CSO Control Program --
Glossary of Terms The following is a list of definitions of terms about combined sewers and more generally about wastewater treatment. a-c | d-g | h-l | m-p | r-s | t-z Main sewer
This is a larger pipe in which smaller branch and submain sewers are connected. It may also be called a trunk sewer. MG
Million gallons, a measure of liquid volume. mgd
Million gallons per day, a rate of liquid flow. Model
A formal set of relationships that attempt to represent some processes of the real world. Some models are intended to explain causes and effects of processes, others are tools to estimate or project the results of those processes, even if the processes themselves are not fully understood. Monitor
To systematically and repeatedly measure conditions in order to track changes. For example, dissolved oxygen in a bay might be monitored over a period of several years in order to identify trends in concentration. National Pollutant Discharge Elimination System (NPDES)
Section 402 of the U.S. Clean Water Act, which prohibits discharge of pollutants into navigable waters of the United States unless a special permit is issued by EPA, a state, or (where delegated) a tribal government on an Indian reservation. Nonpoint source pollution
Pollution that enters water from dispersed and uncontrolled sources (such as surface runoff) rather than through pipes. Nonpoint sources (for example, stormwater runoff from agricultural or forest operations, on-site sewage disposal systems, and discharge from boats) may contribute pathogens, suspended solids, and toxicants. The cumulative effects of nonpoint source pollution can be significant. NPDES Permit
Permit issued under the National Pollution Discharge Elimination System, which establishes reporting requirements and other conditions for discharge of pollutants to receiving waters. Outfall
The exit point, usually a pipe or pipes where flow is discharged from the wastewater system into receiving water and which is engineered to ensure dispersion and dilution of the effluent in the receiving waters. Pathogens
Microorganisms that can cause disease in other organisms or humans, animals, and plants. Pathogens include bacteria, viruses, fungi, or parasites found in sewage, in runoff from farms or city streets, and in water used for swimming. Pathogens can be present in municipal, industrial, and nonpoint source discharges. Peak flow
The maximum flow expected to enter a facility. Predesign
The initial phase of a project's design process. The results of this initial phase are generally limited to determination of the alignment, layout and technology for the project. Primary treatment
The first stage of wastewater treatment involving removal of floating debris and solids by screening and/or settling.  Pump station
A pump station is used when sewer trunk lines have conveyed flows to a low-lying area. The pump station lifts the wastewater up to a point where it can flow by gravity to a wastewater treatment plant or another pump station.
a-c | d-g | h-l | m-p | r-s | t-z |
