ARCADIS LETTER RE: REVISION TO DESIGN PLAN, REMEDIATION … · Services, Inc. detailing the proposed thermal oxidizer to be used with the LTTD unit for effluent air treatment. Details

EPA Region 5 Records Ctr.

229194

ARCADIS GERAGHTY&MILLER

Scott HansenU.S. Environmental Protection Agency, Region V77 West Jackson Boulevard (HSRM-6J)Chicago, Illinois 60604

Subject:

Requested Revision to Design Plan, Remediation of Waste Disposal Area 2,Lakeland Disposal Landfill, Claypool, Indiana.ARCADIS Geraghty & Miller Project No. WI000765.0001

ARCADIS Geraghty & Miller, Inc.

126 North Jefferson Street

Suite 400

Milwaukee

Wisconsin 53202

Tel 414 276 7742

Fax 414 276 7603

ENVIRONMENTAL

Dear Mr. Hansen:

This letter serves to document our recent telephone conversations regardingalternative effluent air treatment options for the low-temperature thermal desorption(LTTD) unit located at the Lakeland Disposal Landfill site in Claypool, Indiana. Asyou are aware, the vapor-phase activated carbon air treatment units utilized for theinitial 3,837 tons of soil treatment activities did not provide a cost-effective andreliable means for air treatment. Based on SUMMA canister influent and effluentair sampling, it was determined that the carbon usage rates were much higher thananticipated, resulting in frequent shutdowns to facilitate replacement of the carbon.

Following the initial two carbon change outs, the LTTD unit continuous emissionmonitor (CEM) registered a sustained total hydrocarbon reading in excess of theallowable limit on October 18, 2000, indicating that the carbon was spent afterapproximately 2 days of treatment activities. It is believed that this conditionresulted from a higher concentration of lighter-weight organic compounds (whichhave low carbon adsorption rates) than what was seen during the first portion of theLTTD project. The LTTD unit was subsequently shut down until an alternativeprocedure could be determined that would provide efficient and effective treatmentof the effluent air stream.

It was subsequently determined that thermal oxidation would provide effectivetreatment of the LTTD unit effluent air stream. ARCADIS Geraghty & Miller, Inc.,on behalf of the Lakeland Disposal Respondents, is requesting United StatesEnvironmental Protection Agency (USEPA) and Indiana Department ofEnvironmental Quality (IDEM) approval to modify the LTTD unit to replace thevapor-phase carbon beds with a thermal oxidizer for effluent air treatment.

Preliminary discussions with IDEM have indicated that this would be an acceptableoption. However, IDEM requested that the effluent air sampling include carbonmonoxide (CO) and nitrogen oxide (NOx) monitoring to ensure that the allowable

Milwaukee, Wisconsin

2 November 2000

Contact:

Richard Studebaker, Jr.

Phone:

(414)276-7742

g1 \aproject\dy kmagos\wi0765Vem_action\corr\desmod5.doc11/2/008.15.07 AM

Scott Hansen

ARCADISGERAGHTY&MILLER 2 November 2000

limit of 250 tons per year for these constituents is maintained throughout thetreatment activities.

Enclosed for your review is a copy of a letter from Williams EnvironmentalServices, Inc. detailing the proposed thermal oxidizer to be used with the LTTD unitfor effluent air treatment. Details on the technical specifications, operatingparameters, and estimated discharge concentrations for the thermal oxidizer, thetreatment unit configuration, and the effluent monitoring plan are provided in theenclosed package.

Please review the enclosed information and provide a response to this request assoon as possible to facilitate completion of the remediation of Waste Disposal Area2. Following receipt of approval from USEPA and IDEM, the thermal oxidizing unitcan be mobilized to the site and erected in approximately 7 to 10 working days.

If you have any questions, or require any further information, please contact either ofthe undersigned.

Sincerely,

ARCADIS Geraghty & Miller, Inc.* *-' •*

Rich#d L. Studebaker, Jr.Project Engineer

Michael S. Maierle, P.E.Principal Engineer

Copies:J. Huxhold - IDEMS. Labunski - TetratechD. Tripp - Dykema GossettG. Gilezan - Dykema GossettA. Aguwa - AESB.Lang-UTCM. Fieri - Williams

Page:g:\aproject\dykmagos\wi0765\rem_action\corr\desmod5.doc _ ._11/2/008:1507 AM 2.12.

EnviRonmenTnL SERVICES, inc.

October 24, 2000

Mr. Ric StudebakerARCADIS Geraghty & Miller, Inc.126 N. Jefferson StreetSuite 400Milwaukee, Wisconsin 53202

Subject: Remediation of Waste Disposal Area 2Lakeland Disposal LandfillClaypool, IndianaTransmittal No.: 46No. of Pages: 4

Re: Continued Soil Treatment Operations utilizing a Thermal OxidizerWilliams Project No.: 04301000

Dear Ric:

As you are aware, Williams Environmental Services, Inc. (Williams) ceasedoperations at the Lakeland Disposal Landfill (LDL) site on October 18, 2000 dueto elevated concentrations of total hydrocarbons (THC) in the stack gas.Following the AWFSO for the rolling average THC in excess of 107 ppm, theinstantaneous THC reading remained in excess of 100 ppm for over 20 minutes,while no soil was being fed to the unit. One hour after operations stopped, theinstantaneous THC reading remained at 19 ppm. Based on this data, it wasdetermined that the carbon beds were spent after less than two days of treatmentwith the new carbon. ARCADIS Geraghty & Miller (AG&M) subsequently shutdown operations after conversations with Williams and US Filter/Westates,during which it was determined that resumption of operations with the current unitconfiguration was not a reasonable alternative. Therefore, Williams suggestedthe use of a thermal oxidizer to treat the off-gas from the baghouse. As youdiscussed with IDEM, this proposal has received preliminary approval fromIDEM, pending submittal of additional information regarding the proposedchanges. This correspondence serves to provide the additional informationrequested by IDEM, as outlined below.

