ENGINEERING RESEARCH INSTITUTE THE UNIVERSITY OF MICHIGAN ANN ARBOR Final Report AIR-POLLUTION CLIMATOLOGY NEAR MONROE, MICHIGAN E. Wendell Hewson Professor of Meteorology Harold W. Baynton Research Associate Project 2442 DETROIT EDISON COMPANY DETROIT, MICHIGAN March 1956

- ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE OF CONTENTS Page LIST OF TABLES iii LIST OF FIGURES iv ABSTRACT v OBJECTIVE v TOPOGRAPHY AND GEOGRAPHY 1 WINDS 1 PRECIPITATION 12 TEMPERATURE INVERSIONS 22 VISIBILITY 25 POSSIBLE HAZARDS TO POPULATION CENTERS 26 CONCLUSIONS 29 RECOMMENDATIONS 29 REFERENCES 51 ii.

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN LIST OF TABLES No. Page I. Relative Frequency of Occurrence of Winds in Various Directions Grouped According to Wind Speeds 4 II. Relative Frequency of Occurrence of Winds in Various Directions Grouped According to Wind Speeds 5 III. Relative Frequency of Occurrence of Winds in Various Directions Grouped According to Wind Speeds 6 IV. Relative Frequency of Occurrence of Winds in Various Directions Grouped According to Wind Speeds 7 V. Relative Frequency of Occurrence of Winds in Various Directions Grouped According to Wind Speeds 8 VI. Season of Maximum Hazard for Various Population Centers Affected by Different Winds 13 VII. Relative Frequency of Occurrence of Winds in Various Directions Grouped According to Wind Speeds 14 VIII. The Association of Precipitation with Wind at Toledo Airport 15 IX. The Association of Precipitation with Wind at Toledo Airport 16 X. The Association of Precipitation with Wind at Toledo Airport 17 XI. The Association of Precipitation with Wind at Toledo Airport 18 XII. The Association of Precipitation with Wind at Toledo Airport 19 XIII. Presence or Absence of Inversions Based Below 1000 Feet in Relation to Wind Speed and Direction 24 XIV. Relative Monthly Frequency of Visibilities Equal to or Less Than 6 Miles, with Ceilings Greater Than 9500 Feet 26 XV. Values of Diffusion Coefficients 28 XVI. Computed Values of %l/Q 28 --------------------------- iii

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN LIST OF FIGURES No. Page 1. Topographic map of proposed site and surroundings. 2 2. Percentage frequency of occurrence of winds and wind speed in mph from directions shown. 9 3. Percentage frequency of occurrence of winds and wind speed in mph from directions shown. 10 4. Percentage of total winds which brought precipitation from each direction at Toledo. 20 5 Percentage of total winds which bring precipitation from each direction. 21 6. Percentage frequency of occurrence at 2200 EST of winds associated with inversions based below 1000 ft and corresponding mean wind speeds with same inversions from directions shown. 25 iv

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN ABSTRACT The topography and geography of the area near the plant site are described. The average wind conditions as measured at the Toledo Airport are discussed in relation to winds near the plant site, and the importance of local lake effects at the latter is emphasized. The maximum hazard to various population centers as a result of this wind pattern is outlined. The occurrence of precipitation would reduce the hazard to the more distant communities. The occurrence of inversions at Toledo Airport is analyzed and their significance indicated. The results of a study of atmospheric visibility at Toledo Airport are presented and discussed. Sutton's equations are then employed to examine in detail the hazard to communities. The conclusions regarding hazards are outlined and recommendations made for a program of measurements and analyses of meteorological quantities and of concentrations of a tracer substance over the lake in order to reduce the uncertainty concerning the hazards involved. OBJECTIVE The object of the study is to assess the hazard to the communities around the western end of Lake Erie if an accidental release of radioactive materials from the projected plant near Monroe, Michigan, should occur. ----------------------------------- -— V —-------------------------------— AT

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TOPOGRAPHY AND GEOGRAPHY The plant site is located on the western shore of Lake Erie about 7 miles ENE of Monroe. The shoreline in the immediate neighborhood of the site is cut by a series of inlets. The general terrain is very flat in all directions and only a few feet above the level of the lake. The vegetation consists mostly of tall grass, low bushes, and occasional clumps of trees about 40 feet high. Although the shoreline is quite irregular, in general the west shore of Lake Erie lies in a NE-SW direction. Figurel illustrates the topography of the area and the location of important population centers. In addition to Monroe, mentioned above, there are the cities along the Detroit River from Trenton, about 12 miles NNE of the site, through Wyandotte, Ecorse, River Rouge, to Detroit, about 22 miles to the NNE. Directly to the NE, about 10 miles away, lies Canada. The city of Toledo is about 22 miles SSW of the site. But perhaps the closest population center is the group of beaches along the lakeshore from 2 to 5 miles SW of the site. Thousands crowd these beaches every weekend during the summer. At other seasons they are virtually deserted. The topographical contours on the map illustrate the flatness of the terrain with only a gentle rise from the lakeshore. WINDS Two sets of data were considered for this report. One was for Willow Run Airport, about 24 miles NW of the site, and the other was for Toledo Airport, about 29 miles to the SSW. Willow Run data for the period January, 1948, to December, 1950, had been analyzed in connection with an earlier report and will be discussed later. However, for the present report it was decided to rely mainly on the Toledo data since they were more likely to reflect the influence of Lake Erie. In addition, Toledo had been the site of a vertical temperature sounding station for a number of years and these important data were also available for study. Accordingly, wind observations from January, 1950, to December, 1954, were analyzed. The weather station at Toledo was located about 10 miles SW of Lake Erie. Winds were observed at a height of 47 feet above the ground. In view 1

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN'0 L/ /,,/ \~/o CL A K E Ilesr NW^^^i P1^^^^ w\NE C\y <A D A Wi Wi'\v\ ^ \^^-^-^-^^ E^va tn 5 2 ft J ES OLEDO FIG. I-TOPOGRAPHIC MAP OF PROPOSED SITE AND SURROUNDINGS 2

