NRMRL RTP 236a January 2002 Characterization of Mercury Emissions at a Chlor Alkali Plant VOLUME I Report and Appendices A E John S. Kinsey U. S. Environmental Protection Agency Office of Research and Development National Risk Management Research Laboratory Research Triangle Park, North Carolina 27711 ii ABSTRACT Current estimates indicate that up to 160 short tons ( 146 Mg) of mercury ( Hg) is consumed by the chlor alkali industry each year. Very little quantitative information is currently available, however,

on the actual Hg losses from these facilities. The Hg cell building roof vent is considered to be the most significant potential emission point in chlor alkali plants, especially when the cells are opened for maintenance. Because of their potential importance, chlor alkali plants have been identified as needing more accurate measurements of Hg emissions. To obtain a better understanding of the fate of Hg within their manufacturing process, the Olin Corporation voluntarily agreed to cooperate with the U. S.

Environmental Protection Agency in a comprehensive study of the Hg emissions from their Augusta,

GA, facility, in collaboration with other members of the Chlorine Institute representing the active chloralkali plants in the United States.

To investigate the Hg releases from the Olin chlor alkali facility, the EPA's National Risk Management Research Laboratory, Air Pollution Prevention and Control Division ( EPA APPCD) in Research Triangle Park, NC, organized a special study involving multiple organizations and personnel. However, only the research conducted by EPA APPCD involving roof vent monitoring and air flow studies conducted in the Olin cell building is discussed in this report.

The overall objective of monitoring the cell building roof vent was to determine the total elemental mercury ( Hg0) mass flux from the cell building under a range of typical wintertime meteorological conditions, including both normal operation of the cell building and routine maintenance of Hg cells and decomposers. Secondary objectives of the research were to perform an air flow mass balance for the building and to compare various Hg monitoring methods under a variety of sampling conditions. Both objectives were met during the February 2000 field sampling campaign, which showed an average Hg0 emission rate of 0.36 g/ min from the roof ventilator as determined over the 9

day monitoring period. iii TABLE OF CONTENTS Volume I ABSTRACT . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . viii LIST OF ABBREVIATIONS AND SYMBOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix UNIT CONVERSION TABLE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi ACKNOWLEDGMENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xii SECTION 1 INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1.2 Overall Program Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 1.2.1 Preliminary Survey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.2.2 Winter Sampling Campaign . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 1.3 Research Objectives . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 1.4 Organization of Report . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 SECTION 2 CONCLUSIONS AND RECOMMENDATIONS . . . . . . . . . . . . . . . . . . . . . . . 9 SECTION 3 PROCESS DESCRIPTION AND OPERATION . . . . . . . . . . . . . . . . . . . . . . . 12 3.1 General Process Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.2 Plant Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3.3 Cell Building . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 SECTION 4 EXPERIMENTAL PROCEDURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.1 Measurement Methods, Setup, and Calibration . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.1.1 Roof Vent Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 4.1.2 Manual Tracer Gas Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29 4.1.3 Manual Velocity Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4.2 Data Reduction and Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 4.2.1 Roof Vent Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 4.2.2 Tracer Gas Analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 4.2.3 Emission Rate Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35 4.2.4 Manual Velocity Measurements and Flow Balance Calculations . . . . . . 40 TABLE OF CONTENTS ( Continued)

iv SECTION 5 RESULTS AND DISCUSSION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5.1 Mercury Monitoring Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44 5.1.1 Monitoring Data and Mercury Emission Rates . . . . . . . . . . . . . . . . . . . 44 5.1.2 Comparison of Mercury Measurement Methods . . . . . . . . . . . . . . . . . . 55 5.2 Tracer Gas Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 5.2.1 Roof Vent Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63 5.2.2 Tracer Gas Study   Manual Bag Sampling . . . . . . . . . . . . . . . . . . . . . . 63 5.3 Air Flow Study Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 5.3.1 Roof Vent Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66 5.3.2 Flow Balance Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 68 5.4 Discussion of Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 5.4.1 Roof Vent Monitoring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 5.4.2 Building Air Flow Evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 5.4.3 Comparison with Historical Information . . . . . . . . . . . . . . . . . . . . . . . . 71 SECTION 6 QUALITY ASSURANCE/ QUALITY CONTROL . . . . . . . . . . . . . . . . . . . . . . 74 6.1 UV DOAS Measurements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 6.2 Optical Anemometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 74 6.3 SF 6 Release, Sampling, and Analysis ( FTIR) . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 6.4 Long Path FTIR QA/ QC Checks ( Roof Vent) . . . . . . . . . . . . . . . . . . . . . . . . . 77 6.5 On Site Audit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79 6.6 Data Quality Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 SECTION 7 REFERENCES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81 APPENDICES A Description of Buildings and Processes at the Olin Facility . . . . . . . . . . . . . . . A i B FTIR Spectral Analyses Conducted by ManTech, Inc. ( Jeff Childers) . . . . . . . B i C FTIR Spectral Analyses Conducted by ARCADIS Geraghty & Miller ( David Natschke) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . C i D Roof Vent Manual Velocity Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . D i E Manual Velocity Data in Cell Building Openings and Associated Air Flow Balance Calculations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . E i TABLE OF CONTENTS ( Continued)

v Volume II F Elemental Mercury Emission Rate Calculations . . . . . . . . . . . . . . . . . . . . . . . . F i G Elemental Mercury and Air Velocity Measurements at Entrance to Roof Vent Made During January 2000 Presurvey . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . G i H UV DOAS Quality Control Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . H i I Bag Sampling Quality Control Data and Rotameter Calibrations . . . . . . . . . . . . I i J Copies of Field Sampling Notebook Pages from Manual Bag Sampling . . . . . . . J i vi LIST OF FIGURES 1 1 Project organization chart ( includes contractor support from OPSIS ® , Inc., and Eastern Research Group, Inc.). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1 2 Location of measurement activities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 1 Simplified diagram of the mercury cell process. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 3 2 Process flow diagram for Olin Augusta. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3 3a Cell building showing interior of roof ventilator. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3 3b Cell building showing exterior of roof ventilator ( from north). . . . . . . . . . . . . . . . . . . . 17 3 4 Electrolyzer used at the Olin Augusta plant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3 5 Mercury cell: horizontal view and outlet end box view. . . . . . . . . . . . . . . . . . . . . . . . . 19 3 6 North line of electrolytic cells in Olin cell building. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 3 7 Decomposer used at the Olin Augusta plant. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 3 8 General diagram of the cell building showing cell rows, general fan locations, etc. . . . . 23 4 1 Cross section of roof ventilator showing internal structure. . . . . . . . . . . . . . . . . . . . . . 26 4 2 From left to right, the FTIR retroreflector, UV DOAS light source, and optical anemometer receiver unit installed on the east sampling platform. . . . . . . . . . . . . . . . . . 27 4 3 Relative locations of instrument beam paths in roof vent cross section. . . . . . . . . . . . . . 29 4 4 Cylinder layout along the cell building basement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4 5 Soaker tubing layout inside the cell room. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34 4 6a Average roof vent temperature differential as determined from 15 min monitoring data. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 4 6b Calculated temperature differential for roof ventilator as determined from average monitoring data shown in Figure 4 6a. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39 5 1 Time history of roof vent elemental mercury concentration for February 17, 2000. . . . . 45 5 2 Time history of roof vent elemental mercury concentration for February 18, 2000. . . . . 45 5 3 Time history of roof vent elemental mercury concentration for February 19, 2000. . . . . 46 5 4 Time history of roof vent elemental mercury concentration for February 20, 2000. . . . . 46 5 5 Time history of roof vent elemental mercury concentration for February 21, 2000. . . . . 47 5 6 Time history of roof vent elemental mercury concentration for February 22, 2000. . . . . 47 5 7 Time history of roof vent elemental mercury concentration for February 23, 2000. . . . . 48 5 8 Time history of roof vent elemental mercury concentration for February 24, 2000. . . . . 48 5 9 Time history of roof vent elemental mercury concentration for February 25, 2000. . . . . 49 5 10 Time history of roof vent air velocity for February 17, 2000. . . . . . . . . . . . . . . . . . . . . 50 5 11 Time history of roof vent air velocity for February 18, 2000. . . . . . . . . . . . . . . . . . . . . 50 5 12 Time history of roof vent air velocity for February 19, 2000. . . . . . . . . . . . . . . . . . . . . 51 5 13 Time history of roof vent air velocity for February 20, 2000. . . . . . . . . . . . . . . . . . . . . 51 5 14 Time history of roof vent air velocity for February 21, 2000. . . . . . . . . . . . . . . . . . . . . 52 LIST OF FIGURES ( Continued)

vii 5 15 Time history of roof vent air velocity for February 22, 2000. . . . . . . . . . . . . . . . . . . . . 52 5 16 Time history of roof vent air velocity for February 23, 2000. . . . . . . . . . . . . . . . . . . . . 53 5 17 Time history of roof vent air velocity for February 24, 2000. . . . . . . . . . . . . . . . . . . . . 53 5 18 Time history of roof vent air velocity for February 25, 2000. . . . . . . . . . . . . . . . . . . . . 54 5 19 Elemental mercury emission rates for February 17, 2000. . . . . . . . . . . . . . . . . . . . . . . . 56 5 20 Elemental mercury emission rates for February 18, 2000. . . . . . . . . . . . . . . . . . . . . . . . 56 5 21 Elemental mercury emission rates for February 19, 2000. . . . . . . . . . . . . . . . . . . . . . . . 57 5 22 Elemental mercury emission rates for February 20, 2000. . . . . . . . . . . . . . . . . . . . . . . . 57 5 23 Elemental mercury emission rates for February 21, 2000. . . . . . . . . . . . . . . . . . . . . . . . 58 5 24 Elemental mercury emission rates for February 22, 2000. . . . . . . . . . . . . . . . . . . . . . . . 58 5 25 Elemental mercury emission rates for February 23, 2000. . . . . . . . . . . . . . . . . . . . . . . . 59 5 26 Elemental mercury emission rates for February 24, 2000. . . . . . . . . . . . . . . . . . . . . . . . 59 5 27 Elemental mercury emission rates for February 25, 2000. . . . . . . . . . . . . . . . . . . . . . . . 60 5 28 Lateral profile of elemental mercury concentration as determined by the Jerome 431 X instrument. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 5 29 UV DOAS/ Tekran comparison ( February 17 21, 2000). . . . . . . . . . . . . . . . . . . . . . . . 62 5 30 Chronology of elemental mercury concentrations measured by OPSIS   Model AR 500 UV DOAS and Tekran Model 2537A CVAFS for February 17 21, 2000. . . . . 62 5 31 Bag sampling locations in cell building. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 5 32 Hand held anemometer readings at the optical anemometer measurement height on the east sampling platform, looking west . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 5 33 Hand held anemometer readings at the optical anemometer measurement height on the west sampling platform, looking west. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 5 34 Profile of elemental mercury concentration along length of roof vent entrance as obtained during the January 2000, presurvey. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70 viii LIST OF TABLES 4 1 Roof Vent Instrumentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 4 2 Typical FTIR Operating Parameters . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31 4 3 Gas Release Concentrations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36 5 1 Summary of 30 sec Roof Vent DOAS Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49 5 2 Summary of 1 min Roof Vent Optical Anemometer Data . . . . . . . . . . . . . . . . . . . . . . . 54 5 3 Summary of Calculated Elemental Mercury Emission Rates . . . . . . . . . . . . . . . . . . . . . 60 5 4 Manual Bag Analysis Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 5 5 Comparison of Velocity Measurements in Roof Vent . . . . . . . . . . . . . . . . . . . . . . . . . . 68 5 6 Results of Air Flow Balance Calculations for the Olin Cell Building . . . . . . . . . . . . . . . 68 5 7 Comparison of Current Study with Prior Research . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 6 1 QC Checks for Experimental Methods Included in QA Plan . . . . . . . . . . . . . . . . . . . . . 75 6 2 Quality Control Checks for UV DOAS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 6 3 Results of Daily QC Checks of Model 104a Optical Anemometer . . . . . . . . . . . . . . . . . 76 6 4 Manual Bag Sampling/ Analysis Blank Control Checks . . . . . . . . . . . . . . . . . . . . . . . . . 78 6 5 Manual Bag Sampling/ Analysis Quality Control Checks . . . . . . . . . . . . . . . . . . . . . . . . 78 6 6 Data Quality Indicator Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 ix LIST OF ABBREVIATIONS AND SYMBOLS APPCD Air Pollution Prevention and Control Division ATREEs anemometer trees CAPs Chlor alkali plants CH 4 methane Cl 2 chlorine gas CO carbon monoxide CVAFS cold vapor atomic fluorescence spectrometer DAS data acquisition system DMB direct mass balance DOAS differential optical absorption spectrometer DQI data quality indicator EPA U. S. Environmental Protection Agency ERG Eastern Research Group, Inc.

FTIR Fourier transform infrared spectrometer H 2 hydrogen HCl hydrogen chloride Hg mercury Hg0 elemental mercury LIDAR Light Detection and Ranging LOA Scientific Technology Model LOA 104 optical anemometer LRPCD Land Remediation and Pollution Control Division N 2 O nitrous oxide NaCl sodium chloride LIST OF ABBREVIATIONS AND SYMBOLS ( Continued)

x NaOH sodium hydroxide NERL National Exposure Research Laboratory NIST National Institute for Standards and Technology NWS National Weather Service OECA Office of Enforcement and Compliance Assurance ORNL Oak Ridge National Laboratory OxyChem Occidental Chemical Corporation PI Principal Investigator QAPjP Quality Assurance Project Plan QC quality control SOP Standard Operating Procedure SF 6 sulfur hexafluoride UM University of Michigan UV DOAS ultraviolet differential optical absorption spectrometer xi UNIT CONVERSION TABLE Multiply By To Obtain atm 29.92 in. Hg atm 760 mm Hg ft 0.3048 m km 0.6214 mi L/ day 0.264 gal./ day m3/ min 35.31 ft3/ min pounds 453.6 g short ton 0.91 metric ton temperature (

C + 17.8) 1.8 temperature (

F) xii ACKNOWLEDGMENTS This report was prepared with the assistance of Julie Swift and Joan Bursey of Eastern Research Group, Inc., 1600 Perimeter Park Drive, Morrisville, NC 27560, under EPA Contract 68 D7 0001. Julie Swift was responsible for the tracer gas release and manual bag sampling conducted in the field as well as preparing applicable sections of the report. Joan Bursey was responsible for the QA/ QC sections of the report as well as supervising its overall production.

The author acknowledges the excellent contributions of both individuals. 1 SECTION 1 INTRODUCTION 1.1 Background Current estimates indicate that up to 160 short tons ( 146 Mg) of mercury ( Hg) is consumed by the chlor alkali industry each year ( Chlorine Institute, 1999). Very little quantitative information is currently available, however, on the actual Hg losses from these facilities. The most significant potential emission point in chlor alkali plants ( CAPs) is thought to be the mercury cell building roof vent, especially when the cells are opened for maintenance. Because of their potential importance, CAPs have been identified as needing more accurate measurements of Hg emissions.

