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Section 1: Regulatory Context of the HRS

Section 105(a)(8)(B) of CERCLA, as amended, requires that the statutory criteria provided by the Hazard Ranking System (HRS) be used to prepare a list of national priorities among the known releases or threatened releases of hazardous substances, pollutants, or contaminants throughout the United States. The list, which is Appendix B of the National Contingency Plan (NCP), is the National Priorities List (NPL).

The HRS is the primary tool that EPA uses to place sites on the NPL. As a part of the Superfund cleanup process, the NPL is primarily to serve as an information and management tool. The identification of a site for the NPL is intended primarily to guide EPA in:

  • determining which sites warrant further investigation to assess the nature and extent of the human health and environmental risks associated with a site;
  • identifying what CERCLA-financed remedial actions may be appropriate;
  • notifying the public of sites EPA believes warrant further investigation; and
  • serving notice to potentially responsible parties that the EPA may initiate CERCLA-financed remedial action.

Inclusion of a site on the NPL does not in itself reflect a judgment of the activities of its owner or operator, it does not require those persons to undertake any action, nor does it assign liability to any person. The NPL serves primarily informational purposes, identifying for the States and the public those sites or other releases that appear to warrant remedial actions.


CERCLA, referred to as "Superfund," was passed in 1980 to fill a gap in the nation's environmental laws (highlighted by Love Canal, NY).

CERCLA established a $1.6 billion trust fund for 5 years to fund:

  • removal actions (short-term responses);
  • remedial actions (long-term responses); and
  • legal enforcement and cost-recovery actions.

CERCLA responses are limited to actual or threatened releases of "hazardous substances" and to actual or threatened releases of "pollutants or contaminants" that "may present an imminent and substantial danger to the public health or welfare." This "Superfund" was originally funded through taxes, but is a revolving fund. CERCLA provides that the government can recover response cost from responsible parties and use these funds for additional response.

CERCLA also requires the establishment of a National Priorities List (NPL) : "a list of the releases of hazardous substances that present the greatest threats to human health and the environment."

For more information on CERCLA view the CERCLA Overview.

1.2 The Hazard Ranking System

A site's HRS score can range from 0 to 100. The HRS was established in 1982 to rank hazardous waste sites so that the most serious could be included on the NPL.

A cutoff score of 28.50 was established for listing on the NPL.

  • This score was set to meet the Congressional mandate of 400 sites on the original NPL.
  • This score appears to flag 5 to 10 percent of all sites as NPL sites. (Since 1991, EPA has, on average, added 30 sites per year to the NPL.)

1.3 SARA

The Superfund Amendments and Reauthorization Act (SARA) of 1986 extended and increased the CERCLA trust fund. SARA Overview.

  • Funded at $11.97 billion through 1994.

SARA also required EPA to revise the HRS:

"... shall ensure, to the maximum extent feasible, that the hazard ranking system accurately assesses the relative degree of risk to human health and the environment posed by sites and facilities subject to review."

SARA also required many specific revisions to the HRS. These are detailed in the preamble to the HRS Rule. HRS Training Section 1: Regulatory Context of the HRS Section-by-Section Analysis of Rule Changes, 55 FR 51569 - 51581. Some examples of revisions include the following:

  • SARA 105(a)(8)(A) requires EPA to take into account the damage to natural resources that may affect human food chain and the potential to release to ambient air. Both of these considerations are in the revised HRS.
  • SARA 118 required EPA to give high priority to sites where contamination has resulted in closing of drinking water wells, or has contaminated a principal drinking water supply. Therefore, the revised HRS gives greater weight (higher scoring points) to actually contaminated targets.

A substantially revised HRS was promulgated in 1990 (the one currently used).

1.4 Hazardous Substances

The HRS rule, page 51586 defines hazardous substances as:

"CERCLA hazardous substances, pollutants, and contaminants as defined in CERCLA sections 101(14) and 101(33), except where otherwise specifically noted in the HRS."

CERCLA 101(14) defines hazardous substances by referring to definitions in other laws.