1. The specifications for the proposed thermal oxidizer.2. The configuration of the proposed thermal oxidizer.3. The proposed treatment of off-gases from the LTTD unit (e.g., the anticipated

concentrations of contaminants in the gas entering and exiting the oxidizer).4. The continued measurement of THC.5. The measurement of CO and NOX.

A Williams Group International, Inc. Company2075 West Park Place Stone Mountain, Georgia 30087 770/879-4107 FAX: 770/879-4831

Mr. Ric StudebakerOctober 24, 2000Page Two

1. The specifications of the proposed thermal oxidizer.

As previously transmitted to AG&M, the specifications of the proposed thermaloxidizer are as follows:

Thermal Oxidizer (TO-1)Drum Dimensions

VolumeCross-sectional Velocity

10' diameter x 42' long2,900 cubic feet

20.2 feet per secondThermal Oxidizer Burner (B-2)

ManufacturerCapacity

FuelBlower

Eclipse Vortometric55 MM BTU/hour

PropaneChicago 24.5" ID, 25 hp, 1 1 ,000 cfm

Additional information is provided in the attached Process Description andDesign. Williams started with Section 5 of the Work Plan and mademodifications accordingly to reflect the use of the thermal oxidizer instead of thecurrent configuration. Provided with the process description are a revisedprocess flow diagram and equipment layout.

2. The configuration of the proposed thermal oxidizer.

The attached Process Description contains several figures delineating theproposed changes to the thermal treatment unit to incorporate the thermaloxidizer. Essentially, Williams plans to remove all equipment after the baghouse(i.e., quench, air mix chamber, reheater, and carbon beds) and replace it with thethermal oxidizer.

3. The proposed treatment of off-gases from the LTTD unit (e.g., theanticipated concentrations of contaminants in the gas entering andexiting the oxidizer).

The proposed treatment of off-gases is described in the revised ProcessDescription. After removal of particulates, the gas stream enters the thermaloxidizer, where the oxidation of the volatile organic compounds occurs. Theoxidation efficiency of the organics depends on the temperature inside thethermal oxidizer, the turbulence of the gases, and the retention time of the gasesinside the thermal oxidizer chamber. The chamber is sized to provide sufficientretention time (> 2 seconds) at 1,500°F and has an Eclipse Vortometric burner to

Lake046

Mr. Ric StudebakerOctober 24, 2000Page Three

provide the temperature and turbulence required to oxidize the organics. Afterthe organics have been oxidized, the clean gases are passed through the stackto the atmosphere. The clean stack gases will be monitored using a continuousemissions monitoring (GEM) system equipped with total hydrocarbons monitor.

Based upon the previous SUMMA canister sampling data, as well as additionalsampling data available to Williams, it is anticipated that the averageconcentration of contaminants in the gas stream to the oxidizer will be 600 - 800ppm. At the proposed oxidizer operating temperature of 1,500°F, it is anticipatedthat a 99% or greater destruction of the VOCs will be achieved (i.e., 6-8 ppm inthe off-gas). As noted above, the actual destruction efficiency depends on thetemperature inside the thermal oxidizer, the turbulence of the gases, and theretention time of the gases inside the thermal oxidizer chamber.

4. The continued measurement of THC.

Williams will continue to utilize its THC GEM to report the concentration of THC inthe stack. Furthermore, Williams will eliminate the AWFSO for high THC rollingaverage and replace it with an AWFSO for THC in excess of 100 ppm based oninstantaneous values. Williams will also continue to calculate daily VOCemissions based on the average THC readings.

5. The measurement of CO and NOX.

As per AG&M's initial conversations with IDEM, Williams will monitor emissionsof CO and NOX to ensure compliance with the limits of 250 tons per year. | ,-Emissions of CO will be determined from the SUMMA canister collected at the -f- |\ //stack, whereas NOX emissions will likely be monitored with a CEM during the /^next SUMMA test. Both results will be reported along with the VOC results from ^the SUMMA canister to ensure that the oxidizer is operating efficiently and thatWilliams is not in danger of exceeding the VOC emission limit of 10 tons peryear. Furthermore, Williams would propose eliminating the inlet SUMMA canisterduring subsequent testing activities. The purpose of the inlet sample was toprovide an indication of remaining carbon bed capacity (i.e., was the carbonspent). Since it is now proposed to eliminate the carbon beds, the outlet sampleresults will be sufficient to determine the effectiveness of the thermal oxidizer.

Lake046

Mr. Ric StudebakerOctober 24, 2000Page Four

The cost of the proposed changes described above will be provided as aseparate transmittal. In the meantime, should you have any questions regardingthe thermal oxidizer, please contact me at (770) 879-4107.

Sincerely,

WILLIAMS ENVIRONMENTAL SERVICES, INC.

