Superfund Sites and Cleanup: A Comprehensive Guide

A Superfund site is a contaminated property that the EPA has determined poses a significant risk to human health or the environment due to hazardous substances — waste, chemical releases, or radioactive material left by former or current industrial, military, or commercial operations. Sites above a threshold hazard score are placed on the National Priorities List (NPL), making them eligible for federally directed cleanup under CERCLA.

The term “Superfund” refers to the trust fund Congress created to finance cleanups — initially capitalized through taxes on the petroleum and chemical industries, later dependent on general appropriations. The name stuck even after the dedicated tax expired.

NPL sites are not a uniform category. They include former industrial plants, federal military bases, mining operations, municipal landfills, and smelter sites. What they share is a Hazard Ranking Score (HRS) above 28.5, calculated by EPA using a standardized methodology that weighs contamination pathways — groundwater, surface water, soil, and air — against the population and sensitive environments exposed.

The program traces directly to one watershed moment: the Love Canal disaster in Niagara Falls, New York, where residents of a residential neighborhood built over a former chemical dump reported unusually high rates of illness and birth defects in the late 1970s. Federal investigation confirmed that Hooker Chemical had buried over 21,000 tons of toxic waste beneath the site decades earlier. The contamination, long sealed, had migrated into basements, schoolyards, and bodies.

Congress responded in December 1980 with the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA), signed by President Carter. CERCLA did three things simultaneously: it created a trust fund to pay for cleanups when responsible parties couldn't be identified or compelled; it gave EPA broad authority to investigate, rank, and remediate sites; and it established strict, joint, and several liability — meaning any party that contributed waste to a site could be held responsible for the full cost of cleanup.

The 1986 Superfund Amendments and Reauthorization Act (SARA) strengthened cleanup standards, introduced community right-to-know provisions, and added the Emergency Planning and Community Right-to-Know Act (EPCRA) — the legal basis for the TRI reporting that this site also covers. Subsequent amendments broadened protections for innocent landowners and sharpened cleanup criteria.

EPA's remediation framework is defined in the National Contingency Plan (NCP). A site moves through a structured sequence; each gate requires a formal EPA finding or document. The process is long — median time from NPL listing to construction completion has historically exceeded a decade for complex sites — but each phase serves a defined evidentiary purpose.

1. 1

   Site Discovery & Preliminary Assessment (PA)

   EPA or a state agency receives a complaint, referral, or discovers the site during routine environmental review. A desk-based Preliminary Assessment reviews available records (former uses, permits, spill history) to determine whether a full inspection is warranted.

2. 2

   Site Inspection (SI)

   Field investigators collect air, soil, and water samples at and around the site. The goal is to characterize what is present, in which media, at what concentrations — enough to calculate a Hazard Ranking Score.

3. 3

   Hazard Ranking Score & NPL Proposal

   EPA applies the HRS model, integrating contamination severity, migration potential, and population exposure. Sites scoring ≥ 28.5 are proposed for the NPL; a public comment period follows. Federal facility sites (military, DOE) can be listed through a separate interagency agreement process.

4. 4

   Remedial Investigation / Feasibility Study (RI/FS)

   The most resource-intensive phase. A Remedial Investigation defines the full nature and extent of contamination — what chemicals, in what concentrations, in which media, across the entire affected area. The Feasibility Study then evaluates alternative cleanup approaches against EPA's nine criteria, including long-term effectiveness, implementability, and cost.

5. 5

   Record of Decision (ROD)

   EPA issues a Record of Decision that formally selects the cleanup remedy — excavation, in-situ treatment, containment, groundwater pump-and-treat, monitored natural attenuation, or combinations. The ROD is a public document; all EPA-approved RODs are indexed in the SEMS database, which underpins the contaminant data on this site.

6. 6

   Remedial Design & Remedial Action (RD/RA)

   Engineers develop detailed design documents (Remedial Design); contractors then execute the physical cleanup (Remedial Action). This phase can span years for large, complex sites with multiple operable units — distinct zones or contamination problems addressed sequentially.