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN of the flat terrain, the observed winds at Toledo generally would be representative of those at the plant site. However, the influence of the lake undoubtedly would be much stronger at the plant site. Some discussion on the possible nature of lake effects on winds will be given later. The frequency of occurrence of winds at Toledo from various directions, grouped according to wind speed, is shown for the seasons and the whole year in Tables I through V. The increased frequency of ENE and E winds in spring is the only important seasonal departure from the yearly picture. Figures 2 and 3 also illustrate the frequency of occurrence of winds from various directions, and the mean wind speed for each direction. In discussing the significance of Tables I through V and Figs. 2 and 3, some grouping of wind directions is possible. For instance, winds from the NE and ENE would carry contaminants to the nearby beaches. Winds from the ENE would also carry contaminants towards Monroe. Winds from the E, ESE, SE, SSE, and S would carry 20 or more miles before reaching any large population center. Winds from the SSW would carry contaminants to the Detroit River communities, the nearest of which is 12 miles from the site. Winds from the SW and WSW would carry 10 to 15 miles across Lake Erie to Canada. Winds from W, WNW, NW, NNW, N, and NNE would carry across Lake Erie 20 or more miles from the site before reaching land. The two groups of directions which provide dispersal without serious hazard may be considered first. Winds from the E through SE to S occur 21.7 percent of the time in an average year, and with nearly the same frequency in each season. Winds from the W through NW to NNE occur 29.9 percent of the time in an average year, and with nearly the same seasonal frequency. Combining the two, it is seen that 51.6 percent of the time any contaminants released at the plant site would be carried 20 or more miles before reaching large population centers. Even under adverse diffusion conditions a considerable dilution would result in this distance. However, Toledo might be affected under special circumstances described later. Considering possible hazards to the beaches, winds from the NE and ENE occur 13.3 percent of the time in an average summer. The average wind speed at Toledo for these directions is 9.5 mph. However, along the lake shore some lake-breeze effect2 would be felt. During the summer afternoon, when air temperatures are higher over land than over water, this would tend to reduce wind speeds somewhat and impart a small component across the shoreline from water to land. The rate of dilution is small in this influx of stable stratified air from the lake. During summer nights, when air temperatures are higher over water than over land, the lake effect would increase the winds and impart a small component from land towards water. The beach hazard is primarily a summer concern. However, Monroe is a permanent population center subject to ENE winds throughout the year. The frequency ---------------------- 3 -----------------------

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE I RELATIVE FREQUENCY OF OCCURRENCE OF WINDS IN VARIOUS DIRECTIONS GROUPED ACCORDING TO WIND SPEEDS Toledo Municipal Airport January, 1950 -- December, 1954 Winter (Dec., Jan., Feb.) ^-^ rp~~~~~~3 otal 32 Total Total Obs. Me an peed 1-3 4-12 13-24 25-31 and 4 and Dir. mph mph mph mph Over Over peNoed %S. No- - /o. mph pmph mph N 0.5 2.3 1.0 3.4 3.6 595 10.1 NNE 0.1 1.8 1.6 0.1 3.4 3.6 385 12.4 NE 0.2 1.9 1.8 0.1 5.8 4.0 452 12.5 ENE 0.2 2.1 2.8 0.4 5.5 5.5 591 14.5 E 0.5 2.6 1.4 4.0 4.3 467 10.1 ESE 0.2 2.0 0.6 2.5 2.8 501 9.1 SE 0.5 2.5 0.7 5.0 5.5 552 8.9 SSE 0.2 2.2 1.5 3.6 5.8 411 11.1 S 0.4 5.2 s.4 0.2 6.8 7.2 777 12.9 SSW 0.2 4.8 6.5 0.6 0.2 12.1 12.5 133550 14.5 SW 0.5 5.7 7.1 0.8 0.2 15.8 14.1 1524 14.1 WSW 0.5 5.4 6.6 0.7 0.5 12.9 15.2 1429 14.0 W 0.5 3.6 2.9 0.2 6.8 7.2 774 12.1 WNW 0.1 2.6 3.5 0.4 0.1 6.7 6.8 752 14.5 NW 0.2 2.1 2.7 0.2 5.0 5.5 570 15.5 NNW 0.1 1.2 2.2 0.1 2.6 2.7 295 12.5 Calm 0.5 59 0 Totals 0.5 5.9 45.8 45.1 5.8 0.9 95.6 100.0 10824 12.9 ---------------------- 4 —---------

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE II RELATIVE FREQUENCY OF OCCURRENCE OF WINDS IN VARIOUS DIRECTIONS GROUPED ACCORDING TO WIND SPEEDS Toledo Municipal Airport January, 1950 -- December, 1954 Spring (Mar., Apr., May) \NE 0.1 1.9 1.25.1 5.2 55132 Total peed 1-3 4-12 13-24 25-31 and 4 and Total Obs Dir. \ mph mph mph mph Over Over No. p _ No _..mph mph mph N 0.3 2.9 1.0 5.9 4.2 468 9.1 NNE 0.1 1.9 1.2 3.1 35.2 351 11.1 NE 0.2 3.0 2.7 5.8 6.0 667 11.8 ENE 0.2 4.1 6.5 o.6 0.1 11.2 11.4 1258 14.6 E 0.4 3.8 3.0 0.1 6.9 7.53 811 11.4 ESE 0.2 2.2 0.7 3.0 3.2 350 9.4 SE 0.3 2. 2.3 0.5 2.7 3.0 332 8.4 SSE 0.2 1.8 0.9 0.1 2.7 2.9 525 11.0 S 0.5 2.9 1.8 0.2 4.9 5.5 582 11.7 SSW 0.2 3.1 3.5 0.3 0.1 7.0 7.2 796 15.7 SW 0.4 4.8 4.4' 0.5 0.2 9.8 10.2 1127 15.5 WSW 0.3 4.2 5.4 0.7 0.2 10.4 10.8 1189 14.3 W 0.2 3.6 3.7 0.4 7.7 8.0 881 13.4 WNW 0.3 2.4 4.7 0.4 7.6 7.8 865 14.9 NW 0.1 2.2 3.1 0.3 5.6 5.8 636 14.0 NNW 0.2 1.7 0.8 0.1 2.6 2.8 507 10.6 Calm 0.9 97 0 Totals 0.9 3.9 46.9 45.9 3.7 0.8 95.2 100.0 11040 12.7 ----- 5.

