combustion chamber, where it is immediately swept into the lower end of the combustion chamber. Limestone solids are co-fed with the solid feed. In this case, the solid waste feed is PCB-contaminated site wastes such as soils, plastic, and tyvec suits.

The high-combustion air velocity and circulating soils and limestone solids result in a uniform temperature around the combustion loop (combustion chamber, cyclone, and solids return leg). The circulation produces rapid heating of the feed and highly efficient combustion and

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HAROLD R D I ~ DERRELL T. YOUNG

Figure 1. Schematic Flow Diagram of the CBC

COMBUSTION CHAMBER n 191

EOOLJNG WATER

A& CONVEYOR SISTEM

reaction. This eliminates the need for afterburners or wet scrubbers. During combustion, ash is periodically removed from the CBC and

cooled. The hot gas leaving the cyclone passes through a flue gas cooler, and small particulates discharged from the cyclone are collected in fabric filter baghouses before exiting through the exhaust stack.

Auxiliary fuel is used to maintain temperature in the CBC during start- up and operations with soil-type feeds. Natural gas is readily available and thus is the auxiliary fuel at the site.

The transportable CBC consists of seven steel modules, which contain the process equipment and provide the structural framework of the CBC. The modules do not exceed measurements and weights suitable for single- drop trailer transport. Special transportation permits are not required.

Costs Prices for incineration, using the OES Circulating Bed Combustor, are

based on such factors as the quantity of material to be treated, moisture, and organic content of the contaminants. Ranges of cost per ton are $150/ ton to $300/ton for quantities of 20,000 to 50,000 tons and $350/ton to $400/ton for quantities of 10,000 to 15,000 tons. These prices are for incineration only and do not include excavation.

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FLmm BED PCB INCINXUTION IN Aumu

Figure 2. PCB Remediation Project Status

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fOUYMENl L f r t l l n Y O M I l ~ T l O U

Incineration Phase Overdew and status Figure 2 shows a schedule representing the overview of work

accomplished to date. The contract for the PCB cleanup was signed March 31,1988, and it covered an initial 45,000 tons. Mobilization of personnel and equipment to the site along with excavation and CBC site preparation occurred between April and June 1988. The CBC modules were trans- ported from fabrication facilities in Louisiana to the site, and installation was completed between late-July and mid-August. Shakedown of the CBC and feed and ash handling equipment was done between mid-August and mid-September. The Demonstration Test officially started on September 22,1989, and lasted until September 26,1989. With the completion of the DemonstrationTest, a one-week down period was used for inspection and planning for start of Interim Operations on soil contaminated at levels of less than 50 ppm PCBs. Interim Operations were made possible by a permit granted by EPA Region X and by ADEC based on operation within the boundaries of previous CBC demonstration tests and permits. EPA and ADEC monitored the operations in both weekly and quarterly report requirements and in more than 50 on-site inspections.

OES has made equipment and facility modifications in the feed preparation and ash handling areas. These modifications were required due to a greater-than-expected quantity of fine silt in the excavated soils. These modifications were not involved in the fundamental CBC process parameters, and thus have been reviewed as minor modifications by the

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HAROLD R D I ~ T DERKF~LL T. YOUNG

agencies. The modifications will allow greater feed and ash handling flexibility than originally designed for this site.

The Toxic Substances Control Act CECA) permit for operation of the CBC on soils contaminated at levels above 50 ppm was received in early June. This permit analysis of required the demonstration test data, reporting and evaluation, and public meetings and public hearings on the project and on the demonstration test results.

Once the TSCA permit was approved, TSCA operations began on all site soils and miscellaneous material. With the discovery of additional contaminated soil, more than 80,000 tons of soil will be purified by the CBC, encompassing approximately 2 years of operation. By mid-April 1990, Ogden had processed more that 32,700 tons of soil.

Project Permits and Approvals Permitting the first transportable hazardous waste incinerator in the

state of Alaska deserves a separate article in itself. This process, which

Table 1. Permits and Approvals

EPA Public Participation

ADEC Transportable Air Quality Permit Alaska Coastal Zone Consistency Review EPA TSCA Transportable PCB Permit

ADEC Tran.@ortabk Air Quality Permit. This permit from the state agency controls not only the criteria pollutants, but has also controlled operations criteria for the CBC using parameters and guidance from EPA.

Alaska CoastalZoneConsistencyRarlau.This process ensuredthat all required information and agencies had been involved in the permitting process and that our operations were consistent with the criteria estab- lished for the Alaska coastal zone.

P A Traqbombk PCBPmit . This permit involved submission and approved of the Demonstration Test Plan, and a demonstration test operation monitored on-site by EPA. The resulting audited sampling and analysis led to a report and agency reviews. A draft permit based on EPA and ADEC review of the demonstration test was then offered for public and interagency review and comment.

EPAPublic PaMclfation. A formal public review and hearing process was involved in the approval of the permit under the bounds established in the demonstration test. EPA and ADEC have fdized the permit and the public responsiveness summary. The final permits were issued in early June 1989.

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pLuIDrza~ BED PCB INCINERATION IN

Permitting the first tramportab le haxardous waste incinerator in the state of Alaska deserves a separate article in itself.

involved months of work, was founded on the CBC's earlier TSCA permit gained in 1985. Also, there have been numerous public presentations and meetings on this project site involving many agency personnel from USFWS, the lead agency on the cleanup on the wildlife refuge; the Bureau of Land Management; EPA Region X (Anchorage and Seattle); EPA TSCA (Washington D.C.); and ADEC (Juneau, Anchorage, and Soldotna).

We will give only a brief overview of some of the key permits and approvals shown in Table 1.