  • A list of over 600 CERCLA hazardous substances is provided in 40 CFR 302.4.

CERCLA 101(33) defines pollutants or contaminants in terms of their negative impact on people and the environment:

The term "pollutant or contaminant" shall include, but not be limited to, any element, substance, compound, or mixture, including disease-causing agents, which after release into the environment and upon exposure, ingestion, inhalation, or assimilation into any organism, either directly from the environment or indirectly by ingestion through food chains,will or may reasonably be anticipated to cause death, disease, behavioral abnormalities, cancer, genetic mutation, physiological malfunctions (including malfunctions in reproduction) or physical deformations, in such organisms or their offspring; except that the term pollutant or contaminant shall not include petroleum, including crude oil or any fraction thereof which is not otherwise specifically listed or designated as a hazardous substance... and shall not include natural gas, liquefied natural gas, or synthetic gas of pipeline quality (or mixtures of natural gas and such synthetic gas).

These negative impacts must be documented if a pollutant or contaminant is used for HRS scoring. (For example, one NPL site was scored solely on nitrates. The documentation record included a reference that showed that the concentration in ground water was above safe levels for infants. The U.S. District Court of Appeals upheld EPA in the listing of the site.)- see Apache Powder Company v.EPA, No.90-1543, June 1992

The HRS definition of hazardous substances includes both CERCLA hazardous substances and "pollutants or contaminants."

1.5 HRS Definitions of Site and Source

HRS definitions of site and source:

  • The HRS rule, section 1.1 on page 51587:

"Site: Area(s) where a hazardous substance has been deposited, stored, disposed, or placed, or has otherwise come to be located."

"Source: Any area where a hazardous substance has been deposited, stored, disposed, or placed, plus those soils that have become contaminated from migration of a hazardous substance. Sources do not include those volumes of air, ground water, or surface water sediments that have become contaminated by migration, except: in the case of either a ground water plume with no identified source or contaminated surface water sediments with no identified source, the plume or contaminated sediments may be considered a source."

EPA lists sites on the NPL. HRS scores are calculated based on the characteristics of sources at the site and other factors.

The site boundary generally will not be identical to the facility property boundary.

1.6 CERCLA Definition of Release

What Constitutes a Release Under CERCLA? Section 101(22).

"[A]ny spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into the environment (including the abandonment or discarding of barrels, containers, and other closed receptacles containing any hazardous substance or pollutant or contaminant)... "

Remember: EPA can respond to, and list on the NPL, both actual and threatened releases.

Who Must Be Notified?

1.7 Statutory and Policy Exclusions

A number of statutory and policy provisions affect a site's eligibility for CERCLA response actions and listing on the NPL. If any of the following issues arise at a site, contact your EPA Regional NPL Coordinator. Exclusions should not be discovered at the HRS scoring stage. These issues should be resolved at the PA or SI stage. However, new information may become available during scoring and, thus, HRS scorers should be familiar with the general site eligibility considerations.

Petroleum Exclusion

  • Petroleum, natural gas, natural gas liquids, liquefied natural gas, or synthetic gas usable for fuel are excluded from consideration under CERCLA.
  • The petroleum exclusion includes the substances found in products coming out of a refinery, including gasoline with additives such as 1, 2-dichloroethene and lead tetraethyl.
  • Whenever it is suspected that the petroleum exclusion may apply to a site, consult the EPA Regional NPL Coordinator.

HRS Guidance Manual, page 19:  CERCLA Sections 101(14) and (33) exclude petroleum from the definitions of "hazardous substances" and "pollutant or contaminant," respectively. The exclusion applies to petroleum, including crude oil or any fraction thereof (if the fraction is not specifically listed nor designated a hazardous substance by other listed acts), natural gas, natural gas liquids, liquefied natural gas, and synthetic gas usable for fuel.

