FINAL REPORT PROJECT: TRACER STUDY OF POWER PLANT EMISSION TRANSPORT AND DISPERSION FROM THE OXNARD/ VENTURA PLAIN " '· "'.. -
By Brian K. Lamb, Arndt Lorenzen (Air Resources Board), Fredrick H. Shair (Principal Investigator
Division of Chemistry and Chemical Engineering California Institute of Technology Pasadena, California 91125 (213) 795-6811: X 1180, X 1197
Prepared for: The California State Air Resources Board Contract No. ARB-5-306 February, 1977 ii
The statements and conclusions in this report are those of the contractor and not necessarily those of the California Air Resources Board. The mention of commercial products, their source or their use in connection with material reported herein is not to be construed as either an actual or implied endorsement of such products. ; ; ;
Summary
Atmospheric tracer experiments were conducted in order to determine the transport and dispersion associated with pollutants emitted from the Ormond Beach Generating Station. Sulfur hexafluoride tracer was released from 3:00 a.m. to 5:00 p.m. on September 21, 1975, and from 3:00 a.m. to 11:40 a.m. on September 22, 1975. Air samples were collected along ten automobile traverses during September 21, 1975, and along three automobile traverses during September 22, 1975. In addition to the automobile traverse data, hourly averaged air samples were collected, at each of eight stations, continuously from midnight September 20, 1975, until noon on September 24, 1975. The data clearly show that pollutant transport occurs from the Oxnard/ Ventura Plain along the Malibu coast into the Lennox area of the Los Angeles Basin, and along an inland route into the San Fernando Valley as far east as Burbank. These tracer data were found to be consistent with air parcel trajectories computed from the available meteorological data. Pollutants emitted from the Ormond Beach Generating Station, under the test conditions, were determined to be diluted by approximately 105 upon reaching the San Fernando Valley and upon reaching the Los Angeles Basin. Further experiments would be required to determine various details associated with the transport and dispersion from the Oxnard/Ventura Plain. However, these data suggest that a Gaussian plume model yields a reasonable upper-bound prediction for downwind concentrations of pollutants emitted from the Oxnard/Ventura Plain. iv
Acknowledgment
We are very happy to acknowledge Charles L. Gennett, Senior Air Pollution Specialist with the California Air Resources Board, for his interest, helpful suggestions, and his help in coordinating this program.
The SF 6 tracer was released by personnel of Meteorology Research Incorporated (MRI); we wish to thank MRI along with the Southern California Edison Company for giving us release data concerning the tracer, along with pertinent meteorological information. We wish to thank the Ventura County Air Pollution Control District, in particular Dr. William C. Thuman, Mr. Douglas Tubbs, Mr. Steve Mollnar, Dr. Thomas Wurzburger, for their cooperation in providing sampling locations, and for providing wind data. We also are grateful to the Los Angeles Air Pollution Control District, in particular to Mr. Dominick J. Mercadante, for providing sampling locations and for providing wind data. We thank Dr. Duane A. Lea, Head of the Atmospheric Sciences Branch of the Geophysics Division of the Pacific Missile Range located in Point Mugu, California, for his interest and for providing wind data. Chief Ron Mathis and Chief Jack Nare of the Malibu and Burbank Fire Stations, respectively, permitted us to locate air samplers at their facilities. We also thank Mr. William Ehorn and r1r. Wayne Pero for permitting us to locate air samplers on the island of Anacapa. V
Personnel
The following persons participated in the 1975 Oxnard/Ventura tracer field studies:
1. Mr. Jeff Blynn 2. Mr. J. David Bruchie 3. Mr. Rex Clingan 4. Mr. Kevin Gromley 5. Mr. James Hickey 6. Mr. Brian Lamb 7. Mrs. Margaret Lamb 8. Mr. Ken Lee 9. Dr. Fredrick Shair 10. Mr. David Walker vi
Table of Contents
Summary iii Acknowledgment iv
Personnel V Table of Contents vi List of Tables viii List of Figures ix 1. Introduction 1 1.1 Description of Test Region 1 1.2 Review of Previous Studies 1 1.3 Objectives of Tracer Field Program 2 2. Experimental Procedure 4 2.1 Release Schedule 4 2.2 The Air Sample Collection Systems 4 2.21 Automobile Traverse System 4 2.22 Hourly Averaged Sequential Air Samplers 7 2.3 Chemical Analysis of Air Samples 7 2.4 Meteorological Support Systems 10
2.41 Surface Wind Data Networks 10 2.42 Upper Air Wind and Temperature Data Collection 10
3. Presentation and Discussion of Results 18
3.1 Meteorological Conditions 18 3.2 Automobile Traverse Results 18 3.3 Best-fit Gaussian Curves to Traverse Data 41 3.4 Traverse Tracer Mass Balance Calculations 57 3.5 Hourly Averaged Tracer Results 62 Vii
Page 3.6 Forward Surface Air Parcel Trajectories 74 3.7 The Gaussian Plume Model as an Upper Bound 87 . 3.8 Pollutant Dilution Factor Calculations 90
4. Summary of Results 94
4.1 Transport Paths, Pollutant Buildup, and Slosh 94 4.2 Dilution Factors and Effects of Terrain 95
4.3 Conclusions 96 5. Recommendations 98
Appendices
A. SF 6 Tracer Release Data 99 B. Gas Chromatograph Calibration Results 102 C. Tabulation of Meteorological Data
C-1 Surface Wind Data 105 C-2 Upper Air Wind Speed and Direction Data 151 C-3 LAX Inversion Height Data 168 D. Tabulation of Automobile Traverse Tracer Data 169
E. Tabulation of Hourly Averaged Tracer Data 189
Literature Cited 196 viii
List of Tables Table No. Page
1 SF 6 Tracer Release Rate Data 99 2 Ormond Beach Generating Station Operational Characteristics 100
3 Automobile Traverse Descriptions 5
4 Location of SF6 Hourly Sampling Stations 8 5 Location of Wind Data Stations and Description of Data 11
6 Surface Wind Speed and Direction Data 105
7 MRI Upper Air Wind Speed and Direction Data 151
8 Point Mugu Radiosonde Data 165
9 Inversion Height Data from Los Angeles International 168 Airport
10 Automobile Traverse Tracer Data 169
11 Best-fit Gaussian Plume Results 58 12 Comparison of Various Dispersion Coefficients 60 13 Tracer Mass Balance Calculation 63
14 One-hour Averaged SF 6 Tracer Data 189 15 Dilution Factors from Hourly Averaged Tracer Data 92 16 Sulfur Dioxide Concentrations 93
17 Gas Chromatograph Calibration and Crosscheck Results 104 ix
List of Figures Figure No. Page 1 Operating Parameters, Ormond Beach Generating Station 101
2 Location of SF6 Sequential Hourly Sampling Stations 9 3 Location of APCD and Navy Surface Wind Data Stations 14 4 Location of MRI Surface and Upper Air Wind Data Stations 15 5 Location of Caltrans Mechanical Weather Stations 16
6 Location of National Weather Service Wind Data Stations 17 7 Point Mugu Radiosonde Data 167 8-28 .Automobile Traverse Tracer Data 19 29-32 Overviews of Automobile Traverse Tracer Data 42 33-43 Best-fit Gaussian Curves Compared to Traverse Tracer Data 46 44 Oxnard Horizontal Dispersion Parameter 59 45 Comparison of Oxnard Dispersion Parameter, ay, to Pasquill 61 Dispersion Parameters 46-47 Hourly Averaged Tracer Data versus Time of Day 64 48-5l1 Overview of Hourly Averaged Tracer Data 67 55-64 Forward Surface Air Parcel Trajectories 75 65 Gaussian Calculated and Experimental Tracer Concentrations versus Downwind Distance 88 66 Gaussian Calculated and Experimental 89 Concentrations versus Downwind Distance 67 Calibration Curve: Zl 103 TRACER STUDY OF POWER PLANT EMISSION TRANSPORT ANO DISPERSION FROM THE OXNARD/VENTURA PLAIN
1. Introduction 1.1 Description of Test Region The Oxnard/Ventura plain of southern California can be characterized as a flat coastal region bounded north and east by inland mountain-valley terrain and on the west and south by the Pacific Ocean. The rough Santa Monica tk>untains rise along the coast to the southeast. The meteorology of this area is dominated by a diurnal land-sea breeze pattern with strong on-shore winds during most of the day. Typically, a shallow (300 meters) mixing layer of marine air exists over the plain. The presence of urban-industrial centers along the Ventura coast and in the northwest and central regions of Los Angeles County poses difficult questions concerning the pollutant impact relationships between the two regions. The complex mountain-valley and coastal terrain that separates the areas, coupled with the diurnal wind system, does not permit simple descriptions of pollutant transport, dispersion, and impact from either region. 1.2 Review of Previous Studies Previous studies in other locales have sought to describe the dispersion of atmospheric pollutants over complex terrains; for example, see Hewson (1945), Holland (1953), Start, et al. (1974), Egami, et al. (1974), Hovind, et al. (1974), and Pasquill (1974). Work by Buettner and Thyer (1962) and Davidson and Rao (1963) was directed towards understanding atmospheric circulation patterns over rough terrain. Examination of turbulence and diffusion mechanisms over and around mountainous regions was the purpose of 2
studies by Davidson (1961) and (1963), Slade (1968), and MacReady, et al. (1974). Work has been reported by Defant (1951), Godske (1957), Ayer (1961), and Kao, et al. (1974) describing mountain-valley wind systems. The results of all of these studies indicate that a great deal of terrain-caused area individuality occurs in dispersion processes. In the southern California coastal region, work by Hind (1970) in the Point Arguello area showed that atmospheric stability had a strong effect upon the importance of terrain in dispersion mechanisms. Angell (1966), using results of tetroon releases in the Ventura area, suggested that "the heating of the interior may cause this area to act like a gigantic vacuum cleaner, sucking in air of a diversified origin." In a study of vertical ozone profiles over the Oxnard plain, Lea (1968) found maximum ozone levels above the inversion layer and concluded that these levels were appareritly the result of air trans ported from the direction of the Los Angeles basin. Most recently, Giroux, et al. (1974) described the results of an SF6 tracer study conducted from Southern California Edison's Ormond Beach Generating Station. They found that the SF6 plume became widespread across the region with no significant differences between concentrationsmeasured in elevated terrain and those found in the flatlands. This was attributed to increased dispersion due to mechanically and thermally induced turbulence over the mountains of the area. In that study, the SF6 plume was easily tracked as far as 40 kilometers downwind. 1.3 Objectives of Tracer Field Program The purpose of this study was to determine possible pollutant transport paths from the Oxnard/Ventura plain to the San Fernando Valley and the central basin of Los Angeles County, and to quantify the dilution of pollutants along 3
such paths. The examination of tracer transport was expected to provide some information about possible offshore pollutant buildup and inland· pollutant 11 slosh 11 due to diurnal winds. The test would also allow further study of the effects of mountain-valley and coastal terrain on the dispersion of atmospheric pollutants. Finally, this preliminary study was to serve as a preparational experience for more extensive future tracer tests in the area. 4
2. Experimental Procedure 2.1 Release Schedule Meteorology Research, Inc. (MRI), Altadena, California, proposed an intensive SF6 tracer study to be conducted for Southern California Edison (SCE) from the Ormond Beach Generating Station (OBGS) during one week in early September, 1975. Under contract to the California Air Resources Board and in cooperation with MRI, we were to conduct an extensive air sampling and SF 6 analysis program during the MRI releases. Due to improper meteorological conditions, the series of SF 6 releases was postponed to late September and then shortened to only two days.
On September 21, 1975, SF 6 was released by MRI from the stack of Unit 1, OBGS, from 0300 to 1705 PDT and on September 22, 1975, from 0300 to 1140 POT.
