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Glossary of Storm Water Terms

    Active Construction Area: An area defined by the contractor where the contractor intends to be actively working in the ensuing 21-day period. This may include areas that have not already been cleared and grubbed as well as areas that have already been cleared and grubbed.|

    Annual Construction Compliance Review Plan (ACCRP): Plan describing compliance evaluation criteria, protocols, and reporting methods for the upcoming year’s construction compliance monitoring program.

    Annual Maintenance Compliance Review Plan (AMCRP): Plan describing compliance evaluation criteria, protocols, and reporting methods for the upcoming year’s maintenance compliance monitoring program.

    Average Daily Traffic (ADT): Average count of vehicles passing a given point or using a specified roadway.

    Aquifer: Water bearing layer of the earth's crust.

    Best Available Technology Economically Achievable (BAT): Best Available Technology (BAT) is a term derived from Section 301(b) of the federal CWA and refers to BMPs to reduce toxic and non-conventional pollutants in discharges from construction sites. Toxic pollutants are those defined in Section 307(a)(l) of the CWA and include heavy metals and man-made organics. Non-conventional pollutants are those not covered by conventional and toxic pollutants, such as ammonia, chloride, toxicity and nitrogen.

    Best Conventional Pollutant Control Technology (BCT): Best Conventional Technology (BCT) is a term derived from Section 301(b) of the federal CWA and refers to BMPs to reduce conventional pollutants in discharges from construction sites. Conventional pollutants include biochemical oxygen demand, total suspended solids, oil and grease, fecal coliforms and pH.

    Best Management Practices (BMPs): Good housekeeping solutions that include the proper handling, storage and disposal of toxic materials to prevent stormwater pollution. BMPs can include source controls (controls that keep pollutants out of runoff) and treatment controls (controls that remove pollutants from runoff).

    Catch Basin: A storm drain inlet having a sump below the outlet to capture settled solids.

    Code of Federal Regulations (CFR): Document that codifies all rules of the executive departments and agencies of the federal government. It is divided into fifty volumes, known as titles. Title 40 of the CFR (referenced as 40 CFR) lists all environmental regulations. 40 CFR is available from bookstores operated by the Government Printing Office and online at:

    Conduit: Any channel or pipe for directing the flow of water.

    Construction Contractor: Party responsible for carrying out the contract per plans and specifications. The Plans, Standard Specifications and Special Provisions contain storm water protection requirements that the contractor must address.

    Construction Site: The area involved in a construction project as a whole.

    Contamination: An impairment of the quality of waters of the state by waste to a degree that creates a hazard to the public health through poisoning or through the spread of disease, including any equivalent effect resulting from the disposal of waste, whether or not waters of the state are affected.

    Conventional Pollutants: Those pollutants defined in the federal regulations at 40 CFR 401.16 (pursuant to Section 304(a)(4) of the CWA). These pollutants include biochemical oxygen demand (BOD), total suspended solids (TSS) (nonfilterable), pH, fecal coliform, and oil and grease.

    Conveyance System: Any channel or pipe for collecting and directing stormwater.

    Co-permittee: A permittee to an NPDES permit that is only responsible for permit conditions relating to the discharges from its area of jurisdiction.

    Culvert: A channel or a large diameter pipe that crosses under a road, sidewalk, etc.

    Detention Basin: Reservoir designed to temporarily store stormwater.

    Detention Device: Facilities designed to collect and temporarily detain the initial volume of storm water runoff for a specified period of time, to permit settlement of particulate pollutants.

    Dewatering Operations: The removal of groundwater resulting from excavation activities.

    Discharge: A release or flow of stormwater or other substance from a conveyance system or storage container.

    Disturbed Soil Area (DSA): Areas of exposed, erodible soil, including stockpiles, that are within the construction limits and that result from construction activities.

    Drainage Area: That portion of the earth’s surface from which precipitation or other runoff flows to a given location. With respect to a highway, this location may be either a culvert, the farthest point of a channel, or an inlet to a roadway drainage system.