Greg WhetstoneSenior Project EngineerGTW:pc

Attachmentcc: Z. Lowell Taylor

Mark A. FieriMark FriarDearl TateJob File 04301000

Lake046

Section 5

Process Description and Design

5.1 PROCESS DESCRIPTION OVERVIEW

The process described in this section employs Williams' LTTD treatment systemas discussed in Sections 5.2 and 5.3. First, Williams will excavate andprecondition the contaminated soils (size reduction and screening) as describedin Section 5.3.1. Williams will then utilize a rotary dryer thermal desorber (TD-1)to volatilize moisture and organics contained in the excavated soil. The off-gasesfrom the desorber will then be treated in the baghouse (BH-1) to removeparticulate matter. Following the baghouse, a thermal oxidizer will be used toremove organics in the gas stream prior to the off-gas exiting to the atmospherevia the stack.

The process will treat soils to an exit temperature capable of volatilizing thehazardous organic constituents in the soil and achieving cleanup levels asoutlined in Table 5.1. A process flow diagram complete with the anticipated heatand material balance is provided in Figure 5.1. Williams anticipates a thermaldesorber operating temperature of less than SOOT and a thermal oxidizeroperating temperature of 1,500°F at a feed rate of 17 tons per hour and 15%moisture content.

5.1.1 Feed Processing

The feed material for this project consists of soil that will be excavated fromWaste Disposal Area 2 and staged in an area designated for pre-treatmentstorage. Pre-conditioning of the contaminated soils will be as discussed inSection 5.3.1. The conditioned soil will be transported from the storage areadirectly to the LTTD operations area (refer to the Site Layout, Figure 7.1).-^fhesoil will be removed from the feed stockpile with a front-end loader and deliveredto the feed metering unit (FU-1) where it will be placed into a feed hopper. Anapron feeder will move the soil from the hopper to a belt conveyor (C-i) whichwill elevate the soil to the slinger belt at the entrance to the desorber. The speedof the apron feeder is regulated from the control room (0 - 20 tons per hour) andused to set the soil feed rate to the thermal desorber at approximately 17 tonsper hour. The feed belt contains a load cell for the continuous weighing of thefeed soils. The instantaneous and cumulative weights are displayed in thecontrol room.

Treated soil exits the thermal desorber via the discharge auger (C-2). Followingthe discharge auger, a stacking conveyor (C-5) produces stockpiles that areanalyzed by the Engineer for the contaminants of concern. Collection andanalysis of the samples will be in accordance with the Standard Operating

1REVISED PROCESS DESCRIPTIONLAKELAND DISPOSAL LANDFILLWILLIAMS PROJECT NO.: 04301000

DRY GAS LB/HR

DRY SOUDS LB/HR

THERMAL CAPACrTY MM BTU/HR

N2 LB/HR

02 LB/HR

C02 LB/HR

H20 LB/HRFUEL USAGE LB/HR

TEMPERATURE ' F

TOTAL MASS SOLID LB/HR

TOTAL GAS MASS LB/HR

TOTAL GAS VOLUME ACFM

WASTEFEED

28.900

5,100

50

34.000

TREATEDSOIL

24.565

800

DESORBERBURNER

20.419

14

15.661

4.758

654

50

21,073

4.391

DESORBEROFFGAS

20.003

15.661

2.379

1.963

9.544

250

29,546

10,435

OXUMZERBURNER

26.449

28

19.297

5,862

1,290

50

26,449

5.411

OXKXZEROFFGAS

44.341

34.958

3.551

5,832

11,654

1.500

55,995

50.996

INFLUENT

2.500

50

TREATEDWATER

6.570

50

CITYWATER

4,070

50

COMPRESSEDAIR

INDUCED DRAFT (F-1)FAN DAMPER

3AGHOUSE

(BH-1)

THERMALOXIOCERBURNER(B-2)

THERMAL OXIDIZERCTO-D

EMERGENCYHAIR INTAKEffl OFF-SITE DISPOSAL

(AS REQUIRED)

SCREWCONVEYOR

(C-3)SURFACE RUNOFF

WASTEWATERTREATMENT

THERMALDESORBERAIR DAMPER

THERDESORBER

(TD-1)

LEGEND

DIRTY GAS

WATER

FUEL

CLEAN GAS

MATERIAL FLOW

COMBUSTION AIR

FEEDPREPARATION

ASH PRODUCTBELT CONVEYOR

(C-S)

OVERSIZED MATERIAL

CONTAMMATED SOLFROM EXCAVATION

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1°O Q-

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10/23/00

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5.1

Procedures developed by the Engineer and provided under separate cover. If anoriginal treated soil sample fails to meet the cleanup criteria for the site, and theQA/QC results are within the acceptable ranges, then Williams will recycle thefailed soil stockpile to the feed pad for further treatment. This "recycled" feed willnot necessarily be stored separately from the "virgin" feed, but documentationwill be kept of the amounts of "virgin" feed processed versus "recycled" feedprocessed. If, however, the laboratory report indicates difficulties in the analysisof a failed soil sample, or the QA/QC data falls outside of acceptable ranges, asecond sample from the treated soil stockpile will be collected to verifycontaminant concentrations prior to re-processing the soil.

