Document 3JqyZopwVjyMwxLR940LVDMMy

s' . ^ (VxA*^ ' TO? R. D. blin eD AU G 8 1985 FROM: DATE: Interoffice Communication SUBJ: J. C. Ledvina August 6, 1985 TOXIC GAS RELEASES VISIA jfL I attended a Toxic Gas Release se linar on July 31 put on by Trinity Consultants. The following day the Air Pollution Control Association held a conference on the same subject. Below highlights that may be of use in formulating Vista's program. 1. 2. <9 4 Britian passed a law about a year ago requiring industries to notify the general public near facilities handling toxic materials. The law also requires industry to do prior training and notify the public directly in the event of a release. I can get a copy of the British law if more details are needed. The Texas Railroad Commission Rule 36 requires immediate notice to near neighbors in the event of a sour gas release from a well. This rule is in response to the death of several people outside of Denver City, TX in the mid-1970's from exposure to H2s. Dow has placed speakers in homes near their chlorine plant in Placquimine, LA. Approximately 20 SaferTM systems have been installed in the United This system is a computerized air dispension iredict downwind concentrations of toxic gases from a Eastman Kodak management has mandated their plants to install Safer Systems. I talked to two engineers-from Texas Eastman at Longview who are working with Safer1 on the installation for their Plant. Although not yet installed, they has more Public Relations value than ractical value i: predicting downwind toxic concentrations. tman's Longview Dick Schultz of Trinity Consultants installed two TM systems for clients in Mississippi. He is very skeptical that they will ever be used. 5. There is no proven mathematical model to reliably predict , concentrations of heavy getses. tA\ hneavy gas is one such ammonia or chlorine where a sudden release emits both gas and an aerosol of droplets. Classical dispersion equations do not accurately predict concentration until all the droplets have vaporized and the cloud starts moving with the wind. However, vapor releases of ammonia or chlorine are "modelable**. VAB.0001093734 f R. D. Gamblin Page 2 August 6, 1985 6. In many cases, neighbors are likely to be exposed to less toxic gas if they remain in their homes. This is especially true if the release is a "puff" and there is a wind. 7. Dispersion modelling is best used as a planning tool. By speculating on likely release scenarios and using dispersion modelling, decisions can be made as to which neighborhoods, if any, should be given special attention. I have some written material on dispersion modelling as well as a bibliography of references related to toxic gas releases. Let me know if any of this is of interest to you. ajo/3 cc RTF, WLM VAB.0001093735 REGISTRATION LIST Houston, TX - July 31, 1985 Mr. Allen Jurisich Senior Program Advisor, Environmental Service Cigna Loss Control 139 West Livingston Place Metairie, LA 70005 (504) 831-1617 Mr* John Brau Employee Relations Manager Sohio Chemical Company Box 659 Port Lavaca, TX 77979 (512)552-8218 Mr* Joe Ledvina Director of Environmental Activities Vista Chemical Company P*0. Box 19029 Houston, TX 77224 (713)531-3451 Ms* Ailleen Teng Senior Environmental Health Specialist Cigna Loss Control Service 12815 Leader Houston, TX 77072 (713)933-1826 Mr. Ron Pertuit Texas Eastman Company P*0* Box 7444 Longviev, TX 75607 (214) 236-5000 ext. 2760 Mr. Joe Woolbert Texas Eastman Company P.0. Box 7444 Longviev, TX 75607 (214) 236-5000 ext* 2760 TRINITY CONSULTANTS, INC XA 1093736 SERVICES TO ESTIMATE AIR QUALITY Trinity Consultants, Inc* has specialized in making estimates of air quality and in obtaining air pollution permits since 1974* All employees devote their time exclusively to this narrow area of the environmental field and they are unusually familiar with rules, regulations, and current practices* The client benefits in terms of reduced costs and quick response time* As a small firm with 7 employees and its own computer, overhead is low and individuals working on study deal directly with the client. > These studies are performed to help clients evaluate the air quality either to pinpoint the sources of current problems or to evaluate the effect of proposed changes* Since 1978, Trinity Consultants has prepared over 300 dispersion modeling studies for clients in 40 states* Typical categories of work include: e Trinity Consultants is a leading firm in preparing "Prevention of Significant Deterioration" (PSD) applications* Since 1977, 115 PSD reports have been prepared for nearly every type of industrial plant* Applications have been prepared for plants located in all 10 EPA regions and in 29 states* SIP Revisions - Since 1978 Trinity Consultants has helped 9 clients obtain permits to.construct in non-attainment areas* In 15 other cases Trinity Consultants has been involved in State Implementation Plan revisions* Stack Heights - Trinity Consultants has conducted more than a dozen studies of stack design to optimize investment* . Three courses are conducted: a two-day course on the fundamentaIs dispersion modeling, a two--day laboratory applications course using dispersion models on an IBM-PC and a one-day seminar entitled "Permits Under the Clean Air Act". These courses have been taught a total of over 90 times and have been sponsored by professional associations for their : embers, major corporations for their employees and Trinity Consultants for the public* Sale of Models and Met Data* Clients can purchase dispersion models and meteorological data in one of 3 ways: First, 21 firms currently use Trinity Consultants timesharing service devoted almost exclusively to air quality dispersion models* Second, over 70 customers have purchased IBM-PC versions of popular air pollution dispersion models* Third, since 1976 some 20 firms have purchased IBM mainframe version of the UNAMAP models* Trinity Consultants also processes and sells meteorological data from its extensive library* Delivery is generally overnight 20 firms have been served with studies of the possible effects of a potential gas releases, estimated effects of actual releases, building ventilation studies and testimony in court* Both puff models and steady state models have been used in these analyses* January 1, 1985 214/234-8567 TRINITY CONSULTANTS, INC. Finn* PARTIAL LIST OF CLIENTS Allied Materials Corp. * American Petrofina, Inc* Calumet Refining Co* Inc* + Champ1in Petroleum, Inc* * Crystal Oil Company Dorchester Refining Company Getty Refining & Marketing Co* + Gulf Oil Co. - U.S. Kerr-McGee Corp* Lake Charles Refining Co* + Murphy Oil Corp. + Pennzoil Oil Corp* Plateau Refining Co* Rock Island Refining * Sigmor Refining Co* + Standard Oil Co* (Indiana)(AMOCO) Standard Oil Co* (Ohio) + Sun Company Union Oil Company * Vidette Refining Co* + Aminoil U.S.A., Inc* Arco Oil & Gas Co* Mid-American Oil & Gas (Centex) Cities Service Company Delhi Gas Pipeline Co* + Endevco, Inc. Exxon Production Research + Farmland Industries + Getty Oil Co* Haliburton Resource Management * Runt Energy Co* Husky Oil Co* + Kerr-McGee Corp Koch Hydrocarbon Co* Leede Oil & Gas Inc* Mesa Petroleum Co* Moore McCormick Energy + Pursue Gas Processing + Shell Oil Co* + Sun Exploration & Production Texas Oil & Gas Corp* Tipperary Corp* * Tomlinson Interests * Union Texas Petroleum Boise-Cascade + Bovater Southern Paper Corp* Celotex Container Corporation of America + Fort Howard Paper Co* Georgia-Pacific * Hammermill Paper + Owens-Illinois, Inc* Temple Eastex, Inc* Airco Carbon + Agrico, Inc* + Firestone Synthetic Rubber & Latex Freeport Chemical Co* + American Cyaminid Georgia Pacific Co. + CF Industries, Inc* + Goodyear Tire A Rubber Co* Cabot Corp* + W.R* Grace (Davidson Chemical Div*) Calgon Corporation + Kerr-McGee Chemicals Chemische Werke Hula AG Mississippi Chemical Corp* Chevron Chemical Co* Monsanto Corp* Colombian Chemical Co* 01in Chemical Conoco Chemical Co* Petro United, Inc* Cosden Oil - Chemical Co Procter & Gamble Co* Coulton Chemical Co* Rohm A Haas, Inc* + Dow Chemical Co. Sintech, Inc* + E* I* DuPont de Nemours Stauffer Chemical + Ethyl Corp* Sid Richardson Carbon A Gasoline FMC Corporation Union Carbide Corp* . Vulcan Chemical Co* TRINITY CONSULTANTS, INC. VAB Metals Energy Fuels Nuclear, Inc Kerr-McGee Corp. Texas Industries + Fittston Coal * Sohio Consultants m * Arco Aluminum Blav-Knox Chaparral Steel (TXI) Kaiser Aluminum & Chemical Corp LTV Steel National Steel * National Zinc +* NL Industries + RSR Corporation * Ross Metals Argento, Vittorio Benham Group, Inc Louis Berger & Asso Bovay Engineers, In Breisch Engineering Browning George R. Alexander, Jr. Baker & Daniels Greenberg, Traurig Lynberg & Nelson Millbank, Tweed Popham, Haik, Schnobrick, Service CE-Maguire Chittenden Engineering Co* Clark, Diets A Associates + Controls for Environmental Pollution Cooper Engineers Kaufman & Doty Rooks, Pitts & Poust Sewell, Junell & Riggs Thompson & Knight Wachtell, Lipton, Rosen A Katz Daniel Construction Co. Davis A Floyd Engineers, Inc. Lime A Glass Evergreen Environmental Management F.E. Courtney A Associates Acme Brick FordBacon A Davis Gibbs and Eill Kaiser Engineers George E. McVehil MITRE Metro Environmental Application Moore Engineering J.F. Mullen A Associates Ortloff Corp. Petro Project Engineering, Inc. Petrochem Consultants, Inc. R.W. Beck A Associates Resource Consultants, Inc. Rist, Frost Associates Scott Environmental Simons Eastern Stanley Consultants Steuver & Associates + J.E. Thibault & Associates Tippet & Gee Trovillion, A1 TRW, Inc. B.L. Anderson + Capitol Aggregates, Inc. +* Chemical Lime * Centex Corp. Dal-Tex Cement Chemicals General Portland, Inc. Genstar Building Materials C Gifford Hill Portland Cement Ideal Basic Industries Lehigh Portland Cement Libbey-Ovens-Ford Lone Star Cement Loomis Construction * Nevada Cement Owens-Corning Owens-Illinois, Inc. + Southwestern Portland Cement + Texas Industries, Inc. +* U.S. Brick + U.S. Gypsum Turner Engineering Turner, Mason & Associates Roy F. Weston Co. A TRINITY CONSULTANTS, INC__________ ___ VARJ^TOI 093739 t * Arizona Public Service, Inc. * Brazos Electric Pover Cooperative +* Cajun Electric Pover Cooperative Foothills Pipeline, Ltd. * Golden Valley Electrical Co-op, Inc +* General Electric Co. + Hawaiian Electric Company Louisiana Pover & Light Mississippi River Transmission Corp * Nebraska Pover & Light New Orleans Public Service, Inc. + Panhandle Eastern Pipeline * Oklahoma Gas & Electric Co. + Southwestern Electric Pover Co. Tennessee Gas Transmission Co. Transcontinental Gas Pipeline Co. * United Gas Pipeline, Inc. * Valley View Energy Alexander & Baldwin Amstar Corp. Bunge Corp. * City of Detroit Dresser Industries Ford Motor Co. (Boiler) + Frito Lay, Inc. Gearhart Industries City of Indianapolis + Intec, Inc. * Iowa Beef Processors Manyille Building Corp. McDonnell-Douglas Corp. * City of San Diego TD Mechanical Texas Instruments * University of Vermont Varo, Inc. * Warwick, Rhode Island A1 abama Alaska Arkansas California Colorado Connecticut Florida Georgia Hawaii Illinois States in Which Studies Have Indiana Iowa Kansas Kentucky Louisiana Maine Maryland Michigan Mississippi Missouri Mont ana Nebraska New Jersey New Mexico Nevada North Dakota Ohio Oklahoma Pennsylvania Puerto Rico ' m m v m . +i Rhode Island South Carolina Tennessee Texas Utah Vermont Virginia West Virginia Wisconsin Wyoming Been Done Brazil New Zealand Belgium Netherlands Canada Saudi Arabia Gulf of Mexico Indone sia Air Pollution Control Association American Cyanimid American Society of Mechanical Engineers Aramco Services Company Ashland Chemical City of Indianapolis Damson Oil IBM Inland Steel Co. Kerr-McGee Corp. * Served through a consulting firm + Performed more than one study '(`Mobil Oil PEDCO Environmental Republic Steel Standard Oil Co. (Indiana)(AMOCO) Tennessee, State of Texas Chemical Council Timken Company U.S.Environmental Protection Agency Regions IV and VII United Technologies University of Texas (for EPA) January 1, 1985 (84-62) TRINITY CONSULTANTS, INC VAB.OQ01093740 EMPLOYEE QUALIFICATIONS Richard H. Schulze President Mr* Schulze received a BSE degree in Mechanical Engineering from Princeton University in 1954 and a MBA degree from Northwestern University in 1958. Following .13 years of work in corporate long-range planning and product development, he joined Core Laboratories Inc. in 1971 as President of their environmental affiliate. Ecology Audits, Inc. He supervised activities in stack sampling, ambient air monitoring networks, water quality studies and preparation of environmental impact statements. In 1974, he founded Trinity Consultants, a firm responsible for over 300 dispersion modeling studies including over 115 PSD permits and 15 SIP revisions. In 1975 he started teaching a two-day short course on dispersion modeling. To date, there are over 1000 graduates of this course which has been offered 80 times throughout the world. Since 1978 he has taught all the Air Pollution Control Association (APCA) short courses dealing with the fundamentals of dispersion modeling as well as selected EPA courses. He is a registered Professional Engineer, a Diplornate of the American Academy of Environmental Engineers, the founder of the North Texas Chapter of APCA, the author of numerous papers on air pollution, and a member of more than 10 professional organizations. He is the sole owner of Trinity Consultants, Inc. James C. Clary, Jr Project Manager Mr. Clary has over 10 years experience in work as a consulting meteorologist. He holds both the BS and MS degrees in Meteorology from Florida State University. After completing his active military obligation as an officer, Mr. Clary joined Dames & Moore Consultants where he worked on meteorological and safety studies for nuclear power plants as well as on the dispersion of conventional pollutants, including preparation of several PSD permits. Mr. Clary has continued his work in meteorology since joining Trinity Consultants in 1978. He has served as project manager for over 28 PSD permit applications and over 50 other modeling studies. He is also the director of data processing and has installed two computer systems at Trinity. Mr. Clary has been responsible for converting most of EPA's UKAMAP models to be executable on IBM-PC or compatible computers and for developing a two-day Dispersion Modeling Laboratory course which he has now taught 6 times. Mr. Clary is a Certified Consulting Meteorologist of the American Meteorological Society. He taught a semester-length course on modeling of air pollutants at the University of Texas at Dallas. A TRINITY CONSULTANTS, INC. Y-AB 1093741 A Ms. Fusselman graduated cum laude in Chemical Engineering from Texas A&M University in 1980. After graduation* she joined Trinity Consultants and became involved with the development of emission inventories and the preparation of state and federal permit applications. Subsequently* her work also included over 70 dispersion modeling studies. More than half of these dispersion modeling studies were performed for state and federal permit applications. The majority of the permit applications have focused on petroleum refineries* chemical plants* natural gas processing plants and compressor stations. Ms. Fusselman has also assisted timesharing customers vith the use of the computer and with technical modeling advice. She has converted most of the EPA*s UNAMAP models to execute on the IBM mainframes. She has satisfied the written requirements for registration as a Professional Engineer in the State of Texas. She is a member of the American Institute of Chemical Engineers and the Air Pollution Control Association. Tammy S. Rippetoe Project Meteorologist Ms. Rippetoe graduated cum laude in Meteorology from Texas A&M University in 1983. She joined Trinity Consultants in July* 1984* and has become involved in preparing emission inventories* dispersion modeling and processing meteorological data. She is a member of the American Meteorological Society and the Air Pollution Control Association. Scott R. Humphrey Project Meteorologist Mr. Humphrey graduated magna cum laude in Meteorology from Texas A&M in 1983 and received his Master of Science degree in Meteorology from Texas A&M in 1985. His graduate study was in the areas of atmospheric diffusion and boundary layer turbulence. He joined Trinity Consultants in March* 1985* and his duties include dispersion modeling* processing meteorological data* and aiding in the preparation of project reports. He is a member of the American Meteorological Society and the Air Pollution Control Association. TRINITY CONSULTANTS* INC. TRPUF TOUR SOLUTION FOR EVALUATING TOXIC GAS RELEASES INTRODUCTION Trinity Consultants, a leader in the field of IBM-PC applications for the air pollution professional, has developed a software package for evaluating releases of toxic gases. This package consists of both the EPA Puff model and TRPUF, a puff model developed by Trinity Consultants. TRPtiF is based upon the EPA Puff model. A graphics system is also included in this package. System characteristics include: # Simple data entry using interactive and menu-driven screens e Complex input variables are not required Graphical output of concentration versus distance produced on your printer This model is described in the EPA publication "Estimating Concentrations Downwind from an Instantaneous Puff Release" (PB82-261959), August 1982. The model is based upon the Gaussian Puff equation using the dispersion parameters presented in Meteorology and A^pj-c Energy. This program has been converted for the IBM-PC with all of the features included in the original model. Verification test files are included. TRPUF TRPUF is based on the Puff EPA model. Several enhancements have been made p to make the program easier to use in the PC environment. All input parameters are specified with simple interactive commands. When TRPUF is started a screen of input items is presented. This screen contains the data used in the last run made. You simply enter the variable number you wish to modify. The computer will prompt you for the entry, verify the entry and then present the input screen again. The input screen is shown in Figure 1. Notice that all of the entries are relatively simple. There are no complicated variables to define. Tou also have complete control of the output format from units through fixed or scientific presentations. -------------- ------------ TRINITY CONSULTANTS, INC. -?C-C X 4> When you select option zero from the input screen, TRPUF begins executing. The results are automatically printed on your printer as the model executes. Total execution times vary with different printers, but vill be under two minutes for most printers. An example of the output is shown in Figure 2. This compact output displays both instantaneous and average concentrations at several downwind distances. Concentrations are included for all three stabilities as well as the maximum concentrations. All input parameters are also shown. The results of your TRPUF run are not only sent to the printer but are also placed in a disc file. Another program included in this package, PDIST, allows you to produce plots of concentration versus downwind distance. Again, you may design your output with simple interactive responses as shown in Figure 3. The output of PDIST is processed by the Golden Software package to produce high quality plots on your dot-matrix printer. Examples are included as Figures 4 and 5. GOLDEN SOFTWARE GRAPHICS SYSTEM This complete graphics system is included in the TRPUF package. This system, developed by Golden Software of Golden, Colorado, is used to produce the concentrations versus distance plots. However, this package contains many additional capabilities including contour and three-dimensional plots, XT, graphs, bar charts, pie charts, line graphs and scatter charts. PRICE AND HARDWARE BF.OTTTBEMENTS The complete TRPUF package is available for $995.00 for a single-use license. This package includes: o Both source and executable versions of the EPA Puff model and test data files o Both source and executable versions of TRPUF o Executable version of PDIST o Complete Golden Software Graphics System with all documentation o EPA guide for the EPA Puff model and Trinity Consultants guide for TRPUF o Telephone support services to help you get started. Hardware requirements are an IBM-PC, PC/XT or AT, or compatible; two floppy disc drives or one floppy and one bard drive; 256 kb of RAM; and a dot-matrix printer. A math coprocessor will decrease execution time, but is not required. TRINITY CONSULTANTS, INC * 1093744 COMPANY-WIPE LICENSE A company-wide license of the software* This license removes the restriction that only copies for backup purposes be made* The user is free to copy and distribute the software and manuals within a single company* The user is responsible for all reproduction* Questions about the software must be made by one person. The additional cost of this option is $500* You must have also purchased one copy of our single-use product. TRINITY CONSULTANTS, INC. v * TRPUF - H0D5 COPYRIGHT 1985 TRINITY CONSULTANTS, INC. 1) TITLE - EXAMPLE OF TRPUF3 2) RELEASE AMOUNT (POUNDS) * 2.20300 3) MOLECULAR HEIGHT * 64.00 4) AMBIENT TEMPERATURE (DEGREES F) * 88.00 5) AMBIENT PRESSURE (MB) * 1013.00 6) RECEPTOR HEIGHT ABOVE GRABE (FEET) * 3. 7) AVERAGING TIME (SECONDS) * 300. 8) EXIT VELOCITY (FEET PER SECOND) (USE 0 IF NOT A VERTICAL RELEASE) 5.000 P) STAGS DIAMETER (FEET) 1.500 10) DISTANCE FACTOR (USE 1 FOR THE STANDARD DOWNING DISTANCES) = 1.0000 11) KIND SPEED (MPH) 3.0 12) STACX HEIGHT (FEET) * 60.00 13) CONCENTRATION UNITS * U6/H3 /'**' INITIAL PUFF CENTER CONCENTRATION (PPM) 5.00E405 DISTANCE AT WHICH INITIAL PUFF SIZE IS KNOW (FEET) * 0. 16) INITIAL HORIZONTAL STANDARD DEVIATION (FEET) * .00 17) INITIAL VERTICAL STANDARD DEVIATION (FEET) .00 IS) OUTPUT FORMAT - SCIENTIFIC ENTER VARIABLE NUMBER TO BE MODIFIED, 0 TO RUN, W TO STOP PC-C 4 FIGURE 1VAB.0001093746 PC-C A fRPUF - MODS COPYRIGHT 1985 TRINITY CONSULTANTS, INC. A PUFF MODEL DEVELOPED BY TRINITY CONSULTANTS, RICHARDSON, TEXAS 214/234-8567 EXAMPLE OF TRPUF5 RELEASE AMOUNT (POUNDS) = 2.20500 RECEPTOR HEIGHT ABOVE GRADE (FEET) MOLECULAR WEIGHT = 64.00 EXIT VELKITY (FEET PER SECOND) ENT TEMPERATURE (DEO F) * 88.00 STACK DIAMETER (FEET) AMBIENT PRESSURE (MB) =1013,00 WIND SPEED (MPH) STACK HEIGHT (FEET) COMPUTED VIRTUAL DISTANCES (FT) HORIZONTAL VERTICAL UNSTABLE 3.3 3.3 NEUTRAL 16.4 16*4 STABLE 85.3 85.3 5. 5.000 1.50 5.0 60.00 AL CONCENTRATION (PPM) 5.00E+05 HORIZONTAL S16MA (FEET) = .00 AL VERTICAL SIGMA (FT) * .00 DOWNWIND DISTANCE (FT) * 0. DOWNWINI PEAK INSTANTANEOUS CONCENTRATIONS AVERAGE CONCENTRATIONS FOR 300. SECONDS SIGMAS (FEET) DISTANCE mm(FEET) UNSTABLE (UG/M3) NEUTRAL STABLE MAXIMUM UNSTABLE (UG/H3) NEUTRAL STABLE TRAVEL UNSTABLE NEUTRAL STABLE MAXIMUM (MINUTES) HOR VER HOR VER 20 5.3409E-07 2.2128E-09 6.7703E-09 5.5409E-07 1.7591E-09 4.W2X-12 1.1093E 40 2.0281E+01 7.2767E-10 4.468X-09 2.0281E+01 1.1391E-01 2.2348E-12 8.5457E 60 80 1.9562E403 12150E+04 3.3662E-10 1.8649E-10 3.1362E-09 23043E-09 1.9562E403 1.2150E+04 1.5583E401 1.3668E-12 12461E402 9.3783E-13 6.8435E 5.6399E 100 2.B975E+04 1.1553E-10 1.7539E-09 2.8975E+04 3.6224E402 6.9102E-13 4.7519E 1.7391E-OT 1.1391E-01 1.5S83E+01 1.2441E+02 3.4224E+02 .045 .091 .136 .IX .227 37 5 11 7 15 9 18 11 22 231 1 3422 4422 4 52 2 5622 120 4.30778404 4.2469E-10 1.3728E-09 4.5077E+04 6.6321E402 2.9391E-12 140 5.6339E+04 1.9488E-07 1.0993E-09 5.6339E+04 9.5187E402 1.5296E-09 160 6.2312E+04 1.7899E-05 8,9711E-10 6.2312E404 1.187X403 1.5694E-07 180 6.4114E+04 5.3571E-04 7.4386E-10 6.4114E+04 1. 3586E403 5.1847E-06 200 6.3107E404 7.4O87E-03 6.2525E-10 6.3107E+04 1.4710E403 7.8394E-0S 6.4321E-W2 .273 13 25 6 7 3 2 9.5187EW2 .318 15 27 7 7 3 2 1.1873E+03 .364 17 30 8 8 3 2 1.3584E+03 .409 19 33 8 9 3 2 1.4710E+03 .455 20 35 9 9 3 2 220 6.040X+04 5.9064E-02 5.3177E 10 6.0408E404 1.5350E403 6.7793E-04 2.2469E 12 1.3350E+03 240 5.6808E+04 3.1416E-01 4.X95E 10 5.6808E404 1.5621E403 3.8856E-03 2.0429E 12 1.5421EW3 260 5.282X404 1.2322E400 3.9622E 10 5.2823E404 1.5620E403 1.6331E-02 1.868X 12 1.S420E+03 280 4.8773E404 3*824X400 3.4633E 10 4.877X404 1.54271403 5.4032E-02 1.716X 12 1.5427E+03 300 4.484X404 9.8854E400 3.0491E 10 44843E404 1.5103E403 1.4836E-01 1.584X 12 1.5103E+03 .500 .545 .591 .636 .682 22 38 10 10 4 3 24 40 11 10 4 3 26 43 12 11 4 3 28 45 12 12 4 3 30 47 13 12 5 3 320 4.1134E404 2.209X401 2.7017E 10 4.1134E404 1.4692E403 3.5084E-01 1.469X 12 1.4492E+03 340 3.7693E404 4.3934E401 2.4079E 10 3.7693E+04 1*42281403 7.3567E-01 1.3666E 12 1.4228EW3 360 380 400 3.4536E404 3.1659E404 2.905X404 7.9416E40I 1.3271E402 2.0776E402 2.1575E* 1.9424E' 1.7566E* 10 10 10 3.4536E404 3.1659E+04 2.9050E404 1.3733E403 1.322X403 1.2717E403 13983E400 2.450X400 4.0143E400 1.2756E 1.1942E 1.1212E- 12 12 12 1.3733E+03 1.3225E403 1.2717E+03 .727 .773 .818 .864 .909 31 50 14 13 5 3 33 52 15 13 5 3 35 54 15 14 5 3 37 X 16 14 5 3 38 58 17 15 6 3 420 2.668X404 3.078X402 1.5949E' 10 2.6688E404 1.221X403 6.2U2E400 1.055X- 12 1.2213E+03 440 2.4554E404 43556E402 1.4536E* 10 2.4554E404 1.1726E403 9.156X400 9.9557E 13 1.1724E+03 460 480 2.262X404 2.0882E+04 5.9227E+02 7.7844E+02 1.3294E* 10 1.2198E- 10 2.2625E404 2.0882E404 1.1252E403 1.0797E403 1.2952E401 1.768X401 9.4130E8.9179E* 13 13 1.1252EW3 1.0797EW3 500 1.930X404 9.935X402 1.1225E- 10 19305E404 1.0361E403 2.340X401 8* 4648E* 13 1.0361E+03 .955 1.000 1.045 1.091 1.136 40 60 18 15 6 4 42 62 18 16 6 4 44 65 19 16 6 4 45 67 20 17 6 4 47 69 21 17 7 4 520 1.7877E404 1. 60E+03 1.0359E 10 1.7877E404 9.9452E402 3.014X401 S.M87E' 13 9.9452EW2 540 1.6583E404 1. 38E+03 9.5846E 11 1.6583E404 9.5490E402 3.793X401 7.6657E- 13 9.5490EW2 560 580 600 1.5408E404 1.4339E404 1.3366E404 1.794 403 2.103 403 2.4290E403 8.8899E 8.264SE 7.6997E 11 11 11 15408E404 1.4339E404 1.3366E404 9.1724E402 8.8147E402 8.4753E402 4.6751E401 5.656X401 6.7328E401 7.3121 6.9849 6.681X 13 13 13 9.1724E+02 8.8147E.02 8.4753E+02 1*182 1.227 1.273 1.318 1.364 49 71 21 17 7 4 51 72 22 18 7 4 52 74 23 18 7 4 54 76 24 19 7 4 X 78 24 19 8 4 620 1.2478E404 2.7668E403 7.1881E-11 1.2478E404 8.1534E402 7*897X401 6.3992E 640 660 680 1.1667E404 1*0924E404 1.0244E404 3.1135E403 3.4656E403 3.8200E403 6.7234E-11 6.3002E-11 5.9138E-11 1.1667E404 1.0924E404 1.0244E404 7.8480E402 7*558X402 7.283X402 9.144X401 1.0463E402 11847E402 6.1363E 5.891X 5.6616E 700 9.6184E403 4.1736E403 5.5602E-11 9.6184E403 7.0232E402 1.328X402 5.4467E 8.1534E+02 7.8480E402 7.3S8SE.02 7.2838EW2 7.0232E+02 1.409 1.455 1.500 1.545 1.591 57 80 25 20 8 4 59 82 26 20 8 4 61 84 26 21 8 4 62 X 27 21 8 5 64 87 28 21 9 5 VAB.0001093747 FIGURE 2 Page 1 of 2 PC-C A TRPUF - MODS COPYRIGHT 1985 TRINITY CONSULTANTS, INC* A PUFF MODEL DEVELOPED BY TRINITY CONSULTANTS, RICHARDSON, TEXAS 214/234-8567 EXAMPLE OF TRPUF5 RELEASE AMOUNT (POUNDS) = 20500 RECEPTOR HEIGHT ABOVE GRADE (FEET) MOLECULAR WEIGHT * 64.00 AMBIENT TEMPERATURE (DEG F) * 88.00 EXIT VELOCITY (FEET PER SECOND) STACK DIAKE1ER (FEET) AMBIENT PRESSURE (KB) =1013,00 WIND SPEED (MPH) STACK HEIGHT (FEET) COMPUTED VIRTUAL DISTANCES (FT) HORIZONTAL VERTICAL UNSTABLE 3.3 3.3 NEUTRAL 16.4 16.4 STABLE 85.3 85*3 5. 