A federal cleanup under way at the former Kenyon Piece Landfill on Sand Plain Road has revealed hundreds of old paint cans and other containers, as well as debris such as old fabric, which has tested positive for hazardous substances known as volatile organic compounds, a spokesman for the Environmental Protection Agency said Tuesday.

In recent weeks, cleanup crews have dug a few pits on the 2.5-acre site and found several hundred 5-gallon cans, a handful of 55-gallon drums and a few 35- gallon containers, Allen K. Jarrell, the EPA’s on-site coordinator in Charlestown, said. In addition, they have removed a lot of debris, including solventsoaked textiles.

Some of the containers still had paint in them, and were found in various stages of decomposition.

“Some of them have holes, some of them are crushed and some of them are intact,’’ Jarrell said.

Monitoring on the site has confirmed the presence of VOCs, a group of contaminants that includes the compounds toluene, ethylbenzene, naphthalene and tetrachloroethene. Clean-up crews are wearing protective suits and are being provided fresh air, he said.

The cleanup site is probably going to be bigger than EPA anticipated because once workers got underground they found that one pit led to another or was larger than expected, according to Jarrell.

“The first pit we dug ended up taking us into the trees,’’ he said. The size of this pit required clearing trees from an area approximately 50 feet by 50 feet in size.

Also, old photographs of the site, which were provided by the town of Charlestown, show a dump site bigger than was originally thought, Jarrell said. Despite the greater size, the cleanup is still expected to take six months, he said.

The EPA announced in August that it would clean the site, citing the threat of groundwater contamination posed by leaking barrels and cans. These contaminants might leak into nearby private drinking water supplies and also pose a risk to people who walk across the property, the EPA said.

The cleanup involves excavating the contaminated material, safely removing it, then filling the area with clean dirt. The total cost of the project has not been determined because it is still not known exactly how many drums and other containers are buried on the site.

Located in the northwest corner of Charlestown, south of Sand Plain Road, the removal site is part of a larger 62-acre parcel that was used as a landfill by the now-defunct Kenyon Piece Dyeworks. From 1968 through 1979, Kenyon Piece Dyeworks carted solid and liquid waste from its plant off South County Trail and dumped it on the site.

Kenyon Piece later became Kenyon Industries, which filed for bankruptcy in 1988. In 1993, Kenyon’s parent company, Coated Seals, Inc., abandoned the property, which has since been used by dirtbikers and others drawn to its wooded trails.

Concerned about the proximity of private wells to the landfill, the well water of residents in nearby Columbia Heights and in Shannock has been tested by the state’s Department of Environmental Management, among other organizations, over the years. These tests have at times revealed the presence of VOCs, requiring a few residents to use bottled water. The results of this testing helped the site to qualify for a special EPA program that involves emergency removal of hazardous waste.