Table 5.1Treated Soil Performance Standards

AnalyteMethylene Chloride

Acetone1,1-Dichloroethene1,1-Dichloroethane

trans-1 ,2-Dichloroethylene2-Butanone (MEK)

1 ,1 ,1-TrichloroethaneBenzene

4-methyl-2-pentanone (MIBK)Tetrachloroethene

TolueneEthyl Benzene

Xylenescis-1 ,2-Dichloroethylene

TrichloroetheneNaphthalene

2-MethylnaphthaleneDiethylphthalate

N-NitrosodiphenylamineDi-n-butylphthalate

Butylbenzylphthalatebis(2-ethylhexyl)phthalate

Vinyl Chloride

Performance Standard (mg/kg)7.8317.21.061.1030.0 |.6i10.21.961.14

26.021.1410.010.019.81.096.0

0.570.150.050.230.483.680.134.0

REVISED PROCESS DESCRIPTIONLAKELAND DISPOSAL LANDFILLWILLIAMS PROJECT NO.: 04301000

5.1.2 Soil Treatment

A countercurrent thermal desorber is used to volatilize the moisture and organicconstituents from the soil. The desorber has internal flights for lifting andshowering the soils through the hot gas stream to ensure intimate contactbetween the soils and desorbed gases. The soils enter the desorber at the sameend where the exhaust gases leave. The exit gas temperature will be maintainedat less than 475°F in order to protect the baghouse. The actual gas exittemperature is dependent upon several factors, including soil characteristics, thedesorber operating temperature, and the ID fan draft, and will be determinedbased on optimum unit performance. While the soil passes through thedesorber, the soil temperature initially rises to 212°F as water is removed. Afterthe moisture has been removed, the soils move toward the discharge end of thedesorber where the soil temperature increases to the desired temperature. Forthis project, an initial soil exit temperature of 800°F has been selected. Sincecountercurrent flow is utilized, high exit soil temperatures can be readilyobtained.

The treated soils exit from the rotary dryer and are combined with the baghousedust in the treated soil discharge screw conveyor, providing a means ofsecondary treatment for the dust. Water is added via nozzles in the dischargeauger to cool the soil and provide suppression of fugitive dust. Negativepressure is maintained on the discharge conveyor through the rotary dryerbreaching to capture the steam generated from moisturizing the soil. Thetreated, conditioned soil discharges from the screw conveyor to a belt conveyorfor stacking. The treated soils are removed from the stacking area by a front-endloader to the verification holding area for subsequent analyses in accordancewith the Engineer's SOP for soil sampling. After meeting the clean-up goals, thetreated soils will be used as backfill on-site.

Heated air is provided to the desorber by a propane fired burner (B-1). Thisburner is located away from the desorber so that no direct oxidizing flame comesin contact with the soils. Combustion air for the burner is provided by a separateblower, but the overall draft is maintained by an induced draft (ID) fan locatedafter the baghouse. The pressure at the burner end of the desorber is monitoredand the ID fan damper is regulated to maintain a negative pressure inside thedesorber at all times.

5.1.3 Gas Cleaning

The gas stream leaving the desorber contains particulates, moisture, andvolatilized organics. This stream must be treated to remove the particulate andorganic matter in order to achieve the required air emission standards before thegas is discharged to the atmosphere. A baghouse dust collector and thermaloxidizer will be used to provide the necessary off-gas treatment.


The baghouse utilizes a pulse jet type cleaning system. A maximum design air-to-cloth ratio of 5:1 is provided. The polyimide bag material (P-84) providesexcellent removal efficiency (>99%) for particulates and has a maximumcontinuous operating temperature of SOOT.

The air from the desorber enters the baghouse at temperatures below 475°F.After passing through the filter bags, the particulate free gas exits the baghouseat about 400°F. The baghouse dust is removed from the baghouse hoppers by ascrew conveyor which discharges into the dust transfer conveyor (C-4) fortransfer to the treated soil discharge screw conveyor at the hot end of the dryer.

After removal of particulates, the gas stream enters the thermal oxidizer, wherethe oxidation of the volatile organic compounds occurs. The oxidation efficiencyof the organics depends on the temperature inside the thermal oxidizer, theturbulence of the gases, and the retention time of the gases inside the thermaloxidizer chamber. The chamber is sized to provide sufficient retention time (> 2seconds) at 1,500°F and has an Eclipse Vortometric burner to provide thetemperature and turbulence required to oxidize the organics. After the organicshave been oxidized, the clean gases are passed through the stack to theatmosphere. The clean stack gases will be monitored using a continuousemissions monitoring (CEM) system equipped with total hydrocarbons monitor.

5.1.4 Water Treatment System

Water treatment operations at the Lakeland site are designed to cover allactivities related to the treatment of water and wastewater. The waters to betreated primarily include surface runoff and decontamination water. Furtherdetails pertaining to the water treatment system are provided in Section 12,Water Management Plan.

5.2 EQUIPMENT DESCRIPTION OVERVIEW

The process equipment for the Lakeland project is configured for four (4) primaryequipment assemblies, plus the auxiliary material handling and fuel storage units.The composition of each assembly is defined below.

• The thermal desorber unit, which includes the rotary dryer (TD-1), feed belt(C-1), and thermal desorber burner (B-1).

• The baghouse unit, which includes the baghouse dust collector (BH-1),baghouse discharge conveyor (C-3), and dust transfer conveyor (C-4).Auxiliary equipment includes air compressors.

• The thermal oxidizer unit, which includes the thermal oxidizer and thermaloxidizer burner.

