Technical Term Definitions

Greenpoint Petroleum Remediation Project Photo

Aeration - The process by which air is circulated through or mixed with a substance, where oxygen and other agents convert organic wastes and other materials to forms that may be less harmful to the environment.

Air Stripping – A chemical engineering technology used for the purification of groundwater and wastewater containing volatile organic compounds with a high vapor pressure. As the water descends in a tank, air is forced up through the column, stripping off the volatile organic compounds.

Aquifer - An underground layer of rock or unconsolidated materials (gravel, sand, silt, or clay) that contain groundwater.

Backwash - The process of cleaning a filter by reversing the flow of water through it with the dirt and rinse water going to waste.

Biodegradation - The process by which organic substances are broken down by microorganisms (bacteria). Organic material can be degraded aerobically (with oxygen), or anaerobically (without oxygen).

Boom – A temporary floating barrier used to contain pollution.

Bulkhead – A weight-bearing retaining wall along a waterfront designed to prevent sliding or erosion of the land into the water (similar to a seawall).

Cone of Depression - Occurs in an aquifer when groundwater is pumped from a well and the water level around the well drops.

Consent Order - A binding legal agreement between parties. In the case of Greenpoint, it is the government requiring responsible parties to clean up the petroleum contamination in the subsurface.

Dual Pump System – System where both groundwater pump and product pumps are installed in the recovery well. As groundwater is pumped from the subsurface to a water treatment system, free-product flows into the cone of depression that formed around the recovery well.

Effluent – Treated groundwater that flows out from a treatment plant into a body of water. For the Greenpoint Petroleum Remediation Project, this discharge is typically to Newtown Creek.

Filtration - A mechanical or physical operation which is used for the separation of solids from liquids.

Free product – Any petroleum contamination that exists as a separate material that does not mix with or dissolve in water. Because petroleum is lighter than water, free product is usually floating on top of groundwater. Also known as Free Phase and Non-Aqueous Phase Liquid (NAPL).

Influent – Anything flowing into something. For the Greenpoint project, this typically means extracted groundwater flowing into a treatment system.

Oil-Water Seperators (OWS) – A device designed to separate oil and suspended solids from influent water.

Operable Unit (OU) – a portion of the site that for technical or administrative reasons can be addressed separately to investigate, eliminate or mitigate a release, threat of release or exposure pathway resulting from the site contamination. The Operable units were proposed by ExxonMobil and approved by DEC to make cleanup faster and more manageable.

Plume – The geographic area where contamination below the ground surface either in groundwater or as free phase contamination has spread.

Recovery – The removal of free product petroleum contamination from below the ground surface.

Residual Petroleum Contamination – Petroleum contamination remaining in the soil once all recoverable free product has been removed.

Semi-Volatile Organic Compound (SVOC) - A large group of carbon-based chemicals with higher vapor pressures than volatile organic compounds (VOCs) and therefore evaporate or change from a liquid to a gas at room temperature much more slowly than VOCs.

Sheen - A very thin layer of oil (less than 0.0001 inches or 0.003 mm) floating on the water surface. Petroleum sheens vary in color ranging from rainbows, grays, and silvers for the thicker layers to almost transparent for the thinnest layers. Organic sheen can be white, light grey, or colorless, and is often associated with leaves, and other debris, and may sometimes be considered “garbage” sheen.

Skimmer pump – Pump installed in the recovery well that removes free-product floating on top of groundwater without removing groundwater. Most common type of skimmer pumps used at the Greenpoint Petroleum Remediation Project are Spill Buster units.

Soil Gas – Vapors that exist below the ground surface.

Summa Canister – An evacuated (empty) vessel typically made of stainless steel that is used to collect an instantaneous air sample.

Test Pit – an excavation or trench dug into the ground to observe subsurface soil conditions and determine if contamination is present. It is intended to get a larger indication of the presence of contamination, if any, than a single point sample.

Total Fluids Pump – Pump installed in the recovery well that removes both free-product and groundwater.

Vapor Extraction / Recovery – A soil remediation technique where a vacuum is applied to the ground and contamination is removed as a gas. The contaminants pulled from the soil are separated into liquids and vapors, and treated as necessary. Typically referred to as soil vapor extraction (SVE) or sub-slab depressurization (SSD) systems.

Volatile Organic Compound (VOC) - A large group of carbon-based chemicals that evaporate or change from a liquid to a gas at room temperature. VOCs are often components of petroleum fuels, hydraulic fluids, paint thinners, and dry cleaning agents.

Water Table – The top of groundwater in an aquifer is known as the water table.

Waterflooding Technology – A remediation method where water is injected into the ground to move free product in an attempt to increase the amount of recovery.


This page was last reviewed on Thursday, April 17, 2014.