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE III RELATIVE FREQUENCY OF OCCURRENCE OF WINDS IN VARIOUS DIRECTIONS GROUPED ACCORDING TO WIND SPEEDS Toledo Municipal Airport January, 1950 -- December, 1954 Summer (June, July, Aug.) 32 Total peed 1-3 4-12 13-24 25-31 and 4 and Total Obs. Mean Dir. \ mph mph mph mph Over Over o. Speed \ mp h mphph N 0.7 3.3 0.6 3.9 4.6 509 7.8 NNE 0.3 2.4 0.8 3.2 3.5 391 9.1 NE 0.6 3.7 1.3 5.0 5.6 619 9.1 ENE 0.6 4.9 2.2 7.1 7.7 849 9.9 E 0.7 4.1 0 6 4.8 5.5 604 7.7 ESE 0.4 2.5 0.1 2.5 3.0 330 6.4 SE 0.7 3.3 0.1 3.4 4.1 456 6.0 SSE 0.6 2.9 0.3 3.2 3.8 416 6.7 S 0.7 5.2 0.7 5.8 6.6 727 7.6 SSW 0.7 6.6 2.4 0.1 9.1 9.8 1086 9.7 SW 1.1 9.0 3.1 0.1 12.1 13.3 1463 9.1 WSW 0.7 5.5 2.6 0.1 8.2 8.8 973 9.7 W 0.8 4.1 1.4 5.6 6.4 705 8.8 WNW 0.5 3.8 2.1 6.0 6.5 721 10.5 NW 0.7 2.9 1.3 4.2 4.9 545 9.3 NNW 0.5 2.2 0.8 3.1 3.6 394 8.8 Calm 2.3 252 0 Totals 2.3 10.4 66.4 20.4 0.4 0.1 87.3 100.0 11040 8.6

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE IV RELATIVE FREQUENCY OF OCCURRENCE OF WINDS IN VARIOUS DIRECTIONS GROUPED ACCORDING TO WIND SPEEDS Toledo Municipal Airport January, 1950 - December, 1954 Fall (Sept., Oct., Nov.) 32 Total peed 1-3 4-12 13-24 25-1 and 4 and Total bs ean r.~~pe eSpeed Dir. mph mph mph mph Over Over No. p m mpph mph N 0.6 3.0 0.9 3.9 4.5 493 8.7 NNE 0.2 1.7 1.3 3.0 3.2 347 11.3 NE 0.4 2.4 1.5 4.0 4.4 478 10.4 ENE 0.4 2.1 1.2 3.3 3.7 403 10.0 E 0.6 2.6 0.5 3.1 3.7 405 7.5 ESE 0.2 1.6 0.1 1.8 2.0 221 7.1 SE 0.6 2.5 0.1 2.6 3.2 355 6.3 SSE 0.5 2.5 0.5 0.1 3.2 3.6 395 8.6 S 0.7 5.8 2.0 0.1 7.9 8.6 940 9.8 SSW 0.6 7.9 5.4 0.2 13.6 14.2 1556 11.4 SW 0.9 9.4 5.2 0.4 0.2 15.1 16.0 1745 11.3 WSW 0.8 5.5 3.7 0.3 9.5 10.3 1122 11.2 W 0.5 3.6 1.6 0.1 5.3 5.8 630 10.0 WNW 0.3 3.2 2.8 0.1 6.1 6.4 703 12.1 NW 0.6 2.3 2.6 0.1 5.0 5.6 606 12.1 NNW 0.2 1.7 1.3 3.1 3.3 562 11.2 Calm 1.5 159 Totals 1.5 8.1 57.8 30.7 1.6 0.4 90.5 100.0 10920 10.3 ------------ 7.......... —----

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE V RELATIVE FREQUENCY OF OCCURRENCE OF WINDS IN VARIOUS DIRECTIONS GROUPED ACCORDING TO WIND SPEEDS Toledo Municipal Airport January, 1950 - December, 1954 32 T otal |.\%peed 1-3 4-12 13-24 25-31 and 4 and Total Mean |Dir. \ mph mph mph mph Over Over No. pee m ph, mph N 0.5 2.9 0.9 3.8 4.3 1865 8.8 NNE 0.2 2.0 1.2 3.2 3.4 1474 10.9 NE 0.4 2.8 1.8 4.6 5.0 2196 10.8 ENE 0.3 3.3 3.2 0.2 6.7 7.1 3101 12.6 E 0.5 3.3 1.4 4.7 5.2 2287 9.5 ESE 0.3 2.1 0.4 2.5 2.7 1202 8.1 SE 0.5 2.6 0.3 2.9 3.4 1495 7.3 SSE 0.3 2.4 0.7 0.1 3.2 3.5 1545 9.2 S 0.5 4.2 2.0 0.1 6.4 6.9 3026 10.4 SSW 0.4 5.6 4.5 0.3 0.1 10.4 10.9 4768 12.3 SW 0.7 7.2 4.9 0,4 0.1 12.7 13.4 5859 11.9 WSW 0.5 5.1 4.6 0.4 0.1 10.2 10.8 4713 12.5 W 0.5 3.7 2.4 0.2 6.4 6.8 2990 11.3 WNW 0.3 3.0 3.3 0.2 6.6 6.9 3021 13.1 NW 0.4 2.4 2.4 0.1 5.0 5.4 2357 12.3 NNW 0.3 1.7 1.1 2.8 3.1 1358 10.6 Calm 1.3 567 0 Totals 1.3 6.6 54.2 35.0 2.4. 5 92.1 100.0 43824 11.1.... b~~~~~~

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN W~~~~~~~~ _N NE N NE WNW I \ENE WSW \^ \.^ /ny^'^~\ \\ / ^ESE WSW E S sSW SE S FIG.2- PERCENTAGE FREQUENCY OF OCCURRENCE OF WINDS (rectangles) AND WIND SPEED IN MPH (heavy lines) FROM DIRECTIONS SHOWN. NUMBER IN CENTER GIVES PERCENTAGE OF CALMS.TOLEDO MUNICIPAL AIRPORT JANUARY 1950-DECEMBER 1954 INCLUSIVE. ------------------- ----------------— 9

- ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN W 1 E W E DEC., JAN., FEB. MARCH,APR.,MAY N N W E W'E % or mph / \ 5or mph S S JUNE, JULY, AUG. SEPT., OCT., NOV. FIG.3- PERCENTAGE FREQUENCY OF OCCURRENCE OF WINDS(rectongles) AND WIND SPEED IN M PH.(heavy lines) FROM DIRECTIONS SHOWN. NUMBER IN CENTER GIVES PERCENTAGE OF CALMS. TOLEDO AIRPORT BY SEASONS. JAN. 1950-DECEMBER 1954 INCLUSIVE 10

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN of these winds ranges from 357 percent in the fall to 11.4 percent in the spring. The spring is thus seen to be the season of chief concern. The average speed of ENE winds in spring at Toledo is 14.6 mph, which would normally assure rapid dilution by mechanical turbulence. However, the lake effects again must be considered. Lake effects are most pronounced when the difference in air and water temperatures is greatest. During the spring, when the lake temperature lags behind the air temperature, the lake-breeze effect can be quite pronounced, particularly on a warm afternoon. The result will be an influx of stable lake air and reduction of wind speeds along the lake shore. Therefore, it is likely that with ENE winds the intensity of mechanical turbulence and, hence, mixing will be less near the plant site than at Toledo. It should be noted that an abstract discussion such as this does not reveal the magnitude of these conflicting influences. An analysis of on-thespot wind observations is the most satisfactory way of evaluating land- and lake-breeze effects. It would be desirable to conduct such an investigation at the proposed site. The lake-breeze effect is pertinent not only to possible hazards to Monroe, but also to the Detroit River area, as will be pointed out in the next paragraph. When winds are SSW, the Detroit River communities are downwind from the plant site. The frequency of SSW winds ranges from 7.2 percent in the spring to 14.2 percent in the fall. The mean speed at Toledo ranges from 9.7 mph in summer to 14.5 mph in winter. However, there is a possibility of lake effects producing significant wind changes in the area of the plant site. When the temperature over the land is higher than the water temperature, there will be a tendency for these winds to increase in speed, and there will also be an influx of stably stratified lake air. These two conflicting influences on turbulence would tend to cancel one another. However, when the temperature over the land is lower than the water temperature, there will be a tendency for these winds to decrease and there will be a slight flow of air out over the lake. Conditions of this sort may be expected at night during the three fall months when western Lake Erie temperatures average 65~, 54~, and 45~F,3 compared to average overnight minima of 54~, 43~, and 320F4 at Toledo. Thus, in the fall the influence of the lake will be to act as a brake on SSW winds, producing more occurrences of light winds near the plant site and along the lake and river shore than the Toledo statistics would indicate. Evidently, then, the greatest hazard to Detroit River communities will be during the fall months. When winds are from the SW and WSW, contaminants from the plant site would be carried across Lake Erie to Ontario. Although this section of Ontario is mainly farming country with a few small towns, the high frequency of these winds (24.2 percent) and the possibility of international complications make it worthy of some consideration. The mean speed of SW and WSW winds is above the average for all directions at Toledo, and probably at the plant site too, suggesting that mechanical turbulence will be considerable. Although the winds will be influenced by the lake in much the same manner as were the SSW winds, 11

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN the lake's effect on vertical temperature gradients will be more important. When the lake is warmer than the air moving across it, the flow will become more turbulent as it moves out over the lake. This will be the situation throughout much of the fall and winter. Thus, during the fall and winter, contaminants carried towards Canada would be dispersed rapidly in the turbulent flow over the lake. On the other hand, when the lake is colder than the land, the flow will tend to become laminar over the lake. This will often be the case during the spring and summer. The persistence of smoke plumes from vessels over Lake Erie is quite noticeable during warm summer days. Thus, during the spring and summer, contaminants might reach the Canadian shore in considerable concentration. They would begin to disperse more rapidly on moving over the land. The possibility of contaminants reaching Toledo is somewhat analogous to the case just discussed. Contaminants carried by NNE winds from the site to Toledo would travel over water most of the way. Thus, during the fall and winter, turbulence induced by the relatively warm lake would provide effective dilution in the 22-mile distance. However, during spring and summer, stable stratification of the air induced by the cool lake surface might prevent adequate dilution of contaminants before reaching Toledo. It should be noted that effluents were observed to cross Lake St. Clair from Sarnia to Detroit, a distance of more than 30 miles, during May, 1952.5 The essence of the forgoing discussion of winds is summarized in Table VI. As mentioned earlier, weather data are available for Willow Run Airport which is 5 miles closer to the site than Toledo but considerably farther from the lake. Analyses similar to the foregoing have been performed on Willow Run observations for the period January, 1948, to December, 1950. From these analyses, a portion of which is reproduced in Table VII, it is evident that data from either of the two stations would give essentially the same picture. PRECIPITATION The amount of precipitation occurring, and its correlation with wind direction, is of significance in an air-pollution survey. Although precise details are lacking, it is clear that contaminants are washed out to some extent by precipitation. For a discussion of washout, see Reference 6. The variation of precipitation with wind direction for each of the seasons and for the year is given in Table VIII through XII and depicted by wind roses in Figs. 4 and 5. These data are computed for Toledo Airport based on the period January, 1950, to December, 1954. 12

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE VI SEASON OF MAXIMUM HAZARD FOR VARIOUS POPULATION CENTERS AFFECTED BY DIFFERENT WINDS Frequency of Wind Distance to Season of W Wind Affected tace t ea During Season of Affected Area Maximum Direction Area Maximum Hazard (miles) Hazard (percent) (percent) N Nil within 20 miles NNE Toledo 22 Spring and 3.2 and 3.5 summer NE ENE ENE Beaches 2-5 Summer 1535 ENE Monroe 7.5 Spring 11.4 E ESE ESE Nil within SSE 20 miles SSE S SSW Detroit 12-25 Fall 14.2 River SW Spring and WSW Canada 10 su 21.0 and 22.1 WSW summer With this analysis it is possible to consider how precipitation may modify the conclusions summarized in Table VI. For instance, Toledo is most susceptible to the influence of NNE winds in spring and summer. Tables IX and X and Fig. 4 indicate that rainfall is very infrequent with these winds. Hence there is only a small probability of contaminants being washed out before they might reach Toledo. Therefore, the vulnerability of Toledo to NNE winds is essentially unaltered by precipitation in spring and summer. During the fall and winter, when turbulence alone is considered sufficient to disperse contaminants before they might reach Toledo, rainfall would also tend to remove contaminants, thus providing an additional margin of safety. 13

