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Glossary Of Environmental Cleanup Terms G Through P

This glossary lists common terms related to New York State Department of Environmental Conservation's voluntary cleanup, brownfield, and inactive hazardous waste disposal site programs.


Environmental Cleanup Terms from G to P
Term Description
Gas venting system A system of pipes and vents installed in a landfill to prevent the build up of landfill gases, such as methane, that could potentially explode. Sometimes the gas vents have flares on them to burn the gas as it is released into the atmosphere. At some very large landfills, the gas is collected and used to generate electricity.
Geomembrane A low permeability plastic sheet that is placed over a landfill to deter rain and snow from entering a landfill's waste. Geomembranes are often made from a plastic called HDPE (high density polyurethane). The geomembrane is covered with soil (barrier protection layer) and top soil to protect it.
Geophysical surveys Techniques used to characterize the subsurface without having to dig up large areas. Examples include seismic refraction (commonly used to determine depth to bedrock), ground-penetrating radar (used to define sub-surface structures and buried objects), and magnetometry (used to detect buried iron objects).
GeoprobeTM A special machine used to make soil borings and to create temporary groundwater monitoring wells.
Gram(g) The unit of mass in the metric system. An ounce is about 28 grams, and a pound is approximately 450 grams.
Granular activated
carbon treatment
A filtering system often used in small water systems and individual homes to remove organic compounds. See activated carbon.
Groundwater Water found beneath the earth's surface that fills pores between soil particles such as sand, clay, and gravel or that fills cracks in bedrock. Precipitation that does not evaporate or runoff to surface waters percolates downward through soil and becomes groundwater. Groundwater flows from areas of high elevation to low elevation at generally low velocities (usually ranging from 10-1000 feet/year) and eventually discharges into surface waters such as rivers, lakes, and wetlands. Groundwater often provides a source of drinking water via wells. The chemical composition of the groundwater reflects the soil or bedrock through which it passes; groundwater dissolves minerals in the soil and bedrock. If a source of contamination exists at or below the earth's surface, percolating rainfall or snowmelt can transport contaminants downward where they can migrate with the groundwater.
Groundwater collection/
extraction and
treatment system
A system of wells fitted with pumps and piping used to pump out or extract contaminated groundwater from the subsurface. Properly designed and operated systems can effectively contain a groundwater contaminant plume and prevent further contaminant migration.
Groundwater table See Water Table
Half-life (1) The time required for a pollutant to lose half its effect on the environment. (2) The time required for half of the atoms of a radioactive element to undergo decay. (3) The time required for the elimination of one half a total dose from the body.
Hammer mill A high-speed machine that uses hammers and cutters to crush, grind, chip, or shred solid waste.
Hazardous ranking system
A scoring system used to evaluate potential relative risks to public health and the environment from releases or threatened releases of hazardous materials. EPA and States use the HRS to calculate a site score (0 to 100) based on the actual or potential release of hazardous materials from a site through air, surface water, or groundwater. This score is the primary factor used to decide if a hazardous waste site should be placed on the National Priorities List.
Hazardous waste A waste which appears on the list or satisfies the characteristics according to ECL 27-0903 and any substance which appears on the list found in ECL 37-0103; provided, however, that the term "hazardous waste" does not include:
i. natural gas, natural gas liquids, liquefied natural gas, synthetic gas usable for fuel, or mixtures of natural gas and such synthetic gas; nor
ii. the residue of emissions from the engine exhaust of a motor vehicle, rolling stock, aircraft, vessel, or pipeline pumping station engine; nor
iii. source, byproduct, or special nuclear material from a nuclear incident, as those terms are defined in the Atomic Energy Act of 1954; nor
iv. oil or petroleum of any kind and in any form including but not limited to, oil, petroleum, fuel oil, oil sludge, oil refuse, oil mixed with other wastes and crude oils, gasoline, kerosene and dielectric fluids.
Hazardous waste site A place where hazardous wastes have been dumped, buried or improperly stored. Sites range from a crest of land containing thousands of tons of chemical wastes to a few drums of solvents dumped in a vacant lot. See also inactive hazardous waste disposal site.
Health and safety plan A plan included in investigation or cleanup work plans which outlines protective measures for site workers and the community during investigation or cleanup activities.
Health hazard Anything which can have harmful effects on health. There can be both acute and chronic health hazards.