    Drainage Report: A report prepared during project design (prior to the start of construction) for reference in showing drainage patterns.

    Drainage Swale: A storm drainage conveyance structure designed to intercept, divert and convey surface runoff, generally sheet flow, to prevent erosion and reduce pollutant loading.

    Dredge: To clean, deepen or widen by removal of sand or mud, especially from the bottom of a body of water.

    Encroachment: Occupancy of project right-of-way by nonproject structures or objects of any kind or character; also, activities of other parties within the operating right-of-way.

    Environmental Protection Agency (EPA): The federal agency with primary responsibility for implementation of federal environmental statutes, including the CWA, Clean Air Act, Safe Drinking Water Act and Resource Conservation and Recovery Act

    Erosion: The wearing away of land surface, primarily by wind or water. Erosion occurs naturally as a result of weather or runoff, but can be intensified by clearing, grading or excavation of the land surface.

    Erosion Control: The stabilization of cut and fill slopes and other areas within a highway right-of-way.

    Estuary: Body of water at the lower end of a river which is connected to the ocean and is semi-enclosed by land. In an estuary, sea water is measurably diluted by freshwater from the land. Evaluation: Refers to the analysis and interpretation of information obtained through monitoring.

    Exempt (from NPDES Permit) Construction Activities: Routine maintenance to maintain original line and grade, hydraulic capacity or original purpose of a facility; emergency construction activities required to protect public health and safety; projects such as rehabilitation of highway planting and irrigation.

    Existing Vegetation: Any vegetated area that has not already been cleared and grubbed.

    Facility Pollution Prevention Plan (FPPP): A plan that identifies the functional activities specific to the maintenance facility and the applicable BMPs and other procedures utilized by maintenance personnel to reduce the discharge of pollutants in storm water.

    Fair Weather Prediction: When there is no anticipated precipitation in the forecast for the 24 hours immediately after the close-of-business of a working day (72 hours on Fridays). The forecast should be that of the National Weather Service (NOAA weather radio) or some other agreed upon source of forecasting information.

    Fertilizer: A substance, such as manure or chemical mixtures, that is used to make soil more fertile.

    Fire Protection Strips: Buffer strips adjacent to the right-of-way where vegetation is controlled to reduce the risk of fire.

    First Flush: The first big rain after an extended dry period (usually summer) which flushes out the accumulated pollutants in the storm drain system and carries them straight to local waterways.

    Flood Control Channel: Open waterway that is designed to carry large amounts of rain water. These structures are often lined with concrete to help control flood waters.

    Good Housekeeping: A common practice related to the storage, use or cleanup of materials performed in a manner that minimizes the discharge of pollutants.

    Grading: The cutting and/or filling of the land surface to a desired shape or elevation.

    Groundwater: The term usually refers to the saturated zone in the ground where all the pore space between the soil particles is occupied by water.

    Grubbed: Vegetation has been removed by mechanical or manual methods.

    Gutter: Area formed by the curb and the street Helps prevent flooding by channeling runoff to storm drains.

    Hazardous Substance: Any material that poses a threat to human health and/or the environment. Typical hazardous substances are toxic, corrosive, ignitable, explosive or chemically reactive.

    Hazardous Waste: A waste or combination of wastes that, because of its quantity, concentration, or physical, chemical or infectious characteristics, may either cause or significantly contribute to an increase in mortality or an increase in serious irreversible illness; or pose a substantial present or potential hazard to human health or the environment when improperly treated, stored, transported, disposed of or otherwise managed. Possesses at least one of four characteristics (ignitability, corrosivity, reactivity or toxicity) or appears on special EPA or state lists.

    Herbicides: Chemical compounds that are used to control weeds.

    Household Hazardous Waste: Common, every-day products that people use in and around their homes (including paint, paint thinner, herbicides and pesticides) that, due to their chemical nature, can be hazardous if not properly disposed.

