Waste stabilization ponds: Possible contamination of the shore

Abstract

A waste stabilization pond was investigated to determine if there was a health hazard due to contamination of the shore line.

Soil samples were taken at various points along the bank and water samples were collected from the pond. Coliform and enterococci counts were made from the samples and were employed in conjunction with observations made of conditions at the sample points to determine if a health hazard existed at the shore line. Three stations were located along the leeward side of the pond. At each station samples were taken in adjacent soil, soil at the water line, water at the water line, water from the pond surface and water from one and one-half feet beneath the pond surface off shore. Using the geometric mean, coliform counts ranked as follows: 1717.7 water sample one and one-half feet below the surface and off shore, 583.9 soil sample at the water line, 79.0 soil on adjacent bank, 20.2 surface water sample off shore, and 11.5 water sample at water line.

The high count one and one-half feet below the surface is presumably from the sewage being added to the pond. Low counts were associated with pH values near ten. High counts generally occurred at more neutral pH values of about eight. The counts at the water line are not high enough to indicate the presence of significant concentrations of fecal matter. Also, no fecal matter or other floating matter was observed at the shore line. The counts from the soil on the bank up from the shore line were what would be expected from a similar area excluding the waste stabilization pond.

A comparison of the coliform and enterococci counts showed that the enterococci count is approximately one half the coliform count which is in agreement with other investigations (2) and indicates its usefulness as an indicator organism.