Hourly mass flow rates and SF6 stack gas concentrations are tabulated in Table 1, Appendix A. The SF 6 stack gas concentrations were calculated from mass flow rate data and flue gas flow rate data made available by SCE and shown in Table 2 and Figure 1, Appendix A. 2.2 The Air Sample Collection Systems 2.21 Automobile Traverse System During each release day, a series of automobile air sampling traverses were conducted using three, two-person teams. Automobile traverses were made by having the passenger in each car take grab samples in 30 cm 3 plastic syringes. Generally, samples were collected every 0.2, 0.3, 0.4, or 0.5 miles, depending upon the distance from the release point and the steadiness of the wind. Descriptions of the traverses are given in Table 3. Traverse paths were determined in the field based upon real time wind data obtained from the Point Mugu U.S. Navy Weather Center and the Ventura Air Pollution Table 3 Automobile Traverse Descriptions
,~~c:t~r,,r- Ga~::- TE:s t ~ta 'le r5 2 Hi ~J h• .. ,a~.' Directicn CrossroJd re~ot~~J Trct \'E.:. rs e U I_, .... C11 ...... _. ; ~ C: • ~: ':, l C ' ,, ' i';o. ,,0. Trav2lec Startin; Locati0n Tin.E: Tr'aveled Cc1>::_, PDT (ri',ii2S
"~=--·~ - -·------~
9/21/75 1 l l Southeast Hueneme 1200-1218 15.6 40 2 1 Southeast Nauman 1423-1442 16.8 55
3 l Southeast Hueneme 1631-1705 27.5 56
4a &b 101 & Las West and 23 Marth 1200-1225 20 51 Posas Rd. South 5 1 &Las Posas North Vista Point on 1 1425-1437 8.4 29 Rd.
6 Hueneme Rd. & East Las Posas 1445-1515 15.5 32 Potrero Rd. U1
7a &b Nl & l South and l 01 1655-1717 15.5 32 East
8a, b, 23 North, East l 1215-1254 23.0 47 ~ C &North 9a g~ b 23 South South and l 01 1415-1456 25.0 51 &l East
lOa &b 27 & l South and l Ol 1645-1721 18. 0 37 East
9/22/75 2 l 1 Southeast Oxnard Blvd. 1250-1312 20.4 52
2a & b 23 South, South, l 01 1245-1320 21. 0 43 . Potrero Rd. , West, Las Posas Rd., South, and &l Southeast Table 3 (co1,-,)
e:: ~:--= j Cr:·.!.. !r'G\'E(Sf Hi ~l h\·.,(~:1 .~ rec t ·i en Cr0ssro:d Dcnoti~s Trc1v2rse Distc'nce !Jc .. :- :Sar· :=, l c: s .' - 7 ;.; 1=• . ,"l.U. r"'d\/£ 7 e:~~ StJrti n ~~ Lo cat i or~ Ti1!e Tti'!ele(2 Co 7 ·': c.: ·-= :~ (rr,i l es ) ------··--· ·-· ·-·-·----··--·----··------·------
9/22/75 2 3 l 01 West 23 North 12 45-1307 22.0 45 (cont.)
O'\ 7
Control District. Additionally, the location and approximate plume shape were determined prior to each set of traverses by sampling along Highway 1 and Los Posas Road downwind of OBGS. These samples were analyzed in the field using a portable electron capture gas chromatograph. The results were qualitative; no attempt was made to quantitatively measure SF concentrations 6 with the portable chromatograph. 2.22 Hourly Averaged Sequential Air Samplers A total of 28 sequential air samplers were located at eight sampling sites within Ventura and Los Angeles Counties. The air samplers (by Developmental Science, Inc.) permitted the collection of hourly averaged air samples each hour for 12 consecutive hours. These samplers were maintained from midnight, September 21, through noon, September 24, which corresponds to seven 12-hour sampling periods. Table 4 lists the location of the sites. Figure 2 is a map of the region and shows the location of OBGS and the eight sampling stations. 2.3 Chemical Analysis of Air Samples
Air samples were analyzed for SF 6 using electron capture gas chromatography. Analytical and operational details for electron capture detection of SF are 6 available elsewhere (Drivas, 1974). Five chromatographs and two digital integrators used in the study were set up at the California Institute of Technology, Pasadena, California. Field samples were returned each day to the lab for analysis. Calibration was done using an exponential dilution method. 12 Calibration results show that concentrations down to 10- parts SF6 per part air can be detected at a signal-to-noise ratio of better than 3 to 1. The chromatogram peaks were integrated with an Autolab System I electronic digital integrator (Spectra-Physics, Santa Clara, California). The uncertainty of the tracer data is approximately± 9% overall. Details of the calibration 8
Table 4
Location of SF 6 Hourly Sampling Stations
1. Lennox, Los Angeles APCD Station, 11408 La Cienega Blvd.
2. Santa Monica, Ocean Park Blvd. Children's Center, sth Avenue and Ocean Park Blvd.
3. Malibu, Malibu Fire Station #88, 23720 W. Malibu Road
4. Thousand Oaks, Ventura APCD Station, Glenwood School, 1135 Windsor Drive
5. Simi Valley, Ventura APCD Station, Simi Valley High School, 5400 Cochran
6. Reseda, Los Angeles APCD Station, 18330 Gault Street
7. Newhall, Los Angeles APCD Station, 24811 San Fernando Road
8. Burbank, Main Burbank Fire Station, 353 E. Olive Avenue <::?
~ SANTA BARBARA ~
PASADENA
I.O
~Ji09 ANACAPA .. ISLAND
◊LENNOX \ I
~ SCALE 5~-== 0 ,o. 15 20 MILES 5 0 5 10 15 20 ~---- 25 ~ KILOME TEAS oLONG BEACH -:=-:....----::::=:= _.::_~---::..::::::::.-----=--
- ~ -, --~~ ·,. Figure 2. Location of SF6 Sequential Hourly Sampling Stations ◊ , 10
results are described in Appendix B. 2.4 Meteorological Support Systems 2.41 Surface Wind Data Networks Wind speed and direction data stations used during the test periods are listed in Table 5 and shown in Figures 3-6. The surface wind data from each of the stations are given in Table 6, Appendix C. The data were obtained from several agencies: Ventura Air Pollution Control District, Los Angeles Air Pollution Control District, Meteorology Research, Inc., Caltrans Mechanical Weather Station System, U.S. Navy Pacific Missile Range (Point Mugu), and the National Weather Service (NWS) data network. Data from the first four sources represent hourly averages taken from continuously recording instruments. Data from Point Mugu and NWS consist of single hourly observations. 2.42 Upper Air Wind and Temperature Data Collection Upper air wind direction and speed measurements were taken by MRI at four locations several times daily during the release days. Similar data, including upper air temperature soundings, were obtained from Point Mugu for September 22. The MRI data are given in Table 7; the soundings are shown in Figure 7. Inversion height data from measurements taken twice daily at Los Angeles International Airport (LAX) are given in Table 9. This information is all in Appendix C. 11
Table 5 Location of Wind Data Stations and Description of Data
Location* , Operating Agency Type of Data 1. Camarillo, Ventura APCD Station Continuously recorded surface wind speed and direction 2. Santa Paula, Ventura APCO Station Continuously recorded surface wind speed and direction 3. Simi Valley, Ventura APCO Station Continuously recorded surface wind speed and direction 4. Ventura, Ventura APCD Station Continuously recorded surface wind speed and direction 5. Laguna Peak, Point Mugu U.S. One observation per hour, Naval Station (elevation, 447 m) surface wind speed and direction 6. Point Mugu, Point Mugu U.S. Naval One observation per hour, Base surface wind speed and direction; upper air temperature, wind speed and direction, three times daily 7. Burbank, Los Angeles APCD Station Continuously recorded surface wind speed and direction 8. Lennox, Los Angeles APCD Station Continuously recorded surface wind speed and direction 9. Newhall, Los Angeles APCD Station Continuously recorded surface wind speed and direction 10. Reseda, Los Angeles APCD Station Continuously recorded surface wind speed and direction 11. Camarillo Heights, MRI Tracer Continuously recorded surface Study Station wind speed and direction 12. Moorpark, MRI Tracer Study Station Continuously recorded surface wind speed and direction; upper air wind speed and direction, several times daily
*The address of any particular station may be obtained from the appropriate operating agency. 12 . Table 5 (cont.)
Location, Operating Agency Type of Data 13. Ocean View School, Oxnard, MRI Continuously recorded surface Tracer Study Station wind speed and direction 14. Rio Mesa High School, MRI Tracer Continuously recorded surface Study Station wind speed and direction 15. Camarillo, MRI Tracer Study Upper air wind speed and Station direction, several times daily 16. Camarillo State Hospital, MRI Upper air wind speed and Tracer Study Station direction, several times daily 17. Ormond Beach Generating Station, Upper air wind speed and MRI Tracer Study Station direction, several times daily 18. Los Angeles International Airport Single observation surface wind (data obtained from LA APCD) speed and direction; upper air temperatures twice daily
19. Granada Hills, Caltrans Station Continuously recorded surface wind speed and direction
20. Camarillo, Caltrans Station Continuously recorded surface wind speed and direction
21. Glendale, Caltrans Station Continuously recorded surface wind speed and direction
22. Los Angeles (downtown), Continuously recorded surface Caltrans Station wind speed and direction 23. Pasadena, Caltrans Station Continuously recorded surface wind speed and direction
24. Culver City, Caltrans Station Continuously recorded surface wind speed and direction
25. Claremont, Caltrans Station Continuously recorded surface wind speed and direction 13 Table 5 (cont.)
Location, Operating Agency Typi: of Data 26. Woodland Hills, Caltrans Station Continuously recorded surface wind speed and direction
27. Santa Barbara, National Weather Single hourly surface wind Service (NWS) speed and direction observation 28. Oxnard NWS Single hourly surface wind speed and direction observation 29. Santa Monica NWS Single hourly surface wind speed and direction observation 30. Van Nuys NWS Single hourly surface wind speed and direction observation 31. Burbank NWS Single hourly surface wind speed and direction observation 32. Torrance NWS Single hourly surface wind speed and direction observation 33. Long Beach NWS Single hourly surface wind speed and direction observation 34. Ontario HWS Single hourly surface wind speed and direction observation 35. Santa Ana NWS Single hourly surface wind speed and direction observation 36. San Nicholas Island ~WS Single ~curly surface wind speed and direction observation 37. Santa Catalina Island NWS Single hourly surface wind speed and direction observation
~ SANTA BARBARA
PASADENA
I-' .i::,.