In order to better understand the fate of mercury within their manufacturing process, the Olin Corporation voluntarily agreed to cooperate with the U. S. Environmental Protection Agency ( EPA) in a comprehensive study of the Hg emissions from their Augusta, GA, facility. This effort is in collaboration with other members of the Chlorine Institute representing the active chlor alkali plants in the United States.

Chlorine Institute members have committed to reduce overall mercury consumption by 50% ( from 1990 95 levels) by the year 2005.

To investigate the Hg releases from the Olin chlor alkali facility, the U. S. Environmental Protection Agency's National Risk Management Research Laboratory, Air Pollution Prevention and Control Division ( EPA APPCD) in Research Triangle Park, NC, organized a special study involving multiple organizations and personnel. Each major aspect of the study was addressed by a separate Principal Investigator ( PI) based on the individual area of expertise. It should be noted, however, that only the research conducted by EPA APPCD involving roof vent monitoring and air flow studies conducted in the Olin cell building is discussed in this report. The following sections describe the overall study 2 conducted at the Augusta plant, the objectives of the specific research described in this report, and organization of the remainder of the document.

1.2 Overall Program Description A multidisciplinary research team was assembled for the purpose of the Olin study. This team was made up of the following organizations and associated principal investigators ( PIs):

Olin Corporation, Olin Chemicals, Charleston, TN ( W. Rankin) and Chlor Alkali Division, Augusta, GA ( S. Asbill).

U. S. Department of Energy, Oak Ridge National Laboratory ( ORNL), Environmental Sciences Division, Oak Ridge, TN ( S. Lindberg).

U. S. Environmental Protection Agency, Office of Enforcement and Compliance Assurance ( EPA OECA), Office of Regulatory Enforcement, Washington, DC. ( C. Secrest).

U. S. Environmental Protection Agency, Office of Research and Development, National Exposure Research Laboratory ( EPA NERL), Research Triangle Park, NC ( M. Landis).

U. S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Air Pollution Prevention and Control Division ( EPA APPCD), Research Triangle Park, NC ( J. Kinsey).

U. S. Environmental Protection Agency, Office of Research and Development, National Risk Management Research Laboratory, Land Remediation and Pollution Control Division ( EPA LRPCD), Cincinnati, OH ( P. Randall).

U. S. Environmental Protection Agency, Region 4 ( EPA Region 4), Science and Ecosystem Support Division, Atlanta, GA ( D. France).

U. S. Environmental Protection Agency, Region 5 ( EPA Region 5), Great Lakes Program Office, Chicago, IL ( F. Anscombe).

University of Michigan ( UM), Department of Environmental & Industrial Health, School of Public Health, Ann Arbor, MI ( J. Nriagu).

As shown, the research team represents nine different organizations with up to 28 people working on site. Figure 1 1 shows the organization of the project, including the various monitoring activities conducted and PIs responsible for each facet of the program as well as contractor support to EPA APPCD from OPSIS ® , Inc. and Eastern Research Group ( ERG), Inc. 3 Frank Anscombe EPA Region 5 Administrative Lead John Kinsey EPA APPCD Technical Lead Roof Vent Monitoring ( EPA APPCD)

PI  John Kinsey ( EPA APPCD)

Long Path FTIR ( EPA Region 4) Long Path UV DOAS ( Opsis) Optical Scintillation Anemometer ( EPA APPCD)

Point Source Measurements ( ORNL)

PI  Steve Lindberg ( ORNL)

Tekran Model 2537A Automated Hg Analyzer Jerome Model 431 X electrical conductivity analyzer and Lumex Model RA 915 Zeeman Mercury Spectrometer Denuder Grab Samples ( EPA NERL) Cell Building Air Flow Determination ( EPA APPCD)

PI  John Kinsey ( EPA APPCD)

Long path Optical Anemometer ( EPA APPCD) Tracer Gas Release and Analysis of Point SF6 ( Eastern Research Group) Manual Anemometry ( EPA APPCD)

Flux Measurements ( ORNL)

PI  Steve Lindberg ( ORNL)

Tekran Model 2537A with Flux Chambers Upwind/ Downwind Monitoring ( EPA NERL, EPA Region 4, EPA OECA, and EPA APPCD)

PIs  Matt Landis ( EPA NERL), Danny France ( EPA Region 4), and Cary Secrest ( EPA OECA)

Tekran Model 2537A with 1130 and 1135 Speciators ( EPA NERL) EPA Denuders ( EPA NERL) Open Path FTIR Spectrometer ( EPA APPCD) UV DOAS ( EPA Region 4/ OECA)

Waste Stream and Product Evaluation ( UM, EPA LRPCD)

PIs Jerome Nriagu ( UM) and Paul Randall ( EPA LRPCD)

Liquid Waste Sample Collection/ Analysis Solid Waste Sample Collection/ Analysis Product Sample Collection/ Analysis Nancy Adams EPA APPCD Quality Assurance Officer On site Quality Control Officers Geddes Ramsey/ Jimmy Pau, EPA APPCD W. Rankin Olin  Charleston S. Asbill Olin  Augusta Figure 1 1. Project organization chart ( includes contractor support from OPSIS ® , Inc., and Eastern Research Group, Inc.). 4 The program was divided into two phases: a preliminary survey, and a winter sampling campaign conducted in February 2000. A summer campaign was also planned to evaluate the effects of elevated ambient temperature but this phase was eliminated and thus is not discussed here. Implementation of the overall program is briefly outlined below with formal publication of the results by the respective Principal Investigator planned for late 2002.

1.2.1 Preliminary Survey The purpose of the survey was to obtain preliminary information to assist in planning the second,

and more significant, phase of the program. The survey included measurements of the typical range of elemental mercury ( Hg0) concentrations in the cell building as well as similar measurements external to the cell building. In addition, flow visualization experiments were also performed and meetings held with Olin operating personnel to plan the logistics of the winter sampling campaign.

The Hg monitoring methods used in the preliminary survey generally involved portable hand held instruments, including both the Jerome Model 431 X electrical conductivity analyzer and the Lumex Model RA 915 Zeeman Mercury Spectrometer. The Model RA 915 is a portable cold vapor atomic absorption ( CVAA) spectrometer capable of monitoring Hg0 at nanograms per cubic meter levels. Both instruments were used to measure and spatially map Hg0 levels in and around the electrolytic cells as well as upwind and downwind of the cell building.

In addition to point monitoring, profiles of air velocity and Hg0 concentration were also obtained near the entrance to the roof vent. The measurements were conducted by mounting a sampling line and hotwire anemometer on a non conducting mast attached to the upper platform of the movable crane used for cell maintenance. The sampling line was connected to a Jerome 431 X electrical conductivity analyzer with the velocity measurements made at selected intervals along the length of the vent.

Finally, since the determination of air flow is critical to study implementation, special flow visualization equipment was also used as part of the preliminary survey. This equipment included an infrared camcorder to observe and record thermal plumes from the cell building and a commercial smoke generator and associated video camcorder for visualizing the overall flow field within the cell room. Flow 5 visualization answered several important questions regarding the nature of the air flow pattern inside the building as well as dispersion of the plume after it exits the roof vent.

1.2.2 Winter Sampling Campaign The overall objective of the winter sampling campaign was to determine the total Hg release from the plant using parallel sampling approaches under typical wintertime meteorological conditions. The activities in the winter campaign included: roof vent monitoring, point source measurements, air flow studies, flux measurements, upwind/ downwind monitoring, and waste and product evaluation. The locations of the various activities at the Olin plant site are shown in Figure 1 2.

As stated above, the research described in this report includes only the roof vent monitoring and air flow studies conducted by EPA APPCD with contractor support from OPSIS ® , Inc. and ERG. The other related activities performed by study collaborators are briefly summarized below.

Point Source Measurements The objective of the point measurements was to characterize the distribution of airborne Hg0 in the cell room ( including the floor below the cells) and around the exterior of the cell building. The primary instrument used for point monitoring was the Tekran Model 2537A automated Hg analyzer. The Model 2537A is a cold vapor atomic fluorescence ( CVAF) spectrometer which is equipped with dual gold traps for preconcentration of the sample prior to analysis. This analyzer was housed in the control room with samples obtained from a high flow sampling line which extended to a point near the center of the roof vent entrance.

In addition to the Tekran monitoring, walking surveys were also conducted using a Jerome Model 431 X and/ or Lumex Model RA 915 instrument. These data were combined with measurements from a hand held air anemometer to identify potential hot spots and any ancillary emission points found in or around the cell building. Manual " denuders" were also employed to determine the concentration of nonelemental Hg ( e. g., divalent Hg compounds) in the cell room. A series of short duration grab samples was collected from the crane above the south cell line and analyzed on site using a Tekran Model 2537A. 6 Preliminary results of these analyses indicate that non elemental forms of Hg represent < ~ 5% of the total Hg at the time of sample collection ( Landis et al., 2000). 7 H C D I E B A G F A B = 200 m Key:

A/ B = Downwind Hg0 and SF6 monitoring using open path instruments.

C = Flux chamber measurements and waste stream evaluation.

D/ E = Roof vent monitoring.

F/ H = Upwind/ downwind monitoring using mobile laboratories.

G = Main plant observation point.

I = Point source measurements and building air flow study.

Figure 1 2. Location of measurement activities. 8 Flux Measurements Mercury fluxes from surfaces in and around the cell building ( especially the basement floor of the building) were also determined to assess the role of these surfaces as sources. Flux chambers of various designs were used over the cell room and ground ( basement) floors to determine their source strength and Hg0 emission characteristics. Chambers were also deployed over old waste deposits within the plant facility and, since solar radiation can strongly influence soil fluxes, operated throughout the diurnal cycle.

Upwind/ Downwind Monitoring Upwind/ downwind ambient air monitoring was also conducted as part of the overall program. The purpose of this monitoring was to estimate the total mass flux of Hg compounds from the entire facility as a check on the source estimates obtained within the plant, for model validation purposes, and to collect data which can potentially be compared to similar measurements conducted outside other facilities.

For the upwind/ downwind monitoring, instrumentation was deployed at different locations. Tekran analyzers were used in two mobile monitoring laboratories located a significant distance upwind and downwind from the process area ( Figure 1 2). ( Note that two of the Tekran instruments used in the mobile laboratories were a Model 1130 analyzer and the prototype Model 1135 capable of measuring gas and particle phase elemental and non elemental Hg.) In addition, an open path Fourier Transform Infrared ( FTIR) spectrometer and ultraviolet differential optical absorption spectrometer ( UV DOAS) were also installed near the cell building in the prevailing downwind direction ( Figure 1 2). Using the various instruments, the concentration of elemental and non elemental Hg and SF6 tracer gas could be determined in near real time. ( Note that the open path monitoring was not successful due to atypical wind conditions occurring during the limited 9 day study period.)

Waste and Product Evaluation Sampling and analysis of liquid and solid wastes and selected liquid product streams were also performed. Wipe samples were also collected from various environmental surfaces including building walls and exterior cell surfaces. These samples were subsequently analyzed for total Hg, Hg0 , and 9 dissolved reactive Hg ( also referred to as " easily reduced Hg"), as appropriate, using a Tekran analyzer as the primary measurement tool.

1.3 Research Objectives The overall objective of the roof vent monitoring described in this report was to determine the total Hg0 mass flux from the cell building under a range of typical wintertime meteorological conditions. This research was to include both normal operation of the cell building as well as routine maintenance of Hg cells and decomposers. Secondary objectives of the research were to perform an air flow mass balance for the building and to compare various Hg monitoring methods under a variety of sampling conditions. Each of these objectives was met in the study.

1.4 Organization of Report This report is organized into five additional sections plus references and appendices. Section 2 provides the conclusions and recommendations derived from the study results, and Section 3 describes the mercury cell process and its operation. Section 4 outlines the experimental procedures used in the research,

and Section 5 presents and discusses the study results. Finally, Section 6 presents the quality control/ quality assurance procedures used in the research to ensure collection of high quality data. 10 SECTION 2 CONCLUSIONS AND RECOMMENDATIONS This section provides conclusions drawn from the use of the equipment, methods, and data analysis procedures described in Section 4 to determine the total Hg release and volumetric air flow from the Olin chlor alkali cell building:

Elemental mercury concentrations measured by the UV DOAS varied over an order of magnitude from ~ 73 to 7.3 µ g/ m3. The overall average for the 9 day study period was 24 µ g Hg0/ m3.

Hg0 emission rates measured in the roof ventilator varied from 0.08 to 1.2 g/ min. An overall average for the monitoring period of 0.36 g/ min ( 472 g/ day) was calculated from the data. These values appear to represent only a small percentage of the total potential Hg0 emissions, however, based on available estimates of the makeup Hg0 added to the cells on an annual basis.

A comparison between the concentration of Hg0 measured by the UV DOAS and similar measurements conducted using a hand held instrument across the width of the roof vent showed that the Hg0 concentrations were relatively consistent across the vent and compare reasonably well to the average concentration obtained with the UV DOAS.

Comparison of roof vent monitoring data obtained by the UV DOAS and point measurements made using a Tekran Model 2537A automated Hg analyzer at the entrance to the vent exhibited a relatively high degree of scatter with only about 63% of the variance explained by linear regression. The data do, however, show comparable trends in Hg0 concentration with time. Scatter in the data is potentially due to a combination of factors including differences in analysis method, non representative sampling, and sampling line losses.

The SF6 tracer gas results obtained using the long path FTIR in the roof vent were found to be unusable for the purpose of determining volumetric air flow due to optical saturation of the detector.

Results of the 24 hour, time integrated bag sampling showed SF6 tracer gas concentrations either at or below the instrumental detection limit except for one sampling period on February 20, 2000. 11

The average roof vent air velocity measured by a hand held anemometer as compared to that obtained by the optical anemometer showed that the two methods agreed within ± 10 %.

Very good closure ( 79 to 100%) was obtained for each of the three air flow balance calculations performed for the cell building. The three methods also correlate well with each other, and the high degree of closure of these flow balances lends further credibility to the air velocity measurements made by the optical anemometer in the roof ventilator.

No specific pattern could be discerned from daily plots of Hg0 emission rates. Various episodic events were observed during the study where the emission rate rose for a period of time, then dropped back to some nominal level which could not be correlated to either process operation or maintenance events using plant records.

Although the concentration of Hg0 was found to be relatively homogeneous across the lateral dimension of the roof vent, concentrations of Hg0 were not consistent along the length of the ventilator.

On the basis of the results obtained for this study, the following recommendations are applicable:

This study was conducted at one chlor alkali plant, in a time window of approximately 2 weeks. For more thorough characterization of operations in this industry, extended monitoring at a single location and/ or monitoring at more plants is recommended to better characterize maintenance events and other operational transients. Better monitoring of these transients is also needed.

Roof vent instrumentation may be a useful tool for process monitoring in some facilities to identify problems in the operation of the cells that may require corrective action. The long term suitability of these instruments must be established, however, by additional on site evaluations.

The high electromagnetic field at the facility had an adverse effect upon instrument operation. For future studies of this type, optical modems and cables should be used to allow logging of data at a remote location to reduce data loss and make troubleshooting much easier for the operator.

