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Performance Measures Glossary

Combined Sewer Overflow (CSO)
Any intermittent overflow or other untreated discharge from a municipal combined sewer system (including domestic, industrial and commercial wastewater and stormwater) prior to reaching the headworks of the sewage treatment facility which results from a flow in excess of the dry weather carrying capacity of the system.
Community Water Systems (CWS)
A public water system that provides water to the same population year-round. Examples are municipal systems, authorities, and mobile home parks or residential developments with their own water supplies.
Compliance Evaluation Inspection (CEI)
This is a comprehensive inspection to review all aspects of an NPDES discharger's facility. A CEI can stand alone as an inspection but it is also an element of any Compliance Sampling Inspection and may be part of a Performance Audit Inspection.
Compliance Sampling Inspection (CSI)
This is similar to a CEI except that, in addition, sampling is conducted at all outfalls in accordance with NPDES permit requirements.
Designated Use
State water quality standards assign designated beneficial uses to waters and DEP measures a variety of physical, chemical, and biological water quality and habitat indicators to determine if water uses are attained. The water quality indicators used by Pennsylvania for making use attainment decisions are interpreted within the context of the Commonwealth’s Water Quality Standards.
Discharge Monitoring Report (DMR)
The form referred to as the NPDES reporting form under Chapter 92 that is used for reporting wastewater monitoring results, as approved by EPA for use in Pennsylvania, including any supplemental forms provided by DEP. The term also means the DEP- or EPA-supplied form(s) for the reporting of self-monitoring results by the permittee. An electronic version of the DMR (eDMR) is also available for reporting results in lieu of paper forms.
The incorporation of any life stages of fish and shellfish with intake water flow entering and passing through a cooling water intake structure and into a cooling water system.
Groundwater Under the Direct Influence of Surface Water (GUDI)
Any water beneath the surface of the ground with the presence of insects or other macroorganisms, algae, organic debris or large diameter pathogens such as Giardia lamblia and Cryptosporidium, or significant and relatively rapid shifts in water characteristics such as turbidity, temperature, conductivity or pH which closely correlate to climatological or surface water conditions. The term does not include finished water.
The entrapment of any life stages of fish and shellfish on the outer part of an intake structure or against a screening device during periods of intake water withdrawal.
Industrial Waste
A liquid, gaseous, radioactive, solid or other substance, not sewage, resulting from manufacturing or industry, or from an establishment, and mine drainage, refuse, silt, coal mine solids, rock, debris, dirt and clay from coal mines, coal collieries, breakers or other coal processing operations. The term includes all of these substances whether or not generally characterized as waste.
Non-carbon-based compounds such as metals, nitrates, and asbestos. These contaminants are naturally-occurring in some water, but can get into water through farming, chemical manufacturing, and other human activities.
Lead and Copper Rule (LCR)
This rule established national limits on lead and copper in drinking water. Lead and copper corrosion pose various health risks when ingested at any level, and can enter drinking water from household pipes and plumbing fixtures.
Major Facilities
For the NPDES program, any sewage facility with a design flow of one million gallons per day (MGD) or greater, a service population of 10,000 or greater, or has a significant impact on water quality, and any industrial waste facility that receives a rating of at least 80 points per an EPA NPDES rating procedure. Other facilities not meeting the above criteria can be designated as a discretionary major facility with proper justification.
Maximum Contaminant Level (MCL)
The highest amount of a contaminant that EPA allows in drinking water. MCLs ensure that drinking water does not pose either a short-term or long-term health risk. MCLs are defined in milligrams per liter (parts per million) unless otherwise specified.
Maximum Residual Disinfectant Level (MRDL)
The maximum permissible level of a disinfectant added for water treatment that may not be exceeded at the consumer’s tap without an unacceptable possibility of adverse health effects. MRDLs are defined in milligrams per liter (parts per million) unless otherwise specified.
Minor Facilities
For the NPDES program, sewage facilities with a design flow of less than one million gallons per day (MGD) and a service population of less than 10,000; industrial waste facilities with a rating less than 80 points per an EPA NPDES rating procedure; and otherwise not determined to be discretionary major facilities.
