Pre-Determining the Extent of a Sewage Field in Sea Water

This paper presents a method for pre-determining the probable area and extent of a sewage field in sea water, when the quantity of sewage flow and the direction and depth of discharge below the ocean surface are given. The formulas may also be applied to define the probable limits of a sewage field at any given degree of dilution. Research by the writers fails to reveal any established numerical relationship between the known or pre-determined factors surrounding an ocean outfall outlet and the probable amount of dilution obtained at the ocean surface over the outlet or of the probable spread of the field. In many instances bacteriological surveys made of the area of ocean pollution at sewer outlets have disclosed the extent of the permissible pollution to be far from what the designers anticipated. The predicted area in such cases was based largely upon an “acres-per-second-foot-of-sewage" factor used as a constant rather than as a variable, dependent on the elements of design and conditions existing .at the outfall site.