The variation in Hg0 concentrations along the length of the ventilator vs. the homogeneous values observed for Hg0 across the lateral dimension argue strongly for the use of spatially integrated measurements rather than point sampling with a manifold system.

Roof vent tracer gas data in this study were not usable. Since the use of a tracer is well accepted for determining flow rates, the possibility of tracer gas analyses for future flow measurement studies should not be abandoned. Greater care is needed, however, to verify proper instrument setup and operation. 12

The possibility of using different tracer gases has been discussed. Some of these candidate tracer gases ( e. g., carbon tetrafluoride) can be determined using UV DOAS, making concurrent sampling and analysis of mercury and tracer gas highly desirable. Additional research is also recommended to determine the best way to diffuse the tracer gas into the cell room.

Additional measurements of non elemental ( oxidized) forms of Hg should also be conducted to determine their overall environmental significance. 13 SECTION 3 PROCESS DESCRIPTION AND OPERATION 3.1 General Process Description In Hg cell CAPs, Hg0 is used as a flowing cathode in electrolytic cells. The Hg electrolytic cell consists of an electrolyzer and a decomposer. In the electrolyzer section, a sodium chloride ( NaCl) brine solution flows concurrently with the Hg0 cathode. A high current density is applied between the Hg0 cathode and metal anodes. Chlorine gas ( Cl2) forms at the anode and a sodium amalgam forms at the Hg0 cathode. The amalgam is separated from the brine in a discharge end box and then enters the decomposer section, where deionized water is added. In the decomposer, the amalgam becomes the anode to a shortcircuited graphite cathode resulting in formation of hydrogen ( H2) gas and sodium hydroxide ( NaOH), and conversion of the amalgam back to Hg0. The Hg0 is then recycled to the inlet end box, where it reenters the electrolyzer. Cell surface temperatures of ~ 66  C ( 150  F) and decomposer surface temperatures of ~

116  C ( 240  F) are typical at the Olin facility.

The chlor alkali electrolysis process results in the manufacture of Cl2, H2, and NaOH caustic solution. Of these three, the primary product is Cl2. The overall process reaction is:

2NaCl + 2H2O

Cl2 + H2 + 2NaOH ( 3 1)

Figure 3 1 is a general diagram of the mercury cell process.

3.2 Plant Operation The basic process flow diagram for the Olin Corporation's Augusta, GA, facility is shown in Figure 3 2. As can be seen, the plant produces NaOH, H2, and Cl2 as described above plus HCl and 14 Brine Saturation Sodium Chloride Precipitation Filtration Cooling Electrolysis Amalgam Decomposition Cooling Mercury Removal Raw Brine Mercury Hydrogen Dechlorination Cooling Mercury Removal Storage Sodium Hydroxide Diluted Brine Caustic Solution Hydrochloric Acid Analyte Amalgam Water Caustic Solution Hydrogen Precipitants Residue Hydrochloric Acid Cooling Drying Chlorine Gas Compression Chlorine Figure 3 1. Simplified diagram of the mercury cell process. DC Electric Power Sodium Chloride Water Chlorine Gas Chlorine Gas Chlorine Gas Chlorine Electrolytic Cells 98% Acid Drying Towers Chlorine Compressors Refrigeration Liquid Chlorine Decomposers Reactors Hydrochloric Acid Unit Water Water Sulfur Dioxide Sodium Amalgam Sodium Amalgam Hydrogen Compressor Hydrogen Gas 50% Sodium Hydroxide Hydrochloric Acid Liquid Sodium Hydrosulfite ( Reductone and Hydrolin )

R R Figure 3 2. Process flow diagram for Olin Augusta.

14 16 liquid sodium hydrosulfite. A description of the various buildings and processes at the facility as provided by Olin can be found in Appendix A.

The Olin facility has a total rated output of 309 Mg/ day ( 340 short tons/ day) of Cl2, 348 Mg/ day ( 383 short tons/ day) of NaOH, and 8.2 Mg/ day ( 9 short tons/ day) of H2 produced by the 60 cells in the building. According to plant records provided to the research team, the process was operated at a relatively constant production rate except for a few brief periods when cells were taken off line for maintenance.

3.3 Cell Building The cell building at the Olin facility is a single fiberglass and steel structure approximately 62 m ( 204 ft) long by 34 m ( 112 ft) wide which is generally oriented in a east/ west direction. The peak of the building is located approximately 16 m ( 51 ft) above grade with a single monovent ( Figures 3 3a and 3 3b)

running its entire length.

The Hg cell building consists of two floors. The ground floor ( basement) is used for storage tanks and various other process equipment and, except for the Reductone ® area, is open to the atmosphere on three sides. The Hg cells and associated decomposers are mounted on a support structure on the cell room floor which is open to the basement below except for concrete aisles along the edges and through the center of the cell array. In this configuration, each cell is exposed to ventilation air used for cooling or worker protection.

The cell building houses the 60 electrolysis cells ( Figures 3 4 and 3 5) containing a total estimated Hg inventory of ~ 169,000 kg ( 372,000 lb). In 1997, 7,444 kg ( 16,411 lb) of " virgin" makeup Hg was supplied to the cells ( Rosario, 2001). This amount of makeup Hg represents ~ 5% of the total quantity used by all plants in the chlor alkali industry during that year ( Rosario, 2001).

The electrolytic cells in the Olin cell building are mounted in two rows of 30 units each which run east to west ( Figure 3 6). The cell rows are separated by a ~ 2.4 m ( 8 ft) wide aisle running along the centerline of the building with other, ~ 3.4 m ( 11 ft) wide aisles located along the perimeter of the cell rows to allow access for equipment maintenance. The decomposers used for Hg recovery ( Figure 3 7) are located on the end of each cell near either the north or south wall. 17 Figure 3 3a. Cell building showing interior of roof ventilator. 18 Figure 3 3b. Cell building showing exterior of roof ventilator ( from north). 19 48 ft 4 in. Cell Cutout Switch Anode Adjustment Hg Inlet End Anode Frame Amalgam Return Line Cell Cover Clamps Copper Studs Rubber Cell Cover Chlorine Outlet Air Switch For Pneumatic Operation of Cell Switches Brine Feed Waste Water To Sewer To Decomposer Amalgam Return Line 0 Figure 3 4. Electrolyzer used at the Olin Augusta plant. 20 10 ft Floor Level Amalgam Return Line Cell Suports Upper Cell Cover Flexible Copper Bus Graphite Anode Graphite Anode Plates Horizontal View Outlet End Box View Depleted Brine Header 10 in. & 12 in.

To Sewer Amalgam Return Line Flush Gate Handle 7 ft 5 in.

Figure 3 5. Mercury cell: horizontal view and outlet end box view. 21 Figure 3 6. North line of electrolytic cells in Olin cell building. 22 Figure 3 7. Decomposer used at the Olin Augusta plant. H Outlet 2 Caustic Outlet Hg Distributor Tray 0 Water Feed To Decomposer Baskets Lump Carbon Packing Hg to Pump Tank 0 Perforated Plates Screens Amalgam Return Decomposer Seal Pot Figure 3 7. Decomposer used at the Olin Augusta plant. 23 The building is ventilated by natural convection with three sides of the basement and cell room floor ( except for the Reductone ® area) open to the atmosphere. During colder weather, two large sliding doors on the west end of the cell room floor can be closed to reduce ventilation. Also, various 1.1 m ( 3.7 ft) high panels located on the north and south sides of the building can be either removed or replaced as ambient conditions dictate.

To further assist with ventilation of the cell room, 13 large axial blade fans located in and along the walls can also be operated, as needed, depending on ambient temperature. Each of these fans is rated at 626 actual m3/ min ( 22,100 actual ft3/ min) and is manually activated/ deactivated by operating personnel.

A general diagram of the cell building, showing the cell rows and general fan locations, is shown in Figure 3 8.

In general, the internal temperature of the cell room varies with the ambient outdoor temperature.

The impact of this variation on ventilation rate is discussed in further detail in Section 4.2.3 below.

In the northwest corner of the cell building is the Reductone ® process area. This area contains reactors used for the production of 303,000 L/ day ( 80,000 gal./ day) of liquid sodium hydrosulfite which is operated from a separate control room in that part of the building. Since sodium amalgam from the electrolytic cells is used in this process, the Reductone ® area is also a source of fugitive Hg emissions.

Finally, based on observations made during the study, the Olin chlor alkali plant appeared to be a very well operated and maintained facility. General housekeeping of the cell building and adjacent areas was excellent and the Olin staff were found to be highly motivated to reduce Hg emissions from the process. Periodic maintenance was also performed throughout the study period as part of the normal operation of the cell building. In addition, two specific maintenance events expected to generate elevated Hg levels were monitored: a cell opening and a decomposer " basket" changeout. To facilitate maintenance,

both operations were conducted after the equipment had been taken off line and allowed to cool. ( Note that cooling of hot process equipment before opening is not only a good maintenance practice, but also a good engineering practice to minimize release of Hg emissions.) Neither of these events resulted in abnormally high Hg0 concentrations either in the area adjacent to the maintenance activity or in the roof vent. 24 Sulfur Dioxide Storage Tank Reductone Reactors Hg Collection Area Reductone Truck Fill Area Large Sliding Doors Cell Row ( 30 Cells)

Cell Row ( 30 Cells)

Control Room Cooling & Drying Brine Dechlorination & Head Tank Spent Acid Pumps & Sump Spent Acid Tanks Rectiformers X = Approx. location of 13 ventilation fans in walls X X X XX X X X X X XX X ~ 8 ft ~ 11 ft ~ 9 ft 48 ft 4 in.

Figure 3 8. General diagram of the cell building showing cell rows, general fan locations, etc. 25 SECTION 4 EXPERIMENTAL PROCEDURES This section provides detailed information on the field measurements conducted during the period February 17 to 25, 2000. Both the manual and automated techniques are described along with the procedures used to reduce and analyze the experimental data.

4.1 Measurement Methods, Setup, and Calibration A combination of measurement methods was used for data collection at the Olin chlor alkali facility. Past studies of this type show that parallel approaches reduce the overall uncertainty of the estimates and provide useful constraints on measurement accuracy. The methods used were: roof vent monitoring, tracer gas analyses, and manual velocity measurements. Each is described in detail below.

4.1.1 Roof Vent Monitoring The basic measurement approach used in this portion of the research was the " roof monitor method" developed in the late 1970s for fugitive emissions ( Cowherd and Kinsey, 1986). In this particular study, however, long path instruments were used in lieu of extractive sampling using a manifold system ( EPA, 1984). The use of long path instruments allows measurements to be made on a spatially integrated basis, thus eliminating problems with representative sampling typical of point measurements.

The primary instrumentation used in the roof vent consisted of:

UV DOAS for the measurement of Hg0 concentration;

Optical scintillometer ( anemometer) for the determination of air velocity; and

FTIR spectrometer for the measurement of SF6 tracer gas concentration. 26 This equipment was selected because it has been used successfully for testing of similar emissions in other industries monitoring roof vents. In fact, the Model LOA 104 optical anemometer has recently received an EPA Reference Method 14 equivalency designation for the determination of air velocity in aluminum pot room roof vents ( EPA, 1984; Hunt, 1998). The long path instruments used for roof vent monitoring are described in Table 4 1.

Table 4 1. Roof Vent Instrumentation Parameter Monitored Type of Instrument Manufacturer Model No. Optical Configurationa Gas phase Hg0 UV DOAS OPSIS   , Inc. Model AR 500 Bi static Air velocity Optical scintillometer ( anemometer) Scientific Technology Model LOA 104b Bi static SF6 tracer gas concentration FTIR Environmental Technologies Group Air Sentry Mono static a Bi static = separate light source and receiver; mono static = combination light source and receiver in one unit. b Modified with a 2 in. aperture in place of the standard 6 in. aperture for path lengths < 100 m.

The long path instruments were mounted on wooden sampling platforms erected at the east and west ends of the cell building roof vent ( Figure 4 1). The UV DOAS receiver, FTIR, and optical anemometer transmitter were located on the west platform with the UV DOAS transmitter ( light source), a retroreflector, and the optical anemometer receiver mounted on the east platform. Except for the optical anemometer, the signals from all instruments were directed by optical fiber to computerized data acquisition systems ( DASs) located in a trailer parked directly beneath the roof ventilator at the west end of the cell building. For the optical anemometer, the microprocessor and associated laptop computer used for data acquisition were located on the sampling platform itself. This arrangement was necessary due to the high electromagnetic field which precluded the use of the low voltage modems supplied with the instrument.

Due to practical considerations, the optical measurement path of all the instruments was positioned slightly above the exit plane of the ventilator " throat" as shown in Figure 4 2. 27 Figure 4 1. Cross section of roof ventilator showing internal structure. 28 Figure 4 2. From left to right, the FTIR retroreflector, UV DOAS light source, and optical anemometer receiver unit installed on the east sampling platform. 29 Each instrument was set up and calibrated according to the operating manual and/ or approved Quality Assurance Project Plan ( QAPjP) for the study ( Kinsey et al., 2000). For the UV DOAS, both the transmitter and receiver units were bolted to steel plates attached to the internal building structure at the approximate centerline of the vent cross section. Instrument calibration was performed at the beginning and end of the study using a sealed Hg gas cell placed in the measurement path. Daily checks of instrument performance were made by OPSIS ® personnel who operated and maintained the UV DOAS during the course of the study.

For operation of the optical anemometer, the transmitter and receiver were bolted directly to the wooden platform on the south side of the roof vent centerline. The instrument was initially compared against a standard unit evaluated in the National Institute for Standards and Technology ( NIST) low speed wind tunnel and thus is considered to be NIST traceable. Since a dynamic calibration could not be performed on site, daily quality control ( QC) checks were made each morning using the electronic calibrator supplied with the instrument. In addition, two sets of manual velocity measurements were also made as a comparison with the readings made by the optical anemometer as described below.

The open path FTIR and associated retroreflector were also bolted to the wooden platforms on the north side of the roof ventilator centerline. The instrument was calibrated both before and after the main data collection period using a nitrogen purge followed by 500 ppmv n butane and 25 ppmv SF6 according to EPA Method TO 16 ( EPA, 1999). Daily QC checks were also made by the instrument operator. A diagram showing the location and beam path of each long path instrument relative to the roof vent cross section is shown in Figure 4 3.

Finally, a Met One Model 062 temperature controller and meteorological station and associated laptop computer were also installed on the west sampling platform to monitor air temperature and relative humidity. This system provided 15 min average data for these two parameters as logged by the computer.

( Note that the high electromagnetic field precluded the transfer of electronic files from the meteorological station computer in situ and thus the data were provided as hard copy output directly from the computer.)

Note, however, that the meteorological station was not available until about midday on February 21, and thus temperature and humidity data are not available for the entire study. The available data were analyzed, however, to estimate the air temperature for periods where actual monitoring was not conducted.

Ambient data for the study period were also obtained either from 30 0.0 1.0 2.0 3.0 4.0 0 10 20 30 40 50 60 Dis tan ce fr om We s t Buildin g Wall, m Distance from South Vent Wall, m LOA DOAS FTIR Figure 4 3. Relative locations of instrument beam path in roof vent cross section.

on site meteorological monitoring conducted by study collaborators or from National Weather Service ( NWS) archives for Bush Airport located ~ 2.4 km ( 1.5 mi) north of the facility.

