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'. L. M. ALEXANDER The oxides of nitrogen-the first prediction of the boiler manufacturer, Combustion Engineering -is that nitrogen oxides emission will be in the order of 400,500 PPM concentration. No standards for this emission have been established by the government. NOx becomes of concern primarily in very large population centers where it can react with unburned hydrocarbons from autos to form the photo-chemical smog such as observed in Southern California. We can conclude that the relatively minute quantities of gases and particulate matter which will escape will be well within the limits set out in Federal, State and County regulations, and as such will not be harmful to people, plants, fish or animals. It will not be obnoxious to our aesthetic senses either. To prove that, one of the studies being conducted will include the development of an index of potential pollutant exposure. In layman's Slide 21 language, it will tell us how much of what is likely to go where. This slide illustrates a first approxi. mation to what might result. Although upper level (700-1500 feet) winds have not been recorded in and near the plant site for any appreciable length of time, it was possible to create a synthetic portrayal of what is thought to be representative of the Navajo plant site area. Note that the pollurant exposure envelope has its major axis north of the plant site running NE-SW while south of the plant site it shifts more southerly due to terrain influence in the plant vicinity, The potential pollution exposure envelope is not to be misunderstood-it attempts to answer the question as to what areas might be most likely affected, no matter how slight the pollution, We intend to initiate a pollution monitoring program in the near future which will keep us informed as we go, Slide 22 Slide 22 illustrates what might be termed a first look at what is considered to be the worst condition, In technical jargon this condition occurs when the atmosphere permits the stack plume to "fumigate" the ground in and near the plant site. Although we intend to study this further, our meteorologists tell us that fumigation occurs with all stack heights when the ground temperature warms sufficiently during the day to bring the stack plume temporarily to the ground. Further, they tell us that fortuitously, this condition is of normally short duration (30-60 minutes) and will occur on the order of only about 2-3% of the time at the Navajo site, So far this condition does not come under regulatory consideration, but is of interest since it can occur. 'Slide 22 shows that fumigation begins when the temperature condition reaches a lapse as shown A-B and ends, or is assumed conservatively to end, when the lapse of CoD is reached (this is when the plume has ascended at least one-half the original stack height thus lessening the ground level concen- tration). ' Slide 23 This slide indicates what our meteorologists believe to be representative 'of the frequency of the direction of the winds when fumigation takes place. Note that the wind direction frequency is directly proportional to the lengths of the dark bars on the chart. The numbers at the ends of the bars are the average wind speeds for each bar, Again here we note the anticipation of southwesterly and westerly flow domination, i.e" winds from the southwest and west, at stack height level. Our on-site program will also monitor wind conditions so that we can accurately portray conditions as they actually occur at the Navajo site. This effort will be coupled with our air monitoring effort which we expect to initiate in the near future. A portion of this work has already been in operation since March of 1969, -27-