ABSORPTION: The process by which one substance is taken into and included within another substance, as the absorption of water by soil or nutrients by plants.
ADSORPTION: The increased concentration of molecules or ions at a surface, including exchangeable cations and anions on soil particles.
AESTHETICS: All surface waters shall be free from pollutants in concentrations or combinations that settle to form objectionable deposits; float as debris, scum or other matter to form nuisances; produce objectionable odor, color, taste or turbidity; or produce undesirable or nuisance species of aquatic life.
ALTER: Under the Massachusetts Wetlands Protection Regulations, 310 CMR 10.04, to change the condition of any wetland resource area subject to protection under the Massachusetts Wetlands Protection Act (MGL c.131, s.40). Examples of alterations include, but are not limited to: a) changing drainage characteristics, flushing characteristics, salinity distribution, sedimentation patterns, flow patterns, and flood retention areas; b) lowering the water level or water table; c) destruction of vegetation; d) changing the water temperature, biochemical oxygen demand (BOD), and other physical, biological, or chemical characteristics of the receiving water.
ANTIDEGRADATION PROVISION: Portion of Massachusetts Water Quality Standards stating that in all cases, the existing uses and level of water quality must be maintained and protected. Antidegradation is implemented in three tiers. Tier I protects all existing uses. Tier II and Tier III are special cases of Tier I where waters are better than prescribed standards. Tier II sets the rules for justified lowering of high quality waters (the floor being the minimum specified by the class). Tier III protects Outstanding Resource Waters from any lowering of water quality.
ANTI-SEEP COLLAR: A plate that is attached to the barrel running through an embankment of a pond that prevents water seepage around the pipe.
AQUIFER: Geologic formation that is saturated and sufficiently permeable to transmit large quantities of water.
| BANK (INLAND): Under the Massachusetts Wetlands Protection Regulations, 310 CMR 10.54(2), the portion of the land surface which normally abuts and confines a water body. It occurs between a water body and a bordering vegetated wetland and adjacent flood plain, or, in the absence of these, it occurs between a water body and an upland. The upper boundary of a bank is the first observable break in the slope or the mean annual flood level, whichever is lower. The lower boundary of a bank is the mean annual low flow level.
BARREL: A concrete or corrugated metal pipe that passes runoff from the riser, through the embankment, and to the pond outfall.
BASE FLOW: The portion of stream flow that is supported by groundwater seepage into a channel, rather than by stormwater runoff.
BASIN: See WATERSHED.
BEST MANAGEMENT PRACTICES (BMPs): For purposes of stormwater management, structural, nonstructural, and managerial techniques that are recognized to be the most effective and practical means to prevent or reduce nonpoint source pollutants from entering receiving waters.
BIOACCUMULATION: Accumulation of metals or other toxics in living organisms.
BIOFILTRATION: The use of a series of vegetated swales to provide filtering treatment for stormwater as it is conveyed through the channel. The swales can be grassed, or contain emergent wetlands or high marsh plants.
BIORETENTION: landscaping features where surface runoff is directed into shallow, landscaped depressions designed to remove pollutants.
BORDERING VEGETATED WETLAND: Under the Massachusetts Wetlands Protection Regulations, 310 CMR 10.55(2), a freshwater wetland which borders on creeks, rivers, streams, ponds, and lakes, such as wet meadows, marshes, swamps, and bogs.
BUFFER STRIPS: Areas of grass or other close growing vegetation that separates a waterway (ditch, stream, brook) from an intensive land use area (subdivision, farm); also referred to as filter strips, vegetated filter strips, and grassed buffers. Buffer strips can either be natural or man-made.
BYPASS VOLUME: Volume (cubic feet) at which stormwater flow bypasses the treatment components of the system. Once this volume is in the system, additional flows are not treated.
|CATCH BASIN: A conventional structure for the capture of stormwater utilized in streets and parking areas. It typically includes an inlet, sump, and outlet and provides minimal removal of suspended solids. In most cases a hood also is included to separate oil and grease from the stormwater.
