Glossary

For additional definitions, please visit the Glossary of Environmental Terms at the California Department of Toxic Substances Control's website.

Administrative Consent Agreement A legally binding contract between a lead agency and responsible party that serves to resolve an environmental violation through an administrative settlement agreement rather than through a court action.
Applicable, Relevant, and Appropriate Requirements (ARARs) Federal or state laws, regulations, standards, criteria, or requirements that would apply to the cleanup of hazardous substances at a particular site.
Area of Concern (AOC) Areas outside of the source remediation site that are being evaluated and may be contaminated due to past practices and/or proximity to the source site. These areas are subject to the overall site’s environmental investigation to determine if they will also need to be remediated.
California Environmental Quality Act (CEQA) A law mandating review of environmental impact of governmental actions. It requires that public agencies study the significant environmental effects of proposed activities and that the public be informed and allowed to comment on project decisions.
Chemical Reduction Typical chemical reduction/oxidation process (sometimes referred to as Redox) reactions chemically convert hazardous contaminants to nonhazardous or less-toxic compounds that are more stable, less mobile, and/or inert. Redox reactions involve the transfer of electrons from one compound to another. Specifically, one reactant is oxidized (loses electrons) and one is reduced (gains electrons).
Clearinghouse Task Force (CTF) A group formed to develop and implement processes and tools to improve communications and enhance Topock stakeholder understanding of Project technical and regulatory information.
Community Outreach Plan (COP) A plan that documents community concerns about a site and identifies specific actions to respond to them. The COP outlines the preferred ways to involve the community in the DTSC decision-making process.
Community Survey A survey prepared by the California Department of Toxic Substances Control (DTSC) and distributed to the community surrounding a project site. The survey is a tool to gather information about the community’s level of awareness and interest in a project site, understand specific concerns about a project site, and to gather project-specific public involvement questions or concerns.
Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) Commonly known as Superfund, this law created a tax on the chemical and petroleum industries and provided broad federal authority to respond directly to releases or threatened releases of hazardous substances that may endanger public health or the environment. CERCLA established prohibitions and requirements concerning closed and abandoned hazardous waste sites, provided for liability of persons responsible for releases of hazardous waste at these sites, and established a trust fund to provide for cleanup when no responsible party could be identified. The law authorizes two kinds of response actions: short-term removals, where actions may be taken to address releases or threatened releases requiring prompt response; and long-term remedial response actions that permanently and significantly reduce the dangers associated with releases or threats of releases of hazardous substances that are serious, but not immediately life-threatening.
Consent Decree An agreement between a lead agency and responsible party in which the responsible party commits to investigate the nature and extent of contamination at and surrounding a site governed by CERCLA, and related remedial actions addressing contamination, and to take corrective action.
Corrective Action Consent Agreement (CACA) A voluntary agreement between a lead agency and responsible party in which the company commits to investigate the nature and extent of contamination at and surrounding a site governed by Resource Conservation and Recovery Act (RCRA), and to take corrective action.
Corrective Action Specific activities designed to clean up contamination at a site resulting from present and past hazardous waste handling practices.
Corrective Action Process A process designed to evaluate the nature and extent of releases of a hazardous substance and implement appropriate measures to protect public health and the environment.
Corrective Measures Implementation (CMI) Once a remedy has been selected, the facility enters the CMI phase of corrective action. During the CMI, the owner/operator of the facility implements the chosen remedy.
Corrective Measures Study/Feasibility Study (CMS/FS) A study conducted by the facility owner/operator to identify and evaluate alternative remedies (i.e., cleanup options) to address contaminant releases at a site.
Consultative Workgroup (CWG) A group consisting of stakeholders and multiple state and federal agencies that have an interest in the cleanup of a contaminated site, and meet regularly to discuss actions and make decisions.
Department of the Interior (DOI) The United States department charged with conservation and development of natural resources. The U.S. Department of the Interior uses sound science to manage and sustain America’s lands, water, wildlife, and energy resources, honors our nation’s responsibilities to tribal nations, and advocates for America’s island communities.
Department of Toxic Substances Control (DTSC) The department within the California Environmental Protection Agency in charge of the regulation of hazardous waste from generation to final disposal. DTSC oversees the investigation and cleanup of hazardous waste sites.
Environmental Impact Report (EIR) A report designed to examine the potential environmental impacts of proposed activities.
Final Remedy The final cleanup action proposed for managing contaminants at a project site.
Freshwater Flushing Moving of fresh water through the well system to push the plume through an In Situ Reduction ZoneAn area below ground where contamination levels in the plume are reduced in a cleanup. located along National Trails Highway.