    Hydraulics: The study and technological application of the behavior of fluids.

    Illicit Connection: Any connection to a storm drain system for which there is no permit or that is used for an illegal discharge. This includes, but is not limited to: (1) any connections that convey sewage, process wastewater and wash water to the storm drain system, (2) all connections from indoor drains or sinks, and (3) all unapproved, undocumented drains from loading docks and hazardous materials handling areas directly connected to the storm drain system.

    Illegal Discharge: Any non-permitted discharge to a receiving water.

    Impervious Surface: Paved surface or other land cover that does not allow water to percolate into the ground.

    Industrial General Permit: An NPDES permit issued by the State Water Resource Control Board for the discharge of stormwater associated with industrial activity.

    Infiltration Device: An infiltration basin designed to capture runoff volume from the water quality design storm and infiltrate it to the soil.

    Irrigated: Artificially supplied with water through ditches or pipes.

    Maintenance Activities: Routine maintenance activities that may require clearing, grading or excavation to maintain original line and grade, hydraulic capacity or original purpose of the facility.

    Maintenance Facilities: Facilities under the Department’s ownership or control that contain such areas as fueling areas, waste storage or disposal facilities, wash racks, equipment or vehicle storage and materials storage areas.

    Mass Loading: The quantity of a constituent found in runoff expressed in mass per unit of time. Mass loadings are commonly expressed in units of tons/year or pounds/year.

    Median Area: The portion of a divided highway separating the traveled ways for traffic in opposite directions. Often contains storm drain system facilities, such as ditches and swales.

    Metals: Elements such as mercury, lead, zinc, nickel and cadmium that are of environmental concern because they can accumulate in the food chain and, in high enough concentrations, can be hazardous to the environment and the public's health.

    Monitoring: Refers to a variety of activities and processes through which the Department will obtain information relevant to its implementation of the storm water quality management program so that the need for and/or opportunities for revising or refining its program can be identified.

    Municipal Separate Storm Sewer System (MS4): Storm drain systems regulated by the federal Phase I and Phase II storm water regulations. Municipal combined sewer systems are regulated separately. MS4s are defined in the federal regulations at 40 CFR 122.26(b)(8). The preamble to the Phase I regulations discusses submitting MS4 storm water permit applications to DOTs in some circumstances.

    Navigable Waters: The waters of the United States that are currently used, were used in the past, or may be susceptible to use in interstate or foreign commerce, including all waters that are subject to the ebb and flow of the tide; interstate waters; and intrastate lakes, rivers, streams, mudflats, sandflats and wetlands.

    Non-active Construction Area: An area defined as part of the construction site but not identified by the contractor as being active during the rainy season.

    Nonpoint Source Discharge: Discharge from a diffuse pollution source (i.e., without a single point of origin or not introduced into a receiving stream from a specific outlet).

    Non-Stormwater Control Measure: Low technology, low cost activities, procedures or management practices designed to prevent pollutants associated with site functions and activities from being discharged with stormwater runoff. Examples include good housekeeping practices, employee training, standard operating practices, inventory control measures, etc.

    Non-Storm Water Discharge: Any discharge to a storm drain system or receiving water that is not composed entirely of storm water.

    Notice of Intent (NOI): A formal notice to State Water Resources Control Board submitted by the owner/developer that a construction project is about to begin. The NOI provides information on the owner, location, type of project, and certifies that the permittee will comply with the conditions of the construction general permit.

    Nutrients: Any substance assimilated by living things that promotes growth. The term is generally applied to nitrogen and phosphorus in wastewater, but is also applied to other essential and trace elements.

    Oil Waste: Oil of any kind or in any form, including, but not limited to, petroleum, fuel oil, sludge, oil refuse and oil mixed with wastes other than dredged soil.

    Outfall: The point source where a municipal storm sewer discharges to waters of the United States.