Demonstration Test The demonstration test of the CBC was conducted between September

22 and September 26, 1988. This test operation used site soils known to have the highest levels of PCB contamination on this site. The test was the first operation of this transportable CBC on contaminated material and was monitored continuously by EPA, ADEC, and USFWS personnel on-site.

The test was planned to demonstrate two basic operating conditions in the CBC: 1600'F and 1700OF. (Note that past CBC demonstration tests proved 1800° F to be effective in the required PCB destruction.) Under the TSCA criteria, three identical tests were run at each condition.

Table 2 and Table 3 show results of these tests versus permit require- ments. Table I1 shows that the key criteria of Destruction Removal Efficiency (DRE%) >99.9999%. This requirement was met in all three tests at 1700OF and all three tests at 1600'~. Particulate emissions measured at the stack averaged 0.012 grain per dry standard cubic foot of stack gas compared ta a permit requirement of 0.05. Acid gas emissions averaged

Table 2. Demonstration Test Results Averaged Performance Parameters

PARTXCULATES LB/HR GRAINDSCF ACID GAS

DRE AT 7% 0, (HCL)

CONDITION 1 (1,600 F) TEST 1, 2, 3 >99.9999?? 0.008

CONDITION 2 (1,700 F) TEST 4, 5 , 6 >99.9999?? 0.016

PERMIT REQUIREMENTS 199.9999?/6 c0.05

1.3

1.4

S4.0

Destruction Removal Efficiency Where: W,, = PCB Fed Wow = PCB Emitted

% DRE =(WIN - W,, / WIJ X 100

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HAROLD R Drm DERRE~~L T. YOUNG

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Table 3. Demonstration Test Results Averaged Performance Parameters

co HYDRO- COMBUSTION ASH PCB EMISSIONS CARBONS EFFICIENCY' @PM)

CONDrnON 1 (1,600 F) e 20 1-3 > 99.9% c 0.009 TEST 1, 2, 3

CO"XON 2 (1,700 F) c 20 1-3 9 9 9 % C 0.014 TEST 4, 5 , 6

PERMlT REQUIREMENTS 190 PPM 299.90h e.000

0/6 COMBUSTION mramcy = KO, / co, + COI x 100

below 1.4 pounds per hour versus the 4.0 pounds per hour requirement. Table 3 shows that CO emissions were less than 20 ppm versus the less

than 90 ppm requirement. Unburned hydrocarbons were less than 3 pprn. Combustion efficiencywas overthe 99.9% requirement. PCB content in the ash was less than 0.014 ppm versus the less than 2.000 ppm requirement.

Hence, the CBC performance was typically orders of magnitude better than the requirements in the permits.

Site Layout Figure 3 shows a sketch of the site layout. Key features are: 1.

3&4. 5&6.

7.

8.

9.

10.

On-site laboratoty. The lab is EPAaudited and analyzes soils fed to the CBC and purified soils or ash discharged from the CJ3C The lab also assists in daily health and safety monitoring, and in teated water analysis. @den o m e and c o n f m e t r a i h . Health and Safety o&e andpersonnel safety fmilities. Decon- tamination showers and other necessary facilities are housed in this area, which is the key point of personnel entry and egress for the feed preparation building. Feed preparatton buikding. The soils and miscellaneous con- taminated site materials are prepared for feeding to the CBC. CBC Includes all required feed handling, thermal destruction and ash handling facilities. Control Room. Operations and control center from which the CBC is controlled and where process data are recorded in the process control unit. Powergeneration station. The site generates its own power and is completely self-contained.

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Excavatbn Activities Excavation activities have been divided into subtasks involving a

variety of excavation approaches. Standard excavation methods using backhoes, front-end loaders, and motor graders were employed in the more open areas to remove zones of PCEcontaminated soils. Dump trucks were then used to transport the material to a lined and bermed containment faciIity at the site. The materid was weighed prior to placement in the containment facility. The nonactive areas at the containment facility are covered with liner. "Hot lines" were established at the various excavation sites, and, where possible, trucks transporting the contaminated material remained outside of exclusion zones. If this was not possible, remote truck decontamination stations were established at the excavation site. Harsh weather conditions limited excavation generally to a period between May and October.

A few of the excavation sites required special handling and precautions during excavation. The compressor plant, site of the original explosion and PCB release, is still operational and will remain so during excavation activities. The plant compresses gas produced during oil recovery. The gas is then reinducted into the oil reservoir to maintain pressures required for oil recovery. The compressor plant is essential for continued operation of the oil field.

SUMMARY The PCB remediation at the site has shown that over 80,000 tons of

PCB-contaminated soil can be safely excavated and isolated in bermed and lined holding stockpiles. We have demonstrated that a transportable CBC can be quickly installed and operated and successfully qualified for PCB destruction. We have also shown the successful routine operation of the entire facility over several months of operation.

This has been done with several firsts and unique challenges. To list a few:

First application of a hazardous waste incinerator in Alaska First transportable CBC in Alaska First Interim Operations Permit for less than 50 ppm operations Awarded generic TSCA permit for PCB destruction in all EPA regions Record breaking cold (-40OF ambient temperatures and -90°F wind chill factor)

The CBC cleanup of the site is safe and the best environmental solution. On-site thermal destruction is an environmentally sound and permanent solution as well as consistent with EPA policy of "Complete Destruction of Contamination On-site." Long-term liabilities are eliminated, and the risks associated with transportation of larger volumes over land and water are avoided.

CBC safety in both operation and emissions has been proven in past work and reconfirmed in this project. The safety is assured by continuous

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monitoring. CEK on-site remediation destroys the hazards where they are and avoids off-site transport hazards and liabilities. Once the CBC work is completed, the facilities will be relocated and the site restored. EB

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