With regard to on site data processing and storage, the raw data stream from each instrument was continuously logged and accumulated by the associated DAS. For QC purposes, a copy of each instrument data file was made by the EPA Work Assignment Manager on a daily basis and stored separately both in electronic format and as hard copy. The hard copy data were stored in ring binders to provide a permanent record for the study.

4.1.2 Manual Tracer Gas Analyses The SF6 tracer gas concentration was measured inside the Hg cell building by ERG's Optical Measurements Group using manually operated bag samplers and a closed cell Nicolet Magna 760 FTIR to analyze the gas samples. The roof vent and upwind/ downwind monitoring was conducted using EPA operated FTIRs to determine tracer gas concentrations. All analyses and measurements for the tracer gas were completed following EPA Method TO 16 ( EPA, 1999). 31 Manual sampling was accomplished by drawing sample air into a Tedlar ® bag over a nominal 24 hour period. Tedlar ® bags were used for air sampling, and were constructed of a material that minimizes adsorption of many ambient air chemical species. Tedlar ® bags will be referred to as " bags" for the remainder of this section. A bag sampling location consisted of a rigid container with an enclosed bag,

a sample pump to pull a vacuum on the container, and associated flow measurement and control devices ( rotameters).

Sampling was achieved by placing an evacuated bag inside the container, sealing the container, and attaching a pump and sampling lines to the container. The sample pump was started and withdrew air from the container, creating a vacuum within the container which then inflated the bag by drawing in sample air.

Sampling rate was controlled by adjustment of the pump flow rate.

Multiple sampling locations were used to obtain a distribution of tracer concentration at key locations in and around the cell building. The locations were sampled nearly simultaneously for approximately 24 hours. Sampling locations were determined based on estimated air flow patterns and/ or wind conditions prior to sampling.

Prior to sampling, all equipment was inspected for proper operation. Bags were inspected for integrity, and the sampling containers were inspected and tested for leaks. When all equipment passed inspection, the equipment was placed in its designated sampling location and assembled. All clocks used during sampling were synchronized with a master clock set to the atomic clock in Boulder, CO.

Due to the density difference between air and SF6, all flowmeters were calibrated with tracer gas before sampling using a manual Buck calibrator. After the bag samples were obtained, they were removed from the rigid container ( 10 gal. drum), labeled, and transported to the trailer for analysis. All samples were analyzed at Olin using the ERG Nicolet FTIR.

The bag samples were analyzed by FTIR spectroscopy because of the high sensitivity of FTIR to SF6 and the ability of FTIR to simultaneously detect many other analytes of interest. The FTIR operating parameters are given in Table 4 2. These parameters provide acceptable detection limits for the target analytes anticipated in this study. 32 Table 4 2. Typical FTIR Operating Parameters Parameter Value Spectral Range ( cm 1) 400  4000 Spectral Resolution ( cm 1)

0.5 Optical Cell Pathlength ( m) 10 ( approximate)

Optical Cell Temperature (  C) Ambient ( nominally 25  C)

Sample Volume ( L) 3 Integration Time ( min) 6 ( Average of 256 interferograms)

Prior to each day's analysis, the FTIR instrument was checked for proper operation, and a background spectrum was collected using ultra high purity nitrogen. A background spectrum was considered a zero response measurement. After the background spectrum was collected, QC measurements were performed at nominal SF6 concentrations of 0.1 and 0.5 ppm ( volume). QC results are described in detail in Section 6.

4.1.3 Manual Velocity Measurements Manual anemometer measurements were also performed as part of the study. The objective of these measurements was to evaluate air velocity in the roof vent as an independent check on the optical anemometer as well as to determine the air velocity in various building openings for the purpose of performing an overall flow balance for the cell building.

The original study design proposed the use of three specially designed " anemometer trees"

( ATREEs) for the determination of air velocity and air flow. The ATREEs consisted of multiple thermal anemometer probes which were mounted on a movable metal mast and connected to a central data logger.

Upon initial deployment, however, it was determined that the thermal anemometers used in the ATREEs were far too sensitive for these measurements and immediately went off scale. Therefore, a hand held,

Davis Instruments TurboMeter ® propeller anemometer was used for the manual velocity measurements.

This instrument is capable of integrated air velocity measurements down to 0.1 m/ s and thus was well suited to this particular application. The propeller anemometer was also compared with a hand held 33 hot wire instrument during selected measurement periods. Since propeller data were available for all of the manual measurements, only this information was used in the analyses described below.

Propeller anemometer readings were obtained both in the roof ventilator and in cell building openings. For the vent measurements, readings were made at selected locations across the width of the ventilator throat both at the same height as the optical anemometer measurement path and also ~ 20 cm ( 8 in.) below the throat exit. For the various building openings, anemometer readings were obtained at the approximate geometric center of each opening. All data collected during the manual velocity measurements were recorded by hand in a bound field notebook.

4.2 Data Reduction and Analysis The data reduction and analyses conducted in the study are described below. Copies of the Excel ® spreadsheets containing the reduced data are appended, as appropriate.

4.2.1 Roof Vent Monitoring For the Hg0 concentration measurements made by the UV DOAS, the raw 30 sec average values generated by the spectrometer were downloaded directly from the instrument in the form of an ASCII text file for each day of the study. The individual text files were then imported into separate pages of an Excel ® spreadsheet where the data were checked for any obvious errors or anomalies. Any entries in the spreadsheet which appeared corrupted or questionable were deleted, the remaining information plotted as a chronology, and summary statistics calculated for each 24 hr period. In addition, a second data set consisting of 1 min averages was downloaded from the DAS for the purpose of the emission rate calculations. These data were analyzed in a similar fashion except that graphs and summary statistics were not generated.

A similar procedure was also used for analysis of the optical anemometer results. In this case,

however, raw 1 min averages were generated by the instrument and were imported as ASCII text files into the spreadsheet pages. Due to the high electromagnetic field and subsequent frequency of corrupted data,

special care was taken to check each data line prior to further reduction and analysis. Note, however, that the data generated by the optical anemometer were provided at actual roof vent temperature and pressure, 34 whereas the DOAS results were reported at a constant temperature of 30  C ( 86  F) and pressure of 760.7 mm Hg ( 29.95 in. Hg). Therefore, an appropriate temperature and pressure correction was applied to the optical anemometer results prior to the two data sets being used to calculate Hg0 emission rates.

For the roof vent meteorological station, the temperature and humidity data were entered by hand into a spreadsheet from the hard copy records. The data entries were then checked by the analyst for accuracy. These data were later combined with applicable ambient temperature information to make the necessary corrections for the emission rate calculations described below.

Finally, probably the most complex data set to be analyzed was that obtained from the roof vent FTIR. This data set consisted of individual infrared ( IR) spectra generated by the instrument from 64 separate scans conducted over a time period of approximately 5 min. The individual spectra were analyzed by post processing to determine the concentration of SF6 and other gases of interest.

Data files containing the FTIR spectra were provided to two separate EPA contractors for post test data reduction and analysis. An initial set of ~ 300 spectra collected late in the study was first provided to Jeff Childers of ManTech, Inc., who developed the basic spectral analysis scheme and provided a quality control check of the data ( Appendix B). A complete set of spectra ( including those provided previously to ManTech) was also furnished to EPA's in house contractor ( ARCADIS Geraghty & Miller) who conducted a separate analysis ( Appendix C) of the information generated in the field using the methodology developed by Childers.

As stated in Childers' report ( Appendix B), the FTIR detector was found to be optically saturated due to poor instrument setup in the field. Because of detector saturation, the response of the instrument is highly non linear, making quantitative interpretation of the spectra impossible. Therefore, the entire data set was considered to be unuseable for the quantitative determination of air flow rate from the cell building.

The data are of some qualitative interest, however, as discussed in Section 5.

4.2.2 Tracer Gas Analyses The SF6 tracer gas was released as a diffuse line source along the centerline of the cell room. The tracer was provided from two separate compressed gas cylinders through a ` soaker hose' running the length 35 of the building. Figure 4 4 shows the cylinder layout along the cell building basement. Figure 4 5 shows the soaker tubing layout inside the cell room.

Gas was metered from the cylinder using a pressure regulator and precision rotameter which was calibrated in the field with SF6 using a bubble test meter prior to use. Single point calibration checks 36 G1 F1 E1 D1 C1 B1 60 30 31 58 59 29 1 3 2 G11 A11 A1 D2 D3 D4 D5 D11 North South Column number along basement All columns continue from 1 to 11 Rotameters 1 & 2 on cell room floor 1 2 3 4 SF6 cylinder SF6 cylinder Cell numbers Rotameter 3 on cell room floor; Rotameter 4 in basement Rotameter 4 and soaker tubing was along basement on 2/ 23 and 2/ 24/ 00 Figure 4 4. Cylinder layout along the cell building basement.

60 30 31 58 59 29 1 3 2 North South Rotameters 1 & 2 1 2 3 Rotameter to SF6 cylinders in basement continue cells 31 to 58 continue cells 3 to 29 Cells 1 29 & 59 on Northside Cells 30 58 & 60 on Southside Reductone Area TM to SF6 cylinders in basement Figure 4 5. Soaker tubing layout inside the cell room. 37 were made at the beginning, middle, and end of the tests. Calibration checks are presented in Section 6 ( Quality Assurance/ Quality Control).

The total average gas release for the first 3 days of sampling, February 17 through February 20,

2000, was 137.4 g/ min. Gas concentration was increased on February 21, 2000, because the FTIR instrument was detecting baseline amounts of SF6. The average release from February 21 to 23, 2000, was 248.1 g/ min. Because there was still a problem with the detection of SF6 from the long path roof vent FTIR, the rotameters were exchanged and calibrated, and a higher flow was set to run the last 2 days of sampling, February 23 and 24, 2000. The average release was 3356.0 g/ min. Gas release concentrations are listed in Table 4 3.

4.2.3 Emission Rate Calculations Using the data sets described in Section 4.2.1 above, the emission rate for each 1 min averaging period was calculated according to:

( 4 1) E 60VcAeC( 10) 6 =

Where:

E = Hg 0 emission rate ( g/ min); Vc = air velocity obtained from optical anemometer corrected for temperature and pressure ( m/ s); Ae = effective flow area of vent ( m2); and C = Hg 0 concentration as measured by the UV DOAS ( µ g/ m3).

The corrected air velocity was calculated by Equation 4 2 as:

( 4 2) Vc Va TrPa TaPr =

Where:

Va = air velocity obtained from optical anemometer at actual conditions ( m/ s); Tr = reference absolute temperature ( 303 K); 38 Table 4 3. Gas Release Concentrations Date Time Rotameter Concentration mL/ mina SF6 Concentration ( g/ min) b Comments Rotameter Site Locationc Total Flow Rotameter Site Locationc Total Flow 1 2 3 4 1 2 3 4 2/ 17 18: 30 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 Density of SF6 = 5.13 g/ mL 19: 00 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 2/ 18 9: 00 20.9 3.5 21.1 45.5 107.2 17.7 108.3 233.2 9: 01 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 10: 00 8.8 6.6 9.4 24.8 45.0 34.1 48.1 127.1 11: 30 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 12: 10 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 16: 00 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 17: 10 8.8 6.1 9.4 24.3 45.0 31.4 48.1 124.4 17: 11 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 17: 30 8.8 6.1 8.4 23.2 45.0 31.4 42.9 119.2 17: 31 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 17: 45 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 18: 00 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 2/ 19 7: 40 7.8 16.8 17.8 42.3 39.9 86.0 91.1 217.0 7: 41 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 9: 00 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 10: 15 8.8 5.6 6.0 20.4 45.0 28.6 30.9 104.5 10: 16 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 10: 50 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 11: 45 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 12: 45 7.8 6.9 9.4 24.1 39.9 35.5 48.1 123.5 12: 46 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 13: 39 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 14: 30 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 14: 57 8.8 6.6 9.4 24.8 45.0 34.1 48.1 127.1 14: 58 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 16: 40 8.8 7.4 9.4 25.6 45.0 38.2 48.1 131.2 17: 00 7.1 6.1 9.4 22.6 36.6 31.4 48.1 116.0 17: 01 8.76 7.44 9.37 25.6 45.0 38.2 48.1 131.2 2/ 20 8: 30 8.76 19.4 24.5 52.7 45.0 99.7 125.5 270.1 8: 31 8.76 7.44 9.37 25.6 45.0 38.2 48.1 131.2 9: 30 8.76 7.44 9.37 25.6 45.0 38.2 48.1 131.2 10: 30 7.78 7.44 9.37 24.6 39.9 38.2 48.1 126.2 10: 31 8.76 7.44 9.37 25.6 45.0 38.2 48.1 131.2 11: 00 5.49 6.11 11.0 22.6 28.1 31.4 56.7 116.2 Average in g/ min 137.4 11: 01 8.76 7.44 9.37 25.6 45.0 38.2 48.1 131.2 2/ 20 15: 00 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 16: 00 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 ( Continued) Table 4 3. ( Continued)

Date Time Rotameter Concentration mL/ mina SF6 Concentration ( g/ min) b Comments Rotameter Site Locationc Total Flow Rotameter Site Locationc Total Flow 1 2 3 4 1 2 3 4 39 2/ 21 8: 30 13.7 16.8 21.1 51.6 70.2 86.0 108.3 264.5 8: 31 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 9: 30 13.7 10.1 12.7 36.5 70.2 51.9 65.3 187.3 9: 31 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 10: 35 13.7 8.78 11.0 33.5 70.2 45.0 56.7 171.9 10: 36 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 11: 40 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 2/ 22 10: 15 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 11: 00 13.7 8.78 11.0 33.5 70.2 45.0 56.7 171.9 11: 01 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 11: 20 13.7 8.78 11.0 33.5 70.2 45.0 56.7 171.9 11: 21 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 12: 00 15.0 8.78 11.0 34.8 76.9 45.0 56.7 178.6 12: 01 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 14: 00 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 15: 00 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 19: 40 13.7 11.2 14.1 38.9 70.2 57.3 72.2 199.7 19: 41 13.7 11.4 14.4 39.5 70.2 58.7 73.9 202.8 Average in g/ min 248.1 2/ 23 10: 00 47.7 66.9 35.0 149.7 244.9 343.4 179.7 768.0 10: 01 47.7 43.1 47.2 138.0 244.9 221.3 242.0 708.2 New rotameters 2/ 23 11: 30 59.4 43.1 47.2 51.2 200.9 304.7 221.3 242.0 262.8 1030.8 14: 00 59.4 43.1 47.2 51.2 200.9 304.7 221.3 242.0 262.8 1030.8 Average in g/ min 1606.3 16: 15 59.4 209.7 217.1 51.2 537.5 304.7 1076.0 1113.9 262.8 2757.3 2/ 24 8: 30 176.1 209.7 217.1 51.2 654.2 903.4 1076.0 1113.9 262.8 3356.0 11: 00 176.1 209.7 217.1 51.2 654.2 903.4 1076.0 1113.9 262.8 3356.0 Average in g/ min 3356.0 13: 00 176.1 209.7 217.1 51.2 654.2 903.4 1076.0 1113.9 262.8 3356.0 a Reading in mL/ min = ( Flowmeter reading mL/ min * slope) + y intercept. Slope and intercept were obtained for initial day that the flowmeters were calibrated. b Concentration in g/ min = density in g/ mL x mL/ min [ Density of SF6 = 5.13 g/ mL]. c See Figures 4 4 and 4 5 for rotameter site locations. 40 Pa = actual barometric pressure ( mm Hg) = 1.006 Psta ; Psta = station pressure for Bush field ( mm Hg); 1.006 = altitude correction for Bush field; Ta = actual absolute temperature ( K) =  C + 273; and Pr = reference atmospheric pressure = 760.7 mm Hg.