- .ii(')9 ~ ANAC~PA ISLAND \\ '~ -~
,, ■ LENNOX \ I \ SCALE 5 0 "'> 10 15 20 MILES -=-:::::::a--t". - 5 0 ~ 10 15 20 2~ 30 l ~ SANTA BARBARA ~ •:~ PASADENA ORMO BEACI ..... GENERA u, STATION ~~9 ANACAPA ISLAND ◊LENNOX I \ SCALE _, '0 !~___ _20 MILES ' 0 ~~ 5, ------0 -- 5 =----~- !0----~-===--==- l~ 20 2~ 30 KILOMETERS. _.~-~~ONGBEACH r-P · -.~ ~ '~", '" \ ~ Figure 4. Location of MRI Surface and Upper Air Wind Data Stations• ¢ ~ SANTA BARBARA lfJ ~f- l \4SA0£NA -0-, ~,:i()9 ~SANTA CRUZ ISLAND ANACAPA ~ ISLAND \ \ •◊LENNOX I \ SCALE 10 15 20 MILES ,o 15 20 25 "30 Kl LOME TERS ~BEACH r ·~ Figure 5. Location of Caltrans Mechanical Weather Stations. ◊ ~ SANfA BARBARA ~ '~ PASADENA ...... '-I ~- r'" ~ - ~409 SANTA CRUZ ~S~ ,r===~- ANAC-lPA ISLAND £◊LENNOX I \'\' \~ SCALE A 5 0 ;Q ,'5 20 MILES -=-.;:.~. 5 0 '5 1Q •5 20 2'5 ~O J(lLOMETERS Ji..LONG BEACH PC31B- ~- - ~ \ .A -Y~\ ·, ',, Figure 6. Location of National Weather Surface Wind Data Stations A 18 3. Presentation and Discussion of Results 3.1 Meteorological Conditions During the daytime sampling periods, surface winds. were generally from the west-northwest at approximately two meters per second along the coastal regions and from the south-southwest at one meter per second in inland areas. At night, surface winds were from the north-northeast at less than one meter per second over the coastal plain and were variable at low speeds further inland. The inversion height over 0BGS during Test 1 is unknown; data taken at LAX indicate the inversion height to be slightly more than 200 meters during the afternoon. Test 2 data show the inversion height increasing from 100 meters at 0455 PDT to around 180 meters by 1615 PDT on September 22. For the remaining sample periods, the height of the inversion layer ranged from the surface during sample period 5 to 600 meters on several occasions. In terms of Pasquill atmospheric stability classes, conditions were generally class D during the daytime hours of both release days. 3.2 Automobile Traverse Results Ten automobile traverses were completed during Test 1 and three traverses were conducted during Test 2. Significant SF6 concentrations were detected in all Test 1 traverses and in one out of three Test 2 runs. Tbe data is tabulated in Table 10, Appendix D. Figures 8 - 28 show SF6 concentrations plotted versus distance along the traverse. Starting and stopping points as well as the direction of travel and various landmarks are marked below each traverse. Important characteristics of tracer transport from 0BGS are apparent in the concentration plots. First, a single, high concentration plume Figure 8. TEST 1 TRAVERSE 1 LEG DATE 9/21/75 TIME• FROM 1200 TO 1218 0 N (T') ... CROSSWIND__J PORTION -I ~§?I- I \ ► SOUTHEAST ON HWY I J- ("\I a..CL .....,, __, !POINT !HWY <..O - :z D I \ MUGU 23 -o J-a:(D- a: :zJ- w u :z I~ D u~,w ~w z w ::) I oL,__ 0 3 6 9 12 15 18 DISTANCE AL~NG TRAVERSE (MILES) Figure 9 TEST 1 TRAVERSE 2 LEG DATE 9/21/75 TIME• FROM lij23 TO 1442 a a N a (D r-. - I- Q_ (L .._,,a z-N N D I I I I I 0 ~ I-cc a: 1-ozoo w u z 0 u a :::1' a ...... ,.....,.,...... ,~....-----~----~---~~----~---~ 0 3 6 9 12 15 18 :::0 z NI DISTANCE RL~NG TRAVERSE TEST 1 TRAVERSE 3 LEG- ORTE 9/21/75 TIME• FROM 1631 TO 1705 0 (D..... 0 r-..N 1-- ..... Cl.. 0... '--- z 8 N -oL I l I-' 1--ooa: a: 1--z w u z 80 u ::1' 0'----=...."------'------L-----_i_-----....__-----~------L------' 0 ij B 12 16 20 2l! 28 :::0 :r: ~-0 DISTANCE RL~NG TRAVERSE (MILES) ZI 0 C C O_ -lO Q (D lO :::::, ::r 0.:::::, C -+- (D :f Q 3 '< (D --... Sn11thP.nst nn Hinhv,1r,v I Figure 11 TEST 1 TRAVERSE q LEG A DATE 9/21/75 TIME• FR~M 1200 TO 1225 C) -N ,,..... ~ a.. C) (L co ....__,, z N ...... CD I I \ N ~cc a: z~ WO uz ::t' D u - o~~~~~~----ti~0 2 ij 6 8 10 12 ll! NI DISTANCE AL~NG TRAVERSE (MILES) :::or (>J <.O. 00 G)C) 0 CJ) z :::r ~o ~ 0::J 0... --0 0 0... (D 0 (D '-· CJ> '< 0 0 _.. West on Hiahwav IOI ( r, Figure 12 TEST 1 TRAVERSE l! LEG B DATE 9/21/75 TIME• FROM 1200 TO 1225 0 0 LI) 0 0 :::1' r",. I- (L Q_ '-../ 0 0 Zen N ..,_D I I \ w I- a: r-oa::o ZNw u z u~ 0 0- oJ, • A I 0~::J""",t(0 A ---.1•~~ld•~=-,,,__..J_~ ~--~'_____JL ____ , - 0 1 . . 2~ 3 ij 5 6 7 -<0 A .I, ~ DISTANCE AL~NG TRAVERSE (MILES) I I ::::0 I t.O oc ::J""" 0 (D :f 0.. :::J 0 '< (D '< --.. Sn11th nn I nc:. Pnc:.nc:. Rnnrl =1 Figure 13 TEST 1 TRAVERSE 5 LEG DATE 9/21/75 TIME• FROM lij25 TO 1437 0 ::J' C'\I 1-" 0... 0 ..._,,(L -(D z D N ...... ~ l a: a: 1-z w UO ZCD 8u 01 ~ I ...... ,1 M". ~ ...... ,.. .. ' 0 2 ll 6 8 10 -O< AL □ NG 0 -· DISTANCE TRAVERSE (MILES) 0~ -· (f) -l.O :::,-t-0- :::r ~ s-o 0 ·c o '< lO :::, . -. North on I n nc! Ins Pnsnc; Ronrl Figure 14 TEST 1 TRAVERSE 6 LEG- DATE 9/21/75 TIME• FROM tij45 TO 1515 0 =i- ,..._O r- en CL Q_ '-/ z N ._a...... D u, a:("\J ._a: z w u z uoD - o .. •• ...... • • "' 0r 3 6 9' 12 15 18 0 0 o::::0 en DISTANCE AL~NG TRAVERSE~ (MILES)' ' NI . ~ ~ (>JI.O. ::::0 ::::0 (f) -::::::r 0 CD 0 -- :E 0 ::, 0 (/) 0... 0 '< 0 ( /) _.,.. Fnst nn Pntr8ro Ronrl Figure 15 TEST 1 TRAVERSE 7 LEG A DATE 9/21/75 TIME• FR~M 1655 TO 1717 0 (D ._,,...._ O...o (L :::f' '-/ z D N ._._.... I • • I \ I \ 7'--- (J) a: ._a: z WO uNz E) u 0 -1. 0~ol ______L__ -t.Ol 2 4 ____...L6 ----:----8 10 o DISTANCE AL~NG TRAVERSE (MILES) -- I lO ::r ~ 0 '-< '-< -.. South on Hiohwnv NI Figure 16 TEST 1 TRAVERSE 7 LEG B DATE 9/21/75 TIME• FROM 1655 TO 1717 ('\J..... r-- t- 0.... a_(X) '-" z N 0 '-I t-1 I \ I t- a: I \ I ! a: zt- w u ::t' z IDu □ ;:;------~------:1:------_L______j_~______J 0 1 2 3 ij 5 ZI DISTANCE AL~NG TRAVERSE (MILES) I.O :::r :E 0 '< --.. Fnst nn Hinhwn" I Figure 17. TEST 1 TRAVERSE 8 LEG DATE 9/21/75 TIME• FRCTM 1215 TCT 125ij a a -1.-----~---CROSSWIND1 PORTION------~ a (X) ,-... I- WEST a.... a.... ----► NORTH ON 23 S _..ON --~► NORTH ON 23 S '-J N a HWY IOI (X) z 0 I I - ~ - I - - ll(: I~ ¥ 1 I I I 0 4 8 12 16 20 24 DISTANCE AL~NG TRAVERSE (MILES) Figure 18 TEST 1 TRAVERSE 8 LEG- A DATE 9/21/75 TIME• FROM 1215 TO 12SY 0 -0 0 (D ~ I- a... a_ ..._,, 0 zw ID N ._1----4 I \ I.O a: a: 1-o z ::r w u z ID u 0 ('\J o.______....______.______._""'16-______.______---'_ _.'------A a 2 ij 6 8 10 12 I DISTANCE RL~NG TRAVERSE (MILES) 0~ lO -<..0 :::r :::r ~ ~ 0 0 '< _.. North on 23S '< 30 :::1' N Highway t() C'\I 23N -0 I- t() -N E cc0 u.. UJ- "en .....E w I- _J 1--1 .._,,.:E: t() t'- ...... w - N en -...... a: C O') w UJ > ( I- a: C a: a: CJ ...... l-- -+- 0-, u ...... C) Q c:: Q) co s.. z ---- ~ c;, 0 •r- _J ~ cb a: t UJ ....J w u z co a: l-- en 1--1 UJ (J") 0 cc UJ > ~ I- 1- (J") UJ I- fl~~----:---~9~t-----~~---_J o Highway 8 (ldd) NQI1~~1N3JN~J o 23S Figure 20 TEST 1 TRAVERSE 8 LEG C DATE 9/21/75 TIME• FROM 1215 TO 1254 0 CD ,...... ~ CL a Q_ ::1' "'-../ z w ...... E) I ---...... _.. ~ a: a: z~ WO zUN E) u 0 ol___..J__~_ 2 4 6 8 10 o:r; DISTANCE AL~NG TRAVERSE (MILES) -lO :::r ~ 0 '< -. North on ?~f\! 32 ~ Highway I (O lf) ::r .-c 0 t- lf) -::,0-,..... -0 aa: LL ,,...... , UJ- (f) .....2: w t- _J co ...... , L -....J If) ['- w N' en - a: Cf ('1)' lJ.J I'< UJ > (\. I- a: a: a: C CJ co I- C ...... N D ..c: a., a: -+- s... z - ::::l 0 C- .....c:n _J Cf 1.1.. cb a: UJ _J lJ.J u t :::,,Z a: I- en ~ LUen 0 a: lJ.J a:> a: I- N Ien UJ I- '------1------~~------' o Highway 09 Oh 0~ O IOI (ldd) NQI1~81N3JNQJ Figure 22 TEST 1 TRAVERSE 9 LEG B DATE 9/21/75 TIME• FROM lijlS TO lij56 0 00 ,..,.□ (JJ I- 0...... _,,CL :z w E) I I ~ I ~ I w ...... • 1- □ a: :::14 a: I- :z w u z E) 0 UN c:,.______,L______-4--______,______,______.______.______. a 2 l! 6 8 10 12 1~ NI (>.J -- DISTANCE AL~NG TRAVERSE (MILES) s lO 0 ::r rr :E C 0 '< _.., Fn~t nn ~irihwn,, I 34 ::j' -~ .-, (\J r- .-1 ...... D Highway I 11) N =.1' ...... CD - L cc0 u.. w- " .....L ocn...... w ...... _J 1-1 ~ '-..../ r- 11) (, r--- --.... w (/") -~ ~ -(\J '- --.... co er: < 0) w ,- > r- ...... w cc '- M N a: er: I □ r- N 1- (/) w I- J..------1------~------+-- o Highway Oct 08 On O IOI (ldd) NQI1~81N3JN □ J Figure 24 TEST 1 TRAVERSE 10 LEG B DATE 9/21/75 TIME 1 FROM 1645 TO 1721 0 :::I' 0 ~ (Y) i- Q_ Q_ '-../ z w D t.n ~ i--0a:N a: zi- w u z D uo...... o,.______L.-...______..,______~ ______.______...... 0 1 2 3 ij 5 NI s@rn~ -..J -- DISTANCE AL~NG TRAVERSE (MILES) c.O 0 0 < :::::I ::::, :::, ::::, 0... 0 -- -+. 0 :E oo - 0 0 ::::, '< ...... -----Crtr-+ ~.,.., 11;,... 1-- •• ,. Figure 25 TEST 2 TRAVERSE 1 LEG DATE 9/22/75 TIME• FROM 1250 TO 1312 0 <.D .,_r--.. CLo ...._(L :::l' z w E) I I I 0) .,_...... a: .,_a: z WO zUN E) u o ____ - - 0 3 6. 9 12 15 18 21 mo NI - >< DISTANCE AL~NG TRAVERSE (MILES) 0J -- < :J ~-0 l.O .o..o C O _ ::J"" l.O :J ~ '0.. C -+ 0 _.., Sn 11th Pnst nn Hin h,,vnv I '< 37 ...... co 0 N ...... ('I") 0 Las Posa I- Road l/) :::r N...... l/) :i:: - a:0 LL ,,...._ lJJ- Cf) :i:: LJ.J -I- _J N i----t -L ( -....J l/) ( r-- ...... IJ.J N C N en ...... a:: O') lJ.J lJJ > I- a: -+ a: a:: ( CJ O') 1-- C I.O N c..:, w a: z s... 0 -+ :::I ( O'> _J -~ ( LL cb a: w <- _J LJ.J - u J CD Z N a: 1-- en 1-i w 0 lf) a: lJJ a:> a: I- ('I") N .... lf) w I- o Highway 9 fl c 0 101 ( ldd) NIJ I lt:U::11N3JN(JJ 38 0 ::jt Highway (\I ('r) -C) I- l/) ;j' ('\I- L tJcc u.. ('r) .,,-.... UJ- (/) L lJ.J I-- _J "7 _, { L ( '-/ l/) C ['- lJ...I (. ('\I (/) t N' cc t 0) LU C ' > C UJ a: I-a: cc (., 0 NI- t r-.... N ~ C Qj a:, C s... z ::, 0 O"l _J .