Health risk assessment A process which estimates the likelihood that people who could be exposed to chemicals may have health effects. The four steps of a risk assessment are: (1) hazard identification (Can this substance damage health?), (2) dose-response assessment (What dose causes what effect?), (3) exposure assessment (How and how much do people contact it?), and (4) risk characterization (combining the other three steps to estimate risk).
Heavy metals Metals with high atomic weights, such as mercury, chromium, cadmium, arsenic, and lead. They can damage living things at low concentrations and tend to accumulate in the food chain.
Herbicide A chemical used to control, suppress, or kill plants, or to severely interrupt their normal growth process.
Heterogeneous Consisting of dissimilar ingredients or constituents.
Historic fill material Non-native material, historically deposited or disposed in the general area of a site to create useable land by filling water bodies, wetlands or topographic depressions, which is in no way connected with the subsequent operations at the location of the emplacement, and which was contaminated prior to emplacement.
Homogeneous Having a uniform consistency or ingredients; composed of similar ingredients.
Hydraulic Operated, moved or effected by means of water.
Hydraulic conductivity The rate at which water can move through a permeable medium.
Hydraulic gradient In general, the direction of groundwater flow due to changes in the depth of the water table. Just as water flows downhill, water in the ground moves from areas of high elevation to areas of low elevation. The slope of the water table is the hydraulic gradient. The hydraulic gradient determines the speed of groundwater flow. A steep gradient causes groundwater to mover faster than a nearly horizontal gradient.
Hydrocarbon Any of a series of chemical compounds that consist entirely of carbon and hydrogen.
Hydrogen Release Compound
Hydrogen Release Compound (HRCTM) is a passive treatment option for bioremediation of chlorinated solvents. HRCTM is injected into contaminated soils. Naturally occurring microbes metabolize lactic acid released by HRCTM, and produce hydrogen. The resulting hydrogen can be used to break down the chlorinated solvents. The process requires anaerobic conditions. Major target compounds include perchloroethene, trichloroethene, and trichloroethane as well as their breakdown products.
Hydrogeologic testing Physical tests performed to obtain specific groundwater and geologic data. A pump test, for example, is used to determine the permeability (a measure of how readily groundwater flows) and storage capacity (a measure of the amount of water available) of an aquifer.
Hydrogeology The geology of groundwater, with particular emphasis on the chemistry and movement of water.
Hydrology The study of the movement and properties of water on the earth's surface, underground and in the atmosphere.
Impermeable Unable to be penetrated, as by liquids. For example, an "impermeable membrane" can be a thin plastic sheet through which rainwater cannot move.
Inactive hazardous waste
disposal site
A hazardous waste site where disposal of hazardous wastes has been confirmed and wastes are no longer being disposed of there ("inactive" site).
Incineration Burning of certain types of solid, liquid, or gaseous materials under controlled conditions to destroy hazardous wastes.
Infiltration The penetration of water through the ground surface into sub-surface soil or the penetration of water from the soil into sewer or other pipes through defective joints, connections, or manhole walls. (See: percolation.)
Influent Water, wastewater, or other liquid flowing into a reservoir, basin, or treatment plant. The opposite of effluent.
Ingestion Swallowing. This is one way a person can be exposed to chemicals.
Inhalation Breathing. This is one way a person can be exposed to chemicals.
Inorganic chemicals/
Chemicals that do not contain carbon. Metals are inorganic chemicals.
In-Situ In the original place. In-situ treatment is carried out at a hazardous waste site without having to dig up and move the contaminated material. In-situ is the opposite of ex-situ.
Insoluble Incapable of being dissolved in water or another liquid.
Institutional controls Any non-physical means of enforcing a restriction on the use of real property that limits human or environmental exposure, restricts the use of groundwater, provides notice to potential owners, operators, or members of the public, or prevents actions that would interfere with the effectiveness of a remedial program or with the effectiveness and/or integrity of site management activities at or pertaining to a site.
Interim remedial
measure (IRM)
Action that can be conducted at a site relatively quickly to reduce the risk to people's health and the environment from a well-defined hazardous waste problem. An IRM can involve removing contaminated soil and drums, providing alternative water supplies or securing a site to prevent access.
Land Disposal Restrictions
Federal rules that require hazardous wastes to be treated before disposal on land to destroy or immobilize hazardous constituents that might migrate into soil and groundwater.