To obtain the value of Ta in Equation 4 2, the temperature data obtained from the roof vent meteorological station were used, where available. However, for time periods when actual monitoring was not conducted, the available data were analyzed separately to estimate the vent air temperature.

To estimate roof vent air temperature, the available monitoring data were copied into a separate spreadsheet and the difference between the vent temperature and the ambient temperature calculated for each 15 min averaging period. The temperature differentials (  Ts) obtained from these calculations were then plotted on the same graph as a series of daily time histories. Upon examination of these plots, a similar daily trend in   T was observed, as would be expected for a naturally ventilated building.

Appropriate averages were then calculated from the 15 min monitoring results which were subsequently applied to the ambient temperature data for those time periods where actual monitoring was not conducted.

The time histories generated from the monitoring results and the average daily   T cycle calculated from these data are shown in Figures 4 6a and 4 6b, respectively. As shown by Figure 4 6b, the " artificial"

chronology developed from the average data is very similar to the daily trends actually determined from the monitoring results ( Figure 4 6a) and thus should be adequate to estimate vent air temperature.

Finally, the concentration, velocity, temperature, and pressure data described above were imported into an Excel ® spreadsheet and the Hg0 emission rate calculated for each 1 min averaging period using Equations 4 1 and 4 2. Also generated in the spreadsheet were summary statistics and a time history for each 24 hr period. A copy of this spreadsheet is provided in Appendix F. 41 11.0 12.0 13.0 14.0 15.0 16.0 17.0 0: 15 1: 30 2: 45 4: 00 5: 15 6: 30 7: 45 9: 00 10: 15 11: 30 12: 45 14: 00 15: 15 16: 30 17: 45 19: 00 20: 15 21: 30 22: 45 Tim e o f Day Delta Temperature ( ° C)

2 2  Feb 2 3  Feb 2 4  Feb 2 5  Feb Figure 4 6a. Average roof vent temperature differential as determined from 15 min monitoring data.

11.0 12.0 13.0 14.0 15.0 16.0 17.0 0 : 15 1: 30 2 : 45 4: 00 5 : 15 6: 30 7 : 45 9: 00 10: 15 11: 30 12: 45 14: 00 15 : 15 16: 30 17 : 45 19: 00 20: 15 21: 30 22 : 45 Tim e of Day Delta Temperature ( ° C)

Figure 4 6b. Calculated temperature differential for roof ventilator as determined from average monitoring data shown in Figure 4 6a. 42 4.2.4 Manual Velocity Measurements and Flow Balance Calculations For the manual velocity measurements in the roof vent, the data from the field notebook were entered by hand into an Excel ® spreadsheet ( Appendix D). These data were then plotted with respect to the physical boundaries of the ventilator throat and averages calculated for each set of observations. The averages were then compared to similar values obtained from the optical anemometer for the same time period. In addition, the data points obtained at both edges of the ventilator were extrapolated by linear regression to the point of zero velocity. These locations were then used to determine the effective flow area of the vent ( Ae) for the emission rate calculations shown in Equation 4 1 above.

In the case of the building openings, the manual velocity data were also entered by hand into an Excel ® spreadsheet ( Appendix E). These values were then multiplied by the cross sectional area of each opening as determined either from building drawings or field notes to determine volumetric flow rate. The individual flow rates were then combined with the total volumetric flow of the electrically powered ventilation fans to obtain the total ambient air entering the cell building. Similar calculations were also performed for the roof vent using the applicable optical anemometer data for the same measurement period and the effective flow area as described earlier.

To perform the flow balance for the building, three separate techniques were used. The first technique simply corrected the total flow obtained for the building inlets and roof vent to standard temperature and pressure and compared the two values on a volumetric basis. In the second method, the mass of air entering and leaving the building was calculated and a similar comparison made. Finally, a method developed by the Occidental Chemical Corporation ( OxyChem) as part of their direct mass balance ( DMB) modeling effort was also used. For the sake of consistency, all flow balance calculations were performed in English units as described in the following paragraphs.

In the first approach, the total flow for both the building inlets and the roof vent was corrected to a standard temperature of 77  F ( 25  C) and pressure of 29.92 in. Hg ( 760 mm Hg) according to:

( 4 3) Qs Qa TsPa TaPs = 43 Where:

Qs = volumetric flow rate at standard conditions ( ft3/ min); Qa = volumetric flow rate at actual conditions ( ft3/ min); Ts = standard absolute temperature ( 537  R); Ta = actual absolute temperature: (  R) =  F + 460; Pa = actual barometric pressure ( in. Hg) = 1.006 Psta; Psta = station pressure for Bush field ( in. Hg); 1.006 = altitude correction for Bush field; and Ps = standard atmospheric pressure = 29.92 in. Hg.

As shown by Equation 4 3 above, no correction for relative humidity ( water vapor) was made in the calculations.

Percent closure of the volume balance was then calculated as:

( 4 4) % Balance 100 Qin Qout Qin * 100 =

  Where:

Qin = volumetric air flow entering the cell building ( standard ft3/ min); and Qout = volumetric air flow exiting the roof ventilator ( standard ft3/ min).

In the second calculation scheme, a traditional mass balance was performed which compared the quantity of air entering the building through the various openings to that exiting the roof vent per unit time.

For these calculations, the partial pressure of water vapor in moist air ( pw) at the building inlet and outlet was found by ( ASHRAE, 1981):

( 4 5) p w p s =   Where:

pw = partial pressure of water vapor in moist air ( in. Hg/ in. 2);

  = relative humidity ( expressed as a fraction); and ps = vapor pressure of water in moist air at saturation ( in. Hg/ in. 2). 44 Equation 4 5 assumes that pw is approximately equal to the vapor pressure of saturated pure water ( pws)

which is generally accepted for most calculations ( ASHRAE, 1981).

Next, the volume of moist air per unit mass of dry air (  ) was found for the air entering and leaving the building by ( ASHRAE, 1981):

( 4 6)   =   RaT ( p pw)

Where:

  = volume of moist air per unit mass of dry air ( ft3 of mixture/ lbm dry air); Ra = ideal gas constant for dry air ( in. Hg/ in. 2 ° lbm  1 ° OR 1); lbm = pound mass of air ( engineering units); T = absolute temperature (  R); p = barometric pressure ( in. Hg/ in. 2 ); and pw = partial pressure of water vapor in moist air ( in. Hg/ in. 2) from Equation 4 5.

The mass of air either entering or leaving the building per unit of time was then calculated according to Equation 4 7:

( 4 7) M V =   Where:

M = mass of dry air per unit time ( lbm/ min); V = volumetric flow rate ( ft3/ min); and   = volume of moist air per unit mass of dry air ( ft3 of mixture/ lbm dry air) from Equation 4 6.

To assess the percent closure of the mass balance, Equation 4 8 was used:

( 4 8) % Balance 100 Min Mout Min * 100 =

  45 Where:

Min = mass of dry air per unit time entering the building ( lbm/ min) Mout = mass of dry air per unit time exiting the building ( lbm/ min)

Finally, the field data were entered into a special Excel ® spreadsheet developed by Michael Shaffer of OxyChem's Delaware City plant. This spreadsheet uses a slightly different approach to performing the mass balance which was adopted as an independent check on the calculations described above. 46 SECTION 5 RESULTS AND DISCUSSION This section provides the results of the Olin field study as obtained using the equipment, methods,

and data analysis procedures described in Section 4. Also included in this section is a discussion of key experimental results.

5.1 Mercury Monitoring Results The outcome of the roof vent monitoring conducted at the Olin cell building is discussed below.

Both the Hg0 emission rates calculated from the continuous monitoring data as well as comparisons of the UV DOAS results to other Hg0 measurement techniques are also described.

5.1.1 Monitoring Data and Mercury Emission Rates As discussed above, continuous monitoring was conducted at the roof vent for Hg0 concentration and air velocity from which 1 minute average Hg0 emission rates were calculated. In addition, continuous monitoring was also attempted for SF6 tracer gas as a separate measure of the air flow rate from the vent.

The results of these measurements are discussed below.

The raw 30 sec averages generated by the UV DOAS were reduced to produce daily plots of the Hg0 monitoring results as well as summary statistics for each day. The daily data plots are shown in Figures 5 1 to 5 9 with summary statistics calculated from the data provided in Table 5 1. As can be seen from Table 5 1, the measured Hg0 concentration varied over an order of magnitude from ~ 73 to 7.3 µ g/ m3.

The overall average for the study period was 24 µ g Hg0/ m3.

Similar plots and statistics were also created from analysis of the 1 min optical anemometer data as discussed in Section 4.1.1. The plots are shown in Figures 5 10 to 5 18 with summary statistics for each daily data set provided in Table 5 2. As shown in Table 5 2, the air velocities measured by the 47 48 0 10 20 30 40 50 60 70 11: 18 11: 56 12: 36 13: 15 13: 52 14: 30 15: 07 15: 45 16: 22 16: 59 17: 37 18: 15 18: 53 19: 30 20: 08 20: 45 21: 22 22: 01 22: 39 23: 16 23: 53 Time of Day HgO Concentration ( µ g/ m3 )

Figure 5 1. Time history of roof vent elemental mercury concentration for February 17, 2000.

0 10 20 30 40 50 60 70 0: 00 1: 07 2: 15 3: 22 4: 35 5: 41 6: 52 8: 05 10: 04 11: 11 12: 20 13: 26 14: 36 15: 42 16: 49 18: 05 19: 13 20: 19 21: 27 22: 35 23: 41 Time of Day HgO Concentration ( µ g/ m3 )

Figure 5 2. Time history of roof vent elemental mercury concentration for February 18, 2000. 49 0 10 20 30 40 50 60 70 0: 00 1: 06 2: 10 3: 14 4: 19 5: 23 6: 29 7: 33 8: 40 10: 08 11: 14 12: 19 13: 23 14: 34 15: 44 16: 55 18: 02 19: 12 20: 18 21: 24 22: 32 23: 39 Time of Day HgO Concentration ( µ g/ m 3 )

Figure 5 3. Time history of roof vent elemental mercury concentration for February 19, 2000.

0 10 20 30 40 50 60 70 0: 00 1: 05 2: 13 3: 21 4: 27 5: 32 6: 39 7: 45 8: 52 10: 19 11: 23 12: 29 13: 34 14: 41 15: 48 16: 57 18: 03 19: 08 20: 14 21: 19 22: 25 23: 36 Time of Day Hg0 Concentration ( µ g/ m3 )

Figure 5 4. Time history of roof vent elemental mercury concentration for February 20, 2000. 50 0 10 20 30 40 50 60 70 0: 00 1: 18 2: 29 3: 35 4: 42 5: 51 6: 57 8: 06 9: 44 10: 48 11: 52 12: 56 14: 00 15: 04 16: 12 17: 16 18: 24 19: 27 20: 31 21: 35 22: 38 23: 43 Time of Day Hgo Concentration ( µ g/ m3 )

Figure 5 6. Time history of roof vent elemental mercury concentration for February 22, 2000. 0 10 20 30 40 50 60 70 0: 00 1: 06 2: 13 3: 17 4: 24 5: 31 6: 34 7: 40 8: 51 10: 15 11: 23 12: 34 13: 46 14: 57 16: 03 17: 16 18: 29 19: 33 20: 36 21: 41 22: 48 23: 51 Time of Day Hg0 Concentration ( µ g/ m3 )

Figure 5 5. Time history of roof vent elemental mercury concentration for February 21, 2000. 51 0 10 20 30 40 50 60 70 0: 00 1: 00 2: 00 2: 58 3: 57 4: 53 5: 48 6: 47 7: 48 8: 58 10: 12 11: 15 12: 14 13: 19 14: 18 15: 24 18: 38 19: 47 20: 48 21: 46 22: 41 23: 41 Time of Day Hgo Concentration ( µ g/ m3)

Figure 5 8. Time history of roof vent elemental mercury concentration for February 24, 2000. 0 10 20 30 40 50 60 70 0: 00 1: 01 2: 06 3: 10 4: 14 5: 17 6: 20 7: 27 8: 34 9: 58 11: 20 12: 32 13: 37 14: 42 15: 46 16: 49 18: 02 19: 06 20: 20 21: 24 22: 31 23: 39 Time of Day Hg o Concentration ( µ g/ m 3)

Figure 5 7. Time history of roof vent elemental mercury concentration for February 23, 2000. 52 0 10 20 30 40 50 60 70 0: 00 0: 19 0: 40 1: 00 1: 20 1: 40 1: 59 2: 16 2: 38 2: 58 3: 18 3: 37 3: 56 4: 15 4: 38 4: 58 5: 15 5: 36 5: 54 6: 12 6: 32 6: 52 7: 11 7: 30 7: 50 8: 07 8: 26 Time of Day Hgo Concentration ( µ g/ m3 )

Figure 5 9. Time history of roof vent elemental mercury concentration for February 25, 2000.

Table 5 1. Summary of 30 sec Roof Vent DOAS Dataa Date Hg0 Concentration ( µ g/ m3) a No. of Observations ( n) b % Completenessb Maximum Minimum Mean Standard Deviation 2/ 17/ 00 56.6 15.5 27.4 6.01 1281 89 2/ 18/ 00 35.5 10.2 22.1 4.33 2553 89 2/ 19/ 00 38.8 7.32 16.8 4.83 2549 89 2/ 20/ 00 73.0 8.49 23.0 11.9 2553 89 2/ 21/ 00 71.3 8.43 19.0 9.00 2555 89 2/ 22/ 00 36.6 7.83 20.0 5.97 2544 88 2/ 23/ 00 40.0 10.5 21.2 7.03 2546 88 2/ 24/ 00 62.7 15.3 30.7 8.15 2317 80 2/ 25/ 00 51.1 19.3 34.7 7.13 922 89 Mean 51.7 11.4 23.9   88 a At 30

C and 29.95 in. Hg. Three significant figures. 53 b Dimensionless. Target value  75%. 54 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 10: 45 11: 26 12: 06 12: 49 13: 31 14: 11 14: 52 15: 32 16: 13 16: 53 17: 34 18: 15 18: 56 19: 36 20: 17 20: 57 21: 39 22: 19 23: 00 23: 40 Time of Day Air Velocity ( actual m/ s)

Figure 5 10. Time history of roof vent air velocity for February 17, 2000.