5.000 1.50 5.0 60.00 AL CONCENTRATION (PPM) * 5.00E+05 HORIZONTAL SIGMA (FEET) > *00 AL VERTICAL SI6MA (FT) = *00 DOUNVIND DISTANCE (FT) * 0. D0UMI1NB PEAK INSTANTANEOUS CONCENTRATIONS AVERAGE CONCENTRATIONS FOR 300. SECONDS - SIGMAS (FEET) DISTANCE (FEET) UNSTABLE CUG/H3) NEUTRAL STABLE (UG/M3) MAXIMUM UNSTABLE NEUTRAL STABLE TRAVEL MAXIMUM (MINUTES) KOR V6R NOR VER HQR VER 800 900 1000 1100 1200 1300 1400 1500 /-SOO 00 7.1553E+03 5.8462E+03 4.1752E 11 7.1553E+03 5.90446+02 2.0986E+02 4.5504E 13 5.9044E+02 5.4742E+03 7.2158E+03 3*2330E 11 7*21586+03 5.0321E+02 2*88076+02 3.8755E 13 5.0321E+02 4*26821+03 8.2037E+03 2*5 11 8*20376+03 4.3417E+02 3.60256+02 3.3 13 4.3417E+02 3.4273E+03 8.82526+03 2.0 11 8.8252E+03 3.78701+02 4.2249E+02 2.9 13 4.22496+02 2.7867E+03 9.1378E+03 1.7128E 11 9.1378E+03 3.3350E+02 4.7338E+02 2.6 13 4.73386+02 2.2997E+03 9.2101E+03 2*24356-11 9.2101E+03 2.96206+02 5*13106+02 3*64226-13 5.1310E+02 1.9225E+03 9.1056E+03 3*22986-10 9.10S6E+03 2* 6504E+02 5*42626+02 5.57B9E-12 5.42626+02 1.6255E+03 1.3882E+03 8.87746+03 8.5672+03 4.26576-09 4*033IE-08 8*87746+03 8.5673E+03 2.3874E+02 2.1634E+02 5*63296+02 7.8081E-11 5.76516+02 7.79556-10 5*63296+0: 5*76516+0 1.1962E+03 8*20696+03 2*86386-07 8.20696+03 1.9709E+02 5*83616+02 5.8267E-09 5*83616+02 1*818 2.045 2.273 2.500 2.727 2.955 3.182 3.409 3.636 3.864 72 96 81 105 89 113 97 122 105 129 113 137 121 145 129 152 137 160 145 167 32 23 10 35 25 11 39 27 11 42 29 12 45 31 13 49 33 14 52 34 15 56 36 li 59 38 17 62 39 18 5 5 6 6 6 7 7 7 7 8 1800 1.0390E+03 7.8191E+03 1.60296-06 7.8191E+03 1.8041E+02 58578E+02 3*42336-08 5*85786+02 1900 2000 2500 9.0896E+02 7.4205E+03 7.3509E-06 7.42056+03 1 * 65876+02 5.8401E+02 1.64386-07 5.8401E+02 8.0039E+02 4.5860E+02 7.0225E+03 5.2344E+03 2.8491E-05 4*15626-03 7.0225E+03 5.23446+03 1.5310E+02 1.07686+02 5.7917E+02 5*29276+02 6*65616-07 1.1757E-04 5.7917E+02 5*29276+02 3000 2.8996E+C2 3.9020E+03 9.5734E-02 3.9020E+03 8.0500E+01 4 * 6614E+02 3.16956-03 4.6614E+02 4.091 4.318 4*545 5.682 6.818 3500 1.9643E+02 2.9558E+03 7.98066-01 2.95S8E+03 6.28286+01 4.0661E+02 3.0201E--02 4,06416+02 7.955 4000 1.4003E+02 22832E+03 3*60776+00 2*28326+03 5.0615E+01 3*54956+02 1.5335E-01 3.5495E+02 9.091 4500 5000 5500 1.03B2E+02 7.9402E+01 6.2281E+01 17977E+03 1* 4406E+03 1.1727E+03 1*10046+01 2.5727E+01 4.9876E+01 1.7977E+03 1.44066+03 1.17276+03 4.1762E+01 3.50871+01 2*98936+01 3.1133E+02 2*74786+02 2.4412E+02 5.1B37E-01 1.3288E+00 2.8004E+00 3.11336+02 2.7478E+02 2*44126+02 10.227 11.364 12*500 152 174 66 41 19 8 160 181 69 43 20 8 168 188 72 44 21 8 206 221 89 51 25 10 244 252 105 58 29 11 281 283 121 65 33 12 317 311 136 71 37 12 354 339 152 77 41 1* 390 366 167 83 45 14 425 393 183 89 49 15 6000 4.9885E+01 9.6808E+02 8*^806+01 9.68086+02 2.57476+01 2.1827E+02 5.2133E+00 2,18276+02 13.636 6500 7000 7500 4.0665E+01 3.3651E+01 2.8210E+01 8.0917E+02 6*83866+02 5.83686+02 1*28936+02 1.8222E+02 2*42336+02 8.09176+02 6.8386E+02 5*63686+02 2*23716+01 1.95796+01 1*72426+01 1*96356+02 1.7762E+02 1.61516+02 8.3816E+00 1*26436+01 1*78676+01 19635E+02 1.7762E+02 1*61516+02 14.773 15*909 17.045 8000 2.3918E+01 5.0261E+02 3*07106+02 S.0261E+02 1.3266E+01 1*47566+02 2.396SE+01 1.4756E+02 18.182 461 419 198 95 53 16 496 444 213 100 57 17 531 468 228 105 61 IS 566 493 243 111 65 IE 600 516 258 116 68 19 8500 9000 10000 10500 11000 2.0482E+01 4*36256+02 3.7435E+02 4.3625E+02 1.35B2E+01 1*35416+02 3.0816E+01 1.35416+02 1.7694E+01 3.81386+02 4*42116+02 4.4211E+02 1*21376+01 1.2475E+02 3.8274E+01 1.24756+02 1.3510E+01 2.97066+02 5.727 1.1923E+01 2*64386+02 6.33 1*05831+01 2*36476+02 6.89 +02 5*72766+02 9.8079E+00 1.0700E+02 5.4414E+01 1.07006+02 +02 6.3328E+02 8*86426+00 9* 6.2811E+01 9.95546+01 +02 68952E+02 8.03786+00 9* 7*12576+01 9.28796+01 19*318 20.455 22.727 23*864 25.000 635 540 272 121 72 20 669 563 287 126 76 2: 737 608 316 135 83 22 77! 630 331 140 87 23 805 651 345 145 91 23 11500 12000 12500 13000 13500 9.4439E+00 2.1247E+02 7.41026+02 7*41026+02 7.31106+00 8.686SE+01 7.96456+01 8.6865E+01 8.4680E+00 7.6266E+00 1*91726+02 1.7368E+02 787526+02 8*28936+02 7.87526+02 8*28936+02 6.669SE+00 8*14226+01 6,10126+00 7.64736+01 8.7887E+01 9.59086+01 8.78876+01 9.59086+01 6.8971E+00 1.57906+02 8*65326+02 8.65326+02 5.59606+00 719576+01 1.03656+02 1.03656+02 6.26096+00 1 * 4404E+02 8*96826+02 8.9682E+02 5.14546+00 6.7820E+01 1*1107E+02 1.11076+02 26.136 27*273 28.409 29.545 30.682 838 673 872 694 905 715 938 736 971 757 360 149 94 374 154 98 388 158 102 402 163 105 417 167 109 24 25 25 26 26 FIGURE 2 var 0001093748 Page 2 of 2 PC-C L'OPTRIBHT 1985 TRINITY CONSULTANTS^ INC RENDING DATA* * PLOT TYPE* (UNILINEAR, L06*L06-LD6)? L06 ih NININIM DOWNWIND DISTANCE (FEET) (USE 0 FOR AU. DISTANCES)? 0 ^*4XINUH DOWNWIND DISTANCE (FEET) (USE FOR AIL DISTANCES)? 0 ENTER I FDR INSTANTANEOUSi A FOR AVSRAGE CONCENTRATIONS I SELECT THE STABILITY CLASS - ENTER U - UNSTABLE N * NEUTRAL S - STABLE N - HAXIAUH OF THE THREE STABILITIES ENTER U, N, Sr OR NT H * FIGURE 3VAB.0001093749 MAXIMUM CONCENTRATIONS (U G /M ; )FOR ALL STABILITIES h EXAMPLE OF TRPUF5 m o + PC-C figure 4 VAB.0001093750 EXAMPLE OF TRPUF5 PC-C 4 # M 0.00 * 25.00 40.00 55.00 70.00 DISTANCE (FT) + 101 85.00 100 00 FIGURE 5 VAB.0001093751 PRACTICAL PLANNING FOR TOXIC GAS RELEASES July 31, 1985 Your evaluation of this course would help make future workshops more useful to others. Would you please fill out this evaluation and return it in the enclosed stamped envelope. Coverage of Subject Technical Depth Usefulness Appropriate Appropriate .Very Practical Too Little Too Simple Average Too Much Too Advanced Limited Organisation of Material Presentation Length of Course Well Planned Good Too Long Average Average Too Short Poor Poor .About Right How would you rate the course overall? Exce1lent Good .Adequate Unsatisfactory If given again, would you recommend the course to your associates? Yes ____No PLEASE CONTINUE ON REVERSE SIDE TRINITY CONSULTANTS, INC VAB.0001093752 H List those topics that you would like to have more time spent on. List those topics that you would like to see omitted or cowered only briefly. List suggestions for improvement in regard to material, lectures, or facilities. THANKS! TRINITY CONSULTANTS, INC mmf UK 4 PRACTICAL PLANNING FOR TOXIC GAS RELEASES Richard H. Schulze July 31, 1985 Trinity Consultants, Inc. 100 N. Central Expressway Suite 600 Richardson, Texas 75080 (214) 234-8567 TRINITY CONSULTANTS, INC. /ftffitAS-*#* <Eyj u/**V} 6"/> ta Ss-v </ -- 0-4&4K T^cJlk EtP^ >,t>>6>*^ . Ofaux* CO^S^K. (3si/Oo v) J2o/fW&~ ' VAB.0001093755 PRACTICAL PLANNING FOR TOXIC GAS RELEASES REGISTRATION LIST # Houston, TX - July 31, 1985 Mr* Allen Jurislch Senior Program Advisor, Environmental Service Cigna Loss Control 139 Vest Livingston Place Metairie, LA 70005 (504) 831-1617 Mr. John Brau Employee Relations Manager Sohio Chemical Company Box 659 Port Lavaca, TX 77979 (512)552-8218 Mr. Joe Ledvina Director of Environmental Activities Vista Chemical Company P.0. Box 19029 Houston, TX 77224 (713)531-3451 Ms. Ailleen Teng Senior Environmental Health Specialist Cigna Loss Control Service 12815 Leader Houston, TX 77072 (713)933-1826 Mr. Ron Pertuit Texas Eastern Company P.0. Box 7444 Longview, TX 75607 (214) 236-5000 ext. 2760 Mr. Joe Woolbert Texas Eastern Company P.0. Box 7444 Longview, TX 75607 (214) 236-5000 ext. 2760 TRINITY CONSULTANTS, INC PREFACE TABLE OF CONTENTS I Introduction A. Regulations Affecting Toxic Gas Accidents B. Affected Industries II Atmospheric Turbulence A. Description of Turbulence B. Categories of Atmospheric Turbulence III Plume Dispersion A. Gaussian Models B. Accuracy of Models C. Pasquil1-Gifford Coefficients D. inuous E. Puff F. Puff Model Dispersion Coefficients G# Average Concentrations from Puff Releases H. Puff Equations I. When to Use Puff or Continuous Release Models IV Initial Cloud Size and Building Wake Effects A* Accounting for Initial Cloud Size -> B. Virtual Distance Method C. Conversion of Concentration Units D* Obstructions V Effective Stack Heights A, Briggs1 Buoyancy Formula 1 Buoyancy Flux 2. Wind Speed 3. Restoring Acceleration 4. Size of Plants B. Plum Rise of Flares .1. Calculating F from Heat Release 2 Losses Due to Radiation 3. Effect of Addition of Steam C. Briggs' Momentum Formulas VI Toxicological Considerations A. Chronic and Acute Toxicity B. Air Contaminant Limits in the Work Place C. Air Contaminant Limits in the Ambient Air D* Time Averaged Concentrations E. Method Used by EPA for Chronic Toxicity Studies 4 1 1 3 6 6 13 24 24 25 26 26 37 38 41 45 45 48 48 50 51 52 58 60 63 64 65 66 66 68 70 71 77 80 80 81 83 84 87 TRINITY CONSULTANTS, INC___________VAj90tfiO93758 VII, Large Spills and Heavy Gases A. Common Dilute Clouds B. Description of Spills 1, Liquid Spills 2, Liquid Gas Spills a* Small Hole in Vapor Space b. Large Hole in Vapor Space c. Hole in Liquid Space d. Dense Gas Cloud e. Description of Releases f. Shape and Characteristics of Dense Gas Clouds g. Modeling Dense Gas Clouds 3, Gas Spills C. Bursts with Continuing Emissions D. Lover Flammable Limits VIII Location of Spills and Data Required A. Transportation B. Accidents at Plant Sites IX. Techniques for Reducing Risk X. Computer Models A. SPILLS B. SAFER C. CHARM D. CARE E. HASTE F. EPCHEMS II G. MESOCHEM, JR. H. Other Systems I. EPA Puff J. TRPUF K. PTPLU L. PAL K. ISCST N. VALLEY O. TEM8 XI. Evaluation of Risks A. Development of Accident Scenarios B. Causes of Failures C. Hazard and Operability (HAZOP) Studies D. Risk Analysis 1. Analyzing Risk 2. Computer Model 3. Value of Risk Analysis 90 90 91 91 93 93 94 95 95 97 99 101 102 102 103 105 105 110 121 121 124 127 128 129 130 130 131 131 132 137 137 138 142 144 148 148 150 151 152 152 154 155 TRINITY CONSULTANTS, INC **!&I01093759 FIGURES 1. Average Wind Speed Anniston Airport (Surface) and Plant (500* Elevation) 2. Description of Atmospheric Stability Categories 3. Combinations of Wind Speed and Stability Analyzed by PTMAX 4. Frequency of Occurence of Wind Speed and Stability Combinations 14 15 17 19 5. Coordinate System Showing Gaussian Distribution in the Horizontal and Vertical 6* Vertical Dispersion Coefficient as a Function of Downwind Distance from the Source 7 Constants Used to Calculate in EPA Developed Programs 8. Horizontal Dispersion Coefficient as a Function of Downwind Distance from the Source 27 22 .9. Constants Used to Calculate Oy in EPA Developed Subroutine DBTSIG 10 Horizontal Dispersion Coefficients - Pasquil1-Gifford and those for Quasi-Instantaneous Releases 32,33 39 11. Vertical Dispersion Coefficients - Pasquil1-Gifford and those 40 for Quasi-Instantaneous Releases 12. Dispersion of a Puff from a Pipeline Break 42,43,44 13. Growth of Wake 14. Ratio of Calculated to Observed Values of Ah 15. Schematic Mollier Chart 16. Safety Factors Used to Derive Acceptable Ambient Concentrations from Occupational Limits 54 61 73 85,86 17. Guide 20 - Emergency Response Guide Book (1984) 18. Table of Isolation & Evacuation Distances 19. Station for Collecting Meteorological Data 20. Major Differences Between TRPUF and EPA Puff Models 107 108,109 112 134 21. Tabular Output of TRPUF 22. Graphical Output of TRPUF 23. Terrain Adjustments for Selected Gaussian Models 135,136 237 145 TRINITY CONSULTANTS, INC 4 AB.ea01093760 INTRODUCTION The purpose of this manual is to help the engineer, safety 4 specialist or other technically trained person prepare for and evaluate the dispersion of a potentially toxic gas. Some compounds will enter the atmosphere as a gas while others will be the result of evaporation from a liquid pool. Interest in this subject, at least judged by inquiries to our firm, has increased steadily since 1980. It was the tragic events in Bhopal, India, in December, 1984, that has galvanized corporations and regulatory agencies to re-examine their contingency plans. A. Regulations affecting Toxic Gas Accidents For the most part, toxic gas releases are not subject to environmental regulations. In contrast, oil spill planning is. In 40CFR112, detailed requirements are set forth for the preparation of Spill Prevention Control and Countermeasure Flans (SPCC Plans). The preparation of plans is required if an organization stores more than 42,000 gallons in an underground tank or 1,320 gallons in above ground containers. Surprisingly, no such plan is required for the discharge of hazardous substances in waste waters but the reporting of such a discharge is required by 40CFR116 and 117. In general, the response to any toxic gas accident is handle 1 TRINITY CONSULTANTS. INC local public safe*-" fire department. 1 -- *,*fc* T5--1 - -- - In nearly all plan is a decisioi L transports or sto In some instanc involved vith the or transporter of Outside the Unite addres sing the p 1982 No. 1357 is Handling Hazardous Substances Regulation". S.I. 1984 No. 1902 is entitled "The Control of Industrial Hajor Accident Hazards s Regulations". The first of these regulations enabled the Health Safety Executive to identify installations and define priorities for inspection programs. The second requires, among other things, the preparation of a hazards analysis, an emergency plan, and an off-site emergency plan. It also requires that members of the public living in the vicinity of an industrial activity be informed about the activity and associated hazards. The Appendix contains a flow chart of the regulations taken from the Health Safety Executive Guide for the 1984 regulations. These regulations implement Directive 82/ 501/EF'* 2 TRINITY CONSULTANTS, INC. w-------------- mmmmm Communities* In February, 1985, the World Bank issued a draft guideline entitled "World Bank and IFC Guidelines for Identifying, Analyzing and Controlling Hajor Hazard Installations in Developing Countries". It is based on the two British regulations and is currently used to evaluate proposed facilities in developing countries that are seeking funding from the World Bank. This draft is included in the Appendix. B. Affected Industries There are certain indu" ristries and organizations that have risks associated with toxic gas releases. Broadly speaking, releases can occur in transportation accidents or at plant or warehouse sites The chemical industry manufactures materials such as chlorine and ammonia. In addition, the plant chemical industry uses a number of toxic gases as intermediates in the production of final products. These include phosgene, phosphine and the cause of the Bhopal disaster, methyl isocyanate. Chlorine is the most ubiquitous of the hazardous it widely country for drinking water treatment swimming pools Anmonia is alsc widely used, primarily as a fertilizer. Ethylene oxide is used in the sterilization of equipment, ---------- TRINITY CONSULTANTS, INC=^abW)93763 A V i supplies and disposable items used in the medical field* Although large volume sterilizers such as the manufacturers of plastic disposables have facilities equipped with scrubbers, many smaller users, such as hospitals, do not. About 20 percent of the natural gas produced in the United * States contains some hydrogen sulfide vhich must be removed before the gas is delivered to common--carrier pipelines. There is risk both in drilling for gas and in processing the gas. Hydrogen sulfide is also of concern in refineries where up to several tons of the compound can be contained in pipelines or process vessels. The liquid extraction of elements such as sulfur or bromine often involves processing hydrogen sulfide* The semi-conductor industry uses some unusually toxic gases such as arsine, hydrogen selenide and phosphine in the manufacture of wafers. As the use of metal--organic vapor phase epitaxy reactors come into wider use, increased quantities of these hazardous gases will be used. Human error is another major cause of toxic gas releases. Hater in place of nitrogen was introduced to the storage tank of methyl isocyanate in Bhopal. Operators have pumped a caustic solution into a sulfuric acid tank. Haintenance personnel have used inappropriate chemicals to clean a contaminated tank. Material in an epoxy resin blending tank got too warm and started a reaction which caused a cloud of gas to drift over a Transportation spills are difficult to assess. The most elaborate system is operated for the Department of Defense by Lawrence Livermore Laboratory. If a nuclear weapon accident occurs anywhere in North America as a result of a plane crash, a missile silo accident or other cause, the direction and concentrations in the released material can be forecasted. More comnonly, however, a trucking or railroad accident occurs and local public safety officials do the best they can to reduce the risk to those nearby. The most difficult task, however, is to determine the quantity of gas released. When a tank car is laying in a ditch it is difficult to determine whether the tank has a small puncture or a large gash. The major uncertainty in most situations is the value of the "source term", that is the quantity that is or was actually introduced into the atmosphere. Next, in order of uncertainty, are the meteorological parameters. Finally, there is the inherent uncertainty regarding the accuracy of the model. Ixj summary, there is usually a great deal of uncertainty, and thus, most analyses of actual or potential accidents tends to stress the "worst case". 4 5 TRINITY CONSULTANTS, INC. 1 093765 A II. ATMOSPHERIC TURBULENCE A. Description of Turbulence Atmospheric turbulence is caused both by the wind and by surface heating and cooling (thermal) effects. The meteorological terms are mechanical and convective turbulence.1 A* An atmosphere that is well mixed because of strong winds - vigorous mechanical mixing in meteorological terms - under overcast skies is termed "neutral." Under these conditions, there are no surface heat ing or cooling effects and the temperature decreases with altitude at the "ADIABATIC LAPSE RATE". Lapse rate is the change in tern- I perature with elevation. This is illustrated as follows: HEIGHT ABOVE GROUND z or h Pasquill Stability Class D ADIABATIC LAPSE RATE IS -5.4F/1000 FT OR ''>-0.01 C/METER DUE TO MECHANICAL TURBULENCE ONLY. This condition is typical of over cast days and nights with strong winds. TEMPERATURE This is an idealized illustration. The actual lapse rate shows a variable change in slope, particularly with lighter winds. In 6 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75231 * the Pasquill system of categorizing stability, this condition is called D. Sometimes meteorologists refer to the potential lapse rate. This term is equal to the actual temperature lapse rate less the adiabatic lapse rate. For example if the actual lapse rate is 0.01C/m, the potential lapse rate is 0.02*C/m (O.Ol-(-.OD) If the winds are moderately strong, in excess of 10 m/sec, the atmosphere is well mixed from the surface to the top of the boundary layer. The boundary layer is usually defined by an upper air inversion, where the es positive or nearly s under overcast skies, the atmosphere can When of a number of mixing zones. Surface friction will create a turbulent meters laminar Above this will be zones that The gradual. The primary source of surface heat on the earth is the sun, or more exactly, solar radiation. As the sun rises in the morning or as an overcast sky becomes partly cloudy, a larger amount of solar radiation reaches This causes the air near warm and "cells" of this warm air start to rise much as steam is formed on the bottom surface of a pot of boiling water. amount radiation reaching the surface is determined largely by the cloud cover and 7/85 7 TRINITY CONSULTANTS. INC * 1093767 the elevation of the sun (solar insolation). The more direct the sunlight, the more heating of the surface and the greater the thermally induced, convective, turbulence. As the cells of warm air leave the surface, they are replaced by downward moving cells of colder air. condition is typical of sunny days when the sun has warmed the earth. is called "unstable," peradiabatic," "overturning," advecting" because of thermally induced turbulence. The unstable conditions have been subdivided into three categories by Pasquill: A, B, or C. Turner refined Pasquill's definitions somewhat to facilitate the use of computers to determine stability from routine surface observations. Category A applies when the sun is 60 or more above the horizon and the sky is cloudless or nearly so. Category B applies when the sun has less elevation or the sky is cloudier. Category C is only slightly unstable. Under 8 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS. TEXAS 73231 VAB.0001093768 these conditions, the lapse rate Is called "superadiabatic," "overturning," "unstable," or "advecting". Since about 1972 a number of studies have been conducted to help in understanding convective turbulence better. Briggs enumerates these in a 1975 review. During the day, convective turbulence strongly mixes the lower atmosphere, but this mixing ends abruptly at the top of the mixing layer. Nearly all of the time there is a stable air (a lapse rate with a positive slope) layer aloft that acts as a lid on mixing. In rural areas on clear mornings the mixing zone starts as a shallow layer near the ground 4 at sunrise and continues to increase during the day as long as t the radiation input from the sun exceeds the earth's outward radiation. The lower boundary of the upper air stable layer increases in height as more of this stable air becomes involved in the convective turbulent layer. The temperature gradient is superadiabatic only in the lowest tenth or so of the mixing depth and just slightly less than adiabatic above this. The mixing layer consists of upward ther mals carrying heated air from the surface and of compensating downdrafts. The turbulence is much greater inside the thermals than in the subsiding downdrafts. Extremely unstable conditions 9 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS. TEXAS 75231 * -- VAB.0001093769 can only exist during periods of light winds. Moderately unstable conditions can exist with winds up to moderate speeds. As night comes and solar radiation ceases, the earth cools as it radiates heat. The earth, like the sun, radiates heat in propor tion to the fourth power of the absolute temperature. In the absence of wind, the cooling air near the surface shrinks in volume and tends to settle. This results in cool air tending to "drain" downhill. For example, in the fall, frost will most often first occur in the valleys rather than on the tops of the hills. LATER AT NIGHT EARLY EVENING This condition is typical of relatively cloudless nights with light winds. The elevation at which the actual lapse rate reverses is the depth of the "inversion layer". This condition is called "stable". Pasquill divided the stable conditions into two categories. 10 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75231 "i--* I VAB.0001093770 Stability E applies with clear nights and moderate winds or partly cloudy nights and light winds. Stability F applies to calm clear nights in rural areas. The United States Environmental Protection Agency uses a potential lapse rate of 0.02*C/m for E and 0.035*C/m for F stability or actual lapse rates of 0.01#C/m and 0.025C/m respectively for E and F. During the Arctic winter, rather severe inversions can occur. During extended periods of cloudless still days with virtually no sun, lapse rates of .036 to .055 degrees per meter are not uncommon in places s such as Fairbanks, Alaska. Strong inversions can also occur at the surface as warm winds blow across cold bodies of water. This is typical of spring conditions on the Great Lakes. It can also occur as cold winds are drawn in across land such as in the Los Angeles basin. Stabilities stronger than E or F are sometimes referred to as G and H. mornings ally induced turbulence starts at the surface and gra The increases in depth as it erodes the stable layer from beneath. The inversion layer generally disappears within 5 to 7 hours after sunrise 7/85 11 TRINITY CONSULTANTS, INC. / YA& t NEUTRAL STABLE UNSTABLE This condition is typical of the period after sunrise when the sun starts to warm the surface and the night-time inversion starts to disappear. Mixing takes place only within layers in the atmosphere, not between the layers. Thus in the morning situation just described, the layer closest to the ground will be very well mixed due to motions The emitted forms If pollutants were they would remain in this layer until the unstable layer erodes the stable layer and reaches a depth equal to the centerline of the plume. At this point, the pollutants will be mixed rapidly in the un stable layer. Meteorologists call this condition "Inversion Breakup Fumigation". 12 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS. TEXAS 75231 f" Under Cyplcal daytime conditions, after disappearance of the noc turnal inversion layer, the surface boundary layer continues to have a reasonably well-defined upper limit that is usually between 500 and 2000 meters deep. At night the surface layer is stable in nature and is not nearly as deep as the daytime layer because of the absence of ground thermals. 3 i The diurnal changes in the atmosphere are illustrated in Figure 1. It shows average wind speeds by hour for the 27 days of June at an Alabama location at a 10-meter elevation and at a nearby 150- meter elevation. It is apparent that there is a strong inversion at night. The surface wind speed is a small fraction of the wind aloft. By about 0900 the surface has become warmed so that good vertical mixing is occurring and the winds at the surface are equal to those aloft. This condition continues past mid-day when the cumulus clouds start to increase. By evening the winds subside. At night only the aloft winds increase, suggesting a surface-based a inversion. B. Categories of Atmospheric Turbulence Figure 2 is the description of Atmospheric Stability Categories taken from Turner's "Workbook of Atmospheric Dispersion Estimates 11 This table is similar to that on page 368 in F. Pasquill, "Atmo- 13 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75331 / a^V4- * ^fMt * 4P# * # ^ * * | -r ' * t *' ! +-> ^ 1 ^ '' J * * * - ^4* . **^***aVT i* * W* A* + + 4 '*< * ' t 1................................................................................^ * ' -- * ---- "' ' ' " a4 * ' M" ' ." * t J t 1 I "/"'*' 4 t * ^ -- " -- t * * |* * -- -! ^ * * * P # ----- -f---a, ^ ^ *4-* ^ g 4 t M r i *#* M * * ** ! * * * * * * | -- -- -- - * 1 Ml P *m ^4 *-#** " M S **<*# *' '* '* 11 . . "' JE FIGURE i AVERAGE WIND SPEED AT ANNISTON AIRPORT (SURFACE) AND CSl>0a33dS QNIM 4 FIGURE 2 DESCRIPTION OF ATMOSPHERIC STABILITY CATEGORIES KEY TO STA3ILITY CATEGORIES* Surface Wind Speed at 10 ra Altitude 2.24 MPH * 1.95 Knots 3.6 KPH 1.0 m/sec Day Incoming Solar Radiation Strong Moderate Slight Night Thinly Overcast or >4/8 Low Cloud <3/8 Cloud <4.5 <3.9 <2 A A-B B 4.5-6.7 * I 6.7-11.2 3.9-5.8 5.8-9.7 2-3 3-5 A-B B B B-C C C EF DE 11.2-13.4 9.7-11.7 5-6 C C-D D DD >13.4 >11.7 >6 CD D Dn The assumed conditions during day or night, Night refers to a period from 1 hour before sunset to 1 hour after sunrise. For pur-^*"^ computer 2, etc. "Strong" incoming solar radiation corresponds to a solar altitude greater than 60 with clear skies in midsummer; "slight" insolation corresponds to similar conditi in midwinter or to a solar altitude from 15 to 35 with clear skies in midsummer Cloudiness will decrease incoming solar radiation and should be considered along with solar altitude in determining solar radiation. Incoming radiation that woul be strong with clear skies can be expected to be reduced to moderate with broken (5/8 to 7/8 cloud cover) middle clouds and to slight with broken low clouds. wind used when forecasting to result in ambient concentrations with f less than 2 meters per second (4.5 KPH or 3.9 knots). At low ds tend to meander widely. In addition , surface wind speeds at rarely indicative of aloft velocities or of upper air stability lity categories are reliable in open, rural areas. In urban and heavily wooded , the surface roughness and heat islands have an effect on the category, par ticularly on still nights. On calm clear nights stability E or F night occurs in rural areas where D is likely to occur over urban areas. *D. Bruce Turner, Workbook of Atmospheric Dispersion Health, Education, and Welfare, Revised 1970. 15 TRINITY CONSULTANTS P.O. BOX 3145 i DALLAS. TEXAS 7S231 , U.S. Department of spheric Diffusion" (second edition). Turner defined stabilities in terms of solar insolation angles and cloud cover instead of such terms as "sunny midday in summer in England" used by Pasquil Turner also omitted a notation Pasquill used in his table which reads "for A-B take average of values for A and B etc." The Appendix contains the description of a computer algorithm that determines stability category from routine surface meteorological observations that is used ? STAR" program Combinations anlayzed by PTMAX, a computer by Turner that analyzes a single stack. This matrix of stabilities and wind speed in PTMAX contains some inconsistencies with Figure 2. According to Figure 2, stability A can't exist with winds in excess of 2 or 2.5 meters per second. Low wind speeds can exist for both C- and F-stabilities PTMAX also analyzes wind speeds of 4 and 5 meters per second for F-stability that, according to Pasquill's definition, cannot occur It is also questionable that any sort of modeling will be very accurate with winds of 1 meter per second or less. The National Climatic Center produces a "STAR1 frequency of stability, wind speed, and wind direction based on historical meteorological data. The degree of atmospheric tur- 16 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75231 VAB.0001093776 FIGURE 3 COMBINATIONS OF WINO SPEED AND STABILITY ANALYZED BY PTMAX WIND SPEED M/SEC.) *M ** + ft# STABILITY (PASQUILL) B=2 C=3 D=4 E =5 F=6 S***#******+**<( TSJSfffST*! 4*5 10.0 12.0 15.0 20.0 *#*+f++*+4**++*# *****4*| :;taaa:::a: &::: **#* ++****+ k2Siiii2Si***+***+*#*#' I*****4#****4#j****#< iti' 'V M V V uihs::::j:::E:i I*###****#*****#**** # MM* (*# **** tl k:: ** *< *******#*#* * mia *+#$! P*t**i*J; ifM4) ' MM Jtr:5r MM***MM*MM*ft**< i *#* VPTTVWPWVVV-V **+***#+*** i*m|l *> iMUtHtfOiiNitfO ' .. : >******#** lOMiiMM f 'W" '?