• The control house, which includes the control panel, data logger, PLC, CPU,and CEM analyzers. In addition, the motor control center and a smallworkshop area are contained in this trailer.


• Auxiliary material handling equipment includes the feed processing unit (FU-1), discharge screw conveyor (C-2), and stacking conveyor (C-5). Othertrailer shipments include the decontamination and tool trailers, the stack,ducting, and earth moving equipment.

5.3 EQUIPMENT DESCRIPTION

The low temperature thermal desorption treatment system consists of a feedprocessing unit, thermal desorber, auxiliary air intake, baghouse, induced draftfan, thermal oxidizer, burner systems, control trailer, and soil feeding system.The air pollution control system is comprised of the baghouse for removal ofparticulates and the thermal oxidizer for destruction of organics in the off-gasstream. The system is designed to accommodate a variety of feed conditions,but nominally operates at a feed rate of 15-20 tons per hour for soil with 15-20%moisture content and negligible BTU content (< 500 BTU/lb). A layoutjDf thetreatment system is presented in Figure 5.2.^Based on~~"pre io~us~pTojecr

experience, as well as the results of previous treatability testing, the LTTDsystem will meet the performance requirement for reducing the levels of VOCsand SVOCs from contaminated soil at the Lakeland site. The major componentsof the system are described below. Equipment tag numbers are also listed forcross-reference with the equipment drawings.

5.3.1 Feed Processing Unit (FU-1)

As stated previously, the LTTD is designed to accommodate variable feedconditions such as changes in moisture content or levels of organics.Operational parameters (e.g., temperatures, feed rate, and dryer slope) can oftenbe modified in order to eliminate the need for soil conditioning prior toprocessing. Therefore, mixing or blending of waste feed material is generally notrequired. However, if excessive soil moisture contents are encountered,blending and/or the addition of lime may be required to make the material moreamenable to material handling.

Initially, the contaminated soil will be excavated and staged for screening. APowerScreen Mark II (or equivalent) will be utilized to segregate inorganic debrisand size organic materials to 2-inch minus. After screening, the soil will bedelivered to the feed metering unit by a front-end loader. If necessary, a bargrate will be utilized to further screen rocks and debris before the soil passes intothe hopper of the apron feeder and onto the feed belt conveyor (C-1). Williams'material handling units can be fitted with several different screen sizes or noscreen at all depending upon the amount of oversized material present in thefeed soil. The screen size to be used during production operations will beselected based on the optimum unit performance and may change with varying


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SHEET NO.

10/23/00

FIG 1

feed soil conditions. If the consistency of the feed material causes excessivebridging of the screen, Williams may elect to eliminate further use of the screen.A weigh belt scale located on the feed belt conveyor provides the control boardoperator with instantaneous and cumulative feed rates to the system. The speedof the drag chain on the apron feeder is adjustable to control the soil feed flowrate. The weigh belt conveyor transfers metered soils to the slinger belt forintroduction into the thermal desorber.

5.3.2 Thermal Desorber (TD-1)

The thermal desorber consists of a rotary dryer with internal flights for lifting andshowering the solids through the hot gas stream. The repeated spilling actionveils the material through the hot gas stream, raising the soil temperature totemperatures in the range of 400°F to 1000°F. The desired soil temperaturedepends on the physical characteristics of contamination and the cleanup levelsrequired. Moisture is evaporated and hazardous waste constituents in the soilare volatilized or desorbed. For the Lakeland project, it is anticipated that a soiltreatment temperature of less than SOOT will be required to meet the soilcleanup goals. If phthalates do not meet the cleanup criteria at this condition,Williams will then increase the temperature to approximately 850°F.

Operation of the desorber is countercurrent, with heat supplied by a gas-firedburner (B-1). Retention time in the desorber varies based on the speed ofrotation and the slope of the unit, and is typically between 20 to 25 minutes.Furthermore, countercurrent flow of gases and solids provides greater heattransfer efficiency with a given inlet gas temperature.

Treated soils exit the desorber through the discharge end breaching and fall intothe discharge screw conveyor (C-2). The processed soils are then quenched tocool the material and suppress fugitive dust emissions. A stacking conveyor (C-5) is used to generate temporary treated soil stockpiles that are then sampled forverification analyses.

Gases exit the thermal desorber through the transition ductwork above the feedinput. The temperature of the off-gases is monitored to prevent any condensationof water or organic compounds in the duct and the baghouse, as well as toprotect the baghouse from high temperature excursions.

5.3.3 Baghouse (BH-1)

Particulates in the gas stream from the desorber are filtered in the baghouse.The baghouse consists of 5,300 square feet of filter area and is designed to givea maximum design air-to-cloth ratio of 5:1. Furthermore, the baghouse providesgreater than 99% efficiency for removal of particulates greater than one micron insize. The bag material is P-84, which can withstand temperatures in the range of500°F and has excellent resistance to corrosive atmospheres.


The baghouse cleans by pulse jets of compressed air that expand the flexiblebags and dislodge the filter cakes. Baghouse dust is removed via a series ofaugers located in the base of the baghouse and is transferred to the dischargescrew conveyor for further treatment with the processed soils. This closes thesolids loop in the treatment process.