CERTIFIED VERNAL POOL: Under the Massachusetts Wetlands Protection Regulations, 310 CMR 10.57(a)(5)-(6), these are pools that have been certified by the Massachusetts Division of Fisheries and Wildlife, and the area 100 feet from the boundary of said pool. If the pool has not been certified, the wetlands regulations contain procedures for determining the probable extent of said habitat. These pools provide crucial habitat to several vertebrate and many invertebrate species of wildlife.
CHANNEL: In hydrology, the bed of a river or stream through which water is moved or directed. Channels may be either natural or man-made (e.g., a concrete lined box channel).
CHECK DAM: An earthen or log structure used in grass swales (perpendicular to the runoff flow) to reduce water velocity, promote sedimentation, and enhance infiltration.
COLLOIDS: The finely divided suspended matter that will not settle.
COMBINED SEWER OVERFLOW: A sewer pipe or system through which both sanitary wastewater and stormwater flows. During low frequency storms, both flows remain separate. During higher frequency precipitation events, the stormwater is mixed with the sanitary flow and may bypass wastewater treatment and be released to a receiving water body without treatment.
CONTRIBUTING WATERSHED AREA: The portion of a watershed contributing runoff to a BMP.
CONVEYANCE: System of pipes, conduits, ditches, and channels.
CZM: The Massachusetts Office of Coastal Zone Management. State agency with the mission to balance the impacts of human activity with the protection of coastal and marine resources.
| DEAD LOAD: Stationary component of load-bearing capacity - soils, concrete, snow, etc.
DEP: Massachusetts Department of Environmental Protection. State agency responsible for protecting human health and the environment by ensuring clean air and water, the safe management and disposal of solid and hazardous wastes, the timely cleanup of hazardous waste sites and spills, and the preservation of wetlands and coastal resources.
DESIGN STORM: A rainfall event of a specific size and return frequency (e.g., 2-year, 24-hour storm) that is used to calculate runoff volume and peak discharge rate to a BMP.
DETENTION POND: A facility that collects water from developed areas and releases it at a slower rate than it enters the collection system. The excess of inflow over outflow is temporarily stored in a pond or a vault and is typically released over a few hours or a few days.
DETENTION TIME: The amount of time that a unit volume of stormwater actually remains in a BMP. Greater detention times will provide increased removal of suspended solids.
DISCHARGE: Water or effluent released to a receiving water body.
DISCHARGE RATE: The volume of water flowing in a stream or conveyance or through an aquifer past a specific point in a given period of time, usually denoted as the letter "Q" in hydrologic equations.
DRAINAGE AREA: Land area from which water flows into a stream or lake (see also watershed).
DRAINAGE CHANNEL: Shallow drainage conveyance designed with sufficient capacity to convey runoff safely, without erosion, during large (10-year frequency) storm events.
DRAIN DOWN VALVE: A valve located at the outlet structure of a detention basin. Normally closed, it is used to drain the detention basin for emergency purposes or routine maintenance.
DRY WELL: A type of BMP comprised of a small, excavated pit, backfilled with aggregate, which is used to infiltrate high quality runoff.
|ENHANCED VEGETATIVE FILTER STRIPS: A natural buffer or Vegetative Filter Strip which has been engineered and maintained to improve pollutant removal capabilities. Also known as an Enhanced Vegetative Buffer Area.
EPA: Federal Agency whose mission is to protect human health and the environment.
ETV: EPA's Environmental Technology Verification (ETV) Program develops testing protocols and verifies the performance of innovative technologies that have the potential to improve protection of human health and the environment.
EVENT: An actual storm or a computer program that models a single storm response.
EXFILTRATION: The downward movement of runoff from the bottom of an infiltration BMP into the soil layer.
EXTENDED DETENTION BASIN: An area surrounded by an embankment, or an excavated pit, designed to temporarily hold stormwater long enough to allow settling of solids and reduce local and downstream flooding.
FILTER FABRIC: Permeable or impermeable textile of a very small mesh or pore size. Permeable filter fabric allows water to pass through while keeping sediment out. Impermeable filter fabric prevents both water and sediment from passing through it.
FIRST FLUSH: Pollutant concentrations, including suspended sediments, carried by stormwater in the beginning of a storm. These concentrations are typically higher than at the middle or end of the storm. For purposes of the Massachusetts Stormwater Management Policy, the first flush is the first half-inch of precipitation, and in Critical Areas, the first inch of precipitation.
