The following terms shall have, throughout this chapter, the meanings given herein. Where a term is not defined below but is defined by Chapter
145, Subdivision and Land Development, of the Code of Lower Saucon Township, the definition from Chapter
145, Subdivision and Land Development, of the Code of Lower Saucon Township shall apply.
The removal of the surface of the land through the combined action of human activities and natural processes, at a rate greater than would occur because of the natural processes alone.
AGRICULTURAL ACTIVITYActivities associated with agriculture, such as agricultural cultivation, agricultural operation, and animal heavy use areas. This includes the work of producing crops, including tillage, land clearing, plowing, disking, harrowing, planting, harvesting crops or pasturing and raising of livestock and installation of conservation measures. Construction of new buildings or impervious area is not considered an agricultural activity.
BEST MANAGEMENT PRACTICE (BMP)Activities, facilities, measures or procedures used to manage stormwater quantity and quality impacts from the regulated activities listed in §
137-5, to meet state water quality requirements, to promote groundwater recharge and to otherwise meet the purposes of this chapter.
Densely vegetated, depressed features that store stormwater and filter it through vegetation, mulch, planting soil, etc. Ultimately, stormwater is evapotranspirated, infiltrated or discharged. Optimal bioretention areas mimic natural forest ecosystems in terms of species diversity, density, distribution, use of native plants, etc.
BUFFERA. STREAMSIDE BUFFERA zone of variable width located along a stream that is vegetated and is designed to filter pollutants from runoff.
SPECIAL GEOLOGIC FEATURE BUFFERA required isolation distance from a special geologic feature to a proposed BMP needed to reduce the risk of sinkhole formation due to stormwater management activities.
CAPTURE/REUSEStormwater management techniques, such as cisterns and rain barrels, which direct runoff into storage devices, surface or subsurface, for later reuse, such as for irrigation of gardens and other planted areas. Because this stormwater is utilized and no pollutant discharge results, water quality performance is superior to other noninfiltration BMPs.
CARBONATE BEDROCKRock consisting chiefly of carbonate minerals, such as limestone and dolomite; specifically, a sedimentary rock composed of more than 50% by weight of carbonate minerals that underlies soil or other unconsolidated, superficial material.
CISTERNA reservoir or tank for storing rainwater.
CLOSED DEPRESSIONA distinctive bowl-shaped depression in the land surface. It is characterized by internal drainage, varying magnitude and an unbroken ground surface.
COLLECTORAny watercourse, swale, pipe, culvert or other stormwater control structure receiving runoff from an upstream watershed of 40 acres or less.
CONSTRUCTED WETLANDSConstructed wetlands are similar to wet ponds (see below) and consist of a basin which provides for necessary stormwater storage as well as a permanent pool or water level, planted with wetland vegetation. To be successful, constructed wetlands must have adequate natural hydrology (both runoff inputs as well as soils and water table which allow for maintenance of a permanent pool of water). In these cases, the permanent pool must be designed carefully, usually with shallow edge benches, so that water levels are appropriate to support carefully selected wetland vegetation.
CULVERTA pipe, conduit or similar structure, including appurtenant works, which carries surface water.
DAMAn artificial barrier, together with its appurtenant works, constructed for the purpose of impounding or storing water or another fluid or semifluid or a refuse bank, fill or structure for highway, railroad or other purposes, which does or may impound water or another fluid or semifluid.
DEPThe Pennsylvania Department of Environmental Protection (formerly the "Pennsylvania Department of Environmental Resources").
DESIGN STORMThe depth and time distribution of precipitation from a storm event measured in probability of occurrence (e.g., 100-year storm) and duration (e.g., twenty-four-hour) and used in computing stormwater management control systems.
DETENTION BASINA basin designed to retard stormwater runoff by temporarily storing the runoff and releasing it at a predetermined rate.
DEVELOPERA person, partnership, association, corporation or other entity, or any responsible person therein or agent thereof, that undertakes any regulated activity of this chapter.