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE VII RELATIVE FREQUENCY OF OCCURRENCE OF WINDS IN VARIOUS DIRECTIONS GROUPED ACCORDING TO WIND SPEEDS Willow Run Airport January, 1948 -- December, 1950 32 Total peed 1-3 4-12 13-24 25-31 and 4 and Total Obs. Mean Dir. mph mph mph mph Over Over o. Speed mph mph mph N 0.2 2.1 0.7 2.9 3.1 803 9.9 NNE 0.3 2.8 0.9 3.8 4.0 1056 9.7 NE 0.4 5.6 2.2 0.1 7.9 8.2 2168 10.3 ENE 0.3 2.5 1.6 0.2 4.3 4.5 1195 11.8 E 0.3 2.8 2.1.1 1 5.1 5.4 1414 11.9 ESE 0.2 2.2 1.1 3.3 3.6 942 10.5 SE 0.2 2.3 0.7 2.9 3.2 835 9.3 SSE 0.3 2.5 0.5 3.1 3.4 894 8.4 S 0.4 2.9 0.7 3.6 3.9 1031 8.4 SSW o.6 4.7 2.2 0.1 7.1 7.6 2000 10.2 SW 0.9 8.9 3.5 0.2 12.6 13.5 3550 9.9 WSW 0.8 6.5 3.1 0.4 10.0 10.8 2835 10.7 W 0.6 5.1 3.3 0.3 0.1 8.7 9.3 2440 11.7 WNW 0.2 4.6 2.8 0.1 7.5 7.7 2033 11.3 NW 0.4 4.1 1.9 6.1 6.4 1691 10.3 NNW 0.2 2.4 0.8 3.2 3.4 883 9.5 Calm 2.0 528 Totals 2.0 6.1 61.9 28.1 1.6 0.2 91.9 100.0 26298 10.2 14

- ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN - TABLE VIII THE ASSOCIATION OF PRECIPITATION WITH WIND AT TOLEDO AIRPORT January 1950 - December 1954 Winter (Dec., Jan., Feb) Hours of Precipitation as Wind Average Wind Average No. Percentage of Wind Sed Peptto No. __ Percentage of Direction peed Preipitatin bservations Total Hours of | (mph) (in.) Precipitation Total Hours N 12.1.03 78 7.1 0.7 NNE 15.9.04 81 7.4 0.7 NE 13.6.04 75 6.8 0.7 ENE 16.7.05 136 12.4 1.3 E 12.0.04 73 6.7 0.7 ESE 11.9.04 46 4.2 0.4 SE 11.1.05 57 5.2 0.5 SSE 13.9.04 60 5-5 0.6 S 14.6.04 116 10.6 1.1 SSW 15.2.04 114 10.4 1.1 SW 16.9.03 77 7.0 0.7 WSW 15.7.03 47 4.3 0.4 W 12.4.02 26 2.4 0.2 WNW 14.5.02 32 2.9 0.3 NW 14.5.02 47 43. 0.4 NNW 13.5.03 29 2.6 0.3 Calm 0.0.01 2 0.2 0.0 Total 14.3.04 1096 100.0 10.1 15

- ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE IX TEE ASSOCIATION OF PRECIPITATION WITH WIND AT TOLEDO AIRPORT January 1950 - December 1954 Spring (Mar., Apr., May) Hours of Precipitation as Wind Average Wind Average No. Percentage of Direction Speed Precipitation Observations Total Hours of (mph) (in. ) _Precipitation Total Hours N 13.3.04 26 2.7 0.2 NNE 14.0.05 34 3-5 0.3 NE 13.9.05 69 7.1 0.6 ENE 16.3.05 193 19.8 1.7 E 13.4.06 98 10.1 0.9 ESE 145.06 44 4.5 0.4 SE 11.6.05 40 4.1 0.4 SSE 14.0.04 49 5.0 0.4 S 14.6.05 49 5.0 0.4 ssw 15.4.05 73 7.5 0.7 SW 14.8.04 84 8.6 0.8 WSW 16.4.05 46 4.7 0.4 W 14.3.03 45 4.6 0.4 WNW 15.5.04 57 5-9 0.5 NW 16.6.04 40 4.1 0.4 NNW 11.5.02 23 2.4 0.2 Calm. 0.01 4 0.4 0.0 Total 14.7.05 974 100.0 8.8 _____ ___________________ 16 ___________

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE X THE ASSOCIATION OF PRECIPITATION WITH WIND AT TOLEDO AIRPORT January 1950 - December 1954 Summer (June, July, Aug.) Hours of Precipitation as Wind Average Wnd Average No. Percentage of Wind -... No. ____Percentage of Direction peed Precipitatin Observations Total Hours of Tol (mp (in.) Precipitation Total Hours N 11.2.08 18 3.8 0.2 NNE 11.5.09 24 5.0 0.2 NE 11.0.05 42 8.8 0.4 ENE 10.2.o6 25 5.2 0.2 E 11.3.10 28 5.9 0.3 ESE 7.6.23 8 1.7 0.1 SE 7.3.07 18 3.8 0.2 SSE 8.2.05 17 3.6 0.2 S 8.2.05 27 5.7 0.2 SSW 12.4.08 62 13.0 0.6 SW 10.8.08 82 17.2 0.7 wsw 11.4.09 38 8.0 0.3 w 9.8.16 21 4.4 0.2 WNW 12.0.10 24 5.0 0.2 NW 10.9.06 13 2.7 0.1 NNW 13.0.14 21 4.4 0.2 Calm.0.07 9 1.9 0.1 Total 10.6.08 477 100.0 4.3 _17

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE XI THE ASSOCIATION OF PRECIPITATION WITH WIND AT TOLEDO AIRPORT January 1950 - December 1954 Fall (Sept., Oct., Nov.) Ave.rage....... Hours of Precipitation as Wind Average Wind Average Wind No. Percentage of Direction pd P ii i Observations Total Hours of _ (mph) _ _ (inj. ) Precipitation Total Hours N 14.6.06 36 5.7 0.3 NNE 15.2.06 40 6.3 0.4 NE 11.5.14 27 4.3 0.2 ENE 143..07 35 5-5 0.3 E 10.8.06 53 8.4 0.5 ESE 10.0.07 15 2.4 0.1 SE 9.4.06 14 2.2 0.1 SSE 13.6.05 35 5-5 0.3 S 14.5.06 69 10.9 0.6 SSW 15.6.05 77 12.1 0.7 SW 12.4.06 79 12.5 0.7 WSW 12.2.04 48 7.6 0.4 W 9.7.03 23 3.6 0.2 WNW 12.9.05 27 43. 0.2 NW 17.1.04 55 5.2 0*5 NNW 19.2.08 18 2.8 0.2 Calm 0.0.02 5 0.8 0.0 Total 13.2.06 634 100.0 5.8 18