* 1*4# was *_______ * ### ** * Mt*4 ttAM***** * :::: :::::dmiHBa:m:u: 'fMMMfMMMMniMiRnSRT. Ml **#| **###* ft# fimU2SSi&Sfi Mi* *+** ** 4#M **M* * AM* AM* *****A*Mi*M Shaded area indicates 49 combinations of wind speed and stability analyzed by PTMAX Computer Program. This program was developed by D. 8. Turner of the Environmental Protection Agency to analyze single stacks following the method described his "Workbook of Atmospheric Dispersion Estimates." ,j 17 TRINITY CONSULTANTS P.O. BOX 31481.* DALLAS, TEXAS 75231 VAB.oOo1093777 bulence is inferred from the surface observations, figure 4 illustrates the frequency distributions of wind speed and stability for New Orleans, Louisiana and Willis ten, North Dakota. It provides an idea of the relative frequency of the occurrence of various stability and wind speed combinations. i New Orleans generally has less cloudiness so it has a higher fre quency of both A-, B-, and F-stability than North Dakota. For these two locations, unstable conditions exist between 14 and 25 percent of the time while stable conditions exist between 29 and 39 percent of the time. Neutral conditions occur between 38 and 7 percent of the time. Extremely unstable conditions, Category A, occur relatively rarely. There are two other methods used by some scientists to determine stability. One relates stability to variation in wind direction. The other method physically measures the vertical lapse rate on a tower or with a balloon. The standard deviation of wind direction in the horizontal direc' M. It can be determined bv anal- yzing the directional trace of anemometer either manually or bv use of computer averaging techniques. 3elow are two schemes for 18 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS `5231 VAB.0001093778 Stability A B C D F f * Wind Speed (Kts) (m/sec) calm 1-3 4-6 TOTAL .5 - 1.5 2.1 - 3.1 calm 1-3 4- 6 7-10 TOTAL 0.5 - 1.5 2.1 - 3.1 3.6 - 5.1 calm 1- 3 4-6 7-10 11 - 16 17 - 21 > 21 TOTAL 0.5 - 1.5 2.1 - 3.1 3.6 - 5.1 5.6 - 8.2 8.7 -10.8 >10.8 m calm 1- 3 4-6 7-10 11 - 16 17 - 21 > 21 TOTAL 0.5 - 1.5 2.1 - 3.1 3.6 - 5.1 5.6 - 8.2 8.7 -10.8 >10.8 4-6 7-10 TOTAL 2.1 - 3.1 3.6 - 5.1 calm 1-3 4-6 TOTAL 0.5 - 1.5 2.1 - 3.1 New Orleans Inter- Airport Frequency Hours (percent) per Year 0.09 .20 1.02 1.31 8 18 89 115 0.34 1.24 4.09 3.82 9.50 30 109 358 335 832 0.32 0.57 3.57 8.02 1.43 0.05 28 50 313 703 125 4 13.95 1223 0.27 0.87 5.84 14.21 13.23 1.47 0.19 36.08 24 76 512 1245 1159 129 17 3162 6.83 5.54 12.37 598 485 1083 7.58 9.04 10.18 26.80 664 792 892 2348 Williston, North Dakota Frequency Hours (percent) per Year >9.26 0*14 0.40 }23 12 35 >1.00 1.73 1.09 3.82 >88 152 95 335 >1.09 2.80 5.08 1.07 0.12 0.04 10.19 ) 95 245 445 94 11 __ 4 893 <4 > 1.05 8.15 17.43 23.24 5.63 1.34 56.84 5.55 6.87 12.43 } 5.70 10.63 16.33 } 92 714 1527 2036 493 117 4979 486 602 1089 i }499 931 1430 Period of Record: New Orleans, January, 1960 - December, 1964 Sloulin Field, January, 1967 - December, 1971 19 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75231 "a t page 102, and one from the Brookhaven National Laboratory Studies as quoted "Recommended Guide for the Prediction of the Dispersion of Airborne Effluents", published by the American Society of Mechanical Engineers (ASME).4 Meteorology and Atomic Energy Stability Horizontal Direction (Degrees) 25 Stability AS ME Standard Deviation Horizontal Direction ______ (Degrees) Unstable 10.5 Stable 2 o *rj w a n w > As indicated in the table, significant wind meander is expected in unstable air. Minimal meander is typical of stable conditions. The Nuclear Regulatory Commission (NRC) uses a third method to determine stability. It is specified in NRC Guide 1.23.5 Appli cants for nuclear power plants are required to erect a tower and measure temperature at two different elevations. Most towers are 50 meters high and, therefore, measure the lapse rate only in the lowest portion of the atmosphere. This is satisfactory for nuclear ----------------- 20 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75231 applications where accidental discharges have no plume rise and dis- * perse within 100 meters of the ground. But such a technique may be misleading for discharges from tall stacks or from stacks having significant plume rises. Below is data taken by Louisiana Power and Light from a tower located within. 13 miles across flat terrain from the New Orleans Airport. Frequency of Occurrence Stability Lapse Rates C/m LP&L* 1.23 Method 7/72 - 7/75 N.0. Airport Pasquill's Method (from Table 4) A > --.0X9 14.9 B -.019 to -.017 1.7 C -.017 to -.015 2.1 1.3 9.5 14.0 D -.015 to -.005 24.1 36.0 E -.005 to .015 31.9 12.4 F .015 to .040 14.5 G > .040 10.8 }26.8 Temperature measured at 9 and 40 meter elevations One notable aspect of the NRC system is the rather narrow range of values assigned B- and C-stabilities. It appears that this was the result of an arbitrary decision by meteorologists at the NRC who incorrectly assigned lapse rates for these categories. In the opinion of many USEPA meteorologists, it is incorrect to assess stability based on measured lapse rates because it is only one of 4J i m TF 21 TRINITY CONSULTANTS P.O. BOX 31461 DALLAS, TEXAS 75231 *9 9 VAB.0001093781 I the turbulence producing mechanisms. In addition, lapse rates are typically measured in the first 50 meters of the atmosphere mos 100 to 500 meters. 22 TRINITY CONSULTANTS p.o. box 31481 Dallas, Texas 7S23i i VAB.0001093782 CHAPTER II: REFERENCES 1- David H. Slade, Editor, Meteorology and Atomic Energy, U. S. Atomic Energy Commission, Oak Ridge, Tennessee, 1968. pp. 13-116. (Available as Publication TID-24190 for $6.00 from National Technical Information Service (NTIS), Springfield, Virginia 22151). 2. F. Pasquill, Atmospheric Diffusion. 2nd Edition, John Wilgy & Sons Inc., New York, 1974. 3. D. Bruce Turner, Workbook of Atmospheric Dispersion Estimates, U. S. Environmental Protection Agency, Research Triangle Park, North Carolina, 1970. pp. 1-2. 4. Martin John R., Recommended Guide for the Prediction of the Dispersion of Airborne Effluents, 3rd Edition. American Society of Mechanical Engineers, New York, 1979. pp. 7-12. 5. Nuclear Regulatory Commission Guide 1.23. Revised 03/81 23 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75231 III. FLUME DISPERSION A Plume dispersion is a problem involving fluid turbulence. Up to now the fluid turbulence problem has resisted all attempts at a general solution. Therefore, the best present solution contains both hypothetical and empirical elements. In the final analysis, the results can only be judged by comparison with data. A. Gaussian Models Numerous experiments have been conducted to study the shape of plumes. The publication Meteorology and Atomic Energy lists over twenty experiments, many of which have been conducted by the Atomic Energy Commission (now the U. S. Department of Energy)1 In general, most investigators have been satisfied that a Gaussian distribution is a good mathematical approximation of plume behavior for periods on the order of five minutes to one hour. Although Gaussian models, properly applied, are peerless as a practical diffusion modeling tool in terms of simplicity, of flexibility and of correlations between predicted and measured values, they contain some definite shortcomings. The Gaussian distribution assumes uniform conditions in the vertical direction. In reality, the lapse rate shows changes with elevation as does wind speed. In addition, the dispersing plume will deposit material on the surface. t 24 TRINITY CONSULTANTS, INC. There is, of course, much more uniformity in the horizontal direction. Strictly speaking, the Gaussian equation implies an speed of propagation of pollutants physically unrealistic. Pasquill, however, has pointed out that the exact form of the tails of the distribution is not important as a practical matter. Accuracy of Kbdels Despite these objections, Gaussian models provide reasonable estimates in flat or gently rolling terrain. Gently rolling is N ^ ^ generally described as terrain elevations of less than twenty ^K percent of effective stack height. Turner states that the estimates provided are generally accurate by a factor of 2 (plus minus 50 percent).2 This is significantly less accurate * than most engineering calculations or work done with computers. American Meteorological Society Committee evaluated the accuracy of models and quoted Pasquill in saying that under ideal conditions, the error can be as little as 10 to 20 * percent, but "Factor of 2 accuracy is perhaps the best that can expected in most applications of urban--scale dispersion models".3 m This estimate accuracy also underscores the need for a monitoring program should calculated values start to approach the ambient air standards. It has been the experience of most of the computer models than under 25 TRINITY CONSULTANTS, INC VAS, C. Pasquil1-Gifford Coefficients Figure 5 illustrates the coordinate system of a typical plume. The downwind directior is "x," the horizontal crosswind is "v." and the vertical is u_z ir As a result of field studies. coefficients of dispersion in the y and z direction have been developed. Figures 6 through 9 show the Pasquil1-Gifford dispersion coefficients as a function of distance from the stack, both form from Turner and in formulas in several EPA models.* Although these coefficients have many shortcomings, they are those in widest current use. As discussed previously, nixing - and therefore diffusion - is more unstab1 The that diffusion in both the y and z direction is accentuated when the air is < unstable and minimized when the air is stable. D. Continuous Release Equations There are four equations that are useful for estimated ground--level concentrations. A 26 TRINITY CONSULTANTS, INC * VAB.0001093786 1,000 J DISTANCE DOWNWIND, km Vertical dispersion coefficient as a function of downwind distance from the source. TRINITY CONSULTANTS P.O. BOX 31481 DALLAS. TEXAS 75231 HIM VAB.QQOTD93788 FIGURE 7 Constants Used to Calculate o Developed Programs b ^6 DBTSIG (used in Downwind Stability Distance (x) (Paaouill) A < .1 1 - .15 .15 - .2 .2 - .25 .25 - .3 Values for a (meters) JL b 122.8 158.08 170.22 179.52 217.41 .9447 1.0542 1.0932 1.1262 1.2644 5 Ji Downwind Distance (x) TEH. TCM b_ 100 - 500 .0383 1.2812 .3 .4 .5 > 3.11 .4 .5 3.11 258.89 346.75 453.85 1.4094 1.7283 2.1166 * 500 - 5000 .000254 2.0886 B < .2 90.673 .93198 .2 - 4 98.483 .98332 100 - 500 .1393 .9467 .4 - 35.0 >35.0 109.30 1.0971 * 500 - 5000 .04936 1.1137 C >123.0 <123.0 61.141 .91465 * 100 - 500 500 - 5000 5000 -123000 .1120 .1014 .1154 .9100 .9260 .9109 D < .3 34.459 .86974 DAT .3 - 1.0 1.0 - 3.0 32.093 32.093 .81066 .64403 100 - 500 500 - 5000 .0856 .2591 .8650 .6869 > 3.0 - 10.0 33.504 .60486 5000 - 50000 .7368 .5642 A CT2 - ax DBTSIG (used in PTMTP. ISC. CRSTER. RAM) Stability Dovmrind Distance (x) Values for a z (meters) Downwind Distance (x) 24*260 k 83660 (meters) ___ a EU (cm fc TCM) .1 .3 .3 - 1.0 1.0 - 2.0 23.331 21.628 21.628 .81956 .75660 .63077 100 - 500 500 - 5000 5000 - 50000 .0545 .2017 1.5763 .8124 .6020 .3606 2.0 - 4.0 4.0 - 10.0 10.0 - 20.0 20.0 - 40.0 >40.0 22.534 24.703 26.970 35.420 47.618 .57154 .50527 .46714 .37615 .29592 E (TEH) 100 - 500 500 - 5000 5000 - 50000 .1094 2452 9204 .7657 .6358 .4805 - P < .2 15.209 .81558 F (TEK) .2 .7 14.457 .78407 100 - 500 .05645 .8050 .7 - 1.0 13.953 .68465 500 - 5000 1930 .6072 5000 - 50000 1.505 .3662 1.0 - 2.0 13.953 .63227 2.0 - 3.0 14.823 .54503 3.0 - 7.0 16.187 .46490 7.0 - 15.0 15.0 - 30.0 30.0 - 60.0 >60.0 17.836 22.651 27.074 34.219 .41507 .32681 .27436 .21716 Example Calculation: pncrp cm C-Stability 3000 meters .91465 - 61.141(3.0) .9260 - .1014(3000) 167.0 168.2 30 TRINITY CONSULTANTS, INC / 10,000 1,000 b m ttirs .1 Its* ,M -tff M IM* -W 4H- * t4*i IM* 'fT 44* Hit tm m im ^ m *v It#* . 4tN w* .. Ml Mil ill,, L|r| H-- Pll iBH rtli. IW4MI IIP-* I^Ml-'hir-* AJMi flIFH iiMli ** HMt tIM W|l *H| tmm mm rttal 14*4 -hfH* Mil 44 IM 'Hm Mu mm **p -M" Mfll itw -> hn. lM|l kn .w. B4|p III. HM x-f m\> m- ttfti ** 0.1 *. 4 * >* < V* l Mt n l f 1111 i1 tl n M TM <1 * r. i Ifr- Hi l : ta i i r 1 . I I. .' h k I iik. H m J * K * J < H ! D i I -H p ............................................................................................................................... . 1 DISTANCE DOWNWIND, km 10 Horizontal dispersion coefficient as a function of downwind distance from the source. 100 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75231 J AD.0001093791 FIGURE 9 Constants Used to Calculate in EPA Developed Subroutine DBTSIG 1000 zb sin 9 2,15 cos 9 465*12 xk tan 6 xk downwind distance in Kilometers Stability (Pasquill) Value of 6 (radians) A 24.167-2*5334 log^ xk 57.2958 B 18.333-1.8096 logg xk 57.2958 C 12.5-1.0857 loge zk 57.2958 D 8.333-.72382 lo 57.2958 E 6.25-.54287 57.2958 F 4.1667-.36191 log (Conti-ued on next page) 32 TRINITY CONSULTANTS, INC VftBtf001093792 FIGURE 9 (continued) Example calculation: C-Stability 3000 meters 12.5 - 1.0857 ln3. 57.2958 12.5 - 1.0857 e 1.099 _ 11.307 57.2958 " 57.2958 .19735 (465.12)(3.)(tan.19735) - (465.12)(3.)(.19995) - 279.0 Constant. Used to Calculate a,, in TEH Stability (Pasquill) Downwind Distance (x) __ (otters )__ A <10,000 >10*000 B <10,000 >10,000 C <10,000 >10,000 D <10,000 >10,000 E <10,000 >10,000 F <10,000 >10,000 Example calculation: C stability 3000 meters Oy * c** Values for ay (meters) cd .495 .606 .873 .851 .310 .523 .897 .840 .197 .285 .908 .867 .122 .193 .916 .865 .0934 .912 .141 .868 .0625 .911 *0800 .884 90 8 ay - (.197)3000* - 282.9 33 TRINITY CONSULTANTS, INC__________ _____YAE-Q where the term exp- a b a b This equation is valid if the source emits If only ground level concentrations are of Interest then * z*0 and the equation becomes (2) X (xty,o;H) exp { - ITOyOjgU And if only center line concentrations are of Interest equation } (3) X (x,o,o;H) If the point of effective plume is: is at ground level and there is no 0) then the centerline concentration (x,o,o;o) 1TOyOzU \ where x " ground level concentration (grams per cubic meter) Q * source strength (grams per second) ir - 3.1416 Oy * horizontal dispersion coefficient (meters) (Figure 10) oz vertical dispersion coefficient (meters) (Figure 8) u * wind speed (meters per second) H * effective stack height (meters) * 34 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS, TEXAS 75331 VAB.0001093794 It is estimated that 80 grams per second of hydrogen sulfide is being emitted from an extinguished flare petroleum refinery at an average effective height l> * of 60 meters. At 8 a.m. an overcast winter morning with the surface wind of 6 meters per second, what is the ground level concentration directly downwind from the refinery at a distance of 500 meters? SOLUTION: Q- 4 Use equation 3 80 X it(36.1) (18.3)6 1 ' 60 } 2 2 18.31 6.42 x 10-3 exp [" 2 2 (3- 28) /8-i u_ (o (Aa/i - \ (3.28)2 \ (10.75) -5.37 1 1 216 6.42 1A-3 -6 X nrX 10 29.7 x 10 grams/meter3 30ug/m3 35 TRINITY CONSULTANTS. INC 093795 4 E. Description of Puff Release The dispersion of a puff can as the continuous release. In continuous model the plume disperses in the vertical (z) and horizontal cross wind (y) direction. In a puff model the dispersion takes place in the z,y and dovnvind (x) direction. The calculated concentration is peak instantaneous of wind speed. When a release occurs the gas forms a spherically-shaped cloud just above the point of release. The concentration in the cloud is highest at the center. The cloud then is transported by the vind groving in size as it entrains ambient air. The grovth of the cloud and its movement can be compared to a balloon that gradually inflates as it is moved by the vind. The mass of the gas in the cloud does not change as the cloud moves dovnvind, but its concentration does, as more ambient air is entrained. Sometimes the release is not instantaneous but takes place over a period of several minutes such as vhen gas in a cylinder leaks out or during the interval betveen the time a leak in a valve is discovered and it can be stopped. In cases such as these the cloud may become somevhat elongated and look like a blimp or a hot dog. By assuming an instantaneous release a puff model vill overestimate peak concentrations, but it vill have virtually no effect on average concentrations provided the averaging time is long enough. 37 TRINITY CONSULTANTS, INC__________ * VAR.O A Hie EPA puff model uses dispersion coefficients developed by studying instantaneous 6 These coefficients generally provide for less plume dilution than the familiar Pasquil1-Gifford coefficients. The table shovs the dispersion coefficients Figures 1 and 2 plot the coefficients on a diagram of the Pasquil1-Gifford coefficients. Coefficient b where x is downwind distance in meters Stabilitv Horizontal (z and y) b Vertical (z) a Unstable .14 .92 .53 .73 Neutral .06 .92 .15 .70 l!L Very Stable .02 .89 .05 .61 r p \ \ Since the dispersion in the x and y direction are generally i t I I considered to be equal, some authors refer to the standard I deviation in the horizontal as or (r for radius). 4 l i 38 * TRINITY CONSULTANTS, INC. * V'AHIlOOl093798 10,000 : :.gure 0 8 b r r4* pH n rj a 4* nn I4-- --H ih -p + 4- 4i IrH-^H 9 *'* * * b> * * **-1 FT- C' ***** 4 U*"v s MOM Horizontal dispersion coefficient as a function of downwind distance from the source 39 TRINITY CONSULTANTS P.O. BOX 31481 DALLAS. TEXAS 75231 VAB.0001093799 TV W1 o 1,000 ^ I riA i4V4 N '***-*91 ***< t *# *-F-#MJ* hmmm'Jp ir*Zr 1 *4t^p -b4" J p^l, 'V~ JipB!wv * m |*Mi* 1 * ^ 1-* * * 100 b t 10 A 1.0 0-k^ *5^ DISTANCE DOWNWIND, km Vertical dispersion coefficient as a function of downwind distance from the source. 40 TRINITY CONSULTANTS P.O. BOX 31481* DALLAS, TEXAS 7S231 VAHIRXO1093800 6. Average Concentrations from Puff Releases The average concentration is a function of wind speed. For example, a wind of 10 knots will transport twice as much air past a Bite as wind of 5 knots. The average concentration is a function of the number of standard deviations in the horizontal direction (sigma*"** or sigma--r) that pass a given point for the averaging time in question. At long downwind distances and low wind speeds the average concentration will not be much less than the peak instantaneous concentration. The puff has become so dilute that possibly less than one sigma passes a point for the averaging time specified. At the other extreme, there is a significant difference between average and peak instantaneous close to the release point. This is because the puff is sma in dimension and most material passing a point is air except for the very concentrated puff. Figure 12 illustrates how a puff would disperse fro pipeline break. 41 TRINITY CONSULTANTS. INC VAR Figure 12 A 111 cn < o LU * # NOI1VH1N30NOO 42 * VAB.0001093802 DISTANCE Figure 12 (cont'd) 43 VAB.0001093803 igure 2.2 (cont' d) U Cf) < UJ LU QC UJ u. < *) DISTANCE NOI1VN1N30NOO 44 VAB.0001093804 H* Fuff Equations The basic equation is: x 2 CTxGyiz ot l+i Bote that Q is ^a release quantity in this equation, not a release rate* v/fs a peal instantaneous concentration, not the conQece^ti IV. a dt:ri o . *JlX>rA- peak instantaneous concentration (grams per cubic meter) Q TT 3.1416 (grams) x horizontal downwind dispersion coefficient (meters) (This value is often set equal to ) y horizontal crcssvind dispersion coefficient (meters) vertical dispersion coefficient (meters) H effective stack height (meters) ! When to use Puff or Continuous Release Models The puff model should be used cloud i travel time of the cloud* For example, if the release took place over a period of 10 minutes, then it would be appropriate to calculate concentrations at receptors beyond a 10-minute trarel time using a puff model* For receptors within a 10-minute travel time distance it would be appropriate to use a puff model based on the release of a series of puffs at intervals minute model such as PAL -D TRINITY CONSULTANTS, INC j. -* / Answer Sheet Problem C * estimated that 4800 grams fro an extinguished flare a petroleum emitted effective stack height of 60 meters. At 8 a.m. on an overcast winter morning with a surface wind of 6 meters per second, what is the peak instantaneous concentration at a distance of 500 meters from the and distance? 1. Time of travel: 500m/6m/sec 83,3 seconds - 1 minute, 23.3 seconds 2, Peak concentration: Q - 4800 jy - .06(500)-92 18.25 3Z - .15(500)-70 - 11.62 2Q (2n) 1 5oy2Oj5 exp 2 _ _2_ x 4800 x_106 1 | 60 n X (15.75)(18.25)zill.62) exp "2 *11.62* X - (157492) exp-13.331 X " 0.256 yg/m3 46 TRINITY CONSULTANTS, INC Weft 01093806 CHAPTER III: REFERENCES 4 1. Slade, op. cit. pp. 117-188. 2. Turner, op. cit. pp. 5-10. 3. "Accuracy of Dispersion Models," Bulletin of the American Meteorological Society. Volume 59, Number 8 (August, 1978) p. 1025. 4. U. S. Environmental Protection Agency, UNAMAP Series of Dispersion Models. Data derived by examination of coded data in program. 5. Adrian D. Busse and Jobn R. Zimmerman, "User's Guide for the Climatological Dispersion Model," U. S. Environmental Protection Agency publication number EPA-R4-73-024, Research Triangle Park, North Carolina, 1973, p. 8. 6. Slade, op. cit. p. 120, p. 173-175. 47 TRINITY CONSULTANTS, INC IV. Initial Cloud Size and Building Wake Effect* A. Accounting for Initial Cloud Size Xa.rely is the source a point Instead a cloud of finite d formed examp cab ine t xay break. The hydrogen and 10 percent arsine. The ventilated gas cabinet has volume of 83 feet Thus a cl cud containing the arsine will have a volume before dilution in the atmosphere of 248 cubic feet cf vhich 16.5 cubic feet will be arsine The initial concentration of arsine is 66,500 pom and 248 cubic feet vould occupy a sphere with a diameter cf 2.38 meters at 68"F. The cloud in already 2.38 meters in the z,y and z direction point standard deviation is calculated by dividing the horizontal extent of the cloud by + .3 and the vertical extent of the cloud by 2.15. The apprrpriate way to adjust the dispersion coefficient for the mitta- clcud size is to vectorial.~ add the standard deviation cf the cloud dimensions to the standard deviation calculated fron the dispersion coefficients. J~ T~L y yo 2Y uy T + azo * A 4f a Subscript for adjusted sigma values Subscript for sigua values at origin In a Gaussian cloud the material is assumed t: be distributed in 48 TRINITY CONSULTANTS, INC VAB.0001093808 the edge of the cloud is assumed to be 10 percent of the central value. Statistically speaking, the cloud is 4.3 standard deviations vide. Within this area 96.48 percent of material is contained. The average concentration across such a cloud is: .9648 (4.3)(.3989) 0.5625 of the value at the center of a tvo dimensional Gaussian curve What really happens is that instead of having a sphere of uniformly mixed gas 2.38 meters in diameter, there is a cloud vith a gaussian distribution of contaminants. At the center of this cloud the concentration is 66,500 ppm. The mathematics to convert the tvo dimension values to three dimensions are complex. The equivalent gaussian sphere vith a diameter standard deviation is about 2.04 times the diameter of a cloud containing uniformly mixed gas. In the example the diameter of the cloud is 4.86 meters. Sigma y is 1.13 meters and sigma z is 2.26 meters. When using computer programs that request a user-supplied dimension of the initial cloud size, it is best to estimate the initial sphere size and then adjust it in the manner described above The degree of accuracy in estimating the initial cloud size can make a significant difference at receptors close to the source, those vithin a fev hundred meters. At greater distances 49 TRINITY CONSULTANTS, INC MV V atmospheric turbulence dominates dispersion and rarely does the initial cloud size have much effect on concentrations at distances beyond one or two kilometers. B. Virtual Distance Method Instead of making detailed calculations of initial cloud size, a computer program can be written which will calculate a virtual distance. The virtual distance will be added to the actual downwind distance for the purpose of determining dispersion coefficients. The virtual distance is the distance a puff would have to travel for atmospheric turbulence to dilute it to a concentration equal to the initial center--of--cloud concentration calculated. Usually a computer program iterates up-vind in 1 or 10 meter increments until the virtual distance is too great then reverses direction and iterates in 0.1 or 1 meter steps to find the correct distance. The initial concentrations are most often known in terms of parts per million (ppm). If a pure escapes the concentration at the center of the cloud is 1,000,000 ppm. But the model is designed to calculate concentrations in grams per cubic meter A calculation must be made involving molecular weight, temperature and pressure to relate ppm to grams per cubic meter. 50 TRINITY CONSULTANTS, INC * 66,500 ppm of arsine (molecular weight * 77.9). If this release were to take place at 77*F and at sea level, the concentration would be: 77.9 X 1013.2 x 66,500 X 298.16 x .0831 211.8 grams per cubic meter Under neutral conditions the virtual distance is calculated to be 29.3 meters. The sigma x and sigma 1.342 meters and the sigma z value is 1.596 meters. C. Conversion of Concentration Units Concentrations are usually expressed in a volume ratio such as ppm or in a weight per unit volume such as micrograms per cubic meter. mm if The equation to convert concentrations is \ X (PPm) m3) x T(K) x R M x P(mb) where: T Absolute temperature (K) R Gas constant (mb m3/gin-mo K) M Molecular weight (gmrmol) P Atmospheric pressure (mb) Standard conditions CFR50 the right of the definitions. 298.16 0.0831 1013.2 X (ppm) .02445 iT" * X (ug/m3) 51 TRINITY CONSULTANTS, INC ,4^0001093811 I Increases in altitude reduce atmospheric pressure and result in increases in concentrations expressed in ppm. The table below summarizes values for various altitudes: Altitude (feet) Atmospheric pressure (mb) Molecular weight where ppm equals micrograms per cubic meter 0 2,000 4,000 6,000 8,000 10,000 D. Obstructions 1013.2 942.1 875.0 812.05 752.45 696.9 .02445 .02630 .02832 .03051 .03293 .03555 P If a cloud or plume is traveling downwind and it encounters an obstruction such as a building the cloud will generally flow around the building. In flowing around the building the cloud grows in size so that it is as large as the building. Other disturbances that can cause the cloud to grow include automobile traffic on a road or a complex open structure such as structural steel supports of process units at a chemical plant. A This phenomenon suggests that as obstructions to wind-driven flow increase, the greater the probability that the cloud will become diluted. In 1977 and 1979, Alan Huber of the U.S. Environmental Protection Agency published the results of extensive wind tunnel investigations. The conclusions of the study were that the wake 1.2 could be divided into three areas: 52 TRINITY CONSULTANTS, INC. * V'Am)001093812 Zone 1 Zone II Zone III 3 3* to 10. 10. The building studied was twice as long as it was high, representing a typical type of structure. The vertical dispersion parameter for stack heights less than the sum of H + 1.5H in Zone II was determined to be: ozl - 0.7Hb + 0.067 (x - 3Hb,) oy - + 0 *067 (x - 3H0) where: ^ m width of building perpendicular to the wind Figure 13 illustrates the growth of the wake. The value for Oy is determined by dividing the wake width by 4.3. The value for a' is determined by dividing the half height by 2.15. For Zone III calculations, an enhanced dispersion parameter can be estimated using a virtual displacement. The plume widths are estimated based on moving the source somewhat further away from its actual location. 53 TRINITY CONSULTANTS, INC Figure 13 GROWTH OF WAKE VAB.0001093814 where: Sy it the virtual source distance such that (7y (10% ) 0.7% 12 4-0.46% . S is the virtual source distance such that ai(10% ) 1.167% . If the building is taller than it is vide, substitute % for % in the calculations of both 0y and az An example vill clarify the calculations: Assume a building 15 meters in height, 50 meters in width, D stability and Pasquil1--Gifford dispersion coefficients. Downwind Distance Multiple of Meters Wake Area Undisturbed Flow 45 3 17.5 10.5 3.9 2.3 75 5 19.5 12.5 6.3 3.6 ' 150 10 24.6 17.6 11.9 6.6 300 328 478 1000 20 67 34.7 36.5 46.2 79.1 21.9 22.8 26.8 39.4 22.6 24.6 34.5 68.1 12.1 13.0 17.6 32.1 55 TRINITY CONSULTANTS, INC. V7SBH001093815 At 150 meters (10 characteristic dimensions) downwind Oy m 24*55 meters which is the same oy as undisturbed flow for a downwind distance of 328 meters* The virtual distance for the calculation is is 178 meters (328 less 150 meters)* In the wake a' for 300 meters downwind is based on the width of undisturbed flow at 478 meters. For 1000 meters it is based on 1178 meters. The a should not be adjusted if the stack height is greater than 1.2Hb according to Huber. At 150 meters <ji is 17*55 me undisturbed flow for a downwind distance of 475 meters The virtual distance is 325 meters* The az for 300 and 1000 meters is determined from the az for 625 and 1325 meters respectively. Huber recommends ignoring the horizontal dispersion parameter enhancement if the stack height ,is greater than 1*2H^ This algorithm for wake effects is included in the following computer models: ISCST, ISCLT, TEM8 and TCM2. 