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 0: 00 0: 57 1: 54 2: 51 3: 50 4: 50 5: 46 6: 46 7: 45 8: 45 9: 41 10: 5411: 53 12: 4913: 4514: 4515: 41 16: 3817: 4218: 4019: 3720: 3321: 31 22: 28 23: 24 Time of Day Air Velocity ( actual m/ s)

Figure 5 11. Time history of roof vent air velocity for February 18, 2000. 55 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 0: 00 0: 59 2: 00 3: 02 4: 03 5: 01 6: 01 7: 02 8: 02 9: 02 10: 2111: 1912: 1813: 1714: 17 15: 1916: 2117: 21 18: 2219: 2020: 20 21: 18 22: 1823: 19 Time of Day Air Velocity ( actual m/ s)

Figure 5 13. Time history of roof vent air velocity for February 20, 2000. 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 0: 00 1: 29 2: 56 4: 24 5: 52 7: 20 8: 48 10: 40 12: 09 13: 38 15: 14 16: 49 18: 23 19: 55 21: 23 22: 54 Time of Day Air Velocity ( actual m/ s)

Figure 5 12. Time history of roof vent air velocity for February 19, 2000. 56 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 0: 00 1: 03 2: 06 3: 07 4: 10 5: 15 6: 16 7: 18 8: 20 9: 43 10: 4811: 53 13: 01 14: 07 15: 0916: 12 17: 19 18: 28 19: 28 20: 2921: 31 22: 34 23: 34 Time of Day Air Velocity ( actual m/ s)

Figure 5 14. Time history of roof vent air velocity for February 21, 2000.

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 0: 00 1: 04 2: 11 3: 09 4: 08 5: 10 6: 09 7: 08 8: 10 9: 39 10: 3511: 32 12: 2813: 2614: 2215: 2016: 2017: 1718: 16 19: 14 20: 1021: 0722: 0323: 0023: 57 Time of Day Air Velocity ( actual m/ s)

Figure 5 15. Time history of roof vent air velocity for February 22, 2000. 57 0.5 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 1.4 0: 00 0: 56 1: 56 2: 55 3: 53 4: 50 5: 50 6: 48 7: 49 8: 50 10: 12 11: 22 12: 2513: 2414: 2315: 2416: 21 17: 2718: 2619: 26 20: 3321: 31 22: 3523: 32 Time of Day Air Velocity ( actual m/ s)

Figure 5 16. Time history of roof vent air velocity for February 23, 2000.

0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 0: 00 1: 01 2: 07 3: 07 4: 09 5: 10 6: 09 7: 13 8: 15 9: 30 10: 4611: 49 12: 51 13: 52 14: 54 16: 0517: 19 18: 28 19: 41 20: 46 21: 48 22: 47 23: 50 Time of Day Air Velocity ( actual m/ s)

Figure 5 17. Time history of roof vent air velocity for February 24, 2000. 58 0.6 0.7 0.8 0.9 1 1.1 1.2 1.3 0: 000: 17 0: 350: 53 1: 1 1: 291: 47 2: 042: 21 2: 402: 583: 15 3: 343: 524: 10 4: 294: 505: 075: 23 5: 445: 596: 15 6: 346: 537: 11 7: 287: 468: 028: 208: 408: 57 Time of Day Air Velocity ( actual m/ s)

Figure 5 18. Time history of roof vent air velocity for February 25, 2000.

Table 5 2. Summary of 1 min Roof Vent Optical Anemometer Dataa Date Air Velocity ( m/ s) No. of Observations ( n) b % Completenessb Maximum Minimum Mean Standard Deviation 2/ 17/ 00 1.1 0.62 0.85 0.091 780 98 2/ 18/ 00 1.3 0.67 0.94 0.10 1380 96 2/ 19/ 00 1.3 0.70 0.97 0.10 1367 95 2/ 20/ 00 1.5 0.66 0.94 0.11 1372 95 2/ 21/ 00 1.3 0.58 0.89 0.12 1323 92 2/ 22/ 00 1.3 0.51 0.96 0.10 1347 94 2/ 23/ 00 1.3 0.24 0.91 0.13 1314 91 2/ 24/ 00 1.3 0.68 0.93 0.10 1264 88 2/ 25/ 00 1.3 0.76 1.0 0.083 492 90 Mean 1.3 0.60 0.93   93 a Measured at actual vent temperature and pressure. Two significant figures. 59 b Dimensionless. Target value = 90%. 60 optical anemometer varied from 0.24 to 1.5 m/ s with an overall average for the monitoring period of 0.94 m/ s.

The 1 min average Hg0 emission rates calculated from the monitoring data are plotted in Figures 5

19 to 5 27 for the 9 day study period. Summary statistics calculated from these data are shown in Table 5

3. As indicated by Table 5 3, the Hg0 emission rate varied over about 2 orders of magnitude from 0.08 to 1.2 g/ min. An overall average Hg0 emission rate for the monitoring period of 0.36 g/ min was also calculated from the data.

5.1.2 Comparison of Mercury Measurement Methods In addition to the continuous monitoring described above, the UV DOAS results were also compared to other measurement techniques performed by collaborators from the Oak Ridge National Laboratory ( ORNL). Each comparison is described below along with the results obtained.

In the first analysis, a comparison was made between the concentration of Hg0 measured by the UV DOAS and similar measurements conducted using a hand held instrument at various points across the width of the roof vent ( i. e., from north to south). This comparison was made to determine whether any stratification in the Hg0 concentration was evident across the width of the vent. The hand held measurements were made by ORNL using a Jerome Model 431 X survey instrument. ( Note that the Model 431 X uses an electrical resistance cell to measure Hg0, and thus the readings are not directly comparable to an optical method such as the UV DOAS. Also, the lower detection limit of the Jerome is 3000 ng/ m3 as compared to ~ 130 ng/ m3 for the DOAS.) The data obtained from this evaluation are summarized graphically in Figure 5 28.

As shown by Figure 5 28, the Hg0 concentrations determined by the Jerome instrument were relatively consistent across the width of the vent and compare reasonably well to the average concentration obtained with the UV DOAS. Based on these results, the measurements made by the UV DOAS were considered to be representative of the entire vent cross section and thus useful for the purpose of the emission rate calculations. 61 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0: 00 1: 04 2: 09 3: 12 4: 21 5: 26 6: 33 7: 41 8: 49 10: 43 11: 50 12: 53 13: 56 15: 03 16: 07 17: 12 18: 23 19: 28 20: 31 21: 37 22: 41 23: 44 Time of Day Hg o Emission Rate ( g/ min)

Figure 5 20. Elemental mercury emission rates for February 18, 2000. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 11: 18 11: 54 12: 32 13: 08 13: 44 14: 20 14: 55 15: 30 16: 06 16: 41 17: 17 17: 53 18: 28 19: 04 19: 39 20: 15 20: 50 21: 25 22: 02 22: 38 23: 13 23: 48 Time of Day Hg o Emission Rate ( g/ min)

Figure 5 19. Elemental mercury emission rates for February 17, 2000. 62 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 0: 00 1: 06 2: 15 3: 24 4: 31 5: 37 6: 46 7: 52 9: 00 10: 28 11: 33 12: 40 13: 46 14: 55 16: 03 17: 12 18: 20 19: 25 20: 32 21: 40 22: 46 23: 57 Time of Day Hg 0 Emission Rate ( g/ min)

Figure 5 22. Elemental mercury emission rates for February 20, 2000. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0: 00 1: 07 2: 12 3: 17 4: 23 5: 28 6: 35 7: 41 8: 48 10: 17 11: 24 12: 30 13: 37 14: 49 15: 59 17: 12 18: 21 19: 30 20: 38 21: 47 22: 52 Time of Day Hgo Emission Rate ( g/ min )

Figure 5 21. Elemental mercury emission rates for February 19, 2000. 63 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0: 00 1: 15 2: 27 3: 32 4: 38 5: 46 6: 51 7: 59 9: 36 10: 39 11: 42 12: 44 13: 48 14: 50 15: 58 17: 01 18: 04 19: 10 20: 12 21: 15 22: 18 23: 22 Time of Day Hg0 Emission Rate ( g/ min )

Figure 5 24. Elemental mercury emission rates for February 22, 2000. 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0: 00 1: 06 2: 13 3: 17 4: 24 5: 31 6: 34 7: 40 8: 51 10: 15 11: 23 12: 34 13: 46 14: 57 16: 03 17: 16 18: 29 19: 33 20: 36 21: 41 22: 48 23: 51 Time of Day Hg 0 Emission Rate ( g/ min)

Figure 5 23. Elemental mercury emission rates for February 21, 2000. 64 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0: 00 1: 00 2: 04 3: 07 4: 10 5: 12 6: 14 7: 20 8: 25 9: 47 11: 04 12: 20 13: 23 14: 27 15: 32 16: 34 17: 46 18: 46 19: 57 21: 04 22: 06 23: 15 Time of Day Hg o Emission Rate ( g/ min)

Figure 5 25. Elemental mercury emission rates for February 23, 2000.

0.00 0.20 0.40 0.60 0.80 1.00 1.20 0: 00 1: 00 2: 00 2: 58 3: 57 4: 53 5: 48 6: 47 7: 48 8: 58 10: 12 11: 15 12: 1413: 1914: 1815: 24 18: 38 19: 4720: 4821: 46 22: 4123: 41 Time of Day Hgo Emission Rate ( g/ min)

Figure 5 26. Elemental mercury emission rates for February 24, 2000. 65 0.00 0.20 0.40 0.60 0.80 1.00 1.20 0: 00 0: 20 0: 43 1: 04 1: 26 1: 46 2: 05 2: 25 2: 46 3: 09 3: 29 3: 50 4: 10 4: 31 4: 54 5: 13 5: 35 5: 54 6: 13 6: 346: 55 7: 17 7: 36 7: 56 8: 15 Time of Day Hgo Emission Rate ( g/ min)

Figure 5 27. Elemental mercury emission rates for February 25, 2000.

Table 5 3. Summary of Calculated Elemental Mercury Emission Ratesa Date Hg0 Emission Rate ( g/ min)

No. of Observationsb Total Daily Emissions ( g/ day) c Maximum Minimum Mean Standard Deviation 2/ 17/ 00 0.82 0.24 0.38 0.076 747 N/ A 2/ 18/ 00 0.58 0.15 0.33 0.075 1339 481 2/ 19/ 00 0.64 0.10 0.26 0.085 1364 370 2/ 20/ 00 1.2 0.13 0.35 0.19 1368 510 2/ 21/ 00 0.88 0.12 0.27 0.11 1311 387 2/ 22/ 00 0.69 0.12 0.31 0.080 1340 453 2/ 23/ 00 0.65 0.080 0.30 0.090 1300 438 2/ 24/ 00 0.83 0.24 0.46 0.12 1130 662 2/ 25/ 00 0.87 0.33 0.58 0.11 450 N/ A Mean 0.80 0.17 0.36   472 a Two significant figures. b Dimensionless. c Sum of measured 1 min values adjusted to standard day of 1440 min to account for missing data. 66 Three significant figures. 67 R o o f V en t L a te ra l H g 0 P rofile ( West P latform) F eb ru ary 2 1 , 2 0 00 0 5 10 15 20 25  1 .0 0 0 .00 1.0 0 2.0 0 3 .00 4.0 0 5.0 0 Dis tan ce f rom No r th Sid e o f V e n t ( m ) Hg0 Concentration ( 10 µ g/ m 3)

A vg . DOA S C o nc. = 2 0 ( 1 0 ) µ g / m3 Std . D ev. = 0 .7 5 µ g / m3 Figure 5 28. Lateral profile of elemental mercury concentration as determined by the Jerome 431 X instrument.

In the second analysis, monitoring data obtained by the UV DOAS were compared to point measurements made using a Tekran Model 2537A automated Hg analyzer operated by ORNL. The Model 2537A is a cold vapor atomic fluorescence spectrometer ( CVAFS) originally designed for ambient air monitoring which uses gold traps to preconcentrate the sample prior to analysis. The Tekran analyzer was located in the cell building control room with air samples collected from a high flow sampling line which extended to a point in the ceiling of the cell building ~ 5 m ( 16 ft) below the approximate center of the roof vent entrance.

Selected data from both instruments were imported into an Excel ® spreadsheet. The two data sets were time synchronized and plotted against each other, and a simple linear regression calculation performed on the data. The results of this analysis are shown in Figure 5 29.

As Figure 5 29 shows, the data exhibit a relatively high degree of scatter with only about 63% of the variance being explained by the linear regression. Possible reasons for these results include differences in analysis method, non representative sampling ( e. g., sample extraction at a single point vs. a pathaveraged method), and sampling line losses. The data do, however, show comparable trends in Hg0 68 concentration with time ( Figure 5 30) which may be useful for identifying process upsets or maintenance events as discussed below. 69 y = 0.6572x + 10.748 R2 = 0.6312 0 10 20 30 40 50 60 70 80 90 100 0 20 40 60 80 100 Tekran Hg 0 Concentration ( µ g/ m 3 ) DOAS Hg Conc. ( ug/ m )

3 o Figure 5 29. UV DOAS/ Tekran comparison ( February 17 21, 2000).

0 10 20 30 40 50 60 70 80 90 12: 00: 00 2/ 17/ 00 20: 37: 30 2/ 17/ 00 5: 12: 30 2/ 18/ 00 14: 32: 30 2/ 18/ 00 23: 50: 00 2/ 18/ 00 8: 25: 00 2/ 19/ 00 18: 15: 00 2/ 19/ 00 2: 50: 00 2/ 20/ 00 11: 25: 00 2/ 20/ 00 20: 05: 00 2/ 20/ 00 4: 40: 00 2/ 21/ 00 Date/ Time UV DOAS Tekran 2537 Hg Concentration ( ug/ m )

0 3 Figure 5 30. Chronology of elemental mercury concentration measured by OPSIS   Model AR 500 UV DOAS and Tekran Model 2537A CVAFS for February 17 21, 2000. 70 5.2 Tracer Gas Results The results of the tracer gas measurements are provided in the following paragraphs. These results include both the roof vent monitoring conducted using the open path FTIR and the manual bag sampling conducted in various building openings.

5.2.1 Roof Vent Monitoring As was discussed in Section 4.2.1 above, the FTIR results were found to be unuseable for the purpose of determining volumetric air flow due to optical saturation of the detector. However, the qualitative results are of at least some general interest.

In the analysis of the IR spectra, several trace gases other than SF6 were found in measurable amounts. These gases include carbon monoxide ( CO), nitrous oxide ( N2O), and methane ( CH4), all of which were estimated to be in concentrations above background. ( Note that background readings were obtained from the ambient FTIR located at the east plant road which was also operated by EPA as part of the larger study.) Although the emission rate of these compounds could not be quantified, it is interesting to note that three " greenhouse" gases were found in measurable quantities in the roof vent effluent. The exact source( s) of these gases could not be determined, however, from the available data.

5.2.2 Tracer Gas Study   Manual Bag Sampling The bags were sampled manually by drawing sample air into a Tedlar ® bag over a nominal 24 hour period. Multiple sampling locations were chosen ( Figure 5 31) to obtain a distribution of tracer concentrations at key building openings. This sampling process was conducted to obtain ambient levels of SF6 released along the open areas in the basement and in the cell room. If SF6 were detected, it would have indicated possible release of Hg along the vents from the cell building.