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE XII THE ASSOCIATION OF PRECIPITATION WITH WIND AT TOLEDO AIRPORT January 1950 - December 1954 Annual Hours of Precipitation as Wind Average Wind Average No Percentage of Direction peed Pre itatin Observations Total Hours of ___ (mph) ___(in.) _____Precipitation Total Hours N 12.7.04 158 5.0 0.4 NNE 14.8.05 179 5.6 0.4 NE 13.0.06 213 6.7 0.5 ENE 15.9.05 389 12,2 0.9 E 12.2.06 252 7.9 0.6 ESE 12.3.07 113 3.6 0.3 SE 10.6.05 129 4.1 0.3 SSE 13.2.04 161 5.1 0.4 S 13.8.05 261 8.2 0.6 SSW 14.3.05 326 10.2 0.7 SW 13.7.05 322 10.1 0.7 WSW 14.0.05 179 5.6 0.4 W 12.1.05 115 3.6 0.3 WNW 14.1.05 140 4.4 0.3 NW 15.4.03 133 4.2 0.5 NNW 14.0.06 91 2.9 0.2 Calm 0.0.04 20 o.6 0.0 Total 13.7.05 3181 100.0 73. 19.

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN N 1.5 % I0 WI i IE FIG.4- PERCENTAGE OF TOTAL WINDS WHICH BROUGHT PRECIPITATION FROM EACH DIRECTION AT TOLEDO. JANUARY 1950- DECEMBER 1954 INCLUSIVE 20

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN w -""E;' DEC., JAN.,FE8. MAR.,APR.,MAY JYUN E, IUYAUG SPT.,E * E JUNE,ULY, AUG. SEPT. OCT., NOV. FIG. 5- PERCENTAGE OF TOTAL WINDS WHICH BRING PRECIPITATION FROM EACH DIRECTION.DATA HAVE BEEN ANALYZED ACCORDING TO SEASON. TOLEDO AIRPORT JAN. 1950DECEMBER 1954 INCLUSIVE. 21

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN The occurrence of precipitation will reduce the hazard to Monroe. The important wind direction is ENE. Since Monroe is about 7.5 miles from the site, rainfall probably would wash out most of the contaminants before they could reach Monroe. During the spring, ENE winds occur 11.4 percent of the time. However, precipitation occurs with ENE winds 1.7 percent of the time. The difference, 9.7 percent, represents the portion of the time when contaminants would reach Monroe, diluted by diffusion processes only. Similar computations give 4.2 percent as the frequency of vulnerability to contaminants from the plant during winter, 7.5 percent during summer, and only 3.4 percent during the fall. Even after considering precipitation, spring remains the season of greatest hazard. Similarly, the occurrence of precipitation will reduce slightly the hazard to such remote centers as the Detroit River communities and Canada. On the average, precipitation occurs 7 percent of the time that the wind is SSW and 5.5 percent of the time that the wind is SW. This will not materially alter the conclusions of Table VI. In the cases discussed thus far, precipitation is considered an agency to reduce the hazard. Only in the unlikely event that the precipitation commenced at the exact time that a cloud of contaminants reached a population center, or just before, would precipitation increase the hazard. However if the area being considered is close to the source, the washout produced by rainfall would increase the hazard. It is this type of effect that must be considered with reference to the beaches, which are 2 to 5 miles from the plant site. During the summer, the beaches will be downwind from the site 13.3 percent of the time. Rain together with NE and ENE winds occurs only 0.5 percent of the time. Hence the hazard to the beaches will be increased by the occurrence of rain only about 4,5 times out of every 100 times that the beaches are downwind from the site. TEMPERATURE INVERSIONS Temperature inversions in which temperature increases with height are important because they tend to suppress turbulent air motion and, hence, turbulent diffusion. With inversions, concentrations downwind from a source will be relatively high. Radiosonde observations provide one of the most satisfactory sources of data on vertical temperature gradients. Such observations are not available for the plant site, but were taken at Toledo for a number of years. The incidence and intensity of inversions may differ between Toledo Airport and the plant site as a direct result of lake influences, some of which were discussed in relation to possible hazards to Canada and Toledo. Nevertheless, the obser22

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN vations at Toledo will provide a measure of the seasonal trends for the plant site. The distributions of inversion and noninversion conditions in relation to wind direction at Toledo are given in Table XIII. The data cover the period January, 1946, to December, 1950. A wind rose giving percentage frequency of occurrence of winds associated with inversions with bases below 1000 feet and corresponding mean wind speeds for 2200 EST is presented in Fig. 6. Table XIII shows clearly that the low-level inversion is primarily a nighttime phenomenon. In fact, inversions over land are usually the result of surface cooling produced by long-wave radiation to outer space. They were observed on 61 percent of the nighttime temperature soundings but only on 19 percent of the daytime soundings. The association of light winds with low-leve inversions is quite evident at nighttime from a comparison of mean winds, but is apparent only to a lesser extent in the daytime. This suggests that the hazard due to any contaminants will in general be greater at night than during the day. Inversions are also seen to be a relatively common occurrence with winds from the sector S through SW. Thus, a transport of contaminants towards the Detroit River or Canada under conditions of poor diffusion is likely to be rather common. However, it has been noted earlier that the relatively warm lake surface may improve the diffusion conditions somewhat in SW winds during fall and winter. VISIBILITY The object of a survey such as this is to define as accurately as possible the diffusion climatology of an area without measuring the concentrations of contaminants over a period of months or years. There is another source of information, involving observations over a number of years, which helps to reveal the seasons in which poor diffusion conditions are most prevalent. The monthly climatological summaries for first-order Weather Bureau stations include occurrences of restricted visibility when ceilings are higher than 9500 feet. For this group of observations, the 9500-foot ceiling precludes the possibility of precipitation; hence, the visibility restriction must be smoke, haze, or fog, whose occurrence is mainly associated with poor diffusion. A tabulation was made of occurrences of visibilities equal to or less than 6 miles with ceilings greater than 9500 feet at Toledo Airport for the period January, 1950, to December, 1954. The mean number of hourly occurrences for each month was computed and the results expressed as the relative 23