DIRECT RECHARGE/SUBSURFACE BMPA BMP designed to direct runoff to groundwater recharge without providing for vegetative uptake. Examples include infiltration trenches, seepage beds, dry wells and stormwater drainage wells such that nearly all runoff becomes recharge to groundwater.
DRAINAGE EASEMENTA right granted by a landowner to a grantee, allowing the use of private land for stormwater management purposes.
DRAINAGE PLANThe documentation of the proposed stormwater quantity and quality management controls to be used for a given development site, including a BMP operations and maintenance plan, the contents of which are established in §
137-26.
A construction or other human activity which disturbs the surface of the land, including but not limited to clearing and grubbing, grading, excavations, embankments, road maintenance, building construction and the moving, depositing, stockpiling or storing of soil, rock or earth materials.
EROSIONThe removal of soil particles by the action of water, wind, ice, or other geological agents.
EXISTING USESThose uses actually attained in the water body on or after November 28, 1975, whether or not they are included in the water quality standards. (25 Pa. Code §
93.1).
Man-made deposits of natural soils or rock products and waste materials.
FREEBOARDThe incremental depth in a stormwater management structure, provided as a safety factor of design, above that required to convey or control the design runoff event.
HARDSHIP WAIVER REQUESTA written request for a waiver alleging that the provisions of this chapter inflict unnecessary hardship upon the developer. A hardship waiver does not apply to and is not available from the water quality provisions of this chapter and should not be granted.
HOT SPOT LAND USESA land use or activity that generates higher concentrations of hydrocarbons, trace metals or other toxic substances than typically found in stormwater runoff. These land uses are listed in § 137-15K.
HYDROLOGIC SOIL GROUP (HSG)Soils are classified into four HSGs (A, B, C and D) to indicate the minimum infiltration rates, which are obtained for bare soil after prolonged wetting. The Natural Resources Conservation Service (NRCS) of the U.S. Department of Agriculture defines the four groups and provides a list of most of the soils in the United States and their group classification. The soils in the area of the development site may be identified from a soil survey report that can be obtained from local NRCS offices or conservation district offices. Soils become less permeable as the HSG varies from A to D.
INFILTRATION PRACTICEA practice designed to direct runoff into the ground, i.e., french drain, seepage pit, seepage trench or bioretention area.
INTERCEPTORAny watercourse swale, pipe, culvert or other stormwater control structure receiving stormwater runoff from an upstream watershed of over 40 acres.
KARSTA type of topography or landscape characterized by surface depressions, sinkholes, rock pinnacles and an uneven bedrock structure, underground drainage and caves. Karst is usually formed on carbonate rocks, such as limestones or dolomites and sometimes gypsum.
LAND DEVELOPMENTAny of the following activities:
A. The improvement of one lot or two or more contiguous lots, tracts or parcels of land for any purpose involving:
(1) A group of two or more residential or nonresidential buildings, whether proposed initially or cumulatively, or a single nonresidential building on a lot or lots regardless of the number of occupants or tenure; or
The division or allocation of land or space, whether initially or cumulatively, between or among two or more existing or prospective occupants by means of, or for the purpose of streets, common areas, leaseholds, condominiums, building groups or other features.
Development in accordance with Section 503(1.1) of the MPC.
LOADING RATEThe ratio of the land area draining to the system, as modified by the weighting factors in §
137-14B, compared to the base area of the infiltration system.
A development approach that promotes practices that will minimize post-development runoff rates and volumes thereby minimizing needs for artificial conveyance and storage facilities. Site design practices include preserving natural drainage features, minimizing impervious surface area, reducing the hydraulic connectivity of impervious surfaces and protecting natural depression storage.
MAINSTEM (MAIN CHANNEL)Any stream segment or other conveyance in a Dual Release Rate or Condition No Detention I Subarea used as a reach in the Catasauqua Creek study area hydrologic model. In Conditional No Detention II Subareas, the main channel is the Lehigh River.
MANNING EQUATION (MANNING FORMULA)A method for calculation of velocity of flow (e.g., feet per second) and flow rate (e.g., cubic feet per second) in open channels based upon channel shape, roughness, depth of flow and slope. "Open channels" may include closed conduits so long as the flow is not under pressure.