FLOATABLES: Materials in stormwater or sanitary flows which float to the surface.
FOREBAY: Additional storage space located near a stormwater practice inlet that serves to trap incoming coarse sediments before they accumulate in the main treatment area.
|GRASS SWALE: A shallow drainage conveyance with relatively gentle side slopes, generally with flow depths less than one foot, planted with grass.
GRATE INLET: Structure used to cover an inlet to a sewer system to keep out debris.
GRASSED FILTER STRIP: Vegetated area intended to treat sheet flow from adjacent impervious areas. Filter strips function by slowing runoff velocities and filtering out sediment and other pollutants, and providing some infiltration into underlying soils.
GROUNDWATER RECHARGE: The return of water to an underground aquifer by either natural or artificial means such as exfiltration of a BMP.
HI MARSH: For purposes of stormwater management, the area in a stormwater wetland located at the surface of the normal pool to six inches in depth.
HYDRAULIC RADIUS: The ratio of the cross-sectional area of a stream and the wetted perimeter.
HYDRAULIC SURFACES: The surfaces of a channel or pipe over or through which water flows. If the surfaces are smooth, as in a concrete pipe or culvert, there is less friction and water will flow faster. If the surfaces are rough, the velocity of the flowing water is slower.
HYDROPERIOD: The extent and duration of inundation and/or saturation of wetland systems.
|IMPERVIOUS AREA: Impermeable surface, such as pavement or roof top, which prevent the infiltration of water into the soil.
INFILTRATION: The entry of water (from precipitation, irrigation, or runoff) into the soil.
INFILTRATION BASIN: An impoundment where incoming stormwater runoff is stored gradually until it exfiltrates through the soil of the basin floor.
INFILTRATION BMP: A type of BMP designed to enhance the movement of stormwater runoff from the surface to the subsoil.
INFILTRATION CHAMBER: A concrete or plastic structure with a porous or open bottom where incoming stormwater runoff is stored until it exfiltrates through the soil of the chamber floor.
INFILTRATION RATE: The quantity of water that can enter the soil in a specified time interval.
INFILTRATION TRENCH: Shallow, excavated trench that is filled with stone to create an underground reservoir for stormwater runoff. The runoff gradually exfiltrates through the bottom of the trench, into the subsoil, and eventually into the water table.
INTERCEPTOR: Conduit at downstream end of a combined sewer that carries sewage to a treatment plant.
INTERIM WELLHEAD PROTECTION AREA (IWPA): For public water systems using wells or wellfields that lack a DEP approved Zone II, DEP will apply an interim wellhead protection area (IWPA). This interim wellhead protection area shall be a one-half mile radius measured from the well or wellfield for sources whose approved pumping rate is 100,000 gallons per day (gpd) or greater. For wells or wellfields that pump less than 100,000 gpd, the IWPA radius is proportional to the approved pumping rate which may be calculated according to the following equation: IWPA radius in feet = (32 x pumping rate in gallons per minute) + 400. A default IWPA radius or an IWPA radius otherwise computed and determined by the DEP shall be applied to transient non-community (TNC) and nontransient non-community (NTNC) wells when there is no metered rate of withdrawal or no approved pumping rate. The default IWPA radius shall be 500 feet for TNC wells and 750 feet for NTNC wells.
INVERT: Bottom of a channel or pipe.
| LEVEL SPREADER: A device used to spread out stormwater runoff uniformly over the ground as sheetflow. Level spreaders are used to prevent concentrated, erosive flows and to enhance infiltration.
LIVE WEIGHT: Transient component of load-bearing capacity - cars, people, etc.
LOAD BEARING CAPACITY: Amount of weight a system can bear.
LOADING: The quantity of a substance entering the environment (soil, water, or air).
MAXIMUM EVENT RECURRENCE INTERVAL: Largest storm event (as measured by recurrence interval - e.g. 1 year storm, 10 year storm) that was used to evaluate BMP in this study.
