Deep-well disposal of acidic wastes has been employed successfully at the E. I. du Pont Pigments Plant, New Johnsonville, Tennessee, since 1967. In 1965, as part of a program to reduce surface discharge of waste fluids, together with other methods for waste disposal, an investigation of the feasibility of subsurface waste disposal was conducted. Basic data were developed and from this a proposal was made to the state for drilling a deep disposal well. A public hearing, attended by local, state, and federal representatives, was held and all inquiries answered. Under state permit, a 6,700-ft geologic test well was drilled. Receptive zones were found in the middle and lower Knox-Copper Ridge Dolomites (Cambrian). Laboratory studies conducted with rock cores showed that the w ste fluids are compatible with the formation rocks and their contained waters. Appropriate state agencies approved completion designs and the well was completed in 1966.

Acidic wastes were injected into the well at design rates and pressures from 1967 through 1971, at which time the well was retired from service. Two additional waste wells have been drilled and are operating successfully. A fourth well is scheduled to be drilled in the near future.

In addition to downhole monitoring systems on each well, the plant monitors many freshwater wells in the surrounding area, as well as 1 deep well on the plant property, for evidence of waste-fluid migration. To date, no vertical migration of waste has been observed.

A second deep monitor well is to be drilled in conjunction with the upcoming fourth waste well. At New Johnsonville it has been shown that a properly installed waste-disposal well system can successfully remove undesirable waste fluids from the biosphere.

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