Oil Water Separator Glossary
Stormwater and Oil Water Separator Glossary
Anadromous fish: Fish (such as Salmon) that ascend rivers from the sea for breeding.
Aquifer: A geologic stratum containing groundwater that can be withdrawn and used for human purposes.
Baffle: A device to deflect, check or regulate flow.
Berm: Constructed barrier of compacted earth.
BMP: Best Management Practice. See Structural and Nonstructural BMPs.
CWA: Clean Water Act. The federal environmental law that includes the management of stormwater. (See EPA resources and the text of the law).
Direct discharge: Undetained discharge from a proposed project to a major receiving water.
Discharge: Runoff, excluding offsite flows, leaving the development through overland flow, built conveyance systems, or infiltration facilities.
Drainage: The collection, conveyance, containment, and/or discharge of surface and storm water runoff.
Drainage area or Drainage basin: An area draining to a point of interest.
EIS: Environmental Impact Statement. A document that discusses the likely significant adverse impacts of a proposal, ways to lessen the impacts, and alternatives to the proposal. It is required by the national and state environmental policy acts when projects are determined to have the potential for significant environmental impact.
Effluent: The water exiting an oil water separator.
Emulsion or Emulsified: A stable suspension of droplets of one liquid within another, in this case, oil droplets within the water. This can be caused by either mechanical action such as the use of a centrifugal pump, or chemicals such as soaps and detergents. Either of these types is difficult to separate in an oil water separator and special designs may be required.
EPA: United States Environmental Protection Agency
EPA 1664: This is the analytical method usually employed in determining hydrocarbon content in water.
Eutrophic: A condition of a water body in which excess nutrients, particularly phosphorous and hydrocarbon materials, stimulates the growth of aquatic plant life usually resulting in the depletion of dissolved oxygen. Thus, less dissolved oxygen is available to other aquatic life.
FEMA: Federal Emergency Management Agency.
Fisheries: Canadian Fisheries Act. The requirement for discharge according to the Canadian Fisheries Act (Section 36.1a) is that “no deleterious substance” shall be discharged into any water where fishing is carried on and these waters are further defined in Section 40.5b, as all waters that cannot be proven to be never frequented by fish (paraphrase). This requirement is often interpreted as meaning that oil and grease discharges must be limited to 10 mg/L or less.
Freeboard: The vertical distance between the design water surface elevation and the elevation of the structure or facility which contains the water.
Free oil: Non-soluble, non-emulsified hydrocarbons
Groundwater: Underground water usually found in aquifers. Groundwater usually originates from infiltration. Wells tap the groundwater for water supply uses.
Habitat: The specific area or environment in which a particular type of plant or animal lives and grows.
Harmful pollutant: A substance that has adverse effects on an organism including death, chronic poisoning, impaired reproduction, cancer, or other effects.
Hydrocarbon: Crude oil or a refined petroleum product. These include gasoline, diesel fuel, aviation fuel, kerosene, NAFTA, lubricating oil (new and used), hydraulic fluid, and other products derived from petroleum
Illicit discharges: Discharges of non-stormwater to the storm drainage system. Examples are discharges from internal floor drains, appliances, industrial processes, sinks, and toilets that are connected to the nearby storm drainage system. These discharges should be going to the sanitary sewer system, a holding tank, an on-site process water treatment system, or a septic system.
Impervious surface: A hard surface area which either prevents or retards the entry of water into the soil mantle as under natural conditions prior to development; and/or a hard surface area which causes water to run off the surface in greater quantities or at an increased rate of flow from the flow present under natural conditions prior to development.
Common impervious surfaces include but are not limited to, rooftops, walkways, patios, driveways, parking lots or storage areas, concrete or asphalt paving, gravel roads, packed earthen materials, and oiled macadam, or other surfaces which similarly impede the natural infiltration of surface and storm water runoff. Open, uncovered flow control or water quality treatment facilities shall not be considered impervious surfaces for determinations of thresholds.
Infiltration/Inflow (I/I): Clean storm and/or groundwater that enters the sewer system through cracked pipes, leaky manholes, or improperly connected storm drains, downspouts and sump pumps. Most inflow comes from stormwater and most infiltration comes from groundwater. I/I affects the size of conveyance and treatment systems and, ultimately, the rate businesses and residents pay to operate and maintain them.
Influent: The water/hydrocarbon mixture entering the oil water separator.
Lake: An area permanently inundated by water in excess of two meters (7 ft) deep and greater than twenty acres in size as measured at the ordinary high water mark.
MEP: Maximum extent practicable
Nonpoint source (NPS) pollution: NPS pollution occurs when rainfall, snowmelt, or irrigation runs over land or through the ground, picks up pollutants, and deposits them into rivers, lakes, and coastal waters or introduces them into ground water. (See USEPA Factsheet)
Nonstructural BMP: A preventative action to protect receiving water quality that does not require construction. Nonstructural BMPs rely predominantly on behavioral changes in order to be effective. Major categories of non-structural BMPs include education, recycling, maintenance practices and source controls.
NPDES: National Pollutant Discharge Elimination System. The part of the Clean Water Act which requires point source discharges to obtain permits. These permits, referred to as NPDES permits, are administered by the Washington State Department of Ecology.