56 TRINITY CONSULTANTS, INC. WrB: CHAPTER IV: REFERENCES 1. Alan H. Huber, "Incorporating Building/Terrain Wake Effects on Stack Effluents", presented at Joint Conference on Applications of Air Pollution Meteorology, November 29 - December 1, 1977, Salt Lake City, Utah. 2. Alan H. Huber, "An Evaluation of Obstacle Wake Effects on Plume Dispersion", presented at American Meteorological Society, Fourth Symposium on Turbulence, Diffusion, and Air Pollution, January 15-18, 1979, Reno, Nevada. 57 a TRINITY CONSULTANTS, INC. -- w YA: V. Effective Stack Heights In order to calculate ground-level concentrations, the effective height of emission must be known* The diffusion experiments described in the previous chapter all oriented the source of tracer material in the horizontal position and emitted material at ambient temperatures* This sidestepped the practical problem associated with industrial stacks of plume rise due to momentum or thermal effects* The simplest way to calculate effective stack height is to add physical stack height to the observed or calculated plume rise: H h + Ah Where: H is effective stack height h is physical stack height Ah is plume rise Some confusion centers on the meaning of plume rise* Ideally it is the elevation above the stack top of the centerline of a plume traveling in a horizontal direction* The only difficulty, according to Briggs, is that in more than 90 percent of the recorded observations the plume had not yet become level when it was no longer visible. Measured plume rise is strongly a function of measuring technique* Flumes dispersing in stable or neutral atmospheres are relatively easy to measure* Those under unstable conditions are nearly impossible to measure accurately* t. 58 TRINITY CONSULTANTS, INC. To overcome this problem Briggs suggests that plume rise be defined as the difference between stack height and the effective stack height one would need in the diffusion equation to correctly h calculate the maximum ground-level concentration.1 Plume rise is both a function of momentum and buoyancy. Terms related to one or both factors are included in all plume rise formulas For cold stacks, those with emissions of less than 5 to 10#C. ambient, momentu: important For hot stacks (those warmer than about 50C) buoyancy, due to the light weight of hot gases, is the most important. Caution should be used on stacks where the emissions include * moisture droplets. As the water in the plume leaving the stack vaporizes, it requires heat of vaporization which quickly cools the diluting stack gases Under conditions of low humidity this can cause the plume to fall to the ground rather than rise. This condition is often visible on cooler days. Over the years more than 100 plume rise formulas have been proposed by over 50 groups of investigators according to Briggs. For the most part, these investigators limited their studies to specific stacks. Many also studied plume rise under a limited range of conditions. Although there has been widespread disagreement within the environmental community regarding the accuracy and appropriateness 59 TRINITY CONSULTANTS, INC. VAS. V. Effective Stack Heights In order to calculate ground-level concentrations, the effective height of emission must be known* The diffusion experiments described in the previous chapter all oriented the source of tracer material in the horizontal position and emitted material at ambient temperatures* This sidestepped the practical problem associated with industrial stacks of plume rise due to momentum or thermal effects* The simplest way to calculate effective stack height is to add physical stack height to the observed or calculated plume rise: H h + Ah Where: H is effective stack height h is physical stack height Ah is plume rise Some confusion centers on the meaning of plume rise. Ideally it is the elevation above the stack top of the centerline of a plume traveling in a horizontal direction. The only difficulty, according to Briggs, is that in more than 90 percent of the recorded observations the plume had not yet become level when it was no longer visible* Measured plume rise is strongly a function of measuring technique* Plumes dispersing in stable or neutral atmospheres are relatively easy to measure* Those under unstable conditions are nearly impossible to measure accurately* 58 TRINITY CONSULTANTS, INC- T of dispersion modeling there has been virtually no challenge to the plume rise formulas developed by Briggs. These formulas are incorporated puff releases A. Briggs' Buoyancy Formula In 1969 Gary A. Briggs, then an employee of the Atomic Energy Commission, made very thorough study of the available plume rise equations Figure 14 is taken from Briggs' vork3and it compares calculated and observed values for selected formulas. Briggs vent on to study plumes, most of them from coal-fired power plants, m much detail than previous investigators. He then proposed his own set of formulas. I* Following a detailed evaluation of Briggs' original work and two subsequent modifications, the Environmental Protection Agency adopted his equations.*^Briggs' equations have been recommended in place of Holland for calculating dispersion following Turner's Workbook of Atmospheric Dispersion Estimates starting * with the sixth edition, published in December, 1972. 60 TRINITY CONSULTANTS, INC. VA&00O1O93821 FIGURE 14 Comparison of Calculated Values with Observations for Neutral Conditions (N OC g VD <0 o o * 9^* O_' ^ . 4* * Ul tn woi o-- iOn n*c oo* oi OO' OOl g g * ** *# 4* 4 ucjr _: <c e 9* -- * _# * <e * ss_Op* 5j o jn c I i* * Ov> m -- --04 # t 3 9^ M ^ O 4**4 44 noOc oni 8 oXr --oi o9I m VI 9 Om * e * *4 Ratio of calculated to observed values of u All aw " Vi V> I n*I OnOn <n6N NS rnd6i 3 O -- ^9 O_ * X_I 044 O* $ S oi o- IQ m .4 3 SK JZ II O O' * * N * -- 4 04 O' do 'tr w-jO' NO r* 04 ess 04 04 -- 04 ^* 04 04 oOCc X r, 4 m-9 4 4*4 m tn mn OC o 04 04 n c - O n ir, ton4 .44M r. rt ___* I *# * d d d d d d 000 -- 9000 nx_ * mr* * S 0--4 * tn * _ Ol T Ol^ O' O' * 4 * O 94 94 Cc <nn O9i * inn 4 iocn od *9 e 9n x n <n ^ ^ 9n 4 _ _ * m oi 4o*4 od ^od <dn w O' n*o X m9 rs d d d * ..* ^mmnCO fiG4 o 9s 9 O' O' O' O' O' Cb 6L CSil :5 < aa o *-- 3 *i1!15J -5 5 5 1& 1iS l1a 5aT5 iCe>fc^r =C ' MB sobu 32 ^ u an *-4 -g 4 1 it i. S JB ^3 2c 5 2 vs 1& -5 S55S5I * o 323 "2 >H & -5--S S^*3 a"mS * 5J SS s* o 2 i< :a Oa ak a 2 i 9V VI 'w -. :3 O rJ a. 61 TRINITY CONSULTANTS, INC BRIGGS1 BUOYANCY PLUME neutral and unstable conditions categories A, B, C and D) istance x downwind Ah 1.6F* 333(x)*667 u For final rise Ah - -21- u425F--*-7--5- Ah 38.710F-6 u F < 55 F > 55 Final plume rise is achieved when the downwind distance x equals 3.5x*. For final plume rise under stable conditions (stability categories G and F) F 333 Ah 2.6 (--us ) Where F T IT (1 " T ) x* iAp625 where F < 55 X* 34F*4 where F > 55 & (i) T k6z' 60/6z Vertical potential temperature gradient in the atmosphere E category F category 02 K/m (stable conditions) 035K/m (stable conditions) F buoyancy flux (m4/sec3) Ah plume rise above stack top (m) u wind speed at stack level (m/sec) horizontal downwind distance (m) x* horizontal distance from the stack at which atmospheric turbulence begins to dominate entrainment 3.5x* m distance to point of final rise for unstable conditions (m) g gravitational acceleration *9.8 m/sec2 T ambient air temperature " 293K (usually) * stack gas temperature (K) Vf stack gas volume flow (m3/sec) Revised 7/85 62 TRINITY CONSULTANTS, INC, In some lectures Gary A. Briggs has commented on the shortcomings of his videly used formula for plume rise* 1* Buoyancy Flux The Briggs* formula assumes that the stack gases have a molecularveight similar to that of air. For fuel combustion sources this assumption is accurate within five percent. The products of natural gas combustion have a molecular veight of about 27.5 which is slightly lighter * than air because of thewater vapor formed from the combustion of hydrogen. The products of coal burning have a molecular weight of about 30, which is slightly heavier than air because of the large amount of carbon dioxide. As a practical matter, nitrogennearly always dominates the composition of stack gases so that molecularweights significantly different from air are rare. On the other hand, an incinerator burning hydrogen sulfide emitting chlorine compounds have the same weight as air and some adjustment may be appropriate. The term (1 - T/T ) reflects the buoyancy of the heated 9 gases. It is this term in the buoyancy flux, F, that can be modified to account for differences in the molecular weight of the stack gases. 63 TRINITY CONSULTANTS, INC. VAB.Cf / A F (i _ "mr--\ * 28.9TS' where wm molecular weight of stack gases When computer models which don't allow entry of molecular weight, it is often easier to adjust the stack + temperature for the molecular weight difference. Trinity Consultants recommends that this adjustment should only be attempted if the use of routine plume rise formulas produces results which are quite different than observations. 2 Wind Speed The wind speed in the various formulas should be the centerline of the plume as it rises. Some investigators program speed for the height of the stack top plume rise, the wind speed was r incremental final plume rise was determined. It turned out that if one made an appropriate adjustment for the wind speed at stack top. then it wasn't sary to make the incremental adjustments. The CSH, RAM, TEM, TCM and CRSTER programs make adjustments for higher average wind speed at the top of the stack anemometer PTMAX. PTMTP VALLEY programs do not make wind speed adjustment, but this may 64 ----- TRINITY CONSULTANTS, INC_____________ VSBXOT1093825 may not be a flav depending on hov these programs are used. w If the programs are being used to calibrate a model then it is likely that correction for the higher speed winds aloft than those measured at the surface is appropriate. If the program is being used to forecast worst case* then assuming a uniform vertical wind field may be better. 3 Restoring Acceleration In the plume rise equation for stable air the "potential lapse rate" represented by the term <56/6z is used. This is assigned a somewhat arbitrary value by EPA in their models. Briggs suggests that when evaluating a specific site the restoring acceleration value should be the difference between the adiabatic lapse rate (--0.01C/meter) and the actual lapse rate from the top of the stack to the plume centerline not the lapse rate close to the ground. In other words: 56/6* AT/Ah + 0.01 Where: AT is the air temperature difference between the plume centerline and the top of the stack. Ah is the plume rise in meters. f In all EPA models z is assumed to be 0.02 and 0.035C/m for E- and F-stabilities respectively. These values are typical TRINITY CONSULTANTS, INC values in the lowest 50 meters of the atmosphere. At higher elevations it may be more appropriate to use lower values because the lapse rate will tend to become more adiabatic. For tall stacks on a power plant, a value of 0.01C/meter is probably more appropriate. 4. Size of Plants The Briggs formulas have generally been validated for plants C with an approximate fuel consumption greater than 200 X 10 BTU per hour or roughly 34 cubic meters per second of stack gases at about 300F (422K) assuming fuel oil combustion and 30 percent excess air. The use of Briggs formulas for smaller stacks is often done, but there is an absence of validation on these smaller stacks. Among other things, it appears that the coefficient for the stable plume rise is less (about 2.4) for smaller stack and greater (up to 3.1) for larger stacks. B. Flume Rise of Flares Flares are incinerators that burn waste gases in the open atmosphere. Typically, a flare is a vertical stack through which waste gas, and sometimes fuel gas, is emitted to the . atmosphere. At the top of the stack the mixture burns in the atmosphere. The flare tip is often equipped with an automatic device to keep the flare lit* It is also often equipped with a steam line. The steam acts to make the flare "smokeless." 66 TRINITY CONSULTANTS, INC. vab:o Most flares at industrial facilities are used for the emergency p release of process gases during upsets. Thus emissions from flares are rarely included in emission inventories and are rarely modeled, except fcr the annual rate of emissions. An exception is the natural gas processing industry which uses a large number of continuous flares for disposing of acid gases (hydrogen sulfide and carbon dioxide) from the amine plants used to "sweeten" the gas. Flares tend to be very efficient in converting hydrocarbons to products of combustion. JL study was performed by Engineering Science, Inc. in 1983 and jointly sponsored by the Chemical Manufacturers Association and the United States Environmental 7 Protection Agency. This study reports that "when flares are operated under conditions which are representative cf industrial practices, excluding emergency releases, rhe combustion efficiencies in a flare plume are greater than 98Z." The Briggs' buoyancy plrme rise formulas can be easily adapted to forecast the plume rist fron flares. These formulas require parameters that are ccmncnlv available such as the stack temperature and the vo linns trie flow rate in the stack. From these values the user calculates buoyancy flux, F, which is heat manual calculations are being made, F can be calculated knowing the volume and heat content of the gases heir? flared. But if a computer is being used, it is often easier to first calculate F, assume a stack temperature and calculate synthetic volumetric ~4 4 TRINITY CONSULTANTS, INC. flow rate This latter method permits one to use all existing EPA computer programs to analyze flares 1. Calculating F from Heat Release Briggs states the following equivalencies in Equationas 4.19c and 4*20* A (1) where: F - buoyancy flux parameter (m4/sec3) g - gravitational constant (9*8 m/sec2) v stack velocity (m/sec) r stack radius (m) p - density of air (1205i/m3) ps density of stack gases Qg * heat release (low heat value) (calories/sec) CL -specific heat of air (0.24 calories/g K) T " ambient air temperature (usually 68*F - 20 C * 293 K) Tg stack gas temperature ( A) V - volume of stack gases at standard conditions (m3) Vf - volume of stack gases at stack conditions The equation on page 57 of this manual is: (2) The equality between equations (1) and (2) can be demonstrated Thus, (3) The heat release is the product of the volume of gases, the specific heat per unit volume and the temperature change. The specific heat of gases is given in units per weight so 68 TRINITY CONSULTANTS* INC. one must multiply this by the density to get specific heat per unit volume. A value for V can be calculated and substituted in equation (3). /""N VC-3 (Ts - T) substituting stack conditions: V QH . V T rewriting to get an equations for Vf : e substituting this value for Vf in equations (3) F . 80S f la I fx. - T ] . 8QH rCj.;T { -s - ~J [ Xs J CpPT The usual problem is to intermix flare stacks with conventional stacks. In the usual form of Briggs' plume a rise equation, best release is calculated from stack temperature and the volaetric flow rate of the stack* For a flare, heat release is known, but in order to intermix flares with conventional stacks, a stack temperature is assumed and an equivalent volumetric flow rate determined* 69 TRINITY CONSULTANTS, INC 01093830 Trinity Consultants usually makes the following assumptions and then substitutes in equation (6). 4 T - 68*F - 20C - 293 K Cp * 0*24 cal/gramK p 1203 gram/m3 Ts - 1000*K QH 0.24(1205X293) f* 1000 1000 - 293 ; 16.7 X 10"5Qh Although the products of combustion usually have a higher specific heat than air and are heated first* these products become rapidly diluted with ambient air. Hence the specific heat of air should be used for calculating plume rise. - At higher altitudes the density of air decreases, as does the density of the plume. Although this increases the absolute plume buoyancy, the buoyancy relative to ambient air remains unchanged. Altitude has no effect on plume 2. Losses Due to Radiation combustion products of combustion. A small portion is radiated. The visible and ultraviolet emissions rarely exceed 0.4 percent of the heat of combustion. emissions and often range from 2 to 20 percent The energy lost 70 TRINITY CONSULTANTS, INC mmmmm through infrared radiation is a function of the surface area and the fourth power of the absolute temperature of the hot gas envelope. If the flame is burning smoothly, and turbulence is at a minimum, then a higher radiation loss will occur. As turbulence increases, due to either the nature of the gas discharge jet or wind, the radiation loss * decreases. This it a result of a higher rate of dilution and a smaller hot gas envelope. Judgment should be used to determine the amount of radiated heat. In order not to underestimate radiation and therefore overstate plume rise. Trinity Consultants assumes a 20 percent loss. This neans that 80 percent of the heat of combustion is used to heat the products of combustion. I Effect of Addition cf Steam Steam is often used to make a flare "smokeles s " High pressure steam is throttled through nozzles into the area of combustion. If the nozzle were perfect, then the flow would be isentropic (constint entropy). Most nozzles have an efficiency of between 87 and 92 percent. Trinity Consultants assumes that 90 percent of the enthalpy loss at isentropic (constant entropy) conditions occurs and i. from this calculates the enthalpy at the nozzle outlet. This is compared to the enthalpy of water vapor at standard conditions and the difference subtracted (or added) to the 71 ------ TRINITY CONSULTANTS, INC. heat of combustion. This can be illustrated vith schematic Hollier chart. a A In the exai shown in Figure 15, the steam and Its initial enthalpy is 1279 BTU per pound. If the nozzle were perfect the would and the final enthalpy would be 1117 BTU per pound. The discharge steam would contain 3.5 percent water vapor Because of the inefficiency of the nozzle only 90 percent of the enthalpy me somewhat The discharge stream contains 1.8 percent vater. Since 970 BTU*s are required to convert each pound of water to steam. * 17 BTU (970 times .018) must steam by the combustion of the flare to vaporize the water formed. The heat content in fuels is described by two numbers, the high heat value and the low heat value. The difference between the two is that the high heat value includes the heat of vaporization. Low heat is the high heat value less the heat required to vaporize water formed during combustion. Between the point of formation of water vapor to ultimate plume rise of a flare, water is rarely condensed. Therefore, as a matter of being conservative, the use of the low heat value is recommended. 72 TRINITY CONSULTANTS, INC. 093833 FIGURE 15 ENTHALPY 1279 1132.8 1116.5 ENTROPY, $ 73 THINITY CONSULTANTS P.O. BOX 31481*DALLAS, TEXAS 75231 / VAB.0001093834 m PROBLEM E: A An acid gas stream of the folloving composition is being sent to a flare. Ho fuel gas is being used: Methane (CHi*) Ethane (C2Hg) Propane (CgHg) Other (C4+ ) Hydrogen Sulfide (H2S) Carbon Dioxide (C02) Nitrogen (N2) X by volume 1.97 .55 .41 .68 43.40 52.84 .15 100.00 The measured flow rate is 452,000 cubic feet per day measured at 60F at 14.65 pounds per square inch No steam or fuel gas is being used. The first form is used to correct gas flows from measured conditions (which vary widely) to standard conditions. The second form calculates the heat release (Qh) and the equivalent volumetr an assumed stack temperature of 1000K. Calculate the equivalent volumetric flow rate assuming an equivalent stack gas temperature of 1000K. 74 TRINITY CONSULTANTS, INC VA&0OO1O93835 CALCULATION OF VOLUME WASTE GAS FLOW RATE ,3139 103 CF/MIN. AT. STD. CONDITIONS 60 F 14.65 psia FUEL GAS FLOW RATE103 CF/MIN. AT STD. CONDITIONS *Fpsia COMPONENT CORRECTED FLOW RATE TO 68F - 20C - 293K, 14.7 psia WASTE'GAS FUEL GAS mol% 103 CFM mol% 103 CFM TOTAL 100.00 318 100.00 TO CORRECT FUEL GAS FLOW RATE: RATE AT 60-F, 14.65 psia gg * g x - 1.012 4 page 1 of 2 75 VAB.0001093836 CALCULATION OF HEAT RELEASE 4 * TOTALS HEAT RELEASE FROM COMBUSTION .093 106BTU/MIN PORTION OF HEAT USED TO HEAT PRODUCTS OF COMBUSTION .80 (Usually .80 or greater) NET HEAT RELEASE (QH,,)----.-0--7--4--4------ 10&BTU/MIN x 60 252 Calories 1 BTU 60 Seconds 1 Minute .312 ]106CAL/SEI Using an assumed stack temperature of 1000K (1340F) .6 Vf - 16.7 x 10 Q 76 page 2 of 2 VAB.0001093837 C. Briggs' Momentum Formulas Since 1967 there has been considerable research done on the plumes from sources where momentum, not buoyancy, is the principal source of rise* Briggs proposed these formulas in 1971 and they are used in most of the newer models* In these models, the plume rises are calculated by adding the buoyant rise to the momentum rise* The greater of the two values is then used for further calculations* The formulas used are as follows: Unstable: Ah - 1.89 v2d u(v + 3u) 667 x. 333 * Stable: Ah (max) vd u Ah(max) - .945(vd)'667u"*333s"'167 Where: x downwind distance (m) * stack exit velocity (m/sec) u wind speed (m/sec) d stack diamter (m) & li * " T 9z g gravitational acceleration (9*8) m/sec2 T - ambient air temperature (293K usually) 90/3 a " vertical temperature gradient in the atmosphere* Both EPA and Texas assume: stability category F--stability category 02C/m 035C/ ft 77 TRINITY CONSULTANTS, INC. * VAB. As a practical natter final plume rise with unstable conditions is reached rather rapidly so the use of the final plume rise formula rarely results in an error. It is questionable whether the gases from short vents on buildings enter a stable atmosphere. The atmosphere in the immediate vicinity of buildings, especially in industrial areas is more likely to be neutral than stable. 78 TRINITY CONSULTANTS, INC. CHAPTER V: REFERENCES 1* Gary A. Briggs, "Plume Rise Predictions," Chapter 3 in Lectures on Air Pollution and Environmental Impact State ments, American Meteorological Society, Boston, 1975. pp* 59-111* 2* Turner, op* cit* p. 31* 3* Briggs, Plume Rise, op, cit* p* 45* 4* Gary A* Briggs, "Some Analyses of Plu vations," Proceedings Second International Clean Congress* Academic Press, New York, 1971* pp* 1029-1032 5* Gary A* Briggs, "Discussion on Chimney Plumes in Neutral and Stable Surrounding," Atmospheric Enviro^*"1*?*^ 6 (July 1972). pp. 507-510" ~~ 6* Gary A. Briggs, a taped lecture contained in "Effective Stack Height/Plume Rise," U*S* Environmental Protection Agency, 1974* (Available as Course No* SI 406 from National Audiovisual Center, Order Dept* (GSA), Washington, D.C* 20409)* 7 Chemical Manufacturers Association, "A Report on a Flare Efficiency Study" March, 1983* 79 TRINITY CONSULTANTS, INC* Chronic toxicity refers to long term effects on the human body. Chronic effects are usually estimated using annual average models. Acute toxicity refers to short term effects on the human body. Time spans ranging from a fev seconds to 30 minutes are generally of interest when studying acute effects. Section 112 of the Clean Air Act requires EPA to develop regulations for hazardous air pollutants. air pollutant means The term hazardous Man air pollutant to which no ambient air quality standard is applicable and which in the judgment of the Administrator causes, or contributes to, air pollution which may reasonably be anticipated to result in a increase in mortality or an increase in serious irreversible, or incapacitating reversible, illness." Under this section EPA has generally limited its studies to the continuous releases of chronic pollutants such as asbestos, vinyl chloride, benzene, acrylonitrite and similar compounds. The EPA has not employed probability estimates for episodic releases of such pollutants. A human can be exposed to a rather large concentration of some of these but if the duration is quite brief the long terms effects will be rather small. Vinyl chloride is a good example of such an air contaminant. 80 ------------ TRINITY CONSULTANTS, INC:------------------------^ar On the other hand some compounds are dangerous in high 9 concentrations for brief periods of time but relatively harmless in lover concentrations for extended periods. Hydrogen sulfide is generally fatal if concentrations exceed 1000 ppm for 5 minutes but the workplace standard allows values of 10 ppm for an H-hour work day. Because each chemical compound has different short and long term effects, it is suggested that a toxicologist be consulted to establish safe acute toxicity levels for exposure. The appendix contains a sample report prepared for arsine. % B. Air Contaminant Limits in the Work Place The most comprehensive set of suggestions is published annually by the American Conference of Governmental Industrial Hygienists (ACGIH).1 The 1968 version of this publication forms the basis for the Occupational Safety and Health Administration (OSHA) rules affecting air contaminants 29CF&1910.93.2 It also is used by various state agencies. One example is "Airborne Contaminants" published by the State of California, Department of Industrial Relations (GAL/OSHA). The ACGIH publication contains four columns of data for each substance. The time weighted average (TWA) and The Short Term Exposure Limit (STEL) are shown in terms of ppm and milligrams per cubic meter. 81 TRINITY CONSULTANTS, INC. The TWA is defined as follows: "The time-weighted average concentration for a normal 8-hour work day and a 40-hour work week, to which nearly all workers may be repeatedly exposed, day after day, without adverse effect." The STEL is defined as follows: "a 15-minute time-weighted average exposure which should not be exceeded at any time during the work day even if the eight-hour time weighted average is within the TLV. Exposures should not be longer than 15 minutes and should be repeated more than four times per day. There should be at least 60 minutes between successive exposures to the STEL. (It is a) concentration to which workers can be exposed continually for a short period of time without suffering from: 1) irritation, 2) chronic or irreversible tissue change or 3) narcosis of sufficient degree to increase the likelihood of accidental injury, impair self-rescue or materially reduce work efficiency." For the great majority of substances with a TLV, there is not enough toxicological data available to warrant a STEL. The ACG1E recommends that short term exposures should exceed 3 times the TLV-TWA for no more than 30 minutes during the work day and under no circumstance should they exceed five times the TLV provided the TLV-TWA is not exceeded. Thus this most widely used publication is directed towards the work place environment and provides limited aid in assessing safe levels for a one-time intensive exposure to a toxic gas. The U.S. Government has two organizations involved in worker safety. Under the Department of Labor, OSHA has general responsibility for developing and enforcing regulations. Under the Department of Health and Human Services, the National Institute for Occupational Safety . and Health (NIOSH) is 32 ---------- TRINITY CONSULTANTS, INC. s* responsible for research to develop the technical basis for standards. These organizations jointly published a guide that * defines acute levels of toxicity.3 It is entitled, "NIOSH/OSHA p Pocket Guide to Chemical Hazards" This is probably the most useful publication to establish safe one-time short-term exposure levels for assessing the hazard caused by a toxic gas cloud. One concept that is commonly used by toxicologists is ppm/min. For example, chlorine meaning person can withstand 1000 ppm for one minute, 200 ppm for five minutes, or any other combination of concentration and time in minutes is 1000. It is improper to apply this technique to the TLV-TWA values without professional advice because the physiological effects of * substances differ so widely. Two other publications provide a rich source of information to help establish tolerable levels of contaminants. N. Irving Sax is the author of "Dangerous Properties of Industrial Materials".4 "Patty's Industrial Hygiene and Toxicology"5is a publication consisting of five volumes. a C. Air Contaminant Limits in Ambient Air Starting with Montreal in 1978 numerous governments in North America j- of toxic compounds from industrial plants in the ambient air. According to a recent report, 14 states and 6 local progra II have toxics regulatory programs in place C An even larger number have programs in preparation. Many states and localities use some form of ambient guideline or standard for the control of toxic air pollutants. Most of these use "factored" occupational values as a basis for ambient limit, at least for some pollutants. A factored occupational value is the use of a constant fractional value to apply to all of a specific set of occupational limits to convert from a workplace guideline (based on exposure to a particular contaminant over an eight-hour day, five days a week) to an ambient guideline. The occupational limits used most commonly for this purpose are the TLV--TWA, the OSHA limits and the N10SH recommended criteria for occupational exposures in air. KIOSH recommendations are based primarily on medical science while OSHA considers technical feasibility and economic factors in its role as regulator. Figure 16 is a summary of the limits adopted or proposed by selected state and local air pollution control programs.