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN r O O r C\ Ln rK f -- \o-OO cO O -- O o o Cd L, O r-! J6 C; NCO KK -r4 K O OJ.c E r-t r- r-4 r-I r- Hrl r- r-H r- r-l r- r r-l r rO *H 0) Cr) a) L'O Ln \jt I C t — -0~ ~ -o"i c' CO cO C cO rjco' | O a) ) 1 U O\ KlOr - \ N - N -t c oO COO K-\r- CO | > r- r r- OJ r- r- r —l _:H 0 HCO 0 0 CO r0 nd 0 \O CO O cO r-4V ) \O 0rAn OOO - OJ 1 r-o r, ) r* *. ( r-l p4^ r-l tr-4 r-4 rl r- r-l r- rI rAlr-l r-1 E p 0 H 0 O r- O Ln O O O C O r — (- - L n LLn L \ - OH K " _ H O V o 0. I I.,; H EI | ko o I a:) oJ O ) OO cO (D Lr\ o n P4 P i_.Q 0] ~ |D ~ C l |) L 01, —---, —-, —t rl._.X- -. — ~ — kO L- | — H HE O 0 0 *................ H HC.OC ) X M E-l P H 1CQ pq r O2 0 0 C0 rd Q ( O L C - Wr r0 CU — l C - CO CO O 0 9 rd a) MO H 10t H 0) CO OJ n~ d)^............... E-: E-! vZj;-4 n \IDo \ID c O cQ O -AC co 0-1 c o \0 IO |, _r O cu \o n c > rq rq \1 r r hN K> |?-l r- — H — H -H H H ^ ^ rd S j - I- t Kl 1c\ Ln ct o co Co co \10 Ko - co 0rr 1 r4 rF- r I —--- C- r-1 ---- ---- 24 _____n _n N-_\ \1 n W_ _____'r-I rD rl rl rA fl 24

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN __ N z NN - I ~NNE WNW/ / \ENE 10 5% ormph WNSW SE S FIG. 6 - PERCENTAGE FREQUENCY OF OCCURRENCE AT 2200 EST OF WINDS ASSOCIATED WITH INVERSIONS BASED BELOW 1000 FT (rectangular areas) AND CORRESPONDING MEAN WIND SPEEDS WITH SAME INVERSIONS (mphheavy lines) FROM DIRECTIONS SHOWN. NUMBER IN CENTER GIVES PERCENTAGE OF CALMS. TOLEDO, OHIO JANUARY 1946 TO DECEMBER 1950 INCLUSIVE. 25

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN frequency of restricted visibility. These data are presented in line 1 of Table XIV. Line 2 is obtained by smoothing the data of line 1 [by the formula (A + 2B + C)/4 = smoothed B], a standard procedure for climatological data computed for a.short period of years. TABLE XIV RELATIVE MONTHLY FREQUENCY OF VISIBILITIES EQUAL TO OR LESS THAN 6 MILES, WITH CEILINGS GREATER THAN 9500 FEET, FOR TOLEDO, JANUARY, 1950, TO DECEMBER, 1954 Percentages by Months J F M A M J J A S 0 N D Ob s e rved frequeny 6.7 8.3 6.1 6.6 9.1 8.8 10.1 15.5 9.6 16.8 12.2 8.3 frequency Smoothed frequency 7-5 74 6.8 7.1 8.4 9.2 11.1 12.7 12.9 13.8 12.4 8.9 Table XIV represents the large-scale climatological trends, unaltered by the lake influence at the proposed site. It suggests that conditions predisposing to smog are most prevalent in the fall. This conclusion is borne out by the past occurrence in other areas of prolonged smogs in the fall months. POSSIBLE HAZARDS TO POPULATION CENTERS In considering the potential hazards to population groups, two possibilities must be considered: a slow leak of radioactive materials from the reactor, or an explosion which would instantaneously release radioactive materials. The former may be treated as a continuous point source, and the latter as an instantaneous point source. Sutton7,8 gives expressions for downwind concentrations -X in mass of contaminant per unit volume of air as follows: Instantaneous Point Source 2Q, _______.n- /x2 y2 z2 (x,y,z,t) =./2+ C L 3'/2 Cx Cy (yt) 5(2-n)/2 exp x2 C2 Cz

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN where x, y, and z are distances measured from an origin moving with the cloud at constant speed uT; t is the time interval from the instant of the explosion; Q is the total mass released by the explosion; Cx, Cya and Cz are virtual diffusion coefficients; and n is a coefficient which varies with the turbulence and is obtained by fitting the theoretical profile u = u1 zn/(2-n) to the observed variation of wind with height. The maximum concentration is found at the center of the puff, where x = y = z = 0O so that the expression for the maximum concentration is 2Q max = 3/2 CxyC ('t) 3(2-n)/2 (1) Continuous Point Source X (xy,.) 2Q o- exp -xn-2 2 + - XCy^Cz-n C where Q is now the mass of contaminant emitted per unit time. At a given distance x downwind from the source the maximum concentration occurs at y-= z = 0 and is therefore given by 2Q -max = XCyC X2-n (2) The principal problem involved in the use of these equations is the choice of suitable values of the several coefficients. The values given below in Table XV represent the writers' choice on the basis of Sutton's earlier values,9 Smith and Singer's recent values determined experimentally at Brookhaven National Laboratory from concentration measurements,10 and Friedman's values obtained from wind-vane data at M.I.T.'s Round Hill Field Station.11 The values are chosen so as to give mean concentrations at a point downwind from a continuous point source such as would be obtained by sampling continuously for a one-hour period. Using these values of the coefficients, Equations 1 and 2 reduce to: Instantaneous Point Source Moderate lapse: /./Q = 15.96/(Ut)264 Large inversion, land trajectory:. 7 /Q = 89.8/(ut)2 0 Large inversion, water trajectory: %7/Q = 200/(T-t)1.8 27