The baghouse is the Best Available Control Technology (BACT) for controllingparticulate emissions. Stack tests on all previous jobs with P-84 fabric havedemonstrated particulate loadings in compliance with the federal standard of 0.08gr/dscf described in 40 CFR 264 Subpart O. Three of these prior stack testswere conducted with the LTTD unit configuration proposed for the Lakeland site.Particulate emissions at the first two sites averaged 0.0006 gr/dscf and 0.0015gr/dscf. No testing was required at the third site based on these previous results.

5.3.4 Induced Draft Fan (F-1)

An induced draft (ID) fan located after the baghouse provides the driving force forthe movement of gases in the system. The Chicago Blower exhaust fan,equipped with 65 and 75 horsepower motors, is capable of maintaining a nominalflow rate of 25,000 acfm and will maintain negative pressure in the thermaldesorber and baghouse to prevent fugitive emissions.

5.3.5 Thermal Oxidizer

The gases from the baghouse enter the oxidizer and are heated to temperaturefor approximately 2 seconds in a 4-6% oxygen rich atmosphere to ensurecomplete oxidation of the VOCs. The destruction of the VOCs in the flue gasdepends on the residence time, turbulence, and temperature inside the oxidizer.The oxidizer is sized to provide sufficient residence time and is fitted with a highintensity burner to provide the turbulence necessary to oxidize organiccompounds.

The thermal oxidizer unit is fabricated of 3/16-inch carbon steel and isapproximately 10 feet in diameter by 42 feet long. The combustion chamber isinsulated with a blanket of 1-inch thick Kaowool and 4-inch thick center-mountedceramic Z-block modules. Castable refractory lines the bottom of the chamber.The high intensity burner, mounted in the center of the chamber's end, has arating of 55 million Btu/hr.

The temperature of the gases can be raised in excess of 1,800°F in the thermaloxidizer to ensure complete oxidation and destruction of chlorinatedhydrocarbons. However, the operating temperature for this waste will be typicallymaintained at temperatures in the range of 1,500°F.


Table 5.2 provides a description of the major equipment items that arereferenced in this section and in Figure 5.1, Process Flow Diagram. Each pieceof equipment has also been identified by its tag number for easy cross-referencewith the Process Flow Diagram. Key characteristics for the major componentslisted below have been provided in accordance with Section 13180 of thespecifications. A list of anticipated excavation and material handling equipmentis provided in Section 8 (Table 8.1).

Table 5.2LTTD Equipment Description and Specifications

Feed Metering Unit (FU-1)Hopper Capacity

Apron Feeder CapacityBelt Conveyor Size

DriveManufacturer and Model

10.0 cubic yards100 tons per hour

36 inchesElectricTarmac

Feed Belt (C-1)Type

Belt Conveyor WidthDrive

Belt Scale

Belt conveyor with receiving hopper18 inches

2 horsepower electricTecweigh, instantaneous and cumulative

readouts (tons/hour)Thermal Desorber (TD-1)

ManufacturerNominal Feed Rate

Internal Drum DimensionsDrum Speed

DriveMaterials

Cedar Rapids, countercurrent rotary dryer25 tons per hour

6'-4"dia. x 31 '-0" long1. 65 to 6. 60 rpm, variable

40 hp electric, variable speedCarbon steel, Incoloy

Thermal Desorber Burner (B-1)Manufacturer and Model

CapacityFuel

Blower

Eclipse Vortometric 14V32 MM Btu/hour

PropaneChicago Fan 18" ID, 15hp,

6,400 scfm and 8" spDischarge Screw Conveyor (C-2)

TypeSizeDrive

Screw conveyor18" diameter x 24' long

25 horsepowerStacking Conveyor (C-5)

Type

Stacking RadiusBelt Width

Drive

Covered belt conveyor withwater spray

30 feet18 inches

10 horsepower electric


Baghouse Dust Collector (BH-1)Type

Nominal FlowrateFilter Area

Filter MaterialMaximum Temperature

Air to Cloth Ratio

Williams, pulse jet dust collector25,000 acfm

5,300 square feetP-84

510°F5:1 (maximum design ratio)

Baghouse Discharge Conveyor (C-3)TypeDrive

9 inch screw conveyor2 horsepower electric

Dust Transfer Conveyor (C-4)TypeDrive

10 inch screw conveyor7.5 horsepower electric

Induced Draft Fan (F-1)Manufacturer and Model

TypeSize

Nominal FlowrateConstruction

Damper

Chicago Blower, 29LSIndustrial radial blade centrifugal

29 inch inlet, 65 and 75 hp motors25,000 acfm

Stainless steelInlet, radial

Thermal Oxidizer (TO-1)Drum Dimensions

VolumeCross-sectional Velocity

1 0' diameter x 42' long2,900 cubic feet

20.2 feet per secondThermal Oxidizer Burner (B-2)

ManufacturerCapacity

FuelBlower

Eclipse Vortometric55 MM BTU/hour

PropaneChicago 24.5" ID, 25 hp, 11,000 cfm

StackDiameter

Exit Height from GradeConstruction

6 feet24 feet

Carbon steel with ceramic refractoryProgrammable Logic Controller

Manufacturer and ModelType

Software

Application

Allen-Bradley SLC 500Modular Rack System

Allen-Bradley Advanced ProgrammingSoftware (APS)

Provides startup sequencing and systeminterlock control


5.4 CONTROL SYSTEM DESCRIPTION

The control room for the LTTD is inside a mobile trailer. Three sides of thecontrol room are glass paneled so the control room board operator cansimultaneously monitor the process variables and view the operations outside thecontrol room. The equipment motors and pumps are started and stopped viaSTART-STOP push/pull buttons located on the panel in the control room trailer.The control room is insulated and can be heated or cooled as per therequirement. The pressure in the control room is kept positive to prevent dustfrom entering.