Landfill Any place where wastes were disposed of by dumping waste and covering it. There are three main kinds of landfills: (1) Sanitary landfills are disposal sites for nonhazardous solid wastes at which the waste is spread in layers, compacted to the smallest practical volume, and covered with material at the end of each operating day. (2) Secure chemical landfills are disposal sites for hazardous waste. They are selected and designed to minimize the chance of release of hazardous substances into the environment. (3) Old landfills were built without modern day protections; these may contain hazardous wastes. Many of these landfills are being investigated and cleaned up under the State's remediation program.
Landfill cap/
landfill cover system
A layering of material over a landfill to deter rain and snowmelt from moving through the waste pile. A typical landfill cover will include a geomembrane or a layer of clay covered with a layer of low permeability soil, which in turn is covered by a layer of topsoil and seeded to encourage grass to grow. Landfill cover systems can also include gas vents to prevent gases such as methane from building up inside the landfill. The cover system is designed so rain and snowmelt is directed into a drainage ditch or swale.
Landfill gas As organic wastes within a landfill break down, gases such as methane and hydrogen sulfide are produced. The production of these gases drops off over time.
Leachate Surface or groundwater that is contaminated while moving through a landfill's wastes.
Leachate collection system A system that gathers leachate and pumps it to the surface for treatment.
Light non-aqueous phase liquid
Liquids lighter than water that represent a special class of soil and groundwater contaminants with unique behavior and problems. See also NAPL.
Liner A relatively impermeable barrier designed to keep leachate inside a landfill. Liner materials include plastic and dense clay.
List / listing When DEC adds a hazardous waste site to the Registry of Inactive Hazardous Waste Disposal Sites, this is called "listing" a site.
Listservs - Contaminated Sites The public can receive site information by email by signing up through the GovDelivery service.
Liter The unit of volume in the metric system. A liter is about the same as a quart.
Low Temperature
Thermal Desorption
The process of heating soil anywhere between 200 and 1000°F in order to vaporize contaminants with low boiling points. The vaporized contaminants are collected and treated. The low temperatures requires less fuel than other treatment methods.
magnetometer survey
A magnetometer is an instrument that can detect metal objects buried underground. When this instrument is used to look for buried drums or other metal objects at a hazardous waste site, this is called a magnetometer survey.
Manufactured Gas Plants (MGPs)

MGPs were used to produce gas from coal, oil and other fuels but are no longer in operation in New York State. However, coal tar and other hazardous waste, created as part of the manufacturing process, may still be present at those sites and require cleanup.

Maximum contaminant level The maximum permissible level of a contaminant in water delivered to any user of a public water system. MCLs are enforceable standards.
Media/medium Specific environments that can contain contaminants. Air, water, sediment and soil are media.
Metals A number of chemical elements that share certain special characteristics. Many metals can be toxic in high doses and can bioaccumulate in the food chain. Metals sometimes found at hazardous waste sites include: arsenic, barium, cadmium, chromium, copper, lead, mercury, nickel, silver, and zinc.
Methane An odorless gas produced in newer landfills as organic material (previously living things or material derived from living things) breaks down. Methane production drops off as a landfill gets older.
Methylene chloride A colorless nonflammable liquid, with a pleasant aromatic odor, used as a solvent, paint remover, and degreaser.
Micrograms per kilogram
A way of expressing dose: micrograms (ug) of a substance per kilogram (kg) of body weight or soil.
Micrograms per liter
A unit of measure: the number of micrograms of one substance in a liter of liquid. One microgram per liter means one microgram of chemical per liter of water, and is essentially equivalent to one part per billion (ppb). Theoretically one ug/l of a substance equals one part per billion of the substance multiplied by its density.
Milligrams per kilogram
A way of expressing dose: milligrams (mg) of a substance per kilogram (kg) of body weight or soil.
Milligrams per liter
A unit of measure: the number of milligrams of one substance in a liter of liquid. One milligram per liter means one milligram of chemical per liter of water, and is essentially equivalent to one part per million (ppm) at very low concentrations. Theoretically one mg/l of a substance equals one part per million of the substance multiplied by its density.
Monitored Natural Attenuation Natural attentuation that is expected to achieve site cleanup objectives within a time frame that is reasonable compared to more active cleanup methods. The natural attenuation processes are carefully monitored. Monitored Natural Attenuation is used in combination with "source control" or removing the contamination source as far as practicable.