MICROPOOL: A small permanent pool used in a stormwater pond due to extenuating circumstances, i.e. concern over thermal impacts of larger ponds, impacts on existing wetlands, etc.
MULCH: Any substance spread or allowed to remain on the soil surface to conserve soil moisture and shield soil particles from the erosive forces of raindrops and runoff.
|NATURAL HYDROLOGIC REGIMES: Stream channel, land form, and vegetative conditions that have not been altered by man.
NATIONAL POLLUTANT DISCHARGE ELIMINATION SYSTEM (NPDES): A national program under Section 402 of the Clean Water Act for regulation of discharges of pollutants from point sources to waters of the United States. Discharges are illegal unless authorized by an NPDES permit.
NONPOINT SOURCE (NPS) POLLUTION: Pollution of surface or groundwater supplies originating from land use activities and/or the atmosphere, having no well-defined point of entry.
NON-STRUCTURAL PRACTICE: 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.
OBSERVATION WELL CLEARANCE RATE: The drop in water level per unit time in a test well installed in an infiltration device. Tracking the pattern of measurements over a series of years may indicate potential clogging problems.
OFFLINE SYSTEM: Treatment system that restricts flows to treatment facilities, bypassing higher flows around them. Typically, the first flush is captured and treated in an offline system.
OIL AND GREASE: This includes hydrocarbons, fatty acids, soaps, fats, waxes, and oils. Tests for oil and grease are determined on the basis of their common solubility in freon.
OIL AND GREASE SEPARATOR: Also known as a Water Quality Inlet (WQI).
100-YEAR, 24-HOUR EVENT: Precipitation from a storm that occurs with a predicted statistical frequency of once every 100 years over a 24-hour period. This storm has a 1% chance of happening in any one given year. Because this is a statistical storm, it could occur twice in the same year. The predicted statistical frequency may be based on actual data collected over a 100-year period or on a synthetic record based on partial data or data extrapolated from a nearby area.
100-YEAR FLOODING EVENT: The flood elevation that has a predicted statistical frequency of occurring once every 100 years This flood elevation has a 1% chance of happening in any one given year. Please note there is no correlation between the 100-year flood and the 100-year 24-hour precipitation event.
ONLINE SYSTEM: Treatment system that passes all storm flows through the system. Flows above the design treatment flow or volume pass through the system with lesser or no pollution removal.
OUTFALL: The end of the pipe which discharges stormwater, sanitary flows, or effluent to a receiving water body.
OVERLAND FLOW: Flow of water across the land surface.
|PARTICULATES: Sand, silt, or clay soil particles and organic matter found in stormwater.
PEAK DISCHARGE: The maximum instantaneous rate of flow during a storm, usually in reference to a specific design storm event.
PERCOLATION: The flow or trickling of a liquid downward through soil or filtering medium. The liquid may or may not fill the pores of the medium.
PERVIOUS: Surfaces or soils which are permeable, allowing water to pass or migrate downward.
PILOT CHANNEL: A paved or riprap channel that routes runoff through a BMP to prevent erosion of the surface.
PLUG FLOW: A flow value which is used to describe a constant hydrologic condition.
POCKET WETLAND: A stormwater wetland design for small drainage areas with no reliable base flow source.
POND/WETLAND SYSTEM: A two-cell stormwater wetland design with a wet pond in combination with a shallow marsh.
PONDSCAPING: A technique that uses wetlands vegetation, native trees, shrubs, and herbaceous plants to meet specific functional design objectives in a stormwater wetland system.
POINT SOURCE POLLUTION: Pollution of ground or surface water supplies at well-defined, usually manufactured, "points" or locations; discharges of treated wastewater from municipal and industrial treatment plants are common point sources of pollution.
POLLUTANT REMOVAL MECHANISM: One factor which must be considered in the stormwater runoff management plan at a site. This factor considers the means by which expected contaminants at a site will be eliminated/controlled through the use of appropriate BMP(s).
POROUS PAVEMENT: A manufactured surface that allows water to penetrate through and percolate into the soil (as in porous asphalt pavement or concrete). Porous asphalt pavement is comprised of irregular shaped crushed rock, pre-coated with asphalt binder. Water seeps through into the lower layers of gravel for temporary storage, then filters naturally into the soil.