^ D. Time Averaged Concentrations As was discussed in Chapter III, the time average concentration 84 ----------- TRINITY CONSULTANTS, INC_________________093845 4 Figure 16 SAFETY FACTORS USED TO DERIVE ACCEPTABLE AMBIENT CONCENTRATIONS FROM OCCUPATIONAL LIMITS State or Locality Safety Factor Applied to Occupational Limit Averaging Time Alabama Arkansas Connecticut1 Georgia1 Illinois Indiana1 Michigan \* Minnesota Mississippi Montana Nevada New Hampshire1 New York Rhode Island1 South Carolina Texas 2.5% (1/40) 1% (1/100) 0.5% (1/200)* 1% (1/100). or 2% (1/50). depending on pollutant group 0.33% (1/300) if known human carcinogen. 1% (1/100) if not known human carcinogen 0.33% (1/300) for non carcinogens 1% (1/100) * 1% (1/100) for selected pollutants 1% (1/100) 3.3% (1/30). usually 2.4% (1/42) 10% (1/10) 1% (1/100) 0.33% (1/300). 2% (1/50) depending on toxicity category 1% (1/100) 0.24% (1/420) 1% (1/100). 0.1% (1/1000) 1 hour 24 hour 8 hour 24 hour 24 hour 24 hour 8 hour 8 hour NA1 e- 1 year* 8 hour NA1 1 year * 24 hour NA* 30 minute 1 year * * (Continued) A 85 VAB.0001093846 pigure 16 (cont'd) a State cr Locality Safety Faetor Applied to Occupational Limit Averaging Time 0.24% (1/420) Tisconii1 s ECAG.HI. California Fiilacelphia, Pennsylvania 1% (1/100) for carcino gens 1.7% (1/60) for non carcinogens 2.4% (1/42) 2.4% (1/42) 2% (1/50) 0.33% (1/300) 100% for selected pol- lutants 0.24% (1/420) or 2.4% (1/42) 24 hour or 1 year depending on pol lutant 24 liour 24 hour NA* 1 year, 24 hour. 1 hour 8 hour 1 year Teutitive: program in preparation. 5or trailable at the time of this vriting. reported in Radian Corporation. "Survey of State and Local Agency Programs :cr Control of Toxic Air Pollutants." Draft Report. Prepared for TT.S. EPA, Ifi i:e of Air Quality Planning and Standards. State and Territorial Air PolIntirn Program Administators, and Association of Local Air Pollution Control ! f i i: it 1 s, June 8. 1983. 86 VAB.0001093847 is determined by counting the number of standard deviations of a cloud that pass a certain point. If an observer is located close to a brief (fetr-second release), then an observer may only be breathing the toxic gas for a few seconds. The rest of the air breathed over, say, five minutes will te fresh air. On the other hand if the observer is several kilometers away the peak instantaneous concentration would be nearly equal to the 30-second average concentration. The science of establishing safe acute levels for 30-second, 1-minute or even 5-cinute periods is not veil developed. Therefore, when analyzing possible accidents it may be best to analyze several averaging times. Most people spend most of their time indoors There significant buffering effect in air movement into a building. Under ideal conditions the occupants cf a building could be varned When the venti teased to the maximum extent possible to flush out any toxic gases that might have permeated the building. Method Used by EPA for Chronic Toxicity Studies. For years EPA has studied the risk of citizens living near chemical plants. These studies are based on the use of the CUM computer model and meteorological data collected at nearby 87 TRINITY CONSULTANTS, INC 4 v4 airport8. There is some question regarding the effectiveness of this approach. First CDM is an urban model and cany plants are located in rural areas. Nearby airport meteorclogical data may not be representative of conditions near the plant, particularly in mountainous areas. The CDM model does not consider the wake effects of individual structures, rather it adjusts the vertical dispersion coefficient if the release height is less than 50 meters. 38 TRINITY CONSULTANTS, INC VAB.0001093849 4 CHAPTER VI: 1EFERENCES 1. American Conference of Governmental Industrial Hygienists, "TLVa-ThreehoId Limit Values for Chemical Substances and Physical Agents in the Work Environment and Biological Exposure Indicies with Intencsd Changes for 1984-85"* Available from ACGIH, 6500 Glenvay Avenue, Building D-7, Cincinnati, Ohio 45211 (513)651-7881 $4*00* 2* Office of Technology Assessment, Preventing Illness and Injury in the Workplace". April, 1985. (as quoted in Chemical and Engineering News, April 14, 1985 p*14*) 3. NIOSH/OSHA Pocket Guide to Chemical Hazards. Stock Number 017-033-00342-4, Superintendent of Documents, U.S. Govern ment Printing Office, Washington, DC 20402, pp* 191. $7.50. 4. N. Irving Sax, Dangerous ISBN Number 0-82^7-7250-4, ACGIH, Publications Section, 6500 Glenvay Avenue, Building D-7, Cincinnati, GB 45211. 5. American Conference of Governmental Industrial Hygienists, Numbers 0-471-16046-5, 0-471-16042-3, 0-471-07943-X, 0-47109258-2, 0-471-02698-0. ACGIZ, Publications Section, 6500 Glenvay Avenue, Building D-7, Cincinnati, OH 45211. 6. U.S. Environmental Protection Agency, Office of Air Quality Planning and Standards, Air !:xics Information Clearinghouse, Second Interim Report of Selected Information on State and Local Agency Air Toxics Activities March 1985. p.14. EPA No. 68-02-3889, WA15. Project Officer: Karen 1. Blanchard, 919/541-2350. 7. ibid, p28 * 85 TRINITY CONSULTANTS, INC / 4AB4jeeTO93850 \ A review of the TLV-TWA list shows values ranging from less than 1 :nn ~p to 5000 ppm. Some as acetylene, helium - -- J thane act as simple asphyxiants. recommended -he suggested minimum oxygen content is 18 percent by volume.1 Some zz these asphyxiants are explosive and care should be exercized to ep concentrations below the lower explosive limit. If oxygen is 1 volume '143,000 ppm). OSHA sets a limit of 19.5 percent oxygen in ZFU :c)o. (d)(9)(vi) and 16.5 percent oxygen in 29CRF1915 k Torsion Dilute Clouds ^ince the concentrations of primary concern for most gases is in :he range of less than 1 ppm up to 5000 ppm, this means that the :lcud contains no less than 99.5 percent air. As such, the rolecular weight of the contaminant, or its original temperature, have virtually no effect on dispersion and can be w ignored. More complex processes may exist near or at the source, but by the time the gas has been diluted to loncentrations of interest, the cloud will be nearly all ambient air. Moreover, the rate of dilution of the cloud will be trimarily governed by the prevalent atmospheric turbulence. 90 TRINITY CONSULTANTS, INC. Whenever there is an accidental spill o a liquid or gas, some or all of the material volatizes* As the cloud of volatile material and air moves gradually downwind, the natural process of atmospheric turbulence reduces the concentrations* If the spill is of a hazardous material, the concentrations at some point downwind will fall below the toxic level. Regardless of the nature of the spill, atmospheric turbulence is generally the major factor in diluting the plume as it moves downwind* The initial turbulence of the actual release generally has only a minor effect on concentrations at distances beyond 250 meters or so from the spill* There are three types of spills: liquids, gases stored as liquids, and gases* In nearly all cases dense gas clouds are created. Buoyant clouds are created only when there is a small hole in a container of gas or when there is evaporation from a liquid pool on the ground. Buoyant plumes are also created when there is a fire. A more detailed description of the three types of spills follows: 1* Liquid spills* The spill of a material which is normally a liquid at 91 TRINITY CONSULTANTS, INC atmospheric pressure sad temperature causes a pool to form* Examples of such liquids include benzene, acrylonitrile, and vinyl chloride* The liquid will evaporate from the pool at a rate that can be calculated based on the vapor pressure of the liquid which governs the rate of liquid to gas transfer, the area of the pool, the heat of evaporation, the air temperature, the ground temperature and the heat transfer of convection and radiation* The viscosity of the liquid will determine the rate of growth of the pool on flat ground. If the material is spilled into a ditch, both the surface exposed to the atmosphere and the surface exposed to the warm earth will be reduced, thus cutting the evaporation k rate. In fact one suggestion for minimizing the emissions from spills is to build concrete basins under the potentially leaking vessel. A small deep basin will result in minimum evaporation* By putting a sump in the basin, the spilled material can be quickly recovered. For most liquids the initial rate of emiss greater per unit area than the equilibria As evaporation takes place, the pool will be cooled, reducing temperature evaporating. Wu and Schroy have provided a good summary of the thermodynamics and heat transfer associated with liquid spills2 92 TRINITY CONSULTANTS, INC. VKB If the spill of a liquid occurs on water, then the release rate of the material will be much greater than if the spill occurs on land. On land there is no circulaticn onl conduction, a much less efficient means of heat transfer. The rate of release of toxic material decreases as the temperature of the underlying surface decreases. If the pool is floating on water, then circulation patterns in the water will help keep the pool relatively warm. The Chlorine Institute suggests that chlorine spilled on water should be assumed to vaporize.3 2. Liquid Gas Spills. Many materials are stored in pressurised or refrigerate'i containers. These include ammonia, chlorine and llquifiei natural gas (LNG) and liquified petroleum gas (LPG; nature of the failure has much to do with how the release disperses. a. Small Hole in Vapor Space puncture the container where liquids do not escape, the material will enter the atmosphere as a gas. If the release rate is slcv and if \ 93 TRINITY CONSULTANTS, INC VAB.UOD1093854 the gas has a molecular weight less then Air, the releese will hAve buoyant plume rise*4 If the moleculAr weight is greeter than air, the plume will rise due to omentun and then sink because of density differences. b. Large Bole in Vapor Space If a large hole should suddenly exist in a tank containing liquified ammonia under pressure, the consequences are quite different than those associated with a small hole. If the hole is t vapor can be replenished by evaporation from the liquid surface above which the pressure changes little if at all. If the hole is large, the pressure abo^e the surface is relieved instantaneously. Pressure at and below the liquid surface (which is the of atmospheric pressure and static head) is less than the saturation vapor pressure. As a result, bulk boiling occurs and most of the contents of the vessel vill be flung into the air. For ammonia heat will contents vaporize remaining vessel cloud of finely divided boiling liquid droplets at a temperature of -33C. Experiments confirm rapid depressurization occurs, the entire contents of 94 TRINITY CONSULTANTS, INC. 4 VSB the container becomes airborne* e* Hole in Liquid Space* If toe puncture or release occurs belov the liquid level, then liquid vill enter the atmosphere. If the contents are stored at atmospheric pressure the liquid vill form a pool and as it evaporates gas will enter the atmosphere* One conclusion that can be drawn from this observation is that it is safer to store liquified gases refrigerated at atmospheric pressure than in pressurized containers* If the contents are pressurized, then a portion of the liquid vill immediately flash to a gas while the liquid portion is rapidly cooled. d* Dense Gas Cloud. Because of the turbulence induced by the flashing of gas most of the liquids do not form a pool on the ground but rather form an aerosal of liquid droplets. This cloud, competed of suspended boiling droplets, is called a "dense gas cloud". A dense gas cloud is also formed when there is a catastrophic failure of an ammonia or chlorine tank. t f f p i i \ + \ p i 1 95 TRINITY CONSULTANTS, INC. cloud vaporize, the cloud becomes neutrally buoyant and the usual Gaussian dispersion equation apply* The location, dimensions and concentrations of gases in a dense gas cloud are analyzed using differential equations that are totally different than the familiar Gaussian equations* i A set of six partial differential equations has been proposed to analyze the characteristics of a dense gas c1oud5including: Equation Width Lateral Momentum Mass Conservation Mass Fraction Conservation Longitudinal Momentum Enthalpy Conservation Variables Horizontal velocity, gravity spread velocity and entrainment velocity* Hydrostatic force and surface drag. Entrainment velocities. Boil off from surface pool is added to local flux valves. Entrainment of ambient momentum (wind speed), acceleration from hydrostatic gradients, and surface drag. Surface heat transfer, entrainment of water vapor, ground ource of boiling cryogenic liquid and longitudinal dispersion* i 96 TRINITY CONSULTANTS, INC k * ,1 m e. Descriptions of Releases In the case of a sudden release, such as a tank rupture, the dispersion process can be described as four phases according to Griffiths and KaiserFirst, there is the turbulence, called "flash off", caused by the rapid escape of the liquid or gas. For a 20-ton ammonia tank rupture, tests suggest that about 20 percent becomes vapor while 80 percent remains as a liquid aerosol. A similar fraction of chlorine will flash at an ambient temperature of 85 F according to the Chlorine Institute. The liquid aerosol appears to observers as a cloud in mm the shape of a column or vertical cylinder. The gases within this cylinder are quite cold due to the evaporation of part of the gas. Second, this cylirder starts to slump, much in the way a column of water starts to spread out. During slumping, air is entrained fairly slowly and this stage will typically last 30 to 40 seconds for a 20-ton gas spill. Third, the cloud of liquid droplets now enters the ground-hugging phase in which the entrainment of air takes place at a rate less than that expected for a passively diffuse plume. The area of the top surface is X I. 97 TRINITY CONSULTANTS, INC. much greater than the area of the sides and, therefore, most of the entrainment of air takes place through the top surface* Depending on the ambient temperature, the gases in the cloud will reach ambient air density in 3 to 5 minutes after slumping starts from a 20-ton spill* Fourth, the natural process of atmospheric turbulence takes over and the cloud diffuses like any other gas in the atmosphere* The boundaries between the phases are rather blurred and indistinct* The description of the four phases, however, is useful when discussing the atmospheric dispersion of dense gases* In the case of large volume releases, the dense cloud can remain intact for some distance* For example, the cloud of vapor formed from the release of 40 tons of ammonia at Pensacola, Florida, vas tracked on a radar for an hour out to a distance of nine miles before it dissipated into a neutrally buoyant phase. On May 11, 1976, in Houston, an ammonia truck crashed from the elevated structure of the Southwest Freeway 1-610 interchange. The grass vas "burned" in a circle with a radius of about 150 meters from the point of impact and in the downwind distance out to a distanc about 1000 The "burned" grass apparently reflects the initial slumping column followed by a ground-hugging dense gas cloud of liquid droplets that m eventually warmed to become a gas. f. Shape and Characteristics of Dense Gas Clouds Slumping of a dense gas cloud takes place rapidly and it causes the cloud to spread out radially including * movement upwind until arrested by the wind. A raised formed with the slumped cloud summing a doughnut-like shape and eventually decaying to pancake and movement cloud is nearly independent of atmospheric stability. A dense gas cloud moves more slowly than a buoyant cloud because of surface drag Tests in the Burro series reported by Meroney show that with a wind speed of 2m/sec the center of the cloud moved at about a third the wind speed. The cloud dimensions for a 10 ton spill of LNG were approximately 200 meters wide and 6 meters deep at a location 140 meters downwind, 200 seconds after the release. 99 TRINITY CONSULTANTS, INC u~\ /""N 4 i s \ In i \ I I Griffiths end Kaiser repcrt that a 20 ton ammonia spill forms a cloud up to 4C1 deters in diameter after 50 seconds and up to 600 meters in diameter after 100 seconds * Another characteristic of a dense gas cloud is that as the cylindrical cloud sltmps, concentrations occur upvind of the center of the release. In the case of Burro, they occurred up to 15 meters upwind. In Houston they extended about 150 meters upwind. The effects of gravity on a dense gas cloud are strong. In an effort to restrict the number and type of * variables that require consideration, the significant dense gas tests have been conducted on flat, open uniform terrain. These induce Porton Down, Map 1 in Sands, China Lake (Burrc) and the recent Thorney Island experiments It is known qualitatively that cense gas clouds do not move uphill except with ruderate strong winds and they may even roll down a hill trains; slight winds. Further research is necessary tc qualify the effects of topography. 100 V TRINITY CONSULTANTS, INC -I I A There has been extensive research conducted on dense gas spills mostly involving liquified petroleum gas. The studies generally are directed at determining the lover flammable limit (LFL) of a gas/air mixture. Depending on the gas, the LFL are in the range of 10,000 to 125,000 ppm, far in excess of a safe level for gases such as chlorine or ammonia. The dissipation of the dense gas cloud into a neutrally buoyant cloud and the dilution of the buoyant cloud down to levels of 100 to 500 ppm has not been studied. Various assumptions are made by scientists and a more accurate solution to this issue may not occur for some time. Modeling Dense Gas Clouds. Although many scientists believe that adequate data exists to validate dense gas models, most are avaiting the availability of data from the China Lake and Thorney Island experiments for confirmation. At the point of transition to a neutrally buoyant cloud, the dense gas cloud may be up to several hundred meters vide but only a fev meters deep. 101 TRINITY CONSULTANTS, INC For highly toxic substances, for which the concentration of concern nay be in the ppm range, the behavior during the gravity influenced phase of dispersion may not significantly affect the calculations. Moreover, in most if not all cases, the Gaussian dispersion calculation will tend to overestimate concentrations relative to methods which combine a dense gas dispersion Q and Gaussian calculations. 3. Gas Spills. The spill of a material which is normally a gas both at atmospheric conditions and at storage and/or transporation conditions results in the formation of air/gas mixture at a temperature somewhat below ambient temperature. The reduced temperature is the result of the pressure reduction between storage and/or transportation conditions and atmospheric pressure. An analysis of such a release using hydrogen sulfide as an example is provided by Echols. Bursts with Continuing Emissions When a tank or vessel fails, the release of the gas starts at a high rate but it rapidly decreases as the container becomes depres surized. 102 TRINITY CONSULTANTS, INC. VAB.0001093863 Under these conditions it is appropriate to divide the release individual hurst The should be analyzed first. This provides a worst case analysis. o^The following bursts or puffs will contain less contaminants. survive the first puff, the person should he able to survive D. Lower Flammable Limits All combustible gases have a lower flammable limit. If the concentration is higher than this level, then any spark or flame can cause an explosion. As a result, good engineering practice is to keep storage tanks of combustibles some distance away from open flames or sources of sparks. H I t 4 -103 TRINITY CONSULTANTS, INC. 093864 CHAPTER VII: REFERENCES 1 ACGIH, TLV'a, 1984-85, p.7. 2 Wu, John M. and Schroy, Jerry M. "Emissions from Spills" 1979. Paper presented at Conference sponsored by Air Pollution Control Association at Gainesville, Florida, February, 1979. (Proceedings available from Air Pollution Control Association, Pittsburgh, PA) 3 The Chlorine Institute, Inc. "Calculating the Area Affected by Chlorine Releases", June, 1982 (Chlorine Institute Pamphlet 74) 4. Kaiser, G.D. and Walker, B.C. "Releases of Anhydrous Anmonia from Pressurized Containers - The Importance of Denser-Than-Air Mixtures" Atmospheric Environment 12:12 (December, 1978, p. 2289-2300). 5. Meroney, Robert N. "Transient Characteristic of Dense Gas Dispersion" Journal of Hazardous Materials, 9 (1984, p.139-157). 6. Griffiths, R.F. and Kaiser, G.D. "The Accidental Release of Anhydrous Ammonia to the Atmosphere - A Systematic Study of Factors Influencing Cloud Density and Dispersion" 1979. Draft document prepared for Safety and Reliability Directorate, United Kingdom Atomic Energy Authority, Cheshire. 7. Harris, N.C. "Heavy Gas Dispersion", Appendix 6 "The control of Major Hazards - Advisory Committee on Major Hazards - Third Report", 1984, Her Majesty's Stationery Office, London. \ ii 8. McQuaid, J. "Overview of Current State of Knowledge on Heavy Gas Dispersion and Outstanding Problems Issues", 1985, Presented at Heavy Gas (LNG/LPG) Workshop, Toronto. 9. Echols, W. Terry "Estimating the Hazardous Radius of Exposure h From Accidental Releases of Hydrogen Sulfide Gas", Proceedings of 1976 National Conference on Control of Hazardous Material Spills, New Orleans. A \ 104 TRINITY CONSULTANTS, INC VIII Location of Spills and Data Required In all cases the most difficult part of analyzing a spill is to determine the quantity spilled* This task is particularly difficult in transportation accidents. * A. Transportation In most transportation accidents the person at the scene in rural areas is usually local firemen, a state policeman or a sheriff. In urban areas, many larger fire departments have a hazard material coordinator. The U.S. Department of Transportation publishes "Emergency Response Guidebook" (1984). Copies of this guide have been made available to each police, fire, civil defense and rescue squad vehicle in the United States. The procedure to use this guide is as follows: 1. Identify the material from: a) Data on Shipping papers b) Four digit number on an orange panel c) Material name that may appear on vehicle 2. Look up Material18 2-digit guide. 3. Turn to numbered guide pages. 105 TRINITY CONSULTANTS, INC. The on-8ceile coordinator is encouraged to call CHEMTREC for Immediate advice for those at the scene of emergencies. CHEMTREC immediately contacts the shipper of the hazardous materials for more detailed assistance and appropriate follow-up. It is strongly suggested that the on-scene coordintor keep the phone line open. The CHEMTREC facility consists of a teleconferencing bridge which allows experts from the shipper or anyone else to communicate with the on-scene coordinator. The user of the Guide is advised to purchase U.S/ Geological Survey Maps of the area of responsibility to aid in evacuations a where they are necessary. Preplanning and response team training is recommended. v Figure 17 is a reproduction of the Guide 20 which is used for chlorine, nitrogen dioxide, nitrogen tetroxide, and other gases. The guide also contains tables (Figure 18) specifying evacuation distances during the initial phase of an accident involving hazardous liquids or gases shipped in bulk or multiple-container loads i If a hazardous material cloud goes between several multi~story 106 TRINITY CONSULTANTS, INC Figure 17 HEALTH HAZARDS Poisonous; may be fatal if inhaled. Contact may cause burns to skin and eyes. Contact with liquid may cause frostbite. Runoff from fire control or dilution water may cause pollution. FIRE OR EXPLOSION May ignite other combustible materials (wood, paper, oil, etc.). Mixture with fuels may explode. Container may explode in heat of fire. Vapor explosion and poison hazard indoors, outdoors or in sewers. Keep unnecessary people away; isolate hazard area and deny entry. Stay upwind; keep out of low areas. Ventilate closed spaces before entering them. Wear positive pressure breathing apparatus and full protective clothing. Evacuate area endangered by gas. (See Isolation and Evacuation Table in back of guidebook; find the material by name.) FOR EMERGENCY ASSISTANCE CALL CHEMTREC (800) 424-9300. if water pollution occurs, notify appropriate authorities. FIRE Small Fires: Dry chemical or C02. Large Fires: Water spray, fog or foam. Move container from fire area if you can do it without risk. Stay away from ends of tanks. Cooi containers that are exposed to flames with water from the side untii well after fire is out. For massive fire in cargo area, use unmanned hose holder or monitor nozzles; if this is impossible, withdraw from area and let fire burn. SPILL OR LEAK Keep combustibles (wood, paper, oil, etc.) away from spilled material. Stop leak if you can do it without risk. Use water spray to reduce vapor but do not put water on leak or spill area. Isolate area until gas has dispersed. FIRST AID Move victim to fresh air; call emergency medical care. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Remove and isolate contaminated clothing and shoes at the site, in case of contact with material, immediately flush skin or eyes with running water for at least 15 minutes. Keep victim quiet and maintain normal body temperature. Effects may be delayed; keep victim under observation. 107 TRINITY CONSULTANTS, INC. Figure 18 TABLE OF ISOLATION & EVACUATION DISTANCES k ections feet 300 90 80 320 170 50 110 140 80 80 40 270 80 460 1 Directions | feet 620 180 160 Width miles 1.5 0.4 0.4 Length miles 2.4 0.6 0.6 670 1.7 2.6 350 0.8 1.3 100 0.2 0.3 220 I 0.5 0.8 290 0.7 I 1.0 170 0.4 0.6 170 1,4 2.2 80 0.2 0.3 570 1.4 2.2 160 0.4 0.5 980 2.5 3.9 108 TRINITY CONSULTANTS, INC VABT0001093869 Nitrogen dioxide (106?) | Nitrogen peroxide (1067) 1 Nitrogen tetroxide (1067) 1 110 220 0.5 0.8 Oleum. (1831) 280 580 1.5 2.2 PercMoromethylmercaptan (1670) 1 1 220 450 1.1 1.6 Phosgene (1076) 600 1250 3.3 5.2 Phosphorus trichloride (1809) Sulfur dioxide (1079) J 1 1 Sulfuric acidf fuming (1831)1 Sulfuric anhydride (1829) 1 Sulfur trioxide (1829) 1 110 120 280 220 0.5 0.8 250 0A 0.9 580 1(5 2.2 Titanium tetrachloride (1838) I 1 30 60 0.2 0.2 Trimethviamine, anhvdrous (1083) 1 i 50 90 0.2 0.3 THIS INFORMATION B POE USB IN ADDITION TO THE GUIDE PAGE RECOMMENDATIONS FOR HANDLING THE TO HAZARDS OP THESE MATERIALS IF THEY ARE NOT ON FIRE ____ 109 TRINITY CONSULTANTS, INC. buildings or down a valley, the cloud could affect people much further away than the distance specified. The guide also notes that occupants on the upper floors of multi-story buildings are likely to be safer remaining where they are if the heating and air-handling equipment in the building can be shut down. If a fire begins to burn the spilled material, the health hazard may become less important and the evacuation distance may not have to be as great as they were with no fire involvement. In order to estimate the dispersion of the gas at a spill, the following information is needed: Whether it is day or night Estimated wind speed Wind direction Amount of cloud cover (to determine stability) Description of topography Some firms maintain libraries of US6S maps of the transportation corridors most commonly used in shipping dangerous materials. B. Accidents at Plant Sites The instrumentation at a plant often provides a good estimate of the amount of gas released. It is recommended that all plants which handle or process toxic gases record meteorological data and have that data available at several locations in the plant. This data should include the following parameters: 110 TRINITY CONSULTANTS, INC * * b) Wind direction c) Standard deviation of wind direction Wind direction should be recorded with a low-mass wind vane, not the type that looks like a wingless, single-engine airplane* the vane should respond quickly to variations in wind direction* Figure 19 illustrates a typical Weather Station* It is recommended that wind speed and direction be recorded at a 10 meter elevation* The approximate costs are as follows: Parameter(s) Wind speed, wind direction, temperature and strip chart recorder Sigma-theta card Cassette recorder Tripod mast as shown 10 meter mast Dew point sensor Solar panel (Solar radiation) Tipping bucket rain guage Cost $ 3200 600 2800 150 300 675 450 475 The availability of real-time meteorological data will aid in forecasting the speed and direction of travel of any released material* Moreover, the recording of the data will be invaluable in determining the validity of any claims for compensation should there be an accident* TRINITY CONSULTANTS, INC. ----- >----------- VAB.9001093872 ipun Figure 19 112 i VAB.0001093873 Some firms that handle toxic gases place monitors along fence * lines* An analysis should be made of the width and the vertical dimension of any possible release. This should be compared to the actual or proposed spacing of inlets to the sampler. It is therefore suggested that the inlets to the sampler should be no more than 3 times sigma y apart in the horizontal direction and about one sigma z above grade for releases within 5 meters of the ground. ii3 TRINITY CONSULTANTS, INC. There are numerous techniques for reducing the risks. 