The U.S. Environmental Protection Agency on Friday announced the final stages of a $24.7 million plan to clean up groundwater contamination at the Peninsula Boulevard Groundwater Plume Superfund site in Hewlett.

The federal plan’s first phase began in 2011 and included pumping polluted groundwater to the surface for treatment. The EPA also will inject additives to break down contaminants into highly contaminated areas. The second phase will now target the sources of contamination at and around former dry cleaning operations. Additives will also be injected here (www.epa.gov/superfund/peninsula-groundwater).

Water will be regularly tested during and after the work is complete.

Local residents and Woodmere Middle School get clean drinking water from several wells about 1,000 feet north of the Superfund site and it’s monitored regularly, the EPA stated.

“EPA is using the best available technology at the Peninsula Boulevard site to protect residents of Hewlett,” said Acting Regional Administrator Catherine McCabe.

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The site is the former home of Grove Cleaners, which operated at 1274 Peninsula Blvd. from 1987 to 1992. The site, next to Woodmere Middle School, was added in 2004 to the Superfund list of the most contaminated hazardous waste sites.

A tetrachloroethylene groundwater plume flows northwest from the site to the Long Island American Water Plant 5 Well Field, a source of drinking water. Water extracted there is treated to remove contaminants before distribution and is sometimes mixed with water from other sources, officials said.