£. .... -+- LL. (!) a: - LU C lJ...I u -' u z N a: I- t (/) 1-t UJ (f')cc -□ IJJ >a: cc I- N 1- (f') lJJ I- 83---~9;----~fl----1-~---_Jo Potrero (ldd) NQI1~81N3JNgJ o Road Figure 28 TEST 2 TRAVERSE 3 LEG N+- DATE 9/22/75 TIME• FROM 12q5 rcr 1307 ♦ J"""- o._ CL "-" z ...... 0 w J- - H ~ a: • a: • • Jz w u z u0 ol!••••l l ••••••• l ••1 l •• l •• l 1•• l •••• 1 ll... f 0 ll 8 12 16 20 21J DISTANCE AL~NG TAAVEASE (MILES) 40 profile immediately downwind of OBGS was outlined by traverses 1, 2, and 3 along Highway 1 and in 4b and 5 on Las Posas Road during Test 1. The same is true for traverse 1 of Test 2 on Highway 1. Maximum concentrations in the Test 1 routes range from 126 to 420 ppt SF6 at downwind distances between 7 and 10 kilometers. The peak value in the Test 2 traverse is 59 ppt SF . 6 The second-day traverses occurred just after the release was stopped. A second feature of the first-day runs is that for traverses taken parallel to the wind, concentrations decreased very irregularly with downwind distance. Traverses 1, 2, 3, 7b, 9b, and lOb clearly indicate the irregular presence of significant levels of SF6 all along the coast as far to the southeast as Lincoln Boulevard in Santa Monica. Ten-second traverse sample concentrations near and in Santa Monica were approximately 20 ppt SF6• This coastal transport is also evident in crosswind traverses ?a, 8(8a), 9a, and lOa. Data from these coastal mountain drives place the centerline of the plume from 2 to 8 kilometers inland. Peak concentrations decreased from 90 ppt in 8a to 40 ppt in 10a, 26 and 56 kilometers downwind of OBGS, respectively. The high sharp peak at the start of traverse 10a cannot be logically explained; it is assumed to be due to local contamination. The final major detail in the traverse picture is the path of a second, inland plume from OBGS. Traverse 4a outlines a clear plume profile 21 kilometers to the northeast of the release point. The centerline concentration in this route was 117 ppt SF6. Concentrations around 30 ppt SF6 were detected in traverse 6 along Potrero Road on the north side of the coastal mountains. The presence of twin plumes is also evident in traverse 8. The coastal plume peaks two kilometers inland at 90 ppt, while the inland plume is centered at 60 ppt approximately 25 kilometers inland, north of Highway 101. 41 The second plume extends as far north as Moorpark. Comparison of peak concentrations between the two plumes indicates that the major transport path probably passed along the coast. The southerly positions of the high profiles immediately downwind of OBGS support this observation. Overview maps of the traverse data are shown in Figures 29-32. The double plumes are most apparent in Figure 29. The inland plume passes over Thousand Oaks and appears headed across the area between Simi Valley and Reseda. The coastal plume is outlined more clearly in Figure 31 where traverses were taken all along the coast. It is possible that under the nighttime land-breeze, a cloud of SF6 developed offshore, and then with the advent of the daytime sea-breeze, the cloud was pushed inland superimposed over the daytime OBGS plume. The north-south widespread detection of tracer does not prohibit such a deduction. However, the traverses do show two apparently separate plumes downwind of the release point. If the cloud were present, its strength and size could not be differentiated from the plumes carried by the daytime winds. 3.3 Best-fit Gaussian Curves to Traverse Data Crosswind traverse data are compared with best-fit Gaussian curves in Figures 33-43. On traverses 1, 2, 3, and 4b, the data conform fairly well to a Gaussian shape. These traverses were taken immediately downwind of the release point across flat, open country. Traverses 4a, 8a, 8c, 9a, and 10a were located further downwind amidst the inland mountains and valleys. In these cases, the Gaussian curve provides only an approximate form of the data. The best-fit curves were used to determine the crosswind standard OXNARD TEST NO. 1 9/21/75 Figure 29. AUTO TRAVERSES: 1 12:00-12:18 p.m.PDT C> 4 12:00-12:25 p.m. PDT ~ ► 8 12: 15 - 12:54 p.m. PDT * RELEASE POINT MAX [S F6] = 420 ppt. PASA0£N,,! .+:--, N ~,iii:)9 ANACAPA ISLAND \\ \ ◊Lt:NNOX 1 SCALE 0 5 10 l!t 20 MILES 0 1Q l!!I 20 25 30 KILOMETERS .~~-~ONGBEACH r·~,. rr,..-' '\, ~)' . \ """, OXNARD TEST NO. 1 Figure 30 9/21 / 75 2 2 :23 - 2 :42 p.m. PDT ~ 5 2:25-2:37 p.m. PDT ~ t> 6 2: 45- 3: 15 p.m. PDT ► 9 2: 15- 2:56 p.m. PDT * RELEASE POINT MAX (S F6 ] = 209 ppt. PA5A0Ou! ..,. <.,-1 ~,t,()9 ANACAPA ISL.t.tvO ◊LENNOX I SCALE 5-=~ 0 ~ 10 I~ 20MILES 5 0 5 10 15 20 25 }O Kl LOME TERS L0NG BEAC,; ~--.c--··- -- 0 ~ _,,'7.t!;:;y~ '\ j=· ~ ·.• ""'· \ '· "-.,, OXNARD TEST N0.1 9/21/75 Figure 31 AUTO TRAVERSES: 3 4: 31 - 5:05 p.m. PDT t> 7 4:55- 5: 17 p.m. PDT ~ ► 10 4:45- 5: 21 p.m. PDT N * RELEASE PO INT I MAX [ S F6 ] = 126 ppt. PASADENA -+"- -+"- ~jl)9 ANACAPA ISLAND ◊LENNOX \ I I I• I' SCALE "' 0 ~ 10 t!1 20 Mil.ES 5 0 ~ I!) 20 25 ~ KILOM£TERS t- , i.c-~)- oLONG BEACH 1 1~·¾,>'c~~ - ~~ ~'· OXNARD TEST N0.2 9/22/75 Pigure 32 AUTO TRAVERSES: ◊ > I 12:50- I: 12 p.m. PDT C> 2 12:45 - I :20 p.m. PDT ~ ► 3 12:45- I :07 p.m. PDT * RELEASE POINT MAX [SF6 ] = 59 ppt. PASA0£NA ~ tJl '~~9 ANACAPA ISLAAO ◊?£NNOX I SCALE ~-2----- 5 tQ 15 20 MILES ~-=9_ ~ 10 IS 20 ·==2~ -30 KILOMETERS JJ:,;~~--~-LONG BEACH- 1/.~!'-- - ~... ,,: "¾ \. " Figure 33 TEST 1 TRAVERSE 1 LEG DATE 9/21/75 TIME• FR~M 1200 TO 1218 a ('\I en t!fi a /'"'- ::!' I- ('\I a.... CL '--"' z D .,::. --.a O'I I-crCD a: 1-z w u z o a Uro Cl~!r-6..------'-----::::l!i~--'------'------'------...___------' o 3 6 9 12 15 18 DISTANCE AL~NG TRAVERSE (MILES) Figure 34 TEST VENl TRAVERSE 2 LEG DATE 9/12/75 TIME• FROM 1423 TO 1442 a a ('\I a (D...... ,...,, I- CL CL '-./a z N...... 0 1--i...__ a: a: ...__ a zco w u z D u a :::1' Of I I I I I I I 4- I I I I I I I~ I I I ::::-::---, 0 1 2 3 4 5 6 7 DISTANCE RL~NG TRAVERSE TEST 1 TRAVERSE 3 LEG DATE 9/21/75 TIME• FROM 1631 TO 1705 0 (D- 0 r-..N 1--- CL CL.,._,, z .j:::, .._E) I I \ \ 00 1--0 a: co a: 1-- z w u z 00 Ll::::,, o.__~.-----L------l==------'------'------'------'------J 0 l! 8 12 16 20 24 28 DISTANCE ALONG TRAVERSE (MILES) Figure 36 TEST 1 TRAVERSE ll LEG A DATE 9/21/75 TIME• FROM 1200 TO 1225 0 ('\J...... r--.. I- CL.a CL co ~ +" :z I I / \ ~ U) ...... 0 I- a: a: I- :z WO u:::!' :z E) u o~ 1 :r=:::+ 1 I., .r-C I I I I t -- I 0 2 ll 6 8 10 12 1ll DISTANCE RL~NG TARVEASE (MILES) Figure 37. TEST 1 TRAVERSE l! LEG B DATE 9/21/75 TIME• FROM 1200 TO 1225 a a l/) _!' a a ::::f' ...... I- Q_ CL '-"a tn z~' II .. ~ 0 ...... 0 I-cc er: 1-0 z~ w u z 0 u a a..... OJ. • A I • • ,.L. • • I 41: • J. ~~ I I I 0 1 2 3 ij 5 G 7 DISTANCE ALONG TRAVERSE (MILES) Figure 38 TEST 1 TRAVERSE 5 LEG DATE 9/21/75 TIME• FR~M 1425 TO 1ij37 C) :::t' N ,,...._ 1- Q_ C) Q_ (D '-.J - u, :z ...... D 1- C) 1 --::ii. 1 I I I I I I 11 1..-::: '>t I I I I I I I I I I I I I 1 0 2 ij 6 8 10 DISTANCE RL □ NG TARVEASE (MILES) Figure 39 TEST 1 TRAVERSE 7 LEG A DATE 9/21/75 TIME• FROM 1655 T~ 1717 a (D ;--. r- a_o a_::!' '-./ z (J"I D I ~ I \ ~ N 1--i r- (I a: r- z WO UNz E) u o..______.______....______.______--L..______. 0 2 4 6 8 10 DISTANCE RL □ NG TARVEA5E CMILE5) Figure 40 TEST 1 TRAVERSE 8 LEG A DATE 9/21/75 TIME• FROM 1215 T~ 125ij C) -C) C) (X) ,,..... a...J- a... '-../ C) z (DJ wU1 0 "\ 1------4 J- a: a: J- □ z ::jt w u z 0 u C) N al I I .. t::>...(-• I - • .. I\.,/: I 0 2 ij 6 8 10 12 DISTANCE RLDNG TARVEASE (MILES) Figure 41 TEST 1 TRAVERSE 8 LEG C ORTE 9/21/75 TIME• FROM 1215 TO 125ij 0 (D "'I- CL a CL::!' '-/ z u, D -i::- 1--i I ~ I- a: a: I-z WOu('J z E) u a....______...... ______.______.______.______. 0 2 L! 6 8 10 · DISTANCE RL~NG TARVEA5E (MILES) Figure 42 TEST 1 TRAVERSE 9 LEG A DATE 9/21/75 TIME• FR~M 1415 TO 1Y56 0 (.£) ~ r- a_ □ a_ =:2' '-J z ~ u, D I A / v-' I ~\ u, ...... r- CI cc r- :z WO :zUN E) u C)"---______,______.______.L------'------__,______-...J 0 2 ~ 6 8 10 12 DISTANCE RL □ NG TARVEASE (MILES) Figure 43. TEST 1 TRAVERSE 10 LEG A DATE 9/21/75 TIME• FROM 1645 T~ 1721 CJ CD r". ~ a... CJ CL ::2' '-JI' z u, D I ~ 0) -cc~ a: ~z WCJ zUN uD CJ b "& ~ V: ";. ~ I I I I I I 0 2 l! 6 8 10 12 14 DISTANCE AL □ NG TRAVERSE (MILES) 57 deviation, cry, for each traverse; the results are given in Table 11. Traverse 4a is not included. Additionally, the maximum experimental tracer concentration (Cmax(exp)) and its distance along the traverse (Ymax(exp)) are listed in comparison to the best-fit values. The downwind distance X, also given, was measured from the overview maps. Traverse data from Test 2 were not used in the best-fit calculations. A plot of cry versus downwind distance is given in Figure 44; the line in the plot is a least squares best-fit through the data. If the form of cry is taken to be: cr = axb y the coefficients a and b can be found from the best-fit line through the data. These values are compared to coefficients for Pasquill stability classes in Table 12. Pasquill values are for dispersion over flat, open country. Figure 45 shows the Oxnard line and several Pasquill curves. As might be expected, the Oxnard curve is steeper; dispersion increases quickly with distance. Pasquill classes Band C border the Oxnard data at downwind distances of less than 10 km. At greater distances, horizontal dispersion increases to levels comparable to Pasquill class A stability. Evidently, the complex terrain downwind of OBGS greatly aids in dispersing pollutants emitted from the plant. No data is available to determine the effects of this terrain on vertical dispersion. 