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aluminum) when the treated area is compared to the control (untreated) area are indicative of bactericide effectiveness and that the bactericide treatment continues to be effective for over three years. The treated area parameters continue to show consistently improved conditions and stability.

The data in Table 1 are a composite of data from lysimeters placed in the treated and control areas on the Norton site. This data also shows the distinct benefits from bactericide treatment over the past twenty-one months.

Table 1. Composite Water Quality from Lysimeters on the Norton Site

A study of the growth of heterotrophic microorganisms in the bactericidetreated area versus the untreated area was made. This comparison was conducted for the topsoil and for the soil-refuse interface. The results of the heterotroph growth study (Table 2) indicate that the treated area clearly has more heterotrophic microorganisms than the untreated area.

Average MPN values for T. ferrooxidans in the soil and refuse for the treated and control areas are shown in Table 3. The control area has a far greater T. ferrooxidans population. Over 400 times as many T. ferrooxidans remained in the control area compared to the treated area. This prolonged low population density of T. ferrooxidans in the treated area is evidence of the effectiveness of the controlled release bactericide treatment.