MARYLAND STORMWATER DESIGN MANUALA stormwater design manual written by the Maryland Department of the Environment and the Center for Watershed Protection. As of November 2006, the Manual can be obtained through the following website: www.mde.state.md.us.
MINIMUM DISTURBANCE/MINIMUM MAINTENANCE PRACTICES (MD/MM)Site design practices in which careful limits are placed on site clearance prior to development allowing for maximum retention of existing vegetation (woodlands and other), minimum disturbance and compaction of existing soil mantle and minimum site application of chemicals post-development. Typically, MD/MM includes disturbance setback criteria from buildings as well as related site improvements, such as walkways, driveways, roadways and any other improvements. These criteria may vary by community context as well as by type of development being proposed. Additionally, MD/MM also shall include provisions (e.g., deed restrictions, conservation easements) to protect these areas from future disturbance and from application of fertilizers, pesticides and herbicides.
NO-HARM RUNOFF QUANTITY OPTIONThe option of using a less restrictive runoff quantity control if it can be shown that adequate and safe runoff conveyance exists and that the less restrictive control would not adversely affect health, safety and property.
NPDESNational Pollutant Discharge Elimination System.
NRCSNatural Resource Conservation Service, U.S. Department of Agriculture (formerly the "Soil Conservation Service").
OIL/WATER SEPARATORA structural mechanism designed to remove free oil and grease (and possibly solids) from stormwater runoff.
OUTFALL"Point source," as described in 40 CFR
122.2, at the point where the municipality's storm sewer system discharges to surface waters of the commonwealth.
One with an interest in and often dominion over a property.
PEAK DISCHARGEThe maximum rate of flow of stormwater runoff at a given location and time resulting from a specified storm event.
PENN STATE RUNOFF MODEL (PSRM)The computer-based hydrologic modeling technique adapted to each watershed for the Act 167 Plans. The model was calibrated to reflect actual flow values by adjusting key model input parameters.
PERSONAn individual, partnership, public or private association or corporation, firm, trust, estate, municipality, governmental unit, public utility or any other legal entity whatsoever which is recognized by law as the subject of rights and duties.
POINT SOURCEAny discernible, confined and discrete conveyance, including but not limited to any pipe, ditch, channel, tunnel or conduit from which stormwater is or may be discharged, as defined in state regulations at 25 Pa. Code §
92.1.
Measures implemented for hot spot land uses designed to reduce the concentration of hydrocarbons, trace metals and other toxic substances to levels typically found in stormwater runoff.
PRELIMINARY SITE INVESTIGATIONThe determination of the depth to bedrock, the depth to the seasonal high water table and the soil permeability for a possible infiltration location on a site through the use of published data and on-site surveys. In carbonate bedrock areas, the location of special geologic features must also be determined along with the associated buffer distance to the possible infiltration practice. See Appendix G.
PUBLIC WATER SYSTEMA system which provides water to the public for human consumption which has at least 15 service connections or regularly serves an average of at least 25 individuals daily at least 60 days out of the year (see 25 Pa. Code Chapter
109).
A method of peak runoff calculation using a standardized runoff coefficient (rational "c"), acreage of tract and rainfall intensity determined by return period and by the time necessary for the entire tract to contribute runoff. The Rational Method formula is stated as follows: Q = ciA, where "Q" is the calculated peak flow rate in cubic feet per second, "c" is the dimensionless runoff coefficient (see Appendix C), "i" is the rainfall intensity in inches per hour, and "A" is the area of the tract in acres.
REACHAny of the natural or man-made runoff conveyance channels used for watershed runoff modeling purposes to connect the subareas and transport flows downstream.
RECHARGE VOLUME (REV)The portion of the water quality volume (WQv) used to maintain groundwater recharge rates at development sites. (See §
137-14J).
All activities that may affect stormwater runoff, including land development and earth disturbance activity, which are subject to regulation by this chapter.