3.4 Traverse Tracer Mass Balance Calculations The automobile traverse data can be integrated over distance to provide an average flux of tracer gas passing through the traverse area. This flux can then be compared to the amount of tracer released at the source to 58 Table 11 Best-fit Gaussian Plume Results Test 1 (9/21/75) Trav. Time Cmax ymax X cry PDT exp fitted exp fitted km meters ppt km 1 1200 270 223 2.6 3.7 6.75 1170 2 1423 190 159 8.7 8.2 7.50 625 3 1631 126 109 7.2 7.6 9.75 900 4b 1200 420 431 9.0 9.5 8.63 920 5 1425 209 115 0.0 0.0 9.38 860 7a 1655 52 34 9.7 9.3 43.10 4710 Ba 1215 88 67 .8 0.0 26.20 4240 8c 1215 58 52 4.0 5.1 29.10 6800 9a 1415 53 44 11.3 9.3 27.00 7390 10a 1645 39 34 15.3 15.0 55.70 4460 59 (/) 3 a: 10 w ~ I-w :l: • >- I a: ~ 0 ~ 102 (/) 10 1 L---'--~-'-.._.,_..1....1...JLI---'--'----L-.....L.-l___.__._...... __ _,______,J.__._._...,_,_...... __, 102 103 104 105 X, METERS OXNARD-1 Figure 44. Oxnard Horizontal Dispersion Parameter 60 Table 12 Comparison of Various Dispersion Coefficients cr = axb y a b cry cry (x= 10 km) (30 km) Oxnard 0.0415 1.116 1208 4116 Class A 0.426 0.891 1561 4155 Pasquill Class B 0.317 0.891 1162 3092 Class C 0.218 0.891 799 2126 Class D 0.144 0.891 528 1404 Class E 0.112 0.891 410 1092 Class F 0.0729 0.891 267 711 61 U1 3 a: 10 w I-w ~.. >- I (I ~ C) 102 -U1 10 1 ..______._...___.___.__...... _...... __...,___.__,__._....L...... L...i-i..J....---'---'--'-...._._...... _..__, 102 103 104 105 X, METERS Figure 450 62 provide a mass balance on the experimental data. If the wind is averaged over height, the tracer is assumed well-mixed to the mixing layer, and no transport occurs above the mixing layer, the flux may be written 00 Q = ii L I C(y) dy -oo where u is the average wind speed, Lis the mixing layer height, and C(y) is the concentration of SF6 along the traverse path. Details of the integration scheme are available elsewhere (Lamb, et al., 1975). Results for Test 1 traverses are shown in Table 13 in terms of percent tracer gas observed. These values were calculated using L = 244 meters, and taking -u = 5.4 m/sec, the wind speed at OBGS averaged from the surface to 211 meters. An alternative method of using the mass balance calculations is to assume 100% of the tracer is observed and to back-calculate either the mixing height or average wind speed. These results are also given in Table 13. The mass balance results are very good considering the simplifying assumptions. The average percent tracer observed in the 10 traverses is 95%. The predicted mixing heights appear to be rather high compared to the LAX inversion height data. However, except for Traverse 5, the predicted average wind speeds do not seem unreasonable. 3.5 Hourly Averaged Tracer Results Hourly averaged tracer data from the eight stationary sampling sites are tabulated in Table 14, Appendix E, and plotted versus time of day in Figures 46 and 47. During sample period 1, no tracer activity was detected 63 •I Table 13 Tracer Mass Balance Calculation ~,, Test 1 ( 9/21/75) Traverse %Tracer Predicted Predicted Observed Mixing Layer Wind Speed meters meters/sec 1 129 189 4.2 2 47 519 11.4 3 47 519 11.4 4a 91 268 6.0 4b 182 134 3.0 5 25 976 22.0 7a 70 349 7.7 8 178 137 3.0 9a 119 205 4.5 10a 61 400 8.9 AVE. 95% AVE. 370 AVE. 8. 2 64 SAMPLE PERIOD 1 2 3 4 5 6 7 LENNOX: SANTA MONICA: Ir....,...... ,...,,. r•r.,....,--,..·,----,...... -...-,.-,-, ,-. •-~·•·-, i t t < -~. ~: ;~·~~·~-~;!"I:-,::~. ·- '4., ,_. ,_,,, •111111, r;• ... (II, - MALIBU: 'f t f •-,. -, -, I I -~~~· l'~,...,_R0-'2 ::l, z·.i, 7':, BURBANK: SF6 Tracer Release Times: 9/21/75 9/22/75 0300-1705 PDT 0300-1140 PDT SF Scale= Oto 60 ppt 6 Test Period: midnight(9/21/75) to noon(9/24/75) Figure 46. 65 SAMPLE PERIOD 1 2 3 4 5 6 7 THOcrSAND OAKS: snu VALLEY: STIHICNNO, S •~•r-.··--r·~"'T"·t•-, ,l RESEDA: 5HHION Nl'I. STAI 100 NO .,,:[r~T ., . ' NE'i'lHALL: SHH ION NO. STRT!ON "I!!. SF Tracer Release Times: 6 9/21/75 9/22/75 0300-1705 PDT 0300-1140 PDT SF Scale= 0 to 60 ppt 6 Test Period: midnight(9/21/7S) to noon(9/24/75) Figure 47. 66 at any station. However, in the second period, the afternoon and evening of Test 1, an inland tracer plume moved through Thousand Oaks at noon, Reseda at 1400, and into Burbank by 1500 PDT. Concentration levels were on the order of 20 to 30 ppt SF6. On the coast, at the same time, a plume passed through Malibu at levels of 50 ppt, apparently missed Santa Monica, and, at low levels, hit Lennox around 1300 PDT. In sample period 3, SF6 was detectable only in Burbank where it was clear that significant levels were present until 1000 PDT. Tracer released during the morning of Test 2 was first detected at Malibu around noon and also at Santa Monica and Lennox. Peak concentration levels ranged from 43 ppt at Lennox to 16 ppt SF6 at Malibu. Low SF6 concentrations were recorded in Burbank during period 4, beginning at 1700 PDT. No data were taken at several inland stations due to a combination of sampler malfunction and poor communication with MRI concerning the release schedule. After the second test, all functioning stations, except Lennox, showed no significant tracer levels. During period 5, in Lennox, what appeared to be the last portion of the Test 2 plume slowly disappeared around 0400 PDT. However, at the end of period 6 and in period 7, approximately 16 hours later, a concentration pattern characteristic of earlier plumes, appeared at Lennox and then decayed. No other station exhibited this behavior. The peak concentration recorded by this reappearing plume was 29 ppt SF6. Overview maps of the hourly averaged tracer data are given in Figures 48-54. The twin plume pattern described by the traverse results is confirmed during sample period 2, Figure 49. The inland plume can be seen along Highway 101 in Thousand Oaks, Reseda, and Burbank. Coastal transport is indicated by high SF6 levels in Malibu and Lennox. During the morning of Test 2, Figure 50, only Burbank exhibits appreciable levels of SF6, presumably the last OXNARD TEST NO. 1 ◊ 9/21/75 SAMPLE PERIOD 1 ONE-HOUR AVERAGED SF DATA~ SANTA 6 B;.RB_ARA~ ~ ~\, ~ ~ ··~" ~... 8 ----fl :OASADENA ORMOND ...-;.;.:_-:.:_"-~ BEACH GENERATIN ·11 STATION m ~~ '-.I 5.t.':T.t. CRL'Z IS~A,VD ~.,c()9 ANACAPA ~.:_-.t"."'!.. !Sc AND ' 2 =--··.··\ I LENNOX ~~••:~_'!_ SCALE 5 0 10 15 20 MILES -~~ 5 0 5 10 15 20 25 . 30 KILOMETERS -=-=--- ... ==- 0 LOIIG BEACH ...1-,3/---y".·~L,;,=~~~~ . -~ ~ ~- ·.,, TIME SCALE= 12:00 (midnite) to 12:00(noon) PDT~ '-~--~, ~ ···~~ S F6 SCALE = 0 to 60 ppt * RELEASE POINT SF6 RELEASED: 3:00 a.m. to 5:05 p.m. PDT (9/21/75) Figure 48 OXNARD TEST NO. 1 ◊ 9/21/75 SAMPLE PERIOD 2 ONE-HOUR AVERAGED SF6 DATA ~ SANTA BARBARA ~ PASADENA 0 BEAC GENERA STATION Q\ 00 ~Ai:)9 ANACAPA ISL4N0 . . .=.;;. ,:;=\·i I LENNOX t.-.,_,._ ~ \ SCALE 0 ~ 10 1$ 20 MILES 0 5 10 15 20 25 30 KILOMETERS oLONG BEACH i: s ~ TIME SCALE - 12:00 (noon) to 12:00(midnite) PDT r? .'\ SF6 SCALE = 0 to 60 ppt RELEASE PO I NT SF6* RELEASED: 3:00a.m. to 5:05 p.m. PDT (9/21 / 75) Figure 49 OXNARD TEST NO. 2 ◊ 9/22/75 SAMPLE PERIOD 3 ONE-HOUR AVERAGED SF6 DATA~ SANTA BARBARA fl 7 PASA0£1/A °'\D ~ r~ ~- j, SANTA CRUZ ISLAN~ ~j609 ANACAPA -::.. ... ~ ISLAND ,: 2 ◊L£NNOX \ 1 I SCALE ' 0 5 10 15 20 "41L(S ~.. 0 5 10 15 20 2~ }O KILOM(TERS oLONG 8£'.!CH YJ.,? TIME SCALE= 12:00(midnite) to 12:00(noon) PDT ~~- ~ '"" SF6 SCALE = 0 to 60 ppt ·,. ... * RELEASE POINT SF6 RELEASED: 3:00a.m. to 5:05 p.m.PDT(9/21/75) 3:00a~m. to 11:40a.m.PDT(9/22/75) Figure 50 OX NARD TEST NO. 2 <&- 9/22/75 SAMPLE PERIOD 4 ONE-HOUR AVERAGED SF6 DATA~ SAi\ -~ 8AR5.J '.J ~ 7 ~ ~"", ~ --- . ~-- 1 8 PASADENA ~·:•:.-"""'·~ II -...J ~ii()9 ~SAt✓ TA Cf?LZ ISLA-VC , ,:,NAC/.PA :~"""" ·,,~ 2 1SLAAD :04,_ - \.: .• -- LENNCX \l I . \ --~. SCALE \ ~ 0 10 15 20 M1LES --=---=----~ 0- 5 iQ :~ 20 25 ,o KILOMETERS ' oLONG BEACH ~-----~--- _:~:---=-- --:::::::..-::~ ~· . ---~--~~•·.,,,·.~· -·~ _f --,,_"' TIME SCALE = 12:00(noon) to 12:00(midnite) PDT ~ .. . \., S F6 SCALE = 0 to 60 ppt " * RELEASE POINT SF6 RE LE AS ED: 3 : 0 0 a. m. to 5: 0 5 p. m. PDT (9 / 2 I / 75 ) 3:00 a.m. to 11:40 a.m. PDT (9/22/75) Figure 51 OXNARD TEST NO. 2 ◊ 9/23/75 SAMPLE PERIOD 5 ONE-HOUR AVERAGED SF6 DATA {s SAJ\cA N ~.· ~~. ~~ . ~ '7 ! ! ·~ \...._, \ \ \ '-.!.._>- ,ere,r?::--..tf ... 8 PASADtNA ORMOND* h.3~1 J-..-.v-- ·~··"'.::~ BEACH l GSENERATIN~. !I TAT ION ~< -...J I-' • 'sANT"- t.'CMC';y ~:~~~, . ~ C.'iLZ l5cM,Q/ ~.e-<)9 ANACAPA ~2 ~~ ISLAND \ \ \ \\·: .· I LtNNOX ~~ \ \ SCALE <----=-==-.....----=--- 0 __- 10 15 20 MILES ~ 0 '5 10 J 20 2~ 30 K,LOMETERS ..:_.-;__at-:-~~---::-.::·=---=-_.:..:__~_;:-- ( ",,{,,{], o'O:'_ 8',CH .,..~....,,'~.,.~.~}·ce..;:;::.c,· ~"-,, TIME SCALE = 12:00(midnite) to 12 :00 (noon) PDT "· ', SF6 SCALE = 0 to 60 ppt ' RELEASE POI NT SF6* RELEASED: 3:00a.m. to 5:05p.m. PDT(9/21/75) 3:00a.m. to 11:400.m. POT(9/22/75) Figure 52 OXNARD TEST NO. 2 ¢ 9/23/75 SAMPLE PERIOD 6 ONE-HOUR AVERAGED SF6 DATA~ S~VTA -,_3~~ N I -~" ti ! ~ ~ ~ \ H PASADENA ORMOND' '-I BEACH N GENERATING STATION ~ ~¥)9 1U:,1CAPA IS -~ND 2 \-~. - I LENNCX •:- j \ SCALE -- '~ TIME SCAL;•=-~;:~~(n•~o~) ;,to ,I:~~~~ (midnitel PDT~✓{;;!iv~'.