Q AND q: Q is the flow rate per unit time, e.g. cuft/s or m/s; q is the flow rate per unit width, e.g. m2/s
QUALIFYING EVENT MINIMUM STORM DEPTH: Minimum storm size (in inches) that qualifies as a measurable storm event for this study.
RECEIVING WATERS: Bodies of water that receive runoff or wastewater discharges, such as streams rivers, ponds, lakes, and estuaries.
RECHARGE: Water that infiltrates to an aquifer, usually from above.
RECURRENCE INTERVAL OR RETURN PERIOD: Time interval in which an event will occur on the average.
RETENTION POND: permanent pool of water that allows settling of sediments (including fine sediments) and removal of soluble pollutants.
RETROFIT: The installation of a new BMP or improvement of an existing BMP in an already developed area.
RIPRAP: A combination of boulders, large stones, and cobbles used to line channels, stabilize banks, filter out sediments, or reduce runoff velocities.
RISER: A vertical pipe extending from the bottom of a pond BMP that is used to control the discharge rate from the BMP for a specific design storm.
RUNOFF: Precipitation, snow melt, or irrigation that flows over the land, eventually making its way to a surface water (such as a stream, river, pond).
RUNOFF RATE OR VELOCITY: The speed of runoff from a storm, expressed in units of distance per unit of time.
RUNOFF VOLUME: The volume of runoff as a direct result of a storm, usually expressed in units of cubic feet.
SAND FILTER: Self-contained beds of sand underlain with perforated underdrains. Runoff is filtered through the sand and is collected in the underdrain system and discharged to a receiving water or to another BMP for further treatment.
SCALABILITY: The number of multiple units that can be installed together in a single system.
SCOURING: The clearing and digging action of flowing water, especially the downward erosion caused by stream water in sweeping away mud and silt from the streambed and outside bank of a curved channel.
SEDIMENT: Eroded soil and rock material and plant debris, transported and deposited by runoff.
SEDIMENT TRAP or FOREBAY: Component of a stormwater runoff BMP that uses a small settling basin which allows sediments to settle out prior to flowing to a subsequent BMP. They are often used in tandem with infiltration devices, wet ponds, or marshes. Also known as a sediment trap.
SEDIMENTATION: The deposition of transported soil particles due to a reduction in the rate of flow of water carrying these particles.
SHEETFLOW: Runoff that flows over the ground as a thin, even layer rather than concentrated in a channel.
SIPHON: A closed conduit (pipe) a portion of which lies above the hydraulic grade line, resulting in a pressure less than atmospheric and requiring a vacuum within the conduit to start flow. A siphon utilizes atmospheric pressure to effect or increase the flow of water through the conduit.
SITE DESCRIPTION: Description of the area where the test study took place for validated technologies
SITE PLANNING: In terms of stormwater management, a preliminary component of a development plan, where appropriate BMP structures are well and properly sited.
SORB OR SORBTION: The attraction and adherence of moisture or metals onto soil particles. See ADSORPTION. The binding, or holding, of pollutants.
SLOPE: One factor to be considered as part of the physical site suitability assessment when designing and selecting a BMP. The slope, or incline, at a site limits the type(s) of BMP which may be employed in treating the stormwater runoff.
SOIL SUITABILITY: One factor to be considered under the physical site suitability assessment for selecting an appropriate BMP.
SOLUBLE: Refers to material which can be dissolved in water.
SOURCE CONTROLS OR SOURCE REDUCTION: A practice or structural measure to prevent pollutants from entering stormwater runoff or other environmental media.
STORM DRAIN: An inlet for the capture of stormwater.
STORMWATER: Runoff from a rain storm event, snow melt runoff, and surface runoff and drainage.
STORMWATER DISCHARGE: Stormwater discharge is defined as any stormwater that culminates in a point source which discharges directly to a water of the Commonwealth, or to a separate stormwater sewer which in turn discharges to a water of the Commonwealth.
STORMWATER MANAGEMENT SYSTEM: A conveyance system for the capture, treatment and discharge of stormwater. May include several BMPs linked together.
STORMWATER RUNOFF: For the purpose of this document, any stormwater that flows overland before infiltrating into the ground.