    Peak Flow: The highest amount of stream or river flow occurring in a year or from a single storm event.

    Percolation: Process where surface waters are absorbed through the soil into ground water.

    Permanent BMPs: BMPs that are installed during construction and designed to provide long-term storm water quality protection following a project's completion.

    Permanent Soil Stabilization: Soil stabilization controls that provide storm water quality management after construction is completed.

    Person Year (PY): The equivalent of a full-time person working year round; a method of measuring labor.

    Pesticide: Any material used to control pests. Includes insecticides, herbicides, and rodenticides.

    Plans, Specifications and Estimates (PS&E): The bid documents, including general design, specifications, and estimated costs. These also include Water Pollution Control Special Provisions.

    Point Source: Any discernible, confined and discrete conveyance or collection system by which pollutants are or may be discharged.

    Point Source Pollution: Pollution from a single identifiable source such as a smoke stack or a sewage treatment plant.

    Pollutant: Generally are substances introduced into the environment that adversely affect the usefulness of a resource.

    Pollution: A human or naturally caused change in physical, chemical, or biological conditions that result in an undesirable effect on the environment.

    Project Delivery: The Department’s program that is responsible for the planning, design and construction of projects; includes associated functional units.

    Project Engineer (P.E.): The P.E. responsible for the preparation of Project Study Reports and Project Reports during the project planning phase. The P.E. is also responsible for PS&E documents during the design phase.

    Pump Station: A complete pumping installation, including a storage box, pump or pumps, standby pumps, connecting pipes, electrical equipment, pumphouse and outlet chamber.

    Receiving Water Limitations: Permit water quality limitations applied to dischargers to prevent violations of water quality standards.

    Receiving Waters: A river, lake, ocean, stream or other watercourse into which wastewater or treated effluent is discharged as provided in the .Terms of Environment. (U.S. EPA Office of Communications, Education, and Public Affairs; December 1997).

    Resident Engineer (RE): The RE administers the construction contract. The RE makes decisions regarding acceptability of material furnished and work performed, and exercises contractual authority to direct the contractor. The RE may impose sanctions if the contractor fails to take appropriate actions specified in the contract to correct deficiencies.

    Retention: The storage of stormwater to prevent it from leaving the development site; may be temporary or permanent.

    Risk Assessment: The qualitative and quantitative evaluation of the risk posed to human health and/or the environment by the actual or potential presence and/or use of specific pollutants.

    Runoff: Water originating from rainfall and other precipitation (such as sprinklers) that is found in drainage facilities, rivers, streams, springs, seeps, ponds, lakes, wetlands and shallow groundwater.

    Sanitary Sewer: Underground pipes that carry off only domestic or industrial waste, not storm water.

    Secondary Containment: Structures, usually dikes or berms, surrounding tanks or other storage containers and designed to catch spilled material from the storage containers.

    Sediment: Organic or inorganic material that is carried by or is suspended in water and that settles out to form deposits in the storm drain system or receiving waters.

    Sedimentation: The process of depositing soil particles, clays, sands, or other sediments that were picked up by runoff.

    Sediment Load: Sediment particles maintained in the water column by turbulence and carried with the flow of water.

    Site: The land or water area where any facility or activity is physically located or conducted, including adjacent land used in connection with the facility or activity.

    Slope: Any area with a grade of 1:20 (V:H) or more.

    Slough: An inlet on a river.

    Soil Stabilization: Erosion control measures used to minimize erosion.

    Source Control: Action to prevent pollution at its origin.

    Specific Conductance: Rapid method of estimating the dissolved solid content of a water supply by testing its capacity to carry an electrical current.

    Spill: An accidental dumping or spilling of a potential pollutant onto the ground or into a waterway.

    State Transportation Improvement Plan (STIP): A capital improvement program of transportation projects funded with revenues from the State Highway Account and other sources.