Monitoring well (1) A well used to obtain water quality samples or measure groundwater levels. (2) A well drilled to collect groundwater samples for testing to determine the amounts, types, and distribution of contaminants in the groundwater beneath the site. The well enables samples of groundwater to be collected at a specific horizontal and vertical location for chemical analysis. Sometimes soil samples are also collected as the well is being drilled.
National Priorities List
The U.S. Environmental Protection Agency's list of the most serious uncontrolled or abandoned hazardous waste sites identified for possible long-term remedial response using money from a special trust fund (Superfund).
Natural attenuation Relying on natural (physical, chemical, or biological) processes to reduce mass, toxicity, mobility, volume or concentration of compounds in earth or groundwater. Under proper conditions, can be used for perchloroethylene (PCE), trichloroethylene (TCE), and trichloroethane (TCA) at a lower cost than conventional remediation technologies.
Natural resource All land, fish, wildlife, biota, air, water, groundwater, drinking water supplies, and other such resources belonging to, managed by, held in trust by, or otherwise controlled by the State.
New York State
Department of Health
Agency within the executive branch of New York State government which: determines potential risk from environmental exposure at hazardous waste sites; conducts health-related community outreach around sites; and reviews remedial actions to assure that public health concerns are addressed.
New York State
Department of Law
Agency within the executive branch of New York State government which takes the lead on hazardous waste site litigation. Litigation can involve negotiations and court action with responsible parties to clean up sites; natural resources damage claims, and recovery of remedial costs.
New York State
Registry of Inactive Hazardous
Waste Disposal Sites
See Registry of Inactive Hazardous
Waste Disposal Sites in New York State
Non-aqueous phase liquids
Liquids, commonly a mixture of several different chemicals, that are either denser or less dense than water. Dense NAPL (DNAPL), such as chlorinated solvents, will sink if it enters groundwater; less dense, or light NAPL (LNAPL), such as gasoline, will float on the water table. NAPL in the subsurface can be a persistent source of groundwater contamination due to its low solubility and viscosity.
exposure limits
Maximum allowable concentrations of toxic substances in workroom air for workers.
Odor threshold The lowest concentrations of a substance's vapor, in air, that can be smelled. Odor thresholds are highly variable, depending on the individual who breathes the substance and the nature of the substance.
Operable unit An administrative term used to identify a portion of a site that can be addressed by a distinct investigation and/or cleanup approach. For example, groundwater contamination at a site may be considered as one operable unit, and soil contamination at the same site may be dealt with as a second operable unit. An operable unit can receive specific investigation, and a particular remedy may be proposed. A Record of Decision is prepared for each operable unit.
Operation and maintenance
The period following construction of a remedy during which elements of the remedy must be operated and maintained. For example, after a groundwater collection and treatment system is installed (the remedial construction phase), operation of the groundwater collection system and treatment of the water would be part of the "Operation and Maintenance" phase of the remedial program. Activities could also include site inspections, groundwater well monitoring and other sampling.
Order on Consent See Consent Order
Organic (1) In chemistry, any compound containing carbon. (2) Referring to or derived from living organisms.
Organic compounds Chemicals that contain carbon.
Overburden The rock and soil in the ground above bedrock.
Oxidizer (1) A substance (compound) that will accept electrons from another compound, thus changing (oxidizing) the other compound. (2)A material which may cause combustible materials to ignite without the aid of an external ignition source (such as flame) or which, when mixed with combustible materials, increases the rate of burning of these materials.
Part 360 New York State landfill regulations, including some regulations related to old landfills that contain hazardous waste.
Part 375 The portion of New York State regulations governing inactive hazardous waste disposal sites.
Particulates Fine liquid or solid particles such as dust, smoke, mist, fumes, or smog, found in air or emissions.
Parts per billion (ppb) The concentration of a substance of air, water or soil. One ppb means that there is one part of a substance for every billion parts of the air, water or soil in which it is measured. One ppb is about one drop of dye in 18,000 gallons of water or about one second in 32 years. One ppb is 1,000 times less than one part per million.
Parts per million (ppm) The concentration of a substance in air, water or soil. One ppm means that there is one part of a substance for every million parts of the water or soil in which it is measured. One ppm is about one drop of dye in 18 gallons of water, about one inch in 16 miles, or one penny in $10,000.