Groundwater Water beneath the Earth’s surface that flows through soil and rock openings (aquifers).
Hexavalent chromium Hexavalent chromium is a form of chromium. Chromium is a metal naturally found in rocks, soil, and the tissue of plants and animals. Hexavalent chromium can be found naturally at low concentrations, but it is also used in industrial products and processes and is a known carcinogen. On May 28, 2014, the California Department of Public Health adopted a new California drinking water standard at 10 parts per billion for hexavalent chromium.
In Situ Reduction Zone (IRZ ) An area belowground where contamination levels in the plume are reduced in a cleanup.
In Situ Treatment Treatment of contamination in place.
Information Repository (IR) Designated locations that provide public access to site-related documents as required by the DTSC.
Initial Study Pursuant to CEQA, an analysis of a project's potential environmental effects and their relative significance. An initial study is preliminary to deciding whether to prepare a negative declaration or an EIR.
Interim Measures (IM) Cleanup actions taken to protect public health and the environment while long-term solutions are being developed.
Notice of Determination A notice that is sent by the lead agency to notify agencies and the public whether or not the project was determined potentially to have a significant effect on the environment.
Notice of Exemption The environmental document that is prepared for projects or actions that meet specific criteria for exemption from the requirements of the California Environmental Quality Act. Examples of actions meeting such criteria include those taken to restore property damaged in a disaster area and specific actions designed to prevent an emergency.
Notice of Preparation (NOP) A notice that is sent by the lead agency to notify agencies and the public that an EIR is being prepared and to request input on the content of the EIR.
Parts per billion (ppb) A unit of measure used to describe levels or concentrations of contamination. One part per billion is the equivalent of one drop of contaminant in one billion drops of water.
Percolation Beds An unlined bed with built-up sides constructed of soil that collects discharged wastewater and allows it to soak into the ground and/or evaporate.
Plume A body of contaminated groundwater. The movement of a groundwater plume can be influenced by such factors as local groundwater flow patterns, the character of the aquifer in which the groundwater is contained, and the density of contaminants.
Proposed Plan A plan for a site cleanup that is available to the public for comment.
Public Participation Plan A plan that documents community concerns about a site and identifies specific actions to respond to them. The Plan outlines the preferred ways to involve the community in the DTSC decision-making process. The Public Participation Plan has been superseded by the Community Outreach Plan (COP).
Record of Decision A public document that explains which cleanup alternative(s) will be used at cleanup sites under CERCLA.
Remedy The cleanup action proposed for dealing with contaminants at a site.
Remediation Actions taken to remove or contain a toxic release or spill of hazardous substances at a site.
Resource Conservation and Recovery Act (RCRA) A 1976 amendment to the first federal solid waste legislation, the Solid Waste Disposal Act of 1965. In RCRA, Congress established initial directives and guidelines for the U.S. EPA to regulate and manage solid waste, including hazardous waste. RCRA established a regulatory system to track hazardous substances from the time of generation to final disposal. The law requires safe and secure procedures to be used in treating, transporting, storing, and disposing of hazardous wastes. RCRA was designed to prevent new, uncontrolled hazardous waste sites.
RCRA Facility Assessment (RFA) A detailed, preliminary site assessment of a treatment, storage, and disposal facility that may be required to undergo some form of corrective action under RCRA. The first step in the corrective action process, an investigation to determine whether or not potential substances or other constituents of concern exist in soils or groundwater at or near a facility. A lead agency, such as DTSC, gathers information about potential chemical releases relative to chemical usage, storage, and treatment at the site.
RCRA Facility Investigation/Remedial Investigation (RFI/RI) An investigation that occurs in the corrective action process following a Facility Assessment under RCRA and/or a Site Inspection under CERCLA. It is an in-depth study designed to gather data needed to determine the nature and extent of contamination at a site.
Risk Assessment A study prepared to assess health and environmental risks due to potential exposure to hazardous substances.
Statement of Basis A document that describes the basis for DTSC's proposed remedy and cleanup standards.
Surface Water Water collecting on the ground or in a stream, river, lake, wetland, or ocean.
Solid Waste Management Unit (SWMU) An area outside of the source remediation site that is being evaluated and may be contaminated due to the management of solid wastes without proper protective practices in place. The SWMU is subject to the overall site’s environmental investigation to determine if it will also need to be remediated.
Technical Work Group (TWG) A focused stakeholder subgroup of the Consultative Work Group (CWG) where various stakeholders and their consultants discuss technical Project-related issues in greater detail, which are then reported back to the CWG.
Time-Critical Removal Action (TCRA) A time-sensitive action to stabilize and mitigate the threat of release of contaminated material. It is not intended to substitute for any remedial activities or be the final remedy.
Topock Leadership Partnership (TLP) A forum that enables senior officials to provide input to the regulatory agencies on the direction of actions necessary to complete the Topock project.

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