1. Limit the amount stored at the site. Design a manufacturing process that immediately consumes any toxic gases in further processing. The reduced risk of an accident must be weighed against the reliability of the manufacturing process in which, for example, the failure of a phosgene production unit results in the immediate shutdown of the toluene diisocyanate plant. 2. Construct a building around the plant or loading area Many chemical plants are built outside with pipes and vessels suspended from a structural steel framework. If the entire process were located in a building, then a monitor could be installed on the forced draft building exhaust vent. Furthermore, the building exhaust vent could be elevated, like a stack, to greatly reduce ground level concentrations In some types of facilities there is a fear of an explosion which militates against an enclosed structure. One firm enclosed the process area down to an area about six feet above grade. A large cooling tower fan was installed on the gabled roof. This arrangement overcame possible explosion problems while insuring that most gases from any release would occur at i 114 TRINITY CONSULTANTS, INC VAB.0001093875 T T* * a significant elevation. 3. Conduct hazardous operations when dispersion is best* Bright, sunny days with moderate to strong winds are indicative of a great deal of atmospheric turbulence and the conditions which will most rapidly dilire a cloud* It may also be possible to select days or times wian the winds would not carry any cloud towards populated centers If a railroad were to attempt to move a punctured tank cir of hydrogen fluoride, it should be accomplished on a clear day vith strong winds in a direction to affect the fewest peopls* A semi-conductor manufacturer should choose to move bottles :f toxic gases such as arsine during the lunch hour when emp loyses are absent or during the weekend day shift* 4* Properly train people* Then a disaster occurs, the reaction of most people is unpredictable. There have been cases where employees have run t:wtrds a chlorine cloud and successfully sued their employer* Tterefrre, it is prudent to develop a detailed plan and to retearss it* Nearly everyone recalls tie fire drills that took place when they went to grammar sciocl* The fire bell would ring and students and teacher vcclc proceed quickly and orderly outdoors. After a veils the fire drill became routine and because it is, deaths from school fires are virtually 1 non-existent today A similar attitude is beneficial at a plant where drills should be conducted not just during the working day* but at all hours. Host of these drills can be announced in advance* but a few can be a surprise. The drill can test evacuation procedures* evacuation and plant shutdown procedures* evacuation and procedures. The personne contractors held The ideal situation one personnel react out of habit as a result of regular drills. 5. Design unique fittings to avoid misconnections. One the causes the Bhopal disaster was the introduction of water instead of nitrogen into a storage tank. One can speculate that the threads on the fittings of the water and nitrogen lines were alike. By making these fittings unique, an this type can be avoided. 6. Use existing equipment to increase dispersion. For example* if a vent that could carry a toxic gas release is near a boiler stack, duct the vent to it. The plume rise on the boiler stack * will greatly reduce ground level concentrations. If there is an incinerator or burner, supply at least part of the burner t 116 TRINITY CONSULTANTS, INC * VAB.0001093877 air from the forced draft ventilation of a building in which hazardous gases are used. 7. Provide comnunicetions equipment to nearby residents. In at least one location plant safety personnel can broadcast a message directly into homes that could be affected by a release. The residents can be directed to first, close all windows, second, open windows after the cloud has passed or, third, evacuate the area. Some plants are starting to rely on automatically dialed telephone messages. Although some plant managers have been reluctant to share their knowledge of the ?iaks with nearby residents, this will be a requirement of m British law effective January 1, 1986. 8. Use water sprays. Tests show that water spray curtains can mitigate the consequences of the release of heavy gases into the atmosphere.^ *2 The water spray curtain acts to entrain large quantities of air producing a rapid dilution of a dense plume. Several conclusions are drawn from the studies. Location of the barrier makes little difference but by placing it closer to * a source, both water use and construction costs are lowered. wind speeds tripled from 2 to 6 m/sec, the effectiveness of the barrier fell by 50 percent. Increasing the water pressure increased the rate of dilution. * The water spray systems were most effective under stable 117 TRINITY CONSULTANTS, INC. i VAB least a factor of 10 and often could get as large as 50. The barriers are most effective in rapidly decreasing n concentrations of flammable gases below the lower explosive limit. The use of water sprays appears to have only limited value where concentrations are less than 10,000ppm or distances are greater than 1000 meters from the source. 9. Construct retention areas. Construct dikes around storage tanks and build basins underneath large process vessels and rail or truck loading facilities. Design the basin to maximize the depth of the liquid and reduce the surface area. Make provision for pumping accumulated liquids to safe storage tank. 10. Ignite flammable gases. The standard procedure in natural gas drilling operations is to ignite a well blow-out if there is significant hydrogen sulfide in the gas. Not only does this convert the hydrogen sulfide to sulfur dioxide (a less hazardous gas) but it adds significantly to plume elevation because of plume buoyancy. 11. Store gases as refrigerated liquids. The catastrophic failure or even a large hole of a pressurized container results in an immediate release of the contents. If the same material were stored in a refrigerated container at atmospheric pressure, the v ..... I "Ff 118 TRINITY CONSULTANTS, INC mm leak from or failure of the container would result in a boiling pool on the ground. This would extend the period of release reducing the peak concentrations and allowing those in the path p of the cloud more time to escape. If a method of containing the leak exists, then it may be possible to recover the product reducing the magnitude of the release. 12. Use pressure relief valves. Many containers have "blow-out1' plugs that melt or are forced out under excessive internal pressure. The use of pressure relief valves will reduce the quantity of the material released and distribute the release of the entire contents of a vessel over an extended period. 13. Sample for contaminants. One reason many accidents occur is because of contaminated raw materials. It is wise to sample all incoming raw materials as well as manufactured raw tater ials contamination could cause an unplanned release. 14. plan time systems a toxic cloud can be helpful. On the other hand, the use of these systems may reduce managements1 interest in frequent, serious drills and thereby impart a false sense of security. Moreover, power to a computer may a result of a power failure or the catastrophic release itself causes a power failure. Management may wish to use the 119 TRINITY CONSULTANTS, INC. t y.Aa periodic, unplanned power failures at its plants as a means to evaluate shut-down procedures and emergency procedures using computer-based aids. 15* Seep people indoors. The indoor concentrations of pollutants are generally less than those outdoors. The ratio of the two 3 concentrations is: XL 1-e-ct Xo Xi Indoor concentration Xo Outdoor concentration Air changes per unit time t Time interval Typically a sealed building will experience between 0.1 and 1.5 air change per hour depending on the make-up air to the ventilation system. A building with open windows on a breezy experience 5 to 10 changes hour. In a typical office building with^ 1.5 / changes per hour the indoor five minute concentration wilA be only (^1-e-1.5/12 ) or 12 percent of the outdoor concentration. SS*' 0 4 1 \ 120 TRINITY CONSULTANTS. INC. VAB.0001093881 r*TT CHAPTER IX: REFERENCES 1. Meroney, R. N. and Neff, D. E. "Numerical Modeling of Water Spray Barriers for Dispersing Dense Gases", Boundary Layer Meteorology, 31 (1985) 233-247. 2. McQuaid, J. and Fitzpatrick, R. D., "Air Entrainment by Water Sprays: Strategies for Application to the Dispersion of Gas Plumes'*, Journal of Occupational Accidents, 5 (1983) 121-133. 3. Beattie, J. R., "A Quantitative Study of Factors Tending to Reduce the Hazards from Airborne Clouds", Appendix 3 Canvey Report (1978). t 121 TRINITY CONSULTANTS, INC. * mm X. Computer Models The first eleven models employ puff algorithms and may also use continuous release algorithms. The next group of nocsis starting with K. PTPLU are continuous release models that are part of the UNAMAP series of programs. A. SPILLS This model was developed by Shell Development Company, Houston, and given to the U.S Government for public distribution. 1 Three options depending on the nature of the spill have been incorporated in the model: 1) continuous spills, such as leaks from tank cars, tanks or pipelines, 2) instantaneously-formed pools of liquids or liquefied gases and 3) stacks, where the emission rate is assumed to be known. This model does not analyze concentrations from dense gas clcuds. For options 1 and 2, thermophysical properties (available as a subroutine in the computer program) of 36 potentially hazardous chenioals are used to calculate, through heat and mass transfer mechanisms, the evaporation rate, which becomes the emission rate for the atmospheric dispersion calculations. A 122 TRINITY CONSULTANTS, INC A 01093883 The first option is for a snail continuous leak of a liquid. Two key variables are unknown, the area of the pool and the emission rate into the atmosphere. Since the area of the pool *- is difficult to determine, the model makes the simplifying sumpt emission emission rate to the atmosphere. The model calculates the spill area based on convective mass transfer (evaporation). The model assumes ambient temperature and pressure so that there is no heat transfer between the pool and the earth. The second option considers instantaneously formed pools. The * mechanism by which the evaporation will take place depends on the nature of the chemical spilled. Chemicals with a normal boiling point below ambient temperature will first flash off due to the pressure drop between the storage pressure (the storage temperature has to be specified by the user) and atmospheric pressure. The evaporation rate due to this adiabatic flash calculation is assumed to occur during the first minute after the spill. The chemical will then form a pool of liquefied gas at its normal boiling point. In reality the remaining liquid after rapid depressurization is often an aerosol rather than a boiling pool. The difference between the temperature of the boiling pool and the ambient temperature will cause heat to be transferred from the ground (the soil is assumed to be at 123 TRINITY CONSULTANTS. INC v- ` VA'B. pool Mass transfer vind blowing over the pool, takes over when the heat transfer * evaporation rate becomes equal to the mass transfer evaporation Note that this occurs transfer decreases as time Increases whereas, the mass transfer rate is independent time The the chemical is evaporated* With this option the user must amount The third option provides for dispersion of gases from stacks, vents, leaks or other point sources* The user supplies up to 100 emission rates for each time interval from the initiation of the phenomenon. If only one rate is supplied, the program considers the case to be steady state* This option incorporates the Briggs plume rise formulas. This Pasquil1-Gifford dispersion coefficients are used in this model. Total calculated concentrations at a receptor are determined by integrating the contributions from puff centers within four standard deviations from the receptor. For area sources the initial plume width is set equal to the area width divided by 4*3. The output of the program contains a printer-plot of the A 124 TRINITY CONSULTANTS, INC. isopleths of concentrations from a release* Typically, the TLV-TWA and the STEL are displayed for the 36 chemicals analyzed by the program* This program is designed for use on an IBM mainframe computer* Although it is user-friendly, the user must have some type of communications link to the host computer* B* SAFER This system is the most widely used real-time toxic gas response system today* It is a sophisticated product that has been marketed very effectively. There are over 30 installations including some overseas. The manufacturer is SAFER Emergency Systems, Inc., 756 Lakefield Road, Westlake Village, CA 91361. The system is designed around a 32-bit microprocessor employing a Motorola 68000 CPU. It includes a high-resolution 19-inch color graphics screen, a monochrome CRT and a printer* Meteorological information is recorded on site and directly entered into the system* Monitored information on chemicals can also be entered directly. In its usual operating mode the programs are activated by a light pen. The color graphics terminal typically displays 1 r 1 | } I t I i ** ! i i j It 125 TRINITY CONSULTANTS* INC.------------- =----- --093886 m diagrams the plant so the operator can pinpoint maps of the area around the plant a gas cloud is displayed. The monochrome screen provides instructions to the operator such as persons to be notified and their telephone numbers, The printer is useful to print out the meteorological record previous day as veil as a list of landmarks, phone numbers, time of arrival of cloud, direction it is coming from, distance from the plant and the proper message to give the authorities. Also reported is the type of chemical, release time, spill size. maximum downwind distance the cloud will travel and a table of critical concentrations at various downwind distances. The system can also place telephone calls automatically, send messages over the telephone lines, and keep track of which calls were made and which calls were completed. The system answers critical questions often asked by plant officials during a release of a hazardous chemical. These include: 1) which direction the vapor cloud is moving, 2) will the concentrations downwind plant toxicity levels or explosive limits, 3) how soon will the cloud Arrive at population center, 4) when will the cloud disperse to a safe level. 126 TRINITY CONSULTANTS, INC v In the case of e leak, sensors tied directly into the system automatically detect the ambient concentrations of the escaping vapors and sound an alarm at the central station, thus alerting the plant operator to the release. The plant operator then enters information into the system regarding type of chemical released and size of leakage ("default" amounts are pre-stored for each plant equipment). Wind direction, speed, temperature end stability data, measured from a tower and sensors located on the plant site, are continuously fed into the system and automatically updated. The system then quickly calculates the projected path of the vapor cloud and atmospheric dispersion rate of specific chemical. This calculation of the cloud is displayed in different colors and superimposed over base maps of the plant and surrounding community. Should the system will automatically shi wind direction change new plant chemicals are programmed into the system and evaporation effects are taken into account in the on-going calculations. the emergency actions to be taken are tailored to the severity inating the problem 127 TRINITY CONSULTANTS, INC. V 4 Vah. over-reacting and causing an unnecessary evacuation* However, should the release be a severe one, the print-out provides pre-planned instructions on whoa to call and what to say* This includes telephone number, areas affected, evacuation routes, emergency procedures and health effects from exposure to the vapors* The dispersion model is a multiple Lagrangian Wall and can wind r both puffs and continuous sources* Complex terrain and channeling can be incorporated. No information was provided on the dispersion coefficients or on the mechanics for determining liquid evaporation or buoyancy effects* The basic price of this system is in the $70,000 range. The most common use of SAFER is in postulating scenarios and in conducting drills* C. CHARM This model was developed by Radian Corporation, 8501 Mo-Pac Boulevard, Austin, TX 78766* CHARM is an acronym for Complex Hazardous Air Release Model and it has been implemented on an IBM-PC with a color graphics screen* Data on 57 compounds are stored. Algorithms for continuous liquid release, continuous 128 TRINITY CONSULTANTS, INC wm Included. instantaneous liquid or gas releases and The dispersion model has been validated against actual / * jUi' .a>/4ttuudd ies of gas release experiments and can simulate the transport and dispersion of buoyant, neutral or heavier~than Meteorological data can be input automatically event data inputs are archived for documentation and data ana The software is priced at about $10,000 and there are about 40 purchases. Mot all purchasers have been able implement CHARM a? e>Fh D. CASE This system was developed by Environmental Systems Corporation 200 Knoxville. TN CARE is an acronym for Computerized Airborne Release Evaluation em The software can be implemented on an IBM-PC or HP200 personal comput er The system consists of 5 modules The source module contains an inventory their properties. It includes a gravitational slumping model for use with dense gas clouds. The meteorological module relies on observed data or it modifies observed data via a three dimensional in complex terrain. for use The dispersion module is based on a puff-advection model that has a variable trajectory. The display shows the location and concentration of the hazardous chemical. An effects module provides information on the hazard posed to health and welfare by the materials in the plume. It includes dose calculations for nuclear releases as well as data on the TLV and IDLH for chemicals. The fifth module provides the user with recommended response actions. E. HASTE This system was developed by Environmental Research and Technology, Inc., 696 Virginia Road, Concord, MA 01742. HASTE I is an acronym for Hazard Assessment System for Toxic Emissions. The system can be implemented on an IBM-PC or on an NEC APC. There is one known installation. $40,000. The system sell for about The system features include a menu driven decision assistance program supported by color graphics, computerized inventories of hazardous chemicals and their properties, pre-programmed release scenarios, dispersion models for dense gas and neutrally buoyant A rwV m 130 TRINITY CONSULTANTS, INC WcB: 1093891 plumes, real-time or user-input meteorological data, archiving m capability for input data and results and automated emerging protocols. F. EPCHEMS II This system vas developed by Enviroplan, 59 Main Street, West EPCHEMS II consists of Enviroplan Chemical Emergency Mitigation System and a Continuous Emissions Monitoring Data Acquisition System. The svstem bases its source term pressure, flov and level for any number of storage tanks and pipes to determine whether parameters are in accepted safe personnel and aids personnel to respond to the emergency It calculates and displays ions from the release on maps of the area. The system is implemented on a small Data General minicomputer. G. MESOCHEM, JR. This system vas developed by Impell Corporation (a subsiding of Combust Engineering, Inc.) 350 Lennon Lane, Walnut Creek, CA 94598. 131 TRINITY CONSULTANTS, INC 4 VAB. 9001093892 A This system was originally developed on a main frame computer or clients in the nuclear industry. It uses color graphics and m has many if not all the features common to SAFER, HASTE, CARE and EPCHEMS II. H. Other Systems Both NUS (Gaithersburg, MD) and Dames & Moore (Chicago, IL) have been prominent in developing systems for emergency response in the nuclear industry on large main frame computers. Both firms offer similar systems to chemical firms for toxic gas releases. Two other systems under development include CEES, Energy Impact 9- Associates, Pittsburgh, PA and MARKS, Ensco, Indian Harbor, FL. I. EPA Puff In 1982, EPA published "Estimating Concentrations Downwind from an Instantaneous Puff Release".2 A copy of this publication is included in the Appendix. This model is based on a summary of experiments on the dispersion of clouds from quasi-instantaneous releases contained in Meteorology and Atomic Energy 3 Turner refers to this work in the Workbook of Atmospheric Dispersion Estimates. 4Although it is difficult to make direct comparisons between the puff model and continuous models, the concentrations calculated using the quasi-instantaneous dispersion coefficients 132 TRINITY CONSULTANTS, INC are several times those using Pasquill-Gifford coefficients The EPA program calculates peak instantaneous values and time-averaeed values for times assumes steady state wind conditions* The user supplies the initial height of the release and the standard deviations of the initial cloud size* The three stability categories analyzed are unstable, neutral and stable* Concentrations are calculated for 12 downwind distances ranging from 10 meters to 30 kilometers* This model is not particularly user*-friendly in terms of both the calculations required by the user before creating an input and in the input format* The model does represent EPA's thinking regarding the analysis of ji / quasi*-instantaneous spills. J. TRPUF This model is based on the EPA puff model and was developed by Trinity Consultants, Inc* Its input is much more user-friendly and the output is significantly more useful than EPA puff* The model is executable on an IBM-PC and includes a graphics capability in which plots are produced on the PC printer. Figure 20 summarizes the differences between TRPUF and the EPA puff model* Figure 21 is a copy of the output of TRPUF and Figure 22 is a plot of the output produced on an IBMr*PC printer* This model is used primarily to help management analyze various f 133 TRINITY CONSULTANTS, INC VAB.0001093894 Figure 20 Major Differences Between TRPUF and EPA Puff Models EPA Model Concentration at release point and farther downwind Calculates a virtual distance so that the calculated concentration at release point is equal to the concen tration used as input. The user can also specify the distance downwind for which cloud dimensions are known Vectorially adds initial sigma values to sigma values for downwind distances, Average Calculates peak Calculates peak " *i * Concentrations instantaneous as well instantaneous at as average concentra all receptors and tions f:r all recep average concentrations tors. only at discrete receptors. Receptors Receptcr grid consists of 70 ctvnvind dis tances selected easily :y the user. Receptor grid consists of 12 downwind dis tances from 10 meters to 30 kilometers downwind Plume Rise Uses Briggs1 unstable/ neutral ncnectum plume rise fcr all stability classes. User inputs a fixed value independent of wind speed. Concentration Units User selects Ppm, mg/m- cr -g/n* grams /m3 Other Information Displays travel time ant signs values 13- TRINITY CONSULTANTS, INC Figure 21 iRFUF - R0D5 COPYRIGHT 1985 TRINITY CONSULTANTS, INC* A PUFF H0iL DEVELOPED BY TRINITY CONSULTANTS, RICHARDSON, TEXAS * EXAMPLE OF TRHJFS 214/234-8567 RELEASE AMOUNT (POUNDS) = 2.20500 RECEPTOR HEIGHT ABOVE SPADE (FEET) MOLECULAR IfEIGHT = 64*00 EXIT VELOCITY (FEET PER SECOND) AMBIENT TEMPERATURE (KG F) * 88.00 STACK DIAMETER (FEET) AMBIENT PRESSURE (MB) =1013,00 H1NB SPEED (KPH) STACK HEIGHT (FEET) COMPUTED VIRTUAL BIST I HORIZONTAL VERTICAL ABU 3.3 3.3 16.4 16.4 ABLE 83*3 85.3 5. INITIAL CONCENTRATION (P;,M) = 5.00E+05 5.000 INITIAL HORIZONTAL SIGMA (FEET) .00 1.50 INITIAL VERTICAL SIGMA (FT) = .00 5.0 DOWWIIND DISTANCE (FT) 0. 60.00 BOUNNIND PEAK INSTANTANEOUS CONCENTRATIONS AVERAGE CONCENTRATIONS FOR 300. SECONDS -- SIGMAS (FEET) DISTANCE (UG/M3) mm2) TRAVEL UNSTABLE NEUTRAL STABLE (FEET) UNSTABLE NEUTRAL STABLE MAXIMUM UNSTABLE NEUTRAL STABLE MAXIMUM (MINUTES) HOP VER HOR VER HQR VER 20 5.5409E-07 2.2128E-0? 6.7703E-0? 5.5409E-07 1.7591E-09 4.5425E-12 1.1093E-11 1.7591E-09 40 2.0281E+01 7.2767E-10 4.4680E-09 2.0281E+01 1.1391E-01 2.2348E-12 8.5457E-12 1.1391E-01 60 1.9562E+03 3.3662E-10 3.1362E--09 1.9562E+03 1.5583E+01 1.3666E-12 6.8435E-12 1.5583E+01 30 1.2150E+04 1.8649E-10 2.3043E-09 1.2150E+04 1.2461E+02 9.3783E-13 5.6399E-12 1.2461E+02 100 2.3975E+04 1.1553E-10 17539E-09 2.8975E+04 36224E+02 6.9102E-13 4.7519E-12 3.6224E+02 120 4.5077E+04 4.2469E-10 1.3728E-09 4.5077E+04 6.6321E+02 2,9391E-12 4.0747E-12 6.6321E+02 140 5.6339E+04 1.9488E-07 1.0993E-09 5.6339E+04 9.5187E+02 1.5296E-09 3.5444E-12 9.5IB7E+02 160 6.2312E+04 1.7899E-05 8.9711E-10 6.2312E+04 1.1873E+03 1.5694E-07 3.1199E-12 1.1873E+03 180 6.4114E+04 5.3571E-04 7.4386E-10 6.4114E+04 13586E+03 5.1847E-06 2.7738E-12 13586E+03 200 6.3107E+04 7.4O87E-03 6.2525E-10 6.3107E+04 1.4710E+03 7.8394E-05 2.4873E-12 1.4710E+03 220 6.0408E+D4 5.9064E-02 5.3177E 10 6.040SE+04 1.5350E+03 6.7793E-04 2.2469E-12 1.5350E+03 240 5,6808E104 3.1416E-01 4.5695E- 10 5.6803E+04 1.5621E+03 3.8856E-03 2.0429E-12 1.5621E+03 260 5.2623E+04 1.2322E+00 3.96221 10 5.2823E+04 1.5620E+03 1*6331-02 1.8660E-12 1.5620E+03 230 4.3773S+04 3.8245E+00 3.4633E 10 4.8773E+04 15427E+03 5.4052E-02 1.7168E-12 1.5427E+03 J.'V -.4843E+04 9.8854E+00 3.0491E 10 4.4843E+04 1.5103E+03 1.4836E-01 1.5848E-12 1.5103E+03 320 4.1134E+04 22095E+01 2.7017E 10 4.1134E+04 1.4692E+03 3.50S4E-01 1.4690E-1'2* 1.4692E+03 340 3.7693E+04 4.3934E+01 2.4079E' 10 3.7693E+04 1.4228E+C3 7.3567E-0! 1.3666E- 12 1.4223E+03 360 v7 * i6E?04 79416E+01 2.1575E 10 3.4536E+04 1.3733E+03 1.39S3E+00 1.2756E- 12 I.3733E+03 1 - B 1 3,i659E+04 1 * 3271E4-02 1.9424E 10 3.1659E+04 1.3225E+03 2.4503E+00 1.1942E 12 1.3225E+03 "t Ai'tA/, ..?C50ir04 2.0776E-02 1.7566E 10 29050E+04 1.2717E+03 4.0143E+00 1.1212E- 12 1.2717E+03 -20 2.6688S+04 3.0788E+02 1.5949E 10 2.6688E+04 1.2215E+03 6.2112E+00 1 * 0553E- 12 1 4.4.1JL . V J 440 2.4554E+04 4.3556E+02 1.4536E 10 2.4554E+04 1.1726E+03 9.1568E+0C 9.9557E 13 1.1726E+03 460 430 2.2625E+04 2.C832E+04 5.9227E+02 7./844E+Q2 1.32P4E 1.2198E 10 10 2.2625E+04 2.0882E+04 1.I252E+03 1.0797*+03 141.*2^9*.5cA2vAEt++O01l 9.4130E8.9179E 13 13 1.1252=+03 1.0797E+03 500 1.93C5E+04 9.9350E+02 1. 10 1.9305E+O4 1.0361+03 2.3400E+01 8.4643E 13 1.0361L+03 .045 .091 .136 .182 .227 .273 .318 .364 .409 .455 .500 .545 .591 .636 .682 .727 .773 * 315 .864 .909 *955 1.000 1.045 1.091 1.136 37 K 11 7 15 9 18 11 22 2 3 1 1a 3 4 > 2 4 4 2 _ 452 56 2n 13 25 15 27 17 30 19 33 20 35 6 7 3 A 773 8 8 8 9 3 n 99 * 22 38 10 10 < 1 24 40 11 10 4 7 26 43 12 11 4 23 45 12 12 41 20 47 13 12 5 * 5071 V* W77W 52 *mt ^ **' */ mt V ** 54 56 58 14 13 15 13 15 14 16 14 17 15 5 S Vsw 5 6 * A * 60 4*? 62 18 15 18 16 6 6 1 m 1 -4 65 19 16 w / 45 67 20 17 6 m 47 69 21 17 7 a 520 1.7S77E+04 12360E+03 1.0359E 10 1.7877E+04 9.9452E+02 3.0148E+01 8.0487E 13 9.9452E+02 540 1.6533E+04 1.5038E+03 9.5846E 11 1.6583E+04 9.5490E+02 3.7935E+01 7.6657E 13 9.5490E+02 560 1.5408E+04 1.7940E+03 .8899E 11 1.5408*404 9.1724E+02 4.6751E+01 7.3121E 13 9.1724E+02 SvUOVft 1.4339E+04 2.1035E+03 .2645E 11 14339E+C4 8.8147E+02 5.6565E+01 6.9849E 13 8.8147E+02 600 1.3366E+04 2.4290E+03 7.6997E II 1 * 3366E+04 8.4753E+02 6.7328E+01 6.6813E 13 8.4753E+02 1.182 1.227 1.273 1.318 1.364 4rv.9tl 71 72 52 74 21 17 22 18 23 18 7 7 7 $ j % ? 