The Regional Quality Control (QC) Guidance for NPL Candidate Sites (OSWER Publication 9345.1-08, December, 1991) identifies several issues to consider when scoring a site possibly containing petroleum or petroleum products:

  • CERCLA does not define petroleum. Crude petroleum includes a number of hazardous substances that would otherwise be CERCLA hazardous substances, such as benzene, toluene, xylene, and ethylbenzene. In their pure forms, these substances remain hazardous substances and can be scored. When they are part of, or released directly from, a petroleum product, they cannot be used in scoring.
  • The presence of petroleum products at a site, as a part of site contamination, does not exclude the site from consideration. Sites are excluded if they contain only excluded petroleum products.
  • Releases of petroleum products contaminated with hazardous substances (i.e., used oil/waste oil contaminated with metals or PCBs) can be listed if the hazardous substances cannot be separated from the petroleum.
  • If two distinct plumes commingle, one of petroleum and one of a hazardous substance that can be listed, the release can be listed; however, only the non-petroleum plume (including the intersection of the plumes) can be used in HRS scoring.
  • A petroleum release can be used to show aquifer interconnection for purposes of evaluating a site containing eligible substances."

Radioactive Materials

A limited category of radioactive materials is excluded from CERCLA consideration. They are:

  • Releases from a nuclear facility licensed by the Nuclear Regulatory Commission (NRC) and covered under NRC financial protection provisions.
  • Releases from one of 17 uranium tailings sites specifically designated in the Uranium Mill Tailings Radiation Control Act of 1978 (UMTRCA).

HRS Guidance Manual, page 19, 20:  "Section 101(22) of CERCLA excludes a limited category of radioactive materials from the statutory definition of "release," making them ineligible for CERCLA response or the NPL. These are (1) releases of source (uranium or thorium, or any combination of the two, in any physical or chemical form), by-product (any radioactive material that was made radioactive by exposure to radiation from the process of using or producing special nuclear material), or special nuclear material (plutonium, uranium-233, enriched uranium-233 or -235, or any material that the NRC determines to be special nuclear material (not including source material)) subject to section 170 of the Atomic Energy Act; and (2) any release of source, by-products, or special nuclear material from any processing site specifically designated under the Uranium Mill Tailings Radiation Control Act of 1978.

The exclusion of these substances does not exclude other types of radioactive materials. Reporting Exemptions for Certain Radionuclide Releases. However, it is Agency policy not to list releases of radioactive materials from facilities with a current license issued by the NRC (e.g., certain medical facilities, manufacturing plants, research laboratories). These facilities are under the authority of the NRC which is responsible for requiring and overseeing cleanup at these sites. All other types of radioactive materials sites, including state licensees and former NRC licensees, are eligible for the NPL."

Other Excluded Releases

Certain releases are excluded from response by CERCLA statute, even though they may involve a CERCLA hazardous substance, pollutant, or contaminant. These include:

  • Releases that result in exposure solely within the workplace;
  • Emissions from engine exhaust of a motor vehicle, train, aircraft, vessel, or power pumping station; and
  • The normal application of fertilizer.

1.8 Policy Considerations in Listing Sites

Historically, the listing of certain types of sites, although eligible for scoring, has raised policy issues for EPA. These types of sites should be discussed with EPA Regional NPL Coordinators.

  • Resource Conservation and Recovery Act (RCRA) Subtitle C treatment, storage, or disposal facilities (HRS Guidance Manual, page 20);
  • Facilities with a current license issued by the NRC;
  • Environmental problems that have resulted from the legal application of pesticides permitted under the Federal Insecticide, Fungicide and Rodenticide Act; and
  • Ground water plumes or contaminated surface water sediments where the source is currently unknown. Such sources could, for instance, be subjected to RCRA Subtitle C and deferred to that authority.

1.9 Questions and Answers

There is a mine tailings pile and large area of soil contaminated by wind-blown particulate. In addition, the ground water under the pile is contaminated and there are contaminated sediments in a nearby stream. How many sources are there?

Two. The tailings pile and the area of contaminated soil. The contaminated ground water and surface water sediments are considered releases from the sources.

If an intact drum of hazardous substances is found lying in a field, is it a CERCLA release?

Yes, if the drum has been "abandoned or discarded."

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