RELEASE RATEThe percentage of the predevelopment peak rate of runoff for a development site to which the post-development peak rate of runoff must be controlled to avoid peak flow increases throughout the watershed.
RETURN PERIODAn expression of the intensity of an event based on its statistical chance of being equaled or exceeded in any given year. An event with a 1% chance in any given year is stated to have a 100-year return period. An event with a 50% chance is stated to have a two-year return period. Over a very long period of record, events might be expected to recur on average in accordance with their return period.
ROAD MAINTENANCEEarth disturbance activities within the existing road cross section, such as grading and repairing existing unpaved road surfaces, cutting road banks, cleaning or clearing drainage ditches and other similar activities.
RUNOFFThat part of precipitation which flows over the land.
RUNOFF BMPA BMP designed for essentially the full volume of runoff entering the BMP to be discharged off-site.
SALDOThe current (or otherwise applicable) version of Chapter
145, Subdivision and Land Development, of the Code of Lower Saucon Township.
The former Soil Conservation Service, U.S. Department of Agriculture, now known as the "NRCS."
SEDIMENT TRAPS/CATCH BASIN SUMPSChambers which provide storage below the outlet in a storm inlet to collect sediment, debris and associated pollutants, typically requiring periodic cleanout.
SEEPAGE PIT/SEEPAGE TRENCHAn area of excavated earth filled with loose stone or similar material and into which surface water is directed for infiltration into the ground.
SEPARATE STORM SEWER SYSTEMA conveyance or system of conveyances (including roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels or storm drains) primarily used for collecting and conveying stormwater runoff.
SHEET FLOWStormwater runoff flowing in a thin layer over the ground surface.
SOIL COVER COMPLEX METHODA method of runoff computation developed by NRCS which is based upon relating soil type and land use/cover to a runoff parameter called a "curve number."
SPECIAL GEOLOGIC FEATURESCarbonate bedrock features, including, but not limited to, closed depressions, existing sinkholes, fracture traces, lineaments, joints, faults, caves, pinnacles and geologic contacts between carbonate and noncarbonate bedrock, which may exist and must be identified on a site when stormwater management BMPs are being considered.
STATE WATER QUALITY REQUIREMENTSAs defined under state regulations protection of designated and existing uses (see 25 Pa. Code Chapters
93 and
96), including:
A. Each stream segment in Pennsylvania has a designated use, such as cold water fish or potable water supply, which is listed in 25 Pa. Chapter 93. These uses must be protected and maintained under state regulations.
"Existing uses" are those attained as of November 1975, regardless whether they have been designated in 25 Pa. Code Chapter
93. Regulated earth disturbance activities must be designed to protect and maintain existing uses and maintain the level of water quality necessary to protect those uses in all streams, and to protect and maintain water quality in special protection streams.
Water quality involves the chemical, biological and physical characteristics of surface water bodies. After regulated earth disturbance activities are complete, these characteristics can be impacted by addition of pollutants, such as sediment, and changes in habitat through increased flow volumes and/or rates as a result of changes in land surface area from those activities. Therefore, permanent discharges to surface waters must be managed to protect the stream bank, streambed and structural integrity of the waterway to prevent these impacts.
STORAGE INDICATION METHODA method of routing or moving inflow hydrograph through a reservoir or detention structure. The method solves the mass conservation equation to determine an outflow hydrograph as it leaves the storage facility.
STORM DRAINAGE PROBLEM AREASAreas which lack adequate stormwater collection and/or conveyance facilities and which present a hazard to persons or property. These areas are either documented in Appendix B of this chapter or identified by the Township or Township Engineer.
STORM SEWERA system of pipes or other conduits which carries intercepted surface runoff, street water and other wash waters, or drainage, but excludes domestic sewage and industrial wastes.
STORMWATERThe surface runoff generated by precipitation reaching the ground surface.
STORMWATER DRAINAGE WELLSWells for injection of stormwater to the subsurface that are regulated by the U.S. Environmental Protection Agency to protect underground sources of drinking water.