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN TABLE XV VALUES OF DIFFUSION COEFFICIENTS Vertical Temperature Gradient (m sec- n Cx Cy Cz Moderate lapse 6.24.30.30.25 Large inversion 2.65.20.20.10 (land trajectory) Large inversion 2.80.16.16.04 (water trajectory) Continuous Point Source Moderate lapse: X/Q = 1.414/xl'76 Large inversion, land trajectory: XC/Q = 15.91/x135 Large inversion, water trajectory: X/Q = 49.74/x1' The calculated values of X/Q at the centers of interest, using these equations, are given in Table XVI. TABLE XVI COMPUTED VALUES OF X/Q Type of Source Center Distance Moderate Lapse Large Inversion Instantaneous Beaches 3200 m 8.9 x 10l9m-3 8.8 x 10l-6i3 point Monroe 11300 3.0 x 10-10 7.0 x 10-7 Canada 16000 1.3 x 10'10 5.4 x 10-6 Wyandotte 19500 7.5 x 10-11 2.4 x 10-7 Toledo 35000 1.6 x 10-11 1.4 x 10-6 Detroit 35000 1.6 x 10-11 7.4 x 10-8 Continuous Beaches 3200 9.6 x 10-7sec m-3 2.9 x 10-4 sec m-3 point Monroe 11300 1.0 x 10-7 53. x 10-5 Canada 16000 5.5 x 10-8 4.1 x 10-4 Wyandotte 19500 3.9 x 10-8 2.6 x 10-5 Toledo 35000 1.4 x 10-8 1.8 x 10-4 Detroit 35000 1.4 x 10-8 1.2 x 10-5 28

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN CONCLUSIONS The projected plant to be located on the west shore of Lake Erie, near Monroe, presents the greatest hazard to the nearby beaches and to that portion of Canada immediately across Lake Erie. There is also some hazard to Monroe and to Toledo. The hazard to the southern part of the densely populated strip along the Detroit River is less, decreasing to slight at Detroit. The beaches may be affected in NE and ENE winds which occur 13.3 percent of the time in summer. However, the serious hazard associated with large inversions will occur only about 1/3 of the time, thus reducing the original 13.3 to about 4.5 percent. The Canadian shore may be affected by SW and WSW winds during the spring and summer when large inversions may persist throughout day and night. These winds occur a little more than 20 percent of the time, but usually with a speed in excess of the 2 m sec-1 used in the computations of Table XVI. The hazard to Monroe occurs when winds are ENE, and is therefore greatest in the spring. However, since persistent inversions are frequent in the fall, it is advisable to think of this season also as one of some hazard to Monroe, despite the relative infrequency (35.7 percent) of ENE winds. The hazard to Toledo exists when winds are from the NINE and when the water temperature of the lake is generally colder than air temperatures over land. This limits the hazard to the spring and summer when TNE winds occur only a little more than 3 percent of the time. It should be noted that although Detroit and Toledo are equidistant from the source, the much closer approach to laminar flow that may be realized in a water trajectory may produce concentrations at Toledo that are 15 to 20 times those at Detroit. RECOMMENDATIONS The evaluation of the pollution hazard in the vicinity of the Monroe site is hampered by the absence of knowledge of the diffusion pattern over and near a lake surface. Thus, the values of coefficients used for this report, and given in Table XV, are estimates obtained by modifying values appropriate for land trajectories and may therefore be considerably in error. A more adequate evaluation of the hazard can be made only by (1) an experimental program of appropriate measurements at and near the site and (2) 29

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN an analysis of these measurements. The following recommendations are therefore made. 1. Meteorological Studies Recommended.-A program of meteorological observations should be undertaken at and near the plant site. For this purpose, the erection of a 100-foot self-supporting steel tower at the water's edge is recommended. The following instrumentation at each of three levels on the tower is proposed: anemometer and wind vane, bivane (for special periods), and temperature element, with necessary recording equipment. Analyses of meteorological observations taken at the tower for evidences of special lake effects are an essential part of the program. 2. Diffusion Studies Recommended.-Studies of diffusion over the lake under various meteorological conditions are required. It is proposed to use a tracer substance emitted from a source near the plant site, with concentration measurements made at various locations offshore. A full program of meteorological measurements would be made at the same time. Analyses of these measurements of concentration and of the meteorological variables provide the required knowledge of the diffusion pattern over the lake. Such a program would reduce the uncertainty concerning the hazard from the projected plant to communities around the lake. 3o

ENGINEERING RESEARCH INSTITUTE * UNIVERSITY OF MICHIGAN REFERENCES 1. Hewson, E. W., "Pollution Climatology of the Ann Arbor Area," Eng. Res. Inst., The Univ. of Mich., Ann Arbor, 1953. 2. Wexler, R., "Theory and Observations of Land and Sea Breezes," Bull. Am. Meteor. Soc., 27:272-287 (1946). 3. Millar, F. Graham, "Surface Temperatures of the Great Lakes," Jour. of the Fisheries Research Board of Canada, Ottawa, 9 (7), 1952, pp. 329-376. 4. U. S. Weather Bureau, "Local Climatological Data, Toledo," National Weather Records Center, Asheville, N. C. 5. Baynton, H. W., "Report of an Unusual Gas Visitation at Detroit," Technical Advisory Board on Air Pollution, International Joint Commission, Ottawa, Canada, 1952. 6. U. S. Weather Bureau, Meteorology and Atomic Energy, Chap. 7. Washington: U. S. Government Printing Office, 1955. 7. Sutton, O. G., "The Problem of Diffusion in the Lower Atmosphere," Quart. Jour. Roy. Meteor. Soc., 73:257-281 (1947). 8. Sutton, O. G., Micrometeorology. New York: McGraw-Hill Book Co., 1953, p. 287. 9. Sutton, 0. G., "The Theoretical Distribution of Airborne Pollution from Factory Chimneys," Quart. Jour. Roy.. Meteor. Soc., 73:426-436 (1947). 10. Smith, M. E., and I. A. Singer, "Sampling Periods in Air Pollution Evaluations," Proc. Third Natl. Air Poll. Conf., Los Angeles, Stanford Resi. Inst., 1955, pp. 80-85. 11. Friedman, D. G., "The Height Variation of Lateral Gustiness and Its Effect on Lateral Diffusion," Jour. Meteor., 10:372-379 (1953). 51

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