~ SF6 SCALE = 0 to 60 ppt - ' RELEASE POI NT SF5* RELEASED: 3:00a.m. to 5:05 p.m. PDT(9/21/75) 3:00a.m. to 11:400.m. PDT(9/22/75) Figure 53 SANTA ONE-HOUR AVERAGED SF6 DATA BARB~ ~ ~"""" 8 PASL. ✓ Et,h --..: 0 w BEACH GENERATI STATION ~-0 ~-.,()9 SANTA~ ANACAPA ~·-,'°;-, _,,,, ISLAND ,: 2 ---/" -:..--•-~;•~ - \--- : --- LENNOX "-: I ~~-- SCALE 5 0 5 10 15 20 MILES -=-:~-===----5 0 5 10 15- 20 25 30 KILOMETE:RS L~ oLONG BU.CH ..::JI!" .•- ..=..----::.=---:-.:::===--:-.=.--=-=- ~ \ ~' > ~ Tl ME SCALE = 12 :OO(midnite) to 12:00(noon) ~ ~~ ~- SF6 SCALE = 0 to 60 ppt * RELEASE POINT SF6 RELEASED: 3:00a.m. to 5:05 p.m. PDT(9/21/75) 3:00a.m. to 11:400.m. PDT(9/22/75) Figure 54 74 remnants of the Test 1 plume. In Figure 51, Malibu, Santa Monica, and Lennox data provide evidence of coastal transport during Test 2. Burbank was the only operational central, inland station; low tracer levels were observed there. In the remaining overview maps, the Lennox samples, alone, show SF6 present. 3.6 Forward Surface Air Parcel Trajectories In order to compare the automobile traverse data and the hourly averaged data with the meteorological data, hourly wind streamlines were constructed for September 21, 22, and 23. All of the available surface wind data were treated as hourly averaged values. In some instances, single observation values were disregarded where there was sharp disagreement with hourly averaged values. Upper air wind data were not used in the development of the wind streamlines. These hourly streamlines and the wind vectors for each station were used to develop air parcel surface trajectories beginning at OBGS for six release times on the 21st and four release times on the 22nd. Each hourly movement was based on the two appropriate hourly streamlines (as explained in W. J. Saucier (1956)). The results of this analysis are shown in Figures 55-64. It is important to note that no wind data exist for large expanses of the ocean; streamlines and trajectories were subjectively constructed for ocean areas using nearest data points and the overall flow pattern. Some of the most striking features to be noted are: no matter at what time the trajectory was started, the path ended in the Ontario area. Some of the Ormond Beach releases milled around the San Fernando Valley for many hours before exiting and continuing on to the Ontario area. Some of these releases left the San Fernando Valley, got caught up in the land breeze and meandered off the coastline for a few hours, came ashore with the sea breeze in the early :-. ~~ -- ~o ~ ~ 0, o r::.:J~Y:~ ~ -- r. -~1u0 ~oO '11·,~ o~11 o (I&...... _•--· ...--~ ·,2...... ~ oq 10 11 o:)o lOnQ <.n \ 0 21/0300 - 21/1600 PST, Sept. 1975 Forward Surface Trajectory 21/0300 PST Orment Beach Release 0 Scale: 24.7 km/in ~ "' Figure 5S-. ~ .:::-1~:~.~::i\s:~.....~------:----~. ~ t··.f'':x:~r~.· .,_.·_·...... ·..... ~ , - - ...~~,:':.,..!_· '.i'----soo -- ~· 'OQ ": l::::, · ~ V l~_.? - '--"..rJ '10~ L I.J M ~ r--- ~ )\ '-.'-1_)', J1 O 0 ~---'""1-i - ... _,.,. 0 0 0 17·-~-- n/tl - 0 ~oO ~----0~ 0 ~ •!/" l \ -~o / /0 ~~ IO• _,,, 0 L/°'c,Clj 21/0600 - 23/1800 PST, Sept. 1975 0 Forward Surface Trajectory 21/0600 PST 0nnond Beach Release o"" ~ Figure 56. • -· ;:;,,-:-:-e ·- ~ ------· --- ·------_;. >itt:11 1 \ \ Lr,\J ✓ c JJt 1 ' --.J • (/'); •.'-)· '-·r- <- v •. \ ' - ·1 J 1° · - ·• , - , :-i ·' 1 ·o ~ (" V·'Ooo 0.'• 2-2£gc'.' . "',, v~ ··1 "· .r------•-,<:i '-- 1.s,u .,· ...:a _ ./o/ "__;,-P ~~ t ~< _(',<._ f.J o L ..---3 '1-· '-.._/ -.,,.-~',_ __J'-.., .--- \ "'-.J /_ 1/;~ , ·" . '--.-') , ,1\ , ,r r , Q. '·-? 1 ~c__( • V -- ~ '/[•.;, c::::__ ..) 1/7' \/•>' '·uo;,- ,,-'.C,-.. ( I C='.:::, , S i :,;i( c , A - --? - rf.-o() -:;, n< ...!'.' •• ,.r j _,..I~-~ ··-2::-~ •~ ,I ,_.__\_,,;:-::::::,.':'_(J ~ r~ ".', . "\'Woo _f /-;_;------.;:::>c:'10Qo>::25QQ ~--?~q, c<____;:,) ~on,I \1! r-C, 'J '<.._ \ ~ ------=. ,_ . -----.. c:' ,.S V~ ,, ! •.. ~c-, "'-vi -- ~ · ------~0-~------~ ~ J ("?)' ~ . ,~;F, ~'Jl,, o _ ~ ~ (}~ 'v' i,.,J o ...,._.. 11 Figure 57. ((). '~-~- ..~-;_~-:,,-W~~~~~,:••·:;.··.;,ev~· ) ~~/]~.. '._ ..... ~0- ~ 0 0 0 -· 0 21/rz. · - " oc.·~ 0 ~- 0 , ~ ~oO 0 ~\-_-./•11 ~~~ ~::~ 10 II 0 ~ 100a '- ~ 0 ~ -,·--{ ... • 21/1200 - 22/1500 PST, Sept. 1975 0 Forward Surface Trajectory 21/1200 PST Onnond Beach Release 0 ... ~ Figure 58. "' -~':~ ~ --- -- _____'j.~ \ ,;-~ \ ' ', I '. L,: ,· ,( ) ' :_, ' .•-, '--'· ,·, ~- / ( . ' ) . ' ' \ ,'(: . , (' . ·• : <'- -·• ) ,~.•. J ,, /, _j '-.... \. \ \ \, J ; \; I ./ 'Oc ·rr\·oO ' • l ,. ~ ' .,, ,, " ' •·,, ·, , , - D (\ ~ I .,. ( • . I ·-- Lr,.-:_ J"-, "•>' j ,, /•. 'o' - ~" f0} ., :.,, '> , ".'., r,c, ,.,---,( 0 \ -, \_' __,,., _) --~ · _, -~- \. ) ''---J-- i c;· c. 1 '-L_.., I / , ' \ ' , / ,._ , • -· > '\' _j . ' ' •-,·, ' . ,_ .. ' . . , l -- • - . ' ) ''✓ : ' ' l , .. / , ' ' ·- 11 )(. J •-, : , c - \ ,, ✓:, ·,,: '- j 00() -'\,,,, " c: , \c::· _, i'J CJ {/ (; 500Q, ) -, .._\_,,,j,,.f_J l ' ;::_?'--.) 'j',J' " 1,·•/, ·)'ir' :• -~Ooo,_ ;; r-··. - \'--::::,f,\ \ n,l · --'l?,.--.__;,.,, - "'\ ✓-7 ~ '. <,· . ' , . I, ,,C, ~ "·' ,-,-,,_,_-.,_. ( l,,1 ('-_1:-<.J_,,.~,uu ; f\i;v \) ( ,.;? ½ .11 · 11 · _,,. ,---;;::, C>-. r-,. '::, ..J \~ . · ? 0 '.,,Jv--,.,_.;;::.; 0 c'_J1r1~ \.-v( " 'WV o , o ,1---- <,,O_u ,-,.., ." o r<:-r 01 0 0 o ""'-nooo o ~ 'Q.. o ·, I . "· o o _) ['' \ S. f\, '-"CJ L. ~'.) Q O/'3 ~ <- \r rJ /'J. r.:: --.....__) - 5"·' 12 140 ' I \ "'0C {,r-----~- j'_ ,,, o.(\,v ,::1/£1n ' u.Jts • \ r-:.::..:.::..:__ -"' t ..... /-.___/"1 --.....,~ .. _,__ - --:·0 I z1/1s "~~~tf.,1000~LJV o"~,. o / __,' ) -, (" . ~~ --- ' •'b-, :::.,~ ~:-.::.------C:::C:.c,0 \ ~1C'o .'- ] -~\• _....--· '" ,1 ~..::..c:::--. - --zo • 2J ••',, ..r.--_,, ,.-,,,-;,, ,_, II .,_',ooc:i '\';:') "'r· \ -...... __.....,/' -/ ,i l'-i t\ cl) ~~' \ 0 O ~ ~ o O ~~C 0 ,- ' 0 o~i o- 21/1500 - 22/1500 PSTt Sept. 1975 Forward Surface Trajectory ~ 21/1500 PST Ormond Beach Release '-"' ,\ 0 ~l)-, ~... ''cJ\,. .:.._!;:.:> 9-n ~---:'--.1,, ~ --····,:::::::::_.1 " \ '·,\ --,_Ol Figure 59. ,,..._ j 'y}1 ,,,; \/__,-), -~ /j(~ ' ""v [:-,:, \~ ( , , ' \, ',,, 'J '0 \ vz '-,'----s,(,I ( ( 'lo , >, ·,. ·-i., 'v 'r,,, , : -.., '' ., j ..- Ooo ~ ,(_,,~ 0 /? 'l '--~,_,....·-,. ·~· ··,r 0 0 0 ~ () ( 0 0 0 0 10/00~13'1-i:~.~ <,Ai'\l-o'', ~ o ~ -"-z.t¥ 0 ~~cc::, 12 \, --"' o cl 1;l-,y,,I\.( ~ _,.,_ .~~ .;--..____ ~0 ol r:::;:->-- 1 ',:---> ,,---__ 21f,1 :/) - 'IOOO_o---;-:.: ) 0 0 c--... 21/1700 - 22/1500 PST, Sept. 1975 0 Forward Surface Trajectory ,.:·-, "-'.:~\.__------:::--,_ ' 21/1700 PST Ormond Beach Release , Q'\ 0 ~ ~ ~ ~ Figure 60. r,-., ' \ I ·, ,•n • . 1 ,, '-' \ I . \\ l,, ,,., '" ','•••✓r•) ,. \ \r" ,,,._ I(' ,,. ,,, '' ✓, ,•, , ,, /() .I '------•· , L-\ , ' Jc ' ,300 0,, ""~ ' ) '\_ ',,,. \., ' ! ',' ' . ' . ,. ', J ,/ •'001)· (' C:\ ' --, ~ · •,~ I ~. , i , • , > , • •. ' -., · •, , , ';) '·-~ . ------.. ··---r·,) ,_ l \;,_, ,_, . _, . / ,·7; .-~)\\, l c_,. ( , ('.1. <:) 1 1 . '/,, J ' J .. ,_ \ ' ·~ ~' ,;---9.;;·~ ~.2soa~t;;;i7, •--- ~o ~~~·ocD:utf;~p•~.S1000 ',fO -o/11 ~- 0 f\ ''-\ • ,'.Jf, O O • ,J::=, o ---:::: 22 01 0 / f"::' '0 ,, ,,N '5 2 ---, ~),) 2 °'·* n (~-::-::_-;:.___ · , d ~--- 'I !\S /'S' ~~, 0 oa ___,._,.,,,,--, ) -._, '.:.:.,i'-. (-~- 1°2. ·t{?t ..____~,'/) .1000I\) ,~. o • (\:; - I \._ .,,o.~,, .-:-=~i!J I ~l ~ ~'::-:!__/ ___ ---- O \ ~)ro "7 o,s "·0(. '•~- --:::::-et~.------•-- • -,,.--·----oI ,, o ,. ~4 2.10~0 ~ ~,,,-, ,~o0 M1 ~ d1 . k•o.~,..3 0 0 11• j 0 •oB 12 ,. 0 ~7... ,)J"" ~ ~ o In c.; 0 22/0200 - 23/1700 PST, Sept. 1975 0 Forward Surface Trajectory \ ~ \'---~ 22/0200 PST Ormond Beach Release -~~ ~O\ , I ZJ'-, 0 --'I., Q..o c-- '~)) ~ ,~-.-...... __ \. ----... --..___o) Figure 61. ((\ ~-...... \ J' ) u '. I -· \, -\,- -"',_ - ; ' --, '..\r-·. - , 'J- -,, ,,',..·-'O - \ \ '-,, '\_ - - \ ' ' -) ; " ' , ' ;-- ' ,_ ,J1, , ' .,, <-· .-,o·<~ .... ,- \ 1:; ·-- > -. -~-. _, · ·, i_·-,. • 1· c.) 1 ./f Oc,,1 ,---.. ,-./\, I " ' ' ' -- ' ' u' ,, ' ' ' ' \~ --c., ·,_ --.)\.",,./ ' -' -' . '' -·, .... ' ~\ -')·'" <,_ --•,,- .., .,,_,\\ ? ~/,,, 1':', r:· 0 (.J ·, , -·, - ' ' -,f \ \'-i__ , ' r. ; "' l '~,-· ' , , ,<:::,, J'')''•o ( < / -, --, '-,• , _ ~ <::,<\ \ ,- < , ,r,, ) \, (,! , ;, ,-1 rl ,l -) ·Oo')-- -- ~----- '\ '(-:.~-' _,, r' f c~J- ~ ,.,,,, VL. '-,, '-->'•,,, i; ,,<,• ·,,," •·.//(,.,. 1 (_,,,_"> JS,;c:.oo Q __.5 - ---.' __,_,_ ·L _; ·-.\ ·, -/._,_/_, , < 1'D' ·1 --~- ,v "'vJ , -·"'- ~::;::,---- r,; c: •-.. r, r·- •,' ' ' --- :,_,' ..,,.."-cw-,' ' '. " )\ \a""' ',f','" , '\ °" Ir"'.', t;i~ .,._ '\ / . .,---.------c/100'------·)ro;::---, u·~ <,. ' , I-' ------.- r·___,,-:55--~------)/ , - '(._:::..___.-, ..)/ ,-Lz __,..1(\er- - 1)l .._,J,,. (') __J/ ..~A re -- ~ . -- . , ' ' , r t-.. -, hl · ------'--'o-.,__,,-- --~._::~'-..._) C-1 ~vv ·-g ~ ~ ~~ ~ c:: \,__ <.,_6 I , ~ ':,------._,, r-.::;J C ~'w, [.-. ,,__,,_ r'-;----, ~ 0 0 ' ,- 0 1 OG~...,_4-.,~-~-~----~Soo -.../L.----- v t;q)' '~- ,o "~ --- - •= o ~ 1 o • - :0'00..:1 ·.. IS ►e/u. \ \_o o r:;-:c->~ c--. \\' V-0'-r.,..,,c:; - "'-,.18 0 0 " o 14- ~;---,____ O 0 ----::, .._,~/15U, ~:-;-..o.,o - s u,,.. \:::;:_~,,(.? 22/u.->,/~f\'.\... ('·,1;,, /N • , c:,'~n O '--- r---._ -,-·-- ... __ ,,-·, ... , ' tX> \'' ·- C-1\/,~ rv ....__,..,.,,___, , o ,,....._~_.,,,,.-, ...... ___c- ' ---- ' ''-- .!1 \ / 0 ~ ---- I ·::c.o0 --. • ~--- .___, JOQQ 0---::x: Q Q CON '-. ' ·, · ...___ ,- ---- 0 0 t)r 7 (:~~~:/-~~'.~~-- ./ 0 / __ ; ,1 '--;--... •~..