    Storm Drain Inlet: A drainage structure that collects surface runoff and conveys it to an underground storm drain system.

    Storm Drain System: A vast network of underground pipes and open channels designed for flood control, which discharges directly into local waterways.

    Storm Water: Storm water means storm water runoff, snow melt runoff, and surface runoff and drainage.

    Storm Water Advisory Team (SWAT): The Department.s teams with responsibility for evaluating new or modified storm water BMPs (Maintenance SWAT, Project Delivery SWAT, and Water Quality SWAT).

    Storm Water Drainage System: Streets, gutters, inlets, conduits, natural or artificial drains, channels and watercourses, or other facilities that are owned, operated, maintained and used for the purpose of collecting, storing, transporting or disposing of storm water.

    Stormwater pollution: Water from rain, irrigation, garden hoses or other activities that picks up pollutants (cigarette butts, trash, automotive fluids, used oil, paint, fertilizers and pesticides, lawn and garden clippings and pet waste) from streets, parking lots, driveways and yards and carries them through the storm drain system and straight to the ocean.

    Stream: Small natural waterway originating from underground springs, snow melt, runoff, or other natural sources which drains to lakes, rivers, channels or oceans.

    Sump: In drainage, any low area that does not permit the escape of water by gravity flow.

    Surface Runoff: Precipitation, snow-melt or irrigation water in excess of what can infiltrate the soil surface and be stored in small surface depressions.

    Temporary Construction Site BMPs: BMPs only temporarily required to address a short-term storm water contamination threat.

    Temporary Soil Stabilization: Soil stabilization controls that provide storm water quality management during construction.

    Total Maximum Daily Load (TMDL): A calculation of the maximum amount of a pollutant that a water body can receive and still meet water quality standards. It is the sum of the allowable loads of a single pollutant from all contributing point and non-point sources.

    Toxic Pollutants: Those pollutants defined in the federal regulations at 40 CFR 401.15 (pursuant to Section 307(a)(1) of the CWA). These pollutants include copper, lead, zinc many chlorinated organic compounds, including pesticides and other constituents sometimes found in wastewater.

    Treatment Control: Treatment methods to remove pollutants from stormwater.

    Vegetation Control: Maintenance of vegetation on facilities owned by the Department by a combination of chemical application (herbicides) and mechanical methods (mowing, cutting, etc.).

    Vista Point: A paved area beyond the shoulder that permits travelers to safely exit the highway to stop and view a scenic area. In addition to parking areas, trash receptacles, interpretive displays, restrooms, drinking water and telephones may also be provided.

    Waste Load Allocation (WLA): The maximum load of pollutants each discharger of waste is allowed to release into a particular waterway. Discharge limits are usually required for each specific water quality criterion being, or expected to be, violated. Also, the portion of a stream’s total assimilation capacity assigned to an individual discharge.

    Water Quality Program: The Department’s Headquarters group that assists the Headquarters functional Programs, the Districts and the Department’s transportation partners in complying with federal and state laws regarding water pollution.

    Water Quality Standards: State-adopted and EPA-approved ambient standards for water bodies. The standards prescribe the use of the water body and establish the water quality criteria that must be met to protect designated uses.

    Watershed: The drainage basin contributing water, organic matter, dissolved nutrients and sediments to a stream, estuary or lake.

    Waters of the State: Any water, surface or underground, including saline waters, within the boundaries of the state.

    Water Pollution Control Program (WPCP): A plan to identify water quality management practices to be implemented that must be prepared for all construction projects that do not require preparation of an SWPPP.

    Water Quality Volume: The water quality volume is the volume of runoff produced by the equivalent of, at a minimum, the 1-year, 24-hour storm event.

    Wetland: Those areas that are inundated or saturated by surface or groundwater at a frequency or duration sufficient to support vegetation typically adapted for life in saturated soil conditions. Generally includes playa lakes, swamps, marshes, bogs, mudflats, natural ponds and similar areas.

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