76 24 19 7 56 7B 24 19 e * V6b V 1.2478E+04 2.7668E+03 7.1881E 11 1.2478E+04 8.1534E+02 7,8978E+01 6.3992E-13 8*1534E+02 640 1.1667E+04 3.1135E+03 6.7234E 11 1.1667E+04 78480E+02 9.1440E+01 6.1363E 13 7.8480E+02 660 1.0924S+04 3.4656E+03 6.3002E 11 1.0924E+04 7.55B5E+02 1.0463E+02 5.8910S 13 7.5585E+02 680 1.0244E+04 3.8200E+Q3 5.9133E 11 1.0244E+04 72838E+02 1.1847E+02 5.6616E 13 7.2838E+02 700 9.6184E+C3 4.1736E+C3 5.5602E-11 9.6184E+03 7.0232E+02 1.3235E+02 5.4467E 13 7.0232E+02 1.40? 1.455 1.500 1.545 1.591 57 80 25 20 8 * 59 82 26 20 8 t 61 84 26 21 8 * 62 86 27 21 8 t 64 87 28 21 9 l mm rw 135 VAB.0001093896 MR mm mm Figure 21 (Cont'd) A TRPyF - MODS COPYRIGHT 195 TRINITY CONSULTANTS, INC. A PUFF MODEL DEVELOPED BY TRINITY CONSULTANTS, RICHARDSON, TEXAS i EXAMPLE OF TRPUF5 214/234-8567 RELEASE AMOUNT (POUNDS) = 2.20500 RECEPTOR HEIGHT ABOVE GRADE (FEET; 5. INITIAL CONCENTRATION (PPM) = MOLECULAR HEIGHT = 64.00 AMSIENT TEMPERATURE (DEG F) = 88.00 EXIT VELOCITY (FEET PER SECOND) 5.000 INITIAL HORIZONTAL SIGMA (FEET) STACK DIAMETER (FEET) 1.50 INITIAL VERTICAL SIGMA (FT) = AMBIENT PRESSURE (MB) =1013.00 WIND SPEED (M?V) = 5.0 STACK HEIGHT (FEET) = 60.00 DOWNWIND DISTANCE (FT) = COMPUTED VIRTUAL DISTANCES (FT) HORIZONTAL VERTICAL UNSTABLE 3.3 3.3 NEUTRAL 16.4 16.4 STABLE 85.3 85.3 5.C0E+C5 + "V0 ,00 0. PEAK INSTANTANEOUS CONCENTRATIONS AVERAGE CONCENTRATIONS FOR 300. SECONDS SIGMAS (FEET) -- DISTANCE (FEET) UNSTABLE (UG/M3) NEUTRAL STABLE MAXIMUM UNSTABLE (UG/M3) NEUTRAL STABLE TRAVEL UNSTABLE NEUTRAL STABLE MAXIMUM (MINUTES:1 KOR VER HOR VER HOR VER 800 7.1553E+03 5.8462E+03 4.1752E-11 7.1553E+03 5.9O44E+02 2.0986E+02 4.5504E-13 5.9044E+02 900 1000 5.4742E+03 7.2158E+03 3.2330E-U 7.2158E+03 5.0321E+02 2.S307E+02 3.8735E-13 5.0321E+02 4.2882E+03 8.2037E+03 2.5660E-11 8.2037E+03 4.3417E+02 3.6025E+02 3.3524E-13 4.3417E+02 1100 3.4273E+03 8.8252E+03 2.0786E-11 8.82525+03 3.7870E+02 4.2249E+02 2.9373E-13 4.2249E+02 1200 2.7B67E+03 9.1378E+03 1.7128E-11 9.1378E+03 3.3350S+02 4.73385+02 2.6012E-13 4.7338E+02 1.818 2.045 2.273 2.500 2.727 72 96 81 105 89 113 97 122 105 129 32 23 10 35 25 11 39 27 11 42 29 12 45 31 13 5 5 6 6 6 1300 2.2997E+03 9.2101E+03 2.2435E-11 9.2101E+03 2.9620i02 5.1310E+02 3.6422E-13 5.1310E+02 1400 1.9223E403 9.1056E+03 3.2298E-10 9.1056E+03 2,6504E+02 5.4262E+02 5.5789E-12 5.42625+02 *VV V 1.6255E+03 8.8774E+03 4.2657E-09 8.8774E+03 2.3874E+02 56329E+02 7.8C31E-11 5.6329E+02 1600 1.3332E+03 S.56735+03 4.0331S-08 8.5673Ef03 2.1634E+02 5.7651E+02 7.7935E-10 5*76515+02 1700 1.1962E+03 8.2069E+03 2.8633E-07 8.2O69E+03 1.9709E+02 5.S361E+02 5.8267E-09 5.8361E+02 2.955 3.192 3.409 3.636 3.864 113 137 121 145 129 152 137 160 145 167 49 33 14 52 34 15 56 36 16 59 38 17 62 39 18 7 7 7 7 8 1800 1.0390E+03 7.8191E+03 1.6029E-06 7.8191E+03 1.8041E+02 5.3578E+02 3.4233E-08 5.8578E+02 OAA .7vV 9.0396E+02 7.4205E+03 7.3509E-06 7.42C5E+03 i.6587E+02 5.9401E+02 1.6438E-07 5.9401E+02 ^ AA A w t tn VV 3.C039E+02 7.02255+03 2.8491E-05 7.0225E+C3 1.531CE+02 5.7917E+02 6.6361E-07 5.7917-+02 2500 4.5860E+02 5.23445+03 4.1562E-03 5.23445+03 1,0768E+02 5.2927E+02 1.1737E-04 5.2927E+02 * : n^i:AI -V V V 2.8996E+02 3.9020E+03 9.5734E-02 3.9020E+C3 s.osocs+o; 4.66KS+02 3.1695E-03 4.6614E+C2 4.091 4.318 4.545 5.682 6.81S 3500 1.9643E+02 2.9558E+03 7.9806E-01 2.9558EiQ2 6.2S2S i/',* . V* 4.0661E+02 3.C201E-02 4.0661-+C2 7.955 j K P. A * . V 1.4003E+02 22832E+03 36077E+00 2.2332E+03 5.0615 v * 3.54955+02 1.5335E-01 3.54958+02 9.091 **p i* :: i k v 1.0382E+02 17977E+03 1.1004E+0! 1.7977E+C3 i * 762 *4* 0V 3.1133-+02 5.1637E-01 3.1133E+C2 10,227 - :1 VVV 7.9402E+C1 1,4406E+03 2.5727E+01 1.4406E+03 3.5087*tO1 2.7478E+C2 1.3238E400 2.7478E+02 11.364 m VV 6.2231E+01 1.1727E+03 4.9876E+01 1.1727S+C3 2.9893-+01 2.44125+02 2.8004E400 2.4412E+02 1O caa / . *i *1 WVV 152 174 66 41 19 3 160 181 69 43 20 8 1884 1 / * AW IWv 72 44 21 8 206 221 89 51 25 10 244 252 105 58 29 11 281 283 12! 65 33 12 317 311 136 71 37 13 339w J A ^ 152 77 41 14 3667 DA w7v 167 83 45 14 183 89 4?T Q 7 flv 4L iJ iAAA W V i/ V 4.9885E+01 9.6808E+Q2 8.43805+01 96808Ef02 2.5747 +01 2.1327E+02 5.1123E400 2.1827E+02 13.636 ; 50 0 *::o 4.C665E+01 3.3651E+01 8.0917E+02 6.8386E+02 1.2893E+02 1.8222E+02 8.0917E+02 6.83S6E^02 2.2371 +01 1.?5?c -- in- V* 1.96355+02 1.7762E+02 8.3816E+0C 1.26^31+01 1.9635E+02 1.7762E+C2 14.773 15,909 V v" T *VV 2.8210E+01 5.8368E+02 2.4233E+02 5.8368E+C2 1.7242 +01 1.-151E+02 1. / c-57tt01 1.61515+C2 17.045 3000 2.3913E+01 5.G261E+02 3*0710E+02 5.0261E+02 1.5266 +01 1.4756E+02 2.3965E+01 1.47568+02 18.182 461 419 198 95 53 16 496 444 213 100 57 17 463P71 vvi 228 105 61 13 566 493 243 111 65 13 600 516 253 116 68 1? 8300 -000 17)00 4 * ^ P. ft 1 * , HI * vVV W ^ *. A, , Ar i: 44V VW 2.0482E+01 4.3625E+02 3.74355+02 4.3625E+02 1.3582E+01 1.3541E+02 3.0816E+01 1.35415+02 1.7694E+01 3.S138E+02 4.42UE+02 4.4211E+02 1.2137E+01 1.2475E+02 3.8274E+01 1.2475E+02 1.3510E+01 2.9706E+02 5.7276E+02 5.7276E+02 9.8079S+OQ 1.17008+02 5.4414E+01 1.0700E+02 1.1923E+01 2.6438E+02 6.3328E+02 6.3328E+02 8.8642E+00 9.95545+01 6.2SUE+01 9.95545+01 1.0583E+01 2-3647E+02 6.8952E+Q2 6.8?52S+('2 V vv' * *f V 9.2379E+01 7.1237E+01 9.2879E+01 19.318 20.455 22.727 23.864 25.000 635 540 272 121 72 20 669 563 287 126 76 21 737 608 316 135 83 p 771 630 331 140 87 23 805 651 345 145 91 23 * * .vv 4 , * a A 1 ? i A b VV V 4 AA i. tap * V 13000 13:00 9.4439E+00 2.12475+02 7.4102E+Q2 7.4102E+02 7.3110 +00 8.6365E+G1 7.9645E+01 8.6865E+01 . !3.4680E+00 1.9172E+02 7.8752E+02 7.8752E+02 6.6695 +0C 8.1422E+C1 3.7S27E+01 8.7887E+01 7.6266E+00 1.73685+02 8.2893E+02 8.2893E+02 6 10 +00 7.c473E+01 9.5902E+01 9.590SE+01 6.8971E+00 6.2609i+00 1.5790E+02 1.4404E+02 8.6532E+02 B.9632E+02 8.6532E+02 8.9682E+02 f55,i*9*6V0- +00 41 II I V V* i + 7.1957E+01 6.7320tT01 1.03655+02 l.::o7Er02 1.0365E+C2 l.UC'E+02 26.136 27.273 23.409 29.545 30.682 838 673 872 694 905 715 938 736 971 757 360 149 94 374 154 93 3SS 158 102 402 163 105 417 167 109 24 25 25 26 26 136 * VAB.0001093897 Figure 22 EXAMPLE OF TRPUF5 iOf> 4* MAXIMUM CONCENTRATIONS (UG/M3) FOR ALL STABILITIES DISTANCE (FT) 137 ft VAB.0001093898 This model is used primarily to help management analyze various leak scenarios and determine the likely risks. K. PTPLU PTPLU is an adapted and improved version of PTMAX for quickly analyzmg the approximate location of maximum concentrations and the meteorological conditions under which it occurs for a single point source. Most air quality studies will start by analyzing a representative sample of stacks with this program to guide the receptor placement in more extensive modeling. PTPLU determines maximum concentrations through a process of iteration. In this process, concentrations are calculated for gradually increasing downwind distances until the peak is passed, then the program decreases the downwind distance until a peak is passed again. After several reversals, the maximum is found. Stack tip downwash and partial plume rise can be considered in the calculations. requires the user to specify the meteorology. In addition to analyzing point sources, it accepts area sources, two types line sources and two types of curved path sources. Up to 99 138 TRINITY CONSULTANTS, INC. sources of each type can be analyzed. Concentration estimates can be made at 99 user-specified receptor locations. One unique feature is a superior area source algorithm. This makes models particularly useful in analyzing, fugitive dust sources, emissions from waste treatment ponds and land fills, transportation sources, and situations involving sources other than stacks. M. ISCST This model is the most versatile of the EPA model for analyzing short term concentrations because of its numerous features that aid the user. If used unwisely, it can be very expensive in terms of computer time. i Sources may be grouped so that average concentrations or deposition from combined sources can be calculated. The ISCST model can analyze point, area and volume sources. Source emission rates may be varied. Receptors may be located in Cartesian or polar coordinates. The effects of stack-tip downwash, building wakes and gravitational settling may also be modeled ISCST has one rural and two urban modes. The Rural Mode uses rural mixing heights and Pasquil1-Gifford dispersion 139 TRINITY CONSULTANTS, INC- --------- VAE. coefficients* Urban Mode 1 uses urban mixing heights, Pasquil1-Gifford coefficients, and redefines the E and F stability classes as D (neutral) stability. Urban Mode 2 also uses urban mixing heights and Pasquil1-Gifford coefficients. Additionally, Urban Mode 2 combines the E and F stability classes, and uses the Pasquil1-Gifford dispersion coefficients for the stability class one step more unstable than the indicated category. For example, if the meteorological data indicate C stability, Urban Mode 2 will use the coefficients for B stability. Urban Mode 2 is recommended for area sources but should not be "+ used for stack sources in modeling studies for regulatory purposes. If the pollutant is depleted by an exponential time-dependent decay mechanism, the user can specify a decay coefficient. Particulate matter with an appreciable gravitational settling velocity can be modeled by using the gravitational settling option. The user divides particulate emissions into a mavimm of 20 settling categories according to particle size. The settling velocity, mass fraction of total particulate emissions, and surface reflection coefficients must be specified for each category. A i 140 TRINITY CONSULTANTS, INC. mm VAB.0001093901 Emission rates may be varies, 1) by hour of the day, 2) by season or month, 3) by hour of the day and season or 4) by wind p speed and stability class. For point sources the following parameters must be specified: release height, exit velocity, inside diameter and exit temperature* The effect of nearby building wakes on - concentrations can be modeled using the Huber-Snyder method by entering the building height, width and length* Entering these dimensions automatically causes the wake effects option to be used. For area sources, the user enters the location of the southwest corner of each area source square, the length of a side and the effective emission height* For volume sources, the user enters h the location and the height of the center of the volume source and the initial horizontal and vertical plume dimensions* The building wake effects option cannot be used with volume or area sources The user may select either a Cartesian or polar coordinate system to locate receptors* UTM coordinates can be entered if a Cartesian system is specified. For the polar system a radial distance from a user designated origin and the angle measured clockwise from north are specified* For a single source or a 141 TRINITY CONSULTANTS, INC. group sources in close proximity, the polar system is easiest use system usually more convenient. The user may d grid and/or discrete receptors. A Cartesian or polar grid can be generated by the program. Discrete receptors may be located in either Cartesian or polar coordinates coordinate system used specify discrete receptors does not have to be the same as the grid system. The user may fi convenient, for example use Cartesian coordinates locate discrete receptor plant fence line and polar coordinates for grid beyond the fence line in the same run. the source modeled may base each source and cannot the lowest stack height or height the Receptor heights emission There are six categories of program output. Any or all of these categories may be output at the user's option. The first category reproduces the input data for the problem run. This category contains all control parameters, meteorological and other constants, receptor data and source data. Additionally, * 142 TRINITY CONSULTANTS, INC 11 hourly Meteorological data proeeaaad by the program may be output as p&rfc of this cstsgory* The second category produces 4 an output containing the concentrations at each receptor for each day of meteorological data processed in the problem run. For each day, tables shoving concentrations for time periods and groups of sources specified by the user are printed. The third category produces an output containing the concentrations at each receptor for groups of sources specified by the user 4 averaged over the number of days of meteorological data -p processed m the run. This option allows average concentrations for time periods up to a year to be calculated with ISCST. The fourth category contains tables of the highest and second highest concentrations calculated at each receptor for sources or groups of sources time periods specified by the user. The fifth category contains a table of the maximum 50 concentrations calculated for the problem run for each time period and source group combination. The sixth category outputs the concentrations to magnetic tape. If deposition is being calculated, deposition values can be output using the above options. N. VALLEY This model has two modes of use. It can be used to estimate 24-hour and annual concentrations at receptors located above 143 TRINITY CONSULTANTS. INC------------------------ wflffl5io93904 r* stack height. VALLEY COMPLEX COMPLEX this. Alternatively, VALLEY can be used to calculate annual averages in flat terrain for rural areas. The model analyzes 112 receptors located at seven distances on sixteen radial lines. The user can also specify worst--case term meteorology Ground*level elevations are subtracted from the effective stack height. In however less than ten meters allowed to be This is illustrated in Pigure 23. Short-term calculated concentrations from area and/or point sources calculated using Briggs' plume rise and Pasquil1-Gifford vertical dispersion coefficients In the horizontal, the plume is assumed to be 22.5 degree The assumes that a given type of meteorology 6 hours out of 24. term for divided by 4 to produce a 24-hour estimate. The output consists of a print-plot of calculated concentrations along with detailed data. The user can specify a print-plot of each source. the total from all sources and an map permits one to scale the map can be placed directly over standard U.S. Geological Survey maps This model has until a better model is proven One of the frequent A 144 TRINITY CONSULTANTS, INC VAB1)001093905 TERRAIN ADJUSTMENTS FQR SELECTED GAUSSIAN MODELS -VALLEY MODEL STABLE CONDITIONS Ficire 23 O UJ Xl CM CM I X M O UJ X UoaJ 5 VAB.0001093906 UJ 2 CL questions concerns the 10-meter assumption, but it is relatively y unimportant at distances of 2 kilometers or more from a stack. More important is the shape the terrain. If a plume carried towards a vertical cliff plume inpingement may On the other hand terrain were rather gently sloping, the air would tend to follow the slope. One indicated that the overestimate in this case was a factor 0. TEM8 The TEM (Texas Episodic Model) was developed by the Texas Air Control Board to predict air pollution concentrations for periods up to 24 hours. Since then, it has been revised and modified to increase its flexibility and utility. The current version is TEM-8 (Version 8). The TEM was M alternative to the EPA models, PTMPT and PAL. developed as an In developing the TEM, the Texas Air Control Board incorporated a number of enhancements that provided flexibility and speed in the program operation. PTMPT and PAL were originally developed to provide a method to compare calculated and observed pollutant concentrations. For this comparison, the user input receptor points and meteorological data that would correspond to actual conditions. In contrast, the TEM calculates concentrations for a program generated grid using meteorological data supplied by the user. lap* IMP 146 TRINITY CONSULTANTS, INC 1093907 By varying the input of meteorologica 1 data, the TEH is used primarily to identify worst case conditions over the area covered by the grid. Both PTMFT and PAL could also be used to simulate worst case conditions, but these conditions could only be analyzed for user-specified receptor points. An additional enbanceaent mad. to IBM reduce* the program run time. This enhancement creates a data table of precalculated constants. Thxs data table allows the program to go through the concentration calculations only once and interpolate the other values. This enhancement provides accurate concentration predictions with a substantial saving of computer time. p In 1983, TEM was modified to allow the user to input building dimensions so that wake effects can be analyzed as they are in ISCST. Finally, the TEM uses a time-averaging technique to spread the plume in the crosswind direction. The program takes the calculated sigma--y values for a 10-minute period and adjusts it to a 30-minute, 1--hour or 3-hour value. In this method the mass of the plume cross section is conserved for all averaging times. The 24--hour concentration may be obtained by summing the three-hour values for eight scenarios or 24 1-hour values. 147 TRINITY CONSULTANTS, INC. V7tBT questions concerns the 10-meter assumption, but it is relatively unimportant at distances of 2 kilometers or more from a stack. More important is the shape of the terrain. If a plume is carried towards a vertical cliff then plume inpingement may occur. On the other hand, if the terrain were rather gently sloping, the air would tend to follow the slope. One study indicated that the overestimate in this case was a factor of 20. TEM8 The TEM (Texas Episodic Model) was developed by the Texas Air Control Board to predict air pollution concentrations for periods up to 24 hours. Since then, it has been revised and modified to increase its flexibility and utility. The current version is TEM-8 (Version 8). The TEM was developed as an alternative to the EPA models, PTMPT and PAL. In developing the TEM, the Texas Air Control Board incorporated a number of enhancements that provided flexibility and speed in the program operation. PTMPT and PAL were originally developed to provide a method to compare calculated and observed pollutant concentrations. For this comparison, the user input receptor points and meteorological data that would correspond to actual conditions. In contrast, the TEM calculates concentrations for a program generated grid using meteorological data supplied by the user. 146 TRINITY CONSULTANTS, INC. ADJUSTED SIGMA-Y RELATED TO SAMPLING TIME Stability (P-G) 10 Minut es 3Q Minutes 1 Hour 3 Hou A B C D E &F 1.0 2.10 3.35 7.04 1.0 1.83 2.68 4.90 1.0 1.60 2.14 3.42 1.0 1.40 1.71 2.38 1.0 1.21 1.37 1.66 Sampling time options 1 through 4 correspond to 10-, 30-, 60- and 180-minute times Sampling time are for 24-hour evaluations using either eight 3-hour scenarios or twenty-four 1-hour scenarios. The last two options are for a variable evaluation time depending on the number of scenarios entered. Option 7 assumes the scenarios are for 10 minutes while option 8 assumes one hour. For example, using option 7 six inute scenarios will produce a 1-hour TEM calculates concentrations at up to 2500 locations in a rectangular grid from up to 300 point sources (stacks) and 50 area sources. The user has several options for presenting the calculated data: a list of receptors with concentrations, a print plot with concentrations in their correct relative location, a punched card output of concentrations for subsequent use in plotting, a list of the amount of pollutant contributed by the five most v important sources to each receptor and a list of maximum concentrations for each scenario. * 148 TRINITY CONSULTANTS, INC. VAB.0001093910 CHAPTER X: REFERENCES 1* Fleischer, M.T. "SPILLS An Evaporation/Air Dispersion Model for Chemical Spills on Land", December 1980 User's Guide available from National Technical Information Service (KTIS), publication number PB83-109470 ($403)* 2. Petersen, William B. "Estimating Concentrations Dovnvind from an Instantaneous Puff Release", August 1982* Available from U.S. Environmental Protection Agency as EPA 600/3-82078 or from NTIS as PB82-261959. 3. Slade, David H. "Meteorology and Atomic Energy", 1968. U.S. Atomic Energy Commission, pp 120, 173-175. 4. Turner, p. 41. 149 TRINITY CONSULTANTS, INC / VAB.0001093911 XI. Evaluation of Risks "Safe" does not mean risk-free. There is no activity or product that does not carry some potential for accidental injury* Often this is related to the misuse of a product or equipment* Vhat "safe" means is that society considers the risk acceptable. This chapter is concerned with how to identify possible hazardous situations, some typical causes of hazards, how to conduct a hazard and operability survey and briefly how to relate the hazard to risk. A. Development of Accident Scenarios Before applying the techniques for analyzing dispersion in the 4 atmosphere, an ana should be performed to me possible disaster scenarios. From such an analysis the plant manager can distinguish the accidents which have trivial consequences from those that are significant. Furthermore, the significant possible accidents can be dissected to determine whether improved process design, modification of equipment, improved operator training or other safety measures could be employed to reduce the risk. This analysis of significant disaster scenarios will aid in the preparation of contingency plans for the plant. Although the computer provides plant managers with the ability to respond in real-time, it would be unwise to not rehearse responses for the 150 TRINITY CONSULTANTS, INC v? most likely disaster scenarios The loss of life from releases or ignition of flammable materials in this century is about equal to the loss of life from hazardous gas releases. Most studies of hazards generally include both ignitable releases as veil as toxic gas releases. The property damage from explosions and fires is often much greater than from a toxic gas release alone. The table below summarizes accident statistics. Substance Reference Chlorine Chlorine Ammonia Flammable gases Ammonium Nitrate Ethylene Oxide 1 2 1 1 1 1 Accidents Total Fatal 18 10 28 15 11 5 24 19 33 22 Deaths in Fatal Accidents 112* 120* 41 306+ 1132 5 * Excludes deaths of about 5000 allied troups at Ypres, Belgium in April, 1915. + Excludes the LPG incident in Mexico City, 1984 in which 300 lives were lost. Reference 1 is dated 1979 while Reference 2 is dated 1974. * B. Causes of Failures On June 1, 1974 a release of 40 tons of cyclohexane vas ignited in a large fire ball which largely destroyed a chemical plant at Flixborough, England, killing 28 workers. Several public inquiries were held and one result was a decision to conduct an extensive study of the chemical refinery complex at Canvey near the mouth of the Thames. This study was the first major risk assessment study made for a large refinery/chemical complex. The British Health and Safety Executive Commissioned a $600,000 study which was conducted by the Safety and Reliability Directorate of the Atomic Energy Authority. The selection of the contractor was a recognition of the fact that the nuclear industry has pioneered the development of risk analysis procedures. 3*4 The principal factors involved in failures include:^ a. Operator errors b. Metallurgical fatigue or aging of ma c Internal or external corrosion d. Loss of process control, e.q. pressu flow, etc. e. Overfilling f. Introduction of Impurities g- Fire and/or explosion h. Missiles i. Flooding usually stated m terms rn a year. Thus, an event that can occur once in 100 years has h 152 TRINITY CONSULTANTS, INC 'T 1093914 a probability of 10E-2 thi* year. One event in a million year* is 10E-6. A surprising number of accidents are the result of operator error in which water is introduced to a tank inadvertently, an improper chemical is used to clean a tank an incorrectly pumps caustic soda into a tank of sulfuric acid* It is not enough to examine the obvious sources of a toxic gas it important to speculate chemicals manufactured, stored or consumed at a site* C. Hazard and Operability (HAZOP) Studies One of the first steps to assess potential hazards is a carefully structured hazard and operability (HAZOP) study* It is suggested that a team of three to five members be assembled along with flow sheets of a proposed or an existing process*6 The team should meet for no more than three hours at a time and a seasoned study leader should act as chairman* As a general rule, each individual part studied, such as each main pipeline into a vessel, will take about 15 minutes* Another way to estimate time is to allow 2*5 hours per vessel* The author of the Guide indicates that after several sessions the initial tedium vanishes and the members start to derive satisfaction from such a thorough analysis of a design* 153 i TRINITY CONSULTANTS, INC purpo se study hazards can other cases special studies may be necessary to solutions. In some develop D. Risk Analysis distinguish and societal risk, individual Risk" is defined as the risk to an individual of an "Societal Risk" is the risk to society of an event in terms of number of fatalities. Thus, individual risk varies from place to place depending on where the person happens to be at the time of a major accident. The societal risk is a measure of a combination of the likelihood and severity of a single event. Risk is a quantified by three factors: a. Accident frequency or probability b. Accident severity c. Exposure - the measure of the opportunity to be involved with an accident. 1. Analyzing Risk Once hazards are identified it becomes relatively simple to assess probabilities. Consider, for example, a plant with 200 meters of piping. The risk of failure of pipe is 3*10E-7 per meter per year. Thus, the likelihood of failure for the network is A 154 TRINITY CONSULTANTS, INC. VAB.0001093916 200 * 3 * 10E-7 - 6 * 10E-5 per year Assume that valves exist to limit the quantity released but there is 1 in 100 chance that they will fail to work* The total risk of a large failure is: 6 * 10E-5 * 10E-2 - 6 * 10E-7 There is also a risk of release of smaller quantities of gas between the values of 0.99 * 6 * 10E-5 - 6 * 10E-5 If the gas is flammable, the risk of release can be multiplied by the probability that ignition will occur before the released gases are diluted below the lower favorable limit. Finally, meteorological and population / location data is used to assess the probability of a gas release affecting nearby residents. Statistical data is available to assess the probability of many other events. Some of the probabilities used in the second Canvey report include: Rupture of refinery process vessels from all modes Railroad tank car derailment and puncture Probability of fire after LPG car puncture Aircraft crash into process area of a refinery The Canvey report provides an ext 4.4 * 10E-5 per year 10E-8 per km 0.73 per event 5 * 10E-6 per year 155 TRINITY CONSULTANTS. INC ship loading and unloading accidents The final result of this work was a series of tables that by the second report had assessed the average individual risk at 35 * 10E-6 per year for residents living near the Canvey complex* There was also a one in a thousand risk that ten or more lives would be lost in an incident each year* By way of reference the individual risk of death from motor vehicle accidents in Great Britain is 130 * 10E-6 and all other accidents about 190 * 10E-6. Needless to say, it is expensive and time consuming to prepare a detailed plan for a plant or for a large complex* A London-based consultant, Technica, Ltd*, completed a traditional study in 1981 for selected areas near Rotterdam for the Rijnmond Authority* They then developed a user-friendly computer program for risk analysis of process plants called "SAFETI".8 The code sells for about $70,000, but it is available from timesharing vendors. The user will typically be trained for about a week and spend an added one or two days collecting data for each process unit such as a group of storage vessels, chlorine plant cell room, or cracking furnace section* 156 TRINITY CONSULTANTS, INC VTsH >3918 A plant data file is created by an interactive program which prompts the analyst in a logical sequence* Other data needed includes the distribution of population by location, the distribution of ignition sources and meteorological data* The output consists of individual risk contour plots which are overlaid on a map of the area and so called F-N plots* The frequency of an event (F) is plotted against the number of fatalities (N) for societal risk in a log-log presentation* 3* Value of Risk Analysis There are many uncertainties involved in any HAZOP and risk analysis survey* First, it is difficult to speculate on all the possible operator errors that could occur* Even if a reasonable method of assessing risk is completed, there is still a great deal of uncertainty as to the consequences given the rather inaccurate nature of dispersion modeling, the number of people that will be affected, the response of individuals to acutely toxic doses and whether the people affected will be outdoors or in buildings with varying ventilation rates* Perhaps the best that can be accomplished is to use risk assessment to evaluate relative risks* The iteration of tI \in i 157 TRINITY CONSULTANTS, INCvtaeoatlumm ' 1. Health end Safety Commission "Advisory Committee on Major Hazards -- Second Report" (1979) Her Majesty's Stationery Office, London p. 10-16 2. Simmons, John A., Erdmann, Robert C. and Naft, Barry 7, "Risk Assessment of Large Spills of Toxic Materials", 1974 Hazardous Materials Conference p. 166-175. 