NORTH PROVIDENCE, R.I. — From the outside, Centredale Manor resembles most other assisted-living facilities. It has 123 bedrooms, and houses elderly and low-income residents. It rests comfortably on the eastern banks of the Woonasquatucket River, not far from the mom-and-pop shops in the village of Centredale. Town Hall and Route 44 are a stone’s throw away.

The Smith Street facility is also a Superfund site, built on top of or near some of the state’s most toxic dirt. A legacy of Rhode Island’s manufacturing era, the Centredale Manor site was once a dumping ground for untold amounts of hazardous chemicals and other waste. Three-plus decades of industrial polluting from chemical production and drum reconditioning created one of the most toxic Superfund sites in New England.

The Environmental Protection Agency (EPA), in partnership with the Rhode Island Department of Environmental Management and organizations such as the Woonasquatucket River Watershed Council (WRWC), a nonprofit dedicated to restoring and preserving the river, have focused on cleaning up the site for two decades.

WRWC held a virtual community conversation in early October to provide an update on the status of the site, and for many, letting them know what lies beneath.

“I logged onto the call because I’m interested in local Superfund sites, and how people support each other collectively — not only regarding current sites, but also prevention of future pollution,” said Cynthia Roberts, a North Smithfield resident.

The main contamination site is 135 feet south of the southernmost parking lot at Centredale Manor. It is filled with 20th-century industrial waste, although federal and state officials are not sure of the main pollutant sources.

While the pollutants are centered mainly around Centredale Manor, the Superfund site has a wide area of impact. Its boundaries include upstream to Brook Village — a senior living facility — and down through Allendale Pond, Lyman Mill Pond, and a 30-acre forested wetland known as the Oxbow area.

The two primary toxins concerning WRWC today are dioxins and hexachlorophene, a disinfectant banned in 1972 by the Food and Drug Administration for all non-prescription uses. Dioxins were dumped into the river for years, as a byproduct of hexachlorophene production.

“We know dioxin is a class 1 carcinogen,” WRWC River Ranger Taliq Tillman Virgil said. “That means it can cause cancer over a long amount of time, and also in really, really small amounts it can be really, really harmful.”

Dioxins are hydrophobic, which means they don’t dissolve in water and settled into the sediment at the bottom of nearby waterbodies. Dioxins are persistent organic pollutants, meaning they take a long time to break down once they are in the environment. They are highly toxic and can cause cancer, reproductive and developmental problems, damage to the immune system, and can interfere with hormones, according to the EPA.

Around the area of the Woonasquatucket River, bird populations have struggled to reproduce because of this legacy pollution. Dioxins were first found in fish from the Woonasquatucket River in 1996. The Rhode Island Department of Health (DOH) issued a fishing advisory for any fish caught downstream of the site three years later. Soil sampling in 1999 from the site showed dioxin levels at an extremely high 115.82 parts per billion (ppb). The EPA classified the area a Superfund site a year later.

EPA officials identified the area encompassing Centredale Manor and Brook Village as the source of the contamination. All hazardous materials — soil, glass, metal drums, and industrial waste — were excavated and put into the southernmost area of the source site. This area was then capped and paved over to become a public walking trail. Any other exposed hazardous areas to human contact were capped or fenced off.

Even before any litigation was settled, the EPA rebuilt the then-failing Allendale Dam to prevent further pollution impacting the river downstream. The source area has been considered completely remediated and federal workers are now focused on cleaning up Allendale Pond, and will then tackle the rest of the downstream impacted areas.

WRWC has been acting as the EPA’s local technical advisory group for the site. They disseminate the latest developments from the EPA to the community, holding lunches like the one earlier this month.

The Providence-based nonprofit also advises the EPA on the cleanup strategy and community uses for the land post-remediation. Federal officials have built a road to truck materials to and from the site, and once the cleanup is finished, WRWC wants to convert it to walking trails.

The Oxbow area presents a unique problem for cleanup officials, as it is among one of the only forested areas in the urban area. In the past the area has been used by off-road vehicles and for birding and camping. The WRWC does not want to completely block public use of the area. Unfortunately, much of the area is contaminated, and the property is going to see some deforestation when the EPA gets to its planned cleanup. Federal officials plan on planting replacement trees.

WRWC is advocating for gentler uses of the Oxbow area once the cleanup is complete. The organization would like to install boardwalks, bird viewing areas, and kayak launches. It would also like to prohibit destructive past uses such as all-terrain vehicles.

The polluted area is a legacy from the Industrial Revolution and Rhode Island’s textile boon. Two companies, the Olneyville Wool Combing Co. and the Centredale Worsted Mills, used the property, and the river, as a disposal site for toxic byproducts.

By the early 1940s, the site was home to two new companies: the Atlantic Chemical Co., which changed its name in 1953 to Metro-Atlantic Inc., and the New England Container Co. Both companies continued to produce chemicals on-site and dump waste in the river. Company buildings were demolished in the 1970s, with construction of Centredale Manor and Brook Village beginning later in the decade.

The Brook Village apartments opened in 1977, after construction had been delayed by DOH officials. While investigating complaints of noxious fumes, they found some 50 abandoned metal drums on the site. A later investigation in the early ’80s by the Rhode Island Department of Environmental Management turned up more. The drums were filled with polychlorinated biphenyls (PCBs) and other caustic materials.

Centredale Manor opened in 1982.

The EPA and the Department of Justice reached a settlement with the New England Container Co. in 2015. The company agreed to pay $8.75 million to resolve its liability. Federal officials said the money was used to clean up the site. Further litigation against two Stanley Black & Decker Inc. subsidiaries led to a $100 million settlement.

DOH officials said, as of the latest data they have, that the Centredale Manor Superfund site has caused no significant cancer clusters.

“There wasn’t a clear pattern the last time we looked into the area,” DOH official Michael Burns said. “It’s definitely something that is difficult to look into.”

To watch a video that provides an aerial view of the Superfund site, click here.