STORMWATER FILTERSAny number of structural mechanisms, such as multichamber catch basins, sand/peat filters, sand filters, and so forth, which are installed to intercept stormwater flow and remove pollutants prior to discharge. Typically, these systems require periodic maintenance and cleanout.
STORMWATER MANAGEMENT FACILITIESAll facilities and features, such as infiltration practices, pipes, catch basins, inlets, culverts, open channels, ditches, swales, stormwater detention facilities, etc., used to transmit, infiltrate, or temporarily store surface water runoff.
STORMWATER MANAGEMENT PLANAny plan for managing stormwater runoff adopted by Northampton County for a watershed as required by the Act of October 4, 1978, P.L. 864 (Act 167), and known as the "Storm Water Management Act."
SUBAREAThe smallest unit of watershed breakdown for hydrologic modeling purposes for which the runoff control criteria have been established in the stormwater management plan.
SURFACE WATERSPerennial and intermittent streams, rivers, lakes, reservoirs, ponds, wetlands, springs, natural seeps and estuaries, excluding water at facilities approved for wastewater treatment such as wastewater treatment impoundments, cooling water ponds and constructed wetlands used as part of a wastewater treatment process.
SWALEA low-lying stretch of natural or man-made land which gathers or carries surface water runoff. See also "vegetated swale."
TIMBER HARVESTING ACTIVITIESEarth disturbance activities, including the construction of skid trails, logging roads, landing areas and other similar logging or silvicultural practices.
TOWNSHIPLower Saucon Township, Northampton County, Pennsylvania.
TRASH/DEBRIS COLLECTORSRacks, screens or other similar devices installed in a storm drainage system to capture coarse pollutants trash, leaves, etc.
VEGETATED BUFFERSGently sloping areas that convey stormwater as sheet flow over a broad, densely vegetated earthen area, possibly coupled with the use of level spreading devices. As water quality BMPs, vegetated buffers serve to filter pollutants from runoff and promote infiltration. Vegetated buffers should be situated on minimally disturbed soils and have low flow velocities and extended residence times. Vegetated buffers may be, but are not restricted to, use in riparian (streamside) conditions.
VEGETATED ROOFSVegetated systems installed on roofs that generally consist of a waterproof layer, a root-barrier, drainage layer (optional), growth media, and suitable vegetation. Vegetated roofs store and eventually evapotranspirate the collected rooftop rainfall; overflows may be provided for larger storms.
VEGETATED SWALESVegetated earthen channels designed to convey and possibly treat stormwater. As water quality BMPs, these are broad, shallow, densely vegetated, earthen channels designed to treat stormwater through infiltration, evapotranspiration and sedimentation. Swales should be gently sloping with low flow velocities to prevent erosion. Check dams may be added to enhance performance.
VEGETATED/SURFACE BMPA BMP designed to provide vegetative uptake and soil renovation or surface infiltration of runoff. Capture/reuse BMPs are included if the captured runoff is applied to vegetated areas. Examples include bioretention and surface infiltration basins.
WATER QUALITY INSERTSAny number of commercially available devices that are inserted into storm inlets to capture sediment, oil, grease, metals, trash, debris, etc.
WATER QUALITY VOLUME (WQv)The increase in runoff volume on a development site associated with a two-year, twenty-four-hour storm event.
WATERCOURSEAny channel or conveyance of surface water having defined bed and banks, whether natural or artificial, with perennial or intermittent flow.
WATERS OF THE COMMONWEALTHAny and all rivers, streams, creeks, rivulets, impoundments, ditches, watercourses, storm sewers, lakes, dammed water, wetlands, ponds, springs and all other bodies or channels of conveyance of surface water, or parts thereof, whether natural or artificial, within or on the boundaries of this commonwealth.
WATERSHEDThe entire region or area drained by a river or other body of water, whether natural or artificial.
WET DETENTION PONDSA basin that provides for necessary stormwater storage as well as a permanent pool of water. To be successful, wet ponds must have adequate natural hydrology (both runoff inputs as well as soils and water table which allow for maintenance of a permanent pool of water) and must be able to support a healthy aquatic community so as to avoid creation of mosquito and other health and nuisance problems.