3. Health and Safety Executive, CANVEY: An Investigation of Potential Hazards from Operations in the Canvey Island/Thurrock area." (1978) Her Majesty's Stationery Office, London. 4. Health and Safety Executive, "CANVEY: A Second Report. A Review of Potential Hazards from Operations in the Canvey Islsnd/Thurrock Area Three Tears After Publication of the Canvey Report" (1981) Her Majesty's Stationery Office, London. Chemical Industry Safety & Health Council the Chemical Industries Association Limited Guide Hazard and Operability Studies" (1977) hemical Industries Association (CIA) Albert Embankment. London SE1 Second CANVEY Report (1981) p. 70. Technica, Ltd., "SAPETI - Report on A Computer Based System Assessment of a Chemical Plant Using a Simplified Classical (1984). London. /fj M6asJbr ?T*4 1 159 TRINITY CONSULTANTS. INC. 093921 A. Implementation Schedule for S.I. 1984/1902, "The Control of Industrial Maj:r Accident Hazards Regulations". B. Tabulation of Pasc/oil 1-Gifford dispersion coefficients for various downwind distance C. Petersen, William B., "Estimating Concentrations Downwind from an Instantaneous Puff Release", (August 1982) U.S. Environmental Protection Agency, Research Triangle Park, NC 27711 (EPA 600/3-S2-078 or PB 82-261959). D. Wei, E. T., "Report for Trinity Consultants (on Arsine)", list! E. "World Bank and 112 Guidelines for Indentifying, Analyzing and Controlling Majcr Hazard Installations in Developing Counties" (Draft-February 1935) World Bank, Washington, DC. TRINITY CONSULTANTS, INC. VAR0001093922 A MANUFACTURER'S GUIDE TO THE CIMAH REGULATIONS FIGURE .a $6 .2 s f I 5 = S I?3 K-" a^c 5s *{ ni <C =-J2J-t 2 a * 093923 RURAL VERTICAL DISPERSION COEFFICIENTS (METERS) DOWNWIND DIST (KM) 0. 010 0. 020 0. 030 0. 040 0. 050 0. 060 0. 070 0. 080 0. 090 0. 100 0. 110 0. 120 0. 130 0. 140 0. 150 0. 160 0. 170 0. 180 0. 190 0. 200 0. 210 0. 220 0. 230 0. 240 0. 250 0. 260 0. 270 0. 280 0. 290 0. 300 0. 310 0. 320 0. 330 0. 340 0. 350 0. 360 0. 370 0. 380 0. 390 0. 400 0. 410 0. 420 0. 430 0. 440 0. 450 0. 460 0. 470 0. 480 0. 490 0. 500 ------------------------------ AB 1. 58 1. 24 3. 05 2. 37 4. 47 3. 45 5. 87 4. 51 7. 25 5. 56 8. 61 6. 59 9. 96 7. 61 11.30 8. 61 12. 63 9. 61 13. 95 10. 60 15. 43 11. 59 16. 91 12. 57 18. 40 13. 54 19. 89 14. 51 21. 40 15. 47 22. 96 16. 43 24. 53 17. 39 26. 11 18. 34 27. 70 19. 29 29. 30 20. 23 30. 96 21. 23 32. 62 22. 22 34. 30 23. 21 35. 98 24. 21 37. 67 25. 20 39. 59 26. 19 41. 52 27. 18 43. 48 28. 17 45. 45 29. 16 47. 44 30. 14 49. 69. 31. 13 51. 96 32. 12 54. 26 33. 11 56. 60 34. 09 58. 96 35. 08 61.34 36. 06 63. 76 37. 05 66. 20 38. 03 68. 67 39. 02 71. 16 40. 00 74. 27 41. 10 77. 42 42. 20 80. 64 43. 30 83. 91 44. 41 87. 23 45. 52 90. 61 46. 63 94. 04 47. 74 97. 52 48. 86 101. 06 49. 97 104. 65 51. 09 STABILITY CD 0. 91 0. 63 1. 71 1. 15 2. 47 1. 63 3. 22 2. 10 3. 95 2. 55 4. 66 2. 98 5. 37 3. 41 6. 07 3. 83 6. 76 4. 24 7. 44 4. 65 8. 12 5. 05 8. 79 5. 45 9. 46 5. 84 10. 12 6. 23 10. 78 6. 62 11. 44 7. 00 12. 09 7. 38 12. 74 7. 76 13. 39 8. 13 14. 03 8. 50 14. 67 8. 87 15. 31 9. 23 15. 94 9. 60 16. 57 9. 96 17. 21 10. 32 17. 83 10. 68 18. 46 11. 03 19. 08 * 19. 71 11.39 11.74 20. 33 12. 09 20. 95 12. 42 21. 56 12. 74 22. 18 13. 06 22. 79 13. 38 23. 41 13. 70 24. 02 14. 02 24. 63 14. 33 25. 23 14. 65 25. 84 14. 96 26. 45 15. 27 27. 05 15. 58 27. 65 15. 89 28. 25 16. 19 28. 85 16. 50 29. 45 16. 80 30. 05 17. 10 30. 65 17. 40 31. 24 17. 70 31. 84 18. 00 32. 43 18. 30 E 0. 51 0. 92 1. 29 1. 64 1. 98 2. 31 2. 62 2. 93 3. 24 3. 53 3. 82 4. 10 4. 38 4. 66 4. 93 5. 20 5. 46 5. 72 5. 98 6. 24 6. 49 6. 75 7. 00 7. 24 7. 49 7. 74 7. 98 8. 22 8. 46 8. 70 8. 92 9. 13 9. 35 9. 56 9. 77 9. 98 10. 19 10. 40 10. 61 10. 81 11. 02 11. 22 11. 42 11. 62 11. 82 12. 02 12. 22 12. 41 12. 61 12. 80 P 0. 36 0. 63 0. 87 1. 10 1. 32 1. 33 1. 74 1. 94 2. 13 2. 33 2. 51 2. 70 2. 88 3. 06 3. 41 3. 58 3. 76 3. 93 4. 09 4. 25 4. 41 4. 57 4. 72 4. 88 5. 03 5. 18 5. 33 5. 48 5. 62 5. 77 5. 92 6. 06 6. 20 6. 35 6. 49 6. 63 6. 77 6. 91 7. 05 7. 19 7. 32 7. 46 7. 59 7. 73 7. 86 a. oo 8. 13 8. 26 8. 40 RURAL VERTICAL DISPERSION COEFFICIENTS (METERS> DOWNWIND DIST (KM) 0. 510 0. 520 0. 530 0. 540 0. 550 0. 560 0. 570 0. 580 0. 590 0. 600 0. 610 0. 620 0. 630 0. 640 0. 650 0. 660 0. 670 0. 680 0. 690 0. 700 0. 710 0. 720 0. 730 0. 740 0. 750 0. 760 0. 770 0. 780 0. 790 0. 800 0. 810 0. 820 0. 830 0. 840 0. 850 0. 860 0. 870 0. 880 0. 890 0. 900 0. 910 0. 920 0. 930 0. 940 0. 950 0. 960 0. 970 0. 980 0. 990 1. 000 A 109. 13 113. 71 118. 39 123. 17 128. 05 133. 02 138. 10 143. 28 148. 56 153. 94 159. 42 165. 00 170. 69 176. 47 182. 36 188. 35 194. 44 200. 63 206. 93 213. 33 219. 83 226. 43 233. 14 239. 95 246. 87 253. 89 261. 01 268. 24 275. 57 283. 00 290. 54 298. 19 305. 94 313. 79 321. 75 329. 82 337. 99 346. 26 354. 64 363.13 371. 72 380. 42 389. 23 398. 14 407. 16 416. 28 425.51 434. 85 444. 30 453. 85 STABILITY 8CD 52. 22 33. 03 18. 59 53. 34 33. 62 18. 89 54. 47 34. 21 19. 18 55. 59 34. 80 19. 47 56. 72 35. 39 19. 77 57. 86 35. 98 20. 06 58. 99 36. 56 20. 35 60. 13 37. 15 20. 64 61. 27 37. 73 20. 92 62. 41 38. 32 21. 21 63. 55 38. 90 21. 50 64. 69 39. 49 21. 78 65. 84 40. 07 22. 07 66. 99 40. 65 22. 35 68. 13 41. 23 22. 63 69. 29 41. 81 22. 92 70. 44 42. 39 23. 20 71. 59 42. 97 23. 48 72. 75 43. 54 23. 76 73. 91 44. 12 24. 03 75. 06 44. 70 24. 31 76. 23 45. 27 24. 59 77. 39 45. 85 24. 87 78. 55 46. 42 25. 14 79. 72 47. 00 25. 42 80. 88 47. 57 25. 69 82. 05 48. 14 25. 97 83. 22 48. 71 26. 24 84. 39 49. 28 26. 51 85. 57 49. 85 26. 78 86. 74 50. 42 27. 05 87. 92 50. 99 27. 32 89. 09 51. 56 27. 59 90. 27 52. 13 27. 86 91. 45 52. 70 28. 13 92. 63 53. 26 28. 40 93. 81 53. 83 28. 67 95. 00 54. 39 28. 93 96. 18 54. 96 29. 20 97. 37 55. 52 29. 47 98. 56 56. 09 29. 73 99. 75 56. 65 30. 00 100. 94 57. 21 30. 26 102. 13 57. 78 30. 52 103. 32 58. 34 30. 79 104. 51 58. 90 31.05 105. 71 59. 46 31. 31 106. 90 60. 02 31. 57 108. 10 60. 58 31. 83 109. 30 61. 14 32. 09 E 12. 99 13. 19 13. 38 13. 57 13. 76 13. 95 14. 14 14. 32 14. 51 14. 69 14. 88 15. 06 15. 25 15. 43 15. 61 15. 79 15. 97 16. 15 16. 33 16. 51 16. 69 16. 87 17. 05 17. 22 17. 40 17. 57 17. 75 17. 92 18. 10 18. 27 18. 44 18. 61 18. 78 18. 96 19. 13 19. 30 19. 47 19. 63 19. 80 19. 97 20. 14 20. 31 20. 47 20. 64 20. 80 20. 97 21. 14 21. 30 21. 46 21. 63 F 8. 53 6. 66 8. 79 8. 92 9. 05 9. 18 9. 30 9. 43 9. 56 9. 69 9. 81 9. 94 10. 06 10. 19 10. 31 10. 44 10. 56 10. 68 10. 81 10. 93 11. 04 11. 14 11. 25 11. 35 11. 46 11. 56 11. 67 11. 77 11. 87 11. 98 12. 08 12. 18 12. 28 12. 38 12. 48 12. 58 12. 68 12. 78 12. 88 12. 98 13. 08 13. 18 13. 28 13. 37 13. 47 13. 57 13. 67 13. 76 13. 86 13. 95 RURAL VERTICAL DISPERSION COEFFICIENTS (METERS) DOWNWIND ------------------------------ STABILITY DIST (KM) A B 0 D 1. 050 503. 22 115. 31 63. 93 33. 12 1. 100 555.30 121. 35 66. 71 34. 12 1. 150 1. 200 610. 08 127. 41 667. 59 133. 50 69. 48 72 24 35. 12 36. 09 1. 250 727. 83 139. 62 74. 98 37. 05 1. 300 790.83 145. 76 77. 72 38. 00 1. 350 856. 60 151. 92 80. 45 38. 94 1. 400 925. 14 158. 10 83. 17 39. 86 1. 450 996. 47 164. 31 85. 89 40. 77 1. 500 1070. 60 170.53 88. 59 41. 67 1. 550 1147. 54 176. 78 91. 29 42. 56 1. 600 1227. 31 183. 05 93. 98 43. 44 1. 650 1309. 90 189. 33 96. 66 44. 31 1. 700 1395. 34 195. 63 99. 34 45. 17 1. 750 1483. 63 201. 96 102. 01 46. 02 1. 800 1574. 79 208. 30 104. 67 46. 86 1. 850 1668. 82 214. 65 107. 33 47. 70 1. 900 1765. 72 221. 02 109. 98 48. 52 1. 950 1865. 52 227. 41 112. 62 49. 34 2. 000 1968. 22 233. 82 115. 26 50. 15 2. 050 2073. 82 240. 24 117. 89 50. 96 2. 100 2182. 34 246. 68 120. 52 51. 75 2. 150 2293. 78 253.13 123. 14 52. 54 2. 200 2408. 15 259. 59 125. 76 53. 33 2. 250 2525. 47 266. 07 128. 37 54. 10 2. 300 2645. 73 272. 57 130. 97 54. 87 2. 350 2768. 95 279. 07 133. 58 55. 64 2. 400 2895. 13 285. 59 136. 17 56. 40 2. 450 3024. 28 292. 13 138. 77 57. 15 2. 500 3156. 40 298.68 141. 35 57. 90 2. 550 3291. 51 305. 24 143. 94 58. 65 2. 600 3429. 61 311. 81 146. 52 59. 38 2. 650 3570. 71 318. 39 149. 09 60. 12 2. 700 3714. 81 324. 99 151. 66 60. 84 2. 750 3861. 93 331. 60 154. 23 61. 57 2. 800 4012. 06 338. 22 156.79 62. 29 2. 850 4165. 21 344. 85 159. 35 63. 00 2. 900 4321. 39 351. 49 161. 91 63. 71 2. 950 4480. 62 358. 15 164. 46 64. 42 3. 000 4642. 88 364. 81 167. 01 65. 12 3. 050 4808. 19 371. 49 169. 55 65. 77 3. 100 4976. 55 378. 18 172. 09 66. 42 3. 150 5000. 00 384. 87 174. 63 67. 07 3. 200 5000. 00 391. 58 177. 16 67. 71 3. 250 5000. 00 398. 30 179. 69 68. 35 3. 300 5000. 00 405. 03 182. 22 68. 98 3. 350 5000. 00 411. 76 184. 74 69. 61 3. 400 5000. 00 418. 51 187. 26 70. 24 3. 450 5000. 00 425. 27 189. 78 70. 86 3. 500 5000. 00 432. 03 192. 29 71. 48 E 22. 30 22. 97 23. 62 24. 26 24. 90 25. 52 26. 14 26. 74 27. 34 27. 93 28. 51 29. 09 29. 66 30. 23 30. 78 31.34 31. 88 32. 42 32. 96 33. 49 33. 96 34. 43 34. 90 35. 36 35. 82 36. 27 36. 72 37. 17 37. 61 38. 04 38. 48 38. 91 39. 33 39. 75 40. 17 40. 59 41. OO 41. 41 41. 82 42. 22 42. 62 43. 02 43. 42 43. 81 44. 20 44. 59 44. 97 45. 35 45. 73 46. 11 F 14. 39 14. 82 15. 24 15. 66 16. 07 16. 47 16. 87 17. 26 17. 65 18. 03 18. 41 18. 78 19. 15 19. 52 19. 88 20. 23 20. 59 20. 94 21. 28 21. 63 21. 92 22. 21 22. 50 22. 78 23. 06 23. 34 23. 61 23. 89 24. 16 24. 42 24. 69 24. 95 25. 21 25. 47 25. 73 25. 98 26. 23 26. 48 26. 73 26. 98 27. 18 27. 39 27. 60 27. 80 28. OO 28. 20 28. 40 28. 59 28. 79 28. 98 RURAL VERTICAL DISPERSION COEFFICIENTS <METERS) rrrrt DOMNWINO STABILITY DIST (KM> A B C D F 3. 550 5000. 00 438. 81 194. 80 72. 10 46. 49 29. 17 3. 600 5000. 00 445. 59 197. 31 72. 71 46. 86 29. 36 mi 3. 650 5000. 00 452. 39 199. 82 73. 32 47. 23 29. 55 3. 700 5000. 00 459. 19 202. 32 73. 92 47. 60 29. 74 3. 750 5000. 00 466. 00 204. 82 74. 53 47. 96 29. 92 3. 800 5000. 00 472. 83 207. 32 75. 13 48. 33 30. 11 3. 850 5000. 00 479. 66 209. 81 75. 72 48. 69 30. 29 3. 900 5000. 00 486. 49 212. 30 76. 31 49. 05 30. 48 3. 950 5000. 00 493. 34 214. 79 76. 90 49. 41 30. 66 4. 000 5000. 00 500. 20 217. 27 77. 49 49. 77 30. 84 4. 050 5000. 00 507. 06 219. 76 78. 08 SO. 08 31. 02 4. 100 5000. 00 513. 93 222. 24 78. 66 50. 39 31. 19 4. 150 5000. 00 520. 81 224. 71 79. 24 50. 70 31. 37 4. 200 5000. 00 527. 70 227. 19 79. 81 51. 01 31. 54 4. 250 5000. 00 534. 60 229. 66 80. 39 51. 32 31. 72 4. 300 5000. 00 541. 50 232. 13 80. 96 51. 62 31. 89 4. 350 5000. 00 548. 41 234. 60 81. 53 51. 92 32* 0^ 4. 400 5000. OO 555. 33 237. 06 82. 09 52. 22 32. 23 4. 450 5000. 00 562. 26 239. 53 82. 65 52. 52 32. 40 4. 500 5000. 00 569. 19 241. 99 83. 21 52. 82 32. 57 4. 550 5000. 00 576. 14 244. 45 4. 600 5000. 00 583. 09 246. 90 83. 77 84. 33 53. 12 S3. 41 32. 74 32 91 4. 650 5000. 00 590. 04 249. 36 84. 88 53. 70 33. 07 4. 700 5000. 00 597. 01 251. 81 85. 43 53. 99 33. 24 4. 750 5000. 00 603. 98 254. 26 4. 800 5000. 00 610. 96 256. 70 85. 98 86. 53 5g44. 2587 33. 40 33. 56 4. 850 5000. 00 617. 94 259. 15 87. 07 54. 86 33. 73 4. 900 5000. 00 624. 93 261. 59 87. 61 55. 14 33. 89 4. 950 5000. 00 631* 73 264. 03 88. IS 55. 43 34. 05 5. 000 5000. 00 638.94 266. 47 88. 69 55. 71 34. 21 5. 500 5000. 00 709. 37 290. 74 93. 95 58. 46 35. 76 6. 000 5000. 00 780. 42 314. 82 99. 03 61. 08 37. 23 6. 500 5000. 00 852. 05 338. 74 103. 94 63. 60 38. 64 7. 000 5000. 00 924. 22 362. 49 108.71 66. 03 40. 00 7. 500 5000. 00 996. 90 386. 11 113. 34 68. 37 41. 16 8. 000 5000. 00 1070. 04 409. 58 117. 85 70. 64 42. 28 8. 500 5000. 00 1143. 63 432. 94 122. 25 72. 84 43. 36 9. 000 5000. OO 1217. 64 456. 17 126. 56 74. 97 44. 40 9. 500 5000. 00 1292. 05 479. 30 130.76 77. 05 45. 41 10. 000 5000. 00 1366. 85 502. 32 134. 89 79. 07 46. 38 10. 500 5000. 00 1442. 01 525. 25 138. 66 80. 89 47. 33 11. 000 5000. 00 1517. 51 548. 08 142. 36 82. 67 48. 26 11. 500 5000. 00 1593. 35 570. 82 145. 99 84. 40 49. 15 12. 000 5000. 00 1669. 51 593. 48 149.54 86. 10 50. 03 12. 500 5000. 00 1745. 98 616. 06 153.04 87. 76 50. 89 13. 000 5000. 00 1822. 75 638. 56 156.47 89. 38 51. 72 13. 500 5000. 00 1899. 81 660. 99 159.85 90. 97 52. 54 14. 000 5000. 00 1977. 14 683. 34 163.18 92. 53 53. 34 14. 500 5000. OO 2054. 74 705. 63 166. 45 94. 06 54. 12 ***** 15. 000 5000. 00 2132. 60 727. 85 169. 67 95. 56 54. 88 H.4 * VAB.0001093927  RURAL VERTICAL DISPERSION COEFFICIENTS (METERS) ft*** .tt DOWNWIND STABILITY DIST <KM> A B C D E F 15. 500 5000. OO 2210. 72 750. 01 172.85 97. 03 55. 48 16.000 5000. 00 2289. 08 772. 11 175. 98 98. 48 56. 05 16.500 5000. 00 2367. 68 794. 15 179. 08 99. 91 56. 62 17. 000 5000. 00 2446. 50 816.14 182. 13 101. 31 57. 18 17. 500 5000. 00 2525. 56 838. 06 185. 14 102. 69 57. 72 18.000 5000. 00 2604. 84 859. 94 188. 11 104. 05 58. 25 18.500 5000. 00 2684. 32 881.76 191. 05 105. 39 58. 78 -W 19. 000 5000. 00 2764. 02 903. 53 193. 96 106. 71 59. 29 19. 500 5000. 00 2843. 92 925. 26 196. 83 108. 02 59. 80 20. 000 5000. 00 2924. 02 946. 93 199. 67 109. 30 60. 29 21. 000 5000. 00 3084. 80 990. 15 205. 26 111. 33 61. 26 22. 000 5000.00 3246. 33 1033. 19 210. 74 113. 29 62. 20 23. 000 5000. 00 3408. 57 1076. 06 216. 10 115. 20 63. 11 24. 000 5000. 00 3571. 50 1118.78 221. 37 117.06 64. 00 25. 000 5000. 00 3735. 09 1161. 34 226.54 118. 87 64. 86 26. 000 5000. 00 3899. 31 1203. 76 231. 63 120. 64 65. 69 27. 000 5000. 00 4064. 15 1246.03 236. 63 122. 36 66. 51 28.000 5000. 00 4229. 59 1288. 18 241. 55 124. 05 67. 30 29. 000 5000. 00 4395. 59 1330. 19 246. 39 125. 70 68. 08 30. 000 5000. 00 4562. 16 1372. 09 251. 16 127. 31 68. 84 31. 000 5000. 00 4729. 26 1413. 86 255. 41 128. 89 69. 46 32. 000 5000. 00 4896. 89 1455. 52 259. 59 130. 44 70. 07 33. 000 5000. 00 5000. 00 1497. 07 263. 72 131. 96 70. 66 34. 000 5000. 00 5000. 00 1538. 51 267. 78 133.45 71. 24 35. 000 5000. 00 5000. 00 1579. 85 271. 78 134.91 71. 81 36. 000 5000. 00 5000. 00 1621. 08 275. 72 136. 35 72. 37 37.000 5000. OO 5000. 00 1662. 22 279. 62 137. 76 72. 91 38.000 5000. 00 5000. 00 1703. 26 283. 46 139. 15 73. 45 39. 000 5000. OO 5000. 00 1744. 21 287. 25 140. 52 73. 97 40. 000 5000. 00 5000. 00 1785. 08 291. 00 141.86 74. 49 41. 000 5000. OO 5000. 00 1825. 85 294.70 142. 90 75. 00 42. 000 5000. 00 5000. 00 1866. 54 298. 36 143. 92 75. 49 43. 000 5000. 00 5000. 00 1907. 15 301. 97 144. 93 75. 98 44. 000 5000. 00 5000. 00 1947. 68 305. 55 145. 92 76. 46 45. 000 5000. 00 5000. 00 1988. 12 309. 08 146.89 76. 94 46. 000 5000. 00 5000. 00 2028. 50 312. 58 147. 85 77. 40 47. 000 5000. 00 5000. 00 2068. 79 316. 04 148. 79 77. 86 48.000 5000. 00 5000. 00 2109. 02 319. 46 149. 72 78. 31 49. 000 5000. 00 5000. 00 2149. 17 322. 85 150. 64 78. 75 50. 000 5000. 00 5000. 00 2189.25 326.21 151. 54 79. 19 H. 5 * VAB.0001093928 RURAL HORIZONTAL DISPERSION COEFFICIENTS (METERS) numuwintiiwiTirkaiun CTA13 T1 T TV _. DIST (KM) 6 B C D E 0. 010 3. 36 2. 34 1. 47 0. 96 0. 72 0. 020 6.29 4. 42 2. 80 1. 84 1. 37 0. 030 9. 08 6. 41 4. 08 2. 68 2. 00 0. 040 n. 77 8. 34 5. 33 3. 50 2. 61 0. 050 14. 39 10. 23 6. 56 4. 31 3. 22 0. 060 16. 96 12. 09 7. 77 5. 11 3. 81 0. 070 19. 49 13. 92 8. 96 5. 89 4. 40 0. 080 21. 98 15. 72 10. 14 6. 67 4. 98 0. 090 24. 43 17. 50 11. 31 7. 44 5. 55 0. 100 26. 85 19. 27 12. 46 8. 20 6. 12 0. 110 29. 25 21. 01 13. 61 8. 96 6. 69 0. 120 31.63 22. 74 14. 75 9. 71 7. 25 0. 130 33. 98 24. 46 15. 88 10. 46 7. 81 0. 140 36. 31 26. 16 17. 00 11. 20 8. 36 0. 150 38. 63 27. 86 18. 12 11. 93 8. 91 0. 160 40. 93 29. 54 19. 23 12. 67 9. 46 0. 170 43. 21 31. 21 20. 34 13. 40 10. 01 0. 180 45. 48 32. 87 21. 44 14. 12 10. 55 0. 190 47. 73 34. 52 22. 53 14. 84 11. 09 0. 200 49. 97 36. 17 23. 62 15. 56 11. 63 0. 210 52. 20 37. 80 24. 71 16. 28 12. 16 0. 220 54. 41 39. 43 25. 79 16. 99 12. 69 0. 230 56. 62 41. 05 26. 86 17. 70 13. 23 0. 240 58. 81 42. 66 27. 93 18. 41 13. 76 0. 250 60. 99 44. 27 29. 00 19. 12 14. 28 0. 260 63. 17 45. 87 30. 07 19. 82 14. 81 0. 270 65. 33 47. 46 31. 13 20. 52 15. 33 0. 280 67. 48 49. 05 32. 19 21. 22 15. 85 0. 290 69. 63 50. 63 33. 24 21. 92 16. 38 0. 300 71. 76 52. 20 34. 29 22. 61 16. 89 0. 310 73. 89 53. 77 35. 34 23. 30 17. 41 0. 320 76. 01 55. 34 36. 38 23. 99 17. 93 0. 330 78. 12 56. 90 37. 43 24. 68 18. 44 0. 340 80. 23 58. 45 38. 47 25. 37 18. 96 0. 350 82. 33 60. 00 39. 50 26. 05 19. 47 0. 360 84. 42 61. 55 40. 54 26. 74 19. 98 0. 370 86. 50 63. 09 41. 57 27. 42 20. 49 0. 380 88. 58 64. 62 42. 60 28. 10 21. 00 0. 390 90. 65 66. 15 43* 62 28. 78 21. 51 0. 400 92. 71 67. 68 44. 65 29. 46 22. 01 0. 410 94. 77 69. 21 45. 67 30. 13 22. 52 0. 420 96. 82 70. 73 46. 69 30. 80 23. 02 0. 430 98. 87 72. 24 47. 71 31. 48 23. 52 0. 440 100. 91 73. 75 48. 72 32. 15 24. 03 0. 450 102. 94 75. 26 49. 74 32. 82 24. 53 0. 460 104. 97 76. 77 50. 75 33. 49 25. 03 0. 470 107. 00 78. 27 51. 76 34. 15 25. 52 0. 480 109.02 79. 77 52. 76 34. 82 26. 02 0. 490 111.03 81. 26 53. 77 35. 48 26. 52 0. 500 113.04 82. 75 54. 77 36. 15 27. 02 F 0. 48 0. 91 1. 33 1. 74 2. 14 2. 53 2. 92 3. 31 3. 69 4. 07 4. 45 4. 82 5. 19 5. 56 5. 92 6. 29 6. 65 7. 01 7. 37 7. 73 8. 08 8. 44 8. 79 9. 14 9. 50 9. 84 10. 19 10. 54 10. 89 11. 23 11. 58 11. 92 12. 26 12. 60 12. 95 13. 29 13. 62 13. 96 14. 30 14. 64 14. 97 15. 31 15. 64 15. 98 16. 31 16. 64 16. 97 17. 31 17. 64 17. 97 ( Am; RURAL HORIZONTAL DISPERSION COEFFICIENTS (METERS) INWIND STABILITY >t (km) A B C D? E F 0. 510 115. 04 84. 24 55. 77 36. 81 27. 51 18. 30 0. 520 117. 04 85. 72 56. 77 37. 47 28. 01 18. 62 0. 530 119. 04 87. 21 57. 77 33* 13 28. 50 18. 95 0. 540 121. 03 88. 69 58. 77 38. 79 28. 99 19. 28 0. 550 123. 01 90. 16 59. 76 39. 45 29. 48 19. 61 0. 560 124. 99 91. 63 60. 75 40. 10 29. 97 19. 93 0. 570 126. 97 93. 10 61. 74 40. 76 30. 46 20. 26 0. 580 128. 94 94. 57 62. 73 41. 41 30. 95 20. 59 0. 590 130. 91 96. 03 63. 72 42. 07 31. 44 20. 91 0. 600 132. 88 97. 50 64. 71 42. 72 31. 93 21. 24 0. 610 134. 84 98. 95 65. 69 43. 37 32. 42 21. 56 0. 620 136. 79 100. 41 66. 68 44. 02 32. 90 21. 88 0. 630 138. 75 101. 86 67. 66 44. 67 33. 39 22. 21 0. 640 140. 69 103. 32 68. 64 45. 32 33. 88 22. 53 0. 650 142. 64 104. 76 69. 62 45. 97 34. 36 22. 85 0. 660 144. 58 106. 21 70. 60 46. 61 34. 84 23. 17 0. 670 146. 52 107. 65 71. 57 47. 26 35. 33 23. 50 0. 660 148.45 109. 09 72. 55 47. 90 35. 81 23. 82 tstttt 0. 690 150. 38 110. 53 73. 52 48. 55 36. 29 24. 14 0. 700 0. 710 0. 720 152. 31 154. 23 156. 15 111. 97 113. 40 114. 84 74. 49 75. 46 76. 43 49. 19 49. 83 50. 47 36. 77 37. 25 37. 73 . 24. 46 24. 78 25. 10 0. 730 0. 740 158. 07 116.27 159. 98 117. 69 77. 40 78. 37 51. 11 51. 75 38. 21 38. 69 25. 41 25. 73 0. 750 0. 760 0. 770 0. 780 0. 790 0. 800 0. 810 0. 820 0. 830 0. 840 0. 850 0. 860 0. 870 0. 880 0. 890 0. 900 0. 910 0. 920 0. 930 0. 940 0. 950 0. 960 0. 970 0. 980 0. 990 l. 000 161. 89 163. 80 165. 70 167. 61 169. 50 171. 40 173. 29 175. 18 177. 06 178. 95 180. 83 182. 70 184. 58 186.45 188. 32 190. 19 192. 05 193. 91 195. 77 197. 63 199. 48 201. 33 203. 18 205. 02 206. 87 208. 71 119. 12 120. 54 121. 96 123. 38 124. 80 126. 21 127. 63 129. 04 130. 45 131. 85 133. 26 134. 66 136. 06 137. 46 138. 86 140. 26 141. 65 143. 04 144. 43 145. 82 147. 21 148. 59 149. 98 151. 36 152. 74 154. 12 79. 33 80. 30 81. 26 82. 22 83. 18 84. 14 85. 10 86. 06 87. 02 87. 97 88. 92 89. 88 90. 83 91. 78 92. 73 93. 68 94. 63 95. 57 96. 52 97. 46 98. 41 99. 35 100.29 101. 23 102. 17 103. 11 52. 39 53. 03 53. 67 54. 30 54. 94 55. 58 56. 21 56. 84 57. 48 58. 11 58. 74 59. 37 60. 00 60. 63 61 * 26 61. 89 62. 51 63. 14 63. 77 64. 39 65. 02 65. 64 66. 26 66. 89 67. 51 68. 13 39. 17 39. 64 40. 12 40. 60 41. 07 41. 55 42. 02 42. 50 42. 97 43. 44 43. 91 44. 39 44. 86 45. 33 45. 80 46. 27 46. 74 47. 21 47. 67 48. 14 48. 61 49. 08 49. 54 50. 01 50. 47 50. 94 26. 05 26. 37 26. 69 27. 00 27. 32 27. 63 27. 95 28. 27 28. 58 28. 90 29. 21 29. 52 29. 84 30. 15 30. 46 30. 78 31. 09 31. 40 31. 71 32. 02 32. 33 32. 64 32. 95 33. 26 33. 57 33. 88 H. 7 A VAB.0001093930 J RURAL HORIZONTAL DISPERSION COEFFICIENTS (METERS) DOUINW1 NO STABILITY------------- DIST (KM) A B C D 'E F A\V MM** 1. 030 217. 88 160. 99 107. 80 71. 23 S3. 26 35. 43 1. 100 227. 00 167. 82 112. 46 74. 31 55. 56 36. 96 1. 150 236. 06 174. 62 117. 10 77. 38 57. 86 38. 49 .VWft 1. 200 245. 07 181. 38 121. 71 80. 44 60. 15 40. 01 1. 250 254. 03 188. 11 126. 32 83. 49 62. 43 41. 53 1. 300 262. 94 194. 81 130. 90 86. 52 64. 70 43. 04 w.*w 1. 350 271.81 201. 48 135. 46 89. 54 66. 96 44. 55 1. 400 280. 63 208. 11 140. 01 92. 56 69. 21 46. 05 1. 450 289. 41 214. 72 144. 54 95. 56 71. 46 47. 54 1. 500 298. 16 221. 31 149. 06 98. 55 73. 70 49. 03 1. 550 306. 86 227. 86 153. 56 101. 53 75. 93 50. 51 *** 1. 600 1. 630 315. 52 234. 39 158. 04 104.50 324. 15 240. 90 162. 51 107. 46 78. 15 80. 37 51. 99 53. 47 1. 700 332. 75 247. 38 166. 97 110.41 82. 57 54. 94 1. 750 341. 31 253. 83 171. 41 113.35 84. 78 56. 41 * 1. 800 349. 83 260. 27 175. 85 116. 29 86. 97 57. 87 1. 850 358. 33 266. 68 180.26 119. 22 89. 16 59. 33 1. 900 366. 79 273. 08 184. 67 122. 13 91. 35 60. 78 1. 950 375. 22 279.45 189. 06 125. 05 93. 53 62. 23 ' ** 2. 000 383. 62 285. 80 193. 45 127. 95 95. 70 63. 68 I- 2. 050 392. 00 292. 13 197. 82 130.84 97. 87 65. 12 `2. 100 2. 150 400. 34 298. 44 202. 18 133. 73 100. 03 4 408. 66 304. 73 206. 52 136. 61 102. 18 66. 56 67. 99 *4 2. 200 416. 95 311. 01 210. 86 139. 49 104. 33 69. 42 111 2. 250 425. 21 317. 27 215. 19 142. 36 106. 48 70. 85 J 2. 300 433. 45 323. 51 219. 51 145. 22 108. 62 72. 28 2. 350 441. 66 329. 73 223. 82 148. 07 110. 76 73. 70 ***** 2. 400 449. 85 335. 93 228. 11 150. 92 112. 89 75. 12 2. 450 458. 02 342. 12 232. 40 153. 76 115. 02 76. 53 2. 500 466. 16 348. 30 236. 68 156. 60 117. 14 77. 95 *" 2. 550 474. 28 354. 46 240. 95 159. 43 119. 26 79. 36 * 2. 600 482. 37 360. 60 245. 21 162. 25 121. 37 80. 76 2. 650 490. 45 366. 73 249. 47 165. 07 123. 48 82. 17 2. 700 498. 50 372. 84 253. 71 167. 88 125. 59 83. 57 2. 750 506. 53 378. 94 257. 94 170. 69 127. 69 84. 97 2. 800 514. 54 385. 02 262. 17 173. 49 129. 78 86. 36 MM 2. 830 522. 53 391. 09 266. 39 176.29 131. 88 87. 76 2. 900 530. 50 397. 15 270. 60 179. 08 133. 97 89. 15 2. 950 538. 45 403. 19 274. 81 181. 86 136. 05 90. 54 3. 000 546. 38 409. 22 279. 00 184. 65 138. 13 91. 92 3. 050 554. 29 415. 23 283. 19 187.42 140. 21 93. 31 3. 100 562. 18 421. 24 287. 37 190. 19 142. 29 94. 69 i 3. 150 570. 05 427. 23 291. 54 192. 96 144. 36 96. 07 3. 200 577. 91 433. 20 295. 71 195. 72 146. 42 97. 44 w+w * 3. 250 3. 300 3. 350 585. 74 593.56 601.37 439. 17 445. 12 451. 07 299. 87 304. 02 308. 16 198.48 201. 23 203. 98 148. 49 150. 55 152. 60 98. 82 100. 19 101. 56 3. 400 609. 15 457. 00 312. 30 206. 72 154. 66 102. 92 * p 3. 450 616. 92 462. 92 316. 43 209. 46 156. 71 104.29 3. 500 624. 67 468. 82 320. 56 212. 19 158. 75 105. 65 H.8 VAB.0001093931 RURAL HORIZONTAL DISPERSION COEFFICIENTS <METERS> DOWN WIND STABILITY DIST (KM) A B C D E 3. 550 632.41 474.72 324.68 214. 92 160. 80 3. 600 640. 13 480. 61 328. 79 217. 65 162. 84 3. 650 647. 83 486. 48 332. 90 220. 37 164. 88 3. 700 655. 52 492. 34 336. 99 223. 09 166. 91 3. 750 663. 20 498.20 341. 09 225. 81 168. 94 3. 800 670. 85 504. 04 345. 18 228. 52 170. 97 3. 850 678.50 509. 87 349. 26 231. 22 173. 00 3. 900 686.13 515. 70 353. 33 233. 92 175. 02 3. 950 693. 74 521. 51 357. 40 236. 62 177. 04 4. 000 701. 34 527. 31 361. 47 239. 32 179. 06 4. 050 708. 93 533. 11 365. 52 242. 01 181. 07 4. 100 716. 50 538. 89 369.58 244. 69 183. 08 4. 150 724. 05 544. 66 373. 62 247. 38 185. 09 4. 200 731. 60 550. 43 377. 66 250. 06 187. 10 4. 250 739. 13 556. 18 381. 70 252. 74 189. 10 4. 300 746. 65 561. 93 385. 73 255. 41 191. 10 4. 350 754. 15 567. 67 389. 76 258.08 193. 10 4. 400 761. 64 573.39 393.78 260. 74 195. 10 4. 450 769.12 579. 11 397. 79 263. 41 197. 09 4. 500 776. 58 584. 82 401. 80 266. 07 199. 08 4. 550 784. 03 590. 53 405. 81 268. 72 201. 07 4. 600 791. 48 596. 22 409. 81 271. 38 203. 06 4. 650 798. 90 601. 90 413. 80 274. 02 205. 04 4. 700 806. 32 607. 58 417. 79 276. 67 207. 02 4. 750 813. 72 613. 25 421. 78 279. 31. 209. 00 4. 800 821. 11 618. 91 425. 76 281. 95 210. 98 4. 850 828. 49 624. 56 429. 74 284.59 212. 95 4. 900 835. 86 630. 20 433. 71 287. 23 214. 92 4. 950 843. 22 635. 84 437. 67 289. 86 216. 89 5. 000 5. 500 850. 56 641. 47 441. 64 292. 48 218. 86 923. 42 697. 34 481.01 318. 60 238. 42 6. 000 995. 25 752. 50 519. 98 344. 45 257. 77 6. 500 1066. 14 807. 01 558. 57 370. 05 276. 94 7. 000 1136. 17 860. 93 596. 81 395. 43 295. 94 7. 500 1205. 40 914. 30 634. 72 420. 59 314. 78 8. 000 1273. 88 967. 15 672. 34 445. 55 333. 47 8. 500 1341.67 1019. 52 709. 67 470. 32 352. 02 9. 000 1408. 80 1071. 44 746. 74 494. 92 370. 44 9. 500 1475. 32 1122. 92 783. 55 519. 36 388. 74 10. 000 1541. 25 1174. 01 820. 13 543. 64 406. 92 10.500 1606. 63 1224. 71 856.48 567. 77 424. 99 11.OOO 1671.48 1275. 04 892. 62 591. 76 442. 96 11. 500 1735. 83 1325. 02 928. 55 615. 61 460. 82 12.000 1799.70 1374. 67 964. 29 639. 34 478. 59 12.500 1863. 11 1424. 00 999. 84 662.94 496. 27 13. OOO 1926. 08 1473. 02 1035. 20 686. 43 513. 86 13. 500 14. OOO 14. 500 15.OOO 1988. 62 2050. 76 2112. 50 2173. 87 1521. 75 1570. 20 1618. 37 1666. 28 1070. 40 1105. 42 1140. 29 1175. 00 709. 79 733. 05 756. 21 779.26 531. 36 548. 78 566. 12 583. 39 F 107. Oi 108. 37 109. 73 111.08 112. 43 113. 79 115. 13 116. 48 117. 83 119. 17 120. 51 121. 85 123. 19 124. 52 125. 86 127. 19 128. 52 129. 85 131. 18 132. 50 133. 83 135. 15 136. 47 137. 79 139. 11 140. 42 141. 74 143. 05 144. 36 145. 67 158. 69 171. 58 184. 34 196. 99 209. 54 221. 98 234. 34 246. 61 258. 79 270. 90 282. 94 294. 90 306. 80 318. 63 330. 41 342. 12 353. 78 RURAL HORIZONTAL DISPERSION COEFFICIENTS (METERS) DOWNWIND STABILITY DIST (KM) A B C D E F 15.500 2234.87 1713.93 1209.56 802.21 600.58 399.88 16.000 2295.52 1761.33 1243.98 825.06 617.70 411.28 16. 500 2355. 82 1808. 50 1278. 25 847. 03 634. 75 422. 64 17.000 2415.80 1855.44 1312.39 870.50 651.73 433.95 17.500 2475.45 1902.15 1346.40 893.09 668.65 445.22 18. 000 2534. 78 1948. 64 1380. 27 915. 59 685. 50 456. 44 18.500 2593.82 1994.92 1414.03 938.01 702.29 467.63 19.000 2652.56 2041.00 1447.66 960.35 719.03 478.77 19.500 2711.01 2086.87 1481.17 982.61 735.70 489.88 20.000 2769.18 2132.55 1514.57 1004.79 752.32 500.95 21.000 2884.72 2223.34 1581.03 1048.94 785.39 522.98 22. 000 2999. 22 2313. 41 1647. 06 1092. 81 818. 25 544. 86 23.000 3112.73 2402.78 1712.68 1136.41 850.91 566.62 24.000 3225.29 2491.49 1777.91 1179.75 883.38 588.25 25. 000 3336. 95 2579. 57 1842. 77 1222. 84 915. 66 609. 75 26. 000 3447. 74 2667. 04 1907. 27 1265. 70 947. 77 631. 14 27.000 3557.70 2753.93 1971.43 1308.33 979.70 652. 41 28. 000 3666. 85 2840. 25 2035. 24 1350. 73 1011. 47 673. 57 29. 000 3775. 23 2926. 03 2098. 75 1392. 93 1043. 08 694. 63 30.000 3882.87 3011.29 2161.94 1434.92 1074.54 715.59 31.000 3989.78 3096.04 2224.83 1476.72 1105.85 736.45 32.000 4096.00 3180.30 2287.43 1518.32 1137.02 757.21 33. 000 4201. 54 3264. 09 2349. 75 1559. 74 1168. 05 777. 88 34.000 4306.43 3347.42 2411.80 1600.98 1198.95 798.46 35. 000 4410. 68 3430. 31 2473. 59 1642. 05 1229. 72 818. 96 36. 000 4514. 32 3512. 76 2535. 12 1682. 94 1260. 36 839. 37 37.000 4617.36 3594.79 2596.40 1723.67 1290.87 859.70 38. 000 4719. 32 3676. 41 2657. 44 1764. 25 1321. 27 879. 95 39.000 4821.72 3757.64 2718.24 1804.66 1351.55 900.12 40.000 4923.06 3838.48 2778.81 1844.93 1381.72 920.22 41.000 5023.86 3918.94 2839.16 1885.04 1411.78 940.25 42. 000 5124. 14 3999. 03 2899. 29 1925. 01 1441. 73 960. 20 43.000 5223.91 4078.76 2959.21 1964.84 1471.57 980.08 44. 000 5323. 18 4158. 14 3018. 92 2004. 54 1501. 31 999. 89 45.000 5421.97 4237.17 3078.43 2044.10 1530.95 1019.64 46.000 5520.27 4315.87 3137.73 2083.52 1560.49 1039.32 47.000 5618.11 4394.25 3196.84 2122.82 1589.94 1058.94 48.000 5715.49 4472.30 3255.77 2162.00 1619.29 1078.49 49. 000 5812. 43 4550. 04 3314. 50 2201. 05 1648. 55 1097. 99 50. 000 5908. 94 4627. 46 3373. 05 2239. 97 1677. 72 1117. 42 Estimating Concentrations Downwind from an Instantaneous Puff Release i. * TRINITY CONSULTANTS, INC VAB.0001093934 Estimating Concentrations Downwind from an Instantaneous Puff Release * (U.S.) Environmental Sciences Research Dab* Research Triangle Park, NC PB82-261959 * ** Aug 82 U.S. DEPARTMENT OF COMMERCE National Technical Information Service VAB.0001093935