October 17, 1951

In a discussion with M. M. Weiss of the Health Physics Division of the
Brookhaven National Laboratories, and M. E. Smith of the Meteorology group at
Brookhaven, the following points were discussed and the following conclusions
were reached:

• a. The elevation of the monitors is not considered necessary. All
  of the BNL monitors are in small wooden structures on the ground,
  except one station which is at an elevation of about 300 feet on the
  tower. It was the opinion of the group that the roofs of the campus
  buildings would make satisfactory monitor sites if they are sufficiently
  accessible. It is to be emphasized that this elevation is not con-
  sidered necessary in that ground stations have proved satisfactory in
  every way.
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• b. Trees in the vicinity do not constitute a serious obstruction in that
  they do not interfere greatly with the normal flow of air. Tall
  buildings do constitute a serious obstruction in that they do impede the
  flow of air.
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• c. In flow of the number of reasonably tall buildings in the immediate
  vicinity of the stack it is evident that the rough ten stack length
  rule needs to be modified. In the judgment of the group, the near
  monitors should be at a distance of about 600 ft.
•  
• d. Tests should be made with a mobile monitor at all buildings or knolls
  at or slightly above stack height within a radius of 10 miles.