SALT LAKE CITY — It's known as "Lot 6" among environmental remediation managers and scientists, once branded as one of the worst places in Utah for the amount of poisonous chemicals saturating the soil, groundwater and a ditch that flows into the Jordan River.

The legacy of Lot 6 included 48 drums of reactive and ignitable liquids, some of which were leaking within a few hundred yards of residential and commercial areas.

Nearly 30 years ago, more than 2,400 cubic yards of contamination had been dumped in a concrete-lined pond. Other waste was discharged into the ditch at 700 West.

About 60,000 people pumped drinking water from private wells within three miles of the polluted site, with one well situated 2,000 feet from the contamination.

The former site of Wasatch Chemicals is nearly cleaned up now, but wells sunk a year ago found stubborn traces of a contaminant that remains in the groundwater and a deep aquifer.

The Environmental Protection Agency recently announced more sampling and analysis needs to happen at the Superfund site near the intersection of 2100 South and 700 West, a process that is estimated to take another three years to complete.

Much has already been done, work detailed by the agency in the latest five-year review of the remediation. This is the fourth such review in a cleanup that has proven stubborn, lengthy and costly.

An array of toxic pesticides and chemicals were left at the site when Wasatch Chemical went out of business. Industrial operations at the site from 1957 to 1971 included the production and storage of chemical products such as bleach and acids. Pesticides, herbicides, fertilizers and industrial solvents were blended and packaged there until 1978.

Lot 6 was idled by 1980, and five years later, state health officials were testing groundwater, finding the presence of several hazardous chemicals.

Ultimately, the property — which had been acquired by a subsidiary of Questar in 1968 — landed on the Superfund list, requiring a multi-pronged approach for such a vast cleanup.

Contractors used electricity to super-heat soil, sludge and other waste into glassy blocks of slag, transforming 9,600 tons of contaminated material into solid form via the in situ vitrification process. The transformation required 37 individual melts across the entire evaporation pond at Lot 6, finishing up in January 1996.

The cleanup also included excavating the contaminated soils and placing a cap over the treated area.

Last fall, four new wells were drilled, and during the activity on the site, more contaminated soil was found that exceeded federal standards.

State and federal officials visited the site in March and conducted surveys of those involved in the remediation process, as well as businesses that occupy some of the 18-acre site.

The EPA's project manager said what is left to be done is an accurate characterization of the most recent contamination discovered, plus the development of a long-term groundwater solution.

Land-use restrictions already exist at the site, including provisions that kick in should any new development occur.

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