7. 7

   Construction Completion

   EPA certifies that all physical construction activities defined in the ROD are complete. This milestone does not mean the site is clean — post-construction monitoring often continues for decades, especially for groundwater plumes with long restoration timelines.

8. 8

   Post-Construction & Five-Year Reviews

   EPA conducts five-year reviews for every site where hazardous substances remain above unrestricted-use levels. These reviews assess whether the remedy remains protective of human health and the environment — a critical oversight mechanism for sites with ongoing institutional controls or engineered covers.

9. 9

   NPL Deletion

   A site is deleted from the NPL when EPA and the state determine that all cleanup objectives have been met and no further action is needed. Partial deletion applies to portions of large multi-operable-unit sites. Deleted sites remain indexed in SEMS; their cleanup history is permanent public record.

EPA's SEMS database records contaminants of concern at each NPL site — the chemicals named in formal decision documents (Records of Decision and related). A single site may list dozens to hundreds of distinct chemicals across multiple media. The most contaminated site in our database, the Savannah River Site (Usdoe) in South Carolina, carries 395 distinct contaminants.

Contamination type varies systematically by site origin. Industrial and chemical manufacturing sites dominate for volatile organic compounds and heavy metals. Former military installations disproportionately appear in the PFAS and solvent categories. Department of Energy sites carry radioactive contamination — cesium, uranium, technetium — that is essentially absent from civilian industrial sites.

Contaminants across the NPL span several health-endpoint categories. Classifications below follow EPA and ATSDR designations:

PBT = Persistent, Bioaccumulative, and Toxic. Classifications per EPA TRI and ATSDR priority substance lists. Carcinogen designations per IARC Group 1 or EPA carcinogen weight-of-evidence Category A/B1.

Pollution Analyst's current database spans 1,814 NPL sites across all 50 ingested states, drawn from EPA's Superfund Enterprise Management System (SEMS) as of the 2026-05-11 pipeline run. This total combines NPL Final sites (under active or completed cleanup oversight) and a smaller number of NPL Deleted sites where EPA has certified cleanup completion.

The top 10 most contaminated sites by distinct contaminants reported are led by federal facilities — particularly Department of Energy nuclear production sites and Cold War-era military installations, which carry both chemical and radioactive contamination across enormous acreages.

Source: EPA SEMS via Pollution Analyst pipeline, 2026-05-11. Contaminant count = distinct (contaminant, medium) pairs cited in EPA decision records. Full top-20 ranking →

Superfund sites are not randomly distributed across communities. Decades of environmental justice research — and EPA's own EJScreen data before the tool was retired in 2025 — document a consistent pattern: NPL sites are disproportionately located near communities that are lower-income, have higher shares of people of color, and face cumulative environmental burdens from other sources.

This site surfaces the equity context on every NPL site page: population demographics within a 1-mile buffer, national EJ percentile ranks per indicator, and EPA's EJ disparity scores. A score above 150 is widely considered notable; above 200 is severe.

Example: Hunters Point Naval Shipyard, San Francisco

The Hunters Point pattern is not unusual for Superfund sites in urban industrial areas. The equity overlay on every site page is drawn from Census ACS 2018–2022 block-group demographics and the EPA-maintained EJ disparity data published via the USEPA-clone/ejamdata repository.

Pollution Analyst publishes a page for every NPL site in the database, organized by state and county. Each site page shows contaminant records from EPA SEMS, nearby groundwater public water systems, and the equity context for surrounding block groups.

By national ranking — the Superfund rankings page lists the top 20 most contaminated sites nationally and the top 10 sites with the most nearby groundwater utilities. This is the fastest way to identify the highest-complexity sites across the country.

By state — each state page includes a table of all NPL sites in the state with status, primary contaminant, and federal facility flag. Navigate to any state via the States menu or the homepage.

By city or county — county and city pages include a Superfund section listing every NPL site within the jurisdiction, with direct links to site profiles.