The sampling results for the manual bag analyses are presented in Table 5 4. The average concentration of SF6 for the low release days, February 17 through February 20, 2000, was 0.019 ppmv,

which is just over the detection limit of 0.008 ppmv. The average concentration for the high release 71 G1 F1 E1 D1 C1 B1 A1 60 30 31 58 59 29 1 2 3 D2 D3 D4 D5 D11 A11 G11 Bag sampling locations  shown in basement, although sampling was performed on both levels North South Figure 5 31. Bag sampling locations in cell building.

Table 5 4. Manual Bag Analysis Results Bag ID Site Description Date Taken Date Analyzed Reported Concentrations ( ppmv) Description Column Location Basement or Cell Room E8 22 Under Cell 8 G3 Basement 02/ 18/ 00 02/ 22/ 00 NDa E13 22 Under Cell 13 G8 Basement 02/ 18/ 00 02/ 22/ 00 ND A31 22 Under Cell 31 A3 Basement 02/ 18/ 00 02/ 22/ 00 0.016 A53 22 Under Cell 58 A8 Basement 02/ 18/ 00 02/ 22/ 00 0.014 B1 22 Southwest B1 Basement 02/ 18/ 00 02/ 22/ 00 ND Table 5 4. ( Continued)

Bag ID Site Description Date Taken Date Analyzed Reported Concentrations ( ppmv) Description Column Location Basement or Cell Room 72 Wall ( Continued)

DE1 22 Between D1& E1 D1 & E1 Basement 02/ 18/ 00 02/ 22/ 00 ND UPG3 22 Cell 3 G3 Cell Room 02/ 19/ 00 02/ 22/ 00 ND UPG13 22 Cell 13 G8 Cell Room 02/ 19/ 00 02/ 22/ 00 ND UPA31 22 Cell 31 A3 Cell Room 02/ 19/ 00 02/ 22/ 00 0.016 UPA53 22 Cell 53 A8 Cell Room 02/ 19/ 00 02/ 22/ 00 0.017 UAB1 22 Southwest Wall Opening B1 Cell Room 02/ 19/ 00 na Bag leaked UPDE1 22 Between D1& E1 Column D1 & E1 Cell Room 02/ 19/ 00 02/ 22/ 00 ND UPB1 22 Southwest Wall B1 Cell Room 02/ 20/ 00 02/ 22/ 00 ND NWEND 22 Northwest Wall F3 Basement 02/ 20/ 00 02/ 22/ 00 0.022 20UG3 22 Cell 20 G3 Cell Room 02/ 20/ 00 02/ 22/ 00 0.022 LOG13 22 Under Cell 13 G8 Basement 02/ 20/ 00 02/ 22/ 00 ND LOA31B 22 Under Cell 31 A31 Basement 02/ 20/ 00 02/ 22/ 00 0.024 UA53 22 Cell 53 A8 Cell Room 02/ 20/ 00 02/ 22/ 00 0.020 A31 24 Cell 31 A3 Basement 02/ 23/ 00 02/ 24/ 00 ND A53 24 Cell 53 A8 Basement 02/ 23/ 00 02/ 24/ 00 ND G13 24 Cell 13 G8 Basement 02/ 23/ 00 02/ 24/ 00 ND G3 24 Cell 8 G11 Basement 02/ 23/ 00 02/ 24/ 00 ND UPDEL 25 Mid Wall Column D1 & E1 Basement 02/ 24/ 00 02/ 25/ 00 ND 1B1 25 Southwest Wall Opening B1 Cell Room 02/ 24/ 00 02/ 25/ 00 ND UPG3 25 Cell 3 G3 Basement 02/ 24/ 00 02/ 25/ 00 ND LOG13 25 Cell 13 G8 Cell Room 02/ 24/ 00 02/ 25/ 00 ND UPA31 25 Cell 31 A3 Basement 02/ 24/ 00 02/ 25/ 00 ND LOA53 25 Cell 53 A8 Cell Room 02/ 24/ 00 02/ 25/ 00 ND aDetection limit = 0.013 ppmv 73 days, February 22 through 23, 2000, was below the method detection limit ( MDL). Although the concentrations of SF6 on February 20, 2000, were less than 5 x MDL ( MDL = 0.008 ppbV), the concentrations detected were significantly higher, on average ( 0.022 ppbV), than any other sampling day,

suggesting very minimal Hg transport during this sampling period. The bags that detected SF6 were located on the upper and lower northwest and southwest levels of the cell building. Samples were also taken from the standard check cylinder used to QC the long path FTIR. The results of these measurements are presented in the Quality Control/ Quality Assurance Section of this report.

5.3 Air Flow Study Results The results of the manual velocity measurements and the associated air flow balance calculations performed for the cell building are described below.

5.3.1 Roof Vent Monitoring The data obtained from the manual velocity measurements are shown in Figures 5 32 and 5 33 for the east and west sampling platforms, respectively. As these graphs show, the velocity profiles obtained on each platform exhibit a distinct decrease at the approximate center of the vent created by a structural member running the length of the building. In addition, the air velocity drops off rapidly outside the physical boundaries of the vent throat as would be expected.

The average air velocity measured manually by the propeller anemometer was also compared to that obtained by the optical anemometer for the same time period. The results of this comparison are provided in Table 5 5. As shown, the average air velocities determined by the two methods were within + 10% which is quite acceptable considering the differences in measurement technique ( i. e., optical vs.

mechanical), the limited amount of manual data collected, etc. Based on these results, the measurement path of the optical anemometer was considered to be located at a point representative of the average velocity and thus appropriate for use in the emission rate calculations. 74 0 0.5 1 1.5 2 2.5  1.00 0.00 1.00 2.00 3.00 4.00 5.00 Distance Relative to South Edge of Ve nt ( m ) Air Velocity ( actual m/ sec)

22 Feb 1 5 4 5 hrs ( Prop) 23 Feb ~ 1 0 0 8 hrs ( Prop) 23 Feb ~ 1 0 2 1 hrs ( Ho t W ire) South Edge o f V ent LOA B eam Pat h = ~ 1 .8 m Figure 5 32. Hand held anemometer readings at the optical anemometer measurement height on the east sampling platform, looking west.

0.0 0.5 1.0 1.5 2.0 2.5 0.00 1.00 2.00 3.00 4.00 5.00 Dis tance Re lative to South Edge of Vent ( m ) Air Velocity ( actual m/ sec)

22 Feb 23 Feb So ut h Ed g e o f V ent LOA B eam Pat h = ~ 1 .8 m Figure 5 33. Hand held anemometer readings at the optical anemometer measurement height on the west sampling platform, looking west. 75 Table 5 5. Comparison of Velocity Measurements in Roof Venta Sampling Location Sampling Date Average Velocity ( Propeller Anemometer) Average Velocity ( Optical Anemometer) Percent Difference East platform February 22, 2000 0.9 m/ s 0.8 m/ s 10 February 23, 2000 1 m/ s 0.9 m/ s 4 West platform February 22, 2000 0.9 m/ s 0.9 m/ s 7 February 23, 2000 0.9 m/ s 0.9 m/ s  1 a Rounded to one significant figure. Propeller anemometer = Davis Instruments TurboMeter ® ; optical anemometer = Scientific Technology Model LOA 104A.

5.3.2 Flow Balance Calculations The results of the cell building flow balance calculations are shown in Table 5 6 for the three methods described in Section 4.2.4. As Table 5 6 shows, unusually good closure ( i. e., 79 to 100%) was obtained in each of the three flow balance calculations performed. In addition, the three methods also correlate well with each other, providing additional confidence in the calculations performed. Finally, the high degree of closure of these flow balances lends further credibility to the air velocity measurements made by the optical anemometer in the roof ventilator to adequately characterize the air flow from the cell building.

Table 5 6. Results of Air Flow Balance Calculations for the Olin Cell Buildinga Date Volume Balance (% Closure) Mass Balance (% Closure) OxyChem DMB Resultsb (% Closure) Mass Balance (% Difference)

February 24, 2000 82 82 79 2.9 February 25, 2000 100 99 100  0.9 a Rounded to two significant figures. b Occidental Chemical Corporation direct mass balance ( DMB) method as provided by Michael Shaffer. 76 5.4 Discussion of Results The following sections discuss the results presented above for the roof vent monitoring, cell building air flow evaluation, and the tracer gas study conducted at the Olin chlor alkali facility.

5.4.1 Roof Vent Monitoring No specific pattern could be discerned from the daily plots of Hg0 emission rate determined from the roof vent monitoring conducted in this study. Figures 5 19 to 5 27 demonstrate that various episodic events were observed where the emission rate rises for a period of time then drops back to some nominal level.

An attempt was made to correlate these episodes to either process operation ( Figure 3 3) or maintenance events using plant records. Except for one specific event on February 20, when a significant Hg leak occurred in the Reductone ® area of the building , this analysis failed to find any useful association.

The plant operational logs were simply not adequate to pinpoint when certain maintenance operations were performed on the cells and thus when high airborne Hg levels might be expected. The data do suggest,

however, that roof vent instrumentation may be a useful tool for long term process monitoring to identify when problems occur in the operation of the cells which may require corrective action.

Another observation made during the study involves the impact of the high electromagnetic field on instrument operation. If future studies of this type are conducted, optical modems and cables should be used for the optical anemometer to allow logging of the data at a remote location. This procedure would substantially reduce the amount of lost data and make troubleshooting much easier for the operator.

Finally, although the concentration of Hg0 was found to be relatively homogeneous across the lateral dimension of the roof vent, such was found not to be the case along the longitudinal dimension. This observation is illustrated in Figure 5 34 which shows Hg0 concentration data collected during the January presurvey ( Appendix G). These data were obtained by sampling from the mobile crane over the south cell line using a Jerome Model 431 X survey instrument and a long sampling tube attached to a non conducting pole which extended to a point near the entrance of the roof ventilator throat. 77 Elemental Hg Longitudinal Profile in R oof Ventilator ( 1/ 13/ 00)

0.000 0.010 0.020 0.030 0.040 0.050 0.060 0 10 20 30 40 50 60 Dis tance from We s t Wall ( m ) Hg0 Concentration ( mg/ m 3)

Figure 5 34. Profile of elemental mercury concentration along length of roof vent entrance as obtained during the January 2000, presurvey.

As shown in Figure 5 34, the Hg0 concentrations were not consistent along the length of the ventilator. The lowest concentrations were found on the west end of the building near the two large open doors. Figure 5 34 also at least partially explains the lack of correlation between the Tekran and DOAS measurements described earlier. These differences constitute yet another argument supporting spatially integrated readings in lieu of point sampling with a manifold system. However, also note that these measurements were conducted below the ventilator throat, which can also affect the homogenity of the Hg0 levels obtained.

5.4.2 Building Air Flow Evaluation Unexpectedly good closure was obtained for each of the three air flow balance calculations performed in the study, especially for February 25 ( Table 5 6). One possible reason the balance obtained for February 25 has the highest degree of closure is that the manual velocity data were collected very quickly ( i. e., within about 15 min) as compared to the previous day when the measurements required about 78 1.5 hr to complete. Conditions within the cell building tend to change rapidly; thus, there is a need to obtain the necessary data over as short a time period as possible. A much larger data base is required,

however, to verify the results of the current flow study at other naturally ventilated buildings of this type.

As a final note, it was unfortunate that the roof vent tracer gas data were not useable in our analysis. The use of a tracer is a very well accepted technique for determining flow rates in situations where other methods prove difficult to implement. Therefore, the possibility of a tracer gas analysis for future flow measurement studies should not be abandoned. However, greater care is needed to verify proper instrument setup and operation in the field.

5.4.3 Comparison with Historical Information Additional analyses can be made of the data obtained in the study which are worthy of note. First is the comparison of the current results with those of prior emission testing of chlor alkali plants. For this analysis, only four documents were found in the literature which provide emission data for cell building roof vents. Two of these documents were EPA reports of contractor testing conducted in the 1970s as part of the original development of the Hg National Emission Standard for Hazardous Air Pollutants ( R. F.

Weston, 1971; Marks and Davidson, 1972). The other two documents were journal articles of two remote sensing studies conducted in Sweden and Italy ( Edner et al., 1989; Ferrara et al., 1992, respectively). The remote sensing studies were conducted using light detection and ranging ( LIDAR) systems to profile the plume from the cell building and as such were indirect measures of the Hg0 emissions from the building.

Table 5 7 summarizes the data contained in the above documents as compared to current study results. As shown, the daily emission rate obtained at the Olin facility is a factor of ~ 2 to 3 lower than that obtained in prior testing reported in the literature. It should be noted, however, that the literature values are based on generally outdated information from studies of more limited duration as compared to the current research.

Another observation that can be made from the historical data is a comparison of the estimated annual emissions from the cell building roof vent to the amount of makeup Hg added by the plant. 79 Table 5 7. Comparison of Current Study with Prior Research Reference Description of Study Daily Hg0 Emission Rate ( g/ day) a Roy F. Weston, Inc. 1971 Monitoring of two roof vents and nine powered ventilators using a Barringer Airborne Spectrometer and hot wire anemometer; one test per location 990 Marks and Davidson, 1972 Monitoring of two roof vents and ten powered ventilators using an iodine monochloride impinger train and vane anemometer; two runs per location 1,500 Edner et al., 1989 Differential absorption light detection and ranging ( DIAL) of a Swedish plant; 1 week study ( number of tests not specified) 720 Ferrara et al., 1992 Differential absorption light detection and ranging ( DIAL) of an Italian plant; 3 day study 930b Current study Continuous monitoring with UV DOAS and optical anemometer in roof vent for 9 day study period 470 a Extrapolates short term values to annual basis assuming 24 hr/ day and 365 days/ yr operation. Rounded to two significant figures.

b Average of all tests conducted. Value could be adjusted upward by at least 20% to account for interferences in the measurement path plus elimination of minor sources from the calculated average.

Assuming that the 9 day study period is indicative of the annual operation of the plant, which may or may not actually be the case, 172 kg/ year of Hg0 would theoretically be released to the atmosphere from the cell building vent. This value represents 2.3% of the total makeup Hg0 added by the plant in 1997. Note,

however, that Olin has implemented an aggressive Hg conservation program since 1997, and it is currently not known how much Hg was actually added during the year in which the study was conducted ( 2000).

Therefore, the above comparison is probably not valid for the 2000 operating year. However, taking these factors into consideration, it still appears that a substantial percentage of the potential Hg emissions were not measured in the roof vent during the current study. Data from other parts of the measurement program described in Section 1.2 may, however, provide additional information on other Hg sources within the plant which are not currently available for analysis. 80 Finally, in the 1997 Mercury Study Report to Congress, 18.8 Mg/ yr was estimated for all noncombustion Hg sources for the period 1994 95 ( Keating et al., 1997). Again assuming that the above annual emissions from the current study are valid, the Olin cell building represents less than 1% of the total non combustion Hg emissions inventory for 1994 95. Also, assuming a worst case makeup Hg consumption for the entire industry of 146 Mg as mentioned in Section 1, the Olin cell building annual emissions would constitute approximately 0.1% of this value.