5.4.1 Process Variable Recording

Several process variables are continuously recorded. Among these are the soilfeed rate; soil exit temperature; temperature at the exit of the desorber andoxidizer; differential pressure across the baghouse; and desorber draft. Thisdata is recorded by a Johnson Yokogawa Model HR2400 data logger.

5.5 PROCESS RESIDUAL STREAMS

Upon commencement of shakedown and production operations, the LTTDprocess and associated tasks will generate the following residual streams:

• oversized debris too large for treatment (> 2 inches cubed)• treated soil prior to laboratory confirmation• water collected from containment pad run-off• decontamination residuals.

5.5.1 Oversized Material and Debris

Thermal desorption requires a significant amount of material handling. Williamswill be processing organic material that will be sized to two inches or less.Initially, material will be screened through a PowerScreen (or equivalent) unitprior to thermal treatment. Oversized material rejected by the PowerScreen gridwill be stockpiled and disposed in accordance with the specifications. Thisoversized material will not be treated by the thermal desorption process becauseit cannot be handled by the LTTD's material handling equipment and may causedamage to the unit.

5.5.2 Treated Soil Prior to Laboratory Confirmation

Treated soil exits the thermal desorber and passes into the enclosed dischargescrew conveyor. A negative pressure is maintained on the discharge conveyor tocapture any steam from the re-moisturization process. The treated, conditionedsoil then discharges to a belt conveyor for stacking. The stacking conveyor iscapable of producing treated soil piles in excess of 200 tons. The treated soil is


removed from the stacking area by a front-end loader to an interim storage area.While awaiting laboratory confirmation, soil piles remain within the confines of thecontainment area and are covered by plastic sheeting. The covering helpsprevent dusting due to wind and run-off due to rain. Any run-off that may occurfrom the treated soil piles during times they are uncovered (i.e., duringloading/off-loading) will be collected and treated by the unit's water treatmentsystem. After lab results have been obtained to confirm that the treated pileshave met soil cleanup goals, the soils will be stockpiled as clean soil andsubsequently backfilled on-site.

5.5.3 Run-off Water

Water collected as run-off from the LTTD operations area will be transferred toand treated by the water treatment facility. Treated water will be used for soil re-moisturization activities prior to soil sampling or disposed in accordance with therequirements of the disposal facility.

5.5.4 Decontamination Residuals

During decontamination activities, Williams intends to treat as much soil andsludge residue via thermal desorption as possible. However, after the LTTD unithas been dismantled, any residuals collected will be stockpiled and analyzed forthe contaminants of concern. If the analyses show that the contamination levelsare below site cleanup goals, the residues will be backfilled as all other treatedsoils. Residues failing to meet cleanup standards will be disposed off-site.

5.6 PROCESS CONTROLS, MONITORING, AND EMERGENCYPROCEDURES

5.6.1 Overview

Williams has provided instrumentation for process control of feed rates,temperatures, pressures, burner efficiency, and gas stream contents. In addition,the system is designed to provide for the control and orderly management of anyupset condition that may potentially occur during operations. This system alsoprovides documentation of key operating variables to verify operating conditions.

The feed rate of the soil is monitored by a weigh belt located on the feedconveyor. The readout in the control room gives the instantaneous feed rate intons per hour plus integrated totals. The data acquisition system also providesthe feed rate rolling average. Pressures are registered on standard industrialpressure and vacuum gauges for low pressures and draft with industrial Bourdontube gauges for high pressures. Temperatures are measured by k-typethermocouples installed well into the process streams to obtain accuratetemperature measurements.


Certain specific process upsets can create situations where timely actions arerequired to ensure safety, protect equipment, and prevent the emission ofparticulates, gases, or liquids from the system at rates that exceed regulatorystandards. Two automatic control actions are provided to address the mostprobable upsets, failures, or emergencies. These are the Automatic Air Intake(AAI) and the Automatic Waste Feed Shut Off (AWFSO). Typical eventstriggering an AAI or AWFSO are listed in Table 5.3.

The AAI action allows ambient air to be introduced into the process gas streamjust prior to the baghouse. This is accomplished by opening a damper thatsupplies air to the main crossover duct before it enters the baghouse plenumchamber. The major purpose of the AAI is to protect the air pollution controlequipment (APCE) from high gas temperature excursions. The location of the airintake is on the draft side of the ID fan. This allows air to be introduced into thesystem while eliminating the possibility of fugitive emissions.

The AWFSO action shuts down the feed belt conveyor to the thermal desorber.This is accomplished by interlocks in the control system. The major purpose ofthe AWFSO is to discontinue soil processing if process operating conditions areoutside of established limits.

In addition to the automatic controls described above, operators are trained torespond to any other abnormal process operating conditions. Potential abnormaloperating conditions and operator responses are described in Section 5.6.3.

5.6.2 Emergency or Upset Conditions

Instrumentation is provided to monitor process conditions, to provide data forensuring compliance with regulatory requirements, and to ensure appropriateprocess response, control, operations flexibility, safety interlocks, and shutdownfeatures. The safety interlocks and shutdown features comprise a major portionof the control system. Typical conditions under which the AWFSO and AAIoperate are noted in Table 5.3.