-- ii. M -10~ \ ,_...... ,-,,.. ' " /1 \oi O c;v~~ ) o O ~~~ ~On~?, 22/0500 - 23/1600 PST, Sept. 1975 0 Forward Surface Trajectory 22/0500 PST Ormond Beach Release \\~~)- ___ ~ ~-Q), 0 •.1' ''Q\, ! .:2,, Q..o ~==-;-~?) c-,,.,...______~ \_~~) Figure 62. ,..,.._ 0 0 . CV') c..o Q) s.. ::::, .....01 LL. LO r--.. Q) I' O'I V1 (/ .-t n:l Q) . ,- (9 +-> Q) ,I I 0. >, 0:: QJ s.. V') 0 .c ~j +-> u .. u n:l I Q) Q) V') .,.., OJ c.. n:l s.. "O 0 I- C: 0 0 c..o QJ E ...... u s...... n:l 0 (V') '+- N s... I- ::::, V') V') c.. 0 "O 0 0 s... 0 0) n:l 0) 0 3 0 ...... s...... ,,_,, N 0 N N LL. N 19!t, ~7 t!tll I ~t~.-r ) ~~ ~-io . ~· ~ ~· :so . -- - Rll --~ ',;. 0 V .,,.,,. ,, 14- ~ 0------....., 0 0 ~ c:_ ~ Tu'~ 22/1100 - 23/1600, Sept. 1975 Forward Surface Trajectory 0 22/1100 PST Ormond Beach Release ~~ 0 ~ ~ "" Figure 64. ' C~\ 'I ~· __,._. A - 85 afternoon and then joined the other trajectories on their way to Ontario. Other releases managed to go directly from the source area to the vicinity of Ontario, so that all of the trajectories impacted the Ontario area during the late afternoon hours {1400 - 1800 PST). Depending on the initial "push 11 at Ormond Beach, the surface trajectories: (1) went offshore before turning to the east, going on shore near L.A. International Airport {far enough south to bypass the flow turning into the San Fernando Valley) for a direct shot at the Ontario area (e.g., 21/0300 PST); (2) hugged the coastline, passing Malibu on the way into the San Fernando Valley, where many hours were usually spent meandering- sometimes even back to Ventura County's upper valleys--until, if they were close enough to the mouth of the San Fernando Valley, they were caught up by the land breeze to go offshore for a few hours and then return with the early afternoon, Ontario-bound sea breeze (e.g., 21/0600, 21/0900, 22/0200 PST); (3) after meandering in the San Fernando Valley, as in (2) above, several of the trajectories went directly to the Ontario area (e.g., 21/1200, 22/0500, and 22/0800 PST), showing that just a small displacement during trajectory construction in the San Fernando Valley can show quite different intermediate results (i.e., the 11 side trip 11 off the L.A. coastline), although in the end, all of the trajectories tended to be in the same receptor area; (4) went up the Oxnard plain, via the Simi Valley, and then ended up in the San Fernando Valley, meandered for awhile, and ended up in the "normal" receptor area (Ontario) the next afternoon (e.g., 22/1100 PST 86 release time). At times it was difficult to discern whether the initial 11 push 11 would start the trajectory on an ocean or an inland voyage. The proximity of the ridge line* to the source area could also occasionally split the flow into both an ocean and an inland plume at the same time. Whether or not a particular trajectory stayed in the San Fernando Valley for many hours (e.g., as when it was 11 captured 11 by the calm winds at Van Nuys) or came right back out depended on very small distances during the trajectory construction. Although the trajectories were based on surface wind data only, the Ormond Beach power plant plume rise was calculated to be about 200 meters on 21 September 1975. The wind from 450-meter high Laguna Peak was used in conjunction with the 300-meter pibal data to get an indication of which way 11 11 the elevated plume would be pushed : north or south of the Santa Monica Mountains ridge line. On 21 September the 11 push 11 was generally to the south of the ridge line (with some brief 1-2 hour periods of northerly flow in the source area). However, the radiosonde data indicate that the plume was just below the base of the temperature inversion, implying that the shallow surface layer was uncoupled from the overlying warmer layer; i.e., the surface trajectories should be used in preference to data above 200 meters. On 22 September the inversion remained shallow, implying that part of the time the plume went into or above the inversion. Again, the flow would have pushed the plume south of the ridge for the 0200 to 0800 PST release times. At the 1100 PST release time, the Laguna Peak wind would have pushed the plume north of the ridge while the pibals showed a NE flow until 1300 PST. Laguna Peak, etc., of the Santa Monica Mountains 87 Since the winds aloft were usually stronger than the surface winds, any tracer material influenced by these upper air winds should have reached its receptor area much sooner than indicated by the surface wind data. 3.7 The Gaussian Plume Model as an Upper Bound The results of the cry analysis in Figure 45 as well as previous studies (Start, 1974; Liu, et al. 1976) indicate that the simple Gaussian plume model will serve only as an upper bound to pollutant dispersion over complex terrain. However, the Gaussian model may be of use when experimental data is available for a particular locale or for a particular type of terrain. As an example, meteorological and tracer release data from the afternoon of Test 1 were used in the Gaussian plume model to calculate SF6 centerline, surface concentrations as a function of downwind distance. Turner's expression may be written ~xp [- ½(~j] + nt (exp t ½~z + ~ - 2nl)2J + 2nl)2] + exp [ ½~z -~/ 2nln + 2nl)2J )) The tracer release rate, Q, was constant at 4.0 grams/sec± 0.3 grams/sec over the time period from 1000 to 1600 POT. The average wind speed, u, was 2.6 meters/sec. The plume rise, H, ~as calculated according to Briggs {1969), (1972) to be 198 meters. The tetr.is in the summation are used to account for the reflection of the plume ~t the bottom of the inversion layer. The inversion height L was 244 meters taken from LAX data. 87A Centerline concentrations for two stability classes and two sets of dispersion parameters are plotted versus downwind distance in Figures 65 and 66- The automobile traverse centerline concentrations and the maximum hourly averaged concentrations for the first release day are also plotted. The higher curve in each figure was calculated using oy and oz as given by Pasquill-Turner for flat, open country. For the lower curve, oy for both stability classes was taken from the experimental data 1 116 (oy = 0.0415 x · ) while oz, modified for a surface roughness of 50 cm, was taken from Liu, et al. (1976). In each stability class the Gaussian model with Pasquill-Turner parameters serves as an upper bound to the data. The curves adjusted for the locale with the Oxnard and Liu parameters more closely predict the data. The data falls between the class C and D curves. For modeling purposes, the class D curve yields a close upper bound to the prediction of downwind concentrations. An important feature of the plotted data is that both 10-second and hourly averaged values appear to lie along the same curve. Hino (1968) has suggested adjusting concentrations for sampling times using the power laws: for sampling times less than 10 minutes and for sampling times between 10 minutes and 5 hours. 106 ATM. STABILITY CLASS C 105 A 10-SEC AVERAGED C~NCENTAATI~NS ~ H □ URLY AVERAGE □ C~NCENTAATI □NS 10y (5~) PPT. OJ 103 co 102 (!) (!) 10 1 20 4:0 60 80 100 D~WNWIND DI5TRNCE CKM) Figure 65 10s RTM. STRBILITr CLASS D 105 ~ 10-SEC AVERAGED CONCENTAATI~NS ~ H~URLY AVERAGED C~NCENTRATI~NS 1011 (5~) co PPT. I.!) 103 Pasquill-Turner 102 ,t.A A (!) -"Oxnard-Liu A (!) (!) (!) 101 10° I 0 20 40 60 80 100 ODWNWINO DISTANCE (KM) Figure 66 l l 90 Applying these corrections to the traverse and hourly data would yield a plot with concentrations appearing to increase with downwind distance. It is apparent that Hino's correction should not be applied to the experimental data. Hino noted, however, that for experimental data from very short sampling times the relation between concentration and sampling times varied widely. 3.8 Pollutant Dilution Factor Calculations The SF6 injected into the stack becomes diluted along with other stack gases by atmospheric turbulence; SF6 concentrations measured at ground level downwind can be converted to equivalent ground-level pollutant concentrations associated with that particular stack. Thus, where CP isthe ground-level pollutant concentration, Cp{stack) is the stack- gas pollutant concentration, and CSF and c F are corresponding SF 6 5 6(stack) 6 concentrations. The ratio of the SF6 ground-level concentration to the stack gas concentration can be defined as the dilution factor, OF, characteristic of the particular stack and test conditions. 91 The DF values calculated from the maximum hourly average concentration at each station are listed with downwind distance in Table 15. These calculations are based on an average SF6 stack concentration of 1.6 ppm for Test 1 and 1.0 ppm for Test 2. Generally, pollutants emitted during Test 1 and Test 2 were diluted by approximately 105 after transport into the Los Angeles area. No pollutant stack concentrations were made available by SCE for the Oxnard tracer tests. If, for example, the so2 levels in the OBGS stack were 200 ppm, the tracer data indicate that downwind so2 concentrations due to one stack would be 2 ppb, hourly average. Concentrations of so2 compiled by the California Air Resources Board during the Oxnard tests are listed in Table 16 for selected sites. There is almost an order of magnitude difference between measured so2 levels and the estimated levels due to OBGS. In this comparison, so2 is assumed to be nonreactive during transport. If reaction rates are known for so2 or for other pollutants, reactant and product concen trations can be calculated using the dilution factors. 