Oil water separator: A system, often located underground but not necessarily so, designed to efficiently separate oil from water. These are usually designed to meet the requirements of the Clean Water Act or Fisheries Act and provided with high-efficiency internals to ensure compliance. May be used for either stormwater processing or industrial water treatment.
Outfall: A point where collected and concentrated surface and storm water runoff is discharged from a pipe system or culvert.
Phase 1 Stormwater Permit Program: The Phase I program addressed sources of storm water runoff that had the greatest potential to negatively impact water quality. Under Phase I, EPA required NPDES permit coverage for storm water discharges from “medium” and “large” municipal separate storm sewer systems (MS4s) located in incorporated places or counties with populations of 100,000 or more; and eleven categories of industrial activity, one of which is construction activity that disturbs five or more acres of land. (See USEPA Information).
Phase 2 Stormwater Permit Program: The Phase II Program requires NPDES permit coverage for storm water discharges from certain regulated small municipal separate storm sewer systems (MS4s), and construction activity disturbing between 1 and 5 acres of land. (See USEPA Phase 2 Information).
Point discharge: The release of collected and/or concentrated surface and storm water runoff from a pipe, culvert, or channel.
Point source pollutant: Storm water discharges are generated by runoff from land and impervious areas such as paved streets, parking lots, and building rooftops during rainfall and snow events that often contain pollutants in quantities that could adversely affect water quality. Most storm water discharges are considered point sources and require coverage by an NPDES permit. The primary method to control storm water discharges is through the use of best management practices.
Pollution-generating impervious surface: An impervious surface considered to be a significant source of pollutants in surface and storm water runoff. Such surfaces include those subject to vehicular use or storage of erodible or leachable materials, wastes, or chemicals, and which receive direct rainfall or the run-on or blow-in of rainfall. Thus, a covered parking area would be included if runoff from uphill could regularly run through it or if rainfall could regularly blow in and wet the pavement surface.
Pollution-generating pervious surface: A non-impervious surface with vegetative ground cover subject to use of pesticides and fertilizers. Such surfaces include, but are not limited to, the lawn and landscaped areas of residential or commercial sites, golf courses, parks, and sports fields.
POTW: Publicly owned treatment works (sanitary sewer facility)
Receiving waters: Bodies of water or surface water systems receiving water from upstream man-made or natural systems.
Recharge: The flow to groundwater from the infiltration of surface and stormwater runoff.
Retention: The process of collecting and holding surface and storm water runoff with no surface outflow.
Riparian: Pertaining to the banks of rivers and streams, and sometimes also wetlands, lakes, or tidewater.
Riprap: A facing layer or protective mound of stones placed to prevent erosion or sloughing of a structure or embankment due to the flow of surface and storm water runoff.
Runoff: Water originating from rainfall and other precipitation that ultimately flows into drainage facilities, rivers, streams, springs, seeps, ponds, lakes, and wetlands as well as shallow groundwater.
Salmonid: A member of the fish family Salmonidae (Salmon). Salmonid species include Chinook, Coho, chum, sockeye, and pink salmon; cutthroat, rainbow, and brown trout and steelhead; Dolly Varden, brook trout, char, kokanee, and whitefish.
SDWA: Safe Drinking Water Act
Septic system: An onsite wastewater collection system
Sewer system: The system of pipes and pump stations that collect and transport wastewater from homes and businesses to a wastewater treatment plant.
Solid: Settleable particulate matter such as sand, grit, or mud.
Spill: When used in reference to a hydrocarbon pollutant, meaning a number of hydrocarbons discharged into the natural environment from or out of a structured vehicle or other container and is abnormal in a quality oriented quantity that exceeds the limits imposed by the authority having jurisdiction. Note: some non-hydrocarbon oils (such as canola oil) when discharged in large quantities may also constitute a spill.
Stormwater: Stormwater is the water that runs off surfaces such as rooftops, paved streets, highways, and parking lots. It can also come from hard grassy surfaces like lawns, playfields, and from graveled roads and parking lots.
Stormwater Facility: Facilities that control the discharge of stormwater and that remove pollutants are the bulk of the structural solutions applied to surface water problems. Stormwater facilities included storage facilities (ponds, vaults, underground tanks, and infiltration systems); water quality facilities (wet ponds, biofiltration swales, constructed wetlands, sand filters, and oil/water separators); and conveyance systems (ditches, pipes, and catch basins).
Once constructed, stormwater facilities require on-going maintenance to ensure they continue to perform as intended. Maintenance of storage facilities typically includes the removal of accumulated sediment, oil and debris.
Stormwater Management: The application of site design principles and construction techniques to prevent sediments and other pollutants from entering surface or ground water; source controls; and treatment of runoff to reduce pollution.
SMP (or SWMP): Stormwater Management Program
Storm drain system: The system of gutters, pipes, streams, or ditches used to carry surface and storm water from surrounding lands to streams, lakes, or ocean.
Structural BMP: Constructed facilities or measures to help protect receiving water quality and control stormwater quantity.
SWMP (or SMP): Stormwater Management Program
Toxic: Poisonous, carcinogenic, or otherwise directly harmful to life.
Water quality treatment facility: A drainage facility designed to reduce pollutants once they are already contained in surface and storm water runoff. Water quality treatment facilities are the structural component of best management practices (BMPs); when used singly or in combination, WQ facilities reduce the potential for contamination of surface and/or ground waters.