Parts per trillion (ppt) The concentration of a substance in air, water or soil. One ppt means that there is one part of a substance for every trillion parts of the water or soil in which it is measured. One ppt is 1,000 times less than one part per billion.
(polychlorinated biphenyls)
A group of toxic, persistent chemicals used in transformers for insulating purposes, in gas pipeline systems as a lubricant, and in some florescent light ballasts. The sale of PCBs was banned by law in 1979, but many old transformers still contain them.
Perchloroethene See Tetrachloroethene
Percolate/ percolation The movement of water through a porous substance such as soil.
Periodic review report (PRR) A report which evaluates the institutional and engineering controls, summarizes any monitoring results and/or evaluates any operation and maintenance activities.
Permeable/ permeability The rate at which liquids pass through soil or other materials in a specified direction. Water moves easily through a "high permeability" soil (such as gravel) and very slowly through a "low permeability" soil (such as clay).
Pesticide Substance or mixture of substances intended for preventing, destroying, repelling, or mitigating any pest. Some pesticides can accumulate in the food chain and/or contaminate the environment if misused.
pH A measure of the acidity or alkalinity (how basic) of a liquid or solid material. It is related to the number of hydrogen ions in a substance.
Photo ionization detector
A hand-held instrument used to measure the overall level of volatile organic compounds in air.
Piezometer An instrument used to measure the elevation of the water table, i.e. how far below the surface groundwater is located.
Plume An area of chemicals moving away from its source in a feather-like (hence the name, plume) shape. A plume, for example, can be a column of smoke drifting away from a chimney. An area of dissolved chemicals moving with groundwater is called a "groundwater contaminant plume."
Polychlorinated biphenyls See PCBs
Polycyclic aromatic
A group of over 100 different chemicals that form during the incomplete burning of coal, oil and gas, garbage, or other organic substances like tobacco or charbroiled meat. PAHs are usually found as a mixture containing two or more of these compounds, such as soot. Some PAHs are manufactured. PAHs are found in coal tar, crude oil, creosote, and roofing tar, but a few are used in medicines or to make dyes, plastics, and pesticides. Most do not dissolve easily in water and stick tightly to soil particles.
Polynuclear aromatic
hydrocarbons (PAHs)
See polycyclic aromatic hydrocarbons
Porosity The percentage of the total volume of a given body of rock that is pore space. It is the portion of void (air) space in rock, soil, or sediment.
Potable Drinkable.
Potentially responsible
party (PRP)
Persons identified by the EPA under CERCLA or by New York State law as being responsible for the contamination at a hazardous waste site. By law, PRPs may be generators, present or former owners or operators of a site, or transporters of the hazardous substances.
PRAP See Proposed Remedial Action Plan
Precipitation (1) Rain or snow. (2) Removal of solids from liquid waste so that the hazardous solid portion can be disposed of safely.
Presumptive remedy Cleanup technique(s) that can be applied to hazardous waste sites with common characteristics. For example, old municipal landfills built without a liner often have similar characteristics. EPA has developed a "presumptive remedy" for this type of site. Essentially, EPA said "Here's a site similar in all key ways to many other sites we've cleaned up. Wouldn't it make sense to use that cleanup approach here too?"
Project manager A DEC staff member within the Division of Environmental Remediation (usually an engineer, geologist, or hydrogeologist) responsible for the remedial program at a hazardous waste site. The project manager works with the Office of Communication Services, fiscal and legal staff and the Department of Health to accomplish site-related goals and objectives.
Proposed Remedial Action
Plan (PRAP)
A document outlining alternatives considered by the Division of Environmental Remediation for the remediation of a hazardous waste site and highlighting the alternative preferred by DEC. The PRAP is based on information developed during the site's Remedial Investigation and Feasibility Study. The PRAP is reviewed by the public and other state agencies.
Public hearing A formal hearing at which the public has the opportunity to submit comments and testimony on proposed actions for the public record.
Public meeting A scheduled gathering of DEC staff and the public to give and receive information, ask questions and discuss concerns.
Publicly owned treatment
works (POTW)
A wastewater system, owned by a municipality, state, or tribe that is used for the collection, treatment, and/or disposal of sewage. Usually POTW refers specifically to the sewage treatment plant.
Pump and treat A method used to collect and treat contaminated groundwater. Typically, groundwater is collected in a well or trench and pumped to a treatment system.

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