92 Table 15 Dilution Factors from Hourly Average Tracer Data Location Distance Minimum Dilution Factor (km) Test 1 Test 2 Thousand Oaks 28.3 1.8. 10-5 0.5 10- 5 Malibu 46.5 5.0 · 10-5 1.6 10-5 Simi Valley 46.7 0.7 · 10-5 0.7 . 10-5 Reseda 62.4 2 .1 · 10-5 1. 2 • 10-5 Newhall 66.4 0.6 · 10-5 0.4 · 10-5 Santa Monica 66.9 2.3 · 10-5 Lennox 78.6 1. 4 • 10-5 4.3 · 10-5 Burbank 84.0 3. 3 · 10-5 1. 9 • 10-5 93 Table 16 Sulfur Dioxide Concentrations Station Ave. [S02], ppb Maximum Hourly Average 9/21 9/22 9/23 9/21 9/22 9/23 Burbank 14 13 11 20 1400 20 1700 20 0000 West Los Angeles 10 16 11 10 0000 20 1300 20 0100 Reseda 11 10 10 20 2000 20 0000 10 0000 Lennox 10 24 37 10 0000 60 1600 80 1300 Newhall 17 10 10 20 0000 10 0000 10 0000 Downtown Los Angeles 14 23 25 30 1500 50 2000 40 2300 Pomona 15 14 15 30 1400 20 0000 30 1600 Redondo Beach 10 13 40 10 0000 30 2300 110 1100 Pasadena 20 19 17 30 1500 30 0800 20 0400 94 4. Summary of Results 4.1 Transport Paths, Pollutant Buildup, and Slosh In general, the traverse tracer data and the hourly averaged tracer data yield the same picture of transport paths during Tests 1 and 2. The results indicate the presence of an inland SF6 plume and a stronger coastal plume. Traverses close to the source defined a Gaussian plume directly east of OBGS, and later traverses measured its path along the coast into Santa Monica. Inland traverse data showed significant SF levels reaching as far north as 6 Moorpark and as far east as Highway 27 at the southern edge of the San Fernando Valley. Hourly averaged tracer data confirm this description. Significant levels of SF 6 were found in Thousand Oaks, Reseda, and Burbank as well as along the coast in Malibu, Santa Monica, and into Lennox. The air parcel trajectory analyses support the traverse and hourly data. As previously noted, the most probable initial push moved the plume mainstraam south of Laguna Peak for transport parallel to the Malibu coast. Inland concentrations probably resulted from momentary changes in the initial push direction at OBGS and, perhaps, from SF6 buildup off the coast during the night and morning hours. The large spread of tracer from the coast to Moorpark indicates buildup might have occurred. If all of the tracer detected north of the coastal mountains resulted from tracer buildup, tracer and pollutant concentrations due to this cloud were almost as great as those occurring within the primary plume along the coast. However, the trajectory analyses for early morning releases do not trace parcels moving off the coast and then returning to the Oxnard plain. Rather they show parcels looping out over the ocean and then moving eastward along the coast. 95 The wind trajectories suggest reasons for the slow disappearance of tracer in the Burbank area. In most of the trajectories, the air parcel became trapped in the Burbank region and did not move out until sometime the following day. In view of these movements, slow decay appears reasonable. In at least one case, air from Burbank, upon moving out of the area, was swept back towards the ocean possibly moving over Lennox. Such behavior might explain the presence of significant SF6 concentrations in Lennox during the last three sampling periods. However, it seems surprising that the levels seen in Lennox would be entirely due to such well-traveled air. This 11 slosh 11 pattern is similar to that examined by Giroux, et al. (1974) for the area immediately downwind of OBGS. They reported that SF6 concentrations decayed fairly fast once a release stopped, and thus concluded that inland pollutant buildup due to sloshing was unlikely. This appears to be the case in these tests; at Burbank meandering winds apparently increased tracer decay time and at Lennox land breezes transported tracer back out to sea. 4.2 Dilution Factors and Effects of Terrain Under the conditions of Tests 1 and 2, increased horizontal dispersion, probably due to the effects of the rough terrain downwind of OBGS, resulted in dilution factors on the order of 10- 5 for the areas tested. Such values are lower than those that would be predicted using the Gaussian plume model. No data are available concerning terrain effects upon vertical dispersion. Under the shallow inversion heights encountered in these tests, the terrain most likely enhances vertical mixing so that the vertical concentration gradient becomes constant at relatively short downwind distances. Raynor, et al. (1974) in a study of dispersion over the sea concluded that diffusion over water differs appreciably from that over land and is 96 largely determined by the air-water temperature difference. During stable conditions diffusion over water is much less than over land, resulting in concentrated plumes far from the source. During unstable conditions, diffusion approaches that over land. In the Oxnard tests, traverse and trajectory results indicate that the plume mainstream was transported over portions of the ocean under slightly stable conditions. However, with no over-water air samples available, little can be concluded about the effects of the over-water transport on the OBGS plume. The Gaussian calculations serving as an upper bound suggest that most of the dispersion involved transport over rough terrain and not over water. No dispersion data were obtained covering other meteorological stability conditions. It is not clear how close the test conditions were to worst-case or to typical conditions. Class D conditions prevailed during the tests; the frequency of such conditions in the Oxnard area is not known at this time. Because of the long release times covering both land and sea breeze conditions, no differentiation between a possible SF6 cloud impact and direct plume impact can be made. While the path and impact of the primary coastal plume is clear, the impact of the secondary inland plume could not be separated from the possible impact of a tracer cloud caused by night-time offshore buildup. 4.3 Conclusions In summary, the results of this two-day tracer release clearly show pollutant transport occurring from the Oxnard/Ventura plain along the Malibu coast into the Lennox area of the Los Angeles basin and by an inland route into the San Fernando Valley as far east as Burbank. The trajectory data suggest that transport along the coast also moves pollutants into the Burbank region. 97 Trajectory analyses, unsupported by tracer data, indicate all easterly transport finally impacts in the Ontario area. Pollutants emitted from the Ormond Beach Generating Station under the test conditions were diluted by approximately 105 after transport into the San Fernando Valley and central Los Angeles Basin. This dilution range is greater than that predicted using the Gaussian plume model. It appears that the mountainous terrain east of the Oxnard area increases horizontal dispersion over that expected in flat, open country. The results of these effects are to lower downwind concentrations and to decrease pollutant impact. No assessment of pollutant concentrations could be made since pollutant stack concentrations were not available. It appears possible that offshore night-time pollutant clouds can form and then be pushed inland with the daytime winds. The impact of this kind of cloud relative to the impact of an inland plume or the impact of a coastal plume was not determined. Pollutant slosh over the inland regions possibly occurs, but does not appear to cause inland pollutant buildup. Meandering winds over Burbank slowed the disappearance of tracer material, and land breezes transported pollutant back over the Lennox area. These two conclusions are based on the nature of the hourly average data and the constructed trajectory paths. It is quite possible that some other mechanism was reponsible for the nature of the data. In any event, no buildup of tracer material was detected; slow decay and possible reappearance of material was observed. 98 5. Recommendations Future tests should be designed to cover a larger range of meteorological conditions aimed at worst-case and typical impact conditions. Information concerning the dimensions and dilution effects of offshore, night-time pollutant clouds could be obtained. More detailed descriptions of over-water and over-land transport between the Oxnard/Ventura plain and western Los Angeles County would result from appropriate tracer releases. In particular, specific transport paths into and out of the Burbank region could be determined. Further study of terrain effects should include analysis of vertical dispersion as well as horizontal dispersion. The position and effect of the shallow inversion layer would be important in such studies. Finally, work in this area should include an inventory of current and future industrial and urban activity on the Oxnard/Ventura plain, in the San Fernando Valley, and throughout the central basin of Los Angeles. Such emission studies, when coupl~d with long- and short-term meteorological analyses, could be used with transport and dispersion data to provide a better understanding of the relationships of pollutant impact between Ventura and Los Angeles counties.