National Pollutant Discharge Elimination System (NPDES)
The national program for issuing, modifying, revoking and reissuing, terminating, monitoring and enforcing permits, and imposing and enforcing pretreatment requirements, under sections 307, 402, 318, and 405 of the Clean Water Act.
Non-Municipal Sewage Treatment Plant
A system or facility used for the treatment of sewage generally collected at privately-owned establishments. Examples include sewage treatment facilities located at mobile home parks, business parks, and campgrounds.
Nontransient Noncommunity Water System (NTNC)
A PWS that is not a CWS, but that regularly serves at least 25 of the same people at least six months of the year. Examples include schools, factories, and hospitals that have their own water supplies.
Organic Contaminants
Carbon-based compounds, such as industrial solvents and pesticides. These contaminants generally get into water through runoff from cropland or discharge from factories.
Publicly Owned Treatment Works (POTWs)
A device or system used in the treatment (including recycling and reclamation) of municipal sewage or industrial wastes of a liquid nature which is owned by a state or municipality. The term includes sewers, pipes or other conveyances only if they convey wastewater to a POTW providing treatment.
Public Water Systems (PWS)
A system that provides piped water for human consumption to at least 15 service connections or serves an average of at least 25 people for at least 60 days each year. PWSs can be community, nontransient noncommunity, or transient noncommunity systems.
Radionuclides (RADS)
Radioactive particles, including radium-226, radium-228, gross alpha, and beta particle/photon radioactivity, that can occur naturally in water or result from human activity.
Reconnaissance Inspection
This is a visit to a facility primarily to evaluate compliance status. The degree of detail and formality will depend on the conditions observed during the inspection.
Sanitary Sewer Overflow (SSO)
An intermittent overflow of wastewater, or other untreated discharge from a separate sanitary sewer system (which is not a combined sewer system), which results from a flow in excess of the carrying capacity of the system or from some other cause prior to reaching the headworks of the sewage treatment facility.
Significant Chesapeake Bay Dischargers
For facilities discharging to waters that flow to the Chesapeake Bay, a sewage facility with a design flow of 0.4 MGD or greater or an industrial waste facility that discharges at least 75 pounds per day of Total Nitrogen or 25 pounds per day of Total Phosphorus (computed as an average daily load over the entire year).
Significant Noncompliance (SNC)
Indicator status for significant violations that have occurred or are occurring at Major facilities, pursuant to EPA regulations at 40 CFR 123.45. Examples of SNC violations include major exceedances of effluent limits, failure to meet compliance schedule milestones by at least 90 days of the date specified in an enforcement document or permit, and failure to submit major reports, such as DMRs, within 30 days of the due date.
Single Residence Sewage Treatment Plant (SRSTP)
A system of piping, tanks or other facilities serving a single family residence located on a single family residential lot, which collects, disposes and treats solely direct or indirect sewage discharges from the residence into surface waters of the Commonwealth.
Stage 1 Disinfectants and Disinfection Byproducts Rule (DDBP)
Beginning in January 2004, the Stage 1 Disinfectants and Disinfection Byproducts Rule applies to community water systems and non-transient non-community systems that add a disinfectant or oxidant to the drinking water during any part of the treatment process.
Surface Water Treatment Rule
The Surface Water Treatment Rule establishes criteria under which water systems supplied by surface water sources, or groundwater sources under the direct influence of surface water, must filter and disinfect their water.
Total Chemicals
The total value for organic, inorganic and radionuclide contaminants.
Total Coliform Rule (TCR)
The Total Coliform Rule establishes regulations for microbial contaminants in drinking water. These contaminants can cause short-term health problems.
Transient Noncommunity Water System (TNC)
A system that caters to transitory customers in non-residential areas such as campgrounds, motels, and restaurants having their own water supplies.
Treatment Technique (TT)
A water treatment process for contaminants that laboratories cannot adequately measure. Treatment techniques are used instead of MCLs