STORMWATER WETLAND: A constructed wetland system designed to maximize pollutant removal through uptake of pollutants by wetlands plants, retention, and settling.
STRUCTURAL PRACTICES: Constructed facilities or measures to help protect receiving water quality and control stormwater quantity. Examples include storage, vegetation, infiltration, and filtration.
SUBBASIN: See WATERSHED
SUBSIDENCE: The process of sinking to a lower level. For example, the elevation of the land surface above an aquifer may sink or subside when groundwater is withdrawn from the underlying aquifer. Subsidence also refer to the process by which sediment in solution settles out.
SUSPENDED SOLIDS: See TOTAL SUSPENDED SOLIDS
TARP: The Technology Acceptance and Reciprocity Partnership was formed by the states of California, Illinois, Maryland, Massachusetts, New Jersey, New York, Pennsylvania, and Virginia to provide a uniform method for demonstrating the effectiveness of stormwater technologies and developing test quality assurance plans for certification or verification of performance claims.
10-YEAR, 24-HOUR EVENT: Precipitation from a storm that has a predicted statistical frequency of occurring once every 10 years over a 24-hour period. This storm has a 10% chance of happening in any one given year.
THERMAL ENHANCEMENT: A raise in temperature of a surface water. This factor must be considered in the physical site suitability assessment when selecting/designing a BMP, particularly when the classification of the receiving stream is a cold water fishery. The Massachusetts Surface Water Quality Standards provide the minimum water quality criteria which must be maintained in order to support the designated use(s) of the state's water bodies.
TIDE GATE: Structure installed at the outlet of a sewer system that discharges into tidal waters to prevent the backflow of the receiving water into the conduits.
TIME OF CONCENTRATION (T c): The time it takes for runoff to travel from the hydraulically most distant point of a watershed until it reaches an outlet or other specified point within the watershed. It is used to estimate peak discharge or to develop a hydrograph. The time includes sheet flow, shallow concentrated flow, and channel flow.
TIME OF TRAVEL (T t): The time it takes surface water to travel from one location to another in a watershed. Sheet flow is not included. Travel time is a component of time of concentration).
TOTAL DISSOLVED SOLIDS (TDS): The weight of solids per unit volume of water which are in true solution; usually determined by the evaporation of a measured volume of filtered water and determination of the residue weight. Total Dissolved Solids is a measurement of any minerals or salts in the water. Bicarbonate, Chloride, Sulfate, Calcium, Magnesium, Sodium are the major components of dissolved solids in water. High amounts of these salts provide the major cause of water taste problems. High TDS can cause the water to appear inappropriate to drink, and spotting of glassware, fixtures, or painted surfaces such as automobiles. Also high dissolved solids can diminish the life of home appliances. The EPA has set a maximum contaminant level of 500 ppm.
TOTAL SOLIDS: The sum of the dissolved and suspended solids in a water or wastewater. Usually expressed as milligrams per liter.
TOTAL SUSPENDED SOLIDS (TSS): Matter suspended in water or stormwater; when water is filtered for laboratory analysis, TSS are retained by the filter, dissolved solids pass through.
TURBIDITY: Cloudiness in water due to suspended and colloidal organic and inorganic material.
2-YEAR, 24-HOUR EVENT: Precipitation from a storm that has a predicted statistical frequency of occurring once every 2 years, over a 24-hour period. This storm has a 50% chance of happening in any one given year.
|URBAN RUNOFF: Surface runoff from urbanized areas (such as streets, parking lots, retail malls, residential developments, subdivisions. etc.).
VEGETATIVE BUFFER AREAS: Refer to Vegetative Filter Strip (VFS).
VEGETATIVE FILTER STRIP (VFS): A type of BMP which EPA defines as a "permanent, maintained strip of planted or indigenous vegetation located between nonpoint sources of pollution and receiving water bodies for the purpose of removing or mitigating the effects of nonpoint source pollutants such as nutrients, pesticides, sediments, and suspended solids". A VFS, which both decreases velocity and removes pollutants from the stormwater, is designed to receive overland flow from an upland development. Also referred to as a Vegetative Buffer Area.