Based on the above analyses, there is an apparent discrepancy between the results obtained in the current study and the potential Hg emissions from this and other CAPs. However, a number of factors could explain differences in the Hg0 emission rate, including better process control and increased plant maintenance. It is recommended, therefore, that extended monitoring at the Olin plant and/ or monitoring at additional plants be performed to address, among other issues, maintenance events and operational transients which are suspected as being the major cause of Hg release to the atmosphere from the cell building. 81 SECTION 6 QUALITY ASSURANCE/ QUALITY CONTROL A number of quality control ( QC) checks were made for the measurements conducted in the study.

For the automated methods, both long path and point monitors, checks included calibration using standards, daily system checks, and calibration of flow meters. For the manual techniques, QC checks included duplicate samples, field and instrument blanks, QC samples, and spiked samples. Table 6 1 summarizes the QC checks used for the various measurements conducted in the program. More detailed information on these checks can be found in the following sections. As discussed in Section 1, only the cell room data are discussed in this report. The other collaborators in this study will provide the quality assurance from their programs in separate publications.

6.1 UV DOAS Measurements The UV DOAS instrument used in the roof vent was initially calibrated in the laboratory using an optical bench. In the field, instruments were calibrated using a sealed optical cell with the concentration determined based on temperature. Temperature was measured by a calibrated, laboratory grade electronic thermometer. Calibrations are presented in Appendix H for the Hg0 response obtained on February 17, 24,

and 25, 2000. QC checks are reported in Table 6 2, and percent completeness was shown previously in Table 5 1.

6.2 Optical Anemometry As mentioned in the Quality Assurance Project Plan ( Kinsey, et al., 2000), an assessment of precision and accuracy for the optical anemometer was not possible. However, percent completeness was calculated for each 24 hr monitoring period as shown previously in Table 5 2. In addition, QC checks were also performed each morning using the electronic calibrator supplied with the instrument. 82 Table 6 1. QC Checks for Experimental Methods Included in QA Plana QC Check Long Path FTIR UV DOAS SF6 Bag Samples Calibration procedure SOP in QAPjP OPSIS   QA in QAPjP SOP in QAPjP Calibration frequency Before and after testing Before and after testing Before and after testing Type of calibration standard used Optical cell w/ certified gas standard ( vent only) Sealed optical cell Optical cell with gas standard Standard concentration or value 25 ppm SF6; 500 ppm n butane ( vent only) Saturated Hg vapor ( function of temp.) 0.1 and 0.5 ppm SF6 Source of standard Scott Specialty Gases ( vent only) OPSIS   Spectra Gases Standard traceability NIST ( vent only) N/ A Certified at ± 10%

Instrument flow rate N/ A N/ A N/ A Duplicate samples N/ A N/ A 10%

Field blanks N/ A N/ A One per bag Instrument blanks Nitrogen purge N/ A Zero gas   one per day QC samples or checks Daily system check per SOP Daily system check per QA manual Daily system check per SOP Reagent blanks ( if applicable) N/ A N/ A N/ A Spiked samples N/ A N/ A N/ A a SOP = Standard Operating Procedure; QAPjP = Quality Assurance Project Plan.

Table 6 2. Quality Control Checks for UV DOAS Description Date Taken Concentration ( µ g/ m3) Percent Recovery (%)

Test 2/ 24/ 00  1.2 NA Expected 7.0 µ g/ m3 2/ 24/ 00 6.45 92.1 Expected 41.7 µ g/ m3 2/ 24/ 00 34.0 81.5 Expected 83.4 µ g/ m3 2/ 24/ 00 72.55 87.0 Zero Test 2/ 24/ 00  0.35 NA Expected 5.7 µ g/ m3 2/ 24/ 00 4.63 81.2 Expected 37.5 µ g/ m3 2/ 24/ 00 40.4 108 Expected 75 µ g/ m3 2/ 24/ 00 78.2 104 Zero Test 2/ 25/ 00  0.96 NA Expected 4.3 µ g/ m3 2/ 25/ 00 4.75 110 Expected 42.5 µ g/ m3 2/ 25/ 00 42.0 98.8 Expected 83.3 µ g/ m3 2/ 25/ 00 83.4 100 83 The results of these checks are summarized in Table 6 3 below. All QC checks were within the acceptable ranges specified by the manufacturer.

Table 6 3. Results of Daily QC Checks of Model 104a Optical Anemometer Output from Electronic Calibrator by Measurement Rangea Breakout Box Voltage Date 0.1 m/ s 5 m/ s 10 m/ s Channel A Channel B February 17 0.03 1.70 3.37 2.56 2.49 February 18 0.03 1.71 N/ A 2.40 2.38 February 19 N/ A 1.69 3.36 2.37 2.37 February 20 0.03 1.71 N/ A 2.36 2.46 February 21 0.03 1.71 N/ A 2.38 2.48 February 22 0.03 1.71 N/ A 2.24 2.40 February 23 0.03 1.72 N/ A 2.41 2.41 February 24 0.03 1.70 N/ A 2.45 2.39 February 25 ( b) ( b) ( b) 2.65 2.32 a Readings obtained from computer DAS in m/ s for each calibrator range indicated. Since a 2 in. aperture was used in place of the standard 6 in. aperture, all values shown must be multiplied by a factor of 3 to obtain equivalent value. N/ A = not available. b DAS crashed just prior to daily QC check. Instrument operational until QC check attempted per downloaded data files.

6.3 SF 6 Release, Sampling, and Analysis ( FTIR)

The SF6 tracer gas was released as a diffuse line source along the centerline of the cell room. The tracer was provided from compressed gas cylinders through a " soaker hose" running the length of the building. Gas was metered from the cylinder using a pressure regulator and precision rotameter calibrated with SF6 using a bubble test meter prior to deployment. Single point calibration checks were made at least every 4 days throughout the program. Calibrations are presented in Appendix I for the rotameter calibrations obtained on February 16 and 23, 2000. 84 QC procedures for bag sampling and analysis were performed. Sampling QC activities were conducted separately from analytical QC. Field sampling data were recorded in a laboratory notebook.

Copies of the notebook pages are presented in Appendix J.

Sampling QC included daily inspection of the FTIR spectrometer and a bag container leak check.

Sampling system QC was performed prior to each sample run including blank values for each sample collection bag. Acceptable blank values were

5x MDL ( MDL for closed cell SF6 = 0.008 ppbV). Blank and quality control checks are reported in Tables 6 4 and 6 5, respectively.

QC procedures for the FTIR spectrometer included:

 Instrument sample cell integrity check;

 Collection of diagnostic spectra; and  Gas standard measurements.

These procedures were conducted each test day prior to analysis. Diagnostic spectra were collected for the SF6 gas standards which included 0.1 and 0.5 ppm SF6. The analytical procedures for both diagnostic spectra and gas standards were identical. All calibration procedures for bag sample collection and FTIR analysis were included in the Standard Operating Procedure ( SOP) as listed in Table 6 1 above.

6.4 Long Path FTIR QA/ QC Checks ( Roof Vent)

Based on the quality review provided by ManTech Environmental, the data from the long path roof vent FTIR were not used. Appendix B contains a complete description of problems with data validation.

For calibration and QA/ QC purposes, the roof vent FTIR optical cell was first purged with 99%

purity nitrogen. During this procedure a background spectrum was collected and recorded. After purging,

the instrument's optical cell was challenged with n butane certified at 500 ppm. Resulting spectra were collected and recorded. Then the cell was again purged with 99% purity nitrogen to remove any residue.

The cell was then challenged with SF6 certified at 25 ppm. Resulting spectra were collected and recorded.

Finally, the cell was again purged with 99% purity nitrogen. This procedure was performed before the 85 FTIR began to collect data and when data collection for the study was completed. For QA/ QC purposes,

the FTIR was purged with 99% purity nitrogen and challenged with SF6 throughout the sampling period.

Table 6 4. Manual Bag Sampling/ Analysis Blank Control Checksa Bag ID Description Date Taken Date Analyzed Average Concentration ( ppmv) zero1 17 Blank 02/ 17/ 00 02/ 17/ 00 0.0000 zero2 17 Blank 02/ 17/ 00 02/ 17/ 00 0.0000 zero3 17 Blank 02/ 17/ 00 02/ 17/ 00 0.1310 zero1 18 Blank 02/ 18/ 00 02/ 18/ 00 0.0000 zero2 18 Blank 02/ 18/ 00 02/ 18/ 00 0.0017 zero3 18 Blank 02/ 18/ 00 02/ 18/ 00 0.0020 zero1 22 Blank 02/ 22/ 00 02/ 22/ 00 0.0000 zero2 22 Blank 02/ 22/ 00 02/ 22/ 00 0.0140 zero3 22 Blank 02/ 22/ 00 02/ 22/ 00 0.0140 ZERO4 22 Blank 02/ 22/ 00 02/ 22/ 00 0.0135 ZERO1 23 Blank 02/ 23/ 00 02/ 23/ 00 0.0000 ZERO2 23 Blank 02/ 23/ 00 02/ 23/ 00 0.1022 ZERO1 24 Blank 02/ 24/ 00 02/ 24/ 00 0.0000 ZERO2 24 Blank 02/ 24/ 00 02/ 24/ 00 0.0000 ZERO3 24 Blank 02/ 24/ 00 02/ 24/ 00 0.0000 ZER04 24 Blank 02/ 24/ 00 02/ 24/ 00 0.0000 ZERO5 24 Blank 02/ 24/ 00 02/ 24/ 00 0.0000 ZERO6 24 Blank 02/ 24/ 00 02/ 24/ 00 0.0000 ZERO1 25 Blank 02/ 25/ 00 02/ 25/ 00 0.0000 ZERO2 25 Blank 02/ 25/ 00 02/ 25/ 00 0.0000 ZERO3 25 Blank 02/ 25/ 00 02/ 25/ 00 0.0000 a All high blanks were followed by recalibrations and re analysis Table 6 5. Manual Bag Sampling/ Analysis Quality Control Checks Bag ID Description Date Taken Date Analyzed Concentration ( ppmv) True Value ( ppmv) Percent Recovery Comments std 1 18 Standard 2/ 18/ 00 2/ 18/ 00 0.104 0.1 104.4 std 2 18 Standard 2/ 18/ 00 2/ 18/ 00 0.480 0.5 96.02 std 2a 18 Standard 2/ 18/ 00 2/ 18/ 00 0.478 0.5 95.62 std 2 22 Standard 2/ 22/ 00 2/ 22/ 00 0.510 0.5 101.92 std 3 22 Standard 2/ 22/ 00 2/ 22/ 00 0.115 0.1 115.1 QC check repeated ( std 7 22) std 4 22 Standard 2/ 22/ 00 2/ 22/ 00 0.122 0.1 121.6 std 5 22 Standard 2/ 22/ 00 2/ 22/ 00 0.499 0.5 99.84 std 6 22 Standard 2/ 22/ 00 2/ 22/ 00 0.467 0.5 93.44 ( Continued)

Table 6 5 ( Continued) 86 Bag ID Description Date Taken Date Analyzed Concentration ( ppmv) True Value ( ppmv) Percent Recovery Comments std 7 22 Standard 2/ 22/ 00 2/ 22/ 00 0.486 0.5 97.2 std 1 23 Standard 2/ 23/ 00 2/ 23/ 00 0.482 0.5 96.42 std 2 23 Standard 2/ 23/ 00 2/ 23/ 00 0.104 0.1 103.6 std 3 23 Standard 2/ 23/ 00 2/ 23/ 00 0.104 0.1 103.5 std 4 23 Standard 2/ 23/ 00 2/ 23/ 00 0.095 0.1 95.3 std 6 23 Standard 2/ 23/ 00 2/ 23/ 00 0.101 0.1 101.2 std 1 24 Standard 2/ 24/ 00 2/ 24/ 00 0.113 0.1 113.1 QC check repeated ( std 2 24) std 2 24 Standard 2/ 24/ 00 2/ 24/ 00 0.508 0.5 101.62 std 3 24 Standard 2/ 24/ 00 2/ 24/ 00 0.504 0.5 100.7 std 4 24 Standard 2/ 24/ 00 2/ 24/ 00 1 0.5 103.76 std 1 25 Standard 2/ 25/ 00 2/ 25/ 00 0.502 0.5 100.36 std 2 25 Standard 2/ 25/ 00 2/ 25/ 00 0.110 0.1 110.1 QC check repeated ( std 3 25) std 3 25 Standard 2/ 25/ 00 2/ 25/ 00 0.488 0.5 97.52 VanQC 25 FTIR Roof QC 2/ 25/ 00 2/ 25/ 00 20.7 25 82.7496 Check against Roof FTIR's QC std 4 25 Standard 2/ 25/ 00 2/ 25/ 00 0.490 0.5 98.02 std 5 25 Standard 2/ 25/ 00 2/ 25/ 00 0.104 0.1 103.8 std bag 1 25 Standard in Bag 2/ 25/ 00 2/ 25/ 00 0.083 0.1 83.3 std bag 2 25 Standard in Bag 2/ 25/ 00 2/ 25/ 00 0.430 0.5 86.06 std bag 3 25 Standard in Bag 2/ 25/ 00 2/ 25/ 00 0.087 0.1 87.2 std bag 4 25 Standard in Bag 2/ 25/ 00 2/ 25/ 00 0.439 0.5 87.84 VanQC 25 FTIR Roof QC 2/ 25/ 00 2/ 25/ 00 23.3 25 93.196 Check against Roof FTIR's QC 6.5 On Site Audit An on site audit was performed by two members of EPA APPCD's QA staff. An audit report was written and submitted to the research team for their response. The written responses from the research team were accepted as submitted without further clarification. 87 6.6 Data Quality Indicators Data quality indicators ( DQIs) were described in the Quality Assurance Project Plan,

Section 4. The field verification of the DQI results is presented in Table 6 6. With the exception of the FTIR roof vent monitoring, only one other DQI failed to meet acceptance criteria. Because of the optical saturation of the FTIR detector used for the Roof Vent monitoring, the DQIs were not achieved; the FTIR results are discussed in Section 4.2.1.

Table 6 6. Data Quality Indicator Results Parameter Measurement Method Data Quality Indicator Value Obtained Achieved criteria?

SF6 Tracer Concentration Manual bag sampler Precision 20% 12.2  16.7% Yes Accuracy 6% 4.4  4.7% Yes Detection Limit 6 ppb 6 13 ppb  a Completeness 95% 96.4% Yes Air Velocity in Cell Building Long path optical anemometer Detection Limit 0.2 m/ s 0.2 m/ s Yes Completeness 90% 93% Yes Total Gas Phase Hg0 Roof vent UV DOAS Precision 15%  b  b Accuracy 15% 8  18.8% Yes Detection Limit ~ 130 ng/ m3  b  b Completeness at 75% 80  89% Yes a The detection limits for the bag sampling determined during each analysis day of the field testing ranged from 6 to 13 ppb. The highest detection limit value determined was used to facilitate data processing and determine daily analytical values.