5.6.3 Corrective Action Procedures

In addition to the above procedures, several process upset conditions and theircorresponding corrective actions have been identified for this project. These aredescribed below.

a. Partial or Complete Stoppage of Soil Feed

The stoppage of waste feed (if it is not observed by the operator) will be firstidentified as an increase in desorber exit gas temperature followed by a decreasein desorber pressure. An increase in desorber temperature is covered under (e).


Should the feed be interrupted, the operator will idle the plant with heat in thesystem until feed is restored.

b. Puffing or Sudden Occurrence of Fugitive Emissions

The desorber draft is monitored continuously. The operator will manuallyincrease draft via the induced draft fan if the draft is less than -0.01" w.c. (watercolumn). If the draft goes positive (i.e., > 0.00" w.c.), an AWFSO will result untilthe draft is increased.

c. Failure of Forced Air Supply

The Burner Management System (BMS) will automatically trip the burner if theforced draft fan fails.

d. Process Temperature Too High

A preliminary operating desorber off-gas temperature of about 400°F has beenselected. When the temperature goes above the 400°F setpoint, there will be aproportional decrease in fuel to the desorber. If the temperature reaches apredetermined maximum value of approximately 475°F, based on a rollingaverage, all fuel and waste feed flow will be stopped. If the temperature exceedsSOOT, an AAI will occur.

A preliminary thermal oxidizer setpoint temperature of approximately 1,500°F hasbeen selected. If the temperature rises above 2,100°F, the thermal oxidizerburner will be shut down and an AWFSO will result.

e. Process Temperature Too Low

An operating desorber off-gas temperature setpoint of about 400°F is expected.When the temperature goes below 400°F, there will be a proportional increase infuel to the desorber.

f. Desorber Pressure Too High (Loss of Vacuum)

The desorber draft is monitored continuously. The operator will manuallyincrease draft via the I.D. fan if the draft is less than -0.01" w.c. If the draft goespositive (i.e., > 0.00" w.c.), an AWFSO will result until the draft is increased.

g. Baghouse Differential Pressure Too Low

A low baghouse differential pressure may be an indication of low gas flow or filterbag failure. This parameter will be continuously monitored and tied to anAWFSO based on operating experience at the site.


h. Sudden Loss of Refractory Lining

This is an unusual occurrence and is indicated by hot spots on the thermaloxidizer. Hot spots are detected visually. A loss of refractory lining causes theoxidizer shell to increase in temperature and appear to glow in the area ofrefractory loss. If the hot spots persist, Williams will take the necessarymeasures, such as running cooling water over the affected areas, until such timeas the proper repairs can be made. If the situation becomes more serious (e.g.,leaks developing in the shell of the oxidizer), this will signal the operator toperform an orderly system shutdown for inspection and repair.

i. Indication of Failure of the I.D. Fan

If the induced draft fan fails, both the fuel and the waste feed flow will be stoppedat once.

j. Failure of Treated Material Handling System

When the processed soil handling system fails, the operator will inspect thesystem and idle or shut down as necessary.

k. Power Failure

In the event of a power failure, feed and fuel are interrupted. This sequence alsooccurs when the induced draft fan stops.

I. External System Fire

ABC fire extinguishers will be strategically placed; however, the fire departmentwill be called on any major system fires.

m. Burner System Safety Controls

The gas burner system includes a standard industrial interlock system that shutsthe burner system down if:

• Flame is detected during pre-ignition,• Pilot fails to ignite,• Burner fails to ignite, or• Loss of flame after ignition.

The interlocks are controlled through the burner management system, whichincludes flame safeguards and safety packages. The main features of thesystem include:


UV scanner and pilot safetyBurner shutdown due to loss of ID fanAir to fuel ratio controlHigh temperature cut-offHigh gas pressure control.

Table 5.3Events Triggering Interlock Control System

Control Parameters (a)Group A ParametersMaximum rotary dryer pressureMaximum rotary dryer exit gas temperatureMinimum baghouse differential pressureMaximum oxidizer exit gas temperatureMaximum THC (instantaneous)Burner system failure

Units

in. w.c.°F

in. w.c.°F

ppm

Approx.Value

0.005100.25

2,100100

Comments (b)

Instantaneous AWFSOInstantaneous AWFSO, AAIInstantaneous AWFSOInstantaneous AWFSOInstantaneous AWFSOInstantaneous AWFSO

Notes:(a) Group A parameters are continuously monitored and are interlocked with

the AWFSO system.(b) AWFSO = automatic waste feed shutoff; AAI = automatic air intake

5.7 OPERATION AND MAINTENANCE

Operation and maintenance (O&M) on the LTTD system will be performed asrequired and/or at regularly scheduled intervals. Maintenance will be performed inaccordance with the O&M Manual for the system, as well as based on previousexperience with the unit. It is important to note, however, that the O&M Manual isgeneral in nature and is not intended to be site specific. Its purpose is to serveas a general guideline for operation and maintenance of the equipment;therefore, not all aspects of the manual may be applicable to every project.Specific requirements related to a project are left for discussion in the work planand it's supporting documents.


Documents

ARCADIS LETTER RE: REVISION TO DESIGN PLAN, REMEDIATION … · Services, Inc. detailing the proposed thermal oxidizer to be used with the LTTD unit for effluent air treatment. Details