VEGETATIVE SWALE: A natural depression or wide, shallow vegetated ditch used to temporarily store, route, or filter runoff.
|WASTEWATER: Typically liquid discharged from residential, business or industrial sources that contains a variety of wastes (fecal matter, by-products).
WASTEWATER TREATMENT FACILITY: A physical plant and its processes utilized for the purpose of treating waterborne pollutants from industrial and/or municipal wastewater.
WATER COLUMN: Water in a receiving water body or wetland.
WATER QUALITY BMP: A BMP that is specifically designed for pollutant removal.
WATER QUALITY INLET (WQI): An underground retention system, also known as an oil/grease separator, designed to separate trash, debris, sediments, and oil and grease from stormwater runoff.
WATER QUALITY SWALE: A shallow drainage conveyance designed primarily for the prescribed stormwater water quality volume and to enhancer stormwater pollutant removal effectiveness.
WATERSHED: An area of land that contributes runoff to one specific delivery point; large watersheds may be composed of several smaller "subwatersheds," each of which contributes runoff to different locations that ultimately combine at a common delivery point.
WATER TABLE: The upper level of a saturated zone below the soil surface, often the upper boundary of a water table aquifer. The water table rises and falls according to the season, and the amount of rain and snow melt that occurs.
WETLAND BUFFER ZONE: Area of land extending one hundred (100) feet horizontally outward from the boundary of any resource area defined under the Wetland Protection Act Regulations (310 CMR 10.00) except for land under water bodies, land subject to tidal action, land subject to coastal storm flowage and land subject to flooding.
WETLAND MULCH: A technique for establishing marsh areas by spreading the top 12 inches of wetland soil from a donor wetland over the surface of a constructed stormwater wetland as a mulch.
WETLAND RESOURCE AREA: Protected areas specified in the Wetlands Protection Act. Specifically, these areas are banks, bordering vegetated wetlands, land under water bodies and waterways, land subject to flooding, coastal areas, and riverfront areas specified in the Act.
WET POND: An area surrounded by an embankment, or an excavated pit, designed with a permanent pool of water. Runoff entering the wet pond displaces the water already present in the pool and remains there until displaced by the next storm event. Detention of the runoff in the pool allows for settling of solids and reduces local and downstream flooding.
|ZONE A: Zone "A" means a) the land area between the surface water source and the upper boundary of the bank; (b) the land area within a 400-foot lateral distance from the upper boundary of the bank of a Class A surface water source, as defined in 314 CMR 4.05(3)(a); and (c) the land area within a 200 foot lateral distance from the upper boundary of the bank of a tributary or associated surface water body.
ZONE B: Means the land area within one-half mile of the upper boundary of the bank of a Class A surface water source, as defined in 314 CMR 4.05 (3)(a), or edge of watershed, whichever is less. However, Zone B shall always include the land area within a 400 foot lateral distance from the Class A surface water source.
ZONE I: Means the protected radius required around a public water supply well or wellfield. For public water supply system wells with approved yields of 100,000 gallons per day (gpd) or greater, the protective radius is 400 feet. Tubular wellfields require a 250 foot protective radius. Protective radii for all other public water supply system wells are determined by the following equation: Zone I radius in feet = [150 x log of pumping rate in gpd] - 350. This equation is equivalent to the chart in the DEP Water Supply Guidelines. A default Zone I radius or a Zone I radius otherwise computed and determined by the DEP shall be applied to transient non-community (TNC) and non-transient non-community (NTNC) wells when there is no metered rate of withdrawal or no approved pumping rate. The default Zone I radius shall be 100 feet for TNC wells and 250 feet for NTNC wells.
ZONE II: Means that area of an aquifer which contributes water to a well under the most severe pumping and recharge conditions that can be realistically anticipated (180 days of pumping at approved yield, with no recharge from precipitation). It is bounded by the groundwater divides which result from pumping the well and by the contact of the aquifer with less permeable materials such as till or bedrock. In some cases, streams or lakes may act as recharge boundaries. In all cases, Zone II shall extend upgradient to its point of intersection with prevailing hydrogeologic boundaries (a groundwater flow divide, a contact with till or bedrock).